A 63-year-old woman complained of general malaise and insomnia initially. Atrial septal defect was diagnosed by transthoracic echocardiography thereafter. She had not received complete cardiac studies until progressive dyspnea was noted half a year later. After a series of examinations, sinus venosus type atrial septal defect (ASD) associated with partial anomalous pulmonary venous connection to high superior vena cava (SVC) and persistent left SVC was documented. Surgical correction was performed later. The postoperative course was smooth and her condition improved gradually at 10-month follow-up.