Patent Foramen Ovale (PFO)

A patent foramen ovale is a small, flap-like opening in the dividing wall (septum) between the upper two chambers of the heart ¨C the left atrium and the right atrium. In the womb, all babies have a PFO. This is because a baby does not use its own lungs to filter and oxygenate its blood. Instead, it receives oxygen-rich blood from its mother via the umbilical cord. This blood has been filtered and oxygenated by the mother¡¯s lungs. The PFO allows this blood to be sent directly to the brain, which has a high requirement for oxygen-rich blood during development.

In most people, the two flap-like sections of septum which form the foramen ovale fuse together after birth to form a solid dividing wall between the right and left atria.  However, in approximately 15-20% babies, the foramen doesn¡¯t fuse together and remains open or ¡°patent¡±.  This opening makes it possible in certain circumstances for blood to cross from the right atrium to the left atrium¡ªthis is called a right-to-left shunt.

Heart showing how oxygen rich blood flows to the fetus during late gestation. The foramen ovale normally fuses within a short time after birth.

The two flap-like sections of a patent foramen ovale overlap and usually prevent blood from crossing from the right side to the left side of the heart because the pressure in the right atrium is typically lower than in the left atrium. Under certain circumstances the pressure inside the right atrium increases to such an extent that the flaps may separate. This allows blood which has not been filtered and oxygenated by the lungs to "shunt" or cross the PFO from the right atrium to the left atrium.  For a great majority of the people with this condition, this shunting is very small and does not cause problems.

However, if the blood that crosses the PFO contains debris or a clot, it can enter the arteries which supply the brain and cause a stroke or transient ischemic attack(TIA).

How can a PFO be treated?

There are different treatment methods available to help prevent stroke or TIA in patients who have a PFO.

?Medication: Traditionally, stroke or TIA patients who have a PFO are given medication to thin the blood, or to make it less ¡°sticky¡±, and prevent the formation of clots which could lead to stroke.  Typically, these drugs include warfarin and aspirin.

?Surgical closure: Until the 1980s, open heart surgery was the only alternative to medication.  Today, these procedures are infrequently performed because major surgery is involved and less invasive methods available.

?Non-surgical closure: Nowadays, there is a non-surgical method to treat PFO using a device called a septal repair implant.