Arrhythmias — MCQs

Q: Match the following A. Atrial fibrillation B. Atrial flutter C. PSVT D. Ventricular tachycardia

A-2, B-1, C-3, D-4. ***A-2, B-1, C-3, D-4*** - Image 2 shows irregularly irregular QRS complexes with no discernible P waves, which is characteristic of **atrial fibrillation**. - Image 1 shows a "sawtooth" pattern of atrial activity, indicative of **atrial flutter**. - Image 3 displays a narrow complex tachycardia with a very regular rhythm, consistent with **PSVT**. - Image 4 demonstrates wide, regular QRS complexes without clear P waves, which is the hallmark of **ventricular tachycardia**. *A-1, B-2, C-3, D-4* - This option incorrectly matches atrial fibrillation with the "sawtooth" pattern (image 1) and atrial flutter with the irregularly irregular rhythm (image 2). - Atrial fibrillation is characterized by the absence of discrete P waves and irregular ventricular response (image 2), while atrial flutter shows organized atrial activity with a "sawtooth" pattern (image 1). *A-1, B-2, C-4, D-3* - This option misidentifies image 1 as atrial fibrillation and image 2 as atrial flutter, which are reversed. - It also incorrectly matches PSVT with image 4 (ventricular tachycardia) and ventricular tachycardia with image 3 (PSVT). *A-2, B-1, C-4, D-3* - This option correctly identifies atrial fibrillation (A-2) and atrial flutter (B-1), but incorrectly swaps the ventricular and supraventricular tachycardias. - Image 3 shows narrow complex tachycardia (PSVT), not the wide complex pattern of ventricular tachycardia seen in image 4. *A-4, B-3, C-2, D-1* - This option incorrectly matches all the rhythms to the wrong images, demonstrating a fundamental misunderstanding of their characteristic ECG features. - For example, it matches atrial fibrillation to image 4 (ventricular tachycardia) and ventricular tachycardia to image 1 (atrial flutter).

Q: A patient is pulseless with the following rhythm shown in the ECG. What is the next best step in management?

Defibrillate and continue chest compression. ***Defibrillate and continue chest compression*** - This scenario describes a **pulseless ventricular tachycardia (pVT)**, which is a **shockable rhythm**. - Immediate defibrillation is crucial, followed by resuming **chest compressions** without delay, as per advanced cardiac life support (ACLS) guidelines. - The correct sequence is: shock → immediate CPR for 2 minutes → rhythm/pulse check. *Defibrillate and check pulse* - While defibrillation is the correct initial intervention for a shockable rhythm, checking the pulse immediately after is incorrect. - Chest compressions should be resumed immediately after a shock for 2 minutes before stopping to check a pulse. - Minimizing interruptions in chest compressions is critical for survival. *Check pulse and give synchronized DC* - Checking a pulse before any intervention wastes critical time in a pulseless patient with a shockable rhythm; immediate defibrillation is indicated. - Synchronized direct current (DC) cardioversion is used for unstable patients **with a pulse** (e.g., unstable ventricular tachycardia with a pulse), not for pulseless rhythms. *Give synchronized DC and continue chest compressions* - Synchronized DC cardioversion is inappropriate for a **pulseless rhythm**; unsynchronized defibrillation is required. - Synchronization requires an R wave to time the shock, which is not feasible in pulseless VT management. *Start chest compressions and give epinephrine* - While chest compressions are essential, the **immediate priority** for a shockable rhythm (pVT/VF) is **defibrillation**. - Epinephrine is given during CPR cycles (after the first shock), but defibrillation must come first for shockable rhythms. - This would be the approach for **non-shockable rhythms** (PEA/asystole), not pulseless VT.

Q: Match the following ECG findings (1-4) with their corresponding arrhythmias (A-D): 1. Sawtooth pattern in leads II, III, aVF with regular ventricular response 2. Irregularly irregular rhythm with absent P waves 3. Narrow QRS tachycardia with abrupt onset/termination 4. Wide QRS tachycardia with AV dissociation A. Atrial fibrillation B. PSVT (Paroxysmal Supraventricular Tachycardia) C. Atrial flutter D. Ventricular tachycardia What is the correct matching?

A-2, B-3, C-1, D-4. The correct matching is **A-2, B-3, C-1, D-4**: ***C-1: Atrial flutter - Sawtooth pattern*** - Atrial flutter is characterized by a **sawtooth pattern** of flutter waves, particularly prominent in leads II, III, and aVF - Represents rapid, organized atrial depolarization at 250-350 bpm - Regular ventricular response due to **AV block** (commonly 2:1 or 4:1) - The sawtooth pattern is the pathognomonic feature ***A-2: Atrial fibrillation - Irregularly irregular rhythm*** - Identified by an **irregularly irregular rhythm** with absent distinct P waves - Replaced by chaotic fibrillatory waves showing disorganized atrial activity - Ventricular rate is rapid and unpredictable - No organized atrial pattern unlike the regular flutter waves ***B-3: PSVT - Narrow QRS with abrupt onset/termination*** - Presents with **narrow QRS complex tachycardia** (QRS 0.12 seconds) - **AV dissociation** is a key diagnostic feature showing independent atrial and ventricular activity - Originates from ventricular tissue, not supraventricular structures - Lacks the organized P wave patterns seen in atrial arrhythmias

Q: A 45-year-old male is brought into the emergency department by emergency medical services. The patient has a history of substance abuse and was found down in his apartment lying on his right arm. He was last seen 24 hours earlier by his mother who lives in the same building. He is disoriented and unable to answer any questions. His vitals are HR 48, T 97.6, RR 18, BP 100/75. You decide to obtain an EKG as shown in Figure 1. Which of the following is most likely the cause of this patient's EKG results?

Hyperkalemia. ***Hyperkalemia*** - This patient's presentation with **bradycardia**, potential **rhabdomyolysis** from being "found down" and immobility, and the EKG showing changes like **peaked T waves** (often the first EKG sign) are all highly suggestive of hyperkalemia. - Prolonged immobility (lying on arm for 24 hours) can lead to **muscle breakdown**, releasing significant intracellular potassium into the bloodstream. *Hypocalcemia* - Hypocalcemia typically manifests on EKG as **QT interval prolongation**, not peaked T waves or bradycardia. - While some forms of muscle injury can affect calcium, it's not the primary EKG finding expected with rhabdomyolysis. *Hypercalcemia* - Hypercalcemia is associated with a **shortened QT interval** on EKG. - It is unlikely to cause severe bradycardia or marked T wave changes as seen in profound hyperkalemia. *Hypomagnesemia* - Hypomagnesemia can cause various EKG changes, including **QT prolongation** and an increased risk of **torsades de pointes**, but not typically the peaked T waves characteristic of this scenario. - It often coexists with hypokalemia but isn't the primary explanation for the EKG findings described. *Hypokalemia* - Hypokalemia is associated with **flattened T waves**, prominent **U waves**, and often **QT prolongation** as well as various arrhythmias. - It is highly unlikely to cause the **peaked T waves** and **bradycardia** observed in this patient.

Q: A 52-year-old woman presents with decreased exercise tolerance and difficulty breathing on exertion and while sleeping at night. She says that she requires 2 pillows to sleep at night to alleviate her shortness of breath. These symptoms started 6 months ago and are gradually increasing in severity. She does not have any chronic health problems. She has smoked 15 cigarettes per day for the past 20 years and drinks alcohol occasionally. Vital signs include: blood pressure 110/70 mm Hg, temperature 36.7°C (98.0°F), and regular pulse 90/min. On physical examination, the first heart sound is loud, and there is a low pitched rumbling murmur best heard at the cardiac apex. This patient is at high risk of developing which of the following complications?

Cardiac arrhythmia. ***Cardiac arrhythmia*** - The patient's symptoms, including **paroxysmal nocturnal dyspnea**, **orthopnea**, **exertional dyspnea**, and an apical **low-pitched rumbling diastolic murmur** with a **loud S1**, are highly suggestive of **mitral stenosis**. - **Mitral stenosis** leads to increased **left atrial pressure** and progressive **left atrial enlargement**, making the left atrium particularly vulnerable to developing **atrial fibrillation**, which is the **most common complication** occurring in 30-40% of patients. - Atrial fibrillation can cause palpitations, worsen heart failure symptoms, and significantly increase stroke risk. *Infective endocarditis* - While patients with **mitral stenosis** have an increased risk of endocarditis, this is a less common complication compared to atrial fibrillation. - There are no signs of active infection such as fever, new murmur changes, or systemic inflammatory response in this presentation. *Systemic thromboembolism* - **Thromboembolism** is a serious complication of mitral stenosis, particularly when complicated by atrial fibrillation, but the **left atrial enlargement** and stasis that predispose to arrhythmias occur first. - Without established atrial fibrillation, the immediate risk of arrhythmia development is higher than thromboembolic events. *Pulmonary hypertension* - **Pulmonary hypertension** develops as a consequence of chronic elevation in left atrial pressure transmitting back to the pulmonary vasculature. - While this is a recognized complication, it typically develops later in the disease course, and **atrial fibrillation** remains the most common complication. *Right heart failure* - **Right heart failure** can occur secondary to pulmonary hypertension from long-standing mitral stenosis. - This represents a later-stage complication, whereas atrial arrhythmias occur earlier and more frequently in the natural history of mitral stenosis.

Match the following ECG findings (1-4) with their corresponding arrhythmias (A-D): 1. Sawtooth pattern in leads II, III, aVF with regular ventricular response 2. Irregularly irregular rhythm with absent P waves 3. Narrow QRS tachycardia with abrupt onset/termination 4. Wide QRS tachycardia with AV dissociation A. Atrial fibrillation B. PSVT (Paroxysmal Supraventricular Tachycardia) C. Atrial flutter D. Ventricular tachycardia What is the correct matching?

A 45-year-old male is brought into the emergency department by emergency medical services. The patient has a history of substance abuse and was found down in his apartment lying on his right arm. He was last seen 24 hours earlier by his mother who lives in the same building. He is disoriented and unable to answer any questions. His vitals are HR 48, T 97.6, RR 18, BP 100/75. You decide to obtain an EKG as shown in Figure 1. Which of the following is most likely the cause of this patient's EKG results?

A previously healthy 22-year-old woman comes to the emergency department because of several episodes of palpitations that began a couple of days ago. The palpitations are intermittent in nature, with each episode lasting 5–10 seconds. She states that during each episode she feels as if her heart is going to “spin out of control.” She has recently been staying up late to study for her final examinations. She does not drink alcohol or use illicit drugs. She appears anxious. Her temperature is 37°C (98.6°F), pulse is 75/min, and blood pressure is 110/75 mm Hg. Physical examination shows no abnormalities. An ECG is shown. Which of the following is the most appropriate next step in management?

A 23-year-old patient who has recently found out she was pregnant presents to her physician for her initial prenatal visit. The estimated gestational age is 10 weeks. Currently, the patient complains of recurrent palpitations. She is gravida 1 para 0 with no history of any major diseases. On examination, the blood pressure is 110/60 mm Hg heart rate, heart rate 94/min irregular, respiratory rate 12/min, and temperature 36.4°C (97.5°F). Her examination is significant for an opening snap before S2 and diastolic decrescendo 3/6 murmur best heard at the apex. No venous jugular distension or peripheral edema is noted. The patient’s electrocardiogram (ECG) is shown in the image. Cardiac ultrasound reveals the following parameters: left ventricular wall thickness 0.4 cm, septal thickness 1 cm, right ventricular wall thickness 0.5 cm, mitral valve area 2.2 cm2, and tricuspid valve area 4.1 cm2. Which of the following statements regarding this patient’s management is correct?

A 52-year-old woman presents with decreased exercise tolerance and difficulty breathing on exertion and while sleeping at night. She says that she requires 2 pillows to sleep at night to alleviate her shortness of breath. These symptoms started 6 months ago and are gradually increasing in severity. She does not have any chronic health problems. She has smoked 15 cigarettes per day for the past 20 years and drinks alcohol occasionally. Vital signs include: blood pressure 110/70 mm Hg, temperature 36.7°C (98.0°F), and regular pulse 90/min. On physical examination, the first heart sound is loud, and there is a low pitched rumbling murmur best heard at the cardiac apex. This patient is at high risk of developing which of the following complications?

A 63-year-old woman is brought to the emergency department 1 hour after the onset of right-sided weakness. She was eating breakfast when suddenly she could not lift her spoon. She cried out to her husband but her speech was slurred. For the past 4 months, she has been more anxious than usual and felt fatigued. She used to exercise regularly but had to give up her exercise routine 3 months ago because of lightheadedness and shortness of breath with exertion. She has a history of hypertension. She is a tax accountant and has had increased stress at work recently. She takes lisinopril daily and alprazolam as needed. Her temperature is 37.2°C (99.0°F), pulse is 138/min, respirations are 14/min, and blood pressure is 146/86 mm Hg. Her lungs are clear to auscultation bilaterally and she has an S1 with variable intensity. On neurologic examination, she has a right facial droop and 2/5 strength in the right shoulder, elbow, wrist, and fingers. Sensation is diminished in the right face and arm. Further evaluation is most likely to show which of the following?

Q10

Two days after an uncomplicated laparoscopic abdominal hernia repair, a 46-year-old man is evaluated for palpitations. He has a history of hypertension, type 2 diabetes mellitus, and a ventricular septal defect that closed spontaneously as a child. His father has coronary artery disease. Prior to admission, his only medications were hydrochlorothiazide and metformin. He currently also takes hydromorphone/acetaminophen for mild postoperative pain. He is 180 cm (5 ft 11 in) tall and weighs 100 kg (220 lb); BMI is 30.7 kg/m2. His temperature is 37.0°C (99°F), blood pressure is 139/85 mmHg, pulse is 75/min and irregular, and respirations are 14/min. Cardiopulmonary examination shows a normal S1 and S2 without murmurs and clear lung fields. The abdominal incisions are clean, dry, and intact. There is mild tenderness to palpation over the lower quadrants. An electrocardiogram is obtained and shown below. Which of the following is the most likely cause of this patient's ECG findings?

Arrhythmias US Medical PG Practice Questions and MCQs

Question 1: Match the following A. Atrial fibrillation B. Atrial flutter C. PSVT D. Ventricular tachycardia

A. A-1, B-2, C-3, D-4
B. A-2, B-1, C-3, D-4 (Correct Answer)
C. A-1, B-2, C-4, D-3
D. A-4, B-3, C-2, D-1
E. A-2, B-1, C-4, D-3

Explanation: ***A-2, B-1, C-3, D-4*** - Image 2 shows irregularly irregular QRS complexes with no discernible P waves, which is characteristic of **atrial fibrillation**. - Image 1 shows a "sawtooth" pattern of atrial activity, indicative of **atrial flutter**. - Image 3 displays a narrow complex tachycardia with a very regular rhythm, consistent with **PSVT**. - Image 4 demonstrates wide, regular QRS complexes without clear P waves, which is the hallmark of **ventricular tachycardia**. *A-1, B-2, C-3, D-4* - This option incorrectly matches atrial fibrillation with the "sawtooth" pattern (image 1) and atrial flutter with the irregularly irregular rhythm (image 2). - Atrial fibrillation is characterized by the absence of discrete P waves and irregular ventricular response (image 2), while atrial flutter shows organized atrial activity with a "sawtooth" pattern (image 1). *A-1, B-2, C-4, D-3* - This option misidentifies image 1 as atrial fibrillation and image 2 as atrial flutter, which are reversed. - It also incorrectly matches PSVT with image 4 (ventricular tachycardia) and ventricular tachycardia with image 3 (PSVT). *A-2, B-1, C-4, D-3* - This option correctly identifies atrial fibrillation (A-2) and atrial flutter (B-1), but incorrectly swaps the ventricular and supraventricular tachycardias. - Image 3 shows narrow complex tachycardia (PSVT), not the wide complex pattern of ventricular tachycardia seen in image 4. *A-4, B-3, C-2, D-1* - This option incorrectly matches all the rhythms to the wrong images, demonstrating a fundamental misunderstanding of their characteristic ECG features. - For example, it matches atrial fibrillation to image 4 (ventricular tachycardia) and ventricular tachycardia to image 1 (atrial flutter).

Question 2: A patient with a history of hypertension presents with atrial fibrillation, shortness of breath, and bilateral basal crackles on auscultation. Which of the following would be the least important in the management of this patient?

A. Start on anticoagulants
B. Start β-blocker
C. Cardioversion to correct rhythm if hemodynamically remains unstable even after medical management
D. IV Digoxin for control rate (Correct Answer)
E. Administer diuretics for fluid overload

Explanation: ***IV Digoxin for control rate*** - While **Digoxin** can be used for **rate control in atrial fibrillation**, its role is limited, especially in patients with **congestive heart failure** due to its delayed onset of action and narrow therapeutic window. - In a patient with **shortness of breath** and **bilateral basal crackles** (suggesting acute decompensated heart failure), rapid rate control with a **β-blocker** or **calcium channel blocker** is usually preferred for immediate symptom relief. - Digoxin is not first-line therapy in this acute setting and is therefore the **least important** among the management options listed. *Start on anticoagulants* - **Anticoagulation** is crucial for patients with **atrial fibrillation** to prevent **thromboembolic events**, particularly strokes. - Given the patient's history of **hypertension** and presence of **atrial fibrillation**, their **CHA2DS2-VASc score** is likely elevated, necessitating anticoagulation. *Start β-blocker* - **Beta-blockers** are first-line agents for **rate control in atrial fibrillation**, especially in patients with **hypertension** and signs of **heart failure**. - They effectively reduce ventricular response rate, improve diastolic filling, and can alleviate symptoms like **shortness of breath**. *Cardioversion to correct rhythm if hemodynamically remains unstable even after medical management* - If a patient with **atrial fibrillation** and signs of **heart failure** remains **hemodynamically unstable** despite initial medical management (e.g., rate control, diuretics), **cardioversion** (electrical or pharmacological) is an essential intervention to restore sinus rhythm. - This can acutely improve cardiac output and resolve symptoms of **decompensated heart failure**. *Administer diuretics for fluid overload* - **Diuretics** (e.g., furosemide) are essential for managing the **volume overload** in this patient, as evidenced by **bilateral basal crackles** and **shortness of breath**. - Reducing preload helps improve **pulmonary congestion** and alleviates acute heart failure symptoms. - Loop diuretics are a cornerstone of acute decompensated heart failure management.

Question 3: A patient is pulseless with the following rhythm shown in the ECG. What is the next best step in management?

A. Defibrillate and continue chest compression (Correct Answer)
B. Defibrillate and check pulse
C. Check pulse and give synchronized DC
D. Give synchronized DC and continue chest compressions
E. Start chest compressions and give epinephrine

Explanation: ***Defibrillate and continue chest compression*** - This scenario describes a **pulseless ventricular tachycardia (pVT)**, which is a **shockable rhythm**. - Immediate defibrillation is crucial, followed by resuming **chest compressions** without delay, as per advanced cardiac life support (ACLS) guidelines. - The correct sequence is: shock → immediate CPR for 2 minutes → rhythm/pulse check. *Defibrillate and check pulse* - While defibrillation is the correct initial intervention for a shockable rhythm, checking the pulse immediately after is incorrect. - Chest compressions should be resumed immediately after a shock for 2 minutes before stopping to check a pulse. - Minimizing interruptions in chest compressions is critical for survival. *Check pulse and give synchronized DC* - Checking a pulse before any intervention wastes critical time in a pulseless patient with a shockable rhythm; immediate defibrillation is indicated. - Synchronized direct current (DC) cardioversion is used for unstable patients **with a pulse** (e.g., unstable ventricular tachycardia with a pulse), not for pulseless rhythms. *Give synchronized DC and continue chest compressions* - Synchronized DC cardioversion is inappropriate for a **pulseless rhythm**; unsynchronized defibrillation is required. - Synchronization requires an R wave to time the shock, which is not feasible in pulseless VT management. *Start chest compressions and give epinephrine* - While chest compressions are essential, the **immediate priority** for a shockable rhythm (pVT/VF) is **defibrillation**. - Epinephrine is given during CPR cycles (after the first shock), but defibrillation must come first for shockable rhythms. - This would be the approach for **non-shockable rhythms** (PEA/asystole), not pulseless VT.

Question 4: Match the following ECG findings (1-4) with their corresponding arrhythmias (A-D): 1. Sawtooth pattern in leads II, III, aVF with regular ventricular response 2. Irregularly irregular rhythm with absent P waves 3. Narrow QRS tachycardia with abrupt onset/termination 4. Wide QRS tachycardia with AV dissociation A. Atrial fibrillation B. PSVT (Paroxysmal Supraventricular Tachycardia) C. Atrial flutter D. Ventricular tachycardia What is the correct matching?

A. A-2, B-1, C-3, D-4
B. A-1, B-2, C-4, D-3
C. A-2, B-3, C-1, D-4 (Correct Answer)
D. A-4, B-3, C-2, D-1
E. A-1, B-2, C-3, D-4

Explanation: The correct matching is **A-2, B-3, C-1, D-4**: ***C-1: Atrial flutter - Sawtooth pattern*** - Atrial flutter is characterized by a **sawtooth pattern** of flutter waves, particularly prominent in leads II, III, and aVF - Represents rapid, organized atrial depolarization at 250-350 bpm - Regular ventricular response due to **AV block** (commonly 2:1 or 4:1) - The sawtooth pattern is the pathognomonic feature ***A-2: Atrial fibrillation - Irregularly irregular rhythm*** - Identified by an **irregularly irregular rhythm** with absent distinct P waves - Replaced by chaotic fibrillatory waves showing disorganized atrial activity - Ventricular rate is rapid and unpredictable - No organized atrial pattern unlike the regular flutter waves ***B-3: PSVT - Narrow QRS with abrupt onset/termination*** - Presents with **narrow QRS complex tachycardia** (QRS < 0.12 seconds) with regular rhythm - Atrial rate usually 150-250 bpm - **Abrupt onset and termination** is the characteristic feature differentiating it from other supraventricular arrhythmias - P waves may be hidden within or immediately after QRS complexes ***D-4: Ventricular tachycardia - Wide QRS with AV dissociation*** - Defined by **wide QRS complex tachycardia** (QRS > 0.12 seconds) - **AV dissociation** is a key diagnostic feature showing independent atrial and ventricular activity - Originates from ventricular tissue, not supraventricular structures - Lacks the organized P wave patterns seen in atrial arrhythmias

Question 5: A 45-year-old male is brought into the emergency department by emergency medical services. The patient has a history of substance abuse and was found down in his apartment lying on his right arm. He was last seen 24 hours earlier by his mother who lives in the same building. He is disoriented and unable to answer any questions. His vitals are HR 48, T 97.6, RR 18, BP 100/75. You decide to obtain an EKG as shown in Figure 1. Which of the following is most likely the cause of this patient's EKG results?

A. Hypocalcemia
B. Hypercalcemia
C. Hypomagnesemia
D. Hypokalemia
E. Hyperkalemia (Correct Answer)

Explanation: ***Hyperkalemia*** - This patient's presentation with **bradycardia**, potential **rhabdomyolysis** from being "found down" and immobility, and the EKG showing changes like **peaked T waves** (often the first EKG sign) are all highly suggestive of hyperkalemia. - Prolonged immobility (lying on arm for 24 hours) can lead to **muscle breakdown**, releasing significant intracellular potassium into the bloodstream. *Hypocalcemia* - Hypocalcemia typically manifests on EKG as **QT interval prolongation**, not peaked T waves or bradycardia. - While some forms of muscle injury can affect calcium, it's not the primary EKG finding expected with rhabdomyolysis. *Hypercalcemia* - Hypercalcemia is associated with a **shortened QT interval** on EKG. - It is unlikely to cause severe bradycardia or marked T wave changes as seen in profound hyperkalemia. *Hypomagnesemia* - Hypomagnesemia can cause various EKG changes, including **QT prolongation** and an increased risk of **torsades de pointes**, but not typically the peaked T waves characteristic of this scenario. - It often coexists with hypokalemia but isn't the primary explanation for the EKG findings described. *Hypokalemia* - Hypokalemia is associated with **flattened T waves**, prominent **U waves**, and often **QT prolongation** as well as various arrhythmias. - It is highly unlikely to cause the **peaked T waves** and **bradycardia** observed in this patient.

Question 6: A previously healthy 22-year-old woman comes to the emergency department because of several episodes of palpitations that began a couple of days ago. The palpitations are intermittent in nature, with each episode lasting 5–10 seconds. She states that during each episode she feels as if her heart is going to “spin out of control.” She has recently been staying up late to study for her final examinations. She does not drink alcohol or use illicit drugs. She appears anxious. Her temperature is 37°C (98.6°F), pulse is 75/min, and blood pressure is 110/75 mm Hg. Physical examination shows no abnormalities. An ECG is shown. Which of the following is the most appropriate next step in management?

A. Echocardiography
B. Pharmacologic cardioversion
C. Observation and rest (Correct Answer)
D. Electrical cardioversion
E. Cardiac catheter ablation

Explanation: ***Observation and rest*** - The ECG shows a **normal sinus rhythm with no acute abnormalities**, and the patient's symptoms are intermittent and brief, lasting only 5-10 seconds, which suggests **benign palpitations** possibly related to anxiety and stress (studying for finals, staying up late). - Given the patient's **hemodynamic stability** (BP 110/75 mmHg, HR 75/min), normal physical examination, and absence of alarm symptoms (e.g., chest pain, syncope, severe dyspnea), a conservative approach with observation and reassurance is appropriate. *Echocardiography* - Echocardiography is typically reserved for ruling out **structural heart disease** when there are concerning features such as murmurs, signs of heart failure, or sustained rhythm disturbances. - The patient's ECG is normal, her physical examination is unremarkable, and her symptoms are transient, making it unlikely that a structural abnormality is the cause. *Pharmacologic cardioversion* - Pharmacologic cardioversion is indicated for **sustained tachyarrhythmias** that are causing significant symptoms or are hemodynamically unstable, or for atrial fibrillation/flutter of recent onset. - The patient's heart rate is normal (75/min), and her palpitations are brief and intermittent, indicating that she is not in a sustained tachyarrhythmia requiring cardioversion. *Electrical cardioversion* - Electrical cardioversion is used for **unstable tachyarrhythmias** causing hemodynamic compromise (e.g., hypotension, shock, acute heart failure) or for sustained tachyarrhythmias refractory to pharmacologic treatment. - The patient is hemodynamically stable, her ECG shows no acute arrhythmia, and her symptoms are not severe enough to warrant immediate electrical intervention. *Cardiac catheter ablation* - Cardiac catheter ablation is a procedure typically performed to treat **recurrent, symptomatic tachyarrhythmias** that are refractory to antiarrhythmic medications or when long-term drug therapy is not desired. - This is an invasive procedure and is not indicated for intermittent, brief palpitations in a hemodynamically stable patient with a normal ECG and no clear evidence of a significant arrhythmia.

Question 7: A 23-year-old patient who has recently found out she was pregnant presents to her physician for her initial prenatal visit. The estimated gestational age is 10 weeks. Currently, the patient complains of recurrent palpitations. She is gravida 1 para 0 with no history of any major diseases. On examination, the blood pressure is 110/60 mm Hg heart rate, heart rate 94/min irregular, respiratory rate 12/min, and temperature 36.4°C (97.5°F). Her examination is significant for an opening snap before S2 and diastolic decrescendo 3/6 murmur best heard at the apex. No venous jugular distension or peripheral edema is noted. The patient’s electrocardiogram (ECG) is shown in the image. Cardiac ultrasound reveals the following parameters: left ventricular wall thickness 0.4 cm, septal thickness 1 cm, right ventricular wall thickness 0.5 cm, mitral valve area 2.2 cm2, and tricuspid valve area 4.1 cm2. Which of the following statements regarding this patient’s management is correct?

A. Beta-blockers are the preferable drug class for rate control in this case. (Correct Answer)
B. The patient requires balloon commissurotomy.
C. It is critical to reduce the heart rate below 60/min because of physiological tachycardia later in pregnancy.
D. Warfarin should be used for thromboembolism prophylaxis.
E. It is reasonable to start diuretic therapy right at this moment.

Explanation: ***Beta-blockers are the preferable drug class for rate control in this case.*** - The patient presents with **atrial fibrillation** (irregular heart rate, palpitations, ECG findings) in early pregnancy, which requires rate control to optimize cardiac output and diastolic filling. - **Beta-blockers** (such as metoprolol or labetalol) are the **preferred first-line agents** for rate control in pregnant patients with atrial fibrillation because they are relatively safe in pregnancy and effectively control ventricular rate. - The patient has mild mitral stenosis findings (opening snap, diastolic murmur), but the **mitral valve area of 2.2 cm²** is essentially **normal** (normal MVA >2.0 cm²), so the primary concern is managing the atrial fibrillation. - Rate control is particularly important in pregnancy due to increased cardiac demands and the need to optimize diastolic filling time. *It is reasonable to start diuretic therapy right at this moment.* - **Diuretics** are generally avoided in early pregnancy unless there is clear evidence of **pulmonary congestion** or **heart failure** with volume overload. - This patient shows **no signs of fluid overload**: no jugular venous distension, no peripheral edema, normal blood pressure. - Starting diuretics without volume overload can lead to **reduced placental perfusion** and potentially compromise fetal growth. - Diuretics would be indicated if the patient develops signs of heart failure or pulmonary congestion later in pregnancy. *The patient requires balloon commissurotomy.* - **Balloon commissurotomy** is reserved for patients with **severe symptomatic mitral stenosis** (mitral valve area <1.5 cm²) who are refractory to medical management. - With a **mitral valve area of 2.2 cm²**, the patient has essentially **normal valve area** (or at most very mild stenosis), making invasive intervention completely unnecessary. - The patient's symptoms are due to **atrial fibrillation**, not hemodynamically significant mitral stenosis. *It is critical to reduce the heart rate below 60/min because of physiological tachycardia later in pregnancy.* - While rate control is important in atrial fibrillation, targeting a heart rate **below 60/min** is excessively low and can lead to **bradycardia** with reduced cardiac output. - The appropriate target for rate control in atrial fibrillation is typically **60-80 bpm at rest** and **<110 bpm with activity**. - Pregnancy physiologically increases heart rate by 10-20 bpm, so overly aggressive rate control (HR <60) would be detrimental to maternal and fetal perfusion. - The goal is **adequate rate control**, not excessive bradycardia. *Warfarin should be used for thromboembolism prophylaxis.* - **Warfarin is teratogenic** and is **absolutely contraindicated** in the first trimester of pregnancy due to the risk of **fetal warfarin syndrome** (nasal hypoplasia, stippled epiphyses, CNS abnormalities). - For pregnant patients with atrial fibrillation requiring anticoagulation, **unfractionated heparin** or **low-molecular-weight heparin (LMWH)** should be used during the first trimester. - Warfarin may be considered in the **second and third trimesters** in select high-risk patients (such as mechanical valves), but should be switched back to heparin near term. - This patient at 10 weeks gestation is in the critical first trimester period where warfarin must be avoided.

Question 8: A 52-year-old woman presents with decreased exercise tolerance and difficulty breathing on exertion and while sleeping at night. She says that she requires 2 pillows to sleep at night to alleviate her shortness of breath. These symptoms started 6 months ago and are gradually increasing in severity. She does not have any chronic health problems. She has smoked 15 cigarettes per day for the past 20 years and drinks alcohol occasionally. Vital signs include: blood pressure 110/70 mm Hg, temperature 36.7°C (98.0°F), and regular pulse 90/min. On physical examination, the first heart sound is loud, and there is a low pitched rumbling murmur best heard at the cardiac apex. This patient is at high risk of developing which of the following complications?

A. Cardiac arrhythmia (Correct Answer)
B. Infective endocarditis
C. Systemic thromboembolism
D. Pulmonary hypertension
E. Right heart failure

Explanation: ***Cardiac arrhythmia*** - The patient's symptoms, including **paroxysmal nocturnal dyspnea**, **orthopnea**, **exertional dyspnea**, and an apical **low-pitched rumbling diastolic murmur** with a **loud S1**, are highly suggestive of **mitral stenosis**. - **Mitral stenosis** leads to increased **left atrial pressure** and progressive **left atrial enlargement**, making the left atrium particularly vulnerable to developing **atrial fibrillation**, which is the **most common complication** occurring in 30-40% of patients. - Atrial fibrillation can cause palpitations, worsen heart failure symptoms, and significantly increase stroke risk. *Infective endocarditis* - While patients with **mitral stenosis** have an increased risk of endocarditis, this is a less common complication compared to atrial fibrillation. - There are no signs of active infection such as fever, new murmur changes, or systemic inflammatory response in this presentation. *Systemic thromboembolism* - **Thromboembolism** is a serious complication of mitral stenosis, particularly when complicated by atrial fibrillation, but the **left atrial enlargement** and stasis that predispose to arrhythmias occur first. - Without established atrial fibrillation, the immediate risk of arrhythmia development is higher than thromboembolic events. *Pulmonary hypertension* - **Pulmonary hypertension** develops as a consequence of chronic elevation in left atrial pressure transmitting back to the pulmonary vasculature. - While this is a recognized complication, it typically develops later in the disease course, and **atrial fibrillation** remains the most common complication. *Right heart failure* - **Right heart failure** can occur secondary to pulmonary hypertension from long-standing mitral stenosis. - This represents a later-stage complication, whereas atrial arrhythmias occur earlier and more frequently in the natural history of mitral stenosis.

Question 9: A 63-year-old woman is brought to the emergency department 1 hour after the onset of right-sided weakness. She was eating breakfast when suddenly she could not lift her spoon. She cried out to her husband but her speech was slurred. For the past 4 months, she has been more anxious than usual and felt fatigued. She used to exercise regularly but had to give up her exercise routine 3 months ago because of lightheadedness and shortness of breath with exertion. She has a history of hypertension. She is a tax accountant and has had increased stress at work recently. She takes lisinopril daily and alprazolam as needed. Her temperature is 37.2°C (99.0°F), pulse is 138/min, respirations are 14/min, and blood pressure is 146/86 mm Hg. Her lungs are clear to auscultation bilaterally and she has an S1 with variable intensity. On neurologic examination, she has a right facial droop and 2/5 strength in the right shoulder, elbow, wrist, and fingers. Sensation is diminished in the right face and arm. Further evaluation is most likely to show which of the following?

A. Irregularly irregular rhythm without P waves on ECG (Correct Answer)
B. Left-sided carotid stenosis on duplex ultrasound
C. Crescent-shaped hyperdense lesion on head CT
D. Intraparenchymal hyperdensity on head CT
E. Spikes and sharp waves in temporal region on EEG

Explanation: ***Irregularly irregular rhythm without P waves on ECG*** - The sudden onset of right-sided weakness and slurred speech suggests an **acute ischemic stroke**. The patient's history of lightheadedness, shortness of breath on exertion, and a pulse of 138/min with variable S1 intensity are highly suggestive of **atrial fibrillation (Afib)**, a common cause of cardioembolic stroke. - An **irregularly irregular rhythm without P waves on ECG** is the hallmark finding of atrial fibrillation. *Spikes and sharp waves in temporal region on EEG* - **Spikes and sharp waves on EEG** are characteristic findings in **epilepsy**, particularly in the temporal lobe for temporal lobe epilepsy. - While a seizure could present with focal neurological deficits, the sudden onset, persistent deficits, and history of cardiac symptoms make stroke more likely than an acute seizure as the primary etiology here. *Left-sided carotid stenosis on duplex ultrasound* - **Carotid stenosis** is a common cause of ischemic stroke, usually ipsilateral to the symptomatic side. However, the patient's symptoms are on the right side, suggesting a lesion in the **left cerebral hemisphere**. - While **left-sided carotid stenosis** could cause a stroke affecting the right side of the body, the cardiac symptoms and examination findings (tachycardia, variable S1) make a cardioembolic source (like Afib) a more likely primary cause in this specific scenario. *Crescent-shaped hyperdense lesion on head CT* - A **crescent-shaped hyperdense lesion** on head CT is characteristic of a **subdural hematoma**, which is typically caused by trauma and results from venous bleeding. - The patient's presentation of sudden-onset neurological deficits without trauma is inconsistent with a subdural hematoma. *Intraparenchymal hyperdensity on head CT* - An **intraparenchymal hyperdensity** on head CT indicates an **intracerebral hemorrhage**. While this can cause sudden neurological deficits, the patient's other symptoms, especially the rapid heart rate and variable S1, point more strongly towards an **ischemic event** secondary to an embolic source. - An intracerebral hemorrhage is less likely given the absence of typical risk factors for hemorrhagic stroke (e.g., uncontrolled severe hypertension, anticoagulant use) and the strong indicators for a cardiac embolic source.

Question 10: Two days after an uncomplicated laparoscopic abdominal hernia repair, a 46-year-old man is evaluated for palpitations. He has a history of hypertension, type 2 diabetes mellitus, and a ventricular septal defect that closed spontaneously as a child. His father has coronary artery disease. Prior to admission, his only medications were hydrochlorothiazide and metformin. He currently also takes hydromorphone/acetaminophen for mild postoperative pain. He is 180 cm (5 ft 11 in) tall and weighs 100 kg (220 lb); BMI is 30.7 kg/m2. His temperature is 37.0°C (99°F), blood pressure is 139/85 mmHg, pulse is 75/min and irregular, and respirations are 14/min. Cardiopulmonary examination shows a normal S1 and S2 without murmurs and clear lung fields. The abdominal incisions are clean, dry, and intact. There is mild tenderness to palpation over the lower quadrants. An electrocardiogram is obtained and shown below. Which of the following is the most likely cause of this patient's ECG findings?

A. Hydromorphone administration
B. Hypokalemia (Correct Answer)
C. Accessory pathway in the heart
D. Atrial enlargement
E. Acute myocardial ischemia

Explanation: ***Hypokalemia*** - The ECG shows **prominent U waves**, which are characteristic of and most often associated with **hypokalemia**. The patient's history of being on **hydrochlorothiazide**, a thiazide diuretic, increases the risk of electrolyte disturbances, including hypokalemia. - While the patient's pulse is 75/min and irregular, the primary finding on the ECG that points to hypokalemia is the presence of **U waves**, which can also predispose to arrhythmias. *Hydromorphone administration* - Opioids like hydromorphone can cause various side effects, but they typically **do not directly cause U waves** on an ECG or directly lead to the specific type of irregular rhythm seen with hypokalemia. - Common cardiac side effects of opioids include **bradycardia** or **QT prolongation**, which are not consistently present or the most prominent finding here. *Accessory pathway in the heart* - An accessory pathway often presents with a **short PR interval** and a **delta wave** (pre-excitation) on ECG, indicative of conditions like Wolff-Parkinson-White syndrome. These findings are not described in the ECG provided or implied by the symptoms. - While an accessory pathway can cause palpitations due to reentrant tachycardias, the specific ECG finding of prominent U waves is **not consistent** with an accessory pathway. *Atrial enlargement* - **Left atrial enlargement** can manifest as a **notched P wave** (P mitrale) or a **prolonged P wave duration** on ECG, while **right atrial enlargement** might show a **tall, peaked P wave** (P pulmonale). - The ECG findings described (prominent U waves, irregular pulse) are not characteristic of either left or right atrial enlargement. *Acute myocardial ischemia* - Acute myocardial ischemia would typically present with ECG changes such as **ST segment elevation or depression**, **T wave inversions**, or **new Q waves**. - While palpitations can be a symptom of ischemia, the described ECG findings, particularly the **prominent U waves**, are not indicative of acute myocardial ischemia.

Question 11: A 30-year-old man presents with progressive muscle weakness for the past 6 hours. He says he had significant bilateral ankle pain which onset shortly after completing a triathlon earlier in the day. Then, he says he awoke this morning with bilateral upper and lower extremity weakness, which has progressively worsened. He has no significant past medical history and takes no current medication. The vital signs include: temperature 37.0℃ (98.6℉), pulse 66/min, respiratory rate 21/min, and blood pressure 132/83 mm Hg. On physical examination, the patient has diffuse moderate to severe muscle pain on palpation. His strength is 5 out of 5, and deep tendon reflexes are 2+ in the upper and lower extremities bilaterally. Laboratory findings are significant for the following: Laboratory test Sodium 141 mEq/L Potassium 6.3 mEq/L Chloride 103 mEq/L Bicarbonate 25 mEq/L Blood urea nitrogen (BUN) 31 mg/dL Creatinine 6.1 mg/dL BUN/Creatinine 5.0 Glucose (fasting) 80 mg/dL Calcium 6.3 mg/dL Serum creatine kinase (CK) 90 mcg/L (ref: 10–120 mcg/L) Which of the following is the next best step in the management of this patient?

A. IV calcium chloride
B. Blood transfusion
C. ECG (Correct Answer)
D. Kayexalate
E. Hemodialysis

Explanation: ***ECG*** - This patient presents with **hyperkalemia** (potassium 6.3 mEq/L) and **hypocalcemia** (calcium 6.3 mg/dL), which can lead to life-threatening cardiac arrhythmias. - An **ECG** is crucial for assessing for cardiac manifestations of hyperkalemia, such as **peaked T waves**, prolonged PR interval, and widened QRS complex, to guide immediate treatment. *IV calcium chloride* - While **IV calcium chloride** (or calcium gluconate) is indicated in hyperkalemia with ECG changes, the **ECG needs to be performed first** to confirm the cardiac effects and guide the urgency and necessity of calcium administration. - Administering calcium without an ECG could delay the diagnosis of significant arrhythmias or mask changes, leading to inappropriate management. *Blood transfusion* - There is no indication for a **blood transfusion** in this patient; his hemoglobin and hematocrit levels are not provided, and there is no mention of acute blood loss or symptomatic anemia. - Transfusions carry risks and should only be given when clearly indicated. *Kayexalate* - **Kayexalate** (sodium polystyrene sulfonate) is a potassium-binding resin used to lower potassium levels, but its onset of action is slow (hours). - Given the patient's acute symptoms and significantly high potassium, more immediate measures to stabilize the myocardium and shift potassium intracellularly are prioritized, with Kayexalate considered as an adjunctive treatment. *Hemodialysis* - **Hemodialysis** is the most effective way to rapidly remove potassium and is indicated in severe, refractory hyperkalemia or when there are signs of advanced renal failure with complications. - However, it is an invasive procedure and other less invasive, yet rapid-acting, treatments (like calcium for cardiac stabilization, insulin-dextrose, or beta-agonists for potassium shift) should be considered and an ECG should be obtained first to determine the severity and direct initial management.

Question 12: A 40-year-old man is brought to the emergency department 20 minutes after his wife found him unconscious on the bathroom floor. On arrival, he is conscious and alert. He remembers having palpitations and feeling lightheaded and short of breath before losing consciousness. He takes captopril for hypertension and glyburide for type 2 diabetes mellitus. His vitals are within normal limits. Physical examination shows no abnormalities. Random serum glucose concentration is 85 mg/dL. An ECG shows a short PR interval and a wide QRS complex with initial slurring. Transthoracic echocardiography reveals normal echocardiographic findings with normal left ventricular systolic function. Which of the following is the most likely underlying cause of this patient's findings?

A. Ischemic myocardial necrosis
B. Ectopic foci within the ventricles
C. Accessory atrioventricular pathway (Correct Answer)
D. A dysfunctional AV node
E. Low serum glucose levels

Explanation: ***Accessory atrioventricular pathway*** - The ECG findings of a **short PR interval**, **wide QRS complex**, and **initial slurring (delta wave)** are characteristic of **Wolff-Parkinson-White (WPW) syndrome**, which is caused by an **accessory atrioventricular pathway**. - Symptoms like **palpitations, lightheadedness, and syncope** in a patient with these ECG findings suggest an underlying **tachyarrhythmia originating from the accessory pathway**. *Ischemic myocardial necrosis* - While syncope can be a symptom of **myocardial ischemia**, the ECG findings (short PR, wide QRS with delta wave) are not typical for **ischemia or infarction**. - The **normal echocardiogram** and absence of chest pain also make **ischemic myocardial necrosis** less likely. *Ectopic foci within the ventricles* - **Ventricular ectopic foci** can cause wide QRS complexes (e.g., in ventricular tachycardia), but they typically do not involve a **short PR interval or a delta wave**. - The characteristic ECG pattern observed points away from primary **ventricular ectopy** as the underlying cause. *A dysfunctional AV node* - A **dysfunctional AV node** typically leads to **AV blocks** (prolonged PR interval, dropped beats) or sometimes reentrant tachycardias, but it does not cause a **short PR interval with a delta wave and wide QRS complex**. - The described ECG pattern indicates a bypass of the **AV node's normal delay function**. *Low serum glucose levels* - Although the patient takes **glyburide** (which can cause hypoglycemia), his **random serum glucose** was 85 mg/dL, which is within the normal range and does not indicate **hypoglycemia**. - While hypoglycemia can cause syncope, it does not explain the specific ECG abnormalities observed.

Question 13: A 23-year-old man comes to the physician because of a 1-year history of episodic shortness of breath. Physical examination shows no abnormalities. Laboratory studies show elevated serum IgE levels. Microscopic examination of the sputum shows eosinophilic, hexagonal, double-pointed crystals. A methacholine challenge test is positive. Exposure to which of the following is most likely responsible for this patient's condition?

A. Aspirin
B. Cold air
C. Tobacco smoke
D. Dust mites (Correct Answer)
E. Bird droppings

Explanation: ***Dust mites*** - The presence of **Charcot-Leyden crystals** (eosinophilic, hexagonal, double-pointed) in sputum and elevated serum **IgE** levels indicate an **allergic inflammatory process** in the airways, characteristic of **asthma**. - **Dust mites** are common indoor allergens that trigger such an allergic response in susceptible individuals, leading to episodic **shortness of breath** and a positive **methacholine challenge test**. *Aspirin* - While aspirin can trigger asthma in some individuals (**aspirin-exacerbated respiratory disease**), it is typically associated with nasal polyps and a severe asthma phenotype, and would not necessarily cause Charcot-Leyden crystals or elevated IgE due to a primary allergic response to aspirin itself. - Aspirin-induced asthma is a pseudoallergic reaction, not an IgE-mediated allergic response to the drug itself. *Cold air* - **Cold air** can be a non-specific trigger for bronchoconstriction in patients with asthma, but it is not an allergen and would not directly cause **elevated IgE** levels or Charcot-Leyden crystals. - It acts as an irritant that can worsen existing airway hyperactivity. *Tobacco smoke* - **Tobacco smoke** is a strong respiratory irritant and can exacerbate asthma symptoms and contribute to chronic obstructive pulmonary disease (COPD). - However, it does not typically cause **elevated IgE** levels or the formation of **Charcot-Leyden crystals** through an IgE-mediated allergic mechanism. *Bird droppings* - Exposure to **bird droppings** can cause **extrinsic allergic alveolitis** (hypersensitivity pneumonitis), a restrictive lung disease, or IgE-mediated allergies leading to asthma. - While it can be associated with IgE sensitization, the presentation of asthma with episodic shortness of breath and the specific finding of Charcot-Leyden crystals point more strongly to common inhaled allergens like dust mites.

Question 14: A 72-year-old man is taken to the emergency room after losing consciousness. According to his wife, he suddenly complained of fluttering in his chest, lightheadedness, and profuse sweating while walking to the grocery store. He then turned gray, lost consciousness, and collapsed onto the ground. His medical history is significant for a prior anterior wall myocardial infarction 2 years ago that was complicated by severe left ventricular systolic dysfunction. His blood pressure is 80/50 mm Hg, the temperature is 36.7°C (98.0°F), and the carotid pulse is not palpable. An ECG was obtained and the results are shown in the picture. Cardiopulmonary resuscitation is initiated and the patient is cardioverted to sinus rhythm with an external defibrillator. The patient regains consciousness and states there was no antecedent chest discomfort. Cardiac enzymes are negative and serum electrolytes are normal. Which of the following is the best next step for this patient?

A. Intravenous magnesium sulphate
B. Intravenous adenosine
C. Implantable cardioverter-defibrillator (Correct Answer)
D. Intravenous metoprolol
E. Temporary or permanent cardiac pacing

Explanation: ***Implantable cardioverter-defibrillator*** - The patient experienced **sudden cardiac arrest (SCA)** due to a **lethal ventricular arrhythmia (ventricular tachycardia progressing to ventricular fibrillation)**, suggested by the syncopal episode, unrecordable pulse, and successful defibrillation. - Given the history of severe **left ventricular systolic dysfunction** (LVEF <35-40%) post-MI, he is at high risk for recurrence, making an **ICD** the most appropriate intervention for secondary prevention of SCA. *Intravenous magnesium sulphate* - **Magnesium sulfate** is primarily used for the treatment of **Torsades de Pointes**, a polymorphic VT often associated with a prolonged QT interval. - The provided ECG (though not visible here, the clinical context implies a monomorphic VT or VF) and history do not specifically suggest Torsades de Pointes. *Intravenous adenosine* - **Adenosine** is the drug of choice for terminating **supraventricular tachycardias (SVTs)** by transiently blocking the AV node. - It is **contraindicated** in wide-complex tachycardias of uncertain origin, especially in patients with structural heart disease, as it can worsen ventricular arrhythmias. *Intravenous metoprolol* - **Beta-blockers** like metoprolol are used to slow heart rate, reduce myocardial oxygen demand, and can be helpful in some forms of VT, but they are not the definitive treatment for **hemodynamically unstable** VT or for preventing future SCA in a patient with severe LV dysfunction. - Administering a beta-blocker during an acute, unstable event could worsen hypotension. *Temporary or permanent cardiac pacing* - **Cardiac pacing** is indicated for **bradyarrhythmias** or some forms of **tachycardia** (e.g., overdrive pacing for recurrent VT), but it is not the primary treatment for preventing SCA from ventricular fibrillation in a patient with severe LV dysfunction like this. - The patient's presentation was due to a fast, lethal arrhythmia, not a slow rhythm.

Question 15: A 55-year-old woman presents to the physician with repeated episodes of dizziness for the last 3 months, which are triggered by rising from a supine position and by lying down. The episodes are sudden and usually last for less than 30 seconds. During the episode, she feels as if she is suddenly thrown into a rolling spin. She has no symptoms in the period between episodes. The patient denies having headaches, vomiting, deafness, ear discharge or ear pain. There is no history of a known medical disorder or prolonged consumption of a specific drug. The vital signs are within normal limits. On physical examination, when the physician asks the woman to turn her head 45° to the right, and then to rapidly move from the sitting to the supine position, self-limited rotatory nystagmus is observed following her return to the sitting position. The rest of the neurological examination is normal. Which of the following is the treatment of choice for the condition of this patient?

A. Oral prednisolone for 2 weeks and follow-up
B. Singular neurectomy
C. Posterior canal occlusion
D. Canalith repositioning (Correct Answer)
E. Oral meclizine for 6 weeks and follow-up

Explanation: ***Canalith repositioning*** - The patient's symptoms (short-lasting, positional dizziness, rolling spin sensation, absence of other neurological symptoms, and positive **Dix-Hallpike maneuver** with **rotatory nystagmus**) are characteristic of **Benign Paroxysmal Positional Vertigo (BPPV)**. - **Canalith repositioning maneuvers** (e.g., Epley maneuver) are the treatment of choice as they aim to move dislodged otoconia out of the semicircular canals. *Oral prednisolone for 2 weeks and follow-up* - **Prednisolone** is a corticosteroid used for inflammatory conditions, but it is **not indicated for BPPV**, which is a mechanical problem. - While corticosteroids might be used in other vestibular disorders like Meniere's disease or vestibular neuritis, they would not address the underlying cause of BPPV. *Singular neurectomy* - **Singular neurectomy** is a surgical procedure that involves cutting the singular nerve (posterior ampullary nerve). - This is a highly invasive treatment reserved for **intractable BPPV** that has failed multiple conservative treatments, and it carries risks such as hearing loss. *Posterior canal occlusion* - **Posterior canal occlusion** is a surgical procedure that involves plugging the posterior semicircular canal. - This is a surgical option for **severe, refractory BPPV** that has not responded to canalith repositioning maneuvers, and it is more invasive than repositioning. *Oral meclizine for 6 weeks and follow-up* - **Meclizine** is an antihistamine used to relieve symptoms of nausea, vomiting, and dizziness associated with vertigo. - While it can help alleviate symptoms, it does **not treat the underlying cause of BPPV** and is typically used for symptomatic relief, not as a definitive treatment.

Question 16: A 77-year-old man presents to the emergency department complaining of feeling like “his heart was racing” for the last 8 days. He denies any chest pain, dizziness, or fainting but complains of fatigue, difficulty breathing with exertion, and swelling of his legs bilaterally for the last 2 weeks. He has had hypertension for the last 25 years. He has a long history of heavy alcohol consumption but denies smoking. His blood pressure is 145/70 mm Hg and the pulse is irregular at the rate of 110/min. On examination of his lower limbs, mild pitting edema is noted of his ankles bilaterally. On cardiac auscultation, heart sounds are irregular. Bibasilar crackles are heard with auscultation of the lungs. An ECG is ordered and the result is shown in the image. Transesophageal echocardiography shows a reduced ejection fraction of 32% and dilatation of all chambers of the heart without any obvious intracardiac thrombus. Which of the following is the optimal therapy for this patient?

A. Immediate direct current (DC) cardioversion
B. Warfarin and diltiazem indefinitely
C. Rivaroxaban for 3–4 weeks followed by cardioversion and continuation of rivaroxaban (Correct Answer)
D. Catheter ablation for pulmonary vein isolation
E. Observation

Explanation: ***Rivaroxaban for 3–4 weeks followed by cardioversion and continuation of rivaroxaban*** - This patient has **atrial fibrillation (AF)** with a history of hypertension, which places him at high risk of **thromboembolic events** (CHA2DS2-VASc score). Since the AF has been present for 8 days, it is considered of **unknown duration** (or longer than 48 hours for practical purposes), necessitating adequate **anticoagulation (3-4 weeks)** before cardioversion to prevent stroke. - After successful cardioversion, indefinite continuation of **oral anticoagulation with rivaroxaban** (a direct oral anticoagulant or DOAC) is crucial given his high CHA2DS2-VASc score to prevent future strokes due to recurrent AF or paroxysmal AF episodes. *Immediate direct current (DC) cardioversion* - **Immediate cardioversion** without prior anticoagulation is contraindicated because the AF duration is unknown/longer than 48 hours, significantly increasing the risk of **thromboembolic stroke** as pre-formed clots in the atrium could embolize upon restoration of sinus rhythm. - While the patient is hemodynamically stable, the risk of stroke from immediate cardioversion outweighs the benefits. *Warfarin and diltiazem indefinitely* - Although **warfarin** is a suitable anticoagulant, starting it now and continuing **diltiazem** (for rate control) indefinitely without attempting rhythm control (cardioversion) would leave the patient in AF, contributing to continued symptoms and progressive **cardiac remodeling** given his reduced ejection fraction. - The goal should be to restore sinus rhythm while ensuring safe anticoagulation. *Catheter ablation for pulmonary vein isolation* - While **catheter ablation** is an effective rhythm control strategy for AF, it is typically considered after **pharmacological management** fails or in patients who prefer a non-pharmacological approach. - In this acute setting, the immediate priority is to safely cardiovert the patient after adequate anticoagulation, and ablation is a secondary consideration for long-term rhythm maintenance. *Observation* - **Observation** is inappropriate given the patient's symptomatic AF, reduced ejection fraction, and risk of **thromboembolic stroke**. - This approach would leave the patient in AF, exacerbating his symptoms and increasing the risk of complications such as **heart failure progression** and stroke.

Question 17: A 76-year-old woman with a history of hypertension and type 2 diabetes mellitus is brought to the emergency department 60 minutes after the acute onset of left-sided abdominal pain and nausea with vomiting. Three weeks ago, she underwent emergency surgical revascularization for acute left lower extremity ischemia. Physical examination shows left upper quadrant tenderness without rebound or guarding. Serum studies show an elevated lactate dehydrogenase level. Laboratory studies, including a complete blood count, basic metabolic panel, and hepatic panel, are otherwise unremarkable. A transverse section of a CT scan of the abdomen is shown. Further evaluation is most likely to show which of the following?

A. Infrarenal aortic aneurysm on abdominal CT scan
B. Non-compressible femoral vein on ultrasonography
C. Schistocytes on peripheral blood smear
D. Right atrial thrombus on transesophageal echocardiography
E. Absent P waves on electrocardiogram (Correct Answer)

Explanation: ***Absent P waves on electrocardiogram*** - The patient presents with classic signs of **acute mesenteric ischemia**, including sudden onset severe abdominal pain, nausea/vomiting, and a history of vascular disease in a hypercoagulable state (recent revascularization for limb ischemia). An elevated **lactate dehydrogenase (LDH)** is a non-specific but suggestive marker of tissue ischemia. The CT scan images show **pneumatosis intestinalis** and portomesenteric venous gas, which are definitive signs of bowel infarction. - The most common cause of acute mesenteric ischemia is an **arterial embolism**, often originating from the heart due to **atrial fibrillation**. In atrial fibrillation, the atria quiver instead of contracting effectively, leading to blood stasis and clot formation, which can then embolize. An **absent P wave** on ECG is the hallmark of atrial fibrillation. *Infrarenal aortic aneurysm on abdominal CT scan* - While an aortic aneurysm can cause abdominal pain, the pain is typically described as tearing or radiating to the back, and the CT findings of **pneumatosis intestinalis** and **portomesenteric venous gas** are not features of an uncomplicated aortic aneurysm. - Furthermore, an aneurysm would not explain the high likelihood of **cardiac embolization** as the cause of mesenteric ischemia in this setting. *Non-compressible femoral vein on ultrasonography* - A non-compressible femoral vein indicates **deep vein thrombosis (DVT)**, which could lead to a pulmonary embolism, but not typically acute arterial mesenteric ischemia unless there is a paradoxical embolism through a patent foramen ovale, which is less common. - DVT is a venous issue, whereas acute mesenteric ischemia is primarily an arterial occlusive disease in this clinical context. *Schistocytes on peripheral blood smear* - **Schistocytes** indicate **microangiopathic hemolytic anemia**, which can be seen in conditions like thrombotic thrombocytopenic purpura (TTP), hemolytic uremic syndrome (HUS), or disseminated intravascular coagulation (DIC). - While systemic illnesses can contribute to vascular problems, the acute presentation with clear signs of bowel ischemia and a history pointing to an embolic source makes other diagnoses less likely to be the primary cause of mesenteric ischemia. *Right atrial thrombus on transesophageal echocardiography* - A right atrial thrombus is typically associated with conditions that increase venous stasis, such as central venous catheters or deep vein thrombosis (DVT), and usually causes **pulmonary embolism** if it embolizes. - While a thrombus in the heart can embolize, an **arterial embolism** causing mesenteric ischemia more commonly originates from the left side of the heart, particularly in the context of atrial fibrillation.

Question 18: A 21-year-old woman presents with palpitations and anxiety. She had a recent outpatient ECG that was suggestive of supraventricular tachycardia, but her previous physician failed to find any underlying disease. No other significant past medical history. Her vital signs include blood pressure 102/65 mm Hg, pulse 120/min, respiratory rate 17/min, and temperature 36.5℃ (97.7℉). Electrophysiological studies reveal an atrioventricular nodal reentrant tachycardia. The patient refuses an ablation procedure so it is decided to perform synchronized cardioversion with consequent ongoing management with verapamil. Which of the following ECG features should be monitored in this patient during treatment?

A. Amplitude and direction of the T wave
B. Length of QRS complex
C. Length of QT interval
D. Length of PR interval (Correct Answer)
E. QRS complex amplitude

Explanation: ***Length of PR interval*** - Verapamil is a **non-dihydropyridine calcium channel blocker** that primarily acts on the **AV node** to slow conduction. - Monitoring the **PR interval** is crucial because excessive slowing of AV nodal conduction can lead to **AV block**, which is indicated by a prolonged PR interval. *Amplitude and direction of the T wave* - Changes in T-wave amplitude and direction are often associated with **myocardial ischemia** or **electrolyte imbalances**, which are not the primary concerns with verapamil. - While verapamil can affect repolarization, the most direct and common adverse effect related to its mechanism of action on the AV node is not primarily reflected in T-wave changes. *Length of QRS complex* - The QRS complex duration primarily reflects **ventricular depolarization** and is typically affected by medications that alter conduction through the His-Purkinje system or within the ventricles, such as antiarrhythmics like **flecainide** or **amiodarone**. - Verapamil's main action is on the AV node, so it generally does not significantly prolong the QRS complex unless there is pre-existing conduction system disease. *Length of QT interval* - The QT interval represents **ventricular repolarization**, and its prolongation can lead to **Torsades de Pointes**, a life-threatening arrhythmia. - While many antiarrhythmics can prolong the QT interval, **verapamil is not known to significantly prolong the QT interval** and is generally considered safe in this regard. *QRS complex amplitude* - Changes in QRS amplitude can indicate conditions like **pericardial effusion**, **cardiomyopathy**, or changes in ventricular mass. - These are generally not direct or common side effects of verapamil therapy, which primarily focuses on AV nodal conduction.

Question 19: A previously healthy 66-year-old woman comes to the physician because of a 3-day history of fever, cough, and right-sided chest pain. Her temperature is 38.8°C (101.8°F) and respirations are 24/min. Physical examination shows dullness to percussion, increased tactile fremitus, and egophony in the right lower lung field. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of these findings?

A. Fluid in the interstitial space
B. Air in the pleural space
C. Consolidation of a lung segment (Correct Answer)
D. Fluid in the pleural space
E. Collapse of a lung segment

Explanation: ***Consolidation of a lung segment*** - The combination of **fever**, **cough**, and **chest pain** along with physical exam findings of **dullness to percussion**, **increased tactile fremitus**, and **egophony** in a specific lung field is classic for **lobar pneumonia**, which involves consolidation. - **Consolidation** occurs when the normally air-filled alveoli become filled with inflammatory exudate (fluid, cells, and fibrin), leading to increased density of the lung tissue. *Fluid in the interstitial space* - **Interstitial fluid** typically causes **crackles** on auscultation and can be associated with conditions like **pulmonary edema**, but it does not usually cause **increased tactile fremitus** or **egophony**. - **Dullness to percussion** would be less localized and tactile fremitus would not be increased as the sound transmission is not enhanced. *Air in the pleural space* - **Air in the pleural space (pneumothorax)** would lead to **hyperresonance** to percussion, **decreased or absent breath sounds**, and **decreased tactile fremitus**, which are opposite to the findings described. - There would be no egophony, as sound transmission is diminished. *Fluid in the pleural space* - **Fluid in the pleural space (pleural effusion)** would cause **dullness to percussion** and **decreased or absent breath sounds** over the effusion. - It would also typically result in **decreased tactile fremitus** due to the fluid separating the lung from the chest wall, unlike the increased fremitus seen with consolidation. *Collapse of a lung segment* - **Collapse of a lung segment (atelectasis)** would result in **dullness to percussion** and **decreased or absent breath sounds**. - **Tactile fremitus** would be **decreased** over the affected area, not increased, because the collapsed lung tissue does not transmit vibrations as effectively.

Question 20: A 55-year-old woman visits the clinic after experiencing what she describes as an odd episode of tingling in her fingers and the sensation of smelling sour milk. She denies loss of consciousness, confusion, or incontinence. She also denies a history of head trauma or the ingestion of toxic substances. Past medical history is significant for type 2 diabetes mellitus, which is well controlled with metformin. Her temperature is 36.8°C (98.2°F), the heart rate is 98/min, the respiratory rate is 15/min, the blood pressure is 100/75 mm Hg, and the O2 saturation is 100% on room air. The physical exam, including a full neurologic and cardiac assessment, demonstrates no abnormal findings. Laboratory findings are shown. Brain MRI does not indicate any areas of infarction or hemorrhage. ECG is normal, and EEG is pending. BUN 15 mg/dL pCO2 40 mmHg Creatinine 0.8 mg/dL Glucose 95 mg/dL Serum chloride 103 mmol/L Serum potassium 3.9 mEq/L Serum sodium 140 mEq/L Total calcium 2.3 mmol/L Magnesium 1.7 mEq/L Phosphate 0.9 mmol/L Hemoglobin 14 g/dL Glycosylated hemoglobin 5.5% Total cholesterol 4 mmol/L Bicarbonate (HCO3) 19 mmol/L Urine toxicology screen is negative. What kind of seizure is most likely being described?

A. Complex partial
B. Absence
C. Myoclonic
D. Tonic-clonic
E. Simple partial (Correct Answer)

Explanation: ***Simple partial*** - The patient's description of **tingling in her fingers** (somatosensory symptom) and the **sensation of smelling sour milk** (olfactory hallucination) are characteristic features of a **simple partial seizure**. - **Consciousness remains intact** during simple partial seizures, which aligns with the patient's denial of loss of consciousness or confusion. *Complex partial* - **Complex partial seizures** involve an **alteration or loss of consciousness**, which the patient explicitly denies. - While they can include focal symptoms, the defining feature of a complex partial seizure is impaired awareness, which is not present here. *Absence* - **Absence seizures** typically present as brief episodes of **staring spells** or a sudden cessation of activity, often seen in children. - They do not typically involve focal sensory or olfactory symptoms like tingling or smelling sour milk. *Myoclonic* - **Myoclonic seizures** are characterized by **sudden, brief, shock-like jerks** of a muscle or a group of muscles. - The patient's symptoms of tingling and olfactory hallucination are not consistent with the motor manifestations of myoclonic seizures. *Tonic-clonic* - **Tonic-clonic seizures** involve a loss of consciousness, followed by a tonic (stiffening) phase and then a clonic (jerking) phase, often with postictal confusion. - The patient denies loss of consciousness and her symptoms are focal and much less dramatic than a generalized tonic-clonic event.

Question 21: A 62-year-old man with a 5-year history of chronic obstructive pulmonary disease comes to the physician for a follow-up examination. He has had episodic palpitations over the past week. His only medication is a tiotropium-formoterol inhaler. His pulse is 140/min and irregular, respirations are 17/min, and blood pressure is 116/70 mm Hg. Pulse oximetry on room air shows an oxygen saturation of 95%. The lungs are clear to auscultation. Cardiac examination shows no murmurs, rubs, or gallops. Serum concentrations of electrolytes, thyroid-stimulating hormone, and cardiac troponins are within the reference range. An electrocardiogram is shown. Which of the following is the most appropriate next step in management?

A. Procainamide therapy
B. Radiofrequency ablation
C. Synchronized cardioversion
D. Propranolol therapy
E. Verapamil therapy (Correct Answer)

Explanation: ***Verapamil therapy*** - The ECG shows **multifocal atrial tachycardia (MAT)**, characterized by at least three different P-wave morphologies, irregular PP/PR/RR intervals, and an atrial rate >100/min. Given the patient's COPD and stable hemodynamics, **verapamil** (a non-dihydropyridine calcium channel blocker) is the preferred treatment to control the ventricular rate. - Verapamil is effective in slowing AV nodal conduction and can help re-establish a regular rhythm in patients with MAT, especially those with underlying pulmonary disease where beta-blockers may be relatively contraindicated. *Procainamide therapy* - **Procainamide**, a Class Ia antiarrhythmic, is typically used for ventricular arrhythmias or re-entrant supraventricular tachycardias, not usually as first-line for MAT. - It carries risks of proarrhythmia and hypotension, which are less desirable in a patient with stable MAT. *Radiofrequency ablation* - **Radiofrequency ablation** is a definitive treatment for refractory arrhythmias but is generally reserved for patients whose MAT is symptomatic and resistant to pharmacological therapy. - It is an invasive procedure and not the initial management choice for a stable patient with MAT. *Synchronized cardioversion* - **Synchronized cardioversion** is indicated for unstable tachyarrhythmias causing hemodynamic compromise (e.g., hypotension, altered mental status, acute heart failure, ischemic chest pain). - This patient is hemodynamically stable (BP 116/70, clear lungs, normal oxygen saturation), so cardioversion is not immediately necessary. *Propranolol therapy* - **Propranolol**, a non-selective beta-blocker, could be effective for rate control in MAT. However, in a patient with **COPD**, non-selective beta-blockers can worsen bronchoconstriction and are generally avoided. - While cardioselective beta-blockers (e.g., metoprolol) might be considered, **calcium channel blockers** like verapamil are often preferred in MAT with concurrent pulmonary disease due to less risk of bronchospasm.

Question 22: A previously healthy 33-year-old woman comes to the emergency department because she could feel her heart racing intermittently for the last 2 hours. Each episode lasts about 10 minutes. She does not have any chest pain. Her mother died of a heart attack and her father had an angioplasty 3 years ago. She has smoked a half pack of cigarettes daily for 14 years. She drinks one to two beers daily. She appears anxious. Her temperature is 37.6°C (98.1°F), pulse is 160/min, and blood pressure is 104/76 mm Hg. The lungs are clear to auscultation. Cardiac examination shows no murmurs, rubs, or gallops. An ECG is shown. Which of the following is the most appropriate initial step in management?

A. Intravenous adenosine
B. Aspirin
C. Intravenous procainamide
D. Vagal maneuvers (Correct Answer)
E. Coronary angioplasty

Explanation: ***Vagal maneuvers*** - The ECG shows a **narrow complex tachycardia** at a rate of 160/min. Given the patient's stable hemodynamics (BP 104/76 mm Hg), **vagal maneuvers** are the most appropriate initial step to attempt to terminate the re-entrant rhythm, such as Valsalva maneuver or carotid sinus massage. - Vagal maneuvers increase **parasympathetic tone** to the heart, which can slow conduction through the AV node and potentially break the re-entrant circuit causing the supraventricular tachycardia (SVT). *Intravenous adenosine* - **Adenosine** is a treatment for **narrow complex tachycardia** if vagal maneuvers fail, but it is not the *initial* step in a hemodynamically stable patient. - It works by transiently blocking the **AV node**, interrupting re-entrant pathways. *Intravenous procainamide* - **Procainamide** is an antiarrhythmic typically used for **wide complex tachycardia** or for narrow complex tachycardias that are refractory to vagal maneuvers and adenosine, or when there is evidence of pre-excitation. - It is not the first-line treatment for a stable **narrow complex tachycardia**. *Aspirin* - **Aspirin** is an **antiplatelet agent** used in the management of acute coronary syndromes or for cardiovascular disease prevention. - It has no role in the immediate termination of a **tachyarrhythmia** like the one presented. *Coronary angioplasty* - **Coronary angioplasty** is a procedure used to open blocked or narrowed coronary arteries, usually for **acute coronary syndromes** or chronic stable angina. - The patient presents with a **tachyarrhythmia** and no signs of acute ischemia (no chest pain, although risk factors are present), making angioplasty an inappropriate initial management step.

Question 23: A 68-year-old woman is brought to the emergency department by her husband because of acute confusion and sudden weakness of her left leg that lasted for about 30 minutes. One hour prior to admission, she was unable to understand words and had slurred speech for about 15 minutes. She has type 2 diabetes mellitus and hypertension. She has smoked 1 pack of cigarettes daily for 30 years. Current medications include metformin and hydrochlorothiazide. Her pulse is 110/min and irregular; blood pressure is 135/84 mmHg. Examination shows cold extremities. There is a mild bruit heard above the left carotid artery. Cardiac examination shows a grade 2/6 late systolic ejection murmur that begins with a midsystolic click. Neurological and mental status examinations show no abnormalities. An ECG shows irregularly spaced QRS complexes with no discernible P waves. Doppler ultrasonography shows mild left carotid artery stenosis. A CT scan and diffusion-weighted MRI of the brain show no abnormalities. Which of the following treatments is most likely to prevent future episodes of neurologic dysfunction in this patient?

A. Warfarin (Correct Answer)
B. Enalapril
C. Alteplase
D. Aspirin
E. Mitral valve replacement

Explanation: ***Warfarin*** - The patient experienced a **transient ischemic attack (TIA)** due to **atrial fibrillation** as indicated by the irregular pulse and ECG findings of irregularly spaced QRS complexes with no discernible P waves. Atrial fibrillation significantly increases the risk of stroke due to thrombus formation in the atria. - **Warfarin**, or other oral anticoagulants (e.g., direct oral anticoagulants), is crucial for preventing future embolic events by reducing the risk of clot formation in the heart. - The patient has a high CHADS₂-VASc score (age ≥65, hypertension, diabetes, prior TIA), making anticoagulation the standard of care. *Mitral valve replacement* - The patient has a grade 2/6 late systolic murmur with a midsystolic click, which is classic for **mitral valve prolapse (MVP)**. While MVP can rarely be associated with embolic events, it is typically benign and does not require surgical intervention unless there is severe mitral regurgitation with heart failure symptoms. - The primary cause of this patient's neurologic dysfunction is **atrial fibrillation**, not structural valve disease. There are no clinical signs of severe mitral regurgitation (pulmonary edema, severe heart failure) that would warrant valve replacement. - Anticoagulation for atrial fibrillation addresses the root cause of the embolic risk. *Enalapril* - Enalapril is an **ACE inhibitor** used to treat hypertension and heart failure. While managing hypertension is important for stroke prevention, it does not address the underlying thrombogenic risk from atrial fibrillation. - Although blood pressure control is part of comprehensive stroke prevention, her transient neurological events are cardioembolic, making anticoagulation the priority for primary prevention. *Alteplase* - **Alteplase** (tissue plasminogen activator) is a thrombolytic agent used to treat acute ischemic stroke, typically administered within a narrow time window after symptom onset. This patient's symptoms were transient and resolved (TIA), and she is currently asymptomatic with no acute stroke on imaging. - Administering alteplase to a patient post-TIA with no active stroke would be inappropriate and potentially harmful due to the risk of bleeding. - Alteplase treats acute strokes; it does not prevent future events. *Aspirin* - **Aspirin** is an antiplatelet agent used for secondary stroke prevention in patients with atherosclerotic disease or non-cardioembolic TIAs. However, for cardioembolic events due to atrial fibrillation, aspirin alone is insufficient. - Patients with atrial fibrillation require **anticoagulation (e.g., warfarin or DOACs)**, which is significantly more effective than antiplatelet therapy in preventing stroke from atrial fibrillation. - The mild carotid stenosis noted is not severe enough to be the primary cause of her symptoms.

Question 24: A 32-year-old woman is hospitalized after developing an allergic reaction to the contrast medium used for a cerebral angiography. The study was initially ordered as part of the diagnostic approach of a suspected case of pseudotumor cerebri. Her medical history is unremarkable. On physical examination she has stable vital signs, a diffuse maculopapular rash over her neck and chest, and a mild fever. She is started on hydrocortisone and monitored for the next 8 hours. After the monitoring period, a laboratory test shows significant azotemia. The patient complains of generalized weakness and palpitations. Tall-peaked T waves are observed on ECG. Which of the following explains this clinical manifestation?

A. Anemia
B. Platelet dysfunction
C. Uremic pericarditis
D. Metabolic acidosis
E. Hyperkalemia (Correct Answer)

Explanation: ***Hyperkalemia*** - The combination of **significant azotemia** (indicating acute kidney injury), **generalized weakness**, and **peaked T waves on ECG** are classic signs of hyperkalemia. - The allergic reaction and subsequent treatment may have exacerbated kidney dysfunction, leading to impaired potassium excretion and subsequent elevated serum potassium levels. *Anemia* - While anemia can cause weakness and palpitations, it does not typically manifest with **peaked T waves** on ECG or directly explain the presence of **azotemia**. - Anemia is common in chronic kidney disease but is not the primary cause of acute symptoms and ECG changes described here. *Platelet dysfunction* - Uremia can lead to **platelet dysfunction**, causing bleeding tendencies, but it does not account for the **generalized weakness**, **azotemia**, or the characteristic **peaked T waves** on ECG. - Platelet dysfunction is typically associated with bruising or prolonged bleeding, not the cardiovascular and neurological symptoms observed. *Uremic pericarditis* - **Uremic pericarditis** can cause chest pain, a friction rub, and sometimes palpitations, but it does not directly explain the **peaked T waves** or generalized weakness in the context of acute azotemia. - The primary symptoms of pericarditis are often related to inflammation of the pericardium rather than electrolyte imbalances. *Metabolic acidosis* - **Metabolic acidosis** is common in acute kidney injury and can contribute to weakness and dyspnea, but it does not directly cause **peaked T waves** on ECG. - While clinically important, acidosis itself doesn't explain the specific ECG findings, which are more indicative of hyperkalemia.

Question 25: A 42-year-old woman comes to the physician because of a 5-day history of intermittent palpitations. She has no history of syncope or chest pain. She had similar symptoms 1 year ago and following workup has been treated with daily flecainide since then. She drinks one to two glasses of wine on the weekends. She does not smoke. Her pulse is 71/min and her blood pressure is 134/72 mm Hg. A complete blood count shows no abnormalities. Serum creatinine, electrolytes, and TSH are within normal limits. An ECG is shown. Ablation near which of the following sites would be most appropriate for long-term management of this patient's condition?

A. Atrioventricular node
B. Basal interventricular septum
C. Cavotricuspid isthmus
D. Bundle of Kent
E. Pulmonary vein openings (Correct Answer)

Explanation: ***Pulmonary vein openings*** - The ECG shows **atrial fibrillation (AF)**, characterized by an **irregularly irregular rhythm** and **absent P waves**. - The most common cause of **paroxysmal AF** is ectopic foci originating from the **pulmonary veins**, making ablation in this area the most appropriate long-term management. *Atrioventricular node* - **AV node ablation** is typically reserved for patients with uncontrolled ventricular rates in AF despite medical therapy, often requiring a **pacemaker** afterward. - It would not prevent recurrences of AF itself, as the primary source of the arrhythmia is not the AV node. *Basal interventricular septum* - Ablation in the **basal interventricular septum** is primarily performed for arrhythmias originating from the **His bundle** or nearby ventricular foci, such as **idiopathic ventricular tachycardia**. - It is not a common target for AF ablation. *Cavotricuspid isthmus* - The **cavotricuspid isthmus (CTI)** is the classic ablation target for **atrial flutter**, a re-entrant arrhythmia in the right atrium. - While AF and flutter can coexist, the ECG findings here are classic for AF, not typical atrial flutter. *Bundle of Kent* - The **bundle of Kent** is an **accessory pathway** responsible for **Wolff-Parkinson-White (WPW) syndrome**, which causes pre-excitation. - The ECG provided does not show characteristic delta waves or a short PR interval, ruling out WPW as the primary diagnosis.

Question 26: A 54-year-old woman comes to the emergency department because of two episodes of bright red blood per rectum within the past day. She has a history of migraine, which is treated prophylactically with verapamil. She appears well and is hemodynamically stable. Cardiac exam reveals a regular heart rate without any murmurs or gallops. Lungs are clear to auscultation. Her abdomen is mildly tender without rebound or guarding. Digital rectal examination shows fresh blood on the glove. Laboratory studies show: Hemoglobin 10.4 g/dL Leukocyte count 5,000/mm3 Platelet count 175,000/mm3 Partial thromboplastin time 35 seconds Serum Na+ 140 mEq/L K+ 3.7 mEq/L Cl- 101 mEq/L HCO3- 25 mEq/L Mg2+ 1.8 mEq/L A routine ECG shows a heart rate of 75/min, a normal axis, PR interval of 280 ms, QRS interval of 80 ms with a QRS complex following each p wave, and no evidence of ischemic changes. Which of the following is the most appropriate next step in management with respect to this patient's cardiovascular workup?

A. Observation (Correct Answer)
B. Atropine therapy
C. Synchronized cardioversion
D. Metoprolol therapy
E. Pacemaker placement

Explanation: ***Observation*** - The patient is currently **hemodynamically stable** despite the prolonged PR interval, indicating that the **first-degree AV block** is not causing immediate compromise. - Continuation of **verapamil** (a calcium channel blocker) for migraine prophylaxis is the likely cause of the prolonged PR interval; however, in the absence of symptoms attributable to the AV block, observation is appropriate. *Atropine therapy* - **Atropine** is used to increase heart rate in **symptomatic bradycardia** or higher-degree AV blocks (second or third-degree) if the patient is unstable. - This patient is **hemodynamically stable** with a heart rate of 75/min and has only a first-degree AV block, making atropine unnecessary. *Synchronized cardioversion* - **Synchronized cardioversion** is reserved for **unstable tachyarrhythmias** or some unstable bradyarrhythmias not responsive to chemical therapy. - The patient's heart rate is 75/min, and she has **no evidence of an arrhythmia** requiring cardioversion; her prolonged PR interval is a conduction delay, not an arrhythmia. *Metoprolol therapy* - **Metoprolol** is a beta-blocker that would **further slow AV nodal conduction** and could potentially worsen the first-degree AV block or precipitate a higher-degree block. - It is contraindicated as a treatment for AV block and would exacerbate the underlying issue caused by verapamil. *Pacemaker placement* - **Pacemaker placement** is considered for **symptomatic second-degree or third-degree AV block**, or in some cases of first-degree AV block if it progresses to a higher degree and causes severe symptoms. - This patient has a **first-degree AV block** and is **asymptomatic** and **hemodynamically stable**, thus a pacemaker is not indicated at this time.

Question 27: A 60-year-old male presents with palpitations. He reports drinking many glasses of wine over several hours at a family wedding the previous evening. An EKG reveals absent P waves and irregularly irregular rhythm. He does not take any medications. Which is most likely responsible for the patient’s symptoms?

A. Transmural myocardial infarction
B. Untreated hypertension
C. Ventricular hypertrophy
D. Torsades de pointes
E. Atrial fibrillation (Correct Answer)

Explanation: ***Atrial fibrillation*** - The EKG findings of **absent P waves** and an **irregularly irregular rhythm** are pathognomonic for **atrial fibrillation**. - The history of heavy alcohol consumption, known as "holiday heart syndrome," is a common trigger for paroxysmal atrial fibrillation. *Transmural myocardial infarction* - A myocardial infarction (heart attack) would typically present with **chest pain**, shortness of breath, and EKG changes such as ST-segment elevation or Q waves. - While palpitations can occur, the characteristic EKG trace described is not consistent with a transmural MI. *Untreated hypertension* - Chronic untreated hypertension can lead to cardiac remodeling and increase the risk of arrhythmias, including atrial fibrillation, but it doesn't directly cause absent P waves and an irregularly irregular rhythm on its own; it's a risk factor rather than the direct cause of the immediate EKG findings. - The presenting symptoms are specifically palpitation, not necessarily those of hypertensive crisis or end-organ damage from chronic hypertension. *Ventricular hypertrophy* - Ventricular hypertrophy, often caused by untreated hypertension, is a structural change in the heart, not an arrhythmia itself. - While hypertrophy can predispose to arrhythmias, it wouldn't directly manifest as absent P waves and an irregularly irregular rhythm on EKG. *Torsades de pointes* - Torsades de pointes is a polymorphic ventricular tachycardia characterized by a **prolonged QT interval** and QRS complexes that appear to twist around the baseline. - The EKG description of absent P waves and irregularly irregular rhythm is not consistent with Torsades de pointes.

Question 28: A 66-year-old man presents to the emergency department with a 3-hour history of crushing chest pain radiating to the left shoulder and neck. Patient states that the pain began suddenly when he was taking a walk around the block and has not improved with rest. He also mentions difficulty breathing and prefers to sit leaning forward. He denies ever having similar symptoms before. Past medical history is significant for hypertension, diagnosed 10 years ago, and hyperlipidemia diagnosed 8 years ago. Current medications are atorvastatin. Patient is also prescribed hydrochlorothiazide as an antihypertensive but is not compliant because he says it makes him urinate too often. Vitals show a blood pressure of 152/90 mm Hg, pulse of 106/min, respirations of 22/min and oxygen saturation of 97% on room air. On physical exam, patient is profusely diaphoretic and hunched over in distress. Cardiac exam is unremarkable and lungs are clear to auscultation. During your examination, the patient suddenly becomes unresponsive and a pulse cannot be palpated. A stat ECG shows the following (see image). Which of the following is the next best step in management?

A. Synchronized cardioversion
B. Administer amiodarone
C. Urgent echocardiography
D. Administer epinephrine
E. Unsynchronized cardioversion (Correct Answer)

Explanation: ***Unsynchronized cardioversion*** - The ECG shows **ventricular fibrillation (VF)**, a chaotic electrical activity with no coordinated contractions, which leads to immediate cardiac arrest. - In a patient who is unresponsive and pulseless with VF, **immediate unsynchronized defibrillation** (cardioversion) is the definitive treatment to restore a perfusing rhythm. *Synchronized cardioversion* - **Synchronized cardioversion** delivers an electrical shock timed to the QRS complex, used for unstable patients with a pulse and organized tachyarrhythmias (e.g., ventricular tachycardia with a pulse, atrial flutter, or atrial fibrillation). - This patient is **pulseless** and in **ventricular fibrillation**, making synchronized cardioversion inappropriate and ineffective. *Administer amiodarone* - **Amiodarone** is an antiarrhythmic drug used in cardiac arrest protocols for **refractory VF/pulseless VT** after initial defibrillation attempts and epinephrine have failed. - It is not the *initial* best step in a pulseless patient with VF, as electrical defibrillation is paramount. *Urgent echocardiography* - While an echocardiogram might be useful in identifying the underlying cause (e.g., myocardial infarction leading to VF), it is **not the immediate life-saving intervention** for a patient in cardiac arrest from VF. - Delaying defibrillation for an echocardiogram would significantly worsen the patient's prognosis. *Administer epinephrine* - **Epinephrine** is a vasoconstrictor and cardiac stimulant used during **cardiac arrest**, typically given after the initial defibrillation attempt for VF/pulseless VT. - It helps improve myocardial and cerebral blood flow but is **secondary to immediate defibrillation** in VF.

Question 29: A 32-year-old man is brought to the emergency department after a car accident; he was extricated after 4 hours. He did not lose consciousness and does not have headache or nausea. He is in severe pain. He sustained severe injuries to both arms and the trauma team determines that surgical intervention is needed. Urinary catheterization shows dark colored urine. His temperature is 38°C (100.4°F), pulse is 110/min, and blood pressure is 90/60 mm Hg. The patient is alert and oriented. Examination shows multiple injuries to the upper extremities, contusions on the trunk, and abdominal tenderness. Laboratory studies show: Hemoglobin 9.2 g/dL Leukocyte count 10,900/mm3 Platelet count 310,000/mm3 Serum Na+ 137 mEq/L K+ 6.8 mEq/L Cl- 97 mEq/L Glucose 168 mg/dL Creatinine 1.7 mg/dL Calcium 7.7 mg/dL Arterial blood gas analysis on room air shows a pH of 7.30 and a serum bicarbonate of 14 mEq/L. An ECG shows peaked T waves. A FAST scan of the abdomen is negative. Two large bore cannulas are inserted and intravenous fluids are administered. Which of the following is the most appropriate next step in management?

A. Intravenous mannitol
B. Intravenous sodium bicarbonate
C. Packed red blood cell transfusion
D. Intravenous calcium gluconate (Correct Answer)
E. Intravenous insulin

Explanation: ***Intravenous calcium gluconate*** - The patient presents with severe **hyperkalemia** (K+ 6.8 mEq/L) and ECG changes (peaked T waves), indicating immediate cardiotoxicity risk. **Calcium gluconate** stabilizes the cardiac cell membranes, protecting the heart from the effects of high potassium. - While other options address other issues, stabilizing the heart takes precedence in cases of extreme hyperkalemia with ECG changes. *Intravenous mannitol* - **Mannitol** is an osmotic diuretic used to reduce intracranial pressure or acute cerebral edema. The patient does not show signs or symptoms requiring this intervention (no consciousness loss, headache, or nausea). - Its use here would not address the life-threatening hyperkalemia or cardiologic findings. *Intravenous sodium bicarbonate* - **Sodium bicarbonate** can help shift potassium intracellularly and correct metabolic acidosis, but its effect is slower and less reliable than calcium for immediate cardiac stabilization in severe hyperkalemia. - The primary concern here is the acute cardiac risk, which calcium directly addresses. *Packed red blood cell transfusion* - The patient has a hemoglobin of 9.2 g/dL, indicating **anemia**, likely due to trauma. However, his blood pressure is 90/60 mm Hg despite intravenous fluids, suggesting ongoing hypovolemia or other shock. - While addressing blood loss is important, the immediate life threat is the **cardiac instability due to hyperkalemia**, which must be managed first. *Intravenous insulin* - Insulin, often given with dextrose, helps shift potassium into cells. This is an effective treatment for hyperkalemia but does not provide immediate **cardiac membrane stabilization** like calcium gluconate. - Given the peaked T waves, protecting the heart from arrhythmias is the most critical first step.

Question 30: A 31-year-old nurse presents to the emergency department with palpitations, sweating, and jitteriness. She denies chest pain, shortness of breath, and recent illness. She states that she experienced weakness in her arms and legs and a tingling sensation in her fingers before the palpitations occurred. Medical and surgical history is unremarkable. Her mother has Grave’s disease. The patient has been seen in the ED multiple times for similar symptoms and was discharged after appropriate medical management. Today, her temperature is 37°C (98.6°F), blood pressure is 128/84 mm Hg, pulse is 102/min and regular, and respirations are 10/min. On examination, the patient appears diaphoretic and anxious. Her pupils are dilated to 5 mm. The rest of the examination is normal. Urine toxicology and B-HCG are pending. Which of the following is the next best step in management?

A. Fingerstick blood glucose (Correct Answer)
B. D-dimer levels
C. Echocardiogram
D. TSH levels
E. Urine metanephrines

Explanation: ***Fingerstick blood glucose*** - In the emergency department, **point-of-care glucose testing** is a critical first step for any patient presenting with autonomic symptoms (palpitations, sweating, diaphoresis), altered mental status, or neurological complaints (weakness, tingling). - **Hypoglycemia** is a life-threatening condition that can present with identical symptoms: palpitations, sweating, jitteriness, weakness, paresthesias, and altered mental status. It must be ruled out immediately as it requires urgent treatment. - This test takes **seconds to perform** and provides immediate results that guide acute management, whereas other tests (TSH, D-dimer) take hours and do not address immediate life threats. - The patient's recurrent ED visits with similar presentations that resolved with "appropriate medical management" suggest a functional or metabolic etiology rather than undiagnosed structural disease. - **Standard ED protocol** dictates checking glucose in patients with these presentations before pursuing more extensive workups. *TSH levels* - While the family history of Grave's disease raises suspicion for hyperthyroidism, this is a **screening test for outpatient workup**, not an emergency intervention. - **Hyperthyroidism** does not typically cause weakness and tingling as **preceding symptoms** before palpitations. The symptom progression described is more consistent with hyperventilation or panic attacks. - **Thyroid storm** would present with fever (temperature >38.5°C), not the normal temperature of 37°C seen here. - TSH results take hours to return and do not guide immediate ED management. After stabilizing the patient and ruling out acute emergencies, thyroid function testing may be appropriate for outpatient follow-up. *D-dimer levels* - **D-dimer** screens for thromboembolic disease such as pulmonary embolism, which typically presents with **chest pain, shortness of breath, and hypoxia**—all explicitly denied by this patient. - The patient's presentation involves autonomic and neurological symptoms without cardiopulmonary complaints, making thromboembolism unlikely. *Echocardiogram* - An **echocardiogram** evaluates cardiac structure and function and would be indicated if there were concerns for structural heart disease, valvular abnormalities, or persistent arrhythmias. - However, the patient has a **regular pulse** at 102/min (mild sinus tachycardia) without evidence of arrhythmia or hemodynamic instability. - This is not the appropriate first diagnostic step for undifferentiated autonomic symptoms in the ED. *Urine metanephrines* - **Urine metanephrines** test for **pheochromocytoma**, a rare catecholamine-secreting tumor that causes paroxysmal hypertension, palpitations, and sweating. - While pheochromocytoma is in the differential for recurrent autonomic episodes, it is **extremely rare** and would typically present with more severe hypertension during episodes. - This is a **send-out test** taking days to result, not appropriate for immediate ED management. Point-of-care glucose testing takes precedence.

Question 31: A 25-year-old man presents to the emergency department complaining of palpitations, lightheadedness, and sweating. He just started working at an investment firm and has been working long hours to make a good impression. Today, he had a dozen cups of espresso to keep himself awake and working. He has never had such an episode before. His past medical history is unremarkable. His pulse is 150/min, blood pressure is 134/88 mm Hg, respirations are 12/min, and temperature is 36.7°C (98.0°F). ECG shows supraventricular tachycardia. Which of the following is the next best step in the management of this patient?

A. Drinking coffee
B. Synchronized cardioversion
C. Valsalva maneuver (Correct Answer)
D. Adenosine infusion
E. Dipping his face in cold water

Explanation: ***Valsalva maneuver*** - The Valsalva maneuver is a **first-line vagal maneuver** used to terminate **supraventricular tachycardia (SVT)** in a stable patient, as it increases vagal tone to slow heart rate. - Given the patient's **hemodynamic stability** (BP 134/88 mmHg, no signs of shock), vagal maneuvers are the appropriate initial intervention. *Drinking coffee* - **Caffeine** is a stimulant that can *induce* or worsen tachycardia, making it an inappropriate and potentially harmful intervention in this situation. - The patient's current symptoms are likely **caffeine-induced**, so more caffeine would exacerbate the problem. *Synchronized cardioversion* - **Synchronized cardioversion** is reserved for **unstable SVT** (e.g., hypotension, altered mental status, acute heart failure, ischemic chest pain), which is not present in this patient. - It is an invasive procedure with risks and should only be used when less aggressive measures fail or the patient is in immediate danger. *Adenosine infusion* - **Adenosine** is an effective pharmacological agent for terminating SVT but is typically used if **vagal maneuvers fail** or are contraindicated. - As this patient is stable, **vagal maneuvers** should be attempted first due to their non-invasive nature and rapid action. *Dipping his face in cold water* - While **diving reflex** (induced by cold water immersion) is a vagal maneuver that can terminate SVT, it is **less commonly used** and often less effective than the Valsalva maneuver. - The Valsalva maneuver is generally the preferred and more practical initial vagal maneuver in an emergency setting.

Question 32: A 68-year-old man presents to the emergency department because of difficulty breathing and chest tightness for the last 3 days. He also has a productive cough with excessive amounts of green sputum. He has had chronic obstructive pulmonary disease for the past 10 years, but says that the cough and sputum are different compared to his baseline. He took 2 doses of nebulized albuterol and ipratropium at home, but that did not completely relieve his symptoms. He has a 50 pack-year smoking history and drinks alcohol occasionally. His vital signs include a blood pressure of 110/60 mm Hg, a temperature of 37.2 °C (98.9°F), a respiratory rate of 26/min, an irregular radial pulse at a rate of 110–120/min, and an oxygen saturation of 88%. On physical examination, the patient appears drowsy, crackles are heard on chest auscultation bilaterally, and the heart sounds are irregular. A chest X-ray shows hyperinflation of the lungs bilaterally, and the diaphragm is flattened. An ECG is ordered and shown in the accompanying image. Which of the following is the best initial treatment for this patient’s arrhythmia?

A. Synchronized cardioversion
B. Reversing bronchoconstriction and correction of electrolyte abnormalities (Correct Answer)
C. Metoprolol
D. Diltiazem
E. Catheter ablation of the cavotricuspid isthmus (CTI)

Explanation: ***Reversing bronchoconstriction and correction of electrolyte abnormalities*** - The ECG shows **multifocal atrial tachycardia (MAT)**, characterized by at least three different P-wave morphologies, an irregular heart rate, and an atrial rate usually between 100-150 bpm. This arrhythmia is commonly associated with severe pulmonary disease (like the patient's COPD exacerbation) and electrolyte imbalances (e.g., hypokalemia, hypomagnesemia). - The **best initial treatment** involves addressing the underlying cause. For this patient, optimizing his COPD exacerbation by reversing bronchoconstriction (e.g., with inhaled bronchodilators) and correcting any electrolyte abnormalities (which can trigger and sustain MAT) are the most appropriate first steps before considering antiarrhythmic drugs. *Synchronized cardioversion* - Synchronized cardioversion is indicated for patients with **unstable tachyarrhythmias** (e.g., hypotension, altered mental status, signs of shock, acute heart failure, ischemic chest discomfort). While the patient is drowsy and has an irregular pulse, his blood pressure is stable, and there are no immediate signs of instability warranting urgent cardioversion. - Cardioversion is generally **not effective** for MAT because the multiple ectopic atrial foci can immediately initiate new rhythms, making it unlikely to achieve sustained sinus rhythm. *Metoprolol* - **Beta-blockers** like metoprolol can be used to control the ventricular rate in MAT, but they should be used with extreme caution in patients with severe **COPD** or asthma due to the risk of exacerbating bronchospasm, even with cardioselective agents. - Given the patient's acute COPD exacerbation, using a beta-blocker as an initial treatment approach could worsen his respiratory status, making it a less suitable choice. *Diltiazem* - **Non-dihydropyridine calcium channel blockers** like diltiazem can also be used for rate control in MAT. However, caution is advised in patients with compromised cardiac function or severe lung disease. - While diltiazem may be considered if initial measures fail, addressing the underlying respiratory and electrolyte issues is the primary and safest initial approach before resorting to pharmacologic rate control agents that could have adverse effects. *Catheter ablation of the cavotricuspid isthmus (CTI)* - Catheter ablation of the CTI is the definitive treatment for **typical atrial flutter**, which is characterized by a "sawtooth" pattern on ECG (especially in leads II, III, aVF) due to a re-entrant circuit in the right atrium. - The patient's ECG shows **multifocal atrial tachycardia (MAT)**, not atrial flutter. Therefore, CTI ablation is not indicated for this specific arrhythmia.

Question 33: A 40-year-old woman comes to the physician for a 6-month history of recurrent episodes of chest pain, racing pulse, dizziness, and difficulty breathing. The episodes last up to several minutes. She also reports urinary urgency and two episodes of loss of consciousness followed by spontaneous recovery. There is no personal or family history of serious illness. She does not smoke or drink alcohol. Vitals signs are within normal limits. Cardiopulmonary examination shows no abnormalities. Holter monitoring is performed. ECG recordings during episodes of tachycardia show a QRS duration of 100 ms, regular RR-interval, and absent P waves. Which of the following is the most likely underlying cause of this patient's condition?

A. AV node with slow and fast pathway (Correct Answer)
B. Pre-excitation of the ventricles
C. Mutations in genes that code for myocyte ion channels
D. Macroreentrant rhythm in the right atria through cavotricuspid isthmus
E. Fibrosis of the sinoatrial node and surrounding myocardium

Explanation: ***AV node with slow and fast pathway*** - This describes **AV nodal reentrant tachycardia (AVNRT)**, a common cause of **paroxysmal supraventricular tachycardia (PSVT)**. The ECG findings of **narrow QRS (100 ms)**, regular RR-interval, and **absent P waves** (often hidden within the QRS complex) are characteristic of AVNRT. - The patient's symptoms of recurrent chest pain, racing pulse, dizziness, and spontaneous recovery from loss of consciousness fit the episodic nature of **AVNRT**. The presence of two pathways (slow and fast) within the AV node facilitates the reentrant circuit. *Pre-excitation of the ventricles* - **Pre-excitation syndromes** (e.g., Wolff-Parkinson-White syndrome) involve an accessory pathway that bypasses the AV node, leading to a **delta wave** and **short PR interval** on the baseline ECG. - While they can cause SVT, the ECG during tachycardia would typically show a **wide QRS complex** if the accessory pathway is part of the reentrant circuit (antidromic), or a narrow QRS with a visible P wave if orthodromic and the accessory pathway is used for retrograde conduction, which doesn't fully align with the absent P waves and typically *normal* QRS during tachycardia as described. *Mutations in genes that code for myocyte ion channels* - This refers to **channelopathies** (e.g., long QT syndrome, Brugada syndrome), which predispose to **ventricular arrhythmias** like **polymorphic ventricular tachycardia** and **ventricular fibrillation**. - These conditions typically cause **wide QRS tachycardias** and have distinct ECG patterns (e.g., prolonged QT interval, Brugada pattern) not described here. The narrow QRS and regular rhythm point away from primary ventricular channelopathies as the cause of this specific tachycardia. *Macroreentrant rhythm in the right atria through cavotricuspid isthmus* - This describes **atrial flutter**, which typically presents with characteristic **"sawtooth" F waves** on ECG, representing atrial activity. - While atrial flutter can cause recurrent episodes of rapid heart rate, the ECG description of **absent P waves** and a **narrow QRS complex** without F waves makes atrial flutter less likely. *Fibrosis of the sinoatrial node and surrounding myocardium* - **Sinoatrial node dysfunction (sick sinus syndrome)** can lead to bradycardia, sinus pauses, or alternating bradycardia and tachycardia (tachy-brady syndrome). - It does not primarily cause the described paroxysmal narrow-complex tachycardia with absent P waves. The patient's symptoms are more consistent with an abrupt-onset, regular supraventricular tachycardia.

Question 34: A 44-year-old man comes to the emergency department because of persistent palpitations for the past 2 hours. The day before, he was at a wedding, where he drank several glasses of wine and 9–10 vodka cocktails. He has never had similar symptoms before. He is a manager at a software company and has recently had a lot of work-related stress. He is otherwise healthy and takes no medications. His temperature is 36.5°C (97.7°F), pulse is 90/min and irregularly irregular, respirations are 13/min, and his blood pressure is 128/60 mm Hg. Physical examination shows no other abnormalities. An ECG is performed; no P-waves can be identified. Echocardiography shows no valvular abnormalities and normal ventricular function. One hour later, a repeat ECG shows normal P waves followed by narrow QRS complexes. He is still experiencing occasional palpitations. Which of the following is the most appropriate next step in management?

A. Electrical cardioversion
B. Defibrillation
C. Adenosine injection
D. Observation (Correct Answer)
E. Catheter ablation

Explanation: ***Observation*** - The patient experienced **paroxysmal atrial fibrillation (AF)** likely triggered by **binge alcohol consumption** (holiday heart syndrome), which has already spontaneously converted to normal sinus rhythm. - Given his hemodynamic stability, normal ventricular function, and the transient nature of this isolated episode, **close observation** for recurrence is the most appropriate initial step. *Electrical cardioversion* - This is primarily used for **hemodynamically unstable AF** or for persistent AF that fails to convert spontaneously. - The patient is currently **hemodynamically stable** and has already converted to normal sinus rhythm, making cardioversion unnecessary. *Defibrillation* - **Defibrillation** is used for life-threatening arrhythmias like **ventricular fibrillation** or **pulseless ventricular tachycardia**. - It is not indicated for stable atrial fibrillation, and the patient has already converted to sinus rhythm. *Adenosine injection* - **Adenosine** is used to terminate **supraventricular tachycardias (SVTs)** by blocking the AV node. - It is generally **ineffective for atrial fibrillation** and not indicated here as the patient is already in normal sinus rhythm. *Catheter ablation* - **Catheter ablation** is a definitive treatment for recurrent symptomatic AF or other arrhythmias that are refractory to medical management. - This patient has experienced a **first-time episode** that spontaneously resolved, making ablation an overly aggressive and premature intervention.

Question 35: A 62-year-old woman comes to the physician for decreased vision and worsening headaches since this morning. She has hypertension and hypercholesterolemia. Pulse is 119/min and irregular. Current medications include ramipril and atorvastatin. Ocular and funduscopic examination shows no abnormalities. The findings of visual field testing are shown. Which of the following is the most likely cause of this patient's symptoms?

A. Occlusion of the posterior cerebral artery (Correct Answer)
B. Occlusion of anterior cerebral artery
C. Degeneration of the macula
D. Occlusion of the anterior inferior cerebellar artery
E. Impaired perfusion of the retina

Explanation: ***Occlusion of the posterior cerebral artery*** - The patient presents with **acute visual field defect** and **headache** in the context of an **irregular pulse** (atrial fibrillation). - **Atrial fibrillation** is a major risk factor for **cardioembolic stroke**, particularly affecting the posterior circulation. - The **posterior cerebral artery (PCA) supplies the occipital lobe**, which contains the primary visual cortex. PCA occlusion causes **contralateral homonymous hemianopia**, often with **macular sparing** due to collateral blood supply from the middle cerebral artery. - The visual field defect pattern shown, combined with normal funduscopic examination (ruling out retinal pathology), is characteristic of **occipital cortex ischemia**. - **Acute onset** with headache further supports an embolic stroke mechanism. *Occlusion of anterior cerebral artery* - Anterior cerebral artery (ACA) occlusion primarily affects the **frontal and medial parietal lobes**. - Classic presentation includes **contralateral leg weakness** > arm weakness, sensory loss in the leg, and behavioral/personality changes. - ACA strokes do **not cause visual field defects** or homonymous hemianopia. *Degeneration of the macula* - Macular degeneration causes **gradual central vision loss**, presenting with difficulty reading and central scotomas. - This is a **chronic progressive condition**, not acute onset "since this morning." - Would not cause **headache**, irregular pulse correlation, or the specific visual field pattern shown. - Funduscopy would typically show **drusen** or retinal pigmentary changes. *Occlusion of the anterior inferior cerebellar artery* - AICA occlusion affects the **lateral pons and cerebellum**. - Presents with **vertigo, nystagmus, ataxia, ipsilateral facial paralysis**, and hearing loss. - Does **not affect the visual cortex** and would not cause homonymous visual field defects. *Impaired perfusion of the retina* - Central retinal artery occlusion causes **sudden monocular painless vision loss** (not bilateral field defects). - Funduscopy would reveal **"cherry-red spot"** at the macula and retinal whitening. - The question states funduscopic examination shows **no abnormalities**, excluding this diagnosis. - Would not explain the bilateral homonymous field defect pattern.

Question 36: A 54-year-old patient is brought to the emergency department by ambulance with palpitations, lightheadedness, and generalized weakness. He was enjoying the long weekend with his friends at a prolonged destination bachelor’s party over the last several days. They all drank a great deal of alcohol. He can’t quite recall how much he had to drink but he did not blackout. Past medical history includes hypertension. He takes enalapril daily. His blood pressure is 110/75 mm Hg, pulse 140/min, respiratory rate 14/min, temperature 37.0°C (98.6°F). The patient appears ill and has an irregular pulse. An electrocardiogram is performed (see in the picture). The physician explains to the patient that he has an abnormal heartbeat and he needs to be started on anticoagulation therapy to avoid an ischemic stroke from a thrombus that may be forming in his heart. In which of the following locations is a thrombus most likely to be formed?

A. Posterior descending artery
B. Middle cerebral artery
C. Right coronary artery
D. Left main coronary artery
E. Left atrial appendage (Correct Answer)

Explanation: ***Left atrial appendage*** - In **atrial fibrillation**, the atria do not contract effectively, leading to **blood stasis** and increased risk of thrombus formation. - The **left atrial appendage** is a small, blind-ended pouch in the left atrium, making it particularly prone to blood stasis and the most common site for thrombus formation in atrial fibrillation. *Posterior descending artery* - This artery supplies the **inferior wall of the left ventricle** and parts of the right ventricle; thrombus formation here typically leads to **myocardial infarction**, not systemic embolism from atrial fibrillation. - Thrombi in the posterior descending artery are usually due to **atherosclerosis** and plaque rupture, distinct from the stasis-induced thrombi of atrial fibrillation. *Middle cerebral artery* - While a **middle cerebral artery stroke** can be a consequence of a thrombus embolizing from the heart (often from the left atrial appendage), this artery itself is the *destination* of the embolus, not the *source* of the thrombus. - Thrombus formation *within* the middle cerebral artery is usually due to **atherosclerosis** of the cerebral vessels or small vessel disease. *Right coronary artery* - This artery supplies the **right ventricle**, right atrium, and often the SA and AV nodes; thrombus formation here also leads to **myocardial infarction**, not the source of an embolic stroke from atrial fibrillation. - Similar to the posterior descending artery, thrombi in the right coronary artery are primarily due to **atherosclerotic disease**. *Left main coronary artery* - The **left main coronary artery** is a critical vessel that branches into the left anterior descending and circumflex arteries. **Thrombus formation** here causes extensive myocardial ischemia or infarction. - Thrombi forming in the left main coronary artery are a result of **coronary artery disease** and do not typically embolize to cause systemic strokes in the context of atrial fibrillation.

Question 37: A 32-year-old woman presents to the emergency department with unilateral vision loss. She states it started suddenly this evening and this has never happened to her before. The patient is not followed by a primary care physician and is not currently taking any medications. She has had a few episodes of weakness or numbness in the past but states her symptoms usually resolve on their own. Her temperature is 97.6°F (36.4°C), blood pressure is 120/74 mmHg, pulse is 88/min, respirations are 12/min, and oxygen saturation is 98% on room air. Physical exam is notable for decreased sensation over the patient's dorsal aspect of her left foot. Visual exam reveals a loss of vision in the patient's left eye and she endorses pain in the eye on exam. Which of the following findings is also likely to be found in this patient?

A. Pruritus with exposure to heat
B. Symmetric lower extremity reflex loss
C. Ipsilateral loss of proprioception and vibration sensation
D. Electrical pain with neck flexion (Correct Answer)
E. Weakness with repeat exertion

Explanation: ***Electrical pain with neck flexion*** - The patient's presentation with **unilateral vision loss** (optic neuritis), sensory deficits, and a history of resolving neurological symptoms is highly suggestive of **multiple sclerosis (MS)**. - **Lhermitte's sign**, characterized by an "electrical" sensation down the spine and into the limbs with neck flexion, is a classic symptom of MS due to **demyelination in the cervical spinal cord**. *Pruritus with exposure to heat* - While patients with MS can exhibit **Uhthoff's phenomenon** (worsening of neurological symptoms with heat due to decreased nerve conduction), pruritus (itching) is not a typical manifestation. - Uhthoff's phenomenon usually involves a temporary worsening of existing neurological deficits, not new onset pruritus. *Symmetric lower extremity reflex loss* - MS typically causes **upper motor neuron lesions**, leading to **hyperreflexia** and spasticity, rather than reflex loss. - **Symmetric reflex loss** would be more indicative of a peripheral neuropathy or a lower motor neuron disorder. *Ipsilateral loss of proprioception and vibration sensation* - While MS can affect sensory pathways and cause proprioception and vibration deficits, these are generally not **ipsilateral** to a specific motor or sensory deficit in a predictable manner like in a spinal cord hemisection (Brown-Séquard syndrome). - The pattern of neurological deficits in MS is often disseminated in space and time, affecting various parts of the central nervous system. *Weakness with repeat exertion* - **Weakness with repeat exertion** specifically describes **myasthenia gravis**, a neuromuscular junction disorder. - Myasthenia gravis is characterized by **fatigable weakness** that improves with rest and is caused by antibodies against acetylcholine receptors or muscle-specific kinase (MuSK).

Question 38: Two days after admission for myocardial infarction and subsequent coronary angioplasty, a 65-year-old man becomes distressed and diaphoretic in the cardiac intensive care unit. Suddenly he is no longer responsive. Pulse oximetry does not show a tracing. He has a history of hypertension and depression. Prior to his admission, his medication included ramipril and aripiprazole. Examination shows no carotid pulse. An ECG is shown. After beginning chest compressions, which of the following is the most appropriate step in management of the patient?

A. Intravenous procainamide
B. Cardiac catheterization
C. Intravenous amiodarone
D. Intravenous magnesium sulfate
E. Defibrillation (Correct Answer)

Explanation: ***Defibrillation*** - The ECG shows a **wide complex tachycardia** consistent with either **ventricular fibrillation (VF)** or **pulseless ventricular tachycardia (VT)**. - In a patient who is **unresponsive and pulseless**, both VF and pulseless VT are treated identically with **immediate unsynchronized defibrillation** after initiating CPR, according to **ACLS guidelines**. - **Defibrillation** is the definitive treatment to restore a perfusing rhythm and is the priority intervention after chest compressions have begun. *Intravenous procainamide* - **Procainamide** is an antiarrhythmic drug used for certain types of **stable ventricular tachycardia** or wide-complex tachycardia of uncertain type when the patient has a pulse. - It is **contraindicated** in pulseless arrhythmias like VF or pulseless VT, where electrical therapy (defibrillation) is paramount. - Administration would cause dangerous delay in definitive treatment. *Cardiac catheterization* - **Cardiac catheterization** is an invasive diagnostic and interventional procedure typically performed to evaluate and treat coronary artery disease. - It is **not an immediate life-saving intervention** for a patient in **cardiac arrest**, which requires immediate electrical therapy. - Catheterization may be considered after return of spontaneous circulation (ROSC) to address underlying ischemia. *Intravenous amiodarone* - **Amiodarone** is an antiarrhythmic agent used in **VF/pulseless VT that is refractory to initial defibrillation attempts** and after epinephrine administration. - It is administered **after initial defibrillation attempts have failed**, not as the primary or first-line treatment. - The ACLS algorithm recommends amiodarone after the third shock if VF/pulseless VT persists. *Intravenous magnesium sulfate* - **Magnesium sulfate** is the treatment of choice for **Torsades de Pointes**, a polymorphic ventricular tachycardia often associated with **prolonged QT interval**. - The clinical presentation and ECG do not suggest Torsades de Pointes, and magnesium is not indicated as the initial treatment for VF or monomorphic VT. - Magnesium may also be considered for refractory VF/VT with suspected hypomagnesemia.

Question 39: A 15-year-old boy is brought to the emergency department after he passed out in the hallway. On presentation, he is alert but confused about why he is in the hospital. He says that he remembers seeing flashes of light to his right while walking out of class but cannot recall what happened next. His next memory is being woken up by emergency responders who wheeled him into an ambulance. A friend who was with him at the time says that he seemed to be swallowing repeatedly and staring out into space. He has never had an episode like this before, and his past medical history is unremarkable. Which of the following characteristics is most likely true of the cause of this patient's symptoms?

A. Begins with 10-15 seconds of muscle contraction
B. Isolated to the left occipital lobe
C. Episodes with 3-4 hertz spike and wave discharges
D. Starts in the left occipital lobe and then generalizes (Correct Answer)
E. Demonstrates quick and repetitive jerks of extremities

Explanation: ***Starts in the left occipital lobe and then generalizes*** - The patient experienced **visual aura** (seeing flashes of light to his right), indicating seizure onset in the **left occipital lobe**, as visual pathways decussate. - The subsequent **altered consciousness**, automatisms (**swallowing repeatedly**, staring into space), and postictal confusion suggest the seizure generalized. *Begins with 10-15 seconds of muscle contraction* - This description is characteristic of the **tonic phase** of a **tonic-clonic seizure**, which involves widespread muscle rigidity. - The patient's description of a visual aura and automatisms is more consistent with a **focal seizure with impaired awareness** that may have secondary generalization, rather than a primary generalized tonic-clonic seizure. *Isolated to the left occipital lobe* - While the seizure likely *started* in the left occipital lobe due to the visual aura, the subsequent loss of awareness, automatisms, and postictal confusion indicate that the seizure activity did not remain *isolated* to this region but spread to other brain areas. - An isolated occipital lobe seizure without spread would typically present as only visual symptoms without altered consciousness or automatisms. *Episodes with 3-4 hertz spike and wave discharges* - This **EEG pattern** is pathognomic for **absence seizures** (also known as petit mal seizures), which typically manifest as brief, sudden lapses of consciousness without a clear aura or the complex automatisms described. - The patient's presentation with a visual aura, postictal confusion, and repeated swallowing is inconsistent with absence seizures. *Demonstrates quick and repetitive jerks of extremities* - This describes the **clonic phase** of a **tonic-clonic seizure** or **myoclonic seizures**. - The patient's friend described staring into space and repeated swallowing (automatisms), not quick, repetitive jerking of extremities.

Question 40: A 28-year-old man presents to the emergency department with lower extremity weakness. He was in his usual state of health until 10 days ago. He then began to notice his legs were “tiring out” during his workouts. This progressed to difficulty climbing the stairs to his apartment. He has asthma and uses albuterol as needed. He has no significant surgical or family history. He smokes marijuana daily but denies use of other recreational drugs. He is sexually active with his boyfriend of 2 years. He has never traveled outside of the country but was camping 3 weeks ago. He reports that he had diarrhea for several days after drinking unfiltered water from a nearby stream. On physical examination, he has 1/5 strength in his bilateral lower extremities. He uses his arms to get up from the chair. Achilles and patellar reflexes are absent. A lumbar puncture is performed, and results are as shown below: Cerebral spinal fluid: Color: Clear Pressure: 15 cm H2O Red blood cell count: 0 cells/µL Leukocyte count: 3 cells/ µL with lymphocytic predominance Glucose: 60 mg/dL Protein: 75 mg/dL A culture of the cerebral spinal fluid is pending. Which of the following is the part of the management for the patient’s most likely diagnosis?

A. Aspirin
B. Intravenous methylprednisolone
C. Plasmapheresis (Correct Answer)
D. Doxycycline
E. Azithromycin

Explanation: ***Plasmapheresis*** - The patient exhibits classic signs of **Guillain-Barré Syndrome (GBS)**: **ascending paralysis** starting in the lower extremities, progression over days to weeks, and **areflexia**. - The **CSF findings** of **elevated protein** with normal cell count (**albuminocytologic dissociation**) are characteristic of GBS. Plasmapheresis is a first-line treatment, as it removes pathogenic autoantibodies from the plasma. *Aspirin* - **Aspirin** is an antiplatelet agent used for cardiovascular disease prevention or acute ischemic events. - It has no role in the treatment of GBS, which is an autoimmune demyelinating polyneuropathy. *Intravenous methylprednisolone* - While corticosteroids like **methylprednisolone** are used for some autoimmune conditions, they have been shown to be **ineffective** and potentially harmful in GBS. - The primary treatments for GBS are **intravenous immunoglobulin (IVIG)** and **plasmapheresis**. *Doxycycline* - **Doxycycline** is a broad-spectrum antibiotic commonly used for bacterial infections like Lyme disease, rickettsial infections, and some STIs. - It is not indicated for the autoimmune pathophysiology of GBS. *Azithromycin* - **Azithromycin** is a macrolide antibiotic frequently used for respiratory tract infections and certain sexually transmitted infections. - It has no therapeutic benefit in the management of GBS.

Question 41: A 77-year-old man presents to his primary care physician with lightheadedness and a feeling that he is going to "pass out". He has a history of hypertension that is treated with captopril. In the office, his temperature is 38.3°C (100.9°F), the pulse is 65/min, and the respiratory rate is 19/min. His sitting blood pressure is 133/91 mm Hg. Additionally, his supine blood pressure is 134/92 mm Hg and standing blood pressure is 127/88 mm Hg. These are similar to his baseline blood pressure measured during previous visits. An ECG rhythm strip is obtained in the office. Of the following, what is the likely cause of his presyncope?

A. Left bundle branch block
B. Hypertension
C. Captopril (Correct Answer)
D. Right bundle branch block
E. Orthostatic hypotension

Explanation: ***Captopril*** - While **ACE inhibitors** like captopril can cause **vasodilation** and **hypotension** leading to presyncope, this patient's blood pressure readings are **stable and normal** (133/91, 134/92, 127/88 mmHg). - There is **no evidence of hypotension** that would explain the presyncope, making captopril an unlikely direct cause in this presentation. - **Note**: The clinical scenario of fever (38.3°C) with relative bradycardia (pulse 65/min) and presyncope actually suggests a **cardiac arrhythmia** (such as high-degree AV block), especially given that an ECG was obtained. However, this is not among the answer choices. *Left bundle branch block* - LBBB is an electrical conduction abnormality that typically does not directly cause presyncope unless it progresses to **high-degree AV block** or causes significant hemodynamic compromise. - In the context of fever and relative bradycardia, if LBBB were associated with a bradyarrhythmia causing hemodynamic instability, it could contribute to presyncope. - However, without the ECG findings mentioned in the stem, this cannot be confirmed. *Hypertension* - The patient's blood pressure is well-controlled and stable (ranging from 127-134/88-92 mmHg). - Hypertension itself does not cause presyncope; in fact, **hypotension** (not hypertension) causes presyncope due to reduced cerebral perfusion. - This is not the cause of his symptoms. *Right bundle branch block* - RBBB is generally **asymptomatic** and does not cause hemodynamic instability or presyncope. - It is an incidental finding in most cases and would not explain the patient's symptoms of lightheadedness and near-syncope. *Orthostatic hypotension* - Orthostatic hypotension requires a drop in systolic BP ≥20 mmHg or diastolic BP ≥10 mmHg within 3 minutes of standing. - This patient's BP changes from supine to standing (134/92 → 127/88 mmHg) show only a **7/4 mmHg drop**, which does **not meet diagnostic criteria**. - Orthostatic hypotension is ruled out by the blood pressure measurements provided.

Question 42: A 24-year-old woman comes to the physician for a routine health maintenance examination. She feels well. On questioning, she has had occasional morning dizziness and palpitations during the past year. She is a graduate student. She does not smoke and drinks 1–2 glasses of wine on the weekends. Her vital signs are within normal limits. Physical examination shows an irregular pulse. On auscultation of the chest, S1 and S2 are normal and there are no murmurs. An ECG is shown. Which of the following is the most appropriate next step in management?

A. Reassurance (Correct Answer)
B. Event recorder implantation
C. Administration of flecainide
D. Administration of metoprolol
E. Stress echocardiography

Explanation: ***Reassurance*** - This young, healthy patient has **occasional, mild symptoms** (morning dizziness and palpitations) with stable vital signs and a normal cardiac examination except for an irregular pulse. - The ECG shown likely demonstrates **benign ectopy** such as premature atrial contractions (PACs) or premature ventricular contractions (PVCs), which are common in young adults and typically benign. - In the absence of **red flags** (syncope, family history of sudden cardiac death, structural heart disease, hemodynamic instability), reassurance is appropriate for asymptomatic or minimally symptomatic patients with benign arrhythmias. - No intervention is needed unless symptoms become more severe or frequent. *Event recorder implantation* - An event recorder would be considered if the patient had **significant symptoms** (syncope, presyncope) or if the routine ECG was **normal** and there was a need to capture intermittent arrhythmias. - Since an ECG was obtained during the visit showing the irregular rhythm, further rhythm monitoring is not the next step unless the diagnosis remains unclear or symptoms worsen. - This represents overinvestigation for likely benign ectopy in a young, healthy patient. *Administration of flecainide* - Flecainide is a **Class IC antiarrhythmic** used for specific arrhythmias like atrial fibrillation or supraventricular tachycardia. - It should never be initiated without a clear diagnosis and is **contraindicated** in patients with structural heart disease due to proarrhythmic risk. - Empiric antiarrhythmic therapy is not warranted for occasional, mild symptoms with likely benign ectopy. *Administration of metoprolol* - Metoprolol is a **beta-blocker** that can reduce the frequency of ectopic beats and control heart rate in certain arrhythmias. - While it could be considered if symptoms were bothersome despite reassurance, it is not the first-line approach for a minimally symptomatic patient with benign ectopy. - Medical therapy should be reserved for patients with significant symptoms affecting quality of life. *Stress echocardiography* - Stress echocardiography evaluates for **exercise-induced ischemia** or valvular abnormalities provoked by exertion. - This patient has no symptoms of angina, dyspnea, or features suggesting structural heart disease on examination. - There is no indication for stress testing in a young patient with isolated benign ectopy and no cardiovascular risk factors.

Question 43: A 62-year-old woman presents to the emergency department complaining of fever, worsening fatigue, and muscle weakness for the previous 48 hours. The patient describes her muscle weakness as symmetric and worse in the upper limbs. Her past medical history is significant for long-standing diabetes type 2 complicated by stage 5 chronic kidney disease (CKD) on hemodialysis. She takes lisinopril, verapamil, metformin, and glargine. Today, the patient’s vital signs include: temperature 38.6°C (101.5°F), pulse 80/min, blood pressure 155/89 mm Hg, respirations 24/min, and 95% oxygen saturation on room air. The cardiac and pulmonary exams are unremarkable. The abdomen is soft and non-tender. Her strength is 3/5 in the upper extremities and 4/5 in the lower extremities and her sensation is intact. Deep tendon reflexes are absent in both the upper and lower limbs. A 12-lead electrocardiogram (ECG) is shown in the image below. Blood work is drawn and the patient is admitted and started on continuous cardiac monitoring. Based on the available information, what is the next best step in managing this patient?

A. Order a stat serum potassium level
B. Administer IV calcium gluconate (Correct Answer)
C. Emergency dialysis
D. Administer IV sodium bicarbonate
E. Administer regular insulin and 50% dextrose in water

Explanation: ***Administer IV calcium gluconate*** - The patient's presentation with **symmetrical muscle weakness** (worse in upper limbs), **absent deep tendon reflexes**, and characteristic ECG changes (peaked T waves, prolonged PR interval, wide QRS) in the context of **end-stage renal disease** and hemodialysis strongly suggests **severe hyperkalemia**. - **Intravenous calcium gluconate** is the first-line treatment for clinically significant hyperkalemia with ECG changes, as it directly antagonizes the cardiac membrane effects of potassium and helps to stabilize the myocardium. *Order a stat serum potassium level* - While it is crucial to confirm hyperkalemia with a **stat serum potassium level**, the clinical picture (CKD, hemodialysis, muscle weakness, absent reflexes, and ECG changes) is emergent and highly suggestive of severe hyperkalemia. - Waiting for laboratory confirmation before administering calcium gluconate can delay life-saving treatment and is not the "next best step" when ECG changes are evident. *Emergency dialysis* - **Emergency dialysis** is an effective way to remove potassium from the body and is often needed in severe hyperkalemia, especially in ESRD patients. - However, **calcium gluconate** should be administered *immediately* to stabilize the cardiac membrane and prevent life-threatening arrhythmias, even before preparing for dialysis. *Administer IV sodium bicarbonate* - **Sodium bicarbonate** can shift potassium intracellularly, particularly in the setting of metabolic acidosis, but its effect is slower and less reliable than calcium in stabilizing cardiac membranes. - It is often used as an adjunct but not as the initial, most critical intervention for immediate cardiac stabilization in severe hyperkalemia. *Administer regular insulin and 50% dextrose in water* - **Insulin and dextrose** shift potassium into cells, thereby lowering serum potassium levels. This is an important step in managing hyperkalemia. - However, similar to sodium bicarbonate, its effect on serum potassium is not immediate enough to counteract the acute cardiotoxic effects, making **calcium gluconate** the priority for cardiac stabilization.

Question 44: A 64-year-old male presents to the emergency room complaining of chest pain. He reports a pressure-like sensation over his sternum that radiates into his jaw. The pain came on suddenly 2 hours ago and has been constant since then. His past medical history is notable for a stable abdominal aortic aneurysm, hypertension, diabetes, and hyperlipidemia. He takes aspirin, enalapril, spironolactone, atorvastatin, canagliflozin, and metformin. His temperature is 99.1°F (37.3°C), blood pressure is 155/85 mmHg, pulse is 115/min, and respirations are 22/min. On exam, he is diaphoretic and in moderate distress. He is admitted for further management and does well after initial stabilization. He is seen two days later by the admitting team. This patient is at increased risk for a complication that is characterized by which of the following?

A. Cardiac tamponade
B. Intra-cardiac shunt
C. Mitral insufficiency (Correct Answer)
D. Ventricular fibrillation
E. Friction rub

Explanation: ***Mitral insufficiency*** - The patient's presentation with **pressure-like chest pain radiating to the jaw**, diaphoresis, and risk factors (hypertension, diabetes, hyperlipidemia) is highly suggestive of an **acute myocardial infarction (MI)**. A common mechanical complication of an MI is **papillary muscle rupture or dysfunction**, leading to acute mitral insufficiency. - Papillary muscle rupture typically occurs **3-7 days post-MI** and is more common with **inferior wall MI** (affecting the posteromedial papillary muscle supplied by the posterior descending artery). - Mitral insufficiency significantly increases the risk of **heart failure and cardiogenic shock** due to regurgitant flow into the left atrium during systole, presenting with a new **holosystolic murmur** at the apex. *Cardiac tamponade* - This typically occurs due to accumulation of fluid in the **pericardial sac** from a **free wall rupture**, which is a catastrophic mechanical complication of MI. - Free wall rupture usually presents **acutely with profound cardiogenic shock and hemodynamic collapse** (Beck's triad: hypotension, muffled heart sounds, JVD). - The patient "does well after initial stabilization," making this less likely as the primary answer. *Intra-cardiac shunt* - A **ventricular septal defect (VSD)** from septal rupture is another mechanical complication of MI, typically occurring **3-7 days post-MI**. - VSD presents with a **new harsh holosystolic murmur** at the left sternal border, step-up in oxygen saturation from RA to RV, and signs of biventricular failure. - While possible, **mitral regurgitation is more common than VSD** as a post-MI mechanical complication (incidence ratio approximately 10:1). *Ventricular fibrillation* - **Ventricular fibrillation** is an **electrical complication** of MI, usually occurring in the **first 24-48 hours** after MI onset and leading to sudden cardiac arrest. - The patient "does well after initial stabilization" two days later, indicating he survived the acute period when ventricular fibrillation risk is highest. - The question asks about a complication he is at **increased risk for after initial stabilization**, pointing towards a **subacute mechanical complication** rather than an acute electrical one. *Friction rub* - A **pericardial friction rub** is a physical examination finding characteristic of **pericarditis**, which can occur as **early post-MI pericarditis** (24-96 hours) or **Dressler's syndrome** (weeks to months later). - A friction rub is a **sign** of pericarditis, not a complication itself. The question asks for a complication the patient is at risk for, not a physical examination finding. - Post-MI pericarditis is generally **benign** and does not carry the same morbidity as mechanical complications like mitral regurgitation.

Question 45: A 26-year-old nursing home staff presents to the emergency room with complaints of palpitations and chest pain for the past 2 days. She was working at the nursing home for the last year but has been trying to get into modeling for the last 6 months and trying hard to lose weight. She is a non-smoker and occasionally drinks alcohol on weekends with friends. On examination, she appears well nourished and is in no distress. The blood pressure is 150/84 mm Hg and the pulse is 118/min. An ECG shows absent P waves. All other physical findings are normal. What is the probable diagnosis?

A. Anorexia nervosa
B. Graves' disease
C. Hashimoto thyroiditis
D. Toxic nodular goiter
E. Factitious thyrotoxicosis (Correct Answer)

Explanation: ***Factitious thyrotoxicosis*** - The patient's profession as a nursing home staff member provides access to medications, and her attempts to lose weight for modeling suggest a motive for **self-administration of thyroid hormones**. - **Absent P waves** on ECG along with **palpitations and tachycardia** are consistent with atrial arrhythmias often seen in thyrotoxicosis, but the overall presentation with a desire for weight loss points towards an exogenous source. *Anorexia nervosa* - While patients with anorexia nervosa do try to lose weight, their presentation is typically associated with **bradycardia**, not the tachycardia and elevated blood pressure seen here. - ECG findings in anorexia nervosa would more likely show **QT prolongation** or other conduction abnormalities due to electrolyte imbalances, not specifically absent P waves caused by arrhythmia. *Graves' disease* - Graves' disease is an autoimmune condition causing hyperthyroidism, presenting with similar symptoms like **tachycardia and palpitations**. However, it is typically associated with other systemic findings such as **ophthalmopathy (exophthalmos)**, **pretibial myxedema**, or a palpable goiter, none of which are mentioned. - Laboratory findings would show **high T3/T4** with **low TSH**, and often **positive TSH receptor antibodies**, differentiating it from factitious causes. *Hashimoto thyroiditis* - Hashimoto thyroiditis is an **autoimmune cause of hypothyroidism**, characterized by fatigue, weight gain, and bradycardia, which are opposite to the patient's symptoms of palpitations, tachycardia, and weight loss efforts. - While it can initially present with transient hyperthyroidism (hashitoxicosis), the chronic state is hypothyroidism, and the ECG would not typically show absent P waves. *Toxic nodular goiter* - A toxic nodular goiter causes hyperthyroidism due to **autonomous thyroid nodules**, leading to symptoms similar to Graves' disease (palpitations, weight loss). - However, the physical examination would usually reveal a **palpable nodular goiter**, which is not mentioned in this case, making it a less likely diagnosis compared to factitious thyrotoxicosis given the context.

Question 46: A 29-year-old woman with Wolff-Parkinson-White syndrome presents to her cardiologist’s office for a follow-up visit. She collapsed at her job and made a trip to the emergency department 1 week ago. At that time, she received a diagnosis of atrial fibrillation with rapid ventricular response and hemodynamic instability. While in the emergency department, she underwent direct-current cardioversion to return her heart to sinus rhythm. Her current medications include procainamide. At the cardiologist’s office, her heart rate is 61/min, respiratory rate is 16/min, the temperature is 36.5°C (97.7°F), and blood pressure is 118/60 mm Hg. Her cardiac examination reveals a regular rhythm and a I/VI systolic ejection murmur best heard at the right upper sternal border. An ECG obtained in the clinic is shown. Which of the following is the most appropriate treatment to prevent further episodes of tachyarrhythmia?

A. Begin anticoagulation with dabigatran
B. Add verapamil to her medication regimen
C. Begin anticoagulation with warfarin
D. Refer her for electrophysiology (EP) study and ablation (Correct Answer)
E. Refer her for right heart catheterization

Explanation: ***Refer her for electrophysiology (EP) study and ablation*** - This patient has **Wolff-Parkinson-White (WPW) syndrome** and experienced a life-threatening episode of **atrial fibrillation with rapid ventricular response (AFib with RVR)** and **hemodynamic instability**, indicating a high-risk accessory pathway. - **Catheter ablation** of the accessory pathway is the definitive treatment to eliminate the re-entrant circuit and prevent future tachyarrhythmia episodes and sudden cardiac death in symptomatic WPW patients. *Begin anticoagulation with dabigatran* - While anticoagulation is indicated for stroke prevention in AFib, this patient's primary risk is not stroke but rather recurrent, potentially fatal, **tachyarrhythmias due to WPW**. - Current guidelines suggest that anticoagulation is not routinely needed for AFib in the setting of WPW unless other risk factors for stroke are present (e.g., high **CHA₂DS₂-VASc score** for non-valvular AFib), which are not mentioned here for a 29-year-old. *Add verapamil to her medication regimen* - **Calcium channel blockers** like verapamil are contraindicated in WPW syndrome with AFib. - They can block the normal AV nodal conduction, shunting more impulses down the **accessory pathway** and potentially accelerating the ventricular rate, leading to **ventricular fibrillation**. *Begin anticoagulation with warfarin* - Similar to dabigatran, anticoagulation with warfarin is primarily for **stroke prevention in AFib**, not for preventing the tachyarrhythmia itself in WPW. - The immediate and most critical concern for this patient is the risk of recurrent, life-threatening **re-entrant tachyarrhythmias** via the accessory pathway. *Refer her for right heart catheterization* - A **right heart catheterization** is used to measure pressures and oxygen saturations in the right side of the heart and pulmonary arteries, typically to evaluate for conditions like pulmonary hypertension or heart failure. - It is not indicated for the diagnosis or treatment of **supraventricular tachycardias** or **accessory pathways** like in WPW syndrome.

Question 47: A 73-year-old man noted a rapid onset of severe dizziness and difficulty swallowing while watching TV at home. His wife reports that he had difficulty forming sentences and his gait was unsteady at this time. Symptoms were severe within 1 minute and began to improve spontaneously after 10 minutes. He has had type 2 diabetes mellitus for 25 years and has a 50 pack-year smoking history. On arrival to the emergency department 35 minutes after the initial development of symptoms, his manifestations have largely resolved with the exception of a subtle nystagmus and ataxia. His blood pressure is 132/86 mm Hg, the heart rate is 84/min, and the respiratory rate is 15/min. After 45 minutes, his symptoms are completely resolved, and neurological examination is unremarkable. Which of the following is the most likely cause of this patient’s condition?

A. Anterior cerebral artery occlusion
B. Middle cerebral artery occlusion
C. Posterior cerebral artery occlusion
D. Lenticulostriate artery occlusion
E. Vertebral artery occlusion (Correct Answer)

Explanation: ***Vertebral artery occlusion*** - The patient's symptoms of **severe dizziness**, **difficulty swallowing**, **dysarthria**, **unsteady gait**, **nystagmus**, and **ataxia** are classic manifestations of **posterior circulation ischemia**, which is supplied by the vertebral and basilar arteries. - The rapid onset, transient nature, and complete resolution of symptoms suggest a **transient ischemic attack (TIA)** affecting the posterior cerebral circulation, often due to **vertebral artery stenosis** or a **vertebral artery embolus**. *Anterior cerebral artery occlusion* - Occlusion of the anterior cerebral artery typically causes **contralateral leg weakness**, sensory loss, and behavioral changes, which are not seen in this patient. - Symptoms like dizziness and dysphagia are **not characteristic** of anterior cerebral artery involvement. *Middle cerebral artery occlusion* - Middle cerebral artery occlusion commonly presents with **contralateral arm and facial weakness**, aphasia (if the dominant hemisphere is affected), and visual field defects. - The patient's symptoms are localized to the **brainstem/cerebellum**, not the MCA territory. *Posterior cerebral artery occlusion* - While the posterior cerebral artery is part of the posterior circulation, its occlusion primarily causes **contralateral homonymous hemianopia** and, if severe, memory deficits or alexia. - It typically **does not cause severe dizziness**, dysphagia, or gait ataxia as prominent initial symptoms. *Lenticulostriate artery occlusion* - Lenticulostriate arteries supply deep structures like the **basal ganglia** and **internal capsule**. Occlusion typically leads to **pure motor** or **pure sensory lacunar strokes**. - This patient's constellation of symptoms (dizziness, dysphagia, ataxia) is **too widespread for a typical lacunar infarct** in the lenticulostriate territory.

Question 48: A 22-year-old immigrant presents to his primary care physician for a general checkup. This is his first time visiting a physician, and he has no known past medical history. The patient’s caretaker states that the patient has experienced episodes of syncope and what seems to be seizures before but has not received treatment. His temperature is 98.1°F (36.7°C), blood pressure is 121/83 mmHg, pulse is 83/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam is notable for sensorineural deafness. Which of the following ECG changes is most likely to be seen in this patient?

A. Increased voltages
B. Prolonged QRS interval
C. QT shortening
D. Prolonged QT interval (Correct Answer)
E. Peaked T waves

Explanation: **Prolonged QT interval** - The patient's history of **syncope** and **seizures** without treatment, coupled with **sensorineural deafness**, strongly suggests **Jervell and Lange-Nielsen syndrome (JLNS)**, a form of congenital long QT syndrome. - JLNS is characterized by a **prolonged QT interval** on ECG, which predisposes to life-threatening ventricular arrhythmias such as **Torsades de Pointes**, leading to syncope and sudden death. *Increased voltages* - Increased voltages on ECG usually indicate **ventricular hypertrophy**, which is not directly described by the patient's symptoms or suggestive of JLNS. - While some cardiac conditions can cause increased voltages, it's not the primary or most characteristic finding in the context of syncope, seizures, and deafness associated with long QT syndrome. *Prolonged QRS interval* - A prolonged QRS interval typically signifies a **conduction delay within the ventricles**, such as a bundle branch block or ventricular preexcitation. - This is distinct from a prolonged QT interval, which relates to the duration of ventricular repolarization and is the hallmark of conditions like JLNS. *QT shortening* - **Short QT syndrome** is a rare inherited channelopathy characterized by a pathologically short QT interval, which can also cause syncope and sudden cardiac death. - However, the combination of **sensorineural deafness** specifically points towards **Jervell and Lange-Nielsen syndrome**, a form of **long QT syndrome**. *Peaked T waves* - **Peaked T waves** are often associated with **hyperkalemia** or **myocardial ischemia**. - These are not typical findings in congenital long QT syndromes like JLNS, where the primary abnormality is in the duration of the QT interval.

Question 49: A 68-year-old man presents to the emergency department with palpitations. He also feels that his exercise tolerance has reduced over the previous week. His past history is positive for ischemic heart disease and he has been on multiple medications for a long time. On physical examination, his temperature is 36.9°C (98.4°F), pulse rate is 152/min and is regular, blood pressure is 114/80 mm Hg, and respiratory rate is 18/min. Auscultation of the precordial region confirms tachycardia, but there is no murmur or extra heart sounds. His ECG is obtained, which suggests a diagnosis of atrial flutter. Which of the following findings is most likely to be present on his electrocardiogram?

A. Wenckebach phenomenon
B. Slurred upstroke of R wave
C. Atrial rate above 400 beats per minute
D. No discernible P waves
E. Atrioventricular block (Correct Answer)

Explanation: ***Atrioventricular block*** - In **atrial flutter**, the atria consistently beat at a very rapid rate (typically 250-350 bpm), while the **AV node** cannot conduct all of these impulses. - This physiological limitation leads to a **varying degree of AV block** (e.g., 2:1, 3:1, 4:1 block), resulting in a slower, often regular, ventricular response. *Wenckebach phenomenon* - This is a type of **second-degree AV block** (Mobitz Type I) characterized by progressive lengthening of the PR interval until a QRS complex is dropped. - While it is an **AV conduction abnormality**, it is not the primary manifestation seen in typical atrial flutter, where the AV block is usually fixed ratio or consistent block. *Slurred upstroke of R wave* - A **slurred upstroke of the R wave** (delta wave) is characteristic of **Wolff-Parkinson-White (WPW) syndrome**, which involves an accessory pathway. - While atrial flutter can occur in patients with WPW, the **delta wave** itself is indicative of pre-excitation, not a defining feature of the atrial flutter rhythm itself. *Atrial rate above 400 beats per minute* - An atrial rate above 400 bpm is generally indicative of **atrial fibrillation**, where the atrial activity is chaotic and extremely rapid. - In **atrial flutter**, the typical atrial rate is between **250-350 bpm**, characterized by organized, distinct "sawtooth" flutter waves. *No discernible P waves* - The absence of discernible P waves is a hallmark of **atrial fibrillation**, where the atrial activity is irregular and chaotic, leading to fibrillatory waves. - In **atrial flutter**, distinct and organized **"sawtooth" flutter waves** are present, which represent rapid, regular atrial depolarization, not an absence of P waves.

Question 50: A 56-year-old man with chronic kidney failure is brought to the emergency department by ambulance after he passed out during dinner. On presentation, he is alert and complains of shortness of breath as well as chest palpitations. An EKG is obtained demonstrating an irregular rhythm with QRS amplitudes that vary in height over time. Other findings include uncontrolled contractions of his muscles. Tapping of his cheek elicits twitching of the facial muscles. Over-repletion of the serum abnormality in this case may lead to which of the following?

A. Peaked T-waves
B. Seizures
C. Diffuse calcifications
D. Kidney stones (Correct Answer)
E. Bradycardia

Explanation: ***Kidney stones*** - The patient exhibits symptoms of **hypocalcemia**, including neuromuscular irritability (**muscle contractions**) and cardiac arrhythmias (**QT amplitudes varying in height**), in the context of chronic kidney failure. Chronic kidney failure can lead to **hyperphosphatemia**, which drives calcium out of solution, causing hypocalcemia. **Treating hypocalcemia** can involve oral calcium supplements. Over-repletion of calcium can lead to **hypercalcemia** and subsequently increase the risk of **calcium oxalate kidney stones**. - **Hypercalcemia** can result from aggressive or prolonged calcium supplementation in an attempt to correct hypocalcemia, especially in patients with impaired renal calcium excretion. Increased filtered calcium load in the kidneys increases the likelihood of stone formation. *Peaked T-waves* - **Peaked T-waves** are characteristic of **hyperkalemia**, not hypercalcemia. While chronic kidney failure can cause hyperkalemia, this question describes the consequences of over-repleting the serum abnormality (hypocalcemia) with calcium. - While electrolyte imbalances can coexist in CKD, this option does not describe a direct consequence of overtreating hypocalcemia. *Seizures* - **Seizures** can be a symptom of severe **hypocalcemia**, but they are not typically caused by **hypercalcemia** (over-repletion of calcium). - While alterations in calcium levels can affect neurological function, over-repletion leading to hypercalcemia is more commonly associated with lethargy, confusion, or coma, rather than an increased risk of seizures. *Diffuse calcifications* - **Diffuse calcifications**, such as **vascular calcification** or **calciphlaxis**, are severe complications often seen in advanced chronic kidney disease due to complex disturbances in calcium-phosphate metabolism, including hyperphosphatemia and secondary hyperparathyroidism. However, they are not primarily a direct result of simple over-repletion of calcium for hypocalcemia in the short-term clinical scenario described. - While chronic hypercalcemia can contribute to calcifications, the prompt scenario of "over-repletion" leading to a new acute issue points more towards kidney stones. *Bradycardia* - Varying QT amplitudes indicate an excitable state, which is inconsistent with **bradycardia**. While severe hypercalcemia can cause some EKG changes, it is not typically associated with bradycardia but rather with a **shortened QT interval** and, in severe cases, potentially some heart block. - Bradycardia is more commonly associated with conditions like **hyperkalemia** or certain cardiac diseases, rather than the effects of calcium over-repletion.

Question 51: A 59-year-old man presents to the emergency department with right-sided weakness and an inability to speak for the past 2 hours. His wife says he was gardening in his backyard when he suddenly lost balance and fell down. The patient has a past medical history of hypertension, diabetes mellitus, and coronary artery disease. Two years ago, he was admitted to the coronary intensive care unit with an anterolateral myocardial infarction. He has not been compliant with his medications since he was discharged. On physical examination, his blood pressure is 110/70 mm Hg, pulse is 110/min and irregular, temperature is 36.6°C (97.8°F), and respiratory rate is 18/min. Strength is 2/5 in both his right upper and right lower extremities. His right calf is edematous with visible varicose veins. Which of the following is the best method to detect the source of this patient’s stroke?

A. Carotid duplex
B. Head CT without contrast
C. V/Q scan of his lungs
D. ECG (Correct Answer)
E. Duplex ultrasound of his right leg

Explanation: ***ECG*** - The patient's presentation with **sudden focal neurological deficits** (right-sided weakness, inability to speak) points to an **acute ischemic stroke**. His **irregular pulse** and history of **anterolateral myocardial infarction** suggest a cardiac source for an embolism. - An **ECG** can quickly identify **atrial fibrillation (Afib)**, a common cause of cardioembolic stroke due to thrombus formation in the left atrium, especially given his **irregular pulse** and history of cardiac disease. *Carotid duplex* - While **carotid artery stenosis** can cause ischemic stroke, it typically presents with a **carotid bruit** on examination and is often associated with transient ischemic attacks (TIAs) with similar symptoms. - The sudden onset of symptoms with a prominent cardiac history and irregular pulse makes a cardioembolic stroke more likely than carotid stenosis as the immediate source. *Head CT without contrast* - A **head CT without contrast** is crucial for an acute stroke workup to **rule out hemorrhagic stroke** before administering thrombolytics. - However, it does not identify the **source of an ischemic stroke**, only the acute brain changes. *V/Q scan of his lungs* - A **V/Q scan (Ventilation-Perfusion scan)** is used to detect **pulmonary embolism**, not the source of an ischemic stroke. - While a **paradoxical embolism** through a patent foramen ovale (PFO) from a venous thrombus can cause stroke, a V/Q scan would not directly identify this. *Duplex ultrasound of his right leg* - A **duplex ultrasound of the right leg** would identify a **deep venous thrombosis (DVT)** in his edematous calf. - While a DVT could be the source of a **paradoxical embolism** in the presence of a right-to-left shunt like a PFO, the prominent **irregular pulse** strongly points to a **cardiac source** as the primary investigation.

Question 52: A 33-year-old man presents to the emergency department with severe anxiety. He has had multiple episodes in the past treated with low dose lorazepam. The patient states that he feels as if he is going to die and that he cannot breathe. His past medical history is notable for depression and anxiety. His temperature is 98.1°F (36.7°C), blood pressure is 122/83 mmHg, pulse is 153/min, respirations are 13/min, and oxygen saturation is 98% on room air. The patient is given a low dose of lorazepam and reports a complete resolution of his symptoms. An ECG is performed and demonstrates prolongation of the P-R interval. There is a P wave preceding every QRS complex, no dropped QRS complexes, and the P-R interval does not change. His initial lab values are unremarkable. Which of the following is the best management of this patient?

A. Electrophysiological studies
B. Transcutaneous pacing
C. No further management needed (Correct Answer)
D. Sodium bicarbonate
E. Cardiac catheterization

Explanation: ***No further management needed*** - The ECG findings describe a **first-degree AV block**, which is a **benign condition** and typically does not require intervention in asymptomatic patients. - The patient's symptoms resolved completely with lorazepam, indicating his anxiety as the primary issue, and the ECG findings are **incidental and not related** to his acute presentation. *Electrophysiological studies* - These studies are typically reserved for **symptomatic arrhythmias**, higher-degree AV blocks (second or third degree), or suspected **accessory pathways** not evident here. - Given the patient's resolution of symptoms with an anxiolytic and the benign nature of first-degree AV block, **invasive studies** are not indicated. *Transcutaneous pacing* - **Pacing** is indicated for **symptomatic bradyarrhythmias** or **high-degree AV blocks** causing hemodynamic instability. - The patient is **hemodynamically stable**, his heart rate is elevated due to anxiety (tachycardia), and a first-degree AV block does not typically cause severe bradycardia requiring pacing. *Sodium bicarbonate* - **Sodium bicarbonate** is primarily used to treat **metabolic acidosis** or certain drug toxicities (e.g., tricyclic antidepressant overdose leading to QRS widening and arrhythmias). - There is **no indication of acidosis** or specific drug overdose in this patient, and first-degree AV block is not managed with sodium bicarbonate. *Cardiac catheterization* - **Cardiac catheterization** is an invasive procedure typically used to diagnose and treat **coronary artery disease** or evaluate **structural heart abnormalities**. - There is no clinical or ECG evidence suggesting **ischemic heart disease** or significant structural issues that would warrant catheterization.

Question 53: A 51-year-old man is brought to the local emergency room in severe respiratory distress. The patient is an industrial chemist and was working in his lab with a new partner when a massive chemical spill occurred releasing fumes into their workspace. The patient and his lab partner attempted to clean up the spill before they realized it was too large for them to handle. They were not wearing protective equipment at the time, except for a pair of goggles. The fumes caused them both to begin coughing; however, this patient has a history significant for asthma. His condition worsened, which prompted lab management to call for an ambulance. On arrival at the emergency room, the patient’s respiratory rate is 42/min and oxygen saturation is 96% on room air. He is unable to speak on account of his coughing. He is clearly using accessory muscles with inspiration. A pulmonary exam reveals bilateral wheezes. He is given multiple nebulizer treatments of albuterol and is started on intravenous (IV) methylprednisolone. After 2 successive nebulizer treatments, the arterial blood gas test result shows pH 7.36, partial pressure of carbon dioxide (PCO2) 41 mm Hg, and partial pressure of oxygen (PO2) 79 mm Hg. He is now able to speak and the respiratory rate is 32/min. Which of the following is the best next step in this patient’s management?

A. Switch from nebulized albuterol to nebulized ipratropium
B. Continue to administer albuterol (Correct Answer)
C. Intubate the patient and begin mechanical ventilation
D. Administer IV prednisone in addition to IV methylprednisolone
E. Administer IV epinephrine

Explanation: ***Continue to administer albuterol*** - The patient shows **partial improvement** (decreased respiratory rate from 42 to 32/min, able to speak) but **respiratory distress persists** (RR still elevated, ongoing tachypnea). - **Albuterol (short-acting beta-agonist)** is the **cornerstone of acute asthma management** and should be continued until bronchospasm resolves. - The patient is responding to treatment, so the current management strategy should be maintained with continued bronchodilator therapy. - ABG shows acceptable oxygenation (PO2 79 mm Hg) and ventilation (PCO2 41 mm Hg, pH 7.36), indicating no immediate need for escalation to intubation. *Switch from nebulized albuterol to nebulized ipratropium* - While **ipratropium (anticholinergic)** can be used as an **adjunct to albuterol** in severe asthma, **switching entirely from albuterol is inappropriate**. - **Albuterol remains the primary bronchodilator** and should be continued as the patient is responding to it. *Intubate the patient and begin mechanical ventilation* - **Intubation is reserved** for patients with **worsening respiratory failure** despite maximal medical therapy, altered mental status, or inability to protect the airway. - This patient demonstrates **clinical improvement** with current treatment, making intubation unnecessary at this time. - Signs that would warrant intubation include: declining mental status, worsening hypoxemia, rising PCO2, or respiratory arrest. *Administer IV prednisone in addition to IV methylprednisolone* - Both medications are **corticosteroids** with similar mechanisms of action. - Administering both simultaneously provides **no additional therapeutic benefit** and only increases the risk of corticosteroid-related adverse effects. - The patient is already receiving appropriate systemic corticosteroid therapy with **IV methylprednisolone**. *Administer IV epinephrine* - **IV or IM epinephrine** is the treatment of choice for **anaphylaxis**, not routine asthma exacerbations. - While epinephrine has bronchodilatory effects, it carries **higher cardiovascular risks** (tachycardia, arrhythmias, hypertension) compared to inhaled albuterol. - Epinephrine in asthma is typically reserved for **life-threatening bronchospasm unresponsive to standard therapy**.

Question 54: An 80-year-old woman presents to her cardiologist for a scheduled appointment. She was shown to have moderate atrial dilation on echocardiography 3 years ago and was started on oral medications. The patient insists that she does not want aggressive treatment because she wants her remaining years to be peaceful. She has not been compliant with her medications and declines further investigations. Her heart rate today is 124/min and irregular. Which of the following organs is least likely to be affected by complications of her condition if she declines further management?

A. Kidneys
B. Spleen
C. Liver (Correct Answer)
D. Brain
E. Eyes

Explanation: ***Liver*** - While liver congestion can occur due to **right-sided heart failure**, it is less likely to be directly affected by systemic emboli originating from **atrial fibrillation** compared to organs with direct arterial supply vulnerable to clot formation. - The liver is relatively protected from embolic damage because it receives a dual blood supply from both the **hepatic artery** and the **portal vein**, making it less susceptible to infarction from a single embolic event. *Kidneys* - The kidneys can be significantly affected by **systemic emboli** originating from the left atrium in **atrial fibrillation**. - Renal emboli can cause **kidney infarction**, acute kidney injury, or chronic kidney disease due to loss of nephron function. *Spleen* - The spleen is highly susceptible to damage from **systemic emboli** due to its rich arterial blood supply directly from the aorta. - Splenic infarction, characterized by **severe left upper quadrant pain**, is a common complication of emboli arising from **atrial fibrillation**. *Brain* - The brain is a primary target for complications of **atrial fibrillation**, with **ischemic stroke** being the most feared embolic event. - Emboli can travel from the left atrium to the cerebral circulation, leading to severe neurological deficits. *Eyes* - The eyes, specifically the **retinal arteries**, are vulnerable to **cardioembolic emboli** originating from the left atrium in atrial fibrillation. - Retinal artery occlusion can lead to sudden, painless **vision loss** or **amaurosis fugax**, making it a significant risk in patients with unmanaged atrial fibrillation.

Question 55: A 22-year-old man is brought to the emergency department 25 minutes after an episode of violent jerky movements of his arms and legs. He has no recollection of the episode. The episode lasted for 3–4 minutes. His girlfriend reports that he has not been sleeping well over the past month. He is only oriented to place and person. His temperature is 37°C (98.6°F), pulse is 99/min, respirations are 18/min, and blood pressure is 110/80 mm Hg. Neurologic examination shows no focal findings. A complete blood count as well as serum concentrations of glucose, electrolytes, and calcium are within the reference range. Urine toxicology screening is negative. An MRI of the brain shows no abnormalities. Which of the following is the most appropriate next step in management?

A. Lamotrigine
B. Lumbar puncture
C. Tilt table test
D. Electroencephalography (Correct Answer)
E. Lorazepam

Explanation: ***Electroencephalography*** - The patient experienced a **generalized tonic-clonic seizure** (violent jerky movements, postictal confusion, lack of recollection) despite normal labs and imaging. - **Electroencephalography (EEG)** is crucial for diagnosing the type of seizure and identifying underlying epileptiform activity to guide long-term management. *Lamotrigine* - **Lamotrigine** is an antiepileptic drug, but initiating medication at this point without a definitive **EEG diagnosis** is premature. - The first step after a new-onset, unprovoked seizure is to confirm the diagnosis and classify the seizure type. *Lumbar puncture* - A **lumbar puncture** is indicated if there's suspicion of **meningitis or encephalitis** (e.g., fever, nuchal rigidity, altered mental status not explained by postictal state), which are absent here. - The patient's vital signs are stable, and initial lab work is unremarkable, making infection less likely. *Tilt table test* - A **tilt table test** is used to investigate **syncope** or orthostatic hypotension, which typically involve transient loss of consciousness without tonic-clonic movements or a prolonged postictal state. - The patient's presentation with prominent motor activity and postictal confusion is inconsistent with syncope. *Lorazepam* - **Lorazepam** is a benzodiazepine used to **acutely terminate ongoing seizures** (status epilepticus) or manage acute seizure clusters. - The patient's seizure has already resolved, and he is now in the postictal phase, so Lorazepam is not indicated at this time.

Question 56: A 67-year-old woman comes to the emergency department 1 hour after her husband saw her faint shortly after getting out of bed from a nap. She regained consciousness within 30 seconds and was fully alert and oriented. She has had 2 similar episodes in the last 5 years, once while standing in line at the grocery store and once when getting out of bed in the morning. 24-hour Holter monitoring and echocardiography were unremarkable at her last hospitalization 1 year ago. She has hypertension, depression, and asthma. Current medications include verapamil, nortriptyline, and an albuterol inhaler as needed. Her temperature is 37°C (98.4°F), pulse is 74/min and regular, respirations are 14/min, blood pressure is 114/72 mm Hg when supine and 95/60 mm Hg while standing. Cardiopulmonary examination shows no abnormalities. Neurologic examination shows no focal findings. A complete blood count and serum concentrations of electrolytes, urea nitrogen, creatinine, and glucose are within the reference range. Bedside cardiac monitoring shows rare premature ventricular contractions and T-wave inversions in lead III. Which of the following is the most likely cause of this patient's symptoms?

A. Adrenal insufficiency
B. Cardiac arrhythmia
C. Structural cardiac abnormality
D. Autonomic dysfunction (Correct Answer)
E. Hemorrhagic blood loss

Explanation: ***Autonomic dysfunction*** - This patient's symptoms are highly suggestive of **orthostatic hypotension** due to **autonomic dysfunction**, characterized by recurrent syncopal episodes upon standing from a supine or seated position. - The drop in blood pressure from **114/72 mm Hg (supine)** to **95/60 mm Hg (standing)**, combined with the use of **verapamil** (a calcium channel blocker) and **nortriptyline** (a tricyclic antidepressant), both of which can exacerbate orthostatic hypotension, supports this diagnosis. *Adrenal insufficiency* - While adrenal insufficiency can cause **hypotension**, it typically presents with other systemic symptoms such as **fatigue**, **weight loss**, **hyperpigmentation**, and **electrolyte abnormalities**, none of which are noted here. - The patient's otherwise normal lab results and the specific triggers for syncope make adrenal insufficiency less likely. *Cardiac arrhythmia* - Although the patient has rare **premature ventricular contractions (PVCs)** and **T-wave inversions in lead III**, these findings are typically not sufficient to explain recurrent syncope over several years, especially given an unremarkable 24-hour Holter monitoring performed a year ago. - The syncopal episodes reliably occurring with position changes (standing) strongly point away from a primary arrhythmic cause. *Structural cardiac abnormality* - An **echocardiogram** performed a year ago was unremarkable, ruling out common structural causes of syncope such as **aortic stenosis**, **hypertrophic cardiomyopathy**, or **valvular disease**. - Without new symptoms or findings to suggest a recent development, a structural abnormality is unlikely. *Hemorrhagic blood loss* - Acute hemorrhagic blood loss would typically present with signs of **hypovolemia**, such as **tachycardia**, **pallor**, and a significant drop in **hemoglobin**, none of which are reported in this patient. - Her complete blood count is within the reference range, making this diagnosis highly improbable.

Question 57: A 71-year-old female is brought to the emergency room by her husband. The husband reports that they were taking a walk together one hour ago, when his wife experienced sudden, right arm and leg weakness. He noticed that she had slurred speech, and that she was not able to tell him where she was. The patient underwent an emergent CT scan, which was unremarkable, and was treated with tissue plasminogen activator (tPA). Which of the following EKG findings increases a patient's risk for this acute presentation?

A. Supraventricular tachycardia
B. Prolonged QT
C. Normal sinus rhythm
D. Atrial fibrillation (Correct Answer)
E. Atrial bigeminy

Explanation: ***Atrial fibrillation*** - **Atrial fibrillation (Afib)** is a major risk factor for **embolic stroke** due to the formation of thrombi in the left atrium, which can then dislodge and travel to the brain. - The patient's presentation of sudden **focal neurological deficits** (**right arm and leg weakness, slurred speech, disorientation**) is highly suggestive of an acute ischemic stroke, and Afib is a common cause in this age group. *Supraventricular tachycardia* - While supraventricular tachycardia (SVT) can cause symptoms like palpitations, dizziness, and syncope, it is **less commonly a direct cause of cardioembolic stroke** compared to atrial fibrillation. - The rapid heart rate in SVT typically leads to systemic symptoms rather than specific focal neurological deficits indicative of a stroke. *Prolonged QT* - A prolonged QT interval is primarily associated with an increased risk of developing **torsades de pointes**, a life-threatening ventricular arrhythmia. - It does not directly increase the risk of cardioembolic stroke by causing thrombus formation in the heart chambers. *Normal sinus rhythm* - **Normal sinus rhythm** indicates healthy electrical activity originating from the sinoatrial node, which is the heart's natural pacemaker. - Patients in normal sinus rhythm have a **baseline risk** of stroke, but it does not specifically increase the risk of cardioembolic stroke compared to arrhythmias like atrial fibrillation. *Atrial bigeminy* - Atrial bigeminy involves **premature atrial contractions (PACs)** occurring every other beat. While it can cause palpitations, it is generally considered a **benign arrhythmia**. - Unlike atrial fibrillation, atrial bigeminy typically **does not lead to significant stasis of blood** in the atria and therefore does not significantly increase the risk of cardioembolic stroke.

Question 58: A 57-year-old man comes to the emergency department with fatigue and palpitations for several weeks. An ECG shows atrial fibrillation. Echocardiography shows thrombus formation in the left atrium. Which of the following organs is most likely to continue to function in the case of an embolic event?

A. Liver (Correct Answer)
B. Brain
C. Colon
D. Kidney
E. Spleen

Explanation: ***Liver*** - The **liver** is uniquely supplied by two major blood vessels: the **hepatic artery** and the **portal vein**. - This **dual blood supply** provides a protective mechanism against ischemic damage from an embolic event in one of the vessels, as the other can often compensate. *Brain* - The **brain** is highly susceptible to embolic events, which can lead to a **stroke** due to interruption of blood flow to critical areas. - While the Circle of Willis provides some anastomotic connections, an embolus can still cause significant **cerebral ischemia** and neuronal death. *Colon* - The **colon** receives its blood supply from the superior and inferior mesenteric arteries, with limited collateral circulation in some areas (e.g., the watershed areas like the splenic flexure). - An embolic event can lead to **mesenteric ischemia** and potentially bowel infarction, a serious condition requiring immediate intervention. *Kidney* - The **kidneys** are end-organs with a rich but segmental arterial supply, primarily from the renal arteries. - An embolus occluding a renal artery or one of its major branches can cause a **renal infarct**, leading to loss of kidney function in the affected segment. *Spleen* - The **spleen** is supplied by the splenic artery, which is an end-artery with limited collateral blood flow. - Embolic occlusion of the splenic artery or its branches can result in a **splenic infarct**, causing pain and potential organ dysfunction.

Question 59: A 22-year-old medical student presents to a community health center due to an episode of loss of consciousness 3 days ago. She also has a history of multiple episodes of dizziness in the last year. These episodes almost always occur when she is observing surgery in the operating room. She describes her dizziness as a feeling of lightheadedness, warmth, excessive sweating, and palpitations. She feels that she will fall down if she stood longer and usually sits on the floor or leaves the room until the feeling subsides. Three days ago, she collapsed while observing an open cholecystectomy but regained consciousness after a few seconds. Once she regained consciousness, she was pale and sweating excessively. Her medical history is significant for migraines, but she is not on prophylactic therapy. Her younger brother has cerebral palsy, and her uncle had a sudden death at the age of 25. Her blood pressure is 120/80 mm Hg when lying down and 118/80 mm Hg when in a standing position. The rest of the physical examination is within normal limits. What is the next best step in the management of this patient?

A. Electroencephalogram (EEG)
B. MRI of the brain
C. Psychiatric evaluation for anxiety
D. Echocardiogram
E. Electrocardiogram (ECG) (Correct Answer)

Explanation: ***Electrocardiogram (ECG)*** - This patient presents with recurrent episodes of near-syncope and a recent syncopal episode, triggered by a stressful situation (observing surgery), along with a family history of **sudden death at a young age** (uncle at 25). These red flags suggest a possible **cardiac etiology** for her syncope, such as a **long QT syndrome** or other channelopathies, making an ECG the most crucial initial investigation. - An ECG is a **non-invasive, inexpensive, and readily available** test that can detect structural or electrical abnormalities of the heart that could predispose to arrhythmias and syncope. *Electroencephalogram (EEG)* - While loss of consciousness occurred, the clinical description of lightheadedness, warmth, sweating, and palpitations followed by syncope and quick recovery with post-recovery pallor and sweating is more consistent with **vasovagal syncope** or a cardiac cause, rather than a seizure. - The absence of typical seizure features such as **tonic-clonic movements**, post-ictal confusion, or tongue biting makes epilepsy less likely. *MRI of the brain* - **Brain imaging** is generally not indicated for the initial workup of syncope unless there are focal neurological deficits, head trauma, or other symptoms suggestive of a central nervous system pathology. - The patient's symptoms are classic for syncope and do not point to a **structural brain lesion** as the cause of her loss of consciousness. *Psychiatric evaluation for anxiety* - While anxiety can trigger vasovagal responses, the primary concern in this case, given the **recurrent nature of syncope** and the concerning **family history of sudden death**, is to rule out a potentially life-threatening cardiac cause before attributing it solely to psychological factors. - Attributing syncope to anxiety without a thorough cardiac workup could delay diagnosis of a serious underlying condition. *Echocardiogram* - An echocardiogram assesses the **heart's structure and function**, which is important in the workup of syncope. However, it is typically performed *after* an ECG, especially if the ECG reveals abnormalities suggesting a structural or electrical problem. - While it could be a subsequent step if the ECG is abnormal, the **ECG is the most immediate and informative initial step** for ruling out electrical cardiac issues.

Question 60: A 31-year-old woman with a history of anorexia nervosa diagnosed 2 years ago presents for follow up. She says that, although she feels some improvement with cognitive-behavioral therapy (CBT), she is still struggling with her body image and fears gaining weight. She says that for the past 3 weeks she has noticed her ankles are uncomfortably swollen in the mornings. She also mentions that she still is having intermittent menstruation; her last menstrual cycle was 4 months ago. The patient denies any suicidal ideations. She has no other significant past medical history. She denies any history of smoking, alcohol consumption, or recreational drug use. The patient’s vital signs include: temperature 37.0°C (98.6°F), pulse 55/min, blood pressure 100/69 mm Hg, and respiratory rate 18/min. Her body mass index (BMI) is 17.1 kg/m2, improved from 16.9 kg/m2, 6 months ago. Her physical examination is significant for an irregular heart rhythm on cardiopulmonary auscultation. There is also significant 3+ pitting edema in the lower extremities bilaterally. An ECG reveals multiple isolated premature ventricular contractions (PVCs) with 1 10-sec episode of bigeminy. Which of the following aspects of this patient’s history and physical examination would be the strongest indication for inpatient hospitalization?

A. Lower extremity edema
B. BMI of 17.1 kg/m2
C. Pulse 55/min
D. Amenorrhea
E. Bigeminy (Correct Answer)

Explanation: **Bigeminy** - The presence of **cardiac arrhythmias**, specifically **bigeminy** with PVCs, indicates significant cardiac instability and an increased risk of sudden cardiac death in anorexic patients. This is a medical emergency requiring urgent inpatient management. - Anorexia nervosa can lead to **electrolyte imbalances** (e.g., hypokalemia, hypomagnesemia) and structural heart changes, predisposing to potentially lethal arrhythmias. *Lower extremity edema* - While concerning, **peripheral edema** in anorexia nervosa is often multifactorial (e.g., refeeding syndrome, protein deficiency, poor venous return) and typically does not independently warrant inpatient hospitalization unless it's rapidly worsening or associated with severe organ dysfunction. - It is a symptom that needs to be addressed but is less immediately life-threatening compared to significant cardiac arrhythmias. *BMI of 17.1 kg/m2* - A BMI of 17.1 kg/m2 indicates that the patient is **underweight** and meets some criteria for anorexia nervosa, and while a low BMI often necessitates treatment, a BMI above 15 kg/m2 generally allows for outpatient management if other severe medical complications are absent, or if the patient is stable for outpatient care. - Although concerning, this BMI alone is not the strongest indication for inpatient hospitalization compared to acute cardiac instability. *Pulse 55/min* - A pulse of 55/min is considered **bradycardia**, which is common in anorexia nervosa due to metabolic stress and adaptation to low energy states. - While bradycardia below 50 bpm or symptomatic bradycardia may warrant intervention, a pulse of 55 bpm is not as acutely critical as complex cardiac arrhythmias like bigeminy. *Amenorrhea* - **Amenorrhea** (intermittent menstruation) is a common consequence of chronic malnutrition and hormonal dysregulation in anorexia nervosa. - Although it is a significant feature of the disease and a marker of severity, it is a chronic symptom that does not typically require immediate inpatient hospitalization on its own terms, but rather long-term nutritional and hormonal rehabilitation.

Question 61: A 58-year-old man complains of ascending weakness, palpitations, and abdominal pain. He has a history of hypertension, type II diabetes mellitus, diabetic retinopathy, and end-stage renal disease requiring dialysis. He denies any recent infection. Physical examination is notable for decreased motor strength in both his upper and lower extremities, intact cranial nerves, as well as decreased bowel sounds. On further questioning, the patient shares that he has been depressed, as he feels he may not be able to see his grandchildren grow due to his complicated medical course. This caused him to miss two of his dialysis appointments. Which of the following will mostly likely be found on electrocardiography?

A. Progressive PR prolongation, followed by a 'drop' in QRS
B. ST-segment elevation in leads II, III, and aVF
C. Diffuse PR segment depression and ST-segment deviations
D. S wave in lead I, Q wave in lead III, and inverted T wave in lead III
E. Peaked T-waves and shortened QT interval (Correct Answer)

Explanation: ***Peaked T-waves and shortened QT interval*** - The patient's presentation of **ascending weakness**, **palpitations**, **abdominal pain**, and **missed dialysis appointments** in the context of end-stage renal disease strongly suggests **hyperkalemia**. - **Peaked T-waves** (tall, narrow, symmetric T-waves) are the **earliest and most characteristic ECG finding** in hyperkalemia. - **Shortened QT interval** occurs due to accelerated repolarization from elevated potassium levels. - As hyperkalemia worsens, ECG changes progress to widened QRS, prolonged PR interval, loss of P waves, and eventually a sine wave pattern that can lead to cardiac arrest. - The missed dialysis appointments are the key factor causing potassium accumulation in this patient. *Progressive PR prolongation, followed by a 'drop' in QRS* - This description is characteristic of **Mobitz Type II (second-degree AV block)**, which is typically associated with structural conduction abnormalities in the His-Purkinje system rather than the electrolyte imbalances seen here. - While severe hyperkalemia can cause AV nodal dysfunction, a complete "drop" in QRS following PR prolongation is less specific than **peaked T-waves** for initial hyperkalemic changes. - The patient's acute presentation after missed dialysis points more specifically to hyperkalemia. *ST-segment elevation in leads II, III, and aVF* - This pattern indicates an **inferior wall myocardial infarction**, representing acute coronary occlusion typically of the right coronary artery. - While the patient has cardiovascular risk factors (diabetes, hypertension), his symptoms of **ascending weakness** (suggesting neuromuscular dysfunction) and **abdominal pain** with decreased bowel sounds are more consistent with hyperkalemia's effects on skeletal muscle and smooth muscle. - An acute MI would typically present with chest pain/pressure and diaphoresis rather than ascending paralysis. *Diffuse PR segment depression and ST-segment deviations* - **Diffuse PR segment depression** with widespread ST elevation is a classic ECG finding in **acute pericarditis**. - Pericarditis typically presents with positional chest pain (better when leaning forward), a friction rub, and often follows a viral illness. - The patient's presentation of ascending weakness and the specific history of missed dialysis makes hyperkalemia far more likely than pericarditis. *S wave in lead I, Q wave in lead III, and inverted T wave in lead III* - This constellation of ECG findings is known as the **S1Q3T3 pattern**, which is classically associated with **acute pulmonary embolism** causing right heart strain. - Pulmonary embolism typically presents with sudden dyspnea, pleuritic chest pain, and possibly hemoptysis. - The patient's symptoms of ascending weakness, abdominal pain, and decreased bowel sounds do not align with PE, making hyperkalemia the more probable diagnosis given his ESRD and missed dialysis.

Question 62: A 33-year-old African American woman presents to her primary care physician for a wellness checkup. She states that she has lost 20 pounds over the past 2 months yet has experienced an increased appetite during this period. She endorses hyperhidrosis and increased urinary volume and frequency. Physical exam is notable for an anxious woman and a regular and tachycardic pulse. Laboratory values are ordered as seen below. Serum: Na+: 139 mEq/L Cl-: 100 mEq/L K+: 4.3 mEq/L HCO3-: 25 mEq/L Ca2+: 12.2 mg/dL The patient's urine calcium level is elevated. Which of the following is the most likely diagnosis?

A. Sarcoidosis
B. Hyperparathyroidism
C. Malignancy
D. Familial hypercalcemic hypocalciuria
E. Hyperthyroidism (Correct Answer)

Explanation: ***Hyperthyroidism*** - The patient's symptoms of **weight loss with increased appetite**, **hyperhidrosis**, **tachycardia**, and **anxiety** are classic for hyperthyroidism. - While hypercalcemia can occur in hyperthyroidism due to **increased bone turnover**, the elevated urine calcium level helps distinguish it from other hypercalcemic causes, especially when PTH is suppressed, leading to increased calcium filtration and excretion. *Sarcoidosis* - Sarcoidosis causes hypercalcemia due to **granulomatous production of 1,25-dihydroxyvitamin D**, which enhances intestinal calcium absorption. - However, the patient's prominent **hypermetabolic symptoms** (weight loss with increased appetite, hyperhidrosis, tachycardia) are not typical primary manifestations of sarcoidosis, and there is no mention of other common sarcoidosis features like lung involvement, skin lesions, or lymphadenopathy. *Hyperparathyroidism* - Primary hyperparathyroidism leads to hypercalcemia through **excessive PTH secretion**, which increases bone resorption and renal calcium reabsorption. - While it causes hypercalcemia, it typically results in a **low or inappropriately normal urine calcium** (due to PTH-mediated reabsorption), which contradicts the patient's elevated urine calcium. *Malignancy* - Malignancy can cause hypercalcemia through mechanisms like **PTHrp production** (humoral hypercalcemia of malignancy) or **bone metastases**, leading to increased bone resorption. - While malignancy can cause weight loss and sometimes an increased metabolic rate, the constellation of symptoms including **increased appetite, hyperhidrosis, and prominent anxiety** points more strongly to a primary endocrine disorder like hyperthyroidism. *Familial hypercalcemic hypocalciuria* - This is a genetic disorder characterized by **gain-of-function mutations** in the calcium-sensing receptor, leading to inappropriately normal or high PTH and **hypercalcemia with low urine calcium excretion**. - The presence of **elevated urine calcium** in this patient directly rules out familial hypercalcemic hypocalciuria.

Question 63: A 45-year-old man presents to the emergency department with complaints of right-sided weakness and slurring of speech for 1 hour. There is no history of head trauma, myocardial infarction, recent surgery, gastrointestinal or urinary bleeding. He has hypertension, chronic atrial fibrillation, and a 20 pack-year cigarette smoking history. The medication list includes valsartan and rivaroxaban. The vital signs include: blood pressure 180/92 mm Hg, pulse 144/min and irregular, and temperature 37.2°C (99.0°F). On physical examination, there is a facial asymmetry with a deviation of angle of mouth to the left side on smiling. Muscle strength is reduced in both upper and lower limbs on the right side while on the left side it’s normal. Random blood glucose is 104 mg/dL. A complete blood count is normal. A CT scan of the head is shown in the image. What is the most appropriate next step in the management of this patient?

A. Heparin
B. Amiodarone
C. Metoprolol
D. Tissue plasminogen activator
E. Aspirin (Correct Answer)

Explanation: ***Aspirin*** - The patient presents with acute onset **neurological deficits** (right-sided weakness, slurred speech) consistent with an **ischemic stroke** in the setting of **atrial fibrillation**. - The CT scan shows no evidence of hemorrhage (hypodense or normal appearance), confirming **ischemic stroke**. - While the patient is on **rivaroxaban**, the question addresses the **within-window acute management**. In the acute setting (within 1 hour of symptom onset), after ruling out hemorrhage on CT, **aspirin 325 mg** is considered as initial antiplatelet therapy for ischemic stroke. - **Note:** Current guidelines suggest holding rivaroxaban temporarily and avoiding dual therapy (anticoagulation + antiplatelet) due to bleeding risk. However, aspirin remains the safest acute intervention among the choices provided for confirmed ischemic stroke. *Tissue plasminogen activator (tPA)* - **tPA** is the preferred thrombolytic for acute ischemic stroke **within 3-4.5 hours** of symptom onset. - However, it is **absolutely contraindicated** in patients on **direct oral anticoagulants** (like rivaroxaban) due to **dramatically increased risk of intracranial hemorrhage** (up to 10-fold increase). - Even with normal PT/INR, patients on DOACs cannot receive tPA safely without reversal agents. *Heparin* - **Heparin** provides additional anticoagulation on top of rivaroxaban, which would **significantly increase bleeding risk** (both intracranial and systemic). - Not indicated in acute ischemic stroke management, especially when patient is already therapeutically anticoagulated. - May be considered in specific scenarios (e.g., crescendo TIAs, arterial dissection) but not first-line here. *Metoprolol* - **Metoprolol** is a beta-blocker used for **rate control in atrial fibrillation** (patient has pulse 144/min - rapid ventricular response). - While rate control is important, **acute blood pressure lowering in ischemic stroke can worsen cerebral perfusion** and extend the infarct. - Current guidelines recommend **permissive hypertension** in acute stroke (allow BP up to 220/120 unless giving tPA). - Rate control can be addressed after acute stroke management is initiated. *Amiodarone* - **Amiodarone** is an antiarrhythmic used for rhythm control in atrial fibrillation. - Does **not treat the acute stroke** and is not indicated for emergency management of stroke. - Rhythm control is not the priority in the acute stroke setting; the focus is on salvaging brain tissue and preventing further ischemia.

Question 64: A 65-year-old woman is brought to the emergency department by her husband due to difficulty speaking and confusion for 1 hour. She was gardening when she suddenly developed these symptoms. She is not able to respond to the questions despite multiple repetitions. She also appears unsteady with her gait and is able to walk with support. The past medical history includes type 2 diabetes mellitus, dyslipidemia, and osteoarthritis. The medicine list includes aspirin, atorvastatin, metformin, and chondroitin sulfate. The vital signs include: blood pressure 174/88 mm Hg, heart rate 154/min and irregular, respiratory rate 12/min, and oxygen saturation 96% on room air. She is awake, but not following commands. The pupils are equal bilaterally and reactive to light. There is mild facial droop on the right side. The forehead wrinkles are preserved. When the soles of her feet are stimulated with a blunt instrument, the right-sided big toe goes upward, while the left-sided big toe goes downward. The ECG shows variable R-R intervals and absence of P waves. What is the next step in the management of this patient?

A. MRI of the head
B. Echocardiography
C. Amiodarone
D. Aspirin
E. CT scan of the head (Correct Answer)

Explanation: ***CT scan of the head*** - This patient presents with acute neurological deficits suggestive of a **stroke**, including difficulty speaking, confusion, facial droop, and Babinski sign (right-sided big toe going upward). - An **urgent non-contrast CT scan of the head** is the immediate next step to differentiate between an ischemic stroke and a hemorrhagic stroke, which dictates subsequent management. *MRI of the head* - While an **MRI** can provide more detailed imaging of brain tissue, it is **not the initial imaging modality** of choice in acute stroke due to longer acquisition times and limited availability. - CT is faster and readily available in most emergency settings, making it crucial for timely decision-making. *Echocardiography* - **Echocardiography** would be considered later in the workup to identify a potential **cardiac source of emboli**, such as left atrial appendage thrombus in the context of atrial fibrillation. - However, it is **not the immediate next step** as it does not help differentiate between ischemic and hemorrhagic stroke, which is critical for acute management. *Amiodarone* - The patient's irregular heart rate and absent P waves are highly suggestive of **atrial fibrillation with rapid ventricular response**. - While **amiodarone** can be used for rhythm or rate control in atrial fibrillation, addressing the acute stroke and determining its type (ischemic vs. hemorrhagic) takes **precedence** over cardiac rhythm management. *Aspirin* - **Aspirin** is indicated for the acute management of **ischemic stroke** to prevent further clot formation. - However, administering aspirin to a patient with a **hemorrhagic stroke** could worsen bleeding and be devastating, hence the critical need for a CT scan first.

Question 65: A 75-year-old man presents to the emergency department after an episode of syncope while walking outside with his wife. His wife states that he suddenly appeared pale and collapsed to the ground. She says he remained unconscious for 1 minute. He says he noticed a fluttering in his chest and excessive sweating before the episode. He has type 2 diabetes mellitus, essential hypertension, and chronic stable angina. He has not started any new medications in the past few months. Vital signs reveal: temperature 37.0°C (98.6°F), blood pressure 135/72 mm Hg, and pulse 72/min. Physical examination is unremarkable. ECG shows an old bifascicular block. Echocardiogram and 24-hour Holter monitoring are normal. Which of the following is the best next step in the evaluation of this patient's condition?

A. Cardiac enzymes
B. Continuous loop recorder (Correct Answer)
C. Valsalva maneuver
D. Electroencephalography (EEG)
E. Tilt-table test

Explanation: ***Continuous loop recorder*** - This patient's syncope is preceded by **palpitations (fluttering in chest)** and **sweating**, suggesting a cardiac etiology, specifically a **transient arrhythmia** not captured on a standard ECG or 24-hour Holter. - A continuous loop recorder provides prolonged monitoring (months to years), increasing the likelihood of detecting intermittent arrhythmias responsible for syncopal episodes. *Cardiac enzymes* - While cardiac enzymes (e.g., troponin) are crucial for evaluating **acute myocardial ischemia** or infarction, the patient presents with syncope and no new chest pain, and his stable angina suggests chronic disease rather than an acute event leading to syncope in this specific instance. - An **ECG showing an old bifascicular block** and an **unremarkable physical exam** make an acute cardiac event less likely as the primary cause of syncope when an arrhythmia is suspected. *Valsalva maneuver* - The Valsalva maneuver is a diagnostic tool often used to differentiate between certain types of **tachyarrhythmias** or to evaluate for **autonomic dysfunction**, but it is not an evaluative step for a patient presenting with unexplained syncope where an arrhythmia has not yet been documented. - It would not help in identifying the cause of intermittent syncope in a patient whose standard workup has been unremarkable, as it's a test for immediate physiological response, not prolonged cardiac rhythm monitoring. *Electroencephalography (EEG)* - EEG is indicated when **seizure disorder** is suspected as the cause of loss of consciousness, often characterized by tonic-clonic movements, post-ictal confusion, or focal neurologic signs, which are absent in this patient's presentation. - The patient's pre-syncopal symptoms of **palpitations and sweating** point away from a seizure and towards a cardiac cause. *Tilt-table test* - A tilt-table test is used to evaluate for **vasovagal syncope** or **postural orthostatic tachycardia syndrome (POTS)**, often considered when other cardiac causes are ruled out or when syncope is typically triggered by prolonged standing. - Given the patient's pre-syncopal **palpitations**, a **cardiac arrhythmia** remains a higher suspicion than vasovagal syncope at this stage, especially after normal echocardiogram and Holter monitoring, necessitating further arrhythmia investigation.

Question 66: A 24-year-old woman presents to the emergency department with palpitations for the last hour. This is her 3rd emergency department visit in the last 8 weeks due to the same complaint. She denies fever, shortness of breath, nasal discharge, bowel changes, weight loss, and heat intolerance. She has asthma that is poorly controlled despite regular inhaler use. She drinks a cup of coffee each morning, and she is physically active and jogs for at least 30 minutes daily. She is in a monogamous relationship with her boyfriend and regularly uses barrier contraceptives. Her last menses was 1 week ago. Physical examination reveals: blood pressure 104/70 mm Hg, pulse 194 /min that is regular, and respiratory rate 18/min. Her ECG is shown in the image. A gentle massage over the carotid artery for 5–10 seconds did not terminate her palpitations. What is the most appropriate next step in the management of this patient?

A. Amiodarone
B. Propranolol
C. Verapamil
D. Digoxin
E. Adenosine (Correct Answer)

Explanation: ***Adenosine*** - The ECG shows a **regular narrow-complex tachycardia** with a rate of 194 bpm and absent P waves, consistent with a re-entrant supraventricular tachycardia (SVT), most likely **AVNRT or AVRT**. - After vagal maneuvers (carotid massage) fail to terminate stable SVT, **adenosine** is the **first-line pharmacologic treatment** according to ACLS guidelines. - Adenosine works by temporarily blocking AV nodal conduction, interrupting re-entrant circuits and terminating most SVTs with a success rate of 80-90%. - It is administered as a **rapid IV bolus** (6 mg, followed by 12 mg if needed), with effects occurring within seconds. *Verapamil* - **Verapamil** (nondihydropyridine calcium channel blocker) is an effective **second-line agent** for SVT when adenosine fails or is contraindicated. - It slows AV nodal conduction and can terminate SVT, but should only be used after adenosine has been attempted in stable patients. *Digoxin* - **Digoxin** has a **slow onset of action** (hours to days) and is not appropriate for acute termination of SVT. - It may be used for chronic rate control in atrial fibrillation but is not indicated for emergency SVT management. *Amiodarone* - **Amiodarone** is reserved for **ventricular arrhythmias** or refractory supraventricular arrhythmias unresponsive to first-line agents. - It has significant side effects and prolonged onset, making it inappropriate as initial therapy for stable narrow-complex SVT. *Propranolol* - **Propranolol** (non-selective beta-blocker) is **contraindicated** in this patient due to her **poorly controlled asthma**. - Beta-blockers can precipitate severe bronchospasm in asthmatic patients by blocking beta-2 receptors in the airways. - While beta-blockers can be used for SVT rate control, they should be avoided in patients with reactive airway disease.

Question 67: A 43-year-old woman presents to a physician with weakness and fatigue for a week. She mentions that she has been taking oral fluconazole for the last 4 weeks for the treatment of tinea capitis. She also says that she loves coffee and usually consumes 4–6 cups of coffee every day. On physical examination, her vital signs are stable and examination of all systems, including nervous system, is normal. Her laboratory evaluation reveals that her serum potassium level is 3.1 mmol/L (3.1 mEq/L). The physician orders an ECG. Which of the following findings is most likely to be present?

A. Shortened QT interval
B. Tall peaked T waves
C. Disappearing P waves
D. Depression of ST segment (Correct Answer)
E. Widening of QRS complexes

Explanation: ***Depression of ST segment*** - The patient presents with **hypokalemia** (serum potassium 3.1 mmol/L), which is commonly associated with **ST segment depression** on an ECG. - Fluconazole can cause hypokalemia, and coffee consumption can exacerbate it due to its diuretic effect, further contributing to the likelihood of this ECG finding. *Shortened QT interval* - A **shortened QT interval** is typically associated with **hypercalcemia** rather than hypokalemia. - Hypokalemia is more commonly associated with **QT prolongation** or prominent U waves, not shortening. *Tall peaked T waves* - **Tall, peaked T waves** are characteristic of **hyperkalemia**, which is the opposite of the patient's condition. - In hypokalemia, T waves tend to be flattened or inverted. *Disappearing P waves* - **Disappearing P waves** are often seen in conditions like **atrial fibrillation** or severe hyperkalemia, where atrial activity is affected. - They are not a characteristic finding of hypokalemia. *Widening of QRS complexes* - **Widening of QRS complexes** is typically associated with conditions like **bundle branch blocks**, certain intoxications, or severe **hyperkalemia**, not hypokalemia. - Hypokalemia does not directly lead to a widened QRS complex.

Question 68: A 27-year-old man presents to the emergency department with a progressively worsening cough, wheezes, and chest tightness over the last 2 days. He has a history of moderate persistent asthma and his maintenance regimen consists of an inhaled corticosteroid, a long-acting beta-agonist, and albuterol as rescue therapy. He has not improved with his rescue inhaler despite increased use. He reports prior exposure to a person who had symptoms of a respiratory infection. His temperature is 37.4°C (99.3°F), blood pressure is 101/68 mm Hg, heart rate is 99/min, and respiratory rate is 32/min. Physical examination reveals widespread polyphonic wheezes but equal air entry. His oxygen saturation is 92% on room air. The presence of which of the following categorizes this patient’s condition as life-threatening?

A. Dyspnea that limits usual daily activity
B. Respiratory acidosis (Correct Answer)
C. Peak expiratory flow rate (PEFR) >70%
D. Respiratory alkalosis
E. Symptoms lasting for > 3 days after starting treatment

Explanation: **Respiratory acidosis** - The development of **respiratory acidosis** (elevated PaCO2 and decreased pH) indicates severe airflow obstruction leading to **carbon dioxide retention** and impending respiratory failure. - This is a critical sign of a rapidly worsening asthma exacerbation and suggests the need for immediate, aggressive intervention, potentially including mechanical ventilation. *Dyspnea that limits usual daily activity* - While experiencing **dyspnea that limits usual activity** indicates a significant asthma exacerbation, it does not, by itself, categorize the condition as immediately life-threatening. - Many patients with moderate to severe asthma exacerbations experience this symptom without necessarily having imminent respiratory failure. *Peak expiratory flow rate (PEFR) >70%* - A **PEFR >70%** of personal best or predicted values generally indicates a mild to moderate exacerbation, not a life-threatening one. - In severe or life-threatening asthma, PEFR would typically be significantly lower, often less than 40%. *Respiratory alkalosis* - **Respiratory alkalosis** (low PaCO2 and elevated pH) is often seen in the early stages of an asthma exacerbation due to **tachypnea** and hyperventilation as the body attempts to compensate for hypoxemia. - While it indicates an ongoing exacerbation, it is not a sign of life-threatening respiratory compromise; rather, a normal or rising PaCO2 (leading to acidosis) is the critical alarm signal. *Symptoms lasting for > 3 days after starting treatment* - Symptoms lasting for more than 3 days after starting treatment primarily indicates **poor response to treatment** or a persistent exacerbation, requiring re-evaluation. - While concerning, it does not inherently mean the condition is acutely life-threatening at that specific moment; rather, it prompts a change in management strategy.

Question 69: A 26-year-old man comes to the physician because of episodic palpitations for the past 2 months. He has the feeling that sometimes his heart “skips a beat”. His father has a history of atrial fibrillation and myocardial infarction. He has smoked one pack of cigarettes daily for 5 years. He drinks 1–2 beers on the weekends. His vital signs are within normal limits. Physical examination reveals a regular pulse. Cardiopulmonary examination shows no abnormalities. Serum studies, including electrolytes and creatinine, are within normal limits. An excerpt of 24h Holter monitoring is shown. Echocardiography is normal. Which of the following is the most appropriate next step in management?

A. Diltiazem therapy
B. Metoprolol therapy
C. Smoking cessation (Correct Answer)
D. Coronary angiography
E. Permanent pacemaker placement

Explanation: ***Smoking cessation*** - The Holter monitor shows **premature ventricular contractions (PVCs)**, which are benign in patients with structurally normal hearts (as evidenced by the normal echocardiogram). - In a young patient with **no structural heart disease** and only mild symptoms ("skipped beats"), the most appropriate initial step is to address **modifiable risk factors**. - **Smoking** is a well-established trigger for arrhythmias, including PVCs, and cessation is crucial for overall cardiovascular health, especially given the family history of atrial fibrillation and myocardial infarction. - Lifestyle modification should be attempted before pharmacological intervention in asymptomatic or minimally symptomatic patients with benign PVCs. *Diltiazem therapy* - This is a **calcium channel blocker** typically used for rate control in supraventricular tachyarrhythmias (e.g., atrial fibrillation) or for hypertension and angina. - It is **not first-line therapy for isolated PVCs** in an otherwise healthy individual with a structurally normal heart. - Given the patient's normal echocardiogram and mild symptoms, aggressive pharmacological intervention is not indicated initially. *Metoprolol therapy* - **Beta-blockers** like metoprolol can be used to reduce symptomatic PVCs, especially when they are frequent, bothersome, or causing hemodynamic compromise. - However, in a patient with a **structurally normal heart** and **mild symptoms**, addressing lifestyle factors like smoking cessation is the more appropriate first-line approach before initiating medication. - Beta-blockers would be considered if symptoms persist despite lifestyle modifications or if PVCs are highly symptomatic. *Coronary angiography* - This invasive procedure is used to visualize the **coronary arteries** and detect significant stenoses, typically in patients with symptoms suggestive of **ischemic heart disease** (e.g., angina, exertional chest pain, positive stress test). - The patient's symptoms are palpitations from PVCs, with a **normal echocardiogram** and no evidence of ischemia, making coronary angiography overly aggressive and unnecessary at this stage. - There is no indication for invasive testing in this clinical scenario. *Permanent pacemaker placement* - A pacemaker is indicated for symptomatic **bradyarrhythmias** (pathologically slow heart rates) or certain types of heart blocks where the heart's intrinsic electrical system fails to maintain an adequate heart rate. - The patient presents with palpitations due to **premature ventricular beats** (extra beats, not slow rhythm), making pacemaker placement completely inappropriate. - PVCs represent ectopic electrical activity, not failure of the heart's pacing system.

Question 70: A 23-year-old man comes to the emergency department because of palpitations, dizziness, and substernal chest pain for three hours. The day prior, he was at a friend’s wedding, where he consumed seven glasses of wine. The patient appears diaphoretic. His pulse is 220/min and blood pressure is 120/84 mm Hg. Based on the patient's findings on electrocardiography, the physician diagnoses atrial fibrillation with rapid ventricular response and administers verapamil for rate control. Ten minutes later, the patient is unresponsive and loses consciousness. Despite resuscitative efforts, the patient dies. Histopathologic examination of the heart at autopsy shows an accessory atrioventricular conduction pathway. Electrocardiography prior to the onset of this patient's symptoms would most likely have shown which of the following findings?

A. Epsilon wave following the QRS complex
B. Prolongation of the QT interval
C. Cyclic alteration of the QRS axis
D. Slurred upstroke of the QRS complex (Correct Answer)
E. Positive Sokolow-Lyon index

Explanation: ***Slurred upstroke of the QRS complex*** - The patient's presentation with **atrial fibrillation with rapid ventricular response** and subsequent collapse after verapamil administration—a calcium channel blocker—is classic for a pre-excitation syndrome like **Wolff-Parkinson-White (WPW) syndrome**. - In WPW, an accessory pathway (bundle of Kent) bypasses the AV node, leading to a **short PR interval** and a **delta wave** (slurred upstroke of the QRS complex) on ECG during normal sinus rhythm. *Epsilon wave following the QRS complex* - An **epsilon wave** is characteristic of **arrhythmogenic right ventricular cardiomyopathy (ARVC)**, representing delayed depolarization of the right ventricle. - While ARVC can cause arrhythmias, it is distinctly different from the pre-excitation syndrome described, which involves an accessory pathway. *Prolongation of the QT interval* - **Prolonged QT interval** is associated with an increased risk of **torsades de pointes**, a polymorphic ventricular tachycardia. - This finding is typical of **long QT syndrome** and does not directly relate to an accessory atrioventricular conduction pathway. *Cyclic alteration of the QRS axis* - **Cyclic alteration of the QRS axis** or electrical alternans is seen in conditions causing swings in cardiac position, most notably **pericardial effusion with tamponade**. - This ECG finding is unrelated to accessory pathways or the mechanisms of pre-excitation syndromes. *Positive Sokolow-Lyon index* - A **positive Sokolow-Lyon index** signifies **left ventricular hypertrophy (LVH)**, characterized by large QRS voltages (e.g., SV1 + RV5/V6 ≥ 35 mm). - While LVH can be associated with various cardiac conditions, it is not a direct ECG manifestation of an accessory atrioventricular conduction pathway.

Question 71: A 55-year-old man with a past medical history of obesity and hyperlipidemia suddenly develops left-sided chest pain and shortness of breath while at work. He relays to coworkers that the pain is intense and has spread to his upper left arm over the past 10 minutes. He reports it feels a lot like the “heart attack” he had a year ago. He suddenly collapses and is unresponsive. Coworkers perform cardiopulmonary resuscitation for 18 minutes until emergency medical services arrives. Paramedics pronounce him dead at the scene. Which of the following is the most likely cause of death in this man?

A. Pericarditis
B. Aortic dissection
C. Atrial fibrillation
D. Ventricular tachycardia (Correct Answer)
E. Free wall rupture

Explanation: ***Ventricular tachycardia*** - The patient's history of MI **1 year ago** creates a substrate of **scarred myocardium** that predisposes to life-threatening ventricular arrhythmias. - The current presentation of sudden chest pain radiating to the arm suggests **acute re-infarction**, which triggers electrical instability in already compromised myocardium. - **Ventricular tachycardia (VT)** degenerating to **ventricular fibrillation (VF)** is the **most common cause of sudden cardiac death** in patients with prior MI, especially during acute ischemic events. - The rapid collapse and death within minutes, despite CPR, is classic for fatal ventricular arrhythmia. *Free wall rupture* - Free wall rupture is a **mechanical complication** that occurs **3-14 days** (typically days 3-7) after an **acute MI**, not 1 year later. - By 1 year post-MI, the ventricular wall has either healed with fibrous scar tissue or formed a chronic ventricular aneurysm. - While this would cause sudden death via cardiac tamponade, the **timing makes this unlikely** in this scenario. *Pericarditis* - Pericarditis causes **pleuritic chest pain** that is sharp, positional, and typically relieved by leaning forward. - It is **not an immediate cause of sudden cardiac death** and would not explain the rapid collapse and unresponsiveness. - While post-MI (Dressler) pericarditis can occur weeks after MI, it doesn't cause this presentation. *Aortic dissection* - Aortic dissection presents with **sudden, severe, tearing chest pain** often radiating to the back. - While potentially fatal, the patient's description of pain "a lot like the heart attack he had a year ago" and his cardiac risk factors make **recurrent MI with fatal arrhythmia more likely**. - No mention of blood pressure differential or pulse deficits that would suggest dissection. *Atrial fibrillation* - Atrial fibrillation is a **supraventricular arrhythmia** that causes palpitations, dyspnea, and irregular pulse. - It is **not typically immediately fatal** in isolation and does not cause sudden collapse and death within minutes. - While AF can lead to stroke or heart failure over time, it doesn't explain this acute sudden cardiac death.

Question 72: A 62-year-old man is brought to the emergency department because of syncope. He reports sudden onset of palpitations followed by loss of consciousness while carrying his groceries to his car. He is unable to recall any further details and does not have any chest pain or dizziness. He has a history of hypertension, type 2 diabetes mellitus, gastroparesis, and osteoarthritis of the knees. Medications include lisinopril, metformin, and ondansetron as needed for nausea. He also takes methadone daily for chronic pain. Apart from an abrasion on his forehead, he appears well. His temperature is 37.2 °C (98.9 F), heart rate is 104/min and regular, and blood pressure is 135/70 mm Hg. While he is in the emergency department, he loses consciousness again. Telemetry shows polymorphic ventricular tachycardia with cyclic alteration of the QRS axis that spontaneously resolves after 30 seconds. Results of a complete blood count, serum electrolyte concentrations, and serum thyroid studies show no abnormalities. Cardiac enzymes are within normal limits. Which of the following is the most likely underlying cause of this patient's syncope?

A. Prinzmetal angina
B. Fast accessory conduction pathway
C. Brugada syndrome
D. Prolonged QT interval (Correct Answer)
E. Hypomagnesemia

Explanation: ***Prolonged QT interval*** - The patient experienced **polymorphic ventricular tachycardia** with cyclic alteration of the **QRS axis** (Torsades de Pointes), which is characteristic of a prolonged QT interval. - **Methadone is known to prolong the QT interval**, and the patient's history of syncope preceded by palpitations is consistent with this arrhythmia. *Prinzmetal angina* - Prinzmetal angina involves **coronary artery spasm**, leading to **transient myocardial ischemia**, typically causing chest pain, not primarily syncope from polymorphic VT. - While it can cause arrhythmias, the characteristic EKG finding would be **ST-segment elevation during pain**, which is not described. *Fast accessory conduction pathway* - A fast accessory pathway (e.g., in Wolfe-Parkinson-White syndrome) can lead to **AV reentrant tachycardia** or **pre-excitation** with atrial fibrillation, but not typically polymorphic VT with cyclic QRS alteration. - The EKG would show a **delta wave** and a short PR interval, which is not mentioned. *Brugada syndrome* - Brugada syndrome is an inherited channelopathy **characterized by specific EKG patterns** (e.g., coved-type ST elevation in V1-V3) and an increased risk of sudden cardiac death due to ventricular arrhythmias. - The patient's EKG findings of polymorphic VT with cyclic QRS alteration are not typical of Brugada syndrome-induced arrhythmia. *Hypomagnesemia* - While **hypomagnesemia can prolong the QT interval** and lead to Torsades de Pointes, the patient's **serum electrolyte concentrations were normal**, ruling out this direct cause. - Magnesium levels would need to be critically low for such an effect, and this is typically detected on blood tests.

Question 73: A 45-year-old woman comes to the physician because of multiple episodes of dizziness over the past 3 months. Episodes last between 20 minutes and 1 hour. During the episodes she experiences the sudden onset of spinning sensations and imbalance, associated with a ringing in her left ear. She also reports progressive left-sided hearing loss and is unable to follow conversations in noisy surroundings. She has had an upper respiratory infection for the past 5 days, which is being treated with erythromycin. She has been otherwise healthy. Her vital signs are within normal limits. Examination shows no abnormalities. Pure tone audiometry shows a combined low- and high-frequency sensory loss of the left ear with normal hearing in the mid frequencies. Which of the following is the most appropriate initial step in management?

A. Begin topiramate therapy
B. Perform Epley maneuver
C. Reduce caffeine intake (Correct Answer)
D. Discontinue erythromycin
E. Begin fluoxetine therapy

Explanation: ***Reduce caffeine intake*** - The patient presents with classic **Ménière's disease**: episodic vertigo lasting 20 minutes to 1 hour, unilateral tinnitus, progressive unilateral sensorineural hearing loss, and characteristic audiometry showing low- and high-frequency loss with preserved mid-frequencies. - **Lifestyle modifications** including **reducing caffeine, alcohol, and sodium intake** are the **most appropriate initial step** in management and represent evidence-based first-line conservative treatment. - These dietary changes help reduce endolymphatic pressure and may decrease the frequency and severity of attacks. - The symptoms have been present for **3 months**, predating the recent URI and erythromycin use by months, supporting a primary vestibular disorder rather than drug-induced pathology. *Discontinue erythromycin* - While macrolide antibiotics can rarely cause ototoxicity, this typically occurs with **high-dose intravenous erythromycin**, not standard oral doses for URI. - The patient's symptoms began **3 months ago**, well before starting erythromycin **5 days ago**, making drug-induced ototoxicity unlikely. - Aminoglycosides, loop diuretics, and platinum-based chemotherapy are the classic ototoxic agents, not typical oral erythromycin. *Begin topiramate therapy* - **Topiramate** is used for **migraine prophylaxis**, which may be considered for vestibular migraine, but there is no evidence of migraine features in this presentation. - Not indicated as initial management for Ménière's disease. *Perform Epley maneuver* - The **Epley maneuver** is specific for **benign paroxysmal positional vertigo (BPPV)**, characterized by brief (seconds to minutes) episodes triggered by specific head positions. - This patient's episodes last **20 minutes to 1 hour**, are associated with tinnitus and hearing loss, and are not positionally triggered, making BPPV unlikely. *Begin fluoxetine therapy* - **Fluoxetine** may be used for chronic vestibular disorders with comorbid anxiety or depression, or as part of vestibular migraine management. - Not appropriate as initial management for Ménière's disease without evidence of psychiatric comorbidity.

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Supraventricular tachycardias

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Ventricular arrhythmias

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Bradyarrhythmias and conduction disorders

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Sudden cardiac death

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Antiarrhythmic medications

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Cardioversion and defibrillation

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Pacemakers and ICDs

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Catheter ablation procedures

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Secondary arrhythmias (electrolyte, drug-induced)

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Inherited arrhythmia syndromes

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