Arrhythmias US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Arrhythmias. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
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: 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)
Arrhythmias 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.
Arrhythmias US Medical PG Question 4: 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
Arrhythmias 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.
Arrhythmias US Medical PG Question 5: A 26-year-old healthy woman presents with lightheadedness, palpitations, and sweating, which started suddenly after she was frightened by her neighbor’s dog. The patient’s blood pressure is 135/80 mm Hg, the heart rate is 150/min, the respiratory rate is 15/min, and the temperature is 36.6℃ (97.9℉). Her ECG is shown in the exhibit. What is the preferred agent for pharmacologic management of this condition?
- A. Metoprolol
- B. Amiodarone
- C. Propafenone
- D. Adenosine (Correct Answer)
- E. Verapamil
Arrhythmias Explanation: ***Adenosine***
- The ECG shows a **narrow complex tachycardia** with a regular rhythm and no visible P waves, consistent with **paroxysmal supraventricular tachycardia (PSVT)**, likely AVNRT.
- **Adenosine** is the preferred agent for acute termination of stable PSVT due to its ability to transiently block the **AV node**.
*Metoprolol*
- **Beta-blockers** like metoprolol can be used for rate control or prevention of PSVT, but they are not the first-line agent for acute termination due to a slower onset of action compared to adenosine.
- While metoprolol can reduce heart rate, its efficacy in acutely converting PSVT to sinus rhythm is less predictable than adenosine's.
*Amiodarone*
- **Amiodarone** is primarily used for the treatment of **ventricular arrhythmias** and certain types of refractory supraventricular tachycardias, but it is not the first-line treatment for stable PSVT.
- Its use for PSVT is generally reserved for cases unresponsive to adenosine or other first-line agents, or in patients with structural heart disease, due to its significant side effect profile and slower onset.
*Propafenone*
- **Propafenone** is a Class Ic antiarrhythmic drug used for the maintenance of sinus rhythm in patients with atrial fibrillation or flutter, and for some supraventricular tachycardias.
- It is not typically the first-line agent for acute termination of stable PSVT due to its proarrhythmic potential and slower onset of action compared to adenosine.
*Verapamil*
- **Verapamil**, a non-dihydropyridine calcium channel blocker, is an alternative to adenosine for acute termination of PSVT, especially in patients where adenosine is contraindicated or ineffective.
- However, adenosine is generally preferred as the first-line agent for hemodynamically stable PSVT due to its very rapid onset and short duration of action.
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