Secondary foramen ovale type atrial septal defects generally have little effect. Secondary foramen ovale type atrial septal defect is a common type of atrial septal defect, which accounts for more than 75% of atrial septal defects. However, this is a simple defect, usually occurring at the foramen ovale or near the superior and inferior vena cava of the heart. It does not have serious consequences and can be fully recovered with prompt treatment. Secondary foramen ovale atrial septal defects are usually treated with interventional occlusion, which can be performed in young children around the age of 3 years. It should be noted that some secondary foramen ovale atrial septal defects that are smaller than 3 mm may close spontaneously by 3 months of age, and some defects that are 3 to 8 mm in size may close spontaneously by 1.5 years of age. Regular color Doppler echocardiography is recommended if secondary foramen ovale atrial septal defects are detected. If the defect does not close on its own by school age, prompt intervention is needed.