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81 year old female with dual chamber implanted for symptomatic sinus pauses
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Currently programmed AAIR-DDDR 60-130
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Underlying sinus rhythm 1st degree AV block
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Initial appearance of markers appears to be regular atrial rate at a rate of ~160bpm
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Close inspection of EGMs shows sinus rhythm with 1st degree and FFRW
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No true AF seen
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What is FFRW (Far Field R Wave)
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common issue where atrial lead sense a far field ventricular signal
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It is more likely to occur in the following scenarios
unipolar le-unipolar lead sensing -
atrial lead position close to the tricuspid valve
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very sensitive programming
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wide electrode spacing​​​​​​​​​​​​​​​
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Inappropriate mode switches
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records EGMs for episodes which may write over true arrhythmia episodes and also use extra battery
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inappropriate ventricular pacing inhibition due to being a non tracking mode
--may result in AV dysnchrony due to AV block
- may result in withholding required biventricular pacing
-may incorrectly bin tachycardias in an ICD (potential for A>V rather than 1:1 bin) -
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Adjust atrial sensitivity? -
Currently 0.30mV ( p wave sensing is 2mV) - risk of under-sensing true atrial rhythms
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Increase/adjust PBAB?
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Increase PVAB, so that AR falls into blanking period.
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MEDTRONIC DEVICES BEHAVE DIFFERENTLY
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Technically, in this example the FFRW is blanked (not in refractory).
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To eliminate the ABlank marker, PVAB can be adjusted to Partial + (described below) or Absolute which would behave similarly to other device brands
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-Partial: 30ms of absolute blanking followed by the rest of the PVAB (e.g., PVAB 150, (150-30 = 120)) influencing mode switch counters (but not timing or NCAP, PMT, etc)
-Partial+: 30ms of absolute blanking followed by the rest of the PVAB but at a reduced sensitivity (e.g., PVAB 150, (150-30 = 120)). Events in this window will still influence AMS and ICD discrimination algorithms.
-Absolute: standard PVAB programming​​​​​​​
