Effects of vascular stent surface area and hemodynamics on intimal thickening.

PURPOSE

To compare the in vivo response to a new mechanically expandable vascular stent with the response to an existing type of balloon-expandable stent.

MATERIALS AND METHODS

Prototype stents were deployed by means of a balloon catheter in the left iliac arteries of four healthy dogs. Palmaz stents were deployed in the contralateral iliac arteries to act as a control, and all stents were explanted after 6 weeks. Arteriography was performed at the time of insertion and before harvest, 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 Palmaz stent with respect to structural integrity, migration, maintenance of intraluminal diameter, ease of deployment, radiopacity, and pressure gradients. Unlike the Palmaz stent, the prototype stent did not foreshorten during expansion. The stents showed a lack of uniformity in terms of the measured luminal area and neointimal accumulation. Neointimal accumulation was more confined to the struts of the prototype stent; the lumen therefore had a fluted appearance. Neointimal accumulation was more broadly distributed around the circumference of the vessel wall of the Palmaz stent.

CONCLUSION

In vivo performance of the prototype stent was similar to that of the Palmaz stent. Stent geometry may be an important determinant of neointimal response and resultant long-term patency.