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Arrhythmia

This factsheet is for people who have an arrhythmia or for people who would like information on arrhythmia.

An arrhythmia is a disturbance of the normal rhythm of the heart. Arrhythmias are very common and affect over 700,000 people in England. Arrhythmias may occur naturally, or be due to heart disease or other causes, such as a reaction to a medicine. An arrhythmia may occur continuously or just occasionally.

The heart

The heart pumps oxygen-rich blood through a network of blood vessels, the arteries, to tissues including organs, muscles and nerves, all around the body. For information on the heart and how it works, please see the BUPA factsheet, The cardiovascular system.

The heartbeat

A heartbeat starts as a small electrical impulse in a special part of the heart wall called the sinus or sinoatrial node (SAN). This is sometimes called the heart's natural "pacemaker". A network of nerves conduct this impulse across the top chambers of the heart (atria) to the atrioventricular node (AVN). The impulse is then rapidly transmitted down the main conducting pathway in the muscle between the two lower, larger, chambers (ventricles).

Your heart will normally beat between 60 and 100 times a minute when you are resting.

Each heartbeat can be shown electronically on a heart tracing, also called an electrocardiogram or ECG.

Illustration of the heart and heart tracing

Everyone experiences some variation in their heartbeat at certain times and may occasionally feel palpitations. Palpitations are an unpleasant awareness of your heartbeat, often described as a thumping in the chest and can be quite normal. Examples of normal changes in the heart rate include the following:

Sinus tachycardia

This is when the heartbeat is still regular - in the normal "sinus" rhythm - but faster than is usual, ie more than 100 beats per minute. This is a normal response in some situations, such as during exercise or if you are stressed, feeling strong emotions or have a fever. However, it can also happen if you have an overactive thyroid gland or anaemia.

Sinus bradycardia

This is when the heartbeat is still regular, but slow, ie less than 60 beats per minute. Bradycardia is common in athletes and can also occur as a normal response if you are exposed to the cold and have a low body temperature, have an underactive thyroid or are feeling sick.

Ectopic beats

These are extra heartbeats and are very common. They are usually normal. They may be made worse if you consume caffeine and are most noticeable when resting. Ectopic beats are not usually dangerous and don't damage the heart.

Arrhythmia

An arrhythmia is when the heart beats in an abnormal rhythm. The heart rate can become abnormally rapid, slow and/or irregular.

Types of arrhythmia

There are a number of different types of arrhythmia including those listed below:

Atrial fibrillation (AF)

This is a common cause of arrhythmia. It occurs when the muscle fibres in the atria don't contract together; instead they flicker, while the ventricles contract irregularly.

This irregular movement causes turbulent blood flow in the heart. It's possible that a blood clot may form. This may then move in the blood to other parts of the body, sometimes to the brain where it can cause a stroke.

Atrial tachycardia (AT)

Also known as supraventricular tachycardia (SVT), this occurs when an area in the atrium other than the sinoatrial node (the heart's own pacemaker) also produces electrical impulses. This overrides the normal pacemaker with regular impulses in rapid succession, causing the heart to beat at between 140 and 240 beats per minute.

Atrial tachycardia can begin suddenly and unpredictably, and cause the ventricles to contract rapidly too. An attack of atrial tachycardia may only last for a few minutes but it can last several hours. Urgent treatment is usually needed to stop the attack.

Ventricular tachycardia (VT)

Also known as broad complex tachycardia, this is when the ventricles contract rapidly but the rate in the atria remains normal. This can be caused by an increased electrical activity of the electrical impulses to the ventricles. Ventricular tachycardia usually causes sudden collapse. It often happens after a heart attack and if not dealt with promptly, with medical treatment, will result in death.

Ventricular fibrillation (VF)

This is when the whole heart stops beating properly and just flutters. It may follow on from ventricular tachycardia. Blood is not circulated to the brain and the rest of the body and the person usually suddenly collapses and does not have a detectable heartbeat. lf this happens to a friend or family member call the emergency services and start basic life support. If the heartbeat is not rapidly restarted with a defibrillator (equipment that applies an electric shock to the heart), the person will die.

Heart block

Heart block causes an abnormally slow beat. This happens if the impulses generated by the heart's normal pacemaker don't reach the ventricles properly. It may happen after a heart attack if the heart muscle is damaged, or if you have an injury or a disease of part of the heart's conducting system.

Symptoms

You may not notice any symptoms of an arrhythmia. If you do have symptoms, they will depend on the type of arrhythmia you have and how severe it is. Symptoms may include:

• palpitations
• dizziness
• fainting or collapsing
• breathlessness
• chest pain
• angina pain - for more information about angina, please see the separate BUPA factsheet, Angina

Rarely, some types of arrhythmia may result in sudden death.

Causes

There are several causes of arrhythmia, such as the sinoatrial node (SAN) firing more quickly or slowly (sometimes both) or another part of the heart taking over the job of the SAN.

These problems may be due to factors such as:

• underlying heart disease
• heart valve problems
• thyroid disease
• high blood pressure
• Wolff-Parkinson-White syndrome
• side-effects of some drugs
• consuming caffeine
• smoking
• drinking excess alcohol
• low levels of potassium in the blood (hypokalaemia)

Sometimes there may be no known cause for an arrhythmia.

Diagnosis of abnormal heart rhythms

Your GP will ask you about your symptoms and examine you. He or she will listen to your heart. If necessary, your GP will refer you to a cardiologist, a doctor that specialises in heart conditions.

Your cardiologist may do more tests including:

• blood tests
• a resting or an exercise ECG
• a 24 hour heart monitor (also known as an ambulatory ECG)
• an echocardiogram

For more information on these tests, please see the separate BUPA factsheet, Diagnosing heart conditions.

You may have electrophysiology tests as part of an angiogram. This is used to determine which part of your heart is responsible for an abnormal rhythm. A thin flexible tube (called an electrode catheter) will be inserted into an artery or vein, usually in your groin and threaded up to your heart. This will stimulate your heart and record the electrical impulses.

Treatment

Sometimes all you may need is reassurance that the palpitation is harmless. It is also helpful to avoid any triggers if you know of any, such as stimulants like caffeine or alcohol.

If your palpitation is troublesome, there are a number of treatments available. Your treatment will depend on the type and cause of arrhythmia. Treatments include the following.

Drug treatments

Your doctor may prescribe medicines called anti-arrhythmics. Examples include digoxin and flecainide (eg Tambocor). These drugs will slow down a fast heartbeat or help it return to normal.

If you have atrial fibrillation you may be advised to take aspirin or blood-thinning drugs regularly such as warfarin to reduce the risk of blood clots forming.

Cardioversion

In this procedure, a controlled electrical current is applied to the chest wall, which is synchronised with the heartbeat pattern seen on the ECG. This helps your heart to return to its natural rhythm.

This treatment is performed under a general anaesthetic, which means that you will be asleep throughout the procedure and will feel no pain.

Pacemaker implant

A pacemaker implant is a small electrical device, which produces electrical impulses. It ensures that your heart does not go too slowly so is used to treat heart block or slow rhythms (bradycardias) when the heart's own natural pacemaker is not working properly. A pacemaker implant is inserted under the skin of the chest and is connected to the heart muscle with thin wires. You will be given a local anaesthetic that numbs the area but you will be awake.

Catheter ablation therapy

In this procedure, the abnormal areas in your heart that are creating the arrhythmia will be identified and destroyed. Catheter ablation therapy is carried out using the same catheters as are used for electrophysiological testing, and may be carried out at the same time. Radio frequency energy emitted from the tip of the catheter is used to destroy the areas of the heart that are causing an arrhythmia.

You will be given a local anaesthetic that numbs the area but you will usually be awake.

Implantable cardioverter-defibrillator

An implantable cardioverter-defibrillator (ICD) is an implanted device that's fitted in the chest like a pacemaker. It's used if you have had, or are prone to, episodes of life threatening ventricular arrhythmias eg ventricular tachycardia. It recognises the abnormal heart rhythm as soon as it starts and sends a small shock to your heart, which quickly stops the arrhythmia.

The treatment that you will have will depend on your condition. Your doctor will advise you which treatment is best for you.

Further information

• British Heart Foundation
  08450 70 80 70
  www.bhf.org.uk

Sources

• 25,000 lives saved by speedier heart treatment. Department of Health.
  www.dh.gov.uk
  accessed 4 March 2005
• Longmore M, Wilkinson I, Torok E. Oxford Handbook of Clinical Medicine. Oxford: Oxford University Press, 2001.
• Palpitation. British Heart Foundation. Heart Information Series Number 14. January 2005.
  www.bhf.org.uk
• Abnormal heart rhythms (arrhythmias). UK Department of Health. PRODIGY patient information leaflet.
  www.prodigy.nhs.uk
  accessed 6 January 2006
• PRODIGY Guidance - Atrial fibrillation. UK Department of Health. PRODIGY.
  www.prodigy.nhs.uk
  accessed 6 January 2006
• Supravetricular tachycardia. UK Department of Health. PRODIGY patient information leaflet.
  www.prodigy.nhs.uk
  accessed 9 January 2006
• BNF British National Formulary 50, September 2005.

Reviewed by Dr James Quekett, Bsc.MB Ch.B MRCGP DRCOG DFFP, partner/principal general practitioner at Rowcroft Medical Centre.

Published by BUPA's health information team, healthinfo@bupa.com, July 2006.

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