A 62-year-old man with severe chronic aortic regurgitation has a blood pressure of 170/45 mmHg and collapsing peripheral pulses. The widened pulse pressure results primarily from:
- A Reduced arterial compliance alone
- B Reflex bradycardia prolonging diastolic filling
- C Diastolic runoff into the left ventricle combined with increased stroke volume ejected into the aorta ✓
- D Elevated systemic vascular resistance maintaining systolic pressure
Correct answer: C. Diastolic runoff into the left ventricle combined with increased stroke volume ejected into the aorta
Explanation
The regurgitant leak empties the aorta back into the left ventricle during diastole, causing the abnormally low diastolic pressure, while volume overload increases total stroke volume, producing the high systolic pressure. Systemic vascular resistance is actually reduced in chronic aortic regurgitation as part of the compensatory response, which eliminates option D. Reduced compliance contributes modestly but is not the primary mechanism.
Reference: Ganong's Review of Medical Physiology, 26th ed.
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