Exploring the Relationship between Morphological Parameters and Hemodynamic Characteristics in Ascending Thoracic Aortic Aneurysms Using Fluid-Structure Interaction with Patient-specific Models

• Author / Creator

  Xiao, Meng

• Ascending thoracic aortic aneurysm (ATAA) is an abnormal bulge in the ascending part of the aorta. It is associated with the risk of dissection and rupture and has been known as the "silent killer". When dissection or rupture, the outcome is usually severe and associated with high mortality. To prevent those adverse events from happening, surgical repair or replacement of the ascending aorta is necessary. The elective surgical criterion must be selected carefully to balance the risk of surgery and the risk of the adverse aortic events associated with ATAA. Current clinical guidelines were purely diameter based and established based on the natural history study of ATAA. However, recent findings have shown that diameter alone is a not good predictor and hence incorporating other parameters such as ascending aortic length (AAL) into the current clinical standard is desired.
  With the development of computer technology, computational fluid dynamics and finite elements analysis have emerged as useful tools in cardiovascular studies. By employing those computational methods, researchers could study the interaction of the blood flow with the aortic wall and gain insights into the pathology of ATAA. A pathological flow can trigger vascular remodelling and subsequent wall degeneration, resulting in ATAA formation. In this thesis, we hypothesized that the change in morphology of the aorta results in the worsening of hemodynamic conditions, which subsequently initiates aortic wall degeneration. we perform a comprehensive fluid-structure interaction analysis to simulate the blood-aortic wall interaction.
  By assessing the hemodynamic characteristics of ATAA with different morphologies, we confirmed that aortic elongation was associated with the worsening in hemodynamics in ATAA, providing more evidence of using AAL as a surgical indicator. The correlations between AAL and various hemodynamic parameters were comparable to the correlations between diameter and those parameters, meaning that aortic elongation can negatively impact the flow conditions as aortic dilation does. A strong association was also found between the increase in AAV and compromised hemodynamic conditions. Thus, we propose to incorporate AAV, a 3D parameter, into the current clinical elective surgery criterion to account for the variation in the entire aortic geometry instead of just the largest part. Compared with diameter and AAL, AAV showed higher statistical significance and stronger associations with hemodynamic and biomechanical parameters. Hence, by using AAV as an independent or in combination with AAL and diameter, a better prediction might be achieved.

• Subjects / Keywords

  • Aortic Aneurysms
  • Fluid-Structure Interaction
  • Hemodynamics
  • FSI
  • CFD
  • Cardiovascular disease

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-dcth-9c38

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.