ECG Signal Analysis: Past, Present and Future

Cardiovascular activity is a complicated process and the abnormality is directly represented in the ECG rhythm, heart rate, blood pressure and respiration signal. The Electrocardiogram (ECG) is an important tool for diagnosing the health status of the patient. It represents cardiac electrical activity of the patient. Analysis of this cardiac electrical signal is very challenging due to the involvement of various types of noise such as baseline wander noise, differences in the electrode impedances, power line interference, muscle artifact and the current flowing in the signal acquisition arrangement. For analyzing such cardiac electrical signal, it requires Computer aided diagnosis (CAD). Time domain techniques are suitable in the analysis of the clean ECG signal. Frequency domain techniques suffers due to spectral leakage. Hence, not suitable for analyzing nonlinear dynamics of the ECG signal. Nonlinear methods are used for analyzing such nonlinear and nonstationary features of the ECG signals. In this paper, different methods from time, frequency and nonlinear domains have been discussed.