What is Subclavian Steal Syndrome?

From the Guidelines

Subclavian steal syndrome should be treated with revascularization, either through endovascular approaches (angioplasty with stenting) or surgical bypass procedures (carotid-subclavian or subclavian-subclavian bypass), in symptomatic patients, with endovascular treatment being typically first-line due to lower procedural risk, as recommended by the 2011 ASA/ACCF/AHA/AANN/AANS/ACR/ASNR/CNS/SAIP/SCAI/SIR/SNIS/SVM/SVS guideline on the management of patients with extracranial carotid and vertebral artery disease 1.

Diagnosis and Symptoms

Subclavian steal syndrome occurs when there is stenosis or occlusion of the subclavian artery proximal to the vertebral artery, causing blood to flow backward from the brain through the vertebral artery to supply the arm. Symptoms typically include:

• Dizziness
• Vertigo
• Visual disturbances
• Arm claudication or fatigue with exertion

Diagnosis involves:

• Ultrasound
• CT angiography
• Magnetic resonance angiography to visualize the reversed vertebral artery flow and subclavian stenosis

Treatment

Treatment depends on symptom severity. Asymptomatic patients generally require no intervention beyond risk factor modification like:

• Smoking cessation
• Blood pressure control
• Antiplatelet therapy (aspirin 81-325mg daily)

For symptomatic patients, revascularization is recommended, either through:

• Endovascular approaches (angioplasty with stenting)
• Surgical bypass procedures (carotid-subclavian or subclavian-subclavian bypass)

Following intervention, patients should continue antiplatelet therapy and address underlying atherosclerotic risk factors to prevent recurrence or progression of vascular disease elsewhere, as supported by the guidelines 1.

Key Considerations

• The choice between endovascular and surgical approaches should be individualized based on patient factors and anatomy.
• Endovascular treatment is typically first-line due to lower procedural risk.
• Surgical bypass procedures may be preferred in certain cases, such as total arterial occlusion or stenotic lesions that are anatomically unsuited to catheter intervention.

From the Research

Definition and Pathophysiology

• Subclavian steal syndrome is a condition characterized by a steno-occlusive lesion of the proximal subclavian artery, leading to retrograde flow in the vertebral artery away from the brain stem, causing vertebrobasilar insufficiency 2, 3, 4.
• The syndrome is hemodynamically associated with proximal stenosis or occlusion of the subclavian artery and a changed blood flow pattern in the ipsilateral vertebral artery 4.

Symptoms and Diagnosis

• Symptoms of subclavian steal syndrome include paroxysmal vertigo, drop attacks, arm claudication, shortness of breath, left arm pain, and blurry vision with repetitive movement 2, 3, 5.
• Diagnosis can be confirmed by CT or MR angiography, with Doppler ultrasound as a useful screening tool 2, 5.
• A meticulous examination of segmental pulses and pressures, as well as judicious use of duplex ultrasonography, magnetic resonance angiography, computed tomography angiography, or conventional angiography can also confirm the presence of subclavian stenosis 6.

Treatment and Management

• Conservative treatment is the initial best therapy for asymptomatic patients, with surgery reserved for refractory symptomatic cases 2, 4.
• Percutaneous angioplasty and stenting are widely favored surgical approaches, rather than bypass grafts of the subclavian artery 2, 5.
• Symptomatic patients benefit from either percutaneous or surgical revascularization, depending on both anatomic and patient factors 6.

Prognosis and Complications

• Subclavian steal syndrome is an important cause of transient ischemic attacks and acute episodic dizziness 4.
• Subclavian stenosis, regardless of symptoms, is a marker of atherosclerotic disease and increased risk for cardiovascular and cerebrovascular events 6.