[Assessment of prolapsing pattern of the anterior mitral valve in mitral valve prolapse: new echocardiographic diagnostic criteria].

In the present study, the ballooning pattern of the anterior mitral valve (AMV) in mitral valve prolapse (MVP) was investigated, and new diagnostic criteria for MVP were established using two-dimensional and Doppler echocardiography. The study population consisted of 164 patients with prolapse of the AMV alone, including 86 patients with idiopathic MVP, 52 associated with atrial septal defect (ASD), 17 having chordal rupture and nine associated with connective tissue disorders. There were 60 normal controls. The results were as follows: 1. The AMV was divided into two zones, clear and rough (CZ and RZ), according to the point of insertion of the strut chordae based on two-dimensional long-axis echocardiograms of the left ventricle. The severity of AMV prolapse was determined by an angle between the posterior aortic wall (PAO)-CZ and the CZ-RZ. a) Type A: Apparently there was a transitional point between CZ and RZ, despite normal PAO-CZ and CZ-RZ angles. The RZ showed mild ballooning or prolapse into the left atrium. b) Type B: Although the PAO-CZ angle was normal, the CZ-RZ angle was markedly narrowed. Therefore, prolapse of the RZ was more severe compared with that of type A. c) Type C: An overall zone of the AMV showed ballooning or prolapse into the left atrium due to a narrowed PAO-CZ angle. 2. Type B prolapse was frequently observed in idiopathic MVP (58%), the ASD group (71%) and the chordal rupture group (71%), and type C prolapse in MVP of connective tissue disorders (89%). 3. All of 18 patients (100%) with type A, 48 of 99 (48%) with type B, and 10 of 47 (21%) with type C could not be diagnosed as MVP using Gilbert's criterion. 4. Doppler mitral regurgitation (MR) was detected in 40 of the 47 patients (85%) with type C in 56 of the 99 (59%) with type B, and in seven of the 18 (39%) with type A. These results suggested that classification of the two-dimensional echocardiography of the AMV into two zones, clear and rough (CZ and RZ), could contribute to determining not only the severity of AMV prolapse, but also to the extent of myxomatous changes of the AMV and to evaluating the correlations between the degree of MVP and the incidence of MR.