Why do radial artery grafts for aortocoronary bypass fail? A reappraisal.

The reasons for the high failure rate of radial artery grafts for aortocoronary bypass (ACB) are appraised. Each of 11 dogs received four types of grafts: femoral arteries were grafted to carotid arteries, and jugular veins were grafted to femoral arteries bilaterally. One of each pair of grafts was wrapped in a plastic sheet in order to interfere with the regeneration of vasa vasorum. The grafts were examined 2 months later. The results suggest that although operative trauma and intraluminal pressure change play important roles, the thick-walled artery appears to depend more on vasa vasorum for its integrity than does the thin-walled vein. A free radical artery graft, with vasa vasorum disrupted at both ends, cannot regenerate readily from the adjacent tissue, as is the case at the ACB position, and is therefore more vulnerable to subintimal hyperplasia and occlusion than either the vein graft or the internal mammary artery graft; both of these grafts are thinner, and the internal mammary artery graft remains undisrupted at one end.