Electrophysiological characteristics and radiofrequency ablation of focal atrial tachycardia originating from the superior vena cava

The initiation of focal atrial tachycardia (AT) from the superior vena cava (SVC) remains unclear, In 3 patients (2 females, 1 male aged 57, 66 and 50 years, respectively) with focal AT arising from different parts of the SVC , the AT occurred spontaneously, rather than being induced by electrical st imulation. The cycle length of the tachycardia was highly variable, ranging between 190 and 300 ms in patient 1,180 and 320 ms in patient 2, and 200 a nd 300 ms in patient 3. The clinical or associated arrhythmias were atrial fibrillation (AF) (patients 1, 3) and atrial flutter (AFL) (patients 2. 3). A presumed SVC potential that was earlier than the activation of all the o ther mapping sites was recorded during AT at the lower anterior ( 15-mm abo ve the atriocaval junction), the mid-anterior (25-mm above the atriocaval j unction) and the lower posterior aspect of the SVC ( 17-mm above the atrioc aval junction. Radiofrequency (RF) ablation targeting the SVC focus with th e SVC potential promptly eliminated the focal AT in all 3 patients. The coe xistent typical AFL was ablated, but the AF was not. The follow-up period w as 6, 6, and 3 months, respectively, for each of the patients under no anti arrhythmic medication; there has not been a recurrence of symptomatic palpi tation. In conclusion, focal electrical firing in the SVC can initiate AT a nd this type of focal AT is always associated with AFL or AF. RF ablation g uided by the presumed SVC potential is safe and highly effective in elimina ting the tachycardia.