Can aspect ratio be used to categorize intra-aneurysmal hemodynamics?-A study of elastase induced aneurysms in rabbit

Zijing Zeng, Michael J. Durka, David F. Kallmes, Yonghong Ding, Anne M. Robertson

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

Clinical studies suggest that aneurysm aspect ratio (AR) is an important indicator of rupture likelihood. The importance of AR is hypothesized to arise from its influence on intra-aneurysmal hemodynamics. It has been conjectured that slower flow in high AR sacs leads to a cascade of biological activities that weaken the aneurysm wall (Ujiie et al.,1999). However, the connection between AR, hemodynamics and wall weakening has never been proven. Animal models of saccular aneurysms provide a venue for evaluating this conjecture. The focus of this work was to evaluate whether a commonly used elastase induced aneurysm model in rabbits is suitable for a study of this kind from a hemodynamic perspective. In particular, to assess whether hemodynamic factors in low and high AR sacs are statistically different. To achieve this objective, saccular aneurysms were created in 51 rabbits and pulsatile computational fluid dynamics (CFD) studies were performed using rabbit specific inflows. Distinct hemodynamics were found in the low AR (AR<1.8, n=25), and high AR (AR>2.2, n=18) models. A single, stable recirculation zone was present in all low AR aneurysms, whereas a second, transient recirculation zone was also found in the superior aspect of the aneurysm dome for all high AR cases. Aneurysms with AR between 1.8 and 2.2 displayed transitional flow patterns. Differences in values and distributions of hemodynamic parameters were found between low and high AR cases including time averaged wall shear stress, oscillatory shear index, relative residence time and non-dimensional inflow rate. This work lays the foundation for future studies of the dependence of growth and remodeling on AR in the rabbit model and provides a motivation for further studies of the coupling between AR and hemodynamics in human aneurysms.

Original languageEnglish (US)
Pages (from-to)2809-2816
Number of pages8
JournalJournal of Biomechanics
Volume44
Issue number16
DOIs
StatePublished - Nov 10 2011

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Keywords

  • Aneurysm
  • Aspect ratio
  • CFD
  • Hemodynamics
  • Wall shear stress

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation

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