The basic principle of interventional treatment for atrial septal defect is to deliver a double-disc structured occluder through the catheter at the site of atrial septal defect, one of the two discs is in the left atrium and the other in the right atrium, and the two discs are connected by a waist, which is just through the atrial septal gap. Animal experimental studies have confirmed that platelets and fibrin start to accumulate in the occluder 1 day after the septal defect closure surgery, and the entire occluder can be filled in 3-10 days, and the deposition of collagen tissue can be seen; after 7-10 days, endothelial cells start to cover the surface of the occluder and form granulation tissue, which gradually covers the occluder. After 3 months, the endothelial cells and granulation tissue completely encapsulate the occluder, and the platelets and fibrin within it gradually mechanize and finally form a dense tissue structure, which anatomically closes the septal defect. Two factors determine the efficacy of the plugging device: whether the plugging device can rapidly form thrombus inside the plugging device after implantation into the atrial septal defect site, but not on the surface of the plugging device; whether the plugging device can rapidly endothelialize and form a layer similar to the endothelium of the heart on the surface of the plugging device. II. Indications 1. Age greater than 3 years, less than 60 years, weight greater than 5 kg; 2. Secondary foramen ovale septal defect.