This is mainly related to the incomplete neurological function of the pediatric population. During the neonatal period, the innervation of the heart maintains its fetal characteristics, both sympathetic nerves are dominant and the vagus nerve is not yet well developed and its excitability is low. Because of the strong activity of sympathetic nerves, the heart rate of infants is faster and easily accelerated by various factors. after the age of 5, the heart has the neurological structure characteristics of adults, and by the age of about 10, it is mature and the heart rate gradually approaches that of adults. Secondly, because of the high metabolism of children, the body systems need more blood supply, but the contraction force of the heart muscle of children is weak, the heart beats less, in order to meet the needs of the body, the heart needs to increase the number of beats. Therefore, the heart rate of pediatric patients is faster than that of adults. The younger the child is, the faster the heart rate is. The heart rate of children is easily influenced by various factors. For example, the heart rate can increase significantly during meals, crying, activity, and nervousness. When a child has a fever, the heart rate can increase by 15-20 beats/min for every increase in body temperature.