OBJECTIVETo investigate the feasibility, advantages and efficacy of implantation of left atrial and ventricular epicardial dual chamber pacemaker to treat pediatric complete atrioventricular block.

METHODEleven children with median age 4.0 years (0.5-7.6 years) diagnosed as complete atrioventricular block resisting to drug therapy received implantations of left atrial and ventricular epicardial dual chamber pacemakers. Six were male and five female. Temporal or permanent right ventricular pacing was used for all of them before implantation of left atrial and ventricular epicardial dual chamber pacemakers. Three cases showed cardiac dysfunction. Left lateral thoracotomy was performed at 4th intercoastal space along anterior axillary line under general anesthesia, the pericardium was incised vertically anterior to the phrenic nerve, two pacing leads were individually located at left atrial appendage and left ventricular lateral wall. After all the parameters were detected to be satisfactory, a pouch was made at left abdomen under coastal margin. Dual chamber pacemaker was connected with pacing leads through subcutaneous tunnels. The sizes of heart chambers, cardiac functions, parameters of pacemaker, sensitivity, pacing status, PR interval and QRS interval were closely followed up post-operatively.

RESULTImplantations of pacemakers were successful for all of the patients with no complications associated with operations. Preoperative electrocardiograms showed QRS interval (180 ± 33)ms under right ventricular pacing, it decreased to (140 ± 24)ms after implantation of left atrial and ventricular epicardial dual chamber pacemaker, significantly lower than right ventricular pacing (t = 8.8, P < 0.05) . Atrioventricular (AV) interval was set at 90 ms, PR interval (124 ± 4)ms. Echocardiograms performed within 2-3 days after implantation of left atrial and ventricular epicardial dual chamber pacemakers showed that for the 3 cases who were previously under right atrial and right ventricular dual chamber pacing presenting cardiac dysfunction, their left ventricular diastolic diameter (LVDd) decreased from (46.3 ± 12.5) (32.0-55.0) ms to (44.7 ± 12.0) (31.0-53.0) mm and left ventricular ejection fraction (LVEF) increased from 30% ± 15% (18%-47%) to 44% ± 18% (33%-65%). During 2-14 months' follow up, LVEF increased progressively which became significantly higher than before (65% ± 8% vs. 30% ± 15%, t = 5.6, P < 0.05) . Cardiac chamber sizes and left ventricular systolic function for the other 8 patients maintain normal during follow up. Pacing status and sensitivity were satisfactory for all these patients during follow up.

CONCLUSIONImplantation of left atrial and ventricular epicardial pacemaker might be considered for children diagnosed as complete atrioventricular block for whom endocardial pacemaker could not be implanted, due to its utmost protection for cardiac function with minimal injury and its ability to prevent or reverse pacemaker syndrome. Left atrial and left ventricular epicardium should be regarded as the first-choice and routine locations for epicardial pacing.