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What is an ICD?

ICD stands for Implantable Cardioverter Defibrillator. They are implanted to treat people who have, or are at risk of having, life-threatening abnormal heart rhythms. An ICD sends electrical pulses (referred to as a shock) to the heart to regulate abnormal heart rhythms and prevent cardiac arrest. This treatment can be life-saving, but many you may feel very unwell and find the shock painful.

My ICD has one lead but I met someone else with two leads. What does this mean?

ICDs can have one, two or three leads (known respectively as single chamber, dual chamber, or cardiac resynchronisation therapy (CRT)). The leads are part of the pacemaker function of an ICD and how many you have depends on the nature of your condition. There are also ICDs which do not have a pacemaker function and are placed under the skin without any leads in the heart at all. All of these types of ICD do the same job in terms of treating abnormal heart rhythms and delivering a shock if needed.

What does having a shock mean?

It means your ICD has to deliver a pulse of electrical energy to “shock” your heart back into a normal rhythm. When an abnormal heart rhythm occurs, the natural electrical signals which stimulate a heart beat have become too fast and chaotic for your heart to beat properly. A shock from your ICD resets these signals and allows a normal, slower, rhythm to return.

There was recently something in the news about the new iPhone and ICDs. Can I still use my phone?

You can use your mobile phone or tablet as long as you don’t place them directly over your ICD. If you keep your phone or tablet 6 inches (15cm) from your ICD there is very low risk of any interference.

How can I find out more?

The British Heart Foundation have an excellent booklet which you can order for free from their website: https://www.bhf.org.uk/informationsupport/publications/heart-conditions/implantable-cardioverter-defibrillators# . The cardiac physiologists at your local hospital will also be able to answer any specific queries you may have when you attend clinic for your ICD check-up.