[Transthoracic implantation of dual-chamber pacemaker for synchronous treatment of cardiac dysfunction due to idiopathic complete left bundle branch block in children]

Objective: To investigate the efficacy and feasibility of transthoracic implantation of permanent left atrial and left ventricular dual-chamber pacemaker for synchronous treatment of cardiac dysfunction due to idiopathic complete left bundle branch block (CLBBB) in children. Methods: The clinical data of five children with cardiac dysfunction due to idiopathic CLBBB and accepting implantation of permanent left atrial and left ventricular epicardial dual chamber pacemaker from January 2015 to July 2019 at the Pediatric Cardiologic Department of the First Hospital of Tsinghua University were analyzed retrospectively. The effects of pacemaker implantation on patients' cardiac function and cardiac synchrony were evaluated by echocardiogram. Results: Among 5 patients, 2 were males and 3 females. At the time of pacemaker implantation, the age of these patients was 0.5-5.7 years, the left ventricle ejection fraction (LVEF) was 29%-46%, the left ventricle end stage of diastolic diameter was 30-53 mm and the mean Z score was 4.0-34.0. Pacemaker was successfully implanted for all the patients. After the implantation, medications that can suppress atrioventricular node conduction were used and sensed atrioventricular delay (SAV) parameters were modulated until patients' QRS duration became shortest and the percentage of left ventricular pacing increased to and maintained at 97% to 100%. Patients' QRS duration was 120-160 ms before implantation and 90-120 ms after implantation. Patients' cardiac function began to improve 1 day to 1 month after implantation. Patients' cardiac function normalized after a mean of 1-12 months. LVEF increased from 29%-46% to 55%-67%. During the follow-up, interventricular mechanical delay, septal-to-posterior wall motion delay, and left ventricular systolic dyssynchrony index decreased significantly: IVMD decreased from 31-62 ms to 26-50 ms; SPWMD decreased from 40-63 ms to 10-50 ms and Ts-SD decreased from 34.3-50.3 ms to 16.3-31.4 ms. The global longitudinal strain of left ventricle decreased from -7.7%--13.8% to -13.5%--20.3%. Conclusion: Cardiac dysfunction due to CLBBB in children can be treated with transthoracic implantation of permanent epicardial left atrial and left ventricular dual chamber pacemaker which can substitute three chamber pacemaker to achieve the effects of synchronous therapy that lead to reversion and normalization of cardiac function.