title: [MRI in patients with cardiac pacemakers: in vitro and in vivo evaluation at 0.5 tesla].
abstract: OBJECTIVE
  MRI is currently regarded as absolutely contraindicated in patients with implanted cardiac pacemakers. In this prospective study safety and feasibility of MRI in patients with new generation pacemakers (PM) was evaluated in vitro and in vivo.
  
  
  METHODS
  14 PM models in vitro and 18 patients with implanted new generation PM underwent a MRI exam at 0.5 Tesla with standard spin, turbo spin, and gradient echo (FFE) sequences under continuous ECG-monitoring. PM inquiry was performed before and after the MRI exam, including assessment of stimulation thresholds.
  
  
  RESULTS
  In the static magnetic field all PM switched to the asynchronous mode due to activation of the Reed switch, resulting in continuous pacing at a fixed rate. In three PM models in vitro, however, after activation of the Reed switch, there was a software-induced switch back to the demand mode. In these PM inhibition and triggering were observed after starting the MRI scan due to influence of the pulsed magnetic fields. PM program changes, damage of PM components, dislocation/torque of the PM and rapid pacing of the PM were observed neither in vitro nor in vivo. Atrial and ventricular stimulation thresholds remained unchanged.
  
  
  CONCLUSIONS
  MRI at 0.5 Tesla should not be regarded as absolutely contraindicated in patients with implanted new generation PM. However, knowledge of the behaviour of the specific PM model in static and pulsed magnetic fields is required, if necessary also changes of the PM program prior to the MRI exam, continuous ECG monitoring and cardiological stand-by.
authors.affiliation: Radiologische Universitätsklinik Bonn.
authors.forename: T
authors.initials: T
authors.lastname: Sommer
authors.forename: G
authors.initials: G
authors.lastname: Lauck
authors.forename: R
authors.initials: R
authors.lastname: Schimpf
authors.forename: A
authors.initials: A
authors.lastname: von Smekal
authors.forename: S
authors.initials: S
authors.lastname: Wolke
authors.forename: W
authors.initials: W
authors.lastname: Block
authors.forename: J
authors.initials: J
authors.lastname: Gieseke
authors.forename: C
authors.initials: C
authors.lastname: Schneider
authors.forename: H D
authors.initials: HD
authors.lastname: Funke
authors.forename: H
authors.initials: H
authors.lastname: Schild
mesh_terms: D000075202:Contraindications; D004562:Electrocardiography; D005240:Feasibility Studies; D006321:Heart / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects / Q000379:methods*; D010138:Pacemaker, Artificial; D011446:Prospective Studies; D012680:Sensitivity and Specificity
vernacular_title: MRT bei Patienten mit Herzschrittmachern: In-vitro- und In-vivo-Evaluierung bei 0,5 Tesla.