Atrial Fibrillation


Atrial fibrillation (AF) is the commonest abnormal heart rhythm. It involves very rapid, irregular activity in the atria (the top chambers of the heart). The ventricles (the bottom, main pumping chambers of the heart) try to keep up and are therefore often fast and irregular too. AF can start and stop on its own after seconds, minutes or even hours. This is known as paroxysmal AF. Persistent AF is AF that does not stop on its own but will stop if a doctor treats it; the doctor may use medicines or a small electric shock (cardioversion). Permanent AF is AF which remains even after cardioversion.



AF is a combination of two problems, a substrate (a heart that likes AF) and a trigger (rapid extra heart beats). In some patients the atria have become stretched making them more irritable. This might be because of a heart attack, heart failure, high blood pressure or valve disease, for instance. These patients may need only a few extra heart beats to start AF. For other patients, the atria are more normal but the patient has many, many more extra beats driving the heart into AF. These extra beats often come from the veins bringing blood back from the lungs in to the left atrium (the pulmonary veins). Other places in the atria can also produce these extra beats in addition. Some patients may only get AF during a particularly severe acute illness e.g. a pneumonia; these patients may not suffer AF again when well.


First and foremost AF causes symptoms. AF means that the atria no longer contract well and thus the heart is somewhat less efficient. How much the patient notices this depends on the individual. It may produce symptoms such as tiredness, chest pain, breathlessness or dizziness for instance; some patients however have no symptoms.

As blood does not move well through the atria in AF it can form clots, particularly in a structure known as the left atrial appendage. These clots can leave the heart and block blood vessels producing damage, for example strokes. It is for this reason that blood-thinning drugs are so important.

Occasionally the ventricles are made to pump so fast for such a long time in AF that they can become weak - so-called tachycardiomyopathy. Heart rate control is particularly important in AF.


There are many different treatments for AF. The treatment chosen will depend on whether the patient has symptoms, the condition of the patient's heart, how long the abnormal rhythm has been present and whether it is paroxysmal or persistent. It is a complex and ever changing area and it is for this reason that it is so important to see a specialist with an expertise in this area.

Increasingly ablation is being used for selective patients with very symptomatic Atrial Fibrillation.


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