What is the definition or description of: arrhythmia?

Irregular Heart Beat: An arrhythmia is any type of irregular heart beat. It might be a simple skip of the heart beat, or a transient pause which is usually benign. However, there are also more serious types of arrhythmias when the heart races or goes too slowly. The most serious types of arrhythmias are when the ventricle or lower chamber of the heart beats too fast. This can lead to fainting or even sudden death.