Can a dilated coronary sinus produce left ventricular inflow obstruction? An unrecognized entity

Drainage of a persistent left superior vena cava to the coronary sinus is a common congenital lesion associated with dilatation of the coronary sinus. We report on 4 cases in which marked enlargement of the coronary sinus was present, immediately superior to and partially occluding the mitral valve, with consequent obstruction to left ventricular inflow. In 1 patient, presenting with cardiac failure in early infancy, this abnormality was the major defect, mimicking the features of cor triatriatum, and surgical correction led to significant symptomatic improvement. In 3 other patients this abnormality was associated with other congenital lesions, and it is postulated that in these cases impairment of flow into the left ventricle in the presence of an atrial septal defect elevated the left atrial pressure and increased the shunt across the atrial septum, thereby increasing the symptoms and clinical findings. Surgical reduction of the enlarged coronary sinus was performed in each case through the interatrial septum, and the technique is described.