Ventricular septal defects are categorized into small, medium and large, and their severity is related to the type of disease. Generally, small defects are not serious, but when the diameter of the defect is more than 5mm and accompanied by abnormal symptoms, or the diameter of the defect is more than 10mm, then it is more serious. 1. Small ventricular septal defects: Small ventricular septal defects mean that the diameter of the defect is less than 5mm, the patient’s activities are not limited, and most of the defects can be closed before the age of 3 years. Regular follow-up is sufficient, but if there is infection, surgery is needed immediately. 2. Medium-sized ventricular septal defect: the diameter of the defect is 5~10mm, which is relatively serious. If there are no symptoms, there is no need to be too nervous. If there are recurrent lung infections, developmental delays, or other cardiopulmonary anomalies, it is a more serious condition and should be treated promptly. 3. Large ventricular septal defect: the diameter of the defect is more than 10mm, and it is usually accompanied by obvious pulmonary hypertension, bruising, and gradually aggravated, which is more serious. If ventricular septal defects occur, it is recommended to consult a doctor as soon as possible and follow the doctor’s instructions for treatment as soon as possible, so as to avoid gradual aggravation of the condition and irreversible consequences.