Development of a Platform for In Vitro Hemodynamic Measurements in Varying Gravity Profiles.

Area of Science:

• Biomedical Engineering
• Fluid Dynamics
• Aerospace Medicine

Background:

• Cerebrovascular flow under altered gravity is crucial for mitigating flight-related G-force effects.
• In vivo studies have limitations in detailed vascular flow mapping during gravitational changes.
• This work addresses the need for high-resolution analysis of cerebral hypoperfusion mechanisms.

Purpose of the Study:

• To present a novel in vitro carotid bifurcation model for studying cerebrovascular hemodynamics.
• To analyze flow behavior across static and transient gravity profiles and orientations.
• To investigate mechanisms driving cerebral hypoperfusion under varying G-forces.

Main Methods:

• Utilized a patient-derived polydimethylsiloxane carotid model with a blood analog.
• Employed particle image velocimetry and high-speed imaging during parabolic flights (0 Gz, +1 Gz, +2 Gz).
• Analyzed velocity, vorticity, wall shear stress, and recirculation dynamics in supine and vertical orientations.

Main Results:

• Flow separation points shifted upstream with increasing Gz, particularly in vertical orientations.
• Recirculation height significantly increased with higher Gz and vertical orientation.
• Peak wall shear stress elevated with Gz and orientation changes, while vorticity decreased.

Conclusions:

• The in vitro platform enables advanced cerebrovascular hemodynamics research under varying gravity.
• Facilitates controlled study of flow phenomena and orientation effects.
• Provides a tool for validating computational models of cerebral blood flow.