Depending on your symptoms you may be asked to undergo different kinds of ECG:
- ECG stands for electrocardiogram, which gives a recording of the electrical activity of your heart in the form of a graph (see diagram for an example of an ECG recording).
- An electrocardiogram recording consists of 'waves' and 'complexes' which correspond to particular phases in your heart's electrical cycle. These are identified by the letters P, Q, R, S and T.
- Electrodes, attached to sticky patches, are positioned on your chest, wrists and ankles and a recording of the electrical signal between the electrodes is made.
- ECGs are often referred to by the number of 'leads' e.g. 12 lead ECG. Each lead gives a view of the electrical activity of the heart from a particular angle across your body (i.e. between two electrodes).
- The ECG reflects what is happening in different areas of your heart and helps to show up any abnormality in the conducting system.
- An electrocardiogram is painless and the procedure usually takes about 5-10 minutes.
24 hour ECG
- This is sometimes referred to as an ambulatory ECG. In this test there are fewer electrodes than a standard ECG.
- These electrodes are connected to a small box (similar in size to an original personal stereo system) and attached to a belt which you wear for 24 hours, as you go about your normal daily activities.
- A 24hr electrocardiogram records the information on a tape, which can then be studied by your doctor. This can be very helpful in looking at irregular heart rhythms that come and go. It can also be used to confirm whether or not symptoms you are having are related to your heart.
- Also known as a 'stress test' or 'treadmill test'. This is a type of ECG which records the activity of your heart as you make it work harder i.e. by walking and talking on a treadmill.
- You will be closely monitored by medical staff during this test. An exercise ECG records changes that your heart experiences due to an insufficient blood supply.
- It can be used to diagnose angina and assess its severity. Not everyone will be able or fit enough to have this test.