Utility of three-dimensional transesophageal echocardiography for diagnosis of unroofed coronary sinus

We report a case of unroofed coronary sinus (URCS) in a 42-year-old female. At an outpatient clinic, she was found to have an atrioventricular septal defect and mitral regurgitation with pulmonary hypertension, and she was transferred to our institute for surgical treatment. Both atrioventricular valves were located at the same level, and both the right atrium (RA) and right ventricle were enlarged on two-dimensional transthoracic echocardiography. Color Doppler imaging demonstrated severe mitral and tricuspid regurgitation and a left-to-right shunt from the left atrium (LA) to the RA. Although an ostium primum defect of the atrial septum was suspected, the exact position of the shunt flow was unclear. Two-dimensional transesophageal echocardiography (2D-TEE) could visualize a direct communication between the LA and coronary sinus. Three-dimensional transesophageal echocardiography (3D-TEE) clearly visualized the entire route from the coronary sinus into the LA and RA. The utility of 3D-TEE as a modality complementary to 2D-TEE in diagnosis of URCS was confirmed.