Patent foramen ovale (PFO)


A patent foramen ovale (PFO) is a condition characterized by a hole in the heart that remains open after birth. The hole is a small flap-like opening situated between the upper heart chambers, also known as atria.

During fetal development, there is a natural opening known as the foramen ovale between the upper heart chambers. Typically, this opening closes soon after birth. However, when the foramen ovale fails to close, it results in a patent foramen ovale.

Although most individuals with PFO do not exhibit any symptoms and do not require treatment, some rare complications may arise due to the presence of the condition, such as stroke or mini-stroke.


Most people with a patent foramen ovale may not experience any signs or symptoms. The condition is often only discovered during examinations for other medical issues. It is estimated that one in every four people has this condition.
Among the possible PFO symptoms are:

  • Stroke.
  • Transient ischemic attack (TIA) or mini stroke, which affects important organs such as the brain, small intestine, large intestine, or kidneys and hinders the ability to move the arms or legs.

Rarely, patients may also experience heart attack, hypoxemia, and Platypnea-orthodeoxia (P-O) syndrome.


The exact reason why the foramen ovale remains open in certain individuals is unclear. However, genetics may be a contributing factor.

  • Heart before birth: Before birth, the baby’s lungs are not yet functioning, so the heart does not need to pump blood to them. Instead, oxygen-rich blood is provided to the baby’s body through the placenta and umbilical cord from the mother. Blood vessels in the baby’s body connect to the umbilical cord, and the inferior vena cava delivers oxygen-rich blood to the heart’s right upper chamber. The blood flows through the foramen ovale into the left upper chamber and then into the left lower chamber, which pumps it throughout the baby’s body.
  • Heart of a newborn: When a baby’s lungs start functioning, the heart’s blood flow pattern changes. Oxygen-rich blood now comes from the lungs and enters the left upper chamber of the heart. The pressure created by blood pumping through the heart causes the flap opening of the foramen ovale to close, which usually happens during infancy in most individuals.