Prominent Eustachian valve
Above finding was incidentally noted while performing physical examination (POCUS) in a patient with heart failure and acute kidney injury. Note the thin mobile hyperechoic structure arising from the anterior rim of the IVC orifice (arrow) projecting into right atrium consistent with a prominent eustachian valve.
Below are other cardiac views demonstrating the valve with respective anatomic correlates.
During fetal life, the eustachian valve directs oxygenated blood from IVC towards the foramen ovale and away from the tricuspid valve. After the closure of the foramen ovale, it does not have a specific function and either disappears completely or remains as a thin ridge. In some cases, such as ours, it can persist as a prominent elongated mobile structure. It is benign but may occasionally be confused with thrombus or other abnormal structure. Rarely, it may be large enough to cause IVC obstruction or interfere with placement of transvenous devices. It may also harbor vegetations or thrombi. Transesophageal echocardiography is often necessary when such complications are suspected.
In addition to eustachian valve, prominent crista terminalis (fibromuscular ridge formed by the junction of sinus venosus and primitive right atrium) and Chiari network (net-like embryonic remnants of valves of sinus venosus) are two other benign (mostly) structures in the right atrium that POCUS users must be familiar with. See anatomic illustrations below and go through the linked case reports for sonographic images. In the left atrium, coumadin ridge is one such notable finding that we previously discussed.