Arrhythmias occur when the electrical signals to the heart that coordinate heartbeats are not working properly. For instance, some people experience irregular heartbeats, which may feel like a racing heart or fluttering. Any interruption to the electrical impulses that cause the heart to contract can result in arrhythmia.

For a person with a healthy heart, they should have a heart rate of between 60-100 beats per minute when resting.The more fit a person is, the lower their resting heart rate. Olympic athletes, for example, will usually have a resting heart rate of under 60 beats per minute because their hearts are very efficient.