User Manual

108 Lumax Technical Manual
The AV Delay feature includes an AV Delay shortening option
(Sense Compensation) for dual chamber pacing modes. When
enabled, the AV Delay is shortened by the programmed value
(-5 to -60 ms in Lumax 300/340 & 500/540 models and up to
-120 ms in Lumax 600/640 & 700/740 models) from the
programmed AV Delay after an intrinsic atrial sensed event.
The Dynamic AV Delay is intended to mimic physiologic-
shortening of the AV Delay with increasing heart rate. It also
serves for automatic prevention and termination of “circus
movement” pacemaker mediated tachycardia and for prevention
of reentrant supraventricular tachycardias. Dynamic AV Delay is
available with the Lumax DR-T and HF-T ICDs/CRT-Ds.
2.9.5.1 Positive AV Hysteresis
Positive AV Hysteresis allows a user-programmable change in
AV
delay that is designed to encourage normal conduction of
intrinsic signals from the atrium into the ventricles. With Positive
AV hysteresis enabled, the AV delay is extended by a defined
time value after sensing a ventricular event (10 … (10) …150 ms)
in the Lumax 300/340 & 500/540 models and (70, 110, 150, 200
ms) in the Lumax 600/640 & 700/740 models. The long AV
interval is used as long as intrinsic ventricular activity is detected.
The programmed short AV delay interval resumes after a
ventricular paced event.
2.9.5.2 AV Repetitive Hysteresis
With AV Repetitive Hysteresis, the AV delay is
extended by a
defined hysteresis value after sensing an intrinsic ventricular
event. When a ventricular paced event occurs, a long AV delay is
used for the programmed number of cycles. (OFF, 1 … 10) in
Lumax 300/340 & 500/540 models and 5 fixed cycles with scan
AV hysteresis in the Lumax 600/640 & 700/740 models. If an
intrinsic rhythm occurs during one of the repetitive cycles, the
long duration AV delay interval remains in effect. If an intrinsic
rhythm does not occur during the repetitive cycles, the original AV
delay interval resumes.