We report the case of a 65-year-old patient referred to our hospital for st
roke. In the course of the diagnostic procedure, a transesophageal echocard
iography was performed and showed at first sight a mass attached to the rig
ht aspect of the interatrial septum and mimicking a cystic tumor. But after
performing multiple views, it was in fact demonstrated a large Eustachian
valve with its extremity attached to the right aspect of the interatrial se
ptum. The increasing use of transesophageal echocardiography to evaluate pa
tients makes it important for echocardiographers to recognize this anatomic
entity and its normal variants.