Inferior Sinus Venosus Type Atrial Septal Defect Initially Presenting Pulmonary Hypertension on Transthoracic Echocardiography

Inferior sinus venosus type atrial septal defect (ASD) is a rare congenital cardiac deformity that occurs between the inferior vena cava and right atrium. Inferior sinus venosus defect is difficult to diagnose through transthoracic echocardiography because of its location which is infero-posterior to the fossa ovalis. Increasing pulmonary arterial pressure and pulmonary vascular resistance in patients with sinus venosus defect usually occur earlier than other types of ASD. We report a case of 19- year-old man who presented exertional dyspnea due to inferior sinus venous type ASD with mild pulmonary hypertension. In this case, we found clues from slight diastolic flattening of interventricular septum and shortened acceleration time of right ventricular outflow tract on initial transthoracic echocardiography, leading right heart catheterization and transesophageal echocardiography to reveal this rare type of ASD.