Quantifying myocardial organization using coherence analysis during ventricular fibrillation and for defibrillation research: a single reference electrode approach

This study investigated local epicardial electrical organization during ventricular fibrillation (VF), and its relationship with defibrillation outcome. Unipolar electrograms (5 seconds duration) prior to defibrillation shock were recorded from 112 epicardial sites during 168 defibrillation attempts on nine canine subjects. Magnitude-squared coherence (MSC) spectrums were used to calculate normalized coherence values for each of the sites with respect to a reference site chosen ad hoc. The average coherence value at distances 3.5 mm and 26.67 mm from the reference site were found to be 0.69±0.11 and 0.30±0.05 respectively (p<0.01). None of the several local coherence parameters were found to be associated with defibrillation outcome. These preliminary results suggest that the state of local myocardial organization, as quantified by MSC values with respect to a single reference electrode, may not be related to defibrillation outcome.