Visualization of sinus venosus atrial septal defect by transesophageal echocardiography

Atrial septal defect (ASD) is usually suspected clinically but requires a confirmative diagnostic procedure before surgical repair. Two-dimensional and Doppler echocardiography have high sensitivity and specificity for ASD, but the sensitivity of echocardiography is not as high in detecting sinus venosus ASD as it is in ostium primum or secundum defect because of the difficulty in visualizing the sinus venosus area from the subcostal window. For the posteriorly located cardiac structures, including the atrial septum, visualization is superior by transesophageal echocardiography. We describe a case in which sinus venosus ASD was not visualized by conventional transthoracic echocardiography but was diagnosed confidently by transesophageal echocardiography.