Haemodynamics analysis of carotid artery stenosis and carotid artery stenting

Carotid stenosis is a local narrowing of the carotid artery, and is usually found in the internal carotid artery. The presence of a high-degree stenosis in a carotid artery may provoke transition from laminar to turbulent flow during part of the cardiac cycle. Turbulence in blood flow can influence...

Full description

Saved in:

Bibliographic Details
Main Author:	Nasrul Hadi, Johari
Format:	Thesis
Language:	English
Published:	2019
Subjects:	QP Physiology
Online Access:	http://umpir.ump.edu.my/id/eprint/31317/1/Haemodynamics%20analysis%20of%20carotid%20artery%20stenosis%20and%20carotid%20artery.pdf
Tags:	Add Tag No Tags, Be the first to tag this record!

id	my-ump-ir.31317
record_format	uketd_dc
spelling	my-ump-ir.313172021-04-23T04:08:06Z Haemodynamics analysis of carotid artery stenosis and carotid artery stenting 2019-05 Nasrul Hadi, Johari QP Physiology Carotid stenosis is a local narrowing of the carotid artery, and is usually found in the internal carotid artery. The presence of a high-degree stenosis in a carotid artery may provoke transition from laminar to turbulent flow during part of the cardiac cycle. Turbulence in blood flow can influence haemodynamic parameters such as velocity profiles, shear stress and pressure, which are important in wall remodelling. Patients with severe stenosis could be treated with a minimally invasive clinical procedure, carotid artery stenting (CAS). Although CAS has been widely adopted in clinical practice, the complication of in-stent restenosis (ISR) has been reported after CAS. The incidence of ISR is influenced by stent characteristics and vessel geometry, and correlates strongly with regions of neointimal hyperplasia (NH). Therefore, the main purpose of this study is to provide more insights into the haemodynamics in stenosed carotid artery and in post-CAS geometries via computational simulation. The first part of the thesis presents a computational study on flow features in a stenotic carotid artery bifurcation using two computational approaches, large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) incorporating the Shear Stress Transport model with the γ-Reθ transition (SST-Tran) models. The computed flow patterns are compared with those measured with particle image velocimetry (PIV). The results show that both SST-Tran and LES can predict the PIV results reasonably well, but LES is more accurate especially at locations distal to the stenosis where flow is highly disturbed. The second part of the thesis is to determine how stent strut design may influence the development of ISR at the carotid artery bifurcation following CAS. Key parameters that can be indicative of ISR are obtained for different stent designs and compared; these include low and oscillating wall shear stress (WSS),high residence time, and wall stress. A computationally efficient methodology is employed to reproduce stent strut geometry. This method facilitates the accurate reconstruction of actual stent geometry and details of strut configuration and its inclusion in the fluid domain. Computational simulations for flow patterns and low-density lipoprotein (LDL) transport are carried out in order to investigate spatial and temporal variations of WSS and LDL accumulation in the stented carotid geometries. Furthermore, finite element (FE) analysis is performed to evaluate the wall stress distribution with different stent designs. The results reveal that the closed-cell stent design is more likely to create atheroprone and procoagulant flow conditions, causing larger area to be exposed to low wall shear stress (WSS), elevated oscillatory shear index, as well as to induce higher wall stress compared to the open-cell stent design. This study also demonstrates the suitability of SST-Tran and LES models in capturing the presence of complex flow patterns in post-stenotic region. 2019-05 Thesis http://umpir.ump.edu.my/id/eprint/31317/ http://umpir.ump.edu.my/id/eprint/31317/1/Haemodynamics%20analysis%20of%20carotid%20artery%20stenosis%20and%20carotid%20artery.pdf pdf en public phd doctoral Imperial College London Department of Chemical Engineering
institution	Universiti Malaysia Pahang Al-Sultan Abdullah
collection	UMPSA Institutional Repository
language	English
topic	QP Physiology
spellingShingle	QP Physiology Nasrul Hadi, Johari Haemodynamics analysis of carotid artery stenosis and carotid artery stenting
description	Carotid stenosis is a local narrowing of the carotid artery, and is usually found in the internal carotid artery. The presence of a high-degree stenosis in a carotid artery may provoke transition from laminar to turbulent flow during part of the cardiac cycle. Turbulence in blood flow can influence haemodynamic parameters such as velocity profiles, shear stress and pressure, which are important in wall remodelling. Patients with severe stenosis could be treated with a minimally invasive clinical procedure, carotid artery stenting (CAS). Although CAS has been widely adopted in clinical practice, the complication of in-stent restenosis (ISR) has been reported after CAS. The incidence of ISR is influenced by stent characteristics and vessel geometry, and correlates strongly with regions of neointimal hyperplasia (NH). Therefore, the main purpose of this study is to provide more insights into the haemodynamics in stenosed carotid artery and in post-CAS geometries via computational simulation. The first part of the thesis presents a computational study on flow features in a stenotic carotid artery bifurcation using two computational approaches, large eddy simulation (LES) and Reynolds-averaged Navier-Stokes (RANS) incorporating the Shear Stress Transport model with the γ-Reθ transition (SST-Tran) models. The computed flow patterns are compared with those measured with particle image velocimetry (PIV). The results show that both SST-Tran and LES can predict the PIV results reasonably well, but LES is more accurate especially at locations distal to the stenosis where flow is highly disturbed. The second part of the thesis is to determine how stent strut design may influence the development of ISR at the carotid artery bifurcation following CAS. Key parameters that can be indicative of ISR are obtained for different stent designs and compared; these include low and oscillating wall shear stress (WSS),high residence time, and wall stress. A computationally efficient methodology is employed to reproduce stent strut geometry. This method facilitates the accurate reconstruction of actual stent geometry and details of strut configuration and its inclusion in the fluid domain. Computational simulations for flow patterns and low-density lipoprotein (LDL) transport are carried out in order to investigate spatial and temporal variations of WSS and LDL accumulation in the stented carotid geometries. Furthermore, finite element (FE) analysis is performed to evaluate the wall stress distribution with different stent designs. The results reveal that the closed-cell stent design is more likely to create atheroprone and procoagulant flow conditions, causing larger area to be exposed to low wall shear stress (WSS), elevated oscillatory shear index, as well as to induce higher wall stress compared to the open-cell stent design. This study also demonstrates the suitability of SST-Tran and LES models in capturing the presence of complex flow patterns in post-stenotic region.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Nasrul Hadi, Johari
author_facet	Nasrul Hadi, Johari
author_sort	Nasrul Hadi, Johari
title	Haemodynamics analysis of carotid artery stenosis and carotid artery stenting
title_short	Haemodynamics analysis of carotid artery stenosis and carotid artery stenting
title_full	Haemodynamics analysis of carotid artery stenosis and carotid artery stenting
title_fullStr	Haemodynamics analysis of carotid artery stenosis and carotid artery stenting
title_full_unstemmed	Haemodynamics analysis of carotid artery stenosis and carotid artery stenting
title_sort	haemodynamics analysis of carotid artery stenosis and carotid artery stenting
granting_institution	Imperial College London
granting_department	Department of Chemical Engineering
publishDate	2019
url	http://umpir.ump.edu.my/id/eprint/31317/1/Haemodynamics%20analysis%20of%20carotid%20artery%20stenosis%20and%20carotid%20artery.pdf
_version_	1783732165601656832

Haemodynamics analysis of carotid artery stenosis and carotid artery stenting

Similar Items