In a 14 year old patient with tachycardia, a non-organic disease is usually considered the cause, i.e. physiologic tachycardia. Usually at the age of 14, the normal value of heart rate should be 60-100 beats per minute. If tachycardia occurs, it should be considered whether it is caused by neurological diseases, such as cardiac neurosis, vegetative nerve dysfunction, e.g., tachycardia is caused by nervousness, anxiety, or excessive pressure in study or life, or tachycardia is caused by poor quality of rest and sleep, or excessive consumption of strong tea, strong coffee, etc., which stimulates the vegetative nerve function and causes tachycardia. For example, tachycardia is caused by nervousness, anxiety, study stress, life stress, poor rest and sleep quality, or excessive consumption of strong tea or coffee, which stimulates the vegetative nerve function and causes tachycardia. In addition, patients with endocrine metabolic diseases, such as hyperthyroidism, may also have a rapid heartbeat. Finally, cardiogenic diseases should be considered, such as myocarditis, congenital heart disease, heart valve disease, which can also have tachycardia.