AUTOLOGOUS VEIN LINED AND VEIN COVERED STENTS IN SWINE ARTERIES - AN EXPERIMENTAL-STUDY TO ASSESS AND COMPARE PATENCY AND INTIMAL HYPERPLASTIC RESPONSE

Background. Despite the success of arterial angioplasty as well as art erial stent placement, restenosis remains a significant problem in pro longing blood vessel patency. This animal model was used to test the t heory that a stent lined (VLS) or covered (VCS) with autologous vein. would be more biologically compatible with the arterial intima. If suc cessful, this technique would prevent angioplasty failure due to intim al hyperplasia (IH) by supplying a healthy endothelial surface and hel p to eliminate elastic recoil mechanism (ERM) by the use of a stent re ndered less thrombogenic in both stenosed and restenosed arteries. The re might in addition, be other applications for these modified stents. Methods. Nine 50 kg-young pigs had Gianturco-Roubin VIS and VCS mount ed on a balloon angioplasty catheter implanted via a transverse arteri otomy. VLS were implanted in 3 left iliac and 6 left carotid arteries and VCS were placed in the matching contralateral arteries. The change from iliac to carotid arteries was due to the initial perception that the iliac artery was the right size for this device. It proved to be too large and the carotid artery, which was initially felt to be too s mall proved to be the right size. Operative angiography was performed to ensure proper placement. Duplex imaging of the carotid artery place ments were performed at 10-14 days. All animals were sacrificed at 30- 33 days and specimens examined grossly and microscopically. Three 16.5 % of the devices were found to be patent, two Vis and one VCS. The rem aining 14 (78%) were occluded by distortion or thrombus or both. Resul ts. Five devices migrated distally, 2 of which remained patent albeit of smaller diameter. One device migrated to the brain, was not recover ed and was presumed occluded, All arteries and veins, with two excepti ons, demonstrated varying degrees of IH. We believe failure was due to the inability of the stents to resist ERM in these healthy pig arteri es. The IH observed, we believe, is due to the forced dilatation requi red to seat the devices. Conclusions. Based on the observations of the patent devices we suggest that arteries can be relined and supported with modifications of this technique, using a more ERM resistant stent that may be placed without forceful dilatation. This will require fur ther study.