0

Full Content is available to subscribers

Subscribe/Learn More  >

Flow Simulations to Establish the Relationship Between the Inflow Zone in the Neck of a Cerebral Aneurysm and the Positions of Struts

[+] Author Affiliations
Kazuhiro Watanabe, Hitomi Anzai, Makoto Ohta

Tohoku University, Sendai, Japan

Paper No. IMECE2016-67804, pp. V003T04A015; 9 pages
doi:10.1115/IMECE2016-67804
From:
  • ASME 2016 International Mechanical Engineering Congress and Exposition
  • Volume 3: Biomedical and Biotechnology Engineering
  • Phoenix, Arizona, USA, November 11–17, 2016
  • Conference Sponsors: ASME
  • ISBN: 978-0-7918-5053-4
  • Copyright © 2016 by ASME

abstract

Flow-diverter (FD) stent implantation is an attractive treatment for cerebral aneurysms because of its low level of invasiveness. FD stent has a fine mesh structure, and the aim of FD implantation is to reduce the blood flow in an aneurysm by covering the aneurysm orifice. However, the fine mesh of the implant poses the risk of parent artery occlusion.

One approach for avoiding this risk is to use a stent with a higher porosity. Previous studies have shown that placing a strut to disturb the inflow entering an aneurysm can promote a higher reduction in aneurysm flow. However, Hirabayashi et al. reported that a high-porosity stent can be sensitive to misdeployment in flow reduction. We hypothesized that a positioning error in flow reduction was sensitive to the relative position of the strut to the inflow configuration. In this study, we performed flow simulation to investigate the relationship between the inflow zone of the aneurysm neck and the positions of struts.

Lattice Boltzmann (LB) flow simulation was performed to allow a comprehensive study of strut positions. Two rectangular solids were used as the strut model. Steady flow simulation was applied to models based on ideal and realistic three-dimensional (3D) aneurysm geometry, changing two strut positions along the neck plane. For both models, velocity boundaries were imposed on the inlet and a constant pressure boundary was imposed on the outlet.

Average flow velocity in an aneurysm was calculated to evaluate the dependency of the flow reduction effect on the deployment position. We analyzed aneurysm flow using the following three strategies to observe the relationship between flow configuration, strut configuration, and flow reduction.

Analysis A: Flow reduction rate (Rf) with one strut. A strut was moved from the proximal to the distal neck (perpendicular deployment) or from outside to inside (parallel deployment).

Analysis B: Rf with two struts. One strut (strut A) was fixed in a specific position on the neck plane. The other (strut B) was moved along the neck plane in parallel to strut A.

Analysis C: Rf with two struts. Strut B was located on the distal or inner side of strut A. The distance between the two struts was changed, and the two struts were moved along the neck plane while maintaining that distance.

From the results of Analyses A and B, we confirmed a critical area in the inflow zone that maintained a high flow reduction regardless of the position of the second strut.

The results of Analysis C confirmed that there were several distances between the struts at which flow reduction was almost constant. This constant reduction was maintained when one of the struts was located in the critical area, whereas the reduction was disturbed if both struts were located outside the area.

These results suggest that the influence of positioning errors can be reduced by constantly placing at least one strut in a critical area, resulting in a high flow reduction. This may lead to optimal stent porosity for flow reduction and robustness of deployment.

Copyright © 2016 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In