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Frequently Asked Questions

Q: What are the hazards posed by an MR scanner to a pacemaker or defibrillator?

A: Electromagnetic interference (EMI) produced during the MRI has the potential to induce several hazardous effects impacting the normal operation of implantable pacemakers and defibrillators. These include:

  • Vibration
  • Force and torque effects
  • Device interactions with MR magnetic fields
  • Unintended stimulation
  • IPG/ICD heating
  • Lead heating

Q: What are the risks for a patient with an implantable device during an MRI?

A: Possible risks include:

  • Mechanical forces causing rotational force (torque), device dislodgement
  • High rate pacing beyond the pacemaker rate limit
  • Inappropriate pacing leading to arrhythmia
  • Oversensing leading to failure to pace
  • Undersensing leading to inappropriate pacing
  • Cardiac tissue damage
  • Elevated thresholds and/or loss of capture
  • Device malfunction or damage

Q: What do I need to know about the current debate around MRI and device safety in the literature?

A: Despite theoretical and actual risks of MR scanning to patients with cardiac devices, the safety debate continues.

  • Limited studies have documented safe procedures and no adverse events
  • Patient safety cannot be guaranteed by extrapolating findings from limited studies that reported no adverse events. Safety is proven only by more rigorous scientific testing and regulatory review.
  • Clinicians must carefully balance the potential benefits and risks to patients
  • No IPG/ICD is currently labeled for use in the MR environment.
  • All components of an implantable system need to be developed, tested, and proven safe and effective for current and evolving MRI technologies

Q: Why is MR safety in patients with implanted cardiac devices so difficult to achieve?

A: A staggering combination of variables affects the magnitude of risk for patients, including:

  • Type of imaging/MRI sequence
  • Patient and device position within MRI scanner
  • MRI scan duration
  • Strength of RF field
  • Target anatomy of scan
  • Pacemaker and lead materials and design
  • Length and anatomical orientation of pacing leads
  • Blood flow in lead-tip region
  • Patient factors/medical history

Q: Can my patient have a partial extremity MRI?

A: Because a pacing/sensing/ICD lead tip can heat regardless of anatomy being scanned, an MRI is not recommended for patients with implanted cardiac devices even for a partial extremity scan.

Q: Can my patient have an MRI if the implantable cardiac device is programmed off?

A: Even when a device is programmed off, electromagnetic interference (EMI) produced during the MRI has the potential to induce several hazardous effects impacting the normal operation of implantable pacemakers and defibrillators.

Q: Can my patient have an MR scan if the pacemaker generator has been removed but the lead(s) remains?

A: The effect of RF energy on the lead-tissue interface can be accentuated by the removal of the generator. The remaining lead may act like an antenna for RF energy, resulting in even more heating and tissue damage.

Pacemaker manufacturers typically recommend that the safest strategy is to either remove the entire implantable cardiac device system or utilize an alternative imaging modality.

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