The number of heartbeats per minute in a normal person in a quiet state is the heart rate, which is generally 60-100 beats per minute and can vary depending on age, gender or other physiological factors. Generally speaking, the heart rate is faster in infants and children, and slows down in older people as they age. Women’s heart rates are faster than men of the same age, and these are normal physiological phenomena. When the heart rate exceeds 100 beats per minute (usually not more than 160 beats per minute) in adults at quiet time, it is called sinus tachycardia, which is common after transportation, emotional tension and excitement, after drinking strong tea or coffee, and can also be seen in pathological states such as infection, fever, anemia, hyperthyroidism, heart failure, or after the application of heart rate elevating drugs such as atropine, epinephrine, ephedrine, isoprenaline, etc. When the adult’s heart rate is below 60 beats/minute at quiet (usually above 45 beats/minute), it is called sinus bradycardia, which can be seen in healthy people and athletes who have been engaged in heavy physical work for a long time; it can also be seen in hypothyroidism, increased intracranial pressure, hypothermia, and overdose of digitalis, quinidine, or benzos. If the heart rate is less than 40 beats per minute, conditions such as pathological sinus node syndrome and high atrioventricular block should be considered. Atrial fibrillation should be considered if the pulse is unequal in strength and less than the heart rate. Therefore, by monitoring changes in heart rate, combined with medical history, physical examination and other ancillary tests, physicians are able to detect and diagnose the disease in a timely manner. Generally, after effective treatment for the cause of the disease, the heart rate mostly becomes normal range.