The incidence of PDA is about 10-15% of congenital heart disease, and it is the third most common congenital heart disease, with a male to female ratio of 1:3. The clinical symptoms depend on the size of the shunt flow, which is often asymptomatic when the shunt flow is small and palpitations when the shunt flow is large. The clinical symptoms depend on the size of the fractional flow and are often asymptomatic. In 1971, Porstmann reported for the first time the success of the interventional method to seal the unclosed ductus arteriosus, which was introduced to China in the mid-1980s and carried out in Hangzhou, Shanghai. The Raskind method was introduced into China in the early 1990s, and was performed in Beijing, Guangzhou, and Shanghai for the treatment of arterial catheters less than 4 mm in diameter. In 1977, the Amplatzer blocking umbrella was introduced into China, and with the localization of the Amplatzer blocking umbrella, interventional treatment of unclosed arterial ducts was really widely used in clinical practice and became the treatment of choice for PDA. At present, the clinical application of PDA interventional treatment is commonly used for Amplatzer method and controlled spring coil method, among which Amplatzer method is more commonly used. The anatomical typing of PDA is the result of the continuous opening of the 6th arterial arch during embryonic development, often located between the aortic isthmus and the main pulmonary artery or the root of the left pulmonary artery, left PDA, right PDA and bilateral PDA are less common. type B (short PDA with narrowest point at the aortic end), type C (tubular with no stenosis), type D (multiple stenoses), and type E (oddly shaped with elongated funnel-like structures and narrowest point away from the anterior bronchial margin). We analyzed the morphology of PDA in 483 cases of aortic arch angiography at Fu Wai Hospital according to the characteristics of PDA interventions and proposed a new typology: 1. funnel type, all of which have funnel-shaped structures with the anterior part gradually thinning and connected to the pulmonary artery, and this type is the most common (87%). 2. window type, which is the least common and often has a larger diameter (0.6). 3. tube type, which is more common (7). 4. bead type, which has two stenoses. The aortic duct is connected to the pulmonary artery by a thin tubular structure of uniform thickness, but its pulmonary end suddenly becomes thin and finger-like (2.1). 6. Irregular type, the aortic arch is connected to the pulmonary artery by an irregular structure, which is difficult to be classified into any of the above categories (1.0). III. Indications and contraindications 1. Indications For the Amplatzer method: 1) left-to-right shunt simple PDA malformation, PDA narrowest diameter R2.0 mm; age usually > 6 months, weight ≥ 4Kg; 2) surgical or post-interventional residual shunt. 3) PDA combined with pulmonary hypertension, still left-to-right shunt, for interventional indications; 4) PDA combined with (4) PDA combined with pulmonary hypertension, where left-to-right shunt is predominant and a small amount of right-to-left shunt exists, is feasible for trial blocking treatment. For controlled spring-ring method: 1) rightward shunt simple PDA 2) PDA narrowest diameter Q2.0 mm; 3) age usually greater than 6 months; 3) surgical or interventional residual shunt. 2. Contraindications 1) Contrast allergy or blocking material allergy; 2) PDA-dependent cardiac malformation for survival; 3) PDA combined with severe pulmonary hypertension, right-to-left shunt predominant; 4) PDA complicated by severe infection, especially endarteritis within one month. IV. Operation steps 1. Amplatzer method: Select a blocker 2~4mm larger than the narrowest diameter of the measured PDA, connect it to the tip of the delivery guidewire by rotation, and recover it into the loader for backup. The end-hole catheter is delivered via the femoral vein into the pulmonary artery and through the PDA into the descending aorta. A 260 cm stiffened guidewire is fed into the descending aorta via the end-hole catheter, and the catheter is withdrawn and fed into the delivery sheath along the guidewire. The delivery sheath is fed through the delivery sheath into the descending aorta. The delivery sheath is fixed and the delivery guidewire is slowly retracted until the distal disc of the blocker is fully opened, then the delivery sheath and the delivery guidewire are retracted together to bring the distal disc of the blocker to the aortic side of the PDA. Fix the delivery guidewire and retract the delivery sheath to the pulmonary artery side so that the waist of the blocker is completely stuck in the PDA, and repeat the descending aortogram after 10-15 minutes. Withdraw the sheath and compress to stop the bleeding. 2.Spring embolus method: (1) Trans-femoral vein cis-access method: The end-hole catheter is sent into the pulmonary artery via the femoral vein and into the descending aorta via the PDA. Send 260cm stiffened guidewire into the descending aorta via the end-hole catheter, send a delivery sheath tube along the guidewire, send a spring coil to the descending aorta via the delivery sheath tube, place 3~4 turns of the spring coil on the side of the aorta and 1 turn on the side of the pulmonary artery, repeat the descending aorta imaging after 10~15 minutes, if the spring coil is in the right position, the shape is satisfactory, and there is no residual shunt can manipulate the rotating handle to release the spring coil. The catheter is withdrawn and compression is applied to stop the bleeding. (2) Retrograde method via the femoral artery: Feed the end-hole catheter through the femoral artery into the pulmonary artery via the PDA, and feed the spring coil through the delivery sheath to the pulmonary artery, place one coil on the pulmonary side of the PDA and the remaining coils on the aortic side of the PDA, and repeat the descending aortogram after 10-15 minutes. Withdraw the catheter and compress to stop the bleeding. V. Complications and treatment 1. Blocker dislodgement embolism often dislodges to the pulmonary artery, abdominal aorta and its branches. Once it happens, first try the mesh basket catheter to sleeve it out of the body, if it is unsuccessful, then perform surgery to remove it. Strictly standardized operation and selection of suitable blocking device can generally be avoided. 2.Hemolysis Hemolysis occurs on the basis of residual shunt. If the condition is not serious, it can be treated conservatively by appropriately lowering the pressure, alkalizing the urine, giving hormones and antibiotics, etc. If it is not effective, the blocker can be removed surgically and then PDA suture can be performed. 3. Aortic or left pulmonary artery stenosis is related to factors such as oversized blocker type and improper placement. In case of moderate to severe stenosis (differential pressure of 20 mmHg or more, blocking 1/2 of the vessel lumen), surgery should be performed as soon as possible. 4. Transient hypertension If blood pressure is too high, appropriate antihypertensive treatment can be given, and normalization is usually achieved within a short period of time. 5.Other complications of catheterization. At present, the technology of interventional treatment of patent ductus arteriosus has been quite mature, and it is the technology with the most accurate success rate and efficacy in the interventional treatment of precordial disease, and at present, the number of treated cases is more than 2000 per year, which is well received by doctors and patients. However, there are some problems that should be noted in PDA interventional treatment, which are discussed below with my clinical experience. 1, PDA combined with severe pulmonary hypertension interventional treatment of PDA caused by pulmonary hypertension with increased pulmonary blood flow, aortic pressure conduction, pulmonary vasospasm and secondary lesions of the pulmonary arteries. The key to treatment is to determine whether pulmonary hypertension is a reversible change. Pathologic grading of pulmonary artery lesions is available both nationally and internationally to help determine whether the lesions are reversible, but is determined by surgery or lung tissue biopsy. Eisenmenger’s syndrome is a clear contraindication. Domestic and international literature reports that patients with PDA combined with severe pulmonary hypertension who have X-ray chest radiographs showing little pulmonary blood, little or reduced heart size, and no obvious cyanosis on QP/QS90 should try to block and manage as appropriate, because the Amplatzer blocking umbrella has retrievability and can be tried to monitor changes in pulmonary artery pressure, aortic pressure, oxygen saturation and the patient’s own feelings after blocking, which has obvious superiority over surgical procedures It is significantly superior to surgical procedures. If the pulmonary artery pressure decreases satisfactorily (by 20 or more than 30 mmHg of the original pressure), the patient has no systemic reaction, no main pulmonary artery stenosis, and the residual shunt disappears or there is only a small amount of residual shunt, the blocker can be released; if the pulmonary artery pressure increases instead, or the patient has obvious discomfort and the arterial pressure decreases, the blocker should be retrieved. If there is no significant change in pulmonary artery pressure, the patient has no systemic reaction, blood pressure ¸ oxygen saturation does not decrease, the release of the blocker should be cautious. In this case, it is impossible to determine whether the pulmonary vascular lesion is reversible, and it is difficult to predict the prognosis, so the patient and relatives should be informed of the condition and consent should be obtained before releasing the blocking umbrella, and the intervention in this part of the patients should be especially cautious. At present, long-term postoperative follow-up should be performed for category 3 cases to obtain important information for prognosis. 2.Interventional treatment of infants and young children with unclosed arterial duct has its special characteristics. The narrowest diameter of the arterial duct is mostly widened after implantation of the umbrella, probably due to the expansion of the blocker itself and the elasticity of the pediatric arterial duct. If the pressure difference is greater than 10 mmHg, the possibility of stenosis should be considered and the blocking umbrella should be withdrawn and a suitable blocker should be reimplanted. 2) Avoid excessive pulling of the blocking umbrella. In infants under 1 year of age, attention should be paid to the relationship between the length of the unclosed catheter and the blocking umbrella and the operating technique to avoid excessive pulling of the umbrella toward the pulmonary artery end when implanting the umbrella resulting in medically induced left pulmonary artery stenosis Doppler echocardiography can be considered as medically induced left pulmonary artery stenosis if the flow velocity of the left pulmonary artery exceeds 1.5 m/s. The position of the blocking umbrella should be adjusted in time to avoid excessive pulling of the umbrella into the pulmonary artery. At present, the largest model of imported Amplatzer arterial catheter closure blocker is 16/14mm, and the diameter of domestic PDA blocker is generally up to 22/20mm, and the polyester sheet sewn in the domestic blocker is 4 layers, which is more than the imported blocker (3 layers), so the flow blocking effect is better. Therefore, we advocate that for PDA with large diameter, domestic blocker should be preferred for treatment. If the diameter of 22/20mm is still residual shunt or obviously small, it is necessary to customize a larger diameter blocker. Temporary myocardial septal blocker can be used as an alternative blocker, and the choice of atrial septal defect blocker is not advocated (prone to complications such as hemolysis and residual leakage). For larger internal diameter arterial catheter blocking, repeated release and recovery should be avoided, otherwise it is easy to cause pulmonary artery entrapment. 4.Arterial catheter recanalization after surgical procedure Surgical ligation after recanalization due to local tissue adhesion, fibrosis and scar formation, the recanalized arterial catheter wall has poor elasticity and small extensibility, and the funnel section has the tendency to become smaller and shallower after ligation. The diameter of the selected Amplazter blocking umbrella should not differ too much from the narrowest diameter of the recanalized arterial conduit to avoid causing stenosis of the aortic arch or pulmonary artery. The Amplazter blocking umbrella selected should generally be 1 to 2 mm larger than the narrowest diameter of the recanalized arterial conduit, but if the narrowest diameter of the recanalized arterial conduit does not change after surgery, it should be selected to be 3 to 4 mm larger than the narrowest diameter of the recanalized arterial conduit.