• United Kingdom
• Change

Bupa members

Support and offers for individual members and customers

Heart block

Published by Bupa's health information team, June 2008.

This factsheet is for people who have heart block, or who would like information about it.

In heart block, the electrical impulses that control your heartbeat are slowed down or blocked as they travel through your heart. Depending on where in the heart the block happens and how severe it is, this can result in a slow heart rate (bradycardia).

• Animation - The different types of arrhythmia
• About heart block
• Symptoms of heart block
• Causes of heart block
• Diagnosis of heart block
• Treatment of heart block
• Further information
• Questions and answers
• Related topics
• Sources

The different types of arrthythmia

A Flash plug-in is required to view this animation.
Legal notices

About heart block

Your heart is responsible for delivering oxygen and nutrients to the rest of your body via the bloodstream. When your heart beats too slowly, it can't do this as efficiently. This can lead to symptoms such as fainting and black-outs.

What happens in heart block?

Your heartbeat is controlled by electrical impulses, which start in a part of the heart wall called the sinus node, and travel through the heart making it contract. The impulses travel from the atria (the upper chambers of the heart) to the ventricles (the lower chambers) through an area called the atrioventricular (AV) node. The AV node helps to synchronise the pumping action of the atria and ventricles.

If you have heart block, there is a problem affecting how the electrical impulses are transmitted through your heart. When the problem occurs at the AV node, it prevents the impulses being conducted from the atria to the ventricles. This is called AV block. There are three different levels of AV block.

• In first-degree heart block, the electrical impulses are slowed as they pass through the AV node, but all the impulses still reach the ventricles. There are rarely any symptoms with this type of heart block.
• In second-degree heart block, the AV node transmits some impulses to the ventricles, but not others. The impulses can sometimes become increasingly delayed until one is blocked altogether - or it may be that every third or fourth impulse is blocked.
• Third-degree heart block (complete heart block) occurs when no electrical impulses reach the ventricles from the atria at all. The ventricles end up producing their own electrical impulses. This usually results in a very slow heartbeat.

A heart block can also occur in a group of muscle fibres that lead into the ventricles (the bundle of His). This is called bundle branch block. This type of heart block doesn't normally produce any symptoms.

The electrical impulses in a normal heart and a heart with heart block

Symptoms of heart block

Whether or not you have any symptoms from a heart block depends on the type of heart block you have and how severe it is. If the heart block has caused your heart rate to slow down (especially if it's less than 40 beats per minute), you may have the following symptoms:

• dizziness
• fainting, or nearly fainting
• chest pain
• breathlessness following exercise/activity
• seizures, caused by not enough oxygen getting to the brain

These symptoms can also be caused by problems other than heart block. You should visit your GP for advice.

Causes of heart block

Causes of heart block include:

• coronary artery disease
• certain drugs, including digoxin and verapamil
• diseases of the heart muscle
• heart attack
• certain infectious diseases, such as Lyme disease
• some other diseases, such as systemic lupus erythematosus and rheumatoid arthritis
• inherited (congenital) disorders

Diagnosis of heart block

Heart block is often just found by chance when having tests for other problems. However, if you are having symptoms such as dizziness or breathlessness, you should visit your GP for advice. Your GP will ask about your symptoms and medical history, and examine you.

Your GP will probably take your pulse rate and blood pressure. You may also be asked to have a blood test and an electrocardiogram (ECG) - a test that measures the electrical activity in your heart to see how well it is working. An ECG can show up various problems with the heart, including heart block.

If your ECG shows that you have a heart block, or if you have a very low heart rate, your GP will refer you to a cardiologist for further treatment. A cardiologist is a doctor specialising in conditions affecting the heart.

Treatment of heart block

What treatment you have will depend on how severe your heart block is. If your heart block has been discovered by chance and you do not have any symptoms, you will probably not need any treatment at all.

If you are having symptoms or are found to have second-degree or third-degree heart block, you will need to stop any medicines you are taking that may slow your heart rate (such as beta blockers). Any underlying disease you have that is causing your heart block will also be treated. Apart from these measures, the main treatment for heart block is to have a pacemaker fitted.

Surgery

Pacemaker implantation

A pacemaker is a small device, usually implanted under the skin in your upper chest. It monitors your heartbeat and produces electrical impulses to correct your heartbeat if it becomes too slow.

The pacemaker is connected to your heart by one or more leads, which are passed through a blood vessel to your heart. For heart block, pacemakers with two leads (called dual-chamber pacemakers) are normally used. The two leads connect to two different points of your heart - usually your right atrium and right ventricle.

If your doctor thinks you need a pacemaker immediately, you may have a temporary pacemaker inserted until you are able to have a permanent pacemaker. This involves threading a wire into your heart, which keeps the heart pumping regularly.

You will probably have your pacemaker fitted under sedation and local anaesthetic. This means all feeling from the area where the pacemaker is being inserted will be blocked and you will feel relaxed, but stay awake during the procedure.

You will probably be able to go home the day after your procedure, once your cardiologist has checked that the pacemaker is working correctly. It usually takes about six weeks for the wound to heal, but this varies between individuals, so it's important to follow your surgeon's advice.

Further information

• Arrhythmia Alliance
  01789 450787
  www.heartrhythmcharity.org.uk
• The British Heart Foundation
  08450 70 80 70
  www.bhf.org.uk

Related topics

• Arrhythmia
• Cardiovascular system
• Electrocardiogram (ECG)

Sources

• Bradycardia (slow heart rhythm). Arrhythmia Alliance. www.heartrhythmcharity.org.uk, accessed 10 April 2008
• Kumar P, Clark M. Clinical Medicine. 6th ed. Elsevier, 2005:766-770
• Costa DD, Brady WJ, Edhouse J. Bradycardias and atrioventricular conduction block. BMJ 2002; 324:535-538
• Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2005:346-347
• Pacemaker information. Arrhythmia Alliance. www.heartrhythmcharity.org.uk
• Pacemakers. British Heart Foundation, January 2005, Health information series, number 15. www.bhf.org.uk

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Dr Tim Cripps DM FRCP, Consultant Cardiologist, specialist in electrophysiology, Bristol Royal Infirmary, and by Bupa doctors. It has also been reviewed by Arrhythmia Alliance. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: June 2008