Atrioventricular block is a blockage of impulses during atrioventricular conduction. There are two types of block: incomplete and complete. The former includes first- and second-degree AV block, while the latter is also called third-degree AV block, and the block can be in the atrium, AV node, Hitchcock’s bundle and double bundle branches. In complete AV block, the temporal relationship between the atria and the ventricles is separated, and the atria lose their auxiliary pumping effect on ventricular contraction, resulting in a decrease in cardiac output. The differential diagnosis of loss of atrial pumping of ventricular contraction: (1) Congenital complete AV block: Most cases coexist with congenital heart disease and are associated with hypoplasia or defects in the atrioventricular node, bundle of Hirschsprung and its bundle branches. When combined with complex cardiac malformations, wide QRS wave abnormalities in escape rhythm and prolonged Q-T interval, the prognosis is poor. Most patients with complete congenital AV block are asymptomatic. However, some patients may later develop syncope and require pacemaker placement, and a few may suffer sudden death. The response of the escape point to atropine and the recovery time of atrioventricular handover escape can help to estimate the possible symptoms and prognosis of the patient. (2) Acute acquired complete AV block: Complete AV block caused by injuries such as acute myocardial infarction, drugs, cardiac surgery, cardiac catheterization and catheter ablation is often transient. In approximately 10% of cases, the block may be in the Hitchcock bundle, the escape point is often located within the bundle branch-Purkinje fibers, the frequency is <4 beats/min and is not constant, and the QRS waves are often wide and distorted. This injury is often irreversible and requires pacemaker placement. Second- or third-degree Hippocampal system block can occur after the application of certain antiarrhythmic drugs, especially drugs that inhibit sodium fast channels, such as lidocaine, procainamide, and propyzamide, in those with pre-existing Hippocampal system lesions. Surgical treatment of aortic valve lesions and ventricular septal defects tends to damage the Hitchcock bundle, which has a high incidence of postoperative complete AV block. Patients with pre-existing left bundle branch block can have complete AV block due to the development of right bundle branch block when right heart catheterization is performed. In most cases bundle branch injury due to cardiac catheterization is temporary and recovers in a few hours. Complete AV block can also occur during radiofrequency or DC ablation for tachyarrhythmias when the catheter is ablated close to the AV node. (3) Chronic acquired complete AV block: This is usually due to extensive myocardial scarring of various etiologies, especially atherosclerosis, dilated cardiomyopathy, and hypertension, idiopathic cardiac fibrous stent sclerosis (Lev disease), and fibrous degeneration of the conduction system (Lenegre disease), which can lead to chronic progressive exacerbation of bundle branch and branch block. Calcified mitral and aortic annulus, degenerative changes, stenosis, and calcified mitral aortic valve can also cause severe AV block, mainly involving the proximal part of the bundle of Hirschsprung. Other diseases such as nodal disease, rheumatoid arthritis, hemochromatosis, hereditary neuromuscular disease, syphilis, thyroid disease (hyper- or hypothyroidism), and metastatic tumors of the AV node can cause chronic complete AV block. These blocks tend to be permanent and often require the placement of an artificial pacemaker.