ICD EGM & Troubleshooting Flashcards
troubleshooting
How to prevent Wenkebach & 2:1 (URB)
MS - to prevent dropped beats that can cause symptoms
Short AV delay, PVARP or RAAV delay to allow for 1:1 tracking for longer at higher rates
Trouble shooting - Oversensing
Crosstalk
Ap event sensed on ventricular lead/EGM = inappropriately inhibits pacing
Make sure VSP is ON (Vp on top of Vs to prevent dropped beat that can cause symptoms)
Reduce V sensitivity
Decrease A outputs (if possible)
Increase PAVB - blank for longer on V lead after atrial event
What are the disadvantages of programming PAVB too long?
Undersensing of V event if Vs falls into PAVB
Troubleshooting - oversensing
FFRWOS
A channel seeing V events
Programme Partial + On
Decrease Atrial sensitivity (if P wave is big enough for still 2x safety margin)
Troubleshooting - Oversensing
TWOS
Events of V lead being inappropriately sensed (double counting).
- T wave oversensing algorithm
- If Medtronic ICD, programme to Intergrated bipolar
- Increase post sensing blanking period
- Decrease V sensivity (last resort in ICDs due to risk of under sensing ventricular events)
- replace lead if R low R wave amplitude and reprogramming compromises sensing of VF
How does R wave oversensing occur? Troubelshooting?
Duration of sensed electrogram exceeds the short V blanking period in ICDs - sensing broad complex QRS
- Increase V blanking period
- decrease V sensitivity
- increase interval detection count
Troubleshooting - oversensing
P wave
V lead is close to tricuspid valve and can pick up atrial signals (Can occur in kids with small RA or adults with integrated bipolar)
- After implant = RV lead dislodgement –> reposition lead
- reduce V sensitivity
- revise lead if V sensing of V event is comprimised
- Force A pacing by introducing or increase V blanking period after each atrial event (Blank sensed A and force pacing; Ap also shorts V cycle length preventing dynamic V sensing to reach minimal value)
Troubleshooting - Atrial non capture
Check thresholds
Increase atrial outputs
Trouble shooting - atrial undersensing
Check lead integrity
Increase atrial sensitivity
Why is FFRWOS bad?
If AR markers instead of AB then can cause inappropriate MS which can be symptomatic for the patient
Troubleshooting - FFRWOS
Decrease atrial sensitivity (atrial signals should be greater than FF)
Increase PVAB (so FF signals fall into blanking zone and don’t count to MS)
Troubleshooting - V non capture
Check lead integrity
Increase V outputs
Post implant acute drop in R/P wave could mean?
Lead dislodgement
Troubleshooting - atrial undersensing
Increase atrial sensitivity
Case:
Patient is 100% Vp is having high lead thresholds with drops in sensing. Aside from obvious interrogation and troubleshooting
EGM
What is happening in the EGM below?
Lead dislodgement
EGM
What is happening in the EGM below?
Lead dislodgement
RV lead moved to tricuspid annulus
Perform x-ray & reposition lead
Case study 1
What would be the next course of action for this non-dependant CRT patient?
Check lead trends
- atrial lead capped or plugged
(Medtronic tip: if capped and programming dual to VVI, programmed atrial outputs as low as possible cause somehow it will affect battery longevity)
Case study 1
In the image are there any problems with the lead trends?
RV impedance has increased and RV threshold has also jumped in January.
(Lead trends for LV looked fine)
Case study 1
What does the presenting EGM show?
Programmed BIVP @ 75bpm
There is pacing but there is no T waves or QRS so it is not capturing.
D - asystole
(pacing saturation: pacing single is saturating the amplifier - square it on complex on LECG)
What is this showing? What has happened?
No shocks in shock column means
(tip: dots on the bottom line show trigger pacing/conducted AF response)
In what circumstance would wavelet be programmed Off?
If patient is 100% VP.
In such patients the only tachyarrhythmia they may have is AVNRT
Atrial lead insulation failure causes noise in ICD-DR. What kind of troubleshooting can be done, in the first instance?
Provocations to confirm noise
Turn of atrial discriminators
Turn of atrial lead (I.e. programme VVI)
High rate NS episode in VF zone due to TWOS. What trouble shooting should be done in the first instance?
- Provocations in all sensing configurations
- Perform exercise testing - assess oversensing & programme as appropriate
- Extend VF detection interval if appropriate
Noise secondary to conductor failure is likely to be seen on which IEGM?
Near field
A fractured wire with no contact will lead to what?
Undersensing
A fractured wire with intermittent contact will lead to what?
Oversensing
A shock impedance >125 ohms suggests what?
Lead fracture or lead connector issue
If combined count is being used too often, what troubleshooting can be performed?
Increasing VF zone to allow for tachy to fall into VT zone, for fast detection.
