Subclavian Steal Syndrome

The term subclavian steal describes retrograde blood flow in the vertebral artery associated with proximal ipsilateral subclavian artery stenosis or occlusion, usually in the setting of subclavian artery occlusion or stenosis proximal to the origin of the vertebral artery. Alternatively, innominate artery disease has also been associated with retrograde flow in the ipsilateral vertebral artery, particularly where the subclavian artery origin is involved. Subclavian steal is frequently asymptomatic and may be discovered incidentally on ultrasound or angiographic examination for other indications, or it may be prompted by a clinical examination finding of reduced unilateral upper limb pulse or blood pressure. In some cases, patients may develop upper limb ischemic symptoms due to reduced arterial flow in the setting of subclavian artery occlusion, or they may develop neurologic symptoms due to posterior circulation ischemia associated with exercise of the ipsilateral arm.[1] Treatment has traditionally consisted of open subclavian artery revascularization, typically via carotid-subclavian bypass or subclavian artery transposition, which are generally durable procedures. Newer, less invasive options include endovascular intervention with recanalization as appropriate and angioplasty and stenting if required. The clinical relevance of subclavian steal was described in 1961 by Reivich, Holling and Roberts; however, the recognition of retrograde vertebral artery flow dates back another 100 years to Harrison and Smyth. Some papers, including a previous version of this article, advocate restricting the term subclavian steal to patients with neurologic symptoms only, but this is incorrect in view of the substantial literature using this term to describe the hemodynamic scenario of retrograde vertebral flow and proximal subclavian artery disease.