Atrial septal defect is one of the most common congenital heart diseases, which is a residual unclosed defect in the atrial septum during embryonic development. The majority of atrial septal defects are uniportal, a few are porous and sieve-shaped. At the end of the fourth week of embryonic formation, the primitive atrium begins to separate into four atrial chambers. The inner wall of the primitive atrium grows downward from above to form a septum, which becomes the first interatrial septum. At about the sixth week of embryonic formation, the first interatrial foramen is completely closed. At the same time, a perforation is absorbed above the first interventricular septum by itself, allowing the left and right atria to communicate there, and this hole is called the second interventricular foramen. After the appearance of the second interatrial foramen, a second interatrial septum appears to its right to cover the second interatrial foramen. Depending on the cause of atrial defects in embryonic development, they can be divided into primary and secondary foramen defects. (1) Primary foramen ovale defect: If the first interatrial septum completely meets the endocardial cushion during embryonic development, the residual foramen between the two is called primary foramen ovale. (2) Secondary foramen ovale: If the second interatrial foramen is too large or not covered by the second interatrial septum, it becomes a secondary foramen ovale defect. 2.Surgical indications and contraindications Children with definite diagnosis of atrial septal defect should undergo surgical repair, especially for larger defects, which should be operated actively. 1 to 5 years old is the ideal age for surgical treatment. Surgery is contraindicated in children with severe pulmonary hypertension, clinically significant cyanosis and cardiac insufficiency. The treatment of atrial septal defect currently includes two methods: ① surgical treatment: according to the surgical repair method can be divided into patch method and direct repair method, the patch can be polyester sheet or autologous pericardial sheet; ② interventional blocking treatment.