When normal heart rhythm (sinus) is lost, it causes arrhythmia. Atrial fibrillation (AF) is the most common type of arrhythmia and it is caused when in normal conditions:
- heart rate increases or decreases.
Heart rate refers to the speed at which the heart beats, i.e., the number of times it contracts per minute. Normally, the heart beats between 60 and 100 times per minute. Arrhythmia occurs when, under normal conditions, heart rate decreases (bradycardia) or increases (tachycardia).
- heart rate becomes irregular.
Heart rate refers also refers to the way the heart beats; whether they are regular or irregular. Heart rate adapts to the needs of the body at all times. This is why it speeds up when we exercise and slows down when we sleep. However, under normal conditions, it must stay regular.