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Ann Thorac Surg 2005;80:2098-2105
© 2005 The Society of Thoracic Surgeons
a Department of Cardiovascular Surgery, Shin-Tokyo Hospital, Chiba, Japan
b Department of Cardiovascular Surgery, Sakakibara Heart Institute, Tokyo, Japan
Accepted for publication June 3, 2005.
* Address correspondence to Dr Fukui, Department of Cardiovascular Surgery, Shin-Tokyo Hospital, 473-1 Nemoto, Matsudo City, Chiba 271-0077, Japan (Email: tm-fukui{at}gem.hi-ho.ne.jp).
| Abstract |
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METHODS: Two hundred and fifty patients were treated with an extended LAD reconstruction, with or without endarterectomy, as part of coronary artery bypass grafting to achieve complete revascularization. The left internal thoracic artery (LITA) was used to reconstruct the LAD in all patients. There were 197 men and 53 women. The mean age was 65.1 ± 9.0 years. Coronary artery reconstruction was performed without endarterectomy in 183 patients (73.2%) and with endarterectomy in 67 patients (26.8%). The off-pump technique was used in 204 patients (81.6%).
RESULTS: The operative mortality was 1.6%. Perioperative myocardial infarction was observed in 6.4% of the patients. The mean LAD incision length was 4.3 ± 1.7 cm. The patency rate of the LITA to LAD was 98.6% by early angiographic examination (mean, 7.5 ± 2.6 postoperative days). There were 3 late cardiac-related deaths at a mean follow-up of 21.2 ± 10.7 months. The actuarial survival was 92.0% at 45 months. Freedom from death or cardiac events was 88.1% at 45 months.
CONCLUSIONS: Coronary artery reconstruction, with or without endarterectomy, using the left internal thoracic artery for a diffusely diseased LAD can be performed with acceptable early and midterm results.
| Introduction |
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Previous experience with coronary endarterectomy for diffusely diseased coronary arteries has been limited due to poor clinical results in the early years [35]. More recently, however, the benefits of LAD endarterectomy have been gradually recognized because surgical techniques and technologies have evolved [6, 7]. Furthermore, coronary artery reconstruction with an exclusion of plaque has also been performed for diffusely diseased LAD [8]. The greatest advantage to a combined endarterectomy and coronary artery reconstruction is the fact that the myocardium supplied by the side branches of a diffusely diseased LAD can be relieved of ischemia. This advantage cannot be obtained from a conventional graft to the distal LAD alone since this is beyond the diffusely diseased segments. The purpose of the present retrospective study was to review the early and midterm clinical efficacy of our modified technique of long segmental coronary artery bypass grafting (LS-CABG), with or without endarterectomy, for a diffusely diseased LAD using the LITA.
| Patients and Methods |
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Indications for LS-CABG
The LS-CABG was defined as CABG using a segmental anastomosis that was greater than 2 cm in length. Basically, we performed LS-CABG with the principle that the diffusely diseased LAD and its side branches (septal perforators and diagonal branches) that were affected by severe atheromatous plaque should be relieved of ischemia. We performed LS-CABG when a simple anastomosis to the distal LAD was not possible because of diffuse lesions. Even when the distal LAD and its diagonal branches could technically be grafted with a standard anastomosis, a LS-CABG was performed when proximal septal perforator branches would be left isolated from the graft by other disease. The indications for LS-CABG were not influenced by a prior anteroseptal myocardial infarction. We did not perform a LS-CABG in cases with severely limited runoff to the LAD and poor anteroseptal viability as evaluated by echocardiography. The LS-CABG was not performed in cases with a large territory of akinetic or dyskinetic anteroseptal wall.
The LADs were treated in two ways: LS-CABG with plaque exclusion (without endarterectomy) or with endarterectomy. Plaque exclusion was primarily used to treat a diffusely diseased LAD. When stenotic lesions of the LAD were more predominant and severe, endarterectomy rather than plaque exclusion was the preferred technique. The choice between endarterectomy and plaque exclusion was based on both preoperative angiography and our intraoperative impression. Endarterectomy was scheduled for patients with diffusely diseased distal vessels where the luminal diameters were judged to be smaller than 1 mm on preoperative angiography. In these patients, the length of the diffusely diseased segment was almost always longer than 3 cm. There were no cases of severely limited distal runoff in any of the patients reported here. We often made an intraoperative decision to perform endarterectomy in a LAD that had a severely calcified plaque, a long hard fibrous plaque, or a long soft plaque. In the latter case, we felt that plaque exclusion should not be performed in order to avoid distal embolism due to plaque rupture.
Surgical Technique
All types of coronary artery reconstruction were performed manually. A skeletonized LITA was utilized to reconstruct the LAD in all patients. An ultrasonic scalpel (Harmonic Scalpel, Ethicon Endosurgery, Cincinnati, OH) was used to harvest the LITA.
LS-CABG With Plaque Exclusion (Fig 1). The length of the diseased segments to be incorporated by the plaque exclusion anastomosis was ultimately decided during the operation. The arterial incision was made distally in a segment of the LAD that was superficially intact and extended proximally and distally. When a lesion continued to an intramyocardial part of the LAD, the LAD was dissected out with an ultrasonic scalpel until the proximal end of the diffuse plaque was reached. The distal arteriotomy was extended to the nondiseased portion of the LAD. The average length of an arteriotomy was 3.8 ± 1.3 cm (range, 2 to 8 cm). After incising the LAD, the LITA was longitudinally incised adjusting the hood to the length of the incised LAD. The LITA was anastomosed with several 7-0 and 8-0 polypropylene sutures using a running technique. Several sutures were used, tying them end to end in order to avoid a purse string effect. Needles were carefully inserted into the intact intima avoiding plaque rupture as much as possible, and the suture lines were placed on the insides of the plaques, so that the plaques were excluded from the lumen. The majority of the reconstructed lumen consisted of intact intima of the LITA graft. A total of 183 patients (73.2%) underwent coronary artery bypass using this technique.
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Postoperatively, anticoagulation was performed with a strict protocol. Intravenous heparin, low-dose aspirin (100 mg/day), and ticlopidine (200 mg/day) were used in patients undergoing coronary reconstruction with plaque exclusion. Intravenous heparin was stopped at postoperative day 3 and ticlopidine was continued for 3 months. Intravenous heparin, low-dose aspirin (100 mg/day), and warfarin (maintained with target international normalized ratio of 2.0) were used in patients undergoing endarterectomy. Intravenous heparin was continued until warfarin was effective. After 3 months, the administration of warfarin was stopped. Aspirin was continued indefinitely in all patients.
Follow-Up
Medical records were reviewed to ascertain the mortality and morbidity of each patient. Postoperative complications included the following: myocardial infarction (new Q waves in the electrocardiogram or creatine kinase MB > 10%), low cardiac output (a newly placed intraaortic balloon pump or the use of dopamine or dobutamine at doses over 5 µg/kg/minute), atrial fibrillation, ventricular tachycardia or fibrillation, bleeding requiring reexploration, stroke, respiratory failure (intubation time over 48 hours), renal failure, and mediastinitis.
Midterm follow-up was achieved by direct communication with the patient, family, attending physician, or a combination of these. Survival and any cardiac events (recurrent angina, myocardial infarction, congestive heart failure, reintervention, or reoperation) were assessed.
Angiographic Study
Postoperative angiography was performed to check for graft patency in all patients from whom informed consent could be obtained. This was performed before their discharge at 4 to 21 days (mean, 7.5 ± 2.6 days) after the operation. Early postoperative angiography was performed in 212 patients (84.8%) in this study. Interim angiography was also performed in 54 patients (21.6%) at a mean follow-up period of 15.2 ± 7.1 months (range, 3 to 30 months). In all angiographic examinations, the patency of the grafts as well as the reconstructed LAD and its side branches were evaluated.
Statistical Analysis
Continuous variables are reported as means ± standard deviations. Continuous variables were compared using the Student's t test. Discrete variables were compared using the
2 test or Fischer's exact test. Actuarial survival and event-free survival curves were estimated by the Kaplan-Meier method. The log-rank test was used to assess whether there was a difference in survival between subject groups. Differences were considered statistically significant at a p value less than 0.05. Statistical analyses were performed using the StatView 5.0 software package (SAS Institute, Cary, NC).
| Results |
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Postoperative early angiography was performed in 212 (84.8%) patients. The LITA and LAD (including side branches) were completely patent without stenosis in 209 patients (98.6%). The LITA was patent in all patients. However, occlusion of the distal LAD was observed in 3 patients. In these 3 patients, diagonal branches and septal perforators provided runoff to the patent LITA. Percutaneous coronary intervention (PCI) to the LAD was performed in one patient.
We also compared the early results of coronary artery reconstruction with endarterectomy to those without endarterectomy (Table 1). The preoperative characteristics were similar between the two groups. The mean number of anastomoses per patient was not significantly different between the groups (p = 0.32). However, the mean length of LS-CABG with endarterectomy was significantly longer than that of LS-CABG with plaque exclusion (p < 0.0001). The operating time with endarterectomy was also longer (p < 0.0001). The requirement for blood transfusion and the rate of reexploration due to bleeding were greater in the endarterectomy group (p < 0.05). The rate of perioperative myocardial infarction was significantly higher with endarterectomy (p = 0.0003). While there was a difference in surgical mortality between the groups, it did not reach a statistically significant level (p = 0.06).
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| Comment |
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Diffusely diseased coronary arteries have been treated with endarterectomy from the beginning of coronary artery surgery [9]. Results from early series of endarterectomy were not satisfactory [35]. However, the early and late results of more recent series with endarterectomy have been acceptable because of the development of new techniques and technologies in coronary surgery [6, 7]. Furthermore, recent series have shown endarterectomy to be safe when performed with the off-pump technique [10]. We have performed LS-CABG with or without endarterectomy safely and effectively in 204 patients (81.6%) using the off-pump method. Our current series includes previously reported patients [11]. Other investigators have noted that coronary collaterals offer protection against myocardial infarction during off-pump surgery [12]. We think that a severe diffusely diseased LAD can stand longer ischemic times because significant collaterals have developed in this situation. We used an open method for endarterectomy (long arteriotomy and total removal of plaque under direct visualization) and reconstruction of the LAD was performed using the LITA with a matched length arteriotomy in all patients [13]. The traction-countertraction method through a small arteriotomy was not performed due to several possible disadvantages [14] including the following: (1) diagonal and septal perforator branches may be torn off in spite of gentle traction; (2) the distal end of the lumen may be occluded with thrombus or dissection because of insufficient endarterectomy. The openings of the side branches and the distal end of the LAD can be directly observed and confidently endarterectomized with the open method. The adventitial surface left by the endarterectomy was cleaned with saline irrigation in order not to cause distal embolization. We preferred using the LITA for reconstruction rather than a saphenous vein graft because of the superior patency rate of the LITA [2]. The potential disadvantage of hypoperfusion when using the LITA [15] was not observed in our patients. We believe that skeletonization of the LITA graft may optimize vasodilation and prevent hypoperfusion.
Coronary artery reconstruction with plaque exclusion is another method used to treat a diffusely diseased LAD. Barra and his colleagues [8] previously reported this method and the results were excellent. We adopted their method with some modifications as follows. First, the over and over running suture rather than the U-shaped running suture was employed, because we thought that the over and over suture was easier than the U-shaped suture. We were careful not to disrupt the plaque with the needle and suture using the over and over suture technique. Second, a small endarterectomy for calcified plaques was not performed in our patients. Instead we used a long arteriotomy because plaques were not segmental but continuous in the diffusely diseased LAD, and atherosclerosis was especially advanced in a vessel that contained a calcified plaque [16]. Finally, we thought that a long endarterectomy with patch closure was easier and safer than a local endarterectomy with intimal fixation.
The major causes for suboptimal results after coronary endarterectomy are related to triggering of the coagulation cascade by the lack of endothelium in the early stages and myofibro-intimal proliferation in the late stages [17, 18]. We agree that endarterectomy should be avoided if possible because the rate of postoperative myocardial infarction after endarterectomy was higher than that after LS-CABG with plaque exclusion in our study (p = 0.001). Moreover, the rate of transfusion and reexploration for bleeding were higher after endarterectomy. However, this fact may be related to the higher use of cardiopulmonary bypass in the endarterectomy group. On the other hand, we believe that when severe diffusely diseased continuous plaques with calcification, soft large plaques, or hard fibrous plaques are found, they should not be treated by either a simple distal anastomosis or the plaque exclusion method (7.9% of total CABG patients). We think that endarterectomy is the only revascularization method for these complex vessels despite the fact that the endarterectomy group had more perioperative complications. Either LS-CABG with plaque exclusion or LS-CABG with endarterectomy was chosen during the operation according to the severity of the lesion. We also believe that an unexpected severe diffusely diseased lesion that cannot be treated with simple bypass grafting may be encountered during any operation. Even retrospectively, we cannot identify all of the inoperable vessels from the preoperative angiograms alone.
In our study, the overall surgical mortality (1.6%) was lower than that of other reported LAD reconstruction studies [7, 8, 1921]. Furthermore, our observed early mortality for LS-CABG without endarterectomy (0.5%) was better than that of isolated CABG from a recent high volume series (2.7%) [22]. Although the early mortality for LS-CABG with endarterectomy (4.5%) was higher than that of LS-CABG without endarterectomy, this result was not statistically significant (p = 0.06). Moreover, the late survival was similar between these groups. This result is similar to that of other LAD endarterectomy studies [7, 1921]. In this study, operating time, transfusion rate, reexploration due to bleeding, and POMI were all significantly higher for endarterectomy patients. This may be related to the greater use of cardiopulmonary bypass and the lesion severity in the endarterectomy group. However, the perioperative morbidity had no influence on either early mortality or late survival. The patency of both the LITA and LAD (98.6%) by early postoperative angiography was excellent and compares favorably with reported series of standard LITA to LAD anastomoses. Our study revealed acceptable early and midterm results of LS-CABG with or without endarterectomy.
Study Limitations
The limitations of this clinical study are as follows: (1) the number of patients in the study was small and the length of clinical follow-up was only 21.2 months; (2) although 84.8% of patients had early postoperative angiography, follow-up angiography was obtained in only 21.6% of patients; (3) this is a retrospective observational study and was not randomized. Finally, because there is no control group, we cannot conclude that LS-CABG, with or without endarterectomy, is superior to conventional CABG in diffusely diseased LADs. Moreover, because the LAD lesion severity was different between the two groups and was used to determine the surgical methods, we cannot conclude that one method is superior. We believe that each method should be chosen according to the severity of a given lesion.
Conclusion
The LS-CABG, with or without endarterectomy, using the LITA for a diffusely diseased LAD can be performed with acceptable early and midterm results. The LS-CABG technique with plaque exclusion was especially safe as performed in this series. These results are comparable with the results of conventional CABG without a diffusely diseased LAD.
| Acknowledgments |
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| References |
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