User Manual Part 1

TACHYARRHYTHMIA DETECTION
VENTRICULAR DETECTION
3-27
generator calculates a Feature Correlation Coefficient and makes the following
therapy decisions based on the calculation:
• If at least 3 out of 10 beats are correlated, the rhythm is classified as SVT
• If fewer than 3 out of 10 beats a re correlated, the rhythm is classified as VT
Rhythm ID makes its decision to treat or inhibit therapy at the end of Duration. If
the decisio n is made to inhibit therapy, Rhyth m ID (including Vector Timing and
Correlation, V Rate > A Rate, AFib Rate Threshold, and S tability) continues
to be recalculated beat-by-beat throughout SRD.
V Rate > A Rate
The V Rate > A Rate (ventricular rate greater than atrial rate) enhancement
compares the atrial and ventricular rates to classify the type of fast ventricular
rhythm. When the ventricular rate is greater than the atrial rate, therapy will
be initiated regardless of the analysis of the other programmed detection
enhancements.
Analysis is made by comparing the average rate of the last 10 ventricular
intervals prior to the end of Duration to the ave rage rate of the last 10 atrial
intervals prior to the end of Duration (Figure 3-17 on page 3-28). If fewer than
10 atrial intervals are available, those intervals will be used to calculate the
average atrial rate. This analysis is performed using the following criteria:
• If the average ventricular rate is greater than the average atrial rate by at
least 10 bpm, the ventricular rate is declared to be faster than the atrial
rate (indicated as True on the Episode Detail Report), and therapy will
be initiate d.
• If the average ventricular rate is not greater than the average atrial rate by
at least 10 bpm (indicated as False on the Episode Detail Report), therapy
may continue to be inhibited. The Episode Detail report will indicate the
measured value even though the parameter may be programmed to Off.
If therapy is inhibited, the V Rate > A Rate analysis continues until either the
ventricular rate is greater than the atrial rate or other enhancements indicate
therapy treatment, at which time therapy will be initiated.
NOTE: V Rate > A Rate is not evaluated during redetection following ATP
therapy.
- DRAFT -