Coronary artery bypass graft patency and competitive flow.

ver since the observation by Loop et al. (1) that internal horacic arteries (ITA) are more effective coronary artery ypass grafts than saphenous veins in prolonging patient urvival and preventing recurrent ischemic events, cardiohoracic surgeons have tried to improve the results of urgical revascularization by using other arteries as bypass onduits, such as the gastroepiploic, radial, and inferior pigastric arteries (2–4). The better patient outcomes oberved with ITA grafts are related to their excellent longerm stable patency (5). Saphenous vein graft patency is not table; it declines with time from development of vein graft rteriosclerosis. From 1 to 5 years after surgery, saphenous ein grafts occlude at a rate of 1% to 2% per year, ccelerating to 4% to 5% per year by 6 to 10 years. By 10 ears, only 50% to 60% of these grafts are patent, and only ne-half of these are free of angiographic arteriosclerosis (6,7). nlike saphenous veins, ITA grafts rarely develop arterioscleosis ( 4%), and only 1% develop important arteriosclerotic uminal narrowing (8). This resistance to arteriosclerosis results n 90% of ITA grafts being patent 10 years after surgery (5,6). urgeons have hoped that other arterial grafts would behave imilarly.