The majority of patients with “subclavian steal” syndrome have which of the following conditions?

A. Reversed flow in the involved vertebral artery.

D. Decreased systolic blood pressure in the ipsilateral arm.

 DISCUSSION: Subclavian steal syndrome results from occlusion of a subclavian artery, rarely the innominate, with decreased systolic pressure distal to this obstruction. This causes blood to flow up the contralateral vertebral area and across the basilar artery (from which more blood is “stolen”) as it courses down (in a retrograde manner) the ipsilateral vertebral artery to help supply that subclavian artery. Most patients with this phenomenon are asymptomatic, although limb weakness and paresthesias or symptoms of vertebral basilar insufficiency may occur. Strokes do not occur in patients with subclavian disease alone. Most affected patients, however, have associated atherosclerotic disease of other extracranial arteries, particularly the carotid vessels, which may contribute to symptoms of cerebral ischemia.