Carbon-coated stents implanted in porcine iliac and renal arteries: Histologic and histomorphometric study

PURPOSE: To test in a pig model the biocompatibility and effectiveness of carbon-coated renal and iliac artery stent systems during implantation procedures and at different follow-up periods. MATERIALS AND METHODS: Twenty-two miniature pigs received carbon-coated balloon-expandable stainless-steel stents in their renal and iliac arteries. Animals were killed at 7, 30, or 180 days for evaluation of acute, subacute, and chronic biologic response to the implanted devices. Histologic, histomorphometric, and scanning electron microscopy (SEM) analyses were performed to assess inflammatory reaction, endothelialization process, and neointimal growth. RESULTS: Forty-four iliac stents and 42 renal stents were successfully implanted. Mural thrombi were not observed by angiography or histologic examinations. Histologically, no significant inflammatory reaction was detected: the stents appeared covered by a thin monolayer of endothelial cells even at 7-day follow-up. The neointima showed homogeneous growth and moderate thickness at 30-day and 180-day explantations (0.09 mm +/- 0.06 and 0.15 mm +/- 0.13, respectively, for renal arteries; 0.12 mm +/- 0.04 and 0.21 mm +/- 0.12, respectively, for iliac arteries). Internal and external elastic laminae were intact in 82 of 86 cases (95%) of stent-implanted arteries. Histologic validations were obtained with SEM observations for each follow-up group. CONCLUSIONS: This study showed good technical results of deployment of carbon-coated renal and iliac stents and very satisfactory biologic behavior in terms of tissue and hematologic compatibility. The devices do not induce thrombus formation.