Frequency domain analysis of endocardial signals.

Frequency domain analysis, applied to atrial endocardial electrograms during atrial fibrillation, has been used to develop automated arrhythmia detection schemes for implantable devices and to investigate electrophysiologic mechanisms. Such analysis may be used to quantify both temporal and spatial organization during atrial fibrillation. Specifically, autopower spectra and coherence spectra reveal electrogram characteristics that are powerful in discriminating atrial fibrillation from sinus rhythm and regular atrial tachycardias. Furthermore, changes in spectral characteristics with drug administration reveal nonstationarities in spatial organization and in underlying electrophysiologic mechanism. The usefulness of frequency domain analysis in the study of atrial fibrillation is influenced by electrode configuration, the method of spectral estimation and other clinical variables.