Identification of left atrial origin of ectopic tachycardia during right atrial mapping: Analysis of double potentials at the posteromedial right atrium

Left Atrial Ectopic Tachycardia. Introduction: The high posteromedial right atrium is adjacent to the left atrium near the right superior pulmonary ve in. We hypothesized that analysis of electrograms at this site could distin guish left from right atrial tachycardia. Methods and Results: Atrial mapping was performed in 16 patients with left atrial origin ectopic tachycardia (11 patients with right superior pulmonar y vein origin and 5 patients with other left atrial tachycardias). During l eft atrial tachycardia, earliest right atrial activation was recorded at th e high posterior right atrium in 14 of 16 patients. At all of these 14 earl y sites, double potentials were recorded during tachycardia, The first pote ntial was a far-field signal from left atrium as indicated by the following : (1) during sinus beats, the timing of the two potentials reversed such th at the left atrial one was late; (2) ablation at the right atrial site did not decrease the amplitude of the first potential, but did decrease the amp litude of the second potential; and (3) the timing of activation at the adj acent left atrium agreed with that of the first potential. In the 11 right superior pulmonary vein tachycardias, the first potential was markedly earl ier than the p wave onset, but in left atrial tachycardias with other origi ns it was later. In a control group of six patients with pacing to simulate right atrial tachycardia, double potentials were recorded in the posterior right atrium, but the timing of components did not reverse during sinus rh ythm. Conclusion: For some left atrial ectopic tachycardias, particularly those o riginating from the right superior pulmonary vein, recognition of left vers us right atrial origin can be accomplished during right atrial mapping by a nalysis of double potentials in the posteromedial right atrium.