Double outlet right ventricle with severe left ventricular outflow tract obstruction due to small ventricular septal defect and anomalous adherence of the mitral valve to the ventricular septum.

A 1-month-old male infant with a double outlet right ventricle complicated by left ventricular outflow tract obstruction due to a very small ventricular septal defect is described. The atrial septum was intact, but mitral stenosis was present. The characteristic finding in this patient was that the inherently small ventricular septal defect was further narrowed by abnormal adherence of the anterior mitral leaflet to the left ventricular septal surface below the defect. Intracardiac anatomical features other than the adherent mitral valve could be evaluated accurately by two-dimensional echocardiography. Because the atrial septum was intact, balloon atrioseptostomy was not possible. An attempt at surgical creation of an atrial septal defect was unsuccessful, and the patient died immediately after the operation. The autopsy findings of the heart are described, and diagnostic problems and the possibility of radical operation are discussed.