Introduction/Purpose Stent retriever thrombectomy has become a well-established approach for treating acute ischemic stroke. Current stent retrievers are able to retrieve a wide spectrum of clot types, with rapid recanalization time. As stent retriever technology continues to advance, there is an ongoing need to evaluate potential vascular injury due to stent retriever retraction. Preclinical assessment of vascular injury is typically performed in animal models, but recent work has established that endothelialized silicone models can be used for early stage assessment of injury due to catheter simulated use. The purpose of the current work was to create custom endothelialized silicone models to evaluate endothelial injury due to retraction of different sizes and types of commercially available stent retrievers.

Materials and Methods Two separate studies were performed for this work, each employing a different neurovascular geometry, and each evaluating a different subset of stent retriever devices. Both studies included silicone fabrication in custom geometries, followed by silicone sterilization, fibronectin coating, placement in custom bioreactors, deposition with human umbilical vein endothelial cells, and cultivation under flow. After 3–4 days of vessel cultivation, stent retrievers were deployed in, and retracted through, the vessels by a practicing neurointerventionalist. Vessels were then immediately harvested, fixed, stained with H&E, and imaged. Injury to the endothelial cell monolayer was quantified using ImageJ, with key regions of interest identified and characterized. The first study, which included n=21 vessels, evaluated three sizes of stent retrievers from two different companies, with 1-pass and 2-pass treatments. The second study, which included n=18 vessels, evaluated one size of stent retriever from two different companies, with 1-pass and 2-pass treatments as well as wire/microcatheter-only comparisons.

Results Results from the first study illustrated injury ranging from <3% surface area (SA) injured in control vessels, to 37–61% SA injured following 1-pass treatments, to 52–70% SA injured following 2-pass treatments. Injury was lower with the smallest device, and 2-pass treatments tended to cause more injury than 1-pass. In the second study, results illustrated injury ranging from <4% SA injured in control vessels, to 16–18% injured in wire/microcatheter-only treatments, to 50–52% injured in the 1-pass treatment groups, and 58–66% SA injured in the 2-pass treatment groups. In both studies, regional analysis indicated that the most narrow distal regions tended to exhibit higher injury.

Conclusion This work illustrates the use of endothelialized silicone models in clinically-relevant geometries for the assessment of vascular injury due to stent retriever retraction. The specific geometries employed and the regional analysis performed in this work provided data about the extent and location of injury based on device and vessel size. Overall, results revealed expected trends, with increased injury seen in the most distal narrow regions, and also with 2-pass vs. 1-pass treatments. The results documented here provide insight into the present devices, while also supporting the use of these models for cost-effective and scalable early stage assessment of vascular injury due to stent retriever retraction.

Disclosures I. Starr: None. H. Oen: None. A. McCulloch: None. S. Frenklakh: 5; C; Employee of Stryker Neurovascular. R. Grandfield: 5; C; Employee of Stryker Neurovascular. H. Choe: 2; C; Consultant for Stryker Neurovascular. K. Cardinal: 1; C; Stryker Neurovascular.