Local Application of Beta-Particle Radiation to Reduce Venous Anastomotic Intimal Hyperplasia in Polytetrafluoroethylene Arteriovenous Fistulas

Abstract

The long-term patency of arteriovenous fistulas (AVF) created for hemodialysis is limited, especially when prosthetic implants such as polytetrafluoroethylene (PTFE) are used. Since intimal hyperplasia (IH) at the venous anastomosis is the most common cause of AVF demise, a therapeutic technique to safely diminish this hyperplastic response would be valuable to dialysis patients. Recently, pure beta-emitting stents were shown to be effective in decreasing IH in coronary arteries after angioplasty. This study was designed to assess the ability of a newly developed beta-emitting external foil to inhibit IH at the venous anastomosis in PTFE AVFs in a canine model. Bilateral PTFE bridge graft AVFs were placed from the femoral artery to vein in adult mongrel canines. A metallic stainless-steel foil coated with the beta-emitter rhenium 188 was placed around the venous anastomotic site of one AVF in each animal. Twelve weeks after AVF implantation each animal was sacrificed and samples of each anastomosis analyzed histologically. Eight venous anastomoses were analyzed (four test and four control). An analysis of neointimal hyperplasia was performed with image analysis software. Although not statistically significant, there was a trend toward diminished IH observed in the irradiated versus control anastomoses (132.36 ±36 μ vs 159 ±22 μ). However, a foreignbody response was noted external to the vein and anastomosis on the implant side, leading to decreased diameter in the irradiated versus control veins (1.52 ±0.21 mm vs 3.80 ±1.02 mm). Venous IH may be attenuated in canine PTFE AVFs with the use of an external betaemitting foil. Further larger studies to determine the ideal dosimetry and implant material to maximize vein contact yet minimize foreign body response are necessary. This technology could result in a safe and effective way to improve performance in AVFs.