The advantages in using the internal mammary artery

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1 Composite Arterial Conduits for a Wider Arterial Myocardial Revascularization Antonio M. Calafiore, MO, Gabriele Di Giammarco, MO, Nicola Luciani, MO, Nicola Maddestra, MO, Ernesto Di Nardo, MO, and Romeo Angelini, MO Cattedra di Cardiochirurgia, Universita di Chieti, Chieti, Italy From October 1991 to May 1993, 130 patients were submitted to myocardial revascularization using complex preformed arterial conduits. The age ranged from 29 to 75 years (mean age, 60.1 years); 121 patients were male. One hundred twenty-six patients had double- or triple-vessel disease. The mean ejection fraction was 0.53 (range, 0.22 to 0.79); only 6 patients had an ejection fraction less than In 6 cases the procedure was a reoperation. We used 360 arterial conduits, 163 of which as free grafts (3 left internal mammary arteries, 16 right internal mammary arteries, 86 inferior epigastric arteries, 57 radial arteries, and 1 right gastroepiploic artery). One hundred fifty-four free grafts were anastomosed to one or both internal mammary arteries and one to a radial artery. We con- structed 136 complex arterial conduits (branched, lengthened, or both). In 6 cases a double arterial system had to be used in a single patient. There was no operative mortality, and no inotropic or mechanical supports were used. The overall mortality rate was 1.5%. Earlyangiographic controls (between the 7th and 15th postoperative days) demonstrated 100% patency;late angiographic controls (at a mean interval of 9.5 months after operation) documented a mean patency rate ranging from 94.1% of the radial arteries to 100% of the left internal mammary arteries and right gastroepiploic arteries. At a mean follow-up of 7.2 months (range, 1 to 15 months) all patients are alive without recurrence of symptoms. (Ann Thorae Surg 1994;58:185-90) The advantages in using the internal mammary artery (IMA) in myocardial revascularization have been accepted broadly, both for its durability and for better survival compared with saphenous vein [1-3]. In the attempt to limit the use of vein and considering the growing demand for multiple coronary revascularization, either in primary or in secondary operations, which are not always feasible with both IMAs, new arterial conduits are being tested. Some of them, such as the right gastroepiploic artery (RGEA) or the radial artery (RA), had already been used in coronary operations without significant success or with discouraging results [4]. A third arterial graft, the inferior epigastric artery (IEA), has been used recently [5-7]. Although the RGEA can be used as either a pedicled or a free graft, RA and IEA can only be used as free grafts. Arterial conduits used as free grafts show the same late patency as saphenous vein [8], the common point being the aortic anastomosis. For this reason we decided to perform as a routine proximal anastomoses of arterial free grafts on the IMA. This technique already was used in particular situations by other surgeons [5]; we extended it to arrange complex arterial conduits before establishing extracorporeal circulation, tailoring them according to the topography of coronary lesions. In this report we describe the technique used and the results. Accepted for publication Nov 24, Address reprint requests to Dr Di Giammarco, Clinica Cardiochirurgica, Ospedale US.Camillo de Lellis," via Forlanini, 50, Chieti, Italy by The Society of Thoracic Surgeons Material and Methods Patients From October 1991 to May 1993, 130 patients were submitted to myocardial revascularization using complex preformed arterial conduits; in 6 cases the procedure was a reoperation. The clinical characteristics of the patients are summarized in Table 1. Three-hundred ninety-five conduits were employed altogether: 128 LIMAs, 69 RIMAs, 86 IEAs, 20 RGEAs, 57 RAs, and 35 saphenous veins. Of 360 arterial conduits, 163 were used as free grafts: 3 LIMAs, 16 RIMAs, 86 leas, 57 RAs, and 1 RGEA. Five RAs and 1 RIMA had to be anastomosed on ascending aorta; lea and RGEA had to be anastomosed to a saphenous vein in 1 patient each. Of the remaining 155 free grafts, 154 were anastomosed to one or both IMAs and one to an RA, according to the coronary lesions, constructing 136 complex arterial conduits; these systems, together with the donor vessel, included 2 conduits in 117 patients, 3 in 18 patients, and 4 in 1 patient. In 6 cases a double complex arterial system had to be used. Table 2 shows the different arrangements of the grafts in the composite conduits. Surgical Technique The IMA, harvested as a pedicle, is divided distally after systemic heparinization. The artery is cannulated by a I-mm Teflon needle and is gently injected with 10 ml of a solution containing papaverine (1 mg/1 ml of normal saline solution). A hemostatic clip then is applied distally to allow the artery to dilate for at least 10 minutes. The lea is harvested from a paramedian incision run /94/$7.00

2 186 CALAFIORE ET AL CORONARY REVASCULARIZATIONWITH ARTERIAL GRAFTS Ann Thorac Surg 1994;58: Table 1. Clinical Characteristics of the Patients Variable Mean age (y) (range) Sex(MlF) l-vessel disease 2-vessel disease 3-vessel disease LMT Mean EF (range) > <0.35 Urgent/elective Redo EF = ejection fraction; LMT = left main trunk. Value 60.1 (29-75) 121/ ( ) /96 6 ning from a few centimeters below the transverse umbilicalline to the groin. After its fascia is opened, the rectus muscle is displaced medially to expose the first part of the lea. The artery is then followed proximally, up to about 2 ern from its origin, and distally up to its first muscular collaterals, for about 6 cm of length. The vessel is flushed with the same solution as above to wash out the blood from the intimal layer; papaverine solution also is used to immerse the artery before its use. The RA is used only in the patients with normal Allen test. The artery is harvested from a few centimeters down its origin to the wrist, together with its satellite veins and the surrounding adipose tissue. It is treated as the lea. The free grafts always are anastomosed to the donor conduit before extracorporeal circulation is established, laying them down on a folded pad put between the branches of the sternal retractor beside the donor conduit to assure a relatively stable operating field. The anastomosis between the donor conduit and the free graft is performed as end-to-side, end-to-end, or both. END-TO-SIDE ANASTOMOSIS. The posterior surface of IMA is always preferred as the site of the anastomosis of the free grafts. After the underlying fascia is incised and the IMA carefully dissected for about 15 mm, the artery is clamped proximally to the established point. Then the donor conduit is incised for about 8 mm. The conduit is laid down on a folded pad put between the branches of the sternal retractor to make the operating field relatively stable. Then the free graft, mouthed obliquely at its tip, is anastomosed with 7-0 or 8-0 suture (Ethicon Inc, Somerville, NJ; or Sharpoint, Reading, PA). The donor conduit is declamped proximally after the free graft has been clamped temporarily and the site of the anastomosis has been inspected carefully. The free graft is irrigated with 5 ml of the solution mentioned above, and its tip is finally ligated with a hemostatic clip. To avoid bleeding from the little collaterals that are not visible before pharmacologic dilation, hemostasis of the free graft is checked again. In the case of the RA this procedure is particularly important. When the LIMA had to be used to reach the left anterior descending artery, different arrangements of the free grafts on the donor conduit were adopted to achieve a more complete revascularization of the left territories. The more commonly used arrangement was the lea on a diagonal branch, whereas the RA was employed to reach more distant branches. When the left anterior descending artery had to be revascularized with the RIMA, the RA was used on the right coronary territories. This conduit had to be used as a donor vessel in a patient who had a LIMA damaged proximally during the harvesting. END-TO-END ANASTOMOSIS. A free graft was used 19 times to lengthen an RIMA or an LIMA directed to an otherwise not reachable vessel or to execute a sequential anastomosis. This technique allowed us to employ an IMA accidentally cut or partially dissected. In this case the extremity of the free graft and that of the donor conduit were obliquely mouthed to assure a wider anastomosis. The conduit then was treated in the same manner as above. COMBINED END-TO-END AND END-TO-SIDE ANASTOMOSIS. In 2 patients both types of anastomoses were used. In these cases the RIMA, too short to be employed as a donor Table 2. Patterns of Arrangement of the Arterial Grafts in the Composite Conduits Pattern of Arrangement Inflow Branches or Conduit Lengthening No. of Conduits No. of Distal Anastomoses Branches LIMA RIMA 9 19 LIMA lea LIMA RA LIMA RIMA/lEA 3 9 LIMA lea/lea 3 9 LIMA IEAIRA 9 28 LIMA IEA/RIMA/IEA 1 4 RIMA LIMA 1 2 RIMA lea 5 10 RIMA RA 6 12 RA LIMA 1 2 Total Lengthening LIMA IEA 3 5 LIMA RA 2 2 RIMA LIMA 1 1 LIMA lea 8 8 LIMA RA 5 8 Total Lengthening/ branch LIMA RIMA/lEA 1 2 LIMA RIMAIRA 1 2 Total 2 4 Grand total lea = inferior epigastric artery; LIMA = left internal mammary artery; RA = radial artery; RIMA = right internal mammary artery.

3 Ann Thorac Surg 1994;58: CALAFIORE ET AL 187 vessel, had to be cut down. Then it was anastomosed end-to-side to the LIMA (donor conduit) and was lengthened with the IEA (1 case) or with the RA (1 case). All the anastomoses between the conduits were performed under total heparinization and before establishment of extracorporeal circulation. Cardiopulmonary bypass was instituted between the right atrium and the ascending aorta in all patients. Myocardial protection was achieved with intermittent blood cardioplegia delivered in an antegrade fashion through the aortic root; cold cardioplegia was used in 41 patients and warm cardioplegia in the remaining 89. In all cases the donor conduit was anastomosed first to tailor better the side branches when necessary. Only the IMA was anchored to the epicardium with two stitches passed through the muscular remnants of the distal part of its pedicle. The coronary anastomoses were performed with 7-0 or 8-0 sutures (Ethicon or Sharpoint). Of 389 distal anastomoses, with an average of three anastomoses per patient, 35 were venous and 354 were arterial; 282 of the latter were performed using complex preformed arterial conduits. There were six sequential anastomoses using 1 RIMA, 3 RAs, and two lengthened conduits (LIMA to lea and RIMA to RA). In 100 patients only arterial grafts were employed with a number of anastomoses ranging from two to five. The mean cardiopulmonary bypass time was 64 minutes (range, 31 to 93 minutes) and the mean aortic cross-clamping time was 42 minutes (range, 20 to 69 minutes). After aortic declamping a continuous intravenous infusion of diltiazem was administered up to the first postoperative day. It then was administered orally at a dose of 60 mg three times a day (up to 6 months if the RA is present; up to 1 month in the other cases), and aspirin was given at a dose of 325 milligrams daily up to 2 years after operation. Results There was no need of inotropic or mechanical support in the operating theater. One patient died on the first day postoperatively of Table 3. Angiographic Controls Early Control Late Control (7-15 days) (6-14 mol Arterial No. Controlledl Patency No. Controlledl Patency Conduit No. Patent (%) No. Patent (%) LIMA 43/ / RIMA 35/ / IEA 34/ / RA 26/ / RGEA 5/5 2/2 lea = inferior epigastric artery; LIMA left internal mammary artery; RA = radial artery; RGEA = right gastroepiploic artery; RIMA = right internal mammary artery. Fig 1. Left internal mammary artery (LIMA) (to diagonal branch) Y-branched with radial artery (RA) (to obtuse marginal side-to-side and to posterolateral branch end-to-side) at 7 days. myocardial necrosis due to an acutely thrombosed IMA; 1 patient died on the fourth day postoperatively of pancreatic shock. The overall in-hospital mortality rate was 1.5%. No patient received pharmacologic or mechanical support in the intensive care unit. Enzymatic or electrocardiographic signs were observed in 3 patients during the stay in the intensive care unit; all conduits were angiegraphically patent and the only change was an apical akinesia in 1 patient, compared with the preoperative control. The bleeding up to 24 hours after the operation was low (mean ± standard deviation, 743 ± 471 ml) and only 35 patients needed a blood transfusion (mean, 0.7 blood units/patient). One patient had to be reoperated on for bleeding and 2 for sternal dehiscence. The last 2 patients were diabetics who had to be submitted to bilateral IMA harvesting. Angiographic Controls Early angiographic controls have been performed between the seventh and 15th days postoperatively; late controls have been performed at a mean interval of 9.5 months after operation (range, 6 to 14 months). The results are reported in Table 3. We did not observed any graft disease or spasm, the patterns being full patency or complete occlusion. The more common angiographic features of these preformed conduits are shown in Figures 1 through 7. Clinical Outcome At a mean follow-up of 7.2 months (range, 1 to 15 months) all patients are alive without recurrence of symptoms.

4 188 CALAFIORE ET AL Ann Thorac Surg 1994;58: Fig 2. Left internal mammaryartery (LIMA) (to left anterior descending) Y-branched with inferior epigastric artery (lea) (to diagonal branch) at 13 months. Comment The long-term results of myocardial revascularization have improved steadily with the use of one or both IMAs [1, 9, 10). This fact has led to increasing use of this artery in primary or in repeated operations. Other arterial con- Fig 3. Left internal mammaryartery (LIMA) (to obtuse marginal) Y-branched with inferior epigastric artery (lea) (to diagonal branch) at 12 months. Fig 4. Right internal mammary artery (RIMA) (to diagonal branch) Y-branched with inferior epigastric artery (lea) (to left anterior descending) at 14 months. Fig 5. Left internal mammary artery (LIMA) (to left anterior descending) Y-branched with radial artery (RA) (to obtuse marginal) at 10 months.

5 Ann Thorae Surg 1994;58: CALAFIORE ET AL 189 duits recently have been introduced into clinical practice in the belief that arteries could be the conduits of choice for myocardial revascularization [5-7, 11-13]. However, their use has not become popular for various reasons: the lack of late angiographic controls, prolonged cardiopulmonary bypass and cross-clamping times, and some technical difficulties. Moreover all these conduits (except RGEA) can be used only as free grafts, so they need aortic anastomosis either direct or with the interposition of a pericardial patch [5]. It is generally accepted that the behaviour of the arterial free grafts (IMA or different arteries) proximally anastomosed to the aorta is similar to that of saphenous vein for the first year after the operation. After this period they show the same fate as the pedicled arterial conduits [8]. In our opinion there could be two reasons. One is the mismatch between the aorta and the conduit wall in terms of thickness and diameter; this fact implies technical difficulties in executing the anastomosis and could lead to an impairment of flow. Moreover-and in our opinion this is the main reason-these arteries are normally thirdor fourth-order branches of the aorta, so they usually are submitted to a pattern of flow that is quite different and cannot tolerate the flow of the ascending aorta. When these conduits are anastomosed to the aorta the abrupt increase in pressure wave can result in wall stretching with intimal tearing and subsequent development of premature hyperplasia. Furthermore, the RA offers a constant diameter and a length sufficient to reach almost all coronary branches. The lea, on the contrary, has a constant diameter only in the first 5 to 6 em of its course; then it shows a progressive and sensible caliber reduction. When it has to be anasto- Fig 7. Left internal mammaryartery (LIMA) (to left anterior descending) V-branched with radial artery (RA) (to posterolateral branch), V-branched with inferior epigastric artery (lea) (to diagonal branch) at 11 months. mosed to the ascending aorta, the lea must be harvested in all its length, from the groin to the umbilicus, where the diameter of the artery is very small; moreover, many muscular collaterals must be divided, thereby exposing the rectus muscle to ischemia. For these reasons we tend always to use the IMA and the RGEA as pedicled grafts and to branch or lengthen the IMA with the lea or the RA. The technique described above is feasible and the anastomoses so performed are completely safe; furthermore, they can be checked easily before the conduits are put in site. The immediate and the mid-term results reported in this series are encouraging. However, longterm follow-up is needed to assess its value compared with IMA. Fig 6. Right internal mammaryartery (RIMA) lengthened with radialartery (RA) to posterior descending artery at 10 months. The arrow indicates the end-to-end anastomosis between RIMA and RA. References 1. Loop FO, Lytle BW, Cosgrove OM, et al. Influence of the internal mammary artery graft on lo-year survival and other cardiac events. N Engl J Med 1986;314: Zeff RH, Kongatahworn C, Iannone LA, et al. Internal mammary artery versus saphenous vein graft to the left anterior descending coronary artery: prospective randomized study with lo-year follow-up. Ann Thorac Surg 1988;45: Barner HB, Standeven JW, Reese J. Twelve-year experience with internal mammary artery for coronary artery bypass. J Thorac Cardiovasc Surg 1985;90: Mills NL, Everson CT. Right gastroepiploic artery: a third conduit for coronary artery bypass. Ann Thorac Surg 1989; 47: Puig LB, CiongoIIi W, Cividanes GL, et al. Inferior epigastric artery as a free graft for myocardial revascularization. J Thorac Cardiovasc Surg 1990;99: Barner HB, Naunheim KS, Fiore AC, Fischer VW, Harris HH.

6 190 CALAFIORE ET AL Ann Thorae Surg 1994;58: 18S-90 Use of the inferior epigastric artery as a free graft for myocardial revascularization. Ann Thorac Surg 1991;52: Buche M, Schoevaerdts JC, Lavagie Y, et al. Use of the inferior epigastric artery for coronary bypass. J Thorac Cardiovasc Surg 1992;103: Loop FD, Lytle BW, Cosgrove OM, Golding LAR, Taylor pc, Stewart RW. Free (aorto-coronary) internal mammary artery graft: late results. J Thorac Cardiovasc Surg 1986;92: Galbut DL, Traad EA, Dorman M], et al. Seventeen year experience with bilateral internal mammary artery grafts. Ann Thorac Surg 1990;49: Fiore AC, Naunheim KS, Dean P, et al. Results of internal thoracic artery grafting over fifteen years: single versus double grafts. Ann Thorac Surg 1990;49: Pym J, Brown PM, Charrette ED, Parker JO, West RO. Gastroepiploic--coronary anastomosis. J Thorac Cardiovasc Surg 1987;94: Suma H, Wanibuchi Y, Terada Y, Fukuda S, Takayama T, Furuta S. The right gastroepiploic artery graft. Clinical and angiographic midterm results in 200 patients. J Thorac Cardiovasc Surg 1993;105: Acar C, [ebara V, Portoghese M, et al. Revival of the radial artery for coronary bypass grafting. Ann Thorac Surg 1992; 54: A Special Topical Meeting Preparing Your Practice for Change: Thoracic Surgery Into the Next Decade Hyatt Regency Hotel Atlanta, Georgia, September 24-25, 1994 "Preparing Your Practice for Change" will be a unique topical meeting focusing on how the practice of thoracic surgery is being affected as the healthcare reform process sweeps the country. All those interested in keeping their thoracic surgery practices well positioned in the future will benefit from this meeting. Thoracic surgeons from all practice arrangements and all areas of subspecialization as well as surgical practice administrators are encouraged to attend this meeting. The meeting is sponsored by The Society of Thoracic Surgeons under the direction of its Major Issues Committee. The program will feature a variety of nationally renowned experts including many members of The Society who will discuss the major concerns and issues affecting the decision of how to adapt a thoracic surgery practice for the coming change. The program will begin on Saturday, September 24, at 8:30 AM and will conclude on Sunday, September 25, at 1:00 PM. Session topics on Saturday morning include discussion of the political and environmental forces that affect thoracic surgery practices. Various practice patterns will be highlighted to identify critical issues affecting successful adaptation to change. A special luncheon speaker, H. Ross Perot, will address the Physician's Role in Healthcare Reform. Saturday afternoon will focus on getting the most from your healthcare dollar. Discussion of contract negotiations for thoracic surgery services will be undertaken by representatives of managed care organizations as well as hospital administrators. The feasibility of capitation for thoracic surgery practice will be reviewed. The afternoon will conclude with an exploration of quality assessment by database studies as well as outcome analysis, both of which may be mandated in the future. On Sunday morning the meeting will address the role of industry in the new scheme of practice, and there will be a discussion of thoracic surgical training and distribution of specialty services as they relate to future healthcare needs. Further details on this meeting will be mailed to all members of The Society in the near future and may be requested from The Society of Thoracic Surgeons, 401 N Michigan Ave, Chicago, IL 60611; (312)