Complete Heart Block

Failure of the system that conducts electrical impulses from the atria to the ventricles

  • More common in elderly people
  • Smoking, a high-fat diet, lack of exercise, and excess weight are risk factors
  • Gender and genetics are not significant factors

In complete heart block, damage to the heart’s conductive tissue prevents electrical impulses from the atria (upper chambers) from reaching the ventricles (lower chambers), so that the ventricles cannot contract normally. Heart muscle contracts automatically in the absence of a regulating signal. In complete heart block, the ventricles contract at about 40 beats per minute or less instead of the usual rate of 60–80 beats per minute, which greatly reduces the heart’s efficiency. In some cases, the heart may stop beating altogether for up to 20 seconds.

The tissue damage that causes complete heart block is more common in elderly people and is linked with coronary artery disease, for which lifestyle factors such as smoking increase the risk. Sudden complete heart block, which may be either temporary or permanent, may follow a heart attack (see Myocardial infarction).

What are the symptoms?

The symptoms may come on gradually or suddenly and typically include:

  • Palpitations (awareness of an irregular abnormal or heavy heartbeat).

  • Light-headedness, and loss of consciousness if the heart stops beating.

  • Shortness of breath.

  • Chest pain.

If it is left untreated, complete heart block may lead to acute heart failure, chronic heart failure, stroke, shock, and even death.

The heart’s electrical system

Normally, electrical impulses pass from the sinoatrial node to the atrioventricular node and then to the ventricles. In complete heart block, the pathways to the ventricles are blocked and impulses cannot reach them.

What might be done?

Complete heart block is usually suspected if you have a very slow heartbeat and is confirmed by electrocardiography (see ECG). Initial treatment may involve temporary insertion of a pacing wire into the heart; the wire transmits electrical impulses that restore a normal heartbeat until a permanent cardiac pacemaker can be fitted. The general outlook depends on whether there is an underlying disorder, such as coronary artery disease.

Treatment: Cardiac Pacemaker

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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