Subclavian steal syndrome: a rare but important cause of syncope.

An elderly woman came to our emergency room for evaluation of a syncopal episode. While climbing a flight of stairs, she had turned her head to the left and abruptly passed out. Positive physical findings included blood pressure of 141/65 mm Hg (right arm) and 80/43 mm Hg (left arm), as well as nonpalpable left radial and brachial pulses that were detectable only by Doppler ultrasonography. Carotid duplex ultrasonography showed reverse flow in the left vertebral artery and an abnormal, stenotic distal left subclavian artery. Magnetic resonance angiography confirmed complete occlusion of the left subclavian artery with classic subclavian steal. The patient had percutaneous transluminal angioplasty with stenting of the left subclavian artery and has remained asymptomatic through 2 years of follow-up with aggressive risk-factor modification.