[Endocavitary electric cardioversion of atrial fibrillation in patients with persistent left superior vena cava].

The observation of a persistent left superior vena cava is a rare event during electrophysiological procedures. In the literature, many studies can be found describing permanent pacemaker implantation in patients with this congenital defect. We describe the case of a 70-year-old woman, referred to our centre for persistent atrial fibrillation, not converted to sinus rhythm with transthoracic electrical cardioversion in whom we decided to attempt an endocardial electrical cardioversion. During catheter positioning, via the left subclavian vein, we observed the presence of a left superior vena cava.