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Flashcards in CRT Timing cycles Deck (16):
1

What two conditions show good CRT response

Wide QRS (>150ms QRSd)

Left Bundle Branch Block

2

Do most contemporary CRT devices use RV or LV sensing

RV sensing normally

3

Which two PVAB cycles exist in CRT

PAVBRV = similar to dual chamber devices)

PAVBLV = To prevent inappropriate inhibition of LV pacing due to far-field atrial pace oversensing.

4

Define LVRP

LV-sensed event following an LV event (paced or sensed) will not affect or reset timing cycles

5

Why is LVRP important

Prevents oversensing of QRS or T waves following a ventricular event (paced or sensed), preventing inappropriate loss of CRT (seen more commonly with unipolar LV leads)

Long LVRP shortens the LV-sensing window that could affect timing cycles

6

Define LVPP

Prevents device from inadvertently delivering an LV output during the LV vulnerable period after an LV-sensed event, such as when an LV PVC occurs.

the device will still deliver RB pacing.

7

Why is LVPP important

Maximise CRT delivery while reducing the risk of inducing a ventricular tachyarrhythmia.

Programming a long LVPP will reduce the MTR and inhibit biventricular pacing at higher rates.

8

Define VV delay / LV Offset

Programming of different timing between the RV- and LV-paced events

Positive (RV first)
Negative (LV first)
Zero (simultaneous RV/LV)

9

5 occasions which cause loss of BiV

1. Rapid atrial or sinus rates above MTR
2. Short and dynamic PR intervals
3. PACs
4. Frequent PVCs
5. AF with ventricular response > LRL +/- SIR

10

Define negative hysteresis

Shortens AV delay to promote pacing

11

Define positive hysteresis

Extends AV delay to promote intrinsic

12

Define ventricular sensed response // BiV trigger

LV pacing immediately after intrinsic conduction / sensed event.

MUST OCCUR BETWEEN LRL AND MTR

13

BiV pacing will cease above MTR (TARP) TRUE/FALSE

TRUE

14

Once inhibited through tarp - what two components dictate when BiV pacing will return

PVARP + PR interval

15

In CRT systems what algorithm could further reduce BiV pacing due to PVC's

PVC response (as there is PVARP extension)

16

What can be done to improve BiV pacing in AF patients

Increase LRL
Enable ventricular sense response
Aggressive Medical therapy
AVN ablation