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Increasing Flow Diversion for Cerebral Aneurysm Treatment Using a Single Flow Diverter

Xiang, Jianping PhD*,‡,§; Ma, Ding PhD*,§; Snyder, Kenneth V. MD, PhD*,‡,¶; Levy, Elad I. MD*,‡,¶; Siddiqui, Adnan H. MD, PhD*,‡,¶; Meng, Hui PhD*,‡,§,‖

Neurosurgery:
doi: 10.1227/NEU.0000000000000409
Research-Laboratory
Abstract

BACKGROUND: 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 whether the hemodynamic outcome would differ by increasing FD local compaction across the aneurysm orifice.

METHODS: We investigated deployment of a single FD using 2 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 posttreatment 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, isovelocity, and wall shear stress distributions demonstrated enhanced aneurysmal flow reduction with C2. The average intra-aneurysmal flow velocity was 29% of pretreatment with C2 compared with 67% with C1. Aneurysmal flow turnover time was 237% and 134% of pretreatment for C2 and C1, respectively. Vortex core lines and oscillatory shear index distributions indicated that C2 decreased the aneurysmal flow complexity more than C1. Ultrahigh 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, ultrahigh blood shear stress was observed through FD pores, which could potentially activate platelets as an additional aneurysmal thrombosis mechanism.

ABBREVIATIONS: CFD, computational fluid dynamics

FD, flow diverter

HiFiVS, high-fidelity virtual stenting

OSI, oscillatory shear index

PED, Pipeline Embolization Device

WSS, wall shear stress

Author Information

*Toshiba Stroke and Vascular Research Center,

Departments of Neurosurgery,

§Mechanical and Aerospace Engineering,

Biomedical Engineering, and

Radiology, University at Buffalo, State University of New York, Buffalo, New York

Correspondence: Hui Meng, PhD, Toshiba Stroke and Vascular Research Center, Clinical and Translational Research Center, University at Buffalo, 875 Ellicott Street, Buffalo, NY 14203. E-mail: huimeng@buffalo.edu

Received December 10, 2013

Accepted April 09, 2014

Copyright © by the Congress of Neurological Surgeons