FAQ

Abbott ICDs (formerly St Jude Medical) have traditionally alerted you by vibration rather than sound. A typical pattern is a six-second vibration, then sixteen seconds of silence, then a further six-second vibration, then ten seconds of silence, after which the pattern repeats.

Historically, many Abbott devices had no patient alert at all. The newer Gallant models have added an audible alert facility, so a Gallant device may beep as well as vibrate.

If you feel an unexpected vibration from your device, contact your ICD clinic, and ask for a demonstration at your next appointment. Our ICD sounds and alerts page explains the alerts by manufacturer.

Boston Scientific ICDs use audible alert tones. A typical alert is a set of sixteen tones that repeats roughly every six hours until the device is checked.

It is worth knowing that having an MRI scan permanently disables the beeper on these devices. If that applies to you, your clinic will usually recommend relying on remote monitoring so that alerts are still picked up.

If you hear an alert, contact your ICD clinic. To hear what your device sounds like, ask for a demonstration at a clinic visit. Our ICD sounds and alerts page has more detail.

Medtronic ICDs can alert you with both audible tones and vibration. A common pattern is a six-second vibration, then sixteen seconds of silence, then a further six-second vibration, then ten seconds of silence, after which the pattern repeats.

A solid, continuous tone is the magnet alert tone, which you may hear when a magnet is placed over the device. These tones are programmable, so your clinic can adjust them or switch them off, and your own device may sound different.

If you hear an alert, contact your ICD clinic. To hear exactly what your device sounds like, ask for a demonstration at your next appointment. Our ICD sounds and alerts page has example recordings.

No. Whether your ICD makes a sound depends on the manufacturer, the model, and how it has been programmed. Some devices beep, some vibrate, some do both, and some make no patient alert at all.

For example, Medtronic devices use audible tones and vibration, Boston Scientific devices use audible tones, and Abbott devices have historically used vibration, with audible alerts on the newer Gallant models. Biotronik and Sorin/Microport devices do not emit patient alerts and rely on remote monitoring instead.

If you are not sure what your device does, ask for a demonstration at your next clinic appointment. Our ICD sounds and alerts page lists the alerts by manufacturer.

A low-battery alert means your ICD’s battery is approaching the end of its life. The device emits a warning sound periodically, usually at the same time of day, so you may notice it as a regular daily beep.

This warning typically begins three to six months before the battery is depleted, so it is not an emergency. Contact your ICD clinic so they can check the device and plan a replacement, known as a generator or box change.

Our ICD sounds and alerts page explains the common alert types in more detail.

Patient alerts are rare and your ICD is usually silent, so a beep or vibration means the device wants to draw your attention to something.

The common reasons are a low battery, a fault with the device or a lead, a therapeutic shock having been delivered, a magnetic field interfering with the device, or the device being unable to reach your home monitor for a prolonged period.

You do not need to attend A&E for an alert unless you feel unwell. Contact your ICD clinic as soon as you can so they can check what triggered it. If you have also received a shock or feel unwell, treat it as urgent and seek help straight away.

Our ICD sounds and alerts page explains each alert type in more detail.

No, not in normal circumstances. Your ICD is programmed to deliver therapy only above a specific heart rate threshold, set well beyond what ordinary vigorous exercise produces. Raising your heart rate through exercise will not trigger an inappropriate shock.

Your device clinic takes your activity levels into account when programming the device, so tell them if you are returning to running, cycling or other demanding exercise. If you are ever shocked during or after exercise, stop, rest, and contact your device clinic or cardiology team the same day so they can review what the device recorded.

Most people with ICDs exercise regularly and without issue. The bigger barrier is usually confidence rather than the device itself, and that improves with gradual, consistent activity.

No, not in the conventional sense. This is the most clinically important difference between an S-ICD and a standard transvenous ICD.

An S-ICD can deliver brief post-shock pacing — a short burst of pacing in the seconds immediately after it has delivered a defibrillation shock, to prevent the heart pausing dangerously in that window. But it cannot provide ongoing bradycardia pacing (pacing that keeps the heart from beating too slowly on a continuous basis) or anti-tachycardia pacing (ATP, which is rapid pacing used to interrupt a fast heart rhythm before it needs a shock).

This means an S-ICD is not appropriate if:

• You have a slow heart rate that requires a pacemaker to maintain an adequate rate
• You have a type of fast heart rhythm that can be reliably terminated with ATP, which is less painful than a full shock

Some patients who need both ICD protection and pacing have an S-ICD combined with a separate leadless pacemaker (such as the Micra device), which sits inside the right ventricle and handles pacing without transvenous leads. This combination is used in selected cases where both subcutaneous defibrillation and pacing are needed but traditional transvenous leads are undesirable. Your electrophysiologist will determine which configuration is right for you.

An S-ICD is considered when someone needs ICD protection against life-threatening arrhythmias but does not currently require ongoing pacing therapy. It tends to be particularly well suited to:

• Younger patients, where avoiding transvenous leads reduces lifetime exposure to the complications those leads can cause over decades of use, including fracture, infection, and the need for lead extraction procedures
• People with congenital heart disease or unusual cardiac anatomy, where placing transvenous leads is technically difficult or carries higher risk
• Patients at elevated risk of device infection, where keeping leads out of the bloodstream reduces the chance of serious endovascular infection
• People who have already experienced transvenous lead complications, such as lead fracture or infection, and need a different approach

Before an S-ICD can be implanted, a sensing screening test is carried out to confirm that the device will be able to reliably detect the heart’s rhythm from the subcutaneous position. A small number of patients do not pass this screening and require a transvenous device instead. Your electrophysiologist will assess which type of device is most appropriate for your individual situation.

A standard ICD uses leads that travel through a vein into the heart chambers, where they sense the heart’s rhythm and deliver shocks if needed. A subcutaneous ICD (S-ICD) does not enter the blood vessels or the heart at all. Instead, the lead is tunnelled just under the skin, running alongside the breastbone, and the device generator is implanted under the skin on the left side of the chest, below the armpit.

Because there are no leads inside the heart or blood vessels, an S-ICD avoids several risks associated with transvenous leads: lead fracture within the bloodstream, damage to heart valves, and bloodstream infections (endocarditis). It is also generally easier to remove if the device ever needs replacing or explanting.

The most important limitation of an S-ICD is that it cannot deliver ongoing pacing therapy or anti-tachycardia pacing (ATP). It can only detect a dangerous rhythm and deliver a shock. If you need continuous pacing — because your heart rate is too slow, or because ATP is part of your arrhythmia management — an S-ICD would not be appropriate on its own. This distinction is assessed before a device is chosen.

Your device clinic monitors CRT-D function at regular check-ups, just as with a standard ICD. They use a programmer to review pacing data, check battery levels, assess how much of the time the device is delivering biventricular pacing (the percentage pacing figure), and adjust settings if needed. Remote monitoring between appointments allows the clinic to track this data without a visit.

From your perspective, CRT often produces noticeable improvements over weeks and months after implant: reduced breathlessness, better exercise tolerance, and less fatigue. These changes can be gradual rather than immediate. Response to CRT is not universal — roughly one in three patients does not experience the expected benefit, sometimes because the lead positioning is not optimal or because of underlying heart anatomy. If this appears to be the case, your clinic may adjust settings or consider lead repositioning.

If your symptoms worsen after a CRT-D implant rather than improving, or if you receive a shock, contact your device clinic or attend A&E. As with any ICD, any shock should always be reviewed.

A CRT-D is recommended when someone needs both ICD protection and cardiac resynchronisation therapy. This typically applies to people with heart failure where:

• The left ventricle’s pumping function is significantly reduced (usually an ejection fraction of 35% or below)
• The ECG shows a wide QRS complex, indicating that the two ventricles are not contracting in synchrony
• Symptoms persist despite optimal medical therapy

In this group of patients, biventricular pacing can improve symptoms, exercise capacity, and quality of life, and in some cases can partially reverse the structural changes in the heart. Clinical evidence shows that approximately two in three eligible patients experience meaningful benefit from CRT.

Not everyone who has had a cardiac arrest has heart failure, and not everyone with heart failure needs a CRT-D. A standard ICD may be perfectly appropriate. The decision is made by a specialist cardiologist or electrophysiologist based on your ECG, echocardiogram results, symptoms, and other clinical factors. If a CRT-D has been recommended for you, your team will explain the specific reasons.

A CRT-D (cardiac resynchronisation therapy defibrillator) is a device that combines two functions in one: a biventricular pacemaker and an implantable defibrillator.

The biventricular pacing component (the CRT part) sends precisely timed electrical signals to both the left and right ventricles, helping them contract in better synchrony with each other. In people whose ventricles are out of step — a condition that shows up on an ECG as a wide QRS complex — this can significantly improve the efficiency of the heart’s pumping action. The defibrillator component works exactly like a standard ICD: it monitors the heart rhythm continuously and delivers a shock if a life-threatening arrhythmia is detected.

A CRT-D typically has three leads rather than the one or two used in a standard ICD. The extra lead is positioned via the coronary sinus, a vein on the back of the heart, to pace the left ventricle directly. This three-lead system makes the implant procedure more complex than a standard ICD implant.

For most people, life with an ICD is largely unchanged, with some practical adjustments. The ICD monitors your heart rhythm continuously and will deliver a shock if it detects a dangerous rhythm. Most of the time you will not be aware it is there.

There are a few areas to be aware of. Driving is restricted initially, and the rules depend on several factors including the type of rhythm that caused your arrest. Certain sources of strong electromagnetic fields can interfere with an ICD, though the risk in everyday life is low. Some sports, particularly contact sports, need review with your clinical team. Your cardiologist or cardiac nurse specialist will go through the specifics with you.

What many survivors find hardest is the psychological adjustment: knowing that a device is watching your heart, and wondering what it means if it activates. Many ICD recipients describe an initial period of anxiety that eases considerably with time. Our site has detailed information on living with an ICD, and our community includes thousands of ICD recipients, many of whom have been living with one for years and are happy to share their experience.

Sudden Cardiac Arrest UK (SCA UK) is a registered charity supporting survivors of sudden cardiac arrest, their families, and the wider cardiac community. We provide information, peer support, and advocacy, and we connect people at every stage of life after a cardiac event.

Our website includes a comprehensive FAQ covering ICDs, cardiac arrest, CPR, driving, travel, and more. We also run an active online community for survivors, co-survivors, and those newly diagnosed with a cardiac condition.

If you would like to support our work, you can join the Friends of SCA UK programme. For a modest annual contribution, Friends help us fund new resources, reach more people, and keep the community running. Every Friend matters.

A precautionary ICD is still a significant decision, and it is entirely reasonable to have questions about it. The fact that it has not fired does not mean it is not doing its job.

The device monitors your heart rhythm continuously and records any anomalies, even ones you are not aware of. It provides a level of protection and clinical data that passive monitoring alone cannot. For some people, the knowledge that the device is there also provides meaningful reassurance to both themselves and their families.

If you have concerns about whether your device is appropriate for your individual situation, those are legitimate questions to raise directly with your cardiologist. A second opinion is always an option if you feel your concerns have not been adequately addressed.

A venous occlusion is a blockage in a vein, in this case typically the subclavian vein that runs beneath the collarbone, where ICD leads are commonly positioned. It occurs when the presence of the lead causes the vein to narrow or block over time.

Symptoms can include swelling, stiffness, discolouration, or a feeling of heaviness in the arm on the side of the device. It is not always immediately identified, and in some cases people are discharged from hospital without a clear diagnosis, only for the cause to be confirmed when symptoms recur.

Venous occlusion is not a common complication, but it does occur. If you experience unusual arm symptoms after ICD implantation, contact your ICD clinic promptly. Do not wait for your next routine appointment.

Very. Feeling grateful and frustrated at the same time is not a contradiction. It is one of the most commonly reported experiences among people living with an ICD, and it deserves to be acknowledged rather than dismissed.

Many people distinguish between wishing they had not got the device and wishing they had never needed it. Those are two very different things. Others find the psychological adjustment takes time, particularly if the device was implanted following a sudden and traumatic cardiac event, or if it was fitted as a precaution without a clear triggering incident.

If you are struggling emotionally with your device or your diagnosis, speaking to your cardiac nurse specialist or GP is a good first step. Peer support can also be valuable. The SCA UK community connects people at every stage of life with a cardiac condition, and hearing from others who have been through the same adjustment can make a significant difference.

Not necessarily. A full shock is usually noticeable and can feel like a sudden strong thump to the chest. Most people describe it as startling rather than painful, though experiences vary.

ATP (anti-tachycardia pacing), however, often works without the person being aware of it at all. It delivers a rapid burst of pacing to interrupt an arrhythmia before it escalates to the point where a shock is needed.

Some episodes of arrhythmia are also brief enough to resolve before the device needs to intervene at all, but the device will still record them. It is entirely possible to have a significant episode detected by your ICD without knowing anything about it until the data is downloaded at your clinic.

An implantable cardioverter-defibrillator (ICD) is a small device fitted under the skin, usually near the collarbone, that continuously monitors heart rhythm. If it detects a dangerous arrhythmia, it can deliver a controlled electrical shock to restore a normal rhythm.

Some devices also provide pacing support and a therapy called ATP (anti-tachycardia pacing), which can correct certain arrhythmias without a full shock. ATP works silently and the person often has no awareness that it has activated.

ICDs are used both for people who have already experienced a life-threatening cardiac event and for those considered at elevated risk of one, as a precautionary measure. The device records data continuously, which your ICD clinic can download and review remotely or at a scheduled appointment.

It is rare. Your ICD is programmed to allow your heart to normally rise without treatment shocks being delivered. Your device should only deliver a shock when your heart rate meets the specific criteria programmed by your heart doctor. If you receive a shock during intimacy or other activities, contact your cardiologist or device nurse. Your doctor will then determine the cause of the shock and may also make adjustments in the programming of your heart device.

The procedure itself is performed under local anaesthetic with sedation, so you should not feel pain during the implant. You may be aware of some pressure or gentle movement, and you will likely feel drowsy. Once the anaesthetic wears off over the following hours, most people have some soreness at the wound site, which is normal and manageable with standard pain relief.

In the days after the procedure, the wound site will be tender and bruised. This is expected and settles within one to two weeks. If you experience severe pain, significant swelling, redness spreading from the wound, or a high temperature, contact your device clinic promptly or go to A&E, as these could indicate infection.

Most people are surprised by how straightforward and well-tolerated the procedure is. Many members of our community who have been through it are happy to share what it was like from the patient side.

No, but it is strongly recommended. Remote monitoring allows your device clinic to review data from your ICD between appointments without you needing to travel in. If your device detects something that needs attention, an alert can be sent automatically to the clinic, meaning faster review and, where needed, a quicker response.

Many modern ICDs transmit data wirelessly via a small bedside unit or a smartphone app. Your device clinic will let you know whether your device supports remote monitoring and how to get it set up. If it is available to you, there is very little reason not to use it. It is a reassuring extra layer of oversight, particularly in the first year after implant.

ICD alert sounds vary by manufacturer and device model. Your device clinic will explain what the specific alerts on your device mean, as these are set individually based on your programmed thresholds. In general, a beeping tone draws your attention to something the clinic needs to know about, such as a change in battery level, a sensed arrhythmia, or the delivery of a therapy.

The alert will typically repeat at intervals until your clinic reviews the device and adjusts the alert settings. If you hear a beeping tone from your ICD, contact your device clinic as soon as possible. If you have also felt unwell or received a shock, go to A&E.

Our ICD sounds and alerts page explains the common alert types in more detail.

ICDs are highly effective. When the device detects a dangerous heart rhythm, it delivers a shock in the vast majority of cases. Clinical evidence consistently shows appropriate shock delivery rates above 95%, though the exact figure varies depending on the device, the condition being treated, and how the device is programmed.

ICDs do not fail often, but they are not infallible. Lead fractures, sensing errors, and inappropriate shocks (where the device fires when it does not need to) are all recognised but relatively uncommon complications. Your device clinic monitors for signs of these at every check-up, and remote monitoring can flag concerns between appointments.

If your ICD delivers a shock, contact your device clinic or go to A&E. Whether the shock was appropriate or not, it should always be reviewed. Our page on living with an ICD covers what to do if your device activates.

Always carry your heart device ID card. This card is helpful if your heart device sets off a metal detector or a security system.

If you go into cardiac arrest and an AED or external defibrillator is available, it should always be used. Do not hesitate because of your ICD. Saving your life takes priority.

An external shock can occasionally alter your ICD’s programmed settings or, in rare cases, cause minor damage to the device. For this reason, your ICD should be checked by your device clinic as soon as possible after any external defibrillation, even if you feel well. The clinic will test the device and confirm it is functioning and correctly programmed.

If you carry an ICD identification card, it can help emergency responders understand your situation, though it should never delay the delivery of a shock if one is needed.

After your ICD is fitted, your device clinic will set up a schedule of regular check-ups. These typically occur every six to twelve months, and more frequently in the first year after implant.

At each appointment, the clinician uses a handheld device called a programmer, held near the ICD, to communicate wirelessly with it. This allows them to check battery levels, review any stored heart rhythm data, adjust settings if needed, and confirm that the device is working as it should. The process is painless and usually takes no more than twenty minutes.

Many patients are also set up with remote monitoring, which allows the clinic to review device data between appointments without you needing to travel in. This does not replace in-person check-ups, but means that changes or concerns can be picked up more quickly. Ask your device clinic whether remote monitoring is available for your device.

ICD battery life varies depending on the device model, how often it delivers therapy, and how it is programmed. The typical range is 5 to 10 years, though some devices last longer, and higher therapy usage can shorten battery life.

Your device clinic monitors battery levels at every check-up and will give you plenty of notice when replacement is approaching. There is no risk of the battery running out without warning. When the time comes, replacement is a relatively minor procedure, usually simpler than the original implant, as the leads can often be reused.

For a more specific estimate based on your particular device and settings, ask your cardiologist or device nurse at your next appointment. You can also read more on our page about living with an ICD.

Not really. Sedation/anaesthesia is used for the procedure. You might be slightly awake, but you shouldn’t feel anything. You probably won’t remember anything either.

Wherever you travel, your heart device monitors your heart and provides therapy whenever it is needed. You can travel knowing that support for your heart device is available around the world. Your doctor may also be able to check your heart device remotely, so it may be a good idea to let your doctor know when and where you will be travelling.

An overnight stay in hospital is typical after an ICD implant, though some patients go home the same day. Most people are back to light everyday activities within two to three days of the procedure.

It is common to have soreness and tenderness around the wound site for several days, and bruising is normal. The wound usually heals within one to two weeks. For the first few weeks, your cardiologist will advise you to avoid lifting your arm above shoulder height on the side of the implant and to hold off on strenuous activity. This allows the leads and the wound to settle properly.

Your device clinic will give you specific guidance on activity restrictions for your situation. If you are concerned about anything during recovery, contact your device clinic or call NHS 111. Our page on living with an ICD covers what to expect in more detail, and members of our community who have been through the procedure are usually happy to share their experience.