Anomalous course of the left brachiocephalic vein.

An anomalous course of the left brachiocephalic vein beneath the aortic arch was identified in 7 patients undergoing surgical repair of congenital cardiac malformations. Six of these patients had the morphologic features of tetralogy of Fallot including severe obstruction to the right ventricular outflow tract and a right aortic arch. A review of the literature reveals this to be an uncommon anomaly. When it is present, however, it is frequently associated with a ventricular septal defect, obstruction of the right ventricular outflow, and aortic arch anomalies. This anomaly can be documented by echocardiography, at cardiac catheterization, or intraoperatively. The presence of a subaortic left brachiocephalic vein may have implications for the conduct of surgical procedures, especially in the setting of tetralogy of Fallot.