What is atrial fibrillation?
Atrial fibrillation (AF) is an abnormal heart rhythm, where the heart beats irregularly and often fast. It is the most common heart rhythm disorder in the UK.
AF can occur at any age but is most common in people aged over 65 years old. In the over 80s, it can affect 7-10 per cent of people. The top chambers of the heart (atria) have abnormal, disorganised electrical activity. This overrides the sinus node, causing the atria to beat rapidly (more than 300 times a minute) and irregularly (known as fibrillating or fibrillation). At this rate the atria can not pump blood efficiently.
The AV node has a very important protective mechanism; it is able to stop many of these electrical impulses being transmitted from the atria to the ventricles, preventing the ventricles from beating at the same rate as the atria. The rate of the ventricles in AF depends on the AV node and can range from slow to very fast.
The protective function of the AV node means AF is a non-life threatening arrhythmia. However, it can still cause the heart function to become impaired and, regardless of how slow or fast the heart is beating, can increase the risk of stroke.
What are the causes of AF?
The cause of AF is still not fully understood. AF is more likely to occur with increasing age and there are several ill-health factors that can contribute to AF developing:
- ischaemic heart disease
- mitral valve disease
- heart failure
- sleep apnoea
- congenital heart disease
Other factors include:
- hyperthyroidism / hypothyroidism
- respiratory disease / pneumonia / chest infections
- pulmonary embolism (PE)
- alcohol / drugs
- carbon monoxide poisoning
There may be no apparent reason for developing AF; this is when it is called "lone" AF.
What are the symptoms of AF?
Some people might not experience any symptoms associated with their AF; however, if they do, the most commonly reported are:
- tiredness / lethargy
- reduced exercise capacity
- chest discomfort
Is there more than one type of AF?
There are three types of AF, based on both frequency and duration of AF episodes:
- Paroxysmal AF – intermittent episodes that return to normal rhythm within seven days.
- Persistent AF – Episodes that persist for more than seven days and may stop with treatment or sometimes on their own. If it continues for more than 12 months, it is known as long-standing persistent AF.
- Permanent AF – AF that does not terminate with treatment or it has been decided that accepting AF is the best option for you.
Atrial tachycardia (AT) is an abnormal heart rhythm, but unlike AF is more regular and organised. AT also comes from the top chambers (atria) of the heart, from either the right side, left side or both. AT is usually seen in patients that have undergone heart surgery, have congenital heart defects or have undergone previous ablation procedures.
Some people may experience symptoms such as a fast heartbeat, which may feel regular in nature but can also feel irregular. Other symptoms experienced may be similar to AF, such as breathlessness, dizziness and tiredness.