User Manual

Table Of Contents
110 Lumax Technical Manual
2.9.6 IOPT
DR versions only
The IOPT function serves to support the patient’s intrinsic rhythm
and avoid excessive ventricular pacing. This feature simply
activates all of the AV hysteresis parameters with a single
selection. Table 34
details the settings that are preset when
IOPT is turned ON:
Table 34 IOPT Parameters
Parameter IOPT
AV Hysteresis (max AV Delay) 400 ms
AV Scan Hysteresis 5
Repetitive AV Hysteresis 5
2.9.7 Upper Tracking Rate
DR and HF versions only
In the atrial tracking modes (DDDR, VDDR, DDD, and VDD)
ventricular pacing tracks atrial pace/sense events. The maximum
tracking rate (ventricular pacing rate) is limited by the Upper Rate
parameter.
The UTR response will automatically toggle between 2:1 and
WKB (Wenckebach) depending on the relative programmed
values for upper rate and atrial refractory period (AV Delay +
PVARP).
If the UTR is less than the maximum sensed atrial rate, defined
by the atrial refractory period (60,000/ARP), the WKB response is
utilized. Atrial rates exceeding the selected upper rate will result
in a Wenckebach-type pacing pattern. This is accomplished by
progressively lengthening the AV delay to keep the ventricular
pacing rate at the upper rate. Lengthening of the AV interval is
interrupted as soon as: 1) a P-wave falls within the atrial blanking
period and is not detected; or 2) a succeeding P-wave is detected
before the end of the AV delay previously started. In the second
case, the corresponding ventricular pacing pulse is suppressed. If
the atrial rate is just above the upper rate, a low degree (i.e. 6:5)
block results. Higher atrial rates result in higher degrees of AV
block until the intrinsic atrial cycle length violates the programmed
atrial refractory period causing a 2:1 or greater block.