CRT Pacing Flashcards
What components lead to dyssynchrony?
Delayed lateral wall contraction
Disorganized ventricular contraction
Reduced active filling
Paradoxical septal wall motion
What are the goals of CRT?
Organize ventricular activation sequence
Coordinate septal and free wall contraction
Improve cardiac efficiency
What factors may contribute to patient’s response to CRT?
% of CRT capture
Lead positioning
AV delay
V-V interval
Diastolic function
Mitral regurgitation
Scar location/burden
Advanced HF
Multipoint stimulation
What is the optimal location for LV pacing?
LV free wall, midway between base and apex
What are the possible branches available from the CS for most patients?
Postero-lateral vein, lateral branches of middle cardiac vein, lateral branches of the anterior intraventricular vein
The ideal LV pacing location produces what kind of morphology?
R wave in V1 with RBBB morphology, negative lead I
What are some challenges to LV lead placement?
Stenotic or occluded thoracic venous system
Difficult CS access
Tortuous or stenotic venous branches
Small venous branches
Right-sided implants
Persistent LSVC
What are the most common reasons for failed LV lead implants?
Inability to access the CS ostium
Inability to advance the lead into a target branch
Acute lead dislodgement or instability
CRT pacing is LOST when….?
Intrinsic ventricular activation wins out over biventricular pacing
What factors may cause ventricular activation to win out over biventricular pacing?
Atrial tachyarrhythmias
Suboptimal AV intervals
Inadequate LV pacing output
Delayed activation
LV/RV electrode proximity
Undersensing
What is the EffectiveCRT algorithm?
Adjusts pacing rate based on the morphology of the LV electrogram following BiV or LV only pacing.
How does BiV Trigger and Ventricular Rate Regulation (VRR) algorithms help to increase CRT pacing during atrial arrhythmias?
Reduces V-V cycle length variability during partially conducted atrial arrhythmias by modestly increasing the pacing rate
What is Adaptive CRT algorithm?
dynamic, physiologic pacing algorithm that enhances CRT by adjusting parameters automatically with changes in activity level and intrinsic conduction status
How does Adaptive CRT work?
Automatically updates intrinsic AV delays every 5 minutes and then paces at least 50ms before QRS onset
In adaptive CRT, when does the device pace only in the LV?
When intrinsic AV delays are normal
In adaptive CRT, when does the device pace RV and LV?
When intrinsic AV delays are prolonged
How does ventricular sense response (VSR) work to improve BiV pacing %?
Triggering an immediate BiV pace when a ventricular event is sensed.
PMT algorithms are inappropriately triggered ____% of the time?
46% (algorithms should be turned off in most CRT patients).
Describe the algorithm for Non-competitive atrial pacing (MDT)/atrial upper rate (BIO)
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.
How does Atrial Tracking Recovery maintain CRT pacing?
maintains AV synchrony by ensuring continuous CRT pacing when lost due to PVCs or fast conducted atrial rhythms
Pacemaker definition of PVC
Two consecutive sensed V events without an atrial event in between
What is the preferred pacing method for CRT patients?
DDD or VDD, rate response should be avoided if the chronotropic response is preserved
