Brachytherapy for the prevention of neointimal hyperplasia in the canine inferior vena cava after stent placement.

The aim of this study was to evaluate the efficacy of brachytherapy for preventing neointimal hyperplasia in the inferior vena cava (IVC) after stent placement. Sixteen beagles underwent Z-stent placement in the IVC and the aorta. For 8 of 16 beagles, irradiation (15 Gy) was delivered endoluminally to the stented segments of each vessel immediately after stent placement using the 192Ir. All animals were sacrificed after 6 weeks for morphometric and histopathologic examination. Morphometrically, neointimal thickness in the IVC of the radiation group was significantly decreased compared with the control group as well as that in the aorta (p < 0.05). Histopathologic findings showed the neointima in the IVC of the control group contained markedly organization of thrombus and neovascularization though that in the IVC of the radiation group consisted mainly of smooth muscle cells without organization of thrombus and neovascularization. From these data intravenous irradiation may prevent clinical restenosis after stent placement.