Management during Reoperation of Aortocoronary Saphenous Vein Grafts with Minimal Atherosclerosis by Angiography

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1 Management during Reoperation of ortocoronary Saphenous Vein Grafts with therosclerosis by ngiography William G. Marshall, Jr., M.D., Jeffrey Saffitz, M.D., and Nicholas T. Kouchoukos, M.D. STRCT The proper management of saphenous vein grafts showing minimal angiographic evidence of atherosclerosis at the time of reoperation for progressive atherosclerosis in the native coronary circulation or for severe atherosclerosis in other saphenous vein grafts is uncertain. Following the occlusion of vein grafts in 2 patients and 12 years after operation but only 2 years after arteriography demonstrated no major abnormalities in the grafts, we adopted a policy of elective replacement of all saphenous vein grafts, irrespective of angiographic findings, when reoperation was necessary 5 or more years after the initial operation. etween July, 194, and May, 195,16 patients had repeat coronary artery bypass grafting 6 to 13 years (mean, 9 years) after the initial procedure. Complete revascularization was carried out in all patients. In each, it included replacement of at least 1 saphenous vein graft showing no severe obstruction (less than 30% of the luminal diameter) and no (5 patients), minimal (S), or moderate (3) luminal irregularities by angiography. y pathological examination, 3 of the grafts had minimal, 5 had moderate, and had severe atherosclerotic changes present. These changes were generally more diffuse than those observed by angiography. ecause angiography underestimates the severity of the atherosclerotic degeneration in saphenous vein grafts and because of the propensity of the atherosclerotic disease to progress at an unpredictable rate, we recommend routine replacement of all saphenous vein grafts at the time of reoperation if done 5 or more years after the initial procedure. Long-term follow-up studies of patients having coronary artery bypass grafting (CG) with autologous saphenous vein have shown that degenerative changes indistinguishable from atherosclerosis develop in a substantial number of these grafts [l-41. During repeat CG procedures for recurrent symptoms resulting from progression of the atherosclerotic process in the native coronary circulation or in the previously inserted vein grafts, From the Division of Cardiothoracic Surgery and the Department of Pathology, Washington University School of Medicine, St. Louis, MO. Presented at the Thirty-second nnual Meeting of the Southern Thoracic Surgical ssociation, oca Raton, FL, Nov -9, 195. ddress reprint requests to Dr. Marshall, Division of Cardiovascular and Thoracic Surgery, Jewish Hospital of St. Louis, 216 S Kingshighway lvd, St. Louis, MO 631. those grafts that are occluded or severely diseased are replaced. The proper management of vein grafts showing no or minimal angiographic evidence of atherosclerosis is not established. Following the occlusion of single vein grafts in 2 patients and 12 years postoperatively but only 2 years after angiography demonstrated no severe atherosclerotic disease in these grafts, we adopted a policy of elective replacement of all vein grafts in patients undergoing repeat CG 5 or more years following the initial procedure (Fig 1). In this report, we present the angiographic and pathological findings in vein grafts electively replaced at reoperation in 16 patients and a plan of management for similar patients that is based on these findings. Material and Methods etween July, 194, and ugust, 195, 16 patients with at least 1 previously inserted saphenous vein graft showing luminal irregularities of less than 30% of the luminal diameter by angiography, underwent repeat CG. The mean age of these patients was 63 years (range, 3 to 9 years), and (63%) were men. The mean length of time the saphenous vein grafts in question had been in place was 9 years (range, 6 to 13 years). The mean number of grafts placed at the previous operation was 2.3 (range, 1 to 3). Recurrent angina pectoris was the indication for reoperation in 15 patients, and failure of an aortic porcine bioprosthesis was the indication in 1 patient with coexistent coronary artery disease. Coronary arteriography was performed in all patients prior to repeat CG. The vein grafts showing less than 30% obstruction of the luminal diameter in at least two projections were classified as follows: -No areas of luminal irregularity -Luminal irregularities with no areas of obstruction greater than 15% of the diameter of the graft -Luminal irregularities greater than 15% but less than 30% of the diameter of the graft Four patients had a single graft at the initial operation and underwent repeat CG because of progression of disease in the native circulation. ll 4 of these grafts were classified as normal angiographically. Three patients had 2 grafts placed initially. One had recurrence of angina due to progression of disease in the native coronary circulation with both grafts classified as normal by angiography. The other 2 patients had occlusion of nn Thorac Surg 42:163-16, ug 196

2 164 The nnals of Thoracic Surgery Vol 42 No 2 ugust 196 Fig I. () rteriogram shows suphenous vein graft with minimal luminal irregularity 5 years after insertion. () rteriogram made 2 yeurs later demonstrates occlusion of same vein graft. graft, minimal disease in the other graft, and progression of disease in the native circulation. The remaining 9 patients received 3 grafts initially. Four of these patients had occlusion of 1 graft and severe disease in a second graft. Three of these 4 patients had a third graft with minimal disease present, and the fourth patient had moderate disease present in the graft electively replaced. Two of the 9 patients had severe disease in 2 grafts with minimal disease in the third graft in 1 patient and moderate disease in the third graft in the other. In 2 patients, 2 grafts were occluded with minimal disease in the third graft in 1 patient and moderate disease in the third graft in the other. One patient had occlusion of 1 graft with minimal disease in the other 2 grafts. Seven of these 9 patients also had severe progression of disease in the native coronary arteries. In the 2 patients who had 2 grafts with luminal irregularities of less than 30%, the least diseased graft was evaluated. Fourteen of the patients had elective CG, and 2 had urgent operation for severe unstable angina. Thirteen of the operations were secondary procedures, and 3 were tertiary. One patient had concomitant replacement of a malfunctioning aortic bioprosthesis, and 1 had mitral valve replacement for coexistent mitral regurgitation. ll repeat operations were performed with hypothermic (26" to 30"C), nonpulsatile cardiopulmonary bypass with moderate hemodilution. cold (4 C) oxygenated hyperkalemic crystalloid cardioplegic solution was used for myocardial protection. Reversed saphenous vein grafts (single or sequential) were used in all patients, and the left internal mammary artery was used in patients. The mean number of arteries grafted was 3.6 (range, 2 to 5). Segments of the 16 grafts electively replaced and containing the areas of luminal irregularity when present, were opened longitudinally and visually inspected for evidence of atherosclerosis. Thirteen of the grafts were photographed, and using tracings of these photographs, the fraction of the total intimal surface involved with atherosclerosis was determined by planimetry. The vein grafts were classified according to the extent of involvement of the intimal surface: minimal, less than 15%; moderate, 16 to 30%; and severe, more than 30%. Photographs were not available for 3 of the grafts, and the severity of the atherosclerosis in these grafts was estimated from gross and histological examination. Results There was 1 hospital death (6%). The patient could not be weaned from cardiopulmonary bypass at the end of the procedure. Postmortem examination of the heart showed multiple old myocardial infarctions and acute hemorrhagic infarction in the posterior left ventricular wall in the distribution of an occluded saphenous vein graft. One patient (6%) sustained a perioperative myocardial infarction, which probably resulted from inadequate flow through a new left internal mammary artery graft to the left anterior descending coronary artery. The angiographic and pathological findings in the 16 patients are shown in Table 1. None of the 5 grafts with a normal angiographic appearance were free from atherosclerosis (Fig 2). The angiographic estimate of the severity of atherosclerosis underestimated the severity determined by pathological examination in 13 (1%) of the 16 grafts (Table 2). The underestimation was substantial in 9 (56%): with normal angiographic findings, there were moderate or severe pathological changes; with minimal angiographic changes, there were severe pathological changes (Figs 3, 4). There was no correlation between the length of time the grafts had been in place and the severity of the atherosclerotic involvement (Table 3). Comment Long-term follow-up studies of patients having CG with autologous saphenous vein have shown that degenerative changes indistinguishable from atherosclerosis develop in a substantial number of these grafts [l-31. mong grafts evaluated angiographically to 12

3 Fig 2. () rteriogram shows no luminal irregularities in the saphenous vein graft (normal). () The same vein graft after excision reveals minimal atherosclerotic changes. Fig 3. () rteriogram shows luminal irregularities of less than 15% of the luminal diameter (minimal disease). () The same vein graft after excision demonstrates severe atherosclerotic changes. Fig 4. () rteriogram reveals luminal irregularities of greater than 15% but less than 30% of the luminal diameter (moderate disease). () The Same vein graft after excision shows moderate atherosclerotic changes. 165

4 166 The nnals of Thoracic Surgery Vol 42 No 2 ugust 196 Table 1. Summary of Patient Data Patient ge Of Severity of therosclerosis % Of No., ge Graft Graft (Yr) (yr) ngiographic Pathological Surface " " " N 1 36 N N 39 5 "Photograph was not available; severity was estimated from gross and histological examination. N = not available. Table 2. Comparison of ngiographic and Pathological Findings Pathological ngiographic Total Total Table 3. Comparison of ge of Graft and Severity of therosclerotic Changes ge of Graft (yr) therosclerotic Change Total Total years after operation by Campeau and co-workers [l], 42 (39%) were occluded. Of the 66 patent grafts, 40 were considered unsatisfactory primarily because of late changes attributed to atherosclerosis. Only 26 grafts (24%) were classified as satisfactory (unchanged or with diffuse narrowing of less than 20% of the luminal diameter). Campeau and associates [2] also found that in grafts patent 6 to 1 months postoperatively, 30% had occluded at to 12 years and 32% had developed new atherosclerotic changes, defined as wall irregularities and focal narrowings by angiography. They also showed that the incidence of changes increased from 16% in the interval between 1 year and 5 to years postoperatively to 36% in the interval between 5 to years and to 12 years. Lytle and colleagues [3] discovered that among a group of 501 patients studied a mean of 15 months postoperatively who had normal grafts by angiography and who were restudied at a mean of months postoperatively, new stenoses or irregularities had developed in 1% of the grafts and 26% were occluded. These studies indicate that atherosclerotic changes occur with time and are progressive, although the rate of progression in an individual patient or graft cannot be accurately predicted. The study of Campeau and colleagues [2] also suggested that the rates of progression of atherosclerosis and occlusion of the grafts are substantially increased between the sixth and twelfth years compared with the first 5 years. Smith and Geer [5] in autopsy studies found that atherosclerotic changes were present only in saphenous vein grafts that had been in place more than 39 months, and that 0% of the vein grafts examined had such changes. Kern and colleagues [6] also reported major atherosclerotic changes in surgically excised saphenous vein grafts that had been in place an average of 6 to years in 13 of 40 patients. ll of the vein grafts in the present study had been in place more than 6 years, and all had atherosclerotic changes. The cases of the 2 patients seen initially and that prompted this analysis demonstrate that the rate of progression of disease, even in grafts judged to be normal or minimally diseased by angiography, can be rapid. These grafts, which were inserted to 12 years previously, progressed to total occlusion in 2 years. Underestimation by angiographic criteria of the pathological changes in the native coronary circulation has been previously demonstrated []. In our study, there was substantial underestimation by angiography of the atherosclerotic disease in the saphenous vein grafts in 56% of the grafts examined. Previous studies [4, 1 demonstrated that reoperative CG can be performed without excessive risk. There was only 1 death and 1 major complication (perioperative myocardial infarction) in this series. The decision to replace mildly diseased grafts required the insertion of 1 additional graft in 14 patients and 2 grafts in 2 patients. The extra ten to twenty minutes of myocardial ischemia and the twenty to forty minutes of total operating time were tolerated without difficulty in all surviving patients and were not associated with increased morbidity. ecause of the underestimation of the atherosclerotic

5 16 Marshall, Saffitz, Kouchoukos: Management of Saphenous Vein Grafts at Reoperation disease in saphenous vein grafts by angiography, the frequency with which atherosclerotic disease exists in such grafts after 5 years, the inability to predict the rate of progression of the atherosclerosis in a given graft or patient, and the safety with which reoperative CG can be performed, we believe that saphenous vein grafts that have been in place more than 5 years should be replaced regardless of their angiographic appearance. ddendum Since submission of this manuscript for publication, 2 additional patients have had replacement of vein grafts with normal angiographic appearance as previously defined. One had moderate atherosclerotic changes involving 1% of the luminal surface, and 1 had severe atherosclerotic changes involving 39% of the luminal surface. oth grafts had been in place years. The technical assistance of Therese Wedige-Stecher is gratefully acknowledged. References 1. Campeau L, ourassa MG, Enjalbert M, Lesperance J: Fate of saphenous vein aortocoronary bypass grafts -12 years after surgery. In Rapaport E (ed): Cardiology Update: Review for Physicians. msterdam, Elsevier, 194, pp Campeau L, Enjalbert M, Lesperance J, et al: therosclerosis and late closure of aortocoronary saphenous vein grafts: sequential angiographic studies at 2 weeks, 1 year, 5- years, and -12 years after surgery. Circulation 6:Suppl2:1, Lytle W, Loop FD, Cosgrove DM, et al: Long-term (5-12 years) serial studies of internal mammary artery and saphenous vein coronary bypass grafts. J Thorac Cardiovasc Surg 9:24, Loop FD, Cosgrove DM, Kramer JR, et al: Late clinical and arteriographic results in 500 coronary arterial reoperations. J Thorac Cardiovasc Surg 1:65, Smith SH, Geer JC: Morphology of saphenous veincoronary artery bypass grafts. rch Pathol Lab Med 13, Kern WH, Wells WJ, Meyer W The pathology of surgically excised aortocoronary saphenous vein bypass grafts. m J Surg Pathol5:491, 191. rnett EN, Isner JM, Redwood DR, et al: Coronary artery narrowing in coronary heart disease: comparison of cineangiographic and necropsy findings. nn Intern Med 91:350, 199. Schaff HV, Orzulak T, Gersh J, et al: The morbidity and mortality of reoperation for coronary artery disease and analysis of late results with use of actuarial estimate of event-free interval. J Thorac Cardiovasc Surg 5:50, 193