Intra-SVC re-entrant atrial tachycardia successfully treated with a circular multi-electrode array pulsed-field ablation catheter-case report.

Background: The superior vena cava (SVC) is a well-recognized non-pulmonary vein (PV) focus in atrial fibrillation (AF); however, intra-SVC re-entrant atrial tachycardia (AT) is extremely rare. Case summary: An 83-year-old woman with a history of PV isolation using radiofrequency ablation 1 year earlier was referred for a second ablation due to recurrent AT. Activation mapping of the AT demonstrated a re-entrant circuit involving the left atrial (LA) posterior wall. Because bilateral PVs were reconnected, pulsed-field ablation (PFA), including PV re-isolation and LA posterior wall isolation, was performed using a circular multi-electrode array PFA catheter. The initial PFA application did not terminate the tachycardia; however, the arrhythmia transitioned to a different AT. High-resolution mapping revealed a re-entrant circuit confined within the SVC sleeves, characterized by transverse re-entrant propagation. Entrainment pacing confirmed intra-SVC re-entry. Circumferential PFA was delivered to the SVC during sinus rhythm, achieving SVC isolation without sinus node dysfunction or phrenic nerve palsy. Discussion: This case demonstrates effective management of intra-SVC re-entrant AT using a circular multi-electrode PFA catheter. High-resolution mapping identified a rare re-entrant circuit confined to the SVC. Owing to its tissue selectivity, PFA enables safe and effective SVC isolation while minimizing the risk of phrenic nerve injury.