[Experimental evaluation of Vitaflon grafts in the venous position]

To examine the possibilities of replacing the great veins by Vitaflon grafts, an experimental study was made on 20 dogs. In the first group animals (n=10), a segment of the infrarenal posterior vena cava was replaced under conditions of routine blood flow. In the second group (n=10), an arteriovenous fistula closed after one month was formed on the thigh. The graft patency was checked by ascending phlebography. The observation period varied from 5 days to 11 months. After the animals were taken out of the experiment the grafts were inspected macro- and microscopically. It has been established that under conditions of routine blood flow all Vitaflon grafts were thrombosed for the first week. Acceleration of the flow provided for the patency of 10 grafts. The patent grafts took by means of formation of a connective tissue capsule on the exterior and formation of the neointima on their internal surface. The external capsule from the friable connective tissue emerged on the 2nd week of experiment; after 11 months it appeared as a thin layer of the solid fibrous connective tissue without evidence of inflammation which indicated the high biological inertness of the given type grafts. The neointima was formed from the parietal layer of fibrin organized in the direction from the area of anastomoses to the medium graft portion. No complete was recorded toward the end of experiment.