Electrocardiogram (ECG)

An ECG is a simple test to record information about your heart beat. An ECG measures the electrical signals that cause your heat to beat. Wires are connected to your arms, legs and chest to pick up the electrical signals. These signals can be seen on a screen or are traced out on a piece of paper.
There are a number of reasons why you may need to have an ECG. You may have one:

• to check for problems with your heart if you're having symptoms such as dizziness, chest pain or an abnormal heart rate
• to check how well your heart is working before an operation
• as part of a routine health check-up

An ECG can identify problems with your heart including:

• a heart attack
• an enlarged heart that is working under strain
• fast, slow or irregular heartbeats called arrhythmias

There are a number of different types of ECG. These are listed below.

• The standard ECG which is sometimes called a resting ECG. This is taken while you're resting.
• An exercise ECG (also known as a stress test or treadmill test) is taken while you're exercising. This shows how your heart copes under stress. The test can help to diagnose coronary heart disease (when the arteries to your heart become narrowed) and assess how severe it is.
• A 24-hour ECG, sometimes called a Holter monitor or ambulatory ECG, is a test where you wear an electronic recorder for 24 hours. This shows the activity of your heart over a day and night. It's useful for showing any irregular heartbeats (arrhythmia).
• Cardiac event recorders can record your heartbeat over a longer period of time. They include portable event recorders, which you use to record your heart beat when you get symptoms, and implantable loop recorders (ILR), which are put in under the skin in your chest to continuously monitor your heartbeat. An ILR is useful for recording your heart beat if you have dizzy spells or if you faint. They can stay in place for up to a year or longer.

Preparing for an ECG

A standard ECG can usually be done in a doctor’s clinic and no preparation is normally needed for this.

If you're having an exercise ECG, 24-hour ECG or cardiac event monitoring you will need to go to hospital to have the test or have the equipment fitted. You should follow any instructions the hospital give you before your ECG.

You should wear comfortable clothes for an exercise ECG and don't have a heavy meal before the test. If you're taking certain medicines, for example beta blockers, you may be asked not to take them before an exercise ECG.

Your doctor, nurse or technician will discuss with you what will happen before, during and after your procedure, and any pain you might have. This is your opportunity to understand what will happen, and you can help yourself by preparing questions to ask about the risks, benefits and any alternatives to the procedure. This will help you to be informed, so you can give your consent for the procedure to go ahead, which you may be asked to do by signing a consent form.