An atrial septal defect is an abnormal traffic between the right and left ventricles, which normally do not communicate with each other. In atrial septal defect (ASD), the left-to-right shunt flow is mainly determined by the size of the defect and the compliance of the right and left ventricles. Since the right ventricle is more compliant than the left, a left-to-right shunt exists. The degree of cardiac enlargement reflects the degree of shunting, and at the atrial level there is a left-to-right shunt, with increased blood flow to the right atrium, right ventricle, and right main pulmonary artery and its branches, so they all enlarge. These can be reflected on X-ray chest radiographs, which show enlargement of the right atrium, right ventricle, and right main pulmonary artery, as well as increased pulmonary blood flow. Note that the left atrium is not large because the increased pulmonary venous blood does not remain in the left atrium but is shunted back into the right atrium. The small size of the left atrium facilitates the differentiation of atrial septal defects from ventricular septal defects. The dilated right ventricle prolongs the depolarization time of the right ventricle because the conduction bundle is prolonged by the enlargement of the ventricle, resulting in right bundle branch block (RBBB), which has an rsR pattern in V1 on the ECG, but RBBB is not really a block of the conduction bundle. If the duration of the QRS wave is not prolonged, the ASD appears as mild right ventricular hypertrophy (RVH) on the electrocardiogram. Therefore, RBBB and mild RVH are common electrocardiographic manifestations in children with ASD. The heart murmur in ASD is not due to an interventricular shunt. The cardiac murmur in ASD originates from the pulmonary valve, which is systolic due to increased RV volume, resulting in a relative narrowing of the pulmonary valve. The diastolic murmur in the tricuspid region is formed due to increased blood flow through the tricuspid valve thereby producing a relative stenosis of the tricuspid valve. The fixed splitting of the second heart sound, a typical sign of ASD, is partly due to RBBB. In addition, the relatively large interatrial shunt causes the blood flow from the body circulation back to the right atrium to fluctuate and disappear due to the effects of respiration, which results in a higher venous return to the right atrium throughout the respiratory cycle and thus a fixed splitting of the second heart sound. Patients with ASD rarely develop congestive heart failure (CHF) in childhood, and pulmonary artery pressure remains normal for a long time even when a relatively large shunt is present. And no pulmonary hypertension develops because the pulmonary arteries can better tolerate the increased pulmonary blood flow because there is no direct transmission of pressure from the body circulation to the pulmonary circulation. However, CHF and pulmonary hypertension eventually appear around the age of 30 to 40 years. So, what is the natural course of atrial septal defect? That means what happens if it is not treated? 1. The overall natural closure rate of atrial septal secondary foramen ovale defects is 87%. Atrial septal defects with a defect of 3 mm diagnosed before 3 months of age can be 100% spontaneously closed within 1.5 years of age; atrial septal defects with a defect of 3-8 mm can be spontaneously closed in more than 80% of cases within 1.5 years of age; those with a defect of 8 mm or more rarely close spontaneously. Most children with atrial septal defects are generally asymptomatic and do not affect their activities; heart failure can occur in infants, but it is very rare. If left untreated, congestive heart failure and pulmonary hypertension will occur in adults around the age of 20 or 30. 4. Atrial arrhythmias (atrial flutter or atrial fibrillation) can develop in adulthood with or without surgical treatment. 5, Simple atrial septal defects do not present with infective endocarditis, so if there are no other combined malformations, prophylactic treatment is not necessary. 6, cerebrovascular accidents, cerebrovascular embolism due to paradoxical thrombosis caused by atrial septal defect into is a relatively rare complication. So, how should children with atrial septal defect be treated at home? For atrial septal defect less than 8mm, treatment is not necessary before the age of 2 years, waiting for its natural healing, and treatment can be considered if it still cannot heal after the age of 2 years. For atrial septal defect larger than 8mm, if there is no symptom, it can also wait until about 2 years old for treatment, but if the symptom is obvious, frequent pneumonia, and affect the development, it should be treated as early as possible. In the past, the treatment of atrial septal defect mainly relied on surgical procedures to repair or direct suturing. Hospitals in good condition have a high success rate, with an overall mortality rate of about 2%. The cost is usually in the range of 10,000 to 30,000, with higher costs in Beijing and Shanghai. In recent years, interventional treatment of congenital heart disease has gained rapid development. Currently, many congenital heart diseases have replaced surgery as the preferred treatment option. Like pulmonary stenosis, aortic stenosis, active constriction, and patent ductus arteriosus, etc., have become the treatment options of choice. Small ventricular septal defects have also been widely performed throughout the country. And the cost has approached surgical procedures, and in some cases has been lower than surgical less surgery. Cardiac interventional therapy is a non-surgical method of treating heart disease by widening the narrowed heart channels or blocking the abnormal heart pathways with special materials. 1960s, it started to develop rapidly in recent years, making many patients free from the pain of surgery. 1.Simple method: Cardiac intervention is known as a surgery that does not require an incision, and only requires a small 2-3 mm incision at the root of the thigh that needs to be sutured, so the method is very simple. 2.Satisfactory efficacy: a variety of interventional procedures are currently carried out, and after more than 10 years of clinical observation, the surgical effect is good, and many surgical effects have been significantly better than open-heart surgery. 3.Less pain: Interventional surgery causes little damage to the patient and takes only about 1 hour if it goes smoothly. 4.Aesthetics: Since the interventional surgery does not open the chest, no scars are left after healing, and a good aesthetic effect is achieved. Which children can undergo cardiac interventions? 1.Balloon atrial septal stenosis 2.Pulmonary valve stenosis: the narrowed pulmonary artery is dilated through a balloon catheter, which is effective 3.Aortic valve stenosis 4.Aortic constriction 5.Micuspid valve stenosis 6.Aortic ductus arteriosus 7.Atrial septal defect 8.Ventricular septal defect At present, we are able to perform any of the above procedures with great success. Others like Shanghai Children’s Medical Center, Beijing Fu Wai Hospital, Guangzhou Cardiovascular Institute, etc. are doing very well and can be treated nearby.