Unidirectional reconnection of an inter-atrial epicardial connection with wide right atrial insertion site: a case...

The epicardial connections (ECs) via intercaval fibres connecting the right-sided pulmonary veins (PVs) and right atrium (RA) can preclude isolation of the right-sided PVs. Such ECs occasionally have a unidirectional conduction property.

A 62-year-old man was referred to our institution for catheter ablation of paroxysmal atrial fibrillation (PAF). Circumferential antral PV isolation was performed via point-by-point radiofrequency (RF) applications. Thirty months after the ablation session, a recurrence of PAF was observed and a second procedure was performed. The right-sided PV was reconnected via an EC. Radiofrequency application at the RA insertion eliminated the EC. Thirty minutes thereafter, the right-sided PVs were reconnected. However, repetitive firings from the right-sided PVs did not conduct to the RA, indicating a unidirectional (RA to PV) reconnection of the EC, which was resolved by RF applications at the PV insertion. This time, the PV insertion of the EC was targeted and the unidirectional reconnection was successfully eliminated. The patient has remained free from any tachyarrhythmias for 3 years.

Although the mechanism of the unidirectional conduction property is unclear, source-sink mismatch and anisotropy are likely involved in the mechanism, as with accessory pathways. Electrophysiologists should be aware of the potential for unidirectional reconnection of ECs.