Diminutive fetal left ventricle at mid-gestation associated with persistent left superior vena cava and coronary sinus dilatation.

In a fetus with a small left ventricle diagnosed at mid-gestation, a persistent left superior vena cava connected to a dilated coronary sinus was detected. Although the size of the mitral annulus appeared to be normal, opening of the mitral valves was restricted in diastole. Echocardiographic follow-up showed no significant growth of the left ventricle and termination of pregnancy was carried out at 31 weeks at the parents' request. In addition to the prenatal findings, postmortem examination revealed a small mitral annulus with abnormal insertion of the mitral valve chordae tendineae. We hypothesized that abnormal venous return to a dilated coronary sinus may have led to mitral valve dysfunction and hypoplasia. On the other hand the left ventricular hypoplasia we observed may have involved a global abnormality of the left-sided cardiac structures.