| Background and Objective:Progress have been made significantly since the fist device closure of ventricular septal defect(VSD), and controversies surrounding such techniques persist. The early types of devices developed for VSD closure were associated with low success rates and high morbidity, and the fact that the devices were not specifically designed for peri-membranous(pm-VSD) contributes to conduction disturbance and atrioventricular(AV) block, which represents a main concern.By the development of domestic-made VSD-occluder, the success rate and complications related to this procedure are acceptable. Complete AV block, however, remains a preoccupying concern. Mechanisms underlying this complication are still unclear, and hypothesis have been proposed in several ways except invasive electrophysiology.This study focus on patients who underwent attempted transcathter closure of pm-VSD within the indication guided by Chinese Academy of Cardiovascular Sciences. Invasive parameters of His electrocardiogram were recorded prior to and following VSD closure during the procedure in each patient, to explore how transcathter closure techniques affect AV conductions and its relationship with AV block after the procedure.Material and Methods:(1) Patients population:32patients had an attempted transcathter pm-VSD closure in one insitituion. Mean age was10.9±11.2years (range3.0-52years). All patients are with normal sinus rhythm in surface ECG recording and had no significant AV block.(2) VSD-occluder and Adnexa: All patients accept domestic VSD-occluder. Adnexa package include transport sheathe, dilator, transport cable and loading sheathe.(3) Pocedure:All patients underwent right and left cardiac catheterization and angiography under X-ray guidance. The technique for pm-VSD closuring has been previously reported:①Vessel access was create fist;②then arteriovenous guide wire track through VSD was build;③placing transport sheathe;④pushing VSD-occluder through transport sheathe to VSD and open the two discs;⑤release the occluder when a proper position was proved by transthoracic echocardiography and angiography.(4) Electrophysiological study (EPS):①Invasive EPS recording:Invasive His bundle electrograph recording was performed prior to cardiac catheterization and following the release of VSD-occluder during the procedure, and AH, HV, AV intervals were measured. Possibility of the occurrence AVB was estimated during the procedure based on changing of the basic His intervals.②Surface ECG monitoring: recording patients surface ECG before and5to7days after the procedure, and PR intervals, configuration of QRS complex were recorded.(5) Follow-ups:Patients underwent ECG monitoring and TTE at1,3,6, and12month after discharge and yearly thereafter. Adverse events were ascertained at each assessment on the basis of clinical evaluation.Result:(1) Invasive His bundle recording was performed in32patients, no severe complications related to electrode catheter manipulation.(2)30out of32patients had a success release of VSD-occluder. No significant change for AH, HV or AV measurement was observed in those patients(P>0.1).(3) EPS parameters with an increased measurement of15%or more were observed in15/30patients,6among them had AV or intraventricular block, and only2had AV or intraventricular block in the left15patients respectively.(4) With respect to EPS changes, the only detectable risk factor was procedure age. More precisely, AV interval recored after the procedure prolonged significantly than basic recording in patient under10[(130.9±28.4)ms:(119.3±15.8)ms, p=0.048], while no significant change with AH, HV or AV measurement was observed in the other group.(5) With respect to the occurrence of new onset conduction disturbances on surface ECG, there were no identifiable relationships with septal aneurysm(P>0.5), VSD diameters(P>0.5), device/VSD ratio(P>0.6).Conclusion:(1) His mapping in transcathter closure of pm-VSD can detect AV conduction disturbance more precisely, and possesses important clinical value on prediction of potential possibility of AV block after the procedure.(2) Transcathter closure of pm-VSD promotes relative changes in the electrophysiologic parameters of the AV conduction system. These changes had suggestive predictivity of new conduction abnormalities in or after the procedure of VSD closure, thus would be helpful to VSD treatment protocol.(3) In attempting VSD closuring, His bundle mapping provide important clinical value on deciding release VSD-occluder or not during the procedure. |
