The presence of a small amount of fluid in the pericardium is not necessarily a cardiac disease. In normal people, a small amount of fluid can also be present in the visceral and mural layers of the pericardium, and may be due to certain non-cardiac diseases. 1. A small amount of fluid, about 50 ml, can be found in the normal human pericardial visceral and mural layers, which is physiologic. 2. When it exceeds 50mL, the pericardial effusion is pathologic. Systemic diseases such as malnutrition and anemia can lead to pericardial effusion. Cardiac diseases such as cardiac insufficiency, heart failure, tumor metastasis to the pericardium, rheumatic heart disease, valvular heart disease will also appear pericardial effusion, the presence of a small amount of pericardial effusion is not necessarily a heart disease. 3. When serious pericardial effusion occurs, it is necessary to consult a doctor for timely treatment under the doctor’s guidance, avoid strenuous exercise, pay attention to balanced nutrition, pay attention to rest, and avoid exertion.