Figure 1.

Example of data available for the analysis of ECG signals. (a) ECG waveforms (P, QRS and T waves) and standard features extracted from an ECG beat. The RR interval is measured as the peak-to-peak interval between two consecutive QRS complexes, the PR interval is defined as the duration from the beginning of the P wave to the beginning of the QRS complex, the QRS duration (or width) is the duration between the start and the end of the QRS complex, the QRS amplitude is defined as the absolute value of the difference between the minimum and the maximum of the QRS complex, and the QT interval is measured as the time between the beginning of the Q wave and the end of the T wave. (b) Examples of different ECG waveforms: normal ECG [50], ventricular ectopic beats [51], supraventricular ectopic beats [52] and second degree heart block arrhythmia [53]. (Online version in colour.)