ABSTRACT
Eleven models of expanded PTFE arterial prostheses were implanted as infrarenal aortic substitutes in dogs to determine how the modifications in the structure of the grafts influence the healing characteristics. The eleven types included homogenous, reinforced, ringed and reinforced, helix-supported, double-helix-supported, graphitelined, helix-supported graphite-lined and doublelayered designs. They were implanted for predetermined periods ranging from 4 hours to 6 months, to demonstrate different sequences of healing. Scanning electron microscopy showed that, in all graft structures, the endothelialization of the luminal surface of the grafts never extended more than a few millimeters from the anastomoses. Light microscopy demonstrated that the double-layered model experienced the fastest and most extensive fibrous tissue incorporation compared to the other models that showed less fibrous tissue infiltration. The helix external support model showed considerably reduced penetration of blood elements and, thus, fibrous tissue proliferation: the structure of the wall is compressed, resulting in a structure that is less porous and less likely to heal. These results are reported as part of our ongoing program to characterize the arterial substitutes.
