Invited commentary

Abstract

Arterial grafts have been increasely used for coronary artery bypass grafting (CABG) since the successful use of internal mammary artery (IMA) grafting [1Loop F.D. Lytle B.W. Cosgrove D.M. et al.Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events.N Engl J Med. 1986; 314: 1-6Crossref PubMed Scopus (2263) Google Scholar]. Additional arterial grafts are radial artery (RA) [2Acar C. Jebara V.A. Portoghese M. et al.Revival of the radial artery for coronary bypass grafting.Ann Thorac Surg. 1992; 54: 652-660Abstract Full Text PDF PubMed Scopus (648) Google Scholar], gastroepiploic artery (GEA), inferior epigastric artery (IEA), subscapular artery, lateral femoral circumflex artery, inferior mesenteric artery, and ulnar artery. It is the unanimous opinion that the use of IMA is the first choice for an arterial graft, but there is no consensus for the second choice of an arterial graft. In some institutions and my own practice, however, the RA has become the preferred second arterial graft after the IMA.According to our functional classification [3He G.-W. Yang C.-Q. Comparison among arterial grafts and coronary artery. An attempt at functional classification.J Thorac Cardiovasc Surg. 1995; 109: 707-715Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar], the RA is a type III arterial graft—a type of graft that is more spastic than type I arteries (such as IMA and IEA). The major concern about use of RA is its tendency to develop spasms during harvesting and/or in the postoperative period. After successful resolution of this issue [2Acar C. Jebara V.A. Portoghese M. et al.Revival of the radial artery for coronary bypass grafting.Ann Thorac Surg. 1992; 54: 652-660Abstract Full Text PDF PubMed Scopus (648) Google Scholar, 4He G.-W. Yang C.-Q. Use of verapamil and nitroglycerin solution for preparation of radial artery for coronary bypass grafting.Ann Thorac Surg. 1996; 61: 610-614Abstract Full Text PDF PubMed Scopus (125) Google Scholar], this arterial graft is used more safely now. Currently, the major concern about the RA graft is whether the long-term patency of the RA is comparable to other arterial grafts.A recent report of early angiographic studies from Hirose [5Hirose H. Amano A. Takahashi A. Takanashi S. Skeletonization of the radial artery with the ultrasonic scalpel clinical and angiographic results.Heart Surg Forum. 2003; 6: E42-47PubMed Google Scholar] found that the stenosis-free graft patency rate of radial artery anastomoses (291/303 cases, 96.0%) is not significantly different from patency rates of other conduits (left IMA, 95.1%; right IMA, 93.8%; GEA, 93.1%; and saphenous vein, 98.2%).Another recent prospective, randomized, single-center trial from Buxton et al in Melbourne was conducted on two groups of patients undergoing primary coronary artery bypass surgery. They determined that graft patency estimates at 0–10 years are as follows: 0.95 in 39 RA vs 1.0 in 29 right IMA in a younger group (<70 years) and 0.86 in 24 RA vs 0.95 in 22 saphenous veins in an older group (≧ 70 years). They concluded that 5-year interim results do not support the hypothesis that the RA has superior patency to or is associated with fewer clinical events than free right IMA or saphenous vein grafts.The results remind us that in order to determine the patency rates for arterial grafts in the long term, it is necessary to have more reports of prospective, large randomized studies.The report from Hagiwara et al only studied 15 radial artery grafts. Such a small number does not provide definitive conclusions regarding patency or comparisons to other grafts. The authors' conclusion that structural changes rarely developed in radial artery grafts in the early years after surgery is speculative. Rather, the report describes a method to study coronary artery bypass grafts in vivo. As an invasive diagnostic method, the use will be limited. However, before any noninvasive method is developed for evaluation of in vivo graft function or patency, intravascular ultrasound imaging may provide a direct method for observing the early changes in the graft from the intraluminal view. Intravascular ultrasound imaging also may be used as an adjunctive method during angiographic studies of graft patency.[6Buxton B.F. Raman J.S. Ruengsakulrach P. et al.Radial artery patency and clinical outcomes five-year interim results of a randomized trial.J Thorac Cardiovasc Surg. 2003; 125: 1363-1371Abstract Full Text Full Text PDF PubMed Scopus (150) Google Scholar] Arterial grafts have been increasely used for coronary artery bypass grafting (CABG) since the successful use of internal mammary artery (IMA) grafting [1Loop F.D. Lytle B.W. Cosgrove D.M. et al.Influence of the internal-mammary-artery graft on 10-year survival and other cardiac events.N Engl J Med. 1986; 314: 1-6Crossref PubMed Scopus (2263) Google Scholar]. Additional arterial grafts are radial artery (RA) [2Acar C. Jebara V.A. Portoghese M. et al.Revival of the radial artery for coronary bypass grafting.Ann Thorac Surg. 1992; 54: 652-660Abstract Full Text PDF PubMed Scopus (648) Google Scholar], gastroepiploic artery (GEA), inferior epigastric artery (IEA), subscapular artery, lateral femoral circumflex artery, inferior mesenteric artery, and ulnar artery. It is the unanimous opinion that the use of IMA is the first choice for an arterial graft, but there is no consensus for the second choice of an arterial graft. In some institutions and my own practice, however, the RA has become the preferred second arterial graft after the IMA. According to our functional classification [3He G.-W. Yang C.-Q. Comparison among arterial grafts and coronary artery. An attempt at functional classification.J Thorac Cardiovasc Surg. 1995; 109: 707-715Abstract Full Text Full Text PDF PubMed Scopus (125) Google Scholar], the RA is a type III arterial graft—a type of graft that is more spastic than type I arteries (such as IMA and IEA). The major concern about use of RA is its tendency to develop spasms during harvesting and/or in the postoperative period. After successful resolution of this issue [2Acar C. Jebara V.A. Portoghese M. et al.Revival of the radial artery for coronary bypass grafting.Ann Thorac Surg. 1992; 54: 652-660Abstract Full Text PDF PubMed Scopus (648) Google Scholar, 4He G.-W. Yang C.-Q. Use of verapamil and nitroglycerin solution for preparation of radial artery for coronary bypass grafting.Ann Thorac Surg. 1996; 61: 610-614Abstract Full Text PDF PubMed Scopus (125) Google Scholar], this arterial graft is used more safely now. Currently, the major concern about the RA graft is whether the long-term patency of the RA is comparable to other arterial grafts. A recent report of early angiographic studies from Hirose [5Hirose H. Amano A. Takahashi A. Takanashi S. Skeletonization of the radial artery with the ultrasonic scalpel clinical and angiographic results.Heart Surg Forum. 2003; 6: E42-47PubMed Google Scholar] found that the stenosis-free graft patency rate of radial artery anastomoses (291/303 cases, 96.0%) is not significantly different from patency rates of other conduits (left IMA, 95.1%; right IMA, 93.8%; GEA, 93.1%; and saphenous vein, 98.2%). Another recent prospective, randomized, single-center trial from Buxton et al in Melbourne was conducted on two groups of patients undergoing primary coronary artery bypass surgery. They determined that graft patency estimates at 0–10 years are as follows: 0.95 in 39 RA vs 1.0 in 29 right IMA in a younger group (<70 years) and 0.86 in 24 RA vs 0.95 in 22 saphenous veins in an older group (≧ 70 years). They concluded that 5-year interim results do not support the hypothesis that the RA has superior patency to or is associated with fewer clinical events than free right IMA or saphenous vein grafts. The results remind us that in order to determine the patency rates for arterial grafts in the long term, it is necessary to have more reports of prospective, large randomized studies. The report from Hagiwara et al only studied 15 radial artery grafts. Such a small number does not provide definitive conclusions regarding patency or comparisons to other grafts. The authors' conclusion that structural changes rarely developed in radial artery grafts in the early years after surgery is speculative. Rather, the report describes a method to study coronary artery bypass grafts in vivo. As an invasive diagnostic method, the use will be limited. However, before any noninvasive method is developed for evaluation of in vivo graft function or patency, intravascular ultrasound imaging may provide a direct method for observing the early changes in the graft from the intraluminal view. Intravascular ultrasound imaging also may be used as an adjunctive method during angiographic studies of graft patency.[6Buxton B.F. Raman J.S. Ruengsakulrach P. et al.Radial artery patency and clinical outcomes five-year interim results of a randomized trial.J Thorac Cardiovasc Surg. 2003; 125: 1363-1371Abstract Full Text Full Text PDF PubMed Scopus (150) Google Scholar]