Arrhythmias USMLE Step 1 Practice Question
A 24-year-old woman comes to the clinic because of recurrent episodes of sudden-onset palpitations that stop abruptly after she bears down or splashes cold water on her face. She is otherwise healthy. During an episode, ECG shows a regular narrow-complex tachycardia at 190 per minute without clearly visible P waves. Which of the following is the most likely mechanism of this arrhythmia?
Answer choices
- AReentry within dual AV nodal pathwaysCorrect answer
- BAccessory pathway from atrium to ventricle
- CEnhanced sinus node discharge
- DTriggered activity due to prolonged QT interval
- EAutomaticity from multiple atrial foci
- FReentry within the sinoatrial node
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