Patent Foramen Ovale (PFO)

It's unclear what causes the foramen ovale to stay open in some people, though genetics may play a role.

An overview of normal heart function in a child or adult is helpful in understanding the role of the foramen ovale before birth.

Normal heart function after birth

Your heart has four pumping chambers that circulate your blood:

• The right atrium. The upper right chamber (right atrium) receives oxygen-poor blood from your body and pumps it into the right ventricle through the tricuspid valve.
• The right ventricle. The lower right chamber (right ventricle) pumps the blood through a large vessel called the pulmonary artery and into the lungs, where the blood is resupplied with oxygen and carbon dioxide is removed from the blood. The blood is pumped through the pulmonary valve, which closes when the right ventricle relaxes between beats.
• The left atrium. The upper left chamber (left atrium) receives the oxygen-rich blood from the lungs through the pulmonary veins and pumps it into the left ventricle through the mitral valve.
• The left ventricle. The lower left chamber (left ventricle) pumps the oxygen-rich blood through a large vessel called the aorta and on to the rest of the body. The blood passes through the aortic valve, which also closes when the left ventricle relaxes.

Baby's heart in the womb

Because a baby in the womb isn't breathing, the lungs aren't functioning yet. That means there's no need to pump blood to the lungs. At this stage, it's more efficient for blood to bypass the lungs and use a different route to circulate oxygen-rich blood from the mother to the baby's body.

The umbilical cord delivers oxygen-rich blood to the baby's right atrium. Most of this blood travels through the foramen ovale and into the left atrium. From there the blood goes to the left ventricle, which pumps it throughout the body. Blood also travels from the right atrium to the right ventricle, which also pumps blood to the body via another bypass system.

Newborn baby's heart

When a baby's lungs begin functioning, the circulation of blood through the heart changes. Now the oxygen-rich blood comes from the lungs and enters the left atrium. At this point, blood circulation follows the normal circulatory route.

The pressure of the blood pumping through the heart usually forces the flap opening of the foramen ovale closed. In most people, the opening fuses shut, usually sometime during infancy.

Generally, a patent foramen ovale doesn't cause complications. But some studies have found the disorder is more common in people with certain conditions, such as unexplained strokes and migraines with aura.

In most cases, there are other reasons for these neurologic conditions, and it's just a coincidence the person also has a patent foramen ovale. However, in some cases, small blood clots in the heart may move through a patent foramen ovale, travel to the brain and cause a stroke.

The possible link between a patent foramen ovale and a stroke or migraine is controversial, and research studies are ongoing.

In rare cases a patent foramen ovale can cause a significant amount of blood to bypass the lungs, resulting in low blood oxygen levels (hypoxemia).

In decompression illness, which can occur in scuba diving, an air blood clot can travel through a patent foramen ovale.

In some cases, other heart defects may be present in addition to a patent foramen ovale.

A doctor trained in heart conditions (cardiologist) may order one or more of the following tests to diagnose a patent foramen ovale:

Echocardiogram

An echocardiogram shows the anatomy, structure and function of your heart.

A common type of echocardiogram is called a transthoracic echocardiogram. In this test, sound waves directed at your heart from a wand like device (transducer) held on your chest produce video images of your heart in motion. Doctors may use this test to diagnose a patent foramen ovale and detect other heart problems.

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

• Colour flow Doppler. When sound waves bounce off blood cells moving through your heart, they change pitch. These characteristic changes (Doppler signals) and computerized colorization of these signals can help your doctor examine the speed and direction of blood flow in your heart.

If you have a patent foramen ovale, a colour flow Doppler echocardiogram could detect the flow of blood between the right atrium and left atrium.

• Saline contrast study (bubble study). With this approach, a sterile salt solution is shaken until tiny bubbles form and then is injected into a vein. The bubbles travel to the right side of your heart and appear on the echocardiogram.

If there's no hole between the left atrium and right atrium, the bubbles will simply be filtered out in the lungs. If you have a patent foramen ovale, some bubbles will appear on the left side of the heart. The presence of a patent foramen ovale may be difficult to confirm by a transthoracic echocardiogram.

Transoesophageal echocardiogram

Doctors may conduct another type of echocardiogram called a transoesophageal echocardiogram to get a closer look at the heart and blood flow through the heart. In this test, a small transducer attached to the end of a tube is inserted down the tube leading from your mouth to your stomach (oesophagus).

This is generally the most accurate available test for doctors to see a patent foramen ovale by using the ultrasound in combination with colour flow Doppler or a saline contrast study.

Other tests

Your doctor may recommend additional tests if you're diagnosed with a patent foramen ovale and you have had a stroke. Your doctor may also refer you to a doctor trained in brain and nervous system conditions (neurologist).

Most people with a patent foramen ovale don't need treatment. In certain circumstances, however, your doctor may recommend that you or your child have a procedure to close the patent foramen ovale.

Reasons for closure

If a patent foramen ovale is found when an echocardiogram is done for other reasons, a procedure to close the opening usually isn't performed. Procedures to close the patent foramen ovale may be done in certain circumstances, such as to treat low blood oxygen levels linked to the patent foramen ovale.
Closure of a patent foramen ovale to prevent migraines isn't currently recommended. Closure of a patent foramen ovale to prevent a stroke remains controversial.
In some cases, doctors may recommend closure of the patent foramen ovale in individuals who have had recurrent strokes despite medical therapy, when no other cause has been found.

Surgical and other procedures for closure

Procedures to close a patent foramen ovale include:

Device closure

Using cardiac catheterization, doctors can insert a device that plugs the patent foramen ovale. In this procedure, the device is on the end of a long flexible tube (catheter).

The doctor inserts the device-tipped catheter into a vein in the groin and guides the device into place with the imaging assistance of an echocardiogram.

Although complications are uncommon with this procedure, a tear of the heart or blood vessels, dislodgement of the device, or the development of irregular heartbeats may occur.

Surgical repair

A surgeon can close the patent foramen ovale by opening up the heart and stitching shut the flap-like opening. This procedure can be conducted using a very small incision and may be performed using robotic techniques.

If you or your child is undergoing surgery to correct another heart problem, your doctor may recommend that you have the patent foramen ovale corrected surgically at the same time. Research is ongoing to determine the benefits of closing the patent foramen ovale during heart surgery to correct another problem.

Stroke prevention

Medications can be used to try to reduce the risk of blood clots crossing a patent foramen ovale. Antiplatelet therapy such as aspirin or clopidogrel (Plavix) and other blood thinning medications (anticoagulants) — such as warfarin (Coumadin, Jantoven), dabigatran (Pradaxa), apixaban (Eliquis) and rivaroxaban (Xarelto) — may be helpful for people with a patent foramen ovale who've had a stroke.

It's not clear whether medications or procedures to close the defect are most appropriate for stroke prevention in people with a patent foramen ovale. Studies are ongoing to answer this question.

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, stop periodically and go for a short walk. On an airplane, be sure to stay well-hydrated and walk around whenever it's safe to do so.

Preparing for your appointment

A patent foramen ovale is often discovered during imaging tests for other conditions or to look for causes of a stroke.

After a patent foramen ovale has been diagnosed, you'll likely have numerous questions for your doctor. Some questions you may want to ask include:

• What caused this to happen?
• How dangerous is this condition?
• What treatments are available, and 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?