What happens when the foramen ovale is closed incompletely?

PFO is a functional

closure of the foramen ovale. However, if the embryo develops abnormally, the foramen ovale still cannot be closed at about 3 years old after birth. This condition is called PFO and generally has no obvious discomfort. However, if strenuous exercise, cough, etc., cause the right atrium pressure to exceed the left atrium, migraine, dizziness, dyspnea and other discomfort symptoms may occur.