What is a Defibrillator (ICD)?
An Implantable Cardioverter Defibrillator (ICD) is a device placed under the skin, usually near the collarbone, that helps protect you from dangerous fast heart rhythms. It looks similar to a pacemaker but has extra features designed to treat life-threatening arrhythmias.
Why might I need an ICD?
Some people are at risk of developing dangerously fast heart rhythms (called ventricular tachycardia or ventricular fibrillation). These rhythms can make you feel faint, dizzy, or even cause you to black out.
An ICD is there as a safety net. It can step in within seconds if your heart goes into one of these rhythms, acting much quicker than a bystander finding an external defibrillator or calling an ambulance. If you are at risk of dangerous arrhythmias, an implantable defibrillator gives you the best chance of staying safe.
How does it work?
Sensing: The ICD continuously monitors your heart rhythm.
Pacing: If it detects a fast rhythm, it may first try rapid but gentle pacing signals to bring the heart back to normal rhythm. This is often successful at stopping an arrhythmia without you even realising.
Shock therapy: If the arrhythmia is more persistent and pacing isn’t enough, the ICD can deliver a short electrical shock to reset your heartbeat. This can be surprising, but it is life-saving.
Living with an ICD
Most of the time, you won’t notice your ICD working — it sits quietly in the background.
If you ever do receive a shock, it’s important to go to emergency department and let your cardiologist know. In some cases, you may need a follow-up check.
Once you’ve recovered from the procedure, you can usually return to normal activities, including travel and exercise (your care team will guide you on any limits).
Like pacemakers, ICDs are checked regularly through remote monitoring and clinic visits to ensure they are working properly and the battery is healthy.
How long does an ICD last?
ICD batteries can last up to 8 years or more, depending on how often therapies are delivered. Just like pacemakers, the device won’t stop suddenly — regular monitoring gives plenty of warning when replacement is needed. Replacements are usually a straightforward day procedure, where the old device is swapped for a new one using the same leads.
Reassurance for you
An ICD gives powerful protection against dangerous heart rhythms. For most people, it provides peace of mind and reassurance that help is there instantly if their heart ever needs it.