Congenital pulmonary steal phenomenon associated with tetralogy of Fallot, right aortic arch, and isolation of the left subclavian artery

Isolation of the left subclavian artery has been reported in cases of tetralogy of Fallot with a right aortic arch. As the isolated left subclavian artery is supplied by the left vertebral artery (in which the blood flow direction is inverted), this anomaly is usually responsible for a congenital subclavian steal phenomenon. In our case the isolated left subclavian artery was connected by a patent ductus arteriosus to the main pulmonary artery. Therefore the left vertebral artery did not supply the distal left subclavian artery but supplied the main pulmonary artery (congenital pulmonary artery steal).