Electrocardiogram (ECG) at Manchester Institute of Health & Performance (MIHP)

What is an ECG?

An ECG (electrocardiogram) is a test that records the electrical activity of your heart, including its rate and rhythm. It's usually quick and painless, and doesn't send any electricity into your body, it only picks up the signals your heart already makes.

Why might I need an ECG?

You'll usually have an ECG if a doctor thinks you might be having symptoms of a heart attack, coronary heart disease, or a problem with how quickly or regularly your heart beats (an arrhythmia). It may also be done if you've already been diagnosed with a heart condition, before and while taking certain medicines, or if you have an increased risk of heart disease, for example because it runs in your family or you have a condition like diabetes.

What are the benefits of having one?

An ECG can help diagnose and monitor a range of heart conditions and is often the first test used if a heart problem is suspected. Because it's quick and painless, results from an ECG, alongside your symptoms and other tests, can help your doctor find out what's affecting your heart and decide on the right treatment.

Are there different types of ECG?

There are 3 main ways an ECG can be carried out, depending on what your doctor needs to find out:

• a resting ECG, done while you lie still for a few minutes
• a portable, ambulatory ECG, worn for a period of time, usually 24 to 48 hours but sometimes up to 7 days, while you go about your normal activities
• an exercise ECG (also called a stress test), done while you exercise on a treadmill or bike, or after being given a medicine that raises your heart rate if you're not able to exercise.

How do I prepare for an ECG?

For a resting ECG, wear a top that's easy to take off, and avoid using body lotions, oils or talcum powder on your skin beforehand, as these can stop the electrodes sticking properly. Some people may need their chest shaved and cleaned before the test.

If you're having an exercise ECG, avoid a heavy meal or caffeine beforehand. Tell your doctor about any medicines or supplements you're taking, as some can affect the accuracy of your results, though you shouldn't stop taking anything unless you're told to. You can also ask for a chaperone, such as a nurse, to be in the room with you.

What happens during the test?

For a resting ECG:

• you'll be asked to undress from the waist up, behind a screen
• you'll lie back while sticky patches (electrodes) are attached to your arms, legs and chest, connected to the ECG machine
• you'll need to lie still for a few minutes while the machine records your heart's electrical signals
• the electrodes are then removed, which might feel a little uncomfortable, similar to taking off a plaster, and you may notice a slight rash where they were.

The test itself takes just a few minutes, though a portable ECG is worn for much longer and an exercise ECG usually lasts between 40 and 60 minutes.

What happens after the test?

You may get your ECG results on the same day, but it can take a few weeks depending on the type of ECG you had. You'll usually be given a follow-up appointment, or your results will be sent to your GP or the doctor who referred you, and they'll explain what the results mean and what happens next.

If you haven't heard anything after a few weeks, contact the doctor who referred you for the test.

What are the risks?

An ECG carries very little risk. You might feel some discomfort or mild skin irritation when the electrodes are removed, but the test itself doesn't send any electricity into your body, it only records the signals your heart already produces.