- Email: [email protected]
Coronary artery bypass using internal mammary artery branches
Coronary Artery Bypass Using Internal Mammary Artery Branches Jean E. Morin, MD, Giles Hedderich, MD, Normand L. Poirier, MD, John Sampalis, PhD, and James F. Symes, MD Cardiovascular and Thoracic Surgery Service, Department of Surgery, Royal Victoria Hospital, McGill University, Montreal, Quebec, Canada
The excellent long-term patency rates achieved with use of the internal mammary artery (IMA) to bypass the left anterior descending coronary artery have stimulated a variety of approaches to expand the use of this conduit in coronary bypass surgery. In this report we document our results using the two terminal branches of the IMA to bypass two arteries in a Y configuration. Sixty-seven patients received IMA Y grafts during a 6-month period in 1987. A total of 150 IMA branch anastomoses were performed (8 patients received bilateral IMA Y grafts). Fourteen of 67 patients were revascularized using IMA grafts only. Operative mortality was 2 of 67 (3%), and follow-up mortality was 5 of 67 (7.5%). Fifty-eight patients could be evaluated 37 2.7 months later. Clini-
*
F
rom the experience of many centers, the internal mammary artery is considered the optimal conduit for coronary artery bypass grafts [l]. It has provided excellent long-term clinical results. Its patency rate is consistently reported to be greater than 90% after 10 years [2, 31. It increases life span and improves cumulative event-free intervals [4]. The experience from many centers has shown an expected survival rate of 90% and freedom from ischemic manifestations of 77% at 5 years after myocardial revascularization [5]. Like other authors [&lo], we have attempted to expand the use of the internal mammary artery to achieve more extensive and complete revascularization. The mammary artery can be used as a unilateral or bilateral conduit. It can be anastomosed end-to-side or sequentially or as a free graft. It has also been anastomosed in a retrograde fashion. Finally, its distal branches can be anastomosed separately to two different coronary arteries in a Y fashion.
Material and Methods From the Royal Victoria Hospital cardiac surgery registry [ll],we identified 67 patients who underwent mammary Y grafts during the first 6 months of 1987. The objective of Accepted for publication March 5, 1992. Address reprint requests to Dr Morin, Royal Victoria Hospital, Suite S8.30, 687 Pine Ave West, Montreal, Que, H3A 1Al Canada.
0 1992 by The Society of Thoracic Surgeons
cally 36% of patients reported some recurrence of angina and 12 of 47 (25%) had a positive electrocardiographic stress test. Four patients were reoperated on (2 redo coronary artery bypass grafting, 2 transplants). Sixty (40%)of the 150 branch anastomoses could be evaluated objectively and 30 (50%) were patent. Five (8.5%) were stenotic and 25 (41.5%) were occluded (overall patency rate, 58.5%). We conclude that although the use of IMA Y grafts is a technically feasible means to increase IMA usage, extended application of this technique cannot be recommended unless improved patency rates can be demonstrated. (Ann Thorac Surg 1992;54:9114)
this report is to describe the clinical outcome of these patients and the patency rate of the Y branches anastomosed to coronary arteries. All patients were operated on in a similar fashion. The mammary artery was dissected with a cautery to encompass a large, 2-cm-wide pedicle of soft tissue to prevent injury to the vessel or its branches. At the distal end the mammary artery divides into two major branches. One continues within the rectus muscle and the other gives a good-sized intercostal artery. Both branches were dissected for a distance of 2 to 3 cm. Once dissected, they were dilated with an infusion of papaverine chlorhydrate (Merck Frosst Canada Inc, Kirkland, Que, Canada), 65 mg into 200 mL of normal saline solution. Five to 10 mL of this solution was injected into one of the distal branches of the mammary artery through a small 16-gauge clear nylon epidural catheter (Concord/ Portex, Keene, NH) threaded into the distal mammary artery (Fig 1). The papaverine was contained within the mammary artery by blocking its exit with a Ligaclip (Ethicon Ltd, Peterborough, Canada) while cannulation for cardiopulmonary bypass was achieved. All anastomoses were made with continuous 7-0 Prolene (Ethicon Ltd). Myocardial protection was identical in all patients. An average of 1,713 2 438 mL of cold crystalloid cardioplegia was delivered intermittently at 4°C. The average cross-clamp time was 61 2 17 minutes, and the body temperature was lowered to an average of 27.5" & 1.TC. 0003-4975/92/$5.00
912
MORIN ET AL CAB USING IMA BRANCHES
Ann Thorac Surg 199’2;54:9114
angina, and 36% had some degree of recurrent angina as defined by Campeau [12]. Six patients experienced some mild symptoms of congestive heart failure [13], and 2 had severe symptoms. Forty-seven (81%)of the patients available for follow-up underwent an electrocardiographic stress test. Twentyseven test results were negative, 8 inconclusive, and 12 positive. During the 3-year follow-up, 4 patients underwent reoperation, 2 for redo coronary bypass grafts and 2 for transplantation (Table 1).
Evaluation of Anastomoses
Fig 1. Papaverine is used to dilate the mammary artery.
The mammary branches were usually anastomosed to the left anterior descending artery and a diagonal artery, or to two different marginal arteries of the circumflex or the distal right coronary and its marginal branch (Fig 2).
Results Sixty-seven patients were operated on. Two died in the immediate postoperative period for a mortality of 3%. Five other patients died during the next 3 years, 1 of cardiac disease and the other 4 of unrelated causes. Two patients could not be traced. Fifty-eight patients (87%) were evaluated at 37 2.7 months after the operation.
Of the 58 patients, 25 underwent recatheterization, and 1 heart could be inspected directly at time of transplantation. Thus, 45% of the cohort could be restudied by objective criteria. From a total of 150 branches anastomosed, 60 branches (40%)were assessed. Thirty branches (50%) were open with good flow (Fig 3), 5 (8%) had serious obstruction but were still patent, and 25 (42%) were occluded. Of all the branches studied, the anastomosis to the left anterior descending artery had the best patency rate (59%). However, this was not significantly different than the patency rates of other anastomosis sites (2= 6.70; p = 0.88) (Table 2).
Comment The cumulative experience of many centers shows an 83% chance of freedom from angina at 5 years after adequate myocardial revascularization. It is reported that 95% of internal mammary arteries that are anastomosed end-toside to the left anterior descending artery are patent after
*
Operations Performed Fifty-nine patients underwent unilateral mammary Y anastomosis for a total of 118 anastomosed branches, and 8 received a bilateral mammary Y anastomosis for a total of 32 branches. Thus, a grand total of 150 mammary Y graft anastomoses were constructed. A total of 14 patients underwent revascularization using only the mammary arteries, whereas 53 had a combination of mammary and saphenous vein grafts.
Patients’ Profile The average age of the patients was 59 years; 87% of the patients were male. Six percent had a history of cerebrovascular disease, and 18% were diabetic. Thirty-six percent suffered from hypertension, and 49% had a previous myocardial infarction. Sixty-two percent had abnormal left ventricular function as evaluated by abnormal wall contraction on ventriculography. There was an average of 4 grafts constructed per patient.
Follow-up Evaluation Fifty-eight patients were evaluated at an average of 37 -C 2.7 months after operation. Sixty-four percent were free of
Fig 2. Mammary artery Ygrafts to left anterior descending artery and diagonal artery.
MORIN ET AL CAB USING IMA BRANCHES
Ann Thorac Surg 1992;549114
10 years [14]. The use of the internal mammary artery in this fashion contributes to an increased longevity. The 10-year patency rate of the saphenous vein conduit is inferior to that of the internal mammary artery when anastomosed to the left anterior descending artery. The best reported rate at 10 years is approximately 80% [5]. Other large series report patency that ranges between 50% and 70% [15]. It is thus extremely important to try to maximize the patency rate of coronary artery bypass grafts by either extending the use of the mammary artery or finding other conduits that have a similar or even better patency rate. Other authors, as well as ourselves, have tried to use the gastroepiploic artery, but the experience is limited and the long-term results are uncertain. In this cohort of patients we have tried to extend the use of the mammary artery by anastomosing its Y branches. This was successful in increasing our mean graft per patient from 3.4 to 4 grafts per patient. In addition 14 of 67 patients (21%)had complete revascularization with the mammary artery only, without the use of saphenous veins. The operative mortality of 3% is the same as reported for large series of patients. On the other hand, a recurrent rate of angina of 36% at 37 months is higher than reported in cumulative experiences by many centers [5]. On clinical grounds, therefore, it appears that mammary Y grafts are not as satisfactory as direct mammary anastomosis to the left anterior descending artery combined with use of the saphenous vein. Four of 67 patients (6%) underwent reoperation within 3 years, which is higher than the usual reoperation rate of 10% at 10 years. Of the 150 Y branches that were originally constructed, 60 branches were evaluated. Although the patients who
Table 1 . Follow-up Evaluation" Variable Angina 0 1 L
3 4 CHF Mild Severe Stress test Negative Inconclusive Positive Not done Reopera tion Redo CABG Transplantation
No. of Patients
Percent
37 11 4 4 2
64 19 7 7 3
6 2
10 3
27 8 12 11
46 14 21 19
2 2
Fifty-eight patients were followed up 37 -t 2.7 months (mean ? standard deviation) after operation.
a
CABG = coronary artery bypass grafting; failure.
CHF
=
congestive heart
Fig 3. Angiogram O f ginal branches of circumflex artey.
'grafts (arrows)
913
to two mar-
accepted recatheterization were in general more symptomatic than the patients who refused the test, a 42% rate of occlusion in this group is relatively high for the mammary artery conduit. Of the 150 grafts, if we assume that only these 25 studied grafts are blocked and that all the others are open, it would still mean that the occlusion rate is 17%. Thus, our real occlusion rate is situated between 17% and 42%, which is higher than usually reported for this conduit when used as a single pedicle graft. Fourteen patients received Y grafts only, and 10 of 14 (71%)were asymptomatic at the time of reevaluation. Ten branches in 5 patients of this cohort were evaluated by angiography. Four were open, two partially open, and four closed. This is a very small subgroup of patients, and it is not justified to draw a very definitive conclusion. Nevertheless, their clinical status and angiographic results are the same as for the rest of the group. Although we can only speculate as to the reasons for the high occlusion rate, it was our impression that this type of anastomosis is technically more difficult than the standard mammary artery to left anterior descending artery anastomosis. The Y branches are of smaller diameter and could in general only accept the 16-gauge epidural catheter at the time of dilation. The vessel wall
914
Ann Thorac Surg
MORINETAL CAB USING IMA BRANCHES
1992;54:9114
Table 2. Branches Anastomosed Graft Location LAD
First DG
Second DG
No. of Branches 22
16
6
First OM
7
Second OM
7
PVB
1
PDA
1
Patency Condition
No.
Percent
Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed
13
59 9 32 37 12 50 50 17 33 57
2
7 6 2 8 3 1 2 4 0 3 3 0 4 1 0 0 0 0 1
43 43 57
OM LAD = left anterior descending artery; DG = diagonal artery; = obtuse marginal branch; FDA = posterior descending artery; PVB = posterior ventricular branch.
appeared thinner and more friable, and its layers seemed to separate more easily. In addition, the coronary artery anatomy is not always suitable for the Y grafts to fit perfectly. This can lead to slight angulations and increased tension on the limbs of the Y grafts, which may contribute to the higher obstruction rate. All anastomoses were constructed using 2.5X or 3.5X magnifying loupes and continuous 7-0 Prolene suture. It is possible that better results could be obtained with interrupted techniques using finer suture material with an operating microscope. In conclusion, this study demonstrates the technical feasibility of using mammary artery Y grafts for multiple coronary bypass procedures. Its use is limited, however, by the coronary anatomy and the small sizes of the Y branches. The use of the Y branches of the mammary should be considered when conventional mammary or
vein conduits cannot be used in the classic way. We believe that this technique should be part of the cardiac surgeon’s armamentarium, but its use should be limited unless further refinements in surgical technique can be demonstrated to improve patency. We thank Ms Nadine Fosset, RN, for tracing patients for followup, and data gathering.
References 1. Loop FD, Lytle BW, Cosgrove DM. New arteries for old. Circulation 1989;79(Suppl 1):40-5. 2. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal mammary-artery-graft on 10-year survival and other cardiac events. N Engl J Med 1986;31414. 3. Tector AJ, Schmahl TM, Canino VR, Kallies JR, Sanfilippo D. The role of the sequential internal mammary artery graft in coronary surgery. Circulation 1984;7O(Suppl1):222. 4. Cameron A, Kemp HG Jr, Green GE. Bypass surgery with the internal mammary artery graft: 15 year follow-up. Circulation 1986;74(Suppl 3):3M. 5. Kirklin JW, Naftel DC, Blackstone EH, Pohost GM. Summary of a consensus concerning death and ischemic events after coronary artery bypass grafting. Circulation 1989;79(Suppl 1):81-91. 6. Slater AD, Gott JP, Gray LA Jr. Extended use of bilateral internal mammary arteries for coronary artery disease. Ann Thorac Surg 1990;49:1014-5. 7. Kieser TM, FitzGibbon GM, Keon WJ. Sequential coronary bypass grafts. J Thorac Cardiovasc Surg 1986;91:767-72. 8. Landymore RW, Chapman DM. Anatomical studies to support the expanded use of the internal mammary artery graft for myocardial revascularization. Ann Thorac Surg 1987;M: MI.
9. Tector AJ. Fifteen years’ experience with the internal mammary artery graft. Ann Thorac Surg 1986;42(Suppl):S22-7. 10. Singh RN, Sosa JA. Internal mammary artery-coronary anastomosis. Influence of the side branches on surgical result. J Thorac Cardiovasc Surg 1981;82:909-14. 11. Morin JE, Symes JF, Ralphs-Thibodeau S, Tasse S, Morin A, Lefebvre C. A microcomputer system for the practising cardiac surgeon. Can J Surg 1981;29:364-6. 12. Campeau L. Grading of angina pectoris. Circulation 1976;54: 522-3. 13. Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease. Circulation 1975;51:740. 14. Kirklin JW, Akins CW, Blackstone EH, et al. ACC/AHA guidelines and indications for coronary artery bypass graft surgery. Circulation 1991;83:1125-73. 15. Campeau L, Enjalbert M, Lesperance J, Vaislic C, Grondin CM, Bourassa MG. Atherosclerosis and late closure of aortocoronary saphenous vein grafts: sequential angiographic studies at 2 weeks, 1 year, 5 to 7 years, and 10 to 12 years after surgery. Circulation 1983;68(Suppl 2):l-7.
The excellent long-term patency rates achieved with use of the internal mammary artery (IMA) to bypass the left anterior descending coronary artery have stimulated a variety of approaches to expand the use of this conduit in coronary bypass surgery. In this report we document our results using the two terminal branches of the IMA to bypass two arteries in a Y configuration. Sixty-seven patients received IMA Y grafts during a 6-month period in 1987. A total of 150 IMA branch anastomoses were performed (8 patients received bilateral IMA Y grafts). Fourteen of 67 patients were revascularized using IMA grafts only. Operative mortality was 2 of 67 (3%), and follow-up mortality was 5 of 67 (7.5%). Fifty-eight patients could be evaluated 37 2.7 months later. Clini-
*
F
rom the experience of many centers, the internal mammary artery is considered the optimal conduit for coronary artery bypass grafts [l]. It has provided excellent long-term clinical results. Its patency rate is consistently reported to be greater than 90% after 10 years [2, 31. It increases life span and improves cumulative event-free intervals [4]. The experience from many centers has shown an expected survival rate of 90% and freedom from ischemic manifestations of 77% at 5 years after myocardial revascularization [5]. Like other authors [&lo], we have attempted to expand the use of the internal mammary artery to achieve more extensive and complete revascularization. The mammary artery can be used as a unilateral or bilateral conduit. It can be anastomosed end-to-side or sequentially or as a free graft. It has also been anastomosed in a retrograde fashion. Finally, its distal branches can be anastomosed separately to two different coronary arteries in a Y fashion.
Material and Methods From the Royal Victoria Hospital cardiac surgery registry [ll],we identified 67 patients who underwent mammary Y grafts during the first 6 months of 1987. The objective of Accepted for publication March 5, 1992. Address reprint requests to Dr Morin, Royal Victoria Hospital, Suite S8.30, 687 Pine Ave West, Montreal, Que, H3A 1Al Canada.
0 1992 by The Society of Thoracic Surgeons
cally 36% of patients reported some recurrence of angina and 12 of 47 (25%) had a positive electrocardiographic stress test. Four patients were reoperated on (2 redo coronary artery bypass grafting, 2 transplants). Sixty (40%)of the 150 branch anastomoses could be evaluated objectively and 30 (50%) were patent. Five (8.5%) were stenotic and 25 (41.5%) were occluded (overall patency rate, 58.5%). We conclude that although the use of IMA Y grafts is a technically feasible means to increase IMA usage, extended application of this technique cannot be recommended unless improved patency rates can be demonstrated. (Ann Thorac Surg 1992;54:9114)
this report is to describe the clinical outcome of these patients and the patency rate of the Y branches anastomosed to coronary arteries. All patients were operated on in a similar fashion. The mammary artery was dissected with a cautery to encompass a large, 2-cm-wide pedicle of soft tissue to prevent injury to the vessel or its branches. At the distal end the mammary artery divides into two major branches. One continues within the rectus muscle and the other gives a good-sized intercostal artery. Both branches were dissected for a distance of 2 to 3 cm. Once dissected, they were dilated with an infusion of papaverine chlorhydrate (Merck Frosst Canada Inc, Kirkland, Que, Canada), 65 mg into 200 mL of normal saline solution. Five to 10 mL of this solution was injected into one of the distal branches of the mammary artery through a small 16-gauge clear nylon epidural catheter (Concord/ Portex, Keene, NH) threaded into the distal mammary artery (Fig 1). The papaverine was contained within the mammary artery by blocking its exit with a Ligaclip (Ethicon Ltd, Peterborough, Canada) while cannulation for cardiopulmonary bypass was achieved. All anastomoses were made with continuous 7-0 Prolene (Ethicon Ltd). Myocardial protection was identical in all patients. An average of 1,713 2 438 mL of cold crystalloid cardioplegia was delivered intermittently at 4°C. The average cross-clamp time was 61 2 17 minutes, and the body temperature was lowered to an average of 27.5" & 1.TC. 0003-4975/92/$5.00
912
MORIN ET AL CAB USING IMA BRANCHES
Ann Thorac Surg 199’2;54:9114
angina, and 36% had some degree of recurrent angina as defined by Campeau [12]. Six patients experienced some mild symptoms of congestive heart failure [13], and 2 had severe symptoms. Forty-seven (81%)of the patients available for follow-up underwent an electrocardiographic stress test. Twentyseven test results were negative, 8 inconclusive, and 12 positive. During the 3-year follow-up, 4 patients underwent reoperation, 2 for redo coronary bypass grafts and 2 for transplantation (Table 1).
Evaluation of Anastomoses
Fig 1. Papaverine is used to dilate the mammary artery.
The mammary branches were usually anastomosed to the left anterior descending artery and a diagonal artery, or to two different marginal arteries of the circumflex or the distal right coronary and its marginal branch (Fig 2).
Results Sixty-seven patients were operated on. Two died in the immediate postoperative period for a mortality of 3%. Five other patients died during the next 3 years, 1 of cardiac disease and the other 4 of unrelated causes. Two patients could not be traced. Fifty-eight patients (87%) were evaluated at 37 2.7 months after the operation.
Of the 58 patients, 25 underwent recatheterization, and 1 heart could be inspected directly at time of transplantation. Thus, 45% of the cohort could be restudied by objective criteria. From a total of 150 branches anastomosed, 60 branches (40%)were assessed. Thirty branches (50%) were open with good flow (Fig 3), 5 (8%) had serious obstruction but were still patent, and 25 (42%) were occluded. Of all the branches studied, the anastomosis to the left anterior descending artery had the best patency rate (59%). However, this was not significantly different than the patency rates of other anastomosis sites (2= 6.70; p = 0.88) (Table 2).
Comment The cumulative experience of many centers shows an 83% chance of freedom from angina at 5 years after adequate myocardial revascularization. It is reported that 95% of internal mammary arteries that are anastomosed end-toside to the left anterior descending artery are patent after
*
Operations Performed Fifty-nine patients underwent unilateral mammary Y anastomosis for a total of 118 anastomosed branches, and 8 received a bilateral mammary Y anastomosis for a total of 32 branches. Thus, a grand total of 150 mammary Y graft anastomoses were constructed. A total of 14 patients underwent revascularization using only the mammary arteries, whereas 53 had a combination of mammary and saphenous vein grafts.
Patients’ Profile The average age of the patients was 59 years; 87% of the patients were male. Six percent had a history of cerebrovascular disease, and 18% were diabetic. Thirty-six percent suffered from hypertension, and 49% had a previous myocardial infarction. Sixty-two percent had abnormal left ventricular function as evaluated by abnormal wall contraction on ventriculography. There was an average of 4 grafts constructed per patient.
Follow-up Evaluation Fifty-eight patients were evaluated at an average of 37 -C 2.7 months after operation. Sixty-four percent were free of
Fig 2. Mammary artery Ygrafts to left anterior descending artery and diagonal artery.
MORIN ET AL CAB USING IMA BRANCHES
Ann Thorac Surg 1992;549114
10 years [14]. The use of the internal mammary artery in this fashion contributes to an increased longevity. The 10-year patency rate of the saphenous vein conduit is inferior to that of the internal mammary artery when anastomosed to the left anterior descending artery. The best reported rate at 10 years is approximately 80% [5]. Other large series report patency that ranges between 50% and 70% [15]. It is thus extremely important to try to maximize the patency rate of coronary artery bypass grafts by either extending the use of the mammary artery or finding other conduits that have a similar or even better patency rate. Other authors, as well as ourselves, have tried to use the gastroepiploic artery, but the experience is limited and the long-term results are uncertain. In this cohort of patients we have tried to extend the use of the mammary artery by anastomosing its Y branches. This was successful in increasing our mean graft per patient from 3.4 to 4 grafts per patient. In addition 14 of 67 patients (21%)had complete revascularization with the mammary artery only, without the use of saphenous veins. The operative mortality of 3% is the same as reported for large series of patients. On the other hand, a recurrent rate of angina of 36% at 37 months is higher than reported in cumulative experiences by many centers [5]. On clinical grounds, therefore, it appears that mammary Y grafts are not as satisfactory as direct mammary anastomosis to the left anterior descending artery combined with use of the saphenous vein. Four of 67 patients (6%) underwent reoperation within 3 years, which is higher than the usual reoperation rate of 10% at 10 years. Of the 150 Y branches that were originally constructed, 60 branches were evaluated. Although the patients who
Table 1 . Follow-up Evaluation" Variable Angina 0 1 L
3 4 CHF Mild Severe Stress test Negative Inconclusive Positive Not done Reopera tion Redo CABG Transplantation
No. of Patients
Percent
37 11 4 4 2
64 19 7 7 3
6 2
10 3
27 8 12 11
46 14 21 19
2 2
Fifty-eight patients were followed up 37 -t 2.7 months (mean ? standard deviation) after operation.
a
CABG = coronary artery bypass grafting; failure.
CHF
=
congestive heart
Fig 3. Angiogram O f ginal branches of circumflex artey.
'grafts (arrows)
913
to two mar-
accepted recatheterization were in general more symptomatic than the patients who refused the test, a 42% rate of occlusion in this group is relatively high for the mammary artery conduit. Of the 150 grafts, if we assume that only these 25 studied grafts are blocked and that all the others are open, it would still mean that the occlusion rate is 17%. Thus, our real occlusion rate is situated between 17% and 42%, which is higher than usually reported for this conduit when used as a single pedicle graft. Fourteen patients received Y grafts only, and 10 of 14 (71%)were asymptomatic at the time of reevaluation. Ten branches in 5 patients of this cohort were evaluated by angiography. Four were open, two partially open, and four closed. This is a very small subgroup of patients, and it is not justified to draw a very definitive conclusion. Nevertheless, their clinical status and angiographic results are the same as for the rest of the group. Although we can only speculate as to the reasons for the high occlusion rate, it was our impression that this type of anastomosis is technically more difficult than the standard mammary artery to left anterior descending artery anastomosis. The Y branches are of smaller diameter and could in general only accept the 16-gauge epidural catheter at the time of dilation. The vessel wall
914
Ann Thorac Surg
MORINETAL CAB USING IMA BRANCHES
1992;54:9114
Table 2. Branches Anastomosed Graft Location LAD
First DG
Second DG
No. of Branches 22
16
6
First OM
7
Second OM
7
PVB
1
PDA
1
Patency Condition
No.
Percent
Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed Open Partially closed Closed
13
59 9 32 37 12 50 50 17 33 57
2
7 6 2 8 3 1 2 4 0 3 3 0 4 1 0 0 0 0 1
43 43 57
OM LAD = left anterior descending artery; DG = diagonal artery; = obtuse marginal branch; FDA = posterior descending artery; PVB = posterior ventricular branch.
appeared thinner and more friable, and its layers seemed to separate more easily. In addition, the coronary artery anatomy is not always suitable for the Y grafts to fit perfectly. This can lead to slight angulations and increased tension on the limbs of the Y grafts, which may contribute to the higher obstruction rate. All anastomoses were constructed using 2.5X or 3.5X magnifying loupes and continuous 7-0 Prolene suture. It is possible that better results could be obtained with interrupted techniques using finer suture material with an operating microscope. In conclusion, this study demonstrates the technical feasibility of using mammary artery Y grafts for multiple coronary bypass procedures. Its use is limited, however, by the coronary anatomy and the small sizes of the Y branches. The use of the Y branches of the mammary should be considered when conventional mammary or
vein conduits cannot be used in the classic way. We believe that this technique should be part of the cardiac surgeon’s armamentarium, but its use should be limited unless further refinements in surgical technique can be demonstrated to improve patency. We thank Ms Nadine Fosset, RN, for tracing patients for followup, and data gathering.
References 1. Loop FD, Lytle BW, Cosgrove DM. New arteries for old. Circulation 1989;79(Suppl 1):40-5. 2. Loop FD, Lytle BW, Cosgrove DM, et al. Influence of the internal mammary-artery-graft on 10-year survival and other cardiac events. N Engl J Med 1986;31414. 3. Tector AJ, Schmahl TM, Canino VR, Kallies JR, Sanfilippo D. The role of the sequential internal mammary artery graft in coronary surgery. Circulation 1984;7O(Suppl1):222. 4. Cameron A, Kemp HG Jr, Green GE. Bypass surgery with the internal mammary artery graft: 15 year follow-up. Circulation 1986;74(Suppl 3):3M. 5. Kirklin JW, Naftel DC, Blackstone EH, Pohost GM. Summary of a consensus concerning death and ischemic events after coronary artery bypass grafting. Circulation 1989;79(Suppl 1):81-91. 6. Slater AD, Gott JP, Gray LA Jr. Extended use of bilateral internal mammary arteries for coronary artery disease. Ann Thorac Surg 1990;49:1014-5. 7. Kieser TM, FitzGibbon GM, Keon WJ. Sequential coronary bypass grafts. J Thorac Cardiovasc Surg 1986;91:767-72. 8. Landymore RW, Chapman DM. Anatomical studies to support the expanded use of the internal mammary artery graft for myocardial revascularization. Ann Thorac Surg 1987;M: MI.
9. Tector AJ. Fifteen years’ experience with the internal mammary artery graft. Ann Thorac Surg 1986;42(Suppl):S22-7. 10. Singh RN, Sosa JA. Internal mammary artery-coronary anastomosis. Influence of the side branches on surgical result. J Thorac Cardiovasc Surg 1981;82:909-14. 11. Morin JE, Symes JF, Ralphs-Thibodeau S, Tasse S, Morin A, Lefebvre C. A microcomputer system for the practising cardiac surgeon. Can J Surg 1981;29:364-6. 12. Campeau L. Grading of angina pectoris. Circulation 1976;54: 522-3. 13. Austen WG, Edwards JE, Frye RL, et al. A reporting system on patients evaluated for coronary artery disease. Circulation 1975;51:740. 14. Kirklin JW, Akins CW, Blackstone EH, et al. ACC/AHA guidelines and indications for coronary artery bypass graft surgery. Circulation 1991;83:1125-73. 15. Campeau L, Enjalbert M, Lesperance J, Vaislic C, Grondin CM, Bourassa MG. Atherosclerosis and late closure of aortocoronary saphenous vein grafts: sequential angiographic studies at 2 weeks, 1 year, 5 to 7 years, and 10 to 12 years after surgery. Circulation 1983;68(Suppl 2):l-7.