Spatial filtering of unipolar electrograms

In order to be able to derive some quantitative criteria to assist in making decisions about the presence of local activations, zones of canine myocardium incapable of undergoing electrical activation (EA) were created. The criteria are based on the comparison of electrograms recorded in those inexcitable zones with electrograms recorded in normal myocardium. Two criteria for making decisions about local EA in unipolar electrograms are compared. The first is based on the first time derivative (time filtering) of the electrogram and the second is based on th first spatial derivative (spatial filtering) between two electrograms recorded in neighboring electrodes. It is shown that the spatial derivative performs much better than the time derivative in both supraventricular rhythm and ventricular fibrillation