Prestressing Algorithms for Arterial Wall Mechanics: Analysis of the Robustness and Uniqueness

Simulations of arterial wall mechanics often use image-based data to define the in vivo geometry. This state is not stress-free, and prestressing algorithms are required to ensure mechanical equilibrium given the corresponding in vivo boundary conditions. This study aims to investigate the uniqueness of prestressing algorithms in numerical simulations of the arterial wall and to evaluate their impact on conclusions drawn from clinical studies. To assess the uniqueness of prestressing algorithms, we varied the initial guess within an iterative prestressing algorithm and compared the results with an alternative approach assuming a constant prestretch across the arterial wall. Furthermore, we conducted a comparative analysis by calculating the risk of dissection or rupture in ascending thoracic aortic aneurysms using various prestressing algorithms. Our findings demonstrate that the mechanical equilibrium between the in vivo geometry and boundary conditions is not uniquely defined without additional knowledge of the tissue's ex vivo stress-free state. One possible solution to address this challenge is to impose a prior transmural distribution of prestretch based on well-founded experimental observations, if available. It is crucial to recognize this non-unqiueness and to assess its influence on the output of the model for which the prestressing algorithm is used.