Abstract:
Intraluminal irradiation has been shown to decrease neointimal proliferation after angioplasty in experimental models and clinical trials. The purpose of this study was to investigate the biological effects and the dose effect of 186Re stents on intimal hyperplasia in a rabbit model.
Thirty-five New Zealand White rabbits were fed a 0.5 cholesterol diet before balloon angioplasty and insertion of Palmaz stents in the infrarenal aorta. Thirty-three animals were killed 7 weeks after stent implantation (control stents [n=7], 2,58 MBq [n=6], 8,07 MBq [n=6], 15,98 MBq [n=6], 25,80 MBq [n=8]). Two rabbits from the highest dose group were killed 23 weeks after stent implantation (25,80 MBq [n=2]).
After 7 weeks, neointima formation was 2,20 ± 0,86 mm2 in the control group. In the treatment groups, a dose-dependent neointima reduction was detectable (0,52 ± 0,55 mm2 [2,58 MBq]; 0,36 ± 0,53 mm2 [8,07 MBq] and 0,0 mm2 [15,98 MBq and 25,80 MBq]). No intimal hyperplasia was observed in the 25,80 MBq long-term group. 186Re stents did not cause late thrombosis or neointimal induction at the stent margins. Radiation resulted in delayed reendothelialization.