User Manual Part 2

PACING THERAPIES
NOISE RESPONSE
5-61
A retriggerable, 40-ms noise window exists within each refractory and
cross-chamber blanking period. The window is initiated by either a sensed
or paced event. Both the noise window and the refractory period must be
completed for each cardiac cycle in one chamber before the next sensed
event restarts the tim ing in the same chamber. Rec urre nt no ise activity may
cause the noise window to restart, extending the noise window and possibly
the effective refractory period or blanking period.
The Inhibit mode is intended for patients whose arrhythmias may be triggered by
asynchronous pacing. If Noise Response is programmed to an asynchronous
mode and the noise persists so that the noise window is extended longer
than the programmed pacing escape interval, the pulse generator paces
asynchronously at the programmed pacing rate until the noise ceases.
Refer to Figure 5-27 on page 5-61 and Figure 5-28 on page 5-61.
ECG
RV Sensing
RV Paced
event
RV Sensed
event
Noise window (40 ms)
RV Refractory:
sensed = nonprogrammable
paced = programmable
Figure 5-27. R efractory period s an d noise windows, RV
ECG
LV Sensing
LV Paced
event
LV Sensed
event
Noise window (40 ms)
LV Refractory
(programmable)
Figure 5-28. R efractory period s an d no ise w indow s, LV
If Noise Response is programmed to Inhibit, and the sensed noise extends the
noise window beyond the programmed paced or sensed interval, the pace
escape interval timing will reset and the pulse generator will not pace until
one escape interval after the noise ceases. The pulse generator will continue
to use a retriggerable noise window. In addition, a Dynamic Noise algorithm
is intended to automatically adjust the ma ximum se nsitivity to avoid noise
detection. This algorithm is active in all rate channels.
- DRAFT -