Evaluation of a newly designed flow diverter for the treatment of intracranial aneurysms in an elastase-induced aneurysm model, in New Zealand white rabbits

In this study, we analyzed angiographic and histologic aneurysm occlusion of a newly designed flow-diverting device. Visibility and flexibility, as well as occlusions of side branches and neointimal proliferation were also evaluated. Aneurysms were induced in 18 New Zealand white rabbits and treated with a braided, "closed-loop-designed" device of nitinol. Additional devices were implanted in the abdominal aorta to cover the origin of branch arteries. Angiographic follow-ups were performed immediately after placement of the device, after 3 months (n = 9) and 6 months (n = 9). The status of aneurysm occlusion (using a five-point scale) and the patency of branch arteries were assessed. Aneurysm occlusion rates were noted as grade 0 in 2 (11 %), grade I in 1 (6 %), grade II in 1 (6 %), grade III in 9 (50 %), and grade IV in 5 (28 %) of 18 aneurysms, respectively, indicating a complete or near-complete occlusion of 78 % under double antiplatelet therapy. Aneurysm occlusion was significantly higher at 6 months follow-up (P = 0.025). Radiopaque markers provided excellent visibility. Limited device flexibility led to incomplete aneurysm neck coverage and grade 0 occlusion rates in two cases. Distal device occlusions were found in three cases, most likely due to an extremely undersized vessel diameter in the subclavian artery. No case of branch artery occlusion was seen. Intimal proliferation and diameter stenosis were moderate. The tested flow diverter achieved near-complete and complete aneurysm occlusion under double antiplatelet therapy of elastase-induced aneurysms in 78 %, while preserving branch arteries.