Event Monitoring

Event monitoring or Ambulatory ECG, records your ECG over 24 hours or up to a week. Holter monitoring means the same, Holter being the name of a manufacturer.

You wear a portable electronic recorder in a pocket or clipped to a belt for the 24 hours or the week. Fitting it is usually done as an outpatient procedure. You are asked to make a note of when you feel any symptoms such as palpitations, dizzy spells, or faints.

This can detect whether you have an irregular heartbeat (arrhythmia). It gets an ECG recording if you have something that happens occasionally – particularly useful if you have symptoms that only occur unexpectedly and/or intermittently. It may show whether you would benefit from a heart pacemaker, or from drug therapy; or from some other further treatment.

An event monitor takes a continuous recording of the electrical impulses produced by your heart – like an ECG over 24 hours or a week. It typically has three or four electrodes picking up signals from the chest and a small portable recorder for recording the signals – eg a box clipped to your clothing. It gives a record of how your heart behaves as you go about your normal daily life.

Some machines have a switch so you can switch on to record your ECG just when you are having symptoms.

Normal activities

You go home and carry out your normal activities. You can wear the monitor all day and night, and walk about unhindered. But you must keep it dry – eg not have a bath. You are asked to keep a diary of any times when you feel symptoms.

At the end of the period you return to the hospital to have the monitor taken off. The recording can be played back at up to 60 times speed – eg an hour played back each minute. The playback can be even faster if the operator knows from your diary when to concentrate on and can skip playback of your sleeping hours for example.

If your symptoms don’t happen often enough to be picked up on a 24-hour or week recording, there are other devices doctors can use to record your heart’s activity over a longer period of time.

Newer event monitors available since 2001 or 2002 use better computer technology and can run for up to a week. They are much smaller and lighter than earlier monitors that had heavier batteries and ran for only a day.


This information was created and edited by Richard Maddison for the BCPA.
Copyright © 1997-2019 The British Cardiac Patients Association, and/or Richard Maddison.
BCPA Head Office: 15 Abbey Road, Bingham, Nottingham NG13 8EE
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First published in this form 2002, and updated 2005, 2007, 2008, 2011, 2012, 2013, 2017.
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Authors, sources and acknowledgements

The main sources are BCPA Journal published articles, other information from authors, and publicly available documents and websites. In many cases the journal articles give sources and further information than the Glossary entries.

Parts of the wordings under ECG and Echocardiogram are adapted with permission from BUPA's health information resources, available at www.bupa.co.uk/health-information.

We hope we have thanked everyone.

Richard Maddison