Patent Foramen Ovale (PFO): A Common, Small Communication Within the Heart
What is a patent foramen ovale?
Before birth, a channel exists between the two upper chambers of the heart. This channel is called a foramen ovale. This allows oxygenated blood received from the mother to flow from the venous circulation (blood returning to the heart) to the arterial circulation (blood flowing from the heart to the body). Following birth, the lungs unfold and pressures in the circulatory system change, usually causing the channel to close. However, in about 25% of people, this channel does not close. In this case, the foramen ovale is said to remain patent, or open. People with this open channel are said to have a patent foramen ovale (PFO).
Why is a PFO important?
In the vast majority of cases, a person with a PFO experiences no symptoms or events as a result of it. Many PFO’s close naturally as a person grows older. Indeed, an autopsy study found that the prevalence of PFO declines as age increases. However, a very small percentage of people with a PFO experience stroke, or other neurological events.
How is stroke related to PFO?
Stroke is the third leading cause of death worldwide. A stroke is a vascular injury to the brain that causes a loss of neurological function. Most strokes are caused by a narrowing or clot in the arteries leading to the brain. However, out of the more than 500,000 strokes each year, up to 40% have no identifiable cause, even after extensive testing. These are called cryptogenic strokes.
In patients with PFO, it is possible for blood clots to pass through the PFO from the venous circulation to the arterial circulation. This is called a paradoxical embolism. In the arterial circulation, clots can travel to the brain, coronary arteries of the heart, or any other artery in the body. The brain needs large amounts of oxygen to function. If the clot cuts off the blood supply to the brain, it can be damaged by oxygen starvation. This is called an embolic stroke. PFO can also lead to a transient ischemic attack (TIA), in which a person has stroke-like symptoms that resolve within 24 hours with no lasting damage. In the same fashion, if the clot travels to the heart’s arteries it can stop blood supply to the heart and cause a heart attack.
How is a PFO detected?
A PFO is usually detected via a transthoracic or transesophageal echocardiography (TEE). TEE offers the best views by using a small ultrasound wand, which is moved down the esophagus (the tube that connects the throat and the stomach) in order to look at the heart from behind. Patients: Click the following link for more specific information about the TEE procedure at MHI.
What can be done to treat a PFO?
Depending on the size of the PFO and presence of other cardiac or blood clotting abnormalities, there are several options for treatment of problems resulting from a PFO. Many patients and their physicians choose to treat the problem with medical therapy through the use of anticoagulant and/or anti-platelet drugs. This reduces the formation of blood clots, reducing the risk of stroke and heart attack. However, patients on this therapeutic regimen may be restricted in some of their daily activities.
In other patients, drug therapy may not be effective or it may be necessary to close their PFO permanently. PFO closure can be done through open-heart surgery or through percutaneous PFO closure. A cardiologist can know which patients are better suited for each procedure.
Surgical PFO closure
Surgical PFO closure has long been considered the gold standard for PFO closure and has been proven to be safe and effective. The chest is opened, the patient is hooked up to the heart-lung machine, and the PFO is repaired by directly suturing the defect or through the use of patch material. Patients usually remain in the hospital for four to seven days.
Percutaneous PFO closure
Percutaneous (through the skin) PFO closure is done by inserting a tube (catheter) into the femoral vein in the inner thigh and passing it up into the heart. An implant device is then deployed out of the catheter and is positioned through the PFO. This closes the PFO and tissue will begin to grow over the device. This procedure offers important advantages over surgical closure including avoiding the use of the heart-lung machine, avoiding the need for direct suturing or cutting of the heart, and shorter hospitalization.
The procedure usually takes less than two hours. The physician is guided by multiple imaging techniques, including fluoroscopic (x-ray) and echocardiographic (ultrasound) imaging. Patients may or may not be awake during this procedure. Most patients are discharged between 24 and 48 hours after this procedure and remain on anti-thrombotic drug therapy, anticoagulant drug therapy, or both for a period of time. Follow-up requirements include a physician visit with a TEE at six months to look at the device and determine if optimal closure was achieved. Patients also remain on antibiotics for a period of six months after the procedure.
Percutaneous PFO closure at Abbott Northwestern Hospital
The first percutaneous closure of an interatrial communication was performed in 1976. Through the years, there have been many improvements to the closure devices and there are now several that have been approved by the FDA. At Abbott Northwestern Hospital and the Minneapolis Heart Institute, over 200 percutaneous PFO closures have been performed. Independent clinical trials in Europe and Canada have found the success rate for implantation to be between 95 and 100 percent. Similarly, procedures at Minneapolis Heart Institute/Abbott Northwestern Hospital have produced excellent results.
In a small number of patients, a slight residual shunt is still detected. Usually the blood flow through this shunt is altered substantially compared to the original PFO such that the device can act like a filter to reduce the chance of a blood clot travelling across from the right atrium to the left atrium.
Prospective studies are needed to compare the therapeutic value of percutaneous closure with pharmacologic and surgical alternatives. Only the physician who is treating you will be able to determine if this is the right procedure for you. Additionally, some of these residual defects close over time.
To learn more about our interventional cardiologists who specialize in PFO closure, click on a physician name below.
Ivan Chavez, MD
Michael Mooney, MD
Anil Poulose, MD
Related Links on this Web site:
MHI Programs & Services
Physicians:
How to refer patients to MHI
On Other Web sites:
American Heart Association
AGA Medical Corporation, A Family of Amplatzer Occlusion Devices
NMT Medical Device Company
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