User Manual Part 1

3-28
TACHYARRHYTHMIA DETECTION
VENTRICULAR DETECTION
400 380 420 390 410 400 360 440 410 390
580 620 600 640 560 600 580 600 620
1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8
Number of
Intervals
Intervals
in ms
Third fast interval (of the 8 out
of 10 that satisfy the detection
window)
Start Duration.
Evaluate Onset.
Compute the sum of 10 most recent ventricular
intervals. Average = 400 ms = 150 min
-1
(bpm).
Duration expired.
Onset is gradual.
Analyze V Rate > A Rate.
Deliver therapy because V > A.
Average ventricular rate (150 min
-1
[bpm]) is greater than average
atrial rate (100 min
-1
[bpm]) by at
least 10 bpm, so delivery therapy.
Compute the sum of the atrial intervals.
Average = 600 ms = 100 min
-1
(bpm).
Number of Intervals
Intervals in
ms
A
trium
Ventricle
VT detected
ATP therapy
Figure 3-17. V Rate > A Rate analysis
V Rate > A Rate can be programmed to bypass inhibitors (Vector Timing and
Correlation, AFib Rate Thres ho ld , Stability, an d/or Onse t) and initia te therapy in
the event that the ventricular rate is faster than the atrial rate.
NOTE: Refer to "Use of Atrial Information" on page 3-5 for additional
information about device performance when the atrial lead is programmed to
Off.
NOTE: In a Rhythm ID configuration, the evaluation of V Rate > A Rate is
linked to the AFib Ra te Threshold. If Atrial Tachyarrhy th mia Dis crimin ation is
programmed to Off, the AFib Rate Threshold and V Rate > A Rate detection
enhancements are not evaluated.
AFib Rate Threshold
AFib Rate Threshold analysis identifies AF by comparing the atrial rate to the
programmed AFib Rate Threshold.
AFib Rate Threshold cannot be enabled without also enabling the Stability
detection enhancement. The device analyzes both parameters to determine
whether to withhold or deliver therapy.
If the intrinsic atrial rate is greater than the AFib R ate Threshold and the
ventricular rhythm is classified as unstable, the ventricular rhythm is declared
to be due to AF.
- DRAFT -