Abstract 9607: Development of Microporous Covered Stents for Treating Cerebral Aneurysms with Maintenance of Branching Flow

Abstract

Objective: Treatment of large (diameter: 12~25 mm) or giant (diameter: over 25 mm) cerebral aneurysms with broad neck in the cranio-cervical area is extremely difficult or carries high risks, even with clinical available surgical method or endovascular one using coils with the assistance of bare stents. In this study, we developed a novel balloon-expandable, microporous covered stent for treating such intractable cerebral aneurysms with high safety and reliability. Methods and Results: The covered stents were prepared using the specially designed balloon-expandable stents with open cell structure (CoCr, Japan Stent Technology; 3 mm x 20 mm). The stents had thin polyurethane cover membrane (thickness: 20 μ m), in which strut was completely impregnated, with a larger amount of micropores (diameter: 100~300 μ m, opening ratio: 10~30%). The experimental aneurysms (10~15 mm) were created at rabbit brachiocephalic arteries (3 mm) by distal ligation and intraluminal elastase incubation at right common carotid arteries. Upon placing the covered stents at the neck of the aneurysms all aneurysms were occluded immediately (n=15), whereas remaining of the aneurysms was occurred by bare stents even after 6 months (n=5). All the parent arteries were patent after implantation up to 12 months. At 3 months of implantation inner space of the aneurysms was filled completely with granulomatous tissue and luminal surface was covered with extremely thin neointima (n=5, thickness; 68 ± 22 μ m). The branching flow through the cover membrane was maintained in all cases. Conclusion: The newly developed covered stents performed well in terms of creating less intimal hyperplasia with maximum embolization effect without disturbing branching flow.