The cause of congenital heart disease: The cause is still unclear, it is generally believed that early pregnancy (5-8 weeks) is the most important period of fetal heart development, congenital heart disease has many causes, genetic factors only account for about 8%, while the vast majority of 92% is caused by environmental factors, such as women taking drugs during pregnancy, infected with viruses, environmental pollution, radiation, etc. can make the fetal heart development abnormal. In particular, rubella virus infection in the first trimester of pregnancy can dramatically increase the risk of congenital heart disease in children. The main clinical manifestations of these diseases: There are many types of congenital heart disease, and their clinical manifestations depend mainly on the size and complexity of the malformation. Complex and severe malformations can present with serious and even life-threatening symptoms soon after birth. It should be noted that some simple malformations such as ventricular septal defect and patent ductus arteriosus can have no obvious symptoms in the early stage, but the disease can still potentially develop and worsen, requiring timely diagnosis and treatment to avoid losing the opportunity for surgery. The main symptoms are: 1. frequent colds, recurrent respiratory infections, and susceptibility to pneumonia. 2. Poor growth and development, wasting, and excessive sweating. 3.Impotent sucking during breastfeeding, difficulty in feeding, or infant refuses to eat, choking and coughing, and usually shortness of breath. 4.Children complain of easy fatigue and poor physical strength. 5.Blue lips and nails or bruising after crying or activity, pestle-shaped fingers and toes (nail bed bulging like a hammer). 6.Like squatting, fainting, hemoptysis. 7. Auscultation reveals a heart murmur. The main diagnostic methods of such diseases: The diagnosis can be made generally by symptoms, signs, ECG, X-ray and echocardiography, and the hemodynamic changes, degree and extent of lesions can be estimated to determine the treatment plan. For congenital heart disease with multiple malformations and complex and difficult cases, the specialist will selectively take 3D CT examination, cardiac catheterization or cardiovascular angiography according to the situation to understand the degree, type and scope of lesions, make a clear diagnosis by comprehensive analysis, and guide the formulation of treatment plans. However, echocardiography is a non-invasive examination method that uses ultrasonic echo to investigate the heart and large blood vessels to obtain relevant information, including M-mode ultrasound, two-dimensional ultrasound, pulsed Doppler, continuous Doppler, and color Doppler flow imaging.