title: Recommendations for Lengthening of Magnetically Controlled Growing Rods in Children With Pacemakers.
abstract: OBJECTIVE
  Pacemakers are currently identified as a contraindication for the use of magnetic growth rods (MGRs). This arises from concern that magnetic fields generated by the MGR external remote controller (ERC) during lengthening procedures may induce pacemaker dysfunction. We investigated (1) whether MGR lengthening affects pacemaker function, and (2) if the magnetic field of a pacemaker affects MGR lengthening.
  
  
  METHODS
  MGRs were tested in conjunction with an magnetic resonance imaging-compatible pacemaker, which was connected to a virtual patient under continuous cardiac monitoring. To determine whether pacemaker function was affected during MGR lengthening, the electrocardiogram trace was monitored for arrhythmias, whereas an ERC was applied to lengthen the MGRs at varying distances from the pacemaker. To investigate if MGR lengthening was affected by the presence of a pacemaker, at the start and end of the experiment, the ability of the rods to fully elongate and shorten was tested to check for conservation of function.
  
  
  RESULTS
  When the pacemaker was in normal mode, <16 cm away from the activated ERC during MGR lengthening, pacemaker function was affected by the ERC's magnetic forces. At this distance, prophylactically switching the pacemaker to tonic mode before lengthening prevented occurrence of inappropriate pacing discharges. No deleterious effect of the pacemaker's magnetic field on the MGR lengthening mechanism was identified.
  
  
  CONCLUSIONS
  Magnetic resonance imaging-compatible pacemakers appear safe for concomitant use with MGRs, provided a pacemaker technician prophylactically switches the pacemaker to tonic function before outpatient lengthening procedures.
  
  
  CONCLUSIONS
  This experiment was designed to provide the first safety information on MGR lengthening in children with pacemakers. Although currently a rare clinical scenario, with increasing use of MGRs, this clinical scenario may arise more frequently in the future.
authors.affiliation: *Exeter Spine Unit, Princess Elizabeth Orthopaedic Centre, Royal Devon and Exeter NHS Foundation Trust, Exeter ‡The James Cook University Hospital, Middlesbrough, United Kingdom †Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Kimberly-Anne
authors.initials: KA
authors.lastname: Tan
authors.forename: Mathew D
authors.initials: MD
authors.lastname: Sewell
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Clarke
authors.forename: Daniel
authors.initials: D
authors.lastname: Chan
authors.forename: Oliver M
authors.initials: OM
authors.lastname: Stokes
authors.forename: Shahid N
authors.initials: SN
authors.lastname: Khan
authors.forename: Michael
authors.initials: M
authors.lastname: Hutton
mesh_terms: D001852:Bone Lengthening / Q000295:instrumentation* / Q000379:methods; D002648:Child; D000075202:Contraindications; D004562:Electrocardiography; D006801:Humans; D060328:Magnetic Phenomena; D008279:Magnetic Resonance Imaging / Q000009:adverse effects; D059346:Magnets / Q000009:adverse effects*; D019637:Orthopedic Procedures / Q000295:instrumentation* / Q000379:methods; D010138:Pacemaker, Artificial; D012600:Scoliosis / Q000601:surgery*