Retrograde venography and three-dimensional mapping of a great cardiac vein with separate drainage into the high right atrium in a patient with Wolf-Parkinson-White syndrome.

A 13-year-old boy presenting with palpitations was diagnosed with Wolf-Parkinson-White syndrome. We elected to bring him to the electrophysiology lab for evaluation of the accessory pathway and potential ablation. Structural assessment of the coronary sinus with electro-anatomical mapping and retrograde venography led to the discovery of a great cardiac vein having a separate insertion from the coronary sinus into the high right atrium. The accessory pathway was localized to the left lateral portion of the mitral annulus and treated successfully with radiofrequency ablation. Such venous anatomical variant has been seldom reported, and its association with an accessory pathway is described here for the first time. Its recognition can have important implications when performing procedures that require access into the coronary venous system.