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Implantable cardioverter defibrillator (ICD)

An ICD is a device that helps people with dangerously irregular heart rhythms. Find out what happens when you get an ICD and how it might affect your life.

An ICD (implantable cardioverter defibrillator) is a small device that helps keep your heart beating at a steady rate. It can reduce the risk of your heart stopping (cardiac arrest).

Many people feel safer knowing they have an ICD to help their heart if they need it.

Read Jo's cardiac arrest story

What does an ICD look like?

ICD in palm of hand

An ICD is small enough to sit in the palm of your hand.

Who needs an ICD?

You get an ICD when there's a high risk that your heart could stop beating (cardiac arrest). This may be because you've already had a cardiac arrest, or because your heart condition means you’re at risk of having one.

Heart conditions that increase your risk of cardiac arrest are:

  • certain kinds of irregular heart rhythms (arrhythmia)
  • heart attack
  • some kinds of cardiomyopathy (a condition that thickens the heart muscle and stops it pumping properly)
  • heart failure, where the heart function is decreased
  • some inherited heart conditions, such as Long QT syndrome, sudden cardiac death, or Brugada syndrome.

Not everyone with these conditions will need an ICD. Doctors will make the decision on a case by case basis.

How does an ICD work?

The ICD is usually fitted in your chest. It checks your heart beat all the time.

If your heart beat is too slow, some ICDs are programmed to correct it (like a pacemaker). This is called pacing.

If your heart is in danger of stopping, the ICD can deliver an electric shock to help it return to a normal rate. This is called defibrillation.

The ICD is made up of:

  • a pulse generator – a small box, about the size of a business card, which contains a long-lasting battery and an electronic circuit. It is small enough to sit in the palm of your hand
  • one or more leads that connect the pulse generator to your heart.

Electrodes are inserted into a vein leading to the heart. The pulse generator is inserted under the skin.

Subcutaneous ICD

Some people may receive a different type of ICD, called a subcutaneous ICD (S-ICD).

An S-ICD sits on the side of the chest, under the armpit and has a single lead which goes under the skin. The electrode that delivers the shock sits outside the heart rather than being attached to it.

Due to advances in technology, new types of ICDs are currently being developed. Your doctor will talk to you about what the right kind of ICD is for you.

How is an ICD fitted?

Your ICD will be fitted in hospital.

You’ll be given medication to help you relax. You will also get an injection to numb the area (local anaesthetic). It shouldn’t be painful, but you may feel some sensation in the area. Some people may have a general anaesthetic.

The ICD is fitted below your collar bone. The doctor will use x-ray screening to insert the electrical leads through a vein and attach them to your heart. 

The procedure takes at least an hour, but some people may need longer.

Before you leave the hospital

One of the clinical team will check that your ICD is working properly before you leave hospital. They will explain how the ICD and the remote monitoring system works. Check with staff when to expect your follow up appointment.

You should also be given information on how to care for the wound and an ICD identification card. Carry the identification card and a list of your medications with you at all times. Especially for medical appointments and when you're travelling.

For some people, having an ICD fitted is a one-day procedure. Others may have to stay in hospital longer. Either way, you’ll need someone to drive you home.

When you get home

You may be sore after the ICD is inserted.

It’s important not to pick at the glue or stitches that have been used to close the skin. Do not place any plasters, bandages or spray dressings over the wound. Don’t put any cream or talcum powder on the area. Keep the wound dry.

Go straight to the doctor if:

  • you have symptoms like the ones you had before the ICD was put in
  • you have hiccupping or twitching in your chest area
  • you have a racing heart
  • the wound gets red, swollen, hot, more painful, or it leaks
  • you have a high temperature for no obvious reason.

It takes a few weeks for the ICD leads to become fully secure. So during that time avoid lifting heavy items or lifting your arm above your shoulder, on the side of the wound. Be careful when you wash and dry your hair, or put clothes over your head. Take your time and move your arm slowly.

You may need to arrange help for some tasks like:

Hanging out washing, lifting a child, reaching into high cupboards

  • hanging out washing
  • reaching into high cupboards
  • caring for children who need to be picked up.

Once your wound has healed its important that you build regular physical activity back into your lifestyle. See our section on exercise with an ICD for more information.

Cardiac rehabilitation classes and local cardiac support groups can help your recovery.

Complications and risks of getting an ICD

Sometimes people worry about the risk of having an ICD, but the benefits of having an ICD far outweigh the risks. Your medical team will discuss these risks with you before your procedure.

The monitoring system will check that your ICD is working correctly. If you think it's not, contact your ICD clinic.

What happens when an ICD gives a shock?

Most of the time you won't feel the ICD monitoring you. If your heart is in danger of stopping, the ICD will give you a shock. Before this happens, some people feel dizzy, have a racing heart or might collapse. The shock feels like a thump or a kick in your chest or back.

Rest for a while after the shock has been delivered. Go to your nearest emergency department if you continue to feel unwell. If you feel ok, it's still important to contact your ICD clinic.

Can an ICD always prevent a heart from stopping?

An ICD is programmed to correct fatal heart rhythms that cause cardiac arrest, but in some cases this is not possible.

However, along with correct medication and recommended lifestyle changes, an ICD can significantly reduce your risk of dying from a cardiac arrest.

Living with an ICD

When you first get the ICD, it may take a while to get used to. You can feel it under your skin and you might be able to see a bump on your chest. Your wound should be fully healed after a couple of weeks.

Returning to work

Most people can return to work a few weeks after the ICD has been put in.

If you have a job that involves heavy lifting or other intense exercise, you'll need to talk to your medical team and your employer about when you can safely return to work. You might need to be on 'light duties' until you’ve been cleared by your ICD team at your follow up.

You'll also need to talk to the team if you work in an environment with strong magnetic fields.

Can you drive with an ICD?

You won't be allowed to drive for a while after your ICD has been put in.

If you've had a cardiac arrest, you won't be allowed to drive for six months or longer.

If you haven't had a cardiac arrest, it will be at least two weeks.

Check with your doctor and your insurance company before you drive. If your job involves driving, discuss this with your specialist.

You can find out more on the NZTA website.

Mobile phones and ICDs

Keep your mobile phone away from your ICD. Use the opposite ear and don't keep your mobile in a pocket over the device.

Follow up clinic appointments

You'll have appointments every few months to check the ICD and the battery life. The battery can last up to seven years. You'll have a new battery fitted in hospital before the old one runs out.

Sex with an ICD

In the first few weeks after you get your ICD, you'll need to avoid positions that put pressure on your arms and chest.

It’s unlikely you'll get a shock during sex because the ICD is programmed to cope with normal rises in heart rate.

A lot of people feel anxious having sex again after the ICD has been fitted. This is normal. If you're worried, please speak with your ICD team.

Exercise with an ICD

You may need to take it easy in the first few weeks after your ICD procedure. You'll need to avoid heavy lifting and raising your arm above your shoulder for up to six weeks on the affected side. You'll need to avoid sports that involve arm movements, like swimming or golf.

Once you've recovered from your procedure and you’ve got the all clear from the medical team, it’s important to add regular activity back into your daily life.

Cardiac rehabilitation classes are a great way to get back into physical activity. You could also get a green prescription (a free service which provides exercise advice for people with chronic health conditions).

There may be some intense physical activities or contact sports that you can’t do, or that you’ll need to take precautions for. Talk to your team about what’s safe for you.

If you weren't physically active before the ICD, it's important you slowly build up your activity until you're doing about 150 minutes a week. That's about 30 minutes, five days a week. Keeping fit is an important way of reducing your risk of future heart events.

Some people with ICDs avoid exercise because they're worried it will trigger a shock from the ICD. But research has shown that people with ICDs who exercise regularly, improve their fitness and have less ICD shocks.

Travel with an ICD

If you're going on holiday, remember to take your ICD identification card with you. This contains information about your particular type of device.

Can you fly with an ICD?

It’s important to have your ICD identification card with you when going through airport security. Make sure security staff don't hold the hand-held metal detector directly over your device.

In some countries you may still be asked to walk through the security system. This shouldn't be a problem, but it is best to walk through quickly.

What equipment should I avoid with an ICD?

Read the instructions that come with your ICD. As a general rule, you'll need to avoid:

  • Magna-sleeps electric blankets
  • CB radio equipment
  • loudspeakers (must be 30cm away)  
  • magnetic bracelets
  • electrolysis for hair removal
  • electric arc welders
  • high power radar or electrical installations in close range
  • TENS machines.

What should I ask my doctor about living with an ICD?

Here are some things you might like to discuss with your doctor before or after your ICD is put in. You could also take a support person with you.

  • Will I still need to keep taking my heart medications?
  • Are there any cardiac rehabilitation classes or local ICD support groups nearby?
  • Can I keep working?
  • What exercise can I do?
  • When can I drive?
  • How often will I need follow up appointments?
  • What do I need to avoid?

What should I do if I'm worried about my ICD?

If you're worried about your ICD contact your local ICD clinic. If you are feeling unwell seek medical attention.

What's it like to have an ICD?



"My ICD gives me a real sense of security and it lets me do things I haven't done since I started getting heart rhythm problems."

It may take some time to get used to having an ICD and it's quite normal to experience mood swings. It's also common to feel very emotional if you've just been diagnosed with a heart condition or suffered a heart event.

Talk to your doctor or nurse about this, especially If these feelings last for more than a few weeks.

Sometimes it's helpful to hear from other people living with an ICD. Cardiac rehabilitation classes or local cardiac support groups are a great way to meet people who have had similar experiences.

You can also read stories from people who have an ICD on our Journeys pages.

Read ICD stories