The inferior vena cava: an exceptional source of atrial fibrillation.

Mapping in a patient undergoing radiofrequency ablation for drug-refractory paroxysmal atrial fibrillation in the setting of repetitive, monomorphic atrial ectopic beats with negative p waves in the inferior leads revealed an arrhythmogenic focus located in the posteromedial inferior vena cava (IVC) 1 cm below the right atrium to IVC junction. The focus was mapped using a Lasso catheter with successful irrigated-tip catheter ablation at the site of earliest activity. This case demonstrates that, in rare cases, arrhythmogenic muscular sleeves can be found in the IVC and that the IVC can be electrically disconnected from the right atrium using radiofrequency energy.