HEART RATE VARIABILITY ANALYSIS THROUGH WAVELET DECOMPOSITION

parameters (heart rate and blood pressure) at rest and in response to external stimuli. It is composed of two subsystems: the sympathetic and parasympathetic (or vagal) ones, acting simultaneously but at different rates, the first for increasing and the second one for decreasing the heart rate (HR). To evaluate the activities of the two subsystems spectral analysis of HR variability is traditionally used. Standard methods (Fourier and autoregressive analysis) require stationary signals and do not allow to analyze short and transitory periods. But applying the wavelet analysis, it is possible to make a multi-resolution evaluation (in time and frequency) of the activation of the two subsystems and quantify their variations. Since a validated methodology for spectral analysis of transient periods does not exist, we tested the wavelet approach by analysing the Valsalva manoeuvre in healthy and pathologic patients. The physiology of this cardiovascular test is well known and it represents the good target to evaluate the wavelet approach and its feasibility in quantifying sympathetic and vagal activations. The obtained results demonstrate the goodness of wavelet approach: in healthy subjects the different activations were quantified properly with the right sequence. In pathological patients, our analysis demonstrated the absence of some activations and the results are statistically different from the normal ones.