Long-term effects of heparin on veins grafted into the common carotid arteries of rats--a scanning electron microscopic study

Abstract

Jump grafts made from veins with diameters of about 1 mm have very poor patency rates. Dissection and anastomosis damage the endothelia of the arteries and veins and expose collagen in the subendothelial layers of these vessels. Within 1 hr of the introduction of blood flow through the grafts, deposits of fibrin and platelets led to blockage of the grafts. In 9 rats, heparin was given intravenously about 0.5 hr before completion of the grafting procedure; heparin was also used to wash out the veins for grafting. In 11 rats, heparin was used only to wash out the veins for grafting. At periods 1-11 weeks later, the grafts were reexamined. All were patent except 1 from the first group, examined at 7 weeks, and 1 from the second group, examined at 10 weeks. Scanning electron microscopy showed that complete healing of the venous endothelium took several weeks. Heparin was equally effective in keeping the grafts patent when given intravenously and used locally or when only used locally. This study indicates, therefore, that long-term patency in small diameter vein grafts can be achieved merely by washing out the veins for grafting with a solution of heparin.