Arrhythmias

Arrhythmias US Medical PG Question 1: 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

Arrhythmias 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.

Arrhythmias US Medical PG Question 2: 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

Arrhythmias 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.

Arrhythmias US Medical PG Question 3: In a patient with acute myocardial ischemia, which of the following cardiovascular structures is at greatest risk of damage?

• A. Pulmonary valve
• B. Cardiac conduction system (Correct Answer)
• C. Coronary artery
• D. Cardiac septum
• E. Temporal artery

Arrhythmias Explanation: ***Cardiac conduction system*** - The **cardiac conduction system** is highly dependent on a constant oxygen supply, and its disruption by ischemia can lead to serious **arrhythmias** and **heart blocks**. - Ischemia in critical areas like the **AV node** (supplied by the RCA) or the **bundle branches** can severely impair the heart's electrical activity. *Pulmonary valve* - The **pulmonary valve** is primarily a passive structure and is generally not directly damaged by acute myocardial ischemia. - Its function is more affected by changes in **pulmonary artery pressure** or **ventricular remodeling**, not immediate ischemic injury. *Coronary artery* - While **coronary artery disease (CAD)** is the *cause* of myocardial ischemia, the coronary artery itself is not the structure *damaged* in the sense of functional impairment due to lack of blood flow in acute ischemia. - The damage occurs downstream in the **myocardium** that the artery supplies. *Cardiac septum* - The **cardiac septum** can be damaged by myocardial ischemia, particularly the **interventricular septum**, leading to complications like **septal rupture**. - However, the conduction system is at *greatest* immediate risk of functional damage leading to life-threatening events due to its critical role in rhythm generation. *Temporal artery* - The **temporal artery** is a blood vessel located in the head, entirely separate from the heart. - It is not involved in myocardial ischemia and is not at risk of damage from a cardiac event.

Arrhythmias US Medical PG Question 4: A 45-year-old man comes to the physician for a routine health maintenance examination. He feels well. He underwent appendectomy at the age of 25 years. He has a history of hypercholesterolemia that is well controlled with atorvastatin. He is an avid marathon runner and runs 8 miles per day four times a week. His father died of myocardial infarction at the age of 42 years. The patient does not smoke or drink alcohol. His vital signs are within normal limits. Cardiopulmonary examination shows no abnormalities. His abdomen is soft and nontender with a surgical scar in the right lower quadrant. Laboratory studies are within normal limits. An ECG is shown. Which of the following is the most likely diagnosis?

• A. Mobitz type II AV block
• B. First-degree AV block
• C. Mobitz type I AV block (Correct Answer)
• D. Third-degree AV block
• E. Atrial fibrillation

Arrhythmias Explanation: ***Mobitz type I AV block*** - The ECG shows progressive prolongation of the **PR interval** followed by a dropped QRS complex, which is characteristic of a **Mobitz type I (Wenckebach) AV block**. - This rhythm disturbance is often benign, especially in athletes with high **vagal tone**, and does not usually require treatment. *Mobitz type II AV block* - **Mobitz type II AV block** is characterized by a constant PR interval before the dropped QRS complex. - This type of block is generally more serious and indicative of a conduction disturbance below the AV node, often requiring a **pacemaker**. *First-degree AV block* - A **first-degree AV block** presents with a consistently prolonged PR interval (greater than 0.20 seconds) on every beat, without any dropped beats. - In this patient's ECG, there is a dropped QRS complex after progressive PR prolongation. *Third-degree AV block* - **Third-degree (complete) AV block** is characterized by complete dissociation between the P waves and QRS complexes. - There is no relationship between atrial and ventricular activity, and the ventricular rate is typically very slow and escape rhythms are observed. *Atrial fibrillation* - **Atrial fibrillation** is an irregularly irregular rhythm with no discernible P waves and varying R-R intervals. - The ECG provided shows clear P waves and a regular, albeit interrupted, rhythm pattern.

Arrhythmias US Medical PG Question 5: 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

Arrhythmias 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.

Arrhythmias US Medical PG Question 6: A 58-year-old man is diagnosed with right lower lobe pneumonia and has been admitted to a tertiary care hospital. His laboratory investigations suggest that he acquired an infection from the hospital where he underwent an elective abdominal surgery 3 weeks ago. His past medical records reveal a history of deep vein thrombosis and pulmonary embolism one year prior. After a steady clinical improvement over 5 days of inpatient treatment, he develops a cough, breathlessness, and hemoptysis on the 6th day. His temperature is 38.6°C (101.5°F), the pulse is 112/min, the blood pressure is 130/84 mm Hg, and the respiratory rate is 28/min. A general examination shows the presence of edema over the right leg and tenderness over the right calf region. Auscultation of the chest reveals localized crackles over the left mammary region and right infrascapular region. However, his heart sounds are normal, except for the presence of tachycardia, and there are no murmurs. Which of the following is the investigation of choice as the immediate next step in this patient’s management?

• A. Ventilation-perfusion scanning
• B. Echocardiography
• C. Contrast-enhanced computed tomography (CECT) of chest (Correct Answer)
• D. Serum brain natriuretic peptide
• E. Plasma D-dimer

Arrhythmias Explanation: ***Contrast-enhanced computed tomography (CECT) of chest*** - This patient presents with an acute onset of **cough, breathlessness, and hemoptysis** along with signs of **deep vein thrombosis (DVT)**, including leg edema and calf tenderness. This clinical picture, especially with a history of DVT and pulmonary embolism, is highly suggestive of a **pulmonary embolism (PE)**. - **CT pulmonary angiography (CTPA)**, performed as a contrast-enhanced CT of the chest, is the **gold standard** for diagnosing PE, as it directly visualizes thrombi within the pulmonary arteries and provides detailed anatomical information. - Given the **high pre-test probability** (prior DVT/PE, clinical signs of DVT, recent surgery, hemoptysis, tachycardia), immediate imaging with CTPA is indicated without need for D-dimer testing. *Ventilation-perfusion scanning* - **Ventilation-perfusion (V/Q) scanning** is an alternative for diagnosing PE, but it is less sensitive and specific than CTPA, especially in the presence of **pre-existing lung disease** (like the pneumonia this patient has), which can lead to indeterminate results. - It is usually reserved for patients with **renal insufficiency** or **contrast allergy** who cannot undergo CTPA. *Echocardiography* - **Echocardiography** can show signs of **right heart strain** in massive PE, but it is not diagnostic for PE itself, as it cannot directly visualize the emboli in the pulmonary arteries. - It is more useful in assessing **cardiac function** and ruling out other cardiac causes of breathlessness, or for risk stratification in confirmed PE. *Serum brain natriuretic peptide* - **Serum brain natriuretic peptide (BNP)** levels can be elevated in patients with **right heart strain** due to PE, but it is a **non-specific marker** and cannot confirm the diagnosis of PE. - Elevated BNP can also indicate other cardiac conditions, such as **heart failure**. *Plasma D-dimer* - **Plasma D-dimer** is a useful test to **exclude PE** in patients with a **low or intermediate pre-test probability**, but a **positive D-dimer** is non-specific and can be elevated in many conditions, including infection, surgery, and inflammation. - Given the patient's **high clinical probability** for PE (prior DVT/PE, current DVT signs, recent surgery, hemoptysis) and active pneumonia, D-dimer testing is **not indicated** as it would not change management—imaging with CTPA is already warranted regardless of D-dimer result.

Arrhythmias US Medical PG Question 7: A 74-year-old man presents to the emergency department with shortness of breath that started about 30 minutes ago. He is also experiencing chest pain on deep inspiration. He has several significant medical conditions including chronic obstructive pulmonary disease, hypertension, and dyslipidemia. He used to smoke about 3 packs of cigarettes every day until last year when he quit. He was in the emergency room 2 weeks ago for a hemorrhagic stroke which was promptly treated. He currently weighs 97.5 kg (215 lb). His respirations are 20/min, the blood pressure is 110/80 mm Hg, and the pulse is 105/min. On physical examination, Homan's sign is positive. An ECG and chest X-ray are performed. His current oxygen saturation is at 87% and D-dimer results are positive. He is wheeled in for a CT scan. What is the most appropriate initial treatment for this patient?

• A. Subcutaneous fondaparinux
• B. Greenfield filter (Correct Answer)
• C. Surgical thrombectomy
• D. Unfractionated heparin
• E. Warfarin

Arrhythmias Explanation: ***Greenfield filter (IVC filter)*** - This patient presents with **acute pulmonary embolism (PE)** evidenced by sudden **shortness of breath**, **pleuritic chest pain**, **tachycardia (105/min)**, **hypoxemia (87%)**, and **positive D-dimer**. The positive **Homan's sign** suggests deep vein thrombosis as the source. - The critical factor is his **recent hemorrhagic stroke 2 weeks ago**, which represents an **absolute contraindication to anticoagulation** in the acute/subacute period due to the high risk of re-bleeding. - **IVC filter placement** is specifically indicated for patients with **venous thromboembolism (VTE) who have contraindications to anticoagulation**, which precisely describes this clinical scenario. - The filter prevents further emboli from reaching the lungs while avoiding the bleeding risks associated with anticoagulants. *Subcutaneous fondaparinux* - While **fondaparinux** is a factor Xa inhibitor commonly used for PE treatment, it is still an **anticoagulant** that significantly increases bleeding risk. - A **recent hemorrhagic stroke (2 weeks ago)** is an **absolute contraindication** to any form of anticoagulation, including fondaparinux, due to the substantial risk of intracranial re-bleeding. - Standard guidelines recommend avoiding anticoagulation for at least 2-4 weeks (often longer) after intracranial hemorrhage. *Unfractionated heparin* - **Unfractionated heparin (UFH)** is a standard treatment for acute PE but is absolutely **contraindicated** in this patient due to the **recent hemorrhagic stroke**. - UFH would carry an unacceptable risk of causing recurrent intracranial bleeding in the subacute post-stroke period. *Surgical thrombectomy* - **Surgical embolectomy** is reserved for patients with **massive PE causing hemodynamic instability** (cardiogenic shock, persistent hypotension) who have failed or have contraindications to thrombolysis. - This patient is **hemodynamically stable** with a blood pressure of 110/80 mmHg, making surgical intervention unnecessarily invasive and inappropriate as initial management. *Warfarin* - **Warfarin** is an oral anticoagulant used for long-term VTE management but has a **slow onset of action** (requires 5-7 days to reach therapeutic levels), making it unsuitable for acute PE treatment. - More importantly, like all anticoagulants, warfarin is **absolutely contraindicated** in this patient due to the recent hemorrhagic stroke and high re-bleeding risk.

Arrhythmias US Medical PG Question 8: A 71-year-old man develops worsening chest pressure while shoveling snow in the morning. He tells his wife that he has a squeezing pain that is radiating to his jaw and left arm. His wife calls for an ambulance. On the way, he received chewable aspirin and 3 doses of sublingual nitroglycerin with little relief of pain. He has borderline diabetes and essential hypertension. He has smoked 15–20 cigarettes daily for the past 37 years. His blood pressure is 172/91 mm Hg, the heart rate is 111/min and the temperature is 36.7°C (98.0°F). On physical examination in the emergency department, he looks pale, very anxious and diaphoretic. His ECG is shown in the image. Troponin levels are elevated. Which of the following is the best next step in the management of this patient condition?

• A. CT scan of the chest with contrast
• B. Echocardiography
• C. Fibrinolysis
• D. Clopidogrel, atenolol, anticoagulation and monitoring (Correct Answer)
• E. Oral nifedipine

Arrhythmias Explanation: ***Clopidogrel, atenolol, anticoagulation and monitoring*** - The ECG shows **ST depression in multiple leads (II, III, aVF, V3-V6)** and **ST elevation in aVR and V1**, which is highly suggestive of **non-ST elevation myocardial infarction (NSTEMI)** or a **posterior MI/extensive anterior ischemia**. Given the elevated troponin, the patient has an NSTEMI. - Initial management for NSTEMI includes **dual antiplatelet therapy (aspirin and clopidogrel)**, **anticoagulation (e.g., heparin)**, and **beta-blockers (atenolol)**, along with continuous monitoring. *CT scan of the chest with contrast* - A CT scan with contrast would be indicated if **aortic dissection** was suspected, but the classic ECG findings and elevated troponins point away from that diagnosis as the primary concern. - While other causes of chest pain should be considered, the **ECG and troponin elevation** make **acute coronary syndrome (ACS)** the most immediate and critical diagnosis. *Echocardiography* - Echocardiography is useful for assessing **cardiac function, wall motion abnormalities, and valvular disease**, but it is generally not the immediate next step in an NSTEMI after the initial stabilization and medication. - It could be performed later to evaluate for complications such as **ventricular dysfunction** or **valvular issues**. *Fibrinolysis* - **Fibrinolysis** is indicated for **ST-elevation myocardial infarction (STEMI)** when PCI is not readily available, or for other thrombotic events, but not for NSTEMI. - In NSTEMI, the primary treatment strategy includes **antiplatelets, anticoagulants**, and often **early invasive procedures (PCI)**, if indicated by risk stratification. *Oral nifedipine* - **Nifedipine**, a dihydropyridine calcium channel blocker, can be used for hypertension or angina, but it is **not first-line** therapy for **acute coronary syndrome**. - **Beta-blockers like atenolol** are preferred in ACS to reduce myocardial oxygen demand and improve outcomes, whereas nifedipine can sometimes acutely worsen ischemia due to reflex tachycardia.

Arrhythmias US Medical PG Question 9: 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

Arrhythmias 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.

Arrhythmias US Medical PG Question 10: 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

Arrhythmias 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.

Arrhythmias Flashcard 1 of 10

Question: Which thyroid imbalance presents with tachycardia, palpitations, and arrhythmias?_____

Answer: Hyperthyroidism

Arrhythmias Flashcard 2 of 10

Question: _____ is a polymorphic ventricular tachycardia with shifting sinusoidal waveforms on ECG

Answer: Torsades de pointes

Arrhythmias Flashcard 3 of 10

Question: _____ fibrillation is a fatal arrhythmia without immediate CPR and defibrillation

Answer: Ventricular

Arrhythmias Flashcard 4 of 10

Question: Atrial _____ is characterized by a rapid succession of identical, back-to-back atrial depolarization waves

Answer: flutter

Arrhythmias Flashcard 5 of 10

Question: Torsades de pointes can progress to ventricular _____

Answer: fibrillation (VF)

Arrhythmias Flashcard 6 of 10

Question: _____ degree AV block is characterized by independent beating of the atria and ventricles (P waves and QRS complexes are not rhythmically associated)

Answer: 3rd

Arrhythmias Flashcard 7 of 10

Question: Scabies causes pruritis that is worse _____

Answer: at night

Extra Information:  https://onlinemeded.org?ref=anki  super itchy at night with excoriations and crusted, red papules. 

Arrhythmias Flashcard 8 of 10

Question: Adrenal insufficiency may cause _____ following a stressful event (e.g. surgery, infection), characterized by hypotensive shock, confusion, fever, and abdominal pain *bonus: next step in management?

Answer: adrenal crisis

Extra Information:  * because cortisol is unable to maintain blood pressure Watch Hypothalamic & Pituitary Dysfunction Clinical Manifestations [https://dashboard.sketchy.com/study/medical/courses/medical-pathophysiology/units/medical-pathophysiology-endocrine/videos/medical-pathophysiology-endocrine-hypothalamic-and-pituitary-disorders-hypothalamic-and-pituitary-dysfunction-clinical-manifestations?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical] Watch Adrenal Insufficiency [https://dashboard.sketchy.com/study/medical/courses/medical-pathophysiology/units/medical-pathophysiology-endocrine/videos/medical-pathophysiology-endocrine-hypothalamic-and-pituitary-disorders-hypothalamic-and-pituitary-dysfunction-clinical-manifestations?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical] https://onlinemeded.org/spa/endocrine?ref=anki 

Arrhythmias Flashcard 9 of 10

Question: What disease is associated with this spinal cord lesion? _____

Answer: Amyotrophic lateral sclerosis (ALS)

Extra Information:   Watch Spinal Muscular Atrophy, Amyotrophic Lateral Sclerosis (ALS) & Friedreich Ataxia [https://dashboard.sketchy.com/study/medical/courses/medical-pathophysiology/units/medical-pathophysiology-neuro/videos/medical-pathophysiology-neuro-spinal-cord-and-peripheral-nerve-spinal-muscular-atrophy-amyotrophic-lateral-sclerosis-als-and-friedreich-ataxia?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical] https://onlinemeded.org/spa/neuroscience/spinal-cord-lesions/acquire?ref=anki Atlas: Other: 

Arrhythmias Flashcard 10 of 10

Question: _____ incontinence is due to incomplete emptying, due to detrusor underactivity or outlet obstruction

Answer: Overflow

Extra Information:  Watch associated Bootcamp video [https://app.bootcamp.com/med-school/nephrology/videos/urinary-incontinence?index=3] https://onlinemeded.org/spa/gynecology/urinary-incontinence/acquire?ref=anki  Overflow = think of things that stop outflow and cause overflow Often 2/2 neural trauma (trauma, MS)