Diastolic septal defect, also known as secondary septal defect, is a common type of atrial septal defect. The treatment of secondary septal defects is generally determined by the age of the child and the location and size of the septal defect. If the child is less than one week old and the septal defect is relatively small, clinical observation is recommended for the time being, as some children will grow and develop and small septal defects will close on their own. If the child is older than three years of age and the septal defect is relatively large, or if the child has obvious symptoms of ischemia, hypoxia, and heart failure due to blood shunts, surgery is recommended, and the specific surgical procedure should be chosen by the surgeon according to the location and size of the septal defect.