[Changes in the walls of autologous venous grafts after transplantation into arteries]

In 54 dogs 76 operations on plastics of the common carotid arteries with the femoral vein segments have been performed. The animals have been observed for 3 days--1.5 years. The grafts, preserving their permeability, have been studied using a complex of anatomical, histological and micromorphometric techniques. At early stages after the operation (up to 7 days), dystrophic and necrobiotic changes predominate in the wall of the venous graft. As a result of overstretching of the denervated and devascularized vessel, under the effect of a high arterial pressure, nearly total rejection of the endothelial lining takes place, as well as death of some smooth myocytes in the middle tunic; this determines appearance of early thromboses. During 2-6 months after the operation, against the background of a good revascularization of the graft, restorative and adaptive changes develop in its wall. The intima becomes thick at the expense of formation of the obliquely situating layer of myocytes, as well as the result of parietal thromboses organizing on the deendothelized internal surface. These thickenings are especially well seen in the zones of anastomoses. In 6 months--1.5 years after the transplantation into the artery, as a result of constriction of the vessels feeding the graft and reduction of blood stream along them, atrophic and sclerotic changes increase in the wall. The intimal thickenings often acquire the pattern of fibrous patches, that make the lumen more narrow; this can cause appearance of late occlusions and thromboses of the grafts.