Congenital heart disease (congenital heart disease) can be divided into two categories: cyanotic congenital heart disease and non-cyanotic congenital heart disease. The heart is located on the left side of the chest cavity. To use an analogy, the heart is like 4 rooms up and down, the upstairs is divided into the right atrium, the left ventricle
The right atrium and left ventricle are separated from each other by a valve. The right atrium and right ventricle receive blood from the systemic venous return, which is purple blood with low oxygen content, and purple blood
The purple blood (i.e., venous blood) flows into the lungs, expels carbon dioxide and inhales oxygen through breathing, so that the purple blood with low oxygen content is transformed into blood with high oxygen content (i.e., arterial blood), which returns to the left atrium and left ventricle through the pulmonary vein and reaches the systemic arteries by the aorta, and so on and so forth. The blood circulation maintains the life of the body. In the process of fetal growth and development, affected by external factors (mother’s virus infection, etc.) will occur some structural defects or malformations of the heart, in favor of changes in blood flow, such as atria, ventricles or large vessels with holes or small tubes between each other, arterial and venous blood will mix with each other. Under normal circumstances, the pressure of arterial blood is higher than that of venous blood, so the pressure of arterial blood to static is higher than that of venous blood, so arterial blood shunts to venous blood and does not show cyanosis for the time being, such as ventricular or atrial septal defect and unclosed arterial duct. However, when the disease develops to a certain degree and the venous pressure exceeds the arterial pressure, cyanosis will appear, so this type of precordial disease is called potential cyanosis. If the venous blood flows in the direction of arterial blood, there will be cyanosis, for example, in tetralogy of Fallot (there are four malformations: pulmonary artery stenosis, high ventricular septal defect, aortic right span and right ventricular hypertrophy), due to the narrowing of the pulmonary artery, the blood entering the lungs is reduced, so that the venous blood with low oxygen content is converted into arterial blood with high oxygen content is reduced, and because the aorta rides across the left and right ventricles, the blood from the left and right ventricles mixes and enters the cyanosis at the same time. The more blood, the more obvious the cyanosis. These are called cyanotic precordial diseases. The other type is the one in which there is no mixing of blood from both sides (such as right-sided heart, pulmonary stenosis, etc.), and this is the one without cyanosis.