Photoplethysmographic assessment of arterial stiffness and endothelial function

Abstract

Arterial stiffness (AS) and endothelial function (EF) are two features of the arterial system essential for assessing its function. Routine measurements of AS and EF are powerful tools aiding the diagnosis and prognosis of cardiovascular disease. Photoplethysmography (PPG) lends itself well to the assessment of AS and EF due to its low-cost and ease of use. In this chapter, the structure of elastic arteries and its relationship to AS are briefly introduced followed by an outline of the clinical significance of changes in AS. PPG-based measurement of AS, including regional pulse wave velocity measurement and pulse wave analysis methods are presented. Following this, the anatomy and function of the endothelium are described together with an account of endothelial dysfunction and its clinical importance. The principles of flow-mediated dilatation as a means of measuring endothelial health are summarized and the application of PPG to its measurement is outlined. Finally, a review of the measurement of EF by PPG-based flow mediated vasodilatation and its related signal processing is presented and representative studies are described and discussed.