# Orthodromic Reciprocating Tachycardia Relying on Aberrant Conduction: The Need for a Larger Circuit

## TL;DR

This paper discusses a rare heart rhythm disorder where abnormal electrical pathways rely on a specific conduction delay to sustain the condition.

## Contribution

The study identifies a novel mechanism involving aberrant conduction in orthodromic reciprocating tachycardia.

## Key findings

- Three patients exhibited aberrancy-dependent orthodromic reciprocating tachycardia.
- Creating a functional bundle branch block was necessary to induce the tachycardia in these cases.
- Aberrant conduction can be an essential part of the tachycardia circuit, explaining its infrequent and unsustainable episodes.

## Abstract

Aberrant conduction during orthodromic reciprocating tachycardia (ORT) prolongs the ventriculoatrial conduction time, which can be essential for the maintenance of tachycardia in specific cases. We searched for ORT relying on aberrancy among 220 cases in our center. Three patients showed the phenomenon of aberrancy-dependent ORT. All accessory pathways were located at the lateral regions of the atrioventricular annulus. None of them had a baseline bundle branch block (BBB). Creating a functional BBB was necessary to induce the tachycardias. In two cases, termination of tachycardias was directly associated with resolution of the aberration. In the other case, re-entry required both BBB and slow pathway conduction. We conclude that extra transseptal time caused by aberrancy can be an integral part of the ORT circuit, which explains the infrequent and unsustainable episodes of ORT in certain patients and is useful in understanding the circuit and localizing the pathway.