# Atrioventricular node ablation and the pathological findings of a refractory ectopic atrial tachycardia in a small infant with hypoplastic left heart syndrome: a case report

## TL;DR

A 3-month-old infant with a heart defect and a difficult-to-treat heart rhythm disorder underwent a successful ablation procedure, but later died from an infection.

## Contribution

This case report demonstrates successful AVN ablation in a hypoplastic left heart syndrome patient with refractory ectopic atrial tachycardia.

## Key findings

- AVN ablation at the mid-septum of the tricuspid annulus successfully created AV block without damaging surrounding structures.
- The patient showed hemodynamic stability post-ablation with a dual-chamber pacemaker.
- Pathological findings confirmed complete ablation of the AV node without tricuspid or coronary damage.

## Abstract

An atrioventricular node (AVN) ablation and permanent pacing have been previously reported as effective treatments for patients with atrial tachyarrhythmias. However single-ventricle patients requiring chronic ventricular pacing are at a higher risk of developing ventricular dysfunction and atrioventricular valve regurgitation. We report a case of successful AVN ablation in a 3-month-old infant with hypoplastic left heart syndrome and ectopic atrial tachycardia (EAT).

A boy with hypoplastic left heart syndrome who had a refractory EAT resistant to various medications. At 2 months old, we performed an urgent radiofrequency (RF) catheter ablation of the EAT and the applications delivered at the cavo-atrial junction. Although it disappeared after the first catheter ablation for 2 weeks, it recurred on the next day after the diaphragm plication. At 3 months old and weighed 3.1 kg, we decided to perform an urgent AVN ablation of the EAT. The application was performed on the mid-septum of the tricuspid septum. A permanent pacemaker was implanted after the ablation. After the AVN ablation, the haemodynamics stabilized during the EAT. However, he died from a bacteraemia infection at 4 months.

This patient received an AVN ablation due to failure to previous RF catheter ablation and was haemodynamically stable with the dual-chamber pacemaker. The AV block was successfully created by RF energy on the mid-septum of the tricuspid annulus in this hypoplastic left heart syndrome patient. Pathological findings exhibited that the compact AVN was totally ablated without damage to the tricuspid leaflets or coronary artery.