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  • Flow-diverter Treatment Failures: a Patient-specific Computational Flow Dynamics Study on Refractory Aneurysms

    Final Number:

    Anderson Chun On Tsang MBBS; Abraham Yik Sau Tang; Hiu Ning Chan; Kwok Wing Chow; Gilberto K K Leung MBBS, BSc, FRCS, MS

    Study Design:
    Laboratory Investigation

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2014 Annual Meeting

    Introduction: Flow diverting stents shifted the paradigm in endovascular management of intracranial aneurysms, with aneurysm obliteration rate of over 80% by 6 months. However, some aneurysms persist despite successful stent deployment. The risk factors for flow-diverter failures remain unclear. Computational fluid dynamics has been used to study aneurysm hemodynamics and may predict flow-diverting treatment effect. We performed patient-specific fluid dynamics study to identify hemodynamic changes related to flow-diverter treatment outcome.

    Methods: Patients with unruptured intracranial aneurysms that failed flow-diverting stent treatment after 1 year were identified from the hospital database and matched with those successfully obliterated, according to aneurysm location, configuration and size. 3D realistic computational models of the aneurysms were reconstructed from pre-treatment angiograms, with virtual flow-diverting stent structured according to the specifications of Pipeline Embolization Device (eV3, Irvine, California, USA). Simulation of pulsatile blood flow before and after stent placement was performed, and hemodynamic parameters of treatment success and failure cases were compared.

    Results: Aneurysms that persisted after flow-diverter treatment had 4-6 times higher post-treatment volume flow rate across aneurysm neck (78.2-182mm3/s vs 13.8-39.3mm3/s); less reduction in intra-aneurysm flow after treatment (63.2-68.2% vs 87.8-91.2% ); as well as higher maximum jet velocity in the aneurysm (0.278m/s vs 0.12m/s) compared with those that were obliterated. There was no significant change in pressure within the aneurysm before and after stent placement in all the aneurysms studied.

    Conclusions: Computational fluid dynamics can simulate post-treatment flow changes in intracranial aneurysms treated with flow-diverting stents. Inadequate flow diversion as evidenced by high post-treatment volume flow rate and jet velocity across the aneurysm neck may predict treatment failure.

    Patient Care: Pre-treatment aneurysm computational study is feasible and can estimate the flow diversion effect of flow-diverting stents in an individual patient. This additional information may predict flow-diverter treatment outcome and guide better patient selection.

    Learning Objectives: By the conclusion of this session, participants should be able to: 1) Appreciate the potential and limitation of computational fluid dynamics in assessing the hemodynamic changes in flow-diverter treated intracranial aneurysms, 2) Discuss on predictive factors of flow-diverter treatment outcome, and 3) Propose optimal patient selection and treatment paradigm for intracranial aneurysms


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