Implante de marca-passo em crianças e adolescentes: análise evolutiva e experiência de um serviço

Abstract

Pacemaker implantation is an important therapeutic option in the treatment of atrioventricular conduction disorders in pediatric patients; however, few studies have broached this subject. Objective- To describe the clinical profile and outcomes on pediatric patients with atrioventricular block (AVB) and permanent pacing. Methods- This observational and retrospective study was carried out in 50 patients diagnosed with AVB from 1988 to 2013. The analysis encompassed demographic and social characteristics, clinical and laboratorial data, and association with structural congenital heart defects, type and technique of pacemaker implantation, pacing threshold, complications and presence of ventricular dysfunction secondary to cardiac pacing. Results- The mean age was 81.7 months (SD ± 67.3) and median of 60 months; 60.0% of patients were female. The period of follow-up ranged from 1 to 20 (mean:10.8 ± 4.7) years. In patients with congenital complete AVB, the pacemaker was implanted at an earlier age when compared with other causes, (p <0.001). The main indications for pacemaker implantation were congenital complete AVB (54.0%) and post-operative complete AVB (34.0%). Other less frequent causes were bradycardia or pauses of at least three seconds related to sick sinus syndrome, Chagas disease, second-degree AVB Mobitz II, Kearns Sayres syndrome and junctional rhythm. Regarding the implantation techniques, the electrodes were placed using the endocardial approach in 52.0% and the epicardial in 48.0%, from which 75,0% were subsequently replaced by endocardial electrodes. Associated congenital heart disease occurred in 50,0% of patients. After a period of five years following the pacemaker implantation in patients with structural congenital heart disease, there were significant difference of atrial pacing thresholds (p=0,028) which did not occur with ventricular pacing thresholds. After a similar period of follow-up, the ventricular impedance showed a tendency of stability and the increase of the atrial impedance was not significant (p = 0.758). At least once 26% of patients had to undergo a reoperation due to battery depletion.Atrial electrodes were replaced in 14,0% and ventricular electrodes in 10,0% of patients. Using the Kaplan-Meier estimator, a longer survival free of events was seen among patients with congenital AVB when compared to the group pacing for post-operative AVB (p = 0.018); however, no difference was found among patients with congenital complete AVB with and without congenital heart disease (p=0,694). Complications ocurred in 34% (17/50) of the patients and in 76,5% (13/17) complications were related to the electrodes, all of which with active fixation mechanism. Left ventricular dysfunction occurred in 24.0% (6/25) of patients who had echocardiographic reports analyzed in this study. However, it was not possible to attribute this event exclusively to cardiac pacing. Conclusions- It is important to consider childrens anatomical and physiological particularities when choosing the pacing system and the implantation technique. Taking into account the high prevalence of complications it is mandatory the pacemaker programming and control besides patients clinical and laboratorial follow-up.