A normal electrocardiogram(ECG) only records for 10 seconds and so it is very unlikely a patient will have an episode of palpitations (which are usually intermittent) just when they are having an ECG in clinic. So it is often necessary for the patient to have a continuous recording of the ECG with a portable machine-an Ambulatory ECG. This can continuously record the electrical activity of the heart for 1-7 days whilst the patient is at home/work.
It is done by attaching 3 electrodes (patches stuck on the skin) to the patient as in this illustration
As you can see the monitor is small, it is also surprisingly light and unobtrusive under clothes. There is also a belt clip which will allow the recorder to be clipped to a belt.
The monitor wires can be unclipped and the monitor detached for a shower, leaving the electrodes on, and then reattaching the monitor after the shower.
The monitor has a button to press if the patient notices any symptoms eg palpitations/dizziness this marks the exact point in the recording when the patient felt symptoms. There is also a clock on the recorder so that the patient can note the time and write down both time and symptoms on a diary card. In this way it is possible to see exactly what the rhythm of the heart was at the time the patient felt the symptoms.
It is useful for patients with
- Palpitations-to see what type of heart rhythm disturbance is causing the palpitations
- Dizziness-to see if a slow heart rate is the cause
- Blackouts-to see if a fast or slow heart rate is the cause
- Episodic fatigue-to see if a slow heart rate is
- Atrial fibrillation to assess heart rate control
- Genetic tendency to cardiac rhythm disturbance in the family
- Following strokes to check for asymptomatic heart rhythm disturbance
- In patients with heart failure
- In patients with genetic abnormalities of the heart muscle eg Hypertrophic Cardiomyopathy
- Following catheter ablation to the heart to stop cardiac rhythm disturbance.
The electrodes used are designed not to fall off during the recording and so are larger than the ECG electrodes used for a simple clinic ECG. Rarely some patients develop an allergy to the electrodes causing itching and they need to be removed.