Foramen ovale (cardiac)
The foramen ovale (or ovalis) is the opening in the interatrial septum in the fetal heart that allows blood to bypass the right ventricle and non-ventilated lungs, shunted from the right atrium to the left atrium. Specifically it represents the opening between the upper and lower portions of the septum secundum.
In the immediate postnatal period, the foramen closes under the influence of changing pressures in the cardiac chambers as 1) placental flow ceases which raises right atrial pressure and 2) the lungs become aerated and ventilation occurs, which increases venous return from the lungs which increases left atrial pressure.
After closure a small oval depression in the interatrial wall persists as the fossa ovale.
Related pathology
See also
