Arrhythmias USMLE Step 1 Practice Question
A 70-year-old man is hospitalized for an inferior wall myocardial infarction. On hospital day 1, he develops bradycardia with heart rate of 48 bpm, blood pressure 102/64 mmHg, and respiratory rate 16/min. ECG shows progressive PR interval prolongation followed by a dropped QRS complex, with the cycle repeating. Troponin I is elevated at 8.2 ng/mL. He denies chest pain currently. He takes no rate-controlling medications. Which of the following is the most likely site of conduction delay?
Answer choices
- AAtrial myocardium
- BSinoatrial node
- CVentricular myocardium
- DAV nodeCorrect answer
- EBundle branches
- FPurkinje fibers
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