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Ann Thorac Surg 2004;78:1304-1311
© 2004 The Society of Thoracic Surgeons
a Department of Cardiovascular Surgery, National Cardiovascular Center, Osaka, Japan
Accepted for publication March 30, 2004.
* Address reprint requests to Dr Tagusari, Department of Cardiovascular Surgery, National Cardiovascular Center, 5-7-1 Fujishirodai, Suita, Osaka 565-8565, Japan
otagusar{at}hsp.ncvc.go.jp
Presented at the Thirty-ninth Annual Meeting of The Society of Thoracic Surgeons, San Diego, CA, Jan 31–Feb 2, 2003.
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Abstract |
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METHODS: Of 382 consecutive patients who underwent off-pump coronary artery bypass between April 2000 and December 2002, 235 patients (193 men and 42 women, mean age 66 ± 9 years) with three-vessel disease underwent off-pump coronary artery bypass with all arterial grafts. A total of 872 vessels were bypassed (average number of grafts 3.7 ± 0.8). The internal thoracic arteries, radial arteries, and gastroepiploic arteries were used for revascularization of 306, 542, and 24 coronary arteries, respectively. Two hundred twenty-five patients underwent revascularization with composite grafts that were connected to the in situ internal thoracic artery (Y configuration 181, I configuration 55, K configuration 27, X configuration 3, T configuration 1); 10 patients underwent revascularization with all in situ grafts.
RESULTS: Three (1.3%) hospital deaths and 1 late death occurred. There were no occurrences of clinical underperfusion syndrome or new intraaortic balloon pump insertion. Cerebral infarction occurred in 2 patients (0.8%). Early postoperative angiography was performed on 833 grafts in 223 patients (95%); the overall patency rate was 98%. Stratified by coronary distribution, the patency rate was 99% (218/221) in the left anterior descending artery, 97% (84/87) in the diagonal artery, 99% (70/71) in the obtuse marginal artery, 98% (262/268) in the posterolateral artery, 98% (167/170) in the posterior descending artery, and 100% (16/16) in the right coronary artery.
CONCLUSIONS: Total arterial off-pump coronary artery bypass yielded good clinical results and an excellent patency rate of revascularization for the total coronary system.
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Introduction |
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Material and Methods |
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Because possible stenosis of the subclavian artery and celiac artery may be a cause of concern, we routinely evaluate by preoperative imaging such as computed tomography, magnetic resonance angiography, or angiography.
Preparation of the Conduits
A conventional, semiskeletonized method was used for the dissection of the ITAs. The RA was harvested from the nondominant arm using an ultrasonic dissection technique [5]. All arterial conduits were wrapped in a sponge soaked with a solution of papaverine hydrochloride. After administration of heparin (1.5 mg/kg), the arterial grafts were divided. A mixture of blood and a solution of papaverine hydrochloride was gently injected into the lumen of the RA to prevent spasm. The left internal thoracic artery (LITA) was generally used for revascularization of the LAD, or blood source of the RA as various configurations of the composite graft. When the GEA was harvested, it was used as an in situ graft to the posterior descending (PD) or/and posterolateral (PL) artery. The right internal thoracic artery (RITA) was anastomosed to the LAD as an in situ graft or connected to the RA for extension as an I or Y graft. Y configuration was the most common composite graft for multivessel revascularization. A K configuration was used when the diagonal branch (DG) ran parallel to the LAD. The advantage of the K graft is that it spares the length of RA, because a long RA segment is required to avoid kinking when the RA is used as a Y composite graft sewn on the DG that runs parallel to the LAD in a side-to-side fashion (Fig 1). With this K graft, the other end of the RA extends to the PD with a few side-to-side anastomoses (Fig 2). Sequential bypass of the LITA to DG and the LAD was also performed in our series. However, side-to-side anastomosis between the LITA and the DG is technically demanding on the beating heart when the LITA is small. As for the X graft, the RA can extend fully around the heart from the DG to the right coronary artery (Fig 3). All composite grafts except the I configuration were arranged before the distal anastomoses. In the I configuration, the RA was connected to the RITA after the distal anastomoses to adjust the length of the RITA.
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Angiographic Study
In 223 (94.9%) patients, informed consent was obtained and follow-up angiography was performed before hospital discharge by cardiologists. By means of the Cardiovascular Measurement System (QCA-CMS, version 4.1; Medical Imaging System, Leiden, The Netherlands), the stenotic percentage of anastomosis was calculated by comparing the diameter of anastomosis with that of the proximal portion of the graft at the view of the minimum lumen. A percentage stenosis of less than 50% was assessed to be patent [6, 7].
Data Collection and Follow-up
We retrospectively reviewed the data from the operation notes, anesthesia records, clinical histories, laboratory investigations, and cardiac catheterization. This retrospective study was approved by the Internal Review Board of the National Cardiovascular Center. Follow-up data were collected from the medical records of outpatient visits and correspondence with referring physicians. All clinical characteristics were accumulated as a computerized database and analyzed.
Statistical Methods
All values are expressed as the mean ± standard deviation. The discrete variables were analyzed with the Fisher's exact test between two groups and Kruskal-Wallis rank test for more than three groups. Scheffé's test was performed when a significant difference was recognized in the results of the Kruskal-Wallis test. All statistical analyses were performed using the software package SPSS 10.0 for Windows (SPSS Inc, Chicago, IL). The differences were considered statistically significant when the p value was less than 0.05.
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Results |
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Unilateral ITA was used in 127 patients (54.0%) and bilateral ITA in 108 patients (46.0%). The RA was used as a composite graft in 232 patients (98.7%) and the GEA was used as an in situ graft in 16 patients (6.8%). Y, I, K, X, or T configuration was used for the RA composite graft in 181, 55, 27, 3, and 1 patients, respectively. Revascularization with all in situ grafts was performed in 10 patients for 40 distal anastomoses.
Angiographic Study
The patency rates according to coronary distribution, graft materials, and anastomotic fashions are shown in Table 2. The patency rates according to the configurations of the composite graft are also shown in Table 3. The overall patency rate was 98.1% (817/833). Stratified by coronary distribution, the patency rate was 98.6% in LAD, 96.6% in DG, 98.6% in OM, 97.8% in PL, 98.2% in PD, and 100% in the right coronary artery. The patency rate was 98.7% with the LITA, 95.9% with the RITA, 98.5% with the RA, and 88.0% with the GEA. The patency rate was 97.6% with the end-to-side fashion and 98.9% with the side-to-side fashion. The patency rate with GEA was significantly lower than that of the other graft materials (LITA versus GEA, p = 0.001; RA versus GEA, p < 0.001). However, no significant changes were noted in the patency rates between coronary distribution (p = 0.846), anastomotic fashion (p = 0.197), and the configuration of the composite graft (p = 0.779).
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Evident flow competition was observed in 36 patients. Of those, 24 RA composite grafts and 12 of the LITA distal from the anastomotic site of the composite graft to the target coronary artery were not opacified in angiography of the in situ graft, although the target coronary artery and its anastomotic site were clearly opacified in the native coronary angiography.
Early and Late Mortalities and Morbidities
Table 4 lists the early and late complications. Early death occurred in 3 patients (1.3%) due to intracranial bleeding, aspiration pneumonia, and intestinal hemorrhage. Perioperative myocardial infarction (new Q waves in electrocardiogram [ECG], creatine kinase-MB [CK-MB] more than 50 with ECG change or CK-MB more than 70 without ECG change: normal value less than 11 IU/L in our institute) occurred in 6 patients (2.6%). Two patients had a stroke during rehabilitation, one of which occurred during the postoperative angiographic study. No clinical underperfusion syndrome was noted and new intraaortic balloon pump insertion was not necessary.
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Comment |
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Our standard technique to achieve total arterial revascularization for total coronary system is the RA composite graft in combination with one or both ITAs. The RA is used as a material for the free arterial graft because of its easier harvesting and handling. The distal sequential bypass to the coronary arteries, a thicker wall, and wider lumen compared with ITA and GEA allow meticulous anastomosis on the beating heart.
The composite graft technique appears to have advantages over the free graft that is anastomosed to the ascending aorta. First, aorta no-touch OPCAB using a composite graft reduces the incidence of neurologic complications [9, 10]. Second, a composite graft makes more efficient use of the conduit by placing the inflow close to the target coronary arteries [10–12]. Finally, the inflow of the ITA does not expose the free arterial graft to high wall stress, which may cause the early development of intimal hyperplasia [13, 14].
The composite graft technique has the pitfall of total dependence of the coronary bypass flow on the flow of the proximal ITA. We routinely evaluate the subclavian artery and the ITA by preoperative angiography, magnetic resonance angiography, or three-dimensional computed tomographic angiography, because stenosis of the proximal ITA or subclavian artery may be a cause of global ischemia. However, the adaptability of the ITA as a blood source of the arterial composite graft is still a potential risk in this technique. Multiple clinical and experimental studies have examined the suitability of the ITA as a blood source of the arterial composite graft [15–21]. From the results of positron emission tomography, Sakaguchi and colleagues [18] documented that the composite Y graft was not as effective as independent grafts for improving the coronary flow reserve soon after bypass grafting. However, most investigations have reported that the flow reserve of the proximal ITA is sufficient for a blood source of composite graft for multiple coronary revascularizations. Indeed, in the present series, there was no hypoperfusion syndrome or need for new intraaortic balloon pump insertion even in the patients whose total coronary artery system was supplied by single ITA.
In general, hypoperfusion syndrome related to the conventional CABG occurs typically 30 to 40 minutes after discontinuation of a cardiopulmonary bypass [22]. It is conceivable that the reactive hyperemia of the myocardium that presents after removal of the aortic clamp [23–25] may require greater conduit flow while the oxygen debt is repaid. This situation might produce a drastic imbalance between graft flow and myocardiac demand, resulting in the hypoperfusion syndrome [17, 26]. In our standard technique, the LAD is revascularized at first by the ITA because it is the most important coronary artery and exposure of the LAD has no major hemodynamic consequences [27]. After revascularization of the LAD, the coronary artery was anastomosed in the order of the diagonal, obtuse marginal, and posterolateral to posterior descending arterial branches with only local ischemia of the target vessel. We predicted that these techniques, which avoid intraoperative global myocardial ischemia, contributed at least partially to avoiding the hypoperfusion syndrome in our patients.
The competitive flow between the native coronary artery and bypass graft is another concern in any composite graft attached to the ITA [28]. This phenomenon was induced by graft–recipient artery mismatch. In 38 patients with composite grafts, the target coronary artery and its anastomotic site were clearly opacified in the native coronary angiography, although the bypass graft to the target coronary artery (ie, the composite graft or the distal ITA of the composite bifurcation) was not opacified in angiography of the in situ graft. Diffuse narrowing of the distal LITA, from the anastomotic site of the composite graft, was recognized in 13 patients who had competitive flow in the distal LITA to the LAD. No definite conclusion has been reached concerning the relationships between the competitive flow, diffuse narrowing, and true graft failure [29–33]. It still remains to be determined whether a particular coronary artery with a noncritical lesion should be grafted prophylactically using the arterial graft for future progression [34]. We prefer to graft to a coronary artery with moderate stenosis in a side-to-side fashion, and the termination of this conduit was to the coronary artery of severe stenosis. When the posterior descending coronary artery had only mild stenosis, we anastomosed the side of the I composite graft to that branch and the end of the I composite graft to the circumflex branches. In our study, no patient with competitive flow of bypass grafts was readmitted for angina or congestive heart failure. Although late follow-up angiography was performed in only 2 cases with competitive flow of the RA composite graft, the RA was patent at more than 1 year after the operation [10]. These results prompted us to conclude that the RA has potential as a physiologically functional arterial graft that can be recruited on demand with progression of the native coronary artery disease.
In conclusion, the total arterial OPCAB for the total coronary system achieved excellent patency in the early postoperative period and showed good clinical results. These results have prompted us to continue performing complete arterial revascularization, although long-term studies are required to provide evidence of the validity of our technique.
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Discussion |
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DR TAGUSARI: I usually use a diamond anastomosis technique for the radial artery and a parallel fashion for the ITA and GEA.
DR HITOSHI HIROSE (Cleveland, OH): We performed a similar study for patients with three-vessel disease undergoing off-pump CABG and published the results in Surgery last year. Off-pump CABG provided excellent results compared with on-pump CABG and the angiographic results were competitive, as you reported today. I have several questions for the authors. First, what are the inclusion and exclusion criteria for total arterial off-pump CABG? Although the authors stated total arterial bypass is the goal for cardiac surgery, only 52% of the patients received total arterial bypass; what kind of bypass was performed in the rest of 48%? Were they received saphenous vein grafts? How do you select patients undergoing total arterial bypass? Second, only 3% of patients received a gastroepiploic artery graft. Why are the authors not using the gastroepiploic artery?
Thank you.
DR TAGUSARI: I did not include one- and two-vessel disease in this study. All the patients had three-vessel disease. The rate of complete revascularization is 100% in this series. And the next question. The size of the GEA varies; sometimes it was too small to use as a sequential bypass graft. However, recently we have used skeletonized GEA using an ultrasonic scalpel to facilitate visual inspection. We only used saphenous vein graft for the patients more than 80 years old or the patients whose radial artery was not adequate to use, such as chronic renal failure.
DR SMITH: To that question also, I think 52% was the number of patients who received OPCAB out of the total, not the percent that had total revascularization.
DR CHARLES BRIDGES (Philadelphia, PA): I have a couple of questions. One is how soon after surgery did you perform the angiogram? I know you showed one slide where it was performed two days after the operation. Another question I had was how you manage your radial artery patients after the operation, are you using nitrates, calcium blockers, and for how long are you using them? Finally, I wanted to learn a little bit more about the patient characteristics. How sick were your patients? What kind of ejection fractions did they have and how much other comorbid disease did they have? I didn't hear that or see that in your abstract, to get an idea of what kind of results we should expect. And then can you help us with the theory behind composite grafting as opposed to taking, say, a radial artery off the aorta or off of a patch of vein, et cetera, from the aorta? What is the evidence that shows us that composite grafting is theoretically superior to the more routine way, even with arterial grafts? Obviously one reason is that with a composite graft you can graft more territory than you could with just taking things off the aorta. But I was wondering if you could comment on your feeling about that.
DR TAGUSARI: We usually perform postoperative Angiography ten to fourteen days after operation. To avoid spasm of the radial artery, we use intravenous diltiazem or nicardipine until the following morning. Since then, a calcium blocker such as amlodipine has been prescribed for a long time because most of the patients have hypertension. As I have showed on the slide. In 17% of the patients, ejection fraction was less than 35% Long-term follow-up is waiting for evidence that the composite graft is superior to the coronary graft. But, when the radial artery is anastomosed directly to the aorta, it is exposed not only to high blood pressure but also to higher shear stress, which may cause the early development of the intimal hyperplasia. Additionally, we can perform aorta no-touch technique and spare the length of the radial artery and by using as a composite graft.
DR AYHAN OZDEMIR (Bursa, Turkey): The patients you had with low ventricular function, what happened after you did the coronary bypass surgery off-pump? Did their left ventricular function get better or stay the same or worse?
Thank you.
DR TAGUSARI: After the OPCAB, left ventricular function recovered significantly in most cases.
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