What are the advantages of the foramen ovale (hole in heart) for a fetus?
The foramen ovale is a normal cardiac structure found in all newborns and can be best described as a “door” between the right and left atria. The foramen ovale is essential for proper fetal circulation, directing oxygenated, nutrient-rich blood from the placenta, preferentially to the developing fetal brain. During fetal life, the “door” is open, and blood passes from the right to left atrium. However, with separation from the placenta and with the first few breaths, the left atrium fills with blood returning from the lungs and closes the “door.” During the first years of life, the foramen ovale seals shut and becomes a true wall that separates the right and left atria. However, in a significant proportion of people, the foramen ovale does not seal shut and remains a potential trapdoor between the 2 atria. A patent foramen ovale (PFO) is defined as a foramen ovale that does not seal. All newborns are expected to have a patent foramen ovale. The time frame over which most seal shut is v
