Arrhythmias USMLE Step 1 Practice Question
A 34-year-old woman with no significant past medical history presents to the emergency department with acute onset palpitations and chest discomfort. Symptoms began 30 minutes ago while she was at rest and terminated abruptly after carotid massage. Vital signs show heart rate 178 bpm, blood pressure 128/82 mmHg, respirations 16/min, and normal oxygen saturation. Cardiovascular exam reveals a regular tachycardia with normal S1 and S2; no murmurs or extra sounds appreciated. A 12-lead ECG demonstrates a narrow QRS complex tachycardia at 180 bpm with no clearly visible P waves. The patient recalls a similar episode 2 months ago that also resolved spontaneously after several minutes. Which of the following is the most likely diagnosis?
Answer choices
- ASinus tachycardia secondary to anxiety
- BWolff-Parkinson-White syndrome with orthodromic atrioventricular reentrant tachycardia
- CAtrioventricular nodal reentrant tachycardiaCorrect answer
- DAtrial flutter with fixed atrioventricular conduction
- EAtrioventricular reentrant tachycardia using an accessory pathway
- FAtrial fibrillation with rapid ventricular response
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