title: A computer modeling tool for comparing novel ICD electrode orientations in children and adults.
abstract: BACKGROUND
  Use of implantable cardiac defibrillators (ICDs) in children and patients with congenital heart disease is complicated by body size and anatomy. A variety of creative implantation techniques has been used empirically in these groups on an ad hoc basis.
  
  
  OBJECTIVE
  To rationalize ICD placement in special populations, we used subject-specific, image-based finite element models (FEMs) to compare electric fields and expected defibrillation thresholds (DFTs) using standard and novel electrode configurations.
  
  
  METHODS
  FEMs were created by segmenting normal torso computed tomography scans of subjects ages 2, 10, and 29 years and 1 adult with congenital heart disease into tissue compartments, meshing, and assigning tissue conductivities. The FEMs were modified by interactive placement of ICD electrode models in clinically relevant electrode configurations, and metrics of relative defibrillation safety and efficacy were calculated.
  
  
  RESULTS
  Predicted DFTs for standard transvenous configurations were comparable with published results. Although transvenous systems generally predicted lower DFTs, a variety of extracardiac orientations were also predicted to be comparably effective in children and adults. Significant trend effects on DFTs were associated with body size and electrode length. In many situations, small alterations in electrode placement and patient anatomy resulted in significant variation of predicted DFT. We also show patient-specific use of this technique for optimization of electrode placement.
  
  
  CONCLUSIONS
  Image-based FEMs allow predictive modeling of defibrillation scenarios and predict large changes in DFTs with clinically relevant variations of electrode placement. Extracardiac ICDs are predicted to be effective in both children and adults. This approach may aid both ICD development and patient-specific optimization of electrode placement. Further development and validation are needed for clinical or industrial utilization.
authors: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts 02115, USA.
authors: Matthew
authors: M
authors: Jolley
authors: Jeroen
authors: J
authors: Stinstra
authors: Steve
authors: S
authors: Pieper
authors: Rob
authors: R
authors: Macleod
authors: Dana H
authors: DH
authors: Brooks
authors: Frank
authors: F
authors: Cecchin
authors: John K
authors: JK
authors: Triedman
mesh_terms: D000328:Adult; D049628:Body Size; D002648:Child; D002675:Child, Preschool; D003198:Computer Simulation; D017147:Defibrillators, Implantable; D004566:Electrodes; D005260:Female; D020342:Finite Element Analysis; D006330:Heart Defects, Congenital / Q000628:therapy*; D006801:Humans; D008297:Male; D012984:Software