Influence of Dexamethasone: Coated Nitinol Stent on Neointimal Formation in the Canine Great Vessel Model

Yoon, Hyun Ki; Park, Kil Sun; Kang, Sung Gwon; Park, Sang soo; Kim, Tae Hyung; Sung, Kyu Bo; Song, Ho Young

Abstract

PURPOSE: To evaluate the effect of dexamethasone(DM) and polyurethane(PU)-coated nitinol stent on neointimal formation in the canine great vessels.
MATERIALS AND METHODS
Thirty-six nitinol wire stents were implanted in the abdominal aorta and inferior vena cava(IVC) of six dogs. In each animal, six different types of stent (NC, non-coated; PU, polyurethane coated; DM, DM and polyurethane coated) were serially positioned in permutationally possible order in the aorta below the renal arteries and in the IVC below the renal veins. For DM stent an in-vitro drug release test was performed to determine the stability of DM release. The thickness of the intima and media of the aorta and of the intima of the IVC were measured three (n=3) or six months (n=3) after stent placement at and between the wires.
RESULTS
In the in-vitro study, 25% of DM was released during the first week, and the subsequent release rate was 3 microgram/day for 6 months. The intima-to-media ratio of DM-stented aorta was less than in aortas where PU or NC stents were used (p<0.05). The neointima thickness of DM stent in the IVC was less than that of PU stent (p<0.05). These differences were less prominent between the wires than at them, and there was no significant difference between the three-and six-month groups (p>0.05).
CONCLUSION
In this canine great vessel model, newly designed DM-coated nitinol stent decreased neointimal formation.