The internal mammary artery: an overlooked collateral pathway to the leg.

In 10 patients with an occluded aorta, angiography performed with the catheter in the abdominal aorta failed to opacify the reconstituted distal extremity arteries. Repeat injection into the thoracic aorta resulted in adequate opacification of the leg vessels through internal mammary-inferior epigastric artery collaterals. Moving the catheter from the abdominal aorta to the ascending aorta or selectively into the internal mammary artery is suggested when standard abdominal aortic injection fails to demonstrate runoff vessels.