Asian Cardiovasc Thorac Ann 2001;9:315-317
© 2001 Asia Publishing EXchange Pte Ltd
Complete Myocardial Revascularization in Severe Arteriopathy
Augustine TM Tang, FRCSEd,
Mohan Devbhandari, FRCS,
Sunil K Ohri, FRCS
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Department of Cardiac Surgery Wessex Regional Cardiac & Thoracic Unit Southampton General Hospital Southampton, Hampshire, England, UK
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For reprint information contact: Augustine TM Tang, FRCSEd Tel: 44 23 8077 7222 Fax: 44 23 8079 8508 email: gus.tang{at}ntlworld.com Department of Cardiac Surgery, Wessex Regional Cardiac & Thoracic Unit, Southampton General Hospital, Tremona Road, Southampton SO16 6YD, Hampshire, England, UK.
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ABSTRACT
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Multivessel coronary revascularization was successfully performed in a 75-year-old man with severe atherosclerosis of the ascending aorta and aortic arch, significant stenoses in the right subclavian, innominate, and aortoiliac arteries, renal impairment, and conduit shortage, by combining the beating-heart approach with aorta-sparing pedicled arterial and venous grafts. No postoperative complications were encountered.
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INTRODUCTION
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Complete myocardial revascularization in the presence of severe atherosclerosis of the ascending aorta poses a technical challenge to the surgeon. Handling of the aorta during cannulation and clamping may induce dissection and embolism. The situation can be rendered more complex by generalized arteriopathy and shortage of conduits.
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CASE REPORT
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A 75-year-old man with worsening dyspnea, angina, and bilateral leg claudication was referred for coronary artery bypass grafting (CABG). Exercise tolerance on admission was limited to 100 m, predominantly by calf pain. Risk factors for coronary disease included chronic smoking, hypercholesterolemia, and a positive family history. Preoperative electrocardiography showed atrial fibrillation with a previous inferior Q-wave infarct. Angiography was initially attempted via the right brachial route but it was abandoned due to significant stenoses involving the right subclavian and innominate arteries (Figure 1
). The digital subtraction image also revealed right common carotid stenosis that on Doppler ultrasound was judged not to require endarterectomy. A second attempt via the right femoral approach successfully demonstrated triple-vessel coronary artery disease in addition to significant aortoiliac occlusive disease. The ventriculogram confirmed a limited inferior infarct and moderate overall function. In view of a systolic murmur detected clinically, transesophageal echocardiography was performed, which revealed mild mitral valve regurgitation, probably of ischemic origin. Furthermore, a large pedunculated mobile plaque was detected in the aortic arch, which oscillated with pulsatile blood flow (Figure 2). Preoperative clinical assessment indicated reduced right brachial blood pressure consistent with the subclavian stenosis detected angi-ographically, bilateral varicose saphenous veins, and inadequate ulnar collateral supply in both hands. Routine blood testing disclosed elevated serum creatinine of 234 µmol•L-1.
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Figure 1. Transbrachial arteriography showing severe stenoses of the innominate and right subclavian arteries (black arrowheads).
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Figure 2. Transesophageal aortography demonstrating a large pedunculated and mobile plaque in the aortic arch (white arrowhead).
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In view of the severe aortic atherosclerosis and risk of cerebral and renal injury, CABG was performed without cardiopulmonary bypass (CPB) on the beating heart. Surgical exposure was achieved with a median sternotomy, a modified "Lima" pericardial positioning suture, and a suction-based mechanical stabilizer (Octopus; Medtronic, Watford, Hertfordshire, UK). Given the shortage of appropriate conduits, a pedicled left internal thoracic artery (ITA) graft was harvested and anastomosed to the left anterior descending artery; an "inverted" right ITA pedicle was harvested, found to have adequate flow (60 mL•min-1) from the epigastric axis, and grafted to the distal right coronary artery. Revascularization was completed with a non-varicosed segment of saphenous vein grafted to the intermediate branch of the left coronary artery; the proximal end of the vein graft was anastomosed end-to-side to the left ITA pedicle in a "T" configuration. Distal myocardial perfusion was maintained during coronary anastomoses using intracoronary shunts (Medtronic, Watford, Hertfordshire, UK). The patient remained hemodynamically stable throughout the procedure, requiring only minimal inotropic support that was soon tapered off. He made an uneventful postoperative recovery and did not suffer any cerebral or renal complications. At the 4-month follow-up, he showed significant symptomatic improvement with exercise tolerance limited only by fatigue. A radionuclide perfusion scan confirmed adequate regional myocardial blood flow both during stress and after redistribution.
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DISCUSSION
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Due to a common etiology, coronary artery disease often coexists with other manifestations of a generalized arteriopathy. The incidence of significant carotid and peripheral vascular disease in CABG patients is approxi-mately 33% and 16%, respectively.1 The prevalence of aortic atherosclerosis in coronary patients is probably underestimated by clinical criteria.2 Diffuse aortic atheroma is much more common than is realized by intraoperative palpation.3 On the basis that most aortic plaque may remain asymptomatic, routine screening of cardiac surgical patients by intraoperative transesophageal echocardiography or epiaortic ultrasound has been advocated.3 Vascular comorbidity increases both the technical challenge and complications of coronary surgery. In on-pump CABG, aortic atherosclerosis is a known risk factor for cerebral embolism and neurological injury.4 This is manifested clinically in early and late postoperative strokes.5 The risk of embolic stroke in the presence of the large mobile plaque in the aortic arch of our patient would have been substantial if a cannula had been inserted for CPB. Preexisting renal impairment is also known to be exacerbated by CPB. A low-risk strategy was therefore needed to avoid aortic manipulation and CPB.
Various approaches have been taken to minimize cerebral complications in patients with significant aortic athero-sclerosis. Concomitant ascending aortic replacement under hypothermic circulatory arrest has been performed with low rates of perioperative mortality and stroke.6 However, long-term survival is poor and limited by general atherosclerosis. A less radical approach involving axillocoronary bypass grafting on a beating heart has the added benefit of avoiding neurological injury induced by CPB.7 However, adequate lengths of saphenous vein must be available for this technique because of the long extraanatomical route taken by the grafts. The shortage of appropriate conduits in this patient posed a further surgical challenge. Right subclavian artery stenosis proximal to the origin of the ITA precluded the use of a pedicled right ITA graft because of concerns over subclavian steal. The low incidence (approximately 3%) of significant subclavian artery stenosis revealed by differential brachial pressures in coronary patients, greatly increases in the presence of peripheral vascular disease.8 Routing a free right ITA graft to the pedicled left ITA would entail an extra anastomosis and render the entire new blood supply dependent on a single source. Our preferred solution was an "inverted" right ITA graft that provided acceptable flow and avoided aortic anastomosis. This technique has already been proven effective both experimentally and clinically in on-pump CABG.9 We chose not to use a gastroepiploic artery graft in this case to avoid the morbidity of an associated laparotomy and a more prolonged operation.
Postoperative angiographic evaluation of graft patency in this patient would have carried considerable risk because of the severe arteriopathy. Furthermore, it would have been technically impossible to selectively demonstrate the "inverted" right ITA graft using this approach. Concordance between symptomatic and radionuclide parameters nevertheless pointed to a successful early outcome. The combined approach of off-pump CABG and use of aorta-sparing grafting techniques allowed complete myocardial revascularization while avoiding the major complications associated with severe and diffuse arteriopathy.
Presented at the 10th World Congress of the International Society of Cardiothoracic Surgeons, Vancouver, British Columbia, Canada, August 13–16, 2000.
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ABSTRACT
INTRODUCTION
