Specifications

7 x 9 inches (178 mm x 229 mm)
Medtronic Confidential
Refer to the “Reference man.” category in doc#163256 for Printing
Instructions.
196407001 Rev A
■
Pacing occurs at the Lower Rate for all nonrate responsive modes and
VVIR.
Example of noise reversion in the VVIR mode pacing at the Lower Rate.
On the ECG, noise reversion may be difficult to distinguish from loss of
sensing, but Marker Channel recordings will show refractory sense markers
when noise reversion occurs.
NOTE: Atrial sensing during the PVARP, or refractory period following
an atrial paced or sensed event in the DDDR, DDD, DDIR, DDI, or VDD
modes does not restart the refractory period. An atrial refractory sensed
event however, will start a short blanking period of 50 to 100 ms depending
on the signal strength and duration of the atrial event.
Preventing Noise Sensing
Noise reversion may be caused by electromagnetic interference (EMI),
myopotentials, excessively high output settings, or low sensitivity settings.
When it has been identified, noise reversion usually can be reduced or
eliminated by one of the following actions:
■
Reprogram the Sensitivity to a less sensitive (higher numerical value)
setting.
■
Reprogram sensing to bipolar polarity (if available).
■
Reduce the amplitude and/or pulse width in the same or opposite
chamber.
■
Remove patient from EMI environment.
12-22 Understanding Pacemaker Operations
VVIR
V
Act.
P
R R R R P Act.
P
Parameters:
Lower Rate = 60 ppm (1000 ms)
Ventricular Refractory Period = 240 ms
Upper Activity Rate = 120 ppm (500 ms)
200 ms
Lower Rate
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