2 research outputs found
A one-dimensional hemodynamic model of the coronary arterial tree
One-dimensional (1D) hemodynamic models of arteries have increasingly been applied to coronary circulation. In this study, we have adopted flow and pressure profiles in Olufsen's 1D structured tree as coronary boundary conditions, with terminals coupled to the dynamic pressure feedback resulting from the intra-myocardial stress because of ventricular contraction. We model a trifurcation structure of the example coronary tree as two adjacent bifurcations. The estimated results of blood pressure and flow rate from our simulation agree well with the clinical measurements and published data. Furthermore, the 1D model enables us to use wave intensity analysis to simulate blood flow in the developed coronary model. Six characteristic waves are observed in both left and right coronary flows, though the waves' magnitudes differ from each other. We study the effects of arterial wall stiffness on coronary blood flow in the left circumflex artery (LCX). Different diseased cases indicate that distinct pathological reactions of the cardiovascular system can be better distinguished through Wave Intensity analysis, which shows agreement with clinical observations. Finally, the feedback pressure in terminal vessels and measurement deviation are also investigated by changing parameters in the LCX. We find that larger feedback pressure increases the backward wave and decreases the forward one. Although simplified, this 1D model provides new insight into coronary hemodynamics in healthy and diseased conditions. We believe that this approach offers reference resources for studies on coronary circulation disease diagnosis, treatment and simulation
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Patient-specific blood flow modelling in diagnosis of coronary artery disease
This thesis presents the approach for development of patient-specific coronary blood flow models in 3D and 0D domains based on coronary artery geometries reconstructed from Coronary Computed Tomography Angiography datasets (CCTA). The computed flow patterns extend the diagnostic value of CCTA, which, being noninvasive imaging modality, provides only static information on the anatomy of epicardial arteries. The clinical indices extracted from the virtual blood flow can be potentially employed in the assessment of the haemodynamic severity of Coronary Artery Disease (CAD) lesions as well at the analysis of the underlying mechanisms of formation and localisation of atherosclerotic plaques.
However, the existing patient-specific coronary blood flow modelling approaches are generally characterised by relatively high levels of uncertainty and instability due to a number of unknown factors and modelling assumptions. Analysis and comparison of the impact of various modelling assumptions has the potential to reduce this uncertainty. The overarching contributions of this thesis are the thorough analysis and investigation of the existing issues in patient-specific coronary blood flow simulations and the provision of the guidelines for the design and implementation of blood flow models in order to improve and ensure the reliability and accuracy of the numerical results.
In addition, a novel approach for the implementation of spatially extended patient-specific 0D blood flow models was proposed, which significantly decreases the high computational costs generally associated with 3D blood flow simulations. While the classical 0D models based on the electrical–hydraulic analogy use the lumped-parameter representation of major vessel tree structures and are thus characterised by limited spatial characteristics, the proposed method for modelling of individual vessel tree branches through a series of 0D elements provides the means for correlation of the computed flow with the precise location along a vessel. Therefore, this extends the applicability of 0D modelling in patient-specific blood flow simulations for the assessment of functional stenosis severity