Subclavian artery disease

Editors-In-Chief: Alexandra Almonacid M.D.[mailto:aalmonacid@partners.org] and Jeffrey J. Popma M.D.[mailto:jpopma@partners.org]

Etiology

 * Atherosclerosis
 * Most common cause of subclavian artery stenosis
 * Predilection for the proximal part of the artery
 * The occlusion usually extends from the aortic arch to the origin of the vertebral artery due to poor collateral circulation
 * Takayasu's Arteritis
 * Fibromuscular dysplasia
 * Giant Cell Arteritis
 * Radiation-induced Vascular Injury
 * Thoracic Outlet Syndrome
 * Neurofibromatosis

Incidence

 * Incidence of 0.5 - 2% (1)
 * Left : Right = 3-4 : 1 ratio
 * The stenosis is usually focal and in the proximal segment of the vessel
 * Predictors:Hypertension, Tobacco use, Dyslipidemia, and Diabetes.

Clinical manifestations

 * Subclavian-Steal Syndrome
 * Coronary Subclavian-Steal Syndrome

Clinical Diagnosis

 * Obstruction of the subclavian artery is suspected when there is a blood pressure difference > 20mm Hg between the two arms (2)
 * If there is a clinical suggestion of vasculitis: an Erythrocyte Sedimentation Rate (ESR) or C-reactive protein (CRP) should be measured (3)

Noninvasive Diagnostic Modalities

 * Duplex Ultrasonography
 * Duplex ultrasonography of the subclavian artery and the vertebral artery can detect stenosis greater than 50% with a moderately high sensitivity (80% range) and an excellent negative predictive value (> 95%) (4)
 * Duplex ultrasonography is also highly useful in clinical follow-up of patients after revascularization procedures (4)
 * Diagnostic Imaging: The diagnostic imaging work-up of patients should include:(2)
 * Magnetic resonance imaging (MRI) with or without arteriography (MRA)
 * Computed tomographic (CT) scan of the brain with close evaluation of the posterior fossa and brainstream.
 * Arteriography
 * Ascending aortography
 * Selective arteriography of supra-aortic vessels

Indications for Revascularization

 * Symptomatic ischemia of the posterior fossa
 * Symptomatic subclavian steal syndrome
 * Disabling upper extremity claudication
 * Preservation of flow to LIMA/RIMA
 * Preop coronary bypass surgery, where LIMA/RIMA will be used
 * Postop CABG LIMA/RIMA with ischemia (with or without coronary-subclavian steal syndrome)
 * Preservation of inflow to axillary graft or dialysis conduit
 * “Blue-digit” syndrome (embolization to fingers)
 * Inability to measure blood pressure
 * Progressive stenosis or thromboembolus threatening cerebral blood supply

Indications for Revascularization in Asymptomatic Patients

 * Angioplasty of the subclavian stenosis before other cardiovascular intervention and preservation of the vasculature for other angioplasty procedures
 * Preservation of the cerebral perfusion. If other arterial lesions exist at the level of the supra-aortic vessels, to improve cerebral flow.

PTA
Percutaneous revascularization with balloon angioplasty followed by stent placement is the treatment of choice.
 * Prevertebral Portion of Subclavian Artery: Balloon expandable or self expanding stents with good radial force
 * Postvertebral Portion of Subclavian Artery: Self expanding stents to avoid possibility of postvertebral compression by extravascular structures at the thoracic outlet

Indications for Covered Stents

 * Aneurysm or “pseudoaneurysm”
 * Traumatic artery injury
 * Spontaneous arterial rupture or dissection

Associated Vertebral Artery Stenosis

 * Kissing balloon technique
 * Complication: brain embolization
 * Cerebral protection devices, protection balloons, or filters could be used.

Surgery

 * Carotid-subclavian bypass
 * Aortosubclavian bypass
 * Axilloaxillary bypass

Anticoagulation

 * Premedication with Aspirin, with optional addition of clopidogrel
 * Anticoagulation for a period of several weeks prior to revascularization in cases of Subclavian occlusion

Femoral Approach
It is used at first intention in the majority of the cases

Brachial Approach

 * Recanalization of an occluded Subclavian artery (SA)
 * When the occlusion begins at the ostium of the SA
 * Severe tortuosity of the aorta
 * Iliac and subclavian artery
 * Bilateral occlusion of the iliac arteries

Complications

 * Hematomas
 * Subclavian thrombosis
 * Axillary artery thrombosis
 * Stent Migration
 * Arterial rupture
 * Dissection
 * Distal embolization
 * Restenosis
 * Neurologic complications
 * Transient ischemic attack, stroke, hemiplegia, diplopia.

Favorable Predictors

 * Presence of subclavian steal syndrome : it prevents the risk of vertebral embolization
 * Isolatated stenosis
 * Recurrent angina following an internal mammary coronary bypass

Outcomes
Percutaneous transluminal angioplasty appears safe and efficient therapy for subclavian artery stenoses is not only an effective initial treatment, but also successful over the short- and long-term results.