Use of coherence in activation detection during ventricular fibrillation

The use of cardiac activation mapping to study ventricular fibrillation (VF) is discussed. The locations of isochrones in maps are based on decisions on whether and when segments of the electrogram have local electrical activation. The authors compare two quantitative criteria for making decisions about local activity in electrograms. The criteria are based on the comparison of electrograms recorded in those excitable zones with electrograms recorded in normal myocardium. One uses the first derivative of the electrogram (only one electrogram affects the decision); the second uses the first derivative of the primarily local component of the waveform