Safety and performance of the Penumbra Liberty stent system in a rabbit aneurysm model

Background Endovascular treatment of wide necked and large/giant intracranial aneurysms is challenging. The goal of this study was to evaluate the Liberty stent system in the rabbit elastase aneurysm model for 30, 90, and 180 days. Methods The Altes elastase model was used to create aneurysms in the right common carotid artery in New Zealand White rabbits. Safety was assessed by angiographic and histopathological data from treated wide necked aneurysms, treated subclavian arteries, and related vasculature immediately post-treatment and at scheduled end points. Results In this study, stenting of wide necked aneurysms demonstrated excellent results in all 35 animals. The Liberty could be tracked to the final position across an aneurysm neck precisely, without changing microcatheter position. After device deployment, no significant changes in vessel contour and no stent migration were observed. Coil mass was well supported in all aneurysms and high packing densities were achieved. In addition, follow-up angiograms showed stable coil masses and persistent occlusion in all animals, without any recanalization of the neck or aneurysmal sac. Furthermore, there was no evidence of coil compaction or protrusion of coil loop through the stent struts. None of the immediate post-coiling angiograms revealed evidence of vasospasm, dissection, or in-stent thrombosis. Discussion This animal study demonstrated promising results with the novel Liberty stent system. The Liberty showed consistent precise positioning and accurate deployment. The stent revealed good compatibility with embolic coiling procedures, while morbidity and mortality were negligible. In addition, persistent occlusion of aneurysms without recanalization or in-stent stenosis was observed at the 180 day follow-up.