Arrhythmias are caused by a change in the electrical signals of the heart. It may be an abnormal signal or a problem with how the signal moves through the heart. This may happen because of one or more of the following:

  • The heart's pacemaker (sinoatrial [SA] node) is not working as it should. It will set a rate or rhythm that isn’t normal.
  • Damage to the heart that makes it harder for these signals to move through the heart. May be caused by injury or illness such as:
  • A signal to contract starts in areas of the heart other than the SA node.
  • Problems with how your muscles and nerves work.

Factors outside the body that can affect the rhythm of the heart include:

  • Stress
  • Caffeine
  • Tobacco
  • Alcohol
  • Illegal drugs such as cocaine and amphetamines
  • Diet pills
  • Certain medicines, such as those used to treat a cough or cold, heart problems, asthma, depression, or thyroid problems.

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