Word parts
foramen openingovale oval
What it means
Before birth, the fetus gets oxygen from the placenta, so most blood skips the lungs, passing from the right atrium straight to the left atrium through this flap-like opening. After birth, the lungs fill with air, pressure in the left atrium rises, and the flap closes, usually sealing over time. In about a quarter of adults it never seals fully, which is called a patent foramen ovale.
Related terms
atrial septal defect
A hole in the wall between the two upper chambers of the heart.
ductus arteriosus
A blood vessel in the fetus that connects the pulmonary artery to the aorta, so blood can skip the lungs.
patent foramen ovale
An opening between the heart's two upper chambers that did not close after birth as it normally does.