The gap between mitral leaflets as a cause of mitral regurgitation: relationship to mitral valve prolapse.

The gap between the tips of the anterior and posterior mitral leaflets was studied to assess the significance of this gap in the diagnosis of mitral valve prolapse. The subjects were 39 patients in whom the gap was seen and the mitral valve did not exceed the mitral annular line in systole on two-dimensional echocardiography. Forty eight healthy subjects, in whom phonocardiography disclosed no abnormalities, served as controls. The site of the gap as well as the site and severity of mitral regurgitation were assessed with two-dimensional echocardiography and Doppler flow imaging. The incidence of mitral regurgitation was 82%, which was comparable to that in the controls (67%). The site of the gap was consistent with that of regurgitation. The gap was also seen in a low percentage of healthy subjects, but clinically significant mitral regurgitation did not accompany the gap in healthy subjects including the gap-carrying controls. On the other hand, many of the gap-carrying patients showed clinically significant mitral regurgitation. Also the fact that a gap between the tip of the anterior and posterior mitral leaflets was found to be frequently accompanied by phonocardiographical features corresponding to mitral valve prolapse indicates that the presence of a gap is a significant finding.