Reaction of connective tissue of arterial and venous walls to implantation of synthetic and biological grafts

Abstract

30% of patients in the remote period appear to develop restenosis of the anastomoses formed during reconstructive-restorative operations on vessels. Two major causes of restenosis have been determined: intimal hyperplasia and smooth muscle cell proliferation. The reaction of connective-tissue elements of vascular walls in response to implantation of grafts remains unstudied. The study was undertaken to examine the reaction of connective tissue of the arterial and venous walls to implantation of synthetic and biological grafts. We analysed the results of an experimental study performed on a total of 60 rabbits divided into 4 groups each consisting of 15 animals: in the first 2 groups we examined tissue reaction to implantation of synthetic and biological grafts on the wall of an artery and in the remaining 2 groups - on the wall of a vein. The synthetic grafts were made of polytetrafluoroethylene, with the biological ones made of bovine internal thoracic arteries. The portions of the vessels along with the implanted grafts were subjected to histological examination on postoperative days 14, 21 and 30. The specimens were studied by means of light microscopy after haematoxylin-eosin staining. We also carried out a morphometric study consisting in determining the quantitative ratio of the cellular composition of connective tissue. After implantation on the arterial wall, the connective-tissue capsule under the synthetic prosthesis was 1.8 times thicker than under the biological one, with predominance of the cellular component over fibrous one, which deformed the zone of implantation. Under the biological prosthesis, the capsule on the arterial wall was presented by fibrous structures with no deformation of the zone of implantation. The reparative reaction of the venous wall to implantation of the synthetic prosthesis was represented by a thin fibrous connective-tissue capsule. The reaction of the venous wall to the biological transplant was at all terms of the experiment characterised by significant inflammatory alterations with granulomatosis and immunomorphological shifts with formation of lymphoid follicles on the border with the transplant. Implantation of the synthetic polytetrafluoroethylene prosthesis on the arterial wall induced a hyperplastic reaction of the elements of connective tissue, and a normoplasic one on the venous wall. Implantation of the biological prosthesis on the arterial wall did not induce proliferation of connective-tissue elements, and on the venous wall - granulomatous inflammation.