There is no specific mode per se to reduce the percentage of unnecessary right ventricular pacing in Abbott pacemakers.
- the VIP algorithm corresponds to an AV delay hysteresis
- the AV delay is prolonged over a limited number of intervals to promote the return of intrinsic conduction
- at the end of the prolonged AV period, if no ventricular event has occurred, ventricular pacing is delivered
VIP is nominally programmed OFF.
Three parameters are programmable in the VIP algorithm:
- VIP Extension corresponding to the extension of the AV delay that is applied to the programmed AV delay: Off, 50, 75, 100, 125, 150, 160, 170, 180, 190 and 200 ms
- Search interval corresponding to the time interval between each intrinsic conduction search: 30 seconds, 1, 3, 5, 10 or 30 minutes
- Search cycles corresponding to the number of consecutive cycles with prolonged AV delay during which the search for intrinsic conduction occurs: 1, 2 or 3 cycles
The AV delay cannot be longer than 450 ms.
VIP feature programmability
Activation and deactivation of the VIP algorithm
When programmed ON, the algorithm is activated in 2 conditions:
- one intrinsic R-wave is sensed during a search interval
- 3 consecutive sensed R-waves occur outside a search interval (whatever the number of programmed Search Cycles)
The algorithm is deactivated when:
- the number of consecutive paced ventricular cycles is equal to the programmed number of Search Cycles (for example, 2 consecutive AP/VP or AS/VP cycles with Search cycles programmed at 2)
VIP suspends operation:
- when atrial intrinsic rate or sensor indicated-rate is ≥ 110 bpm
- during a capture or sense test
- when mode-switching occurs
Example 1: the device extends the AV Delay by 160 ms searching for R-waves for up to 3 cycles. Intrinsic ventricular activation and the AV delay remains at the lengthened value.
Example 2: the device extends the AV Delay by 160 ms searching for R-waves for up to 3 cycles. No R-waves found within 3 cycles; the AV Delay returns to the programmed value.
Example 3: the VIP is activated following 3 R-waves detected outside a search interval. The VIP annotation appears after detection of 3 R-waves.
The VIP is deactivated after 3 consecutive AP-VP cycles with prolonged AV delay (344 ms); the AV delay remains extended with ventricular pacing for the number of programmed Cycle Count, 3 in this example, before it returns to the programmed AV delay.
- heart rate histograms evaluate the percent of VP
- AV conduction counts determine the amount of VS