Fluid structure interaction analysis of ascending thoracic aortic aneurysms: a comparison of prestressing algorithms

Advanced computational techniques, such as Fluid-Structure Interaction (FSI), to model Ascending thoracic Aortic Aneurysms (ATAA) may revolutionize the way precise medicine is performed. One major issue in modelling ATAA biomechanics is the need for the stress-free configuration which is unavailable from imaging data. The Zero Pressure Geometry (ZPG) and Prestress Tensor (PT) are the two main approaches to overcome this issue. However, their impact on the numerical results is yet to be analysed. In this work, three distinct tissue prestressing methodologies were employed and their impact on the numerical results was analysed. The selected tissue prestressing approaches were: (i) ZPG, (ii) PT and (iii) a combination of the PT algorithm with a regional mapping of calibrated material properties (PTCALIB). The results suggested that PT based approaches presented a close agreement with ZPG regarding ATAA hemodynamics. The PT model presented a significantly stiffer mechanical response than the ZPG model. The inclusion of a regional mapping of calibrated material properties contributed significantly to reduce these differences. Additionally, it was evident that PT based approaches contributed to significantly reduce the amount of iterations required to achieve cycle-to-cycle convergence.