Modelling evolution and the evolving mechanical environment of saccular cerebral aneurysms

Area of Science:

• Biomedical Engineering
• Computational Fluid Dynamics
• Vascular Biology

Background:

• Cerebral aneurysms are life-threatening vascular diseases.
• Current models often simplify the complex biological and mechanical processes involved in aneurysm evolution.
• Understanding the interplay between hemodynamics and tissue remodeling is crucial for predicting aneurysm growth.

Purpose of the Study:

• To develop and utilize a novel fluid-solid-growth (FSG) model for simulating saccular cerebral aneurysm evolution.
• To investigate the role of elastin degradation and collagen remodeling in aneurysm formation and stabilization.
• To quantify the mechanical environment, including tissue stretching, within developing aneurysms.

Main Methods:

• A realistic two-layered structural model of the internal carotid artery was employed.
• The model incorporated elastin degradation and collagen growth and remodeling (G&R).
• Hemodynamic parameters, including wall shear stress (WSS), and tissue stretching were analyzed under steady and pulsatile flow conditions.

Main Results:

• Localized elastin degradation initiated aneurysm formation, leading to altered hemodynamics.
• Low WSS was identified as a key factor driving subsequent elastin degradation and aneurysm growth.
• A novel index for quantifying tissue biaxial stretching was proposed and utilized.

Conclusions:

• The developed FSG model successfully simulates saccular cerebral aneurysm evolution.
• The study highlights the critical link between low WSS, tissue degradation, and aneurysm development.
• This model offers a foundation for more sophisticated simulations of aneurysm growth influenced by cellular mechanical stimuli.