May 6, 2008 There’s an electrical storm brewing inside the hearts of more than 2.2 million Americans. And just like lightning, this kind of storm can have devastating consequences.
The “storm”, in this case, is a condition called atrial fibrillation – the most common form of irregular heartbeat in the United States.
And the “lightning bolts” they can produce are tiny blood clots, which can form when blood pools in a heart that’s not beating regularly. When these clots escape the heart, they can travel to the brain. And then, quick as lightning, those clots can cause a stroke or mini-stroke that can kill or disable a person within minutes.
In fact, as many as one in every five strokes in America are related to atrial fibrillation, which is also called AF. That’s more than 150,000 strokes a year. People with AF have a stroke risk that’s up to six times higher than the risk for other people their age — and if they have other health conditions such as diabetes or heart disease, their stroke risk is even higher.
Fortunately, doctors now have a broad range of new — and tried-and-true — ways to treat AF and prevent blood from pooling in the heart.
Besides medicines that can prevent clots and try to calm a racing heart, these options include some new experimental treatments that are being tried at a small number of hospitals, including the University of Michigan Cardiovascular Center.
These options include radio-wave treatment called ablation that “zaps” tiny areas of heart muscle to restore normal rhythm; an implanted device that closes off a “blind alley” in the upper left chamber of the heart to keep blood from pooling; and a device that uses a special balloon-camera and a precise laser to treat AF.
U-M is considered one of the nation’s leading centers for the treatment of AF and other heart rhythm problems in adults and kids.
No matter which treatment option a patient chooses, the main goals are to try to calm the racing heartbeat of AF and prevent strokes, says Eric Good, D.O, a U-M doctor who specializes in treating AF and other heart-rhythm problem.
“Atrial fibrillation is a chaotic, electrical rhythm that begins in the top chamber of the heart, called the atrium,” explains Good, an assistant professor of cardiovascular medicine at the U-M Medical School.
“It involves impulses that whirl around the top chamber, traveling at speeds of 400 to 600 beats per minute in a type of electrical storm that can bombard the lower chambers with rapid signals and result in a very irregular and fast heart beat.” A normal resting heart rate for an adult is around 50-100 beats per minute.
Most AF treatments aim to calm the symptoms that the condition can cause – including a feeling that the heart is racing, shortness of breath, chest pain, dizziness and light-headedness. Often, these symptoms can interfere with everyday life for many people with AF.
But even people who don’t experience symptoms from their AF are at higher risk of stroke, especially if they have other health problems, Good says.
That’s why national guidelines recommend that many people with AF take blood-thinning medications, and medicines that can control their heart rate. Such medicines have been shown to significantly reduce the risk of stroke in many, but not all, patients.
Warfarin, also called Coumadin, is the most common blood-thinner, and prevents clots very effectively. But it carries risks of uncontrolled bleeding and patients must be tested regularly to make sure their dose is right. Younger patients may just need to take aspirin to prevent clots.
Meanwhile, rate-controlling medicines often work well – but they don’t work for everyone and their effectiveness may decrease after a while. Still, for many people with AF, they are often enough to keep the heart beating relatively regularly for a while.
When medicine isn’t enough
But what if medicines aren’t enough, and fail to control clotting and rhythm? And what about AF patients who have other problems that keep them from being able to take certain medicines? That’s when procedures offered by a few specialized centers, including U-M, might be an option.
Most of these procedures are so new that there isn’t good long-term evidence yet about whether, or how well, they prevent strokes. It would seem to make sense, but it hasn’t been shown for sure – which is why U-M researchers and others are still studying the issue. Nonetheless, such minimally invasive treatments offer relief, and the chance to steady the heartbeat.
The procedure with the longest track record is radiofrequency ablation of the left atrium, also called RF ablation.
“In this procedure, catheters are inserted through the veins in the groin, and advanced up into the heart and across into the left atrium of the heart,” Good explains. “Once the probe is there, we can zap the electrical rhythms that lead to the AF, and restore a normal, regular heart rhythm.”
The procedure puts a large amount of energy into an area of heart muscle just a few millimeters across, which causes scar tissue to form in that tiny area. That keeps the abnormal electrical signals from getting through.
Another option, which is still being investigated at few hospitals nationwide including U-M, is called a Watchman device. It’s designed to keep clots from forming in a small area of the heart that’s called the left atrial appendage – a “sock” off to the side of the atrium. The appendage seems to serve little purpose, and yet it’s the birthplace of more than 90 percent of clots that form in the heart.
Just as with RF ablation, the Watchman device is delivered into the heart through a catheter, so only a tiny needle puncture into the body is required. Once it gets to the right place, it’s unfolded, and tiny barbs on its end grab into the walls of the left atrial appendage.
“Eventually, the body heals over it, and prevents clots from entering that area,” Good explains. “This is an exciting new technology because it could allow patients who would otherwise need blood thinners the rest of their life to come off the medicines while still having, we hope, a reduced risk of stroke.”
Another technology now being tested in U-M patients is an experimental treatment that uses a special balloon-camera to see inside the heart, and a tiny laser to “zap” heart muscle tissue with the same goal as the RF ablation technique: to create tiny scars that will prevent irregular electrical impulses from getting through.
In addition to all of these, many AF patients also consider getting a pacemaker or an implantable cardioverter-defibrillator (ICD) implanted. These devices can directly — or in combination with medication – regulate their heart, and shock it back into rhythm if it starts to enter a dangerously irregular pattern.
In the end, Good says, “The bottom line for patients who have atrial fibrillation, and who may be at risk for stroke, is to be evaluated by their healthcare professional. They can assess the individual risk, and offer access to a whole variety of treatment options that may reduce the risk of having a stroke.”
Lewis Morgenstern, M.D., director of the U-M Stroke Program, agrees. “The link between atrial fibrillation and stroke is so tight that it is crucial that patients work with their doctor to discuss the treatment options,” he says. “There is a lot that can be done, particularly at a center such as ours with specially trained stroke specialists from neurology, cardiology and many other fields.”
What if a stroke strikes?
Everyone who has atrial fibrillation, and their loved ones, needs to be especially aware of the signs and symptoms of a stroke or mini-stroke. Even with the best AF treatment, a stroke can still occur.
Signs of a stroke include any sudden change in the ability to move the arms or legs, sudden changes in vision, and sudden changes in the ability to speak or to understand someone else. If these symptoms occur and then disappear immediately, it may be a mini-stroke – which is a warning sign that a full-blown stroke could happen anytime.
If these symptoms appear and don’t go away within a few moments, that’s a full-blown stroke – and could kill or permanently disable a person within minutes or ours.
In either case, the best thing to do is to call 911 immediately. Don’t wait for the symptoms to go away, don’t drive yourself or ask someone to drive you. And if you can, tell the ambulance crew and emergency room staff that you have atrial fibrillation, and inform them of any medicines you’re taking.
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