Diastolic mitral regurgitation in acute but not chronic aortic regurgitation: implications regarding the mechanism of mitral closure.

In acute aortic regurgitation, left ventricular pressure rises rapidly during diastole, which produces presystolic mitral valve closure. This does not occur in chronic aortic regurgitation. Since normal, nonregurgitant mitral valve closure may depend on properly coordinated atrial and ventricular contractions, we hypothesized that abnormal mitral valve closure occurring before systole in acute aortic regurgitation may produce diastolic mitral regurgitation detectable by Doppler echocardiography. Accordingly, we performed ultrasonic Doppler examination of seven patients with acute aortic regurgitation and 12 patients with chronic aortic regurgitation. Regurgitant aortic flow was severe in all cases. Doppler sampling within the left atrium demonstrated regurgitant mitral flow in late diastole in all patients with acute aortic regurgitation. The onset of diastolic mitral regurgitation coincided with mitral valve preclosure in patients with acute aortic regurgitation and occurred regardless of the position of the mitral leaflets at the initiation of closure. In contrast, none of the 12 patients with chronic aortic regurgitation had mitral valve preclosure or diastolic mitral regurgitation (p less than 0.05 versus acute aortic regurgitation). We conclude that diastolic mitral regurgitation accompanies mitral valve preclosure, which occurs in acute but not chronic aortic regurgitation. Thus diastolic mitral regurgitation may be a Doppler sign of acute aortic regurgitation, in the absence of a markedly prolonged PR interval. Furthermore, this observation suggests that normal, nonregurgitant mitral closure requires more than an increase in left ventricular pressure above left atrial pressure, regardless of the position of the mitral leaflets before closure.