Right aortic arch with isolation of left innominate artery.

A new entity of right aortic arch with isolation of the left innominate artery is described in a three-day-old boy with complete endocardial cushion defect. Embryologically, this type of anomaly will result if the interruption of the embryonic left aortic arch occurs at two sites, one between the left ductus arteriosus and the descending aorta and the other between the ascending aorta and the left common carotid artery. Absence of pulse in the left arm and on the left side of the neck strongly suggests this anomaly. The aortogram and pulmonary arteriogram may confirm the diagnosis of this anomaly during life.