A completely automated activation-repolarization interval algorithm for directly coupled unipolar electrograms and its three-dimensional correlation with refractory periods

Sintered AgAgCl needle electrodes were used to record unipolar directly coupled (DC) electrograms transmurally from right and left ventricular myocardium. Direct coupling yields unfiltered low-frequency signal content, preserving repolarization waveform morphology. These electrograms were analyzed using completely automated computer algorithms for the timing of local activation and local repolarization that permit beat-to-beat determinations of these parameters. The local activation to repolarization interval was compared with the refractory period obtained with the extrastimulus technique from the same electrode during varied basic cycle lengths and pacing sequences. Pooling of the activation to refractory period versus activation-to-repolarization data from all sites and pacing sequences produced a correlation coefficient of 0.96, with a standard error of the estimate of 5.1 msec. The results demonstrate that DC-coupled unipolar electrograms may prove useful in direct, three-dimensional local repolarization timing and in simultaneous assessment of the temporal and spatial dispersion of changes in repolarization from multiple sites.