Studies of the modified venous allograft.

Segments of rat inferior vena cava were modified by proteolytic digestion and dialdehyde starch tanning in an attempt to alter their antigenic nature and increase their tensile strength. These tissues were found to retain their ability to sensitize allogeneic recipients in both the intradermal and intra-aortic positions in all 50 experimental animals. Furthermore, these grafts had a very high aneurysm formation (100%), and aneurysm rupture (54%) rate even in isogeneic recipients, suggesting that the modification procedure so damages the structural integrity of venous tissue that its use in clinical situations may have disastrous consequences. Histologic evidence of intimal thickening, elastic disruption, and often severe acute and chronic inflammation supported the gross evidence of mechanical and immunologic damage and suggests that a mild brief course of immunosuppression may be indicated in clinical trials in situation in which autogenous saphenous vein in unavailable. Although the use of prosthetic mesh support for the graft may help to avoid structural changes, the introduction of synthetic materials may offset the theoretical advantages of the venous tissue.