Improvement of haemocompatibility of metallic stents by polymer coating

An alternative to open heart surgery in treating arterial diseases causing restricted blood flow is the implantation of intracoronary metallic stents. In spite of the advances in implantation and in spite of the excellent mec hanical properties of metallic stents, there are still limitations because of the thrombogenicity of the metal. We have, hence, directed our attention to the coating of metallic stents with an ultrathin polymer layer by chemi cal vapor deposition (CVD) polymerization of 2-chloroparacyclophan. In a se cond step of surface modification the poly(2-chloroparaxylylene) layer is m odified by treatment with a sulfur dioxide plasma in order to obtain a more hydrophilic surface with new functional groups. The results demonstrate th e stable polymer coating of the stents and the improvement of haemocompatib ility after treatment with sulfur dioxide plasma. Platelet adhesion is decr eased from 85% for the metal surface to 20% for the CVD-coated and sulfur-d ioxide-plasma treated surface. (C) 1999 Kluwer Academic Publishers.