# Atrioventricular Ring Tachycardias: Atypical Fast-Slow Atrioventricular Nodal Reentrant Tachycardia and Atrial Tachycardia Share a Common Arrhythmogenic Substrate—A Unifying Proposal

## TL;DR

This paper proposes a new classification for certain heart rhythm disorders, suggesting they share a common heart tissue structure.

## Contribution

The paper introduces the term 'AV ring tachycardia' to unify different types of tachycardias with a shared arrhythmogenic substrate.

## Key findings

- Variants of slow pathway and atypical AV nodal reentrant tachycardia extend beyond Koch’s triangle.
- Superior-type fast-slow AVNRT mimics adenosine-sensitive atrial tachycardia and can be treated via ablation.
- Recent research suggests adult hearts have AV ring tissue around annuli, forming a common arrhythmogenic substrate.

## Abstract

Our understanding of the variants of slow pathway (SP) and associated atypical
atrioventricular (AV) nodal reentrant tachycardia (NRT) is still growing. We have
identified variants extending outside Koch’s triangle along the tricuspid
annulus, including superior, superoanterior and inferolateral right atrial SP and
associated atypical, fast-slow AVNRT. We review the history of each variant,
their electrophysiological characteristics and related atypical AVNRT, and their
treatment by catheter ablation. We focused our efforts on organizing the
published information, as well as some unpublished, reliable data, and show the
pitfalls of electrophysiological observations, along with keys to the diagnosis
of atypical AVNRT. The superior-type of fast-slow AVNRT mimics
adenosine-sensitive atrial tachycardia originating near the AV node and can be
successfully treated by ablation of a superior SP form the right side of the
perihisian region or from the non-coronary sinus of Valsalva. Fast-slow AVNRT
using a superoanterior or inferolateral right atrial SP also mimics atrial
tachycardia originating from the tricuspid annulus. We summarize the similarities
among these variants of SP, and the origin of the atrial tachycardias, including
their anatomical distributions and electrophysiological and pharmacological
characteristics. Moreover, based on recent basic research reporting the presence
of node-like AV ring tissue encircling the annuli in adult hearts, we propose the
term “AV ring tachycardia” to designate the tachycardias that share the AV ring
tissue as a common arrhythmogenic substrate. This review should help the readers
recognize rare types of SP variants and associated AVNRT, and diagnose and cure
these complex tachycardias. We hope, with this proposal of a unified tachycardia
designation, to open a new chapter in clinical electrophysiology.