ABSTRACT
Cardiac pacing is an effective treatment for cardiac pacing and conduction dysfunction and severe heart failure. However， the conventional right ventricular pacing may increase the incidences of heart failure and atrial fibrillation， and biventricular pacing has a relatively high non-response rate. As a new technique of physiological pacing， a number of studies in recent years have been conducted to show the stability of pacing parameters and good cardiac synchronization of his-purkinje system pacing. This article reviews the current status of research and progress in the effects of his-purkinje conduction system pacing on cardiac function， so as to provide a theoretical basis for promoting the development of this technology.
ABSTRACT
Objective To investigate the efficacy of permanent left ventricular epicardial pacing through left lateral thoracotomy in children with complete atrioventricular block (CAVB)or complete left bundle branch block (CLBBB)as well as its effects on heart synchronization.Methods Permanent left ventricular epicardial pacemakers were implanted through left lateral thoracotomy in 26 children with CAVB or CLBBB in Heart Center,the First Affiliated Hospital of Tsinghua University.These children aged (2.3 ±2.1 )years old (1 month -9 years old),weight (1 1 .2 ± 5.8)kg (5 -32 kg),among them 1 5 cases were male and 1 1 cases were female.Among the 26 patients,24 patients had CAVB and 2 patients had dilated cardiomyopathy secondary to CLBBB.Fifteen children who visited the Pediatrics Department for acute upper respiratory tract infection were chosen as control group.The efficacy of left ventricular epi-cardial pacemakers was analyzed and its effects on heart synchronization were observed by using tissue Doppler imaging (TDI).Results Implantations of pacemakers were successfully conducted in all the 26 patients with no complications associated with operations.Left atrial and ventricular dual chamber epicardial pacemakers were implanted in 21 patients and left ventricular single chamber epicardial pacemakers were implanted in 5 patients.Within the follow -up period of (28.2 ±1 5.1 )months (1 month -51 months),atrial and ventricular leads were 1 00% effective.No significant diffe-rence was found in atrial electrode sensing,ventricular electrode threshold and ventricular electrode impedance com-pared with those during implantation(P >0.05).For the 6 patients with preoperative cardiac insufficiency,their left ventricular diastolic diameters decreased from (48.50 ±1 1 .1 0)mm to (40.67 ±6.40)mm after operation,and the difference was significant (t =2.96,P =0.030);but left ventricular ejection fraction increased from 0.27 ±0.08 to 0.53 ±0.08 after operation,and the difference was significant (t =-5.02,P =0.004).Two patients with right ven-tricular pacing developed pacemaker syndrome and were switched to left ventricular epicardial pacing.Their cardiac function returned to normal 1 .5 and 2.0 years later,respectively.Fifteen patients received evaluation of heart synchroni-zation by TDI.No significant difference was found in LVEF,septal -to -lateral wall motion delay,septal -to -posterior wall motion delay and standard deviation of Standard deviation of the peak tissue velocity between these 2 groups(all P >0.05).Conclusions For children requiring epicardial pacing,left ventricular epicardial pacing is safe and effec-tive,which can protect left ventricular systolic synchronization,prevent or reverse the pacemaker syndrome.