Arrhythmias USMLE Step 1 Practice Question
A 67-year-old man with a 15-year history of COPD presents to the emergency department with acute dyspnea, fever, and productive cough. Vital signs show: HR 102 bpm, BP 138/88 mmHg, RR 28/min, O2 sat 82% on room air. Chest X-ray reveals infiltrates consistent with pneumonia. Arterial blood gas shows pH 7.32, PCO2 58 mmHg, HCO3 28 mEq/L. On examination, he has distant breath sounds and peripheral edema. The ECG shows sinus tachycardia at 102 bpm with peaked T waves, a prolonged PR interval, and right axis deviation consistent with his known cor pulmonale. Which of the following arrhythmias represents the most likely acute complication that will develop if his hypoxemia and hypercarbia are not rapidly corrected?
Answer choices
- AVentricular fibrillation
- BMobitz II second-degree atrioventricular block
- CAtrial fibrillation with rapid ventricular responseCorrect answer
- DJunctional rhythm
- EPremature ventricular contractions in a bigeminal pattern
- FAtrial flutter with 2:1 conduction
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