Conduction System Disturbance After Transcatheter Closure Of Perimembranous Ventricular Septal Defects

Objective: To investigate the effect of transcatheter closure on conduction system by analyzing clinical date and parameters of ECG in patients with perimembranous ventricular septal defects (PMVSD) in different times after transcatheter closure.Methods: The PMVSD patients in receiving transcatheter closure from July 2003 to March 2010 were included for following-up. All subjects underwent physical examination, electrocardiogram (ECG), transthoracic echocardiography (TTE) at l, 3, 6 and 12 months after the procedure and yearly thereafter. Follow up data including parameters of ECG were analyzed in 108 patients who had complete data.Results:(1) The incidences of overall heart block, CRBBB, IRBBB, LBBB,Ⅰdegree AVB, CAVB were 23.1%(25/108), 9.3%(10/108), 6.5%(7/108), 3.7%(4/108), 1.9%(2/108), 1.9%(2/108), respectively, after transcatheter closure of PMVSD. No a case had permanent pacemaker implanted. Heart block were detected in 16 patients (CLBBB n=3, CRBBB n=5,IRBBB n=7, and CAVB n=1) within 1 week post procedure, and in 9 patients (CLBBB n=1,CRBBB n=5, CRBBB with LAFB n=1,first-degree AVB n=2,and CAVB n=1) during follow-up. The proportions of early and delayed conduction block accounted for 64%(16/25), 36%(9/25) of overall conduction block, respectively. Heart block within 1 week postprocedure disappeared in 4 patients(25%) before discharge, in 5 patients(31.5%) at 1~2 years and in 6 patients(37.5%) at 5 years post- procedure. (2) Univariate analysis and multivariate logistic regression analysis showed PMVSD diameter(≥8mm) and occluder size(≥10mm) are the risk factors for conduction block after transcatheter closure of PMVSD(P<0.05). (3) Transcatheter closure of PMVSD resulted in a significant decrease of the QT interval, QT dispersion in the 0.5~2, 2~4, 4~7 years postprocedure, compared with those preprocedure and 1 week postprocedure(P<0.05). There were no significant changes in PR interval, QRS duration in the preprocedure, 1 week, 0.5~2, 2~4, 4~7 years postprocedure(P>0.05).Conclusion:(1) The incidence of overall heart block after transcatheter closure of PMVSD was a little high, most types of heart block were bundle branch block. The incidence of CAVB was low. So the risk of developing conducting system seriously damaged was not high. (2) Heart block after transcatheter closure of PMVSD occured not only within 1 week postprocedure but also during follow-up, more intensive observation and follow-up should be therefore needed. (3) PMVSD diameter(≥8mm) and occluder size (≥10mm) are the independent risk factors for heart block after transcatheter closure of PMVSD. (4) There were no significant changes in PR interval, QRS duration in preprocedure and different times after transcatheter closure of PMVSD. There were downward trend in QT interval, QT dispersion more than 6 months postprocedure.