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 radiowave 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 ballooncamera and a precise laser to treat AF.
UM 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 UM doctor who specializes in treating AF and
other heartrhythm 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
UM 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 50100 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 lightheadedness. 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 bloodthinning 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
bloodthinner, 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,
ratecontrolling 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
UM, might be an option.
Most of these procedures are so new that there
isn’t good longterm 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 UM 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 UM, 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 UM patients
is an experimental treatment that uses a special ballooncamera 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 cardioverterdefibrillator (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
UM 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 ministroke.
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 ministroke –
which is a warning sign that a fullblown stroke could happen anytime.
If these symptoms appear and don’t go away within a
few moments, that’s a fullblown 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.
For more information on atrial fibrillation and its
treatment:
