Electrophysiological Delineation of the Tachycardia Circuit in Atrioventricular Nodal Reentrant Tachycardia

Abstract

Background-The exact boundaries of the reentry circuit in atrioventricular nodal reentrant tachycardia (AVNRT) have not been convincingly defined. Methods and Results-To define the tachycardia circuit, single extrastimuli were delivered during AVNRT to 8 sites of the right intra-atrial septum: 3 arbitrarily divided sites of the AV junction extending from the His bundle (HB) site to the coronary sinus ostium (CSOS) (sites S, M, and I) and the superior (S-CSOS), inferior (I-CSOS), posterior (P-CSOS), and posteroinferior (PI-CSOS) portions of the CSOS and the CSOS in 18 patients. The mean tachycardia cycle length (TCL) was 368Ϯ52 ms. Retrograde earliest atrial activation was observed at the HB site in all patients. The longest coupling intervals of single extrastimuli that reset AVNRT at sites S, M, I, I-CSOS, CSOS, S-CSOS, P-CSOS, and PI-CSOS were 356Ϯ51, 356Ϯ51, 355Ϯ52, 357Ϯ51, 318Ϯ47, 305Ϯ53, 311Ϯ56, and 312Ϯ56 ms, respectively, and the following return cycles at these sites were 368Ϯ52, 368Ϯ53, 367Ϯ53, 367Ϯ53, 407Ϯ66, 431Ϯ73, 415Ϯ55, and 412Ϯ56 ms, respectively. The longest coupling intervals at sites S, M, I, and I-CSOS did not differ from each other and were longer than those at CSOS and S-, P-, and PI-CSOS (PϽ0.0001). The return cycles at sites S, M, I, and I-CSOS did not differ from the TCL, whereas those at CSOS and S-, P-, and PI-CSOS were longer than the TCL (PϽ0.0001). Conclusions-The perinodal atrium extending from the HB site to I-CSOS was involved in the tachycardia circuit. I-CSOS was thought to be the entrance of the slow pathway. (Circulation. 1999;100:621-627.)

Analysis of the Anatomical Tachycardia Circuit in Verapamil-Sensitive Atrial Tachycardia Originating From the Vicinity of the Atrioventricular Node

“…A single extrastimulus was delivered beginning with the tachycardia cycle length and decreased by 10 ms until tachycardia was reset. 11 Resetting was defined by the presence of a noncompensatory pause after the extrastimulus was delivered. 12 The longest coupling interval of the single extrastimulus that reset the tachycardia and the following return cycle were measured at each site.…”

Demonstration of the Exact Anatomic Tachycardia Circuit in the Fast-Slow Form of Atrioventricular Nodal Reentrant Tachycardia

“…1 Recent evidence suggests that the reentry circuit in AVNRT involves the perinodal atrium. [2][3][4] Little is known, however, about the exact boundaries of the reentry circuit in the fast-slow (FS) form of AVNRT. The purpose of the present study was to define the tachycardia circuit in FS-AVNRT.…”

Cardiac Conduction System in Congenitally Corrected Transposition of the Great Arteries and Its Clinical Relevance

“…If other mechanisms of supraventricular tachycardia have been excluded using pacing maneuvers, and the earliest activation appears on the septum in the conventional position for the fast pathway (behind the Tendon of Todaro), then empiric, anatomically guided slow pathway ablation should be undertaken. In the situation of twin AV nodes the culprit AV node will need to be defined using resetting or subthreshold stimulation so as to identify the adjacent slow pathway to be targeted40, 41 and robust anterograde conduction via the other AV node confirmed with pacing outside of tachycardia. More commonly, anterograde conduction proceeds via the anterior AV node, and the safest empiric approach will involve ablation in the right posteroseptum in the standard location, observing closely for junctional beats and monitoring AV conduction.…”