Endovascular thrombectomy (EVT) devices are evolving rapidly to improve safety and efficacy of EVT-mediated recanalization of large vessel occlusion strokes, and to access medium and distal vessel occlusions.  

We utilized three FDA-approved stent-retrievers (4mm diameter; variable lengths) and deployed them in an in-vitro ischemic stroke bench model (Sim Agility, Mentice Inc., Sweden). The stent-retrievers were deployed in the M1 segment of the middle cerebral artery of the model using a system comprised of an 0.014inch guide wire and 0.021inch microcatheter. After unsheathing in the M1 segment, in the absence of a blood clot, the microcatheter was withdrawn back into the petrous internal carotid artery, and the whole system was withdrawn at a rate of 5mm/second. Maximum deflection of the terminal internal carotid was measured in 3 axes using a specialized camera set-up.

A total of 3 passes were performed for each stent-retriever (stent-A, stent-B, and stent-C). Maximum deflection of the terminal internal carotid artery (from resting position to largest displacement during stent-retrieval withdrawal) was measured in 3 planes (Table)-

Maximum Euclidean Deflection (MED) ranged from 6.1 to 9.1mm. Deflection varied based on 3 stent-retriever designs and the plane of measurement. Figure demonstrates deflections as seen in Stent-A.

Withdrawing an unsheathed stent-retriever from the middle cerebral artery leads to significant deflection of the internal carotid artery terminus in an in-vitro stroke model. The degree of deflection varies based on stent-retriever design. Further studies are required to examine predictors and impact of the deflection.