Special MRI-Compatible Leads
Two device manufacturers (Medtronic, St Jude Medical) developed special pacemaker systems to avoid thermical injuries due to induced electrical potentials under MRI. Their underlying active principles differ, however. For clinical practice this means that only leads and pacemaker aggregates from the same manufacturer should be implanted. The feasible combination of leads and devices from different manufacturers leads to a loss of MRI-compatibility in every case. Thus far, only specially designated pacemaker systems from Medtronic and St Jude Medical are licensed for unlimited MRI scans with a magnetic field intensity of up to 1.5 tesla. According to the manufacturer’s own information, the Biotronik devices marked as “Pro MRI” should also be combined only with Biotronik Pro-MRI leads (without special conduction algorithms), but they are not suitable for MRI scanning of the thorax or abdomen.
In spite of individual MRI scans in patients with pacemakers that remained uneventful, doctors should be warned against uncritically adopting this practice. I was asked to assess the complete failure of a defibrillator with resynchronization function (CRT-D) as a result of an accidental MRI scan of the head. Another serious criticism relates to one manufacturer’s practice of marketing ICD systems as MRT-compatible when the ICD leads were not actually specially developed for this purpose but were still marked “Pro-MRI.” Observations of individual MRI scans among ICD patients that are not backed up by relevant study results (a prerequisite for gaining licensing approval in the US) are not sufficient in order to classify these ICD systems as MRI-compatible as long as the trunk is excluded.
In general, all pacemaker or ICD patients should be informed individually about the MRI-compatibility of their system and potential limitations, and this might be documented in the pacemaker passport.
PD Dr. med. Bert Hansky
Klinik für Kardiologie, Klinikum Bielefeld
Conflict of interest statement
The author has held contracts as an adviser to Medtronic, Biotronik, and St Jude Medical. He has received conference delegate fees, travel expenses, and hotel expenses, as well as honoraria for preparing medical educational events from Medtronic, St Jude Medical, and Biotronik, and is in receipt of external funding from Medtronic, St Jude Medical, and Biotronik.
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