ECG test

About an ECG test

An electrocardiogram (ECG) is a test that can help diagnose certain heart conditions by measuring the electrical activity of the heart.

Small sticky dots (electrodes) and wire leads are placed on your chest, arms and legs. The leads attach to the ECG machine (electrocardiograph) which records the electrical activity of the heart muscle and displays this as a trace on a screen or on paper.

Any abnormality in the heart rhythm or rate, or damage to the heart muscle, can change the electrical activity of the heart. A doctor will examine the trace and look for specific features of different heart conditions.

An ECG can help diagnose:

• conditions involving the heart’s electrical system
• heart attacks
• abnormal heart rhythms (arrhythmia) – rapid, slow or irregular heart beats
• poor blood supply to the heart
• heart inflammation (pericarditis or myocarditis)
• cardiac arrest.

A doctor may recommend an ECG for a person:

• experiencing symptoms of an abnormal heart rhythm such as:
  • chest pain
  • dizziness
  • fainting
  • fatigue
  • feeling of your heart racing, fluttering, thumping or pounding in your chest (palpitations)
  • shortness of breath
  • sweating
• experiencing warning signs of a heart attack or angina such as:
  • discomfort or pain in your chest, arms, shoulders, neck, jaw or back
  • dizziness, light headedness, feeling faint or feeling anxious
  • nausea, indigestion, vomiting
  • shortness of breath or difficulty breathing
  • sweating or a cold sweat
• who has been diagnosed with a heart condition, to monitor the effects of certain medicines or implantable cardiac devices (like a permanent pacemaker).

Types of ECG

The three major types of ECG are:

• resting ECG – you lie down for this type of ECG. No movement is allowed during the test, as electrical impulses from other muscles can interfere with the test. This type of ECG usually takes five to 10 minutes.
• ambulatory ECG – for an ambulatory ECG you wear a portable recording device for at least 24 hours. You are free to move around normally while the device is attached. A doctor may arrange this type of ECG if you have symptoms that are intermittent (stop-start) which may not show up on a resting ECG. Your doctor may also recommend an ambulatory ECG if you are recovering from heart attack, to ensure your heart is working properly. You may be asked to write down or record any symptoms you experience while wearing the device, including when they occur, so that your own experience can be compared with the ECG.
• exercise stress test/stress test – this type of ECG helps your doctor see how well your heart is working during physical activity. It involves having an ECG while you ride a stationary exercise bike or walk on a treadmill. This type of ECG takes about 15 to 30 minutes to complete. A stress test can also involve medicines, to understand their effects on the heart.

Having an ECG

An ECG is a simple test that usually doesn’t need any special preparation.

• You can eat and drink as normal before having an ECG (unless your doctor has advised otherwise).
• Always let your doctor know what medicines you are taking before you have an ECG.
• Let your doctor know if you have any allergies to adhesive tapes, as an adhesive is needed to attach the electrodes to the skin.
• You will need to remove your upper clothing so that electrodes can be attached to your chest, arms and legs. Wearing a separate top with trousers or a skirt can allow easy access to the chest. Underwire in a bra can interfere with the ECG reading – you may be asked to remove it before the test.
• An ECG works best when the skin is clean and dry, and free of oils and lotions. Sometimes the skin is shaved if necessary because hair prevents the electrodes from sticking properly to the skin.

After an ECG

After an ECG, the electrodes are removed from the skin. You can resume normal activities immediately.

A doctor can usually interpret the results of your ECG straight away based on your medical history, symptoms and clinical examination.

The results of your ECG will help determine what treatment you need, if any.

Your doctor will discuss the various treatments available to find the treatment most suitable for you.

A person with a heart condition may have a normal ECG result if the condition does not cause a problem with the electrical activity of the heart.

In this case, your doctor may recommend other tests, including:

• physical examination (listening to heart sounds)
• chest X-ray - to produce an image that shows the location, size and shape of the lungs, heart and major blood vessels
• echocardiogram (ultrasound of the heart)
• magnetic resonance imaging (MRI) or computerised tomography (CT) scans of the chest - to create 3D images of the organs and structures in the chest, including the heart and lungs
• blood tests
• coronary angiogram (a test to examine the coronary arteries, often used to investigate chest pain or suspected heart attack).

Possible complications of an ECG

An ECG is very a safe test. It does not send electric currents to the body. Some people may be allergic or sensitive to the adhesive used to stick the electrodes to the skin. This might cause some mild skin itchiness and redness which usually resolves on its own and doesn’t require any treatment.

Where to get help

• In an emergency, always call Triple Zero (000)
• Emergency department of your nearest hospital
• Your GP (doctor)
• Your cardiologist
• NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice 24 hours a day, 7 days a week