Our heart beats regularly since we were in our mother’s womb, neither too fast nor too slow, with the same amount of time between any two heartbeats, which we call sinus rhythm. For a long time, we felt comfortable with such a normal heartbeat. When atrial fibrillation strikes, this regular rhythm of the heart is disrupted and replaced by an overwhelming feeling of panic. It’s a kind of flip-flopping sensation, the feeling of carrying a small rabbit in one’s arms, as the common people usually say. In a normal human heart, the atria are at the top and the ventricles are at the bottom. The beating of the ventricles is controlled by the atria. That is, every time the atria beat, the ventricles will follow in the next very short period of time. In this way, the atria and ventricles work in unison, contracting at the same time as they contract, and diastole at the same time as they diastole, to accomplish the overall contractile function of the heart. When atrial fibrillation occurs, the atrial beats become extremely fast and irregular, with a frequency of 300 to 600 beats per minute. The ventricles cannot keep up with such a fast atrial rate. And the ventricles cannot beat as fast as the atria. Because, if the ventricles were to beat more than 180 times per minute, the heart would not be beating, it would be writhing, and the patient would be hypotensive or even in shock. So, when atrial fibrillation occurs, the 300 beats per minute of the atria compete for control of the ventricles. It may be that any one of the atrial beats will act to finger the ventricle to beat once. So, in atrial fibrillation, the ventricles beat fast and slow, sometimes up to 100 to 160 beats per minute, and definitely not neatly; sometimes there is a long gap between two heartbeats, and sometimes several heartbeats in a short period of time. The initial stages of atrial fibrillation are episodic, i.e., the atrial fibrillation lasts for tens of seconds to several minutes or longer, and then reverts on its own to sinus rhythm (i.e., a normal heart rhythm). At this time, people are very sensitive and intolerant to the onset of atrial fibrillation. It is usually possible to clearly state when AF starts and when it stops. It is recommended that people with atrial fibrillation make a note of when you had your first episode of atrial fibrillation, as this is very important for the treatment of atrial fibrillation.