Echo-Based Optimization of CRT Therapy
Echo-Based Optimization of CRT Therapy
The role of echocardiography in CRTPre-CRT implantation -
Dyssynchrony evaluation to predict the CRT responder - More
dyssynchrony, more responsePost-CRT implantation - Optimization of
dyssynchrony to get benefit from CRT therapy - ,
Dr Lin had saied2
Pre-CRT implantation - Dyssynchrony evaluation to predict the
CRT responder
AV conduction delayLBBB_Eletric dyssynchrony
M-modeColor M-mode
Intra-ventricular
Color code tissue doppler
Septal to posterior wall strain delay > 130 ms
Inter-ventricular
Interventricular mechanical delay (IVMD) > 40ms
Post-CRT implantation - Optimization of dyssynchrony to get
benefit from CRT therapy - A-V ; V-V
Atrio-ventricular
Intra-ventricular
Inter-ventricular
Optimal AV delayCompletion of the atrial contribution to
diastolic filling
LV contraction occurs immediately following mitral valve
closure
completion of the atrial contribution to diastolic filling
resulting in most favorable preload before ventricular contraction
AV delay programmed too short will result in absence or
interruption of the atrial component (mitral A wave) by the
premature ventricular contraction and closure of the mitral valve.
AV delay programmed too long can result in suboptimal LV preload or
diastolic MR, or may even allow native LV conduction, which defeats
the purpose of CRT
10
Effect of AV Delay on LV Diastolic Filling Pattern
Short AV Delay50 msA-wave truncated Less time for fillingAtrial
contraction against a closed Mitral valveLong AV Delay280 msFused A
and E waveLess time for fillingPre-systolic Mitral
regurgitationOptimized AV Delay200 msMax diastolic filling
timeMitral closure occurs at end of A-wave
2 AV-optimization methodsIterative MethodEasy to
performAccurateRitter MethodConfusingLimited accuracy for Bi-V
devicesOften times iterative method must be employed to get the
best setting
Step 1: Shorter the programmed AV delay to see truncated A
wave
Step 2: Lengthenthe programmed AV delay to no A-wave
cutoffIterative Method
Ritter MethodStep 1: Shorter the programmed AV delay to see
truncated A wave
Step 2: Lengthen the programmed AV delay to see E A fusion
Diastolic MR (Ishilawa method)Aim to minimize diastolic MR
Optimal AV delay= Long AV delay-duration ofdiastolic MR
V-V OptimizationInvasive left ventricular dP/dtmaxEcho base_
LVOT TVI measureEcho base_ Doppler/ M-mode guided synchrony
Optimal cardiac output
Cardiac Output = Stroke volume x Heart rateStroke Volume= LVOT
area X Velocity Time Integral (VTI) Since LVOT is a constant the
larger VTI the larger stroke volume
DLVOT
Time (sec)
VTI (cm) = Area under velocity curve/timeVelocitycm/sec
18.2720.71 18.918.9V-V OptimizationBest VTI
22.67
20Aortic VTIs
M-Mode guided V-V Optimization
T(2) - T(1) = IVMD .546-.488 = 58ms delayIn the InSync III
Marquis ICD study the following methodology was used: M-Mode of
septal and posterior wall at the papillary muscle levelMeasure from
onset of Q-wave to peak excursion of both septal and posterior wall
across several different V-V paced intervalsCalculate the
difference between the 2 segmentsV-V Opt = the setting with the
smallest delay
Peak posterior excursion
Peak septal excursion
Electrical activationNote: In the study they measured from
Q-wave to the peak of the excursion. In practice, all you really
need to measure is the separation between the peaks.
Device timing optimizationStroke volume(Aortic VTI)
Trans-mitral flow
Intra-ventricular synchrony
Rev Esp Cardiol. 2012;65(6):504510
CRT Follow-up
Timing of optimizationBest evidence-based practice is to follow
the CARE-HF protocol and optimize AV delay using iterative methods
combined with VV delay at Baseline ( pre-discharge ) 3 months every
6 months there after
Timing of echo optimizationEcho prn F/U and echo-base
optimizationWorsen S/S of heart failure
26
_CRTFc171.120.4130.115.8*EF(%)25.66.947.519.1*LVIDd(mm)66.47.959.311.9*QRS(ms)3.470.51.820.7*HF
Admission2.41.20.91.4*
Pre CRTPost CRT* P
