Comparative analysis of Zero Pressure Geometry and prestress methods in cardiovascular Fluid-Structure Interaction

Area of Science:

• Computational Biomechanics
• Medical Imaging Analysis
• Cardiovascular Fluid Dynamics

Background:

• Patient-specific aortic biomechanics modeling is vital for clinical decision-making in Ascending Thoracic Aortic Aneurysms (ATAA).
• Accurate simulation of ATAA requires defining the stress-free configuration, with Zero Pressure Geometry (ZPG) and Prestress Tensor (PT) being key approaches.
• The impact of these prestressing methods on numerical simulation results remains under-analyzed.

Purpose of the Study:

• To compare the numerical results of different prestressing approaches for defining the reference configuration in patient-specific ATAA simulations.
• To evaluate the influence of Zero Pressure Geometry (ZPG), Prestress Tensor (PT), and a combined PT with regional material property mapping (PTCAL) on Fluid-Structure Interaction (FSI) models.
• To assess the convergence and accuracy of these methods for ATAA biomechanical analysis.

Main Methods:

• Development of three patient-specific 2-way Fluid-Structure Interaction (FSI) frameworks using Computed Tomography Angiography (CTA) and Magnetic Resonance Imaging (MRI) data.
• Implementation of distinct tissue prestressing strategies: Zero Pressure Geometry (ZPG), Prestress Tensor (PT), and Prestress Tensor with regional material property mapping (PTCAL).
• Comparative analysis of pressure fields, Wall Shear Stress (WSS) metrics, Relative Residence Time (RRT), and wall mechanics between the developed models.

Main Results:

• Pressure field estimations were consistent across all three models.
• Wall Shear Stress (WSS) metrics showed good agreement, with the exception of Relative Residence Time (RRT).
• The Prestress Tensor (PT) approach with regional material property mapping (PTCAL) demonstrated improved agreement with the Zero Pressure Geometry (ZPG) model for ATAA wall mechanics and required approximately 60% fewer iterations for convergence.

Conclusions:

• Combining the Prestress Tensor (PT) method with regional material property mapping (PTCAL) offers superior correspondence with the Zero Pressure Geometry (ZPG) approach for ATAA simulations.
• The Prestress Tensor (PT) methodology, particularly with regional property mapping, shows potential for enhancing the accuracy and convergence of numerical models for Ascending Thoracic Aortic Aneurysms.
• These findings can advance computational modeling in cardiovascular research and clinical practice for ATAA management.