Characterization of the Valsalva maneuver using wavelet transform

A method to characterize the Valsalva maneuver using the wavelet transform is presented. Frequency domain analysis of heart rate variability is an important tool to assess the cardiovascular system, which is partially controlled by the autonomic nervous system. Fluctuations in heart rate at low frequencies (<0.15 Hz) are mediated both by the sympathetic and parasympathetic nervous systems whereas higher frequency fluctuations (>0.15 Hz) are mediated predominantly by the parasympathetic nervous system. The Valsalva maneuver activates both branches of the autonomic nervous system. A heart rate time series was calculated from the ECG and then analysed using Daubechies 4 Wavelet transform, calculating the followings bands: 0.034-0.067 Hz, 0.067-0.125 Hz, 0.125-0.25 Hz and 0.25-0.5 Hz. The results support the established physiological knowledge of the Valsalva maneuver. The proposed method using the wavelet transform technique may provide additional information on the mechanisms involved in the Valsalva maneuver.