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Ann Thorac Surg 1999;68:399-404
© 1999 The Society of Thoracic Surgeons
a Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
Address reprint requests to Dr Sundt, Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, Suite 3106 Queeny Tower, One Barnes Hospital Plaza, St. Louis, MO 63110
e-mail: sundtt{at}msnotes.wustl.edu
Presented at the Forty-fifth Annual Meeting of the Southern Thoracic Surgical Association, Orlando, FL, Nov 1214, 1998.
| Abstract |
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Methods. Between October 1, 1993, and September 1, 1998, 649 patients aged 30 to 85 years (mean, 60 ± 10 years) had primary coronary artery bypass using an ITA and radial artery in a T-graft configuration. Left ventricular function was severely depressed (ejection fraction <35%) in 12%, and left main stenosis was present in 14%.
Results. A total of 937 distal anastomoses were performed with the left ITA (1.4 per patient) and 1,452 with the radial artery (2.2 per patient). There was one perioperative death (0.2%). There were 32 (5%) q-wave myocardial infarctions, and 14 patients (2%) had transient low output syndrome. There was one episode of hypoperfusion corrected by lengthening the left ITA. Angiography for clinical indications in 27 patients 1 to 35 months postoperatively (mean, 9.5 ± 8.3 months) demonstrated a distal anastomotic patency of 100% for ITA and 82% for radial artery grafts.
Conclusions. Complete arterial revascularization can be achieved with an ITA and radial artery T-graft with low operative risk and acceptable early patency. These results support the continued investigation of this grafting strategy.
| Introduction |
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Complete arterial revascularization can be achieved in most patients by proximal anastomosis of the radial artery (RA) to the side of the ITA in a T-graft configuration. This procedure is technically complex, however, and makes the entire revascularization dependent on the proximal ITA. Although the aim of this procedure is to improve long-term results, the short-term risks must be defined. We reviewed our entire first 5 years experience with this grafting strategy.
| Patients and methods |
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Patient selection
Initially, this grafting strategy was applied in younger patients and in those for whom conduit was limited in availability. With experience, however, T-grafts have become our grafting strategy of choice for patients younger than 75 years. In the senior authors practice, 116 of 153 (76%) of patients who had isolated primary CAB in the last 12 months of the study received an ITA and RA T-graft. No attempt is currently made to reserve this procedure for low-risk patients. As shown in Table 1, the incidence of female sex, diabetes mellitus, hypertension and hypercholesterolemia, left main coronary artery stenosis, and severely depressed left ventricular function (ejection fraction
35%) are similar to those in other series of primary CAB [2, 4]. This strategy has been used occasionally in association with other procedures (Table 2), although most patients in this series had isolated CAB.
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Our technique of myocardial protection has evolved and now entails the use of tepid antegrade blood cardioplegia in almost all cases. Retrograde delivery is used selectively, in less than 5% of cases.
The RA is harvested routinely by a surgical assistant simultaneously with preparation of the ITA. For expediency we prefer to use the left RA regardless of hand dominance. Recently we have used ultrasonic dissection for this purpose. Preoperative assessment of the palmar arch is done routinely with an Allen test alone. Early in our experience we insisted on ulnar filling of the entire hand in less than 5 seconds. As we have gained confidence and experience we have accepted delays up to 10 seconds without evidence of postoperative compromise. Digital plethysmography is done in questionable cases. Calcium-channel blocking agents are used intraoperatively and until the first postoperative day followed by oral therapy for 6 weeks (WAG, TMS) or not at all (HBB).
Follow-up
Early (30-day) follow-up information is available for all 649 patients. Follow-up angiography was not performed routinely; however, 27 patients had subsequent cardiac catheterization for clinical indications 1 to 35 months (mean, 9.5 ± 8.3 months) postoperatively.
Data are presented as the mean ± standard deviation or as percentages.
| Results |
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Mortality and morbidity rates are shown in Table 4. There was one early (30-day) death, for an operative mortality rate of 0.2%. The incidence of q-wave myocardial infarction and low output syndrome were also gratifyingly low. Fourteen patients (2%) had low output syndromes requiring significant inotropic support or an intraaortic balloon pump. Hypoperfusion was recognized in only 1 patient and resolved with mobilization of the ITA. The incidence of deep sternal wound infection was low, and there were no ischemic hand complications.
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| Comment |
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We favor the use of the RA based proximally on the ITA both to obtain adequate length to permit revascularization with two conduits alone and to avoid anastomosis of the arterial conduit directly on the aorta. Patency of anastomoses of the ITA to the aorta have been reported to be only 80% to 90% [14, 15] whereas that for the inferior epigastric artery or gastroepiploic artery is 75% to 85% [1618]. Patency is likely lower if the aorta is thickened unless a vein hood or pericardial patch is used as an intermediary. Furthermore, we share the concern of Calafiore and colleagues [19] that placement of what is normally a third or fourth order artery on the aorta could impose abnormal and potentially harmful sheer stress on the conduit. Using the left ITA for inflow, Tector and associates [20] achieved a 91% patency rate with a T graft configuration, and Calafiore and colleagues [19] a 93% patency for anastomosis of the RA to the left ITA.
We chose to explore the use of the RA for construction of a T graft because it has favorable handling characteristics and can be harvested simultaneously with the ITA. Since the revival of the RA as a bypass conduit by Acar and associates [21], it has been embraced with remarkable rapidity by many surgeons, likely for these same reasons. Furthermore, several large series of CAB with this conduit in more conventional configurations have already been reported with good early results [19, 2123].
The patency rate we observed for RA grafts to the branches of the right coronary artery was disappointing. As the postoperative angiograms in this study were prompted by clinical indications rather than routine control studies, this sampling might be biased negatively with regard to patency. Although other authors have observed lower patency rates of arterial grafts to targets other than the left anterior descending artery [24, 25], this observation suggests that we need to reassess our strategy with respect to right-sided vessels. Given the T graft configuration, the graft segments to progressively more right-sided targets are the most distal on the RA and are therefore most likely to be under tension. The observation of diminishing patency with more distal anastomoses of the RA supports this hypothesis. During the conduct of this series, we preferred to use longitudinal (parallel) technique for all side-to-side anastomoses. We recognize, however, that conduit length might be better conserved by the use of crossing (perpendicular) anastomoses, and we have changed our philosophy accordingly. Alternatively, a greater willingness to use a third conduit might be indicated.
Three RA segments demonstrated string signs at postoperative angiography. Two of these grafts were to target vessels with less-than-critical stenoses. String signs therefore might represent an autoregulatory phenomenon in the presence of competitive flow. The persistent patency despite this competitive flow is, we believe, encouraging.
Comparison with other studies
Sauvage and associates [26] first reported the use of composite arterial grafts in a T graft configuration in 1986; however, it has been only recently that large series have been reported. Tector and colleagues [20] reported complete arterial revascularization in 287 patients using both ITAs in a T graft configuration with an operative mortality rate of 1.7%. Early graft patency among the 26 patients who had postoperative angiography was somewhat higher in that series than in our study, with 91% of free right ITA grafts. In contrast with our experience, 4 patients of Tector and colleagues were returned to the operating room for additional saphenous vein grafts in the setting of apparent hypoperfusion, and 4 other patients, excluded from analysis in that series, had additional saphenous grafts placed before weaning from cardiopulmonary bypass because of regional wall motion abnormalities and suspected hypoperfusion. Subsequently, Barra and associates [27] reported on 80 highly selected patients, receiving a left ITA and right ITA T graft with a somewhat higher operative mortality rate of 3.75%. Sixty patients (84.2%) had control angiography at 12 to 24 months postoperatively, demonstrating 93.4% patency of the free right ITA. No episodes of hypoperfusion were observed.
Calafiore and colleagues [19] introduced the use of the RA as a free Y or T graft from the side of the pedicled left ITA. There were no operative deaths in their series of composite arterial grafts, including 103 radial artery T grafts and 124 T grafts constructed with the inferior epigastric artery. The cumulative patency rate was 93.1% for RA grafts at a mean follow-up interval less than 1 year. In the series as a whole, hypoperfusion was seen in 2.5%. More recently, Weinschelbaum and associates [28] studied 164 patients, all of whom had ITA-RA T grafts. Among the 46 patients who had early control angiography, all arterial conduits were patent. The operative mortality rate was also low, at 1.8%.
The results of our larger study are consonant with these reports. Our operative mortality rate compares favorably with the rates of those studies. In contrast to the experience of Tector and associates with two ITAs, we did not observe hypoperfusion even though we applied this technique more broadly and aggressively to older patients, those with left main stenosis, and to those with poor left ventricular function. Our observed patency rate was somewhat lower than the rates in those studies, perhaps reflecting selection bias in patients who had undergoing angiography in our series or the fact that our series included the learning curves of all surgeons involved. It could also reflect, in part, our aggressive approach to complete revascularization including a willingness to place grafts to small target vessels. Additionally, in contrast to both Weinschelbaum and associates and Calafiore and colleagues, calcium channel blockers were not administered postoperatively in approximately 90% of our patients at the discretion of the surgeon (HBB). There are no clear differences in patency rates among surgeons involved.
Rationale for complete arterial revascularization
It is well established that use of a single ITA to the left anterior descending artery reduces the risk of recurrent angina [2], cardiac reoperation [29], late myocardial infarction, and death [1]. This is presumably attributable to the superior late patency of the ITA. Based on this observation, Fiore and associates [3] and Pick and colleagues [4] attempted to show improved event-free survival with bilateral ITA grafting. A statistically significant reduction in subsequent myocardial infarction and recurrence of angina pectoris was demonstrated by Fiore and associates [3] in their retrospective analysis of 100 patients who had bilateral ITA grafting as compared with 100 case-matched controls. A survival benefit was also suggested, as was improved freedom from coronary reintervention. These findings have been confirmed by Pick and colleagues [4] in a similar case-controlled study of patients who had single (n = 161) or bilateral (n = 160) ITA grafting. Bilateral ITA grafting was an independent predictor of lower rates of angina recurrence and late myocardial infarction. More recently, Lytle and colleagues [7] reported reduced risks of reintervention (reoperation or angioplasty) and enhanced survival for all age groups except for those less than 50 years of age when two ITAs were used instead of one.
Those findings have been challenged. Using the Katholieke Universiteit Leuven Coronary Surgery Database, Sergeant and coworkers [5] have been unable to demonstrate an influence of multiple arterial grafting on patient survival or on the return of angina pectoris and the occurrence of infarction [6]. The explanation for this disparity might be the frequent inappropriate choice of targets to which these additional arterial grafts were placed until 1987 and the limited number of patients with sufficiently long follow-up to permit demonstration of late benefit. A strategy that provides complete arterial revascularization neutralizes the issue of target selection and should provide the best possible long-term result.
Study limitations
The principle limitations of this study are the small number of angiographic controls available and the short duration of follow-up in most patients. Unfortunately, routine follow-up angiography is not practical in the current era of cost containment. As the rationale for using T grafts is predicated on long-term benefit, these data are insufficient to argue the superiority of this strategy over the more standard single ITA and additional saphenous vein grafts. These data do, however, indicate that despite the increased complexity of this approach and the theoretic potential for hypoperfusion, this strategy can be used without incurring an increased operative risk. Whether this safety is predominantly reflective of flow through the ITA or the RA grafts is unknown.
We conclude from these data that complete arterial revascularization can be achieved in most patients with a single ITA and a single RA. The operative risk is low. Early graft patency, particularly to the circumflex system, was encouraging. Disappointing patency to more distal targets was likely related to technical factors that are being addressed. These findings support the continued exploration of this grafting strategy in pursuit of a more durable procedure for the treatment of coronary artery disease. Larger, ideally randomized, prospective trials of complete arterial revascularization versus CAB with a single ITA and additional saphenous vein grafts are warranted.
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