The following examinations can help in the diagnosis of this disease: 1. Chest X-ray: typical cases of tetralogy of Fallot show that the heart is not enlarged, the lung field is abnormally clear, the vascular shadow pattern is sparse, and the left edge of the heart is flat or depressed in cases with a small common pulmonary artery trunk. The aortic arch is located on the right side. 2.Electrocardiogram: It shows right ventricular hypertrophy and strain, right deviation of the electrical axis, significant increase of R wave in the right precordial leads, inversion of T wave, some patients show high pointed P wave with right atrial hypertrophy in leads I and II, the left anterior thoracic leads do not show Q wave and low R wave voltage. 3. Right heart catheterization: Right heart catheterization shows increased pressure in the right ventricle, which can reach the pressure level of the left ventricle. The heart catheter can enter the aorta directly from the right ventricle, indicating the presence of ventricular septal defect and aortic span, and the systolic pressure step difference between the right ventricle and the pulmonary artery due to right ventricular outflow tract and/or pulmonary artery stenosis. Injecting the indicator into the right ventricle and pulmonary artery via the right heart catheter, the indicator dilution curve was recorded in the peripheral artery, which showed the early appearance of the right ventricle injected indicator and a bimodal right-to-left shunt curve in the descending branch of the curve, while the normal curve was recorded in the pulmonary artery injected with the indicator. 5.Selective right ventriculography: Selective right ventriculography is necessary before deciding on surgical treatment in cases of tetralogy of Fallot. A cardiac catheter is placed in the right ventricular cavity to inject contrast, and serial radiographs can show the simultaneous visualization of the pulmonary artery and the aorta and the degree of aortic span. It also shows the location and degree of pulmonary artery stenosis, understands the development of the pulmonary artery and measures the diameter of the common pulmonary artery trunk and ascending aorta, and calculates the ratio between them. 6.Retrograde aortography: It can show the development of arteriovenous ductus arteriosus, bronchial artery collateral circulation and aortic valve opening and closing function. McGoon measures the diameters of the left and right pulmonary arteries and the descending aorta in the diaphragm plane. 7, blood tests: red blood cell count, hemoglobin and red blood cell pressure are significantly elevated, in severe cyanosis cases the red blood cell count can reach 10 million, hemoglobin 258%, red blood cell pressure is generally 50-70%, but can also be as high as 90%. Diagnosis Physical growth and development is slow. Cyanosis is evident on the face, lips, tongue, and eyelid conjunctiva. Pestle finger is common in children. The turbinate zone is not enlarged and the left anterior chest may be elevated. A jet systolic murmur from right ventricular outflow tract stenosis can be heard between the 2nd and 3rd ribs at the left sternal border and may be accompanied by tremor. In severe stenosis, the murmur is less loud and shorter when the right ventricular blood flow to the aorta is increased and the pulmonary artery blood flow is reduced accordingly. In cases of pulmonary atresia, the systolic murmur may disappear and be replaced by a continuous murmur from the collateral circulation or ductus arteriosus. The second heart sound in the pulmonary valve region is diminished or normal, and may sometimes be a single loud heart sound from the second heart sound of the aortic valve.