Document Detail


Turbulence significantly increases pressure and fluid shear stress in an aortic aneurysm model under resting and exercise flow conditions.
MedLine Citation:
PMID:  17349339     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The numerical models of abdominal aortic aneurysm (AAA) in use do not take into account the non-Newtonian behavior of blood and the development of local turbulence. This study examines the influence of pulsatile, turbulent, non-Newtonian flow on fluid shear stresses and pressure changes under rest and exercise conditions. We numerically analyzed pulsatile turbulent flow, using simulated physiological rest and exercise waveforms, in axisymmetric-rigid aortic aneurysm models (AAMs). Discretization of governing equations was achieved using a finite element scheme. Maximum turbulence-induced shear stress was found at the distal end of an AAM. In large AAMs (dilated to undilated diameter ratio = 3.33) at peak systolic flow velocity, fluid shear stress during exercise is 70.4% higher than at rest. Our study provides a numerical, noninvasive method for obtaining detailed data on the forces generated by pulsatile turbulent flow in AAAs that are difficult to study in humans and in physical models. Our data suggest that increased flow turbulence results in increased shear stress in aneurysms. While pressure readings are fairly uniform along the length of an aneurysm, the kinetic energy generated by turbulence impacting on the wall of the distal half of the aneurysm increases fluid and wall shear stress at this site. If the increased fluid shear stress results in further dilation and hence further turbulence, wall stress may be a mechanism for aneurysmal growth and eventual rupture.
Authors:
Khalil M Khanafer; Joseph L Bull; Gilbert R Upchurch; Ramon Berguer
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Annals of vascular surgery     Volume:  21     ISSN:  0890-5096     ISO Abbreviation:  Ann Vasc Surg     Publication Date:  2007 Jan 
Date Detail:
Created Date:  2007-03-12     Completed Date:  2007-03-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8703941     Medline TA:  Ann Vasc Surg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  67-74     Citation Subset:  IM    
Affiliation:
Department of Biomedical Engineering, Vascular Mechanics Laboratory, University of Michigan, Ann Arbor, MI, USA. khanafer@umich.edu
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MeSH Terms
Descriptor/Qualifier:
Aortic Aneurysm, Abdominal / physiopathology*
Computer Simulation
Exercise / physiology
Finite Element Analysis
Humans
Pressure
Pulsatile Flow / physiology*
Stress, Mechanical

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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