Giant eustachian valve with echocardiographic appearance of divided right atrium

The eustachian valve is an embryologic remnant of the valve of the inferior vena cava. It may be prominent in some individuals, but the echocardiographic appearance of a divided right atrium, as the consequence of a large eustachian valve, is extremely rare. Herein we describe an unusual giant eustachian valve with an echocardiographic appearance of a septal structure dividing the right atrium into 2 separate chambers. This abnormality should be differentiated from cor triatriatum dexter, a very rare cardiac malformation for which it could be mistaken.