Common causes of cardiac arrest include coronary heart disease, myocardial infarction, myocarditis, aneurysm rupture or respiratory disease. 1. Coronary heart disease: coronary heart disease may lead to cardiac arrest, the main reason is that patients with coronary heart disease have acute myocardial ischemia, resulting in myocardial necrosis, causing abnormalities in the cardiac conduction system, triggering cardiac arrest. 2. Myocardial infarction: acute myocardial infarction is myocardial necrosis caused by acute and persistent ischemia and hypoxia of coronary arteries. Clinically, there are severe and persistent retrosternal pain, which cannot be relieved by rest and nitrate drugs, accompanied by increased serum myocardial enzyme activity and dynamic changes in electrocardiogram, which is often life-threatening. 3. Myocarditis: acute myocarditis can lead to abnormalities of myocardial blood supply and ejection function, resulting in cardiac arrest. 4. Ruptured aneurysm: Aortic aneurysm refers to an abnormal localized or diffuse dilatation of the aortic wall, which can lead to cardiac arrest when the aneurysm ruptures. 5. Respiratory diseases: These include respiratory inflammation, respiratory metaplasia, pleural diseases, foreign bodies in the respiratory tract, laryngeal spasm and edema, persistent unrelieved asthma, acute respiratory paralysis, congenital malformations, and lung tumors, which lead to cardiac arrest caused by hypoxia. Cardiac arrest requires immediate cardiopulmonary resuscitation (CPR) and a call to 120 for emergency care.