Direct Coronary Surgery Utilizing Multiple-Vein Bypass Grafts

Transcription

1 Direct Coronary Surgery Utilizing Multiple-Vein Bypass Grafts W. Dudley Johnson, M.D., Robert J. Flemma, M.D., and Derward Lepley, Jr., M.D. P revious angiographic and pathological studies have shown that atherosclerosis involves primarily the proximal coronary arteries and rarely is limited to only one coronary artery [l, 31. With techniques developed at our institution by which free saphenous vein grafts are attached directly from the aorta to small distal coronary arteries, it has been possible during the past year to increase coronary flow immediately in 97% of patients afflicted with coronary atherosclerosis. Our first successful small artery anastomosis (posterior descending) was performed in July, A short time later, vein grafts were used to the anterior descending and circumflex arteries. Three early deaths from anterior infarcts after successful implantation of posterior vein grafts prompted the first double-vein bypass graft in November, The results were so encouraging that 90 patients have undergone double- and triple-vein bypass grafting during the past 11 months. It is the purpose of this report to discuss the indications, techniques, and angiographic and physiological results of the expanded surgical approach to severe multiple coronary artery disease. PATIENT POPULATION AND INDICATIONS The 90 patients in our series ranged in age from 28 to 66. No patient referred for operation was refused because of the extent of coronary disease. While difficult to define, end-stage disease has often been thought to include patients with ventricular aneurysm, dyskinetic or akinetic myocardium, elevated end-diastolic pressure, or chronic ventricular malfunction as shown by low cardiac output. Forty-two of the 90 patients fell into one or more of these categories; 15 had only two-vessel disease, while 75 had more than 75% occlusion of all three major coronary arteries. The only contraindications to operation have been continued smoking, overt cardiac failure in patients over 70 years of age, and secondary organ deterioration (ascites, renal failure, severe neurological deficits from cerebrovascular accidents). No patient has been seen in whom it was felt that transplantation offered more hope for long-term survival than did the vein bypass technique as employed at our institution. From the Department of Thoracic-Cardiovascular Surgery, Division of Surgery, Marquette School of Medicine, Inc.; St. Luke s Hospital; and Wood Veterans Administration Hospital, Milwaukee, Wis. Presented at the Sixteenth Annual Meeting of the Southern Thoracic Surgical Association, Washington, D.C., Nov , Address reprint requests to Dr. Flemma, 8700 West Wisconsin Ave., Milwaukee, Wis THE ANNALS OF THORACIC SURGERY

2 Direct Coronary Surgery with Vein Grafts OPERATIONS PERFORMED Operations performed and mortality are tabulated in Table 1. Additional procedures such as aneurysmectomy or multiple arterial implants or both were performed simultaneously in 40% of these patients. The pattern of multiple bypass procedures is seen in Table 2. Bypass grafts to any area of the anterior descending or right coronary artery were by far the most common procedure. Obstructions of all three coronary arteries were bypassed in 10 patients. The circumflex artery was the artery least bypassed, reflecting its relative inaccessibility and also the fact that the right coronary artery is usually the dominant artery to the posterior heart. In this posterior lateral area, multiple internal mammary implantation has been utilized frequently as a complementary procedure, using the multiple small artery implant techniques described elsewhere [21. Also, diffuse atherosclerosis involving the fine distal branches of the circumflex artery has been seen more often than terminal atherosclerosis in the anterior descending or right coronary artery. SURGICAL TECHNIQUES Certain principles have been developed which we feel will promote longterm patency and facilitate operative technique. 1. Major areas of stenosis or occlusion nearly always are associated with lesser degrees of atherosclerosis above and below the principal lesion, even though this more diffuse process is not visualized angiographically. Veins can be anastomosed with any 2-mm. artery, and occasionally with even smaller arteries if the artery is normal. The vein, therefore, should be inserted just beyond the last area of atherosclerosis. This means that the right coronary artery is always exposed to the origin of the posterior descending artery, and this area is the most common site for anastomosis (Table 2). Anteriorly, the midportion of the anterior descending artery is the usual site for anastomosis. Should an obstruction exist in the right coronary artery just proximal to or in either branch adjacent to the distal bifurcation, the arteriotomy is made across the plaque into normal coronary artery proximally and distally. In this manner the critical outflow of the bypass enters normal coronary arteries, and the end-to-side technique allows TABLE 1. MULTIPLE-VEIN BYPASS GRAFT MORTALITY No. of No. of Operation Patients Deaths % Triple aorto-coronary vein bypass graft Double aorto-coronary vein bypass graft Total TABLE 2. PATTERN OF MULTIPLE-VEIN BYPASS Artery Pattern No. of Patients Anterior descending, right coronary, and circumflex 10 Anterior descending and main right coronary 28 Anterior descending, right bifurcation, and distal 40 Anterior descending and circumflex 7 Right coronary and circumflex 5 Total 90

3 JOHNSON, FLEMMA, AND LEPLEY the large vein to act as a patch graft over the atherosclerotic area. Also, flow may be established in both the proximal and distal direction. Figure 1 is a demonstration of this kind of approach with resulting bidirectional flow, demonstrating that the retrograde flow will occur to the proximal point of major obstruction. 2. All veins have been anastomosed in an end-to-side manner to the coronary artery. End-to-end anastomosis has never been used and would rarely be feasible in 90% of the arteries whose diameter is less than 3 mm. 3. All veins should be attached directly to the aorta. Vein interposition has never been used because the proximal coronary artery is probably more prone to progressive atherosclerosis than is an additional inch or two of vein graft. Also, the aorta is far more accessible than is the proximal right or left coronary system. 4. Clamps or tapes are never placed on coronary arteries to secure a dry operative field. The coronary arteries are fragile, and the intima is often thick and easily torn or crushed. Only the anterior surface of the vessel is cleared of overlying tissue. Passing of tapes about the coronary arteries may be especially FIG. 1. Vein bypass graft 0 from aorta (A) to distal right coronary artery (arrow). Bidirectional flow is demonstrated as blood flows proximally in main right coronary artery (r) as well as distally in posterior descending artery from anastomosis. This type of anastomosis, obtained by cutting across the last obstructing plaque, is associated with highest flows. Also shown is left vein graft arching Over pulmonary artery to middle third of left anterior descending coronary artery (lad). 438 THE ANNALS OF THORACIC SURGERY

4 Direct Coronary Surgery with Vein Grafts disastrous on the left, since the posterior perforating branches may be damaged with lethal consequence. 5. All vein-coronary anastomoses should be made in a dry, quiet field. In our experience, consistently good suturing in 2-mm. arteries cannot be performed on a moving, bloody target. Electrical fibrillation with intermittent 15-minute intervals of anoxic, hypothermic (30 C.) arrest is used routinely. Under these conditions, more than 330 veins have been inserted with only two arteries being ligated because of technical problems (both obtuse, marginal branches of circumflex artery). More than 80% of all vein grafts (single and multiple) have been restudied, and only one incident of mild anastomotic stenosis was seen angiographically. More than 90% of these vein grafts have been patent. Clinically or angiographically there has been only one late closure of a vein graft in this group of patients. 6. In any coronary artery, but especially in the anterior descending coronary artery, a second isolated plaque often is found distal to the major obstructing lesion. When this occurs, an arteriotomy should be made across the secondary plaque into normal artery above and below, thus preserving bidirectional fow. Such arteriotomies have been as long as 4 cm. This is desirable because in both the right and the anterior descending coronary arteries the highest flows recordxl at operation occur when the veins are inserted to allow bidirectional flow. FIG. 2. Alternative double-vein bypass technique with anterior descending bypass graft branching 08 right vein graft. Marked filling of distal right branches as well as the entire distal anterior descending and septa1 branches can be seen. Patient s work tolerance has markedly increased. VOL. 9, NO. 5, MAY,

5 JOHNSON, FLEMMA, AND LEPLEY A FIG. 3. Postoperative cineangiogram of triple-vein bypass. (A) Anastomosis to the right coronary artery, and (B) patent vein graft to anterior descending artery (lower arrow) with circumflex vein graft (upper arrow) coming 06f anterior descending artery bypass. B 7. In double grafts we prefer to make both proximal anastomoses into the aorta (Fig. 1). If the ascending aorta is friable, thin, or short, the second vein may be placed end-to-side into the first vein (Fig. 2). A third vein usually is placed end-to-side into one of the first two (Fig. 3). RESULTS Table 1 shows the results of multiple-vein bypass procedures in 90 patients. The overall mortality of 22% seems high. But when we consider that more than 40% of these patients would be candidates for transplantation at other centers, this mortality becomes more acceptable. Triple-vein bypasses obviously carry a higher mortality because of the severity of disease, and these would be considered end stage by any criteria. Figure 3 is a postoperative cineangiogram of one such patient who was completely incapacitated with unrelenting continuous angina and failure secondary to threevessel disease. He had become a drug addict through his attempts to relieve the angina. His heart was massive in size, and his ventriculogram revealed a markedly dilated, dyskinetic myocardium. The left ventricular end-diastolic pressure was 15 mm. Hg. Electromagnetic flowmeter studies of the vein grafts prior to closure of the chest revealed a total vein flow of 215 ml. per minute. Cineangiograms three weeks postoperatively demonstrated patency of all three vessels and an im roved ventriculogram. The patient has resumed full-time work as a salesman an B subjectively is free of angina and drug addiction. As seen in Table 3, double-vein bypasses have been carried out for two-vessel disease with a mortality of only 7%, and this was a cerebral death which occurred more than two weeks postoperatively in a patient who never resumed consciousness after cardiopulmonary bypass. This patient s cardiac status was improved, and examination of the vein grafts at the time of autopsy revealed them both to be widely patent. All patients have been asked to undergo recatheterization before leaving the hospital. Seventy-three percent of this group of patients have consented. In a 440 THE ANNALS OF THORACIC SURGERY

6 Direct Coronary Surgery with Vein Grafts TABLE 3. DOUBLE-VEIN BYPASS FOR TWO- AND THREE-VESSEL DISEASE No. of Vessels No. of No. of Involved Patients Deaths % Two Three Total cineangiographic visualization of 108 veins, 97 (90%) have been found to be patent. Only one vein shows any evidence of a stenotic anastomotic area. In these patients with multiple-vein grafts no patient had more than one vein occluded. Flowmeter studies at operation prior to closing the chest have revealed that there is a mean flow of 63 ml. per minute through all vessels studied. In those patients with bidirectional flow in a distal coronary artery, flows have been recorded as high as 185 ml. per minute in an anterior descending coronary artery and 155 ml. per minute in a right coronary artery. Immediate improvement in myocardial contractility often is noted on the operating table, and decrease in heart size is not unusual. Clinically, patients are totally or nearly totally relieved of angina, and most have immediate improvement in failure symptoms. There has been one late death (hepatitis) and only one late infarct in this group of patients. CAUSES OF DEATH Causes of death among 20 patients are summarized in Table 4. Recent myocardial infarction has been a major contributing factor. We have not operated electively within three months of an infarct, and enzymes are always screened on hospital admission. Among the patients with recent infarcts, all had had previous ECG changes, in many cases chronic. Enzyme levels were normal at the time of admission. In this group, nitroglycerine usage ranged as high as 150 tablets per day. Chest pain has been a very unreliable index of further myocardial necrosis. Other patients have been uniformly typical in one respect: They have profoundly irritable hearts which often fibrillate suddenly despite an apparently successful procedure. To avoid operation on the undiagnosed patient who has had a recent infarct, biweekly enzyme studies are now done for at least one month preoperatively on the more advanced patients. TABLE 4. CAUSES OF DEATH IN PATIENTS HAVING MULTIPLE-VEIN BYPASS GRAFTS Cause No. of Patients Cardiac failure 4 Occult recent infarct 7 Cerebral 1 Pulmonary 2 Technical 3 Gastrointestinal 2 Renal 1 Total 20 VOL. g, NO. 5, MAY,

7 JOHNSON, FLEMMA, AND LEPLEY COMMENT Physiological parameters that are being examined to obtain objective evidence of improvement as a result of multiple-vein graft procedures include bicycle ergometry with set workloads preoperatively and postoperatively, preoperative and postoperative atrial pacing to determine at which rate angina develops, lactate production, and measurement of ejection fractions after the method of Weissler [4-61. Preoperative and postoperative results of bicycle exercise with a set workload for one patient are shown in Figure 4. Preoperatively, this 54-year-old woman was able to do 300 kpm of work before experiencing angina. The mean pulmonary pressure was 37 mm. Hg, the left ventricular end-diastolic pressure rose to 24 mm. Hg, and the heart rate was 150. Two months postoperatively she was able to carry out the 300 kpm work with evidence of a smaller rise in mean pulmonary artery pressure, a smaller rise in left ventricular end-diastolic pressure, and a slower heart rate. She even was able to double the amount of work without developing angina. Figure 2 shows the angiographic result of her double-vein graft. At this time there is normal perfusion of the distal anterior and right coronary artery systems. It is apparent that if direct coronary artery surgery is to be most beneficial to the vast majority (95%) of patients with multiple-vessel disease, vein grafting must be able to bypass multiple arteries. The PRE,POST, 4o 50 watt rec 50wott rec. 100 watt sec 937 MPAP 20] % 0 lo 02Cons C.O Med. severe - No angina - Angina No angina FIG. 4. Preoperative and postoperative results of bicycle exercise with set workload for one patient with double-vein b pass graft. (MPAP = mean pulmonary artery pressure; LVEDP = left ventricu Y ar end-diastolic pressure; HR = heart rate.) 442 THE ANNALS OF THORACIC SURGERY

8 Direct Coronary Surgery with Vein Grafts use of multiple bypass techniques, as originally described here, is an attempt immediately to increase myocardial blood flow to multiple areas of ischemia. Since very few patients have single-vessel disease, the multiple-vein techniques obviously could be beneficial to a far wider range of patients than could implants or even single-vein grafts. The techniques and principles developed utilizing end-to-side anastomosis and anastomosis into the normal distal coronary artery, techniques to obtain bidirectional flow, and operation carried out with a quiet, bloodless field are necessary to achieve the objectives. As can be seen from the angiographic results, successful patency can be obtained in vessels 1% mm. or more in diameter. The extension of this technique to include triple-vein grafts, as first described in this report, is at present associated with a high mortality. When we consider, however, that these patients would all be candidates for transplantation in other centers, a 50% survival over a long period of time certainly represents a far more acceptable mode of treatment. SUMMARY Techniques of multiple-vein bypass grafting to all areas of any coronary artery simultaneously have been found to increase substantially the number of patients who may obtain surgical relief of angina and in whom physiological improvements may result from augmented coronary blood flow. The principles developed at this clinic for the successful performance of anastomosis to any coronary artery or combination of coronary arteries in their distal portions have been presented. Angiographic evidence of increased coronary blood flow and preliminary evidence of objective physiological improvement as well as relief of angina in this first series of patients who received multiple double and triple aorto-vein bypass grafts demonstrate the feasibility and desirability of this approach. Further multiple-parameter evaluation of these patients is being studied intensively to document the results with objective data. REFERENCES 1. Blumgart, H. L., Zoll, P. M., and Kunland, G. S. Discussion of direct relief of coronary occlusion. A.M.A. Arch. Intern. Med. 104:862, Johnson, W. D., Flemma, R. J., Lepley, D., Jr., and Ellison, E. H. Extended treatment of severe coronary artery disease: A total surgical approach. Ann. Surg. 170:460, Schlesinger, M. J., and Zoll, P. Incidence and localization of coronary artery occlusion. Arch. Path. 32:178, Weissler, A. M., Harris, W. S., and Schoenfeld, C. D. Bedside techniques for the evaluation of ventricular function in man. Amer. J. Cardiol. 23:577, VOL. 9, NO. 5, MAY,

9 JOHNSON, FLEMMA, AND LEPLEY 5. Weissler, A. M., Harris, W. S., and Schoenfeld, C. D. Systolic time intervals in heart failure in man. Circulation 37:149, Weissler, A. M., Peeler, R. G., and Roehll, W. H. Relationships between left ventricular ejection time, stroke volume, and heart rate in normal individuals and patients with cardiovascular disease. Amer. Heart J , Editor's Note: The experience of Dr. Johnson and his associates is impressive, and their report is particularly pertinent at this time when the field of coronary artery surgery is expanding so rapidly. It is disconcerting, however, to see reports with such short postoperative follow-ups. The present report is about patients undergoing vein bypass grafts during an 11-month period. The cineangiograms were carried out on these patients within three weeks of operation. Experience in other areas of vascular surgery has shown the importance of long-term followup, since late failure of vein grafts is frequent. It is hoped that the authors will report their long-term results in the future. NOTICE FROM THE SOUTHERN THORACIC SURGICAL ASSOCIATION The Seventeenth Annual Meeting of the Southern Thoracic Surgical Association will be held at the Castle Harbour Hotel Golf and Beach Club in Bermuda, November 5-7, Reservations may be made by writing to Miss Loretta C. Kelly, Director of Sales, Castle Harbour Hotel Golf and Beach Club, Bermuda. Members wishing to participate in the scientific program should submit abstracts-typed double-spaced and in triplicate-to Bertram A. Glass, M.D. (Chairman of the Program Committee), 3600 Prytania Street, New Orleans, La The deadline for submission of abstracts is June 1, If additional information is required, inquiries should be directed to Dr. Glass. Application for membership in the Southern Thoracic Surgical Association, on forms provided by the Association, should be sent directly to Harold C. Urschel, Jr., M.D. (Chairman of the Membership Committee), 3810 Swiss Avenue, Dallas, Tex , no later than September 1, Papers that are accepted for the program and are to be considered for publication in The Annals should be submitted to the Editor by October 15, THE ANNALS OF THORACIC SURGERY