Cyanosis due to an isolated atrial septal defect: case report and review of the literature

Isolated atrial defects usually lead to left-to-right shunt and right ventricular volume load. Descriptions of cyanosis with this congenital heart defect are rare. We describe a rare case of inferior caval vein flow directed through an atrial septal defect in the fossa ovalis leading to severe cyanosis, but without any additional intracardiac anatomical abnormalities. The baby with clinical features of Marfan's syndrome had an eventration of the right-sided diaphragm. Surgical closure of the defect resolved the cyanosis, but the child died 10 weeks later of severe valvar dysfunction, related to Marfan's syndrome. Mechanisms of cyanosis in patients with atrial septal defects are discussed. Echocardiographic bubble studies both from the lower and upper half of the body may help to clarify the mechanism of an otherwise unexplained cyanosis.