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 percent 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 (the lungs actually do
dissolve tiny blood clots). If debris is present in the blood, such
as small blood clots, it now passes through the left atrium and can
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 percent has 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
percent 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)