Comparative effects of bipolar single site and bipolar linear triple site pacing on atrial activation - Studies in canine models

In anisotropic tissue (e.g., right atrium), nonuniform conduction may cause conduction block/delay, or form a functional line of block, thus, providing a substrate for the initiation/maintenance of atrial arrhythmias. We tested the hypothesis that the activation patterns generated by bipolar, linear, triple site stimulation create more uniform propagation compared to single site stimulation, thereby, minimizing or eliminating potential substrates for initiation/maintenance of reentrant atrial arrhythmias. The canine sterile pericarditis model and normal dogs were studied. A plunge wire electrode pair was placed at the superior aspect of the crista terminalis (CT) for single site pacing. For triple site pacing, three bipolar pairs were placed perpendicular and parallel to the superior aspect of the CT in a linear fashion. Rapid pacing using different electrode configurations was performed at 200ms and 300ms cycle lengths up to 6 sec. During pacing, 404 unipolar atrial electrograms were recorded simultaneously from electrode arrays placed on the atria. The data demonstrate that linear triple site pacing creates more uniform linear propagation with less or no conduction delay/block, in contrast to single site pacing which creates elliptical impulse propagation. These findings may help develop alternative pacing techniques for termination and/or prevention of atrial arrhythmias.