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Healing Pattern of Collagen-Impregnated and Preclotted Vascular Grafts in Dogs

To eliminate the need for preclotting dacron fabric vascular grafts, collagen- impregnated microvel double velour vascular grafts were used. Twelve mongrel dogs were implanted in the thoracic aorta with collagen-impregnated pros theses, in the form of a loop, 28 to 38 cm long and 8 mm in diameter. Four identical prostheses were preclotted and served as controls. The prostheses were harvested from two to 216 days postoperatively and the healing pattern was determined by histology and scanning electron micrograph methods. At the time of implantation, none of the collagen-impregnated prostheses bled through the wall and all remained patent. The authors established that the collagen- impregnated prostheses healed markedly faster, as documented by the signifi cantly larger area covered by neoendothelial cells and the significantly greater incidence of vasa vasorum along the grafts implanted for a period ranging from eighty-one to ninety-nine days. The study documents the close association be tween the rate of neoendothelialization and the number of microvessels in the healing prosthesis. The authors conclude that collagen-impregnated microvel double velour vascular grafts prevent bleeding through the wall and enhance the rate of the healing without induction of fibrotic changes.