A dilemma in the electrophysiology lab: where is the coronary sinus in a patient with left inferior vena cava with hemiazygos continuation?

Occasionally, electrophysiological interventions are complicated by an unusual or an anomalous cardiovascular anatomy. We report our experience of a case of situs ambiguous and symptomatic heart failure of which anomalous venous anatomy and coronary sinus variation had prevented a successful endocardial placement of a left ventricular lead for cardiac synchronization therapy.