Hemodynamic Metrics and Arterial Dysfunction: Insights From a Novel Microfluidic Device.

Area of Science:

• Cardiovascular Science
• Biomedical Engineering
• Fluid Dynamics

Background:

• Hemodynamic metrics, especially wall shear stress (WSS), are crucial for understanding endothelial cell (EC) function and vascular pathologies.
• Arterial diseases like hypertension, atherosclerosis, aneurysms, and thrombosis are influenced by blood flow patterns.

Purpose of the Study:

• To review and categorize 35 hemodynamic metrics for their relevance to specific vascular pathologies.
• To analyze key metrics in disturbed flow conditions using computational fluid dynamics (CFD) and a microfluidic platform.
• To identify limitations in current metrics and propose a unified approach for characterizing complex flow environments.

Main Methods:

• Review and categorization of 35 hemodynamic metrics.
• Simulation of disturbed flow using computational fluid dynamics (CFD).
• Analysis using a novel microfluidic endothelium-on-chip platform.

Main Results:

• Shear rosettes provide a comprehensive description of WSS magnitude and direction.
• Anisotropy ratio (AR) characterizes multidirectional flow but cannot differentiate steady from oscillatory flow.
• Existing metrics like transWSS and DOSI have limitations in quantifying bidirectional WSS in low flow or stagnant regions.

Conclusions:

• A unified metric integrating WSS magnitude and bidirectionality is needed.
• Combining AR with magnitude-sensitive metrics (e.g., TAWSS, TransWSS_min) may overcome current limitations.
• CFD and microfluidic platforms offer a robust framework for studying EC responses to disturbed flow and vascular disease progression.