Patent ductus arteriosus (PDA) is one of the most common types of congenital heart disease in children, accounting for 15% of all cases, excluding immature children. It is more common in females, with a male to female sex ratio of 1:3. About 1 case of patent ductus arteriosus can occur in every 2500-5000 surviving newborns. Clinical manifestations] 1. Symptoms: The arterial catheter can be asymptomatic clinically. The thick catheter is often accompanied by tachycardia and weight loss, which can lead to lower respiratory tract infection, pulmonary atelectasis and heart failure. Physical examination: A continuous “machine-like” murmur can be heard above the left edge of the sternum, accounting for the entire systolic and diastolic periods, and is loudest at the end of systole, and is transmitted to the left subclavian, neck and back. A short diastolic murmur may be heard in the apical region in those with high unclosed ductus arteriosus fractions due to relative mitral stenosis. The second sound in the pulmonary valve area is enhanced. In infancy, because of the high pulmonary artery pressure, the pressure difference between the main and pulmonary arteries is not significant in diastole, and thus only a systolic murmur is often heard. As the diastolic pressure decreases, the pulse pressure difference widens, and peripheral vascular signs may appear, such as water-rush pulse and capillary pulsation in the nail bed. 1. ECG: Small to medium-sized arterial catheters have normal ECG or left ventricular hypertrophy; large arterial catheters show enlargement of both left and right ventricles; those with obstructive pulmonary hypertension show right ventricular hypertrophy. 2, X-ray examination: the arterial catheter fine X-ray performance is normal. In those with high flow, the heart shadow is enlarged to varying degrees, with enlargement of the left atrium and left ventricle and dilatation of the ascending aorta. Pulmonary blood increases, the pulmonary artery segment is prominent, and the hilar vascular shadow is thickened. In patients with obstructive pulmonary hypertension, the heart shadow is normal, and the hilar vessels and the common pulmonary artery trunk are significantly thickened. 3.Echocardiography: Two-dimensional echocardiography can directly detect the majority of unclosed ductus arteriosus. Pulsed Doppler can also detect a typical systolic and diastolic continuous turbulent flow spectrum at the opening of the ductus arteriosus. Color Doppler flow imaging reveals red or multicolored flow from the descending aorta and through the duct into the pulmonary artery; in severe pulmonary hypertension, blue flow is seen from the pulmonary artery through the duct into the descending aorta when pulmonary artery pressure exceeds that of the aorta.