Related Experiment Videos
[MRI in patients with cardiac pacemakers: in vitro and in vivo evaluation at 0.5 tesla]
Purpose:
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.
Conclusion:
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.
Insights
Magnetic Resonance Imaging (MRI) is safe for new generation pacemakers (PM) under specific conditions. Studies show MRI at 0.5 Tesla does not cause damage, but pacemaker behavior requires careful monitoring.
Area of Science:
- Cardiovascular Imaging
- Medical Device Safety
- Electrophysiology
Background:
- Cardiac pacemakers (PM) have historically been contraindicated for Magnetic Resonance Imaging (MRI) due to safety concerns.
- Newer generation pacemakers are designed with improved shielding and materials, necessitating re-evaluation of MRI compatibility.
Purpose of the Study:
- To evaluate the safety and feasibility of performing MRI in patients with new generation pacemakers.
- To assess the in vitro and in vivo effects of MRI on pacemaker function and integrity.
Main Methods:
- 14 pacemaker models were tested in vitro, and 18 patients with new generation pacemakers underwent MRI at 0.5 Tesla.
- Standard spin, turbo spin, and gradient echo sequences were used, with continuous ECG monitoring and pacemaker interrogation before and after the scan.
- Pacemaker stimulation thresholds were assessed to evaluate pacing efficacy.
Main Results:
- In static magnetic fields, all pacemakers initially switched to asynchronous mode; some models reverted to demand mode due to software.
- Pulsed magnetic fields caused inhibition and triggering in some pacemakers, but no program changes, component damage, or pacing issues were observed.
- Atrial and ventricular stimulation thresholds remained unchanged throughout the MRI procedures.
Conclusions:
- MRI at 0.5 Tesla is not absolutely contraindicated for patients with new generation pacemakers.
- Understanding the specific pacemaker model's behavior in static and pulsed magnetic fields is crucial.
- Pre-MRI pacemaker programming adjustments, continuous ECG monitoring, and cardiological support are recommended for safe scanning.