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.
Gimbel
J Rod
JR
Park West Hospital, Knoxville, Tennessee, USA. gimbeljr@ix.netcom.com
D001145:Arrhythmias, Cardiac / Q000209:etiology* / Q000517:prevention & control*; D017147:Defibrillators, Implantable; D019544:Equipment Failure Analysis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000009:adverse effects* / Q000379:methods*; D009206:Myocardium / Q000473:pathology*; D010138:Pacemaker, Artificial; D018570:Risk Assessment; D012307:Risk Factors