Atrioventricular block refers to the process in which the impulse sent by the sinoatrial node is partially or completely, temporarily or permanently blocked in the atrioventricular connection area due to physiological or pathological reasons during the process of transmission from the atrium to the ventricle. According to the degree of block, it can be divided into three degrees: the first degree is that the atrioventricular conduction time is prolonged, but the atrial impulse can be transmitted to the ventricle; the second degree is that some impulses cannot be transmitted to the ventricle; the third degree is that all impulses cannot be transmitted to the ventricle, so it is also called complete atrioventricular block.