Spectrotemporal analysis of ventricular late potentials.

The authors introduce a new technique for the analysis of ventricular late potentials: spectrotemporal mapping. Spectrotemporal mapping displays a signal in both the time and frequency domains simultaneously, overcoming some of the limitations of single domain analysis. Spectrotemporal analysis of late potentials was developed from a critique of classical spectral analysis methods. Several examples of spectrotemporal analysis of signal-averaged ECG waveforms are presented. These include cases in which spectrotemporal mapping was able to represent late potentials that were not seen after conventional time-domain processing. Spectrotemporal mapping reveals that ventricular late potentials have a time-varying energy spectrum, which theoretically would preclude the use of classical Fourier analysis techniques. Both the vector magnitude and Fourier transformations are a reduced representation of the information available in the signal average. Spectrotemporal mapping combines time and frequency information in a way that is compatible with the basic statistical structure of late potentials.