Implantable loop recorders

Nurse leading a patient in a gown

An implantable loop recorder or ILR is a small device that records the electrical activity of your heart.

Why do I need an ILR?

If you have symptoms such as palpitations, dizzy spells or blackouts that may not happen very often, your doctor may suggest you have an ILR fitted.

An ILR is a small, slim device, about the size of a packet of chewing gum or computer USB stick which records your heart’s electrical activity. It has a battery that can last up to three years, so it can record your heart rhythm over a long period of time. This is useful if simple tests like an ECG have been unable to determine the cause of your symptoms.

How is an ILR fitted?

The ILR is implanted under the skin on your chest. Inserting the ILR is a very simple and quick procedure. You will have a local anaesthetic and a small cut of about 2 centimetres will be made to allow the device to be implanted under the skin. It is usually placed in the upper left chest area.

How does an ILR work?

An ILR works together with a small hand-held ‘activator’ about the size of a computer mouse. The activator is used to record information from the ILR.

When you experience symptoms, place the activator over your ILR and press a button to start the recording. Your ILR stores the information from before, during and after you press the button. This information is stored for your doctor to look at, or can even be sent to them over the internet.

It’s important to use the activator whenever you have symptoms, so that the medical staff can see what’s happening to your heart rhythm when you feel unwell. In some cases, an ILR can also be programmed to automatically detect an abnormal rhythm without using the activator.

What happens after the ILR is fitted?

An ILR is usually fitted as a day case. Your doctor or cardiac physiologist will programme your ILR and test it’s working properly. You’ll also get instructions on how and when to use your activator and be given a chance to ask any questions you may have.

When your doctor is happy that enough electrical activity has been recorded, your device will be removed. The procedure for removing the ILR is similar to when it was inserted.

Are there any risks?

Having an ILR fitted involves a very small risk of bleeding, bruising and infection. However, it’s a simple procedure and your doctor will explain any risks before you give your consent to have an ILR fitted.


Want to know more?

Order or download our publications:

Tests booklet



Heart rhythms booklet

Heart rhythms