Novel concept of atrial tachyarrhythmias originating from the superior vena cava: Insight from noncontact mapping

Introduction: Information about the activation patterns inside the superior vena cava (SVC) and entry and exit sites at the SVC-right atrial (RA) junction during SVC tachyarrhythmia is limited. Methods and Results: A detailed characterization of electrophysiologic mechanisms and ablation strategies was performed using a noncontact three-dimensional mapping system in two cases of SVC tachycardia. The first case demonstrated SVC tachycardia originating from an ectopic focus inside the SVC, with sustained depolarization and conduction to the atrium. Entry and exit sites across the SVC-RA junction were located very close to each other. The second case demonstrated two different reentrant circuits, one inside the SVC and the other into and out of the SVC-RA junction. The entry and exit sites were located far away from each other. Conclusion: Noncontact mapping may help to reveal the mechanism of SVC tachyarrhythmias and to locate entry and exit sites at the SVC-RA junction as a guide for catheter ablation.