TISSUE-RESPONSE TO COVERED WALLSTENTS

PURPOSE: To evaluate and compare the healing response related to two t ypes of graft-covered Wallstents (WSs) and an uncovered WS in the cani ne iliac artery,MATERIALS AND METHODS: Eight bare mesh WSs, 10 polyeth ylene terephthalate interbraided WSs (PET-WSs), and six polytetrafluor oethylene covered WSs (ePTFE-WSs) were placed in the iliac arteries of 12 dogs. Arteriograms were obtained before and, after implantation an d at explantation. Devices were explanted at 1 month (n = 8), 3 months (n = 6), and 6 months (n = 10) and sent for histologic study. RESULTS : One ePTFE-covered stent-graft was found to be thrombosed at 3 months ; the remaining 23 of 24 implants remained patent to the time of expla ntation, The WS and ePTFE-WS both generated a uniform myointimal cell response without inflammation. The PET-WS induced a fibrous luminal re sponse with substantial foreign body-type inflammatory reaction around the PET fibers. Although neointima associated with the PET-WS appeare d thicker than that associated with either the ePTFE-WS or the bare WS , none of the patent implants developed greater than 50% angiographic narrowing CONCLUSION: The PET-WS induced chronic inflammation, a respo nse not seen with either the WS or ePTFE-WS, This may explain the occu rrence of pain and/or fever in human studies of arterial PET endolumin al stent-grafts, Patency for all three implants was excellent in this model.