[Preoperative diagnosis of unroofed coronary sinus: a case report].

A 54-year-old man was admitted to our hospital because of exertional dyspnea. A second heart sound with fixed splitting and a systolic ejection murmur along the left sternal border was audible. The chest roentgenogram showed increased pulmonary vascularity, and the electrocardiogram showed incomplete right bundle branch block. Two-dimensional echocardiography in the parasternal view demonstrated a partition defect between the left atrium and the coronary sinus. Furthermore, transesophageal echocardiography revealed a left-to-right shunt flow into the coronary sinus through the defect. At these points, the patient was diagnosed as having a partially unroofed mid-portion of the coronary sinus. Unroofed coronary sinus is a cardiac anomaly rarely diagnosed prior to surgical operation. Two-dimensional echocardiography, especially transesophageal echocardiography, is useful for the preoperative diagnosis of unroofed coronary sinus.