Localization of Characteristic Peaks in Cardiac Signal

Cardiovascular system study using Electrocardiogram (ECG) signals have evolved tremendously in the research domain of medical electronics and signal processing community. The extraction of characteristic points of an ECG signal helps in detection of any irregularities if present. This paper attempts to provide the basic understanding of ECG signal, pre-processing and extraction of fiducial points P, Q, R, S, T and their respective amplitude. Continuous Wavelet Transform (CWT) has been used for the localization of R peaks. Finally, other peaks are localized in time plane, using inter-beat interval dependent search windows. The proposed method was tested using ECG signal data obtained from MIT Physionet-ATM database and Signals derived from medical instrumentation lab of M.S. Ramaiah Institute of Technology. The simulation results were quite promising in terms of accurate localization of characteristic peaks, their respective amplitude in time plane and other features like R-R intervals, QRS width, S-T segment length, etc. The simplified procedure proposed in this study shows clear indication for arrhythmias detection which can be extended for automated ECG signal classification by appropriate selection of pattern classifiers.