Atrial septal defect (ASD) is an abnormal occurrence, resorption, and fusion of the atrial septum during embryonic development, resulting in a residual unclosed defect between the left and right atria. It accounts for about 10% of all congenital heart diseases and 20%-30% of adult congenital heart diseases, and is more common in women, with a male to female incidence ratio of 1:1.5-3. ASD can be divided into secondary and primary foramen type according to the embryological pathogenesis and anatomical characteristics of ASD, the former commonly accounts for 80%-90% of ASD and is the main type of choice for interventional treatment; the latter accounts for The latter accounts for 10% to 20% of ASDs. The defect is located in the lower part of the atrial septum, caused by the dysplasia of the primary atrial septum or the abnormal development of the endocardial cushion, and its upper edge is the curved edge formed by the primary atrial septum and the lower edge is the common annulus of the mitral and tricuspid valves, which requires surgical correction. Wang Liming, Department of Cardiac Surgery, Qinghai Provincial Specialist Hospital for Cardiovascular Diseases The overall natural closure rate of secondary foramen ovale ASD is up to 87%. ASDs of less than 3 mm before 3 months of age can be 100% spontaneously closed within 1.5 years of age, and defects between 3 and 8 mm can be spontaneously closed in more than 80% of cases within 1.5 years of age, but defects above 8 mm rarely close spontaneously. the age of spontaneous healing of ASDs ranges from 7 months to 6 years of age, with a median of 1.6 years. The rate of spontaneous healing is 9.5% for those with enlarged right ventricles and 63.6% for those with normal right ventricles. Most children with ASD are generally asymptomatic and do not affect their activities, and most patients do not develop symptoms until after puberty. Congestive heart failure and pulmonary hypertension will occur in large and medium-sized ASDs around the age of 20 to 30 years, especially after the age of 35 years, and without intervention, patients will experience increased right ventricular volume and pressure load due to pulmonary hypertension, which will lead to right heart failure. Moreover, atrial arrhythmias (atrial flutter or atrial fibrillation) can develop after surgery with or without surgical intervention, and some patients can suffer from cerebrovascular embolism due to paradoxical thrombosis. For the prognosis of surgical intervention, Murphy reported that patients without preoperative pulmonary hypertension, heart failure, and atrial fibrillation who underwent closure surgery early had the same survival rate as normal, and follow-up revealed that those who underwent surgery before the age of 24 had the same long-term survival rate as normal controls of the same age and gender, whereas those who underwent surgery after the age of 40 had only 40% survival and a significantly higher incidence of atrial fibrillation. Therefore, in adult patients with ASD, early closure of the defect is indicated whenever there is evidence of right ventricular volume loading on ultrasonography. In addition, although it is traditionally believed that small ASDs smaller than 10 mm without cardiac enlargement and symptoms can be treated without surgery, considering that small ASDs may be complicated by paradoxical thrombosis and brain abscess, and that these two complications occur in adults, especially after 60 years of age, interventional treatment is also recommended for small ASDs in adults. I. Indications and contraindications for interventional treatment (a) Indications 1. usually aged ≥5 years. 2. Secondary foramen ovale ASD ≥5 mm in diameter, with increased right heart volume load, and left-to-right shunt ASD ≤35 mm. 3. The distance from the edge of the defect to the coronary sinus, superior and inferior vena cava and pulmonary veins ≥5 mm; to the atrioventricular valve ≥7 mm. 4. The diameter of the atrial septum >the diameter of the left atrial side of the selected blocking parachute. 5. No other cardiac anomalies that require surgery are combined. With the improvement of ASD interventional techniques and experience, domestic experts have proposed relative indications: 1. age <2 years, but with right ventricular load; 2. lack of or insufficient stump at the anterior edge of the ASD, but otherwise good margins; 3. partial stump less than 5 mm around the defect; 4. special types of ASD such as multiforaminal or sieve-porous ASD; 5. pulmonary hypertension, but QP/QS ≥1.5, and arterial oxygen saturation ≥92%. The arterial oxygen saturation ≥ 92% can be blocked on a trial basis. (B) Contraindications: 1. Primary orifice ASD and venous sinus ASD. 2. Endocarditis and bleeding disorders. 3. Thrombosis at the placement of the blocker or venous thrombosis at the catheter insertion site. 4. Severe pulmonary hypertension resulting in right-to-left shunt. 5. Severe myocardial disease or valvular disease unrelated to ASD. 6. Infectious disease within the last 1 month, or uncontrolled infectious disease. 7. With bleeding disorders, untreated gastric or duodenal ulcers. 8. Left atrial or left ear thrombosis, partial or total pulmonary vein ectopic drainage, left atrial septum, left atrial or left ventricular dysplasia.