The left heart system of the normal human heart forms a closed loop in series with the right heart system. Blood flows sequentially through our body through the right heart, pulmonary artery, left heart, and aorta. Patients with complete transposition of the aorta have a malformation of heart development during fetal life, which causes the right heart to connect to the aorta and the left heart to connect to the pulmonary artery, forming two relatively independent parallel loops, with high oxygen saturation of blood in the lungs and low oxygen saturation of blood in the arteries, and the oxygen carried by the blood from the lungs does not reach the body circulation, so the affected child also shows bruising of the lips of the mouth and the end of the extremities. If there is no traffic between the pulmonary circulation and the body circulation, the child will not survive, so all the children seen have traffic at the atrial, ventricular or arterial level. Patients with transposition of the great arteries have cyanosis. If there is little blood exchange between the two major circulations, the cyanosis is severe, and if there is much blood exchange, the cyanosis is relatively mild, but the patient has symptoms of cardiac insufficiency, such as feeding difficulties, shortness of breath, excessive sweating, and poor growth. Children with combined ductus arteriosus can have higher oxygen saturation in the lower extremities than in the upper extremities due to the shunt from the pulmonary artery to the aorta, and the upper extremities may be a bit more purple in terms of color. Patients suspected of transposition of the great arteries should go to the hospital for ultrasound, chest X-ray and electrocardiogram, etc. Generally, ultrasound can clarify the diagnosis. Sometimes further imaging and catheterization are needed to understand pulmonary artery pressure, left heart size, and other conditions. If the two major circulations rely on the arterial catheter for traffic, avoid oxygenation to prevent premature self-closing of the arterial catheter, and go to a major medical center for emergency surgery if the traffic between the two major circulations is minimal. Complete transposition of the great arteries, if not intervened, leads to death within an average of 3 to 19 months after birth, and only a few survive until 20 to 30 years of age. There is no effective treatment other than surgery, and the procedures include arterial transposition, internal tunnel + external conduit, etc.