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Ann Thorac Surg 2003;76:1505-1509
© 2003 The Society of Thoracic Surgeons
a Department of Cardiovascular Surgery, Maizuru Mutual Hospital, Maizuru, Japan
b Department of General and Cardiothoracic Surgery, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan
Accepted for publication April 28, 2003.
* Address reprint requests to Dr Kamiya, Department of Cardiovascular Surgery, Maizuru Mutual Hospital, Hama 1035, Maizuru 625-8585, Japan.
e-mail: h.kamiya{at}triton.ocn.ne.jp
Abstract
BACKGROUND: The suitability of the radial artery after transradial catheterization as a bypass conduit has been of great concern to surgeons.
METHODS: A total of 67 patients underwent isolated coronary artery bypass grafting using the radial artery: 22 patients received preoperative transradial catheterization (group 1) and 45 patients did not receive transradial catheterization (group 2). Those patients were retrospectively reviewed.
RESULTS: Patient characteristics, operative procedures, and early clinical outcome were not different between groups. The stenosis-free graft patency rates in groups 1 and 2 were 88% (16 of 18 patients) and 90% (38 of 42 patients) in the left internal thoracic artery (p = 0.87); 77% (17 of 22 patients) and 98% (48 of 49 patients) in the radial artery (p = 0.017); and 87% (13 of 15 patients) and 84% (21 of 25 patients) in the saphenous vein (p = 0.42), respectively. Intimal hyperplasia of the radial artery was observed in 68% (11 of 16 patients) in group 1 and in 39% (14 of 34 patients) in group 2 (p = 0.046).
CONCLUSIONS: Transradial catheterization reduced early graft patency and caused intimal hyperplasia, although it did not affect early clinical outcomes. We suggest that the use of the radial artery as a bypass conduit after transradial catheterization should be undertaken cautiously.
The use of the radial artery (RA) graft was introduced by Carpentier and colleagues in 1973 [1], but this conduit was abandoned for its discouraging outcome as a result of hyperspasticity and intimal hyperplasia. However, coupled with an increasing interest in total arterial revascularization in coronary surgery, there has been a resurgence in the use of the RA as an alternative arterial conduit [2], and recently good clinical and angiographic outcomes have been obtained with the RA [3–6]. In addition, the RA has also been used as an alternative entry site for coronary catheterization, and recent advances in miniaturization of devices for percutaneous coronary angiography and angioplasty have further facilitated the transradial (TR) approach as a routine technique [7–9]. Although great concerns have been raised regarding the suitability of the use of the RA after TR catheterization as a bypass conduit, there has been no study that examines this issue.
The purpose of this study was to compare clinical, angiographic, and pathologic results of RA grafting between patients with and without previous TR catheterization and clarify whether the RA after TR catheterization is suitable as a bypass conduit.
Material and methods
Patients
This was a retrospective cohort study. From January 1999 in our hospital, a total of 67 consecutive patients underwent elective isolated coronary artery bypass grafting using the RA. Patients with renal dysfunction were not included in this study because the use of the RA was avoided owing to the possibility for the need of it to make an arteriovenous shunt for hemodialysis therapy in the future. Of those patients, 22 patients underwent preoperative TR catheterization on the same side on which the RA was harvested (group 1), and 45 patients did not undergo recent TR catheterization (group 2). Group 1 included patients who underwent recent catheterization from other sites in addition to previous TR catheterization. During the study period, TR catheterization had been performed in approximately 80% of patients receiving diagnostic catheterization and approximately 60% of patients receiving interventional catheterization at the catheter laboratory in our hospital. Regarding patients from other hospitals, TR catheterization had not been performed at any of the catheter laboratories in other hospitals that consulted us about coronary artery bypass grafting. There were 40 patients consulted by cardiologists in our hospital and 27 patients consulted by cardiologists of other hospitals. Medial records of these patients were retrospectively reviewed. Patients who received off-pump coronary artery bypass grafting were excluded from this analysis. The patient characteristics are detailed in Table 1.
There were no significant differences in patient characteristics between the two groups.
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Harvesting of the radial artery
All patients underwent Allen's test, and negative results were confirmed. In addition, ultrasonic assessment was performed in all patients to rule out severe arteriosclerotic changes, calcifications, or endoluminal narrowing of the RA. The RA far from the previous cannulation sites for TR catheterization was harvested together with its pedicle including the surrounding fat and satellite veins in the nondominant forearm. After systemic anticoagulation with heparin, papaverine chloride (1 mg/mL of saline) was introduced intraluminally through the distal end of the RA with a blunt-end vascular needle, and the distal end was then secured. The RA was allowed to pulsate for 5 minutes before the proximal end was secured, and the harvested RA was placed in heparin-treated arterial blood.
Coronary artery bypass grafting
After harvesting of the appropriate grafts, coronary artery bypass grafting was performed during cardiopulmonary bypass with cardioplegic arrest. The target of the left internal thoracic artery (LITA) was the left anterior descending coronary artery in all cases, and the RA was grafted to the second most important vessel. If necessary, a saphenous vein (SV) graft was used as the third conduit. All RA grafts and SV grafts were anastomosed to the ascending aorta. The operative data are shown in Table 1. There was a tendency for an increased number of distal anastomoses, longer aortic clamping time, and longer cardiopulmonary bypass time in group 1; however, there were no significant differences in the distribution of distal anastomosis sites of grafts between the two groups.
For prophylaxis of perioperative vasospasm, diltiazem (intravenously, 2.5 mg/h; orally, 90 mg/d) was used in all patients.
Angiographic assessment
The necessity and significance of postoperative coronary angiography were explained to all patients, and angiography was performed if patients agreed. Postoperative angiography was performed approximately 1 month after the operation in 18 patients (81%) with 19 LITA, 22 RA, and 15 SV in group 1, and in 42 patients (93%) with 42 LITA, 49 RA, and 25 SV in group 2. Angiographic results showing good patency without more than 50% stenosis, string sign [2], or occlusion were classified as stenosis-free graft patency [10].
Histologic assessment
In cases in which the harvested RA graft had sufficient length, the distal portion of the RA graft was histologically evaluated. Sixteen specimens (72%) in group 1 and 36 specimens (80%) in group 2 were submitted for histologic evaluation. Specimens were fixed with 10% formaldehyde, cross-sectioned at 4 µm, and mounted. These samples were stained with hematoxylin and eosin. Retrospectively, a blinded, independent reader assessed the specimens for intimal hyperplasia. An intima-to-media ratio greater than 0.25 was considered to be demonstrative of the existence of intimal hyperplasia.
Statistical analysis
Results were expressed as mean ± standard deviation. Statistical analysis was performed using Student's t test for continuous variables or 
2 tests (Fisher's exact tests if n < 5) for categorical variables. A p value less than 0.05 was considered significant. All statistical analyses were performed using StatView version 5.0 (SAS Institute, Cary, NC).
Results
Clinical outcome
Hospital death occurred in two patients in group 2 because of perioperative myocardial infarction, but the incidence of hospital death did not show a significant difference between the groups (p = 0.55). No other patients suffered any serious postoperative complications.
Angiographic results
The stenosis-free graft patency rates in groups 1 and 2 were 88% (16 of 18 patients) and 90% (38 of 42 patients) in the LITA, 77% (17 of 22 patients) and 98% (48 of 49 patients) in the RA, and 87% (13 of 15 patients) and 84% (21 of 25 patients) in the SV, respectively. There were no significant differences in graft patency in the LITA and SV between the two groups; however, early graft patency in group 1 was significantly lower than that in group 2 (Fig 1).
In group 1, among 5 cases of RA graft failure, 3 RA grafts were occluded, 1 showed 90% diffuse narrowing at the body (Fig 2),
and 1 showed 90% stenosis at the proximal anastomosis line. In group 2, 1 RA graft was occluded.
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This study demonstrated that preoperative TR catheterization deteriorated early graft patency and caused intimal hyperplasia in the RA, although it did not affect early clinical outcomes.
The use of the RA has been revived because of the availability of antispastic agents, as well as improvement of the harvesting technique [2]. This revival of RA use has made available an additional arterial conduit, which can be used in tandem with the LITA to achieve predominantly or totally arterial coronary revascularization [11, 12]. Parolari and associates [11] reviewed the data regarding the RA as a coronary bypass graft, and they reported that early patency rates of the RA graft ranged from 77% to 100%, and midterm patency rates ranged from 88% to 100%. They concluded that the recent evidence regarding 5-year patency rates supported the use of the RA as the second arterial conduit after the internal thoracic arteries [11]. Moreover, a recent report by Ikeda and coworkers [6] presented excellent results of early and midterm patency rates of the RA in relatively large study population: early patency was 99% (144 of 145 patients) and midterm patency was 91% (24 of 26 patients). Similar to previous reports, the early patency rate of the RA without preoperative TR catheterization was 97% in this study. However, the early patency rate of the RA with preoperative TR catheterization was 77%, and it was significantly lower than that of the RA without preoperative TR catheterization.
It is well known that the RA is a thick-walled muscular artery and has a much higher possibility of suffering from intimal hyperplasia and arteriosclerotic change than the internal thoracic artery, which is an elastic artery [11]. Kaufer and colleagues [13] investigated the pathology of the RA in detail. In their study, an intima-to-media ratio greater than 0.25 was observed in 54% (57 of 106 patients) of the RA specimens and in 23% (14 of 62 patients) of the LITA specimens. They suggested that one of the reasons that the RA is likely to suffer from arteriosclerotic changes is that unlike the internal thoracic artery, the RA may be subject to intraluminal trauma from previous RA cannulation for arterial blood pressure monitoring or blood gas sampling [13]. Similar to their findings, our study demonstrated that distal sites of the RA suffered from greater intimal hyperplasia after preoperative TR catheterization compared with those without TR catheterization. However, the distal cannulation site for the preoperative TR catheterization was not harvested in this series, and thus it cannot be concluded simply that intimal hyperplasia of the RA after preoperative TR catheterization observed in our study was solely caused by cannulation. However, there is a study that suggests that TR catheterization can cause extensive damage to the RA. Nagai and associates [14] performed ultrasound measurements of the RA before, 2 days after, and 95 days after TR catheterization in 162 patients, and they noted a late incidence of total occlusion and diffuse narrowing in 5% and 22% of the patients, respectively. This could well indicate that TR catheterization damaged not only the distal cannulation site but other parts of the RA as well. Hence, we argue that TR catheterization damaged the intima and caused intimal hyperplasia of the whole RA or at least the part to which the introducer reaches, resulting in lower early patency of the RA graft.
The subanalysis regarding relationships between occurrence of graft stenosis or occlusion and TR catheterization indicated that the number of previous TR catheterizations is the most likely factor affecting graft patency (p = 0.07) in this study. There have been no reports about repeated TR catheterizations, but this result suggests at least that the use of the RA as a bypass conduit after repeated TR catheterizations should be undertaken with great caution. Additionally, although the results of this study did not show any statistical significance, the study by Nagai and coworkers [14] suggests that RA with TR catheterization using a large-size introducer system should be used with caution. In their study, 38% (33 of 86 patients) of patients with no flow or diffuse stenosis had RA diameters smaller than the sheath diameter, and 14% (11 of 76 patients) of patients had RA diameters larger than the sheath diameter (p < 0.01) [14].
In conclusion, preoperative TR catheterization deteriorated early patency rates of RA grafts and is likely to cause intimal hyperplasia. Although the results of this study are somewhat limited because of the relatively small number of patients reviewed, we suggest that use of the RA as a bypass conduit after preoperative TR catheterization should be undertaken cautiously, especially in cases in which the RA received repeated TR catheterizations or insertion of a sheath system larger than the diameter of the RA. The results of this study should be confirmed by further clinical investigations at large institutes.
References
This article has been cited by other articles:
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  M. S. Spence, P. Klinke, and D. Hilton Letter by Spence et al Regarding Article, "Impact of Patient and Target-Vessel Characteristics on Arterial and Venous Bypass Graft Patency: Insight From a Randomized Trial" Circulation, October 9, 2007; 116(15): e374 - e374. [Full Text] [PDF]
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 K.F. Layton, D.F. Kallmes, and T.J. Kaufmann Use of the Ulnar Artery as an Alternative Access Site for Cerebral Angiography AJNR Am. J. Neuroradiol., November 1, 2006; 27(10): 2073 - 2074. [Abstract] [Full Text] [PDF]
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 E. Madssen, P. Haere, and R. Wiseth Radial Artery Diameter and Vasodilatory Properties After Transradial Coronary Angiography Ann. Thorac. Surg., November 1, 2006; 82(5): 1698 - 1702. [Abstract] [Full Text] [PDF]
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L. R. Sajja, G. Mannam, N. R. Pantula, and S. Sompalli Role of Radial Artery Graft in Coronary Artery Bypass Grafting Ann. Thorac. Surg., June 1, 2005; 79(6): 2180 - 2188. [Abstract] [Full Text] [PDF]
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 C.-H. Yap and J. F Kenny Transradial angiography may deleteriously affect patency of radial artery grafts BMJ, October 30, 2004; 329(7473): 1046 - 1046. [Full Text]
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