Asian Cardiovasc Thorac Ann 2000;8:97-102
© 2000 Asia Publishing EXchange Pte Ltd
Coronary Artery Bypass Grafting Without Cardiopulmonary Bypass
Tevfik Tezcaner, MD,
Cem Yorgancio
lu, MD,
Zeki Çatav, MD,
Ouz Moldibi, MD,
Hilmi Tokmakolu, MD,
Kaya Süzer, MD,
Yaman Zorlutuna, MD
Thoracic and Cardiovascular Surgery Clinic
Bayindir Medical Center
Ankara, Turkey
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For reprint information contact: Tevfik Tezcaner, MD Tel: 90 312 438 1709 Fax: 90 352 437 5285 Re at Nuri Sokak 86/16, Yukari Ayranci, Ankara 06540, Turkey.
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Abstract
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Between March 1994 and April 1998, 2869 patients underwent coronary artery bypass grafting at our institution. Of these, 415 (14.5%) with a mean age of 54.4 ± 9.9 years were operated on without cardiopulmonary bypass. Internal thoracic artery was used in 402 cases (97%) and the left anterior descending artery was revascularized in all except 1. Distal anastomoses ranged from 1 to 3, with a mean of 1.45 ± 0.58. Major postoperative complications comprised reoperation because of internal thoracic artery spasm in 1 patient, lower extremity ischemia due to intraaortic balloon pumping in 1 patient, revision for excessive bleeding in 3, and perioperative myocardial infarction in another 3. Hospital mortality was 1.2% (5 deaths). Coronary angiography was performed in 38 patients, 1 to 44 months postoperatively. Examination of 56 distal anastomoses revealed a patency rate of 86.1% for internal thoracic artery grafts and 55% for saphenous vein grafts. It was concluded that coronary bypass surgery without cardiopulmonary bypass gave favorable results in the early postoperative period. However, considering the late graft patency rates, either patient selection or the technique should be reevaluated.
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Introduction
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Coronary artery bypass grafting (CABG) has taken a valuable place in the treatment of obstructive coronary artery disease during the last 3 decades.1,2 The favorable outcome of this therapeutic approach has gradually improved, mostly due to use of the internal thoracic artery (ITA) and technological and surgical developments. However, there are still some problems with cardiopulmonary bypass (CPB) in practice.3,4 Recently, cardiac surgeons have directed their attention to minimally invasive procedures, including off-pump coronary bypass through a median sternotomy or thoracotomy, port-access coronary bypass or video-assisted thoracoscopic coronary bypass.5–10 Patient selection criteria and indications for use of these techniques have not been examined in detail. Although several large series have been reported, late postoperative angiographic data have been limited, and patient selection criteria has not been based specifically on long-term results. The purpose of this study is to describe our off-pump CABG experience, to present early and midterm results, and to discuss patient selection and technique.
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Patients and Methods
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Between March 1994 and April 1998, 2869 patients underwent coronary artery bypass grafting at our institution. Of these, 415 (14.5%) were operated on without cardiopulmonary bypass. There were 335 males and 80 females, ages ranged from 28 to 83 years (mean, 54.4 ± 9.9 years). Three operations were carried out on an emergency basis; 2 for evolving myocardial infarction and 1 for coronary dissection after a percutaneous transluminal balloon angioplasty procedure. Surgery was performed on an urgent basis (within 24 hours after coronary arteriography) in 20 cases where angina could only be controlled by intravenous nitroglycerine (Table 1
).
The majority of patients (72.3%) had single-vessel disease. A ventricular performance score was obtained after evaluation of the wall motion in 7 left ventricular segments, scored according to kinetic disturbance (normal = 1, hypokinesia = 2, akinesia = 3, dyskinesia = 4, aneurysm = 5). A score of 7 indicates normal function, scores between 8 and 14 indicate moderately impaired function, and scores above 14 indicate poor left ventricular function. According to this classification, 25% of the patients were estimated to have poor left ventricular function (Table l
).
Patient selection was made from patients in whom CABG was recommended. With the consideration of complete revascularization, selection of patients depended primarily on the feasibility of the operation. Recently, the selection criteria were limited to cases unsuitable for CPB. Accessible coronary arteries, non-intramuscular route, absence of diffuse coronary disease, and good caliber of the target coronary arteries constituted feasibility of the operation and could be estimated during the preoperative angiographic examination. The final decision was made by the surgeon in the operating room after evaluation of the coronary arteries. The left anterior descending (LAD) and right coronary artery (RCA) could always be accessed through a median sternotomy. In 2 cases, branches of the circumflex artery could be accessed through a left thoracotomy incision. The procedure was planned so as to allow switching to an open heart operation in the event of intolerable hemodynamic deterioration due to cardiac rotation or development of any complication that necessitated CPB support.
The surgical technique has been described previously in detail.11 Patients were prepared as though an open heart procedure were to be performed. Patient monitoring included electrocardiography, pulse oximetry, and urethral, arterial, central venous, and pulmonary artery catheterization. Cardiopulmonary bypass facilities were kept on standby during the procedure. After preparation of the grafts, 1 mg•kg–1 heparin was administered. Exposure of the LAD and diagonal artery was accomplished with sponges placed behind the heart. The RCA was exposed with a stay sponge around the inferior vena cava or with stay sutures passed from the acute margin of the heart. To obtain an arrested anastomosis area, stay sutures of 5/0 Prolene (Ethicon Ltd, Edinburgh, Scotland, UK) were passed twice around the coronary artery, just proximal and distal to the planned arteriotomy site, and other stay sutures of 5/0 Prolene were passed from the epicardium close to the anastomosis site.
Follow-up coronary arteriography was recommended to all patients who described angina. However, after the first 2 years of this experience, all patients whether symptomatic or not, were asked to undergo coronary arteriography.
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Results
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Numerical data are expressed as mean ± standard deviation. Operative findings are shown in Table 2. ITA was used in 402 patients to revascularize the LAD. During RCA revascularization, complete atrioventricular block developed in 2 patients, which was managed by temporary cardiac pacing. Normal sinus rhythm was restored after completion of the anastomoses. During LAD revascularization, ventricular fibrillation developed in 1 patient, in whom normal sinus rhythm was restored after a single defibrillation. In 1 patient, ITA spasm was suspected because of significant anterior ST-segment elevation after her arrival in the intensive care unit. She was returned to the operating room and a saphenous vein graft was added to the LAD, again without the use of CPB.
The early postoperative period was generally uneventful. An intraaortic balloon pump was used in 1 patient and positive inotropic agents in 9. Mean mediastinal blood drainage was 610 ± 279 mL. The patients were weaned from ventilation after a mean time of 6.7 ± 4.5 hours. Major complications comprised cerebrovascular accident in 2, reoperation due to excessive bleeding in 3, perioperative myocardial infarction in 3, and lower extremity ischemia due to intraaortic balloon pumping in 1 patient. Two patients with low cardiac output and 3 with perioperative myocardial infarction constituted the hospital mortality (1.2%). Mean durations of hospitalization and intensive care unit stay are given in Table 3.
All survivors could be followed up postoperatively. Premature angina was noted to develop in 18 cases (Table 4). Coronary arteriography was performed in 38 patients between 1 and 44 months postoperatively; 20 patients were asymptomatic. A total of 56 distal anastomoses were evaluated. Examination of these grafts revealed a patency rate of 86.1% in ITA grafts, 55% in saphenous vein grafts, and 75% overall. Anastomosis stricture was noted in 5 cases. In 18 patients, development of a total of 22 new coronary artery obstructions was determined. Percutaneous transluminal coronary angioplasty was performed successfully in these patients, except for 1 who had an occluded graft on the diagonal artery (Table 5).
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Discussion
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It is essential to perform CABG in an arrested and bloodless area. This situation is especially important in 3-vessel disease in order to obtain complete revascularization. Coronary artery bypass grafting has continually improved since 1970 and favorable early and late results have been achieved. It is important to clarify that this progressive improvement has always been in parallel with technological developments. Several studies and large trials defined the method of bypass grafting, as well as the outcome in terms of mortality and morbidity.12,13 According to these studies, conventional CABG (with CPB) offers a convenient and a safe mode of surgery. However, CPB in practice, although minimized, has some problems, especially in patients with malignancy, renal failure, pulmonary disease, coagulation defects, cerebrovascular disease, poor left ventricle function, or in geriatric patients.3,4 Recently, several cardiovascular surgical teams directed their attention to minimally invasive CABG to offer new horizons in cardiac surgery as well as to eliminate the effects of CPB.5–10,14
Preparation of the patient as for open heart surgery gives the surgeon more choices during the operation and makes it easier to decide on aggressive treatment of any complication or to switch to an open heart procedure. During cardiac manipulation or coronary anastomosis, hemodynamic or rhythm disturbances may complicate the procedure. These problems can be followed in detail in patients who are fully monitored, and correct and radical management can be performed. In this series, cardiac manipulations were tolerated well and switching to an open heart procedure was not necessary in any case. Rhythm problems were noted in 3 patients during coronary anastomosis and appropriate management provided time for completion of the procedure. It is our belief that LAD revascularization is better tolerated than RCA revascularization, especially in patients with a dominant and noncritically obstructed RCA. In such cases, we recommend placing temporary pacemaker wires and being ready for pacing before RCA revascularization. In 1 patient not included in this series, the right ventricular cavity was opened during LAD exploration. The operation was quickly switched to an open heart procedure; anastomosis and right ventricular repair were performed under CPB.
In this series, the heart was slowed by intravenous metoprolol or recently, by diltiazem, after opening the pericardium. This made it easier for the surgeon to synchronize with the heart. Besides this advantage, increased tolerance of ischemia during coronary anastomosis can be achieved by reducing the heart rate.
Early postoperative results in this study were favorable and encouraging. Besides the low complication rates, patients were extubated, mobilized, and discharged from the hospital earlier. These altogether improved the surgical outcome and reduced the hospital costs. In the beginning of this experience, patient selection criteria consisted of indication for CABG, feasibility of complete revascularization, and the accessibility and suitability of the coronary arteries. The series was extended after obtaining successful early postoperative results, until the results of postoperative coronary arteriography were obtained. Although the operations were performed by members of the team who were experienced in conventional coronary bypass, it was considered that the late angiographic results were not within tolerable limits.
Distal anastomosis on a beating heart is a meticulous procedure. Besides the technical difficulty, the quality of the anastomosis is an important issue. Graft patency rates were reported in earlier studies, most of which included short-term rates. Buffolo and colleagues14 reported a patency rate of 83.9% for saphenous vein grafts in 41 patients, and Stanbridge and colleagues15 found rates of 85% for left ITA grafts and 57% for right ITA grafts in 38 patients assessed before discharge. During the first postoperative month, patency rates of 87.5% for ITA grafts and 93% for vein grafts in 54 patients were noted by Benetti and colleagues.9 However, early graft patency rates seem to have improved in recent series and the groups of Jansen16 and Cartier17 reported rates of 95% and 100%, respectively. These improved rates may be related to the use of tissue stabilizers. Local tissue stabilization with stay sutures, which was recommended in the early era of minimally invasive coronary artery bypass grafting, was used in this series. It was thought to be satisfactory because ease of surgery was achieved and coronary anastomosis was accomplished through clear vision. However, our patency rates are inferior to other recent results and we are forced to reevaluate our technique.
It was concluded that off-pump coronary bypass is a safe and effective procedure with regard to the early clinical results but its efficiency needs to be improved in terms of patency rates, and the use of tissue stabilizers should be considered.
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References
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Abstract
Introduction
