Ann Thorac Surg 1999;67:1825-1826
© 1999 The Society of Thoracic Surgeons
Correspondence
Use of radial artery as coronary bypass graft in myocardial revascularization
Jacques A.M. van Son, MD, PhDa
a Herzzentrum, University of Leipzig, Russenstrasse 19, D-04289 Leipzig, Germany
To the Editor
With regard to the renewed interest in the use of the radial artery (RA) as a bypass graft in myocardial revascularization, I wish to express a number of concerns about this practice. Initially the RA was used as a conduit in myocardial revascularization in the 1970s, but was abandoned because of its high failure rate and sporadic episodes of hand ischemia [1–3]. Early graft failure was attributed to vasospasm and intimal hyperplasia, for which multiple factors have been implicated, such as vessel-wall ischemia, operative trauma induced by electrocautery, and mechanical or hydrostatic dilation [1–4].
Interest in the RA as an alternative conduit was rejuvenated in the late 1980s [5]. Since then, several reports have documented significantly improved patency rates attributed to modifications in harvesting technique and the routine use of calcium-channel blockers to prevent vasospasm [6–8]. Brodman and colleagues [7] reported a patency rate of 95.7% in 60 patients at 12 weeks postoperatively. Calafiore and coworkers [8] demonstrated a 13-month patency rate of 94.3% in 35 RAs (of 163 RAs used in the patient cohort). However, long-term angiographic follow-up data have not been published as yet.
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Fig 1. Morphometric characteristics (marked difference in width between media of internal mammary artery and radial artery) and gravitational force constitute risk factors for obstruction of the radial artery-to-internal mammary artery anastomosis.
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There are a number of concerns about the use of the RA as a bypass graft for myocardial revascularization. First, from a teleologic point of view, the practice of anastomosing the RA end-to-side to the internal mammary artery (IMA) is less desirable because this may compromise the function and inflow into the distal IMA, which, with its excellent histologic and flow characteristics, is clinically proved to be the most ideal conduit in myocardial revascularization [9, 10]. Such practice carries the substantial risk of jeopardizing both the IMA and the RA and rendering the entire left ventricular perfusion dependent on the sole IMA pedicle. Second, from a practical point of view, this technique may be associated with a considerable risk of some degree of kinking of the IMA and hence flow obstruction in the IMA, the RA, or both. The reasons for kinking are twofold (Fig 1): (1) Morphometrically, the RA has a thick media as compared with the IMA (mean width of 530 versus 350 µm, respectively) [9]. Therefore, anastomosis of the thick-walled RA to the delicate IMA in itself may constitute a risk factor for kinking. (2) Gravitational force may enhance this risk of kinking. Technically, the risk of kinking is enhanced if the RA is anastomosed to the IMA under too obtuse an angle. To neutralize gravitational force and minimize the risk of obstruction, the RA should be anastomosed at an acute angle.
Alternatively, the technique of anastomosing the RA to the ascending aorta probably should be performed only when favorable conditions are present, ie, a smooth and nonthickened aortic wall and relatively large-caliber RA. To circumvent the problem of anastomotic obstruction, the proximal RA may be anastomosed to the aorta on a hood of saphenous vein graft or pericardium. A second concern regarding anastomosing the RA to the ascending aorta is based on morphologic issues and consists of the fact that the thick-walled muscular media of the RA is exposed to the high shear stresses of the central aortic circulation, which may lead to accelerated intimal hyperplasia. To determine the further role of the RA as a conduit in myocardial revascularization, mid- and long-term patency rates of the RA need to be carefully analyzed regarding all the aforementioned issues.
References
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Curtis J.J., Stoney W.S., Alford W.C., Jr, Burrus G.R., Thomas C.S., Jr Intimal hyperplasia: a cause of radial artery aorto-coronary bypass graft failure. Ann Thorac Surg 1975;20:628-635.[Abstract]
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Fisk R.L., Brooks C.H., Callaghan D.C., Dvorkin J. Experience with the radial artery graft for coronary artery bypass. Ann Thorac Surg 1976;21:513-518.[Abstract]
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Van Son J.A.M. Revival of the radial artery for coronary artery bypass grafting: l’histoire se repète [Letter]. Ann Thorac Surg 1993;55:1596-1598.[Medline]
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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]
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Dietl C.A., Benoit C.H. Radial artery graft for coronary revascularization: technical considerations. Ann Thorac Surg 1995;60:102-110.[Abstract/Free Full Text]
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Brodman R.F., Frame R., Camacho M., Hu E., Chen A., Hollinger I. Routine use of unilateral and bilateral radial arteries for coronary artery bypass graft surgery. J Am Coll Cardiol 1996;28:959-963.[Abstract]
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Calafiore A.M., Di Giammarco G., Teodori G., et al. Radial artery and inferior epigastric artery in composite grafts: improved midterm angiographic results. Ann Thorac Surg 1995;60:517-524.[Abstract/Free Full Text]
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Van Son J.A.M., Smedts F., Vincent J.G., van Lier H.J.J., Kubat K. Comparative anatomic studies of various arterial conduits for myocardial revascularization. J Thorac Cardiovasc Surg 1990;99:703-707.[Abstract]
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Van Son J.A.M., Smedts F., de Wilde P.C.M., et al. Histological study of the internal mammary artery with emphasis on its suitability as a coronary artery bypass graft. Ann Thorac Surg 1993;55:106-113.[Abstract]
