Arrhythmias USMLE Step 1 Practice Question
A 38-year-old woman without prior cardiac history presents to the emergency department with acute-onset palpitations and dyspnea. She reports symptom onset 15 minutes ago while at rest. Vital signs: BP 128/82 mmHg, HR 165 bpm, RR 18/min, O2 saturation 98% on room air. Physical examination reveals a regular pulse and no murmurs. A 12-lead ECG demonstrates a wide-complex tachycardia with left bundle branch block morphology. Chest X-ray is normal. Laboratory studies including electrolytes, troponin, and TSH are all within normal limits. Intravenous adenosine 6 mg is administered with no effect on the arrhythmia. The patient remains hemodynamically stable with adequate perfusion. Which of the following is the most appropriate next intervention?
Answer choices
- AIntravenous verapamil 5 mg bolus
- BIntravenous diltiazem followed by transesophageal pacing
- CIntravenous procainamide followed by consideration of synchronized cardioversion if rhythm does not terminateCorrect answer
- DUrgent electrophysiology consultation for immediate ablation
- EObservation with continuous cardiac monitoring and serial ECGs
- FIntravenous amiodarone loading dose followed by infusion
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