Ablation of atrial tachycardia originating from the vicinity of the atrioventricular node: Significance of mapping both sides of the interatrial septum

Objectives The purpose of the study was to examine the value of right- and left-sided mapping to identify the site of tachycardia origin. Background Focal atrial tachycardia may originate from die vicinity of the atrioventricular node from either side of the interatrial septum. Methods In 16 patients undergoing radiofrequency catheter ablation of perin odal atrial tachycardia, activation mapping of the right and left side of d ie interatrial septum was performed. Results Atrial tachycardia originated from the right side of the interatria l septum in 10 patients (group A) and from the left side in 6 patients (gro up B). On the right side, earliest atrial activity preceded the onset of di e P-wave by 49 +/- 15 ms in group A and by 38 +/-8 ms in group B (NS), and it preceded the signal recorded from the right atrial appendage by 59 +/- 1 9 ms in group A and by 60 +/- 13 ms in group B (NS). On the left side, earl iest activity preceded the onset of the P-wave by 27 +/- 16 ms in group A a nd by 51 +/-6 ms in group B (<0.01), and it preceded the signal obtained fr om the right atrial appendage by 38<plus/minus>19 ms in group A and by 73 /-9 ms in group B (<0.01). Atrial tachycardias were successfully eliminated in all patients without impairment of atrioventricular conduction. During follow-up, two patients had a recurrence of tachycardia. Conclusions Mapping of only the right side cannot exclude a left-sided orig in. Therefore, mapping of both sides of the interatrial septum is required prior to ablation of focal atrial tachycardia originating from the vicinity of the atrioventricular node. (J Am Coll Cardiol 2001;38: 394-400) (C) 200 1 by the American College of Cardiology.