An Unusual Case of Severe Stenosis of the Coronary Sinus Ostium in Association With Double Inlet Left Ventricle.

We present a patient with complex single ventricle physiology who was subsequently diagnosed with atresia of the coronary sinus ostium in the setting of myocardial dysfunction following operative palliation. Although a rare cardiac defect, awareness is important as the coronary venous system will often drain to a left superior vena cava (LSVC). If the LSVC is ligated without knowing of this defect, cardiac dysfunction and death can occur.