Assessing hemodynamics from the photoplethysmogram to gain insights into vascular age: a review from VascAgeNet

Abstract

The photoplethysmogram (PPG) signal is widely measured by clinical and consumer devices, and it is emerging as a potential tool for assessing vascular age. The shape and timing of the PPG pulse wave are both influenced by normal vascular ageing, changes in arterial stiffness and blood pressure, and atherosclerosis. This review summarises research into assessing vascular age from the PPG. Three categories of approaches are described: (i) those which use a single PPG signal (based on pulse wave analysis); (ii) those which use multiple PPG signals (such as pulse transit time measurement); and (iii) those which use PPG and other signals (such as pulse arrival time measurement). Evidence is then presented on the performance, repeatability and reproducibility, and clinical utility of PPG-derived parameters of vascular age. Finally, the review outlines key directions for future research to realise the full potential of photoplethysmography for assessing vascular age.

Influences of Intense Physical Effort on the Activity of the Autonomous Nervous System and Stress, as Measured with Photoplethysmography

“…The device that we have used studies variability in the heart rate, which allows for an analysis of the autonomic nervous system, and for an evaluation of physical/mental stress, through its own score, that relates to fatigue and electrocardiac stability. The PPG signal is a valuable source of physiological information, since it is influenced by the cardiovascular system and by the ANS, which can modify its response depending on the degree of stress [ 23 ]. We obtained information related to PRV at two different times, before and after intense physical exercise, in order to observe the changes produced by its action.…”

“…In addition, PRV assessment using PPG can be integrated into other devices for clinical use, in order to increase the quantity and quality of information obtained and provided to patients [ 23 ]. One of these devices is “Max Pulse ® ” that, in addition to providing data regarding autonomic balance and stress, also provides data on vascular health by analyzing the morphology of the pulse wave [ 24 ].…”

Wearable Photoplethysmography for Cardiovascular Monitoring

“…BP has been estimated from the PPG using the following inputs [ 26 ]: a single PPG [ 19 ]; a proximal and a distal PPG to measure PPT [ 21 ], [ 22 ]; or a distal PPG signal and a signal indicating the time of ventricular contraction (e.g., ECG, phonocardiogram) to measure PAT [ 20 ], [ 21 ], [ 150 ]. Techniques that use a single PPG signal are based on analysis of pulse wave shape using either extracted features [ 151 ]–[ 153 ] or the whole pulse wave [ 154 ].…”

“…It has been proposed that the PPG could be used to assess vascular age [ 26 ], [ 32 ]. Several aging indices have been proposed based on features of the second derivative [see Fig.…”

Photoplethysmographic imaging and analysis of pulsatile pressure wave in palmar artery at 10 wavelengths

“…The PPG method continues to draw active attention for its simplicity and unique capacity to determine heartbeat rate, measure waveforms of PPW, and estimate blood pressures in wearable devices. 7,8 Despite these successes, requirement of tissue contact by the PPG method poses considerable risks of pathogen transmission and limits application scenarios like wound monitoring. More importantly, the single-or few-spot nature of PPG method limit its ability to characterize PPW propagation by, e.g., pulse wave velocity (PWV) and spatial distribution for evaluation of arterial stiffness.…”