Ventricular septal defect (VSD) is a disruption of the septal tissue integrity of the two ventricles, resulting in abnormal traffic between the right and left ventricles, and can exist as a separate malformation or as a component of other complex cardiac malformations, such as tetralogy of Fallot, complete atrioventricular canal malformation, transposition of the great arteries, tricuspid atresia, and permanent arterial trunk. The incidence of VSD as the only or major lesion is about 0.2% in newborns. the incidence of VSD in congenital heart disease is about 12-20% in newborns, which is the highest incidence among all congenital heart diseases. 2, embryonic development and pathogenesis Embryonic development to the end of the first month, the tubular type of single-chamber heart is atrioventricular. At the beginning of the second month, the primitive ventricular chambers begin to separate, and along with the formation of the interventricular septum, the muscular part of the primitive ventricular septum appears at the bottom of the ventricle, which grows upward along the anterior and posterior edges of the ventricle and gradually divides the ventricular cavity into two, with a half-moon interventricular foramen remaining in the central part above it. As the cavity develops, the ventricular foramen gradually shrinks, and at the end of normal and 7th week, the conical septum growing downward, the enlarged dorsal endocardial pad right inferior node, and the developing sinus septum fuse with each other to close the interventricular foramen and form a complete ventricular septum, completely separating the left and right ventricular cavities. If an abnormality occurs during this development, a ventricular septal defect will result in the corresponding area. Generally, it is a single defect, but occasionally it is seen in multiple cases. The septal defect can occur in all parts of the ventricular septum or its intersection. The three major types of septal defects commonly used in clinical practice are perimembranous defect, funicular defect and myocardial defect according to the embryonic development, among which perimembranous defect is the most common, followed by funicular defect and myocardial defect is less common.