Iliacs Pressure vs Flow Profiles
Transcript of Iliacs Pressure vs Flow Profiles
Constant wall thickness and linear-elastic wall properties
Modeling of Subject Arterial Segments Using
3D Fluid Structure Interaction and 1D-0D
Arterial Tree Network Boundary Condition
Magnus Andersson, Jonas Lantz and Matts Karlsson
Department of Management and Engineering, Linköping University, Linköping, Sweden
The 6th international symposium on Biomechanics in Vascular Biology and Cardiovascular Disease, April 14-15, 2011, Rotterdam, The Netherlands.
Contact: [email protected]
WK3
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R2
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Elastic support ofsurrounding tissue
INTRODUCTIONIn recent years it has been possible to simulate 3D blood flow trough Computational Fluid Dynamics (CFD) including the dilatation effect in elastic arteries using Fluid-Structure Interaction (FSI) to better match in vivo data. Outlet boundary condition (BC) models have been shown crucial and difficult to implement accurately in order to capture realistic pressure reflection arising from the distal vascular bed.
Qin
11% of Qin is forced into each renal
METHODS
3D - FSI
REFERENCES[1] Heiberg E. et al, Time resolved three-dimensional automated segmentation of the left ventricle, Computers in Cardiology, Vol. 32, pp.599-602, 2005.
[2] Reymond P. et al, Validation of a one-dimensional model of the systemic arterial tree, Am. J. Physiol. Heart Circ. Physion., 297:H208-H222, 2009.
MRI acquisitionSubject specific MRI and PC-MRI scanning was utilized to acquire geometry and flow data respectively.
SegmentationThe MRI images were segmented using an in-house software (Segment, http://segment.heiberg.se,[1]) to obtaina 3D surface of the vessel lumen.
MeshThe surfaces was meshed with a high quality hexahedral elements using ANSYS ICEM CFD 12.0 (ANSYS Inc, Canonsburg, PA, USA).
This work focus on a full scaled FSI simulation at an arterial section obtained from Magnetic Resonance Imaging (MRI) data. The outlet BC at the iliac arteries is connected with a 1D-0D systemic arterial network. This 3D-(0D-1D) connection can provide the essential features of the peripheral flow , the 1D-0D coupling allow for investigation of cardiovascular diseases including stenoses and/or hypertension.
RESULTS
CONCLUSIONS
Deformation at peak systole for normal BP
1D-0D ArterialTree Network
Rightiliac (RI)
Left iliac (LI)
Prediction of the flow impedance at the iliac root boundaries for
Typical 1D vascular
stiffness
High (2x) 1D vascular
stiffness
1D-0D
Approximated iliac flow profiles
Normal BP Hypertension
Iliac pressure profiles
2-wayiterativescheme
3D-FSI Simulation
Solid Mechanics
Fluid Dynamics
Segment wall stiffnessTypical: 2.6 MPaHypertension: 3.9 MPa
3D-FSI modelThe FSI use a 2-way interactively scheme, ANSYS Multifield, for solving the pressure/displacement interaction at the shared interface.
Peripheral arterial segments are terminated with a three-element windkessel (WK3) model.
1D-0D modelThe arterial tree network is based on transmission-line theory represented by a complex flow impedance model for the pressure-flow relationship.
The arterial topology was extracted from literature [2] where only the central arteries was considered.
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Iliacs Pressure vs Flow Profiles
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RI Hypertension
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RI Normal Pressure
LI Normal Pressure
RI Volume Flow
LI Volume Flow
Instantaneous wall shear stress (WSS) at three different times in the cardiac cycle, max acceleration, peak systole and max deceleration, is presented for normal BP and hypertension.
The average WSS over one cardiac cycle was evaluated, revealing close similarities for both results.
Normal BP
Hyper-tension
Wall Shear Stress
Maxacc.
Peaksystole
Timeaverage
Maxdec.
This method allows for a better insight of large scale vascular networks effect of the local 3D flow features and also gives a better representation of the peripheral flow compared to a pure 0D (lumped parameter/Windkessel) model. PC-MRI will provide data for validation of velocity profiles in the 3D model. Future work includes a hyperelastic material model for 3D geometry as well a MRI-based subject specific 1D vascular topology to be combined with the 3D model.
Reduced PC-MRI flow profile Iliac pressure vs. flow profiles
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Two cases are studied, normal and high blood pressure(BP), for different vascular stiffness.
Segment wall stiffness is increase by 50 % at hypertension.