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Implantable Cardioverter Defibrillator

Implantable Cardioverter Defibrillator - What it is

​An implantable cardioverter defibrillator (ICD) (also known as automatic implantable cardioverter defibrillator (AICD) is an electronic device implanted just under the skin of the upper chest, similar to a pacemaker. It is about the size of a pager and performs several functions. It monitors your heart rhythm continuously. Upon detection of a dangerous rhythm (ventricular tachycardia (VT) and ventricular fibrillation (VF)), the device will either pace or deliver a shock to terminate the dangerous rhythm. The ICD protects patients at risk from premature deaths due to life threatening heart rhythm. It can also pace the heart when the rate is too slow.

Implantable Cardioverter Defibrillator - Symptoms

Implantable Cardioverter Defibrillator - How to prevent?

Implantable Cardioverter Defibrillator - Causes and Risk Factors


The risk of implantation is estimated to be about 1%, including excessive bleeding, pneumothorax (air leak from the lung), cardiac perforation, long term risk of infection and device malfunction.

Implantable Cardioverter Defibrillator - Diagnosis

Implantable Cardioverter Defibrillator - Treatments

What does an AICD look like? How does it work?

The AICD consists of two parts: first, a box which houses the electronics (the “device”), and second, one or more wires that connect the box to the heart muscle (the “leads”).

implantable cardioverter defibrillator

This is what an actual AICD looks like. The maximum diameter is around 2 to 3 inches i.e. around the length of your small or ring finger.

implanted aicd

Shown here is what a freshly implanted AICD looks like. The incision used to implant the device is around 5 cm long. Usually it is implanted on the left side; occasionally it is implanted on the right side.

Why does my doctor think I need an AICD?

Your doctor will recommend an AICD if he thinks you are at risk of developing dangerous abnormal heart rhythms (“VT” or “VF”) and therefore at risk of sudden death. This may be because:

  • You have already developed VT or VF once before, and are at risk of further episodes of VF or VT
  • You have never developed VT or VF before, but your heart muscle function is poor and is therefore prone to developing VT or VF; doctors often measure heart function using a number called the ejection fraction (EF) - you may hear them talking about “poor EF”
  • Or you have been diagnosed with one of a number of uncommon syndromes that may predispose you to VT or VF (e.g. Brugada syndrome, long Q-T syndrome, hypertrophic cardiomyopathy, idiopathic VT).

Who and where will the AICD implantation be done?

A specialist doctor called an Electrophysiologist will perform the procedure. The procedure will be done in the Electrophysiology Lab.

Is AICD implantation procedure safe?

A device implant is generally a safe procedure. However, as with any invasive procedures, there are risks. Special precautions are taken to decrease your risks.

Your doctor will discuss your risk with you as every individual is different. In general however, the risk of implanting an AICD is low - only 1% or less of serious complications. These include (but are not limited to):

  • Infection of the AICD which, if serious, may need removal of the AICD altogether
  • Bleeding
  • Pneumothorax (“collapsed lung”)
  • Cardiac perforation
  • Device malfunction

All of these complications are treatable. However, the most common problem with AICDs is that they may deliver unnecessary shocks; if so, your AICD may need to be re-programmed or your medication altered.

What are the benefits to me if I agree to have an AICD implanted?

The purpose of the AICD is to protect you from sudden cardiac death due to abnormal heart rhythms; your doctor will normally only recommend one if he thinks this risk substantially outweighs the low risk of AICD implantation.

Are there different types of ICD?

Yes. Your doctor will determine the best suitable device for you, depending on your condition.

types of icds

Implantable Cardioverter Defibrillator - Preparing for surgery

If I decide to have an AICD, when will I be admitted for the implantation procedure? How long can I expect to be admitted for?

Your doctor will arrange a date for you to be admitted to the hospital. Usually you are admitted on the day of the procedure; occasionally, you will be admitted the day before. Most patients can expect to be discharged the following day; occasionally, your hospital stay may be longer if the procedure is difficult or complicated.

Do I continue to take my medications till the day of the procedure?

Your doctor should already have instructed you on what to do before the procedure.

Please check before discontinuing any medications. The following information is a general guide only.

If you are on warfarin, this will normally need to be discontinued around 5 days prior to the procedure, and a blood test (“INR”) taken to confirm that your blood clotting is normal prior to implantation.

If you are taking aspirin or clopidogrel (Plavix), you may be asked to discontinue one or both of these prior to implantation; however, please confirm this with your doctor.

You can normally continue taking your other medications as usual.

Can I eat before the procedure?

In most cases, you will be told to eat a normal meal the evening before your procedure. However, do not eat, drink or chew anything after 12 midnight before your procedure. This includes gum, mints, water, etc. If you must take medications, only take them with small sips of water. When brushing your teeth, do not swallow any water.

What should I wear?

When getting ready, please do not wear makeup and remove nail polish. Wear comfortable clothes when you come to the hospital. You will change into a hospital gown for the procedure. Please leave all jewelry (including wedding rings), watches and valuables at home.

What happens before the procedure?

Before the procedure begins, a nurse will help you get ready. You will be given a hospital gown to change into. You may keep your clothes in a locker or you may give them to a family member.

You will lie on a bed and the nurse will start an IV (intravenous) line in a vein in your arm or hand. The IV is used to deliver medications and fluids during the procedure.

To prevent infection and to keep the device insertion site sterile:

  • An antibiotic will be given through the IV at the beginning of the procedure
  • The left or right side of your chest will be shaved
  • A special soap will be used to cleanse the area
  • Sterile drapes are used to cover you from your neck to your feet
  • A soft strap may be placed across your waist and arms to prevent your hands from touching the sterile area

Implantable Cardioverter Defibrillator - Post-surgery care

What can I expect immediately after the AICD is implanted?

You will return from the Electrophysiology Laboratory with pressure dressing over the site of the AICD implant. If you have any pain, please inform your nurse so you can be given enough painkillers.

You will stay overnight in the hospital and usually will be able to go home the day after the device is implanted.

What tests will be done after the procedure?

A chest x-ray will be done after the device implant to check your lungs as well as the position of the device and lead(s).

The following day, an Electrophysiology Technician will confirm your AICD is working properly; this is done on the ward, from outside the body.

If there are no problems, you can expect to be discharged the following day with a return appointment in one week. You may also be given a short course of antibiotics to prevent infection.

Do I need long term follow up?

You will need long term follow up. Initially you will be seen at four to six weeks intervals to check the AICD is functioning as intended. If there are no problems, the follow up interval may be lengthened to every three months or more.

Are there any special precautions I must take after an AICD is fitted? Do I need to modify my lifestyle in any way?

After the AICD is implanted, you will need to keep the implant site clean and dry while the overlying skin heals. On discharge from the ward, the nurses will arrange regular dressing changes.

For two to three weeks after implantation, you should also avoid raising your arm on the side of the implant above shoulder level to avoid dislodging the lead or device. After two to three weeks have elapsed, the lead and device should be secure so that this is no longer an issue and you can move your arm normally.

There are few restrictions from having an AICD. Most sports are permitted except contact sports such as rugby where vigorous impact could damage the AICD.

Swimming is permitted but we do advise common sense precautions such as not swimming in deep water alone.

Will I be able to drive myself home after the procedure?

No. For your safety, a responsible adult should drive you home. Ask your doctor when you could resume driving.

The AICD is battery-powered. How often does the battery need changing and how is it changed?

Most AICDs will last around three to six years or more. We will check on the battery status during your regular clinic follow ups. Changing the battery is similar to implanting a new device except the AICD leads (the wires which connect the device to the heart) do not need to be changed.

What instructions will I receive before I leave the hospital?

Your doctor will discuss the results of the procedure and answer any questions you have. Be sure to ask the doctor if you can continue taking your previous medications.

You will receive specific instructions about how to care for yourself after the procedure including medication guidelines, wound care, activity guidelines, device care and maintenance, and a follow-up schedule.

Should I carry my identification card (ID) with me all the time?

Yes. Your ID card contains pertinent information about yourself, type of AICD and your physician.

This is made available quickly in the event of an emergency. If you lose your card, please ask for a replacement.


What should I do if I receive shock therapy?

You should always follow your doctor’s instructions about receiving therapy.

Go to A&E or call 995 if you do not feel well or if there are more than 2 shocks delivered in the same day.

Can I travel with an AICD?

You can travel with an AICD. However, you should discuss your travel plans with your physician as there may be other important medical considerations.

Is it a problem if I walk through airport, shopping or courtroom security metal detectors?

The amount of metal used in most AICDs is very small and not usually enough to set off the detector alarm. If it does, inform the security personnel that you have a AICD implanted, and show them your patient identification card.

Passing through the metal detector portal will not harm your device; however do not linger near it as the magnetic field may temporarily interrupt the normal function of the device.

My doctor has advised me to have a “scan”. Is this safe if I have a AICD implanted?

Ultrasound scans (including echocardiograms), as well as X ray scans (including CT scans) do not affect the function of your AICD; you may proceed with these normally.

However, you should not have MRI (magnetic resonance imaging) scans. Such scans use very strong magnetic fields which can affect the function of the AICD.

What must I do when the ICD emits a warning tone?

Keep calm. It is only an indication that you should contact your doctor. If you hear a continuous tone at high frequency, the situation is not urgent; you should phone your doctor and arrange an earlier appointment. However, if you hear a double high and low frequency tone, you must inform your doctor and arrange to see him immediately.

During out-of-hours period, please do visit the A&E.

Implantable Cardioverter Defibrillator - Other Information


Implantable Cardioverter Defibrillator (ICD)

Cardiac Device Home Monitoring Service


The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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