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Multiple coronary artery bypass using sequential technic
Multiple Coronary Artery Bypass Using Sequential Technic Ricardo J. Moreno-Cabral, MD, Honolulu, Hawaii Richard T. Mamiya, MD, Honolulu, Hawaii Collin R. Dang, MD, Honolulu,
Hawaii
Recent evidence suggests a direct correlation between the relief of symptoms of myocardial ischemia and the completeness of myocardial revascularization [I]. The present report concerns our initial attempt at achieving this goal by utilizing the sequential technic of multiple grafting. Clinical Material
During a two year period (January I,1975 to December 31, 1976) 410 patients underwent coronary bypass grafting. The present report is limited to the technic used and early results obtained in 206 of these patients who underwent four to nine coronary bypasses with or without associated procedures. Ages ranged from thirty-three to- seventy-six years (mean, 55 years); 183 patients (89 per cent) were male and 23 (11 per cent) were female. All patients had severe coronary arteriosclerosis and ninety-three (45 per cent) had had previous clinical myocardial infarctions, six of whom had been resuscitated from cardiac arrest. One patient had four previous infarctions, five patients had three, and seventeen patients had two. Selective coronary arteriography showed complete occlusion of one to three major vessels in 138 patients (68 per cent) (right coronary artery, 80 patients [39 per cent]; left anterior descending coronary artery, 59 patients [29 per cent]; and circumflex artery, 53 patients [26 per cent]). Left ventricular function was considered good in 124 patients (60 per cent), fair in 58 (28 per cent), and poor in 24 (12 per cent). The distribution and number of grafts per patient are shown in Table I. Ten patients underwent associated procedures in addition to coronary bypass: 6 left ventricle aneurysm plication (5 quadruple bypasses, 1 quintuple); 1 left ventricular aneurysm resection (quadruple bypass); 1 mitral valve replacement (quadruple bypass); 1 double valve replacement (quintuple bypass); and 1 coronary fistula ligation (quadruple bypass). Indications for surgery were progressive angina in 182 patients (88 per cent), preinfarction angina in 18 (9 per cent), and acute myocardial infarction in 1 (0.5 per cent). Five patients (2.5 per cent) were asymptomatic, and operation was undertaken because of abnormal Treadmill test results and angiographic evidence of three-vessel disease. From the Department of Surgery, University of Hawaii, John Burns School of Medicine, Honolulu, Hawaii. Reprint requests should be addressed to Richard T. Mamiya, MD, 1301 Punchbowl Street, Honolulu, Hawaii 96813. Presented at the Forty-EighthAnnual Meeting of the Pacific Coast Surgical Association. Palm Springs, California, February 20-23, 1977.
64
Surgical Technic
The long saphenous vein is harvested in its entirety by long incisions with a single skin bridge at the knee. This allows atraumatic and rapid removal of the veins. Should the long saphenous system not be available, the cephalic system is used. Cardiopulmonary bypassing is performed in all patients with aortic cannulation for arterial perfusion, and single right atria1 cannulation is performed for venous return. The left side of the heart is not vented. Moderate systemic hypothermia (30°C), cardiacischemiawithlocalcoolingisused. Pericardial bathing with cold saline was used early in this series, but we now use aortic root infusion of 500 cc Ringer’s lactate plus 10 mEq potassium chloride at 4°C. During systemic cooling, the coronary arteries to be used for anastomosis are marked by incising the epicardium. Technics, of Anastomoses. All anastomoses, whether end-to-side or side-to-side, are performed by a single continuous suture of 6-O Proleneo, including the epicardium in the suture. Venotomies are made longitudinally because transverse incisions often produce varying degrees of kinking. Suturing is started at the heel of the anastomosis, and the first three stitches are placed with the vein and artery apart for maximal visualization. (Figure 1.) The rest of the suturing is made with the vein and arteries together. This technic allows good visualization of every stitch, especially the crucial ones at both ends of the anastomosis. The size of the arteriotomy varies TABLE I
Distribution and Number of Grafts in 206 Patients
Arterial System LAD system Diagonals Circumflex system Distal Marginals Right system Proximal Posterior descending distal Total
Total
Average No. of Grafts per Patient
206 246
452
2.2
196 97
293
144 93
237
982
962
No. of Grafts
1.4
1.2 and
4.6
The American Journal of Surgery
Sequential Multiple Coronary Artery Bypasses
Figure 1. The-bypassing sequence is usually started with an en&to-side anaMmo& to a circumfiex marginal branch.
with the size of the artery but generally is approximately 4 to 6 mm. Normal vessels are preferred for the arteriotomy, but frequently when a significant distal plaque is present, a long arteriotomy is made through this area to assure perfusion of the maximal length of artery. All distal coronary anastomoses are performed under continuous aortic occlusion. Routing of Bypass. An important consideration in the sequential technic is the proper routing of the bypass. The course of the bypass is chosen so as to minimize kinking, and no special attempt is made to keep the largest runoff at the end of the bypass. The end-to-side anastomosis is performed first, and the second venotomy site for a side-to-side anastomosis is chosen after the vein is distended with saline and its course arranged properly. (Figures 2 and 3.) All subsequent sites are chosen in the same manner to assure a proper length between anastomoses. Tacking sutures of 6-O Prolene are used to hold the course of the bypass when necessary.
Figure 2. Lefl, proper alignment is obtained by distending the vein with saline and choosing the venotomy site. Right, venotomy is made with vein distended.
Left Coronary Bypass System. The usual sequence in bypassing the left coronary artery system is an end-to-side anastomosis to a marginal branch of the circumflex artery, a side-to-side anastomosis to the diagonal branch, and another side-to-side anastomosis to the left anterior descending artery. Any other branches in the route described are also bypassed if necessary by side-to-side anastomosis. At the completion of the last anastomosis, the vein is transected after estimating the necessary length to follow a gentle curve towards the aorta. As many as six bypasses have been attached to this single limb. If the distal end or a second marginal branch of the circumflex artery is to be bypassed, this is included in the bypass to the right coronary artery system. Right Coronary Artery System. Usually, a fair degree of disease is encountered in the right coronary artery at the bifurcation, so most of the grafting is now done to the posterior descending and the distal right coronary arteries after the bifurcation. The
Moreno-Cabral,
Mamiya, and Dang
Figure 3. A to E, technic of side-to-side anastomosis. F to H, wturina is completed with clear viwallza~ion of eiety stitch.
Figure 4. The sequence in the posterior aspect of ths heart depends on the locatkn and number of lesions and the length of vein available. 66
posterior descending and distal right coronary arteries are bypassed in sequence to provide the best route without kinking. If the distal circumflex artery is to be bypassed, the bypass is started at this vessel with an end-to-side anastomosis and the right and posterior descending arteries are sequentially placed side-to-side. (Figure 4.) Ao’rtic Anastomosis. The aortic cross clamp is released upon completion of the last coronary anastomosis, a partial occluding clamp applied, and longitudinal aortotomies performed. The vein is occluded proximal to the last anastomosis, filled with saline, and obliquely transected after estimating the necessary length to the aortic incision. The heel three corner stitches are placed under unobstructed view. (Figure 5.) At this time electrical defibrillation is accomplished if no spontaneous beat has occurred. Figure 6 shows the most common sequence used in this series. Duration of Aortic Cross-Clamping and Bypass Procedures. In early 1975, operations were performed on twenty-eight patients without cross-clamping the The American Journal of Surgery
Sequential Multiple Coronary Artery Bypasses
Figure 5. A, partial occluding clamp is applied and aortic
root pettWon catheter removed. B, the in&ion is enlarged with Potts scissors. C, two incisions can be made simultaneously on alternate skies with a scalpel. D, anastomosis performed with continuous 6-O Prolene.
aorta. In the subsequent 178 patients we used the single continuous cross-clamping technic. Aortic cross-clamping time ranged from 25 to 93 minutes (mean, 59 minutes) and was longest in a patient with diffuse arteriosclerosis and multiple occlusions of all major vessels who received nine coronary artery bypasses. The cross-clamping time correlated directly with the number of bypasses. (Table II.) The mean duration of the cardiopulmonary bypass procedure was 1 hour 46 minutes. The longest times were associated with multiple coronary bypass and valve replacement.
Figure 6. Most common sequential bypasses used In this series. TABLE II
Duration of Bypass and Cross Clamping
No. of Grafts
Average Pump Time
Average CrossClamping Time
4 5 6 7 8 9 Total 4.8
1hr 40min 1hr 50min 1hr 52min 2hr 5min 2hr 3min 2hr 26min 1hr 6min
50min lhr Bmin lhr 1 lmin lhr 15min lhr 25min lhr 33min 59.8 min
l
No. of Patients 82 61 24 6 4 1 178’
No cross clamping was used in 28 patients.
TABLE 111 Multiple Sequential Coronary Bypass Results
All in-hospital mortalities occurred in patients undergoing quadruple bypasses. (Table III.) There were no deaths in the 101 patients receiving five to nine grafts and there were four deaths in the 206 patients receiving four to nine bypasses. Three of the four deaths were high risk patients (1 in an emergency state with acute infarction and cardiac arrest, 1 in preinfarctional state, and 1 with poor
Number of Patients
Mortality.
Volume 134, July 1977
Quadruple Qtiintuple Sextuple Septuple Octuple Nontuple Total
1975
1976
Total
33 6 3 1
72 58 23 5 4 1 163
105 64 26 6 4 1 206
43
Hospital Mortality (overall/elective) 412
4(1.9%)/2(0.9%)
67
Moreno-Cabral, Mamiya, and Dang
ventricular function who had had left ventricular aneurysm plication) and died of low output failure and shock. The fourth was a good risk patient who died of a stroke when air escaped into the left atria1 monitoring line. The overall mortality rate was 1.9 per cent (4 of 206 patients), and if the emergency cases are excluded, it is 0.9 per cent (2 of 204). The deaths occurred in the early part of the series, and the last 185 patients with four or more bypasses were performed without mortality. One additional death occurred one and a half months postoperatively in a patient with evidence of severe coronary artery disease, myocarditis, and congestive heart failure, who had had a quadruple bypass graft. Unfortunately, no autopsy was obtained. Complications. Postoperative complications included bleeding or tamponade requiring exploration (19 patients), renal failure (2, 1 required dialysis), upper gastrointestinal bleeding (2), postpericardiotomy syndrome (2), mediastinal infection (l), and hepatitis (1). Counterpulsation was necessary in seven patients (3.3 per cent)-to assist discontinuance of cardiopulmonary bypass in three and for low output failure in the early postoperative period in four. Intraaortic balloon pumping was not used prophylactically in any patient. In the four patients who expired, balloon pump was utilized. In addition, seventeen patients (8 per cent) required vasopressor support in the early postoperative period. Ten patients (5 per cent) had perioperative myocardial infarction as judged by appearance of new Q waves. Eight of these had the same clinical course as patients with no complications. Three patients had late infarction, one six months postoperatively. Repeat coronary angiography was obtained in four patients with postoperative myocardial infarction or recurrent angina. Graft closure was documented in two patients. One had closure of a left anterior descending-diagonal graft, and one who had postoperative pericarditis had complete closure of a quintuple bypass. Both patients have recently undergone reoperation. Clinical evaluation of the remaining patients shows absence of angina in 80 per cent, symptomatic but improved angina in 10 per cent, and no improvement in 10 per cent. Comments
The use of sequential bypass technic has many attractions and advantages in the performance of multiple bypasses: (1) technical simplicity keeps ischemic and operating time down; (2) small arteries can be bypassed without concern for outflow; (3) higher flows are present as compared with individual
68
grafts [2,3]; (4) less space is needed for the aortic anastomosis, which is advantageous in aortic valve replacement or diseased aortas; (5) a shorter lengthof vein is required; (6) this particular technic allows easy anastomoses with unobstructed view and a torsion- and kink-free route for the vein grafts. The obvious disadvantage is that the closure of the single proximal anastomosis may jeopardize several arteries; however, this does not seem to be a frequent occurrence. Recent studies have shown that most occlusions occur at the distal end-to-side anastomoses whereas the proximal segment of the graft remains patent [4,5]. Theoretically, if one includes a vessel without a significant stenosis in the sequence, the graft may serve as intercoronary collateral. It is generally accepted that coronary arteries with more than 70 per cent narrowing have compromised flow and warrant bypass grafts. There is no agreement whether other concomitant arteries with lesser degrees of narrowing should be bypassed. There is also a question whether it is worthwhile bypassing arteries less than 1 mm. The answer to these questions and the fate of multiple sequential bypasses are not known and will require long and careful follow-up data. In our experience, the use of this method has *been associated with satisfying clinical results and no added risk, especially in patients with the most advanced stage of coronary artery disease. We feel encouraged in further application of this technic and generation of data to determine its effectiveness. Summary
The relief of symptoms of myocardial ischemia and its lasting effect may be related to completeness of myocardial revascularization. Multiple bypass grafting to arteries with lesser stenosis and to small arteries can be simplified by use of the sequential technic. This can be done with no added risk, but its ultimate effectiveness will have to be determined at a much later date. References 1. Cheavenchai CH, Effler DB, et al: Triple bypass graft for the treatment of severe triple coronary vessel disease. Ann Thorac Surg 17: 545, 1974. 2. Bartley TD, Bigelow JC, Page US: Acrtocoronary bypass grafting with multiple sequential anastomoses to a single vein. Arch surg 105: 915. 1972. 3. Sewell WH: Improved coronary vein graft patency rates with side-to-side anastomoses. Ann Thorac Surg 17: 538, 1974. 4. Bigelow JC, Bartley TD, et al: Long-term follow-up of sequential aortocoronary venous grafts. Ann Thorac Surg 22: 507, 1976. 5. Grondin CM, Limet R: Sequential anastomosis in coronary artery grafting. Technical aspects and early and late angiographic results. Ann Thorac Surg 23: 1, 1977.
The American Journal of Surgery
Sequential Multiple Coronary Artery Bypasses
Discussion John E. Connolly (Irvine, CA): Grafting with sequential or multiple anastomoses started in the early 197Os, and there were several papers in the literature recommending it. Nevertheless, it was discarded by most cardiac surgeons at that time because not more than two or three anastomoses were being performed by each surgeon, and there was a possibility of the proximal aortic anastomoses occluding and spoiling several grafts. However, over the past two decades a common procedure used to salvage a lower extremity with ischemia has been femoropopliteal and, more recently, femorotibial bypass if the popliteal artery is occluded. Success with bypassing below the knee, however, has been less than ideal. To increase graft flow and to decrease resistance in a femoropopliteal or femorotibial graft and thereby perfuse the ischemic foot more effectively, a number of vascular surgeons, including ourselves, have recently employed multiple sequential anastomoses of a single vein graft to an isolated popliteal segment until below the knee where multiple anastomoses to tibial vessels are made. Flow rates measured at surgery have demonstrated a significant increase in flow through the graft with each additional anastomosis, plus apparently greater clinical response to the surgery. Flow rates through the vein grafts, whether in the lower extremity or in the coronary system, are important in prognosticating long-term graft patency. I would like to ask the authors if they are employing a flowmeter to evaluate the potential increased runoff with their sequential technic. Recent evidence suggests there is a direct correlation between the relief of symptoms of myocardial ischemia and the completeness of myocardial revascularization. If one is going to perform four to nine bypasses in one patient, from a practical aspect the only usable technic is sequential grafting, and we are employing the technic now in selected cases, especially in the left anterior descending artery and the circumflex artery and their branches. It is very important to emphasize, as Doctor Mamiya did, that one must have proper routing and must use very precise technic when employing a sequential graft going to three or four different sites. Regarding the technical performance of such sequential grafting, I agree with the authors’ use of cold aortic root perfusion, but I believe that potassium chloride is not necessary to the technic. In addition, with the use of a needle thermister probe in the heart muscle to monitor the heart temperature during the operation, Doctor Wakabayashi’s nomogram can be used to determine how long aortic cross clamping is safe at a given heart temperature. The saphenous veins should be harvested from the knees to the ankles, as there are hemodynamic advantages to having as little discrepancy as possible in size between the graft and the coronary arteries. I favor the use of a punch biopsy to make a small circular hole in the aorta for the proximal anastomosis, since the
Volume 134, July 1977
multiple distal anastomosis mentioned by the authors may depend on patency at the proximal end. By taking a piece of aorta out a better anastomosis is obtained and will likely stay open longer. The authors obtained excellent operative results and very low mortality in a very large series of sequential grafts. The ultimate fate of sequential grafting, whether it is in the lower extremity or in the coronary arteries, will have to await the test of time; but the early results, such as those presented, show promise in providing the most complete method for revascularization of the heart. George G. Lindesmith (Los Angeles, CA): We began using the sequential grafting technic in some selected cases in 1972, about the time Doctor Tom Bartley first reported it at the Society of Vascular Surgery at Monterey. Our enthusiasm for this technic has increased over the years. In 1974 approximately I4 per cent of our patients underwent sequential grafting. In 1975 that figure increased to 38 per cent, and in 1976 more than 60 per cent of our patients had undergone one or more sequential grafts in their operative procedure. (Slide) This shows the versatility of this operation, where one can do multiple grafts with relatively small segments of vein, and one also is encouraged to graft smaller targets than normally selected with individual grafts. Our technic is somewhat different, in that we use interrupted sutures in all of our anastomoses, and at the present time we often perform the terminal anastomosis on a sequential graft as a side-to-side anastomosis with the vein ligated. The bulk of our vein incisions are also transverse, which allows one to use a more normal curve of the vein around the surface of the heart. (Slide) This shows a postoperative angiogram, with a single vein graft supplying three anastomoses to the left anterior descending, the obtuse marginal, and the posterior descending branches of the right coronary artery. We have restudied approximately seventy-five of these patients with sequential grafts. The patency rate in this group, considering each anastomosis as a separate graft, runs 82 per cent. This concurs with a 79 to 80 per cent patency rate in single grafts (no statistical difference). However, with patency in sequential grafts, it is important to consider that many grafts are placed on much smaller targets than usually selected for a single graft. In general, this technic is extremely important. It is our technic of choice at the present time, and I believe the completeness of revascularization of the myocardium is insured by using this technic. Richard T. Mamiya (closing): We do not measure flow rates, Doctor Connolly, because we lack confidence in the accuracy of our measurements, although I think flow rates have some usefulness. In addition, your idea of measuring myocardial temperature is a good one. We are indebted to Doctor Lindesmith and Doctor Bartley for introducing and popularizing this technic, and we now use it in about 78 per cent of our coronary bypass cases.
69
Hawaii
Recent evidence suggests a direct correlation between the relief of symptoms of myocardial ischemia and the completeness of myocardial revascularization [I]. The present report concerns our initial attempt at achieving this goal by utilizing the sequential technic of multiple grafting. Clinical Material
During a two year period (January I,1975 to December 31, 1976) 410 patients underwent coronary bypass grafting. The present report is limited to the technic used and early results obtained in 206 of these patients who underwent four to nine coronary bypasses with or without associated procedures. Ages ranged from thirty-three to- seventy-six years (mean, 55 years); 183 patients (89 per cent) were male and 23 (11 per cent) were female. All patients had severe coronary arteriosclerosis and ninety-three (45 per cent) had had previous clinical myocardial infarctions, six of whom had been resuscitated from cardiac arrest. One patient had four previous infarctions, five patients had three, and seventeen patients had two. Selective coronary arteriography showed complete occlusion of one to three major vessels in 138 patients (68 per cent) (right coronary artery, 80 patients [39 per cent]; left anterior descending coronary artery, 59 patients [29 per cent]; and circumflex artery, 53 patients [26 per cent]). Left ventricular function was considered good in 124 patients (60 per cent), fair in 58 (28 per cent), and poor in 24 (12 per cent). The distribution and number of grafts per patient are shown in Table I. Ten patients underwent associated procedures in addition to coronary bypass: 6 left ventricle aneurysm plication (5 quadruple bypasses, 1 quintuple); 1 left ventricular aneurysm resection (quadruple bypass); 1 mitral valve replacement (quadruple bypass); 1 double valve replacement (quintuple bypass); and 1 coronary fistula ligation (quadruple bypass). Indications for surgery were progressive angina in 182 patients (88 per cent), preinfarction angina in 18 (9 per cent), and acute myocardial infarction in 1 (0.5 per cent). Five patients (2.5 per cent) were asymptomatic, and operation was undertaken because of abnormal Treadmill test results and angiographic evidence of three-vessel disease. From the Department of Surgery, University of Hawaii, John Burns School of Medicine, Honolulu, Hawaii. Reprint requests should be addressed to Richard T. Mamiya, MD, 1301 Punchbowl Street, Honolulu, Hawaii 96813. Presented at the Forty-EighthAnnual Meeting of the Pacific Coast Surgical Association. Palm Springs, California, February 20-23, 1977.
64
Surgical Technic
The long saphenous vein is harvested in its entirety by long incisions with a single skin bridge at the knee. This allows atraumatic and rapid removal of the veins. Should the long saphenous system not be available, the cephalic system is used. Cardiopulmonary bypassing is performed in all patients with aortic cannulation for arterial perfusion, and single right atria1 cannulation is performed for venous return. The left side of the heart is not vented. Moderate systemic hypothermia (30°C), cardiacischemiawithlocalcoolingisused. Pericardial bathing with cold saline was used early in this series, but we now use aortic root infusion of 500 cc Ringer’s lactate plus 10 mEq potassium chloride at 4°C. During systemic cooling, the coronary arteries to be used for anastomosis are marked by incising the epicardium. Technics, of Anastomoses. All anastomoses, whether end-to-side or side-to-side, are performed by a single continuous suture of 6-O Proleneo, including the epicardium in the suture. Venotomies are made longitudinally because transverse incisions often produce varying degrees of kinking. Suturing is started at the heel of the anastomosis, and the first three stitches are placed with the vein and artery apart for maximal visualization. (Figure 1.) The rest of the suturing is made with the vein and arteries together. This technic allows good visualization of every stitch, especially the crucial ones at both ends of the anastomosis. The size of the arteriotomy varies TABLE I
Distribution and Number of Grafts in 206 Patients
Arterial System LAD system Diagonals Circumflex system Distal Marginals Right system Proximal Posterior descending distal Total
Total
Average No. of Grafts per Patient
206 246
452
2.2
196 97
293
144 93
237
982
962
No. of Grafts
1.4
1.2 and
4.6
The American Journal of Surgery
Sequential Multiple Coronary Artery Bypasses
Figure 1. The-bypassing sequence is usually started with an en&to-side anaMmo& to a circumfiex marginal branch.
with the size of the artery but generally is approximately 4 to 6 mm. Normal vessels are preferred for the arteriotomy, but frequently when a significant distal plaque is present, a long arteriotomy is made through this area to assure perfusion of the maximal length of artery. All distal coronary anastomoses are performed under continuous aortic occlusion. Routing of Bypass. An important consideration in the sequential technic is the proper routing of the bypass. The course of the bypass is chosen so as to minimize kinking, and no special attempt is made to keep the largest runoff at the end of the bypass. The end-to-side anastomosis is performed first, and the second venotomy site for a side-to-side anastomosis is chosen after the vein is distended with saline and its course arranged properly. (Figures 2 and 3.) All subsequent sites are chosen in the same manner to assure a proper length between anastomoses. Tacking sutures of 6-O Prolene are used to hold the course of the bypass when necessary.
Figure 2. Lefl, proper alignment is obtained by distending the vein with saline and choosing the venotomy site. Right, venotomy is made with vein distended.
Left Coronary Bypass System. The usual sequence in bypassing the left coronary artery system is an end-to-side anastomosis to a marginal branch of the circumflex artery, a side-to-side anastomosis to the diagonal branch, and another side-to-side anastomosis to the left anterior descending artery. Any other branches in the route described are also bypassed if necessary by side-to-side anastomosis. At the completion of the last anastomosis, the vein is transected after estimating the necessary length to follow a gentle curve towards the aorta. As many as six bypasses have been attached to this single limb. If the distal end or a second marginal branch of the circumflex artery is to be bypassed, this is included in the bypass to the right coronary artery system. Right Coronary Artery System. Usually, a fair degree of disease is encountered in the right coronary artery at the bifurcation, so most of the grafting is now done to the posterior descending and the distal right coronary arteries after the bifurcation. The
Moreno-Cabral,
Mamiya, and Dang
Figure 3. A to E, technic of side-to-side anastomosis. F to H, wturina is completed with clear viwallza~ion of eiety stitch.
Figure 4. The sequence in the posterior aspect of ths heart depends on the locatkn and number of lesions and the length of vein available. 66
posterior descending and distal right coronary arteries are bypassed in sequence to provide the best route without kinking. If the distal circumflex artery is to be bypassed, the bypass is started at this vessel with an end-to-side anastomosis and the right and posterior descending arteries are sequentially placed side-to-side. (Figure 4.) Ao’rtic Anastomosis. The aortic cross clamp is released upon completion of the last coronary anastomosis, a partial occluding clamp applied, and longitudinal aortotomies performed. The vein is occluded proximal to the last anastomosis, filled with saline, and obliquely transected after estimating the necessary length to the aortic incision. The heel three corner stitches are placed under unobstructed view. (Figure 5.) At this time electrical defibrillation is accomplished if no spontaneous beat has occurred. Figure 6 shows the most common sequence used in this series. Duration of Aortic Cross-Clamping and Bypass Procedures. In early 1975, operations were performed on twenty-eight patients without cross-clamping the The American Journal of Surgery
Sequential Multiple Coronary Artery Bypasses
Figure 5. A, partial occluding clamp is applied and aortic
root pettWon catheter removed. B, the in&ion is enlarged with Potts scissors. C, two incisions can be made simultaneously on alternate skies with a scalpel. D, anastomosis performed with continuous 6-O Prolene.
aorta. In the subsequent 178 patients we used the single continuous cross-clamping technic. Aortic cross-clamping time ranged from 25 to 93 minutes (mean, 59 minutes) and was longest in a patient with diffuse arteriosclerosis and multiple occlusions of all major vessels who received nine coronary artery bypasses. The cross-clamping time correlated directly with the number of bypasses. (Table II.) The mean duration of the cardiopulmonary bypass procedure was 1 hour 46 minutes. The longest times were associated with multiple coronary bypass and valve replacement.
Figure 6. Most common sequential bypasses used In this series. TABLE II
Duration of Bypass and Cross Clamping
No. of Grafts
Average Pump Time
Average CrossClamping Time
4 5 6 7 8 9 Total 4.8
1hr 40min 1hr 50min 1hr 52min 2hr 5min 2hr 3min 2hr 26min 1hr 6min
50min lhr Bmin lhr 1 lmin lhr 15min lhr 25min lhr 33min 59.8 min
l
No. of Patients 82 61 24 6 4 1 178’
No cross clamping was used in 28 patients.
TABLE 111 Multiple Sequential Coronary Bypass Results
All in-hospital mortalities occurred in patients undergoing quadruple bypasses. (Table III.) There were no deaths in the 101 patients receiving five to nine grafts and there were four deaths in the 206 patients receiving four to nine bypasses. Three of the four deaths were high risk patients (1 in an emergency state with acute infarction and cardiac arrest, 1 in preinfarctional state, and 1 with poor
Number of Patients
Mortality.
Volume 134, July 1977
Quadruple Qtiintuple Sextuple Septuple Octuple Nontuple Total
1975
1976
Total
33 6 3 1
72 58 23 5 4 1 163
105 64 26 6 4 1 206
43
Hospital Mortality (overall/elective) 412
4(1.9%)/2(0.9%)
67
Moreno-Cabral, Mamiya, and Dang
ventricular function who had had left ventricular aneurysm plication) and died of low output failure and shock. The fourth was a good risk patient who died of a stroke when air escaped into the left atria1 monitoring line. The overall mortality rate was 1.9 per cent (4 of 206 patients), and if the emergency cases are excluded, it is 0.9 per cent (2 of 204). The deaths occurred in the early part of the series, and the last 185 patients with four or more bypasses were performed without mortality. One additional death occurred one and a half months postoperatively in a patient with evidence of severe coronary artery disease, myocarditis, and congestive heart failure, who had had a quadruple bypass graft. Unfortunately, no autopsy was obtained. Complications. Postoperative complications included bleeding or tamponade requiring exploration (19 patients), renal failure (2, 1 required dialysis), upper gastrointestinal bleeding (2), postpericardiotomy syndrome (2), mediastinal infection (l), and hepatitis (1). Counterpulsation was necessary in seven patients (3.3 per cent)-to assist discontinuance of cardiopulmonary bypass in three and for low output failure in the early postoperative period in four. Intraaortic balloon pumping was not used prophylactically in any patient. In the four patients who expired, balloon pump was utilized. In addition, seventeen patients (8 per cent) required vasopressor support in the early postoperative period. Ten patients (5 per cent) had perioperative myocardial infarction as judged by appearance of new Q waves. Eight of these had the same clinical course as patients with no complications. Three patients had late infarction, one six months postoperatively. Repeat coronary angiography was obtained in four patients with postoperative myocardial infarction or recurrent angina. Graft closure was documented in two patients. One had closure of a left anterior descending-diagonal graft, and one who had postoperative pericarditis had complete closure of a quintuple bypass. Both patients have recently undergone reoperation. Clinical evaluation of the remaining patients shows absence of angina in 80 per cent, symptomatic but improved angina in 10 per cent, and no improvement in 10 per cent. Comments
The use of sequential bypass technic has many attractions and advantages in the performance of multiple bypasses: (1) technical simplicity keeps ischemic and operating time down; (2) small arteries can be bypassed without concern for outflow; (3) higher flows are present as compared with individual
68
grafts [2,3]; (4) less space is needed for the aortic anastomosis, which is advantageous in aortic valve replacement or diseased aortas; (5) a shorter lengthof vein is required; (6) this particular technic allows easy anastomoses with unobstructed view and a torsion- and kink-free route for the vein grafts. The obvious disadvantage is that the closure of the single proximal anastomosis may jeopardize several arteries; however, this does not seem to be a frequent occurrence. Recent studies have shown that most occlusions occur at the distal end-to-side anastomoses whereas the proximal segment of the graft remains patent [4,5]. Theoretically, if one includes a vessel without a significant stenosis in the sequence, the graft may serve as intercoronary collateral. It is generally accepted that coronary arteries with more than 70 per cent narrowing have compromised flow and warrant bypass grafts. There is no agreement whether other concomitant arteries with lesser degrees of narrowing should be bypassed. There is also a question whether it is worthwhile bypassing arteries less than 1 mm. The answer to these questions and the fate of multiple sequential bypasses are not known and will require long and careful follow-up data. In our experience, the use of this method has *been associated with satisfying clinical results and no added risk, especially in patients with the most advanced stage of coronary artery disease. We feel encouraged in further application of this technic and generation of data to determine its effectiveness. Summary
The relief of symptoms of myocardial ischemia and its lasting effect may be related to completeness of myocardial revascularization. Multiple bypass grafting to arteries with lesser stenosis and to small arteries can be simplified by use of the sequential technic. This can be done with no added risk, but its ultimate effectiveness will have to be determined at a much later date. References 1. Cheavenchai CH, Effler DB, et al: Triple bypass graft for the treatment of severe triple coronary vessel disease. Ann Thorac Surg 17: 545, 1974. 2. Bartley TD, Bigelow JC, Page US: Acrtocoronary bypass grafting with multiple sequential anastomoses to a single vein. Arch surg 105: 915. 1972. 3. Sewell WH: Improved coronary vein graft patency rates with side-to-side anastomoses. Ann Thorac Surg 17: 538, 1974. 4. Bigelow JC, Bartley TD, et al: Long-term follow-up of sequential aortocoronary venous grafts. Ann Thorac Surg 22: 507, 1976. 5. Grondin CM, Limet R: Sequential anastomosis in coronary artery grafting. Technical aspects and early and late angiographic results. Ann Thorac Surg 23: 1, 1977.
The American Journal of Surgery
Sequential Multiple Coronary Artery Bypasses
Discussion John E. Connolly (Irvine, CA): Grafting with sequential or multiple anastomoses started in the early 197Os, and there were several papers in the literature recommending it. Nevertheless, it was discarded by most cardiac surgeons at that time because not more than two or three anastomoses were being performed by each surgeon, and there was a possibility of the proximal aortic anastomoses occluding and spoiling several grafts. However, over the past two decades a common procedure used to salvage a lower extremity with ischemia has been femoropopliteal and, more recently, femorotibial bypass if the popliteal artery is occluded. Success with bypassing below the knee, however, has been less than ideal. To increase graft flow and to decrease resistance in a femoropopliteal or femorotibial graft and thereby perfuse the ischemic foot more effectively, a number of vascular surgeons, including ourselves, have recently employed multiple sequential anastomoses of a single vein graft to an isolated popliteal segment until below the knee where multiple anastomoses to tibial vessels are made. Flow rates measured at surgery have demonstrated a significant increase in flow through the graft with each additional anastomosis, plus apparently greater clinical response to the surgery. Flow rates through the vein grafts, whether in the lower extremity or in the coronary system, are important in prognosticating long-term graft patency. I would like to ask the authors if they are employing a flowmeter to evaluate the potential increased runoff with their sequential technic. Recent evidence suggests there is a direct correlation between the relief of symptoms of myocardial ischemia and the completeness of myocardial revascularization. If one is going to perform four to nine bypasses in one patient, from a practical aspect the only usable technic is sequential grafting, and we are employing the technic now in selected cases, especially in the left anterior descending artery and the circumflex artery and their branches. It is very important to emphasize, as Doctor Mamiya did, that one must have proper routing and must use very precise technic when employing a sequential graft going to three or four different sites. Regarding the technical performance of such sequential grafting, I agree with the authors’ use of cold aortic root perfusion, but I believe that potassium chloride is not necessary to the technic. In addition, with the use of a needle thermister probe in the heart muscle to monitor the heart temperature during the operation, Doctor Wakabayashi’s nomogram can be used to determine how long aortic cross clamping is safe at a given heart temperature. The saphenous veins should be harvested from the knees to the ankles, as there are hemodynamic advantages to having as little discrepancy as possible in size between the graft and the coronary arteries. I favor the use of a punch biopsy to make a small circular hole in the aorta for the proximal anastomosis, since the
Volume 134, July 1977
multiple distal anastomosis mentioned by the authors may depend on patency at the proximal end. By taking a piece of aorta out a better anastomosis is obtained and will likely stay open longer. The authors obtained excellent operative results and very low mortality in a very large series of sequential grafts. The ultimate fate of sequential grafting, whether it is in the lower extremity or in the coronary arteries, will have to await the test of time; but the early results, such as those presented, show promise in providing the most complete method for revascularization of the heart. George G. Lindesmith (Los Angeles, CA): We began using the sequential grafting technic in some selected cases in 1972, about the time Doctor Tom Bartley first reported it at the Society of Vascular Surgery at Monterey. Our enthusiasm for this technic has increased over the years. In 1974 approximately I4 per cent of our patients underwent sequential grafting. In 1975 that figure increased to 38 per cent, and in 1976 more than 60 per cent of our patients had undergone one or more sequential grafts in their operative procedure. (Slide) This shows the versatility of this operation, where one can do multiple grafts with relatively small segments of vein, and one also is encouraged to graft smaller targets than normally selected with individual grafts. Our technic is somewhat different, in that we use interrupted sutures in all of our anastomoses, and at the present time we often perform the terminal anastomosis on a sequential graft as a side-to-side anastomosis with the vein ligated. The bulk of our vein incisions are also transverse, which allows one to use a more normal curve of the vein around the surface of the heart. (Slide) This shows a postoperative angiogram, with a single vein graft supplying three anastomoses to the left anterior descending, the obtuse marginal, and the posterior descending branches of the right coronary artery. We have restudied approximately seventy-five of these patients with sequential grafts. The patency rate in this group, considering each anastomosis as a separate graft, runs 82 per cent. This concurs with a 79 to 80 per cent patency rate in single grafts (no statistical difference). However, with patency in sequential grafts, it is important to consider that many grafts are placed on much smaller targets than usually selected for a single graft. In general, this technic is extremely important. It is our technic of choice at the present time, and I believe the completeness of revascularization of the myocardium is insured by using this technic. Richard T. Mamiya (closing): We do not measure flow rates, Doctor Connolly, because we lack confidence in the accuracy of our measurements, although I think flow rates have some usefulness. In addition, your idea of measuring myocardial temperature is a good one. We are indebted to Doctor Lindesmith and Doctor Bartley for introducing and popularizing this technic, and we now use it in about 78 per cent of our coronary bypass cases.
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