A normal heartbeat is 60-100 beats per minute, and if it is lower than 60 beats per minute, it is called bradycardia. There are many reasons why the heart beats slowly, as follows: 1. Sinus bradycardia is common. Sinus bradycardia is partly physiological bradycardia is a normal phenomenon, common in healthy young people, athletes, manual laborers and sleep. The heart rate is generally 50-60 beats per minute, without any discomfort, the situation generally does not require treatment; 2, part of the pathologic bradycardia can be caused by extracardiac diseases, such as intracranial disease, severe hypoxia, hypothermia, hypothyroidism, and the application of amiodarone, β-blockers, digitalis drugs, etc., this type of bradycardia through the treatment of the primary disease or to remove the cause of the disease, the heart rate can be increased; 3, caused by cardiac disease, the heart rate can be increased; 3, caused by cardiac disease, the heart rate can be increased; 4, caused by cardiac diseases. The bradycardia caused by heart disease, such as sick sinus node syndrome, atrioventricular block, and inferior wall myocardial infarction. Asymptomatic bradycardia usually does not need treatment. If symptoms of insufficient blood supply to the brain such as dizziness, blackout, weakness or even fainting occur because of slow heart rate, atropine or isoprenaline can be applied. However, long-term use of medication often has an uncertain therapeutic effect and is prone to serious side effects, which may require treatment with a pacemaker.