The current status of in vivo screening of synthetic implant materials for blood compatibility

There are currently a number of in vivo and in vitro methods for evaluating the potential thromboresistance of various biomaterials. It is felt that in vivo techniques offer more accurate information in this regard and that implantation of prosthetic rings in the canine thoracic vena cava is currently the most satisfactory in vivo test. A number of thromboresistant materials have been evaluated with the caval ring test by the authors over the past several years, and 17 of the more promising materials are presented in this report. The surfaces of these materials seem to fall into three major categories: heparinized surfaces; surfaces with anionic radicals or imposed negative electrical charges; and surfaces of relatively inert materials. There are some extremely promising materials in each of these categories that seem to have application in the fabrication of prosthetic devices.