This 11-year-old girl, who was previously thought to be healthy, came in for a check-up because of tachycardia during stress. A seemingly innocent 2/6 degree murmur (however, holosystolic) can be heard. Note the permanent splitting of the 2nd heart sound. The ultrasound showed a large ASD (atrial septal defect) (10 x 8 mm). Earlier electrocardiography (ECG) and a radiograph had been interpreted as normal. Surgery is required.