Patent Foramen Ovale (PFO)

A human fetus naturally has a hole in the wall (septum) between the left atrium and the right atrium (the two upper chambers of the heart). This hole is called the patent foramen ovale or PFO. The PFO allows blood to circulate without going to the fetus’ lungs, which won’t begin working until birth. After birth, when the baby’s lungs are working, the hole typically closes because it is no longer needed.

About 25 percent of humans have a hole that didn’t close completely, which allows blood to leak from the right atrium to the left atrium, rather than going to the lungs first. Usually, this isn’t a problem and individuals can live normal lives with an unclosed PFO.

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PFO Symptoms and Risk

The only time an open PFO becomes a problem is if a tiny blood clot moves through the PFO and out into your body — and possibly your brain. Very small blood clots frequently travel through your blood back to your heart and lungs. Normally, however, your lungs filter out these tiny blood clots. A PFO that has not fully closed, however, creates a “side door,” which could allow a tiny blood clot to escape that filtering process. Even a tiny blood clot in the brain can cause a stroke.

In fact, some individuals never know they have a PFO until it is discovered by an echocardiogram (a test that uses ultrasound to create an image of the heart) for another medical condition or they have a stroke.

If you have a stroke with no known cause (cryptogenic stroke), your primary-care or a stroke specialist (neurologist) may order an echocardiogram to determine if you have an open PFO. If you do, your doctor may refer you to the Structural Heart and Valve Disease Program at the Swedish Heart & Vascular Institute (SHVI) for further evaluation and treatment.

Closing a PFO

The Structural Heart and Valve Disease team will use advanced imaging to confirm the diagnosis and determine the best treatment option.

If you have an open PFO and you’ve experienced a stroke without a known cause, closing the PFO may decrease your risk for a second stroke. The Structural Heart and Valve Disease team offers a catheter-based procedure (medical procedures that use a catheter to deliver instruments and devices that are used to correct a medical condition) to close a PFO.

Heart specialists at Swedish were pioneers in the procedure to close a PFO. During this procedure, you will be under conscious (twilight) sedation. Using a local anesthetic, your cardiologist will make a small incision in your groin and then thread a catheter through a vein and up to your heart and the area where the hole is located. Your doctor will then use the catheter to deliver the closure device. Over time, your own tissue will grow over the device, making it permanent.

Before, during and after the procedure, your cardiologist will rely on advanced imaging to determine the location and size of the opening, as well as proper placement of the device.

The closure procedure takes about one hour. Most patients remain overnight in the hospital after a PFO closure procedure.

If you have had a stroke with no known cause, talk with your primary-care doctor, cardiologist or neurologist to see if you have an open PFO and whether closure of the PFO might be an option for you.


Patent foramen ovale closure device.