Ectopic tachycardia originating from the superior vena cava.

We report a 65-year-old female patient with a 3-year history of symptomatic paroxysmal supraventricular tachycardia. Electroanatomic and basket catheter mapping revealed a focal tachycardia originating in the superior vena cava (SVC), 5 cm above the SVC-right atrium (SVC-RA) junction. An area of fractionated potentials and slow conduction was found on the anterior wall of the SVC. A line of conduction block extending downwardly and obliquely from the anteroseptal aspect to anterolateral aspect of the SVC forcing the impulse to enter the RA via the posterior aspect of SVC-RA junction was observed. Entrainment attempts from multiple sites within the SVC failed to demonstrate reentry as a mechanism of arrhythmia. The ablation approach consisted of isolation of the arrhythmogenic area from the rest of the SVC.