What happens to the foramen ovale after birth?

Answer 1

The foramen ovale is an opening whereby blood is allowed to travel from the right atrium to the left atrium, bypassing the lungs. The reason for bypassing the lungs is because the fetus does not need to use them while in the womb as the mother's blood supplies oxygen. However, if the foramen ovale isn't closed after birth, typically there are no cardiac complications.However, there have been possibilities (though not yet proven) that there can be increase risks of stroke/ blood clots, migraines, and possibly cyanosis.

Answer 2

The foramen ovale closes after birth. Initially, this is due to a functional equalization of pressures within the atria that apposes the septum primum and the septum secundum. Equalization of pressure occurs because of:

• lung inflation leading to reduced pulmonary vascular resistance
  • foramen ovale is an interatrial communication that permits blood from the inferior vena cava to freely enter the left atrium in utero (right-to-left shunt)
  • at birth, the left atrial pressure exceeds the right atrial pressure (thus reversing the right-to-left shunt of the fetal circulation)
    • this forces the septum primum against the septum secundum, functionally closing the foramen ovale
  • the duct closes by a prostaglandin dependent mechanism, the signal for closure being a rise in circulating oxygen levels
  • eventally the septa eventually fuse and leave a remnant of the foramen ovale, the fossa ovalis

Functional closure can be reversed during the immediate neonatal period; this occurs during bouts of crying when cyanosis may be seen and there is a re-emergent right-to-left shunt.

Anatomical fusion of the septum primum and secundum occurs by one year of age in 80% of the population. Fibrosis results in the fossa ovalis of the interatrial septum. The remaining 20% have a foramen which is only potentially patent. The normal pressures within the atria ensure that it remains closed; the septum primum acts as a flap-valve against the septum secundum due to the greater pressures within the left atrium compared to the right atrium.

Answer 3

The foramen ovale should not close until after birth, when the infant is no longer a fetus, but a neonate. The foramen ovale is an opening between the left and right atria of the heart. In the fetus (before birth), when the infant's blood gets oxygen from the placenta and not the lungs, the foramen ovale lets oxygenated blood get from the right side of the heart to the left, where it can be pumped to the rest of the body. There are other places where this happens as well - the ductus venosus and the ductus arteriosum also serve this purpose. After the child is born, the umbilical cord is cut, and the child takes its first breaths; at that point, the pressure in the pulmonary blood vessels drops, decreasing the pressure gradient from the left to the right heart, thus allowing the foramen ovale to close.

In some circumstances, the foramen ovale does not close, or does not close completely. This is actually not terribly uncommon and frequently will not cause a problem immediately. Later in life, however, this can be an issue, if a left to right shunt develops, leading to systemic hypoxia and heart failure if the foramen is large enough.