[Histological study of saphenous vein graft disease after coronary artery bypass grafting].

In an attempt to determine the cause of pathological changes in saphenous vein grafts arising months or years after coronary artery bypass surgery, we studied 13 patients who underwent reoperation 7 months to 12 years after the first surgery. Four of 17 grafts occluded early in the postoperative period. In these four cases, only thrombosis was observed in the graft lumen, and there were no marked changes in the graft wall. The 13 grafts occluded in late postoperative period exhibited two significant pathological changes. One was fibrointimal proliferation, which was found to some extent in all 13 grafts. However, it was thought to be the cause of occlusion in only one case. This fibrointimal proliferation was interpreted as a remodeling process associated with arterialization of the vein graft and occasionally causing graft occlusion. The other long-term pathological change, observed in 11 grafts, was atherosclerosis. Atherosclerotic changes significantly contributed to the development of occlusive and stenotic lesions and are suspected to be a major cause of late saphenous vein graft deterioration. In conclusion, fibrointimal proliferation and atherosclerosis are different pathological process, and it is important to distinguish between them in the evaluation of saphenous vein graft disease.