How can heart failure affect heart rhythm?
you have heart failure, the lower
chambers of your heart (the ventricles) aren't able to pump as much oxygen-rich
blood as the body needs. Some people who have heart failure also may have
abnormal heart rhythms that can cause sudden death.
The heart may
beat so fast that the ventricles don't have time to fill with blood. This type
of abnormal rhythm is called ventricular tachycardia (say "ven-TRICK-yuh-ler
tack-ih-KAR-dee-uh"). Sometimes the heart quivers, or flutters, and stops
pumping blood. This is called ventricular fibrillation (say "ven-TRICK-yuh-ler
fib-ruh-LAY-shun"). If these abnormal rhythms are not fixed right away, the
person may die.
How can an ICD help?
implantable cardioverter-defibrillator (ICD) is a
battery-powered device that can fix an abnormal heart rhythm and prevent sudden
death. The ICD is placed inside the chest. It's attached to one or two wires
(called leads) that go into the heart through a vein. The ICD is always
checking your heartbeat for an abnormal rhythm. If the ICD senses a dangerous
rhythm, it gives the heart an electrical shock to return the heart to a normal
An ICD also can fix a heart rate that is too slow or too
fast without using a shock. It can send out electrical pulses to speed up a
heart rate that is too slow. Or it can slow down a fast heart rate by matching
the pace and bringing the heart rate back to normal.
putting the ICD in your chest, your doctor will program it to send electrical
pulses or a shock when needed. Whether you get pulses or a shock depends on the
type of problem that you have and how the doctor programs the ICD to respond to
In some people who have heart failure, the ventricles don't
beat at the same time. If these people also have a risk for abnormal heart
rhythms, they may get a device that combines an ICD and a biventricular (say
"by-ven-TRICK-yuh-ler") pacemaker. This type of pacemaker uses electrical
pulses to make the ventricles pump at the same time. The ICD part of the device
can give a shock to fix an abnormal heart rhythm. For more information,
Should I get a pacemaker for heart failure?
How is the ICD placed?
Your doctor will put the
ICD in your chest during minor surgery. You will not have open-chest surgery.
You probably will have
local anesthesia. This means that you will be awake
but feel no pain. You also will likely have medicine to make you feel relaxed
Your doctor makes a small cut (incision) in your upper
chest. He or she puts one or two leads (wires) in a vein and threads them to
the heart. Then your doctor connects the leads to the ICD. Your doctor programs
the ICD and then puts it in your chest and closes the incision.
In some cases, the doctor may be able to put the ICD in another place in the
chest so that you don't have a scar on your upper chest. This would allow you
to wear clothing with a lower neckline and still keep the scar covered.
Most people spend the night in the hospital, just to make sure that the
device is working and that there are no problems from the surgery.
You may be able to see a little bump under the skin where the ICD is
How does it feel to get a shock from an ICD?
shock from an ICD hurts briefly. It’s been described as feeling like a punch in
the chest. But the shock is a sign that the ICD is doing its job to keep your
heart beating. You won't feel any pain if the ICD uses electrical pulses to fix
a heart rate that is too fast or too slow.
There’s no way to know
how often a shock might occur. It might never happen.
that the ICD could shock your heart when it shouldn't. If that were to happen,
you would have pain. The shock could make you fall out of bed, and that could
injure you. You also might be afraid or worried about when the ICD might shock
In rare cases, the shock could cause ventricular
fibrillation. If this happened, the ICD would shock your heart again to stop
the abnormal rhythm.
Many people say that they have a good quality
of life with an ICD. But shocks-and the fear of shocks-can make some people
worry too much. They may be afraid all the time that the ICD might shock them.
This worry can reduce a person's quality of life.
Who might want an ICD?
An ICD often is placed in
people with heart failure who have survived a dangerous abnormal rhythm. The
ICD would protect them if they get another abnormal heart rhythm.
But it also may be offered to people with heart failure who haven't had
an abnormal heart rhythm but are at risk for one.
You will have
tests to see whether you are at risk for abnormal heart rhythms. These may
electrocardiogram (EKG), an
echocardiogram, or an
will use these test results and your medical history to figure out whether an
ICD could help you. He or she also will rely on guidelines that help doctors
find out who might benefit from an ICD.1 These
guidelines will likely change often because experts are doing new research and
creating new technology. You and your doctor can work together to decide
whether you want to get an ICD.
Many medical facts play a role
in whether you should get an ICD. Your doctor will look at whether:
- You're taking medicine to treat heart failure and to prevent
abnormal heart rhythms.
- You're expected to live more than 1 year.
ejection fraction is lower than normal.
- You have passed out from previous abnormal heart
- You have had a
- You have
class II or III heart failure.
Who might not want an ICD?
Sometimes an ICD is
not recommended. You and your doctor may decide against
an ICD if any of the following apply to you:
- You're expected to live less than 1 year.
- You have constant abnormal heart rhythms (ventricular
tachycardia or ventricular fibrillation) that can't be controlled with
medicines. An ICD would shock you repeatedly.
- You have
class IV heart failure and heart transplant surgery is
not an option. People who have class IV heart failure can't do any physical
activity without symptoms. An ICD probably wouldn't help you live
- You have an abnormal heart rhythm that can be fixed with
catheter ablation. This is a procedure that destroys
some heart tissue where the abnormal rhythm starts.
- You have a mental illness that would be made worse by an ICD or
that may keep you from having follow-up checkups.
What are the benefits of an ICD?
An ICD can
prevent sudden death from an abnormal heart rhythm. Studies also show that an
ICD works better than medicine to help people with an abnormal heart rhythm and
heart failure live longer.
- Research has shown that ICDs lower the risk of sudden death in
people who have heart failure but don't have heart disease (coronary artery disease). Over a 2-year period, 1
death was prevented for every 25 people who got an ICD.2
- Another study found that ICDs worked even better to lower the
risk of sudden death in people who have both heart failure and heart disease.
It found that, over a 2-year period, 1 death was prevented for every 18 people
who got an ICD.3
- Another study found that medicine (amiodarone) wasn't much
better than no treatment in lowering the risk of death from a heart rhythm
What are the risks of an ICD?
There are several
risks to getting an ICD. But the risks are different for each person. The
chance of having some problems is very low.
- You could get an infection where the ICD is placed. This
happens less than 1 time out of 100 to just over 12 times out of 100. So there
is no infection about 88 to 99 times out of 100.5
- The leads that attach to the heart may break or stop working
right. This can happen between 2 and 15 times out of 100 after 5 years of
having the ICD. So it does not happen about 85 to 98 times out of 100.5, 6 But the risk of a lead breaking or
not working right appears to increase over time. One long-term study found
that, after 10 years, 20 out of 100 leads had problems. This also means that 80
out of 100 leads didn't have problems.7 If a lead does
break or does not work anymore, you would need surgery. The surgery would be
more complex than that needed to replace an ICD battery.
- Serious bleeding could occur after placement of the ICD. This
happens from 1 to 6 times out of 100. Serious bleeding doesn't happen 94 to 99
times out of 100.5
- A lung could collapse (pneumothorax) from a buildup of air in
the space between the lung and the chest wall. This happens less than 1 time in
100. This doesn't happen 99 times out of 100.5
The ICD could shock the heart when it shouldn't. There is
no way to know if or when this could happen. It might never happen.
There also is a chance that a manufacturer may recall an ICD for a
problem. If this were to happen, you might need surgery to take out the ICD and
What follow-up do you need after getting an ICD?
You will need regular checkups with your doctor to make sure that the ICD
It's important to keep taking your medicines for heart
failure. You'll also need to follow a healthy lifestyle to treat heart failure.
This may include watching how much fluid you drink, eating healthy foods that
are low in salt, and not smoking.
If the ICD gives you a lot of
shocks, your doctor may prescribe amiodarone. This medicine helps prevent
abnormal heart rhythms and may keep the ICD from sending shocks too often. Your
doctor also could suggest catheter ablation to lower the number of times the
ICD shocks you. Catheter ablation can lower the chance of some abnormal heart
rhythms, such as
atrial fibrillation, which could cause the ICD to
ICDs run on a battery that lasts from 5 to 8 years. To
replace the battery, you will need minor surgery.
If you get an
ICD, you have to be careful not to get too close to some devices with strong
magnetic or electrical fields. These include
MRI machines, battery-powered cordless power tools,
and CB or ham radios. But most everyday appliances are safe. For more
- Heart problems: Living with a pacemaker or ICD.
If you need more information, see the topic