Slow heartbeat generally refers to bradycardia. There are many causes of bradycardia, such as physiological factors, myocardial ischemia, hypothyroidism, and sick sinus node syndrome. 1. Physiological factors: bradycardia can be seen in physiological reasons, such as athletes, some healthy people in the sleep situation, can also show bradycardia. 2. Myocardial ischemia: myocardial ischemia can lead to ischemia of the sinus node, and bradycardia can occur after the sinus node function decreases. 3. Hypothyroidism: If there is a lack of thyroid hormone in the body, bradycardia can result due to insufficient thyroid hormone. 4. Sick sinus node syndrome: the decline in sinus node function can cause the heart rate to slow down, showing sinus bradycardia, some patients may also appear fast and slow syndrome. There are many reasons for bradycardia, and it is recommended to go to the hospital in time to improve the examination and take standardized treatment according to the doctor’s instructions, so as not to ignore the symptoms and take it lightly.