[Mitral regurgitation in mitral valve prolapse: its mechanisms and time course]

To clarify the mechanisms and time course of mitral regurgitation (MR) in mitral valve prolapse (MVP), the relationship between the timing of MR flow patterns on pulsed Doppler echocardiography and phase of mitral valve prolapse on two-dimensional echocardiography was investigated. 1. Thirty-seven patients with MVP were followed by pulsed Doppler echocardiography for one to six years with an average of 2.5 years. At the initial examination, the patients were classified in five subsets on the basis of the presence or timing of MR: 10 without MR, five with early systolic MR, one with mid-systolic MR, 15 with late systolic MR and six with pansystolic MR. During the follow-up period, the timing of MR did not change in 21 patients (three with no MR, five with early systolic MR, seven with late systolic MR and six with pansystolic MR). Various changes were observed in 16 patients, i.e., developments of late systolic MR from no MR in four, of pansystolic from no MR in three, from late systolic MR in five and from mid-systolic MR in one, and disappearing late systolic MR in three. 2. Mitral annular diameter and the prolapsing phase of 118 patients with MVP (44 without MR, eight with early systolic MR, 30 with late systolic MR and 36 with pansystolic MR) were examined by long-axis two-dimensional echocardiography. The mitral annular diameter in patients with early systolic MR was significantly less than that of other MR groups, and the diameter in patients with pansystolic MR was markedly increased. The timing of MR was determined according to the prolapsing phase and the grade of the prolapse and the systolic size of the mitral annulus. Six of the eight patients with early systolic MR first had early systolic prolapse of either mitral leaflet, and then the regurgitant gap of the mitral valve orifice was plugged by the prolapsing leaflet and/or the narrowed mitral annulus during mid-to-late systole. In 18 of the 30 patients with late systolic MR, the grade of prolapse of the mitral valve during mid-to-late systole was more severe, compared with that of early systole. The results of the present study indicated that the occurrence of MR in MVP is various in timing (early, mid-, late or pansystole) and shows various changes the during follow-up study, and that pulsed Doppler echocardiography allows phase analysis of MR in MVP.