In our recent clinical work, we have encountered several patients with “AV block”, but unfortunately, they know little about it. Therefore, today we will talk about AV block. As we have described before, the normal heartbeat is generated by the “board of directors” of the sinus node, which sends out “commands”, and then the “commands” are given down layer by layer, so that the whole heart can beat in an orderly manner. First, the “command” from the sinus node causes the atria to beat regularly, and then the “command” is passed to the atrioventricular node. The atrioventricular node is the “middle leader” and is an important conduction channel between the atria and the ventricles. The ventricle follows the sinus node’s “command” and beats regularly together with the atria. The atria and ventricles are like a harmonious “couple” that continues to “go on together” in a synchronized, orderly and regular manner. In the case of “AV block”, the “middle leader” of the atrioventricular node is lazy or on strike, preventing the issuance of “orders” from the sinus node and delaying the issuance of “orders” from the sinus node. “This causes the atrial and ventricular beats to be out of synchronization, which affects the harmonious “couple” relationship between them and reduces the number of ventricular beats, resulting in a slowed heart rate. Atrioventricular block is generally divided into three degrees of atrioventricular block: Ⅰ, Ⅱ and Ⅲ, of which Ⅱ degree atrioventricular block is divided into two types: Ⅱ degree 1 and Ⅱ degree 2. Atrioventricular block of degree I: it is the delay of the “command” from the sinus node to the ventricle. The ventricle tends to lag behind the atrium for a long time before it can beat. If the atria and ventricles are a couple, the ventricles are “home” late for a long time. Atrioventricular block of degree II: This is when the “orders” from the sinus node occasionally do not reach the ventricles. In this case, the ventricle is already “late” occasionally. Grade III AV block: This is when the sinus node “commands” do not reach the ventricles at all. In this case, the relationship between the atria and the ventricles has been completely “broken”, and the ventricles have completely “not come home”. In general, the number of ventricular voluntary beats is very slow, and severe bradycardia occurs at this time. ”In addition to the fact that the atria and ventricles no longer beat together, the main danger of atrioventricular block is that it causes severe bradycardia, resulting in insufficient blood supply. Patients may suffer from chest tightness and dizziness, and even black eyes and fainting due to severe lack of blood supply to the brain, which may lead to sudden death, with very serious consequences. Generally speaking, degree I AV block and degree II type 1 AV block are less likely to have the above mentioned hazards and can be treated conservatively with medication temporarily. In contrast, type II-2 AV block and type III AV block are highly susceptible to these hazards and require pacemaker therapy. Electrocardiogram is the easiest and most effective way to diagnose AV block. Therefore, once symptoms such as chest tightness, dizziness, double vision and syncope occur, count your heartbeat and feel your pulse in time, and if you find that your heartbeat and pulse are slow, you should go to the hospital for an electrocardiogram in time to clarify whether there is “AV block”.