User Manual Part 2

5-30
PACING THERAPIES
RATE ENHANCEMENTS
Ventricular synchronization window: previous R–R interval ± Rate
Smoothing value
Atrial synchronization window: (previous R–R interval ± Rate Smoothing
value) - AV Delay
The following example explains how these w indows are calculated (Figure 5-13
on page 5-30):
• Previous R–R int erval = 800 ms
• AV Delay = 150 ms
• Rate Smoothing Up = 9%
• Rate Smoothing Down = 6%
Thewindowswouldbecalculatedasfollows:
Ventricular Synchronization Window = 800 - 9% to 800 + 6% =
800 ms - 72 ms to 800 ms + 48 ms = 728 ms to 848 ms
Atrial Synchronization Window = Ventricular Synchronization Window - AV
Delay = 728 ms - 150 ms to 848 ms - 150 ms = 578 ms to 698 ms
The tim ing for both windows is initiated a t the end of every ventricular event
(R-R interval).
If paced activity is t o occur, it must occur within the appropriate synchronization
window.
Paced AV Delay (150 ms)
A
trial
Event
Atrial
Event
R-R Interval (800 ms)
RV Event
Atrial Smoothing Window
578 ms 650 ms 698 ms
RV Smoothing Window
728 ms 800 ms 848 msRV Event
Figure 5-13. Rate smoothing synchronization window
It is important to ascertain the patient’s physiologic cycle-to-cycle variation
and program the Rate Smoothing parameter to a value that protects against
pathologic interval changes, yet allows physiologic interval changes in response
to inc reas es in activity or exercise.
- DRAFT -