Titanium-nickel intravascular endoprosthesis: a 2-year study in dogs

Twelve 5-mm-internal-diameter intravascular endoprostheses of noncorrosive, shape-memory titanium-nickel (TiNi) alloy were delivered transluminally by catheter and implanted in the iliac (n = 10) and femoral (n = 2) arteries of six normal dogs for either 1 or 2 years in order to evaluate the implantation technique and long-term effects. The patency rates were as follows: at 1 month, 92% (11/12); at 1 year, 100% 11/12 widely patent; 1/12 recanalized); and at 2 years, 100% (3/4 without stenosis; 1/4 with 20% stenosis). No migration, erosion, inflammation, surface thrombus, or stenosis of the side branches was seen; an absence of untoward angiographic and histopathologic effects was detected at 1 and 2 years. The neointima was completely endothelialized, without changes in thickness over time, 229.3 +/- 127.6 microns after 1 year and 223.3 +/- 216.7 microns after 2 years (p = not significant). The neointimal layer became thicker toward its distal aspect (p less than or equal to .05). Satisfactory delivery, long-term patency, and biocompatibility (manifested as a thin, stable neointima) were observed for the TiNi intravascular endoprosthesis at 1 and 2 years.