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Cardiovascular Hemodynamics: Pathophysiologic flows

Clinical investigations confirm that the arterial lesion (atherosclerosis) or dilation (aneurysm) is site-specific.  Fundamental study of pathophysiologic hemodynamics and mass transfer through these specific locations of arteries are of interest to researchers.  In addition, to determine what happens to blood flow once a blockage or aneurysm develops, our research is to identify whether or not an alteration in flow conditions, i.e., pulsatility or fluid parameters, which may be achieved by pharmaceutical and chemical (blood thinning medication), or mechanical means (mechanical devices such as micropumps and catheters), can help to reduce the risk of arterial diseases, e.g., heart attack and strokes.

        Past studies have shown that for diseased vessels, having complex arterial geometries, including various degrees of atherosclerosis and aneurysm, the effect of the non-Newtonian viscosity of blood on hemodynamic parameters can be much more complicated than for the vessels without disease.  The complexity of the flow increases as the flow is pulsatile in nature.  An arterial vessel of complex geometry experiences a vastly different viscosity and shear rate, leading to a shift and increases in the magnitude of oscillating shear stress along the arterial wall.  In addition, the effect of wall compliance due to the elasticity of the wall and also compliance mismatch create additional intricacy. The wall compliance effect is implemented using Fluid Structure Interaction (FSI) method that involves computational study of blood flow in compliant arteries. Several arterial wall models, namely linear elastic, non-linear strain energy density formulations, including anisotropy of the wall, are applied to accurately predict hemodynamic parameters.  Click on link to see video of FSI simulation of a tapered femoral artery of a dog .

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 Figure 1:  Velocity profiles and shear stress for flow analysis of a physiologic reconstructed porcine aortic trifurcation

        Presently, many researchers are trying to focus on simulating geometries that are ‘true’ but not an idealized form of it.   Our recent studies provide a detailed methodology, from 3D-image reconstruction to flow analysis, for simulating the flow field in realistic arterial geometries.  The procedure takes advantage of the latest state of the art technology in solid modeling, and is illustrated by application to complicated aortic geometries.  The latest procedure on this subject is also discussed in the publications and research section on Thermal Ablation.  Figure 1 shows the velocity profiles and shear stress for flow analysis of a physiologic reconstructed porcine aortic trifurcation.  It is now possible to take MRI or CAT scan images and performs computational flow analysis within physiologic passageways.  

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by zopeown last modified 2007-12-05 10:51