The influence of arm ischaemia and arm hyperaemia on subclavian and vertebral artery blood flow in patients with occlusive disease of the subclavian artery and the brachiocephalic trunk. A peroperative study.

A peroperative study of blood flow and flow direction was performed in series of patients with occlusive disease of the subclavian artery. Particular attention was focused on the flow variations caused by arm ischaemia and postischaemic hyperaemia and on the effect of injection of a vasodilator into the distal subclavian artery. The effect on blood flow and flow direction was measured with the aid of an electromagnetic flowmeter. During arm ischaemia induced by an inflated cuff on the arm, the subclavian flow diminished, as did the vertebral artery flow when it was retrograde. If the vertebral artery flow was anterograde, it increased during arm ischaemia. The postischaemic hyperaemia caused an increase of the subclavian flow and of reversed vertebral flow. If the vertebral flow was anterograde, it diminished during the postischaemic hyperaemia. Similar findings were obtained with intra-arterial injection of a vasodilator. The large amount of blood flow passing through the vertebral artery, as well as the flow variations caused by reactive arm hyperaemia, emphasize the role of this artery as a collateral vessel to the upper limb in cases of the subclavian steal phenomenon.