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

Abstract

Background-Calcium channel-dependent tissue has been suggested to be involved in the circuit of verapamil-sensitive atrial tachycardia originating from the atrioventricular (AV) node vicinity (V-AT), but little information exists. Methods and Results-To examine the tachycardia circuit of V-AT, a single extrastimulus was delivered during tachycardia to 10 sites of the intraatrial septum: the earliest atrial activation site; His bundle (HB) site; 3 arbitrarily divided sites on the AV junction extending from the HB site to the coronary sinus ostium (CSOS) (sites S, M, and I); the internal-CSOS, inferior-CSOS, superior-CSOS, posterior-CSOS, and posteroinferior-CSOS in 10 patients with V-AT. The longest coupling interval that reset V-AT and subsequent return cycle were measured. The longest coupling interval at earliest atrial activation site was significantly longer than the longest coupling interval at the HB site, site S, M, and I, internal-CSOS, inferior-CSOS, superior-CSOS, posterior-CSOS, and posteroinferior-CSOS, respectively (PϽ0.001 for HB site and PϽ0.0001 for the remaining 8 sites). The return cycle at earliest atrial activation site did not differ from the tachycardia cycle length, whereas those at the remaining 9 sites were significantly longer than tachycardia cycle length (PϽ0.001). Furthermore, a single extrastimulus delivered from sites inferior to the HB site advanced His potential without resetting V-AT in 7 patients in whom AV block was not observed during tachycardia. Conclusions-Atrial tissue within the Koch's triangle extending from the HB site to posteroinferior-CSOS is not involved in the tachycardia circuit. Verapamil-sensitive atrial tissue close to the AV node but not the AV nodal conducting system forms the tachycardia circuit of V-AT. (Circ Arrhythm Electrophysiol. 2010;3:54-62.)

Slow Potential at the Entrance of the Slow Conduction Zone in the Reentry Circuit of a Verapamil‐Sensitive Atrial Tachycardia Originating From the Atrioventricular Annulus

“…Since this form of AT was sensitive to adenosine and verapamil, a calcium channel–dependent tissue has been suggested to be involved in the reentry circuit 4, 5, 6, 7, 8, 9. Indeed, cells with atrioventricular nodal or transitional‐type action potentials have been shown to be present in the atrioventricular valve 16, 17, 18.…”

“…Atrial and ventricular pacing were performed using a cardiac stimulator (SEC‐4103; Nihon Kohden). AT was diagnosed using the standard criteria 5, 6, 7, 8…”

Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Incorporating a “Superior” Slow Pathway

“…17,18,25,26 Intra-atrial reentry, the circuit of which includes ATP-sensitive perinodal atrial tissue, has been proposed as the mechanism of that arrhythmia. 17,25 The electrophysiological characteristics of this atrial tachycardia, including a long RP, an earliest site of atrial activation near the HB, ATP sensitivity, and a successful ablation site in the perinodal region or NCSV, 17,18,25,26 are strikingly similar to those of the sup-F/S-AVNRT.…”

“…17,18,25,26 Intra-atrial reentry, the circuit of which includes ATP-sensitive perinodal atrial tissue, has been proposed as the mechanism of that arrhythmia. 17,25 The electrophysiological characteristics of this atrial tachycardia, including a long RP, an earliest site of atrial activation near the HB, ATP sensitivity, and a successful ablation site in the perinodal region or NCSV, 17,18,25,26 are strikingly similar to those of the sup-F/S-AVNRT. Moreover, as described earlier, the following key diagnostic criteria of this atrial tachycardia are satisfied in some cases of sup-F/S-AVNRT: a V-A-A-V activation sequence after ventricular induction of the tachycardia as a result of DAR [14][15][16]21 and ventriculoatrial dissociation produced by ventricular overdrive D) and CARTO activation maps of the right atrium and noncoronary aortic cusp during tachycardia (E and F) in the right and left oblique projections, respectively, in patient 2, whose successful ablation was in the right-sided perinodal region.…”

Tachycardia and the AV Nodal Region

“…4 -6 In this issue of the Circulation: Arrhythmia and Electrophysiology, Yamabe et al 7 provide novel insights into the mechanism of this arrhythmia. They analyzed characteristics by placing late-coupled atrial extrastimuli at 9 predetermined locations in the region of the triangle of Koch's and the coronary sinus ostium and concluded that the AV node, His bundle, and atrial tissue within the triangle of Koch's are not involved in the tachycardia circuit.…”