Radiofrequency Ablation of an Unusual Focal Atrial Tachycardia

Background: Focal atrial tachycardia (FAT) is an uncommon type of supraventricular tachycardia in children. Medical therapy with a variety of antiarrhythmic drugs has been implemented, especially in young children who are likely to experience spontaneous resolution. Radiofrequency (RF) ablation is the treatment of choice in older children with a success rate of 80%. Typical FAT localizations include the right or left atrial appendage or crista terminalis. We report an unusual FAT case in a 10-year-old girl.

Method: FAT had been diagnosed in the course of severe pneumonia at the age of 3 months. Tachycardia was refractory to multiple combinations of antiarrhythmic drugs. Rate control was finally achieved by a combination of propafenone and propranolol. LV function was normal. At the age of 10 years, the girl (36 kg) was referred for catheter ablation. Antiarrhythmic medication was discontinued 2 days before the electrophysiological study. The procedure was performed under general anesthesia. 3D mapping was performed using the EnSite NavX Mode (Abbott Medical GmbH).

Results: Mapping in the right atrium showed the earliest atrial activation during incessant FAT at the septal region. Consecutively, access to the left atrium (LA) was achieved via transseptal puncture. LA mapping showed the earliest atrial activation at the posterior atrial wall close to the LA roof in an area of fractionated signals. RF application using an irrigated tip catheter (FlexAbility, Abbott) with 35 W led to successful FAT elimination. Within a waiting time of 30 minutes, no recurrence was observed. However, on the ECG 5 hours after ablation, SVES and short FAT bursts were noted. As the child came from abroad, a second ablation approach was suggested and was performed on the following day. LA access was possible without transseptal puncture. The earliest atrial activation was again found at the high posterior LA wall. RF application with the irrigated tip catheter using high power–short duration (70 W, 5 sec) led to successful elimination of focal activity. There were no procedural complications. Follow-up at 1 week showed no FAT on ECG or Holter.

Conclusion: FAT localization at the posterior LA wall in children is very rare. It might be speculated that subclinical myocarditis caused the zone of fractionated signals. In our case, a second RF ablation using high power–short duration ablation leads to permanent suppression of the focus.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
28 January 2023