Ablation of a Left-Sided WPW in a Patient with Persistent Left Superior Vena Cava

Anomalies of the venous system may impose serious limitations to the treatment of arrhythmias by means of ablation therapy. We describe a patient who had WPW syndrome with frequent supraventricular tachycardias in whom an ablation was performed. The patient was found to have a persistent left superior vena cava and a left-sided manifest accessory pathway. Persistent left superior vena cava is the most common congenital thoracic venous anomaly with a prevalence of 0.3-0.5% in the general population and is found more frequently in patients with accessory pathways than in patients with AV nodal reentrant tachycardia. Mapping and ablation of an accessory pathway follows the same general electrophysiology principles applicable to patients without anomalous venous return.