External-beam radiation therapy for improved dialysis access patency: Feasibility and early safety

Prosthetic dialysis access grafts fail secondary to neointimal hyperplasia at the venous anastomosis. We hypothesized that postoperative single-fracti on external-beam radiation therapy to the venous anastomosis of hemodialysi s grafts can be used safely in an effort to improve access patency. Dogs (n = 8) underwent placement of expanded polytetrafluoroethylene grafts from t he right carotid artery to the left jugular vein. Five dogs received single -fraction external-beam photon irradiation (8 Gy) to the venous anastomosis after surgery. Controls were not irradiated. Shunt angiograms were complet ed 3 and 6 months postoperatively. Anastomoses, mid-graft, and the surround ing tissues were analyzed. Immunohistochemistry for smooth muscle cell alph a -actin, proliferating cellular nuclear antigen (PCNA), and apoptosis was performed. Incisions healed well, though all animals developed wound seroma s. One control suffered graft thrombosis 4 months postoperatively. Angiogra phy/histology confirmed severe neointimal hyperplasia at the venous anastom osis. The remaining seven dogs developed similar amounts of neointinal hype rplasia. PCNA studies showed no accelerated fibroproliferative response at irradiated anastomoses compared to controls. Skin incisions and soft tissue s over irradiated anastomoses revealed no radiation-induced changes or incr ease in apoptosis. Thus we conclude that postoperative single-fraction exte rnal-beam irradiation of the venous anastomosis of a prosthetic arterioveno us graft that mimics the situation in humans is feasible and safe with rega rd to early wound healing. (C) 2001 by Radiation Research Society.