Abnormal heart rhythms

Doctor analysing printed heart rhythm

An abnormal heart rhythm – also called an arrhythmia – means your heart is beating too fast, too slow, or with an irregular pattern.

Your heart has an electrical system that tells it when to beat and pump blood around your body. If there is a problem with this system you may experience an abnormal heart rhythm. 

What are the symptoms of an abnormal heart rhythm?

The symptoms of an abnormal heart rhythm depend on what type of arrhythmia you have. The most common symptoms of an abnormal heart rhythm include:

  • palpitations (a thumping or fluttering sensation in your chest)
  • dizziness
  • breathlessness
  • feeling tired
  • losing consciousness.

When should I be worried about abnormal heart rhythms?

It's normal for your heart to beat at different rates during the day. It will be slower when you're resting but may be faster when you are physically active, anxious or excited. Many people experience palpitations at some point in their lives and describe them as feeling like your heart is pounding or fluttering.

For most people, although palpitations can be unpleasant, they’re usually harmless and don’t mean anything is wrong with your heart.

You might also feel that your heart has missed or 'skipped' a beat, or that there has been an extra beat. This is called an ectopic beat. Ectopic beats are very common and harmless so they don’t usually need treatment. 

Speak to your doctor about your abnormal heart rhythms if:

  • your palpitations last a long time, don't improve or get worse
  • along with palpitations you start to feel faint or dizzy
  • you have a history of heart problems
  • you're concerned about the palpitations.

They’ll be able to talk to you about your symptoms and whether you need an ECG to assess your heart rate and rhythm.

Read our factsheet on Palpitations and ectopic beats for more information.

What are the types of abnormal heart rhythm?

There are many different types of abnormal heart rhythm. What type you have depends on where in your heart the electrical impulse starts, and if it causes your heart to beat too fast, or too slowly. 

The most common abnormal rhythm is atrial fibrillation, an irregular, or fast heart rhythm.  Other abnormal heart rhythms include:

  • fast heart rhythms such as supraventricular tachycardia (SVT), sinus tachycardia (ST) and ventricular tachycardia (VT) are known as tachycardias and are faster than 90 beats per minute
  • bradycardias such as heart block are slow abnormal heart rhythms, when your heart beat is 60 beats per minute or below
  • atrial flutter is typically a very fast, irregular heart rhythm 
  • tachybrady syndrome (sick sinus syndrome) includes periods of very fast or slow heart beats
  • ventricular fibrillation (VF), is an abnormal heart rhythm that's so fast a pulse cannot be identified and is an emergency situation.

To find out more about these conditions and their treatment, download or order our booklet Heart rhythms.  

What causes abnormal heart rhythms?

There are lots of reasons why you may have a different heart rhythm. Common reasons for getting abnormal heart rhythms are:

  • electrical impulses are coming from another part of the heart and not the sinus node (the place in the heart where natural electrical impulses are usually generated)
  • electrical impulses are coming from the sinus node, but going to the lower chambers of the heart by the usual path
  • there is an abnormality in blood chemical levels.

Some abnormal heart rhythms are inherited. If this is the case for your condition, your doctor may talk to you about having other family members tested. Although, this can be scary, it can also help them know if they need treatment now or in the future. 

How does the heart's electrical system work?


The heart's electrical system has the following process:

  • The sinus node – sometimes called the SA node – is a special group of cells in your heart. It’s known as your heart’s natural pacemaker.
  • It sends an electrical signal to the chambers of your heart, which tells them when to contract and push blood through your heart.
  • If your heart is working properly, the electrical signal will travel from the sinus node to the top chambers of your heart (atria) and then on to the lower chambers (ventricles).
  • The normal electrical pattern of your heart is known as sinus rhythm. A normal sinus rhythm will generally cause your heart to beat between 60 to 100 beats per minute (bpm) when you’re resting. 

What are the tests for abnormal heart rhythms?

Your doctor might recommend that you have an ECG, echocardiogram or electrophysiological (EP) study to help diagnose an abnormal heart rhythm.

What are the treatments for abnormal heart rhythms?

Depending on the type of abnormal heart rhythm, your doctor may recommend using medication to stop, prevent or control it.  If appropriate, they might suggest a procedure such as cardioversion or catheter ablation, or surgery to insert an implantable cardioverter defibrillator (ICD) or pacemaker

Psychological support for living with an abnormal heart rhythm

Living with a heart condition can be emotionally challenging for you and your family. It is important to manage anxiety and stress and there are many outlets of support to help you.

You can use the following ways to get mental support for living with a heart rhythm:

  • Talk to your GP about being referred for counselling or Cognitive Behavioural Therapy.
  • Call us on 0300 330 3311 to speak to one of our nurses on our Heart Helpline between 9 and 5, Monday to Friday.
  • Join our online community platform, HealthUnlocked. Members include those who have been affected by the same condition.

Find out more

Researching abnormal heart rhythms

Your donations help us fund vital research into the causes and treatment of heart conditions, including the work of BHF Professor Barbara Casadei, who is pioneering work to improve our understanding of atrial fibrillation, the most common arrhythmia in the UK.


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