Hemodynamic transition driven by stent porosity in sidewall aneurysms

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Medical Devices

Background:

• Intracranial aneurysms (IAs) healing after flow diverter stent (FDS) treatment depends on hemodynamic changes and endothelialization.
• Two distinct hemodynamic regimes exist in sidewall IA models, influenced by stent porosity and potentially linked to thrombosis.
• Understanding the transition between these regimes is crucial for optimizing IA treatment outcomes.

Purpose of the Study:

• To investigate the physical nature of the hemodynamic transition in intracranial aneurysms treated with flow diverter stents.
• To correlate flow patterns and hemodynamic forces with stent porosity and IA healing.
• To validate computational fluid dynamics (CFD) simulations with experimental measurements.

Main Methods:

• Combined computational fluid dynamics (CFD) simulations and multi-time lag particle imaging velocimetry (PIV) measurements.
• Assessed velocity, shear stress, and pressure fields within the aneurysm sac and parent artery for various stent porosities.
• Analyzed flow characteristics corresponding to shear and pressure-driven regimes.

Main Results:

• Two primary hemodynamic regimes were identified and confirmed via PIV and CFD, characterized by distinct flow patterns.
• Averaged IA velocities correlated with shear stress at the IA neck and pressure gradients in the parent artery.
• Stent porosity was found to control the transition: decreased porosity increased pressure differential and decreased shear stress across the IA neck.

Conclusions:

• The study elucidates the hemodynamic transition in stented intracranial aneurysms, driven by stent porosity.
• Flow diverter stent porosity is a key factor in modulating IA hemodynamics, influencing thrombosis and healing.
• CFD and PIV provide valuable insights, with good agreement observed, though transitional regimes require careful interpretation.