Implantable cardioverter defibrillator (ICD)

An ICD is a device that monitors and treats dangerous heart rhythms. Find out how an ICD works, how it’s implanted, and what to expect when living with an ICD.

Close-up of implantable cardioverter defibrillator (ICD) device held in front of heart rhythm ECG monitor screen.

In this article

What is an ICD?

An ICD (implantable cardioverter defibrillator) is a small device that can detect and correct dangerous fast heart rhythms by giving a shock to reset the heart to a normal rhythm, preventing your heart from stopping (cardiac arrest).  

A standard transvenous ICD has two main parts. 

  • A pulse generator: an electronic circuit and long-lasting battery in a metal case. It is usually placed under the skin on your chest. 
  • One or more leads (thin wires). These connect the pulse generator to your heart. 

The pulse generator is small enough to fit in the palm of your hand.

Why do I need an ICD?

Your heart beats to keep blood moving around your body. The pattern is controlled by your heart’s electrical conduction system. If the electrical system doesn’t work as it should, it may make your heartbeat dangerously fast. Some abnormal heart rhythms can cause your heart to stop beating (cardiac arrest).   

An ICD resets the heart to a normal rhythm, preventing your heart from stopping.  

You may need an ICD if you’ve had a cardiac arrest or have a heart condition that increases your risk of cardiac arrest, including: 

Not everyone with these conditions will need an ICD.

How an ICD works

Your ICD monitors your heart rhythm all the time. If it detects a heart rhythm disorder, a transvenous ICD can send a small electrical signal to your heart to correct the rhythm. This is called pacing. 

If the ICD detects a dangerous heart rhythm and your heart is at risk of stopping, it gives an electric shock to reset your heartbeat to a normal rhythm. This is called defibrillation. 

Types of ICD

Transvenous ICD

A standard transvenous ICD is the most common type. It is implanted under the skin on the chest with leads attached to the heart through the veins. It can provide pacing and defibrillation.

Diagram of transvenous implantable cardioverter defibrillator (ICD) with pulse generator under the skin and electrodes threaded through a vein into the heart

Subcutaneous ICD

A subcutaneous ICD (S-ICD) is another type of ICD. It is implanted under the skin on the side of the chest below the armpit, with a single lead under the skin. The electrode that delivers the shock sits outside the ribcage, not in the heart. An S-ICD is not suitable for patients who need heart rhythm pacing.

Medical illustration of subcutaneous implantable cardioverter defibrillator (S-ICD) showing device and lead positioned outside the ribcage next to the heart.Image provided courtesy of Boston Scientific. ©2026 Boston Scientific Corporation or its affiliates. All rights reserved.

Other ICDs

Due to advances in technology, new types of ICDs are currently being developed, such as the extravascular ICD (EV-ICD).

How do I get an ICD?

Your doctor will refer you to a cardiologist (heart specialist). Your cardiologist will talk with you about what type of ICD is right for you. They will then refer you to a hospital to have it fitted.  

Sometimes people worry about 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. 

How is a transvenous ICD implanted (fitted)?

Before the procedure:

  1. Your cardiology team will ask if you’re on blood thinners. You may need to stop taking them for a short period of time.  
  2. 1–2 days before the procedure you’ll need to have a blood test. 
  3. You may also have other tests (ECG, chest x-ray, or echocardiogram (echo)). 
  4. You might be given antibacterial sponges and iodine nasal swabs to use the night before and morning of your procedure.     
  5. Take your usual medications on the day unless you’ve been told not to.

During the procedure:

  1. You’ll be given medication to help you relax. You’ll 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 be given a general anaesthetic. 
  2. A small incision (cut) will be made near your collarbone to place the ICD under your skin.   
  3. The lead/s are inserted into a vein near your shoulder and gently guided down into your heart.   
  4. The leads are attached to the inside wall of your heart.  
  5. X-rays are taken to check the leads are in the right place. 
  6. The leads are tested and connected to the ICD. 
  7. The cut is closed with stitches that dissolve on their own, and skin glue.

When can I go home?

Having an ICD implanted usually involves an overnight stay in the hospital. Some people may be able to go home the same day. You’ll need someone to drive you home. 

The procedure usually takes a few hours but can vary.  

Your ICD will be checked afterwards. One of the clinical team will explain how the ICD works.  

Before you go home, your cardiology team will let you know which medications are safe to take if you have any pain or discomfort after the procedure.  

Ask when to expect your follow-up appointment.

Recovery from your procedure (the first six weeks)

You might feel sore or have bruising for a few days. Serious problems are rare. It’s normal to feel tired at first, but most people find they’re able to get back to their normal lifestyle quickly.

Caring for your wound

ICD wound care instructions infographic with icons explaining to keep the wound dry, avoid plasters creams or talcum powder, and not to touch the wound.
  • Keep your wound dry for 5–7 days.  
  • Don’t use plasters, creams or talcum powder on the wound.  
  • Avoid touching the wound. It’s important not to pick at the glue or stitches so your skin can heal.

Call your doctor or cardiac device clinic immediately if you notice:   

  • symptoms like the ones you had before getting an ICD 
  • hiccups or twitching in your chest  
  • your heart feels like it’s racing 
  • your wound becomes red, swollen, hot, painful or leaks (this could mean an infection) 
  • you have a high temperature for no obvious reason. 

What should I avoid?      

While you’re healing after ICD surgery infographic showing activities to avoid and everyday tasks to get help with, including heavy lifting, sports, washing hair and reaching high cupboards.

It takes a few weeks for your ICD leads to become secure. While you’re healing:     

  • avoid heavy lifting  
  • avoid raising your arm above your shoulder   
  • avoid sports and activities that involve arm movements, like swimming and golf  
  • you may need help with everyday tasks like hanging out the washing, reaching into high cupboards, washing your hair or getting dressed 
  • you will need help caring for children who need to be carried.  

If you notice any problems with your ICD at any time, call your cardiac device clinic right away. 

When can I start driving again?

You won’t be allowed to drive for a while after your ICD is implanted. It’s important you don’t drive until your cardiologist or cardiac device clinic says it’s safe for you to drive. 

The New Zealand Transport Agency (NZTA) states you should not drive for six months after having an ICD fitted. After six months you should have a specialist assessment to check it’s safe for you to drive again.  

If your job involves driving a large vehicle, like a truck or bus, you must have a specialist assessment before you start driving. 

You should also avoid driving when your ICD: 

  • gives you a shock: avoid driving for six months 
  • batteries are changed: avoid driving for four weeks.

When can I return to work?

Most people can return to work a few weeks after getting an ICD. 

If your job involves heavy physical labour, lifting or driving large vehicles, talk to your doctor about when to return to work. You might need to be on ‘light duties’ until you’ve been cleared by your ICD team at your follow-up appointment. 

Check with your cardiologist or cardiac device clinic if you work in an environment with strong magnetic fields as this may affect your ICD.  

Important: If you feel dizzy or unwell near a device or appliance, move away from it and check with your cardiac device clinic.

Life with an ICD

You will have regular follow-up at your local cardiac device clinic to check your ICD and its battery life. If you have remote monitoring, you may need to visit the clinic less often. 

Home (remote) monitoring 

Some ICDs have remote monitoring. This means the cardiology team can check your ICD data from their office while you’re at home. Your data is not monitored all the time, it is just reviewed by your cardiology team before your appointment. 

Your cardiology team will discuss this option with you if: 

  • they think it will benefit you  
  • you have good mobile phone coverage at home.  

If you have remote monitoring, you might need less frequent visits to the cardiac device clinic.  

ICDs with remote monitoring use Bluetooth or an antenna to send information to a small monitor by your bed. Some can also connect to an app on your phone. The data is sent safely over a mobile phone network to the ICD company, which creates a report for your cardiology team. 

If your ICD is inserted at a private hospital, your follow-up care is usually done at your local public hospital.  

How long does an ICD battery last? 

Most ICD batteries last from six to ten years. A new ICD will be fitted before the old battery runs out. This is done in hospital. You won’t be able to drive for four weeks afterwards. 

What happens when your ICD gives a shock? 

Most of the time you won’t feel the ICD monitoring you. The ICD will give your heart a shock if it is at risk of stopping beating. 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 receiving the shock. It’s important to contact your cardiac device clinic, even if you feel ok. They will check if the ICD needs reprogramming and that your heart health is stable. Go to your nearest emergency department if you continue to feel unwell.  

Exercising with an ICD 

You can return to exercise after you have clearance from the cardiac device clinic. Being active is great for your heart and helps with your recovery.  

You may need to take it easy in the first few weeks after your ICD procedure. 

For the first six weeks, focus on low-impact exercises like walking and gentle cycling while you heal. Avoid heavy lifting, pushing, pulling or activities that involve swinging your arm.      

Remember to warm up and cool down to prevent injuries.  

You should avoid most contact sports, but check with your doctor about what’s safe for you. 

Important: If you feel chest pain, dizziness or shortness of breath while exercising, stop right away and consult your doctor or nurse.   

ICDs are designed to allow for normal increases in heart rate during physical activity so you’re very unlikely to get a shock, unless a life-threatening heart rhythm occurs. 

Cardiac rehabilitation classes can be a great way to get back into physical activity. You could also get a green prescription, which is a free service providing one-to-one support to help you increase your physical activity. 

Sex with an ICD 

A lot of people feel anxious having sex after getting an ICD. This is normal.  

It’s unlikely you’ll get a shock during sex because the ICD is designed to allow for normal increases in heart rate. 

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

ICD identification card  

You’ll be given an identification card (ID) for your ICD. Always carry this card and a list of your medications. You may also consider getting a MedicAlert bracelet.  

You may need to show your ID card when walking through metal detectors, for example, at an airport. 

Travelling with an ICD 

If your ICD has remote monitoring, and you are going to be away for more than three weeks, inform your local cardiac device clinic. 

Take your ICD card with you when travelling. 

Most airport body scanners are safe, but always tell security staff you have an ICD. Ask them not to hold the hand-held metal detector over your chest. 

Using electronics with an ICD 

Most everyday electronic devices are safe with modern ICDs. 

Some larger devices can send out strong electrical signals. If a device makes you feel dizzy or lightheaded, or you notice an unusual heartbeat, move away from it. If you’re unsure if a device is safe, ask your cardiac device clinic. 

Mobile phones  

When using a mobile phone use the opposite ear from your heart. Don’t put mobile phone, earbuds or earphones in a chest pocket. Don’t wear earphones around your neck.   

MRI scans 

Magnetic resonance imaging (MRI) scans use strong magnets to create images of the inside of your body. Most modern ICDs are safe with MRI scans, but will need special programming during the scan. The MRI centre will check with your cardiac device clinic prior to your scan to ensure it is safe.  

Avoid other strong magnets or places with strong magnetic fields.

Other medical procedures

Tell your healthcare team you have an ICD before any medical procedure or treatment. Your ICD may need to be checked before and after.   

If you have any problems with your ICD after a procedure, let your cardiology team know as soon as possible. 

What's it like to have an ICD?

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

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

Read ICD stories