Background: There are a growing number of computational models of thrombosis in cerebral aneurysms that have been designed with consideration towards clinical use. Many of these computational models rely on assumptions to simplify what would otherwise be computationally expensive and slow simulations. A common assumption for these models is that because the average flow-rate is the same, steady flow is an acceptable simplification of pulsatile flow. There is, however, limited evidence suggesting whether steady flow is an acceptable approximation when considering clot formation within a flowing environment.

Aims: Determine whether the use of pulsatile flow in a computational thrombosis model results in a significantly different outcomes than steady flow.

Methods: A pulsatile-flow thrombosis-model has been created in ANSYS® Fluent (ANSYS, Lebanon, NH) using a transient-solution implicit pressure-based solver, wherein an idealized aneurysm geometry is applied, with patient-data-derived pulsatile volumetric flow function supplied at the inlet. A scalar function, derived from Wagenvoord et al., is supplied at the aneurysm wall, and simulates the release of thrombin. The output of an otherwise identical steady-state model is validated with the output of a steady-flow, Particle-Image-Velocimetry (PIV) experiment utilizing an identical geometry, wherein thrombin is injected at the aneurysm, and tracked via a proflavine dye. The validated steady-state numerical model is then altered to include pulsatility, and is then used to determine whether clotting outcomes of a model by Ngoepe and Ventikos, amongst others, differs with pulsatile flow.

Results: This comparison reveals that activated thrombin accumulates more quickly and dissipates more slowly when utilizing pulsatile flow over steady flow. Pulsatile flow creates unsteady flow patterns within the aneurysm, which create an environment where less thrombin is carried out of the aneurysmal sac and into the regular bloodstream.

Conclusions: The results suggest that pulsatile-flow can significantly increase the duration of clotting, which may have a significant effect on clotting outcomes.

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ISTH Congress Abstracts - https://abstracts.isth.org/abstract/effect-of-pulsatility-on-thrombosis-modelling-in-cerebral-aneurysms/