Fibrillation in the Superior Vena Cava Mimicking Atrial Tachycardia

Abstract

A 49-year-old male was referred for catheter ablation for paroxysmal atrial fibrillation (PAF). PAF had recurred after each of 2 prior left atrial ablation procedures. He had a structurally normal heart with a left atrial diameter of 43 mm. The patient presented to the electrophysiology laboratory in AF with an average AF cycle length (CL) of 150 ms and reconnected pulmonary veins. After electric disconnection of all 4 veins using an antral circumferential approach, AF organized to an atrial tachycardia (AT), which was successfully converted into right atrial common type atrial flutter after ablation in the mid coronary sinus (CS). Ablation of the cavotricuspid isthmus was performed and converted the rhythm to a slightly irregular atrial tachycardia at a CL of approximately 430 ms and a P-wave morphology (inferior axis, positive/negative P wave in V1), suggesting an origin in the vicinity of the sinus node. Mapping in this region revealed a focal tachycardia located in the superior vena cava (SVC) with a CL of approximately 215 ms and predominantly 2:1 veno-atrial conduction. Radiofrequency …