Characteristics and Outcomes of Focal Atrial Tachycardia Originating from Sinus Venosus Developed during Catheter Ablation of Atrial Fibrillation

Background: The sinus venosus (SV) is not well known source of focal atrial tachycardia (AT) developed during Catheter ablation (CA) of atrial fibrillation (AF). We investigated the characteristics of focal AT originating from SV. Methods: Total of 1172 patients who underwent CA for AF were reviewed. Electrophysiological and electrocardiographic characteristics and outcomes after CA of AT originating from SV were investigated. Results: Five patients (0.42%) showed focal AT from SV (5 males, 49±19.6 years, 4 persistent and 1 paroxysmal) developed during ablation of AF. Mean cycle length was 279±52 ms. Four patients showed negative P wave in lead V1 and positive P in II, III and aVF in all. The activation sequence of AT was from proximal to distal in superior vena cava and high to low at right atrial septum. Double potentials were recorded during sinus and a second discrete potential preceded 64±26 ms before onset of P wave during AT. Using 6.2 radiofrequency applications, ATs were terminated and became no longer inducible in all. One patient showed transient right phrenic nerve injury. After 10.7 months, all patients were free from any arrhythmia. Conclusions: Focal AT from SV developed during AF ablation had unique electrophysiologic characteristics that are helpful in guiding successful CA.