Distal pulse measurement provides statistical, but not dynamical, features of the central pulse

Heart rate variability is recognized in medicine as an important prognostic factor. It is generally believed that the temporal characteristics of the pulse signal do not depend on the measurement point. Specifically, the distal (on the fingers) arrangement of the photoplethysmographic sensors. Using a high-precision measurement technique, we show that on the way from the heart to distally located measurement points, the value of each individual beat-to-beat time may change. It can happen since each subsequent pulse wave propagates through the vessels with a speed different from the previous one, faster or slower. We show that the magnitude of deviation from the average value seems to be mediated by systemic factors. The most likely physiological mechanisms of the detected effect include both modulations of the properties of passive elasticity of the vascular wall depending on the peak value of systolic blood pressure and neurogenic modulation of the tone of the smooth muscles of the vessels.