Unstable coronary ischemic syndromes caused by coronary-subclavian steal

Coronary subclavian steal syndrome

PURPOSE OF REVIEW

Coronary subclavian steal syndrome (CSSS) is the reversal of blood flow in an internal mammary artery bypass graft that results in coronary ischemia. CSSS is an uncommon but treatable cause of coronary ischemia. In this review, we highlight the historical background and epidemiology of CSSS, common clinical presentations, diagnosis of CSSS and management strategies for relieving ischemia. We also present a case report to illustrate the complexity of CSSS and percutaneous management using current technology.

RECENT FINDINGS

Most commonly, CSSS results from atherosclerotic stenosis of the subclavian artery and occurs in 2.5-4.5% of patients referred for coronary artery bypass grafting (CABG). All patients referred for CABG should have bilateral noninvasive brachial blood pressures checked to screen for the underlying subclavian stenosis. A review of 98 case reports with 128 patients demonstrated a diverse clinical presentation of CSSS, including acute myocardial infarction, unstable angina and acute systolic heart failure. Resolution of CSSS symptoms has been reported with both surgical and percutaneous revascularization. Long-term patency with either revascularization strategy is excellent. Percutaneous revascularization is largely considered the first-line therapy for CSSS and can be safely performed prior to CABG to prevent CSSS.

SUMMARY

CSSS should be suspected in patients presenting with angina, heart failure or myocardial infarction after CABG. Successful amelioration of CSSS symptoms can be safely and effectively performed via percutaneous revascularization.

Percutaneous angioplasty and stenting of subclavian arteries before surgical coronary revascularization in a patient with an aberrant right subclavian artery

An aberrant right subclavian artery occurs in less than 2% of the population. An associated stenosis of the subclavian artery carries a risk of subclavian-coronary steal in patients who undergo coronary revascularization. We report on the case of a 54-year-old man admitted to our hospital for a coronary artery bypass graft (CABG). Angiographic examination revealed bilateral subclavian-artery stenosis with an aberrant right subclavian artery, anomalous origin of the right vertebral artery from the right common carotid artery, and left vertebral-artery occlusion. The patient underwent successful bilateral subclavian angioplasty and stenting.

Myocardial thievery: the coronary-subclavian steal syndrome

Coronary-subclavian steal syndrome entails the reversal of blood flow in a previously constructed internal mammary artery coronary conduit, which produces myocardial ischemia. The most frequent cause of the syndrome is atherosclerotic disease in the ipsilateral, proximal subclavian artery. Although coronary-subclavian steal was initially reported to be rare, the increasing documentation of this phenomenon and its potentially catastrophic consequences in recent series suggests that the incidence of the problem has been underreported and that its clinical impact has been underestimated. We review the causes and background of coronary-subclavian steal; methods of preventing, diagnosing, and treating it; and the potential influence of various treatment regimens on long-term survival and the likelihood of late adverse events in patients with coronary-subclavian steal syndrome.

Subclavian steal syndrome

BACKGROUND

Subclavian steal syndrome is a systemic entity that is well-documented in the medical literature. It occurs when the subclavian artery becomes stenosed or occluded and blood flow is reversed in the ipsilateral vertebral artery. This siphoning or "stealing" of blood has traditionally been thought to cause symptoms of vertebral-basilar insufficiency. Recent literature indicates that subclavian steal syndrome is often asymptomatic, but may be associated with a wide variety of signs and symptoms of vertebro-basilar, carotid, or upper extremity ischemia, and that the manifestation of the condition is probably dependent on the patency of the other cranial arteries.

CASE REPORTS

This report describes three patients who underwent comprehensive eye examinations and who had been previously diagnosed with subclavian steal phenomenon. The initial symptoms included: unilateral Hollenhorst plaque, unilateral fibrino-platelet plaque, and one patient with no symptoms These patients were followed for their ocular conditions concurrently with their physicians following their systemic circulatory disease. Signs and symptoms, imaging and laboratory tests, and management are discussed.

CONCLUSIONS

Subclavian steal syndrome is a systemic condition that may manifest ocular signs and symptoms that optometrists should recognize, and which merits referral for systemic evaluation and treatment as necessary Patients who manifest signs and symptoms of vertebro-basilar insufficiency, carotid territory ischemia, or ocular symptoms of atherosclerosis may be diagnosed with subclavian steal syndrome as evaluation of the extracranial arteries is pursued.

Screening for subclavian artery stenosis in patients who are candidates for coronary bypass surgery

We prospectively evaluated 59 patients who were deemed candidates for coronary bypass surgery after coronary artery angiography for subclavian artery narrowing, which could compromise the ipsilateral internal thoracic artery graft. Bilateral arm blood pressure (BP) measurements, auscultation for supraclavicular or cervical bruits, and questioning about cerebrovascular ischemic symptoms were compared to brachiocephalic-subclavian arteriography. One neurologic complication occurred during arteriography. An upper extremity BP difference of > or = 15 mm Hg identified all patients with > or = 50% subclavian artery narrowing. We recommend brachiocephalic-subclavian arteriography only in patients with abnormal noninvasive screening for subclavian stenosis, not routinely.

Accelerated atherosclerosis in saphenous vein bypass grafts: a spectrum of diffuse plaque instability

Our understanding of plaque instability may be extended to vein graft atherosclerosis, which appears to represent the end of a continuum of plaque instability. Compared with plaque in native coronary arteries, vein graft atheroma is more diffuse and vulnerable to rupture, and the consequences of plaque rupture in vein grafts seem to be associated with almost certain thrombotic occlusion within 7 to 12 years after surgery.

Angiographic prevalence and clinical predictors of left subclavian stenosis in patients undergoing diagnostic cardiac catheterization

The angiographic prevalence, clinical predictors, and sensitivity and specificity of a bilateral arm blood pressure differential for predicting proximal left subclavian artery stenosis were established in 492 patients undergoing cardiac catheterization. Seventeen subjects (3.5%) in the overall population and nine subjects (5.3%) with potential surgical coronary disease had proximal left subclavian stenosis. Precatheterization evidence of peripheral vascular disease (PVD) was the only predictor of subclavian stenosis in the overall population (P < 0.001; OR = 7.9; 95% CI = 2.6-24.3) and in patients with potential surgical coronary disease (P = 0.04; OR = 5.4; 95% CI = 1.1-27.2). Both a bilateral blood pressure differential of > 10 mm Hg and of > or =20 mm Hg had a good specificity but a poor sensitivity for predicting left subclavian stenosis. Thus, left subclavian angiography should be performed in patients with surgical coronary disease with either an arm blood pressure differential of > 10 mm Hg or with other precatheterization evidence of PVD. Cathet Cardiovasc Intervent 2001;54:8-11.

[Refractory angina caused by subclavian-coronary steal syndrome treated with angioplasty and stent]

The coronary-subclavian steal syndrome is a rare cause of recurrent myocardial ischemia in patients who have undergone left internal mammary-coronary artery bypass grafting. A significant left subclavian artery stenosis proximal to its origin, can result in an impaired or reversed flow in this graft and myocardial ischemia. We describe the case of a woman aged 76 who had undergone myocardial revascularization seven months before, and presented refractory angina with severe electrocardiographic ischemia in the left anterior descending artery territory. Arteriography confirmed this syndrome and the patient was successfully treated with percutaneous transluminal angioplasty and placement of two stents in the left subclavian artery. We review the clinical management, diagnostic methods and therapeutic options used in the subclavian-coronary steal syndrome.

[Angina caused by subclavian-coronary steal in patients revascularized with internal mammary artery]

After coronary bypass surgery in the left internal mammary artery, occlusive atherosclerosis in the proximal subclavian artery can produce reverse flow in the mammary artery and myocardial ischemia (coronary-subclavian steal syndrome). This is a rare cause of recurrent myocardial ischemia. We present two patients with postoperative complete obstruction in the proximal subclavian artery and inverse flow in the mammary artery producing severe ischemia in the left anterior descending artery territory. Both patients were treated with subclavian-subclavian bypass, which in one patient was ineffective in producing an adequate anterograde flow in the left internal mammary artery. We review clinical management, diagnostic methods and therapeutic options used in the coronary-subclavian steal syndrome.

Aortocoronary saphenous vein graft disease: pathogenesis, predisposition, and prevention

Aortocoronary saphenous vein graft disease, with its increasing clinical sequelae, presents an important and unresolved dilemma in cardiological practice. During the 1st month after bypass surgery, vein graft attrition results from thrombotic occlusion, while later the dominant process is atherosclerotic obstruction occurring on a foundation of neointimal hyperplasia. Although the risk factors predisposing to vein graft atherosclerosis are broadly similar to those recognized for native coronary disease, the pathogenic effects of these risk factors are amplified by inherent deficiencies of the vein as a conduit when transposed into the coronary arterial circulation. A multifaceted strategy aimed at prevention of vein graft disease is emerging, elements of which include: continued improvements in surgical technique; more effective antiplatelet drugs; increasingly intensive risk factor modification, in particular early and aggressive lipid-lowering drug therapy; and a number of evolving therapies, such as gene transfer and nitric oxide donor administration, which target vein graft disease at an early and fundamental level. At present, a key measure is to circumvent the problem of vein graft disease by preferential selection of arterial conduits, in particular the internal mammary arteries, for coronary bypass surgery whenever possible.

What is 'minimally invasive' coronary bypass surgery? Experience with a variety of surgical revascularization procedures for single-vessel disease

BACKGROUND

Although the use of small incisions is theoretically appealing, it has been argued that the true advantage of minimally invasive approaches to myocardial revascularization lies in the avoidance of cardiopulmonary bypass.

METHODS

Of 25 patients referred for surgical revascularization of single-vessel coronary disease, 20 elected to undergo a minimally invasive coronary artery bypass grafting (MICABG) procedure, while 5 opted to have conventional surgery with cardiopulmonary bypass (CPB). Patients having MICABG underwent single-vessel revascularization without CPB, via limited anterior thoracotomy, hemisternotomy, or median sternotomy. Intraoperatively, hemodynamics, anastomotic time, and total operative time were recorded. Postoperatively, length of hospital stay, incidence of myocardial infarction, indexes of end-organ function, and morbidity rates were recorded. In addition, patient questionnaires were used to assess subjective end points such as postoperative pain, wound drainage, and quality of life.

RESULTS

Fifteen of 20 patients undergoing MICABG underwent revascularization without CPB, while 4 were converted to standard coronary artery bypass grafting with CPB due to technical reasons and 1 for intraoperative ventricular fibrillation. Patients undergoing MICABG had no perioperative myocardial infarctions, while those having CPB had two infarctions (20%). Furthermore, there were no differences in length of stay or postoperative morbidity among the various approaches, while the MICABG procedures, especially via median sternotomy, were associated with shorter operative times.

CONCLUSIONS

The advantage of MICABG lies mainly in the avoidance of CPB. Thus, we advocate that surgeons initially utilize the median sternotomy and limited skin incision for MICABG to assure adequate exposure, technical precision, and patient safety. After a reasonable level of technical proficiency and experience are attained, the limited anterior thoracotomy approach can be used.