Implantable Defibrillators (ICDs) in London: Assessment, Implantation and Care

Everything You Need to Know About Implantable Defibrillators

Expert Care for the Device That Protects Your Life

An implantable defibrillator is, in the simplest terms, an insurance policy you carry inside you. It watches your heart continuously and, in the rare moment it is needed, acts to save your life. Being told you may need one is a significant moment, and the team looking after you should match that. London Pacemaker Centre is dedicated solely to cardiac devices, so your assessment, your procedure and your long-term follow-up are all handled by specialists for whom this is core, everyday practice. This page explains the full picture: how we assess whether an ICD is right for you, what implantation involves, the subcutaneous (S-ICD) option, and how revisions work.

Why Choose London Pacemaker Centre

Because we focus entirely on this field, we can offer expertise and continuity that general cardiology rarely matches: fast access to specialist assessment, often within days, the latest device technology including subcutaneous and MRI-compatible systems, and a dedicated long-term follow-up service so your device is reviewed by someone who knows you and your history. We see both self-funded and insured patients, in modern facilities on Wimpole Street in London’s Harley Street medical district and at the internationally recognised Harefield Hospital in North West London.

We also believe these decisions are conversations, not instructions. We explain things clearly, answer honestly, and make recommendations rather than decisions, so the path you take is the right one for you.

What Is an ICD

An implantable cardioverter defibrillator (ICD) is a small electronic device placed inside the body to control dangerous heart rhythms. While a pacemaker is for a heart that beats too slowly, a defibrillator is for a heart that can go dangerously fast in a way that may be life-threatening, in particular the rhythms known as ventricular tachycardia and ventricular fibrillation.

An ICD monitors your heartbeat continuously. If it detects a dangerous rhythm, it can deliver rapid pacing impulses to correct it, or, if needed, a stronger shock to reset the heart to a normal rhythm. Most of the time you will not notice it working at all. If it ever delivers a shock, it can feel like a sudden jolt or thump in the chest. ICDs are one of the most effective ways to prevent death from sudden cardiac arrest caused by dangerous arrhythmias.

ICD Assessment

Recommending a defibrillator follows careful assessment, because the device is only the right answer for specific situations. An ICD may be considered for people who have survived a cardiac arrest, who have a heart condition that increases the risk of sudden death, or who have severe heart failure or an inherited rhythm disorder.

A key part of assessment is understanding why an ICD is being considered, because this falls into two categories that shape everything that follows, including your driving restrictions afterwards. Primary prevention means you have been found to have a condition that places you at risk, but you have not yet had a dangerous event, so the device is recommended as a safeguard. Secondary prevention means you have already had an event, and the device is there to protect you from another. We explain clearly which group you fall into and what it means for you.

Assessment draws on your clinical history, an ECG, imaging and rhythm monitoring as needed, and a frank conversation about the balance of benefits and risks for your individual circumstances.

ICD Implantation

For a standard implant, having a defibrillator fitted is a short, low-risk procedure, similar in many ways to having a pacemaker.

The most common type is a transvenous ICD. The device is placed under the skin near the collarbone, and thin leads are threaded through the veins into the heart. The procedure is typically carried out under local anaesthetic with sedation, so you are comfortable throughout, and usually takes around an hour. You should not feel pain, only some pressure or movement, and pain relief is available as needed.

For a standard implant, no. It is a form of minor surgery with a low risk of serious complications and a very low risk to life. Serious complications are uncommon, at around one percent, and can include bleeding or bruising, lead displacement, infection at the site, and rarely a lung complication. Your team monitors closely to catch any issue early.

Most people go home the same day or the next, and the site usually heals within a couple of weeks to a month. As with a pacemaker, you will be asked to limit movement of the arm on the implant side and avoid lifting above shoulder height for around four to six weeks, while not keeping the arm completely still. One difference with a defibrillator is driving: you will not be able to drive for a period afterwards, at least a month and in some circumstances six months, depending on whether the device was fitted for primary or secondary prevention. We explain exactly which rules apply to you and why, in line with current DVLA guidance.

Living with an ICD is, for most people, living normally, with the quiet reassurance that the device is there if it is ever needed. As one of our consultants puts it, the hope is that you live the rest of your life and never need it, but that you live it knowing it was there if you did.

Subcutaneous ICD (S-ICD)

A subcutaneous ICD is a different type of defibrillator that avoids placing any leads inside the heart.

Instead of threading a lead through the veins into the heart, an S-ICD uses a lead that runs under the skin of the left side of the chest and up alongside the breastbone. This is connected to the defibrillator itself, which sits under the skin on the left side of the chest, below the armpit. Because nothing is placed inside the heart or veins, the S-ICD can be an attractive option for certain patients, particularly where avoiding leads in the heart is an advantage.

It is not the right choice for everyone. Only a proportion of patients currently benefit from a subcutaneous rather than a transvenous device, in part because an S-ICD is designed to deliver shocks but does not provide the longer-term pacing functions that some patients need. Your consultant will discuss the merits of each option for your situation and recommend the one that fits your needs.

ICD Revision

Like all implantable devices, a defibrillator does not last indefinitely, and occasionally the system needs attention rather than just routine monitoring.

An ICD contains a sealed battery that gradually depletes over a number of years, generally sooner than a pacemaker because of the monitoring and shock functions it performs. When the battery approaches the end of its life, the generator is replaced in a short procedure, with the existing leads usually left in place if they are working well. Battery status is checked at every routine review, so a replacement is planned comfortably in advance rather than left to chance.

Revision also covers situations where a lead needs attention, for example if it is not performing as it should, or where the system needs to be changed or upgraded to better meet your needs. Where a lead needs to be removed entirely, this is a specialist procedure in its own right, carried out by clinicians with specific expertise in lead extraction, and we will explain it fully if it ever becomes relevant to you.

For wider guidance, see our pages on the cost of private cardiac device care, ongoing device checks and optimisation, and living with a cardiac device.

What Our Patients Say

This was my first meeting with Dr Mason who is very charming , but also very professional. He fully explained my current medical situation in language that I could understand and answered all my questions in a re-assuring way.

verified patient 13 Nov 2025

This is the second time Dr Mason and I have met in theatre. He has had to revise work done by others. He is very professional, has a great sense of humour and an easy going manner which makes you feel at ease. I can’t thank Dr Mason enough

verified patient 29 May 2026

He explained the procedure of fitting the pacemaker very clearly. And he answered my concerns that gave me relief and I decided to get pacemaker fitted

verified patient 30 Oct 2025

Frequently Asked Questions

ICD Assessment

An ICD may be recommended for people who have survived a cardiac arrest, who have a heart condition that increases the risk of sudden death, or who have severe heart failure or an inherited rhythm disorder. Specialist assessment confirms whether it is right for you.

Primary prevention means a defibrillator is recommended because you are at risk, before any dangerous event has occurred. Secondary prevention means you have already had an event, and the device protects against another. The distinction also affects your driving restrictions.

A pacemaker treats a heart that beats too slowly. A defibrillator treats a heart that can go dangerously fast, and can deliver a shock to reset the rhythm and prevent sudden cardiac death.

ICD Implantation

You should not feel pain during the procedure. It is carried out under local anaesthetic with sedation, so you are comfortable throughout, and any soreness afterwards usually settles within about a month.

A standard implant usually takes around an hour.

For a standard implant, no. It is a form of minor surgery with very low risk and a short procedure time. Serious complications are uncommon, at around one percent.

Often not, although some patients stay overnight for monitoring. Your team will confirm what is right for you.

Subcutaneous ICD (S-ICD)

An S-ICD is a defibrillator with no leads inside the heart. The lead runs under the skin alongside the breastbone, connected to a device placed under the skin on the left side of the chest, below the armpit.

It is better for some patients, not all. It avoids placing leads in the heart, but it does not provide the longer-term pacing functions some patients need. Only a proportion of patients currently benefit from it, and your consultant will advise.

ICD Revision

Battery life varies by device and how often the defibrillator is active, and is generally shorter than a pacemaker. It is monitored at every routine check, so a replacement can be planned well in advance.

The generator is replaced in a short procedure. The existing leads are usually working well and can be left in place and reconnected to a new device.

Living With an ICD

Most of the time you will not notice the device working. If it delivers a shock, it can feel like a sudden jolt or thump in the chest. Many people live for years without ever experiencing one.

You will not be able to drive for a period afterwards, at least a month and in some circumstances six months, depending on whether the device was fitted for primary or secondary prevention. We explain which applies to you, in line with current DVLA guidance.

For many patients, yes. The device is there to ensure your life is not ended prematurely and to give you the best chance of a normal lifespan. How much it affects your outlook depends on your underlying heart condition, which we will discuss honestly with you.

Book an Appointment

Whether you are being assessed for a defibrillator, considering a subcutaneous device, or due a generator change, London Pacemaker Centre offers expert, specialist care from first assessment through to long-term follow-up. Contact us to arrange a consultation or make a referral, and our team will ensure you receive prompt, expert and personalised care.