[Transesophageal echocardiographic study on the mechanisms of mitral regurgitation in hypertrophic cardiomyopathy: comparison with sigmoid septum].

Transesophageal echocardiography was performed to elucidate the mechanisms of mitral regurgitation (MR) in 40 patients with hypertrophic cardiomyopathy with asymmetric septal hypertrophy, 15 obstructive and 25 nonobstructive, and the organic changes of the mitral leaflet were compared to those of 30 patients with sigmoid interventricular septum. Thirty subjects without cardiac diseases served as the control group. Transthoracic and transesophageal echocardiography were performed in all subjects to measure the following: left ventricular dimension, interventricular septal thickness and peak velocity at the left ventricular outflow tract by transthoracic echocardiography; the lengths and the thicknesses of the rough zone of the anterior and posterior mitral leaflets at mid-diastole and the distance between the tip of the posterior papillary muscle and the anterior mitral annulus by transesophageal echocardiography. The presence of systolic anterior motion of the mitral complex, contact between the anterior mitral leaflet and the interventricular septum during diastole, and the occurrence of mitral valve prolapse (MVP) were also investigated. The maximum area and timing of MR during systole was measured by M-mode color Doppler technique. The following results were obtained. 1. MR was observed in 35 (88%) of the 40 patients with hypertrophic cardiomyopathy. The maximum regurgitant area in the obstructive group was significantly greater than in the other groups, and the regurgitation was frequently pansystolic. 2. The lengths of both mitral leaflets at mid-diastole were significantly greater in both groups with hypertrophic cardiomyopathy than in the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)