Mitral valve prolapse in children: a problem defined by real-time cross-sectional echocardiography.

The cross-sectional echocardiographic features of mitral valve prolapse were defined in 26 children (ages 2-18 years) using a real-time, multiple-crystal ultrasound scanner. In each patient the physical findings of the mitral valve click-murmur syndrome were present and mitral valve prolapse had been diagnosed previously by conventional single crystal echocardiography. Mitral prolapse occurred in a familial setting in eight patients and was associated with the Marfan syndrome in five. Real-time two-dimensional echocardiography uniformly disclosed maximum mitral arching and the superior-posterior prolapse. These visual observations were confirmed by M-mode recordings derived from single elements within the array of 20 crystals. The method allowed a complete M-mode description of the phasic motion of the entire mitral apparatus and observations of the spectrum of prolapse from discrete late systolic prolapse to "hammock-like" holosystolic prolapse. Further, the recording of multiple systolic M-mode lines occurred when the ultrasound beam intersected the arched leaflets more than once. Pseudosystolic anterior motion was observed often and resulted clearly from a superimposition of echoes from the mitral annulus and from the posterior-superiorly arched prolapsed leaflets. A major finding in 22 patients was the association with prolapse of biconvex enlargement of the aortic sinuses of Valsalva and a significant increase in the diameter of the aortic root. Aortic root dilatation was most marked in, but not confined to, patients with the Marfan syndrome and was a prominent finding in six patients with minor musculoskeletal abnormalities. The presence of aortic root dilatation in children with normal body habitus raises important questions concerning the generalized nature of an abnormality of cardiac connective tissue in patients with mitral prolapse. The cross-sectional approach significantly enhances the noninvasive evaluation of mitral valve prolapse and provides an explanation for many of the single crystal observations reported previously.