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Title: Determination of flow patterns and stresses in patient-specific models of abdominal aortic aneurysms
Author: Leung, James
ISNI:       0000 0001 3608 5075
Awarding Body: Imperial College London (University of London)
Current Institution: Imperial College London
Date of Award: 2006
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Abdominal aortic aneurysm (AAA) is a localized dilation of the aorta. Some AAAs can rupture, an event with high mortality rate. A reliable predictor for AAA rupture is currently not available. Previous studies introduced wall stress as a better indicator of rupture with promising results. However, the views for obtaining peak wall stress are controversial. In this study, different methods for obtaining wall stress were compared. Wall stress was also compared with other rupture indicators, including AAA maximum diameter, curvature, and expansion rate. The purpose of this work was to continue the development of a suitable indicator for surgical management. An image processing program, developed in Madab, semi-autornatically reconstructed 9 AAA geometries and 3 control cases from CT iniages. A finite element method software package ADINA 8.2 was used to calculate wall stress. The quality and sensitivity of the software was verified through analytical and hypothetical models. Wan thickness was found to be the most sensitive geometric parameter to wall stress. A method to calculate the Gaussian curvature of AAA was developed, which can locate peak wall stress; however, it could not relate to the wall stress magnitude. Incorporating a pulsatile blood flow using a coupled fluid-structure simulation, did not alter the wall stress distribution significantly. However, adding thrombus to the model showed that ILT reduced wan stress by 17%-66%. Comparing the predicted strains to experimental data, obtained from literature, confirmed that these wall stress results were realistic. Hence, including ILT is essential. When comparing peak wall stress with AAA expansion rate, a 94% correlation was achieved. However., there was only a 34% correlation when compare with maximum diameter. The study has suggested that including thrombus is essential to calculating wall stress, which was also found to have a close relationship with expansion rate.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available