Atrial fibrillation

Atrial fibrillation

• About atrial fibrillation
• Symptoms of atrial fibrillation
• Causes of atrial fibrillation
• Diagnosing atrial fibrillation
• Treating atrial fibrillation
• Complications of atrial fibrillation

About atrial fibrillation

Atrial fibrillation (AF) is a condition that causes an irregular heart rate.

Most commonly, the heart rate will be unusually fast with this condition; but it is possible for the heart rate to be within accepted limits or slower and still be in atrial fibrillation. 

You can measure your heart rate by feeling the pulse in your wrist or neck. A normal heart rate, when you are resting, should be between 60 and 100 beats a minute. In atrial fibrillation, it may be over 140 beats a minute.

How is atrial fibrillation defined?

Atrial fibrillation is defined in various ways, depending on how it affects you:

• paroxysmal atrial fibrillation – this comes and goes, usually stopping within 48 hours without any treatment.
• persistent atrial fibrillation – this lasts for longer than seven days, or less when it is treated.
• longstanding persistent atrial fibrillation – this means you have had continuous atrial fibrillation for a year or longer.
• permanent atrial fibrillation – this is when atrial fibrillation is present all the time and no more attempts to restore normal heart rhythm will be made 

What happens in atrial fibrillation?

When the heart beats normally, its muscular walls contract (tighten and squeeze) to force blood out and around the body. They then relax, so the heart can fill with blood again. This process is repeated every time the heart beats.

Atrial fibrillation occurs when abnormal electrical impulses suddenly start firing in the atria (upper chambers of the heart).

These impulses override the heart’s natural pacemaker, which can no longer control the rhythm of the heart. The atria contract randomly and sometimes so fast that the heart muscle cannot relax properly between contractions. This reduces the heart’s efficiency and performance and causes a highly irregular pulse rate.

What are the symptoms of atrial fibrillation?

Atrial fibrillation can lead to a number of problems, including:

• dizziness
• feeling faint
• shortness of breath
• fast and irregular heartbeat (palpitations)
• feeling very tired

Some people with atrial fibrillation have no symptoms and are completely unaware that their heart rate is irregular.

Find out more about the symptoms of atrial fibrillation

Why does atrial fibrillation happen and how common is it?

Atrial fibrillation is the most common heart rhythm disturbance and affects up to 800,000 people in the UK.

The cause of atrial fibrillation is not fully understood, but it tends to occur in certain groups of people and may be triggered by certain situations, such as drinking excessive amounts of alcohol or smoking.

The condition can affect adults of any age or gender but:

• is more common the older you get
• affects about 10% of people over 75
• more common in men than women

Atrial fibrillation is more likely to occur in people with other conditions, like:

• high blood pressure
• diabetes 
• coronary heart disease

Find out more about the causes of atrial fibrillation and how it’s diagnosed

What is the outlook with atrial fibrillation?

Atrial fibrillation is generally not life threatening, many people live normal healthy lives with this condition, but it can be uncomfortable and often needs treatment.

This condition increases your risk by about four to five times of having a transient ischaemic attack (TIA) or stroke.

This is because when the atria in the heart do not contract properly there is a risk of blood clot formation. Clots from the atria may break off and go to other parts of the body. A blood clot passing up to the arteries supplying the brain may cause a stroke.

For this reason, treatment may involve medication to control the heart rate or rhythm, and medication to prevent clots from forming in the blood.