The porcine hemodialysis access model

PURPOSE: To create a porcine hemodialysis access model that reliably reprod uces intimal hyperplasia (IH) of the outflow vein similar to that which cau ses access failure in human patients undergoing dialysis treatments. MATERIALS AND METHODS: Surgical technique for creation of side-to-side ilia c-artery-to-ipsilateral-iliac-vein (IAV) native fistulas and IAV conduits w as optimized in three standard-bred pigs. Persistent patency of fistulas an d conduits was demonstrated in two additional pigs allowed to survive for 1 week. IAV fistulas and contralateral 2-cm polytetrafluoroethylene IAV cond uits were created in five additional pigs. Venous outflow from these fistul as and conduits was evaluated with venography and intravascular ultrasound (IVUS) immediately after creation (day 0) and at 2-week intervals for as lo ng as 64 days. Animals were killed at 30 days (n = 1), 42 days (n = 2), or 64 days (n = 2), and the arteries, veins, and conduits were evaluated histo logically. RESULTS: IAV native fistulas remained patent until the animals' death and c onduits remained patent for at least 14 days in four of five pigs; both the fistula and conduit likely occluded before 16-day follow-up in the fifth p ig. At 42-64 days, venography demonstrated maximum fistula outflow vein dia meter stenoses of 53%-76% and maximum conduit outflow vein stenoses of 44%- 84%, and IVUS demonstrated maximum area stenoses of 64%-86% and 43%-82%, re spectively. Three of five conduits occluded, one before 16-day follow-up, o ne between 14 and 28 days, and the other after 42 days. Histologic sections demonstrated IH predominantly affecting the veins at the anastomoses and c entral (cephalad) to the anastomoses in all pigs. CONCLUSION: This porcine model reproduces IH in the fistula or conduit outf low vein with measurable stenosis. Such a model might allow relevant precli nical evaluation of interventional devices and techniques intended to reduc e the effects of IH in human patients undergoing dialysis treatments.