Implantable cardioverter defibrillator (ICD)

Heart conditions you’d have an ICD for

You may need an ICD fitted if:

• you’ve had a cardiac arrest  
• you’ve had ventricular arrhythmia before  
• you’re at risk of ventricular arrhythmia in the future 
• other treatments for ventricular arrhythmia have not worked.   

You may be more likely to have an abnormal heart rhythm if you have: 

• heart disease
• had a heart attack 
• heart failure
• disease of your heart muscle (cardiomyopathy) 
• an inherited heart condition, like Long QT syndrome (LQTS) or Brugada syndrome.  

How an ICD works

Your heart has a sinus node that sends out electrical impulses to make your heart beat. If your sinus node is not working properly, your heart can beat too quickly. 

An ICD can take over the role of your sinus node. It will check your heart rhythm all the time.

If it notices an abnormal heart rhythm, especially ones that could be dangerous, it can give electrical pulses to help your heart beat normally.  

If your ICD notices an abnormal heart rhythm it will: 

• Send a series of low-voltage electrical impulses at a fast rate to try and get your heart to beat at a normal rhythm (called pacing). 
• If this does not work, it may also send one or more small electric shocks to get your heart to beat at a normal rhythm (called cardioversion). 
• It can also give one or more larger shocks to get your heart to beat at a normal rhythm (called defibrillation).  

What does a shock feel like?

An ICD shock can feel like a sudden jolt or thump in your chest or back. It may make you jump. The feeling is different for everyone, and some people will only have a mild fluttering feeling or not notice it at all. It cannot shock people near you or touching you. 

Types of ICD

Many people will have a standard ICD fitted. But for some people, they may need a different type of ICD. This includes:

• Cardiac resynchronisation therapy with a defibrillator (CRT-D) – a special type of pacemaker that helps the chambers of your heart to beat at the same time. It’s usually fitted for people who have heart failure and are at risk of ventricular arrythmia.
• Subcutaneous implantable cardioverter defibrillator (SICD) – works in the same way as an ICD, but it’s put under the skin of your chest (outside your ribcage). There are no leads placed into your heart.

Fitting an ICD

Having an ICD fitted is a common procedure but it’s normal to feel a bit nervous. 

It normally takes about 1 to 3 hours. It can take longer if you’re having other treatments at the same time. 

1. You’ll be given local anaesthetic to numb the area. This means you’re awake but should not feel any pain. You may also be given sedation (a type of medicine) to help you relax and feel sleepy.
2. A small cut, about 5 to 6 centimetres, is made on the left side of your chest. 
3. The wires that connect the ICD to your heart will be put into a vein and guided to your heart. The wires (leads) will touch the wall of your heart muscle so they can check your heart rhythm. 
4. The ICD is then fitted into a small space in your chest, between your skin and your chest muscle. The leads and the ICD will be connected.  
5. The cut will be closed with a special type of glue or stitches. 

If you’re having a SICD the leads will be put under the skin in your chest. The box of the SICD will be put under the skin on the left side of your chest, under your armpit.

Most people will stay overnight after having an ICD fitted and go home the next day. You'll need to stay longer if you've had a cardiac arrest. Your ICD will be checked thoroughly before you go home.

• This video shows how ICDs and pacemakers are implanted.

Follow-up appointments

You should have regular follow-up appointments to have your ICD checked.

Usually, you’ll have an appointment every 3 to 12 months, depending on the type of ICD you have and if it’s given you treatment. It’s important to go to your appointments, even if you feel well.

Some ICD checks can be done from home (remotely). If this is possible, your ICD will send information to your healthcare professional.

Questions about living with an ICD

After having an ICD fitted you may want more information on whether it will affect your daily life. Here are some things to be aware of and ask your doctor about.

• Can a mobile phone interfere with my ICD?
• Can I wear a smartwatch if I have an ICD?
• Do I need to stop driving if I have an ICD?
• Are there any other things I need to avoid if I have an ICD?
• Can I have an MRI if I have an ICD?
• Will airport security affect my ICD?

You may need to avoid playing contact sports if you have an ICD. Usually, you can play sports that involve raising your arm, like golf. But check with your doctor about exercise and any sports you want to play.

Read more about living with an ICD in our booklet.

Get support

It’s normal to feel worried about having an ICD fitted and it often helps to talk to someone.

• Speak to other people with an ICD in our online community.
• Talk to one of our cardiac nurses by calling our Heart Helpline.
• Read our booklet about ICDs, including information on living with an ICD.