Patent Foramen Ovale (PFO)

Patent foramen ovale (PFO) is a small hole between the upper right and left chambers (atria) of your heart. This hole may let blood flow between the atria. PFO often has no symptoms. Many people don’t need treatment unless they’re at risk of stroke or blood clots. Treatments include medications and closure of the hole with a catheter or surgery.


A PFO closure fills an opening between your heart’s two upper chambers. This device keeps blood from flowing between them.
Patent foramen ovale is a small hole between the right and left chambers of your heart that allows blood to flow between them.

What is patent foramen ovale (PFO)?

Patent foramen ovale (PFO) is when you have a small flap or opening between the upper right and left chambers (atria) of your heart. Everyone has this opening, called a foramen ovale, before birth. In most people, this closes after birth. Patent foramen ovale occurs when the flap still exists after birth. “Patent” means “open.”

Most of the time, people with PFO don’t have symptoms and won’t need treatment. But some uncommon problems related to the presence of PFO include stroke and mini-stroke.


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What does a foramen ovale do?

A fetus doesn’t use its lungs to get oxygen-rich blood. Instead, this blood comes from the mother’s placenta, delivered through the umbilical cord. A foramen ovale directs the oxygen-rich blood from the umbilical cord in a fetus’s right upper chamber (right atrium) to the left upper chamber (left atrium).

From there, the blood goes to the left side of the fetus’s heart and provides oxygen to fetus’ brain.

The foramen ovale normally closes after birth. This happens when the baby starts to breathe and blood starts to flow to the lungs to get oxygen. This blood then enters the left side of the baby’s heart before getting pumped to the rest of their body.

Who might have patent foramen ovale?

Anyone can have patent foramen ovale regardless of gender, ethnicity or race. PFO is frequently found in:

  • Divers with decompression illness (air embolism), when air bubbles block your vein or artery due to an environmental pressure change.
  • People who’ve had a stroke of unknown cause (cryptogenic stroke).


How common is patent foramen ovale?

Patent foramen ovale affects about 25% of people worldwide. PFO impacts about 30% to 40% of people who’ve had an unexplained stroke. This does not mean that everyone who has PFO will experience a stroke or mini-stroke.

How does patent foramen ovale affect my body?

Patent foramen ovale lets a small amount of blood flow between the flaps connecting your right and left atrium. Normally these flaps stop blood from flowing between them.

Usually, patent foramen ovale causes no problems. But PFO may let a blood clot travel from the right to the left side of your heart. Your heart could pump the clot into your body. If the clot reaches your brain, it could cut off the blood supply. This would cause an ischemic stroke. The clot may also damage your other organs, such as your kidneys or your heart.


Symptoms and Causes

What causes patent foramen ovale?

Researchers don’t know what causes patent foramen ovale.

What are the symptoms of patent foramen ovale?

Most people will not have any signs or symptoms directly from PFO at all. Possible PFO symptoms include:

Less common conditions people may experience include:

Diagnosis and Tests

How is patent foramen ovale diagnosed?

Your healthcare provider will first ask about your symptoms and do a physical exam. If your provider suspects PFO, they may recommend the following tests:

  • Transthoracic echocardiogram: Echocardiogram (also called an echo) uses sound waves to create images of your heart’s chambers. A provider does a transthoracic echocardiogram using a wand on the skin of your chest.
  • Transesophageal echocardiogram (TEE): Your provider places a probe with a tiny camera near your esophagus. TEE can show a clearer picture of PFO than a standard echocardiogram.
  • Transcranial Doppler (TCD) ultrasound: TCD ultrasound uses sound waves to look at blood flow to and within your brain. This test can also find a stroke due to blood clots.

Your provider may also suggest a bubble test, along with an echo or TCD ultrasound. During a bubble test, they inject saltwater solution into your vein. You may have PFO if your lungs don’t filter out the bubbles and they travel through the hole to your left side of your heart.

Management and Treatment

How is patent foramen ovale treated?

Most people with patent foramen ovale won’t need treatment. But your provider may recommend treatment if you have a history or high risk of strokes or blood clots. Treatments for PFC include:

  • Medication to prevent blood clots, such as aspirin or warfarin.
  • Catheterization, where your interventional cardiologist closes the flap with a long, thin tube (catheter). Your surgeon inserts the catheter into the large vein in your groin and advances it through the blood vessel to your heart. Then, they use a closure device to seal the flap. Studies have found catheterization better than surgery for treating PFO if you’re under 60 years old.
  • Heart surgery, where your surgeon makes an incision and stitches the flap closed. They may suggest surgery if catheterization wasn’t successful. Your surgeon may use open-heart surgery or minimally invasive robotically assisted patent foramen ovale repair. They perform this surgery through small incisions in your chest.

Recent research suggests that PFO closure may help prevent future strokes in people with PFO who’ve had an unexplained stroke. Talk to your provider about which treatment may be right for you.

Are there complications/side effects of patent foramen ovale treatment?

Treatments for patent foramen ovale may cause complications in some people. Complications vary depending on the type of treatment:


Complications of taking aspirin or warfarin may include:


Common complications of the catheter procedure may include:

Less common complications of catheterization may include:


Complications from surgery to close the PFO may include:

  • Atrial fibrillation (Afib).
  • Bleeding.
  • Infection.
  • Stroke.


How can I reduce my risk of patent foramen ovale?

You can’t reduce your risk of PFO. But you should get tested for this condition if you have an unexplained (cryptogenic) stroke. That way, you can get prompt treatment if needed.

Outlook / Prognosis

What is the outlook if I have patent foramen ovale?

Many children with PFO find the flap seals completely on its own during their first three years. Many people who still have PFO as adults lead long, full lives.

Living With

How do I take care of myself if I have patent foramen ovale?

You can keep your heart healthy and reduce your risk of stroke by:

You can also reduce your risk of blood clots by not standing or sitting in the same position for too long.

When should I see my healthcare provider?

See your provider immediately or call 911 if you have any stroke symptoms. These symptoms may include:

A note from Cleveland Clinic

Patent foramen ovale (PFO) is a small communication between the upper right and left chambers of your heart. PFO affects about 25% of people. PFO often doesn’t cause any symptoms and may not require treatment. But it can sometimes indicate stroke or mini-stroke. If you have a history of stroke or blood clots, your provider may suggest treatment. Treatments include medications, catheterization and surgery. Most people with patent foramen ovale can lead full lives.

Medically Reviewed

Last reviewed on 07/15/2022.

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