Patent Foramen Ovale

Patent foramen ovale (PFO) is when you have a small flap or opening between the upper right and left chambers (atria) of your heart. Everyone has this opening, called a foramen ovale, before birth. In most people, this closes after birth. Patent foramen ovale occurs when the flap still exists after birth. “Patent” means “open.”

Most of the time, people with PFO don’t have symptoms and won’t need treatment. But some uncommon problems related to the presence of PFO include stroke and mini-stroke.

What does a foramen ovale do?

A fetus doesn’t use its lungs to get oxygen-rich blood. Instead, this blood comes from the mother’s placenta, delivered through the umbilical cord. A foramen ovale directs the oxygen-rich blood from the umbilical cord in a fetus’s right upper chamber (right atrium) to the left upper chamber (left atrium).

From there, the blood goes to the left side of the fetus’s heart and provides oxygen to fetus’ brain.

The foramen ovale normally closes after birth. This happens when the baby starts to breathe and blood starts to flow to the lungs to get oxygen. This blood then enters the left side of the baby’s heart before getting pumped to the rest of their body.

Who might have patent foramen ovale?

Anyone can have patent foramen ovale regardless of gender, ethnicity or race. PFO is frequently found in:

• Divers with decompression illness (air embolism), when air bubbles block your vein or artery due to an environmental pressure change.
• People who’ve had a stroke of unknown cause (cryptogenic stroke).

How common is patent foramen ovale?

Patent foramen ovale affects about 25% of people worldwide. PFO impacts about 30% to 40% of people who’ve had an unexplained stroke. This does not mean that everyone who has PFO will experience a stroke or mini-stroke.

How does patent foramen ovale affect my body?

Patent foramen ovale lets a small amount of blood flow between the flaps connecting your right and left atrium. Normally these flaps stop blood from flowing between them.

Usually, patent foramen ovale causes no problems. But PFO may let a blood clot travel from the right to the left side of your heart. Your heart could pump the clot into your body. If the clot reaches your brain, it could cut off the blood supply. This would cause an ischemic stroke. The clot may also damage your other organs, such as your kidneys or your heart.