Retrograde Vertebral Artery Blood Flow

Reversal of vertebral arterial flow associated with proximal subclavian artery occlusion has been well documented (2, 5, 7, 11, 20, 22). The terms “subclavian steal syndrome” and “brachial-basilar insufficiency” have been used in reference to this association and are descriptive of the hemodynamic alterations which occur. We have encountered two additional groups of patients in whom retrograde flow of contrast medium in a vertebral artery was not associated with proximal innominate or subclavian arterial stenosis or occlusion. In view of the recent interest in the subclavian steal phenomenon, it is important to recognize that retrograde vertebral flow of contrast medium during angiography may occur as a normal variant. We have been unable to find any previous authentication of this finding in the literature. Material Arteriographic studies of the great vessels have been performed at the University of Cincinnati Medical Center in 120 patients with significant signs and/or symptoms of cerebrovascular ischemia. For the most part, the technic of arteriography of the four major cerebral vessels and their intracranial distribution was consistent throughout. Bilateral vertebral arteriography was performed by the percutaneous insertion of a catheter of Teflon tubing with an internal diameter of 0.059 inches and an external diameter of 0.083 inches. The catheter was introduced via the brachial or axillary artery and advanced into the subclavian artery where the tip was usually positioned within 3 inches of the orifice of the vertebral artery. At this point, 15 c.c, of Hypaque, 50 per cent, was injected manually with moderate pressure in approximately three seconds. Three injections were performed on each side, one with the head in each lateral position and the third with the head in the anteroposterior position. The right carotid artery and its intracranial distribution were frequently visualized with the catheter in this position, or by advancing it into the innominate artery. Carotid arteriograms were obtained at a later stage by the percutaneous needle injection of 10 c.c. of 50 per cent Hypaque into the common carotid arteries. When indicated, the aortic arch was evaluated by the retrograde passage of a Teflon catheter with terminal side holes into the aortic root via the right common carotid or axillary artery. This was followed by the injection of 50 to 60 c.c. of Ditriokon with use of the Gidlund apparatus and a pressure of 6–8 kg./ sq. cm. Indications for thoracic aortography were: (a) significant differences in blood pressure and/or pulse volumes in the upper extremities; (b) association of a supraclavicular bruit with signs or symptoms of cerebral ischemia, where routine four-vessel studies had failed to explain the clinical picture; (c) reversal of flow of contrast medium in the vertebral artery on the side contralateral to the one being injected.