Improper beating of the heart, whether too fast, too slow or erratically.

Cardiac arrhythmia is an irregular heartbeat. The heart may beat too fast, too slow or erratically. It happens when electrical signals in the heart don't work as they should.

There may be no symptoms. Or they may include a fluttering, pounding or racing feeling in the chest, chest pain and dizziness.

Some heart arrhythmias do not need treatment. Treatment, if needed, may include medicines, specific actions such as coughing, implanted devices, or a procedure or surgery.