Vascugraft® polyurethane arterial prosthesis as femoro-popliteal and femoro-peroneal bypasses in humans: pathological, structural and chemical analyses of four excised grafts

Following positive results obtained inin vitro studies andin vivo implantations in animals, a clinical trial using the Vascugraft® polyurethane arterial prosthesis as a below-knee substitute was undertaken in 15 patients. Eight grafts became occluded during the first year, and segments from four of them were explanted and made available for pathological, structural and chemical investigations. The implantation periods ranged from 21 to 358 days. Failures were associated with kinking (one case), possible anastomotic mismatch between the graft and the artery (one case), and poor run-off (two cases). No organized collagenous internal encapsulation was noted; however, endothelial-like cells were observed at the anastomotic site of one graft. No significant structural degradation of the prostheses was observed in those grafts implanted for 21, 38 and 46 days. Some deteriorations in the fibrous structure were observed on the external surface of the prosthesis implanted for 358 days. High-resolution carbon C1s analysis by ESCA demonstrated a 60 to 80% decrease in carbonate content on the surface of all explanted prostheses. Chemical analyses of each polyurethane graft by IR, SEC and DSC revealed no significant chemical changes. The clinical performance of the Vascugraft® prosthesis for below-knee implantation proved to be no more impressive than that of expanded polytetrafluoroethylene, the currently accepted reference. The decision by B. Braun Melsungen AG to end this program is therefore to be regarded as highly professional.