Left aortic arch with right descending aorta.

A left aortic arch with a right descending aorta is a rare congenital anomaly. The radiographic findings in 13 previously described cases and three additional cases are discussed. Characteristic findings on the plain radiograph and esophagram can usually obviate the need for aortography. The anomaly was associated with a vascular ring in at least four and probably five of the 16 patients. Additional and more complex studies may be needed in patients with suspected symptomatic vascular rings.