Stents Wrapped in Autologous Vein: An Experimental Study

Abstract

Objectives. A new type of coated stent, consisting of a conventional stent covered by an autologous vein graft, was developed at our institution.Background. Coated stents are under investigation to address stenting limitations. However, experimental implantation of coated stents covered by autologous tissue has not been reported.Methods. An autologous vein graft was removed and carefully prepared. Subsequently, a Palmaz stent was covered by the vein graft both internally and externally. Twenty-seven stents were implanted in the normal iliac arteries of 27 pigs weighing 18 to 33 kg. In 15 of the pigs, 15 noncoated Palmaz stents were implanted in the contralateral artery; these animals served as the control group. The animals were followed up angiographically for a period ranging from 7 days to 6 months. At the time of death, the stented segments were removed, and histomorphometric analysis was performed.Results. Autologous vein graft-coated stent preparation and implantation was feasible and uncomplicated. In both stents, angiographic follow-up revealed the absence of thrombosis, except for two cases of subacute thrombosis in the control group. The thickness of the intimal layer was greater in the coated stents and seems to be due to the existence of the internal vein layer ([mean ± SD] 0.57 ± 0.12 vs. 0.27 ± 0.13 mm, p = 0.001). The arterial media of the coated stent segments was thinner than that in the control group (0.14 ± 0.03 vs. 0.18 ± 0.01 mm, p = 0.02).Conclusions. The autologous vein graft-coated stent seems to be nonthrombogenic, and only minimal hyperplasia was observed in the pigs. Further studies are needed to explore the efficacy of this technique in humans.