Eustachian Valve

The eustachian valve, named after Bartolomeo Eustachi, is also known as valvula venae cavae inferioris. It is a remnant of the embryonic right valve of the sinus venosus.

In the fetal circulation the eustachian valve directs oxygenated blood from the inferior vena cava into the left atrium via the patent foramen ovale. The eustachian valve also directs deoxygenated blood from the superior vena cava toward the right ventricle through the tricuspid valve, preventing it from crossing into the left atrium.

References

Manson F. Eustachian valve. www.TheFetus.net. 2006-06-07-15