The diagnosis of overriding aorta with special reference to circulation time tests

Methods designed to establish the presence of overriding aorta in congenital heart disease have been reviewed. Conventional studies involving the speed of the circulation, including angiocardiography, may prove a right to left shunt without indicating its site. Pressure relationships obtained during cardiac catheterization may be relied upon only to exclude overriding aorta. Passage of a catheter into the aorta from the right ventricle is undoubtedly the most reliable method of proving the diagnosis of overriding aorta. A rapid right ventricle to ear circulation time is strongly in favor of this anomaly. With rare exceptions, the presence of a right-sided aortic arch in a cyanotic patient indicates that the aorta arises in whole or in part from the right ventricle. The difficulties attendant upon the diagnosis or exclusion of overriding aorta are illustrated by a case report.