Endovascular Angioplasty and Stenting for Proximal Subclavian Artery Stenosis

Clinical Evaluation and Diagnosis

Most patients with subclavian stenosis are asymptomatic. Patients are often referred for evaluation by primary care physicians after they find asymmetry in the upper extremity blood pressures. A brachial blood pressure difference exceeding 15 to 20 mm Hg is considered a significant finding.

Symptoms of subclavian artery stenosis can occur either in the form of exertional ischemia of the extremity (limb fatigue or pain) or, rarely, digital embolization, which can manifest as ulcerations or nonhealing wounds. Vertebrobasilar symptoms can occur in patients with reversal of flow in the vertebral artery, and this is referred to as subclavian steal syndrome. Angina or acute myocardial infarction can occur in patients with a previously placed internal mammary bypass and hemodynamically significant proximal subclavian stenosis.

Rarely, patients present with pseudohypotension and are found to have severe bilateral subclavian artery stenoses. Physical examination should include an inspection of the hand and digits for evidence of embolic phenomena; palpation of the brachial, radial, and ulnar arteries; auscultation of the supraclavicular fossa for bruits; and a recording of bilateral brachial artery pressures.

Duplex examination should be the first imaging modality to assess patients with suspected symptomatic disease. Standard imaging of the extracranial carotid arteries should be performed to assess for concomitant disease affecting these vessels, as well as an indirect assessment of the proximal carotid arteries by waveform and velocity analysis. A duplex examination of the subclavian and axillary arteries can suggest significant proximal subclavian artery disease in the presence of elevated peak systolic velocities or monophasic waveforms. However, no recognized duplex criteria have been widely accepted in assessing these arteries. A duplex examination of the vertebral artery should include direction of blood flow: antegrade, bidirectional, or reversed. Bidirectional or reversed flow suggests high-grade subclavian stenosis or occlusion or disease of the innominate artery.

Conventional subtraction angiography is the gold standard for establishing the diagnosis of a subclavian arterial stenosis and has the added benefit of an optional therapeutic intervention during the diagnostic procedure. Computed tomography and magnetic resonance arteriography have limited utility for evaluating subclavian artery stenosis before conventional angiography.

Indications for Treatment

We consider asymptomatic, good-risk patients with severe bilateral subclavian artery disease for treatment in order to facilitate accurate ambulatory blood pressure measurements. Additionally, asymptomatic patients with severe proximal left subclavian artery stenosis should be considered for intervention before coronary artery bypass grafting if the left internal mammary artery is to be used as a conduit. Symptomatic patients with exertional arm ischemia, vertebrobasilar symptoms such as subclavian steal, or angina related to a previous left internal mammary artery bypass are also offered treatment. Patients with vertebrobasilar symptoms or symptoms of subclavian steal with concomitant significant carotid artery stenosis should undergo carotid reconstruction prior to subclavian reconstruction, which may relieve their symptoms.

Endovascular treatment of subclavian artery stenosis can be performed with local sedation and minimal morbidity, but the threshold for intervention should not be lower than that of open surgical therapy. Additionally, although endovascular techniques have continued to improve since the turn of the century with lower-profile delivery systems, better stent design, and other advances, we do not agree that endovascular intervention is the first line of treatment in all patients or lesions. Nevertheless, most centers pursue angioplasty and stent placement, particularly in the management of subclavian and proximal carotid artery pathology.