title: Long-term results of endocardial pacing with Autocapture threshold tracking pacemakers in children.
abstract: OBJECTIVE
  We aimed to evaluate the long-term results of endocardial pacing with Autocapture threshold tracking pacemakers in children.
  
  
  RESULTS
  Implantation and follow-up data of 20 children with these pacemakers were retrospectively evaluated. The pacemakers were implanted subpectorally in five and subcutaneously in 15 patients. The indication for pacing was high-grade atrioventricular block in 18 cases. The mean age at implantation was 7+/-4.8 years. Four patients were pacemaker dependant (heart rate < 30 bpm). At implantation, the mean pacing threshold was 0.5 V at 0.5 ms. The mean evoked response (ER) signal was 8.5+/-3.6 mV, and the polarisation signal (PS) was <1 mV in 15 patients and 1-2 mV in five patients. During the mean follow-up period of 60 months, mean ER signal decreased significantly to 7.7+/-6.3 mV at 24 months and 6.5+/-2.5 mV at 60 months (P < 0.05). In four of 15 patients (26.6%), with a predischarge PS value of <1 mV, it increased between 1 and 2 mV over time. During follow-up, autocapture function was deactivated in six (30%) patients; due to inappropriate ER/PS values in four and due to severe muscle twitching in two with subpectoral implants. These problems occurred during a median period of 21 months after implantation. Generators were replaced in three patients with Microny pacemakers because of battery depletion at 54, 66 and 78 months. In two of them autocapture function had been working since implantation. In seven of 10 patients, who completed > or = 60 months of follow-up, battery impedances were still at the predischarge level.
  
  
  CONCLUSIONS
  Autocapture function works well in most children at implantation. Mean ER signal significantly decreases over time despite stable pacing parameters. Autocapture function may become nonoperational due to decreased ER signal in some patients. Muscle twitching may be an important problem that may result in discontinuation of autocapture function in children with subpectoral implants.
authors.affiliation: Hacettepe University School of Medicine, Ankara, Turkey.
authors.forename: Alpay
authors.initials: A
authors.lastname: Celiker
authors.forename: Naci
authors.initials: N
authors.lastname: Ceviz
authors.forename: Osman
authors.initials: O
authors.lastname: Küçükosmanoğlu
mesh_terms: D000293:Adolescent; D002304:Cardiac Pacing, Artificial / Q000009:adverse effects / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D022062:Electrophysiologic Techniques, Cardiac; D004868:Equipment Failure; D005260:Female; D006327:Heart Block / Q000628:therapy*; D006801:Humans; D007223:Infant; D008297:Male; D010138:Pacemaker, Artificial / Q000009:adverse effects