# Fluid-structure interaction analysis for abdominal aortic aneurysms: the role of multi-layered tissue architecture and intraluminal thrombus

## TL;DR

This study uses biomechanical modeling to show how the layered structure of the aortic wall and blood clots affect stress in abdominal aortic aneurysms, improving rupture risk prediction.

## Contribution

The study introduces a multi-layered tissue model and evaluates the biomechanical impact of intraluminal thrombus in AAA under various conditions.

## Key findings

- The media layer is the primary load-bearing component in the aortic wall.
- Intraluminal thrombus reduces overall stress but its effect on peak stress location varies.
- Media degradation increases stress in other layers, but ILT helps mitigate this.

## Abstract

Abdominal aortic aneurysm (AAA) is a life-threatening disease marked by localized dilatations of the infrarenal aortic wall. While clinical guidelines often use the aneurysm diameter as an indicator for surgical intervention, this metric alone may not reliably predict rupture risks, underscoring the need for detailed biomechanical analyses to improve risk assessments.

We investigate the effects of the multi-layered tissue architecture and the intraluminal thrombus (ILT) on the wall stress distribution of AAA. Using fluid-structure interaction, we analyze the biomechanical responses of fusiform and saccular AAAs under three conditions: without ILT, with ILT but no tissue degradation, and with both ILT and tissue degradation.

The findings show that the media is the primary load-bearing layer, and the multi-layered model yields a more accurate stress profile than the single-layered tissue model. The ILT substantially reduces overall stress levels in the covered tissue, although its impact on the location of peak stress varies across different scenarios. Media degradation increases the stress in the intima and adventitia, but the cushioning effect of ILT largely mitigates this impact.

The results underscore the importance of incorporating the multi-layered tissue architecture and ILT in patient-specific analyses of AAA. These factors may improve the predictive capabilities of biomechanical assessments for rupture risk.