Stroke and PFO
Stroke is the third leading cause of death in the United States. One million people suffer from stroke each year. Stroke is the major cause of disability in the United States. There are 5 million survivors of stroke in this country. Stroke is not rare in young people under 50 years of age accounting for 5% of all strokes. Until recently, 40% of all strokes were of unknown cause. We now know that most of these unexplained strokes are caused by a PFO.
What is a PFO? (Patent Foramen Ovale)
During formation of the heart in the fetus, two pieces of the wall grow to overlap each other to divide the upper chambers (atria) of the heart into right and left chambers. Before birth, the lower divider acts as a flap or tunnel which allows blood to flow from the right side of the heart to the left side. This blood flow contains oxygen from the mother’s placenta. After birth, right to left blood flow is no longer needed. The two dividers of the right and left atria fuse to form a solid wall (septum). The septum is fused in 90% of people by 18 months of age. However, the dividers which form the septum do not fuse in 10% of people leaving a flap or tunnel which may open and close as right heart pressure changes. This opening (flap or tunnel) is the Patent Foramen Ovale or PFO.
Why PFO Cause Strokes
In the normal adult heart, the right and left sides are completely separated. Blood from the body enters the right atrium and flows to the lungs. Filtered blood from the lungs carries oxygen and is pumped to the brain and organs of the body. With a PFO present, blood from the body can bypass the lungs and travel to the left side of the heart. In the normal heart (no PFO), a blood clot from the body would be stopped in the lungs. But if a clot crosses the PFO, it can go to the brain causing a stroke.
Where do blood clots come from to cause stroke in patients with a PFO? Blood clots may form in the veins in the legs, break lose, and travel with blood flow to the heart. These clots may pass through the PFO causing a stroke. Or, blood trapped within the PFO flap or tunnel for a period of time may clot. When increased pressure in the right heart opens the flap of the PFO, the clot may dislodge and travel to the left side of the heart and then to the brain.
How are PFO diagnosed?
Heart disorders are the most common cause of stroke. TransThoracic Echocardiography ( or TTE) is a noninvasive, ultrasound test which evaluates heart structures. Microscopic bubbles injected into a vein show a PFO when they cross to the left side. TTE is about 60% reliable in finding a PFO.
Although surface echo (or TTE) can define most heart structures, the atrial
septum (the site of the PFO) is hard to see. TransEsophageal Echo (or TEE) uses a special ultrasound probe which is placed in the esophagus after giving sedation. The atrial septum and PFO can be clearly seen by this technique.
TransCranial Doppler (or TCD) is a new, non-invasive test for diagnosing the presence of a PFO. TCD is more sensitive than TTE or TEE for finding a PFO, but does not show heart anatomy. TCD+TTE may render TEE unnecessary.
When microscopic bubbles are injected by IV into a vein in a normal heart, the
lungs reduce their passage to the left side of the heart. When a PFO is present, TCD detects bubbles which pass through the PFO and travel to the arteries in the brain. TCD, unlike TTE/TEE, is quantitative. The abnormal flow of blood through the PFO (detected by TCD) is called “shunting”. Shunting is one of the hallmarks of the PFO.
What is known about PFO and Stroke
PFO occurs in 10-15% of all adults PFO is diagnosed in 50-70% of patients with stroke of unknown cause. After a first stroke due to PFO, ½ of patients still have moderate to severe disability after 1 year. After a first stroke due to PFO, second strokes occur at a rate of 2%-9% each year. (depending on risk)
After several strokes from PFO, repeat strokes occur at a rate of 6%-20% each
year. The risk of repeat stroke due to PFO is increased in patients with leg clots,
migraine headache, atrial septal aneurysm (seen by echo), and large PFO
shunting (seen by TCD).
Not all PFO are the same
Risk and Amount of PFO Flow
While blood flow from the right atrium to the left atrium is the hallmark of a PFO, it is the AMOUNT of flow (or shunt) that is associated with the risk of recurrent stroke; the greater the flow: the greater the risk.
Bubbles injected by an IV appear in the right atrium and are detected by echo
when they appear in the left atrium. A small number of bubbles may pass through
Tiny PFO communications are low risk for stroke and do not need treatment.
Large PFO are much more likely to result in stroke, migraine, decompression
illness in divers, and low oxygen levels in the blood. Mistakenly thinking that
all PFO are the same is one of the reasons doctors may disagree on PFO
Atrial Septal Aneurysm and Increased Stroke Risk
In ½ of patients with high flow PFO, the septum primum (lower divider) is redundant and floppy due to excessive tissue. This floppy divider is called an atrial septal “aneurysm” (ASA). It is not at all like a true arterial aneurysm and cannot burst.
In patients with both ASA + PFO, the chance of repeat stroke is increased four fold (even on blood thinning medications). The presence of an ASA in a PFO stroke patient means that the YEARLY stroke risk is 4%. (Risk > 1.5% / year is considered very high).
Defining PFO Stroke Risk
The guide post for all medical treatment is called RISK STRATIFICATION. Medical tests and patient conditions help to show how much danger exists for a stroke. Since ½ of PFO strokes are disabling strokes, predicting the chance of stroke before it happens seems important.
Four risk factors are established in medical research which indicate a higher risk for stroke due to PFO. We use these to decide on PFO treatment. Brain injury on MRI(1) and migraine headache(2) increase the risk of stroke several fold in addition to high flow(3) and septal “aneurysm”(4). Other conditions may also increase risk: leg clots, sleep apnea, and diving.
What Are My Treatment Options?
PFO Treatment Options
ASPIRIN/ PLAVIX/ COUMADIN
-Continued lifelong risk of stroke ranging from 2-9% each year
-Bleeding due to medication effect aspirin:1.4% per year coumadin:2.2% per year
-Inconvenience of frequent blood tests (coumadin)
-No procedure related problems
-Possible reduction in stroke risk
Reduction of stroke due to PFO by medicines remains unproven
OPEN HEART SURGERY
-Serious complications (5%):
death, stroke, nerve injury, lung injury, infection, transfusion, anesthesia,
re-operation, chest scar
-5-7 day hospital stay/ 4-6 week recovery period
-Reduction of stroke risk
-Good complete closure rate: 90% at our hospital
CATHETER CLOSURE OF PFO
-Serious complications (0.2%):
death, stroke, infection, bleeding, blood vessel injury, anesthesia, device
movement or dislodgement (1:400), incomplete closure (1-5%) clot forming on
device (30/10,000 cases)
-Stroke reduction to less than 1%
-No scar; minimal pain
-Out patient procedure
-Return to full activity in 2 days
Available Devices For Catheter Septal Defect
CardioSEAL Septal Occluder
Amplatzer PFO Septal Occluder
These two devices are available for PFO closure. They are not investigational devices but are regulated by the FDA which requires you to have 2 strokes on coumadin (a strong anti-coagulant) before you can receive this preventative treatment.
The Amplatzer SO device is approved for septal defect closure. It has been used “off-label” for PFO closure and in a recent survey (TCT 2005), 90% of centers reported use of this device for PFO closure. Use of devices or medications “off-label” is common, legal, and accepted in medical practice. Indeed, in many circumstances “off-label” treatments are mandatory.
“Off-label” use occurs because research and experience and patient need move beyond original intended use of a therapy. Patients should understand these issues and all options before considering “off-label” treatments.
How do PFO devices work?
The PFO devices consist of two back-to-back umbrellas (CardioSEAL®) or discs (Amplatzer® PFO) which are connected centrally by a thin pin.
The devices are “spring loaded” to open to their original shape after being folded into a catheter or tube for placement in the body.
How do Septal Defect Devices Work?
The Amplatzer® SO device is similar to the other 2 devices and is inserted in the same way. It is available in 17 sizes rather than 3. However, this closure device has a thicker middle section which fills the atrial septal defect space better than the thin pin connectors of the other devices. Use of this device for a PFO septal defect would be an “off-label” use since it was originally intended for an atrial septal defect.
How Do Closure Devices Work?
The closure device is delivered to the heart through a small catheter or tube. The ICE (echo) catheter is placed in the same vein. These catheters are introduced into the body through a major vein in the groin. After the procedure, the catheters are removed and sutures are not needed.
TEE (echo) or more commonly Intra-Cardiac Echo (or ICE) and fluoroscopy (low level xrays) are used to safely and accurately place the devices in the heart. The ICE catheter is placed in the same vein as the device delivery catheter.
The discs or umbrellas on each side of the atrial septum (divider) hold onto the tissue and “pinch” the PFO closed. The SO device “pinches + fills” the septal defect. Device stability and completeness of closure are confirmed by the ICE images immediately during the procedure.
How Septal Occluders Heal
Within 3-6 months, the normal lining cells of the heart grow over the device, completely covering the artificial materials. The occluder device becomes part of the atrial septum and blood flows normally and clots cannot form or pass through the septum.
What Happens After Catheter Closure?
Return to normal activity in 2 days
Aspirin 6 months
Plavix 3 months
TCD 3 months
TTE 3 months
Other testing may be required
No dental care for 6 months
No contact sports for 1 month
No heavy lifting for 1 month
|FREQUENTLY ASKED QUESTIONS|
|Q: Is there anything I can do to prevent strokes or TIA’s before I have my PFO closed?|
|The best prevention of strokes or TIA’s prior to catheter closure of the PFO is to take (1) 325 mg aspirin daily. This provides good anti-coagulation without causing bleeding issues. Some physicians will prescribe Plavix for their patients prior to closure. Aspirin and Plavix, in concert, provide good anticoagulation and anti-platelet aggregation prior to and after closure.|
|Q: Should I stop exercising or participating in recreational activities?|
|Prior to PFO closure, we encourage our patients to continue their physical activities and recreational activities. However, after closure, you will have some restrictions of activity. Those restrictions include not lifting, pushing or pulling anything that weighs 50 lbs or more for 2-4 weeks. We also restrict any activities that may cause sudden movement or jarring in the upper torso. Some of those activities include: horseback riding, water skiing or snow skiing, rock climbing, skydiving, river rafting, mountain biking, ect. You should restrict yourself from those activities for the first 3 months following closure.|
|Q: Will I be required to wear a medical ID bracelet or carry a card in my wallet after closure?|
|No, you will not need to wear a medical ID bracelet or carry a card for the PFO closure device. The PFO is an anatomic defect that you had had repaired. This does not mean you have heart disease.|
|Q: Can I go through a metal detector or MRI scan without problems?|
|Yes, the device is compatible with a MRI scanner and will not present a problem in terms of the magnet. You can go through a security system or metal detector without setting off any alarms. If you do need a MRI scan, it would be advisable to inform your provider that you do have a device in your heart. We will provide you with the type of device you have prior to your discharge from the hospital.|
|Q: Can I resume sexual activity following closure?|
|Yes, you can resume sexual activity following closure. We recommend adequate healing time prior to resuming sexual activity so that the wound does not get irritated or infected. This healing takes approximately 4-5 days.|
|Q: What happens if I have similar symptoms after my PFO is closed?|
|We follow our patients closely following the procedure. The first month following closure is the most anxiety producing for patients. Some of the common symptoms following the procedure include palpitations (rapid heart rate or skipped beats), headache, chest pressure and occasional discomfort of the chest wall. If any of these symptoms persist and are concerning to you, we will schedule you to be seen in the office for an evaluation. We may order a chest x-ray or echo to assess the integrity of the device and, based on presentation and complaints, we may order another TEE (transesophageal echo). Once we have received the results, we treat or prescribe accordingly.|
|Q: How long does it take for the device to heal?|
|Endothelialization, the process of tissue growth over the device, takes approximately 3-6 months depending on the size of the device used.|
|Q: How am I evaluated after the procedure?|
|We have a schedule of follow up for our patients that will allow for us to assess the device over the period of 6 months.1 month following the procedure you will have a nurse visit in the office with the PFO coordinator. At that time a review of your symptoms and your status will be discussed. If there are concerning issues, the coordinator may request some of the above studies and discuss your case with Dr. Sorensen for further directions.
3 months following the procedure you will have a TCD (transcranial Doppler) study, a transthoracic echo (surface echo) and follow up visit with Dr. Sorensen. Your medications may be adjusted or continued based on the results of those studies.
6 months following the procedure, you will have the same studies performed that were done at 3 months. By the 6th month, we expect that endothelialization and anatomical seal of the device has occurred. Based on the individual findings, medications may be continued.
|Q: Will the abnormalities of my MRI heal after this procedure?|
|No, the findings on MRI are permanent. However, the purpose of closing the PFO is to prevent any further neurological damage from occurring. It is important that you discuss the findings on MRI with your neurologist and that you address questions of a neurological nature with them.|
|Q: What is the purpose of closing the PFO?|
|The ONLY indication for closure of the PFO is for stroke prevention. If you meet criteria for closure, you have had a stroke or TIA (transient ischemic attacks, “mini strokes”). The reason for closure is to reduce your stroke risk from 20% to less than 1% with transcatheter closure of the PFO.|
|Q: If I was born with this defect, why am I having symptoms now and not earlier in my life?|
|We do not fully understand the mechanism for symptoms that occur in individuals with PFO. What we do understand is that the strokes or TIA’s are random and unpredictable.|
|Q: If I do not meet criteria for closure, what do I need to do?|
|The hard part is to tell someone that they have a PFO but they don’t meet criteria for closure. However, the good news is that individuals understand that they do have this structural defect and that there are preventative measures to take to avoid TIA’s or stroke. Those measures are anti-coagulants: Plavix, Aspirin or Coumadin. All patients that do not meet criteria for closure are advised to take an anti-coagulant or a combination of anti-coagulants. This will be determined individually and is based on lab values and history. Your cardiologist or neurologist will recommend appropriate medication for you.|
|Q: When will this device be released for those who do not meet criteria?|
|In order for any medical device to be released for general use in the population, the device must be evaluated in clinical trials. Currently, there are 2 clinical trials for the PFO devices on the market. It is likely that the clinical trials will be ongoing for at least 24 months at this time.|
|Q: Are there side effects of Plavix and/or Aspirin?|
|Aspirin and Plavix can cause some stomach irritation. We recommend taking your Aspirin with food. Plavix is best taken in the evenings. If you experience stomach irritation, you can use an over the counter medication like Prilosec or Prevacid to help with the discomfort. If you notice any rectal bleeding or blood in the urine, please call us immediately. This is very uncommon but should be addressed if this occurs.|
|Q: Can migraines be improved by PFO closure?|
|Some patients have experienced relief of their migraine headaches following PFO closure. At this time, PFO closure is still being performed for prevention of stroke and not for the treatment of migraine headaches. There are currently 3 clinical trials in the United States that are designed to determine if PFO closure is effective in the treatment of migraines. The clinical trials are sponsored by 3 manufacturers of the PFO closure devices. Premium is the clinical trial sponsored by AGA Medical, the manufacturer of the Amplatzer device. The other trials are sponsored by NMT Medical (MIST 2); the manufacturer of the CardioSeal and Starflex devices and the third trial is sponsored by St.Jude’s called the Escape trial. The clinical trials are available in limited geographical locations in the United States. To find a clinical research site in your area, you should go to the website of the manufacturer of the devices.
For further information please contact Cardiac Center of Texas at 972-529-6939 or send us a question through the patient portal under the Patients tab at the top of the page. Thank you for visiting CardiacCenterOfTexas.com.