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TECHNICAL PAPERS: Fluids/Heat/Transport

# Comparison of Left Anterior Descending Coronary Artery Hemodynamics Before and After Angioplasty

[+] Author and Article Information
S. D. Ramaswamy, S. C. Vigmostad

Department of Biomedical Engineering, University of Iowa, Iowa City, Iowa 52242

A. Wahle, M. E. Olszewski, M. Sonka

Department of Electrical and Computer Engineering, University of Iowa, Iowa City, Iowa 52242

Y.-G. Lai

IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, Iowa 52242

K. C. Braddy, T. M. Brennan, J. D. Rossen

Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242

K. B. Chandran1

Department of Biomedical Engineering and IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, Iowa 52242Chandran@engineering.uiowa.edu

1

Corresponding author.

J Biomech Eng 128(1), 40-48 (Sep 21, 2005) (9 pages) doi:10.1115/1.2132371 History: Received February 09, 2005; Revised September 21, 2005

## Abstract

Coronary artery disease (CAD) is characterized by the progression of atherosclerosis, a complex pathological process involving the initiation, deposition, development, and breakdown of the plaque. The blood flow mechanics in arteries play a critical role in the targeted locations and progression of atherosclerotic plaque. In coronary arteries with motion during the cardiac contraction and relaxation, the hemodynamic flow field is substantially different from the other arterial sites with predilection of atherosclerosis. In this study, our efforts focused on the effects of arterial motion and local geometry on the hemodynamics of a left anterior descending (LAD) coronary artery before and after clinical intervention to treat the disease. Three-dimensional (3D) arterial segments were reconstructed at 10 phases of the cardiac cycle for both pre- and postintervention based on the fusion of intravascular ultrasound (IVUS) and biplane angiographic images. An arbitrary Lagrangian-Eulerian formulation was used for the computational fluid dynamic analysis. The measured arterial translation was observed to be larger during systole after intervention and more out-of-plane motion was observed before intervention, indicating substantial alterations in the cardiac contraction after angioplasty. The time averaged axial wall shear stress ranged from $−0.2to9.5Pa$ before intervention compared to $−0.02to3.53Pa$ after intervention. Substantial oscillatory shear stress was present in the preintervention flow dynamics compared to that in the postintervention case.

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## Figures

Figure 1

Three-dimensional mesh geometry including extensions: (a) for the before intervention with details of stenosed segment with slices shown; (b) for the after intervention, with details of previously stenosed segment shown.

Figure 2

Flow rate vs time curve with mean flow rate superimposed. 0% corresponds to the end diastolic phase of the cardiac cycle.

Figure 3

Three-dimensional motion of centerline contours during a cardiac cycle: (a) before intervention; (b) after intervention; (c) motion of the centroid of cross sections A–J during a cardiac cycle for the before intervention case; (d) corresponding plot for the after intervention case. “●” denotes the end diastolic (0%) phase and “X” denotes the 90% phase.

Figure 4

Axial velocity profile at slice D, F, H at 30% (a) before intervention, (b) after intervention. Inner wall (I) depicts the local innermost curvature at the respective cross sections and the outer wall (O) depicts the diametrically opposite point in the cross section.

Figure 5

Axial velocity profile at section D, F, H at 70% (a) before intervention, (b) after intervention. Inner wall (I) depicts the local innermost curvature at the respective cross sections and the outer wall (O) depicts the diametrically opposite point in the cross section.

Figure 6

Spanwise vorticity plots at 30% (peak forward flow, top row) and 70% (middiastole, bottom row) phases in the cardiac cycle. The plots for before intervention are in the left column and for the after intervention are in the right column.

Figure 7

Normalized WSS at cross sections D, F, J at 30% phase for the before and after intervention cases. Inner wall (I) depicts the local innermost curvature at the respective cross-sections and the outer wall (O) depicts the diametrically opposite point in the cross section.

Figure 8

Normalized WSS at cross sections D, F, J at 70% (middiastolic phase) for the before and after intervention cases. Inner wall (I) depicts the local innermost curvature at the respective cross sections and the outer wall (O) depicts the diametrically opposite point in the cross section.

Figure 9

Time averaged WSS at cross sections D, F, J for the before and after intervention cases.

Figure 10

Oscillatory shear index plots for the before and after intervention cases: (a) along the local inner wall of curvature; (b) along the lateral wall; and (c) along the outer wall of the arterial segment.

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