Epicardial Tachycardia Originating From a Persistent Left Superior Vena Cava
A 47-year-old woman with a patent secundum atrial septal defect (maximal diameter, 14 mm), a persistent left superior vena cava (LSVC), and a 24-month history of symptomatic paroxysmal atrial fibrillation that was not responsive to antiarrhythmic medication was referred for catheter ablation. During the index procedure, she underwent radiofrequency isolation guided by a circumferential mapping catheter (Lasso, Biosense Webster, Diamond Bar, Calif) of 4 normally situated pulmonary veins, and ablation of the cavotricuspid isthmus. Postablation pacing maneuvers induced sustained slow-fast atrioventricular nodal reentrant tachycardia that was treated by ablation of the slow pathway. Two months later, the patient returned to the electrophysiology laboratory for evaluation of a persistent atrial tachycardia.
The 12-lead ECG was consistent with a tachycardia of left atrial origin (Figure 1). Persisting pulmonary venous electrical disconnection was confirmed. An electroanatomic map (CARTO, Biosense Webster) of the left atrium during tachycardia indicated a focal origin from the superolateral aspect of the mitral annulus (cycle length, 290 ms), in close relation to the anterior aspect of the persistent LSVC. A second electroanatomic map of the LSVC revealed that the site of earliest activity during tachycardia was within this structure (Figure 2A), which preceded earliest activation of the left atrial endocardium by 57 ms. Inadvertent mechanical termination of the tachycardia occurred during mapping of the LSVC; however, infusion of isoprenaline evoked local ectopy, the elimination of which was achieved by ablation at the site of earliest activity. Guided by the circumferential mapping catheter, isolation of the LSVC from the left atrium was achieved. Further inducibility testing with programmed stimulation and burst pacing from within the LSVC was unable to precipitate any atrial arrhythmia.
Dr Hocini received honoraria from Biosense Webster; Dr Jaïs served as speaker for and received honoraria from Biosense Webster; and Dr Haïssaguerre served as speaker for and received honoraria from Biosense Webster. The other authors reported no disclosures.