NEO-ENDOTHELIALIZATION OF PTFE MICROVASCULAR GRAFTS - A 5-YEAR EXPERIENCE

This paper presents the results of a 5-year experience of the implanta tion of 1 mm diameter polytetrafluoroethylene (PTFE) prosthesis in rod ents. By evaluating the implanted grafts at different intervals, the p rocess of neo-endothelial healing can be divided into six phases: Plat elet Aggregation Phase (Stage I); Fibrin Network Phase (Stage II); Bri dging Phase (Stage III); Progression Phase (Stage IV-A); Transmural Mi gration Phase (Stage IV-B) (only in optimal grafts, with thin wall and long fibril length); Intimal Closure Phase (Stage V); and Endothelial Thromboresistance Phase (Stage VI). Grafts with 60 or 90 mu m fibril length offer enough ''anchoring space'' for the ingrowth of neo-endoth elium and they act as a framework for the neo-endothelial invasion. Fu rthermore, this type of material allows intramural migration and penet ration of cellular elements. In particular, a network of capillaries t raversing the graft wall and opening eventually on the luminal surface can provide multiple sources of neo-endothelium, contributing to the development of the inner neo-endothelial lining. Scanning electron mic roscopy can favourably assist in the evaluation of different types of PTFE grafts, with regard to their fibril length, diameter, and wall th ickness. (C) 1995 Wiley-Liss, Inc.