Factors influencing patency of saphenous vein grafts.

To determine factors affecting saphenous vein graft patency, 218 grafts in 66 unselected patients were studied angiographically 1 year after operation. Fourteen variables were extracted from the angiograms, electrocardiograms, and intraoperative flow measurements to assess their predictive value. Preoperative coronary vessel diameter and degree of proximal stenosis measured angiographically correlated significantly with graft patency. Graft patency for vessels greater than 1.5 mm in diameter with greater than 70% stenosis was 93% (98 out of 105). Vessel size at operation and the presence of reactive hyperemia greater than 20 ml per minute also correlated significantly with graft patency. Reactive hyperemia increased significantly as the severity of the vessel stenosis proximal to the graft increased, thus suggesting a mechanism for the improved patency rate of grafts to more stenotic vessels. The patency rate of the end-to-side component of a continuity graft (left anterior descending coronary artery and diagonal or marginal artery in 1 graft) was 100% and of the side-to-side component, 77%. This study shows that the patency rate for saphenous vein grafts compares favorably with the reported patency for internal mammary grafts when critical factors such as vessel size (greater than 1.5 mm) and degree of stenosis (greater than 70%) are considered in bypass selection.