Analysis of heart rate variability by Pisarenko harmonic decomposition

The Pisarenko harmonic decomposition method for retrieving harmonies from a covariance function was used to analyse the heart rate variability signal. The study was conducted in order to evaluate the autonomic response to the hemodialysis treatment in two groups of hemodynamically-stable and unstable patients, comparing the frequency of the main oscillation embedded in the heart rate variability signals. The two groups resulted clearly separated by the value of this frequency: stable patients exhibited a frequency ranging in the LF band, whereas the unstable had a frequency lying in the HF band. This result is in accordance with those of the autoregressive spectral analysis, indicating a reduced sympathetic activation in hypotension-prone patients