Wavelet analysis of the timing of individual components of the ECG signal

ECG recordings were obtained from 21 healthy subjects aged between 13 and 65 years, over a range of heart rate extending from 46 to 184 beats/min (bpm). A wavelet transform method, based on the Mexican Hat wavelet was then used to precisely locate the positions of the onset, peak and termination of individual components in the ECG signal. These times were then classified according to the heart rate associated with the cardiac cycle to which the component belonged. Second order equations in the square root of the cardiac cycle time, T_R-R of the form A.√T_R-R+B.T_R-R+C were fitted to the data obtained for each component to characterize its timing variation