USMLE PRACTICE QUESTION OF THE WEEK

Question for March 27, 2026

A 64-year-old man is brought to the ED after fainting while working in his garden. He reports dizziness and fatigue over the last several weeks, but no chest pain. Medical history includes hypertension, type 2 diabetes, and hyperlipidemia. He has smoked 1 pack/day for 40 years. Medications are lisinopril, metformin, and atorvastatin. On arrival, BP is 90/60 mmHg, HR 38/min, RR 18/min. He appears pale and diaphoretic. Cardiac exam reveals a regular, slow pulse without murmurs. Lungs are clear. ECG shows complete atrioventricular block with a narrow QRS escape rhythm at 35/min. Laboratory studies show normal electrolytes and renal function.

Which of the following is the most appropriate immediate management?

Correct Answer:

D. Temporary transvenous pacing

Correct Answer Explanation:

This patient has symptomatic complete heart block (3rd-degree AV block) with severe bradycardia and hypotension. The most effective immediate treatment is temporary pacing to restore perfusion. Atropine is first-line for sinus bradycardia or AV nodal block but ineffective in complete AV block. Dopamine may improve perfusion but is less definitive. Permanent pacing is needed after stabilization.

Further Insight:

  • Causes: ischemic disease, degeneration of conduction system, medication toxicity.
  • Patients with complete heart block require pacing regardless of reversible factors.