The Impact of Vessel Tortuosity and Hemodynamic Forces on Mechanical Thrombectomy Outcomes
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Mechanical thrombectomy (MT) is the standard of care for patients with acute ischemic stroke, however, patient-specific anatomical variations can influence the success of this procedure [1]. Long and tortuous vessels complicate navigation of endovascular devices, leading to prolonged procedure duration and reduced likelihood of complete reperfusion [1, 2]. Consequently, this study analyses how the patient-specific anatomical and hemodynamic characteristics relate to procedural success and functional outcomes. Nine MT cases with middle cerebral artery M1/M2 occlusions were selected from the Addenbrooke's Hospital (Cambridge, UK) registry (REC ref: 20/HRA/5531). Patient-specific 3D vascular anatomy models were reconstructed (Figure 1a) from CTA images, and anatomical characteristics were estimated (Figure 1b) using Mimics (v26.0, Materialise NV), calculating tortuosity from the ratio of straight line distance to centreline length. In this cohort, patients with higher intracranial tortuosity (>0.6) exhibited lower Reynolds number (mean Re ≈ 580), consistent with reduced mean flow velocity in tortuous vessels. In contrast, hemodynamic metrics showed stronger associations with outcome. Notably, the case requiring most passes (n=5) had low intracranial tortuosity (tau=0.55) but high Reynolds number (Re=617), whereas the most tortuous case (tau=0.75) achieved complete reperfusion (mTICI=3) in one pass (Figure 1c). Suggesting that while tortuosity poses technical challenges during catheter navigation, higher hemodynamic forces in straighter vessels may hinder the efficacy of clot capture. Furthermore, elevated Reynolds values correlated with poorer functional outcomes (mRS 4-6), while complete reperfusion showed ambiguous dependency on anatomical and hemodynamic parameters. CFD analysis showed elevated oscillatory shear index (OSI) values in highly tortuous segments, indicating flow instability. In summary, anatomic and hemodynamic characterisation provides critical insights into procedural complexities and outcomes. Future work will validate these findings in a bigger patient cohort, including a diverse range of anatomical and hemodynamic parameters.
