CRT Pacing

Question 1

What components lead to dyssynchrony?

Answer 1

Delayed lateral wall contraction
Disorganized ventricular contraction
Reduced active filling
Paradoxical septal wall motion

Question 2

What are the goals of CRT?

Answer 2

Organize ventricular activation sequence
Coordinate septal and free wall contraction
Improve cardiac efficiency

Question 3

What factors may contribute to patient’s response to CRT?

Answer 3

% of CRT capture
Lead positioning
AV delay
V-V interval
Diastolic function
Mitral regurgitation
Scar location/burden
Advanced HF
Multipoint stimulation

Question 4

What is the optimal location for LV pacing?

Answer 4

LV free wall, midway between base and apex

Question 5

What are the possible branches available from the CS for most patients?

Answer 5

Postero-lateral vein, lateral branches of middle cardiac vein, lateral branches of the anterior intraventricular vein

Question 6

The ideal LV pacing location produces what kind of morphology?

Answer 6

R wave in V1 with RBBB morphology, negative lead I

Question 7

What are some challenges to LV lead placement?

Answer 7

Stenotic or occluded thoracic venous system
Difficult CS access
Tortuous or stenotic venous branches
Small venous branches
Right-sided implants
Persistent LSVC

Question 8

What are the most common reasons for failed LV lead implants?

Answer 8

Inability to access the CS ostium
Inability to advance the lead into a target branch
Acute lead dislodgement or instability

Question 9

CRT pacing is LOST when….?

Answer 9

Intrinsic ventricular activation wins out over biventricular pacing

Question 10

What factors may cause ventricular activation to win out over biventricular pacing?

Answer 10

Atrial tachyarrhythmias
Suboptimal AV intervals
Inadequate LV pacing output
Delayed activation
LV/RV electrode proximity
Undersensing

Question 11

What is the EffectiveCRT algorithm?

Answer 11

Adjusts pacing rate based on the morphology of the LV electrogram following BiV or LV only pacing.

Question 12

How does BiV Trigger and Ventricular Rate Regulation (VRR) algorithms help to increase CRT pacing during atrial arrhythmias?

Answer 12

Reduces V-V cycle length variability during partially conducted atrial arrhythmias by modestly increasing the pacing rate

Question 12

What is Adaptive CRT algorithm?

Answer 12

dynamic, physiologic pacing algorithm that enhances CRT by adjusting parameters automatically with changes in activity level and intrinsic conduction status

Question 13

How does Adaptive CRT work?

Answer 13

Automatically updates intrinsic AV delays every 5 minutes and then paces at least 50ms before QRS onset

Question 14

In adaptive CRT, when does the device pace only in the LV?

Answer 14

When intrinsic AV delays are normal

Question 15

In adaptive CRT, when does the device pace RV and LV?

Answer 15

When intrinsic AV delays are prolonged

Question 16

How does ventricular sense response (VSR) work to improve BiV pacing %?

Answer 16

Triggering an immediate BiV pace when a ventricular event is sensed.

Question 17

PMT algorithms are inappropriately triggered ____% of the time?

Answer 17

46% (algorithms should be turned off in most CRT patients).

Question 18

Describe the algorithm for Non-competitive atrial pacing (MDT)/atrial upper rate (BIO)

Answer 18

an A pace is delayed 250-300ms from the detection of an A-refractory sensed event to give the atrium a chance to repolarize before pacing. Prevents CAP and triggering of atrial arrhythmias.

Question 19

How does Atrial Tracking Recovery maintain CRT pacing?

Answer 19

maintains AV synchrony by ensuring continuous CRT pacing when lost due to PVCs or fast conducted atrial rhythms

Question 20

Pacemaker definition of PVC

Answer 20

Two consecutive sensed V events without an atrial event in between

Question 21

What is the preferred pacing method for CRT patients?

Answer 21

DDD or VDD, rate response should be avoided if the chronotropic response is preserved