A new rat model of small vessel stenting

Objectives: Restenosis is the major complication of coronary angioplasty an d stenting. In addition, the small vessel diameter represents a major limit ation to the wide use of the technology. The aim of this study was to asses s the feasibility and the vascular response of stent deployment in rat smal l vessels. Methods: In 40 Wistar rats (500-550 g) a Nir stent crimped on a 1.5 mm Come t angioplasty balloon catheter was deployed at high pressure in the common carotid artery. Neointimal area, neointirna/media ratio and the arterial di mension were assessed immediately and at 7, 14, 21, and 28 days after stent ing. Results: After stent deployment, the neointimal area and the neointima/medi a ratio increased progressively and peaked at 14 days (p < 0.05 vs 0 and 7 days). Alpha-actin-positive cells were found circumferentially organized on the lumen surface. At 21 and 28 days after stenting, the neointima and the neointima/media ratio were not statistically different compared with the r esults obtained fourteen days after stent deployment. Mo significant differ ences in the area of external elastic lamina were observed during the study period. In contrast, the internal lumen area was reduced significantly at 14, 21, and 28 days after the stent deployment. Subacute thrombosis rate af ter stent implantation was 26.5%. Conclusions: The results of this study demonstrated that the balloon expand able stents can be safely placed into rat arteries and the reduction of the internal arterial lumen observed after stent deployment was only due to th e neointima formation whereas remodeling did not occur.