Subclavian Steal Syndrome
Contorni first demonstrated in 1960 radiographic reversal of flow in a vertebral artery distal to a subclavian artery stenosis. Classical subclavian steal syndrome theoretically results from increased demand in an exercised upper extremity siphoning blood from the ipsilateral vertebrobasilar circulation. The resulting symptoms include non-lateralizing transient ischemic attacks (TIAs), dizziness, ataxia, and syncope. The principal or dominant neurological symptom must be on the side of the subclavian stenosis. Isolated subclavian stenoses are usually asymptomatic because of the rich collaterals around the head and neck and shoulder, even in the face of demonstrated reverse vertebral flow. The great majority (~80%) of individuals who have symptomatic subclavian artery stenosis also have concomitant lesions in other great vessels of the upper body.
Symptomatic arterial occlusive disease is much less common (5%) than lower extremity disease. The great majority (70%) of symptomatic upper extremity subclavian artery stenoses are on the left. Such lesions produce symptoms of upper extremity ischemia as well as vertebrobasilar insufficiency (see cerebral circulation). In addition, patients who have had an internal mammary used in a CABG procedure may also experience a coronary steal syndrome. Upper extremity ischemia may be hemodynamic (claudication, rest pain) or atheroembolic. A third of patients have manifestations of both. Microemboli originate in ulcerated plaque, claudication from stenotic lesions.
The etiology of upper extremity arterial occlusive disease is much more varied than lower extremity disease, which is predominantly atherosclerotic. Vasospasm, thoracic outlet syndrome, arteritis, autoimmune disease, trauma, cardiac emboli and atherosclerosis may all play a role. A normal brachial pulse rules out subclavian stenosis, but an abnormal pulse does not make the diagnosis of subclavian steal since the stenosis may be beyond the origin of the vertebral.
For symptomatic patients with subclavian stenosis, subclavian-carotid bypass is the procedure of choice if the ipsilateral carotid is healthy. Prosthetic graft has a better patency rate than saphenous vein graft (95% at 5 years v 65%). A second option is transposition of the subclavian distal to the occlusion into the ipsilateral common carotid artery. This is not possible if the patient has had an internal mammary used in coronary revascularization. Those patients with multiple lesions may do best with grafts based on aortic arch inflow.
Occlusive lesions of the innominate (brachiocephalic artery) are rare. Patients tend to be younger (sixth decade) and the majority of lesions are atherosclerotic. The great majority are smoking-related, and about half of patients have concomitant coronary artery disease. Diagnosis is made by asymmetric blood pressure, arch arteriogram and duplex scan, in addition to the more recent gadolinium enhanced MRA.
Early attempts at direct arch reconstruction (endarterectomy) for innominate lesions yielded poor results, and extra-anatomic bypasses were devised to improve outcomes. Axillary-axillary bypass was first described by Myers in 1971 and carotid-to-carotid bypass has also been used. Good results (85% long term patency) have been obtained with axillary-axillary bypass. Problems with the extra-anatomic routes include the subcutaneous position and interference with subsequent CABG in the case of axillary-axillary bypass. Recent renewed interest in direct innominate reconstruction has yielded excellent results with 95% early relief and 90% long-term patency. The combined stroke and death rate is about 15%. Percutaneous transluminal angioplasty with and without stent is somewhat limited to isolated short smooth stenotic lesions. Ulcerated or heavily calcified plaque and thrombus are contraindications. Long term patency (<50%) are not as good as bypass.
Cherry Jr. KJ, Krupski WC, in Rutherford RB, ed., Vascular Surgery, 5th ed., WB Saunders Co., Phila., 2000:1134-1140, 1155, 1725-26, 1790.
Contorni L: Il circolo collaterale vertebro-vertebrale nella obliterazione dell'arteria succlavia alla sua origione. Minerva Chir 15:2680271, 1960.
Myers WO, Lawton BR, Sauter RD: axillo-axillary bypass graft, JAMA, 217:826, 1971.
Long-term results and outcomes of crossover axilloaxillary bypass grafting: A 24-year experience. Mingoli A - J Vasc Surg - 01-May-1999; 29(5): 894-901