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Ann Thorac Surg 2010;90:744-752. doi:10.1016/j.athoracsur.2010.03.109
© 2010 The Society of Thoracic Surgeons
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Right arrow Coronary disease

Original Articles: Adult Cardiac

Comparison of Right Internal Thoracic Artery and Right Gastroepiploic Artery Y Grafts Anastomosed to the Left Internal Thoracic Artery

Kwang Ree Cho, MD, PhDa, Ho Young Hwang, MDb, Jun-Sung Kim, MDb, Dong Seop Jeong, MD, PhDb, Ki-Bong Kim, MD, PhDb,*

a Department of Thoracic and Cardiovascular Surgery, Cheju Halla General Hospital, Seoul, Republic of Korea
b Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul, Republic of Korea

Accepted for publication March 19, 2010.

* Address correspondence to Dr K-B Kim, Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, 28 Yeongeon-dong, Jongno-gu, Seoul 110-744, Republic of Korea (Email: kimkb{at}snu.ac.kr).

Presented at the Forty-sixth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 25–27, 2010.


   Abstract
Top
 Abstract
Introduction
 Material and Methods
 Results
 Comment
 Discussion
 References
 
Background: Early and 1-year results of arterial Y composite grafts anastomosed to the in situ left internal thoracic artery were studied.

Methods: Three hundred twelve patients who underwent off-pump coronary artery bypass using arterial Y composite grafts for revascularization of the left coronary artery territory were analyzed. A skeletonized right internal thoracic artery (RITA) or right gastroepiploic artery (RGEA) was anastomosed to the side of the left internal thoracic artery to construct a Y composite graft. Propensity-matched analysis was used to match patients using RITA (RITA group, n = 102) with patients using RGEA (RGEA group, n = 102). Postoperative coronary angiographies were performed early (200 of 204; 1.8 ± 1.7 days) and 1 year (171 of 204, 11.3 ± 2.5 months) postoperatively.

Results: There were no differences in postoperative mortalities (1 of 102 versus 2 of 102; p = 1.000) and morbidities including atrial fibrillation, mediastinitis, and perioperative myocardial infarction between the RITA and RGEA groups (not significant). Early and 1-year postoperative angiographies showed that there were no significant differences in patency rate between the two groups (early, 99.4% versus 99.3%; p = 1.000; 1-year, 95.4% versus 97.4%; p = 0.251). When the early and 1-year patency rates were compared based on the side-arm graft used, there were no differences in patency rates of RITA versus RGEA grafts between the two groups (early, 99.4% versus 100%; p = 1.000; 1-year, 96.5% versus 97.7%; p = 0.724).

Conclusions: Construction of Y composite grafts using the RITA or RGEA showed comparable results including patency rates early and 1 year postoperatively.


   Introduction
Top
 Abstract
 Introduction
Material and Methods
 Results
 Comment
 Discussion
 References
 
Distal flexibility and good long-term patency may be important factors to consider in the selection of the second graft to be used after the left internal thoracic artery (ITA) when performing multivessel coronary artery bypass grafting. Advantages such as enhanced long-term survival and greater freedom from reinterventions with the use of bilateral ITA grafts compared with a single ITA graft for coronary artery bypass grafting have been demonstrated [1, 2]. However, using bilateral ITAs as in situ grafts sometimes does not achieve complete arterial revascularization for multivessel coronary disease. Construction of a Y composite graft further increases the length of the ITA, and allows the extensive use of bilateral ITA grafts to revascularize both the left and right coronary artery systems [3]. Of the other possible arterial conduits, the right gastroepiploic artery (RGEA) has several advantages, such as providing a comparably sized artery-to-artery anastomosis, necessitating no additional incision in the leg or forearm, and histologic similarity to the ITA, which would suggest long-term patency [4–6]. High tendencies to develop vasospasm and competitive flow in moderately stenotic coronary lesions, however, have been indicated as limitations of the in situ RGEA graft [7, 8].

The aims of this study were to compare (1) the early and 1-year patency rates and (2) the clinical results of off-pump coronary artery bypass grafting (OPCAB) using the skeletonized right ITA (RITA) or RGEA as a Y composite graft anastomosed to the side of the in situ left ITA for revascularization of the left coronary artery system between two propensity score–matched groups.


   Material and Methods
Top
 Abstract
 Introduction
 Material and Methods
Results
 Comment
 Discussion
 References
 
The study protocol was reviewed by the institutional review board and approved as a minimal risk retrospective study (approval number H-0608-025-18) that did not require individual consent based on the institutional guidelines for waiving consent.

Patient Characteristics
Between January 2002 and December 2006, 312 patients who underwent OPCAB using arterial Y composite grafts for revascularization of the left coronary artery territory were studied. A skeletonized RITA (n = 177) or RGEA (n = 135) was anastomosed to the side of the left ITA to construct a Y composite graft. Early in this study, both ITAs were preferred for use when possible for revascularization of the left coronary artery territory. If use of bilateral ITAs as a Y composite graft did not achieve complete revascularization in multivessel coronary artery disease, an RGEA or saphenous vein graft was used for additional revascularization. Because average skeletonized right ITA graft lengths were 14 to 16 cm, a third graft was needed in some patients with three-vessel coronary disease. Skeletonized free RGEA grafts were usually longer than right ITA grafts, and were long enough to revascularize all the diseased territories when used as a Y composite graft. Based on the early postoperative patency rates of RGEA composite grafts in our institution, the RGEA was preferred for use in the latter period of this study. These 312 OPCAB patients were 51.5% (312 of 606 patients) of the total number of patients who underwent isolated OPCABs for multivessel disease during the same period. Among these 312 patients, 102 patients receiving RITA grafts (RITA group) and another 102 patients receiving RGEA grafts (RGEA group) were extracted for comparison after propensity score matching. Characteristics of the study population before and after propensity matching analysis are summarized in Table 1. Patients who required a third graft other than the RITA or RGEA to revascularize the left coronary artery territory or who received the Y composite graft to revascularize the right coronary artery territory in addition to the left coronary artery territory were excluded from the study. When the right coronary artery territory was revascularized in addition to the left coronary artery territory in the RITA group, an in situ or free RGEA graft (n = 50) was commonly used. When the right coronary artery territory was revascularized in addition to the left coronary artery territory in the RGEA group, the distal segment of the RGEA was used as a composite graft and the remaining in situ RGEA was used to revascularize the right coronary artery territory (n = 7).


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  		Table 1 Comparison of the Two Groups by Baseline
 
Operative Techniques
Off-pump coronary artery bypass grafting was performed as previously described [9]. The ITA was harvested using a standard skeletonizing technique in all patients. After the ITA was harvested, a short lower extension (3 to 5 cm) of the median incision was made to harvest the RGEA in a skeletonized fashion. The peritoneal cavity was opened and the RGEA was exposed by electrocautery incision of the anterior layer of the greater omentum. Scissors or the tip of the cold cautery device were used to free the RGEA from the accompanying vein and to identify the side branches to the stomach and omentum. All branches were occluded with the use of surgical clips on each side to the stomach and omentum, and were divided by scissors. The RGEA was approached from the posterior aspect of the greater omentum, and dissected in a skeletonized fashion proximally to the pylorus and then leftward two thirds of the distance along the greater curvature of the stomach. Throughout the dissection, the grafts were sprayed with warm diluted papaverine solution to minimize spasm and to prevent desiccation. After systemic heparinization, the grafts were clipped distally. The grafts were then immersed in a 10-mL syringe filled with warm diluted papaverine saline solution (1 mg/mL) and allowed to dilate pharmacologically until use. A Y composite graft was constructed before beginning the distal anastomoses. In most cases when using Y graft construction, the RITA or RGEA was divided at its proximal section and anastomosed to the side of the left ITA in a Y fashion using 8-0 polypropylene continuous suture. After completion of the Y anastomosis, 1 mL of additionally diluted warm papaverine solution (0.5 mg/mL) was intraluminally injected into the distal end of the RGEA to cause pharmacologic dilation. A sequential anastomosing technique was used for additional revascularization in both groups. Protamine was not given at the end of the procedure. The operations were all performed by a single surgeon (K.-B.K.).

Postoperative Follow-Up
All patients halted aspirin therapy (300 mg/d) the day before surgery and resumed it 1 day postoperatively. Perioperative calcium-channel blockers were not commonly used, except when early postoperative angiography demonstrated a spastic graft. Diltiazem oral therapy (≥90 mg/d) was continued for at least 1 year if early postoperative angiography revealed a spastic graft. Early postoperative coronary angiographies (1.8 ± 1.7 days) were performed in 98.0% (200 of 204) of the patients (101 of 102 in the RITA group; 99 of 102 in the RGEA group), and 1-year postoperative angiographies (11.3 ± 2.5 months) were performed in 83.8% (171 of 204) of the patients (87 of 102 in the RITA group; 84 of 102 in the RGEA group), regardless of the patient's anginal symptoms. Patients who died, refused angiographic evaluation, or had renal function impairment were excluded from angiographic follow-up. One physician initially reviewed all coronary angiograms and consensus was reached after review. Graft patency was graded as described by FitzGibbon and associates [10] (grade A = excellent; grade B = fair; grade A + B = patent). Competitive graft flow was defined as distal native grafted coronary artery flow not clearly opacified as seen by graft angiography, but well-visualized retrograde graft flow as seen by native coronary angiography. If the distal graft as well as the native coronary artery was not opacified as seen by graft angiography, it was classified as a grade B anastomosis.

Statistical Analysis
To correct the effect of nonrandomization of this retrospective study and selection bias, propensity score matching analysis was done. To produce propensity scores, we used logistic regression analysis of various preoperative variables (c statistic = 0.745, Appendices A, B). The propensity score included sex, age, height, diabetes mellitus, previous history of stroke, chronic renal failure, left main coronary artery disease, echocardiographic left ventricular ejection fraction, unstable angina, multivessel disease, and saphenous vein graft use. From these covariates, a propensity score was calculated for each patient. Each patient among the patients receiving an RITA composite graft was matched with a patient (1:1) among the patients receiving an RGEA composite graft. From this matching analysis, 102 patients in each group were selected for final analysis (Table 1). For the comparison of continuous variables between the two matched groups, paired Student's t test was done. For the comparison of proportions between the two matched groups, the McNemar test was used. However, for the comparison of the graft patency rates between different numbers of total anastomoses, we used the {chi}2 test. Statistical analysis was performed with SPSS software (SPSS Inc, Chicago, IL). All results were expressed as mean ± standard deviation, and a probability value less than 0.05 was considered statistically significant.


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   Results
Top
 Abstract
 Introduction
 Material and Methods
 Results
Comment
 Discussion
 References
 
The average number of distal anastomoses per patient was higher in the RITA group than in the RGEA group (3.2 ± 0.9 versus 2.7 ± 0.7; p < 0.001). However, the average number of distal anastomoses per Y graft (2.7 ± 0.6 versus 2.6 ± 0.7; p = 0.307) and the average number of anastomoses using the side-arm Y composite graft (RITA or RGEA; 1.6 ± 0.6 versus 1.5 ± 0.6; p = 0.281) were not different between the two groups. When the coronary arteries were classified as the left coronary artery (left anterior descending artery and left circumflex artery) and right coronary artery territories, the number of distal anastomoses for the left coronary artery territories was not different between the two groups (Table 2).


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  		Table 2 Comparison of the Two Groups by Distal Anastomosis (Matched Data)
 
Operative mortalities were 1.0% in the RITA group and 2.0% in the RGEA group (not significant). There were no significant differences in the incidence of postoperative morbidities such as atrial fibrillation, perioperative myocardial infarction, mediastinitis, bleeding reoperation, and stroke between the two groups. No differences were noted in the length of intensive care unit or hospital stay between the two groups (Table 3).


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  		Table 3 Comparison of the Two Groups by Clinical Results (Matched Data)
 
During the 1-year postoperative follow-up, 3 of 201 survivors experienced the recurrence of angina (0 of 101 in the RITA group versus 3 of 100 in the RGEA group; p = 0.079). Of the 171 patients who underwent 1-year follow-up angiography, target-vessel revascularization (RITA group, 0 of 87 versus RGEA group, 2 of 84; p = 0.148) or nontarget vessel revascularization (RITA group, 1 of 87 versus RGEA group, 2 of 84; p = 0.540) was performed in 5 patients (2.9%).

Early Postoperative Angiographies
Early postoperative angiographies demonstrated a 99.4% patency rate in the RITA group and 99.3% patency rate in the RGEA group (not significant; Table 4). There were no significant differences between the two groups in the patency rate of distal anastomoses using a Y composite graft. The patency rates of distal anastomoses using the left ITA (110 of 111 versus 108 of 110) and those using the right ITA or RGEA (162 of 163 versus 153 of 153) were not different between the two groups.


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  		Table 4 Comparison of Early Graft Patency Rates Between the Two Groups (Matched Data)
 
One-Year Postoperative Angiographies
One-year postoperative angiographies demonstrated a 95.4% patency rate in the RITA group and 97.4% patency rate in the RGEA group (p = 0.251; Table 5). There were no significant differences between the two groups in the patency rates of distal anastomoses using a Y composite graft (96.6% versus 97.4%). The patency rates of distal anastomoses using the left ITA (96.9% versus 96.8%) and those using the RITA or RGEA (96.5% versus 97.7%) were not different between the two groups.


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  		Table 5 Comparison of 1-Year Graft Patency Rates Between the Two Groups (Matched Data)
 
Angiographic Comparison of the Anastomotic Qualities Between the Early Postoperative Period and 1-Year After Off-Pump Coronary Artery Bypass Grafting
When we angiographically evaluated the FitzGibbon graft patency grades of the in situ left ITA and composite (RITA or RGEA) grafts, the proportions of grade A and B of the in situ left ITA grafts were similar between the two groups both early and 1 year postoperatively (Table 6). However, the proportion of grade B grafts was higher in the RGEA group (3.5% versus 9.8%; p = 0.049) at 1 year postoperatively. Four of 6 grade B distal anastomoses using the RGEA showed competitive flow patterns early postoperatively. Two of 5 grade B distal anastomoses using the RITA and 8 of 9 grade B distal anastomoses using the RGEA showed competitive flow patterns at 1 year postoperatively.


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  		Table 6 Comparison of the Anastomotic Qualities Between the Two Groups (Matched Data)
 

   Comment
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
Discussion
 References
 
This study demonstrated three main findings. First, revascularization using the RITA or RGEA as a Y composite graft showed comparable early surgical results. Second, the RGEA composite graft angiographically showed comparable patency rates to the RITA composite graft in the left coronary artery territories early and 1 year postoperatively after OPCAB. Third, there were no significant differences in angina recurrence and target vessel revascularization between the RITA and RGEA composite graft groups during the first postoperative year.

Expanded use of arterial grafts for myocardial revascularization is based on data showing superior long-term patency of left ITA grafts compared with saphenous vein grafts. The skeletonized technique for harvesting the ITA allowed additional graft length and easier use of the ITA with favorable results [11, 12], providing the foundation for using bilateral ITA grafts to achieve complete myocardial revascularization. Construction of a Y composite graft further increased the length of the ITA, and allowed the extensive use of bilateral ITA grafts to revascularize the whole myocardium [3]. Although previous studies [12–14] demonstrated that coronary revascularization using bilateral ITAs as Y composite grafts was an effective and safe method for multivessel disease even in patients with diabetes, concerns of increasing perioperative morbidity including sternal infection made surgeons hesitant to use bilateral ITA grafts. Recently, the patency rate of the RITA used as a composite graft for revascularization of the left coronary artery territory was also revealed to be influenced by the severity of native coronary artery stenosis [15, 16].

Based on the superior advantages of the ITA graft, other arteries such as the radial artery, RGEA, inferior epigastric artery, splenic artery, and ulnar artery have been used in myocardial revascularization [7]. The RGEA graft has several advantages that would create the expectation of long-term patency: it is an arterial conduit that enables comparably sized artery-to-artery anastomosis, and it is a splanchnic artery carrying relatively less muscle fibers and fenestrations at the internal elastic lamina than the radial artery [4, 5]. However, a previous study demonstrated significantly lower patency rates of pedicled RGEA composite grafts than those of radial artery grafts, and discouraged the use of RGEA composite grafts [17]. In contrast, Ryu and associates [18] demonstrated satisfactory clinical and early patency results from skeletonized RGEA composite grafts used in situations when bilateral ITA and radial artery grafts could not be used. In the present study, we compared surgical results between skeletonized RITA and RGEA composite grafts for revascularization of the left coronary artery territories, and demonstrated that there were no significant differences in operative results, incidence of postoperative morbidities, and hospital course between the RITA and RGEA composite graft groups.

Encouraged by a previous study demonstrating excellent early and 1-year patency rates of skeletonized in situ RGEA grafts [9], we extended the use of the skeletonized RGEA to the construction of a Y composite graft anastomosed to the left ITA. Previous studies showed that a third graft was required in about 30% of patients when bilateral ITAs were used for complete revascularization of three-vessel disease [3, 19]. However, most of the skeletonized RGEAs used as composite grafts were long enough to reach the whole right and left coronary artery territories without need of a third graft. Although this grafting strategy may not provide the benefits of bilateral ITAs, particularly in nondiabetic patients, it does provide the benefits of total arterial revascularization while preserving sternal blood supply and saving one ITA that can be used in the future. In the present study, there were no differences in patency rates between the distal anastomoses using RITA grafts versus RGEA grafts when used for revascularization of the left coronary artery system. However, when we evaluated the quality of the patent grafts, a tendency toward increased competitive flow pattern (FitzGibbon grade B) of the RGEA grafts was observed during the first postoperative year. When we serially followed up these grade B lesions for 5 years postoperatively, about half of the grade B lesions improved to grade A [20]. This finding was consistent with another study that revealed that new stenosis was uncommon in skeletonized RGEA grafts after 5 years [6]. Additionally, there were no differences in angina recurrence and target vessel revascularization rates during the first postoperative year between RITA and RGEA composite grafts used in OPCAB.

The development of perioperative RGEA graft spasm has been indicated as one of the drawbacks that might cause early graft failure [7, 17, 21]. Experience with ITA skeletonization prompted surgeons to harvest the RGEA in a similar manner to gain the advantages of skeletonization [6, 9, 22, 23]. By using skeletonized RGEA grafts, advantages such as avoidance of early spasm, easy identification of potential bleeders and quality of the vessel, functionally lengthened and larger grafts, ease in performing sequential anastomoses, and preservation of lymphatic and venous drainage to the stomach are expected. Contrary to previous studies demonstrating more frequently spastic RGEA grafts [21, 24, 25], we experienced similar proportions of graft spasm of the in situ ITA (3 of 110 patients; 2.72%) and RGEA composite grafts (4 of 153 patients; 2.61%) in the RGEA group as seen in early postoperative angiographies. We hypothesized that our low incidence of RGEA graft spasm was attributed to the reversal of vasoconstriction by complete removal of all tissue surrounding the RGEA. To prevent perioperative graft spasm, administration of pharmacologic agents such as calcium-channel blockers has also been recommended [7, 18, 25, 26]. Diltiazem oral therapy (≥90 mg/d) was used for at least 1 year if early postoperative angiography revealed a spastic graft.

Another drawback of RGEA grafts was a relatively high incidence of atherosclerotic lesions in patients undergoing coronary revascularization. Although a previous study demonstrated a rare incidence of significant atherosclerotic luminal narrowing in RGEA grafts [27], we frequently observed significant atherosclerotic lesions in patients undergoing coronary revascularization. During the study period, we observed grossly atherosclerotic RGEA grafts in 11 of 59 consecutive patients (18.6%), and discarded the grafts because of severe, multiple atherosclerotic plaques in 6 patients (6 of 59 patients; 10.2%).

There are limitations to the present study that must be recognized. First, the present study was not performed in a prospective randomized manner although propensity matching analysis was adopted. Second, there was larger number of distal anastomoses per patient in the RITA group than in the RGEA group, although the numbers of distal anastomoses for left coronary artery territories were similar owing to the patient selection criteria in this study. Third, a longer follow-up period is required for predicting the long-term fate of a second arterial graft.

In conclusion, construction of Y composite grafts using skeletonized RITAs or RGEAs for revascularization of the left coronary artery territories showed comparable results, including patency rates early and 1 year postoperatively after OPCAB.


   Appendix
 
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   Discussion
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Discussion
References
 
DR JOSEPH F. SABIK (Cleveland, OH): Gastroepiploics are not used very commonly in the United States. I think one of the reasons is it tends to be a small artery and a little bit more difficult to work with. Do you have any specific method of assessing the gastroepiploic artery either intraoperatively or preoperatively to decide whether it is a conduit that you would want to use?

DR CHO: Preoperative abdominal angiography during coronary evaluation or multidetector thoracoabdominal computed tomography was performed to evaluate the celiac axis. If significant narrowing of the celiac axis was found on the preoperative evaluation, we used the RGEA (right gastroepiploic artery) as a composite or free graft, instead of an in situ graft, to avoid possible flow competition that would result in graft failure. Intraoperatively, the RGEA was initially evaluated by manual palpation right after opening the abdomen and then by visual inspection during harvesting using a skeletonized technique. After completion of the Y anastomosis, 1 mL of warm diluted papaverine saline solution (0.5 mg/mL) was intraluminally injected into the distal end of the RGEA to dilate pharmacologically. After this preparation, diameter of the RGEA is usually larger than that of the left ITA (internal thoracic artery).

In our experience of more than 1,000 patients with the RGEA exploration during CABG (coronary artery bypass grafting), 5.9% of the RGEA had multiple or diffuse atherosclerotic lesions that precluded from using as a bypass graft and another 5.3% of the RGEA were unavailable to use as a graft because of their small caliber. Therefore, overall availability of the RGEA as a graft was 88.2%.

DR SABIK: So if I understood you correctly, the gastroepiploic is larger than the ITA?

DR CHO: Yes, I think so.

DR SABIK: I wonder if that is an ethnic thing, because that is not what we see in the United States.

DR CHO: I am not sure; however, we have rice and may have a big stomach. Mostly, the RGEAs were larger in diameter than the ITAs.

DR GIUSEPPE TAVILLA (Leiden, The Netherlands): I have a question for the author and maybe an answer to Dr Sabik. The question is on what clinical criteria did you decide to use either the GEA (gastroepiploic artery) or the ITA, since this was not a randomized study. Maybe you looked at the comorbidities of the patient. In diabetics, for instance, one might prefer to use the GEA instead of using the two internal thoracic arteries to prevent sternal complications.

DR CHO: During the early period of this study, both ITAs were preferred for use when possible for revascularization of the left coronary territory. If use of the bilateral ITAs as a Y composite graft did not achieve complete revascularization in multivessel coronary disease, the RGEA or saphenous vein graft was used for additional revascularization. As the length of skeletonized right ITA was 14 to 16 cm in average, we needed a third graft in some patients with three-vessel coronary disease. The skeletonized free RGEA graft was usually longer than the right ITA, and was long enough to revascularize all the diseased territories when used as a Y composite graft. Based on the early postoperative patency rates of the RGEA composite grafts in our institution, the RGEA was preferred for use in the latter period of this study.

DR TAVILLA: In answer to Dr Sabik, based on my experience with about 1,000 coronary revascularizations using the GEA in Europeans, the gastroepiploic artery is almost always bigger than the ITA when the GEA is skeletonized, intraluminally injected with a vasodilator, and stored in a warm gauze in the abdomen until used. Accurate GEA harvesting is mandatory for a satisfying diameter of the graft.

DR THOMAS SCHWANN (Toledo, OH): I congratulate you on a fine study, and I think this also adds further credibility to the necessity of using arterial grafting in contemporary cardiac surgery. We have a different approach and we utilize radial arteries extensively almost routinely, and the question is, how would you decide between the second ideal arterial conduit? Would it be an RITA, would it be a gastroepiploic, would it be a radial? So that would be question number one.

Number two is, we have found that the incidence of premature arterial graft failure to the right system is higher and potentially equivalent to the vein. Have you found a similar situation with the gastroepiploic?

Thank you.

DR CHO: Thank you. These are very important questions. In choosing a second graft, we actually do not use radial artery graft, because, as you know, the RAPCO study has revealed that radial artery patency is similar to vein graft patencies until 5 years or so. In terms of the right gastroepiploic and right ITA, I already responded to previous question.

Regarding the revascularization of the right coronary territory that had more than 90% stenosis or total occlusion, any kind of revascularization strategies such as in situ RGEA grafting or composite grafting would be good.

In moderate lesion, however, it has still room to be answered. In moderate right coronary lesion of less than 70% stenosis and of no significant perfusion decrease in preoperative myocardial SPECT (single photon emission computed tomography), we usually leave it unbypassed and consider the lesion to be a candidate for hybrid percutaneous revascularization later. Between 75% and 90% stenosis of the right coronary lesion, we go to the composite grafting technique using the RGEA and check the flow using transit time flow measurement in the operating room. If there was suspicious flow completion, we revised it or anastomosed the free RGEA to the side of the ascending aorta after construction of a pericardial aortic patch.

DR SABIK: You obviously have an incredible wealth of knowledge with your angiograms, because you have an early angiogram and then another angiogram at 1 year. I have two questions. One, why did the grafts fail that did fail? Were you able to learn why by the angiograms? And, two, did you have anyone whose grafts were patent but were still having ischemia? There are some suggestions that when you revascularize an entire heart, both the right and left systems, from one ITA that some patients will still have ischemia despite having bypass grafts. I am just wondering if you have seen that at all.

DR CHO: Actually I did not understand the first question.

DR SABIK: From the angiograms, did you have any insight into why your grafts failed? Was it due to competitive flow, was it due to kinking? Any ideas as to why they failed?

DR CHO: Regarding the technical failure, actually that is why we do the early immediate postoperative angiogram, to prevent any technical errors before we discharge the patient. As you know, the group with all patent grafts had better survival than those with one or more occluded grafts.

We performed reoperations according to the early postoperative angiographic findings; because most technical errors were detected by intraoperative flowmeter measurement and were revised, reoperations in the study period were mostly related to graft trunk problems such as delayed dissection of the arterial graft trunk, graft trunk kinking, localized thrombus around damaged intimal area, or composite graft stenosis. Reoperations due to distal anastomotic occlusion of arterial grafts were quite uncommon.

For the second question, if the graft is patent and still the patient has ischemia, it can be presented as hypoperfusion syndrome at immediate postoperative period, even in the operating room. In such case, we added a saphenous vein graft to that territory based on intraoperative transesophageal echocardiographic findings. After the immediate postoperative period, as we published in the Journal of Thoracic and Cardiovascular Surgery using the single photon emission computed tomography (SPECT) study, there was no difference in perfusion improvement between the Y composite and bilateral in situ ITA grafts in terms of the reversibility score.

The reversibility scores were significantly improved at postoperative month 3 and at 1 year in both groups of Y composite and bilateral in situ ITA grafts, when compared with the preoperative values. The scores approached zero at 1 year postoperatively, suggesting almost complete recovery of myocardial stress perfusion by the first postoperative year.


   References
Top
 Abstract
 Introduction
 Material and Methods
 Results
 Comment
 Discussion
 References
 

  1. Buxton BF, Komeda M, Fuller JA, Gordon I. Bilateral internal thoracic artery grafting may improve outcome of coronary artery surgery: risk-adjusted survival Circulation 1998;98(19 Suppl):II 1-II 6.[Medline]
  2. Lytle BW, Blackstone EH, Loop FD, et al. Two internal thoracic artery grafts are better than one J Thorac Cardiovasc Surg 1999;117:855-872.[Abstract/Free Full Text]
  3. Calafiore AM, Contini M, Vitolla G, et al. Bilateral internal thoracic artery grafting: long-term clinical and angiographic results of in situ versus Y grafts J Thorac Cardiovasc Surg 2000;120:990-998.[Abstract/Free Full Text]
  4. Mills NL, Everson CT. Right gastroepiploic artery: a third arterial conduit for coronary artery bypass Ann Thorac Surg 1989;47:706-711.[Abstract/Free Full Text]
  5. van Son JA, Smedts F, Vincent JG, van Lier HJ, Kubat K. Comparative anatomic studies of various arterial conduits for myocardial revascularization J Thorac Cardiovasc Surg 1990;99:703-707.[Abstract]
  6. Suma H, Tanabe H, Takahashi A, et al. Twenty years experience with the gastroepiploic artery graft for CABG Circulation 2007;116(Suppl 1):I-188-I-191.[Abstract/Free Full Text]
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