Natural Antithrombogenic Surface Created In Vivo for an Artificial Heart

Abstract

Thromboses and embolisms arising from the prosthesis surface are among the most significant problems in artificial hearts. Although antithrombogenic polymer materials have been developed to prevent thrombus formation, they have problems in long-term applications. While the natural antithrombogenicity of endothelial cells is reliable, development of the cell lining requires long periods after implantation. To overcome this problem, we developed a method to obtain rapid endothelialization by seeding autologous venous tissue fragments. The rate of endothelialization and the antithrombogenicity were evaluated in a small-diameter vascular graft treated by this method. A canine jugular vein was minced and suspended with heparin. This was sieved through the wall of a fabric prosthesis by pressurized injection, causing tissue fragments to be trapped in the graft wall. Twenty out of 32 grafts were patent up to 400 days, while all 12 control fabric grafts with preclotting were occluded. The luminal surface at 1 h showed no thrombus deposition. At 1 month, complete endothelialization was noted. There were no degenerative changes in any neointimae of the explanted grafts. These results indicated that heparin reduces the thrombogenicity of collagen by electrostatic binding during endothelialization, and that a natural antithrombogenic surface can be obtained by this method within a short period.