Heart Arrhythmia

What is a heart arrhythmia?

Also known as an irregular heartbeat, an arrhythmia is any abnormality in the heart rate or rhythm.

Arrhythmias can be put into two main categories; too fast a heart beat, or too slow. In a normal adult at rest, the heart beats 60 — 100 times per minute. Bradycardia is when the heart beats at less than 60 beats per minute. Tachycardia is when the heart beats at more than 100 beats per minute.

Arrhythmias can also be categorised according to their origin. Ventricular arrhythmias originate in the ventricles (the two lower chambers of the heart). Supraventricular arrhythmias originate in an area above the ventricles, usually in the atria (the upper chambers of the heart).

Examples of heart arrhythmias are:

  • Atrial fibrillation: a common type of irregular heart rhythm, causing the heart to contract abnormally.
  • Sinus node dysfunction: This usually results in a bradycardia (too slow a heart beat). It can be caused by, for example, hypothermia or severe liver disease.
  • Ventricular fibrillation: This is a major emergency and can be caused by such things as a heart attack (myocardial infarction) or a drowning. With this type of arrhythmia, the ventricles quiver ineffectively, producing no real heart beat, resulting in unconsciousness in the person. Brain damage and death can occur within minutes.

What causes arrhythmias?

There are several different factors that can cause an arrhythmia. These may include:

  • Coronary artery disease
  • Heart attack or other injury to the heart
  • Congenital heart defects and other forms of heart disease
  • Lung conditions and other diseases
  • Electrolyte imbalance in your blood (e.g. levels of sodium or potassium)
  • Medication – arrhythmia can sometimes occur as a side-effect of some medications.

What are the symptoms of a heart arrhythmia?

Symptoms of an abnormally fast heartbeat (tachycardia) can include recurring heart palpitations (you may be able to feel your heart ‘fluttering’), shortness of breath, light-headedness, fainting or near-fainting spells, sweating and chest discomfort.

Symptoms of an abnormally slow heartbeat (bradycardia) can include shortness of breath, fatigue and light-headedness and fainting or near-fainting spells.

Symptoms can also depend on the different types of arrhythmia. A sinus node dysfunction may prove asymptomatic (produces no symptoms). If symptoms are present, they may include fatigue, fainting, or dizziness.

How are arrhythmias treated?

In an emergency, electric shock therapy may be necessary to stop the arrhythmia and restore a normal heart rate.

Other treatment may involve medication to control the heart rate or reduce risk of blood clots, making lifestyle changes or surgery. An implantable device called a pacemaker may be used to control an irregular heart rate in the long-term. In some cases, no treatment at all may be necessary.

Your doctor will decide which treatment, if any, is necessary.

Can heart arrhythmias be prevented?

Some can. For example, if your arrhythmia is a side effect of the medication you are taking, your doctor can change medication or lower your dose.

Some lifestyle measures can also be taken to prevent or control an arrhythmia – including limiting your use of caffeine, nicotine, alcohol and stimulant drugs, and reducing stress through exercise or meditation.

Unfortunately not all heart arrhythmias can be prevented, however it is important to state that occasional, isolated disturbances of the heartbeat are common and usually harmless.

Reviewed: December 11, 2006