A new, all silicone rubber small vessel prosthesis

A new small vessel prosthesis composed entirely of silicone rubber was developed. The new prosthesis has a trilaminar wall structure consisting of: 1) a porous blood contacting layer designed to promote the deposition of a pseudoneointima (PNI) from blood flowing over the surface; 2) a solid middle layer the thickness of which is adjusted to provide approximately the same radial compliance as the host artery; and 3) a porous outer layer that promotes connective tissue attachment to the exterior of the prosthesis to limit tissue capsule formation around the implant and preserve its compliance after healing of the perigraft tissues. The new graft also has excellent suture retention in addition to its other desirable physical characteristics. The mechanical integrity of the textured surfaces was first evaluated in vitro with cyclic flexure testing at a 20-30% strain. Grafts of 4 mm inside diameter by 5 cm length were then implanted in the left carotid artery of adult dogs for an 8 week period. Seven animals were studied. Platelet inhibitors were administered postoperatively. The patency rate was 86% (six of seven); all grafts except the first remained widely patent. After the animals were killed, the grafts were surgically exposed, and compliance was measured directly. The PNI from the grafts was then studied with light and scanning electron microscopy, and morphometric measurements were made of PNI thickness over the length of the graft. Overall, the grafts retained 80% of their preimplant compliance (n = 5); however, in the absence of any postoperative complications such as hematoma or infection, the grafts remained essentially isocompliant with the host artery during the duration of this study.