Endothelialization of biosynthetic vascular prostheses after laser perforation

Objective. This study was undertaken to investigate the feasibility of tran smural capillary ingrowth into the inner surface of biosynthetic vascular p rostheses (Omniflow, BioNova, Melbourne, Australia) through perforations cr eated by an excimer laser, thus inducing an endothelial cell coverage. Method. Biosynthetic vascular prostheses (Omniflow, 10 cm length, 6 mm diam eter) were perforated with an excimer laser (diameter of the holes 50 to 10 0 mu m, distance 4 mm) and implanted into the carotid arteries of eight she ep. They were compared to untreated Omniflow prostheses implanted at the co ntralateral side. Three months after implantation the prostheses were expla nted and evaluated by gross morphology, histologic examination, scanning el ectron microscopy, and immunohistochemical staining for factor VIII to iden tify endothelial cells. Results. All grafts remained patent. Gross morphologic examination revealed no significant difference in the thrombus-free surface between perforated and untreated prostheses. However, scanning electron microscopy showed endo thelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork, and activated platelets formed the inner layer in six of eight untreated Omniflow prostheses. Transmural capillary ingrowth in the laser group was verified by positive factor VIII staining f or endothelial cells in the laser channels. Conclusion. Spontaneous endothelialization of biosynthetic vascular prosthe ses can be achieved by transmural capillary ingrowth through perforations i n the wall of the prostheses in an experimental sheep model. (C) 1998 by Th e Society of Thoracic Surgeons.