A term infant with antenatal diagnosis of trisomy 21 and double-outlet right ventricle (tetralogy of Fallot type) developed progressive biventricular dysfunction. Echocardiogram showed an overriding aorta with aortic-to-mitral valve discontinuity but good ventricular function. The ventricular septal defect (VSD) showed a doubly committed subarterial position. Subsequent echocardiogram revealed depressed biventricular function with a …