Sinus venosus atrial septal defects (SVASDs) have a strong association with partial anomalous pulmonary venous return (PAPVR). Symptoms are uncommon in childhood and the diagnosis may be delayed for several years. Surgery is typically postponed to pre-school age as the lesion is well-tolerated. Preoperative follow-up commonly includes periodic transthoracic echocardiograms (TTE) and electrocardiograms (ECG). An important component of preoperative planning includes accurate delineation of PAPVR w…