On the Potential Self-Amplification of Aneurysms Due to Tissue Degradation and Blood Flow Revealed From FSI Simulations

Abstract

Tissue degradation plays a crucial role in the formation and rupture of aneurysms. Using numerical computer simulations, we study the combined effects of blood flow and tissue degradation on intra-aneurysm hemodynamics. Our computational analysis reveals that the degradation-induced changes of the time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI) within the aneurysm dome are inversely correlated. Importantly, their correlation is enhanced in the process of tissue degradation. Regions with a low TAWSS and a high OSI experience still lower TAWSS and higher OSI during degradation. Furthermore, we observed that degradation leads to an increase of the endothelial cell activation potential index, in particular, at places experiencing low wall shear stress. These findings are robust and occur for different geometries, degradation intensities, heart rates and pressures. We interpret these findings in the context of recent literature and argue that the degradation-induced hemodynamic changes may lead to a self-amplification of the flow-induced progressive damage of the aneurysmal wall.

The Role of Wall Mechanics in the Hemodynamics of a Realistic Abdominal Aortic Aneurysm: A Fluid-Structure Interaction Study

“…Te oscillatory shear index (OSI) is a hemodynamic parameter that measures the magnitude of the oscillations in shear stress that occur during the cardiac cycle. High OSI values have been associated with the development and progression of aneurysms and can lead to the activation of mechanosensitive signaling pathways within the endothelial cells that line the arterial wall [64].…”

Analysis of Intracranial Aneurysm Haemodynamics Altered by Wall Movement

“…Although the analysis of patient-specific cases remains an ultimate goal, it seems that simplified IA geometries are still missing for studying FSI-related phenomena in a more controlled manner. Except for the work of Wan et al [ 31 ], idealized geometries of sidewall aneurysms have always been investigated through rigid-wall CFD simulations [ 32 , 33 , 34 ], showing the sensitivity of haemodynamics towards various geometrical parameters. They were found to be very useful in particular for studying the impacts of certain modelling assumptions and boundary conditions [ 34 ], or highlighting specific and easily explainable trends that could be reproduced.…”

Aneurysmal growth in type-B aortic dissection: assessing the impact of patient-specific inlet conditions on key haemodynamic indices

“…Greater FL flow [ 6 ] and pressurization [ 7 ] have been associated with aortic growth in addition to retrograde flow through the PET [ 4 ] which has been associated with increased FL pressurization. Regions of high oscillatory shear index (OSI) and low time-averaged WSS (TAWSS) have been linked with aneurysmal growth and rupture in TBAD [ 6 ], creating a feedback loop of degradation as growth further exacerbates these effects [ 8 ].…”