TRANSESOPHAGEAL ECHOCARDIOGRAPHIC ANALYSIS OF THE SYSTOLIC PATTERN OFTHE ANTERIOR MITRAL LEAFLET IN PATIENTS WITH FLAT CHEST - DIFFERENTIATION FROM MITRAL-VALVE PROLAPSE

Transesophageal echocardiography was conducted to determine the systol ic pattern of the anterior mitral leaflet in patients with flat chest, and to differentiate it from that associated with mitral valve prolap se. The fronto-sagittal index (an. index of chest flattening) was dete rmined in. 50 subjects using chest radiographs, and was used to classi fy them into a flat chest group (index < 0.38, n = 28) and a normal ch est group (index greater than or equal to 0.38, n = 22). We then. used transesophageal echocardiography to examine the anterior leaflet in t hese subjects. A significant positive correlation was observed between , the fronto-sagittal index: and the short- to long-axis diameter rati o of the left ventricle in all patients. These parameters, and the lef t atrial dimension were lower in the Pat than the normal chest group. The clear zone area of the anterior leaflet during mid- to late-systol e was significantly larger in the flat chest group. However, no interg roup differences existed in the rough zone area of the anterior leafle t or in the middle scallop area of the posterior leaflet. Mitral regur gitation was observed in 20 and 12 subjects in the flat and normal che st groups, respectively. The maximum mitral regurgitant area did not d iffer between the two groups. The clear zone area of the anterior leaf let increased significantly following inhalation of amyl nitrite in 22 subjects of both groups, but the other areas did not increase. The mi tral regurgitant area decreased or disappeared after amyl nitrite at a similar rate in, each group. Thus, the decrease in. the antero-poster ior dimension of the thorax in subjects with flat chest affects the sy stolic pattern of the clear zone of the anterior leaflet more than tha t of the rough zone of the anterior leaflet or the posterior leaflet. This systolic pattern in such patients differs from that associated wi th mitral valve prolapse.