Incomplete intra-atrial conduction block is caused by ectopic excitation of the impulse in the atria, which invades the sinus node during depolarization and prevents or delays the downward transmission of the excitation. The following are the symptoms that are easily confused. 1.Complete intra-atrial conduction block, i.e., atrial separation. Most often seen in the critical phase of organic heart disease. It also often occurs in the hours before death in critically ill patients. In addition, digitalis poisoning. The effects of uremia and drugs (e.g., amiodarone) can also be seen. Mostly manifested as clinical manifestations of the primary disease. 2. Diffuse complete intra-atrial conduction block and sinus-ventricular conduction are both caused by hyperkalemia. Only the latter is a widespread electrical paralysis of the atrial muscle. The atrial muscle loses excitability and conduction. In contrast, the sinus node. The inter-nodal bundle and atrioventricular conduction system are still excitatory and conductive. In the former case, all the conduction bundles and atrial muscles in the atria lose excitability and conduction. This is manifested as sinus arrest. When sinus arrest is prolonged. It can cause dizziness or syncope. Even A.S. syndrome may occur. Prolonged sinus arrest without escape beats can lead to sudden death. It can lead to sudden death. Sinus atrial block is a relatively rare arrhythmia in which the impulses generated by the sinus node cannot reach the atria partially or completely, causing the atria and ventricles to stop at one time or more than two times in a row. Acute sinus block is caused by acute myocardial infarction, acute myocarditis, digitalis or quinidine, and vagal hypertension. Chronic sinus block is commonly associated with coronary artery disease, primary cardiomyopathy, vagal hypertonia, or morbid sinus node syndrome of unknown origin.