Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia Using a Slow Pathway Extending to the Superoanterior Right Atrium

Discrimination of atypical atrioventricular nodal reentrant tachycardia from atrial tachycardia by the V-A-A-V response

INTRODUCTION

The electrophysiological discrimination between fast-slow (F/S-) atrioventricular (AV) nodal reentrant tachycardia (NRT) and atrial tachycardia (AT) originating from the interatrial septum remains challenging. While a V-A-A-V response may occur immediately after ventricular induction or entrainment of either tachycardia, the electrophysiological dissimilarities in that response between the two tachycardias remain unclear. The purpose of this study was to identify a diagnostic indicator discriminating F/S-AVNRT from AT by examining the difference in the V-A-A-V response between the two tachycardias.

METHODS

This retrospective study included 17 patients with F/S-AVNRT [7 with common-form F/S-AVNRT using a typical slow pathway (SP) and 10 with superior type F/S-AVNRT using a superior SP] and 10 patients with reentrant AT. All 27 patients presented with long RP supraventricular tachycardia and an initial V-A-A-V response upon ventricular induction or entrainment. The V-A-A-V response in patients with F/S-AVNRT was due to dual atrial responses. We measured the interval between the first (A1) and second atrial electrogram (A2) of V-A-A-V and calculated ΔAA by subtracting A1-A2 from the tachycardia cycle length.

RESULTS

V-A-A-V responses were observed most often upon ventricular induction of F/S-AVNRT (6±5 times) as well as AT (6±6 times; P = 0.87). The V-A-A-V response upon ventricular entrainment was observed in a single patient with F/S-AVNRT versus 10 all patients with AT (P<0.001). ΔAA ranged between -80 and 228 ms in F/S-AVNRT and between -184 and 26 ms in AT. A ΔAA >26 ms predicted a diagnosis of F/S-AVNRT with a 76% sensitivity and 100% specificity, while a ΔAA ←80 ms predicted a diagnosis of AT with a 50% sensitivity and 100% specificity.

CONCLUSIONS

ΔAA is a useful, confirmatory, diagnostic indicator of F/S-AVNRT versus AT associated with the V-A-A-V response. This article is protected by copyright. All rights reserved.

Local Variation and Age-Related Change in Atrial and Ventricular Myocardial Contiguity at the Atrioventricular Junction in Human Hearts

Background: We explored the histologic patterns of and age-related changes in atrial and ventricular myocardial contiguity at the left and right atrioventricular (AV) junction that could be a target site for catheter ablation.

Methods and Results: Twenty-three structurally normal adult hearts obtained at autopsy were studied. The 2 AV annuli were divided into 13 clinically recognized portions in which we measured distance between the atrial and ventricular myocardium at the AV junction. Overall, measured distance was less on the right than left side (mean [±SD] 0.74±0.59 vs. 1.15±0.78 mm, respectively), and distance increased gradually with age. The gap was smallest at the anterolateral portion on the right side and posterolateral portion on the left side. Three specific features were noted, namely extension of the ventricular myocardium (coarse trabeculae) towards the atrium on the right side of the AV junction, extension of the atrial myocardium onto the AV valve leaflets, and a collection of small myocardial cells, perhaps including specialized cells, in the right anterolateral portion. No concealed AV muscular connections were found.

Conclusions: Contiguity and separation of the myocardium at the AV junction have specific patterns, and myocardial proximity is influenced by age. These histologic features of the AV junction may prove to be informative for catheter ablation of tachyarrhythmias related to the AV junction.

Antegrade slow pathway mapping of typical atrioventricular nodal reentrant tachycardia based on direct slow pathway capture

BACKGROUND

Radiofrequency (RF) ablation of typical atrioventricular nodal reentrant tachycardia (tAVNRT) is performed without revealing out the location of antegrade slow pathway (ASp). In this study, we studied a new electrophysiological method of identifying the site of ASp.

METHODS

This study included 19 patients. Repeated series of very high-output single extrastimulations (VhoSESts) were delivered at the anatomical slow pathway region during tAVNRT. Tachycardia cycle length (TCL), coupling interval (CI), and return cycle (RC) were measured and the prematurity of VhoSESts [ΔPM (= TCL - CI)] and the prolongation of RCs [ΔPL (= RC - TCL)] were calculated. Pacing sites were classified into two categories: (i) ASp capture sites [DSPC(+) sites], where two different RCs were shown, and ASp non-capture sites [DSPC(-) sites], where only one RC was shown. RF ablation was performed at DSPC(+) sites and/or sites with catheter-induced mechanical trauma (CIMT) to ASp.

RESULTS

DSPC(+) sites were shown in 13 patients (68%). RF ablation was successful in all patients without any degree of atrioventricular block nor recurrence. Total number of RF applications was 1.8 ± 1.1. Minimal distance between successful ablation sites and DSPC(+)/CIMT sites and His bundle (HB) electrogram recording sites was 1.9 ± 0.8 mm and 19.8 ± 6.1 mm, respectively. ΔPL of more than 92.5 ms, ΔPL/TCL of more than 0.286, and ΔPL/ΔPM of more than 1.565 could identify ASp with sensitivity of 100%, 91.1%, and 88.9% and specificity of 92.9%, 97.0%, and 97.6%, respectively.

CONCLUSIONS

Sites with ASp capture and CIMT were close to successful ablation sites and could be useful indicators of tAVNRT ablation.

Atypical Slow-Slow Atrioventricular Nodal Reentrant Tachycardia with Use of a Superior Slow Pathway

We report a case of atypical slow-slow atrioventricular nodal reentrant tachycardia (AVNRT) utilizing a superior slow pathway as a retrograde limb. The standard electrophysiological criteria confirm the diagnosis of this AVNRT by successfully excluding a diagnosis of atrial tachycardia and atrioventricular reentrant tachycardia. The earliest atrial activation during tachycardia was found at the interatrial septum 17.5 mm superior to the site identified during retrograde conduction with the fast pathway. The tachycardia was not inducible after ablation at the right posterior septum, consistent with successful ablation of the typical slow pathway.