Brachytherapy for the prevention of stenosis in a canine hemodialysis graft model: Preliminary observations

PURPOSE: To determine whether gamma brachytherapy can prevent in-stent sten osis in hemodialysis grafts. MATERIALS AND METHODS: Six-millimeter polytetrafluoroethylene arteriovenous grafts were created bilaterally in six dogs. After 1 month, Wallstents spa nning the venous anastomosis were placed to accelerate restenosis. Gamma ir radiation (12 Gy) was delivered endoluminally to one of the two grafts by u sing an iridium 192 source; -thus, each animal served as its own control. F istulography was performed monthly for 10 months or until graft thrombosis, with measurement of stenosis at each time point. At the conclusion of the study period, the treated area was examined histologically, and a computer model was used to calculate the volume of intimal hyperplasia. RESULTS: Delayed stent migration resulted in exclusion of one dog. In the r emaining five dogs, maximum stenosis across all time intervals was less for the treated side (P <.04), and the volume of intimal hyperplasia was less for the treated ride (P <.045). In one animal studied at 1 year, this trend reversed in terms of percentage stenosis but not total neointimal volume. CONCLUSION: Brachytherapy with (192)lr (gamma) delivered at the time of ste nt placement reduces restenosis in-this hemodialysis graft model, but, depe nding on the parameter evaluated (stenosis vs total volume of neointima), t he benefit may wane or even reverse with time.