The ductus arteriosus was originally a normal blood flow channel between the pulmonary artery and the aorta during fetal life. Due to pulmonary respiratory dysfunction at this time, pulmonary blood from the right ventricle enters the descending aorta via the ductus, while blood from the left ventricle enters the ascending aorta. After birth, the lungs expand and assume the function of gas exchange, and the pulmonary circulation and the body circulation each perform their own functions, and soon the ducts close by choice due to disuse. If the ductus arteriosus persists and does not close, the ductus arteriosus becomes unclosed. Surgery should be performed to interrupt the blood flow. The arteriovenous ductus arteriosus is a relatively common congenital cardiovascular malformation, accounting for 12% to 15% of all congenital heart disease, and is about twice as common in women as in men. In about 10% of cases, other cardiovascular malformations coexist. I. Etiology and pathogenesis Genetics is the main internal cause. Any factors affecting the embryonic development of the heart during the fetal period may cause cardiac malformation, such as rubella, influenza, mumps, coxsackievirus infection, diabetes mellitus, hypercalcemia, etc., exposure of the mother to radiation, and the mother taking anti-cancer drugs or drugs such as methylglyoxal. II. Pathology The arterial duct connecting the common pulmonary artery trunk to the descending aorta is the main channel of blood circulation in the fetal period. It is usually occluded within a few months after birth due to disuse, and if it is not occluded after 1 year of age, it is considered an unclosed ductus arteriosus. The length, diameter, and morphology of the unoccluded ductus arteriosus vary, with different hemodynamic effects and different prognoses. Pathophysiology Because the aortic pressure is always significantly higher than the pulmonary artery pressure throughout the cardiac cycle, there is a continuous flow of blood from the aorta into the pulmonary artery through the unclosed ductus arteriosus, i.e., left-to-right shunt, which increases the blood flow in the pulmonary circulation and dilates the pulmonary artery and its branches. As the diastolic aortic blood shunts to the pulmonary artery, the diastolic pressure of the peripheral artery decreases and the pulse pressure increases. The clinical manifestations of arterial ductus arteriosus depend on the amount of blood flow from the aorta to the pulmonary artery and whether it produces secondary pulmonary hypertension and its degree. In mild cases, there may be no obvious symptoms, while in severe cases, heart failure may occur. Common symptoms include palpitations after exertion, shortness of breath, weakness, susceptibility to respiratory tract infections and growth retardation. In advanced pulmonary hypertension, cyanosis of the lower half of the body may occur when a reverse shunt is produced. On physical examination of arteriovenous ductus arteriosus, the typical sign is a loud continuous machine-like murmur with tremor heard between the 2nd ribs at the left border of the sternum. The 2nd pulmonary artery sound is hyperactive, but often masked by the loud murmur. In large fractional flows, a diastolic murmur due to relative mitral stenosis can be heard in the apical region. Blood pressure measurements show that systolic pressure is mostly in the normal range, while diastolic pressure decreases, resulting in a widened pulse pressure and a watery pulse and gunshot sound in the vessels of the extremities. In adults with unclosed ductus arteriosus, there are several clinical manifestations depending on the size of the fractional flow: 1, the fractional flow is very small, i.e., the internal diameter of the unclosed ductus arteriosus is small. 2, medium fractional flow patients often have weakness, palpitations after exertion, shortness of breath, chest tightness and other symptoms, heart auscultation murmur nature as above, louder with tremor, wide range of conduction; sometimes can be heard in the apical region due to left ventricular enlargement mitral valve relative closure insufficiency and (or) stenosis caused by mild systolic and (or) diastolic murmur, positive peripheral vascular signs. 3. Unclosed arterial ducts with high shunt flow, often secondary to severe pulmonary hypertension, may result in a right-to-left shunt. The diastolic component of the above typical murmur is reduced or disappears, followed by the disappearance of the systolic murmur and only the diastolic murmur due to incomplete pulmonary valve closure can be heard, and the patient is mostly cyanotic and has severe clinical symptoms. In infants and children, only systolic murmurs can be heard. In late pulmonary hypertension, the murmur may be more variable and may be replaced by a systolic murmur or by a diastolic murmur due to pulmonary valve insufficiency.