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
Programmable parameters
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
Examples
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.
Evaluating diagnostics
- heart rate histograms evaluate the percent of VP
- AV conduction counts determine the amount of VS
