The Examination of Arterial Function and Mechanotransduction Through Brachial Arteries via Flow-Mediated Dilation.

Cardiovascular disease remains one of the leading causes of mortality worldwide, with endothelial dysfunction playing a pivotal role in its initiation and progression. Early detection and accurate evaluation of endothelial dysfunction are therefore essential for effective risk assessment and intervention. This chapter reviews recent developments in a widely used method, flow-mediated dilation (FMD), for assessing endothelial function in clinical research. We begin with an overview of vascular structure and endothelial physiology, laying the groundwork for a deeper exploration of the mechanotransduction processes at the cellular level that drive vasodilation during FMD. Next, we describe the FMD procedure in detail, which evaluates arterial functions by measuring ultrasound-based arterial vasodilation in response to a period of temporary ischemia. We then discuss the limitations of using FMD%, the traditional marker representing the percentage of vasodilation, as the sole output of the FMD test. Although widely used, FMD% fails to capture the full mechanotransduction process linking shear stress to arterial dilation, leading to potentially incomplete or biased interpretations. To overcome this limitation, we introduce a novel physics-based framework for interpreting FMD results. This approach utilizes a set of biophysical models to extract physiologically meaningful parameters by integrating theoretical insights with experimental FMD measurements. Finally, we outline the significant potential of this advanced FMD analysis tool, which may enable a more comprehensive and mechanistically informed assessment of endothelial function.