EFFECTS OF VASCULAR STENT SURFACE-AREA AND HEMODYNAMICS ON INTIMAL THICKENING

PURPOSE: To compare the in vivo response to a new mechanically expanda ble vascular stent with the response to an existing type of balloon-ex pandable stent. MATERIALS AND METHODS: Prototype stents were deployed by means of a balloon catheter in the left iliac arteries of four heal thy dogs. Palmaz stents were deployed in the contralateral iliac arter ies to act as a control, and all stents were explanted after 6 weeks, Arteriography was performed at the time of insertion and before harves t, and pressure gradients were measured across each stent. The stents were then harvested and submitted for histologic examination. RESULTS: The performance of the prototype stent was similar to that of the Pal maz stent with respect to structural integrity, migration, maintenance of intraluminal diameter, ease of deployment, radiopacity, and pressu re gradients. Unlike the Palmaz stent, the prototype stent did not for eshorten during expansion. The stents showed a lack of uniformity in t erms of the measured luminal area and neointimal accumulation. Neointi mal accumulation was more confined to the struts of the prototype sten t; the lumen therefore had a fluted appearance. Neointimal accumulatio n was more broadly distributed around the circumference of the vessel wall of the Palmaz stent. CONCLUSION: In vivo performance of the proto type stent was similar to that of the Palmaz stent, Stent geometry may be an important determinant of neointimal response and resultant long -term patency.