During outpatient visits, parents often ask in disbelief, “Our child’s mouth is not blue, how can it be a heart attack? In other words, in people’s mind, they tend to associate cyanosis with heart disease. Indeed, heart disease can also be classified by the presence or absence of cyanotic symptoms. It is commonly divided into: non-cyanotic and cyanotic. 1, non-cyanotic congenital heart disease: such as arteriovenous catheterization, ventricular septal defect, atrial septal defect and several other, usually no cyanotic performance, so called “non-cyanotic congenital heart disease”; but in violent crying or pneumonia, heart failure and late stage of heart disease, there can be cyanosis, so also known as ” latent cyanotic congenital heart disease”. 2, cyanotic congenital heart disease: such as tetralogy of Fallot, transposition of the great arteries, pulmonary artery atresia, pulmonary vein ectopic drainage, etc.. The prominent manifestation is the early appearance of generalized cyanosis, which is obvious in the mouth, lips, fingers, toes, earlobes and oral mucosa, and cannot be improved by oxygen inhalation. If the cyanosis persists for more than 6 months, the ends of the fingers and toes may become thickened and widened (called pestle-like fingers and toes). Cyanotic congenital heart disease is easier to detect early, while non-cyanotic congenital heart disease is mostly found during visits to the doctor for repeated colds and pneumonia or during physical examinations, and some children are found to have obvious heart enlargement, severe pulmonary hypertension, and even cyanotic symptoms, which adversely affects the prognosis. Therefore, if your child has recurrent respiratory infections, poor health, slow weight gain, and excessive sweating, it is best to have them screened by your doctor’s stethoscope.