King's College London

Research portal

Indices to assess aortic stiffness from the finger photoplethysmogram: in silico and in vivo testing

Research output: Contribution to journalPoster abstract

Original languageEnglish
Article numberP164
Pages (from-to)128
JournalArtery Research
Published4 Dec 2018
EventARTERY18 - Guimaraes, Portugal
Duration: 18 Oct 201820 Oct 2018

King's Authors


Aortic stiffness is predictive of cardiovascular morbidity and mortality. However, the gold standard method for assessing aortic stiffness, carotid-femoral pulse wave velocity, is time-consuming and requires a trained operator. An alternative approach could be to derive an arterial stiffness index (ASI) from the easily measured finger photoplethysmogram (PPG). Our aim was to investigate the performance of PPG-derived ASIs for assessing aortic stiffness.

An in silico dataset of arterial pulse waves (PWs) was generated using a model of pulse wave propagation (1). PWs were generated for virtual healthy subjects aged 25 to 75. Several simulations were run for each age decade to mimic population-level variation in cardiac and vascular properties. PPG PWs were simulated from blood pressure PWs (2). The dataset was used to design an algorithm to calculate over 30 ASIs described in the literature from the finger PPG. In vivo testing was performed using 6,506 subjects from the Airwave dataset (3) who had triplicate PPG and reference PWV measurements.

In silico and in vivo performances of ASIs, including the stiffness index (SI) and reflection index, varied greatly. The SI performed well in vivo, showing strong correlation with reference PWVs. However, in silico assessment demonstrated that the SI and other ASIs were affected by other cardiac and vascular properties as well as aortic stiffness.

This study identified the best-performing ASIs in both in silico and in vivo datasets. In the future multiple ASIs should be combined to improve performance, since different ASIs have different physiological determinants.


(1) Willemet MC, Chowienczyk PJ, Alastruey J. A database of virtual healthy subjects
to assess the accuracy of foot-to-foot pulse wave velocities for estimation of aortic stiffness. American Journal of Physiology-Heart and Circulatory Physiology. 2015; 309(4): H663–H675.

(2) Charlton PH, Celka P, Farukh B, Chowienczyk PJ, Alastruey J. Assessing Mental Stress from the Photoplethysmogram: A Numerical Study. Physiological Measurement. 2018; 39(5): 054001.

(3) Elliott P, Vergnaud A, Singh D, Neasham D, Spear J, Heard A. The Airwave Health Monitoring Study of police officers and staff in Great Britain: Rationale, design and methods. Environmental Research. 2014; 134: 280-285

View graph of relations

© 2018 King's College London | Strand | London WC2R 2LS | England | United Kingdom | Tel +44 (0)20 7836 5454