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Click icon to add picture DR AWADHESH KUMAR SHARMA

DM CARDIOLOGY

FINAL YEAR

DEPARTMENT OF CARDIOLOGY

PGIMER & DR RML HOSPITAL

NEW DELHI

INTRODUCTION

Cardiac resynchronization therapy (CRT) using

atrio biventricular pacing has evolved into a

useful therapeutic option for patients with heart

failure, refractory to optimal medical therapy.

Improvements in quality of life, morbidity,

mortality, severity of mitral regurgitation (MR)

and left ventricular (LV) function have been

demonstrated in large randomized clinical trials

but the treatment is invasive and expensive. Iuliano S, Fisher SG, Karasik PE, Fletcher RD, Singh SN: Department of Veterans Affairs Survival Trial of Antiarrhythmic Therapy in Congestive Heart Failure. QRS duration and mortality inpatients. Am Heart J 2002, 143:1085-1091.

INTRODUCTION CONTD……

Besides, about one third of patients remain

unresponsive in spite of the device

implantation using the existing criteria.

However, 30–40% of patients selected on the

basis of a prolonged QRS do not receive

benefit by CRT since they do not show any

significant inverse LV remodeling (a ≥ 15%

reduction of LV end-systolic volume six

months after device implantation).Cleland JG, Daubert JC, Erdmann E, Freemantle N, Gras D, Kappenberg L, Tavazzi L: Cardiac Resynchronization – Heart Failure (CARE-HF) Investigators. The effect of cardiac resynchronization therapy on morbidity and mortality in heart failure. N Engl J Ned 2005, 352:1539-1549.

INTRODUCTION CONTD…..

Furthermore, QRS duration does not accurately

distinguish responders to CRT .

Although factors responsible for the absence of

favourable response may be lead dislodgement or

inappropriate location of LV lead, mechanical

dyssynchrony (particularly intra-ventricular

dyssynchrony) plays a important role.

There is thus a need to carefully identify the patients

most likely to benefit by this intervention using

indices of mechanical dyssynchrony.J Am Coll Cardiol 2002,40:1703-1719.

DEFINITIONS OF DYSSYNCHRONY

Electrical Vs Mechanical Dyssynchrony

Electrical Dyssynchrony refers to a prolonged

conduction time in the ventricles resulting in a

prolonged QRS duration.

Mechanical Dyssynchrony is the mechanical

discoordination , usually associated with

simultaneous contraction and stretch in different

regions of the LV as well as delays in the time to

peak contraction from one segment to another.

DELETERIOUS HEMODYNAMIC EFFECTS OF LV DYSSYNCHRONY

Diminished SV & CO due:

Reduced diastolic filling time

Weakened contractility

Protracted MV regurgitation

Post systolic regional contraction

Atrio-ventricular

Inter-V

Intra-V

Cazeau, et al. PACE 2003; 26[Pt. II]: 137–143

TOOLS FOR DYSSYNCHRONY ASSESSMENT

2D Echocardiography 3D Echocardiography MRI

ECHOCARDIOGRAPHIC ASSESSMENT

ATRIOVENTRICULAR DYSSYNCHRONY

AV dyssynchrony reduces the duration of

ventricular filling, thus inducing the

appearance of diastolic mitral and tricuspid

regurgitation and reducing stroke volume.

Atrio-ventricular (AV) dyssynchrony occurs in

patients with dilated cardiomyopathy and

first degree AV block and was the first

objective of CRT by bicameral pacemakers in

the early 1990s.

ATRIOVENTRICULAR DYSSYNCHRONY CONTD……

Atrioventricular dyssynchrony- is said to be present when diastolic filling period (DFP) occupies less than 40% of cardiac cycle (measured by R-R interval.

1. To obtain DFP, obtain the apical four-chamber view with mitral valve in the centre of the frame.

2. Using pulsed Doppler with the sample volume placed at the

tips of mitral leaflets; obtain a spectral display of mitral

inflow pattern.3. Measure the time from the onset to the end of the

spectral display- this represents DFP.4. Measure the R-R interval using any two consecutive

regular beats. Divide DFP with R-R interval and multiply by hundred to

obtain a percentage value .

Assessment of atrioventricular dyssynchrony using pulsed-Dopplermeasurement of mitral inflow velocity at mitral leaflet tips

INTERVENTRICULAR DYSSYNCHRONY

Inter-ventricular dyssynchrony represents the

discordance between the times of right

ventricular (RV) and LV contraction.

Interventricular mechanical dyssynchrony is

assessed by measuring the interventricular

mechanical delay.

Cardiac resynchronization therapy and the emerging role of echocardiography (Part 1): indications and results from current studies. J Am Soc Echocardiogr 2007, 20:70-75.

INTERVENTRICULAR DYSSYNCHRONY CONTD…..

PW or CW Doppler images of aortic and

pulmonary flow velocities are currently used

to measure the inter-ventricular mechanical

delay (IVMD).

A difference of IVMD values of > 40 ms

and values of LV PEP of >140 ms are

considered pathological .Echocardiographic modeling of cardiac dyssynchrony before and during multisite stimulation: a prospective study. Pacing Clin Electrophysiol 2003, 26:137-143.

INTERVENTRICULAR DYSSYNCHRONY

To obtain time to onset of LV ejection, obtain

the apical five-chamber view and place the

pulsed-Doppler sample volume at the left

ventricular outflow tract (LVOT).

Measure the time from the onset of QRS

complex to the onset of the pulsed-Doppler

flow velocity. This is the LV pre-ejection

period (LVPEP).Cardiac resynchronization therapy and the emerging role of echocardiography (Part 2); the comprehensive examination. J Am Soc 2007, 20:76-90.

INTERVENTRICULAR DYSSYNCHRONY

To obtain the time to onset of RV ejection, obtain

the Right ventricular outflow tract (RVOT) view

(para-sternal short axis) and place the pulsed

Doppler sample volume at RVOT.

Measure the time interval from onset of QRS

complex to the onset of pulse-Doppler velocity

curve. This is the RV pre ejection period (RVPEP).

The difference of LVPEP and RVPEP gives

interventricular mechanical delay .

LIMITATIONS

Presence of pulmonary arterial hypertension

and/or RV systolic dysfunction, which can

prolong RV PEP.

Concomitantly impaired increase of LV

pressure in very severe CHF.

INTERVENTRICULAR DYSSYNCHRONY CONTD….. Alternatively, pulsed Tissue Doppler can be

used to determine IVMD by measuring the

time from QRS onset to the peak myocardial

systolic velocities (Sm) of the RV free wall

(tricuspid annulus) versus the same time of

LV lateral mitral annulus (apical 4-chamber

view) .Echocardiographic evaluation of cardiac resynchronization therapy: ready for routine clinical use? A critical appraisal. J Am Coll Cardiol 2004, 44:1-9.

INTRAVENTRICULAR DYSSYNCHRONY

Intraventricular dyssynchrony is the principal

factor responsible for contractile dysfunction,

the one most affected by and most predictive

of response to resynchronization therapy.

Large number of indices have been described

and evaluated in studies using several

echocardiographic modalities.

Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony. J Am Coll Cardiol 2002, 40:1616-1622.

ASSESSMENT OF INTRAVENTRICULAR DYSSYNCHRONY

1. M-mode measurement of septal-posterior wall

motion delay (SPWMD)

2. TDI for measurement of time to peak systolic

longitudinal velocity of various myocardial

segments & time to peak systolic longitudinal strain

and strain rate of various myocardial segments

3. Assessment of radial dyssynchrony using speckle-

tracking

4. Three-dimensional echocardiographyVentricular asynchrony predicts a better outcome in patients with chronic heart failure receiving cardiac resynchronization therapy. J Am Coll Cardiol2002, 40:536-545.

M-MODE MEASUREMENT OF SPWMD

This is the simplest technique to assess the

septal to posterior wall motion delay.

1. Position the M-Mode cursor at the papillary

muscle level in either the parasternal long or

short axis view.

2. Keeping the sweep speed from 50-100

mm/second, measure the time delay from

peak inward septal motion to peak inward

posterior wall motion.Cardiac resynchronization therapy and the emerging role of echocardiography; the comprehensive examination. J Am Soc 2007, 20:76-90.

M-MODE MEASUREMENT OF SPWMD ……….

In the original experience of Pitzalis et al on

20 patients with advanced heart failure, a

SPWMD (determined in parasternal short-axis

view) of >130 ms was considered

pathological and SPWMD predicted inverse

LV remodeling and long-term clinical

improvement after CRT, with 100%

sensitivity, 63% specificity and 85% accuracy

.Cardiac resynchronization therapy tailored by echocardiographic evaluation of ventricular asynchrony. J Am Coll Cardiol 2002, 40:1616-1622.

ADVANTAGE & LIMITATION OF SPWMD

The main advantages of this method correspond to the

low-cost technique and the availability in all the

echocardiographic machines.

The limitations include the impossibility to measure

SPWMD in patients with a poor acoustic window, previous

septal or posterior wall myocardial infarction, or abnormal

septal motion secondary to RV pressure or volume

overload.

In addition, M-mode can only visualize dyssynchrony of

the anterior septum or posterior wall whereas other LV

walls can be involved.

COLOR TDI IMAGING, M-MODE

M-MODE MEASUREMENT OF SPWMD is quite simple and widely

available but it is often quite difficult to identify the peaks in both the

walls. To overcome this shortcoming, color TDI M-mode is now

recommended as it enables the identification of the peak systole by

the sharp color transition

1. Position the M-Mode cursor at the papillary muscle level in either the

parasternal long or short axis view.

2. Keeping the sweep speed from 50-100 mm/second, select color TDI.

3. Measure the time delay from peak inward septal motion to peak inward

posterior wall motion, as indicated by the sharp color transition .

A value > 130ms signifies dyssynchrony and response to

CRT with a high degree of sensitivity.

LATERAL WALL POST-SYSTOLIC DISPLACEMENT (LWPSD)

A another method, reported by Sassone et al, determines lateral

wall post-systolic displacement (LWPSD), measured as the

difference of intervals from QRS onset to maximal systolic

displacement of the basal LV lateral wall (assessed by M-mode in

the apical 4-chamber view) and from QRS onset to the beginning of

transmitral E velocity (assessed by pulsed Doppler of mitral inflow).

A positive LWPSD i.e. a longer interval to maximal inward

displacement of LV lateral wall than the interval to opening of the

mitral valve, identifies a severe post-systolic contraction and has

been demonstrated to be an independent predictor of CRT

response in 48 patients with end-stage heart failure and left bundle

branch block.Sassone B, Capecchi A, Boggian G, Gabrieli L, Saccà S, Vandelli R, Petracci E, Mele D: Value of baseline left lateral wall postsystolic displacement assessed by m-mode to predict reverse remodeling by cardiac resynchronization therapy. Am J Cardiol 100(3):470-5. 2007, Aug 1; Epub 2007 Jun 15

QRS onset to maximal systolic displacement of the basal LV lateral wall (assessed by M-mode in the apical 4-chamber view)

QRS onset to the beginning of transmitralE velocity (assessed by pulsed Doppler of mitral inflow)

Minus

Methodology for measuring lateral wall post-systolic displacement (LWPSD). It is measured as the difference of the time interval from QRS onset to maximal systolic displacement of the basal LV lateral wall (assessed by M-mode in the apical 4- chamber view) (upper panel) and the time interval from QRS onset to the beginning of transmitral E velocity (assessed by pulsed Doppler of mitral inflow) (lower panel). In this example, the positive value of the difference indicates the co-existence of segmental post-systolic contraction and diastolic relaxation. (Modified from Sassone B et al, Am J Cardiol 2007;100:470–475).

LATERAL WALL POST-SYSTOLIC DISPLACEMENT (LWPSD)……….

Of interest, despite evaluating intra-ventricular

dyssynchrony based on delay of a single myocardial wall,

LWPSD could predict CRT response.

This may rely to the fact that, in the presence of left bundle

branch block, the lateral wall is the latest to be activated,

theoretically representing the optimal target for LV lead

positioning.

This method has not yet tested in patients without left

bundle branch block and its diagnostic accuracy is unknown.

In addition. it needs the identical heart rate when measuring

the M-mode and pulse Doppler imaging.

TDI FOR ASSESSMENT OF INTRAVENTRICULAR DYSSYNCHRONY

Measurement of time to peak- systolic

longitudinal velocity-

Assessment of longitudinal shortening velocities ie

the time of myocardial systolic velocities (Sm) from

the apical window with TDI has been studied

extensively and several indices proposed.

There are two approaches possible- pulsed-TDI or

color-coded TDI but owing to several limitations with

pulsed-TDI, color TDI is now the preferred method.Doppler myocardial imaging to evacuate the effectiveness of pacing sites in patients receiving biventricular pacing. J Am Coll Cardiol 2002, 39:489-499.

MEASUREMENT OF TIME TO PEAK- SYSTOLIC LONGITUDINAL VELOCITY-

1. Obtain a noise free ECG trace and good quality 2D image from

the apical window with the LV cavity in the centre of image

sector and the depth adjusted to include the mitral annulus.

2. Activate color TDI, adjusting the sector width so as to keep the

frame rate > 90 frames/second.

3. Suspend breathing if possible and acquire 3-5 beats (sinus

rhythm) or more (in case of ectopics).

4. The number of LV segments to be evaluated include mainly a

12-segment model (LV basal and middle segments in 4-, 2-

and 5-chamber views) whereas LV apical segments are not

considered reliable because of the basal apical myocardial

gradient own of Tissue Doppler.

Methodology for measuring pulsed Tissue Doppler derived time to peak Sm and time to onset Sm (left panel).In the right panel measurements of time to peak Sm (upper panel) and of time to onset Sm (lower panel) are depicted. Am=Myocardial atrial velocity, CTm = Contraction time, Em = Myocardial early diastolic velocity, RTm = Myocardial relaxationtime, Sm = Myocardial systolic velocity. Mod from Agler DA et al, J Am Soc Echocardiogr 2007;20:76–90.

TIME TO PEAK- SYSTOLIC LONGITUDINAL VELOCITY

The most widely used measurements correspond to

the time interval between the onset of ECG derived

QRS and the Sm peak (= time to Sm peak) and the

time interval between the onset of QRS and the onset

of Sm (= time to Sm onset), which correspond to LV

PEP.

Intra-ventricular mechanical delay has been

defined for differences of > 65 ms of time to Sm

peak between LV segments.Intra-left ventricular electromechanical asynchrony: a new independent predictor of severe cardiac events in heart failure patients. J Am Col Cardiol 2004, 43:248-256.

TIME TO PEAK- SYSTOLIC LONGITUDINAL VELOCITY CONTD……

Receiver-operator characteristic curve analysis

demonstrated that this cut-off value yielded a

sensitivity and specificity of 80% to predict clinical

improvement and of 92% to predict LV reverse

remodeling in 85 patients with end-stage heart failure,

QRS duration > 120 ms, and left bundle-branch block.

Intra-left ventricular electromechanical asynchrony: a new independent predictor of severe cardiac events in heart failure patients. J Am Col Cardiol 2004, 43:248-256.

LIMITATION OF PW TISSUE DOPPLER

The main limitation of PW Tissue Doppler

corresponds to the impossibility of measuring

the time intervals of different segments

during the same cardiac cycle.

It is also necessary to take into account that

the Sm recorded in apical views reflects LV

longitudinal shortening and not

circumferential contraction.

COLOUR TISSUE DOPPLER

1. Off-line colour Tissue Doppler derived

Tissue Velocity Imaging (TVI),

2. SRI

COLOUR TISSUE DOPPLER

Off-line colour Tissue Doppler derived Tissue Velocity

Imaging (TVI), Tissue Synchronization Imaging (TSI)

and SRI can be used to assess intra-ventricular

dyssynchrony in the longitudinal plane (apical views).

The common advantages of these techniques is the

possibility of measuring the dyssynchrony of

opposite LV walls (= horizontal dyssynchrony) and of

different segments of the same LV wall (= vertical

dyssynchrony) in a given view, from the same

cardiac cycle.

Methodology for recording and measuring intra-ventricular horizontal and vertical dyssynchrony by off-line color Tissue Doppler techniques. Horizontal dyssynchrony occurs between opposite walls. Vertical dyssynchrony isbetween different segments of the same wall.

COLOUR TISSUE DOPPLER

TVI measures the time to Sm peak (Ts) or the time to

Sm onset in LV basal and middle segments of the

three standard apical views.

By identifying the presence of one or more differences

> 50 ms among regional times of Sm onset, suggests

significant intraventricular dysynchrony .

Ghio and coworkers have demonstrated that

intraventricular dyssynchrony is detectable even in

29.5 % of patients with advanced LV dysfunction but

normal QRS duration by this criteria.Echocardiography 2006, 23:709-712.

Sample of time to peak (Ts) measured by off-line color TVI pre and post CRT at the level of anterior septumand postero-lateral wall, in apical 5-chamber view. Aortic valve opening (AVO) and closure (AVC) are derived by previous placement of markers on the onset and the end of LV Doppler outflow. Pre-CRT Ts of postero-lateral wall (upper panel) is clearly delayed in comparison to Ts of anterior septum. Post-CRT the time duration of Ts between the two walls is clearly shortened (lower panel). (Modified from Innelli P et al, Echocardiography 2006;23:709–716)

COLOUR TISSUE DOPPLER CONTD….

o Using a LV 12-segment model. A dyssynchrony

index (DI) or Yu index can be derived as the

Standard deviation of the average values of Ts ie (Ts-

SD).

o As per Yu et al Ts-SD of > 32.6 ms predicts inverse LV

remodeling after CRT with 100% sensitivity, 100%

specificity and 100% accuracy in 30 candidates to

CRT.

Yu CM, Fung WH, Zhang Q, Sanderson JE, Lau CP: Predictors ofleft ventricular remodeling after cardiac resynchronizationtherapy for heart failure secondary to idiopathic or dilatedcardiomyopathy. Am J Cardiol 2003, 91:684-688.

DYSSYNCHRONY INDEX (DI) Methodology of calculation of

Dyssynchrony Index and is ability in predicting LV inverse remodeling.

In the upper panel methodology of calculation of Dyssynchrony Index, i.e., the standard deviation of Ts (Ts-SD) measured in the basal and mid-segments visualizable in the apical views.

In the lower panel, Ts-SD shows the ability to predict an effective LV inverse remodeling after CRT (lower panel). Values of TS-SD > 32.6 (black triangles) predict an effective LV reverse remodeling (DLVVs = delta left ventricular end-systolic volumes) after CRT. Patients with pre-CRT values of Ts-SD < 32.6 (empty circles) do not present significant LV inverse remodeling at follow-up.

(Modified from Yu CM et al, Am J Cardiol 2003;91:684–688)

TISSUE SYNCHRONIZATION IMAGING (TSI)

TSI is an implementation of Ts method.

It displays Ts (time to Sm peak) in multiple LV

segments by colour coding wall motion green

(corresponding to early systolic contraction) or red,

which corresponds to delayed contraction (sensitivity

= 87%, specificity = 81% and accuracy = 84% at a

cut-off value of 34.4 ms in 56 patients with severe

heart failure).A novel tool to assess systolic asynchrony and identify responders of cardiac resynchronization therapy by tissue synchronization imaging. J Am Coll Cardiol 2005, 45:677-684.

Four-dimensional tissue synchronization imaging (TSI) of a normal individual. From the different views (left), a three-dimensional impression of the left ventricle is reconstructed (middle). The entire three-dimensional image of the left ventricle is green indicating no dyssynchrony. Post- processing allows the display of the different segments in a polar map format (right) to further facilitate identification of the site of latest activation.

Four-dimensional tissue synchronization imaging (TSI) of a patient with left ventricular dyssynchrony. From the different views (left), a three-dimensional impression of the left ventricle is reconstructed (middle). The region of latest activation is indicated in red. Post-processing yields the polar-map format (upper right) indicating in red the site of latest activation (anteroseptal), and further calculations can be performed (lower right) tofurther quantify the extent of left ventricular dyssynchrony using different parameters.

SPECKLE TRACKING

This is a 2-D strain technique and has been

used to assess radial dyssynchrony

before/after CRT.

Speckle tracking has been applied to routine

mid-ventricular short-axis images to

calculate radial strain from multiple

circumferential points averaged to six

standard segments.

STRAIN

The principal benefit of LV shear strains is

amplification of the 15% shortening of myocytes into

40% radial LV wall thickening, which ultimately

translates into a >60% change in LV ejection fraction.

Left ventricular shearing increases towards the

subendoardium, resulting in a subepicardial to

subendocardial thickening strain gradient.

STRAIN……

Dyssynchrony from timing of peak radial

strain has been demonstrated to be

correlated with Tissue Doppler measures.

A time difference ≥ 130 ms between the

radial strain peak of LV posterior wall and

anterior septum has shown to be highly

predictive of an improved EF during follow-

up, with 89% sensitivity and 83% specificity.Circulation 2006, 113:960-968.

STRAIN…….

Another possibility, proposed by Porciani et

al, considers the time spent by 12 LV

segments in contracting after AVC, i.e.,

during the isovolumic relaxation time, and

measures the sum of the time of strain

tracing exceeding AVC (ExcT) on the 12 LV

basal and mid-segments (cut-off value = 760

ms, 93.5% sensitivity and 82.8% specificity).

Eur Heart J 2006, 27:1818-1823.

Methodology for measuring time of exceeding aortic valve closure contraction. The sum of the time of strain tracing exceeding aortic valve closure (ExcT) is calculated on the 12 LV basal and middle segments in the standard apical views.AVO = aortic valve opening, AVC = aortic valve closure(Modified from Porciani MT et al, Eur Heart J 2006;27:1818–1823)

DYSSYNCHRONY ASSESSMENT

The data thus obtained can be used to calculate any of

the several proposed dyssynchrony indices, as below

–

Delay in time-to-peak-systolic velocity between

opposing walls- > 65msec.

Maximum delay in time-to-peak-systolic velocity

between any two myocardial segments- >100msec.

Standard deviation of the time-to-peak-systolic

velocity of the 12 basal and mid LV segments- >

33msec. J Am Coll Cardiol Img 2010;3:132– 40

THREE-DIMENSIONAL ECHOCARDIOGRAPHY FOR ASSESSMENT OF DYSSYNCHRONY

Real time 3D echocardiography (RT3DE) is a

relatively new but very promising tool in the

assessment of dyssynchrony.

The greatest advantage of RT3DE is that it enables

the comparison of synchrony in all segments in the

same cardiac cycle.

Quantitative analysis involves using software which

enables LV volumetric analysis with semiautomatic

edge detection to produce a cast of the LV cavity.

Eur Heart J 2006, 27:859.

THREE-DIMENSIONAL ECHOCARDIOGRAPHY FOR ASSESSMENT OF DYSSYNCHRONY…….

o The global LV volumetric dataset has been used to

determine a dyssynchrony index that corresponds to the

standard deviation of the average of the time intervals

needed by multiple LV segments to reach minimal end-

systolic volume.

o This index is expressed as the percent value of the overall

cardiac cycle, in order to be able to compare patients with

different heart rates.

o CRT responders show a significant reduction of this 3-D

dyssynchrony index, which parallels the reduction of LV

enddiastolic volume and the increase in EF3D echocardiography reduces the time needed to assess left ventricular synchronicity in heart failure patients with clinical indication to cardiac resynchronization therapy. (abs) Eur Heart J 2006, 27:822.

LIMITATIONS OF 3-D ECHOCARDIOGRAPHY

The limitations of 3-D method are its

suboptimal feasibility (<80%), its temporal

resolution of about 40–50 ms, and its inability

to distinguish active from passive motion or

to make analysis in the presence of atrial

fibrillation and/or recurrent premature beats.

3-D derived time-volume curves of 16-segment model. Presentation 3-D derived time-volume curves of 16-segment LV model in a patient with intra-ventricular dyssynchrony. Each LV myocardial segment is codified by a different colours.

THREE-DIMENSIONAL ECHOCARDIOGRAPHY FOR ASSESSMENT OFINTRAVENTRICULAR DYSSYNCHRONY SHOWING SEGMENTAL TIME-TO-MINIMUM VOLUME IN SEGMENTAL SHELL-VIEW DISPLAY

MRI FOR DYSSYNCHRONY

VENC-MRI and cine-MRI were performed in 20 patients with heart failure

NYHA class III and reduced ejection fraction before CRT device

implantation.

The interventricular mechanical delay (IVMD) was assessed by VENC-

MRI as the temporal difference between the onset of aortic and

pulmonary flow.

Intraventricular dyssynchrony was quantified by cine-MRI, using the

standard deviation of time to maximal wall thickening in

sixteen left ventricular segments.

RESULTS

14 patients (70 %) clinically responded to CRT. A similar accuracy was

found to predict the response to CRT by measurements of the IVMD.

ALSO data analysis of the IVMD is significantly less time-consuming.

Quantification of mechanical ventricular dyssynchrony: direct

comparison of velocity-encoded and cine magnetic resonance

imaging.

Ref. JACC 2011 Jun;183(6):554-60. Epub 2011 Apr 12.

LV DYSSYNCHRONY AS ASSESSED WITH PHASE ANALYSIS FROM GATED MYOCARDIAL PERFUSION SPECT (GMPS)

Journal of the American College of Cardiology, Vol. 49, No. 16, 2007

Example of a patient without left ventricular (LV) dyssynchrony on gated myocardial perfusion single-photon emission computed tomography (GMPS). The non-normalized (upper panel) and normalized (lower panel) phase distributions are nearly uniform, and the corresponding phase histograms are highly peaked, narrow distributions.

Example of a patient with LV dyssynchrony derived from GMPS. The non-normalized (upper panel) and normalized (lower panel) phase distributions show significant non-uniformity and the corresponding phase histograms are widely spread distributions.

LIMITATIONS OF GATED MYOCARDIAL PERFUSION SPECT (GMPS)

Several limitations need to be acknowledged.

First, follow-up data after CRT implantation

were not available; therefore, it remains to be

determined what the value of GMPS is for

prediction of response to CRT.

Another limitation of GMPS, in general, is that

GMPS is less suitable than echocardiography

for follow-up after CRT implantation, due to the

radiation burden.

RV DYSSYNCHRONY

MAIN TECHNIQUES, PARAMETERS AND REFERENCE VALUES FOR DETECTION OF INTRA-VENTRICULAR DYSSYNCHRONY

SENSITIVITY, SPECIFICITY AND ACCURACY, AND CONFIRMATORY OR CONFLICTING DATA OF THE MAIN TECHNIQUES

DYSSYNCHRONY IN THE NARROW QRS PATIENT POPULATION

If CRT can be shown to be of benefit to these patients(narrow

QRS), the application of echocardiographic assessment of

dyssynchrony is potentially of great importance for patient

selection for therapy.

Trials showing benefit of CRT-

Bleeker et al showed CRT to benefit in 33 patients with NYHA

class III/VI heart failure and EF less than or equal to 35%, but

QRS less than 120 milliseconds, who had mechanical

dyssynchrony defined as a septal-to-lateral wall time-to-peak

systolic velocity delay of greater than or equal to 65

milliseconds by TD.(J Am Coll Cardiol 2006;48:2243-50.)

DYSSYNCHRONY IN THE NARROW QRS PATIENT POPULATION……….

Yu et al reported results on 51 patients with heart failure with narrow QRS

(120 milliseconds) who had CRT based on TD measures of dyssynchrony. CRT

resulted in significant reductions of LV end-systolic volume, and

improvement of NYHA class, 6-minute hall-walk distance, and EF, similar to

patients with wide QRS who underwent CRT.(J Am Coll Cardiol 2006;48:2251-7)

The first randomized trial of CRT in patients with heart failure with narrow

QRS complexes (130 milliseconds), known as the RethinQ trial, was

published by Beshai et al .This trial failed to show a therapeutic effect of CRT

on the primary end point of peak myocardial oxygen consumption. Although

a positive effect of CRT was observed on the secondary end point of

improvement in NYHA functional class, other parameters including quality-of-

life score, 6-minute walk test, and LV reverse remodeling did not change.

(N Engl J Med 2007;357:2461-71.)

CONCLUSIONSIn patients with systolic heart failure and a QRS duration of less than 130 msec, CRT does not reduce the rate of death or hospitalization for heart failure and may increase mortality. (0ct 2013)

According to ASE the dyssynchrony reporting

in cases with borderline ECG should not

include a recommendation whether a patient

should undergo CRT or not, as this should be

a clinical decision on a case-by-case basis.

POST CRT AV DELAY OPTIMIZATION

Because the ventricles are paced in CRT, the

AV delay needs to be programmed.

The optimal programmed AV delay for an

electronic pacemaker has been defined as

the AV delay that allows completion of the

atrial contribution to diastolic filling resulting

in most favorable preload before ventricular

contraction.

AV DELAY OPTIMIZATION

An 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.

An 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.

A simplified Doppler screening protocol after CRT implantation

is proposed using pulsed Doppler mitral inflow, because no

consensus currently exists for the routine performance of AV

optimization after CRT.

AV DELAY OPTIMIZATION………

Auricchio et al concluded that although AV delay often positively

impacts hemodynamics, LV resynchronization of intraventricular

dyssynchrony is more important.(Circulation 1999;99:2993-3001)

A larger report of 215 patients undergoing Doppler guided AV

optimization found small differences between the baseline and post-AV

optimization average AV delay (120 vs 135 milliseconds, respectively).

Furthermore, AV optimization enhanced LV hemodynamics in only a

minority of patients with CRT, suggesting that a significant percentage

of patients do not need to undergo formal AV optimization.

Patients with intra-atrial conduction delay at baseline appeared to

benefit greatest by prolonging the AV delays (150-250 milliseconds)

during AV optimization.Kedia N, Ng K, Apperson-Hansen C, et al. Usefulness of atrioventricular delay optimization using Doppler assessment of mitral inflow in patients undergoing cardiac resynchronization therapy. Am J Cardiol 2006;98:780-5.

THE ITERATIVE METHOD OF AV DELAY OPTIMIZATION

It begins by programming the CRT device in atrial

synchronous V pacing mode testing a series of AV intervals

sequentially.

This usually begins with an AV delay of 200 milliseconds,

then decreases in increments of 20-millisecond intervals to a

minimum AV delay as short as 60 milliseconds.

The minimal AV delay that allows for adequate E and A wave

separation and termination of the A wave at approximately

40 to 60 milliseconds before the onset of the QRS would be

considered the optimal AV delay, and usually corresponds

with a stage I diastolic filling pattern.

AV DELAY OPTIMIZATION……..

Technical features include positioning the

pulsed wave sample volume deeper toward

the left atrium (as opposed to the standard

position at the mitral leaflet tips) to optimize

detection of the mitral valve closure click,

preparing settings of high sweep speeds and

low filters, and inputting the ECG signal from

the device directly to the ultrasound system,

if possible.

AV DELAY OPTIMIZATION……….

A variation on the iterative method for AV

optimization uses transaortic Doppler velocities as a

surrogate for stroke volume.

The optimal sensed and paced AV delay is determined

by the maximum aortic time-velocity integral value at

6 selected paced and sensed AV delays.

A typical protocol will include measurements at AV

delays of 60, 80, 100, 120, 140, and 160 milliseconds,

with each paced and sensed AV delay setting

separated by a rest period of at least 10 to 15 beats.

CONCLUSION

Good quality ECG with a stable baseline and clear delineation

of the onset of QRS complex is an essential requirement for

accurate measurement of time periods.

Choose an ectopic free sequence and acquire at least 3-5

beats with breath held in expiration.

For TDI analysis, a sweep speed of 50-100 is recommended to

improve temporal resolution.

Tissue Doppler analysis is highly angle dependent and

misaligned images produce velocity curves consisting of not

only the longitudinal but also the radial velocities. The sample

volume should be as parallel as possible to the incident beam.

CONCLUSION

While analyzing color TDI data, the region-of-interest should

be moved within the myocardial segment to obtain the

most reproducible velocity curve with minimum artifacts.

If more than one systolic peak is obtained in the tissue

velocity curve, the most reproducible peak of maximum

amplitude should be used for analysis. If two or more peaks

have same amplitude, the earlier peak should be taken into

consideration.

For 3D imaging, optimum gain settings with clear

delineation of the endocardial border, especially at the apex

should be ensured.

CONCLUSION

A complete echocardiographic study along with

quantitation of mitral regurgitation should always be

performed in all cases.

Right ventricular systolic function should also be assessed

routinely during dyssynchrony analysis and the findings

should be reported.

No single parameter is predictive and there is no standard

recommended approach. Hence, all the parameters

possible depending on the laboratory and expertise should

be evaluated.

CONCLUSION The real value of these novel technologies remains to be

determined in randomized trials

Several imaging techniques were evaluated (magnetic

resonance imaging, speckle tracking echocardiography,

strain imaging, nuclear imaging) and yielded several

parameters of LV mechanical dyssynchrony that have

demonstrated to be independent determinants of CRT

response and long-term outcome in several observational

studies.

Everything should be

made as simple as

possible, but not

simpler.

—Albert Einstein

THANKS