What is Patent Foramen Ovale (PFO)?

What is Patent Foramen Ovale (PFO)?

Patent foramen ovale (PFO) is a flap-like opening in the heart between the upper chambers. The foramen ovale is a structure in the wall of the heart between the two upper chambers, the right atrium and left atrium. It’s present in all babies and is a critical part of the fetal circulation before birth, allowing oxygen-rich blood to flow from the right side of the heart to the left. After birth, once the baby starts to breathe on its own, right-to-left flow is no longer needed and the flap usually seals.

When the flap doesn’t fully close, it’s called a patent foramen ovale (PFO). This occurs in about one in four people, with the vast majority having no symptoms or medical problems.

Patent foramen ovale (PFO) vs. atrial septal defect (ASD)

Patent foramen ovale is one of two types of holes in the heart. The other is called an atrial septal defect (ASD).

Comparing PFO vs. ASD:

  • Both PFO and ASD present as a hole between the top two heart chambers. The abnormal hole allows for a little blood to flow from one side to the other.
  • A patent foramen ovale is a hole that exists in every developing baby’s heart. Usually, once a child is born and takes its first breath, the hole closes and seals permanently within a few months. PFO is when the hole fails to close.
  • An atrial septal defect is a failure of tissue to grow between the top heart chambers. Unlike a PFO, it is a congenital defect that only some are born with.
  • An ASD is typically a larger hole and is more likely to cause symptoms in otherwise healthy patients
  • ASDs often need to be repaired whereas patients with PFO don’t often need treatment
  • While PFO occurs in one of every four people, ASD is far less common, occurring in about one in 10,000 births
  • There are different types of ASDs. They are each named for the location in the heart wall and may require different treatments.

Signs & Symptoms of Patent Foramen Ovale


PFO is common, presenting in about one in four people. But more than 95% of those with the condition will never find out, as most don’t suffer PFO symptoms or health issues. Heart specialists don’t often need to diagnose or treat PFO in healthy patients. However, some people experience symptoms and complications of PFO, such as migraine headaches in adults and an increased risk of blood clots or stroke.

Complications of Patent Foramen Ovale


In general, patent foramen ovale doesn’t cause symptoms or health complications, but it can increase your risk for developing the following:

  • Migraine headaches
  • Blood clots
  • Low oxygen levels (Platypnea orthodeoxia)
  • Shortness of breath and dizziness if you suffer from low oxygen levels
  • Increased chance of decompression illness (“the bends”) in scuba or deep-sea divers
  • Stroke
  • Transient ischemic attack (TIA), which may be an early warning sign of a stroke. Sometimes called a ministroke.
  • Heart attack (rare)
  • Vision loss

In some cases, an exam following a stroke or transient ischemic attack may be the first time a PFO is discovered in the heart.

Many of the above complications may be attributed to other heart conditions other than patent foramen ovale. Your doctor can help determine the cause.

What Causes Patent Foramen Ovale?


The cause of why a patent foramen ovale stays open in some hearts and not others is unknown.

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Trust NewYork-Presbyterian for Patent Foramen Ovale Care

NewYork-Presbyterian provides world-renowned pediatric and adult cardiovascular care. Our multidisciplinary teams specialize in a range of heart conditions, including congenital heart issues such as PFO, aortic disease, pulmonary hypertension, and valvular heart disease.

Our exceptional cardiologists are familiar with the symptoms of patent foramen ovale, and can offer comprehensive diagnosis and treatment options for you or your child.