BIOTRONIK Evia DR, Technical Manual

Page: 101 / 183

Evia Technical Manual 93
1. If VCC determines that capture has been maintained,
then the pulse amplitude remains at that current setting
and no action is required.
2. If VCC determines that non-capture (NC) occurred, then
a safety back-up pacing pulse is delivered at an
increased energy (same output voltage and pulse width
extended to 1.0 ms) within 130 ms after the non-
captured pacing pulse.
3. If a series of ventricular pacing pulses at varying AV
delays result in loss-of-capture, a Signal Analysis (SA)
and Automatic Threshold Search (ATM) are initiated to
determine the current pacing threshold.
4. The algorithm is designed to respond appropriately to
fusion beats. In order to discriminate non-capture from
fusion, a capture confirmation algorithm varies the AV
delay after detection of non-capture in the dual chamber
pacing modes. First, fusion is diminished by extending
the AV delay. If a second non-capture is detected, the
AV delay is returned to the programmed AV delay. If a
third consecutive non-capture is detected, loss of
capture is confirmed and a Signal Analysis and
Automatic Threshold Search are initiated. If the first
event was truly fusion, the extended AV delay could
allow intrinsic conduction. The AV delay will not return
to the normal programmed value until ventricular pacing
is required. In case the capture confirmation continues
to detect non-captures without detecting 3 consecutive
non-captures, the algorithm shortens the AV delay
(50 ms after an atrial paced event and 15 ms after an
atrial sensed event for up to 2 paced cycles) to confirm
the occurrence of non-capture. When VCC and CLS are
both enabled, the AV delay is extended after detection of
non-capture and then capture confirmation is temporarily
disabled while CLS performs an AV Hysteresis Scan.