PFO, or patent foramen ovale
, is a heart
valve in humans
that usually closes off at or shortly after birth. The valve’s function is to let the circulating blood bypass the lungs, which the body doesn't rely on until a newborn starts breathing air. Tissue flaps in the heart usually fuse and close the hole, but complete closure never occurs in about 20 percent of the U.S. population. According to Dr. Thompson, division chief of pediatric cardiology at Inova Fairfax Hospital in Merrifield, "Approximately twice as many people with migraine
headaches have PFO compared to the general population.
Relation to migraines
Problems occur when the valve is not completely fused and allows unfiltered blood returning to the heart from other parts of the body to bypass the lungs. Normally, the blood picks up oxygen to circulate directly to organs, including the brain Without the needed oxygen, the proper amount of oxygen does not reach the brain. Cardiologist Dr. Pranav Loyalka, of the Texas Heart Institute, explained it as a “trap door” that “opens when the person strains, such as during a cough or sneeze.” Air bubbles and dissolved chemicals can also slip through the one-way shunt rather than ride to the lungs, where they'd be exhaled or broken down. Wilmhurst, a cardiologist at the Royal Shrewsbury Hospital in England, speculated that the PFO permits a substance that would be filtered in the lungs to get to the brain." He and some other researchers suspect the peptide serotonin, which is neurologically active and doesn't usually circulate in blood heading from the heart to the brain.
A major effect of the opening is that occasionally blood clots escape through the valve and can trigger strokes. According to the research of Lois Collins, a writer for the Deseret News, half a million cryptogenic strokes worldwide every year are directly attributed to PFOs. Because of the association of strokes and PFO, many stroke patients commonly undergo a procedure to test for an opening of the PFO. Stroke patients who are found to have the opening often undergo surgery to close the PFO valve and prevent the possibility of future strokes. Patients have related a disappearance of their migraines to their surgery.
PFO closure has not only been used for stroke patients. A cardiologist of Royal Shrewsbury Hospital in England found that scuba divers with PFOs were unusually susceptible to decompression sickness, a disorder that can occur when bubbles of nitrogen form in the blood and don't get expelled by the lungs. After closing the heart defects of professional divers, several also reported the disappearance of their migraines. Roman Szatajzel, a neurologist at the University Hospitals of Geneva, performed a PFO valve surgery on a stroke patient. As a result of the surgery, the patient reported a disappearance of her migraines. Even though the migraines disappeared after surgery, not all migraines are associated with an opening in the PFO valve. As related by the Journal of Head & Face Pain, “the relationship between migraine and patent foramen ovale may be stronger in patients suffering from migraine with aura compared to patients with common migraine. Because of the many causes of migraines, studies are now beginning to take place to determine the relation between migraines and an opening of the PFO valve.
The article “Against the Migraine” relates two instances where relief has been found for migraines from PFO closure:
In the February 2005 issue of Journal of the American College of Cardiology, Reisman, Jesurum, and their Seattle colleagues describe the results of 162 PFO closures in people with a history of stroke or related vascular blockages. Migraines had affected 57 of the patients before the operations. In more than half the patients who had been troubled with migraines, the headaches disappeared after the operation. Another 14 percent of patients reported a reduction by at least half in migraine frequency.
At a meeting of the American Heart Association in New Orleans last November, Sherman G. Sorensen of the Utah Heart Clinic in Salt Lake City and his colleagues reported on 121 stroke patients who'd had a PFO closed. Of the 69 people who'd had migraine headaches before the procedure, 30 had no headaches afterward and 27 reported partial relief from migraine symptoms. Findings continue to provide evidence that many migraines are associated with the opening of the PFO valve. Even with the many causes for headaches, at least half of patients who undergo the PFO closure procedure have fewer migraines. PFO closure continues to provide evidence of migraine relief.
The most common treatment for headaches is medication, but for many people, medications do not help migraines subside or cease and cause unwanted side effects. Mark Reisman, cardiologist of Seattle's Swedish Medical Center explained an advantage to non medication migraine relief. He said, “In contrast to drugs, PFO closure appears highly effective against migraines and usually has no side effects”. Because PFO closure continues to prove successful, new devices are being produced to make the heart surgery process easier and less severe.
Coherex FlatStent Closure System
From Coherex Medical Inc. of Salt Lake City, a device called the Coherex FlatStent PFO Closure System is being tested as a new product for PFO closure. This device is first being studied by a European clinical study in Frankfurt, Germany. If this study proves to be a success, the device will begin to undergo FDA approval. The Coherex Closure System is an alternative to the typical method of repairing a PFO by placing a disk on each side of the defect and clamping them together to form a solid wall. The typical method doesn't always work particularly well with PFOs because the lengths, widths and dimensions of the defect are always different. The Coherex device is small and looks delicate, although it's not. One of its unique features is that it's deployed inside the tunnel of the PFO, so it closes the defect from within. Because of its construction, it adapts to a PFO's individual shape in terms of length and width, thus avoiding the typical problem with PFO closure. Besides pulling the opening closed, it has a sponge polymer that encourages tissue to grow into it and integrate it into the heart's structure.
Another closure system is in use right now called CardioSEAL. This device looks like a small umbrella made out of Dacron fabric and folded into a special catheter. This catheter is inserted into a vein in the leg like the Coherex device. In order to close the PFO valve, each umbrella opens up and the device is pushed out of the catheter. The device is absorbed into the heart as the heart tissues grow over the implant in time. Figure 2 below shows the catheter and its relation to the size of a penny. You can see the double umbrellas that open up on either side of the vein.
Another device for PFO Closure is called the Amplatzer ASD septal occlude device. Two wire mesh discs filled with polyester fabric are folded into a catheter and inserted into a vein in the leg to advance to the heart. In the same process as the CardioSEAL device, the device is pushed out from the catheter and the discs of the device sit on each side of the hole. The tissue grows over the device over time. Figure 3 below shows the Amplatzer ASD device.
University of Washington Medical Center tests the effectiveness of PFO closure in eliminating migraines in a clinical trial called the Premium Trial. All patients must meet certain criteria to qualify for the study including a diary that recounts the severity and frequency of migraines and undergoing tests to eliminate other medical reasons for migraines. A random selection process is then used to determine which patients have their PFO repaired and which ones do not. After a year, the patients will find out if they had the actual procedure and physicians will be able to determine if the process really worked.
The surgery is not performed by cutting open the chest and working on the heart. Instead, a catheter is pushed up to the hole in the heart after it is inserted in a vein in the leg. In order to keep the study blind, all patients are blindfolded and wear headphones while being mildly sedated. All patients receive a catheter in the leg, but not all catheters are pushed up to the heart. “The device looks like a double umbrella that is opened up to cover each side of the hole to close it. Heart tissue grows over the implant over time. In some cases, the implant is absorbed and replaced with the patient's heart tissue”. If this process works and migraines continue to improve with PFO closure, this will be a great improvement to heart surgery normally done through the chest.
ESCAPE migraine trial
One clinical trial being undertaken began in October 2007 called the ESCAPE Migraine trial to test the relation to PFO closure to migraine relief. Feldman, along with Dr. Susan Rubin, are co-principal investigators of the trial. “The clinical trial expects to enroll 500 patients in the U.S. who have not found relief from migraines with preventive medicine, have experienced unwanted side effects from drug therapy or have been advised by a doctor against medications due to another condition”. This trial will use the closure system called the Premere PFO Closure System that uses the catheter system in the leg to go to the heart. This closure system was designed by St. Jude Medical but is only available for this clinical trial because it has not been approved by the Food and Drug Administration.
The procedure involves two-thirds of the patients who will have their PFO closed, while the other third will have a tube placed in their heart to measure the size of their PFO. The risk of migraine is related to the size of the PFO. Patients will not know until the end of the trial if they were assigned to receive PFO closure. Once the trial is complete, trial participants will meet with a cardiologist for a heart evaluation and a neurologist to evaluate and monitor their migraines after intervention. They will be asked to maintain an electronic journal of their migraines for one year. The apparent relation between an opening of the PFO valve and migraines will further receive validation through this study.
The relation between migraines and the closure of the PFO valve is still undergoing a lot of research. Studies so far appear to show that there is a relation, but that migraines are not always associated with the heart defect. Specific types of migraines may caused by an opening of the PFO valve, but research is still being done to find out the specific relation of certain causes to PFO. Many devices are being studied to improve the PFO Closure process and for now, it looks like many people will find relief from migraines through closure of the PFO.