Spatial Resolution of Atrial Pace Mapping as Determined by Unipolar Atrial Pacing at Adjacent Sites

Background The purpose of this study was to examine the spatial resolution of unipolar atrial pace mapping by pacing at adjacent sites within the coronary sinus and the right atrium. Methods and Results Unipolar pacing from each pole of a quadripolar catheter was performed in the coronary sinus (n=29) and in the right atrium (n=10). Pacing from the distal electrode was used to simulate the site of origin of an atrial tachycardia. These P waves were compared with the P waves generated by unipolar pacing from each of the three proximal electrodes. The P waves were analyzed for changes in amplitude, duration, and configuration. Pacing within the coronary sinus resulted in significant changes in amplitude and duration at distances of 17 and 21 mm from the distal pole, respectively. Similarly, pacing in the right atrium resulted in significant changes in amplitude and duration at distances of 17 and 32 mm from the distal pole, respectively. No significant changes in configuration were noted in the coronary sinus in any lead at pacing sites ≤32 mm from the distal pole. Configurational changes were noted in the right atrium at pacing sites 17 mm from the distal pole. Conclusions The spatial resolution of unipolar atrial pace mapping is ≈17 mm. These findings indicate that mapping techniques that depend on the accurate discrimination of P-wave morphology, such as pace mapping or concealed entrainment, are likely to be imprecise when used in the atria.