Title: Magnetic Resonance Imaging of Implantable Cardiac Rhythm Devices at 3.0 Tesla
Background: A relaxation of
the prohibition of scanning cardiac rhythm device patients is underway,largely
because of the growing experience of safe scanning events at 1.5T. Magnetic
resonance imaging (MRI)
at 3T is becoming more common and may pose a different risk profile and outcome
of MRI of cardiac device patients.
Methods: No restrictions
were placed on pacemaker dependency, region scanned, device type, or
manufacturer.Sixteen scans at 3T were performed with an electrophysiologist
present on 14 patients with a variety
of devices from various manufacturers. An "MRI-S" strategy was used. Multimodal
monitoring was required.
Device interrogation was performed prior to, immediately after, and 1-3 months
after the MRI.For
nonpacemaker-dependent device patients, attempts were made to turn all device
features off (with OOO
programming the goal) conceptually rendering the device "invisible." In
pacemaker-dependent patients,the device was programmed to asynchronous mode at
highest output for the duration of the scan with
the goal of rendering the device conceptually "invulnerable" to MRI effects.
The specific absorption rate
(SAR) was limited to 2W/kg.
Results: All patients were
successfully scanned. No arrhythmias were noted. No significant change in the
programmed parameters, pacing thresholds, sensing, impedance, or battery
parameters was noted.The
insertable loop recorder (ILR) recorded prolonged artifactual asystole during
MRI. One patient noted chest
burning during the scan.
Conclusions: Device patients
may undergo carefully tailored 3T MRI scans when pre-MRI reprogramming of
the device occurs in conjunction with extensive monitoring, supervision, and
follow-up. (PACE 2008;
31:795-801)
