Intracardiac electrograms and sensing test signals: electrophysiological, physical, and technical considerations

Until now, the characterization of intracardiac electrograms was carried out mainly in the frequency domain by which filtering and sensitivity testing was decidingly influenced. The typical structure of the intracardiac electrogram derived with unipolar electrodes that is normally responsible for synchronization can be explained theoretically by assuming two dipoles perpendicular to each other moving along with an excitation wave. An abstraction of this typical structure yields, as a sensitivity test signal, an asymmetric triangle with a 4-ms decay time and a 16-ms rise time. A correlation of different test signals and real heart signals applied to 16 different pacemakers demonstrates that the proposed test signal is superior to all others known so far.