PFO stands for patent foramen ovale, and like many things in medicine, it goes back to Latin. When we are in utero in our mother's womb, there's actually a connection, a hole between the right and left atrium, that allows blood to come from the placenta into the system of the newborn, and that's called the foramen ovale, or the oval hole. After we're born, in most people, that hole closes. But in about one out of four people, it stays open, and the term for that is patent. So that is called a patent foramen ovale, or a PFO.
In most people it doesn't cause a problem, but in a few, it causes trouble. We believe that the PFO, this hole between the right and left side of the heart, can act as a conduit for blood clots that can form in the leg. Even very, very small blood clots that form can go up your legs, into the right side of the heart, go across this hole to the left side of the heart, and then the blood gets ejected to the brain, which can cause a stroke.
We see it mostly in people between the ages of 18 and 65. But it could happen in younger people and older as well. We now have really strong scientific evidence that in people who are less than the age of 60 or 65, who have a stroke, that closing this PFO can be really helpful.
There is a broad number of things that can happen with a stroke. We're looking at neurological symptoms, for example, inability to speak, garbled words, can't find the words, and you can't mouth them, numbness or tingling of your arms and legs and inability to move. These are the key warning signs of a stroke.
There are some basic tests we can do to detect a PFO. What that involves is measuring things that cross from the right side of the heart to the left side of the heart.
There are two broad ways we can do that. One is an ultrasound of the heart called an echocardiogram (ECG). What we do is we mix up salt water, normal saline, and make little bubbles and inject those bubbles into a vein in your arm and we watch your heart on the ultrasound. We see the bubbles come into the right side of the heart and can actually see them when they cross the hole into the left side of the heart. That should never happen. You should never get bubbles on the left side of the heart. It is usually filtered by the lungs.
The second major way to detect a PFO is something called transcranial Doppler. It's an ultrasound of your brain and we can actually see those bubbles go into your brain.
Again, most things in medicine go back to Latin. Genic means coming from. Crypto is unknown, like cryptography or cryptic. So, cryptogenic stroke is a grab bag term. People who have a cryptogenic stroke have strokes that we don't know why they happened. We do think that PFO may be a big part of the explanation for people who have strokes of unknown cause.
When someone shows up with a stroke of unknown cause, we generally think about people who are younger than age 65. Unfortunately as we get older, there are a whole host of known reasons that we can have strokes, be it hypertension, build up of the arteries or build up of atherosclerosis in the carotid arteries. When you're younger, you generally don't have those risk factors.
When we do a work up, we do a set of tests, to figure out whether we can detect a reason. In about 30 to 50 percent of those patients who have a cryptogenic stroke, we uncover a PFO.
If you have a hole in your heart where we think blood clots can travel through from one side of the heart to the other to cause a stroke, it makes sense to ask: Why don't we close the hole, and prevent that from happening?
Over the last decade, several devices have been developed, which we implant through a very small catheter through the vein in the groin. And there are currently two approved devices in the United States. This is not open heart surgery. This is done in a procedure room. We do it with sterile techniques in an operating room. I wear a hat and a mask and a gown. [The patient is sedated]. We guide the catheter by X-ray and a special ultrasound that I actually put inside the heart through a small incision, a needle poke really, in the vein in your groin called the femoral vein.
The procedure takes maybe 45 minutes. We watch you in the hospital for several hours, and then you go home the same day. Most people afterward, when we're done, ask me when I'm going to start the procedure. So that's just usually pretty easy.
There's what's called the Amplatzer PFO Occluder. It's made out of nitinol, which was actually developed by the Navy. Nitinol is actually a metal, but it almost acts like a fabric. It's a nickel titanium alloy made or discovered by the Navy. There are two disks, and inside these disks is a polyester fabric. What's amazing about nitinol is that you can just collapse this into a little tube and you can push it out of the tube and it pops back to its original confirmation.
The Amplatzer PFO Occluder has been proven to reduce the risk of recurrent stroke in patients who have a cryptogenic stroke that we think is from a PFO. Your body's own cells grow over these disks, and hermetically seal it over time.
The other device that has been proven to be effective in clinical trials is called the Cardioform. It's made by a company called W.L. Gore. This also has nitinol metal, but it's almost like a fabric. It kind of unfurls like a sail. This is a very soft, pliable device.
If you have someone who's had a stroke and has a PFO, it's really unclear what the best medical therapy is. It's either antiplatelet medicines like aspirin, or blood thinners like warfarin or Coumadin. So what we did, in two big trials, was flip a coin, and patients who were generally on the younger side, or had had a cryptogenic stroke, we either randomly by computer assigned them to the medicines, aspirin or Plavix, or warfarin, or they got one of these PFO closure devices. We followed them over time to see how many patients had a recurrent stroke. We found that both devices reduced the risk of recurrent stroke by more than 50 percent.
The thing is that every year you live you continue to have that risk of having a stroke. In younger people who have a long life to live, that stroke reduction over time can be pretty significant. The trial showed that the procedures were safe. The FDA approved these procedures, approved these devices, because it was a safe procedure and it was quite effective in reducing recurrent stroke.
I recommend baby aspirin indefinitely after either of these devices are implanted just to prevent other types of causes of stroke. But you certainly do not need blood thinners like warfarin or these other things you may see ads for.
As their physician, I don't recommend sky diving as a recreational activity. But some people do anyway. So, really, very few restrictions. For the first week after the procedure, I ask that they not lift anything terribly heavy. We're just protecting the groin, where I went through your vein. But after that, they can do whatever they want, be it skydiving, yoga or playing Xbox, whatever they like to do.
The disks never need to be replaced because over time your skin grows over them. They become incorporated within the heart in a very organic nice way. I do like to see my patients about a month after the procedure and at six months and at a year, just to see how they're doing and confirm that everything looks fine. The chance of having a complication from this device in particular, where it needs to be removed or something like that, is almost unheard of.
When a patient presents to us with a stroke we need to exclude several things. And some things are more common than others.
A very classic risk for having a stroke is atrial fibrillation (AFib), which is an irregular heartbeat, which in and of itself is benign. Atrial fibrillation is not something that can kill you. However, one of the complications of atrial fibrillation is getting a blood clot in a little pouch on the left side of the heart, which can cause a stroke. For that particular situation, we generally recommend blood thinners to reduce the risk of forming a blood clot, and that reduces the risk of a stroke. These are medications like Coumadin, or you may have heard of medications like Xarelto, or Eliquis, or Pradaxa or Savaysa, a whole host of drugs now.
However, in certain patients we think aren't great candidates for blood thinners, we may actually implant a plug inside that pouch that's called the Watchman device. There are other devices under clinical investigation at Scripps and other places.
Well, the pros are that we know they're effective in reducing the risk of a stroke if you have atrial fibrillation. The con is that you have to take a blood thinner. It's a daily medicine and there's a risk of bleeding. So, it prevents blood clots from forming, which is great, but it's also bad if you have a propensity to have a bleeding problem.
I don't think it's really a wonderful idea for a young person in their 30s or 40s to have to be on a drug like Coumadin for the rest of their lives to prevent another stroke from a PFO. So if we can put in a device to permanently prevent that risk, we get rid of the need to be on blood thinners, and they definitely can go skiing and skydiving after that.
There are other things we look at just to make sure they're not present for people who've had a stroke, whether it's build up of atherosclerosis in the carotid arteries. We look at your aorta. There are a host of things we look at when it comes to rare causes of strokes, This is part of the thing we do at the Cryptogenic Stroke Center. Dr. Mary Kalafut, Dr. John Rogers and myself, we exclude these other things. A lot of times people will go to a hospital with a stroke and they may get a shrug of the shoulders and told, "Oh, we don't know why you had the stroke, or "Oh, that's odd, you're pretty young. We don't know why you had the stroke." It's our burden to go in there and make sure that every box has been checked, and no stone unturned.