[The pathological remnants of the right sinus venosus valve. A presentation of 6 hearts of the cor tritriatum dexter type].

Six hearts specimens of cor triatriatum dextrum, eight with the Chiari's network, and 3 with a membranous remnant of the crista terminalis are studied. These anomalies are interpreted as varying degrees of persistence of the right valve of the sinus venous which reflect different stages of their morphogenesis. The most frequent congenital heart defects associated with these sinus remnants are the absence of a right atrioventricular connexion and pulmonary atresia with intact ventricular septum. There may be some haemodynamic factors in the right atrium such as partial of complete obstruction between the atrium and the right ventricle which explain the fact that the valve is not reabsorbed. In our specimens the persistent right valve divided the right atrium into two compartments; one is located in the medial sinusal portion where both cavae veins and coronary sinus are connected; the other is lateral compartment which represents the primitive right atrium. It must be noted that the persistent right valve favors blood flow to the left atrium through the patent foramen ovale or through an atrial septal defect deviating the course of the blood away from the right ventricle. This could cause the hypoplasia of the right ventricle. When the valve bulges it obstructs the blood flowing into the right ventricle. The diagnosis of these malformations can be made by echocardiographic, angiocardiographic procedures and nuclear magnetic resonance.