CRT Flashcards
What are the common causes for the loss of CRT pacing?
- atrial tachyarrhythmias (AT/AF)
- sub-optimal AV intervals (are too long)
- inadequate LV pacing outputs
- delayed LV activation
- LV/RV electrode proximity
- atrial or RV undersensing
What are Ventricular Sensing Episodes?
recorded episodes where ventricular pacing is inhibited by VS activity
Why does AT/AF cause loss of CRT pacing?
AT/AF drives the intrinsic ventricular rate which inhibits pacing
Which CRT algorithms ensure Ventricular pacing in the presence of Atrial Fibrillation?
- EffectivCRT during AF
- Conducted AF Response (CAFR)
What is the difference between EffectivCRT during AF and Conducted AF Response?
- EffectivCRT during AF paces according to the morphology of the pace on EGM, looks for a negative deflection
- Conducted AF Response paces according to the ventricular activation sequence (VS-VP, VP-VP, etc)
What is considered an effective VP by the device?
an initial negative deflection seen on the LV to RVcoil or LV to Can EGM
What LV to RV delay time is considered a suitable for CRT purposes?
80ms
Which feature determines the percentage of effective CRT pacing by evaluating the morphology of the paced event? of the LV pacing cathode to RVcoil EGM?
EffectivCRT Diagnostic
Which feature helps maintain CRT pacing in the presence of VP inhibition d/t ventricular sensing?
Ventricular Sense Response
On a CRT device, the Rate Histograms provide what information?
- conduction status
- % AS, AP, VP and VS
- % CRT pacing
- BiV and LV, effective and ineffective, VSR
- distribution of A/V rates prior to and since the last session
What are the 3 types of heart rate histograms?
- Atrial rate
- Ventricular rate
- Ventricular rate during AT/AF
Which EGM source vector does the EffectivCRT feature use to determine the percentage of effective pacing in CRT-P devices?
LV cathode to CAN
Which EGM source does the EffectivCRT feature use to determine the percentage of effective pacing in CRT-D devices?
LV cathode to RVcoil
How many beats and how often does the EffectivCRT diagnostic feature use to determine the percentage of effective pacing?
100 consecutive ventricular events every hr
What LVEF is considered an indication for a CRT device?
LVEF ≤ 35%