Patient-specific modeling of the biomechanics of vulnerable coronary artery plaques

Mahmoudi, Mostafa (2022) Patient-specific modeling of the biomechanics of vulnerable coronary artery plaques. Doctoral thesis, Northern Arizona University.

Text Mahmoudi_2022_patient-specific_modeling_biomechanics_vulnerable_corona.pdf - Published Version Download (11MB)

Abstract

Coronary artery atherosclerosis is a local, multifactorial, complex disease, and the leading cause of death in the US. Complex interactions between biochemical transport and biomechanical forces influence disease growth. Wall shear stress (WSS) affects coronary artery atherosclerosis by inducing endothelial cell mechanotransduction and by controlling the near- wall transport processes involved in atherosclerosis. The current management guidelines for detection of atherosclerotic plaques focus on morphological characterizations and the blockage percentage of the stenosis based on coronary computed tomography angiography (CCTA). Despite the progress achieved in therapeutics, the relation between hemodynamic environment and the composition of atherosclerotic plaques remains unexplored. This dissertation is divided into two main sections: the association between hemodynamics/biotransport and longitudinal changes in the plaque vulnerability characteristics and developing a 1D automatic vascular network generation package with the ability to be coupled with a 3D patient-specific model. Biochemical-specific mass transport models were developed to study low-density lipoprotein, nitric oxide, adenosine triphosphate, oxygen, monocyte chemoattractant protein-1, and monocyte transport. The transport results were compared with WSS vectors and WSS Lagrangian coherent structures (WSS LCS). High WSS magnitude protected against atherosclerosis by increasing the production or flux of atheroprotective biochemicals and decreasing the near-wall localization of atherogenic biochemicals. Low WSS magnitude promoted atherosclerosis by increasing atherogenic biochemical localization. To find the association between hemodynamics/biotransport and longitudinal changes in the atherosclerotic plaque characteristics, a plaque quantification software was developed with the aim of performing a segment-specific assessment to accurately calculate the volumes of low attenuation plaque (LAP), fibrous plaque (FP), calcium plaque (CP), and vessel wall and identify the quantitative plaque characteristics including spotty calcification, presence of napkin-ring sign, and positive remodeling. The changes in the different plaque characteristics were compared against the hemodynamic/biotransport parameters. The results showed that WSS magnitude is moderately correlated with the longitudinal changes in LAP, FP, and vessel wall volumes. Also, WSS magnitude and local concentration of nitric oxide (NO) showed a meaningful correlation with the presence of positive remodeling in the follow-up. A hybrid 1D-3D solver was developed in Simvascular software and validated against the existing data in the literature. The results of our coupled 1D-3D solver showed a good agreement with the 3D, deformable wall models. This solver can be used to solve the blood flow in a large network of 1D vessels coupled with a patient-specific 3D model. Finally, an automatic vascular network generation framework was developed using the Constraint Constructive Optimization (CCO) algorithm to study the generation of arterial trees based on theoretical perfusion maps. The algorithm simulated angiogenesis by optimizing the total vessel volume governed by physiological and geometrical constraints.

Item Type:	Thesis (Doctoral)
Publisher’s Statement:	© Copyright is held by the author. Digital access to this material is made possible by the Cline Library, Northern Arizona University. Further transmission, reproduction or presentation of protected items is prohibited except with permission of the author.
Keywords:	Automatic arterial tree generation; Biochemical transport; Coronary artery disease; coupled 1D-3D solver; Mechanotransduction; Vulnerable plaque quantification
Subjects:	Q Science > QP Physiology
MeSH Subjects:	E Analytical,Diagnostic and Therapeutic Techniques and Equipment > E07 Equipment and Supplies
NAU Depositing Author Academic Status:	Student
Department/Unit:	Graduate College > Theses and Dissertations College of Engineering, Informatics, and Applied Sciences > Mechanical Engineering
Date Deposited:	06 Jun 2023 16:45
Last Modified:	18 Aug 2023 08:30
URI:	https://openknowledge.nau.edu/id/eprint/5964

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