An irregular heartbeat is an arrhythmia (also called dysrhythmia). Heart rates can also be irregular. A normal heart rate is 50 to 100 beats per minute. Arrhythmias and abnormal heart rates don't necessarily occur together. Arrhythmias can occur with a normal heart rate, or with heart rates that are slow (called bradyarrhythmias -- less than 60 beats per minute). arrhythmias can also occur with rapid heart rates (called tachyarrhythmias -- faster than 100 beats per minute). In the United States more than 850,000 people are hospitalized for an arrhythmia each year.

What Causes an Arrhythmia?

Arrhythmias may be caused by many different factors, including:

• Coronary artery disease.
• Electrolyte imbalances in your blood (such as sodium or potassium).
• Changes in your heart muscle.
• Injury from a heart attack.
• Healing process after heart surgery.

Irregular heart rhythms can also occur in "normal, healthy" hearts.