Date of Award
2025
Document Type
Open Access Master's Thesis
Degree Name
Master of Science in Biomedical Engineering (MS)
Administrative Home Department
Department of Biomedical Engineering
Advisor 1
Jingfeng Jiang
Committee Member 1
Sean J. Kirkpatrick
Committee Member 2
William Cooke
Abstract
Aortic dissection is a serious vascular condition typically triggered by a tear in the inner layer of the aortic wall. The widespread occurrence of the disease emphasizes the need for standardized treatment and surgical guidelines. There have been improved strategies for surgical intervention and treatment of aortic dissection over the years. However, there remains a gap in monitoring of dissection growth specifically in the pre-surgical period of the disease. Hemodynamic studies based on CFD have shown insightful results regarding false lumen dilatation, aneurysmal growth and thrombus formation in post surgical and endovascular repaired cases. Also, the application of different outlet boundary conditions, in the absence of patient-specific data, can lead to substantial variations in flow dynamics in CFD-based analyses of aortic dissection (AD). In this study, hemodynamic parameters including luminal pressure difference (LPD), time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), relative residence time (RRT), endothelial cell activation potential (ECAP), and the number of combined vortex cores in the false lumen were evaluated under two simulation settings: zero-pressure outlets and pressure waveform outlets. All cases represented pre-treatment stages with variable disease onset times. Morphological characteristics such as maximum false lumen diameter, false lumen volume, and primary and re-entry tear areas were also quantified. Although the parameters did not differ markedly between type A and type B dissections, considerable variations
in flow and pressure parameters were observed between the two boundary condition groups. The relative differences in several key parameters between the two conditions exceeded 100% in most cases (LPD: 144.27%, number of vortex cores: 132.02%, TAWSS: 105.74%). In condition 1 (zero-pressure outlets), the absence of downstream vascular impedance resulted in unrealistically low pressure difference values, whereas condition 2 (pressure waveform outlets) produced higher and more physiologically representative pressures due to the inclusion of pulsatile effects. The altered inflow behavior in condition 2 also led to an increased number of vortex cores in larger false lumens particularly observed in partially thrombosed cases. Additionally, TAWSS values were consistently low across both conditions, suggesting a potential contribution to false lumen thrombus formation and progressive dilatation over time. Overall, the use of zero-pressure outlet conditions can significantly distort flow dynamics and yield hemodynamically unrealistic results in aortic dissection simulations.
Recommended Citation
Tun Suha, Khadiza, "Computational Hemodynamic Analysis of Pre-treatment Type A and Type B Aortic Dissections", Open Access Master's Thesis, Michigan Technological University, 2025.