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J Thorac Cardiovasc Surg 1994;107:1165-1167
© 1994 Mosby, Inc.
LETTERS TO THE EDITOR |
Clinic for Cardiovascular Surgery
University Hospital
Zurich, Switzerland
To the Editor:
The internal thoracic artery (ITA) is considered to be the conduit of choice in coronary artery revascularization because of favorable long-term patency rates. As the patient population with ITA grafts increases, however, early and late complications in this select group are becoming increasingly apparent. Coronary steal syndrome represents a rare complication of ITA bypass grafting. Reduced or even reversed flow in the patent ITA graft leads to myocardial ischemia. There are different types of coronary steal. The best known is the coronary-subclavian steal syndrome, which is due to proximal subclavian artery stenosis.
1 We describe here the case of a patient with coronary-subclavian steal occurring 10 years after ITA bypass grafting, with successful surgical cure.
In 1981, a 58-year-old man with a history of previous posterolateral myocardial infarction and three-vessel disease underwent uncomplicated coronary artery bypass grafting, including a graft from the left ITA to the left anterior descending artery. Before operation, there was no blood pressure difference between the upper extremities. The postoperative course was uneventful and the follow-up coronary angiogram 3 months later showed patent grafts.
In November 1990, the patient had a cerebrovascular insult with left-sided hemiplegia. At admission, physical examination showed a slight left-sided sensomotoric hemiparesis with facial paralysis on the left side. Blood pressure in the right arm was 185/90 mm Hg, with 125/90 mm Hg in the left arm. A cervical bruit was audible on the right side and a loud supraclavicular bruit on the left. Neuroangiologic examination with extracranial pulsed-wave Doppler and duplex scan showed a high-grade stenosis of the right internal carotid artery and, in addition, stenosis of the left subclavian artery with bidirectional flow in the left vertebral artery. Selective exercise of the left arm induced reversed flow. Aortic arch angiography confirmed the findings. Moreover, there was no opacification of the ITA. We interpreted this phenomenon as flow reversal with coronary-subclavian steal. Multistage, graded bicycle exercise testing revealed significant ST segment depressions in the anterior precordial leads without symptoms. These data confirmed the presumptive diagnosis of significant coronary-subclavian steal syndrome.
The patient subsequently underwent left carotidsubclavian artery bypass with a 6 mm Impra graft (Impra, Inc., Tempe, Ariz.) and endarterectomy of the right carotid bifurcation. The postoperative course was uneventful and the patient was discharged 5 days later. The follow-up examination 2 months later showed equal blood pressures in both arms and normal flow profile in the extracranial pulsed-wave Doppler scan of the left vertebral artery. Aortic arch angiography revealed a patent ITA graft with antegrade flow (Fig. 1). Exercise electrocardiogram showed no abnormalities.
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There are only a few clinical measures to detect the patient at risk before coronary artery bypass grafting. Differences in blood pressure between the upper extremities with a supraclavicular bruit suggests subclavian artery stenosis. To confirm the diagnosis, we perform brachiocephalic angiography in combination with coronary artery catheterization. In case of proximal subclavian artery stenosis, the ITA is used as a free graft.
Angiographic confirmation of symptomatic coronary-subclavian steal is an indication for surgical repair. Treatment of the coronary-subclavian steal syndrome is best accomplished with carotidsubclavian artery bypass grafting. This is safe and effective and has good long-term patency rates.
4 Transposition of the subclavian artery onto the common carotid artery is another possibility, as well as endarterectomy of the subclavian artery; but both of these procedures can jeopardize ITA flow, either temporarily or permanently. In recent years, moreover, the premise of surgery has been challenged. Some authors now advocate percutaneous angioplasty as the treatment of choice for subclavian stenosis.
5 Because experience in percutaneous angioplasty of subclavian artery stenosis after ITA grafting is still small, however, it cannot be recommended at this time.
Coronary steal with inadequate myocardial perfusion is a rare complication after coronary artery bypass grafting with the ITA. In case of recurrent angina after myocardial revascularization, a steal syndrome should be ruled out by careful angiographic examination. The treatment of choice for proximal subclavian artery stenosis is carotid-subclavian bypass.
References
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