Artificial heart valves: improved blood compatibility by PECVD a-SiC:H coating

Implants are steadily increasing in importance as substitutions for body functions. With the present state of the art, the limitations of the application of cardiovascular implants are due to insufficient performance of biomaterials. Present research in this field is being concentrated on efforts to improve the thrombus resistance of conventional materials by coating with semiconducting materials to actively influence the electrochemical interaction between the condensed matter and blood proteins. Based on an electrochemical model of the interaction of fibrinogen with an artificial surface and the resulting requirements for improving hemocompatibility, a coating of amorphous hydrogenated silicon carbide deposited by plasma-enhanced chemical vapor deposition (PECVD) is presently under evaluation as a special coating material for cardiovascular prostheses and is herein described. In particular, first results are published concerning the optimum deposition parameters in the PECVD process and cell culture tests. Experimental results of comparative partial thromboplastin time studies serve the purpose of proving the validity of the electrochemical reaction model referring the hemocompatibility of implantable materials to their semiconducting surface properties. The aim of this article is to demonstrate a feasible method for an antithrombogenic surface modification based on doped amorphous silicon carbide films that is in full conformance to the above mentioned model.