Atrial fibrillation

In AF your heart's electrical signals become chaotic

In AF your heart's electrical signals become chaotic

What is AF?

AF is the most common type of heart arrhythmia. In AF the electrical signals in the atria become chaotic and disorganised making the atria contract very rapidly and in an irregular way. This is known as fibrillation.

The atrio-ventricular node can not pass on all of these signals to the ventricles but it still results in fast and irregular contraction of the ventricles. This fast, irregular rhythm prevents the heart from pumping effectively and the circulation of blood can be impaired.

Different types of AF

  • Paroxysmal atrial fibrillation comes and goes and usually stops within 48 hours without any treatment.
  • Persistent atrial fibrillation lasts for longer than 7 days and can be treated with drugs or by cardioversion to help the heart return to beating normally.
  • Permanent or chronic atrial fibrillation lasts for a long time (usually longer than a year). Cardioversion is rarely used in this case and is not usually successful. Drug treatment can be used to help control the heart rate.
  • Acute-onset atrial fibrillation is an episode of AF that either starts suddenly (for the first time) or when existing AF becomes suddenly worse. This kind of AF can cause potentially dangerous symptoms (e.g. very fast heart rate) which may need to be treated in hospital.

Symptoms of AF

Some people have no symptoms and AF is only discovered when a nurse or doctor feels your pulse and finds it to be fast and irregular (no pattern to the beats). However, when the heart beats fast and in an irregular way it can not work efficiently and the following symptoms may occur:

  • Dizziness
  • Tiredness
  • Chest pain
  • Shortness of breath
  • Palpitations (increased awareness of your heartbeat)

If you notice a sudden change in your heartbeat and have chest pain you should always seek urgent medical advice.

Please use the following language to cite the source of the materials: Source: National Heart, Lung, and Blood Institute; National Institutes of Health; U.S. Department of Health and Human Services.

The main risk of AF is causing a stroke

What are the risks of AF?

  • Stroke
    The main risk of AF is causing a stroke. When the atria are not pumping effectively they do not always empty completely leaving a pool of blood in the chamber. This blood can become sludgy and may clot. If a blood clot enters the blood stream it can lead to a stroke. You will usually be prescribed a blood thinning drug (e.g. warfarin, heparin or aspirin).
  • Heart failure
    Over time AF can weaken the heart. When the heart muscle can not meet the body's demands for blood and oxygen the body develops a range of different symptoms. When this happens it is referred to as heart failure because of the failure of the heart to work efficiently.

Causes of AF

Sometimes AF develops along with other medical conditions such as:

  • Heart conditions such as:
    • High blood pressure
    • Coronary heart disease (especially after a heart attack or heart surgery)
    • Heart valve disease
    • Congenital heart disease
    • Cardiomyopathy
  • Lung conditions such as:
    • Pulmonary embolism
    • Asthma
    • Emphysema
    • Chronic obstructive pulmonary disease (COPD)
    • Pneumonia
    • Lung cancer
  • An overactive thyroid gland
  • Diabetes
  • Imbalances in the blood e.g. potassium, calcium

Sometimes the cause of AF is unknown.

What triggers AF?

There are a variety of situations that can trigger an episode of, or contribute to, AF:

  • Drinking excessive amounts of alcohol, particularly 'binge drinking'
  • Being overweight
  • Drinking a lot of caffeine, e.g. coffee, tea and energy drinks
  • Taking illegal drugs, particularly those that stimulate the heart, e.g. amphetamines ('speed') or cocaine
  • Smoking

Learning to recognise your individual trigger factors and reducing, or avoiding, them can sometimes help to minimise your symptoms of AF.

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