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TECHNICAL PAPERS: Fluids/Heat/Transport

Computational Analysis of Blood Flow in an Integrated Model of the Left Ventricle and the Aorta

[+] Author and Article Information
Masanori Nakamura1

Department of Bioengineering and Robotics, Physiological Flow Studies Laboratory, Graduate School of Engineering,  Tohoku University, Aoba 01, Sendai 980-8579, Japanmasanorin@pfsl.mech.tohoku.ac.jp

Shigeo Wada2

Department of Bioengineering and Robotics, Graduate School of Engineering,  Tohoku University, Sendai 980-8579, Japan

Takami Yamaguchi

Department of Bioengineering and Robotics, Graduate School of Engineering,  Tohoku University, Sendai 980-8579, Japan

1

Corresponding author; Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Japan; e-mail: masanori@me.es.osaka-u.ac.jp

2

Department of Mechanical Science and Bioengineering, Graduate School of Engineering Science, Osaka University, Toyonaka 560-8531, Japan.

J Biomech Eng 128(6), 837-843 (Apr 26, 2006) (7 pages) doi:10.1115/1.2400864 History: Received March 24, 2004; Revised April 26, 2006

To study the effects of intraventricular flow dynamics on the aortic flow, we created an integrated model of the left ventricle and aorta and conducted a computer simulation of diastolic and systolic blood flow within this model. The results demonstrated that the velocity profile at the aortic annulus changed dynamically, and was influenced by the intraventricular flow dynamics. The profile was almost flat in early systole but became nonuniform as systole progressed, and was skewed toward the posterior side in midsystole and toward the anterior side in later systole. At a distance from the aortic annulus, a different velocity profile was induced by the twisting and torsion of the aorta. In the ascending aorta, the fastest flow was initially located in the posteromedial sector, and it moved to the posterior section along the circumference as systole progressed. The nonuniformity of the aortic inflow gave rise to a complex wall shear stress (WSS) distribution in the aorta. A comparison of the WSS distribution obtained in this integrated analysis with that obtained in flow calculations using an isolated aorta model with Poiseuille and flat inlet conditions showed that intraventricular flow affected the WSS distribution in the ascending aorta. These results address the importance of an integrated analysis of flow in the left ventricle and aorta.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 5

Streamlines of the intraventricular diastolic flow during a cardiac cycle as viewed from the left of the body with the anterior side toward the left: (a) onset of diastole, t=0.01s; (b) midpoint of the rapid ventricular filling phase, t=0.16s; (c) end of the rapid ventricular filling phase, t=0.303s; (d) just after the onset of systole t=0.420s; (e) midpoint of systole t=0.565s; and (f) end of systole t=0.749s

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Figure 6

Contour plots of the aortic inflow velocity normal to the aortic orifice and vector plots of the secondary flow at the aortic annulus: (a) just after the onset of systole t=0.420s; (b) at the midpoint of systole t=0.565s; and (c) at the end of systole t=0.749s. The images are viewed from the aortic side with the anterior side toward the top.

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Figure 7

Contour plots of the aortic inflow velocity normal to the aortic orifice and vector plots of the secondary flow at a cross section 4.85cm distal to the aortic annulus (a) just after the onset of systole t=0.420s; (b) at the midpoint of systole t=0.565s; and (c) at the end of systole t=0.749s. The images are viewed from the aortic side with the anterior side toward the top.

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Figure 8

Contour plots of the wall shear stress distribution in the aorta at the midpoint of systole t=0.565s calculated for different inflow conditions: (a) the left ventricle is attached; (b) Poiseuille inflow; and (c) flat inflow. The upper and lower figures show the aorta models viewed from the left and right, respectively.

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Figure 9

Comparison of the wall shear stress distribution in the aorta at the midpoint of systole t=0.565s calculated for given different inflow conditions along lines to the (b) left, (c) inside, (d) right, and (e) outside of the aorta. The lines along which the WSS is shown are depicted in (a). The cross sections of the aorta model used as the abscissa of the graphs are numbered from the inlet, and cross sections 20, 40, 60, and 80 are illustrated in (a).

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Figure 1

(a) Definition of the locations of P1–P6, α and β, and the centerline of the aorta; (b) and finite element model of the unit circle used to construct the aorta model and left ventricle model

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Figure 2

Examples of Ψ in the left ventricle model: (MV) mitral valve; (AV) aortic valve

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Figure 3

Computational grid of the model: (a) front view of the model as seen from the anterior side; and (b) side view of the model as seen from the left

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Figure 4

Temporal variation in the volume change of the left ventricle

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