DIFFERENTIAL EFFECT OF THE RETROPLEURAL AND RETROPERITONEAL ENVIRONMENTS ON HEALING OF THE INNER WALL OF POROUS FABRIC PROSTHESES IN THE THORACIC AND ABDOMINAL-AORTA OF THE SAME DOG

Healing of the inner wall of the same preclotted knitted Dacron arteri al prostheses was compared in the descending thoracic aorta (DTA) and the abdominal aorta (AA) of the same dog. Each of 16 dogs received thi s dual implantation with study periods of 4 weeks for five dogs, 8 wee ks for five dogs, and 16 weeks for six dogs. Healing was studied with light microscopy, scanning electron microscopy, transmission electron microscopy, and immunocytochemistry identification. The outer capsule was firmly adherent to the Dacron framework of all grafts implanted in the DTA; advanced healing of the inner wall of all thoracic grafts wa s present by 4 weeks, nearly complete healing by 8 weeks, and complete healing by 16 weeks. In contrast, the outer capsule was either not at tached or only loosely adherent to the Dacron framework in eight AA gr afts (50%), and in these implants no healing of the inner wall occurre d beyond the limited perianastomotic pannus zone. In the other eight i mplants in which the outer capsule was firmly adherent to the Dacron f ramework, healing was roughly comparable to that in the grafts implant ed in the DTA. This study demonstrated that (1) DTA grafts heal faster and more completely than AA grafts, (2) healing and endothelializatio n are related to the tightness of the outer capsule, (3) there is a hi gh incidence of loose tissue attachment in the AA, and (4) healing of aortic grafts is site specific.