Subaortic blind mitral pouch in a double-inlet right ventricle.

A full-term baby girl was diagnosed at birth using echocardiography to have a single ventricle with common atrioventricular valve and subaortic ridge. On the 22nd day after birth she was admitted to hospital for intensive care after sudden onset of cyanosis. Three days later she died after repeated attacks of bradycardia. At necropsy the heart was examined by sequential segmental approach. Situs solitus with double-inlet right ventricle and ventriculoarterial discordance was revealed. The left atrial floor was separated from the ventricle by a small hole leading to a translucent blind pouch, which bulged toward the subaortic outflow tract with its hypoplastic tensor apparatus connected to the subaortic infundibulum. The aortic valve was normal. The pulmonary trunk with a competent bicuspid valve arose from the left-sided rudimentary left ventricle. The pulmonary blood flow was limited by a slit-like interventricular communication. Obstruction of the pulmonary venous return due to the natural closing of the patent foramen ovale and the mitral atresia led to her premature death.