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

Abstract

Hemodynamic metrics provide critical insights into the interplay between flow physics and endothelial cell (EC) function in arterial pathologies. Among these, wall shear stress (WSS) is a central regulator of EC function and a key determinant of vascular disease progression. In this study, we review 35 hemodynamic metrics and assess their association with hypertension and atherosclerosis, aneurysms, and thrombosis. Metrics are categorized by magnitude, direction, energy, stagnation time and flow rate to identify those most relevant to specific pathological conditions. We simulate disturbed flow in a novel microfluidic endothelium-on-chip platform using computational fluid dynamics (CFD) and analyze 16 key hemodynamic metrics. The most comprehensive description of the complex flow environments is provided by shear rosettes, polar plots of WSS magnitude and direction over the cardiac cycle. The anisotropy ratio (AR) metric, derived from the shear rosette, offers a robust characterization of the multidirectional secondary flow but cannot distinguish steady from unidirectional oscillatory flows. The R-Ratio and minimized transverse WSS (TransWSSmin) metrics effectively quantify bidirectional WSS when computed along principal flow directions. In contrast, transWSS and directional OSI (DOSI) are limited in their ability to quantify bidirectional WSS in regions of low mean WSS or stagnation. A unified metric integrating WSS magnitude and flow bidirectionality is currently lacking. Combining AR with magnitude-sensitive metrics, such as TAWSS, TransWSS_min, or |TAWSS_SC|, may address these limitations. Together, CFD and microfluidic platforms provide a powerful framework to assess EC responses to disturbed flows and advance understanding of vascular disease progression.