[Continuity from normal to prolapsed mitral valves: two-dimensional and color Doppler echocardiographic...

To investigate the continuity between the normal and prolapsed mitral valves (MVP), two-dimensional echocardiography (2DE) and color Doppler echocardiography (CDE) were performed in 508 healthy boys aged 12 to 13 years old. The distance from the plane of the mitral annulus to the coaptation of the mitral valve "c", the maximum distance between the anterior leaflet and a straight line connecting the anterior mitral annulus and the coaptation of the mitral valve "d", and the maximum distance between the posterior mitral leaflet and the straight line connecting the posterior mitral annulus and the coaptation of the mitral valve "e" were measured in the parasternal long-axis view. The locations of the anterior and posterior mitral annuli were determined to be the hing point of the anterior leaflet on the left ventricular side and the junction of the posterior leaflet on the ventricular side, respectively. Mitral regurgitation (MR) was evaluated by CDE in the parasternal long-axis view. The ratio of the duration of regurgitation to ejection time (DT/ET) was measured by M-mode CDE in the subjects with and without MVP. The values of "c" ranged from +10 mm to -3 mm, and those of "d" from +5 mm to -4 mm (minus denotes prolapse into the left atrium). Approximately normal distributions were demonstrated with the parameters "c" and "d". The value of "e" could not be measured because of a poor image of the posterior leaflet. The incidence of MVP varied from 2.5 to 13.5% depending on the criterion for applied MVP. Fifty-nine of the 487 healthy subjects turned out to have MR (12%). Coaptation of the mitral valve deviated from the posterior commissure significantly to the left atrium more in the subjects with MR than in those without MR (2.46 +/- 1.93 vs 3.41 +/- 1.84, p < 0.01). The DT/ET ratio of the MR subjects with MVP tended to be higher than that of the boys without MVP. The presence of continuity between the normal and prolapsed mitral valves suggests that MVP may be a multifactorial disorder of the valve. Associated asymptomatic MR may be related not only to the severity of MVP but also to other factors, especially in MR of normal healthy subjects.