A 19-year-old woman admitted to the our cardiology department with progressive dyspnea on effort and palpitations. Her blood pressure 115/85 mmHg, heart rate 70/min, and respiratory rate 20/min. Cardiac auscultation revealed 2/6 grade systolic ejection murmur at the left upper sternal border. Electrocardiography demonstrated sinus rhythm with incomplete right bundle branch block. Transthoracic echocardiography revealed right atrial and ventricular enlargement and a left-to-right shunt within the atrial septum. In Doppler echocardiography demonstrated moderate tricuspid regurgitation. Pulmonary artery pressure was 38 mmHg and the Qp/Qs ratio was 1.6. Transesophageal echocardiography showed an ostium secundum defect, 5 mm in diameter Figure 1, arrow , and a sinus venous defect, 15 mm in diameter Figure 2, arrow .