Wall Shear Stress Estimation of Thoracic Aortic Aneurysm Using Computational Fluid Dynamics

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Medical Imaging Analysis

Background:

• Thoracic aortic aneurysm (TAA) is a life-threatening condition characterized by arterial wall swelling, with rupture posing a significant risk.
• While imaging like CT and MRI visualize TAA, mathematical modeling is crucial for understanding dynamic stress behaviors.
• Wall shear stress (WSS) is a key factor in arterial wall integrity and aneurysm progression.

Purpose of the Study:

• To evaluate the effects of wall shear stress (WSS) on thoracic aortic aneurysms (TAA) using computational fluid dynamics (CFD).
• To develop a mathematical model for analyzing TAA dynamics and predicting rupture risk.
• To investigate the relationship between flow patterns, WSS, and potential cell damage within TAAs.

Main Methods:

• A 3D TAA model was reconstructed from CT scan slices.
• Computational fluid dynamics (CFD) analysis was performed using Star CCM+ with a polyhedral mesh and prism layers.
• Non-Newtonian and Newtonian fluid models were employed with pulsatile flow, and laminar-turbulent-laminar (LTL) flow behavior was considered.

Main Results:

• CFD analysis captured vortex formation and flow reversals, identifying potential sites for cell damage and clot formation.
• Deteriorating WSS was identified as a key indicator of potential TAA rupture, oscillating with cardiac cycles and stress conditions.
• The non-Newtonian model with pulsatile flow yielded a WSS of 15.29 Pa, comparable to the Newtonian model (16 Pa), while the non-Newtonian LTL model predicted a higher WSS of 20.1 Pa.

Conclusions:

• Mathematical modeling and CFD analysis offer valuable insights into the complex hemodynamics of TAA.
• WSS dynamics are critical for understanding TAA progression and rupture risk.
• Accurate modeling, considering non-Newtonian properties and pulsatile flow, is essential for predicting TAA behavior.