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Arrhythmia (irregular heart rhythm)


Expert reviewer, Dr Tim Cripps, Consultant Cardiologist
Next review due November 2022

Arrhythmia is when your heart doesn’t beat in a normal rhythm and/or at a normal rate. It might beat too fast or too slow or with an irregular pattern. There are many different types of arrhythmia, which affect your heart in different ways.

About arrhythmias

Your heart is controlled by an electrical system, which tells it when to beat and push blood around your body. Normally, the electrical signal starts in an area of your heart called your sinus node (or sinoatrial node). This signal is usually transmitted to the upper chambers of your heart (the atria) and makes them contract. It then travels via the atrioventricular node to the lower chambers (the ventricles), making them contract.

An image showing the chambers and electrical conducting system of the heart 

It’s normal for your heart to beat at different rates, depending on what you’re doing or how you’re feeling. For instance, it might beat slower than normal when you’re asleep or relaxing. And it might beat faster when you’re active or ill or feel anxious or excited.

Any problem with your heart’s electrical system can cause an arrhythmia. If it’s an ongoing problem, it can affect how well your heart pumps blood around your body and therefore lead to symptoms.

There are lots of causes of arrhythmia, including:

  • problems with the structure or function of your heart
  • low levels of potassium or magnesium in your blood
  • an imbalance of certain hormone levels (your body’s natural chemicals)
  • taking certain medicines, drugs or other substances – like caffeine and alcohol

Types of arrhythmia

There are many different types of arrhythmia. Some of the main ones are briefly discussed below.

Ectopic beats

Ectopic beats (or extrasystoles) are extra beats outside your heart’s normal rhythm. Many people get these, and they are almost always benign – that is, they are not usually associated with any significant symptoms or underlying disease. For more information on ectopic beats, see our FAQ: Sometimes my heart skips a beat.

Atrial fibrillation

Atrial fibrillation happens when the electrical signals that tell your heart when to beat start firing from different areas in the upper chambers of your heart (the atria). They become disorganised and out of control, so that your atria twitch or ‘fibrillate’ rather than contracting properly. As a result, your heartbeat may feel irregular and faster than usual.

Atrial flutter

Atrial flutter is similar to atrial fibrillation, with electrical impulses forming a circuit in your atria, making them beat much faster than they should. The lower chambers of your heart (your ventricles) beat at a slower rate, which puts your heart under strain. Atrial flutter is usually caused by a problem with the structure of your heart.

Supraventricular tachycardia

Supraventricular tachycardia (SVT) is a type of arrhythmia that often results from extra pathways between your atrial and ventricles. This can cause the electrical signals to form a short circuit in your heart, making it beat faster than it should. Attacks of SVT often come and go spontaneously.

Sick sinus syndrome

Sick sinus syndrome is a group of conditions in which your sinus node, which generates the electric pulses in your heart, doesn’t work properly. Your heart might beat too slowly or too fast. Around half of people with sick sinus syndrome get a type called tachy-brady syndrome. This is when your heart rate alternates between being too slow and too fast.

Heart block

If you have heart block, the electrical signals are partly or completely blocked from travelling from the upper to the lower chambers of your heart. This can cause your heart to beat more slowly. Sometimes heart block doesn’t cause any problems at all. But if it’s more serious, you’ll usually need treatment with a pacemaker to maintain a normal heartbeat.

Ventricular tachycardia

Ventricular tachycardia is a fast heart rate caused by a problem with the lower chambers of your heart (the ventricles). Most people with ventricular tachycardia already have some problems with their heart, but it’s possible to get ventricular tachycardia when your heart is healthy. There’s a danger with ventricular tachycardia that it can progress to ventricular fibrillation, which can be life-threatening (see below).

Ventricular fibrillation

Ventricular fibrillation is when electrical signals fire off in different areas of your ventricles at the same time, making the ventricles quiver (fibrillate). It results in your heart being unable to beat properly, so little or no blood is pumped out of your heart. It normally happens in people who already have heart disease. If you don’t get treatment immediately with cardiopulmonary resuscitation (CPR) and defibrillation (electric shock treatment), ventricular fibrillation is usually fatal.

View our animation: How cardiopulmonary resuscitation (CPR) is carried out.

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Symptoms of arrhythmia

Your symptoms will depend on exactly what type of arrhythmia you have. But some of the most common symptoms of arrhythmias include:

  • palpitations – this means you can sense your heart thumping, fluttering or skipping beats
  • shortness of breath
  • chest pain or discomfort
  • feeling light-headed or fainting

Many people feel palpitations from time to time, but this isn’t usually a sign of an arrhythmia. If you have palpitations and they aren’t getting better or if you have any of the other symptoms listed above, you should see your GP. If you’re unsure about any symptoms you’re having, it’s best to talk them through with your GP.

Diagnosis of arrhythmia

Your GP will ask about your symptoms and medical history. If you’ve been having palpitations, they’ll want to know what they feel like and when you tend to get them. They’ll examine you and check your pulse and blood pressure. Your GP may ask you to have an ECG (electrocardiogram). This records the electrical activity of your heart to see how well it’s working. You may be able to have this done straight away at your GP surgery. Or your GP may arrange for you to have one at a later date.

Your GP may suggest you have further tests if the ECG indicates you could have an arrhythmia. Further tests may include some of the following.

  • Blood tests. These can test for certain substances in your blood that might be related to arrhythmia.
  • 24-hour heart monitor (ambulatory ECG). This records the electrical activity of your heart while you go about your usual activities over 24 hours (or longer if necessary). You might be asked to record any symptoms you have too.
  • Exercise ECG (cardiac stress test). This is when you have an ECG while you exercise on a treadmill to see if this triggers an arrhythmia.
  • Echocardiogram or transthoracic echocardiogram. These use ultrasound (sound waves) to produce a clear image of your heart muscles and valves to see how well your heart is working.

Your GP might be able to arrange these tests directly or they might refer you to see a cardiologist who specialises in diagnosing and treating arrhythmia. A cardiologist is a doctor who specialises in identifying and treating heart conditions.

Treatment of arrhythmia

If your arrhythmia is caused by an underlying problem – such as an infection or hormone problem – your doctor will aim to treat this first.

Treatment for arrhythmia will depend on the type of arrhythmia you have, how serious it is and if it’s causing you any symptoms. Treatment may include the following.

  • Self-help measures such as stopping smoking and doing more exercise to improve your heart health. You may also need to cut back on anything that triggers your arrhythmias – for example, alcohol or caffeine.
  • Medicines to control your arrhythmia, and if necessary, to prevent related problems. For instance, taking an anticoagulant to prevent stroke in atrial fibrillation.
  • A cardioversion – this is a procedure that uses an electrical shock to restore your normal heart rhythm.
  • Having a pacemaker fitted. This is a small device that’s implanted under your skin of your chest to regulate your heartbeat.
  • Having an implantable cardioverter defibrillator (ICD). This is a device that can monitor your heart rhythm and deliver an electric shock to correct your heartbeat if it detects a problem.
  • Catheter ablation therapy, in which your doctor uses heat or cold therapy to destroy tissue in the area of your heart that’s causing the abnormal rhythm.

Frequently asked questions

  • If you think a prescription medicine is affecting your heart rate, speak to your GP. Don’t stop taking the medicine without speaking to your GP first. If you’re taking an over-the-counter medicine, ask your pharmacist for advice.

    Certain medicines can cause a change in your heart rate or rhythm, including:

    • digoxin, which treats heart failure
    • beta-blockers, which treat high blood pressure and coronary heart disease
    • calcium-channel blockers, which are mainly used to treat high blood pressure
    • medicines for asthma, such as salbutamol
    • certain antidepressants
    • some antibiotics
    • antihistamines that are used to treat hay fever
    • antifungal drugs

    Always read the patient information leaflet that comes with your medicine. If you’ve been diagnosed with an arrhythmia, it’s also important to ask whether any medicines you’re taking are still suitable.

  • The rules depend on the type of arrhythmia you have, how well it’s controlled and the type of vehicle you want to drive. You shouldn’t drive if you have an arrhythmia that’s affected or is likely to affect your ability to drive. It’s essential that you don’t drive until your arrhythmia is under control, so you don’t put yourself or others in danger.

    As long as you don’t have any symptoms that could distract you when driving, you’ll probably be able to start driving again. But the cause of your arrhythmia must have been identified and your condition controlled for at least four weeks. Ask your doctor if they agree that your condition is controlled.

    If you have symptoms that could distract you from driving (for example, dizziness or breathlessness), you shouldn’t drive. You should also let the Driver and Vehicle Licensing Agency (DVLA) know. See your doctor for advice as you might be able to try another treatment to control your symptoms.

    If you’ve had a procedure to treat your arrhythmia, you won’t be able to drive for a while. This can range from a couple of days to several months depending on the treatment you have.

    The rules about driving and arrhythmia are different if you drive a lorry or are responsible for passengers. For example, you won’t be allowed to drive a lorry or bus if your heart function is below a certain level. Also, your arrhythmia must have been controlled for at least three months.

    If you’re in any doubt about driving, always check with the DVLA first.

  • If you feel like your heart has missed a beat, it may be due to an ectopic heartbeat. These are actually extra beats, outside of your heart’s normal rhythm – but you may feel a pause in your heartbeat afterwards, as your heart rhythm returns to normal. Ectopic beats can also be felt as a sudden thud in your chest.

    Ectopic beats are very common and usually don’t cause any problems. You don’t usually need any treatment if you just get them occasionally and they’re not bothering you too much. Sometimes though, ectopic beats can be associated with more serious conditions, such as structural problems with your heart. If your ectopic beats are bothering you, your GP may be able to treat them with medication. If they need further investigation or treatment, your GP can refer you to a specialist.


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Related information

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  • Reviewed by Pippa Coulter, Freelance Health Editor, November 2019
    Expert reviewer, Dr Tim Cripps, Consultant Cardiologist
    Next review due November 2022



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