Electrocardiogram (ECG)
General heart health FAQs
View our short videos designed specifically to answer all your questions about heart health, including tests available at London Heart.
What is an electrocardiogram?
xIn this non-invasive test, electrodes are stuck to your skin to monitor electrical signals from your heart. The test measures and records your heart’s electrical activity and rhythm, including the strength and speed of your heartbeat.
It is a simple and routine test that causes no pain. It doesn’t take long, and you may have it while resting. You may also have it whilst exercising to test your heart’s response to exercise or stress.
ECG vs echocardiogram (echo)
Some people confuse these two tests as they sound similar. An echocardiogram is a type of ultrasound. During an echo, we use sound waves to look at your heart’s structure and nearby blood vessels.
ECG results show a moving line known as your sinus rhythm, whereas an echo takes pictures or short videos. These detailed images may highlight large or thickened heart walls. An echo can also suggest whether you have weak or damaged heart valves and tell you if the heart function is impaired.
We may perform both tests to help us diagnose the cause of your symptoms.
When do we recommend an ECG?
An ECG can detect an abnormal heart rhythm (arrhythmia) and a current or previous heart attack. Other issues it can help diagnose include cardiomyopathy, coronary heart disease, and heart structure changes. We may recommend it if you’ve had an injury, to monitor a heart condition, or if you’ve experienced concerning symptoms.
Symptoms that may indicate a heart problem include:
- Chest pain
- Palpitations
- A fast pulse
- Lightheaded
- Weak or tired
- Short of breath
You are more likely to experience an issue if you smoke, drink a lot of alcohol, have a high-fat diet or are obese. High blood pressure, diabetes, and high cholesterol also increase your risk. Your cardiologist will explain why you need the procedure.
Types of ECG
Your symptoms and suspected heart problems will influence which type we suggest. The three main types are:
- Resting: We ask you to lie down while we perform it.
- Exercise/stress: You may need to use a treadmill or exercise bike during the test.
- Ambulatory (sometimes known as a Holter monitor): We ask you to wear a portable device for a day or two.
If we need to measure your heart rhythm for longer, we may recommend an event monitor or implantable loop recorder (ILR).
How does an ECG work?
Preparation
You don’t need to do much to prepare. On the day, you’ll need to avoid wearing moisturiser or oils so the electrodes can stick properly. Electrodes are small, sticky patches with wires that we place on your skin and connect to the monitor. You may also need to shave your chest.
You should wear comfortable clothes and shoes, especially if you have an exercise ECG, and remove any jewellery or metallic items. Most people don’t need to fast beforehand, but your cardiologist may ask you to stop taking certain medications. Avoid products containing caffeine for 12 hours, and don’t drink cold water immediately before.
You may feel more comfortable if you don’t eat a heavy meal before an exercise ECG. Our cardiologist will let you know if there is anything else you need to do to prepare.
Procedure
Before we begin, we will explain each step of the procedure. Let us know if you have any questions. We’ll ask you to undress to your waist so we can prepare your skin for the electrodes. It may involve cleaning or shaving your skin so the electrodes can stick more easily. The room is at a comfortable temperature, so you won’t feel cold or shiver.
During a standard ECG, you lie flat and still while we attach electrodes and perform the diagnostic test. We may attach ten to twelve electrodes across your chest, legs, and arms. The procedure usually takes about ten minutes to complete.
An ambulatory monitor only involves attaching three electrodes, while an event recorder and ILR don’t use any. If you need an ILR, we’ll give you a local anaesthetic to prevent pain as we implant the device.
Results
We can often discuss your results on the same day as your test. We may suggest additional tests if the procedure doesn’t identify the cause of your problems or to confirm our diagnosis. Once we have confirmed your diagnosis, we will form a suitable treatment plan.
Your treatment may include lifestyle changes and medications. Depending on the severity of your condition, you might also need surgery. Our cardiologist will talk you through your results in detail so you can make an informed decision about the next steps.
Risks and side effects
An ECG is a safe, low-risk procedure. Some people have a minor reaction to the adhesive on the electrodes, such as developing a rash or red skin. Less commonly, people experience temporary swelling.
No electricity enters your body during the test, so there is no risk of an electrical shock. If your test involves exercise, it can trigger a heart problem due to strain, but this isn’t common. Your cardiologist will inform you of your risk and circumstances.
The exercise ECG can cause you to feel dizzy, tired, or unwell. Most people can complete the test, but you should tell us if you feel unwell or find it too difficult.
Book a private electrocardiogram
An ECG can identify heart problems before they lead to serious complications. By diagnosing the cause of your symptoms, we can form an appropriate treatment plan to help you manage your condition and feel better.
Our heart rhythm specialist, Dr Syed Ahsan, offers private cardiac diagnostic tests at London Heart Clinic. Book an appointment at our world-class cardiology centre to determine what tests you might need to diagnose a heart problem. Your doctor can also refer you to our clinic if they think you need diagnostic tests.
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What our patients say
After suffering from a heart condition for a number of years I was very happy to meet Dr Ahsan, from the first consultation where he believed there was a solution I have now completed the surgery and had my final consultation with him today…”
I am very grateful to have Dr Syed Ahsan as my consultant. Dr Ahsan always greets you warmly on each visit despite his busy workload. Dr Ahsan explains everything clearly and helps you to understand even the most complex medical terms…