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Ann Thorac Surg 2001;72:120-125
© 2001 The Society of Thoracic Surgeons

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Original article: cardiovascular

Coronary artery bypass grafting using the radial artery: midterm results in a Japanese institute

Accepted for publication April 5, 2001.

Address reprint requests to Dr Amano, Department of Cardiovascular Surgery, Shin-Tokyo Hospital, 473-1 Nemoto, Matsuda City, Chiba 271-0077, Japan
e-mail: shingeka{at}bp.lij4u.or.jp

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. To avoid remote cardiac events associated with graft occlusions, arterial conduits are being increasingly utilized in coronary artery bypass grafting (CABG). The development of antispasmic agents has enabled the use of the radial artery as a graft conduit in CABG.

Methods. Between December 1995 and December 1998, 920 consecutive isolated CABG operations were performed at Shin-Tokyo Hospital. The radial artery was used for graft conduits in 475 of these patients, and their data were analyzed in this study. The patients were followed to determine midterm graft patency, cardiac events, and survival. All data are given as mean ± standard deviation. The end points were patient death or occurrence of cardiac events.

Results. The radial artery was used in 475 patients (366 males and 109 females, with a mean age of 64.5 ± 8.5 years). The left internal mammary artery was used in 94.9% of patients, the right internal mammary artery in 17.5%, the gastroepiploic artery in 50.9%, the inferior epigastric artery in 0.2%, and the saphenous vein in 39.2%. The in-hospital morbidity and mortality rates of the studied group were 12.8% and 0.6%, respectively. A major complication related to radial artery harvesting, compartment syndrome of the arm due to postoperative bleeding, was observed in 1 patient. No postoperative myocardial infarction attributable to radial artery bypass was observed. During the late follow-up period of 3.5 ± 0.9 years, cardiac events were observed in 63 patients, giving actuarial 2- and 3-year event-free rates of 92.8% and 89.6%, respectively. A total of 24 late deaths were noted, including seven cardiac deaths, giving actuarial 2- and 3-year survival rates of 98.1% and 97.2%, respectively. Postoperative angiography was performed in selected patients. The cumulative graft patency rate of the radial artery was 93.0% during the mean angiographical follow-up period of 1.5 ± 1.1 years.

Conclusions. No adverse effects were noted after CABG using a radial artery graft in this short- and midterm follow-up period.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
To avoid remote cardiac events associated with graft occlusions, which are known to occur more frequently in saphenous vein bypasses, arterial conduits are being increasingly utilized in coronary artery bypass grafting (CABG). The internal mammary arteries (IMAs) are the most frequently used, and their reported patency rates have been reported to be 90% or better even 10 years after CABG [1, 2]. Due to the anatomical location of IMAs and their excellent patency, they are normally used for bypass to the left anterior descending artery (LAD). The second choice for arterial conduits is controversial: the gastroepiploic artery (GEA) is often used as an in situ graft to the distal right coronary artery (RCA) [3], and since Acar and associates reported excellent outcomes in patients undergoing radial artery grafting in 1992 [4], the radial artery has also become more commonly utilized in CABG. At our institute, the technique of radial artery grafting was adopted in December 1995, and by the end of 1998, a total of 475 patients had undergone the procedure. In this study, we carried out a retrospective analysis to confirm the safety of performing radial artery grafting and to determine midterm graft patency, cardiac events, and survival rates.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Between December 1995 and December 1998, a total of 920 consecutive patients underwent isolated CABG at Shin-Tokyo Hospital. Those who underwent valvular surgery, left ventricular surgery, or additional general or vascular surgery at the time of CABG were excluded; thus, a total of 475 patients (51.6%) who underwent radial artery grafting were included in this study.

The techniques of radial artery bypass are described elsewhere [5]. Briefly, preoperative exclusion criteria for radial artery harvesting were positive Allen’s test, serum creatinine greater than 1.8, and significant radial artery stenosis as revealed by Doppler ultrasound. Radial artery harvesting was performed using the standard technique described by Reyes and associates [6]. Prophylaxis of vasospasm was achieved by intravenous administration of calcium channel blockers such as diltiazem or nicorandil during the operation, as well as local spraying with diluted papaverine (1:10). The harvested radial artery was preserved by soaking in warm papaverine solution. Shortly before anastomosis, the harvested pedicle was cannulated and systemic arterial pressure was applied in order to facilitate the release of spasm and to achieve further hemostasis.

The radial artery was used as an aortocoronary bypass or as a composite Y-graft. When the radial artery was used as a composite graft, proximal anastomosis between the donor artery and the radial artery was first performed, followed by distal anastomosis onto the target coronary artery. The inflow conduit of the composite Y-graft was usually the left internal mammary artery (LIMA).

Other graft conduits used with the radial artery were the LIMA, usually bypassed onto the LAD, the right internal mammary artery (RIMA) bypassed onto the proximal RCA or LAD, the GEA onto the distal RCA, and the saphenous vein onto the RCA or circumflex artery if arterial grafts were not available. Thus, the primary target of the radial artery was the circumflex artery (CX). CABG was performed under normothermia (36°C) with cardiopulmonary bypass. After September 1996, off-pump CABG was adopted and selected cases were referred to off-pump CABG under beating-heart conditions [7].

Postoperative angiography was performed in selected patients. The first 50 patients systematically underwent coronary angiography within 3 months after surgery, and thereafter, early coronary angiography was performed either due to the poor quality of native coronary arteries or at the request of the referring cardiologists. Late coronary angiography was proposed for all patients followed at our institute; but was only performed with the patient’s permission. Follow-up angiography was strongly recommended for all patients with symptoms of angina. In addition, symptom-free patients underwent angiography at various times because the majority of patients (83%) were followed by referring physicians and were not under our direct observation.

By retrospective chart review, the following parameters were collected: patients’ age, gender, results of preoperative angiography, cardiac profiles, preoperative risk factors, graft material, surgical data, postoperative complications, and mortality. Outpatient follow-up was completed by the referring cardiologists or hospital outpatient clinic. Any cardiac events after discharge from hospital, including myocardial infarction, angina, arrhythmia requiring hospitalization, congestive heart failure requiring hospitalization, native coronary artery or graft stenosis requiring any type of coronary intervention, and sudden death were counted as a cardiac events. These follow-up data were compiled by January 31, 2001. The end points were patient death or the occurrence of cardiac events.

Results are expressed as mean ± standard deviation. Postoperative patient survival, event-free rate, and long-term graft patency were calculated using the Kaplan-Meier method. All statistical analyses were performed using Statview version 5.0 (SAS Institute, Cary, NC).

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
Patients demographics
A total of 475 patients were included in this study (366 males and 109 females, with a mean age of 64.5 ± 8.5 years). The demographic details of the patients are given in Table 1.

Angiographic study
Early (within 3 months after surgery) postoperative angiography was performed in 98 patients (Table 4), which revealed two radial artery occlusions; one was a free-radial artery aortocoronary bypass to the CX, and the other was composite Y-grafting to the LCX. All patients with early graft failures were medically managed and no reoperations were performed. A total of 167 patients (36.4%) underwent late coronary angiography (more than 3 months after surgery), and revealed an additional 16 radial anastomotic occlusions. Nine occlusions were identified in composite radial artery grafts using the LIMA, and seven in aortocoronary bypasses using free-radial artery grafts. There were no significant differences in terms of composite or free radial graft occlusions. Among the patients who underwent late angiography, 26 patients had symptomatic angina and the other 141 patients were symptom free. Occlusion of the radial artery graft was related to the occurrence of angina in four cases (two composite grafts and two free grafts), and these patients were successfully managed by catheter interventions. The cumulative graft patency rate of the radial artery was 93.0% at the mean angiographical follow-up period of 1.5 ± 1.1 years. The calculated patency rates of radial artery grafting at 1, 2, and 3 years were 98.2%, 91.0%, and 86.2%, respectively. String sign, which was defined as a severe and extensive narrowing of the whole body of the graft [4], was documented in a total of 13 radial artery grafts: five by early angiography and an additional eight by late angiography. No patients with string sign had symptomatic angina. Stenosis of the anastomosis was observed in a total of 11 patients: 7 by early angiography and an additional 6 by late angiography.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

In this study, the target of the radial artery graft was usually the CX, because the LAD was normally revascularized with the IMA, and the RCA with the GEA. The RCA can be revascularized with the radial artery if the GEA cannot be used or if the RCA system requires revascularization with more than two grafts. The use of saphenous vein grafts was reserved only if there was a lack of arterial grafts.

One of the contraindications of radial artery harvesting is poor renal function and an increased risk of the need for hemodialysis after surgery, because the radial artery is most commonly used for the inflow of the arteriovenous fistula for hemodialysis blood access. Another contraindication for radial artery use is poor collateral supply from the ulnar artery leading to a risk of postoperative hand ischemia. However, we avoided this problem using a combination of Allen’s test and preoperative Doppler examination. Emergency surgery is not a contraindication for radial artery grafting, because vasospasm occurring in the radial artery can also be successfully resolved under our harvesting protocol. The radial artery can be used safely in diabetic patients. Unlike wounds made to the leg, the wound resulting from radial artery harvesting usually heals rapidly and the occurrence of local infections is rare. Sensory deficit after radial artery harvesting usually due to superficial radial nerve injury, which rarely occurred, is considered to be the result of technical insufficiency during the harvesting. Redo patients may benefit from radial artery grafting, because the radial artery was not used before the 1980s.

In our study, minimal radial artery graft-related complications were observed. No postoperative myocardial infarction attributable to the radial artery bypass was noted. One patient experienced unexpected postoperative renal failure requiring permanent dialysis access via a fistula created in the right arm. We experienced one case of compartment syndrome at the radial artery harvesting site. The wound was closed without any sign of the infection after evacuation of the hematoma and hemostasis of the bleeding vessel.

The radial artery graft was examined by angiography in selected patients. Although the angiographical follow-up period (1.5 ± 1.1 years) was relatively short, the graft patency was excellent. The calculated radial artery patency rates were 91.0% at 2 years and 86.2% at 3 years. These patency rates compared well with the patency of the other arterial graft conduits, such as the IMA or GEA. The longest angiographical follow-up of the radial artery was performed by Acar and associates, who reported radial artery grafts patency rates of 99% in the postoperative period, 92% at 1 year, and 83% at 5 years [11]. A recent review of radial artery grafting showed early patency rates of between 95.7% and 100%, and midterm patency rates of between 87.5% and 100% [12].

String sign occurs relatively frequently in muscular arterial conduits such as the radial artery, the GEA, and the inferior epigastric artery. Possati and associates reported that string sign of the radial artery was observed at a rate of 3.3% in his series of patients [13], which is in close agreement with our results. These string signs were observed under low-graft flow conditions, which resulted from flow competition between the graft and the native coronary artery [14]. Flow competition with the native coronary artery can also be observed in high-flow coronary artery with/without mild coronary stenosis (Fig 1). Another type of flow competition can develop among the composite grafts (Fig 2). If the vascular bed allotted to the radial artery graft is smaller than the territory of the composite IMA graft, and if the IMA requires higher runoff than the radial artery, the graft flow in the radial artery falls off. Furthermore, due to the greater vascular resistance in the radial artery than in the IMA, the low-flow state, angiographically called string sign, of the composite radial artery may lead to a no-flow condition or even total occlusion. Although low-flow volume is rarely related to late graft occlusion in IMA grafts [15], poor flow through the radial artery may result in graft failure. Thus, if poor runoff is expected, the composite radial artery graft should not be used and a free aortocoronary bypass should be considered.

View larger version (91K): [in this window] [in a new window]   Fig 1. Flow competition with the native coronary artery. The right coronary artery (RCA) shows multiple but mild stenosis (left) and the radial artery (RA) has been grafted onto the posterior descending artery of the RCA (right). The distal flow is mainly provided by the native coronary artery. The grafted radial artery has poor graft flow and is showing a string sign.

View larger version (97K): [in this window] [in a new window]   Fig 2. Flow competition between the arms of the Y-graft. The distal perfusion territory of the radial artery (RA) is smaller than that of the left internal mammary artery (LIMA). The graft flow through the RA is smaller than the flow through the LIMA, and the RA is showing a string sign.

Good graft patency was reflected in the small number of patients experiencing remote cardiac events. Although the follow-up period was only 3.5 ± 0.9 years, the calculated 3- and 4-year event-free rates were 89.6% and 85.8%, respectively. Remote death was observed in only 5.1% of our patients, and the calculated 3- and 4-year survival rates were 97.2% and 93.7%, respectively. These were similar to the results reported in a previous study by Acar and associates, who reported a 5-year event-free rate of 88.7% and a 5-year survival rate of 91.6% [11].

No adverse effects were noted after CABG using the radial artery in our midterm follow-up, and the patency of the radial artery graft was similar to other arterial grafts. The use of radial artery bypass contributed to increasing the chance of total arterial revascularization and to decreasing the occurrence of remote cardiac events or cardiac deaths.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Reardon M.J., Conklin L.D., Reardon P.R., Baldwin J.C. Coronary artery bypass conduits: review of current status. J Cardiovasc Surg (Torino) 1997;38:201-209.[Medline]
2. Barner H.B. Arterial grafting: techniques and conduits. Ann Thorac Surg 1998;66(Suppl):2-5.
3. Suma H., Amano A., Horii T., Kigawa I., Fukuda S., Wanibuchi Y. Gastroepiploic artery graft in 400 patients. Eur J Cardiothorac Surg 1996;10:6-11.[Abstract/Free Full Text]
4. Acar C., Jebara V.A., Portoghese M., et al. Revival of the radial artery for coronary artery bypass grafting. Ann Thorac Surg 1992;54:652-660.[Abstract/Free Full Text]
5. Yoshida S., Amano A., Egami J., Sunami H., Takahashi A. Early results of coronary artery bypass grafting using radial artery grafts. Nippon Kyobu Geka Gakkai Zasshi 1998;45:166-167.
6. Reyes A.T., Frame R.N., Brodman R.F. Technique for harvesting the radial artery as a coronary artery bypass graft. Ann Thorac Surg 1995;59:118-126.[Abstract/Free Full Text]
7. Amano A., Hirose H., Takahashi A., Nagano N. Off-pump coronary arterial bypass: midterm results. Jpn J Thorac Cardiovasc Surg 2001;49:67-78.[Medline]
8. Carpentier A., Guermonprez J.L., Deloche A., Frechette C., Du Bost C. The aorta-to-coronary radial artery bypass graft. A technique avoiding pathological changes in grafts. Ann Thorac Surg 1973;16:111-121.[Abstract/Free Full Text]
9. Reardon M.J., Conklin L.D., Reardon P.R., Baldwin J.C. Coronary artery bypass conduits: review of current status. J Cardiovasc Surg (Torino) 1997;38:201-209.
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11. Acar C., Ramsheyi A., Pagny J.Y., et al. The radial artery for coronary artery bypass grafting: clinical and angiographic results at five years. J Thorac Cardiovasc Surg 1998;116:981-989.[Abstract/Free Full Text]
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13. Possati G., Gaudino M., Alessandrini F., et al. Midterm clinical and angiographic results of radial artery grafts used for myocardial revascularization. J Thorac Cardiovasc Surg 1998;116:1015-1021.[Abstract/Free Full Text]
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This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Amano, A. Articles by Nagano, N. Search for Related Content PubMed PubMed Citation Articles by Amano, A. Articles by Nagano, N. Related Collections Coronary disease