Evaluating patient-specific abdominal aortic aneurysm wall stress based on flow-induced loading.

Area of Science:

• Biomedical Engineering
• Computational Mechanics
• Cardiovascular Research

Background:

• Aneurysms pose significant rupture risks, necessitating accurate stress analysis.
• Previous models often assumed uniform pressure loading, potentially underestimating critical stress points.

Purpose of the Study:

• To develop and validate a patient-specific finite element analysis (FEA) procedure for physiologic wall stress assessment.
• To incorporate experimentally measured, non-uniform pressure loading into aneurysm simulations.

Main Methods:

• Patient-specific lumen casts were used to measure non-uniform pressure distribution under steady flow.
• A nonlinear hyperelastic constitutive model, based on published aneurysmal tissue data, described arterial wall mechanics.
• Finite element simulations incorporated measured pressure data and tissue properties.

Main Results:

• A complex, non-uniform wall stress distribution was identified.
• A localized maximum principal stress of 660 kPa was found on the posterior inner aneurysm surface.
• This localized stress is significantly higher than previously reported under uniform loading assumptions.

Conclusions:

• The posterior wall, a common rupture site, experiences substantial stress concentrations.
• The calculated maximum stress is comparable to reported aneurysmal tensile strength, highlighting potential rupture risk.
• This FEA approach provides a more realistic assessment of aneurysm wall stress and rupture potential.