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Subject: 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.
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.
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
Takayasu arteritis: the left subclavian artery is most commonly affected and patients present in their 30s
Giant cell arteritis
May happen after Blalock-Taussig procedure for tetralogy of Fallot
Carotid artery disease
Coronary artery disease is present in 30–60% of patients.
Older patients are more likely to have arteriosclerosis.
Reduced BP of >20 mm Hg in involved arm
Symptoms should be reproducible by exercising the arm.
A variation of the syndrome is the coronary–subclavian steal syndrome, which can only occur after coronary artery bypass grafting (CABG), using the internal mammary artery (IMA); may present with symptoms of cardiac ischemia.
The IMA is attached usually to the LAD; if patient develops subclavian artery stenosis proximal to the take-off of the IMA, patient has potential for having coronary steal syndrome (1)[B].
EKG typically shows ST elevations in aVR with reciprocal depressions in lateral leads (1)[B].
Patients can present with:
Upper extremity claudication or muscle fatigue following minimal exercise, rest pain, ulcers, and digital necrosis
Transient ischemic attacks (usually of the vertebrobasilar territory) often precipitated by exercise or work of the involved upper extremity.
Symptoms of vertebrobasilar ischemia include dizziness, vertigo, diplopia, dysarthria, dysphagia, ataxia, gait disturbances, numbness, nystagmus, syncope, hearing loss, and tinnitus.
Classified as asymptomatic, oligosymptomatic (only neurologic symptoms or upper limb ischemia is present), or complete (both symptoms)
Absent, diminished, or delayed pulses in ipsilateral arm:
Compare carotid, subclavian, brachial, radial, and ulnar pulses.
Using a handheld continuous wave Doppler, a monophasic or reduced biphasic pulse may be heard distal to the lesion.
A brachial systolic pressure difference of >15 mm Hg is >90% specific for subclavian stenosis (only ~50% sensitive).
Auscultation of carotid and suprascapular bruits
Physical examination can subdivide subclavian stenosis as moderate (difference >15 and <25 mm Hg between the arms) or severe (difference >25 mm Hg). This correlates with long-term prognosis.
Compression–decompression test (hyperemia test): Inflate a BP cuff above the systolic BP for 3 minutes. Vertebrobasilar symptoms may be reproduced by rapid decompression.
Evaluation of upper extremities for evidence of embolic disease such as splinter hemorrhages under the nail beds, blue fingers, livedo reticularis, and digital ischemia
Perform Allen test bilaterally.
Vascular: intracranial vascular disease, carotid artery disease, vertebral artery disease
Takayasu arteritis, especially if there are multiple pulse deficits.
Thoracic outlet obstruction particularly in athletes such as baseball pitchers and golfers
Neurogenic: brain tumor, seizures, subdural hematoma
No lab findings are pathognomonic for SSS.
Noninvasive measurement of BP in upper extremities
Pulse volume recording of upper extremities
If Takayasu arteritis is suspected:
Erythrocyte sedimentation rate (ESR) (elevated)
ECG (ischemic pattern)
Chest x-ray (CXR) (widening of thoracic aorta)
Duplex ultrasound with color flow: noninvasive modality of choice
Magnetic resonance angiography (MRA) or computed tomography (CT) as confirmatory tests
Arteriogram of arch vessels, with delayed films of vertebral arteries
Doppler ultrasound may be used as screening test.
According to the hemodynamics, there are four subtypes:
Carotid–subclavian (can only occur on the right side with brachiocephalic occlusion proximal to the origin of the carotid artery)
Antiplatelet therapy with aspirin (or clopidogrel, if intolerant of aspirin), especially in patients with concomitant coronary artery disease
Reduce cholesterol levels, if appropriate, using diet or medication (statin drugs) with a goal of low-density lipoprotein (LDL) <100
Cessation of smoking (2)[A]
In symptomatic patients, consult vascular medicine and cardiovascular surgery.
Potential indications for subclavian artery intervention include:
Disabling upper limb ischemia: rest pain and digital embolization
Angina in a patient with a left internal mammary artery (LIMA) graft
Leg claudication in patient with axillofemoral graft
To increase flow before CABG using the IMA or before creation of dialysis arteriovenous fistula
Balloon angioplasty: stent insertion increases long-term patency rates:
The 8- to 10-year primary patency is 83–95% (3)[B]
The 2- and 5-year patency rates with PTA was 100% and 85.7%, respectively (4)[B].
Long-term patency can be aided with antiplatelet agents.
Complications occur in up to 10% of the cases and include:
Embolic stroke (0.9–1.4% complication rate)
The overall patency rates comparing bypass versus PTA appears to be statistically equivalent (5)[B].
Carotid–subclavian bypass (2)[A]
To be considered if there is distal embolization from the subclavian artery lesion
The reported patency is 100% at 10 years compared with 74% for carotid bypass
Axilloaxillary bypass: 12-year graft occlusion of 10% and 0.4% periprocedural mortality
The majority of data regarding the surgical correction of SSS and coronary-subclavian steal syndrome are based on case studies and retrospective studies. There are currently no RCT studies.
Aggressive management of cardiovascular risk factors
Stroke, critical limb ischemia
Outpatient care, unless vascular surgery is anticipated
Poststenting follow-up at 1-, 6-, and 12-month intervals initially, then yearly thereafter
Frequent neurologic review of systems and subclavian Doppler ultrasound for patients who become symptomatic or have a BP difference of >10 mm Hg between arms.
Prevent injury to arm
Reduce exercise of arm
The presence of subclavian stenosis recently has been defined as an independent risk factor for cardiovascular death.
After angioplasty of the subclavian artery, younger age and stenting are independent predictors of restenosis-free survival.
Aboyans V, Criqui MH, McDermott MM et al. The vital prognosis of subclavian stenosis. J Am Coll Cardiol. 2007;49(14):1540–1545. [View Abstract]
Alcocer F, David M, Goodman R et al. A forgotten vascular disease with important clinical implications. Subclavian steal syndrome. Am J Case Rep. 2013;14:58–62. [View Abstract]
Kotelis D, Geisbüsch P, Hinz U et al. Short and midterm results after left subclavian artery coverage during endovascular repair of the thoracic aorta. J Vasc Surg. 2009;50(6):1285–1292. [View Abstract]
Sixt S, Rastan A, Schwarzwälder U et al. Long term outcome after balloon angioplasty and stenting of subclavian artery obstruction: a single centre experience. Vasa. 2008;37(2):174–182. [View Abstract]
Tsivgoulis G, Heliopoulos I, Vadikolias K et al. Subclavian steal syndrome secondary to Takayasu arteritis in a young female Caucasian patient. J Neurol Sci. 2010;296(1–2):110–111. [View Abstract]
Takayasu arteritis/vasculitis is most common in young females. The aorta and its branches are the major vessels affected by inflammation, thrombus formation, and aneurysmal dilatation. SSS is thought to be relatively common in this disorder.
The left upper extremity is affected more frequently, perhaps because subclavian steal occurs when the obstruction is proximal to the origin of the vertebral artery, and this distance is shorter on the right than on the left.
The physical findings associated with SSS are lower BP, decreased pulse, and bruit (supraclavicular) on the affected side.
Possible presence of subclavian artery stenosis should be assessed before bypass surgery when a LIMA graft is planned. If present, a stenosis may present later on as coronary–subclavian steal syndrome.