Patent Foramen Ovale (PFO)

What is a PFO?
A patent foramen ovale (PFO) is a defect in the septum (wall) between the two upper (atrial) chambers of the heart. Specifically, the defect is an incomplete closure of the atrial septum that results in the creation of a flap or a valve-like opening in the atrial septal wall (see illustration). A PFO is frequent in everyone before birth but seals shut in about 80% of people.

When a person with this defect creates pressure inside his or her chest - such as when coughing, sneezing, or straining during a bowel movement - the flap can open, and blood can flow in either direction directly between the right and left atrium. When blood moves directly from the right atrium to the left atrium, this blood bypasses the filtering system of the lungs. If debris is present in the blood, such as small blood clots, it can pass through the left atrium and lodge in the brain, causing a stroke, or another organ, such as the heart, eyes, or kidneys.

What are the symptoms of a PFO?
PFOs are not uncommon and usually cause no symptoms at all. One in five people have a PFO but less than 1% have a stroke or other cause to have the PFO closed.

What causes a PFO?
A PFO is congenital, meaning it is a defect that is inborn or exists at birth. Stated another way, the defect is an abnormality, not a disease. The septum between the two atrium of the heart developed normally before birth but the flap did not seal completely after birth.

Heart defects in general. Sometimes a viral infection can cause heart defects to develop, other causes include genetic factors, certain other medical conditions (Down’s syndrome, for example), some prescription and nonprescription drugs, but 95% of the time a cause cannot be identified.

How is a PFO diagnosed?
Frequently a PFO is not diagnosed until a child or adult with this defect has a transient ischemic attack (TIA) (symptoms of a stroke that last for less than 24 hours), or a stroke. Symptoms of a TIA or stroke include any of the following:

• Sudden numbness or weakness in the face, arm or leg (especially on one side of the body)
• Difficulty speaking or understanding words or simple sentences
• Sudden blurred vision or decreased vision in one or both eyes
• Difficulty swallowing
• Dizziness, loss of balance or coordination
• Brief loss of consciousness
• Sudden inability to move part of the body (paralysis)

A PFO can only be detected by a specialized test. It does not cause a heart murmur. If a PFO is suspected, your doctor will order tests that can include:

• electrocardiogram (ECG or EKG) - a test that records the electrical changes that occur during a heartbeat; reveals abnormal heart rhythms (arrhythmias) and detects heart muscle stress
• chest X-ray - a test to show the size and shape of the heart and lungs
• echocardiogram - a test that uses sound waves to create a moving picture of the heart’s internal structures. 
• doppler ultrasound - a test that uses sound waves to measure blood flow; often combined with echocardiogram to evaluate both the internal structure of the heart and blood flow across the heart’s valves
• transesophageal echocardiography - an ultrasound test used to visualize the heart and defect, where an imaging probe with a camera is placed into the esophagus
• cardiac magnetic resonance imaging (MRI) - a test that uses three-dimensional imaging to reveal how blood flows through the heart and how the heart is working
• cardiac catheterization - a procedure that involves inserting a thin tube (a catheter) into a vein or artery and passing it into the heart to sample the level of oxygen, measure pressure changes, and make x-ray movies of the heart and its internal structures. 
• angiography - a dye-enhanced x-ray of the heart’s internal structures

How are PFOs treated?
If you or your child is diagnosed with a PFO, your primary care doctor will recommend that you meet with a congenital heart specialist (a doctor who has the training and equipment to determine the heart problem) who will order the necessary special tests, medical care and follow-up checkups. A careful assessment of the patient’s stroke (if he or she has already experienced one) by a neurologist will first need to be done to determine the best course of action for the PFO.

The usual care for a patient who has had a stroke is the use of blood-thinning medications, such as aspirin or the prescription drugs warfarin (Coumadin) or clopidrogrel (Plavix). These drugs keep the blood cells from sticking together, reducing the risk of blood clot development that could lead to new TIAs or stroke.

However, there are risks and inconveniences associated with the long-term use of blood-thinning medications including:

• Development of ulcers
• Internal bleeding
• Bleeding in the brain
• Blood in the urine
• Bleeding in the rectal tissue
• The need to avoid activities that could result in injury, which could trigger internal or external bleeding

An alternative for patients unable to take blood-thinning drugs or those who have a second stroke while on blood thinning drugs is nonsurgical (catheter based) closure of the hole. To learn more about this procedure, see the document, "How is a PFO closed using a catheter-based procedure."