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The left internal mammary artery as a sequential graft to the left anterior descending system
J THORAC CARDIOVASC SURG 86:703-705, 1983
The left internal mammary artery as a sequential graft to the left anterior descending system The left internal mammary artery (IMA) has been used as a sequential graft to the left anterior descending (LAD) system in 39 patients. Seven patients having operation in 1977 werefollowed up for 2 years, and cardiac catheterization in four revealed no problems related to the anastomoses. After a 2 year hiatus we resumed use of the procedure in 1980. A total of 10 patients have had catheterization from 1 month to 5 years postoperatively with no anastomotic narrowing or restriction of distalIMA flow by the side-to-side anastomosis. The IMA should be equal to or greater in size than the larger of the two vessels to be grafted. We continue to use this procedure in carefully selected patients.
Lawrence R. McBride, M.D., and Hendrick B. Barner, M.D., St. Louis. Mo.
Accumulating data on late patency of the internal mammary artery (IMA) indicates that progressive conduit atherosclerosis has not been recognized as a cause of graft occlusion up to 10 years postoperatively':' and that grafts patent 1 year postoperatively have virtually no loss of patency during this interval. I Although early patency of the IMA has varied from 89% to 99%,1.3·9 this rate is equal to or better than that obtained with saphenous vein. In view of this superior late patency of the IMA, it is only logical to try to extend its usefulness. Increasing experience with sequential coronary anastomosis using saphenous vein has led to the application of this technique to the IMA. We here report our 5 year experience with the IMA as a sequential graft to the left anterior descending coronary (LAD) artery and its branches. Patients From August of 1977 through May of 1983, 39 patients having elective coronary bypass grafting had use of the left IMA as a sequential graft to diagonal branches of the LAD artery as well as the LAD. One patient had a triple sequential graft extending from the From the Department of Surgery, St. Louis University School of Medicine, St. Louis, Mo. Received for publication June 30, 1983. Accepted for publication July 27, 1983. Address for reprints: Dr. Hendrick B. Barner, Department of Surgery, 1325 South Grand Blvd., St. Louis, Mo. 63104.
intermediate artery to the first diagonal artery and to the LAD. Another patient had an IMA anastomosed to the intermediate artery and the diagonal artery without bypass of the LAD. There were five (13%) women. Age range was 32 to 65 years with a mean of 51 years. Angina was graded by the Canadian classification with two in Class 0, two in Class 1, five in Class 2, 17 in Class 3, and 13 in Class 4. There were 78 associated saphenous vein grafts (SVG) for a total of 4.0 distal anastomoses per patient. No patients died within 30 days of operation. Perioperative myocardial infarction occurred in one patient by both electrocardiographic and enzymatic criteria. There has been one late death from legionnaires diease 19 months postoperatively. Follow-up catheterization has been obtained in 10 (26%) patients for the following indications: three at 1 month as part of a protocol for the study of antiplatelet drugs and graft patency; one at 4 months following one episode of chest pain (all grafts patent); one at 12 months because of one episode of chest pain (one of two SVGs occluded); two at 18 months, one of which was elective and one for recurrence of angina (one of three SVGs occluded); one at 28 months for recurrent angina due to new disease with a patent IMA; and one at 5 years as required by enrollment in the randomized component of the coronary artery surgical study (CASS). All 20 IMA anastomoses were patent and there was no apparent stenosis related to the side-to-side 703
The Journal of Thoracic and Cardiovascular Surgery
7 0 4 McBride and Barner
Table I. Distribution of IMA grafts by year Year
1977 1978 1979 1980 1981 1982 1983
Sequential IMA grafts 7
o o 6
13 6
...1.
39
Total IMA grafts
Total revascularizations
103
127 116
81 40
131
57 70 66
146
-.l§.
.i:
453
181 165
941
anastomosis. Two of 14 associated SVGs were occluded. Follow-up has ranged from I to 69 months (mean 26). Seven patients were operated upon in 1977, more than 5 years ago. One has died, one has recurrence of angina, and fiveare angina free. There have been no late myocardial infarctions. Comment
Table I depicts the distribution of cases by year. Seven sequential IMA grafts were done in 1977, and then none were done for 2 years. There were two areas of concern: (I) technical adequacy of the side-to-side anastomosis and whether this might restrict flow into the distal IMA if not properly performed and (2) total flow capacity of the IMA. By 1980, four of the seven patients had catheterization demonstrating patency of the IMA distal to the side-to-side anastomosis without apparent stenosisof the IMA caused by this anastomosis or flow restriction into the distal anastomosis. Although one patient had recurrence of chest pain, this was not typical for angina pectoris,and it was elected to proceed with use of the sequential IMA graft. The principle of sequential grafting for coronary reconstruction has been well accepted and widely utilized. Its principal advantages as applied to the saphenous vein relate to its ability to provide flow to a small coronary artery which would not have adequate flow capacity to support its own graft without a high likelihood of graft closure. Additionally the use of a sequential graft will expedite the operation by reducing the number of proximal anastomoses and make optimal use of the saphenous vein if an adequate length of high quality vein is not available. In general, we have restricted use of the sequential saphenous vein to one arterial system for each graft with a maximum of three, and usually two, anastomoses per graft. The primary reason for use of the IMA as a sequential graft is different and is based on its freedom from intimal proliferation and atherosclerosis and therefore better long-term patency. Because of its demon-
strated patency in lowflowsituations, there is no need to increase runoff by providing a second anastomosis. A primary consideration for use of the IMA as a sequential graft centers about its size (internal diameter) in relation to the size of the two coronary arteries which are to be bypassed. The internal diameter should be equal to or greater than that of the distal vessel at the distal anastomosis (the IMA was equal to the distal vessel in 15 instances,greater in 23, and one distal vessel was not sized). In the occasional instance in which the diagonal artery is larger than the LAD, the IMA should be equal to or greater than the diagonal in internal diameter. Although only a'modest number of our patients have had follow-up catheterization, this would not seem to be an important consideration from the standpoint of the durability of the IMA as' a conduit. However, we continue to be concerned that the side-to-side anastomosis has the potential to stenose the IMA and restrict distal flow. This occurrence would more than negate any potential gain and, in effect, vitiate the wholeconceptof the IMA as a sequential graft. Extending use of the IMA to a secondary artery only to compromiseflow into the primary artery makes no sense. Thus, continued assessment of the sequential IMA is necessary. We are also concerned about the flow capacity of the IMA, although we have many IMA grafts to the LAD which appear to adequately supply the diagonal artery in a retrograde fashion. The ability of the IMA to increase in caliber, presumably in response to demand, has been observed by us as well as othersY~12 Technical considerations involve placing the IMA intrapleurally, parallel to the phrenic nerve,and incising the pericardium to the left at the base of the heart so that the IMA has a nearly straight course from its origin to the anastomosis. Forceps must handle the adventitia only and not the arterial wall. Axial torsion must be avoided. The position of the two anastomoses must be such that angulation, kinking,or tension of the IMA are avoided. Longitudinal incisions of equal length (3 to 5 rom) are used for the side-to-side anastomosis with running 7-0 monofilament suture. It must be emphasized that this small series of patients was carefully selectedand has been expandedas we gained confidence with the sequential IMA graft. We initially used the IMA for a singleanastomosis in all patients. We then restricted its use to patients under the age of 60 years with 70% or greater stenosis of the LAD and having electiveisolated coronary grafting. Basedon results of catheterization follow-up, we have recently elevated the age ceiling to 65 years. We would now use the sequential IMA in the same circumstances with the considerations discussed above.
Volume 86 Number 5 November. 1983
REFERENCES I Barner HB, Swartz MT, Mudd JG, Tyras DH: Late patency of the internal mammary artery as a coronary bypass conduit. Ann Thorac Surg 34:408-412, 1982 2 Singh RN, Sosa JA, Green GE: Internal mammary artery versus saphenous vein graft. Comparative performance in patients with combined revascularization. J THORAC CARD10VASC SURG 86:359-363, 1983 3 Tector AJ, Schmahl TM, Janson B, Kallies JR, Johnson G: The internal mammary artery graft. Its longevity after coronary bypass. JAMA 246:2181-2183, 1981 4 Geha A, Baue AE: Early and late results of coronary revascularization with saphenous vein and internal mammary artery grafts. Am J Surg 137:456-463, 1979 5 Green GE: Internal mammary artery-to--coronary artery anastomosis. Three-year experience with 165 patients. Ann Thorac Surg 14:260-271, 1972 6 Jahnke EJ, Love JW: Bypass of the right and circumflex coronary arteries with the internal mammary artery. J THORAC CARDIOVASC SURG 71:58-63, 1976 7 Jones JW, Ochsner JL, Mills NL Hughes L: The internal
SequentialIMA-LAD bypass 705
mammary bypass graft. A superior second coronary artery. J THORAC CARDIOVASC SURG 75:625-630, 1978 8 Kay EB, Naraghipour H, Beg RA, DeManey M, Tambe A, Zimmerman HA: Internal mammary artery bypass graft. Long-term patency rate and follow-up. Ann Thorac Surg 18:269-279, 1974 9 Tector AJ, Davis L, Gabriel R, Gale H, Singh H, Flemma R: Experiencewith internal mammary artery grafts in 298 patients. Ann Thorac Surg 22:515-519, 1976 10 Grondin CM, Lesperance J, Bourassa MG, Campeau L: Coronary artery grafting with the saphenous vein or internal mammary artery. Ann Thorac Surg 20:605-618, 1975 11 Loop FD, Irarrazaval MJ, Bredee JJ, Siegel W, Taylor PC, Sheldon WC: Internal mammary artery grafts for ischemic heart disease. Am J Cardiol 39:516-522, 1977 12 Vogel JHK, McFadden B, Spence R, Jahnke EJ Jr, Love JW: Quantitative assessment of myocardial performance and graft patency following coronary bypass with the internal mammary artery. J THORAC CARDIOVASC SURG 75:487-498, 1978
The left internal mammary artery as a sequential graft to the left anterior descending system The left internal mammary artery (IMA) has been used as a sequential graft to the left anterior descending (LAD) system in 39 patients. Seven patients having operation in 1977 werefollowed up for 2 years, and cardiac catheterization in four revealed no problems related to the anastomoses. After a 2 year hiatus we resumed use of the procedure in 1980. A total of 10 patients have had catheterization from 1 month to 5 years postoperatively with no anastomotic narrowing or restriction of distalIMA flow by the side-to-side anastomosis. The IMA should be equal to or greater in size than the larger of the two vessels to be grafted. We continue to use this procedure in carefully selected patients.
Lawrence R. McBride, M.D., and Hendrick B. Barner, M.D., St. Louis. Mo.
Accumulating data on late patency of the internal mammary artery (IMA) indicates that progressive conduit atherosclerosis has not been recognized as a cause of graft occlusion up to 10 years postoperatively':' and that grafts patent 1 year postoperatively have virtually no loss of patency during this interval. I Although early patency of the IMA has varied from 89% to 99%,1.3·9 this rate is equal to or better than that obtained with saphenous vein. In view of this superior late patency of the IMA, it is only logical to try to extend its usefulness. Increasing experience with sequential coronary anastomosis using saphenous vein has led to the application of this technique to the IMA. We here report our 5 year experience with the IMA as a sequential graft to the left anterior descending coronary (LAD) artery and its branches. Patients From August of 1977 through May of 1983, 39 patients having elective coronary bypass grafting had use of the left IMA as a sequential graft to diagonal branches of the LAD artery as well as the LAD. One patient had a triple sequential graft extending from the From the Department of Surgery, St. Louis University School of Medicine, St. Louis, Mo. Received for publication June 30, 1983. Accepted for publication July 27, 1983. Address for reprints: Dr. Hendrick B. Barner, Department of Surgery, 1325 South Grand Blvd., St. Louis, Mo. 63104.
intermediate artery to the first diagonal artery and to the LAD. Another patient had an IMA anastomosed to the intermediate artery and the diagonal artery without bypass of the LAD. There were five (13%) women. Age range was 32 to 65 years with a mean of 51 years. Angina was graded by the Canadian classification with two in Class 0, two in Class 1, five in Class 2, 17 in Class 3, and 13 in Class 4. There were 78 associated saphenous vein grafts (SVG) for a total of 4.0 distal anastomoses per patient. No patients died within 30 days of operation. Perioperative myocardial infarction occurred in one patient by both electrocardiographic and enzymatic criteria. There has been one late death from legionnaires diease 19 months postoperatively. Follow-up catheterization has been obtained in 10 (26%) patients for the following indications: three at 1 month as part of a protocol for the study of antiplatelet drugs and graft patency; one at 4 months following one episode of chest pain (all grafts patent); one at 12 months because of one episode of chest pain (one of two SVGs occluded); two at 18 months, one of which was elective and one for recurrence of angina (one of three SVGs occluded); one at 28 months for recurrent angina due to new disease with a patent IMA; and one at 5 years as required by enrollment in the randomized component of the coronary artery surgical study (CASS). All 20 IMA anastomoses were patent and there was no apparent stenosis related to the side-to-side 703
The Journal of Thoracic and Cardiovascular Surgery
7 0 4 McBride and Barner
Table I. Distribution of IMA grafts by year Year
1977 1978 1979 1980 1981 1982 1983
Sequential IMA grafts 7
o o 6
13 6
...1.
39
Total IMA grafts
Total revascularizations
103
127 116
81 40
131
57 70 66
146
-.l§.
.i:
453
181 165
941
anastomosis. Two of 14 associated SVGs were occluded. Follow-up has ranged from I to 69 months (mean 26). Seven patients were operated upon in 1977, more than 5 years ago. One has died, one has recurrence of angina, and fiveare angina free. There have been no late myocardial infarctions. Comment
Table I depicts the distribution of cases by year. Seven sequential IMA grafts were done in 1977, and then none were done for 2 years. There were two areas of concern: (I) technical adequacy of the side-to-side anastomosis and whether this might restrict flow into the distal IMA if not properly performed and (2) total flow capacity of the IMA. By 1980, four of the seven patients had catheterization demonstrating patency of the IMA distal to the side-to-side anastomosis without apparent stenosisof the IMA caused by this anastomosis or flow restriction into the distal anastomosis. Although one patient had recurrence of chest pain, this was not typical for angina pectoris,and it was elected to proceed with use of the sequential IMA graft. The principle of sequential grafting for coronary reconstruction has been well accepted and widely utilized. Its principal advantages as applied to the saphenous vein relate to its ability to provide flow to a small coronary artery which would not have adequate flow capacity to support its own graft without a high likelihood of graft closure. Additionally the use of a sequential graft will expedite the operation by reducing the number of proximal anastomoses and make optimal use of the saphenous vein if an adequate length of high quality vein is not available. In general, we have restricted use of the sequential saphenous vein to one arterial system for each graft with a maximum of three, and usually two, anastomoses per graft. The primary reason for use of the IMA as a sequential graft is different and is based on its freedom from intimal proliferation and atherosclerosis and therefore better long-term patency. Because of its demon-
strated patency in lowflowsituations, there is no need to increase runoff by providing a second anastomosis. A primary consideration for use of the IMA as a sequential graft centers about its size (internal diameter) in relation to the size of the two coronary arteries which are to be bypassed. The internal diameter should be equal to or greater than that of the distal vessel at the distal anastomosis (the IMA was equal to the distal vessel in 15 instances,greater in 23, and one distal vessel was not sized). In the occasional instance in which the diagonal artery is larger than the LAD, the IMA should be equal to or greater than the diagonal in internal diameter. Although only a'modest number of our patients have had follow-up catheterization, this would not seem to be an important consideration from the standpoint of the durability of the IMA as' a conduit. However, we continue to be concerned that the side-to-side anastomosis has the potential to stenose the IMA and restrict distal flow. This occurrence would more than negate any potential gain and, in effect, vitiate the wholeconceptof the IMA as a sequential graft. Extending use of the IMA to a secondary artery only to compromiseflow into the primary artery makes no sense. Thus, continued assessment of the sequential IMA is necessary. We are also concerned about the flow capacity of the IMA, although we have many IMA grafts to the LAD which appear to adequately supply the diagonal artery in a retrograde fashion. The ability of the IMA to increase in caliber, presumably in response to demand, has been observed by us as well as othersY~12 Technical considerations involve placing the IMA intrapleurally, parallel to the phrenic nerve,and incising the pericardium to the left at the base of the heart so that the IMA has a nearly straight course from its origin to the anastomosis. Forceps must handle the adventitia only and not the arterial wall. Axial torsion must be avoided. The position of the two anastomoses must be such that angulation, kinking,or tension of the IMA are avoided. Longitudinal incisions of equal length (3 to 5 rom) are used for the side-to-side anastomosis with running 7-0 monofilament suture. It must be emphasized that this small series of patients was carefully selectedand has been expandedas we gained confidence with the sequential IMA graft. We initially used the IMA for a singleanastomosis in all patients. We then restricted its use to patients under the age of 60 years with 70% or greater stenosis of the LAD and having electiveisolated coronary grafting. Basedon results of catheterization follow-up, we have recently elevated the age ceiling to 65 years. We would now use the sequential IMA in the same circumstances with the considerations discussed above.
Volume 86 Number 5 November. 1983
REFERENCES I Barner HB, Swartz MT, Mudd JG, Tyras DH: Late patency of the internal mammary artery as a coronary bypass conduit. Ann Thorac Surg 34:408-412, 1982 2 Singh RN, Sosa JA, Green GE: Internal mammary artery versus saphenous vein graft. Comparative performance in patients with combined revascularization. J THORAC CARD10VASC SURG 86:359-363, 1983 3 Tector AJ, Schmahl TM, Janson B, Kallies JR, Johnson G: The internal mammary artery graft. Its longevity after coronary bypass. JAMA 246:2181-2183, 1981 4 Geha A, Baue AE: Early and late results of coronary revascularization with saphenous vein and internal mammary artery grafts. Am J Surg 137:456-463, 1979 5 Green GE: Internal mammary artery-to--coronary artery anastomosis. Three-year experience with 165 patients. Ann Thorac Surg 14:260-271, 1972 6 Jahnke EJ, Love JW: Bypass of the right and circumflex coronary arteries with the internal mammary artery. J THORAC CARDIOVASC SURG 71:58-63, 1976 7 Jones JW, Ochsner JL, Mills NL Hughes L: The internal
SequentialIMA-LAD bypass 705
mammary bypass graft. A superior second coronary artery. J THORAC CARDIOVASC SURG 75:625-630, 1978 8 Kay EB, Naraghipour H, Beg RA, DeManey M, Tambe A, Zimmerman HA: Internal mammary artery bypass graft. Long-term patency rate and follow-up. Ann Thorac Surg 18:269-279, 1974 9 Tector AJ, Davis L, Gabriel R, Gale H, Singh H, Flemma R: Experiencewith internal mammary artery grafts in 298 patients. Ann Thorac Surg 22:515-519, 1976 10 Grondin CM, Lesperance J, Bourassa MG, Campeau L: Coronary artery grafting with the saphenous vein or internal mammary artery. Ann Thorac Surg 20:605-618, 1975 11 Loop FD, Irarrazaval MJ, Bredee JJ, Siegel W, Taylor PC, Sheldon WC: Internal mammary artery grafts for ischemic heart disease. Am J Cardiol 39:516-522, 1977 12 Vogel JHK, McFadden B, Spence R, Jahnke EJ Jr, Love JW: Quantitative assessment of myocardial performance and graft patency following coronary bypass with the internal mammary artery. J THORAC CARDIOVASC SURG 75:487-498, 1978