Abstract 14359: A Hybrid Finite Element and Smoothed-Particle Hydrodynamics Method Can Simulate Peri-Procedural Complications of Thrombectomy

Abstract

Introduction: Ischemic stroke is a major cause of mortality and morbidity worldwide. Stent retriever thrombectomy (SRT) is a preeminent treatment for large vessel stroke. While effective, SRT only attains first pass success in 30% of cases, and can cause complications, like embolus formation. In silico modeling of SRT facilitates understanding the cause of such complications. Hypothesis: A combination of finite element analysis (FEA) and smoothed-particle hydrodynamics (SPH) can accurately simulate SRT. Methods: We developed a workflow to simulate key SRT steps including stent packaging, delivery, deployment, and clot extraction. The Solitaire X stent was reconstructed from microCT, and FEA with Timoshenko beam elements was used to simulate the superelasticity of the Nitinol wires. Inspired by their structure and components, clots were modeled with a hybrid FEA-SPH method: initially represented in FEA, but as the clot is deformed by the stent, the elements convert to SPH particles, allowing integration of the stent and clot. These methods were used to model SRT of 3 clots with increasing stiffness in a rigid, straight vessel under flow arrest. For validation, the results were compared to in vitro experiments matching the simulations. Results: Our SRT simulations were similar to in vitro tests. In 3 tests, the softest clot was retrieved, but a portion of the tissue was cleaved, creating an embolus, the moderately stiff clot was retrieved successfully, while the stiffest clot was unable to be retrieved. The stress-strain curve of the stent in moderately stiff case showed typical superelastic behavior, and the clot’s curve showed hyperelastic behavior. Conclusions: This study shows the capability of a hybrid FEA-SPH to model SRT and several related clinically-important complications with high accuracy. In the future, this workflow could be used to study mechanisms of peri-procedural complications, or to develop safer, more effective thrombectomy devices.