Echocardiographic spectrum of mitral valve motion in children with and without mitral valve prolapse: the nature of false positive diagnosis.

To examine problems in echocardiographic diagnosis of mitral valve prolapse, multiple crystal cross-sectional echocardiography and single crystal recordings derived from the multiple crystal array were used to study 45 clinically normal children aged 3 to 15 years (Group A), 26 children aged 2 to 10 years with known mitral valve prolapse (Group B), 12 children with a catheterization-proved large left to right shunt at the ventricular level (Group C) and 8 children with catheterization-proved left ventricular outflow tract obstruction (Group D). Children in Groups A and B were not studied hemodynamically. Children in Groups C and D had no evidence of mitral valve prolapse on angiography and were studied echocardiographically to determine the effect of changes in ventricular shape on the patterns of mitral valve motion. In the real time cross-sectional studies, normal patients demonstrated a spectrum of mitral valve motion in which the bodies of the anterior and posterior leaflets became slightly horizontal with systolic ejection. The mitral apparatus assumed a curvilinear funnel shape. Arching of the leaflets into a horizontal configuration was more striking in the presence of either left ventricular dilatation in left to right shunt or involvement of the anterior mitral anulus in subaortic stenosis (two patients) and was associated with false positive M mode tracings suggesting mitral valve prolapse. This latter configuration was easily differentiated from the superior motion of the body of the leaflets in true prolapse. Studies of single crystal M mode recordings derived form the cross-sectional array in known locations from six normal patients revealed M mode patterns of pseudoprolapse in tracings derived from the leaflet body and patterns of normal motion at the free edge. In contrast, superior-posterior prolapse visualized in cross-sectional studies in patients with the click-murmur syndrome was associated with abnormal M mode recordings from all parts of the leaflet, including the free edge, although the abnormalities were most striking in tracings derived from the leaflet body. The M mode echocardiographic findings of mitral valve prolapse in both normal patients and patients with the click-murmur syndrome were dependent upon transducer angulation and the portion of the valve examined. The critical differentiation of the spectrum of normal valve motion from prolapse requires careful evaluation of echoes from the free edge of the leaflet where the posterior and anterior leaflet echoes coapt in early systole.