The Japanese Journal of Surgery (1992) 22:10-14
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SURGERYTODAY
© Springer-Verlag 1992
Original Articles
Multivessel Coronary Revascularization with Bilateral Internal Thoracic Artery Grafts TAIJI MURAKAMI,KOICHIKINO, YUKIOKIOKA, SADAHIKOARAI, KANAMEKUROZUMI,YORIKAZUNAKAYAMA, SHUNJUINDOH, YOSHIMASASENOO, and SHIGERUTERAMOTO The Department of Surgery, OkayamaUniversityMedicalSchool, Okayama,Japan
Abstract: Sixteen patients underwent coronary revascular-
ization with bilateral internal thoracic artery (ITA) grafts between 1988 and 1989 at the Okayama University Hospital. A total 39 coronary grafts were performed, being an average of 2.4 grafts per patient. Each patient received bilateral ITA grafts, and in 5 patients an additional 7 grafts were constructed with 5 autologous veins and 2 gastroepiloic arteries. The right ITA was grafted as a free graft in 4 patients. The ITA graft patency rate was 96.8 per cent (31/32) at the time of hospital discharge. The postoperative morbidity included one reoperation for bleeding and one myocardial infarction. Coronary artery bypass grafting with bilateral ITA grafts can be safely performed and its application facilitates complete revascularization with arterial grafts. Key Words: coronary artery bypass graft, internal thoracic
artery, multivessel revascularization
Introduction
The internal thoracic artery (ITA) has been established as the preferred conduit for myocardial revascularization as it carries a greater long-term patency, an improvement in long-term survival, a decreased need for reoperation and a decreased recurrence of angina, when compared with the saphenous vein graft. 1'2 To further enhance the results of myocardial revascularization, both ITAs have been used in an attempt to bypass multiple vessels with this conduit. 3,4 Bilateral ITA grafting has been our initial choice of operation for the patient who needs multivessel revascularization. A review of all patients undergoing revascularization with bilateral ITA grafts at the Okayama University Hospital during the period from 1988 to 1989 was Reprint requests to: Taiji Murakami, MD, The Department of Surgery, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama City, Japan (Received for publication on Apr. 10, 1990)
undertaken to document the early clinical and angiographic results of that procedure.
Materials and Methods
A total 16 patients underwent coronary revascularization with bilateral ITA grafts during the period from February, 1988 to December, 1989 at the Okayama University Hospital. During the same period, 7 other patients received a single ITA graft, while 2 received a saphenous vein graft without the use of ITA grafts; one because he was 70 years old and the other underwent a combined procedure of left ventricular aneurysmectomy and a saphenous vein graft. Of the above 16 patients, 14 were men and 2 women, with a mean age at operation of 61 years, ranging from 55 to 68 years. Twelve patients had stable angina, 3 unstable angina, and one asymptomatic coronary heart diseasel The coronary risk factors included diabetes mellitus in 2 patients, familiar hyperlipidemia in 1, and prior myocardial infarction in 12 (being anterior in 2 and inferior in 10). Preoperative angiography demonstrated single-vessel disease in 3 patients, double-vessel disease in 6, triple-vessel disease in 5 and left main coronary artery stenosis in 2. One patient had a left ventricular aneurysm and another had mitral valve regurgitation due to the prolapse. Three patients were in New York Heart Association (NYHA) functional Class II, 10 in Class III, and 3 in Class IV. The ITA and accompanying vein were dissected as a pedicle from the ITA subclavian source proximally to its bifurcation distally after the bilateral pleurae had been opened. For in situ grafts, the ITA origin from the subclavian artery was left intact. The distal end of the ITA was divided proximal to the major bifurcation then anastomosed to the coronary artery. If the in situ graft could not reach the coronary artery, the ITA was divided proximally and used as a free graft. All opera-
T. Murakami et al.: Bilateral ITA Grafts
11
tions were conducted using cardiopulmonary bypass and moderate systemic hypothermia. Cold potassium cardioplegia and topical cooling were employed. The ITA-coronary artery anastomosis was constructed with a continuous 8-0 Prolene suture and the proximal anastomosis of the aortocoronary free graft constructed with a continuous 7-0 Prolene suture.
Results
A total 39 coronary grafts were performed on the 16 patients, being an average of 2.4 grafts per patient. Each patient received bilateral ITA grafts, and in 5 patients an additional 7 grafts were constructed with 5 autologous veins and 2 right gastroepiploic arteries. The ITA graft and corresponding recipient arteries are listed in Table 1. In 8 patients, the right ITA was grafted to the left anterior descending (LAD) coronary artery and the left ITA to the obtuse marginal (OM) artery. In 4 patients, the right ITA was grafted to the right coronary artery (RCA) and the left ITA to the LAD. In 3 patients, the right ITA was grafted to the diagonal artery and the left ITA to the LAD. In one
Table 1. Bilateral internal thoracic artery grafts LITA RITA REGA LAD OM PL
7 8 1
Total
16
LAD D1 RCA eL
7 4 (1 a) 4 (2a) 1 (]a) 16 (4a)
RCA RCA
1 1
SVG RCA OM PL
2
1 2 2 5
": free graft. Abbreviations: LITA, left internal thoracic artery; RITA, right internal thoracic artery; RGEA, right gastroepiploic artery; SVG, saphenous vein graft; LAD, left anterior descending artery; OM, obtuse marginalartery; PL, posterolateralbranch of the circumflex artery; D, diagonal branch; and RCA, right coronary artery. patient, the right ITA was grafted as a free graft to the posterolateral branch of the circumflex artery and the left ITA to the OM (Fig. 1). The right ITA was grafted as a free graft to the R C A in 2 patients, to the posterolateral branch in 1 patient, and to the diagonal artery in 1 patient (Fig. 2). Mitral valve replacement was performed as part of a combined operation in one patient. No operative deaths occurred, although one patient required reoperation for postoperative bleeding. Peri-
U
~JU
Fig. 1. Bilateral internal 8 cases
4 cases
3 cases
1 case
RGEA
2 cases
1 case
1 case
thoracic artery grafts
Fig. 2. Free right internal thoracic artery grafts
12
T. Murakami et al.: Bilateral ITA Grafts
Table 2. Pre- and post-operative cardiac functions C1 LVEDP (1/min/m2) (mmHg) FS (%)
mVcf (sec-1)
EF (rest --~ exercise, %)
% A EF
Pre-op
2.9 + 0.6
11.3 _+ 9.4
31.1 _+ 9.2
1.02 _+0.30
53.7 + 12.2-~ 48.0 _+ 11.6
-10.3 + 11.2
Post-op
2.7 _+ 0.3
14.2 _+ 6.8
25.4 + 6.6
0.97 _+0.35
50.6 _+ 12.7-~ 48.3 _+ 12.6
-2.5 _+ 19.2
operative myocardial infarction, defined as new Q waves in the ECG combined with cardiac enzyme elevation, was documented in one patient as an inferior infarction. One right ITA grafted to the LAD became occluded and therefore, the ITA graft patency rate was 96.8 per cent (31/32) at the time of hospital discharge. All 16 patients reported no angina at subsequent follow-up examinations. Preoperatively, 3 patients were in N Y H A Class II, 10 in Class Ill, and 3 in Class IV, whereas postoperatively, 14 patients were in N Y H A Class I and 2 in Class II. Thallium-201 myocardial scintigraphy during exercise was performed in all 16 patients which showed no postoperative myocardial ischemia in 8 patients, increased regional myocardial blood flow in 4 patients, persistent myocardial ischemia in 3 patients, and a new perfusion defect in the inferior wall of the left ventricle in 1 patient. The preoperative and postoperative cardiac functions are shown in Table 2. The cardiac index (CI), left ventricular end-diastolic pressure (LVEDP), fractional shortening (FS), and mean velocity of circumferencial fiber shortening (mVcf) demonstrated no significant changes. Multiple gated equilibrium cardiac blood pool scintigraphy during bicycle exercise was performed in 9 patients and the left ventricular ejection fraction (EF) by the gated equilibrium technique and per cent changes of EF at rest and exercise (per cent AEF) are
EF (rest ~ ex)
( %)
Discussion The autologous saphenous vein is the standard conduit for coronary artery bypass grafting; clinical and angiographic studies having demonstrated favorable early and late results of direct coronary revascularization with the saphenous vein. However, if the saphenous vein is absent or unsuitable, myocardial revascularization is dependent upon alternative conduits. Alternative coronary bypass conduits that were evaluated in the past but have been largely abandoned include the autologous free radial artery, in situ autologous splenic artery, and homologous saphenous vein. Alternative conduits currently used for myocardial revascularization include the autologous arm vein, homologous umbilical vein, and expanded polytetrafluoroethylene (PTFE) prosthetic grafts. 5 However, the early angio-
%AEF
(%)
00
50 40
80
30
60 tj.
1O0
40
- 10
~
2o
20
0
shown in Table 2 and Fig. 3. In 7 patients, the per cent changes of EF increased after the operation but these changes were not statistically significant. Fig. 4 depicts the postoperative angiography of a patient who received triple coronary artery bypass grafts. The RITA was grafted to the RCA, the LITA to the LAD, and the saphenous vein to the obtuse marginal artery and postero-lateral branch of the circumflex artery.
30
I
I
I
I
rest
ex
rest
ex
pre-op
post-op
- 40 - 50 pre-op
post-op
Fig. 3. Pre- and post-operative cardiac functions
T. Murakami et al. : Bilateral ITA Grafts
13
Fig. 4. Postoperative angiography of bilateral internal thoracic artery grafts and a saphenous vein graft
graphic and clinical data for these grafts are not extensive, and late angiographic and clinical data have not been reported. As vein graft atherosclerosis became recognized, there was reports about the low attrition rate of the internal thoracic artery conduit in bypass surgery. 3'6-8 These serial postoperative angiography reports confirmed that approximately half the vein grafts closed by the 10th to 12th postoperative year. In contrast, the internal thoracic artery graft rarely showed atherosclerosis and had a late patency in the 90th percentile up to 12 years postoperatively. Loop et al. 2 reported that an internal thoracic artery graft, rather than a vein graft, to the anterior descending coronary artery significantly improved long-term survival, decreased the occurrence of myocardial infarction, decreased the need for reoperation and improved the cumulative event-free survival. Numerous methods of extending the use of ITA grafts have been suggested, including augmenting their length by multiply-transecting the fascia in the ITA pedicle, 9 constructing sequential grafts, 1° using free ITA grafts by constructing an aorta-ITA anastomosis,ll using both ITAs, 3'4 and choosing the shortest route from the ITA origin to the recipient coronary artery.12 The patency of sequential grafts is equivalent to that of early reports of in situ ITA grafting to one coronary vessel. Dion 1° reported that 157 patients were recatheterized 6 months after the operation and that 95 per cent of the sequential ITA anastomoses were still patent. The free aortocoronary ITA graft is useful for two reasons; la firstly, its use may allow the surgeon to avoid crossing the midline, which may jeopardize the right internal thoracic artery in the case of reoperation and; secondly, the free graft gains additional length to reach a distal anastomosis. Loop et al. al reported that of 40 free grafts restudied within 18 months, 31 (77 per cent) were patient. However, the durability of the free
graft was shown by the fact that 32 of 35 (91 per cent) free grafts studied for more than 18 months postoperatively over a mean period of 94 months were open, and 24 of 26 (92 per cent) grafts restudied beyond 60 months were patent. These late studies of free ITA grafts showed no evidence of graft atherosclerosis and the findings expand the versatility of ITA grafting, justifying the wider use of free ITA grafts. Barner 13 reported performing double internal mammary-coronary bypass in 100 patients in 1974, and Geha 14 showed crossed double internal mammarycoronary artery grafts in 36 patients with excellent functional results. Lytle et al. 3 followed 76 consecutive patients with bilateral ITA grafts operated on from 1971 to 1980 for an average of 67 months. The actuarial survival was 97.2 per cent at 7 years and 90.2 per cent at 9 years. Galbut et al. 4 showed that patients with bilateral ITA grafts had the best survival rates of all and the highest event-free survival. A 10-year survival rate of 83 per cent was reported by these authors, however, surgeons are concerned that the longer, more complicated, and technically more demanding procedure of bilateral ITA grafting may have an adverse effect on surgical morbidity and mortality. Criticisms of bilateral ITA grafting include the following: the graft preparation is technically demanding, can prolong the operation, and may possibly increase the risk of bleeding, wound infection and respiratory comp!ications. Depending on the years surveyed, wound infection is 1 to 3 per cent higher in bilateral ITA graft patients and related to diabetes and age more than any other factor. 15 In this article, the author concluded that bilateral ITA grafting did not increase surgical mortality but increased surgical morbidity slightly in the transfusion requirement. We did not encounter any serious complications in our patients, except for one reoperation for bleeding and one perioperative inferior myocardial infarction.
14
Two reports 16'17in 1987 detailed successful use of the right gastroepiploic artery for coronary artery bypass grafting. Pym 16 detailed his experience in 9 patients with direct right gastroepiploic-to-coronary artery grafting involving distal right and circumflex coronary vessels, whereas Suma ~7 described their use of the right gastroepiploic artery for direct left anterior descending CABG in two cases. Since then, several articles have reported experiences with this new arterial conduit for CABG. Mills ~8 described his experience with 39 patients undergoing CABG using the right gastroepiploic artery. Early postoperative angiography in 29 patients revealed all grafts to be patent. Lytle a9 reported that histologically, right gastroepiploic artery segments from 18 patients could not be distinguished from internal mammary artery segments and that no evidence of atherosclerosis was found. He concluded that early graft patency had been excellent and that the histologic similarity between the right gastroepiploic artery and internal mammary artery suggested favorable long-term results. We used the right gastroepiploic artery as an in situ graft for the right posterior descending CABG in two patients. The postoperative functional results were satisfactory and postoperative angiography revealed both grafts to be patent. Thus, it is concluded that coronary artery bypass grafting with a combined arterial graft using both the internal thoracic artery and right gastroepiploic artery can be safely performed and its application facilitates complete revascularization with arterial grafts.
References 1. Lytle BW, Loop FD, Cosgrove DM, Ratliff NB, Easley K, Taylor PC (1985) Long-term (5 to 12 years) serial studies of internal mammary artery and saphenous vein coronary bypass grafts. J Thorac Cardiovasc Surg 89:248-258 2. Loop FD, Lytle BW, Cosgrove DM, Stewart RW, Goormastic M, Williams GW, Golding LAR, Gill CC, Taylor PC, Sheldon WC, Proudfit WL (1986) Influence of the internal-mammaryartery graft on 10-year survival and other cardiac events. N Engl J Med 314:1-6
T. Murakami et al.: Bilateral ITA Grafts 3. Lytle BW, Cosgrove DM, Saltus GL, Taylor PC, Loop FD (1983) Multivessel coronary revascularization without saphenous vein: Long-term results of bilateral internal mammary artery grafting. Ann Thorac Surg 36:540-547 4. Galbut DL, Traad EA, Dorman MJ, DeWitt PL, Larsen PB, Weinstein D, Ally JM, Gentsch TO (1985) Twelve-year experience with bilateral internal mammary artery grafts. Ann Thorac Surg 40:264-270 5. Foster ED, Kranc MAT (1989) Alternative conduits for aortocoronary bypass grafting. Circulation 79:1-34-1-39 6. Singh RN, Sosa JA, Green GE (1983) Long-term fate of the internal mammary artery and saphenous vein grafts. J Thorac Cardiovasc Surg 86:359-363 7. Frey RR, Bruschke AVG, Vermeulen FEE (1984) Serial angiographic evaluation 1 year and 9 years after aorta-coronary bypass. J Thorac Cardiovasc Surg 87:167-174 8. Barner HB, Standeven JW, Reese J (1985) Twelve-year experience with internal mammary artery for coronary artery bypass. J Thorac Cardiovasc Surg 90:668-675 9. Cosgrove DM, Loop FD (1985) Techniques to maximize mammary artery length. Ann Thorac Surg 40:78-79 10. Dion R, Verhelst R, Rousseau M, Goenen M, Ponlot R, Kestens-Servaye Y, Chalant C, Braimbridge M (1989) Sequential mammary grafting. J Thorac Cardiovasc Surg 98:80-89 11. Loop FD, Lytle BW, Cosgrove DM, Golding LAR, Taylor PC, Stewart RW (1986) Free (aorta-coronary) internal mammary artery graft. J Thorac Cardiovasc Surg 92:827-831 12. Vander Salm TJ, Chowdhary S, Okike ON, Pezzella AT, Pasque MK (1989) Internal mammary artery grafts: The shortest route to the coronary arteries. Ann Thorac Surg 47:421-427 13. Barner HB (1974) Double internal mammary-coronary artery bypass. Arch Surg 109:627-630 14. Geha AS (1976) Crossed double internal mammary-to-coronary artery grafts. Arch Surg 111:289-292 15. Cosgrove DM, Lytle BW, Loop FD, Taylor PC, Stewart RW, Gill CC, Golding LAR, Goormastic M (1988) Does bilateral internal mammary artery grafting increase surgical risk? J Thorac Cardiovasc Surg 95:850-856 16. Pym J, Brown PM, Charrette EJP, Paker JO, West RO (1987) Gastroepiploic-coronary anastomosis. J Thorac Cardiovasc Surg 94:256-259 17. Suma H, Fukumoto H, Takeuchi A (1987) Coronary artery bypass grafting by utilizing in situ right gastroepiploic artery: basic study and clinical application. Ann Thorac Surg 44:394397 18. MillsNL, Everson CT (1989) Right gastroepiploic artery: a third arterial conduit for coronary artery bypass. Ann Thorac Surg 47:706-711 19. Lytle BW, Cosgrove DM, Ratliff NB, Loop FD (1989) Coronary artery bypass grafting with the right gastroepiploic artery. J Thorac Cardiovasc Surg 97:826-831