title: Preclinical evaluation of implantable cardioverter-defibrillator developed for magnetic resonance imaging use.
abstract: BACKGROUND
  Many patients with an implantable cardioverter-defibrillator (ICD) have indications for magnetic resonance imaging (MRI). However, MRI is generally contraindicated in ICD patients because of potential risks from hazardous interactions between the MRI and ICD system.
  
  
  OBJECTIVE
  The purpose of this study was to use preclinical computer modeling, animal studies, and bench and scanner testing to demonstrate the safety of an ICD system developed for 1.5-T whole-body MRI.
  
  
  METHODS
  MRI hazards were assessed and mitigated using multiple approaches: design decisions to increase safety and reliability, modeling and simulation to quantify clinical MRI exposure levels, animal studies to quantify the physiologic effects of MRI exposure, and bench testing to evaluate safety margin.
  
  
  RESULTS
  Modeling estimated the incidence of a chronic change in pacing capture threshold >0.5 V and 1.0 V to be less than 1 in 160,000 and less than 1 in 1,000,000 cases, respectively. Modeling also estimated the incidence of unintended cardiac stimulation to occur in less than 1 in 1,000,000 cases. Animal studies demonstrated no delay in ventricular fibrillation detection and no reduction in ventricular fibrillation amplitude at clinical MRI exposure levels, even with multiple exposures. Bench and scanner testing demonstrated performance and safety against all other MRI-induced hazards.
  
  
  CONCLUSIONS
  A preclinical strategy that includes comprehensive computer modeling, animal studies, and bench and scanner testing predicts that an ICD system developed for the magnetic resonance environment is safe and poses very low risks when exposed to 1.5-T normal operating mode whole-body MRI.
authors.affiliation: Medical University of South Carolina, Charleston, South Carolina. Electronic address: goldmr@musc.edu.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Gold
authors.affiliation: University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Kanal
authors.affiliation: University Hospital Lausanne, Lausanne, Switzerland.
authors.forename: Juerg
authors.initials: J
authors.lastname: Schwitter
authors.affiliation: German Red Cross Hospital, Neuwied, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Sommer
authors.affiliation: Medtronic, Inc, Mounds View, Minnesota.
authors.forename: Hyun
authors.initials: H
authors.lastname: Yoon
authors.affiliation: Medtronic, Inc, Mounds View, Minnesota.
authors.forename: Michael
authors.initials: M
authors.lastname: Ellingson
authors.affiliation: Medtronic, Inc, Mounds View, Minnesota.
authors.forename: Lynn
authors.initials: L
authors.lastname: Landborg
authors.affiliation: Medtronic, Inc, Mounds View, Minnesota.
authors.forename: Tara
authors.initials: T
authors.lastname: Bratten
mesh_terms: D000818:Animals; D002318:Cardiovascular Diseases / Q000628:therapy*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D004869:Equipment Safety / Q000706:statistics & numerical data; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D010138:Pacemaker, Artificial / Q000009:adverse effects*; D015203:Reproducibility of Results; D014693:Ventricular Fibrillation / Q000453:epidemiology*
keywords: Defibrillator; Hazards; Implantable cardioverter-defibrillator; Lead electrode heating; Magnetic resonance imaging; Ventricular fibrillation detection