title: Prospective evaluation of defibrillation threshold and postshock rhythm in young ICD recipients.
abstract: BACKGROUND
  Adaptation of implantable cardioverter defibrillator (ICD) systems to the needs of pediatric and congenital heart patients is problematic due to constraints of vascular and thoracic anatomy. An improved understanding of the defibrillation energy and postshock pacing requirements in such patients may help direct more tailored ICD therapy. We describe the first prospective evaluation of defibrillation threshold (DFT) and postshock rhythm in this population.
  
  
  METHODS
  We prospectively studied patients ≤ 60 kg at time of ICD intervention. DFTs were obtained using a binary search protocol with three VF inductions. Postshock pacing was programmed using a stepwise protocol, lowering the rate prior to each VF induction.
  
  
  RESULTS
  Twenty patients were enrolled: 11 had channelopathy, five congenital heart disease, and four cardiomyopathy. The median age was 16 years, median weight 48 kg. Twelve patients had a transvenous high-voltage coil; eight had pericardial +/- subcutaneous coil(s). Median DFT was 7 J (range 3-31 J); 19/20 patients had DFT ≤ 15 J and all patients <25 kg had DFT ≤ 9 J (n = 6). There was no difference in DFT between patients with transvenous versus pericardial +/- subcutaneous coils (median 7 J vs 6 J, P = 0.59). No patient with normal atrioventricular conduction prior to defibrillation required postshock pacing (n = 16). There were no adverse events.
  
  
  CONCLUSIONS
  These data suggest that many pediatric ICD patients have low DFTs and adequate postshock escape rhythm. This may help determine appropriate parameters for future design of pediatric-specific ICDs.
authors.affiliation: Department of Pediatrics, Vanderbilt University School of Medicine, and the Monroe Carell Jr. Children's Hospital at Vanderbilt, Nashville, Tennessee 37232-9119, USA. andrew.radbill@vanderbilt.edu
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Radbill
authors.forename: John K
authors.initials: JK
authors.lastname: Triedman
authors.forename: Charles I
authors.initials: CI
authors.lastname: Berul
authors.forename: Edward P
authors.initials: EP
authors.lastname: Walsh
authors.forename: Mark E
authors.initials: ME
authors.lastname: Alexander
authors.forename: Gregory
authors.initials: G
authors.lastname: Webster
authors.forename: Frank
authors.initials: F
authors.lastname: Cecchin
mesh_terms: D000293:Adolescent; D002304:Cardiac Pacing, Artificial; D002648:Child; D017147:Defibrillators, Implantable; D004056:Differential Threshold; D004554:Electric Countershock; D005260:Female; D006331:Heart Diseases / Q000628:therapy*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D011446:Prospective Studies; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D055815:Young Adult