The basic principle of interventional treatment for ventricular septal defect shows the use of a double-disc structured occluder, with one disc on the left ventricular surface and the other disc on the right ventricular surface, and the waist connecting the two discs is exactly at the defective septum. The ventricular septal defect is closed by the mechanism of both discs, the waist, the polymer compound sewn inside the occluder, the thrombus formed inside the occluder after the placement of the occluder and the endocardium completely covering the surface of the occluder for about 3 months. Indications and contraindications 1. Indications: (1) perimembranous VSD, age ≥ 3 years, with surgical indications for perimembranous VSD, defect edge distance from aortic right coronary valve > 1.5mm with eccentric blocker, > 2.0mm with symmetric blocker. Without right coronary valve prolapse obscuring the defect orifice and aortic regurgitation, eccentric blocker is used for defect edge distance from tricuspid valve≥2mm, symmetric blocker is used for > 1.5mm. (2) Myocardial VSD with right ventricular surface diameter > 2 mm with left ventricular enlargement. (3)Intracrural VSD, the distance of the defect stump from the pulmonary valve > 3mm, and the distance from the junction of the right coronary, left coronary and noncoronary valves > 2mm, with varying degrees of left ventricular enlargement. ( 4) Post-surgical residual perimembranous or myocardial VSD. 2. Contraindications: (1) VSD combined with severe PH with right→left shunt. ( 2) VSD combined with other cardiac malformations requiring surgical treatment. ( 3) Defect anatomical location is poor, after the placement of the blocker affect the function of the aortic valve or atrioventricular valve. Preoperative preparation: (1) Relevant laboratory tests; transthoracic or (and) esophageal echocardiography, electrocardiogram and X-ray chest film. (2) Oral aspirin 1d before surgery, 3-5mg/( kg·d) for children, 3mg/( kg·d) for adults. (1) Left and right heart catheterization and cardiovascular imaging: femoral vein and femoral artery were cannulated under local or general anesthesia, and heparin 100 U/kg was routinely given, and the right heart catheterization was performed first to measure pressure and blood oxygen, and to detect pulmonary artery pressure and Qp/Qs. The size of VSD and its distance from the aortic valve were measured, followed by ascending aortogram to observe the presence of aortic valve prolapse and regurgitation. (2) Transthoracic ultrasound (TTE) or transesophageal ultrasound (TEE): to evaluate the location, size, number, adjacent structures, and relationship with the valve of VSD, and to measure the distance from the edge of the defect to the aortic valve and the formation of membrane septal aneurysm in membrane VSD. The examination of the peripheral anatomy of the myocardial VSD near the apex will help in the selection of the occluder and the route. 3, blocking method: perimembranous VSD blocking method: currently the most commonly used is the domestic blocker and Amp latzer perimembranous VSD blocker and delivery system for blocking surgery. (1)Establish the arteriovenous track:usually apply 5-6F right coronary catheter or formed pigtail catheter through femoral artery and aorta to the left ventricle, enter the right ventricle through the head end of the exploratory catheter via VSD, then insert 0.035 inch soft tip long exchange guidewire through the catheter into the right ventricle and push it to the pulmonary artery or superior vena cava, then insert a captive device through the end hole catheter from the femoral vein to cover the guidewire of the pulmonary artery or superior vena cava The femoral vein is then pulled out from the femoral vein to establish a femoral vein-right atrium-right ventricle-left ventricle-femoral artery track. (2) Insert a suitable long sheath along the track from the femoral vein end to the right atrium to meet the right coronary catheter (kissing catheter technique), insert the long sheath and dilatation tube together along the guidewire to the aortic arch, withdraw the dilatation tube inside the long sheath, then slowly withdraw the long sheath to the left ventricular outflow tract, push the exchange guidewire and right coronary catheter from the arterial end to the tip of the left ventricle, the head end of the long sheath placed in the left ventricle then points to the apex, and then the arterial end is replaced by a pigtail catheter. Then the arterial end is replaced by a pigtail catheter, inserted into the left ventricle, and the exchange guidewire is withdrawn. (3) Placement of the blocker: Select a blocker of appropriate shape and size and connect it to the special delivery guidewire and delivery catheter, then insert the blocker into the delivery system via the long sheath to deliver the blocker to the end of the long sheath, retract the long sheath to release the left disc and adhere to the ventricular septum, make sure the position is good, then embed the blocker in the VSD at the waist, retract the long sheath and release the right disc. In the case of ventricular septal tumor, most of the symmetric blockers are used to block the left ventricular surface of the defect or the left ventricular side of the rupture of the membranous tumor. The position of the blocker, the presence of shunt and valve regurgitation are observed under TEE/TTE surveillance, followed by left ventriculography to confirm the proper position and shunt, and ascending aortic angiography to confirm the presence of aortic regurgitation. (4) Release the occluder: After satisfactory results of X-ray and ultrasound examination, the occluder can be released and the long sheath and catheter can be withdrawn and compression can be applied to stop the bleeding. After removing the long sheath and catheter, compression is applied to stop the bleeding. 4.Myocardial ventricular septal defect: (1) Establish the arteriovenous track via VSD. Since the myocardial VSD can be located in the middle of the ventricular septum or close to the apex, it is technically different from the membrane VSD occlusion. Usually, the left femoral artery-aorta-left ventricle-right ventricle-right internal jugular vein (or right femoral vein) track is established. (2) Placement and release of blocker ①cis-way: the long sheath is inserted into the right ventricle through the internal jugular vein (or femoral vein) and reaches the left ventricle through the VSD, and then the blocker is placed as usual; ②reverse way: when the myocardial VSD is close to the apex, there are many myocardial trabeculae on the right ventricular surface or the right ventricular surface defect is small and difficult to be inserted in the cis-way. Problems to be noted in the operation (1) Generally, domestic symmetric blockers should be used for VSD blocking of membranous tumors, because most membranous tumors are bag-shaped and have multiple breaches, and asymmetric type is easy to cause incomplete blocking. The symmetric blocker is required to release the left ventricular disc in the left ventricular surface, and the model should be as long as the diameter of the left ventricular surface or add 1~2mm], and choose the model that covers the farthest distance between ruptures for the multiple rupture type. (2) VSD blocking select blocker diameter should not be too large, otherwise it is easy to cause direct or indirect compression of the conduction bundle. Because the atrioventricular bundle and branches travel on the posterior lower edge of the perimembranous VSD, the blocker should be retracted when a high degree of AVB or aortic insufficiency occurs before releasing the blocker due to operation and other factors. ( 3) The perimembranous VSD is closely related to the tricuspid valve, so it is important to note that if the guidewire passes through the tricuspid tendon, the catheter and sheath will have resistance to pushing, and must be reoperated at this time, otherwise it will cause damage to the tricuspid tendon and severe tricuspid valve insufficiency, which requires surgery. (4) 1 week after VSD occlusion is the peak period for the occurrence of grade III AV B. Therefore, close cardiac monitoring and glucocorticoid prophylaxis should be given for 3-5 d. After discharge, the electrocardiogram should be reviewed regularly. V. Severe complications and treatment of precordial catheter intervention 1. Femoral arteriovenous fistula: It occurs mostly in infants and young children, and is related to the close proximity of femoral arterioles, improper puncture points, or thicker delivery sheaths. Therefore, we should pay attention to the lower extremity abduction when puncturing, and generally the femoral arteriovenous fistula can be confirmed by ultrasound, if the diameter is not large, it can be compressed locally, and if it does not heal spontaneously, surgical operation is needed. 2, valve closure incompetence: tricuspid valve closure incompetence is mostly seen in PBPV or VSD occlusion, mainly due to the guidewire or catheter through the tendon or papillary muscle, VSD blocker compression tricuspid valve or PBPV balloon is too long to damage the tricuspid valve structure, so in the operation should be gentle, if the guidewire through the tendon or papillary muscle to immediately withdraw and do not forcibly push the catheter or balloon. One of the serious complications of VSD occlusion is aortic regurgitation, so the appropriate type and size of occluder should be selected and the occluder should be released after echocardiography. The aortic regurgitation should be confirmed by ultrasound and ascending aortogram before releasing the blocker, and if moderate aortic regurgitation occurs after surgery, close follow-up should be performed if necessary. 3, blocker dislodgement: ASD, VSD, PDA blocking can occur, mostly intraoperative, mostly due to small blocker selection, improper operation, once it occurs, according to the location of dislodgement, blocker size, the patient’s symptoms to decide to use foreign body clamp grasping or surgery. 4, pericardial compression: Mostly seen in ASD blocking surgery, when the catheter enters the left superior vein, the operation is rough and penetrates the left heart ear, once it happens, the operation should be stopped immediately, and the pericardial drainage or surgery should be selected according to the echocardiogram to determine the amount of pericardial effusion. 5, acute mechanical hemolysis: most of them occur in the PDA blocking or VSD blocking, the choice of blocking device is too small to produce postoperative residual shunt, once it occurs, we should use hormones, sodium bicarbonate alkalinization of urine to protect renal function, the treatment is not effective, can be re-imaging, choose blocking device to block residual shunt or surgical treatment. 6, arrhythmia: during the catheterization process, due to catheter stimulation, most of the transient arrhythmias can be produced, but most of them recovered after stopping stimulation, among them, VSD blocking can produce grade III AVB during or 1 week after the operation, once grade III AVB occurs, apply hormone, vitamin C and myocardial nutrient drugs, implant temporary pacemaker if necessary, if 2-3 weeks does not recover, a permanent pacemaker should be implanted. 7, death: the incidence of serious complications of precordial intervention is very low, but there are reports of death ( < 015% ), mostly in neonates or infants with serious conditions when serious complications occur improperly or untimely. Strict mastery of indications, standardized operation, and involvement of highly trained personnel are the guarantee to avoid serious complications.