What Is Cardioversion?
Cardioversion (KAR-de-o-VER-shun) is a procedure
used to restore a fast or irregular heartbeat to a normal rhythm. A fast or
irregular heartbeat is called an
arrhythmia
(ah-RITH-me-ah).
Arrhythmias can prevent your heart from pumping
enough blood to your body. They also can raise your risk for
stroke,
heart
attack, or
sudden
cardiac arrest.
Overview
To understand arrhythmias, it helps to understand
how the heart works. Your heart has an internal electrical system that controls
the rate and rhythm of your heartbeat. With each heartbeat, an electrical
signal spreads from the top of your heart to the bottom.
As it travels, the signal causes your heart to
contract and pump blood. The process repeats with each new heartbeat. (For more
information on the heart's electrical system and a detailed animation, go to
the Diseases and Conditions Index article on
How
the Heart Works.)
A problem with any part of this process can cause an
arrhythmia. During an arrhythmia, the heart can beat too fast, too slow, or
with an irregular rhythm. Cardioversion is used to correct fast or irregular
heartbeats.
Cardioversion is done two ways: using an electrical
procedure or using medicines.
For the electrical procedure, low-energy shocks are
given to your heart to trigger a normal rhythm. You're temporarily put to sleep
before the shocks are given. This type of cardioversion is done in a hospital
as an outpatient procedure. This means you can go home after the procedure is
done.
Cardioversion also can be done by taking medicines
that correct arrhythmias. This type of cardioversion usually is done in the
hospital. It also can be done at home or in a doctor's office.
This article only discusses the electrical
procedure.
Many doctors prefer to do electrical cardioversions
because they work better and are more predictable. It's also easier to find out
right away if the procedure worked.
Cardioversion isn't the same as defibrillation
(de-fib-ri-LA-shun), although they both involve shocking the heart.
Defibrillation gives high-energy shocks to the heart to treat very irregular
and severe arrhythmias. Defibrillation is used to restore normal heartbeats
during life-threatening situations, such as cardiac arrest.
For more information on defibrillation, see the
Diseases and Conditions Index articles on
Sudden
Cardiac Arrest and
Implantable
Cardioverter Defibrillator.
Outlook
Cardioversion successfully restores normal heart
rhythms in more than 75 percent of people who have the procedure. However, fast
or irregular heartbeats can occur again. For this reason, you may need to have
more than one cardioversion over time.
The procedure has some risks. For example, it may
worsen arrhythmias. However, serious complications are rare.
Who Needs Cardioversion?
You may need cardioversion if you have an
arrhythmia
that's causing troublesome symptoms. These symptoms may include dizziness,
shortness of breath, extreme fatigue (tiredness), and chest discomfort.
Atrial
fibrillation (A-tre-al fi-bri-LA-shun), or AF, is the most common type of
arrhythmia treated with cardioversion. In AF, the electrical signals travel
through the upper chambers of your heart (the atria) in a fast and disorganized
way. This causes the atria to quiver instead of contract.
Atrial flutter, which is similar to AF, also may be
treated with cardioversion. In atrial flutter, the electrical signals travel
through the atria in a fast, but regular, rhythm.
Less commonly, you may have cardioversion to treat a
rapid heart rhythm in the lower chambers of your heart.
You may need cardioversion on an emergency basis if
your symptoms are severe. However, you usually schedule this procedure in
advance.
Cardioversion may not be right for you if you have
other heart conditions as well as an arrhythmia. Talk to your doctor about
whether cardioversion is an option for you.
What To Expect Before Cardioversion
You usually can't have any food or drinks for about
12 hours before the cardioversion (as your doctor advises).
You're at increased risk for dangerous blood clots
during and after a cardioversion. This is because the procedure can dislodge
blood clots that may have formed due to an
arrhythmia.
Your doctor may prescribe anticlotting medicine to prevent these clots. People
often take this medicine for several weeks before the procedure and for several
weeks to months after the procedure.
To find out whether you need anticlotting medicine,
your doctor may have you undergo a transesophageal echocardiogram (TEE) before
the cardioversion. A TEE is a special type of ultrasound. An ultrasound is a
test that uses sound waves to look at the organs and structures in the
body.
You will be given medicine to make you sleep during
the TEE. A special wand that transmits sound waves is put on the end of a tube.
The tube is put down your throat into your esophagus (the passage from your
mouth to your stomach). The tube is placed close to your heart, and the sound
waves create pictures of your heart. Your doctor will look at these pictures to
see whether you have any blood clots.
The TEE will be scheduled for the same time as the
cardioversion or just before the procedure. If blood clots are found, your
cardioversion may be put off for a few weeks. During this time, you will take
anticlotting medicine.
Even if no blood clots are found, you will be given
anticlotting medicine through a vein during the cardioversion. You also will
take medicine after the procedure to prevent blood clots.
Before a cardioversion, you're given medicine to
make you sleep through the procedure. This medicine can affect your awareness
when you wake up. You will need to arrange for someone to drive you home after
the procedure.
What To Expect During Cardioversion
A nurse or technician will stick soft patches,
called electrodes, on your chest and possibly on your back. Some shaving may be
needed to get the patches to stick to your skin.
These patches are attached to a cardioversion
machine. This machine records your heart's electrical activity. The machine
also sends low-energy shocks through the patches to restore a normal heart
rhythm.
Your nurse will use a needle to insert an
intravenous (IV) line into a vein in your arm. Through this line, the doctor or
nurse will give you medicine to make you fall asleep. While you're asleep, a
cardiologist (heart specialist) will give one or more low-energy electrical
shocks to your heart. You won't feel any pain from the shocks because of the
medicine used to make you sleep.
Your heart rhythm and blood pressure will be closely
watched during the procedure for any signs of complications.
Cardioversion
The illustration shows a typical
setup for a nonemergency cardioversion. Figure A shows an irregular heart
rhythm recording (before the cardioversion). Figure B shows a normal heart
rhythm recording (after the cardioversion). Figure C shows the patient lying in
bed with cardioversion pads attached to his body. The doctor closely watches
the procedure.
Cardioversion takes just a few minutes. However, you
will likely be in the hospital for a few hours due to the prep time and
monitoring after the procedure.
What To Expect After Cardioversion
You will be closely watched for an hour or so after
the procedure for any signs of complications. Your doctor or nurse will let you
know when you can go home.
You may feel drowsy for several hours after the
cardioversion because of the medicine used to make you sleep. You shouldn't
drive or operate heavy machinery the day of the procedure. You will need to
arrange for someone to drive you home from the hospital. Until the medicine
wears off, it also may affect your awareness and ability to make decisions.
You may have some redness or soreness on your chest
where the electrodes were placed. This may last for a few days after the
procedure. You also may have slight bruising or soreness at the site where the
intravenous (IV) line was inserted.
You will take medicine for several weeks to months
after the procedure to prevent blood clots. During this time, you also may take
medicine to prevent repeat
arrhythmias.
What Are the Risks of Cardioversion?
Cardioversion can sometimes worsen
arrhythmias.
Rarely, it can cause life-threatening arrhythmias. These irregular heartbeats
will occur within minutes of the procedure. They're treated right away with
electrical shocks or medicines, so they usually don't cause serious
problems.
Rarely, cardioversion can cause
stroke or other complications due to blood clots in the heart
traveling to other organs or tissues. The risk of this happening is less than 5
percent if you take anticlotting drugs before and after the procedure.
Key Points
- Cardioversion is a procedure used to restore a
fast or irregular heartbeat (an
arrhythmia)
to a normal rhythm.
- Cardioversion is done two ways: using an
electrical procedure or using medicines. This article discusses electrical
cardioversion. For this procedure, low-energy shocks are given to your heart to
trigger a normal rhythm.
- Cardioversion isn't the same as defibrillation.
Defibrillation gives high-energy shocks to the heart. It's used to restore
normal heartbeats during life-threatening situations, such as cardiac
arrest.
- You may need cardioversion if you have an
arrhythmia that's causing troublesome symptoms. These symptoms may include
dizziness, shortness of breath, extreme fatigue (tiredness), and chest
discomfort.
- Atrial
fibrillation is the most common type of arrhythmia treated with
cardioversion.
- You may need cardioversion on an emergency basis
if your symptoms are severe. However, you usually schedule this procedure in
advance.
- You're at greater risk for dangerous blood clots
during and after a cardioversion. This is because the procedure can dislodge
blood clots that may have formed due to an arrhythmia. Your doctor may
prescribe medicine both before and after the procedure to prevent these blood
clots from causing complications, such as
stroke.
- Before a cardioversion, you're given medicine to
make you sleep through the procedure. While you're asleep, a cardiologist will
give one or more low-energy electrical shocks to your heart to trigger a normal
heartbeat. You won't feel any pain from the shocks due to the medicine used to
make you sleep.
- Cardioversion takes just a few minutes. However,
you will likely be in the hospital for a few hours due to the prep time and
monitoring after the procedure.
- You will be watched closely for an hour or so
after the procedure for any signs of complications. You may feel drowsy for
several hours after cardioversion because of the medicine used to make you
sleep. You should arrange for someone to drive you home after the
procedure.
- Cardioversion has some risks. It can worsen
arrhythmias. Rarely the procedure can cause stroke or other complications due
to blood clots in the heart traveling to other organs or tissues. However,
serious complications are rare.
- Cardioversion successfully restores normal heart
rhythms in more than 75 percent of people who have the procedure.
Links to Other Information About Cardioversion
NHLBI Resources
Non-NHLBI Resources
Clinical Trials
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