Die Effektivität von Hirudin-Iloprost beschichteten PTFE-Bypässen im Tiermodell

Objectives: To study the efficiency of hirudin-iloprost coated small caliber PTFE prostheses. Material: 30 femoro-popliteal grafts with a diameter of 4 mm and a length of 8 cm were inserted into 15 pigs. The PTFE prostheses were either uncoated (group I, n = 10), coated with a layer of poly-lactic acid (Poly-(D,L)-Laktid, PDLLA, group II, n = 8) or coated with PDLLA releasing recombinant hirudin (lepirudin) and the prostacyclin analogue iloprost (group III, n = 12). Individual grafts were assigned after randomization. The follow-up period was 6 weeks. Blood flow was measured intraoperatively before implantation of the grafts and immediately before graft removal. The grafts were excised following perfusion fixation applying a perfusion pressure of 100 mm Hg. Patency rates were calculated and development of pseudointima inside the grafts was noted. Results: Patency rates for native PTFE were 70%, for PDLLA coated grafts 87% and for hirudin-iloprost PDLLA prostheses 100%. Mean blood flow before graft implantation was 105 ±2 ml/min (p =n.s.). The blood flow before graft removal differed significantly. The mean pre-explantation flow rates were 29 ± 5 ml/min for group I, 28 ± 8 ml/min for group II and 98 ± 6 ml/min for group III (p < 0,01). The low flow rates in groups I and II correlated with a subtotal stenotic grafts due to pseudointima development. Conclusions: The hirudine-iloprost coating of PTFE prostheses effectively prevents the pseudointima development and leads to superior graft patency in a pig model.