Chapter 5 Programmable Parameters
Evia HF / HF-T Technical Manual
PAGE 57
• Time of day — The time of day allows the user to program a specific time of day when the Active
Threshold Monitoring test is performed. By default, the time is set to 2:00 A.M. This may be
changed if the patient is sensitive to the pacing test occurring at night and may be set to a time
when the patient is awake.
5.15 Ventricular Pace Suppression (Vp-Suppression)
5.15.1 Feature Description
Vp-Suppression is a feature that is available in DDD(R)-ADI(R) mode and is not available with
biventricular pacing. This feature promotes the intrinsic AV conduction by only pacing the ventricle
when intrinsic conduction becomes unstable or disappears. Depending on the presence or absence of
AV conduction, the feature is implemented either in the ventricular pacing suppression state ADI(R),
which promotes the intrinsic conduction, or in the DDD(R) ventricular pacing state Vp DDD(R), which
provides ventricular pacing. Automatic switching capabilities between those two states promote
the intrinsic conduction as much as possible without harming the patient. Scheduled Vs searching
tests look for intrinsic conduction using an extended AV delay of 450ms. In order to protect the
patient from high ventricular rates, the feature provides Mode Switching independent of the present
state of the algorithm. The feature itself becomes suspended for the time of Mode Switching. When
Vp-Suppression becomes enabled, the device starts in the Vp-DDD(R) state and looks for intrinsic
conduction by starting a Vs-searching. Following any suspension (e.g. Mode Switch), the Vp
Suppression feature will resume in Vp-DDD(R) state. The feature provides user programmability with
respect to the switching criteria in order to support intrinsic conduction.
5.15.2 Programmability
The Vp-Suppression feature will provide the following programmability as shown in Table 16.
Parameter Range Default
Vp-Suppression feature On, Off Off
VpS to DDD(R) x/8 cycles without VS 1,2,3,4 3
DDD(R) to VpS x consecutive Vs 1,2,3,4,5,6,7,8 6
Table 16: Vp-Suppression Parameters
Vp-Suppression is available only if DDD(R)-ADI(R) mode is selected.
5.15.3 How the Vp Suppression Algorithm Works
Once the algorithm is programmed ON and the wand is removed, a Vs Continuity test is performed with
the rst intrinsic ventricular event or after 30 seconds of ventricular pacing whichever comes rst.
A Continuity test is used to determine whether a stable intrinsic ventricular rhythm is present. During
the test, the AV Delay is extended to 450 ms for eight cycles. During those eight cycles, the device
looks to determine if six out of eight Vs events occur. If six Vs events occur, Vp Suppression is
activated. If six events do not occur, the device will return to the programmed AV Delay and a new
search will be performed at a specic time interval. More detail on search intervals will be found in the
following section, Intelligent Search.
While the device is in the ADI(R) mode, pacing is available only in the atrium. The AV Delay is set to
450 ms in the background without delivering a pace if the AV Delay timer expires.
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