Severe cyanosis due to atrial septal defect and an anomalous inferior vena caval valve.

Uncomplicated atrial septal defect is often associated with mild arterial desaturation. A case is reported with severe cyanosis and life-threatening hypoxemia due to an atrial septal defect. Cardiac catheterization revealed normal right heart pressures and an atrial septal defect with shunting of inferior vena caval blood into the left atrium. At surgery an anomalous inferior vena caval valve was found directing inferior vena caval blood into the left atrium. The embryologic basis for this association is discussed. The delayed onset of severe cyanosis may have been contributed to by the thoracic scoliosis.