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Arrhythmias

What are arrhythmias?

Atrial Fibrillation

How do I know if I have an arrhythmia?

What are arrhythmias?

An arrhythmia is when the heart beats too fast (tachycardiac) , too slow (bradycardia) or beats irregularly. It covers a range of conditions, such as artrial fibrillation, tachycardiac and bradycardia.

Your heart rate is controlled by electrical currents. The normal electrical pattern of the heart is called a sinus rhythm. This means that it comes from the sinus node. This is a clump of specialized cells which sends out regular electrical signals. It is often called the heart's natural pacemaker. The electrical signals then travel down to the bottom of the heart in an organised way. An abnormal rhythm, or arrhythmia. can occur when:

  • the electrical impulses, that make the heart beat come from another part of the heart and not the sinus node
  • the electrical impulses come from the sinus node but go to the bottom of the heart via a different path
  • the heart is going at a faster rate than normal but is in a regular rhythm
  • the heart beats at a normal rate but the rhythm is not normal
  • abnormal heart rhythms make the heart rate and rhythm change i.e. atrial fibrillation

A normal heart rate at rest is between 60 - 100 heart beats per minute. If the heart rate is over 100 beats per minute at rest then this is called tachycardia, meaning fast heart rate. If the heart rate is below 60 beats per minute at rest then this is called a bradycardia, meaning slow heart rate.

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Atrial Fibrillation

Atrial fibrillation (AF) is the most common arrhythmia. It occurs when electrical signals in the upper chambers, or atria, are sent out in a disorganised way. These signals then interfere with any other signals which are sent out from the sinus node. As a result, the atria no longer beat in an organised way, and pump less efficiently.


The cause of AF is not fully understood, but it often develops in patients with common heart conditions, such as high blood pressure, coronary heart disease and valve disease. It can be associated with thyroid gland disorders, high alcohol intake and chest infections. In many people with AF, there is no cause and this is known as "lone AF".

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How do I know if I have an arrhythmia?

Arrhythmias can produce many symptoms. Some people will have no symptoms at all and it will only be discovered at a routine medical examination. Among the more common symptoms are:

  • premature beats
  • palpitations, skipped beats or dizziness
  • fatigue, lightheadedness, fainting or near fainting
  • chest pain

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