Effects of nitinol Strecker stent placement on vascular response in normaland stenotic porcine iliac arteries

PURPOSE: This experimental study was conducted to evaluate neointimal thick ness, lumen diameters, and histologic changes in normal and stenotic porcin e iliac arteries following placement of self-expanding nitinol Strecker ste nts, MATERIALS AND METHODS: Neointimal trauma causing slight vascular stenosis w as induced unilaterally within external iliac arteries of 12 swines by mean s of endothelial abrasion and high cholesterol diet. Nitinol Strecker stent s were placed within the stenotic and the normal contralateral vascular seg ments. For histopathologic evaluation, the pigs were killed 12 or 24 weeks after stent placement and luminal diamters were evaluated angiographically, RESULTS: Excluding one occlusion, 15% narrowing of the lumen diameter was i nduced unilaterally (P = .002), Initial luminal gain after stent placement was greater for stenotic than for normal arteries. The amount of neointima thickness was not different between stenotic and normal vessels (P > .05), Comparing vascular diameters before stent placement and at follow-up, lumin al loss due to neointima proliferation was 22% within normal arteries (P = .0002), while a luminal gain by 15% was found within the stenotic arteries (P = .008), Maturation of neointima and endothelial coverage were complete after 24 weeks. CONCLUSIONS: Even though nitinol Strecker stents induce excessive neointima l proliferation, stenotic arteries seem to profit from great early luminal gain resulting in 15% of vascular expansion at follow-up while slight steno sis is induced within normal iliac arteries.