User Manual

Table Of Contents
82 Lumax Technical Manual
Upper Threshold (A, RV & LV) - This feature allows the user to
change the upper sensing threshold level (UT in Figure 8
) from
the nominal value of 50% of the sensed R-wave/P-wave
amplitude to either 75% or 87.5% of the R-wave/P-wave value.
This feature is used in the ventricle for example to eliminate
oversensing of large T-waves. This is not applicable to the Lumax
600/640 and 700/740 models.
Hold of Upper Threshold (RV & LV) - This parameter
determines when the sensing decrement begins after an event
(small step-down on the 50% threshold before LT in the figure
above). This parameter “holds” the threshold at a constant value
(UT in Figure 8
) for the programmed time. Maximum Hold Time is
programmable from 100 to 600 ms in Lumax 300/340 & 500/540
and 110 to 500 ms in the Lumax 600/640 & 700/740 models (T-
Wave discrimination period). Additionally, the Lumax 600/640 &
700/740 models are separately programmable between the
paced and sensed signals.
Lower Threshold (A, RV & LV)- This feature allows the user to
change the lower sensing threshold (labeled LT in Figure 8
) from
the default value of 25% of the sensed R-wave/P-wave amplitude
to either 12.5 or 50% of the measured R-wave/P-wave value. This
is not applicable to the Lumax 600/640 and 700/740 models. This
feature is also used in the ventricles to alleviate T-wave
oversensing and/or undersensing of small amplitude events (e.g.,
fine VF).
Blank after atrial pacing (RV) - This feature is used to eliminate
sensing of artifacts after atrial paced events. Blank Post atrial
Pace in the RV is programmable from 50 to 100 ms. For the left
ventricle, this parameter is equal to the safety window time
(100 ms).
VES Discrimination after As - This feature is used to correctly
identify and classify ventricular extrasystoles (VES). With each
atrial sensed event (also with Ars falling into PVARP) a special
timing interval is started for the ventricle, if the subsequent
ventricular event does not fall within the AV delay or the
programmed VES discrimination interval, it is classified as a VES.
LV T-wave Protection - Used to eliminate unintended pacing in
the vulnerable period of the left ventricle. This feature is only used
when left ventricular sensing is active. HF versions only.