Immunohistochemical analysis of vascular prostheses implanted with the left ventricular assist system

Background: Dacron vascular pros-theses are associated with thromboembolic complications and inflammatory responses; impregnation with bovine collagen reportedly stimulates additional inflammatory/immunologic complications. T he Novacor (Baxter Healthcare Corp., Oakland, CA, USA) left ventricular ass ist system uses Dacron inflow and collagen-impregnated Dacron outflow prost heses. Methods: Explanted inflow and outflow prostheses were evaluated for inflamm atory/immunologic, hemostatic, anticoagulant, and fibrinolytic pathways. No n-implanted prostheses immersed in whole blood or plasma were used as contr ols. Results: Immunoglobulins and complement components were observed in all pro stheses with activated macrophages being present only in implanted prosthes es; Antithrombin III was observed in all prostheses whereas fibrin, tissue plasminogen activator, and alpha-2 plasmin inhibitor were present only in i mplanted prostheses. Endothelial and smooth muscle cells associated with Va scular structures containing collagen type IV and laminin were observed sol ely in implanted prostheses. Conclusion: An inflammatory response occurs and key components of hemostati c, anticoagulant, and fibrinolytic pathways are present within implanted pr ostheses. These processes are accompanied by endothelial and smooth muscle cell infiltration which appear to lay the foundation for neovessel developm ent.