Digital Photoplethysmography for Assessment of Arterial Stiffness: Repeatability and Comparison with Applanation Tonometry

Abstract

IntroductionArterial stiffness is an independent risk factor for cardiovascular morbidity and can be assessed by applanation tonometry by measuring pulse wave velocity (PWV) and augmentation index (AIX) by pressure pulse wave analysis (PWA). As an inexpensive and operator independent alternative, photoelectric plethysmography (PPG) has been introduced with analysis of the digital volume pulse wave (DPA) and its second derivatives of wave reflections.ObjectiveThe objective was to investigate the repeatability of arterial stiffness parameters measured by digital pulse wave analysis (DPA) and the associations to applanation tonometry parameters.Methods and Results112 pregnant and non-pregnant individuals of different ages and genders were examined with SphygmoCor arterial wall tonometry and Meridian DPA finger photoplethysmography. Coefficients of repeatability, Bland-Altman plots, intraclass correlation coefficients and correlations to heart rate (HR) and body height were calculated for DPA variables, and the DPA variables were compared to tonometry variables left ventricular ejection time (LVET), PWV and AIX. No DPA variable showed any systematic measurement error or excellent repeatability, but dicrotic index (DI), dicrotic dilatation index (DDI), cardiac ejection elasticity index (EEI), aging index (AI) and second derivatives of the crude pulse wave curve, b/a and e/a, showed good repeatability. Overall, the correlations to AIX were better than to PWV, with correlations coefficients >0.70 for EEI, AI and b/a. Considering the level of repeatability and the correlations to tonometry, the overall best DPA parameters were EEI, AI and b/a. The two pansystolic time parameters, ejection time compensated (ETc) by DPA and LVET by tonometry, showed a significant but weak correlation.ConclusionFor estimation of the LV function, ETc, EEI and b/a are suitable, for large artery stiffness EEI, and for small arteries DI and DDI. The only global parameter, AI, showed a high repeatability and the overall best correlations with AIX and PWV.

The Assessment of Finger Photoplethysmography Fitness Index (PPGF) among Young Men with Cardiovascular Disease Risk Factors: A Cross Sectional Study

“…However, this correlation became insignificant after adjustment for the age and MAP (r=0.16). A study by von Wowern et al (2015) found that b/a ratio was correlated significantly with PWV (r=0.56). Compared to above studies, PPGF correlation with PWV was weak (r=-0.27) which suggest that PWV may not be the only marker that influence PPGF.…”

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“…An index of arterial stiffness (SI) defined as h/Δt, where h is the height of the experimental subject, is considered a simple index to measure arterial stiffness. [33] Furthermore, the ratio d/b reflects arterial stiffness and decreases with age, that is, the d peak moves downward (Figure 5b-d ii), and ratio d/b becomes more negative with aging ( Figure 5g). In addition, AI could reflect the vascular age, that is, arterial stiffness.…”

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“…The Meridian™ DPA apparatus automatically generates HR and 16 different pulse wave indices of arterial function based on the PPG waveform contour and its second derivative (acceleration PPG, called APG), and can to some extent separate arterial stiffness in central and peripheral vessels (10). The physiological background of PPG contour analysis has previously been described by Millasseau et al (24), and we have described the physiological and mathematical background of DPA variables and validated the Meridian™ DPA indices (11). Based on our previous findings of repeatability and correlation to applanation tonometry variables (11), we chose to restrict the analysis to five DPA indices: cardiac ejection elasticity index (EEI) and b/a for stiffness in central arteries and left ventricular capacity, dicrotic index (DI) and d/a for peripheral arteries, and aging index (AI) for systemic arterial stiffness.…”

“…The physiological background of PPG contour analysis has previously been described by Millasseau et al (24), and we have described the physiological and mathematical background of DPA variables and validated the Meridian™ DPA indices (11). Based on our previous findings of repeatability and correlation to applanation tonometry variables (11), we chose to restrict the analysis to five DPA indices: cardiac ejection elasticity index (EEI) and b/a for stiffness in central arteries and left ventricular capacity, dicrotic index (DI) and d/a for peripheral arteries, and aging index (AI) for systemic arterial stiffness. A physiological interpretation of the DPA variables is presented in Table 1.…”

“…DPA variables have shown good correlations to age and cardiovascular pathology and morbidity (9,10). We have previously reported robust repeatability of DPA variables, as well as correlations to the tonometry variables PWV and AIx (11).…”