R3 - The Impact of Vascular Flexibility on Mechanical Thrombectomy Outcomes: A Combined In Silico and In Vitro Study

Introduction: : Acute ischemic stroke (AIS), a leading cause of mortality among cardiovascular diseases worldwide. The AIS is caused by an occluded blood clot in the cerebral circulation and an insufficient blood supply to the brain. Mechanical Thrombectomy (MT) has shown promising results by enabling direct clot removal from occluded cerebral arteries using stent retrievers or aspiration catheters. Nevertheless, MT success depends critically on the clot mechanical properties, stent retriever (SR) design, catheter mechanics, and vascular biomechanics. The interaction between clot, medical device/SR, and arterial wall is very complex. Understanding these factors is essential for optimizing device performance and clinical outcomes. Limited knowledge of mechanical interactions during MT and its influence on treatment outcomes is available. In silico trials—computational simulations of medical procedures—provide a powerful platform to systematically investigate these interactions while precisely controlling device geometries, material properties, and procedural parameters.

Materials and

Methods: : Past studies have performed in silico trials of MT, but they have assumed a rigid vessel wall (Luraghi et al., 2021b, 2021a). This study presents an in-silico and in vitro framework to analyze the impact of flexible catheter and vessel wall properties on MT performance. A high-fidelity finite element model (FEM) of a thrombectomy procedure is developed and validated using in vitro model, incorporating realistic cerebral vasculature model, human-analog clot properties derived from experimental stress-strain tests, and flexible catheter/arterial wall behavior. The computational model captures the dynamic interaction between the catheter, clot, and vessel wall to evaluate critical performance metrics such as clot retrieval success, vessel deformation, and optimized catheter tracking in acutely curved vessels. A parametric study is conducted to assess how variations in catheter flexibility and vessel wall stiffness affect the overall efficacy of MT. Past in silico studies used tracking of the catheter via a predefined path along the vessel, but this work used a realistic pushing method that mimics an in vivo scenario.

Results, Conclusions, and Discussions:: Catheter flexibility influences navigation efficiency and clot engagement, while vessel wall properties determine the extent of vessel deformation and possible damage during retrieval. In silico results indicate that optimum catheter flexibility enhances clot retrieval efficiency while minimizing excessive forces on the vessel wall. Similarly, vessel wall flexibility helps the catheter for efficient tracking. The use of rigid vessel walls leads to catheter kinking and unrealistic behavior.
The findings from this study provide valuable insights into the mechanical aspects of MT, contributing to the development of improved catheter designs and patient-specific treatment strategies. Using in silico trials, clinicians and medical device manufacturers can improve MT techniques and optimize catheter properties to enhance safety and efficacy. Future research will focus on integrating patient-specific blood flow dynamics and MT device variability to further improve the predictive capabilities of computational models. This study proposes the potential of in silico trials as a cost-effective and ethical alternative to extensive in vivo and in vitro testing. The proposed framework paves the way for precision medicine in neurointervention, where device selection and procedural strategies can be tailored based on individualized vessel and clot characteristics.

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