Method for Antegrade/Retrograde Conduction Discrimination Using A Standard Atrial Bipolar Lead

Significant differences between morphology, magnitude, and relative timing of antegrade and retrograde conduction were demonstrated on unipolar electrograms from a standard atrial bipolar J lead positioned in the right atrium in dogs. The morphology of the P wave sensed from the tip was more or less biphasic while the morphology of the P wave sensed from the ring was monophasic only and of lower frequency content. The unipolar-ring P wave was attenuated in retrograde as compared with the antegrade. During retrograde conduction the unipolar-ring signal returned to baseline earlier in time relative to the peak of the unipolar-tip signal, than it did during antegrade conduction. Based on these differences a sensing circuit capable of discriminating between antegrade and retrograde conduction was built. This discriminator circuit, which relies on a standard lead and simple electronics, functioned reliably in trials in dogs and thus may prove to be practical for use in future pacemakers.