In normal fetal development, a small, flap-like opening — the foramen ovale (fo-RA-mun o-VA-le) — is present between the right and left upper chambers of the heart (right atrium and left atrium).

The foramen ovale usually closes within the first or second year of life. However, in at least one out of four people, this opening persists throughout life. This condition, called patent foramen ovale (PFO), may allow blood to flow from the heart's right atrium to the left atrium and vice versa.

Most people with patent foramen ovale don't need treatment and don't know they have the condition. Patent foramen ovale is often discovered during tests for other heart problems. Learning that you have a hole in your heart is understandably worrisome. Patent foramen ovale might increase your risk of stroke and migraines, but the evidence isn't clear.

Most people with patent foramen ovale don't know they have it, because it's usually a hidden condition that doesn't create signs or symptoms.

Symptoms in infants
In rare circumstances, an infant with patent foramen ovale might have bluish skin (cyanosis) when crying or straining, such as when passing stool. When an infant with patent foramen ovale has cyanosis, he or she usually has other heart defects.

In children with complex congenital heart defects, the patent foramen ovale may be necessary for survival, because it provides an essential, if imperfect, route for blood circulation. Babies with such conditions are blue because some oxygen-poor blood isn't sent to the lungs to take on oxygen. The amount of oxygen-poor blood bypassing the lungs depends on the size of the patent foramen ovale and various pressures within the heart.

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Patent foramen ovale

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
Your heart has four pumping chambers that circulate your blood:

• The right atrium, the upper right chamber, receives oxygen-poor blood from your body and pumps it into the right ventricle.
• The right ventricle, the lower right chamber, 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 left atrium, the upper left chamber, receives the oxygen-rich blood from the lungs and pumps it into the left ventricle.
• The left ventricle, the lower left chamber, pumps the oxygen-rich blood through a large vessel called the aorta and on to the rest of the body.

Baby's heart in the womb
Because a baby in the womb isn't breathing, the lungs aren't functioning yet. The heart needs to bypass the lungs and use a different route to circulate oxygen-rich blood to the 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 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 is generally greater in the left atrium than in the right atrium. This pressure forces the foramen ovale closed. In most people, the opening fuses shut, usually sometime within the first or second year of life.

In people with other congenital heart defects, the foramen often doesn't close. It's unclear why the opening never closes in other people, but genetic factors may play a role.

In most people patent foramen ovale doesn't cause complications. There's disagreement about whether patent foramen ovale is a cause or risk factor for some medical conditions. Possible complications may include:

Stroke
Stroke is an interruption or reduction of blood supply to a part of the brain. Some studies suggest patent foramen ovale may be a cause or risk factor of stroke, particularly when no other cause of a stroke can be identified.

We all release tiny clots of blood from veins in the lower abdomen and legs that eventually lodge in the lungs and dissolve there. The theory linking patent foramen ovale and stroke is that a clot may bypass the lungs by traveling through the patent foramen ovale. The clot could then travel to the brain and block an artery. While this is possible in theory, the evidence supporting this is inconclusive.

Stroke and atrial septal aneurysm
Atrial septal aneurysm, a congenital heart defect, is a bulging of the wall (septum) that separates the right atrium and left atrium. This defect — most often bulging into the right atrium — might cause blood clots that could lead to stroke. Having both patent foramen ovale and atrial septal aneurysm may increase the risk of stroke, but more research is needed.

Migraine with aura
Migraines with aura are very painful headaches accompanied by sensations such as shimmering spots, blurred vision and blind spots. There is some evidence of link between patent foramen ovale and migraine with aura. But how this might happen isn't clear.

In most cases, a patent foramen ovale is discovered during imaging tests to examine other heart conditions or to look for causes of stroke. A heart specialist (cardiologist) can detect patent foramen ovale with one of the following tests.

Echocardiogram
An echocardiogram shows the structure and function of your heart. The standard form of this test is called a transthoracic echocardiogram.

With this test, a technician spreads gel on your chest and then presses a device called a transducer against the skin over the heart. The transducer emits high-pitched sound waves and records the sound wave echoes as they reflect off internal structures in the heart. A computer converts the echoes into moving images on a monitor. Variations of this procedure may be used to identify patent foramen ovale:

• Color-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 patent foramen ovale, a color-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 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 patent foramen ovale, some bubbles will appear on the left side of the heart.

Transesophageal echocardiogram
This test uses a tiny transducer on a tube inserted down the esophagus, the part of the digestive tract that runs from the throat to the stomach. Because the esophagus lies close to the heart, having the transducer placed there provides a detailed image of the heart and blood flow through the heart. The use of a transesophageal echocardiogram makes it easier to see a patent foramen ovale by either color-flow Doppler or a saline contrast study.

Most people with patent foramen ovale don't need treatment. Though treatment is sometimes suggested, studies of patent foramen ovale treatments have produced inconclusive evidence.

Medications
Medications can be used to try to reduce the risk of blood clots crossing a patent foramen ovale. The benefit of aspirin and other blood thinners, such as warfarin (Coumadin), in treating patent foramen ovale isn't clear.

Most current studies suggest that warfarin isn't better than aspirin in reducing the chance of another stroke for people who've already had one. However, there may be another condition, such as irregular and chaotic heartbeats in the heart's upper chambers (atrial fibrillation), that indicates the need for warfarin.

Surgical and other procedures
Procedures to close patent foramen ovale include:

• Surgical repair. A surgeon can close the patent foramen ovale by opening up the heart and stitching shut the flap-like opening. This can sometimes be done with the use of "robotic" techniques and a very small incision.
• 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.

Reasons for closure
If 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 opening in the heart may be used in the following circumstances:

• If your child is undergoing surgery to correct a congenital heart defect and your child also has patent foramen ovale, the surgeon may close the opening when making other repairs to the heart.
• In adults having other types of heart surgery, a patent foramen ovale may be closed at the time of the operation.
• Closure of a patent foramen ovale may be done to treat low blood oxygen levels resulting from right-to-left blood flow across the patent foramen ovale.
• Although there's disagreement about whether treatment is needed, closure of the opening has been used to treat migraine and to prevent recurring stroke, particularly when no cause of a first stroke can be identified.

Recommendations of professional organizations
Professional organizations have made the following recommendations about patent foramen ovale closure to prevent stroke or treat migraine:

• American Heart Association/American Stroke Association (AHA/ASA). The AHA/ASA professional guidelines say there's insufficient evidence to support closure in people who have had one stroke. If medications to prevent a second stroke aren't successful, then the procedure may be considered.
• American Academy of Neurology (AAN). AAN professional guidelines say there's not enough evidence to support closing patent foramen ovale for preventing stroke.
• American Headache Society (AHS). The AHS doesn't recommend surgical closure of patent foramen ovale to treat migraines.

Clinical trials
Some professional organizations have encouraged doctors to talk to those with patent foramen ovale about participating in clinical trials addressing the many unanswered questions about patent foramen ovale, stroke and migraine. Your doctor may suggest this option to you and provide information about trials in your area.