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A patent foramen ovale is a small, flap-like opening in the dividing wall (septum) between the upper two chambers of the heart – 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%, 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—this is called a right-to-left shunt.

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).

Valsalva maneuver occurs when a person exhales with a closed windpipe, exerting pressure on PFO. Often associated with straining, such as lifting, bowel movement or childbirth.

How can a PFO be treated? (back to top)

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. (back to top)
	What is involved in the non-surgical PFO closure procedure? Transcatheter PFO Closure is performed in the Cardiac Catheterization Laboratory by a physician. The physician will gain access to the heart through a needle puncture to a major vein in the groin or internal jugular vein. Various catheters will be advanced from the groin or neck into the heart. A test involving moving pictures of the heart, called an angiogram, will be taken to better visualize the heart and the hole (PFO). The physician may use a special ultrasound device, called TransEsophageal Echocardiography (TEE) which uses a probe into the esophagus, or Intra Cardiac Echocardiography (ICE) which uses a probe that is administered through the femoral vein thus avoiding a probe being put down into the esophagus. Once the defect size has been determined, the appropriate size implant is placed into a special catheter. The catheter is then advanced to the site of the defect and deployed so that part of it sits on each side of the defect. The catheter is removed and the procedure completed. (back to top)
STARFlex^® Septal Repair Implant in place closing a PFO