BIOTRONIK Evia HF - Page 33

Chapter 5 Programmable Parameters
Evia HF / HF-T Technical Manual
PAGE 25
Figure 9: ensitivity Screens for the Atrium and Ventricles
Automatic Sensitivity Control
The Automatic Sensitivity Control (ASC) feature automatically measures the peak amplitude
and adapts the sensing threshold automatically. After every sensed event, the function starts the
detection hold-off period and measures the highest peak of the amplitude. After this initial stage, the
sensitivity is initially reduced to 50% of the measured peak of the amplitude. At the end of the phase
duration, sensitivity is reduced to 25% of the measured peak of the amplitude and maintained until
detection of the next event. The sensitivity can never go below the minimum threshold shown below
in the sensed event summary.
Atrial and ventricular ASC function for sensed events are the same, except that the Detection Hold-off
and Step Duration periods use different values. This is shown in Figure 10.
Sensed Events Summary
Detection
Hold-off
Step
Duration
Minimum
Threshold
Atrium
101 ms 82 ms 0.2 mV
1
Right/Left Ventricle
121 ms 125 ms 2.0 mV
+/- Minimum
Threshold
Detection Hold-off Period (DHP)
Step
Duration
+/- Sensitivity Threshold
from the previous event
½ Peak
1/4 Peak
+/- Sensitivity Threshold
of the current event
Event
Detection
Atrium
DHP 100 ms
Step Duration 82 ms
Ventricle
DHP 121 ms
Step Duration 125 ms
Post Sense
Event
Figure 10: Automatic Sensitivity Control for Sensed Events
1 If the sensing is programmed unipolar, the minimum threshold will be 0.5 mV