MRI Scan Procedure Protocol
MRI Protection Mode General Information
2-3
• Pacing mode options include asynchronous pacing or no pacing (DOO, AOO, VOO, or Off).
Off should only be used if the patient is judged to be clinically capable of receiving no pacing
during the time the pulse generator will be in MRI Protection Mode, including during the scan.
The programmed pacing mode prior to entry into MRI Protection Mode determines the default
MRI Protection pacing mode. For example, if MRI Protection Mode is entered from DDD(R),
the pacing mode will be DOO. Any of the other pacing mode options may then be selected.
WARNING: The Programmer/Recorder/Monitor (PRM) is MR Unsafe and must remain
outside the MRI site Zone III (and higher) as defined by the American College of Radiology
Guidance Document for Safe MR Practices
1
. Under no circumstances should the PRM be
brought into the MRI scanner room, the control room, or the MRI site Zone III or IV areas.
WARNING: If the pulse generator enters Safety Mode from MRI Protection Mode, backup
pacing will not occur in the following scenarios:
– if a functional bipolar ventricular pacing lead is not present
– if the Pacing Mode under MRI Protection Mode settings is programmed to Off; the pulse
generator will continue permanently with the Pacing Mode programmed to Off, and the
patient will not receive pacing therapy until the pulse generator is replaced
• The Lower Rate Limit is nominally set to 20 min
-1
above the starting LRL, and is
programmable in normal increments. For both the nominal setting based on the LRL and the
programmable setting, the maximum value is 100 min
-1
.
• Atrial pulse amplitude and ventricular pulse amplitude are nominally set to 5.0 V and are
programmable in normal increments between 2.0 V and 5.0 V.
WARNING: Use caution when programming the MRI Protection Mode pacing amplitude for
pacing-dependent patients who have high pacing thresholds (> 2.0 V). Programming pacing
amplitude below 5.0 V is provided as an option in case of extracardiac stimulation (for
example, diaphragmatic stimulation for RV pacing). If pacing amplitude is programmed below
5.0 V, an appropriate safety margin (2X the pacing threshold + 1.0 V) should be maintained.
An inadequate safety margin may result in loss of capture.
• AV Delay is fixed at 100 ms
• Pulse width is fixed at 1.0 ms for both chambers
• A Time-out feature is nominally set to 24 hours, with programmable values of Off, 12, 24, and
48 hours
WARNING: Exit MRI Protection Mode after MRI scanning is completed. If the MRI
Protection Time-out value of Off is selected, the pulse generator will remain permanently in
the MRI Protection Mode until it is programmed otherwise. Prolonged use of the MRI
Protection Mode (such as may occur when the Time-out feature is programmed to Off) may
increase the rate of battery depletion. In addition, prolonged exposure of a patient to the XOO
mode chosen may be deleterious to the patient’s health.
NOTE: Twenty-four hours in MRI Protection Mode (with pacing on) reduces pulse
generator longevity by approximately 5 days.
CAUTION: The physician choosing MRI Protection Mode parameter values will need to
exercise professional judgment to determine an individual patient’s ability to tolerate the
pacing parameters required for MR Conditional scanning, in conjunction with the physical
conditions required during a scan (for example, prolonged time in a supine position).
1. Kanal E, et al., American Journal of Roentgenology 188:1447-74, 2007.
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