Subclavian Steal Syndrome
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- Subclavian steal syndrome (SSS): a condition that results from stenosis or occlusion of the subclavian artery proximal to the origin of the vertebral artery, causing retrograde flow in the ipsilateral vertebral artery. Blood is drawn from the contralateral, vertebral, basilar, or carotid artery regions into the low-pressure ipsilateral upper limb vessels, “stealing” the blood flow from the circle of Willis.
- The term was reported for the first time by Fisher in 1961. It is a normal pattern of collateral response to proximal subclavian artery occlusion.
- Predominant age:
- Age >55 years—atherosclerotic etiology
- Age <30 years—90% of patients with Takayasu arteritis
- Predominant sex: female > male
- More frequent in African Americans and Caucasians when compared with Hispanics and Chinese Americans
- Present is estimated to be 0.6–6% of the population.
- Hemodynamically significant left subclavian artery stenosis is present in ~2.5% of patients undergoing coronary revascularization.
Etiology and Pathophysiology
- With a left subclavian occlusion or high-grade stenosis, maintenance of blood flow to the left arm occurs with reversal of flow from the basilar artery via the left vertebral artery.
- Symptoms are associated with the degree and location of a second extracranial vessel occlusion.
- Arteriosclerosis obliterans of the proximal subclavian artery in 95% of cases
- Lesions are 4:1 more common on the left side, left-sided SSS is usually acquired.
- Less common causes of obstruction:
- Dissecting aneurysm of aortic arch
- Radiotherapy induced
- Takayasu arteritis: The left subclavian artery is most commonly affected and patients present in their 30s.
- Giant cell arteritis
- Fibromuscular dysplasia
- May happen after Blalock-Taussig procedure for tetralogy of Fallot
- Subclavian artery compression from a cervical rib
Commonly Associated Conditions
- Carotid artery disease
- Coronary artery disease is present in 30–60% of patients.
Older patients are more likely to have arteriosclerosis.