Disorders of heart rate and rhythm are caused by disturbances in the heart’s electrical system and are very common, particularly in elderly people. These disorders do not always cause symptoms and are sometimes detected only during routine health checkups. Treatment usually consists of drugs, although newer techniques that use carefully controlled electric currents are also used.
A healthy adult has a resting heart rate of 60–80 beats per minute, although this rate rises during exercise. Children have a higher resting heart rate, while that of very fit adults and the elderly may be as low as 50 beats per minute. Disorders that affect the pumping action of the heart may increase or decrease the heart rate, alter its rhythm, or, in cardiac arrest, stop the heart pumping altogether. Many of these disorders have coronary artery disease or heart failure as an underlying cause. The first article in this section describes ectopic beats, which are extra, isolated heartbeats. This article is followed by an overview of arrhythmias, which are abnormal heart rates and rhythms, and a discussion of individual types of arrhythmias. The final article discusses cardiac arrest, which is the sudden and complete failure of the heart to pump blood caused by a disturbance in its electrical system. Cardiac arrest is a potentially fatal condition and requires emergency medical treatment.
For more information on the structure and function of the heart, see Blood Flow Through the Heart.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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