Patent Foramen Ovale (PFO)

What is a patent foramen ovale?

The foramen ovale is a small hole between the 2 upper chambers of a baby's heart before birth. The hole is between the left atrium and the right atrium. Normally the hole closes after birth.

After birth a baby's blood gets oxygen from the lungs, but before birth, oxygen comes from the placenta. The foramen ovale allows oxygenated blood to bypass the lungs and get pumped to the rest of the body. After birth, however, this opening can cause problems because the blood now needs to go the lungs to pick up more oxygen. Without going to the lungs, the blood does not get enough oxygen.

There is a flap on the wall that separates the left atrium from the right atrium (the atrial septum). Before birth, the pressure on the right side is greater than on the left side, and the flap stays open. After birth, the pressure on the left side is greater than on the right side, so the flap is pushed against the septum and closes the hole. Over the first few months of life, the flap gets sealed to the septum.

Sometimes the flap does not seal. When this happens, the foramen ovale may open if the pressure on the right side of the heart is the same as the pressure on the left side of the heart. When the flap stays open, the foramen ovale is called a patent foramen ovale (PFO).

How does it occur?

It is not known why the flap seals in some people but not in others.

What are the symptoms?

A patent foramen ovale can cause 2 kinds of problems.

• If you develop a blood clot in a vein in your leg, the clot can break off and float to the left side of the heart and then to the brain, where it can cause a stroke. It may also damage other organs in the body.
• If you have pulmonary hypertension, which is a problem caused by abnormal blood vessels in the lung, the pressure in the right side of the heart may become much higher than the left side. This will cause a lot of blood to flow from the right side to the left side before the blood can pick up oxygen. This causes the overall oxygen level in the blood to drop and will make your shortness of breath much worse.

How is it diagnosed?

The best test for diagnosing a patent foramen ovale is a transesophageal echocardiogram. This tests uses sound waves and a computer to look at your heart. A small amount of fluid is injected into an IV during the echocardiogram. The fluid contains tiny bubbles that are detected by the echocardiogram. This helps your healthcare provider see if blood is flowing abnormally from the right side to the left side of the heart.

How is it treated?

If the PFO does not cause symptoms, no treatment may be needed. Scuba divers may be an exception this rule. During decompression after diving, small nitrogen bubbles may form in the blood. These bubbles may act like blood clots and cause small strokes or damage to other organs. Talk with your healthcare provider if you are a diver.

If PFO causes symptoms, treatment options are anticoagulants (blood thinners), surgery to close the hole, or placement of a tiny umbrella device to cover the hole. This umbrella can be placed without surgery through a catheter (thin tube).

How can I help take care of myself?

If you have been diagnosed with a PFO, you will need regular checkups. Call your healthcare provider if:

• You suddenly have more trouble breathing.
• You wake up at night short of breath.
• Your heartbeat is irregular.