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Research Papers

Sensitivity of CFD Based Hemodynamic Results in Rabbit Aneurysm Models to Idealizations in Surrounding Vasculature

[+] Author and Article Information
Zijing Zeng

Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 3700 O’Hara Street, Pittsburgh, PA 15261ziz3@pitt.edu

David F. Kallmes

Department of Radiology, Mayo Clinic College of Medicine, 200 First Street Southwest, Rochester, MN 55905kallmes.david@mayo.edu

Michael J. Durka

Department of Mechanical Engineering and Materials Science, University of Pittsburgh, 3700 O’Hara Street, Pittsburgh, PA 15261

Yonghong Ding, Debra Lewis, Ramanathan Kadirvel

Department of Radiology, Mayo Clinic College of Medicine, 200 First Street Southwest, Rochester, MN 55905

Anne M. Robertson1

Department of Mechanical Engineering and Materials Science and Center for Vascular Remodeling and Regeneration (CVRR), University of Pittsburgh, Pittsburgh, PA 15261rbertson@pitt.edu

1

Corresponding author.

J Biomech Eng 132(9), 091009 (Aug 26, 2010) (10 pages) doi:10.1115/1.4001311 History: Received June 01, 2009; Revised February 16, 2010; Posted February 22, 2010; Published August 26, 2010; Online August 26, 2010

Computational fluid dynamics (CFD) studies provide a valuable tool for evaluating the role of hemodynamics in vascular diseases such as cerebral aneurysms and atherosclerosis. However, such models necessarily only include isolated segments of the vasculature. In this work, we evaluate the influence of geometric approximations in vascular anatomy on hemodynamics in elastase induced saccular aneurysms in rabbits. One representative high aspect ratio (AR—height/neck width) aneurysm and one low AR aneurysm were created at the origin of the right common carotid artery in two New Zealand white rabbits. Three-dimensional (3D) reconstructions of the aneurysm and surrounding arteries were created using 3D rotational angiographic data. Five models with varying extents of neighboring vasculature were created for both the high and low AR cases. A reference model included the aneurysm sac, left common carotid artery (LCCA), aortic arch, and downstream trifurcation/quadrification. Three-dimensional, pulsatile CFD studies were performed and streamlines, wall shear stress (WSS), oscillatory shear index, and cross sectional velocity were compared between the models. The influence of the vascular domain on intra-aneurysmal hemodynamics varied between the low and high AR cases. For the high AR case, even a simple model including only the aneurysm, a small section of neighboring vasculature, and simple extensions captured the main features of the steamline and WSS distribution predicted by the reference model. However, the WSS distribution in the low AR case was more strongly influenced by the extent of vasculature. In particular, it was necessary to include the downstream quadrification and upstream LCCA to obtain good predictions of WSS. The findings in this work demonstrate the accuracy of CFD results can be compromised if insufficient neighboring vessels are included in studies of hemodynamics in elastase induced rabbit aneurysms. Consideration of aspect ratio, hemodynamic parameters of interest, and acceptable magnitude of error when selecting the vascular domain will increase reliability of the results while decreasing computational time.

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Copyright © 2010 by American Society of Mechanical Engineers
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Figures

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Figure 1

Two-dimensional, anteroposterior subclavian artery angiogram with arrows indicating the surrounding vasculature: LCCA, PPA, DPA, AO, and aneurysm

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Figure 2

Raw Doppler velocimetry waveform (upper right) and corresponding idealized waveform used in computational studies (case 976)

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Figure 3

3D reconstruction of vascular domain used for high AR model E; inlet/outlet cross sections for model E and various submodels are labeled as Γα

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Figure 4

Schematic view of intersecting plane used for error analysis, the cross section plane (left), and the resulting intersecting curve (right)

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Figure 5

Streamlines for all models: (a) high AR case and (b) low AR case; color of the streamlines indicates the velocity magnitude (mm/s)

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Figure 6

WSS contours for all models: (a) high AR case and (b) low AR case; unit in pascal

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Figure 7

WSS along intersecting curve for high AR case: (a) entire aneurysm region (sac and neck, models B–E) and (b) aneurysm sac only (models A–E)

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Figure 8

WSS along intersecting curve for low AR case: (a) entire aneurysm region (sac and neck, models B–E) and (b) aneurysm sac only (models A–E)

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Figure 9

Contours of OSI: (a) high AR case and (b) low AR case

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Figure 10

Contours of magnitude of velocity (mm/s) at systole in cross sectional slices of the PPA: (a) high AR case and (b) low AR case; a and b in column one indicate the orientation of cross sections in the schematics at the right

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