Transcatheter Closure Of Perimembranous And Muscular Ventricular Septal Defects Using The New Amplatzer VSD Occluder And The Effect Of Cardiac Conductive System

Section A: Establishment and closure of ventricular septal defect and the effect of cardiac conductive system in dogsObjective To research and understand the pathological and hemodynamic effect of ventricular septal defect (VSD), the experimental animal models of sub-arterial infundibular / membranous VSD were established with revised aortic cutter in dogs, To understand and evaluate the effect of the VSD occluding procedure on atrioventricular (AV) conductive system in dogs, we occluded the VSD with Amplatzer VSD occluder in the experimental animal models of VSD and observe atrioventricular conductive time (AV period), Wenckebach points of the atrioventricular conductive and atrioventricular nodal effective refractory period (ERP) before and after procedure by means of the cardiac catheter electrophysiologic examination.Methods Thoracotomy was performed on eight dogs through right fourth costal region with left lateral decubitus padded 45 degree high after general anesthesia and intrabronchial intubation after transthoracic echocardiographic (TTE) examination , revised aortic cutter was put into right ventricle via an incision on right ventricular outflow, then vertically punctured through the septum by the help of TTE. VSDs were determined by the cardiac systolic murmur and TTE, then the aortic cutter was retreated out of the heart. The peak velocity and pressure of transseptal shunt was measured by TTE. The AV period, Wenckebach points of the atrioventricular conductive and ERP before and after VSD established procedure by the cardiac catheter electrophysiologic examination. All cases underwent an catheter closure using the new Amplatzer membranous VSD occluder. The 6-7 F sheath was placed to left ventricle through VSD. The VSD occluder was first released in the left ventricular side, pull back catheter a little then release right disc of device under the X-ray fluoroscopy and TTE guidance. The cardiac electrophysiologic examinations were performed before and after the closure procedure so as to observe the effect of atrioventricular conductive system.Results Six dogs had successful acquisition of VSDs. One week later, Doppler echocardiography demonstrated defects varied from 2.8～4.0 mm, the mean value of 3.4 mm. The transseptal shunts with peak velocities ranged from1.6～4.2 m/s, the mean value of 3.3 m/s. Transseptal defect pressure was from 38～52 mmHg, the mean value of 46 mmHg. The pulmonary pressure was ranged from 25～32mmHg, the mean value of 29 mmHg. There were no obvious changes of echocardiographic paraments before and after the eatablishment of VSD. Six dogs had successful occlude of VSDs, of which one had a thee-degree A-V block and died 2 hours later, the others had a more prolonged the AV period and lower Wenckebach points after catheter closure than before (P<0.05), of which 2 cases had the AV period more than 150ms, the AV period and lower Wenckebach point in 5 cases had recovered a few within one week follow-up period. There were no obvious changes of atrioventricular nodal refractory period before and after catheter closure.Conclusion Establishment and closure of ventricular septal defect with revised aortic cutter and Amplatzer VSD occluder were successful in dogs. Appropriate cutter and VSD device, familiar anatomy of heart, dexterous operation can ensure success and prevent complication. Adjusting direction and the choice of the cutter can get different types and diameters of VSD. The prolonged AV conductive time, even severe AV block, showed AV conductive system may be affected easily in the occlude of VSD, so it is necessary to monitor and operate carefully for preventing the AV and bundle branch block in and after operation. Successful Establishment and closure of ventricular septal defect have great significance to the development of VSD clinical intervention therapy. Section B: Transcatheter closure of perimembranous and muscular ventricular septal defects using the new Amplatzer VSD occluder and the effect of cardiac conductive systemObjective Ventricular septal defects (VSD) is a common defect in congenital heart disease. About 70% of all VSDs are perimembranous/ membranous. The treatment of VSD need surgical repair before. The intervention therapy of congenital heart disease has developed rapidly. To evaluate the feasibi1ity, efficacy and complication of transcatheter closure of perimembranous and muscular VSD, we used the new Amplatzer membranous and muscular VSD occluder to occlude perimembranous and muscular VSD and observed the effect of membranous VSD occluding procedure on atrioventricular (AV) conductive system.Methods Nineteen patients (12 males, 7 females) with perimembranous VSD and two patients (1 male, 1 female) with muscular VSD underwent an catheter closure using the new Amplatzer membranous and muscular VSD occluder. The new insymmetry Amplatzer membranous and symmetry muscular VSD occluder are made of nitinol wire with polyester mesh inside enhance clotting. The devices is available in sizes ranging from 4 to 20 mm. The device requires 6-9 Fr delivery sheath. All patients who were eligible for device closure by means of cardiac Doppler echocardiography routinely measure the parameters of hemodynamics and the angiography of left ventricle before catheter closure. Artery-venous track was set up under the X-ray fluoroscopy, transesophageal (TEE) or transthoracic echocardiography (TTE) guidance. Devices were first released in the left ventricular side, pull back catheter a little then release right disc of device. The echocardiography and the angiography of left ventricle and ascend Aorta were repeated 10 minters later. After identified the normal location and stability, no obvious resident shunt, the devices were release totally. Nineteen patients with perimembranous VSD underwent the cardiac electrophysiologic examination, including atrioventricular conductive time (AV interval) and atrioventricular nodal refractory period before and after catheter closure. All patients were followed up at 2 weeks,1 month,3 months and 6 months after the procedures.Results The devices were deployed successfully in 21 patients.There was complete closure in 18 patients immediately,and tiny ( <2 mm ) residual shunt in 3 patients. The residual shunt all disappeared within 1 day. A-V interval was more prolonged after catheter closure than before in 19 patients with perimembranous VSD (P<0.01), of which 3 cases had the AV interval and P-R interval more than 200ms, the P-R interval in 2 cases had recovered normal within one week follow-up period. There were no obvious changes of atrioventricular nodal refractory time before and after catheter closure. There were no obvious changes of the AV interval and atrioventricular nodal refractory time before and after catheter closure in two patients with muscular VSD. There were no other severe complications in all 21 cases. Conclusions Transcatheter closure of membranous and muscular VSD using the new Amplatzer membranous and muscular VSD occluder is safe and effective. The new Amplatzer membranous and muscular VSD occluder can be received back in operation and deployed again, The insymmetry structure of membranous VSD occluder has less effects on aortic valves. The AV conductive system may affected in the occlude of membranous VSD because AV conductive bundle near VSD closely, it is necessary to monitor and prevent the AV and bundle branch block. The operating technique,sizes of device and time of procedure all may be very important to prevent AV block and branch bundle.