Mode Switch Flashcards
What is the purpose of the Mode Switch feature?
To prevent ventricular tracking of fast atrial rates due to atrial arrhythmias
Does rate response work while the device as mode switched to an an atrial non-tracking mode?
Yes, DDIR mode will pace the ventricles up to the sensor-indicated rate
What are the two mode switch methods?
- AT/AF Onset
-> EnRythm, ICDs, advisa and future pacemakers - 4 of 7 with Blanked Flutter Search
-> Adapta/Versa pacemakers
How does the AT/AF Onset mode switch work?
The device will Mode Switch to Atrial non-tracking mode when:
- the AF counter = 3
-> each V-V interval with 2 or more atrial events in between adds 1
to the counter
AND
- the median of the last 12 A-A intervals is less then the detection interval
How does the 4 of 7 blanked flutter search mode switch feature work?
- Device will mode switch if 4 of the last 7 intervals are faster than the detection rate
How does the blanked flutter search mode switch feature work?
Detects Atrial Flutter:
- If 8 consecutive A-A intervals are less than 2x TAB and the atrial rate is greater than 1/2 the mode switch detect rate, the device will:
-> extends PVARP to 400ms for one cycle so the normally tracked P-
wave (AS) will be identified as an AR to try and uncover the
normally blanked P-wave (will show as AS)
- if an AR-AS pattern occurs before the next ventricular event, the device will mode switch
- process will be repeated every 90 seconds as long as the criteria above continues to be met
How often does the blanked flutter search mode switch feature extend PVARP in search of blanked P-waves?
Will extend PVARP every 90 seconds as long as the below persists:
-> pattern of 8 consecutive A-A intervals less than 2x TAB
AND
-> the atrial rate is greater than 1/2 mode switch detect rate
Which 2 timing intervals make up the Total Atrial Blanking (TAB) period?
SAV and PVAB
How long does the blanked flutter search feature extend PVARP to try and uncover blanked flutter waves?
400ms
