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Lumax Technical Manual 115
2.9.9.3 PMT Detection and Termination
In addition to PMT prevention, Lumax contains a programmable
PMT detection and termination algorithm. The termination feature
will take action in case the prevention was not effective and a
PMT is detected. The PMT detection constantly monitors for the
presence of a PMT.
The Lumax PMT detection/termination algorithm consists of
suspicion, confirmation and termination components and is
described as follows.
Suspicion
A PMT is suspected when two criteria are met:
8 successive V pace-A sense (Vp-As) sequences have
occurred with a length shorter than the VA criterion. This
VA criterion is programmable between 250 and 500 ms.
The mean deviation of these 8 Vp-As intervals is less
than the Stability criterion parameter, defined as less than
25 ms.
Confirmation
When the suspicion criterion has been met, the Lumax slightly
modifies the AV delay interval (+ or - 50 ms) or the upper tracking
rate (+50ms) for one cardiac cycle. If the Vp-As interval remains
stable, a PMT is confirmed. Otherwise, a PMT is not confirmed
and the algorithm restarts. Once the PMT algorithm has
confirmed a PMT, the cycle is broken as follows:
Termination
Lumax extends TARP (Total Atrial Refractory Period) for one
cycle to equal the V-V interval + 50 ms. The Lumax 600/640 &
700/740 models extend the AV delay and the PVARP+ Ext.
2.9.10 VES Discrimination after Atrial Sensed
Events
Lumax ICD/CRT-D has a special timing interval (VES/As) – VES
discrimination after atrial sense events to identify ventricular
extrasystoles.