The porcine hemodialysis access model.

PURPOSE: To create a porcine hemodialysis access model that reliably reproduces intimal hyperplasia (IH) of the outflow vein similar to that which causes access failure in human patients undergoing dialysis treatments.
MATERIALS AND METHODS: Surgical technique for creation of side-to-side iliac-artery-to-ipsilateral-iliac-vein (IAV) native fistulas and IAV conduits was optimized in three standard-bred pigs. Persistent patency of fistulas and conduits was demonstrated in two additional pigs allowed to survive for 1 week. IAV fistulas and contralateral 2-cm polytetrafluoroethylene IAV conduits were created in five additional pigs. Venous outflow from these fistulas and conduits was evaluated with venography and intravascular ultrasound (IVUS) immediately after creation (day 0) and at 2-week intervals for as long 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 histologically.
RESULTS: IAV native fistulas remained patent until the animals' death and conduits 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 pig. At 42-64 days, venography demonstrated maximum fistula outflow vein diameter 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%, respectively. Three of five conduits occluded, one before 16-day follow-up, one between 14 and 28 days, and the other after 42 days. Histologic sections demonstrated IH predominantly affecting the veins at the anastomoses and central (cephalad) to the anastomoses in all pigs.
CONCLUSION: This porcine model reproduces IH in the fistula or conduit outflow vein with measurable stenosis. Such a model might allow relevant preclinical evaluation of interventional devices and techniques intended to reduce the effects of IH in human patients undergoing dialysis treatments.