Using Wigner Distribution's cross terms to detect patterns of Ventricular Late Potentials

Ventricular Late Potentials (VLP) are very small electrocardiographic signals that are attenuated, fragmented and delayed, when the depolarization wave reaches some tissue damaged by some myocardial infarction. The detection of the VLP is complicated mainly because their amplitudes are very similar to the electrocardiographic noise levels and their spectral components are overlapping by both the spectral band wide of the noise and the spectral band wide of the ECG signal. Normally these tiny structures appear at the end of the QRS complex. Time domain analysis is the most popular method for VLP detection; nevertheless this produces low predictive values. In this paper we are proposing to use the Wigner Distribution Interference Terms (ITs) or cross terms (CTs) to improve the VLP detection. We have noted that, studying the geometry and quadratic behavior of the CTs, it is possible to identify VLP on the time frequency plane.