Haemodynamic stress in lateral saccular aneurysms. An experimental study

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Cardiovascular Research

Background:

• Intracranial aneurysms pose significant health risks.
• Understanding intra-aneurysmal hemodynamics is crucial for predicting rupture and thrombosis.
• Previous studies have highlighted the complexity of blood flow within aneurysms.

Purpose of the Study:

• To quantitatively measure flow velocities within aneurysm models.
• To investigate the impact of wall elasticity, pulsatility, and perfusion medium properties on intra-aneurysmal circulation.
• To estimate shear stresses at critical locations within the aneurysm models.

Main Methods:

• Utilized non-invasive laser Doppler velocimetry for quantitative flow velocity measurements.
• Employed standardized lateral glass and silastic aneurysm models.
• Investigated both non-pulsatile and pulsatile perfusion conditions.
• Varied perfusion media to simulate different blood-like properties.

Main Results:

• Inflow originated from the downstream lip, directed towards the fundus center, with backflow along the fundus walls.
• Non-pulsatile flow velocities at the center were 0.4–2% of parent vessel velocity.
• Pulsatile flow velocities at the center ranged from 8–13% of parent vessel velocity.
• Slower velocities were observed with macromolecular, blood-like perfusion media compared to glycerol/water.
• Maximum shear stresses at the downstream lip were comparable to arterial bifurcations.

Conclusions:

• Intra-aneurysmal flow and wall shear stress are directly influenced by perfusion pulsatility (systolic/diastolic pressure difference).
• The tendency for spontaneous thrombosis is linked to the viscoelastic properties of blood, specifically hematocrit.
• These findings provide insights into the factors governing aneurysm progression and thrombosis.