Specifications

7 x 9 inches (178 mm x 229 mm)
Medtronic Confidential
Refer to the “Reference man.” category in doc#163256 for Printing
Instructions.
196407001 Rev A
PMT Intervention
Overview
A pacemaker-mediated tachycardia may occur when retrograde P-waves
(due to a loss of AV synchrony) are sensed and tracked in an atrial tracking
mode. Pacemaker-Mediated Tachycardia (PMT) Intervention provides an
automatic way for the pacemaker to detect and interrupt pacemaker-defined
PMTs. This programmable ON/OFF feature is available in the DDDR,
DDD, and VDD modes.
WARNING: Certain PMTs may require intervention such as pacemaker
reprogramming, magnet application, drug therapy, or lead evaluation.
How the Pacemaker Defines PMT
The pacemaker assumes that a PMT may be present when it detects a ninth
ventricular pace following eight consecutive VA intervals that meet all of
the following conditions:
■
duration less than 400 ms
■
start with a ventricular paced event
■
end with an atrial sensed event
PMT Monitoring and Intervention
When PMT Intervention is programmed ON, the pacemaker monitors for
PMT episodes. When a pacemaker-defined PMT is detected, the pacemaker
intervenes, forcing a 400 ms PVARP after the ninth paced ventricular
event. If a PMT is indeed in progress, the extended PVARP ensures that the
next atrial sensed event within 400 ms will be refractory. By interrupting
atrial tracking for one cycle, the PMT may be stopped.
NOTE: A sinus tachycardia could cause a feature intervention, resulting in
a single P-wave falling in the PVARP and therefore not being tracked by
the pacemaker.
Automatic 90-Second Suspension
After an intervention, PMT Intervention is automatically suspended for 90
seconds. This prevents unnecessary intervention in the presence of fast
intrinsic atrial rates.
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