Histological features of a polymer endovascular prosthesis after transcatheter implantation in porcine arteries

A novel approach for the treatment of acute complications and the prevention of restenosis after percutaneous transluminal angioplasty may be the placement of endovascular prostheses (stents). Stents constructed of metal have proven to be thrombogenic, and although they show a tendency to reduce restenosis, they do not prevent it. Pursuant to the search for stents with improved material and surface characteristics, we report in this paper the histological results obtained with a synthetic polymer (polyethylene terephthalate) stent after placement in porcine peripheral arteries. Eight stents were placed at a preselected site and resulted in a 87.5% angiographic patency rate at four weeks' follow-up examination. The neointima measured 114 ± 38 μm (mean ± SEM) on top of the fibers and 246 ± 44 μm between the fibers. Medial impression by the stent measured 27% ± 5%. The neointima consisted mainly of smooth muscle cells. A variable inflammatory reaction and foreign body response to the polymer was observed in all vessels. The present study shows the feasibility of the arterial implantation of polymer stents, in that they result in good intermediate-term arterial patency and limited neointimal hyperplasia. The observed inflammatory reaction, if prolonged, may limit the use of this polymer stent.