The spectrum of pathologic changes in aortocoronary saphenous vein grafts.

Aortocoronary vein grafts removed at autopsy of 182 patients who died up to 5 years after the bypass operation were examined by light and electron microscopy. During the first month after surgery, graft occlusion was due to thrombi, some of them recent, some organized and recanalized. Intimal proliferation of the graft first appeared 4 weeks after the bypass surgery; several cases of total occlusion of the lumen by this process were seen within 6 months of the operation. A change in the morphological features of the intimal thickening from cellular to fibrotic and hylain-like was observed in several grafts implanted for more than 1 year. Typical atherosclerosis developed in vein grafts in three of the six patients surviving the operation for more than 3 years.