Inferior sinus venosus atrial septal defect.

One case of inferior vena cava type sinus venosus defect is reported. It is likely to be missed on transthoracic echocardiography. Transesophageal echocardiography is useful. Unlike superior sinus venosus defect which are easily visible on transesophageal echocardiography, a careful search is needed to detect inferior sinus venosus defects. All patients with unexplained right ventricular volume overload on transthoracic echocardiography should have transesophageal echocardiography to see for sinus venosus atrial septal defects.