Cardiomyopathy is a group of diseases that mainly involve the myocardium. Its etiology is unclear, and most people believe that it is a multi-source disease, such as viral infection, immunity, free radicals, and genetics can cause cardiomyopathy. Diagnosis of cardiomyopathy 1. Mostly seen in children over 3 years old, some of them can have positive family history. 2. No clear history of viral myocarditis. 3.Exclude other known causes of heart disease and chronic constrictive pericarditis. 4. At least one of the following is positive: (1) large heart; (2) congestive heart failure without other causes; (3) ECG with ST-T changes or various arrhythmias without other explanations; (4) history of syncope with large heart; (5) body or pulmonary vein embolism without other explanations.