Arteriovenous ductus arteriosus is one of the common types of congenital heart disease in children, accounting for about 15% of all congenital heart disease cases. Passive opening of the ductus arteriosus during fetal life is an important channel for blood circulation. Arteriovenous ductus arteriosus is commonly seen in preterm infants and can occur in up to 80% of infants born before reaching 28 weeks of gestation, with functional closure occurring approximately 15 hours after birth and should be completely closed anatomically one year after birth. If it remains open and produces pathophysiologic changes, it is referred to as an unclosed ductus arteriosus. The main causes of the occurrence of patent ductus arteriosus can be divided into two categories: genetic and environmental. Any factor affecting the embryonic development of the heart during the fetal period may cause cardiac malformations. Genetic factors alone (e.g., genetic mutations, chromosomal aberrations) account for 8% of cases, environmental factors alone account for 2%, and genetic and environmental factors interact to cause 90% of cases. Environmental factors include cold, rubella, coxsackie virus infection during the first trimester of pregnancy, lithium intake, diabetes, alcohol abuse, maternal exposure to radiation, taking amphetamines early in pregnancy without knowing that the mother is pregnant, and the use of certain birth control medications such as progesterone for preterm abortions early in pregnancy. There are many intracardiac malformations with left-to-right shunts in which the same continuous machine-like murmur or near-continuous biphasic heart murmur can be heard at the left border of the sternum and is difficult to recognize. Before establishing the diagnosis of patent ductus arteriosus for treatment, it must be differentiated, and the major malformations are discussed below in order of onset. 1, high ventricular septal defect combined with aortic valve prolapse When the high ventricular septal defect is large, it is often accompanied by aortic valve prolapse malformation, resulting in incomplete aortic valve closure and causing the corresponding signs. A double phase murmur is heard clinically at the left sternal border, which is splash-like in diastole and does not conduct upward, but sometimes resembles a continuous murmur and is difficult to distinguish. Color echocardiography is now routinely performed in cardiac disease. In this disease, aortic valve prolapse and regurgitation of aortic flow into the left ventricle, as well as shunting from the left ventricle to the right ventricle and pulmonary artery through a ventricular septal defect may be demonstrated. To further clarify the diagnosis, retrograde ascending aorta and left ventriculography can be performed, with the former showing regurgitation of ascending aortic contrast into the left ventricle and the latter showing shunting of left ventricular contrast through the septal defect into the right ventricle and pulmonary artery. It is not difficult to make the differential diagnosis accordingly. 2.Ruptured aortic sinus aneurysm This disease is not rare in China. The clinical manifestations are similar to those of patent ductus arteriosus, and a continuous heart murmur of the same nature can be heard, but the location and direction of conduction are slightly different. Aortic sinus malformation and its shunting into the ventricular and pulmonary arteries or atrial cavity can be identified if color Doppler echocardiography reveals it. The diagnosis can be established with the addition of retrograde ascending aortogram. This coronary artery malformation is uncommon and can be heard as a continuous murmur with fibrillation as in ductus arteriosus, but at a lower and more medial location. Doppler ultrasound can show where the arteriovenous fistula is located and the atrioventricular cavity it communicates with. Retrograde ascending aortography is more likely to show the enlarged main branch of the diseased coronary artery, or the course of the branch and the fistula. 4. Aortopulmonary septal defect is very rare. It often coexists with ductus arteriosus and has the same continuous murmur and peripheral vascular features, but the murmur site is low and medial. A careful echocardiographic examination will reveal a shunt at the root of the ascending aorta. Retrograde ascending aortogram is more likely to confirm this. 5. Ectopic coronary artery opening The right coronary artery originates from the pulmonary artery is a relatively rare congenital heart disease. The heart murmur is also continuous, but lighter and more superficial. Doppler ultrasonography is useful for differential diagnosis. Retrograde ascending aorta angiography on serial radiographs showing abnormal opening and course of the coronary artery and tortuous collateral circulation may clarify the diagnosis.