The septum is the muscular wall separating the heart into the left and right sides.
The atrial septum is the wall separating the atria (the two upper chambers).
The ventricular septum is the wall separating the ventricles (the two lower chambers).
Patent Foramen Ovale (PFO)
The foramen ovale is a small hole located in atrial septum that is used during fetal circulation to speed up the travel of blood through the heart. When in the womb,a baby does not use it’s own lungs for oxygen-rich blood, it relies on the mother to provide oxygen rich blood from the placenta through the umbilical cord to the fetus. Therefore, blood can travel from the veins to the right side of the baby’s heart and cross to the left side of the heart through the foramen ovale and skip the trip to the baby’s lungs.
Normally the foramen ovale closes at birth when increased blood pressure on the left side of the heart forces the opening to close.
If the atrial septum does not close properly, it is called a patent foramen ovale. This type of defect generally works like a flap valve, only opening during certain conditions when there is more pressure inside the chest. This increased pressure occurs when people strain while having a bowel movement, cough, or sneeze.
If the pressure is great enough, blood may travel from the right atrium to the left atrium. If there is a clot or particles in the blood traveling in the right side of the heart, it can cross the PFO, enter the left atrium, and travel out of the heart and to the brain (causing a stroke ) or into a coronary artery (causing a heart attack ).
How Common is Patent Foramen Ovale?
The prevalence of PFO is about 25 percent in the general population. In patients who have stroke of unknown cause (cryptogenic stroke), the prevalence of PFO increases to about 40 percent. This is especially true in patients who have had a stroke at age less than 55 years. ( http://stroke.ahajournals.org/cgi/content/full/37/2/577 )
A PFO can be associated with atrial septal aneurysm, which is characterized by excessive mobility of the atrial septum.
Symptoms of PFO
Most patients do not have any symptoms with PFO.
Stroke and PFO: About 40 percent of patients who have an ischemic stroke have no known cause (called cryptogenic stroke). PFO is present and associated with an increase in stroke in about 40 percent of cases. The most common symptoms of stroke are:
weakness or numbness of the face, arm or leg on one side of the body
loss of vision or dimming (like a curtain falling) in one or both eyes
loss of speech, difficulty talking or understanding what others are saying sudden, severe headache with no known cause
loss of balance, unstable walking, usually combined with another symptom
Migraine headache and PFO: Migraine headaches are more common in patients with PFO. While it seems as though closure of PFO results in improvement of migraine symptoms, larger studies are needed to confirm this finding.
Diagnosis of PFO
Patent Foramen Ovale can be detected by echocardiogram. In some cases the patient is asked to cough or perform the Valsalva maneuver to increase pressure in the right atrium. This can increase the flow of blood from the right to left atrium. Transesophageal echo, can provide a closer and more detailed view of the PFO.
Treatment for Patent Foramen Ovale (PFO)
People with PFO do not need any treatment if there is no associated problems, such as a stroke. Patients who have had a stroke or transient ischemic attack (TIA) may be placed on some type of blood thinner medication, such as aspirin, plavix (clopidogrel), or coumadin (warfarin) to prevent recurrent stroke.
Non-surgical treatment: Cardiac implant
In some patients a cardiologist and a neurologist may reccomend closure of PFO. Most frequently, percutaneous rather than surgical closure is preferred. As part of the procedure, you will first undergo a cardiac catheterization. During this test, catheters (hollow, flexible, tube) will be inserted into the veins in your groins and advanced to your heart. A balloon may be placed across the opening to determine the size and location of the hole in your heart. Measurements are taken of the pressure inside your heart chambers. A tiny catheter with an echo transducer is placed in the heart for imaging.
If the cardiac catheterization shows your PFO is an appropriate size and in an appropriate location for closure with this device, the cardiologist will position the device to close the hole.
Two closure devices
Currently there are no specially designed devices for PFO closure that is approved by the FDA. In patients that closure is indicated, devices that are approved for other heart defects are used.
CardioSEAL® device Photo used with permission from NMT Medical *
The CardioSEAL® device is a small double umbrella arms attached to Dacron fabric. It is folded into a special catheter, similar to the catheter used during your catheterization. The special catheter is inserted into a vein in the leg and advanced into the heart and through the hole. The device is slowly pushed out of the special catheter allowing each umbrella to open up and cover each side of the hole (like a sandwich) and close it. When the device is in proper position, it is released from the special catheter. Over time, heart tissue grows over the implant, becoming part of the heart.