For parents, what symptoms should be observed to suspect that their child has congenital heart disease and needs further investigation? In fact, although there are many types of congenital heart disease, the most simple and easy to understand classification is according to the presence or absence of cyanosis, that is, cyanotic and non-cyanotic congenital heart disease. The most common non-cyanotic congenital heart diseases such as ventricular septal defect, atrial septal defect, and patent ductus arteriosus are most commonly associated with a heart murmur. Due to the increased pulmonary blood flow caused by intracardiac or large-vessel shunts (left-to-right shunts), children often have enlarged hearts, congested lungs, rapid or even nodding whistles, recurrent whistling infections, growth retardation and even feeding difficulties, and these children may develop whistling and circulatory failure in infancy and have to be treated early; however, for non-cyanotic congenital heart disease However, for patients with non-cyanotic precardiac disease, if the left-to-right flow is not large and there is no pulmonary hypertension, some patients can be treated without surgery in infancy, such as atrial septal defect, which is often seen clinically without serious symptoms but with a heart murmur found during the kindergarten physical examination before further examination and treatment. The most common ones are tetralogy of Fallot, where right ventricular outflow tract obstruction or pulmonary artery stenosis restricts blood flow to the lungs via the right ventricle, and there is a right-to-left shunt at the ventricular level through the septal defect, leading to a decrease in arterial oxygen saturation in the body circulation. In severe cases, early bruising of the lips and nail beds may occur, with a tendency to progressively worsen. The symptoms of hypoxia are closely related to the degree of stenosis of the right ventricular outflow tract, and in severe cases, recurrent episodes of hypoxia may necessitate early or even emergency surgery. In children with mild symptoms, the bruising will gradually worsen as they get older than half a year, and older children will also develop pestle fingers and squatting, which are typical clinical symptoms. Long-term hypoxia will also lead to the growth of body-pulmonary collateral vessels in the body, which, although helpful in relieving hypoxia, will have a greater impact on the difficulty of surgical management and recovery of cardiac function after surgery. Therefore, in general, it is a better time for children without severe hypoxia and recurrent hypoxic episodes in early life to receive surgical treatment at about half a year of age. Other cyanotic congenital heart diseases such as large artery misalignment with increased pulmonary artery pressure and complete pulmonary vein ectopic drainage; pulmonary artery stenosis with reduced pulmonary blood and pulmonary artery atresia require surgical treatment at different points in time. There are some congenital cardiac macrovascular malformations that exhibit severe symptoms of hypoxia or circulatory collapse after birth and require urgent surgical management. Examples include obstructive complete pulmonary vein ectopic drainage, aortic arch narrowing with interrupted or near-atretic aortic arch, complete septal integrity with complete aortic malposition, and pulmonary atresia with severe hypoxia. For severe cyanosis after birth, it is important to perform cardiac ultrasound diagnosis to clarify the cardiac malformation before deciding whether to administer high levels of oxygen therapy. The presence of the ductus arteriosus is a key life-sustaining factor in these children, and oxygen inhalation can promote ductus arteriosus closure, leading to more severe hypoxia and worsening systemic failure. Therefore, in children with arterial duct-dependent cyanotic congenital heart disease, not only should oxygen be administered after birth to try to improve hypoxia, but also intravenous access should be opened as soon as possible if possible, and prostaglandin E (Kaiser) should be pumped continuously to keep the arterial duct open in order to provide good conditions for subsequent management and surgery. In addition, the arterial catheter is also very important for aortic arch disruption, because the blood supply to the lower body is perfused through the right ventricle and pulmonary artery via the arterial catheter to the descending aorta, and these children clinically present with what is called differential cyanosis, i.e., lower body oxygen saturation is reduced and upper body oxygen saturation is normal. Thus, interruption of the aortic arch is also an arterial catheter-dependent congenital heart disease, which also requires prohibition of oxygen and kaiser-venous maintenance, and often requires early treatment with emergency surgery. Because of the complexity of congenital heart disease, some complex malformations are more difficult to deal with, so early and clear diagnosis and timely intervention by a specialist is the best solution. One should never let down one’s guard or treat blindly, which can even bring irreversible consequences if not treated properly.