[Mitral valve abnormalities in the hypoplastic right heart syndrome: echocardiographic observations].

Two-dimensional echocardiographic examinations were performed for 86 patients with the hypoplastic right heart syndrome (55 cases of tricuspid atresia, 9 of pure pulmonary stenosis and 22 of pure pulmonary atresia). Prolapse of the anterior mitral leaflet was detected in 14 patients (16.3%). Four of these 14 patients had mitral regurgitation. Among the patients with mitral valve prolapse, ruptured chordae tendineae of the mitral valve were detected in two, and elongation of the chordae in one. There were no significant relationships between the incidence of mitral valve prolapse and sex, age, type of tricuspid atresia, previous palliative surgery, or PaO2. However, one patient with pure pulmonary stenosis, who had had mitral valve prolapse without mitral regurgitation, developed mitral regurgitation several months after undergoing a Blalock-Taussig shunt operation. The mechanism responsible for mitral valve prolapse in the hypoplastic right heart syndrome is not clear. Multiple factors, such as long-standing left ventricular volume overload, hypoxic myocardial damage, and anatomical chordal abnormalities may cause mitral valve prolapse. The presence of a mitral valve abnormality has an important bearing on the natural history as well as the surgical procedure of choice. The need for careful echocardiographic examinations to detect mitral valve abnormalities in the hypoplastic right heart syndrome is thus underscored.