eustachian valve

Crista terminalis, seen as a ridge (notch) of the atrial wall.

The eustachian valve arises from the inferior vena cava just as it enters the right atrium. It may be quite prominent and fairly long (2 to 3 cm or more). It may lead to misinterpretation and become confused with a tumor, thrombus or even a vegetation.

The eustachian valve is important for fetal circulation - it directs blood from the inferior vena cave to the foramen ovale.

The right atrial appendage is more rectangular and "shallow" compared to the left appendage, and is less trabeculated. The right atrial appendage is not seen on transthoracic echo. However, since you will rarely see pathologies or thrombi in this region, this is no real problem.