Stents coated with hypothrombogenic amorphous silicon carbide - preliminary results in the New Zealand White Rabbit

For an increasing number of indications coronary artery stent implantation has become an established treatment modality, which is still hampered by a considerable restenosis rate. Hypothrombogenic silicon carbide coated on st ents may reduce recurrence rates owing to its electrochemical properties. T his trial addressed the histologic reactions to silicon carbide coated sten ts in the animal model. Seventeen slotted tubular tantalum stents coated with the hypothrombogenic amorphous silicon carbide were implanted into the iliac arteries of 9 New Z ealand White Rabbits for an observation period between 4 and 26 weeks. To r educe thrombosis, aspirin (6 mg/kg/day) was given i. m. After sacrificing t he animals, the specimens were harvested, fixed in formalin, processed in p araffin, and stained (H&E, trichrome). Immunohistologic stains for the asse ssment of mitotic activity were performed by means of Ki67 (MiBI) and CD31, Stent implantation was complicated by guide wire dissection, stent bucklin g and hypohydration in three animals, Fourteen implantations were uneventfu l. After four weeks all of the stents were covered by an endothelial layer. Mitotic activity (1.5 +/- 1.6%), intimal thickness increase (44.9 +/- 9.9% ), increase of connective tis sue (20.1 +/- 9.1%), and lumen reduction (15. 8 +/- 4.7%) were considerably less in comparison to previous studies with o ther stents, It is concluded, that in stents coated with the hypothrombogenic amorphous silicon carbide, the induction of mitotic activity of fibroblasts, intimal thickness, and connective tissue increase is limited when being deployed in the rabbit. The possible benefit in man awaits the results of clinical tri als.