title: Do we need pacemakers resistant to magnetic resonance imaging?
abstract: OBJECTIVE
  Manufacturers of pacemakers (PM) and of magnetic resonance imaging (MRI) devices state that MRI scanning of PM wearers is contraindicated. This paper tries to summarise which effects can interfere with PM, what can be hazardous, and how treatment of PM in MRI can be modified to guarantee compatibility.
  
  
  METHODS
  All PM tested were from deceased patients. Reed contact thresholds and reactions were investigated in low magnetostatic fields and compared with those in strong magnetostatic fields. Influence of gradient fields on PM and heating due to radiofrequency (RF) pulses were estimated. Thirty Legal Medicine Departments were questioned whether deaths of PM patients during MRI are known.
  
  
  RESULTS
  Reed contacts are influenced above 0.7 mT. In MRI fields only 28% of the PM in magnet mode remained so in all orientations. Of synchronous PM, 76% remained synchronous in all orientations. Gradient fields can influence sensing but cannot stimulate. Power density and temperature rise produced by RF fall rapidly with distance. Our question revealed six deaths. All suffered from sick-sinus-syndrome and all were not PM dependent. In three cases ventricular fibrillation was proven as the cause of death.
  
  
  CONCLUSIONS
  Asynchronous pacing due to magnetostatic and gradient fields may be problematic in patients with spontaneous rhythm. To avoid them, PM triggered MRI scan restricted to refractory period is proposed. Neither inhibition of PM nor heating of the electrode poses real risks. So far, we have examined eight patients 12 times in MRI triggered mode without problems.
authors.affiliation: Department of Legal Medicine, University Hospital, Giessen, Germany. werner.irnich@technik.med.uni-giessen.de
authors.forename: Werner
authors.initials: W
authors.lastname: Irnich
authors.forename: Burkhard
authors.initials: B
authors.lastname: Irnich
authors.forename: Christine
authors.initials: C
authors.lastname: Bartsch
authors.forename: Wilhelm Alfred
authors.initials: WA
authors.lastname: Stertmann
authors.forename: Hubert
authors.initials: H
authors.lastname: Gufler
authors.forename: Guenter
authors.initials: G
authors.lastname: Weiler
mesh_terms: D004867:Equipment Design / Q000009:adverse effects*; D006801:Humans; D008279:Magnetic Resonance Imaging; D010138:Pacemaker, Artificial; D012804:Sick Sinus Syndrome / Q000150:complications; D014693:Ventricular Fibrillation / Q000209:etiology