Morphological changes in aorto-coronary saphenous vein bypass grafts

Abstract

Before transplantation, saphenous veins show phlebosclerosis or other pathological changes. Therefore, surgeons should provide pathologists with a vein segment for control purposes. Following insertion, several changes occur in the vein wall. Despite initial reports, vein stenosis or occlusion caused by a florid proliferation of loosely arranged fibromuscular intimal tissue is uncommon. Its frequency diminished as surgeons learned to handle veins carefully. More often, in the first weeks after insertion, endothelial cells disappear and superficial medial cells die. Medial fibrosis and intimal proliferation follows, in part due to a reparative response and in part to blood flow through the lumen. Subsequently, the new intima condenses and matures. Small mural thrombi develop on the denuded intima immediately after insertion. They either lyse or become incorporated in the thickened intima. Occlusive thombi also occur. Lipid deposition in the intima of the vein is a late complication.