Atrial septal defect is one of the most common congenital heart diseases and can be referred to as a “hole” in the heart along with ventricular septal defect. There is a consensus that the larger holes in the heart are treated promptly, but with improved medical care, many very small holes are being discovered by physicians. Unlike ventricular septal defects, which are usually associated with a heart murmur, small atrial septal defects are often detected by ultrasound examination of the heart and are not usually detectable by physician auscultation, even if there are recurrent lung infections or other discomfort that cannot be explained by the hole. However, once detected, it always brings a great deal of psychological baggage, and even unnecessary panic, to the parents or patient. At this point its faced with two choices, one to treat, two not to treat. The former is commonly known as a needle in the thigh can be treated, will not leave a body scar, the latter will only leave a small surgical scar in the chest. Because these two methods are not very traumatic, the risk of surgery is really small, so many parents do not even understand why surgery is necessary, just take it for granted that a hole in the heart is a big deal and must be treated. Why does a disease need to be treated? This sounds like a very unanswerable question. Of course a disease needs to be treated! But in reality, it is not that simple. The goal of treatment is to live a long, good life. And does a small atrial septal defect shorten life expectancy? There is no very clear answer to this question. An atrial septal defect is a hole that exists between the left and right atria of the heart, and because the pressure in the left atrium is greater than in the right atrium, this hole causes some of the blood from the left atrium to flow through it into the right atrium, and it is usually thought that this abnormal flow is too great to cause adverse consequences. These consequences include: 1. The right side of the heart is overloaded, leading to enlargement of the right ventricle and right atrium, resulting in right-sided heart failure and tricuspid regurgitation. 2, right atrial enlargement can also lead to atrial arrhythmias. 3, Excessive pulmonary artery blood flow, repeated pulmonary infections, and long-term effects lead to pulmonary hypertension. 4.Infective endocarditis. 5, paradoxical embolism. Generally the first three are predominant, and all are the result of slow, long-term effects, so you can feel free to give yourself a few days to sort out your thoughts, the latter two are rare. There is also thought to be a possible association with migraine and decompression sickness. But these findings may have been studied in larger cases of atrial septal defects, in the days before cardiac ultrasound, when larger septal defects led to clinical manifestations such as recurrent lung infections, heart failure, arrhythmias, etc., which were later detected by listening to heart murmurs and performing cardiac catheterization. So it is questionable whether the conclusions drawn from these data can be extended to small atrial septal defects. However, clinical observations over the years have shown that small atrial septal defects, in general, do not lead to adverse outcomes. When it comes to this point it is important to clarify what kind of atrial septal defect is considered small. It is generally considered to be less than 5 mm (another term that may be encountered is for an unclosed foramen ovale, which can be equated to a relatively small atrial septal defect in the vast majority of cases), no enlargement of the right ventricle or right atrium by cardiac ultrasound, or within 1.5 times of the blood flow in the pulmonary circulation by cardiac catheterization, although, of course, only cardiac ultrasound is usually sufficient and cardiac catheterization is not necessary. The above criteria are not absolute and have to be analyzed individually according to the case. My practical recommendation is: In young children 0-2/3 years old, the vast majority can be observed unless the hole is very large and has led to obvious adverse consequences that require prompt treatment. Here, a special reminder that the fetus is supposed to have a small hole at the septal compartment in the mother, the foramen ovale, and that some of the small defects have the possibility to heal on their own, with a regular review of the cardiac ultrasound, and maybe the next time is a perfect answer. In cases where the defect is really large and has no possibility of healing on its own, early surgery is also a good option. Above 3 years of age, percutaneous or small incisional closure can be considered first for slightly larger defects, and then open-heart surgery can be considered if there are conditions that are not suitable for closure. Combined with severe pulmonary hypertension or having developed a right-to-left shunt, i.e., Eisenmenger syndrome, a comprehensive evaluation is recommended, and it is worse if the opportunity for surgery has been lost.