ABSTRACT
A persistent left superior vena cava can be demonstrated by echocardiography, preferably by transesophageal echocardiography, visualizing it laterally to the left atrium in the transverse projection. The course and entry of the persistent left-side superior vena cava is evident in the longitudinal projection. Preoperative detection and description of a persistent left superior vena cava are crucial if a patient with either acquired or congenital heart disease is undergoing cardiovascular surgery. In the differential diagnosis, a dilated coronary sinus can be seen in elevated right atrial pressure of any cause, e.g. significant tricuspid regurgitation. Contrast echocardiography will reveal contrast medium regurgitating from the right atrium into the coronary sinus, but not contrast coming from inside the coronary sinus. On cursory examination, a significantly dilated coronary sinus may be mistaken for ostium primum atrial septal defect.
