Holter monitoring
Recording the heart's rhythm throughout the day
Holter monitoring is the continuous recording of the heart's electrical activity with a small portable device, usually over 24 hours. An ECG taken at the clinic only shows a snapshot of a few minutes; a Holter, by contrast, monitors your heart rhythm during your normal daily activities.
It may be requested by the doctor for intermittent palpitations, dizziness, fainting or feeling faint, a suspected rhythm disorder, and for monitoring some treatments.
A few electrodes are stuck to your chest and connected to a small recorder worn on a belt or around the neck. Fitting takes a few minutes and is not painful. You are asked to carry on with your usual daily activities during the recording; the device must not get wet, so you should not shower during this time. Noting down your symptoms and what you were doing at the time, with the time of day, makes the recording easier to interpret.
When the period is over, the device is removed and the recording is analysed on a computer. The doctor assesses the result together with the rhythm at the times you noted symptoms.
If symptoms do not occur during the recording, the Holter result may be normal; in such cases your doctor may recommend repeating the recording or other tests.