Arrhythmias USMLE Step 1 Practice Question
A 58-year-old man presents with palpitations and dyspnea on exertion. Vital signs: BP 138/82 mmHg, HR 92 bpm, RR 18/min, temp 37.2°C, SpO2 98% on room air. ECG demonstrates an rSR-prime pattern in lead V1 with QRS duration of 128 milliseconds. Chest X-ray shows normal heart size. He denies syncope. Troponin is negative. He takes no cardiac medications. Which diagnosis best explains these findings?
Answer choices
- AAtrial flutter
- BLeft bundle branch block
- CPreexcitation syndrome
- DRight bundle branch blockCorrect answer
- EHyperkalemia
- FWolff-Parkinson-White syndrome with atrial fibrillation
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