The use of digital filters as the Wavelet Transform is widely recognized in signal processing; however, for the analysis of an electroencephalographic (EEG) signal, the most optimal filter to be used has not been definitively determined. This work presents a comparison between the results obtained by filtering an EEG signal recorded during an 8 minute foreign language class on 69 asymptomatic volunteers using Wavelet Symlets (sym2 - sym10) and Daubechies (db2 - db10). The EEG signals were divided into four sub-bands and an energy, frequency and time analysis was performed. The results obtained show that the filters respond in a different but not significant way. For the identification of the appropriate mother Wavelet for each scope of analysis, its similarity was considered with the average value of Symlets (sym2 - sym10) and this process was replicated for db Wavelets. Considering the energy of the EEG signals, the db4 filter had a higher presence in 5 electrodes in the Alpha and Delta frequency bands. In the frequency domain, the db5 family has a presence in 12 electrodes in the Beta, Alpha and Delta frequency bands. Regarding time, the sym9 filter has a higher presence in 4 electrodes in the Beta, Theta and Delta frequency bands. The purpose of this work is to provide more information for the proper choice of a mother Wavelet in the EEG signal analysis in asymptomatic volunteers.

Changes induced by intrauterine growth restriction (IUGR) in cardiovascular anatomy and function that persist throughout life have been associated with a higher predisposition to heart disease in adulthood. Together with cardiac morphological remodelling, evaluated through the ventricular sphericity index, alterations in cardiac electrical function have been reported by characterization of the depolarization and repolarization loops, and their angular relationship, measured from the vectorcardiogram. The underlying relationship between the morphological remodelling and the angular variation of QRS and T-wave dominant vectors, if any, has not been explored. The aim of this study was to evaluate this relationship using computational models based on realistic heart and torso in which IUGR-induced morphological changes were incorporated by reducing the ventricular sphericity index. Specifically, we departed from a control model and we built eight different globular heart models by reducing the base-to-apex length and enlarging the basal ventricular diameter. We computed QRS and T-wave dominant vectors and angles from simulated pseudo-electrocardiograms and we compared them with clinical measurements. Results for the QRS to T angles follow a change trend congruent with that reported in clinical data, supporting the hypothesis that the IUGR-induced morphological remodelling could contribute to explain the observed angle changes in IUGR patients. By additionally varying the position of the ventricles with respect to the torso and the electrodes, we found that electrode displacement can impact the quantified angles and should be considered when interpreting the results.