Persistent left fifth aortic arch in man Report of two cases

Two cases ofpersistent leftfifth aortic archforming a congenital double lumen aortic arch have been confirmed at necropsy. In the first case, the diagnosis was suspected during life after aortography. An unusual vessel ran inferior and parallel to the aortic arch from the innominate artery to the left subclavian artery. It lay superior to the pulmonary artery. Both cases were associated with other cardiovascular anomalies. The first case had a persistent ductus arteriosus, and a small membranous ventricular septal defect; the second, coarctation of the aorta, persistent ductus arteriosus, bicuspid aortic valve, and a single right coronary artery. There is disagreement about the existence of the fifth aortic arch in man. In the cat embryo, Hunting-ton (I9I9) depicts a fifth arch forming a vascular channel beneath the fourth arch. Brown (I9I3) in the cat embryo, and Buell (I922) in the chick embryo have described the existence of the fifth arch. Congdon (1922) reported that endothelial sprouts arising from the aortic sac ventrally an