Heart block is a type of arrhythmia that can be categorized into three degrees; first degree block is mild, second degree block is more dangerous, and third degree block is the most dangerous and requires prompt treatment. First-degree conduction block is generally not dangerous, and is mild enough that you will not feel any significant discomfort. Second-degree conduction block is more dangerous and usually presents symptoms of palpitations and chest tightness. If dizziness or fainting occurs, it is important to go to the hospital for timely treatment. Third-degree conduction block is the most serious, and may cause fainting, transient loss of consciousness, or even sudden death in severe cases. Therefore, for patients with third-degree block, pacemaker treatment is generally recommended in the clinic. Heart block is common in patients with coronary artery disease, myocarditis and cardiomyopathy, and when discomfort occurs, it is necessary to actively consult the doctor and follow the doctor’s instructions for reasonable treatment.