What is a subcutaneous ICD (S-ICD) and how is it different from a standard ICD?
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.
Category: Implantable DevicesI have a physically demanding job. Can I return to work after a cardiac arrest?
Many people do return to physically demanding work after a cardiac arrest, but it generally takes longer than returning to a sedentary role, and a phased return with gradual increase in activity is usually advisable. Your cardiologist needs to be involved before you return to strenuous physical work.
If you have had an ICD fitted, there are additional considerations. Some industrial or manual environments involve equipment that generates strong electromagnetic fields — certain welding equipment, large motors, and power generation machinery can interfere with ICD function. Your device clinic can advise on what is and is not safe in your specific workplace. This does not rule out physical work, but it does need assessment.
An occupational health referral is particularly important for physically demanding roles. Your occupational health adviser can assess the specific risks of your job, recommend appropriate adjustments or restrictions, and liaise with your employer on a safe return-to-work plan. Some roles may require temporary redeployment while recovery continues. Our page on returning to work after cardiac arrest has further guidance.
Category: Practical IssuesI have been given an ICD. What does that mean for my daily life?
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.
Category: Implantable DevicesWhat is SCA UK and how can it help me?
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.
Category: Living With an ICDI have an ICD fitted as a precaution. Should I be worried?
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.
Category: Implantable DevicesWhat is a venous occlusion and can it happen after ICD implantation?
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.
Category: Implantable DevicesIs it normal to feel conflicted about having an ICD?
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.
Category: Living With an ICDWill I always feel it if my ICD fires?
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.
Category: Implantable DevicesWhat is an ICD and what does it actually do?
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.
Category: Implantable DevicesCan my ICD shock me during everyday activities?
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.
Category: Living With an ICD