Coronary Artery Disease USMLE Step 1 Practice Question
A 49-year-old man with Marfan syndrome presents with progressive exertional dyspnea. Vital signs show BP 160/45 mmHg, HR 92 bpm, RR 18, and SpO2 98% on room air. Physical examination reveals head bobbing, bounding pulses, and a high-pitched early diastolic decrescendo murmur at the left sternal border. Transthoracic echocardiography demonstrates aortic root dilation to 5.2 cm with severe aortic regurgitation. No peripheral edema is noted. Which hemodynamic change best explains these findings?
Answer choices
- ADecreased stroke volume with narrow pulse pressure
- BMarked decrease in preload from venodilation
- CIncreased pulse pressure due to increased stroke volumeCorrect answer
- DNo change in left ventricular end diastolic volume
- EFixed obstruction to left ventricular outflow
- FIncreased afterload from aortic stenosis causing concentric left ventricular hypertrophy
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