Self-Expanding and Balloon-Expandable Stents in The Treatment of Carotid Aneurysms: An Experimental Study

PURPOSE: To assess the efficacy of metal stents for the treatment of different forms and sizes of carotid aneurysms. METHODS: A total of 14 experimentally constructed aneurysms in dogs were treated with transfemorally placed balloon-expandable tantalum and self-expanding nitinol stents. RESULTS: In 10 cases, stenting produced either immediate complete occlusion of the aneurysm (n = 7) or complete delayed thrombosis after 7 to 10 days (n = 3). In two cases treated with balloon-expandable tantalum endoprostheses, repeated angiography showed a persistent aneurys-mal neck with a diameter of 1 mm. No incompletely occluded aneurysms were visible after implantation of nitinol stents. Nine-month angiographic follow-up revealed maximal stenosis of the stented vessel segment of up to 40 % after placement of tantalum endoprostheses. However, no more than 15 % stenosis followed the deployment of nitinol stents. Histologic examination confirmed these findings. Significantly greater intimal fibrocellular tissue growth surrounded tantalum filaments than nitinol filaments, which were covered with a smooth, thin neointimal layer. In two carotid arteries a subtotal and total occlusion of the parent vessel occurred after the insertion of a tantalum and nitinol stent, respectively. No recanalization of completely occluded aneurysms or delayed migration of a stent was observed. CONCLUSIONS: Porous, tubular self