Unusual eustachian valve function

Abstract

The eustachian valve directs oxygen-rich blood from the inferior vena cava toward the foramen ovale and away from the tricuspid valve during fetal development. Ordinarily, it does not prevent reflux of right atrial blood back into the inferior vena cava because it does not function as a true valve. Here we describe an unusual adult patient with severe tricuspid valve regurgitation in whom the eustachian valve did function as a true, albeit regurgitant, valve.