A heart rate of less than 50 indicates bradycardia, which can be seen in sinus bradycardia, sick sinus node syndrome, and third-degree atrioventricular block. 1. Sinus bradycardia can be seen in healthy young people, athletes, and people who are asleep, and does not require treatment. It can also be seen in hypothyroidism, hypothermia, craniocerebral trauma or taking heart rate-lowering drugs, etc. When there are symptoms of insufficient blood flow due to a slow heart rate, it is necessary to inform the doctor in time to adjust the treatment program. 2. Sick sinus node syndrome: sinus bradycardia occurs in sinus node disease caused by various reasons. If there is no bradycardia-related symptoms, no treatment is needed and regular observation is enough, but if there are symptoms, a pacemaker should be installed in accordance with the doctor’s treatment plan in time. 3. Third-degree atrioventricular block: it can be seen in coronary heart disease myocardial infarction, myocarditis, primary hypertension and other diseases, and it needs to be treated with a pacemaker according to the doctor’s treatment plan. If the heart rate is lower than 50 beats/minute, you need to go to the hospital, clarify the cause of the disease, and ask the doctor to guide the treatment.