What is electrical cardioversion?
Cardioversion is a procedure used to reset an abnormal heart rhythm to a normal rhythm.
This procedure is used when the heart is beating very fast or irregular. This is called
an arrhythmia. Arrhythmias can cause problems such as fainting, stroke, heart attack,
and even sudden cardiac death. With electrical cardioversion, a high-energy shock
is sent to the heart to reset a normal rhythm. It's different from chemical cardioversion,
in which medicines are used to try to restore a normal rhythm.
Normally, a special group of cells begin the electrical signal to start your heartbeat.
These cells are in the sinoatrial (SA) node. This node is in the right atrium, the
upper right chamber of the heart. The signal quickly travels down the heart’s conducting
system on the way to the ventricles, the two lower chambers of the heart. As it travels,
the signal triggers nearby parts of the heart to contract. This organized pattern
helps the heart contract in a coordinated way.
Various problems can disrupt this signaling pathway and lead to abnormal heart rhythms.
The heart might beat very quickly, not leaving it enough time to fill with enough
blood between beats. This can prevent your heart from pumping enough blood to the
body. Some abnormal heart rhythms raise your risk of stroke. Some also raise the risk
of life-threatening rhythms that can lead to sudden death. Cardioversion interrupts
the abnormal signaling and lets the heart reset itself back into a normal rhythm.
Cardioversion is usually a scheduled procedure. But sometimes healthcare providers
need to do it on an urgent basis if symptoms are severe. You will likely be given
medicine to put you to sleep before delivering the shocks. Cardioversion is not the
same as defibrillation. Both use shocks to reset the heart. But in a cardioversion,
the shock is synchronized with the heartbeat. Defibrillation is typically done in
an emergency to stop very severe rhythms that can cause sudden death.
Why might I need an electrical cardioversion?
Electrical cardioversion can help treat several different abnormal heart rhythms.
It's commonly used to treat sustained arrhythmias such as atrial fibrillation (Afib).
With this condition, the atria of the heart quiver instead of beating the right way.
Symptoms of Afib may include shortness of breath, fatigue, and a very fast heartbeat.
It can also increase risk for stroke.
If this is your first time having Afib, your healthcare provider may be more likely
to suggest cardioversion. Your provider may also want you to have it if you have ongoing
Afib, especially if it gives you severe symptoms. Electrical cardioversion works better
and is used more often than chemical cardioversion. It's also faster.
Your healthcare provider may not recommend cardioversion if you don't have symptoms
from the Afib or if your symptoms are very minor. It also may not be recommended if
you are elderly, if you have had Afib a long time, or if you have other major medical
problems. Other treatments might be better for you, like heart rate control with medicines.
Electrical cardioversion is also useful for treating other abnormal heart rhythms,
like atrial flutter, which is similar to Afib. It can also be used to treat certain
kinds of supraventricular tachycardias and ventricular tachycardia (VT). These types
of heart rhythms can cause heart rates that are too fast. This can prevent the heart
from pumping enough blood.
Before trying electrical cardioversion, your healthcare provider may try to reset
the heart rate in other ways. This might include the Valsalva maneuver. This is a
method where you hold your breath and increase the pressure in your belly. This can
help bring the heart rate down. Your healthcare provider may then try medicines to
change the rhythm to normal. If these methods don’t work, electrical cardioversion
is often the next step. In other cases, electrical cardioversion is the first recommended
You may need an electrical cardioversion soon if you have severe symptoms from your
What are the risks of electrical cardioversion?
Although most people have a successful electrical cardioversion, it does have certain
risks. Your own risks may vary based on your age, the type of abnormal heart rhythm
you have, and your other medical conditions. Ask your healthcare provider about your
Rarely, the procedure causes a more dangerous heart rhythm. If that happens, someone
will give you medicines or a stronger electric shock to stop this rhythm. Some other
Problems breathing if you had medicine (sedation) to help you sleep during the procedure
Other less dangerous abnormal rhythms
Slow heart rate afterwards
Temporary low blood pressure
Heart damage (usually temporary and without symptoms)
Dislodged blood clot, which can cause stroke or other problems
In certain situations, healthcare providers lower this last risk by giving medicines
to help prevent clots (blood thinners). They give people these medicines before and
after the procedure.
In some cases, the cardioversion may not be able to reset a normal heart rhythm. There
is also a risk that you might go back to your abnormal rhythm shortly after your cardioversion.
Sometimes people need to take medicines to help control the heart rhythm before the
procedure. They may need to take medicines after the procedure and prevent the problem
from happening again.
How do I get ready for an electrical cardioversion?
Talk with your healthcare provider about what you should do to get ready for your
electrical cardioversion. Follow any directions you are given for not eating or drinking
before the procedure.
Follow your healthcare provider’s instructions about what medicines to take before
the procedure. This includes any medicines to prevent abnormal rhythms. Don’t stop
taking any medicine unless your healthcare provider tells you to do so. You might
need blood tests before the procedure to make sure the procedure is safe to do.
If you are at higher risk of blood clots, your healthcare provider may want you to
take anti-clotting medicine. These are commonly taken for several weeks before and
after the procedure. Not everyone needs this medicine, but most people do. You are
likely to need anti-clotting medicine if your abnormal rhythm has lasted more than
48 hours or if you have had a blood clot in the past.
Your healthcare provider may want a transesophageal echocardiography (TEE) test before
the procedure. This test is a special kind of ultrasound. A thin, flexible tube is
put down your throat and into your esophagus. Here, the tube is close to your heart.
It lets your healthcare provider see if you have any blood clots in the heart. Your
cardioversion will be delayed if a clot is found. You’ll likely need to take blood-thinner
medicine such as warfarin for a while until your risk for clots is low. You may have
a repeat TEE to make sure the clot has gone away. It’s important to take any blood-thinning
medicines exactly as your healthcare provider tells you.
What happens during an electrical cardioversion?
Talk with your healthcare provider about what to expect during your procedure. It
may differ if you need an urgent or emergency electrical cardioversion. In general,
you can expect the following:
Soft electrode pads are placed on your chest and maybe on your back. You might need
some areas of skin shaved to get the electrode pads to stick.
These electrodes will connect to a cardioversion machine.
You will get medicine through a vein in your arm to make you fall asleep.
Using the cardioversion machine, a programmed high-energy shock is sent to your heart.
This should convert your heart back to a normal rhythm.
Your team will closely monitor your heart rhythm. They will watch for any signs of
The procedure only takes a few minutes. When it is done, you will wake up.
What happens after an electrical cardioversion?
Ask your healthcare provider about what to expect. You will likely:
Wake up 5 to 10 minutes after the procedure
Be closely watched for signs of complications for several hours
Feel sleepy for several hours after the cardioversion. Arrange to have someone drive
Go home the same day as the procedure
Have some redness or soreness on your chest that lasts for a few days
Ask your healthcare provider about what medicines you’ll need to take when you get
home. Many people need to take an anti-clotting medicine such as warfarin or another
blood thinner. Some people also need medicines to prevent abnormal heart rhythms.
Take all your medicines exactly as your healthcare provider tells you. Tell your healthcare
provider right away if any of your symptoms come back.
Before you agree to the test or the procedure make sure you know:
The name of the test or procedure
The reason you are having the test or procedure
What results to expect and what they mean
The risks and benefits of the test or procedure
What the possible side effects or complications are
When and where you are to have the test or procedure
Who will do the test or procedure and what that person’s qualifications are
What would happen if you did not have the test or procedure
Any alternative tests or procedures to think about
When and how you will get the results
Who to call after the test or procedure if you have questions or problems
How much you will have to pay for the test or procedure