Patent Foramen Ovale (PFO) - A Hole in Your
What is a Patent Foramen Ovale, or PFO?
Normally, blood enters the heart from the veins into the right atrum. From the right atrium the blood flows into the right ventricle and then to the lungs where it becomes oxygenated. The lungs also serve as a filter to trap any debris that is present in the blood and prevents it from going to the brain or other organs. The oxygenated blood then returns to the left atrium and into the left ventricle. Then the heart contracts and sends the blood back out into the body.
A patent foramen ovale, or PFO, is a small flap valve defect (kind of a hole) between the right and left atrium. Though everyone has this "hole" before they're born, it usually closes after birth. If it doesn't close, it causes a defect which works like a flap valve (see above), opening up when the patient creates more pressure inside their chest by coughing, sneezing, or straining at stool. This pressure may be enough to open the flap, allowing the blood to flow between the atria before it has been cleansed and oxygenated. If there is debris present in the blood it can bypass the lungs via the PFO and lodge in the brain, causing a stroke, or in the heart, causing a heart attack. This type of defect is transient, meaning it is present only under certain conditions.
The Role of PFO in Stroke
A PFO does not cause a stroke, but its presence may be a pathway for a stroke to occur by allowing blood to flow from the venous system to the arterial system without going through the lungs first. One of the important functions of the lungs, in addition to oxygen exchange, is to filter debris from the venous blood returning to the heart. If this debris gets into the arterial circulation, it can lodge in an artery serving the brain, heart, or other major organ causing an arterial embolization. When it lodges in the brain a stroke occurs.
What is a Patent Foramen Ovale, or PFO?
In patients for whom the patent foramen ovale can be demonstrated to open, the current method of treatment is blood thinners. These drugs, such as Coumadin (Warfarin), thin out the blood and hopefully reduce the risk of a clot returning to the right atrium from the venous circulation. However, the use of Coumadin does not close the PFO.
There are complications associated with the chronic use of blood thinners, such as ulcers, internal bleeding, cerebral bleeding, hematuria, and hemorrhoidal bleeding. Recently, many neurologists and cardiologists have recommended that PFO's be closed in such patients. Traditionally, PFO closure would involve open-heart surgery with its associated complications. In the past, special devices have been utilized through a catheter for closure of these PFO's with mixed results. However, in February of 2000, a device called "CardioSEAL®" was approved by the FDA for percutaneous, transcatheter (an approach through the skin with a catheter placed into a vein) closure of PFO's. For patients with the CardioSEAL® system, outcomes have been favorable. The recovery associated with the procedure is minimal and it is usually done on an outpatient basis.
How CardioSEAL Closes a PFO
CardioSEAL® is constructed of a metal framework shaped like an umbrella to which a polyester fabric is securely attached. CardioSEAL is comprised of two of these umbrellas, one for each side of the septum.
Using spring coils in the framework, CardioSEAL can be collapsed into a very small tube for insertion into the heart. Once inserted through the tube, CardioSEAL is opened, with an umbrella positioned on each side of the defect.
Once in position, CardioSEAL is released from the catheter, and tissue grows into and around the umbrellas as a result of the fabric.
CardioSEAL is approved in the USA for use in selected patients with PFO & stroke under the humanitarian device exemption (HDE) regulation.
Advantages of CardioSEAL
Many physicians believe that the primary advantage of CardioSEAL closure is that the patient will have a permanent seal to the defect, and will no longer be required to take long-term blood thinning medications. This means the risk of a recurrent stroke or TIA may be eliminated, at least in terms of the role the PFO played in a prior event.
By not having to take anticoagulants for the rest of their life, the patient can participate in those activities which they would have had to avoid if taking the blood thinners commonly prescribed for this condition.
Risks and Complications of Implants
As with all medical procedures, there are risks and potential complications associated with procedures used to deliver implants.
Patients may be allergic to the contrast dye used in the procedure.
There is a risk of embolic stroke from clots, venous debris, or air getting into the heart.
There may be bleeding or injury to the vein at the insertion site.
There are risks associated with the use of transesophogeal echo (sometimes used to help the doctor see the implant during the procedure).
The device itself may dislodge, making surgery necessary if the doctor cannot retrieve it.
The device itself may cause varying degrees of tissue reaction.
Over time, the implant framework could degrade, or fracture.
The patient may develop Endocarditis.
There is a risk that a clot may develop on the device itself.
All of these complications have been reported through the years from different types of septal implants.
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