ONLINE BEAT-TO-BEAT MONITORING OF SPECTRAL PARAMETERS OF HEART-RATE-VARIABILITY SIGNAL USING A POLE-TRACKING ALGORITHM

Spectral parameters extracted from the heart rate variability (HRV) si gnal are obtained on a beat-to-beat basis, following a procedure which uses two recursive algorithms. In the first step of the procedure the set of the AR model coefficients is updated each time a new RR value is available. Then from the estimated AR model parameters, the new pos ition of the poles of the model transfer function in the complex z-pla ne is evaluated and, finally, through a residual calculation, it is po ssible to calculate the spectral parameters which quantify the control of the autonomic nervous system in assessing the cardiac frequency (i .e., power and frequency of LF and HF components). The whole procedure has first been tested on a simulated time series, in order to evaluat e its performance in tracking the dynamic changes during different con ditions; next the algorithms were employed in the study of the HRV sig nal for continuous monitoring of non-stationary conditions.