What is the Foramen Ovale?

The foramen ovale (foh-RAY-mun oh-VAY-lee) is a small hole located in the septum, which is the wall between the two upper chambers of the heart (atria).

Before a baby is born, it does not use its lungs to get blood rich in oxygen. Instead, this blood comes from the mother’s placenta and is delivered through the umbilical cord. The foramen ovale makes it possible for the blood to go from the veins to the right side of the fetus’ heart, and then directly to the left side of the heart.

The foramen ovale normally closes as blood pressure rises in the left side of the heart after birth. Once it is closed, the blood flows to the lungs to get oxygen before it enters the left side of the heart and gets pumped to the rest of the body.

What is a Patent Foramen Ovale?

A patent foramen ovale (PFO) means the foramen ovale did not close properly at birth, so there is still an opening in the septum. In most cases, the PFO does not stay open at all times. Instead, it’s more like a flap that opens when there is higher pressure than normal in the chambers on the right side of the heart. Situations that can cause greater pressure include straining during bowel movements, coughing and sneezing. When the pressure gets high enough, blood may move from the right atrium to the left atrium.

The condition affects about 25% of Americans, but many do not know they have the condition.

What are the Risks and Symptoms of Patent Foramen Ovale?

Most patients with a PFO do not have any symptoms. However, the condition may play a role in migraine headaches and it increases the risk of stroke, transient ischemic attack and heart attack.

Migraine headaches

Patients with a PFO may have migraine headaches with aura. Although the migraines stop for some patients who have the PFO closed, more studies are needed to determine if closure provides relief.

Stroke, transient ischemic attack and heart attack

Patent Foramen Ovale increases the risk of transient ischemic attack (TIA), stroke and heart attack. This is because when pressure increases in the chambers on the right side of the heart, it is possible for a blood clot or solid particles in the blood to move from the right side of the heart to the left through the open PFO, and travel to the brain (which causes a TIA or stroke) or a coronary artery (which causes a heart attack). A TIA is caused by a temporary lack of blood flow to the brain. The symptoms are the same as a stroke, but last less than 24 hours.

Many times, a TIA or stroke is the first sign of a PFO. Patients younger than Age 55 who have a stroke without a known cause (cryptogenic stroke) are more likely to have a PFO. These patients are also more likely to have a deep vein thrombosis (DVT).

Patients with a PFO may also have an atrial septal aneurysm. This condition means the top portion of the septum is bulging into one or both of the atria (top chambers of the heart).

Symptoms of a Stroke and Transient Ischemic Attack (TIA)

  • Sudden weakness or numbness in the face, arm or leg on one side of the body
  • Sudden blurred vision or trouble seeing out of one or both eyes
  • Can’t speak or trouble talking or understanding what others are saying
  • Dizziness, loss of balance, unstable walking
  • Passing out for a short time
  • Suddenly can’t move part of the body (paralysis)

Last reviewed by a Cleveland Clinic medical professional on 05/03/2019.


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  • American Heart Association. About Congenital Heart Defects Accessed 3/12/2015.
  • Centers for Disease Control and Prevention. Facts about Congenital Heart Defects Accessed 3/12/2015.
  • National Heart, Lung, and Blood Institute. What are Congenital Heart Defects? Accessed 3/12/2015.
  • Hirsh JC, Devaney EJ, Ohye RG, Bove EL. Chapter 19B. The Heart: II. Congenital Heart Disease. In: Doherty GM. eds. CURRENT Diagnosis & Treatment: Surgery, 13e. New York, NY: McGraw-Hill; 2010.

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