What is subclavian steal syndrome?

From the Guidelines

Subclavian steal syndrome is a condition where stenosis or occlusion of the subclavian artery proximal to the origin of the vertebral artery causes blood to flow backward from the brain through the vertebral artery to supply the arm, resulting in symptoms of vertebrobasilar insufficiency. This condition occurs when the subclavian artery becomes stenotic or occluded, leading to reversal of flow in the vertebral artery and internal mammary arteries to supply the arm, which can cause symptoms such as dizziness, vertigo, visual disturbances, and syncope, particularly during arm exercise 1.

Key Points

• The diagnosis of subclavian steal syndrome typically involves ultrasound, CT angiography, or magnetic resonance angiography to demonstrate the reversed vertebral artery flow and subclavian stenosis 1.
• Treatment depends on symptom severity and includes risk factor modification (smoking cessation, blood pressure control, cholesterol management) for all patients 1.
• For symptomatic patients, revascularization procedures such as endovascular stenting of the subclavian artery or surgical bypass (subclavian-carotid or carotid-subclavian bypass) may be necessary, with consideration of both options on a case-by-case basis by a vascular team 1.
• Asymptomatic patients with incidentally discovered subclavian steal generally don't require intervention beyond risk factor management, unless the ipsilateral internal mammary artery is required for myocardial revascularization or in cases of ipsilateral haemodialysis arteriovenous access 1.

Recommendations

• Bilateral arm blood pressure measurement is recommended for all patients with peripheral arterial and aortic diseases to detect subclavian artery stenosis 1.
• Endovascular revascularization may be considered over surgery due to lower complication rates, despite similar long-term outcomes 1.
• Routine revascularization in patients with atherosclerotic subclavian artery disease is not recommended, except in cases of proximal stenosis in patients undergoing CABG using the ipsilateral internal mammary artery or in cases of ipsilateral haemodialysis arteriovenous access 1.

From the Research

Definition of Subclavian Steal Syndrome

• Subclavian steal syndrome (SSS) is a hemodynamic phenomenon characterized by blood flow reversal in the vertebral artery due to significant stenosis or occlusion of the proximal ipsilateral subclavian artery 2, 3, 4, 5, 6.
• This syndrome can also occur due to stenosis or occlusion of the innominate artery 6.

Causes and Risk Factors

• Atherosclerosis of the subclavian artery is the most common cause of SSS 4.
• Other causes include dialysis arteriovenous fistulas (AVFs) and arterial congenital malformations 6.
• The syndrome can also be attributed to an arteriovenous graft (AVG) 6.

Clinical Presentation

• Symptoms of SSS include paroxysmal vertigo, drop attacks, arm claudication, and shortness of breath 4, 5.
• The syndrome can also present with neurological and vascular signs and symptoms, such as left arm pain and blurry vision with repetitive movement 5.
• However, many cases of SSS are asymptomatic 4, 6.

Diagnosis

• Doppler ultrasound is a useful screening tool for SSS, but the diagnosis must be confirmed by CT or MR angiography 4.
• Percutaneous angiography can also be used to demonstrate the steno-occlusive lesion of the proximal subclavian artery 5.

Treatment

• Conservative treatment is the initial best therapy for asymptomatic SSS, with surgery reserved for refractory symptomatic cases 4.
• Percutaneous angioplasty and stenting are widely favored surgical approaches for SSS, rather than bypass grafts of the subclavian artery 2, 3, 4.
• Surgical correction is frequently necessary when SSS is attributed to AVF or AVG 6.