Two dimensional echocardiography in differentiating right atrial and tricuspid valve mass lesions.

Atrial myxoma has been diagnosed on the basis of a characteristic M mode echocardiographic pattern of a mass of echoes appearing, with a lag phase, beneath the anterior leaflet of the mitral or tricuspid valve in diastole. However, this pattern is not specific for an atrial tumor. Two patients are described with tricuspid leaflet endocarditic vegetations whose M mode echocardiograms were strikingly similar to the M mode tracing from a patient with a large right atrial myxoma. In a fourth patient, artifact, resulting from the failure of lateral resolution of the atrial wall, was also capable of producing a mass of echoes appearing, with a lag phase, beneath the anterior tricuspid valve leaflet in diastole. In each patient, two dimensional echocardiography confirmed the presence or absence of a right-sided mass lesion and defined more precisely the location of the echocardiographic density relative to the right atrium and tricuspid valve. Because two dimensional echocardiography is capable of detecting anatomic relations in two distance dimensions and of visualizing movement of intracardiac structures relative to one another in real time, it can play an important role in the identification and differential diagnosis of intracardiac mass lesions.