Download Simultaneous 4-Chamber Strain - Circulation: Cardiovascular Imaging

Editorial
Simultaneous 4-Chamber Strain
More and Faster Analysis, But Is It Good Enough?
Tomasz Baron, MD, PhD; Frank A. Flachskampf, MD, PhD
A
Downloaded from http://circimaging.ahajournals.org/ by guest on May 11, 2017
Peak LV LS values, calculated from the 6 segments of the
4-chamber view, were −18±2%. This is lower than a recent
meta-regression from the published literature reported for
classic global LS (calculated from the 18 segments of the
3 apical views), namely −19.7%; 95% confidence interval,
−20.4% to −18.9%.4 Although the reduction compared with
published values may seem low, 1.7% absolute percent difference corresponds to 9% relative change. Because strain
measurements are typically used to detect small, subtle, subclinical changes, this is not a negligible difference.
Peak left atrial strain values reported in the study of
Addetia (+38±13%) are close to the published values.5,6 For
the right ventricular free wall, a normal range of −23±6% was
found, again lower than currently recommended normal values from (−29±4.5%).1 Given the smooth appearance of the
strain curves, postprocessing may have contributed to underestimation, which re-emphasizes that strain values are dependent on underlying software and hardware.
A puzzling detail of the left ventricular and atrial strain
curves is their timing. From Figure 1 of Addetia et al (the only
one with an electrocardiographic tracing), it seems that LV
and left atrial strain curves both start at zero at the end of the
electrocardiographic QRS complex. However, physiologically, left atrial (LA) expansion in sinus rhythm starts at the
onset or even before the QRS complex5,7 (see Figure), and LV
longitudinal shortening also starts during QRS.
The authors found higher strain values in women than in
men and a decrease of peak left and right atrial strain with age,
findings generally in line with the literature,8,9 and new for
the right atrium. Time-to-peak strain measurements from all
chambers are also reported. However, their clinical relevance
is unclear at this point because this parameter to date has been
used mainly to assess regional differences in contraction timing in the LV, and applications for global values are unclear.
The main attraction of the presented technique is that from
one view and within one heart beat, function (more properly,
LS) of all 4 chambers is evaluated quantitatively in a semiautomatic way. Is this the future for time-pressed echocardiographers? Several caveats apply. Echocardiographic acquisition
of an apical 4-chamber view is usually optimized for showing
LV structures as well as possible, mostly the LV endocardium
and the mitral valve. Recognizing this, current guidelines for
right ventricular (RV) assessment explicitly call for an extra,
optimized, RV-focussed view to best evaluate right ventricular morphology and function.1 Similarly, renewed interest
in LA volume as a marker of diastolic function and general
prognosis has reminded us that in many 4-chamber views,
the LA is foreshortened, and often LA-optimized views are
necessary to better delineate this structure, sometimes at the
expense of detail in other chambers. Thus, it is likely that
nalysis of myocardial deformation, or strain imaging, is
becoming part of routine echocardiography.1 The most
widely accepted parameter to date has been global longitudinal strain as a measure of global left ventricular (LV) function.
Global longitudinal strain (LS) of the LV, in (negative) percent, is
the average of the maximal shortening (in percent) in the apicobasal direction of each of 18 LV segments visualized in the 3 standard apical views. The strain curves are computed using speckle
tracking to determine myocardial velocity in a region of interest
from which local strain is derived. LS is defined as deformation
(shortening or lengthening) along the midline of LV walls, that
is, in an apico-basal direction, but following the curvature of the
LV walls.2 Similarly, global left or right atrial or right ventricular
LS can be obtained as average of segmental peak LS. Strain data
are highly dependent on image quality and frame rate, as well as
physiological parameters as blood pressure.
See Article by Addetia et al
The article of Addetia et al3 in this issue of Circulation:
Cardiovascular Imaging explores LS values from all 4 chambers
obtained simultaneously from the 4-chamber view of the same
cardiac cycle using a software (Epsilon Imaging, Ann Arbor MI)
that can accommodate data acquired with echo machines from
different echo manufacturers, although for this article, only echos
acquired with one brand of echo machines were used. LS analysis was based on speckle tracking in 21 segments per patient
(6 for the LV, 3 for the right ventricle, and 6 each for left and
right atrium, using the same 3 septal segments for both); for each
chamber, a global strain curve was calculated by averaging the
segmental LS of the pertinent segments. Less than 1% of segments were excluded because of bad quality, which is a remarkably high success rate. For unclear reasons, the size of individual
segments presented in Figure 1 of Addetia et al is somewhat variable, most conspicuously for the small basal right ventricular free
wall segment. Global peak LS and heart rate–corrected time-topeak LS were measured for each chamber, and data from 259
healthy individuals, stratified by sex and age, are presented.
The opinions expressed in this article are not necessarily those of the
editors or of the American Heart Association.
From the Department of Clinical Physiology, Institutionen för
Medicinska Vetensklaper, Uppsala University, Uppsala, Sweden.
Correspondence to Frank A. Flachskampf, MD, PhD, Akademiska
sjukhuset, Ingång 40, plan 5, 751 85 Uppsala, Sweden. E-mail frank.
[email protected]
(Circ Cardiovasc Imaging. 2016;9:e004544.
DOI: 10.1161/CIRCIMAGING.116.004544.)
© 2016 American Heart Association, Inc.
Circ Cardiovasc Imaging is available at
http://circimaging.ahajournals.org
DOI: 10.1161/CIRCIMAGING.116.004544
1
2 Baron and Flachskampf 4-Chamber Strain
Downloaded from http://circimaging.ahajournals.org/ by guest on May 11, 2017
Figure. A, Representative normal left atrial (LA) regional strain curve obtained by speckle tracking with relation to timing of cardiac
events. Note that positive LA strain (LA expansion) starts well before the end of the electrocardiographic QRS complex. AC indicates aortic closure; AO, aortic opening; Dia, diastasis; LAc, LA contraction; LAr, LA relaxation; LVs, left ventricular systole; MC, mitral closure; MO,
mitral opening; and PaE, LA passive empyting. Modified with permission from Vianna-Pinton et al.5 Copyright @ 2009, Elsevier. B, Speckle
tracking–based, average longitudinal LA strain from six atrial segments from the four-chamber view of a healthy individual. Note that LA
expansion (upward direction of curve) begins at the onset of QRS complex. Peak atrial longitudinal strain at end-systole was +28.8%.
Green vertical line denotes aortic valve closure.
using one single 4-chamber view heart cycle will not produce optimal evaluation of each chamber, even if technically adequate tracking is reported in over 99% of patients
by Addetia et al. Additionally, if RV free wall function is to
be evaluated by speckle tracking, much higher frame rates
and thus better data can be achieved by sector narrowing if
acquisition is focussed on this structure. Thus, and because
of its monoplane representation of the LV, this approach is
unlikely to replace dedicated analysis of single chambers.
The example offered by Addetia et al of a patient with severe
pulmonary hypertension (Figure 7 of Addetia et al) underlines this. The authors state that, “compared with the normal
values…the peak LS RA/LA [right atrial / left atrial] and RV/
LV ratios were elevated, suggesting that right heart function
is hypercontractile when compared with left heart function.”
However, RV/LV peak strain ratio is given as 1.2 for the pulmonary hypertension patient, not much different from 1.1,
the ratio reported for normals.
Importantly, the independence of (left or right) atrial
and ventricular LS is questionable. Because atrium and
ventricle are tethered to each other in mechanical continuity, longitudinal shortening of 1 of the 2 must be associated
with lengthening of the other, and vice versa, because the
total volume and the apico-basal dimension of the heart are
constant throughout the cardiac cycle.10,11 Although strain
measures local deformation, this deformation itself physiologically depends on preload and afterload, which are
affected by the adjacent myocardium. Because the myocardial mass of the left atrium (15–45 g at autopsy)12 is much
smaller than the LV mass, it is likely that peak left atrial
strain, which occurs at LV end-systole, heavily depends on
LV mechanics.
In conclusion, Addetia et al present a first experience with
a formidable feat of image postprocessing, allowing a quick
glimpse of deformation in all 4 chambers from one echo view
and one heartbeat. The place of this approach in the clinical
arena remains to be determined.
Disclosures
None.
References
1. Lang RM, Badano LP, Mor-Avi V, Afilalo J, Armstrong A, Ernande L,
Flachskampf FA, Foster E, Goldstein SA, Kuznetsova T, Lancellotti P,
Muraru D, Picard MH, Rietzschel ER, Rudski L, Spencer KT, Tsang W, Voigt
JU. Recommendations for cardiac chamber quantification by echocardiography in adults: an update from the American Society of Echocardiography
and the European Association of Cardiovascular Imaging. Eur Heart J
Cardiovasc Imaging. 2015;16:233–270. doi: 10.1093/ehjci/jev014.
2. Voigt JU, Pedrizzetti G, Lysyansky P, Marwick TH, Houle H, Baumann R,
Pedri S, Ito Y, Abe Y, Metz S, Song JH, Hamilton J, Sengupta PP, Kolias TJ,
d’Hooge J, Aurigemma GP, Thomas JD, Badano LP. Definitions for a common standard for 2D speckle tracking echocardiography: consensus document
of the EACVI/ASE/Industry Task Force to standardize deformation imaging.
J Am Soc Echocardiogr. 2015;28:183–193. doi: 10.1016/j.echo.2014.11.003.
3. Addetia K, Takeuchi M, Maffessanti F, Nagata Y, Hamilton J, Mor-Avi V,
Lang RM. Simultaneous longitudinal strain in all 4 cardiac chambers: a novel
method for comprehensive functional assessment of the heart. Circ Cardiovasc
Imaging. 2016;9:e003895. doi: 10.1161/CIRCIMAGING.115.003895.
4.Yingchoncharoen T, Agarwal S, Popović ZB, Marwick TH. Normal
ranges of left ventricular strain: a meta-analysis. J Am Soc Echocardiogr.
2013;26:185–191. doi: 10.1016/j.echo.2012.10.008.
5. Vianna-Pinton R, Moreno CA, Baxter CM, Lee KS, Tsang TS, Appleton CP.
Two-dimensional speckle-tracking echocardiography of the left atrium: feasibility and regional contraction and relaxation differences in normal subjects.
J Am Soc Echocardiogr. 2009;22:299–305. doi: 10.1016/j.echo.2008.12.017.
6.Saraiva RM, Demirkol S, Buakhamsri A, Greenberg N, Popović ZB,
Thomas JD, Klein AL. Left atrial strain measured by two-dimensional
speckle tracking represents a new tool to evaluate left atrial function. J Am
Soc Echocardiogr. 2010;23:172–180. doi: 10.1016/j.echo.2009.11.003.
7.Hoit BD. Left atrial size and function: role in prognosis. J Am Coll
Cardiol. 2014;63:493–505. doi: 10.1016/j.jacc.2013.10.055.
8.Andre F, Steen H, Matheis P, Westkott M, Breuninger K, Sander Y,
Kammerer R, Galuschky C, Giannitsis E, Korosoglou G, Katus HA, Buss
SJ. Age- and gender-related normal left ventricular deformation assessed
by cardiovascular magnetic resonance feature tracking. J Cardiovasc
Magn Reson. 2015;17:25. doi: 10.1186/s12968-015-0123-3.
9. Sun JP, Yang Y, Guo R, Wang D, Lee AP, Wang XY, Lam YY, Fang F, Yang
XS, Yu CM. Left atrial regional phasic strain, strain rate and velocity by
speckle-tracking echocardiography: normal values and effects of aging in
a large group of normal subjects. Int J Cardiol. 2013;168:3473–3479. doi:
10.1016/j.ijcard.2013.04.167.
10. Hamilton WF, Rompf JH. Movements of the base of the ventricle and relative constancy of the cardiac volume. Am J Physiol. 1932;102:559–565.
11. Hoffman EA, Ritman EL. Invariant total heart volume in the intact thorax.
Am J Physiol. 1985;249:883–890.
12. Mazzoleni A, Wolff R, Wolff L, Reiner L. Correlation between component cardiac weights and electrocardiographic patterns in 185 cases.
Circulation. 1964;30:808–829.
Key Words: Editorials ◼ cardiovascular
◼ longitudinal strain ◼ strain
imaging
◼
deformation
Simultaneous 4-Chamber Strain: More and Faster Analysis, But Is It Good Enough?
Tomasz Baron and Frank A. Flachskampf
Downloaded from http://circimaging.ahajournals.org/ by guest on May 11, 2017
Circ Cardiovasc Imaging. 2016;9:e004544
doi: 10.1161/CIRCIMAGING.116.004544
Circulation: Cardiovascular Imaging is published by the American Heart Association, 7272 Greenville Avenue,
Dallas, TX 75231
Copyright © 2016 American Heart Association, Inc. All rights reserved.
Print ISSN: 1941-9651. Online ISSN: 1942-0080
The online version of this article, along with updated information and services, is located on the
World Wide Web at:
http://circimaging.ahajournals.org/content/9/3/e004544
Permissions: Requests for permissions to reproduce figures, tables, or portions of articles originally published
in Circulation: Cardiovascular Imaging can be obtained via RightsLink, a service of the Copyright Clearance
Center, not the Editorial Office. Once the online version of the published article for which permission is being
requested is located, click Request Permissions in the middle column of the Web page under Services. Further
information about this process is available in the Permissions and Rights Question and Answer document.
Reprints: Information about reprints can be found online at:
http://www.lww.com/reprints
Subscriptions: Information about subscribing to Circulation: Cardiovascular Imaging is online at:
http://circimaging.ahajournals.org//subscriptions/