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Research Papers

Computation of Hemodynamics in Tortuous Left Coronary Artery: A Morphological Parametric Study

[+] Author and Article Information
Xinzhou Xie

Department of Electronic Engineering,
Fudan University,
Shanghai 200433, China
e-mail: 10110720031@fudan.edu.cn

Yuanyuan Wang

Department of Electronic Engineering,
Fudan University,
Shanghai 200433, China
Key Laboratory of Medical
Imaging Computing and Computer
Assisted Intervention of Shanghai,
Shanghai 200433, China
e-mail: yywang@fudan.edu.cn

Hongmin Zhu

Department of Cardiology,
Sixth People's Hospital,
Jiao Tong University,
Shanghai 200233, China
e-mail: zhm0004@163.com

Jingmin Zhou

Department of Cardiology,
Zhongshan Hospital,
Fudan University,
Shanghai 200032, China
e-mail: zhou.jingmin@zs-hospital.sh.cn

1Corresponding author.

Manuscript received March 26, 2014; final manuscript received July 14, 2014; accepted manuscript posted July 22, 2014; published online August 6, 2014. Assoc. Editor: Dalin Tang.

J Biomech Eng 136(10), 101006 (Aug 06, 2014) (8 pages) Paper No: BIO-14-1137; doi: 10.1115/1.4028052 History: Received March 26, 2014; Revised July 14, 2014; Accepted July 22, 2014

Coronary tortuosity (CT) would alter the local wall shear stress (WSS) and may become a risk factor for atherosclerosis. Here we performed a systematic computational study to relate CT morphological parameters to abnormal WSS, which is a predisposing factor to the formation of atherosclerotic lesions. Several idealized left coronary artery (LCA) models were created to conduct a series of morphological parametric studies, in which we concentrate on three specific morphological parameters, the center line radius (CLR), the bend angle (BA), and the length between two adjust bends (LBB). The time averaged WSS (TAWSS), the oscillatory shear index (OSI), and the time averaged WSS gradient (WSSGnd) were explored by using the computational fluid dynamics (CFD) method, in order to determine susceptible sites for the onset of early atherosclerosis. In addition, two realistic LCA models were reconstructed to further validate the finding's credibility. The CLR and LBB had great impact on the distributions of WSS-derived parameters, while the BA had minor impact on the hemodynamic of the tortuous arteries. Abnormal regions with low TAWSS (TAWSS < 0.5 Pa), high OSI (OSI > 0.1) and high WSSGnd (WSSGnd > 8) were observed at the inner wall of bend sections in the models with small CLR or small LBB. These findings were also confirmed in the realistic models. Severe CT with small CLR or LBB would lead to the formation of abnormal WSS regions at the bend sections and providing these regions with favorable conditions for the onset and/or progression of atherosclerosis.

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References

Figures

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Fig. 1

Vascular geometry and boundary conditions. (a) Idealized geometry model and three morphological parameters: the CLR, the BA, and the LBB. (b) Two realistic LCA models. (c) The normalized boundary velocity waveform used at the inlet.

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Fig. 5

The distribution of WSS-derived parameters for a LCX model. The 3D contours were shown in three different views: left view, front view, and right view.

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Fig. 4

The distribution of WSS-derived parameters for a LAD model. The 3D contours were shown in three different views: left view, front view, and right view.

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Fig. 3

Contours of the WSS-derived parameters for different LBB and flow rate. WSS-derived parameters were unwrapped from the artery wall surface and mapped onto a rectangle (the first 2 cm of the inlet extension and the last 2 cm of the outlet extension are cut off). (a) WSS-derived parameters for five different LBBs (CLRs and BAs were kept constant for five models: CLR = 4.5 mm and BA = 60 deg). (b) Position illustration of line 1 and line 2. (c) WSS-derived parameters for three different flow rates (CLRs, Bas, and LBBs were kept constant for three models: CLR = 3.0 mm, BA = 60 deg, and LBB = 0 mm).

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Fig. 2

Contours of the WSS-derived parameters for different CLRs and BAs. WSS-derived parameters were unwrapped from the artery wall surface and mapped onto a rectangle (the first 2 cm of the inlet extension and the last 2 cm of the outlet extension are cut off). (a) WSS-derived parameters for three different CLRs (BAs and LBBs were kept constant for three models: BA = 90 deg and LBB = 9 mm). (b) Position illustration of line 1 and line 2. (c) WSS-derived parameters for four different BAs (CLRs and LBBs were kept constant for four models: CLR = 4.5 mm and LBB = 9 mm).

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