A soft, low-pitched diastolic rumble heard at the apex in a patient with severe aortic regurgitation is best explained by which mechanism?
- A Diastolic impingement of the regurgitant jet on the anterior mitral leaflet ✓
- B Turbulent flow across the stenotic aortic valve
- C Flow across an atrial septal defect
- D Reverberation from the aortic regurgitation murmur itself
Correct answer: A. Diastolic impingement of the regurgitant jet on the anterior mitral leaflet
Explanation
The Austin Flint murmur of severe aortic regurgitation is a mid-diastolic rumble produced when the regurgitant jet strikes the anterior mitral leaflet, causing it to vibrate and creating relative mitral obstruction. It lacks a loud first heart sound and an opening snap, the two findings that distinguish it from true rheumatic mitral stenosis. Option D describes the Graham Steell-type confusion incorrectly; reverberation is not the accepted mechanism.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.