User's Manual

53
Pacing and Sensing Functions
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Description
— The device measures with a constant, maximum pacing
amplitude for a duration of 5 cycles. The AV delay is shortened to
50 ms after pace and to 15 ms after sense.
— After another 5 cycles, a second pulse is delivered with the same
amplitude 100 ms after the effective pace. This pace reaches
refractory tissue and thus does not evoke a stimulus response.
This makes it possible to determine the sole polarization
artifacts of the lead.
— The average signal from the 5 measurements is used to compare
the effectiveness of the pacing pulse (signal morphology) and to
classify it as effective or ineffective.
— If the signal quality is classified as insufficient, then the
pacemaker temporarily and automatically switches to safety
pacing until a successful measurement can be conducted.
— If insufficient signal quality is measured repeatedly, then the
function is deactivated and the pacemaker switches to
permanent safety pacing.
Automatic Pacing Threshold Search
Purpose
The pacing threshold search function enables the pacing threshold with
the resulting stimulus to be automatically determined.
Prerequisite
Only after the signal quality has been successfully checked can the
pacing threshold search and amplitude adjustment functions be
executed.
Description
The threshold is determined as follows:
— After successful verification of the signal quality, the pacing
amplitude is incrementally decreased with every second pace.
The AV delay is shortened to 50 ms after pace and to 15 ms
after sense.