Implantable Cardioverter Defibrillator (ICD)


What is an Implantable Cardioverter Defibrillator (ICD)?

An implantable cardioverter defibrillator, or an ICD, is a small battery-powered device placed in the chest to detect and stop irregular heartbeats (arrhythmias). It treats your arrhythmia and prevents your heart from beating too fast (tachyarrhythmia) or too slowly (bradycardia). An ICD continuously monitors 24/7 your heartbeat and delivers small, painless electric shocks, when needed, to restore a regular heart rhythm. 

Your cardiologist may recommend an ICD if you’ve had signs or symptoms of a certain type of irregular heart rhythm called sustained ventricular tachycardia, including fainting. An ICD might also be recommended if you survived a cardiac arrest.

An ICD consists of a pulse generator, or defibrillator, and leads. The defibrillator is like a small computer that runs on a battery. The battery and circuitry are sealed inside a titanium case. The leads are insulated wires that connect the defibrillator to your heart.

What is the difference between an ICD and a pacemaker?

A pacemaker and an implantable cardioverter defibrillator (ICD) are similar – they are both medical devices that are implanted in the chest to help regulate the heartbeat. However, there are some important differences between the two devices. An ICD is primarily used to treat fast and potentially life-threatening heart rhythms, such as ventricular tachycardia or ventricular fibrillation and is also able to detect abnormal heart rhythms and deliver a shock to the heart to restore a normal rhythm. A pacemaker is primarily used to treat slow heart rhythms, such as bradycardia. It works by sending rhythmic electrical impulses to the heart to regulate the heartbeat.

The defibrillator continually monitors your heart rhythm and has been programmed by your cardiologist to respond in specific ways to treat your arrhythmia. Your cardiologist uses a specific  programmer to communicate with your ICD via radiofrequency waves using a magnet over your chest. The programmer is used by the cardiologist to adjust the settings of your ICD so that it is fine-tuned to your specific needs. The programmer also reads information contained in the ICD – it stores the records of all of your heart rhythm. Detailed data, including date and time, is provided by the ICD regarding any rapid or slow rhythms you may have had and how they were treated by your device.

There are three ways the ICD may be programmed by your cardiologist, depending on the problem with your heartbeat. The three ICD programming functions include:

1. Pacing
2. Cardioversion and
3. Defibrillation.

Pacing may be used to treat slow or fast rhythms. If your heart beats too slowly or (below a limit set by your cardiologist), your ICD will detect this and will deliver pacing impulses to stimulate your heart. It will continue to do this until your heart starts to beat at a normal rate on its own.

Your cardiologist may also program your ICD to deliver a sequence of pacing impulses as the first step in the treatment of a rapid heart rhythm. One particular form of rapid heart rhythm that is treated this way is called ventricular tachycardia (VT). If normal rhythm is restored no further treatment is delivered.

Most people do not feel these impulses and may not be aware that pacing is occurring. If the pacing is to stop VT, you may feel a slight fluttering sensation in your heart. Clinical data suggests that around 90% of VTs are stopped by pacing.

If pacing does not stop the arrhythmia, the ICD will deliver the next therapy – cardioversion. This involves delivering stronger electrical impulses to the heart muscle. Cardioversion shocks may progress from low energy to high energy as needed.

Most people say this is mildly uncomfortable and describe it as a sharp thump to the chest.

This is similar to cardioversion, but delivers a stronger high energy shock to your heart. This is used when pacing and cardioversion have not been successful in treating VT. It is also always used first to treat a different form of rapid heart rhythm, ventricular fibrillation (VF). VF is where several areas of the heart muscle are contracting in a disorganised and erratic manner. If this happens the heart muscle quivers and the heart no longer pumps any blood at all. The body quickly becomes starved of oxygen and you would usually pass out within a few seconds. This situation is called cardiac arrest.

The electrical current from the ICD during defibrillation passes through the heart, shocking your heart out of VT or VF and stopping the erratic electrical activity allowing the heart to return to a more regular rhythm within those first crucial seconds.

Often the person has lost consciousness when this therapy is delivered, so they are not aware of it occurring. People who have experienced a defibrillation shock whilst conscious describe it feeling like a “kick to the chest”. They say it startles them and is distressing but only lasts for a second.

How to prepare for a Implantable Cardioverter Defibrillator (ICD)

Your preparation for an ICD may include diagnostic tests to gather information about your heart rhythms. You may have already had these prior to admission. These tests may include: a blood test, a 12 lead Electrocardiograph (ECG), or a Cardiac Electrophysiology Study (EPS).

Your doctor will advise you if any medication needs to be ceased prior to the procedure. You will be required to fast for six hours prior to the procedure. Male patients will be required to have their chest shaved. You will have a cannula inserted and connected to a drip. Before the procedure, you will be given a sedative to help you relax.

What happens during an Implantable Cardioverter Defibrillator (ICD) procedure

The ICD procedure will be performed in the cardiac catheter theatre by a specialist cardiologist and should take approximately two hours. It will be performed under a local anaesthetic.

The ICD leads will be implanted transvenously, meaning they will be inserted through a vein, in the left upper chest region. The lead is then threaded through the vein to the appropriate chamber in the heart.

After the leads are in position, they are secured and connected to the pulse generator which is positioned on the left side of your upper chest.

During the procedure, the ICD may be tested to ensure it can detect and successfully treat VF. During this time you will be given a light anaesthetic.

What happens after an ICD procedure

Following your procedure, you will return to the ward and be monitored overnight.

Your ICD will be checked the following morning by your cardiac doctor or pacemaker technician. The monitoring leads will be removed once your device has been checked. It is normal to still experience some pain at the insertion site. This should be eased by taking paracetamol.

You will have a dressing over your wound site and will be advised on how to care for this by the nursing staff. The dressing will be removed three days after you are discharged, then the site will be left uncovered. You do not need to have any stitches removed as they are dissolvable.

Most people will be discharged from hospital the following day. Your doctor will advise you on your follow up appointments prior to discharge.

By the time you are discharged, you may feel emotionally and physically drained. This is quite normal, and will improve as you recover. Most people can return to their usual activities after a few days, although driving and heavy lifting might be restricted for a time.

How will the ICD affect my life?

Your doctor will advise you on what you should and should not do when you return home. Once you have fully recovered, you should be able to confidently resume all your normal activities.

You can safely use all common household appliances including microwaves, televisions, computers etc.

Depending on your condition, your doctor may advise you to avoid activities during which a few seconds of unconsciousness may be dangerous to you or others. These may include driving, climbing a ladder or boating alone.

Remote Monitoring Service

QCG offers a remote monitoring service that enables ‘virtual check-ups’ for your implanted device. This allows you to directly and securely transmit data from your device to your cardiologist from the comfort of your own home. This enables us to detect significant events such as an abnormal heart rhythm, monitor the performance of your device such as battery life, and optimise your care through device programming or medication change.

Your participation in remote monitoring allows us to follow your device function between visits, and in some situations, it may replace office visits. This means less time spent at the doctor’s office for regular checks, faster time to treatment if your cardiologist detects a medical problem and faster troubleshooting if a problem is detected with your device. Research evidence has shown that early detection of issues through remote monitoring leads to improved health outcomes and a reduced risk of hospital admission. It also allows you to monitor your own heart rhythm and quickly detect any irregularities or arrhythmias.
For more information visit Remote Monitoring Service.

ICD Frequently Asked Questions

In Australia, people with ICDs can drive, but there are some requirements that need to be met including that they must have had a medical assessment by a specialist cardiologist, who has deemed them fit to drive.

The Australian Fitness to Drive Guidelines state that a person who has an ICD implanted for ventricular arrhythmias is not fit to hold an unconditional licence.

A conditional licence may be considered by the driver licensing authority subject to periodic review, taking into account the nature of the driving task and information provided by the treating specialist as to whether the following criteria are met:

• the ICD has been implanted for an episode of cardiac arrest and the person has been asymptomatic for six months; or
• the ICD has been prophylactically implanted for at least two weeks; and
• there are minimal symptoms relevant to driving (chest pain, palpitations, breathlessness).

A person with an ICD implanted should not drive:
• for two weeks after a generator change of an ICD;
• for at least four weeks after appropriate ICD therapy associated with symptoms of haemodynamic compromise i.e. blackout, faint. 

Yes, you can travel through an airport with an ICD (Implantable Cardioverter Defibrillator) fitted. As you pass through Airport security you should declare to security staff that you have an ICD.

Here are some important things to keep in mind if you plan to fly with your ICD:

Inform the airport security:
• You should inform the airport security staff that you have an ICD implant before you go through the metal detector or the body scanner. You can show them your device identification card.
• Note: If you do walk through the metal detector, this will not cause harm to the ICD or yourself however it will set of the metal detector alarm.

Carry your device information:
• You should carry your device identification card that contains the information about your implanted device, including the manufacturer’s name, model number, and serial number.

In general, swimming and other water activities can be safe for people with ICDs, after the first week post device implant, once the skin has healed.
If you have had an ICD implanted due to ventricular arrhythmias, you should have another person with you when you swim in case a dangerous ventricular arrhythmia occurs whilst swimming.

If you have concerns or questions please talk to your cardiologist.

ICDs are intended to be implanted permanently in order to reduce the lifelong risk of sudden cardiac death.

While many electronics are generally safe to use, there are some types of equipment that can potentially interfere with the functioning of an ICD.

The primary concern with electronics and ICDs is electromagnetic interference (EMI). EMI can trick the ICD’s ventricular arrhythmia detection algorithm into thinking that a dangerous arrhythmia has commenced. This can then lead to the ICD delivering an unnecessary or inappropriate shock.

Some examples of electronics that may produce EMI include:

Cell phones: Although modern cell phones are generally safe to use, it is recommended that people with ICDs hold the mobile phone at least 12 cm from mobile the ICD. It is still safe to have the phone at your ear on the side that the ICD is implanted on. It is important to not put the mobile phone in a breast pocket on the same side as the ICD.

Security screening equipment: Metal detectors used in airports and other security checkpoints can potentially interfere with ICDs but only if a person was to stand still within the metal detector gate for more than 10 seconds. If a person walks straight through the metal detector gate without pausing, there is no risk of electromagnetic interference. The metal detector gate will likely alarm when a person who has an ICD walk through it as it detects the metal in the device. Please notify airport staff at the security checkpoint and an alternative means of performing a security check will be offered.

Electronic medical equipment:
Current model ICDs are MRI compatible. Your cardiologist will have the details of your device and be able to tell you if you are device is MRI compatible.

This activity can create significant electromagnetic interference and can be a problem for people with ICD is implanted. You will need to check with your cardiologist for an assessment of your particular risk regarding this activity.

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