Double outlet right ventricle with intact interventricular septum--a case report.

Double Outlet Right Ventricle with intact ventricular septum is an extremely rare malformation. Only nine cases are recorded in the known world literature. A new case is reported, concerning a female infant six months old when first seen, and still alive after atrial septectomy. The anatomical studies in Double Outlet Right Ventricle suggest that only the Ventricular Septal Defect in the outlet septum is an integral part of the malformation and can be defined as "typical". In more than 10% of cases the Ventricular Septal Defect opens into the inlet or trabecular-muscular portions of the septum: these latter locations of the defect should therefore be considered as "associated". Double Outlet Right Ventricle with intact ventricular septum can be interpreted as the variant lacking both typical and associated Ventricular Septal Defect. From the analysis of anatomical descriptions of the ten known specimens of Double Outlet Right Ventricle with intact Ventricular septum, the Authors word out the hypothesis that ventricular septum closure could be referred to a well developed bulbo-ventricular fold (bulbo-ventricular fold synonimous of cono-ventricular flange and bulbo-atrio-ventricular ledge), as a consequence of missed or defective conal absorption. They conceive a range including on one hand the Subarterial Ventricular Septal defect (bulbo-ventricular fold poorly developed due to effective conal absorption), on the other hand the Restrictive Ventricular Septal Defect and Intact Ventricular Septum (bulbo-ventricular fold well developed due to defective conal absorption).