Introduction to MR Conditional Pacing
Programming Considerations
1-13
WARNING: Ensure that an external defibrillator and medical personnel skilled in cardio-
pulmonary resuscitation (CPR) are present during the MRI scan should the patient require
external rescue.
WARNING: MRI scanning after Explant status has been reached may lead to premature
battery depletion, a shortened device replacement window, or sudden loss of pacing. After
performing an MRI scan on a device that has reached Explant status, verify pulse generator
function and schedule device replacement.
WARNING: When the Time-out parameter is programmed to a value other than Off, the patient
must be out of the scanner before the time programmed elapses. Otherwise, the patient will no
longer meet Conditions of Use ("MRI Conditions of Use" on page 1-4).
Programming Considerations
WARNING: If the MRI Protection Time-out value of Off is combined with a Pacing Mode of Off,
the patient will not receive pacing until the pulse generator is programmed out of MRI Protection
Mode and back to normal operation. It is recommended to have the Programmer/Recorder/
Monitor (PRM) near the MRI room in case the patient develops the urgent need for pacing.
Patients with the following conditions may have increased risk of developing transient pacing-
dependence:
• A history of syncope related to bradyarrhythmia
• A history of syncope of unknown etiology
• Sinus pauses (Pause > 2 s), AV block permanently or intermittently
• At risk for intermittent AV block (for example, those with progressive AV block, or a history of
unexplained syncope)
• At risk for trifascicular block (alternating bundle branch block or PR interval > 200 ms with
LBBB or other bifascicular block)
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.
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.
Safety Mode
WARNING: Do not perform an MRI scan on a patient whose device has entered Safety Mode.
Safety Mode pacing is VVI unipolar, which, in the MRI environment, subjects the patient to
increased risk of arrhythmia induction, inappropriate pacing, inhibition of pacing, or irregular
intermittent capture or pacing.
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
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