Medtronic
Summary
Onset
Stability
PR logic
Wavelet
Onset
Onset looks at a rolling average of the most recent 4 ventricular intervals and compares to the average of the preceding 4 intervals.
If the % change is less than the programmed onset %, detection will be withheld.
Stability
The feature begins on the 3rd consecutive VT event
The interval is compared to each of the previous 3 VV intevals
Classified as unstable unstable if the difference between the current interval and any of the 3 previous intervals is greater than the programmed Stability interval
When in the VT zone (only), an unstable event is marked as Vs and the tachy counter resets to zero.
PR logic
3 brackets (Specificities of algorithm function n/a)
AF/Afl
•To determine whether atrial flutter with n:1 conduction is present, the defibrillator looks for an n:1 ratio between atrial and ventricular rhythm.
Sinus tach
•when there is sensed 1:1 atrial to ventricular conduction of rhythms that exhibit a gradual increase in rate into the detection zone and a similar PR interval to normal antegrade conduction.
Other 1:1 SVTs
•1:1 SVT in which there are consistent, near‐simultaneous depolarizations of the chambers (AVNRT/JTs)
Wavelet
A baseline template is collected either manually or automatically when the patient is in sinus rhythm.
If >2/8 QRS complexes match the stored template, therapies are withheld
the ventricular rhythm is continuously evaluated there is a morphology change (<3/8 match) or the fast ventricular rate ends
