Ahead of Print: Increasing Flow Diversion Using a Single Flow Diverter

Screen Shot 2014-07-16 at 11.20.00 AMBackground: A neurovascular flow diverter (FD), aiming at inducing embolic occlusion of cerebral aneurysms through hemodynamic changes, can produce variable mesh densities owing to its flexible mesh structure.

Objective: To explore if the hemodynamic outcome would differ by increasing FD local compaction across the aneurysm orifice.

Methods: We investigated deployment of a single FD using two clinical strategies: no compaction (the standard method) and maximum compaction across the aneurysm orifice (an emerging strategy). Using an advanced modeling technique, we simulated these strategies applied to a patient-specific wide-necked aneurysm model, resulting in a relatively uniform mesh with no compaction (C1) and maximum compaction (C2) at the aneurysm orifice. Pre- and post-treatment aneurysmal hemodynamics were analyzed using pulsatile computational fluid dynamics. Flow-stasis parameters and blood shear stress were calculated to assess the potential for aneurysm embolic occlusion.

Results: Flow streamlines, iso-velocity, and wall shear stress distributions demonstrated enhanced aneurysmal flow reduction with C2. The average intra-aneurysmal flow velocity was 29% of pre-treatment with C2, compared to 67% with C1. Aneurysmal flow turnover time was 237% and 134% of pre-treatment for C2 and C1, respectively. Vortex core lines and oscillatory shear index distributions indicated that C2 decreased the aneurysmal flow complexity more than C1. Ultra-high blood shear stress was observed near FD struts in inflow region for both C1 and C2.

Conclusion: The emerging strategy of maximum FD compaction can double aneurysmal flow reduction, thereby accelerating aneurysm occlusion. Moreover, ultra-high blood shear stress was observed through FD pores, which could potentially activate platelets as an additional aneurysmal thrombosis mechanism.

From: Increasing Flow Diversion for Cerebral Aneurysm Treatment Using a Single Flow Diverter by Xiang et al.

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