Electrocardiogram (ECG)


What is arrhythmia?

A heart arrhythmia is an abnormal heart beat or problem with your heart’s natural rhythm. Arrhythmias occur when the electrical signals, which control your heartbeats, do not work properly and cause your heart to beat too fast, too slow or irregularly.

A person with a healthy heart will have a heart rate of between 60 and 100 beats per minute when resting.

What are the different types of arrhythmia?

Atrial fibrillation (AtFib)

Atrial fibrillation is an irregular and often rapid heart rate. The heart’s top chambers or atria quiver in a rapid and chaotic pattern, which can slow blood flow. The heart’s main pumping chambers, the ventricles, also beat unevenly which affects how well they push blood around the body. The heartbeat of a patient with atrial fibrillation is typically about 150 beats per minute but can reach 350 beats per minute in extreme cases.

Atrial flutter (AFL)

Atrial flutter is an abnormal rhythm that occurs in the top chambers or atria of the heart. In AFL, the atria beat regularly but too fast, which results in atrial muscle contractions that are faster and out of sync with the lower chambers or ventricles, of the heart. Patients with AFL typically experience heart rates of 150-180 beats per minute at rest, but rarely can reach 300-350 beats per minute.

Supraventricular tachycardia (SVT)

Supraventricular tachycardia is a rapid heartbeat caused by faulty electrical signals in the upper parts of your heart. Patients usually experience a burst of accelerated heartbeats. SVT usually affects young, healthy people, who will experience a heart rate between 160 and 200 beats per minute.

Ventricular tachycardia

Ventricular tachycardia is an abnormal electrical impulse that begins in the ventricles and causes an irregular fast heartbeat. The ventricle will often contract more than 200 times a minute.

Ventricular fibrillation

Ventricular fibrillation occurs when rapid and erratic electrical impulses cause the ventricles to quiver instead of pump blood properly. It is life-threatening and is often triggered by a heart attack.

Long QT syndrome (LQT)

Long QT syndrome causes uncoordinated heartbeats which can lead to sudden, uncontrollable and dangerous arrhythmias. LQT syndrome can result in fainting, which typically occurs after increased stress or exercise. Patients with LQT syndrome have an underlying genetic problem.


Bradycardia occurs when your heart beats too slow – under 60 beats per minute. It is a normal phenomenon in people who are very fit (e.g. professional athletes). Bradycardia is however a problem if as a result there is not enough blood reaching your brain, which can cause you to pass out.

Ectopic beats

Ectopic beats are extra heart beats that can arise from the atria (atrial ectopic beats) or ventricles (ventricular ectopic beats). These extra beats are usually silent but occasionally, people will notice that their heart appears to have “skipped” a beat or had an extra strong beat. Ectopic beats are almost always benign.

What are the symptoms of arrhythmia?

Some patients have no associated symptoms with arrhythmia, while others may notice symptoms but not have a life-threatening arrhythmia. It is important to have regular check-ups with your GP, especially if you are concerned.

Common symptoms of a heart arrhythmia include:

  • Fluttering feeling in the chest
  • Racing heartbeat
  • Slow heartbeat
  • Palpitations
  • Dizziness
  • Fainting
  • Light-headedness
  • Chest pain
  • Breathlessness
  • Shortness of breath
  • Sudden or abnormal weakness
  • Sweating
  • Confusion
  • Trouble concentrating

What are the causes of arrhythmia?

There are a number of factors that can cause a heart arrhythmia, including:

  • Sleep apnea
  • Some medication
  • Alcohol abuse
  • Excessive caffeine consumption
  • Overactive thyroid gland (hyperthyroidism)
  • Underactive thyroid gland (hypothyroidism)
  • Drug abuse
  • Stress

How is arrhythmia diagnosed?

To detect an arrhythmia, your doctor will review your symptoms, medical and family history and conduct a physical examination. The following heart-monitoring tests may also be required:

To quickly assess whether your heart beat is irregular, you can use phone tools such as Hearts4Heart's app Feel the Beat.

How is arrhythmia treated?

Treatment is only necessary if symptoms are severe, or if you are at risk of a more serious arrhythmia or complication. Some treatments your doctor may advise include:

Treatment for abnormally fast heart rhythms

Generally, patients with abnormally fast heart rhythms can be treated with drugs that slow the heart rate or may be treated with a procedure, known as catheter ablation. This involves passing a catheter up through a vein into the heart and burning away the small regions of the heart that are causing the arrhythmia.

Treatment for abnormally slow heart rhythms

Patients with abnormally slow heart rates are most effectively treated with an electronic pacemaker that sends regular electrical signals to the heart to ensure it beats normally.

Can arrhythmia be prevented?

You can potentially prevent some types of arrhythmia with lifestyle changes. If you have an existing heart problem, it is important to do the following:

If you have a normal, healthy heart, do the following to keep it in check:

How common is arrhythmia?

Heart arrhythmia patient stories

Read the stories of these amazing heart warriors who've experienced arrhythmia complications in their heart disease battles.

Acknowledgement of Country

The Victor Chang Cardiac Research Institute acknowledges Traditional Owners of Country throughout Australia and recognises the continuing connection to lands, waters and communities. We pay our respect to Aboriginal and Torres Strait Islander cultures; and to Elders past and present.

Victor Chang Cardiac Research Institute - The Home of Heart Research for 30 Years