In order for the normal heart to contract and pump blood, it must be driven by electricity. The normal electrical engine of the heart is the sinus node, which gives out electrical impulses that are then transmitted through the atrial muscle to the AV node and left atrium, and then to the bundle of Hitchcock and Purkinje cells to agitate the ventricular muscle and complete a single electrical activity of cardiac contraction. A problem in any of this steps, i.e., an abnormal engine or an abnormal circuit, can lead to arrhythmias, where the heart fails to contract and pump properly. An engine failure is a pathological sinus node syndrome; a circuit failure is a conduction block. Those occurring between the sinus node and the atria are called sinus atrial block, those between the atria and the ventricles are called atrioventricular block, in addition to intra-atrial block, intraventricular block, bundle branch block and so on. Among them, atrioventricular block is more common. The causes of heart engine or circuit failure are: (1) Myocardial inflammation of various causes is the most common, such as rheumatic, viral myocarditis and other infections. (2) Vagus nerve excitation, often manifested as transient slowing of the heartbeat. (3) Drugs: such as digoxin, cortisone, cardioplegia, etc., may cause slowing of the heart rate after long-term use, and most of them are able to recover after stopping the drug. (4) Various organic heart diseases such as coronary heart disease, rheumatic heart disease and cardiomyopathy. (5) Hyperkalemia, uremia, etc. (6) Idiopathic conduction system fibrosis, degenerative changes (i.e. aging), etc. (7) Trauma, accidental injury during cardiac surgery or catheter ablation during interventional procedures. In cases of severe heart engine or circuit failure, such as severe sinus arrest, severe second-degree type II and third-degree AV block with significantly slow ventricular rate, accompanied by significant symptoms such as syncope, loss of consciousness, and episodes of As syndrome, treatment by pacemaker installation is required to avoid prolonged cardiac arrest that may lead to life-threatening injuries. A pacemaker is a medical electronic device implanted in the human body, which maintains a normal heartbeat by distributing a certain form of electrical impulse and stimulating the heart through a pacing lead (artificial circuit) to simulate the formation and conduction of normal heart impulses. Therefore, it can be solved regardless of engine failure or circuit failure. Arrhythmias caused by other reversible factors must be excluded before installing a permanent pacemaker. 2. Reversible factors include: electrolyte disorders, long-term use of heart rate slowing drugs, slow arrhythmias due to inferior wall infarction, myocarditis, diabetes, thyroid abnormalities, metabolic syndrome, etc. When these reversible factors are removed, the malfunction can often disappear. When it is determined that the slow heart rate is caused by irreversible factors, such as advanced age, congenital heart disease, myocarditis sequelae, surgical injury, trauma, etc., pacemaker implantation therapy can be performed after a clear diagnosis based on the electrocardiogram. Simply put, pacemaker therapy is required when the heart rate is below a certain standard, or when the heart rate is not below that standard but there are obvious clinical symptoms (syncope, weakness, loss of consciousness, etc.). 3. How are pacemakers installed in the human body? It is usually done in the cardiac catheterization laboratory, where absolute sterility is required to avoid infection. Generally, the pacemaker is installed under the skin on the chest. The doctor first sterilizes it, lays a sterile sheet, applies local anesthesia, makes a small incision, makes a capsule, punctures the vein or cuts the vein, passes the wire, delivers the lead to the ideal position in the heart under X-ray fluoroscopy, tests the parameters, fixes it if it meets the requirements, and connects the lead to the pacemaker and puts it in the capsule. It is sewn up and gauze wrapped and it is ready. Generally speaking, pacemakers can be classified as single-chamber, dual-chamber, or triple-chamber pacemakers. The appropriate type of pacemaker for a patient must be considered in light of the patient’s age, type of arrhythmia, co-morbidities and other factors. In recent years, with the continuous research and development of pacemaker technology, pacemakers have expanded from simple treatment of slow arrhythmias to the treatment of various diseases, such as prevention of atrial fibrillation and prevention and treatment of long QT syndrome. A kind of pacemaker called buried cardioverter-defibrillator (ICD) is gradually recognized, which has the functions of defibrillation, cardioversion, anti-tachycardia pacing and anti-bradycardia pacing after implantation, and can effectively reduce the morbidity and mortality of patients at high risk of sudden death.