Patent foramen ovale


A patent foramen ovale (PFO) is a hole in the heart that didn't close the way it should after birth. The hole is a small flaplike opening between the upper heart chambers. The upper chambers of the heart are called the atria.

As a baby grows in the womb, an opening called the foramen ovale (foh-RAY-mun oh-VAY-lee) sits between the upper heart chambers. It typically closes during infancy. When the foramen ovale doesn't close, it's called a patent foramen ovale.

Most people never need treatment for patent foramen ovale.


Patent foramen ovale occurs in about 1 in 4 people. Most people with the condition never know they have it. A patent foramen ovale is often discovered during tests for other health problems.


It's unclear why the foramen ovale stays open in some people. Genetics may play a role.

How the heart works

To understand more about patent foramen ovale, it may be helpful to know how the heart typically works.

The typical heart has four chambers that pump blood:

  • The right upper chamber, also called the right atrium. This heart chamber receives oxygen-poor blood from the body. It pumps blood to the right lower heart chamber through the tricuspid valve.
  • The right lower chamber, also called the right ventricle. This heart chamber pumps blood to the lungs through a large vessel called the pulmonary artery. In the lungs, blood picks up oxygen. The blood moves through the pulmonary valve. The valve closes when the chamber relaxes between beats.
  • The left upper chamber, also called the left atrium. This heart chamber receives the oxygen-rich blood from the lungs. It sends blood through the pulmonary veins and mitral valve and into the left lower chamber.
  • The left lower chamber, also called the left ventricle. This chamber is the heart's main pumping chamber. It pumps the oxygen-rich blood to the rest of the body through the body's largest blood vessel, called the aorta. The blood passes through the aortic valve, which also closes when the chamber relaxes.

The heart before birth

Because a baby in the womb isn't breathing, the lungs aren't working yet. That means there's no need to pump blood to the lungs. At this stage, blood goes around the baby's lungs. It uses the placenta and umbilical cord to move oxygen-rich blood from the mother to the baby's body.

In the baby's body, blood vessels connect to the umbilical cord. Oxygen-rich blood gets to the heart through the vein that drains blood from the body to the right upper heart chamber. This vein is called the inferior vena cava. The blood then goes across the foramen ovale and into the left upper heart chamber. Finally, the blood enters the left lower heart chamber, which pumps it throughout the body.

Newborn baby's heart

When a baby's lungs begin working, blood flow through the heart changes. Now the oxygen-rich blood comes from the lungs and enters the left upper heart chamber.

The pressure of the blood pumping through the heart usually forces the flap opening of the foramen ovale to close. In most people, the opening closes sometime during infancy.

Chambers and valves of the heart


A patent foramen ovale, also called a PFO usually doesn't cause complications. Some people with a PFO may have other heart defects

Possible complications of patent foramen ovale may include:

  • Low blood oxygen. Rarely, a patent foramen ovale can cause a significant amount of blood to go around the lungs. This lowers blood oxygen levels, a condition called hypoxemia.
  • Stroke. Sometimes small blood clots in veins may travel to the heart. They may go through a patent foramen ovale and into the left side of the heart. From there, they can travel to the brain and block blood flow, causing an ischemic stroke.

Some studies have found that PFOs are more common in people with unexplained strokes and migraines with aura. But more research is needed. Usually, there are other reasons for these conditions. It's often just a coincidence a person also has a PFO.


Usually a patent foramen ovale is diagnosed when tests are done for another health concern. If your health care provider thinks you may have a PFO, imaging tests of the heart may be done.

If you have a patent foramen ovale and had a stroke, your provider may refer you to a doctor trained in brain and nervous system conditions. This type of provider is called a neurologist.


A test called an echocardiogram is used to diagnose a PFO. The test uses sound waves to create pictures of the beating heart. An echocardiogram shows the structure of the heart. It also shows how blood flows through the heart and heart valves.

Transthoracic echocardiogram

This is a standard echocardiogram. It takes pictures of the heart from outside the body. The health care provider presses an ultrasound device, called a transducer, firmly against the skin over the heart area. The device records the sound wave echoes from the heart. A computer changes the echoes into moving images.

Variations of this procedure may be used to identify a patent foramen ovale, including:

  • Color-Doppler. When sound waves bounce off blood cells moving through the heart, they change pitch. These changes are called Doppler signals. They appear in different colors on the echocardiogram. This test can show the speed and direction of blood flow in the heart.

    If you have a patent foramen ovale, this type of echocardiogram usually shows blood moving between the upper heart chambers.

  • Saline contrast study, also called a bubble study. During a standard echocardiogram, a sterile salt solution containing tiny bubbles is given by IV. The bubbles travel to the right side of the heart. They can be seen on an echocardiogram.

    If there's no hole between the upper heart chambers, the bubbles are filtered out in the lungs. If you have a patent foramen ovale, some bubbles show up on the left side of the heart.

Transesophageal echocardiogram

A patent foramen ovale may be difficult to confirm on a standard echocardiogram. Your provider may recommend this test to get a closer look at the heart.

A transesophageal echocardiogram takes pictures of the heart from inside the body. It's considered the most accurate way to diagnose a patent foramen ovale.

During this test, a flexible probe containing the ultrasound device is guided down the throat and into the tube connecting the mouth to the stomach. This tube is called the esophagus.


Most people with a patent foramen ovale don't need treatment. If a PFO is found when an echocardiogram is done for other reasons, a procedure to close the hole usually isn't done.

When treatment for a PFO is needed, it may include:

  • Medicines
  • A catheter procedure to close the hole
  • Surgery to close the hole


Your doctor may recommend medicines to try to reduce the risk of blood clots crossing a patent foramen ovale. Blood thinners may be helpful for some people with a patent foramen ovale who've had a stroke.

Surgery or other procedures

If you have a PFO and low blood oxygen levels or an unexplained stroke, you may need a procedure to close the hole.

Closure of a patent foramen ovale to prevent migraines isn't currently recommended as the first treatment. Closure of a patent foramen ovale to prevent recurrent stroke is only done after care providers trained in heart and nervous system disorders have said that the procedure will help you.

Procedures to close a patent foramen ovale include:

  • Device closure. In this procedure, the provider inserts a thin, flexible tube called a catheter into a blood vessel in the groin area. The catheter tip has a device to plug the PFO. The provider guides the equipment to the heart to close the opening.

    Complications of device closure are uncommon. They may include a tear of the heart or blood vessels, movement of the device, or irregular heartbeats.

  • Surgical closure. In this heart surgery, the surgeon uses stitches to close the PFO. This surgery can be done using a very small incision. It may be done using robotic techniques.

    If heart surgery is needed for another reason, your provider may recommend that this surgery be done at the same time.

Self care

If you know you have a patent foramen ovale, but don't have symptoms, you probably won't have any restrictions on your activities.

If you'll be traveling long distances, it's important to follow recommendations for preventing blood clots. If you're traveling by car, take breaks and go for short walks. On an airplane, be sure to drink plenty of fluids and walk around whenever it's safe to do so.

Preparing for your appointment

After a patent foramen ovale has been diagnosed, you'll likely have a lot of questions for your health care providers. Some questions you may want to ask include:

  • What caused this to happen?
  • How dangerous is this condition?
  • What treatments are available? Which do you recommend?
  • What are the risks of a procedure to close the patent foramen ovale?
  • I have other health conditions. How can I best manage these conditions together?
  • Should activity be restricted in any way?
  • Could I have passed this condition on to my child?
  • Are there any brochures or other printed material that I can take home with me? What websites do you recommend visiting?

Content From Mayo Clinic Updated: 10/24/2022
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