0
Research Papers

Impact of Stents and Flow Diverters on Hemodynamics in Idealized Aneurysm Models

[+] Author and Article Information
Santhosh Seshadhri

 Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg “Otto von Guericke”, Universitätsplatz 2, D-39106 Magdeburg, Germanysanthosh.seshadhri@st.ovgu.de

Gábor Janiga

 Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg “Otto von Guericke”, Universitätsplatz 2, D-39106 Magdeburg, Germanyjaniga@ovgu.de

Oliver Beuing

 Institute for Neuro-Radiology, Medical Department, University of Magdeburg “Otto von Guericke”, Leipziger Strasse 44, D-39120 Magdeburg, Germanyoliver.beuing@med.ovgu.de

Martin Skalej

 Institute for Neuro-Radiology, Medical Department, University of Magdeburg “Otto von Guericke”, Leipziger Strasse 44, D-39120 Magdeburg, GermanyMartin.Skalej@med.ovgu.de

Dominique Thévenin1

 Laboratory of Fluid Dynamics and Technical Flows, University of Magdeburg “Otto von Guericke”, Universitätsplatz 2, D-39106 Magdeburg, Germanythevenin@ovgu.de

1

Corresponding author.

J Biomech Eng 133(7), 071005 (Jul 18, 2011) (9 pages) doi:10.1115/1.4004410 History: Received January 31, 2011; Accepted May 12, 2011; Revised May 12, 2011; Published July 18, 2011; Online July 18, 2011

Cerebral aneurysms constitute a major medical challenge as treatment options are limited and often associated with high risks. Statistically, up to 3% of patients with a brain aneurysm may suffer from bleeding for each year of life. Eight percent of all strokes are caused by ruptured aneurysms. In order to prevent this rupture, endovascular stenting using so called flow diverters is increasingly being regarded as an alternative to the established coil occlusion method in minimally invasive treatment. Covering the neck of an aneurysm with a flow diverter has the potential to alter the hemodynamics in such a way as to induce thrombosis within the aneurysm sac, stopping its further growth, preventing its rupture and possibly leading to complete resorption. In the present study the influence of different flow diverters is quantified considering idealized patient configurations, with a spherical sidewall aneurysm placed on either a straight or a curved parent vessel. All important hemodynamic parameters (exchange flow rate, velocity, and wall shear stress) are determined in a quantitative and accurate manner using computational fluid dynamics when varying the key geometrical properties of the aneurysm. All simulations are carried out using an incompressible, Newtonian fluid with steady conditions. As a whole, 72 different cases have been considered in this systematic study. In this manner, it becomes possible to compare the efficiency of different stents and flow diverters as a function of wire density and thickness. The results show that the intra-aneurysmal flow velocity, wall shear stress, mean velocity, and vortex topology can be considerably modified thanks to insertion of a suitable implant. Intra-aneurysmal residence time is found to increase rapidly with decreasing stent porosity. Of the three different implants considered in this study, the one with the highest wire density shows the highest increase of intra-aneurysmal residence time for both the straight and the curved parent vessels. The best hemodynamic modifications are always obtained for a small aneurysm diameter.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Characteristic dimensions employed to describe a saccular aneurysm, as introduced in Ref. [10]

Grahic Jump Location
Figure 2

Geometrical configurations considered in this study, from left to right and top to bottom. (a) Sidewall aneurysm model with straight parent vessel: top, lateral view; bottom, cross-section. (b) Sidewall aneurysm model with curved parent vessel (inner bend angle of 60°). (c) Geometry of Neuroform3® stents: top, high porosity (NHP); bottom, low porosity (NLP). (d) Geometry of the Silk4,0® flow diverter.

Grahic Jump Location
Figure 3

Streamlines emitted from inlet and neck, colored with the local velocity magnitude (left) and velocity vectors along the neck region (right), both for Case SP-8-1.4-WOS. In all such figures, the black arrow indicates the flow direction in the parent vessel.

Grahic Jump Location
Figure 7

Peak wall shear stress within the aneurysm sac for all cases (a) straight parent vessel and (b) bent parent vessel

Grahic Jump Location
Figure 8

Relative increase (in %) of blood residence time T within the aneurysm sac for a SILK flow diverter compared to the case without stenting (WOS) for (a) straight parent vessel and (b) bent parent vessel

Grahic Jump Location
Figure 4

Streamlines emitted from inlet and neck, colored with the local velocity magnitude, showing the influence of a decreasing dome-to-neck-ratio for a constant sac diameter of 12 mm: (a) 1.8 (Case SP-12-1.8-WOS), (b) 1.6 (Case SP-12-1.6-WOS), and (c) 1.4 (Case SP-12-1.4-WOS)

Grahic Jump Location
Figure 5

Streamlines emitted from inlet and neck, colored with the local velocity magnitude, plotted for the same vascular geometry and for the three different stent and flow diverter models considered in this study: (a) Without stent (Case BP-8-1.4-WOS) (b) SILK (Case BP-8-1.4-SILK), (c) NLP (Case BP-8-1.4-NLP), and (d) NHP (Case BP-8-1.4-NHP)

Grahic Jump Location
Figure 6

Average velocity magnitude (cm/s) within the aneurysm sac for all cases with a constant dome-to-neck ratio of 1.4 for (a) straight parent vessel and (b) bent parent vessel

Tables

Errata

Discussions

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 Journal Articles
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