CRT

Question 1

What are the common causes for the loss of CRT pacing?

Answer 1

• 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

Question 2

What are Ventricular Sensing Episodes?

Answer 2

recorded episodes where ventricular pacing is inhibited by VS activity

Question 3

Why does AT/AF cause loss of CRT pacing?

Answer 3

AT/AF drives the intrinsic ventricular rate which inhibits pacing

Question 4

Which CRT algorithms ensure Ventricular pacing in the presence of Atrial Fibrillation?

Answer 4

• EffectivCRT during AF

- Conducted AF Response (CAFR)

Question 5

What is the difference between EffectivCRT during AF and Conducted AF Response?

Answer 5

• 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)

Question 6

What is considered an effective VP by the device?

Answer 6

an initial negative deflection seen on the LV to RVcoil or LV to Can EGM

Question 7

What LV to RV delay time is considered a suitable for CRT purposes?

Answer 7

80ms

Question 8

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?

Answer 8

EffectivCRT Diagnostic

Question 9

Which feature helps maintain CRT pacing in the presence of VP inhibition d/t ventricular sensing?

Answer 9

Ventricular Sense Response

Question 10

On a CRT device, the Rate Histograms provide what information?

Answer 10

• 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

Question 11

What are the 3 types of heart rate histograms?

Answer 11

• Atrial rate
• Ventricular rate
• Ventricular rate during AT/AF

Question 12

Which EGM source vector does the EffectivCRT feature use to determine the percentage of effective pacing in CRT-P devices?

Answer 12

LV cathode to CAN

Question 13

Which EGM source does the EffectivCRT feature use to determine the percentage of effective pacing in CRT-D devices?

Answer 13

LV cathode to RVcoil

Question 14

How many beats and how often does the EffectivCRT diagnostic feature use to determine the percentage of effective pacing?

Answer 14

100 consecutive ventricular events every hr

Question 15

What LVEF is considered an indication for a CRT device?

Answer 15

LVEF ≤ 35%

Question 16

What NYHA HF classification(s) is considered an indication for a CRT device?

Answer 16

Class III and IV

Question 17

What QRS cycle length is considered an indication for a CRT device?

Answer 17

120ms ≤ QRS