E-026 pre-clinical testing of a novel thin film nitinol flow diversion stent in a rabbit elastase aneurysm model

Abstract

Purpose Thin Film Nitinol can be processed to produce a thin microporous sheet for vascular applications. As compared to current flow diverters constructed as braided tubes, the TFN device has a lower percent metal coverage ( 2 ). We present in vivo results from treatment of experimental rabbit aneurysms using a TFN device. Methods The TFN device was comprised of the TFN sheet supported by a self-expanding, laser-cut nitinol neuro-stent. 21 aneurysms in the rabbit elastase aneurysm model were treated with a single device; devices were also placed over 17 lumbar arteries to model peri-aneurysmal branch arteries of the cranial circulation. Angiography was performed at sacrifice to assess aneurysm occlusion and lumbar artery flow. Gross pathology and en face CD31 immunofluorescent staining was performed on a subset of devices to quantify neck endothelialization. Results One animal died from causes not device related, and in one animal the TFN flow diverter did not cover the aneurysm neck region. Markedly reduced intra-aneurysmal flow was observed on angiography immediately after device placement in all aneurysms. At 2-week follow-up 57% of aneurysms had complete or near complete occlusion ( n = 7 ), and at 4-week ( n = 8 ) and 12-week ( n = 4 ) follow-up 75% of aneurysms had complete or near complete occlusion. All 17 lumbar arteries were patent at follow-up. CD31 staining of aneurysms treated with the TFN flow diverter ( n = 6 , avg. implant duration 6.3 weeks, avg. neck area of 6.26 mm 2 ) showed that 75 ± 16% of the aneurysm neck region was endothelialized at the time of sacrifice. Conclusions Results from pre-clinical testing of a TFN flow-diverter are encouraging. Marked reductions in intra-aneurysmal flow were observed acutely in all aneurysms treated and there was a 75% rate of complete or near-complete occlusion at 4 and 12-week follow-up. All lumbar arteries treated with the device were patent acutely and at follow-up. Results from CD31 staining suggest that the TFN mesh serves not only as a physical barrier to reduce intra-aneurysmal flow, but also as a biological scaffold that may facilitate rapid tissue in-growth and aneurysm neck healing. Disclosures D. Kallmes: None. R. Kadirvel: None. Y. Ding: None. D. Dai: None. C. Kealey: 1; C; NeuroSigma, Inc., V. Gupta: 1; C; NeuroSigma, Inc., D. Johnson: 1; C; NeuroSigma.