Comparison of Gianturco Z Stents and Wallstents in a Hemodialysis Access Graft Animal Model

Purpose: To compare the primary patency of two structurally different metallic stents in an animal model of hemodialysis access grafts. Materials and Methods: Nineteen synthetic femorofemoral arteriovenous shunts were created in 10 dogs. After a 1-month period of maturation (during which one graft thrombosed), stents were placed spanning the venous anastomosis. The grafts were divided into two treatment groups (Wallstent, n = 6, and Gianturco stent, n = 6) and a control group with no stent (n = 6). Fistulograms and pressure measurements were obtained at monthly intervals for 6 months or until thrombosis of the graft. Results: Mean graft patency in the Wallstent group (112 days ± 30) was significantly shorter than in the control (157 days ± 32, P < .03) or Gianturco (157 days ± 32, P < .05) groups. Patency in the Gianturco stent group was no different from that in the control group. Stenosis due to intimal hyperplasia within the stents appeared greater in the Wallstent group but did not achieve statistical significance. One Wallstent migration, three Gianturco stent shifts, and two Gianturco stent breakages occurred. Histologic examination revealed a necrotizing vasculitis in the portion of vein containing the stent in all grafts treated with the Gianturco stent but not in any other grafts. Conclusion: In an animal model of hemodialysis access grafts, the Gianturco stent had longer primary patency than the Wallstent when placed across the venous anastomosis. However, stent fractures and focal necrotizing inflammation may limit the use of the Gianturco stent in hemodialysis access.