Echocardiographic Assessment of Myocardial Strain · Echocardiographic Assessment of Myocardial Strain ... (22) extended the ... proposed a post-systolic strain index as being predictive

Journal of the American College of Cardiology Vol. 58, No. 14, 2011© 2011 by the American College of Cardiology Foundation ISSN 0735-1097/$36.00

STATE-OF-THE-ART PAPER

Echocardiographic Assessment of Myocardial Strain

John Gorcsan III, MD, Hidekazu Tanaka, MD

Pittsburgh, Pennsylvania

Echocardiographic strain imaging, also known as deformation imaging, has been developed as a means to ob-jectively quantify regional myocardial function. First introduced as post-processing of tissue Doppler imaging ve-locity converted to strain and strain rate, strain imaging has more recently also been derived from digitalspeckle tracking analysis. Strain imaging has been used to gain greater understanding into the pathophysiologyof cardiac ischemia and infarction, primary diseases of the myocardium, and the effects of valvular disease onmyocardial function, and to advance our understanding of diastolic function. Strain imaging has also been usedto quantify abnormalities in the timing of mechanical activation for heart failure patients undergoing cardiacresynchronization pacing therapy. Further advances, such as 3-dimensional speckle tracking strain imaging,have emerged to provide even greater insight. Strain imaging has become established as a robust research tooland has great potential to play many roles in routine clinical practice to advance the care of the cardiovascularpatient. This perspective reviews the physiology of myocardial strain, the technical features of strain imagingusing tissue Doppler imaging and speckle tracking, their strengths and weaknesses, and the state-of-the-artpresent and potential future clinical applications. (J Am Coll Cardiol 2011;58:1401–13) © 2011 by the AmericanCollege of Cardiology Foundation

Published by Elsevier Inc. doi:10.1016/j.jacc.2011.06.038

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Noninvasive assessment of regional myocardial function isimportant to the field of cardiovascular medicine to diag-nose disease, assess therapeutic interventions, and predictclinical outcomes. Although magnetic resonance imagingand computed tomography imaging are useful diagnosticalternatives, echocardiography remains advantageous forwidespread clinical use because of its portability, low risk,and comparatively high temporal resolution. Echocardio-graphic strain imaging, also known as deformation imaging,is a technological advancement that has been developed as ameans to objectively quantify regional myocardial function(1–3). First introduced as a post-processing feature of tissueDoppler imaging (TDI) with velocity data converted tostrain and strain rate, strain imaging information has morerecently also been derived from speckle tracking computerprocessing (4,5). Currently, most echocardiography labora-tories continue to use the subjective visual assessment of wallmotion for resting and stress imaging for everyday clinicaluse, and strain imaging has been more often regarded as aresearch tool. Adoption of strain imaging in clinical practiceappears to have been gaining momentum more recently.This paper reviews the physiology of myocardial strain, thetechnical features of strain imaging using both TDI andspeckle tracking, their strengths and weaknesses, and thepotential present and future clinical applications.

From the University of Pittsburgh, Pittsburgh, Pennsylvania. Dr. Gorcsan hasreceived research grant support from GE and Toshiba. Dr. Tanaka has reported thathe has no relationships relevant to the contents of this paper to disclose.

cManuscript received August 8, 2010; revised manuscript received May 31, 2011,

accepted June 10, 2011.

Physiology of Left Ventricular Strain

D’Hooge et al. (2), Dandel and Hetzer (6), and Mor-Avi et al. (7)published scholarly reviews of the technical features of strainimaging in detail previously. Briefly, myocardial regional mechan-ics assessed by echocardiographic approaches have been describedby 4 principal types of strain or deformation: longitudinal, radial,circumferential, and rotational (Fig. 1). Although myocardial fiberorientation results in these strain vectors occurring 3 dimensionallyin an integrated manner, most investigative works have been doneusing individual strain assessments. The term strain applied toechocardiography in a simplistic sense is to describe lengthening,shortening, or thickening, also known as regional deformation.Strain may be � � �L/L0 understood as an example of annfinitesimally thin bar where the only possible deformation isengthening or shortening. Accordingly linear strain or themount of deformation can be defined by the change in lengthivided by the original length expressed by the formula: � �

�L/L0, where � � strain, �L � change in length, and L0 �riginal length. In reality, the myocardial wall as a 3-dimensional3D) object has strain that may occur along 3 planes (x-, y-, and-axes), known as normal strains, and 6 shear strains (2,3,6).espite the complexities of myocardial wall dynamics, someeaningful information has been derived using the simplified

inear strain or deformation model by echocardiography.

train by TDI

he first description of echocardiographic strain was derivedrom TDI velocity data using the Doppler equation to
onvert ultrasound frequency shifts to velocity information

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1402 Gorcsan III and Tanaka JACC Vol. 58, No. 14, 2011Myocardial Strain September 27, 2011:1401–13

along the scan lines. Because thefundamental data produced byTDI were velocity information,strain rate (strain per unit oftime) was derived from the ve-locity data using the equation:� � V1 � V2/L, where � � strainrate, V1 � velocity at point 1,V2 � velocity at point 2, and L �length, usually set at 10 mm.Strain rate and strain data usingTDI required the direction of themyocardial wall motion to bealong the ultrasound scan line(1,3). Longitudinal shorteningusing the apical windows wasoften used because of the favor-able Doppler angle of incidence

3) (Fig. 2). The alternative was from the parasternal viewshere the relative transmural change in velocity could be

alculated as the velocity gradient, similar to strain rate (e.g.,n the posterior wall) (8–10). TDI strain rate data could bentegrated over time to determine strain (Fig. 3). Because allDI information is affected by the Doppler angle of

ncidence, Doppler angle correction analysis programs wereeveloped to determine wall motion for regions where theotion was not aligned with the Doppler scan line (11).owever, it remained impossible to assess wall motion byDI when the angle of motion was close to 90o. Accord-

ingly, the majority of the published literature on echocar-diographic strain imaging using TDI assessed longitudinalstrain from the apical windows with left ventricular (LV)shortening and lengthening aligned with the Doppler scan

Abbreviationsand Acronyms

CMR � cardiac magneticresonance

CRT � cardiacresynchronization therapy

DSE � dobutamine stressechocardiography

EF � ejection fraction

LBBB � left bundle branchblock

LV � left ventricular

TDI � tissue Dopplerimaging

2D � 2-dimensional

3D � 3-dimensional

Figure 1 Myocardial Fiber Orientation andPrincipal Vectors of Left Ventricular Strain

Echocardiographic application of strain imaging has assessed longitudinalstrain from apical windows and radial, circumferential, and rotational strainfrom parasternal windows. With permission from H. Tanaka.

lines. The important technical features of TDI acquisition andanalysis appear in the Online Appendix.

Strain by Speckle Tracking

A more recent echocardiographic approach to strain analysisis speckle tracking. Speckle tracking is a post-processingcomputer algorithm that uses the routine grayscale digitalimages. Although several manufacturers have devisedspeckle tracking echocardiographic approaches, the funda-mental approach is similar (4,12,13). Briefly, routine gray-scale digital images of the myocardium contain uniquespeckle patterns. A user-defined region of interest is placedon the myocardial wall. Within this region of interest, theimage-processing algorithm automatically subdivides re-gions into blocks of pixels tracking stable patterns ofspeckles. Subsequent frames are then automatically analyzedby searching for the new location of the speckle patternswithin each of the blocks using correlation criteria and thesum of absolute differences (Fig. 4). The location shift ofthese acoustic markers from frame to frame representingtissue movement provides the spatial and temporal dataused to calculate velocity vectors. Temporal alterations inthese stable speckle patterns are identified as moving fartherapart or closer together and create a series of regional strainvectors. Because strain information is not dependent on theDoppler angle of incidence like TDI strain, several morestrain analyses are possible, including longitudinal, circum-ferential, radial, and rotational. Additional technical fea-tures of speckle tracking acquisition and analysis appear inthe Online Appendix.

Strain Imaging forMyocardial Ischemia and Viability

Significant insights pertaining to the pathophysiology ofischemic heart disease have resulted from echocardio-graphic strain imaging over the past decade (14 –18).Previously, the clinical assessment of wall motion abnor-malities at rest or with stress by exercise or dobutaminehas consisted of visual assessment of endocardial excur-sion and wall thickening. The addition of strain imaginghas refined the ability of echocardiography to detect andobjectively qualify specific patterns of ischemia and in-farction. Because ischemic wall motion abnormalities areoften associated with passive motion, such as passiveexpansion and recoil and tethering from adjacent seg-ments, strain imaging has the advantage of differentiatingactive contraction from passive motion, which often isdifficult visually (19). Strain imaging has been validatedin animal models of acute ischemia and infarction (20,21)(Fig. 5). Edvardsen et al. (16) used TDI longitudinal strainin humans to demonstrate patterns of LV wall lengthen-ing with acute ischemia while patients underwent occlu-sion of the left anterior descending coronary artery (16).Specifically, strain quantified expansion in the apical
septal segments (7.5 � 6.5% vs. �17.7 � 7.2%,

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1403JACC Vol. 58, No. 14, 2011 Gorcsan III and TanakaSeptember 27, 2011:1401–13 Myocardial Strain

p � 0.001) and reduced compression in the mid-septalsegments. Skulstad et al. (19) used radial and longitudinalstrain imaging to define the pattern of post-systolicshortening with acute coronary occlusion in an animalmodel with sonomicronometry validation. Kukulski et al.(22) extended the concept of post-systolic shorteningusing TDI strain in humans undergoing coronary angio-plasty with peak strain occurring after aortic valve closureand restoration of strain after reperfusion (Fig. 6).Weidemann et al. (18) proposed a post-systolic strainindex as being predictive of the extent of transmurality ofmyocardial infarction. Lim et al. (23) subsequentlyshowed that time-to-peak TDI strain was significantlycorrelated with the percentage of infarct transmuralitywith a modest correlation coefficient of r � 0.69.

An important contribution of strain imaging has beenas an adjunct to low-dose dobutamine stress echocardi-ography (DSE) to assess myocardial viability. Hanekomet al. (24) examined 55 patients with ischemic heart diseaseby DSE with both visual wall motion assessment andlongitudinal strain and strain rate imaging followed byrevascularization by coronary bypass or percutaneousinterventions. Patients were re-examined 9 months laterto determine LV functional recovery after revasculariza-tion as evidence of viability. Visual wall motion assess-ment alone had a sensitivity of 71% and a specificity of77% for detecting viable segments by DSE. Sensitivitywas modestly but significantly improved by longitudinalstrain and strain rate imaging, with the most favorableresults achieved by a combination of visual assessmentand strain imaging with a sensitivity 84% and a specificity

Figure 2 Strain Imaging in a Normal Subject

Examples of tissue Doppler imaging velocity, strain rate, and strain curves for a ca

of 80%. p

Although radionuclide single-photon emission computedtomography imaging or gadolinium-enhanced cardiac mag-netic resonance (CMR) imaging appear to be preferredcurrently to quantify myocardial scar, strain imaging con-tinues to emerge as a new potential approach (25,26). Roeset al. (27,28) used speckle tracking longitudinal strain toassess viable myocardium compared with contrast-enhancedCMR imaging in 90 patients with chronic ischemic LVdysfunction. A favorable correlation was found betweenresting longitudinal LV strain and the extent of scarring byCMR imaging. The mean longitudinal strain in segmentswithout scarring was �10.4 � 5.2% compared with 0.6 �4.9% in segments with transmural scarring (p � 0.001). Atrain cutoff value of �4.5% had a sensitivity of 81.2% andspecificity of 81.6% for predicting viable myocardium from

egments with transmural scarring by contrast-enhancedMR imaging. Bansal et al. (29) compared speckle tracking

ongitudinal strain with TDI of strain during low-dose DSEo determine viability in 55 patients with subsequent revas-ularization. They reported TDI of strain to be moreccurate to determine viability than speckle tracking longi-udinal strain. The precise reason for this difference isnknown; however, the lower temporal resolution of speckleracking strain compared with TDI of strain is a potentialactor. Future refinements of speckle tracking for patientsith ischemic heart disease are likely forthcoming.

pplications of Strain Imaging forardiac Resynchronization Therapy

train imaging by both TDI and speckle tracking ap-

cycle from a subject with normal cardiac function. L � length; V � velocity.
rdiac
roaches have been reported to assess abnormal regional

l


mechanical activation patterns, known as dyssynchrony,with particular interest for patients undergoing cardiacresynchronization therapy (CRT). Interest has focused ondyssynchrony as a means to predict response to CRTbecause approximately one-third of patients do not appearto benefit using standard clinical selection criteria (30,31).LV longitudinal shortening velocities by TDI from theapical views have been introduced as a means to quantify LVdyssynchrony (32–34). The 2 most popular applications ofTDI velocities have included the differences in timing ofpeak velocity between LV walls (opposing wall delay) andthe SD in time to peak velocities from 12 sites (Yu Index)(32–35). The advantage of TDI velocities is that thesignal-to-noise ratio is high, but a major limitation is theinability of velocity to differentiate active from passive

Figure 3 Longitudinal Strain by Speckle Tracking Imagingin a Normal Subject and a Heart Failure Patient

(A) An example of speckle tracking imaging of longitudinal strain using theapical 4-chamber view in a normal subject demonstrating peak longitudinalstrain of �16.5% and �21.5%, respectively. (B) An example of speckle track-ing imaging of longitudinal strain using the apical 4-chamber view in a heartfailure patient with depressed ejection fraction demonstrating smaller peak lon-gitudinal strain of �8.0% and �12.5%, respectively. AVC � aortic valveclosure.

motion. The multicenter PROSPECT (Providing Regional

Observations to Study Predictors of Events in the CoronaryTree) study suggested that the TDI opposing wall delayperformed relatively better than other dyssynchrony indexesfor predicting LV reverse remodeling; however, echocardio-graphic dyssynchrony was not considered reliable enough toreplace current selection criteria for CRT (36). Accordingly,interest in the quantification of LV dyssynchrony by strainimaging has continued. Yu et al. (35) observed that the12-segment SD of time-to-peak TDI velocities was supe-rior to TDI strain for predicting LV reverse remodelingafter CRT in 256 patients. On the other hand, Miyazaki etal. (37) showed contrary findings that TDI of longitudinalstrain might be a preferred dyssynchrony technique tolongitudinal velocities. In their study of 120 heterogeneoussubjects including normal subjects and patients with leftbundle branch block (LBBB) and reduced ejection fraction(EF). They observed considerable overlap of TDI velocitiesbetween groups and difficulties with analysis of multiplevelocity spikes even in normal subjects. In contrast, theybelieved that longitudinal strain more reliably distinguishedpatients with LBBB or decreased EF from those withnormal EF and normal QRS duration. However, TDI oflongitudinal strain is severely affected by the Doppler angleof incidence, which is a limitation for enlarged spherical leftventricles, commonly encountered in the CRT patients. Weshowed more recently in a prospective study of 229 CRTpatients that a TDI velocity opposing wall delay of �80 msand Yu Index �32 ms were significantly associated withlong-term survival over a 4-year period (38).

Specific Speckle TrackingApplications of Strain for Dyssynchrony

Four different speckle tracking dyssynchrony approacheshave been suggested, including radial strain (myocardialthickening) and circumferential strain (myocardial short-ening) assessed from short-axis views (Figs. 7 and 8) andongitudinal strains (myocardial shortening) and trans-

Figure 4 Speckle Tracking Strain by Echocardiography

Diagram of speckle tracking strain from 2-dimensional short-axis echocardio-graphic images. Information about myocardial strain is generated by changes inspeckles from frame to frame. Strain is calculated as the change in length (�L)divided by the original length (L ) and expressed as a percentage.
0


verse (myocardial thickening) assessed from apical views(Figs. 9 and 10). Radial and transverse strains havepositive curves, reflecting myocardial thickening. Con-versely, longitudinal and circumferential strains havenegative curves, reflecting myocardial shortening. Dys-synchrony is typically characterized in LBBB by early

Figure 5 TDI of Radial Strain of a Myocardial Infarction

This is a pig model of myocardial infarction with angle-corrected tissue Doppler impreserved radial thickening in the noninfarct region and dyskinesis in the infarct re

Figure 6 Post-Systolic Thickening During Acute Ischemia

Examples of radial and longitudinal strain during coronary occlusion and reperfusiodemonstrating the pattern of post-systolic thickening occurring after aortic valve cl

septal radial thickening, followed by delayed posteriorand lateral wall thickening. Suffoletto et al. (13) firstreported the utility of speckle tracking radial strain inquantifying dyssynchrony, defined as the time differencein peak anteroseptum to posterior wall strain �130 ms, tobe associated with EF response to CRT. A combined

(TDI) of radial strain demonstratingLV � left ventricle; RV � right ventricle.

patient with coronary disease(AVC). Modified, with permission, from Kukulski et al. (22).

aginggion.

n in aosure


approach of using both TDI longitudinal velocity oppos-ing wall delay and speckle tracking radial strain wasshown to be of additive value for predicting response toCRT (39). Lim et al. (40) reported the strain delay indexdetermined by longitudinal speckle tracking strain fromstandard apical views was a marker of both LV dyssyn-chrony and myocardial contractility. They demonstratedthat the strain delay index �25% strongly predictedresponse to CRT with a 95% sensitivity and an 83%

Figure 7 Radial Strain by 2D Speckle Tracking in a Normal Sub

(A) An example of speckle tracking radial strain using the midventricular short-axis(arrow). (B) An example of speckle tracking radial strain using the midventricularfor resynchronization therapy demonstrating dyssynchrony; early anteroseptal peak2D � 2-dimensional.

specificity and correlated with reverse remodeling in both

the ischemic (r � 0.68) and nonischemic (r � 0.68)patients (p � 0.0001 for both). The STAR (SpeckleTracking and Resynchronization) study was the firstprospective multicenter study to associate speckle track-ing strain dyssynchrony with EF response and long-termsurvival after CRT (41). Speckle tracking radial strainfrom short-axis views and transverse strain from apicalviews were associated with response to CRT in 132patients, whereas longitudinal and circumferential strain

and a Heart Failure Patient With LBBB

in a normal subject demonstrating synchronous peak radial strain curvesxis view in a heart failure patient with left bundle branch block (LBBB) referredfollowed by late posterior wall peak strain (arrow). AVC � aortic valve closure;

ject

viewshort-astrain

appeared less sensitive in detecting important dyssyn-


chrony. A lack of dyssynchrony before CRT by radial ortransverse strain (or both) was significantly associatedwith death, heart transplantation, or LV assist deviceimplantation. Dyssynchrony by speckle tracking radialstrain was shown to be strongly associated with long-termsurvival after CRT in another study of 229 patients. Alack of radial dyssynchrony was particularly associatedwith an unfavorable outcome in those with a shorter QRSduration of 120 to 150 ms. Most recently, Delgado et al.(26) showed an association of a lack of dyssynchrony byspeckle tracking radial strain with death or heart failurehospitalization in a series of 397 CRT patients withischemic heart disease. Similar results for dyssynchronyanalysis using speckle tracking radial strain may be

Figure 8 Circumferential Strain by 2D Speckle Tracking in a No

(A) An example of 2D speckle tracking circumferential (Circum.) strain using the mcumferential strain curves (arrow). (B) An example of 2D speckle tracking circumfLBBB referred for resynchronization therapy demonstrating early anteroseptal peakAbbreviations as in Figure 7.

achieved using different software approaches, and it

appears promising as an adjunct for patient selection forCRT with borderline QRS duration (42,43).

3D Speckle Tracking Strain

A newer speckle tracking approach to quantify LV dyssyn-chrony is 3D speckle tracking echocardiography (44,45). 3Dspeckle tracking provides a more comprehensive evaluationof LV mechanics from pyramidal 3D datasets than waspreviously possible. 3D cine loops of regional strain are colorcoded and divided into 16 segments for time-strain curves,polar maps, and 3D displays (Fig. 11). Maximum opposingwall delay and SD by 3D speckle tracking strain significantlycorrelated with similar 2-dimensional (2D) strain measures,

Subject and a Heart Failure Patient With LBBB

tricular short-axis view in a normal subject demonstrating synchronous peak cir-l strain using the midventricular short-axis view in a heart failure patient withfollowed by late posterior wall peak strain, resulting in dyssynchrony (arrow).

rmal

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with 3D having the advantage of more precise mechanical

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activation mapping to assist with LV lead positioning (45)(Fig. 12). 3D speckle tracking strain was also useful forshowing differences in the sites of earliest activation in rightventricle–paced patients compared with those with LBBB,but similar sites of latest activation and similar response toCRT (44). Future advancements with expansion of appli-cations for 3D speckle tracking are anticipated.

Assessment of Rotational Strain

Notomi et al. (12,46) used TDI and speckle trackingstrain methods to assess LV rotational mechanics andcalculate torsion. They elegantly reported the normalpattern of slight clockwise basal rotation and greatercounterclockwise apical rotation as viewed in the stan-

Figure 9 Longitudinal Strain by 2D Speckle Tracking in a Norm

(A) An example of speckle tracking longitudinal (Long.) strain using the apical 4-chcurves (arrow). (B) An example of speckle tracking longitudinal strain using the aptherapy demonstrating early septal peak strain followed by late lateral wall peak s

dard short-axis echocardiographic view orientation (Fig. 13).

he combination of these rotational strain vectors wasescribed as torsion. They validated rotational and tor-ion measures against tagged cine magnetic resonancemaging using TDI during systole and early diastoleapical and basal rotation, r � 0.87 and 0.90, respectively;or torsion, 0.84; p � 0.0001). In a second related study,hey performed similar comparisons using speckle track-ng measures of rotation and torsion in 13 patients alsoemonstrating a strong correlation with tagged magneticesonance imaging (y � 0.95x � 0.19, r � 0.93, p �

0.0001). This group went on to describe a temporal linkbetween LV untwisting, relaxation, and suction in ananimal model, showing that the peak untwisting rate wasan independent predictor of tau and intraventricular

bject and a Heart Failure Patient With LBBB

r view in a normal subject demonstrating synchronous peak longitudinal strain-chamber view in a heart failure patient with LBBB referred for resynchronizationesulting in dyssynchrony (arrow). Abbreviations as in Figure 7.

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ambeical 4

train, r

pressure gradient (p � 0.0001 for both) (47– 49). Tan et


al. (50) reported on the role of LV untwisting in patientswith heart failure and normal EF, observing reduced anddelayed diastolic untwisting resulting in reduced LVsuction at rest and on exercise. Bertini et al. (51)demonstrated reduced subendocardial LV twist in pa-tients with ST-segment elevation myocardial infarction,and Andrade et al. (52) recently applied 3D speckletracking to assess LV twist.

Applications of Strain Imagingfor Cardiomyopathies

TDI and speckle tracking strain have been used tocharacterize patients with primary myocardial diseasesincluding hypertrophic cardiomyopathy, cardiac amyloid-osis, drug-induced cardiomyopathy, and arrhythmogenicright ventricular dysplasia (9,53–58). Palka et al. (9)demonstrated that early diastolic strain rates were signif-icantly lower in patients with hypertrophic cardiomyop-

Figure 10 Transverse Strain by 2D Speckle Tracking in a Norm

(A) An example of speckle tracking transverse (Trans.) strain using the apical 4-chcurves (arrow). (B) An example of speckle tracking transverse strain using the aptherapy demonstrating early septal peak strain followed by late lateral wall peak s

athy compared with patients with hypertrophy related to

hypertension or those with athlete’s heart. Kato et al. (56)more recently found that TDI of longitudinal strain of�10.6% (average of the anterior, inferior, septal, andlateral) was associated with a sensitivity of 85% and aspecificity of 100% for the detection of hypertrophiccardiomyopathy. Furthermore, Yang et al. (57) reportedunique findings that longitudinal strain by TDI wassignificantly lower in the mid-septum than that of theapical and basal segments in patients with hypertrophiccardiomyopathy (p � 0.01), and 55% of patients had apositive peak strain value (paradoxical systolic expan-sion). Yajima et al. (59) recently reported regional peaklongitudinal speckle tracking strain can distinguish fi-brotic from nonfibrotic lesions in LV myocardium inpatients with hypertrophic cardiomyopathy and normalLV myocardium in healthy controls.

Koyama et al. (53) first demonstrated the incrementalvalue of longitudinal strain and strain rate for the

bject and a Heart Failure Patient With LBBB

r view in a normal subject demonstrating synchronous peak transverse strainhamber view in a heart failure patient with LBBB referred for resynchronizationesulting in dyssynchrony (arrow). Abbreviations as in Figure 7.

al Su

ambeical 4-ctrain, r

diagnosis of cardiac amyloidosis. They proposed that


longitudinal strain imaging could identify a group ofpatients with probable subclinical cardiac amyloidosisearlier in the course of the disease process at a time whenroutine 2D echocardiography and Doppler assessment ofdiastolic function was normal. In 119 patients withcardiac amyloidosis, they reported a basal longitudinalstrain value of less than �12.0% was predicted of cardiacdeath over a year (60). They concluded that strain andstrain rate displayed greater sensitivity than velocity ordisplacement for detecting subtle abnormalities in thelongitudinal contraction early in the patient’s course withamyloidosis. Bellavia et al. (55) also reported similarfindings from 103 patients with biopsy-proven cardiac

Figure 11 3D Speckle Tracking Radial Strain in a NormalSubject and a Heart Failure Patient With LBBB

(A) The color-coded 3-dimensional (3D) left ventricular (LV) display (top left)and bull’s eye plot image (bottom left) and corresponding time-to-strain curvesfrom 16 LV sites (right) in a normal subject demonstrating synchronous time-to-peak strain curves represented by homogeneous coloring at end-systole(arrow). A maximum opposing wall delay was 20 ms and 16-segment SD was6 ms. (B) The color-coded display (top left) and bull’s eye plot image (bottomleft) and corresponding time-to-strain curves from 16 LV sites (right) in a heartfailure patient with left bundle branch block (LBBB) demonstrating dyssynchro-nous time to peak strain curves represented by heterogeneous coloring at end-systole, with early peak strain in septal segments and delayed peak strain inposterior lateral segments (arrow). A maximum opposing wall delay was 378ms and 16-segment SD was 165 ms. ant � anterior; ant-sept � anterior-sep-tum; inf � inferior; lat � lateral; post � posterior; sept � septal.

amyloidosis.

Detection of chemotherapeutic cardiac toxicity is of greatclinical importance. Ho et al. (54) reported the long-termeffects of standard chemotherapy including trastuzumab onmyocardial function in asymptomatic breast cancer survivorsusing 2D speckle tracking strain. They found that thechemotherapy group had reduced global longitudinalspeckle tracking strain in comparison with normal controls(�18.1 � 2.2% vs. �19.6 � 1.8%, p � 0.0001), eventhough the EF was similar (62 � 4% vs. 60 � 3%). Incontrast, global radial speckle tracking strain did not differsignificantly between the 2 groups. Prakasa et al. (58)evaluated the utility of TDI of longitudinal strain in patientswith arrhythmogenic right ventricular dysplasia to deter-mine whether these modalities could provide complemen-tary and incremental diagnostic information. They foundthat a value of �18% of right ventricular free wall longitu-dinal strain provided the greatest discriminatory power fordifferentiating patients with arrhythmogenic right ventricu-lar dysplasia from normal controls. Importantly, 4 patientshad a diagnosis of arrhythmogenic right ventricular dyspla-sia by TDI of strain with morphologically normal rightventricles by 2D echocardiography.

Applications of Strain Imagingfor Effects of Valvular Heart Disease

The chronic effects of abnormal loading from valvulardisease on myocardial function may be difficult to detect byconventional means, and strain imaging may play a role(61–67). Delgado et al. (62) demonstrated that patientswith severe aortic stenosis and preserved EF exhibiteddecreased radial, circumferential, and longitudinal speckletracking strain. In addition, significant improvement inthese parameters was observed at long-term follow-up afteraortic valve replacement, whereas EF remained unchanged.de Isla et al. (63) reported that preoperative speckle trackinglongitudinal strain at the level of the interventricular septumfrom the apical 4-chamber view strongly predicted a post-operative EF decrease of �10% in patients with chronicsevere mitral regurgitation. Tayyareci et al. (64) demon-strated that longitudinal and circumferential strains assessedby velocity vector imaging were significantly decreased inasymptomatic patients with severe aortic regurgitation andnormal EF compared with normal volunteers. Furthermore,Onishi et al. (61) recently reported that preoperative systolicradial strain rate derived from TDI was the best predictor ofpost-operative LV systolic dysfunction of an EF �50% inpatients with severe aortic regurgitation and a normal EF.These findings highlight that TDI of or 2D speckle trackingstrain enables an early detection of subtle changes in LVsystolic function in patients with valvular heart disease.

Conclusions

Echocardiographic strain imaging, also known as defor-
mation imaging, has provided a means to objectively


quantify myocardial mechanical function. Originally in-troduced as a product of TDI, speckle tracking is a morerecent extension of strain imaging. Strain imaging hasprovided greater understanding of the pathophysiology ofcardiac ischemia and infarction, primary diseases of the

Figure 12 Color-Coded 3D Speckle Tracking Radial Strain Map

Patient A has the site of latest mechanical activation in the midposterior segmentmidlateral segment (red arrow). Patient C has a broad site of latest mechanical a

Figure 13 Rotational Strain Imaging From a Normal Subject

Short-axis views at the basal and apical levels with speckle tracking demonstratinin a subject with normal cardiac function. The combination of basal and apical rotECG � electrocardiogram.

myocardium, assessment of dyssynchrony for CRT, theeffects of valvular disease on myocardial function, and themechanics of diastolic function. Strain by 3D speckletracking has emerged as a further advance to provide evengreater insight. Strain imaging has become established as

m 3 Different Heart Patients With LBBB

rrow). In contrast, Patient B has the site of latest mechanical activation in then (red arrow). Abbreviations as in Figure 11.

wise basal rotation (red line) and counterclockwise apical rotation (blue line)n opposite directions results in left ventricular (LV) torsion.

s Fro

(red activatio

g clockation i


a robust research tool and has great potential to playmany roles to advance the care of the cardiovascularpatient.

Reprint requests and correspondence: Dr. John Gorcsan III,University of Pittsburgh, Scaife 564, 200 Lothrop Street, Pitts-burgh, Pennsylvania 15213-2582. E-mail: [email protected].

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Key Words: deformation y echocardiography y myocardial.

APPENDIX

For additional technical features of TDI and speckle tracking acquisition,
please see the online version of this article.

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Echocardiographic Assessment of Myocardial Strain · Echocardiographic Assessment of Myocardial Strain ... (22) extended the ... proposed a post-systolic strain index as being predictive