Abstract 11927: Demonstration of Anatomical Reentrant Tachycardia Circuit in Verapamil-Sensitive Atrial Tachycardia Originating from the Atrioventricular Annulus Using Manifest Entrainment
Background: The mechanism and the tachycardia circuit of the verapamil-sensitive atrial tachycardia originating from the atrioventricular annulus (AVA-AT) have not been well clarified. Objectives: The purpose of this study was to define the mechanism and the anatomical tachycardia circuit of the AVA-AT using transient entrainment technique.
Methods: Sixteen patients with AVA-AT (10 male and 6 female, mean age 63±13 years old) were included. All tachycardia origins were observed along the tricuspid annulus, distant from the AV node. While recording the atrial electrogram at the earliest atrial activation site (EAAS), rapid atrial pacing at a rate 5 beats/minute faster than the AT rate was delivered from multiple sites of the right atrium (RA) during AT to demonstrate the manifest entrainment and define the direction of the proximity of the slow conduction area of reentry circuit. After identification of manifest entrainment and orthodromic capture of the EAAS, radiofrequency energy was delivered starting at a site 2 cm away from the EAAS in the direction of pacing site. Radiofrequency energy application site was then gradually advanced toward EAAS until termination of AT to define the entrance of the slow conduction area. Results: The mean tachycardia cycle length was 420±80 msec. The EAAS was observed in the 4 o’clock position of the tricuspid annulus (TV 4:00) in 5 pts, TV 5:00 in 1 pt, TV 6:00 in 3 pt, TV 7 in 1 pt, TV 8:00 in 2 pts, TV 10:00 in 1 pt, TV 11:00 in 1 pt and TV 12 in 2 pts. The EAAS was orthodromically captured by pacing delivered from one of the high antero-lateral RA (n=7), high septal RA (n=6), low antero-lateral RA (n=2) and coronary sinus ostium (n=1). Radiofrequency energy delivery to the site 9.8±1.9 mm proximal to the EAAS, in the direction to the pacing site from where the manifest entrainment was observed, terminated AT immediately after the onset of delivery (2.6±1.1 sec). The atrial electrogram at the successful ablation site was observed 13.3±5.7 msec later than that at EAAS.Conclusions:The underlying mechanism of the AVA-AT was reentry with the entrance of the slow conduction area, distinct from the EAAS. Radiofrequency energy delivery to the entrance of reentry circuit, identified under the navigation of manifest entrainment, eliminates the AVA-AT.
- © 2012 by American Heart Association, Inc.