Use of a radial artery graft may be reasonable when grafting left-sided coronary arteries with severe stenoses (>70%) and right-sided arteries with criti- cal stenoses (>90%) that perfuse LV myocardi- um.96 101 (Level of Evidence: B) Class III: HARM 1. An arterial graft should not be used to bypass the right coronary artery with less than a critical steno- sis (<90%).89 (Level of Evidence: C) Arteries (internal mammary, radial, gastroepiploic, and infe- rior epigastric) or veins (greater and lesser saphenous) may be used as conduits for CABG. The effectiveness of CABG in relieving symptoms and prolonging life is directly related to graft patency. Because arterial and venous grafts have differ- ent patency rates and modes of failure, conduit selection is important in determining the long-term efficacy of CABG. 2.1.4.1. Saphenous Vein Grafts Reversed saphenous vein grafts (SVGs) are commonly used in patients undergoing CABG. Their disadvantage is a de- clining patency with time: 10% to as many as 25% of them occlude within 1 year of CABG89,102,103; an additional 1% to 2% occlude each year during the 1 to 5 years after surgery; and 4% to 5% occlude each year between 6 and 10 years postoperatively.104 Therefore, 10 years after CABG, 50% to 60% of SVGs are patent, only half of which have no angiographic evidence of atherosclerosis.104 During SVG harvesting and initial exposure to arterial pressure, the endo- thelium often is damaged, which, if extensive, may lead to platelet aggregation and graft thrombosis. Platelet adherence to the endothelium begins the process of intimal hyperplasia that later causes SVG atherosclerosis.103,105 After adhering to the intima, the platelets release mitogens that stimulate smooth muscle cell migration, leading to intimal proliferation and hyperplasia. 