Late neointimal tissue growth behind the stent after intravascular gamma-radiation.

To determine the nature of the changes of the vascular wall after intravascular brachytherapy in stented arteries leading to incomplete stent apposition.Stents were implanted in the infrarenal aortas of rabbits, and gamma-intravascular brachytherapy (18 Gy) or a sham radiation procedure was immediately implemented. The arteries were harvested at 6 months for histologic analyses.The external elastic lamina area, as well as the vascular wall area behind the stent, were significantly greater in irradiated vs. control arteries (8.94 +/- 0.68 mm2 vs. 6.87 +/- 0.40 mm2 [p0.001] and 1.56 +/- 0.13 mm2 vs. 0.72 +/- 0.07 mm2 [p0.001], respectively). The ratio of the intimal area behind the stent rela…