P18 Vascular Aging Index of the Finger Photoplethysmogram: A Validation Study with Vascular Stiffness, Mental Stress, and Day-to-Day Variability

Abstract

Background: Daily assessment of vascular health may predict cardiovascular incidence. Vascular aging index (VAI) calculated from second derivative of photoplethysmogram (SDPTG) is a simple, non-invasive measure possibly reflecting vascular stiffness. However, the effects of daily life events such as mental stress and day-to-day variability as well as its relation to other indices of vascular stiffness remain unclear. Purpose: To determine whether VAI measured by finger SDPTG is 1) correlated with peripheral augmentation index (pAI), 2) altered by acute mental stress, and 3) affected by day-to-day variability. Methods: Simultaneous measurements of finger photoplethysmogram and radial artery tonometry were performed in 68 healthy subjects (age = 22–64 years) of whom 31 subjects were further tested during a 30-second mental arithmetic and 10 subjects underwent day-to-day variability assessment for 5 consecutive days. VAI was calculated from a 20-second segment of photoplethysmogram data [1]. Results: At rest, VAI was positively correlated with pAI (r = 0.62, p < 0.001). During mental arithmetic, VAI increased when compared with the control condition (p = 0.032) whereas pAI did not show significant change. Five day measurements of VAI demonstrated the overall coefficient of variation of 21.1 ± 13.7% across all subjects. Conclusion: VAI calculated from the finger SDPTG is related to a measure of vascular stiffness and sensitive to mental stress with fair day-to-day variability. These findings suggest that VAI assessment needs to be performed at the quiet resting condition.