echo guidelines for chamber quantification

7/30/2019 ECHO GUIDELINES FOR CHAMBER QUANTIFICATION

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ASE COMMITTEE RECOMMENDATIONS

Recommendations for ChamberQuantification: A Report from the American

Society of Echocardiographys Guidelines andStandards Committee and the ChamberQuantification Writing Group, Developed inConjunction with the European Association

of Echocardiography, a Branch of theEuropean Society of Cardiology

Members of the Chamber Quantification Writing Group are: Roberto M. Lang, MD, FASE,Michelle Bierig, MPH, RDCS, FASE, Richard B. Devereux, MD, Frank A. Flachskampf, MD,

Elyse Foster, MD, Patricia A. Pellikka, MD, Michael H. Picard, MD, Mary J. Roman, MD,James Seward, MD, Jack S. Shanewise, MD, FASE, Scott D. Solomon, MD,

Kirk T. Spencer, MD, FASE, Martin St John Sutton, MD, FASE,and William J. Stewart, MD

Quantification of cardiac chamber size, ventric-ular mass, and function ranks among the mostclinically important and most frequently re-quested tasks of echocardiography. Standardiza-tion of chamber quantification has been an earlyconcern in echocardiography and recommenda-

tions on how to measure such fundamental param-eters are among the most often cited articles inthe field.1,2 During the last decades, echocardio-graphic methods and techniques have improvedand expanded dramatically. Improvements in im-age quality have been significant, as a result of theintroduction of higher-frequency transducers, har-

monic imaging, fully digital machines, left-sidedcontrast agents, and other technologic advance-ments.

Furthermore, echocardiography has becomethe dominant cardiac imaging technique, which,because of its portability and versatility, is now

used in emergency, operating, and intensive caredepartments. Standardization of measurements inechocardiography has been inconsistent and lesssuccessful compared with other imaging tech-niques and, consequently, echocardiographicmeasurements are sometimes perceived as lessreliable. Therefore, the American Society of Echo-cardiography (ASE), working together with theEuropean Association of Echocardiography, abranch of the European Society of Cardiology, hascritically reviewed the literature and updated therecommendations for quantifying cardiac cham-bers using echocardiography. Not all the measure-ments described in this article can be performedin all patients because of technical limitations. Inaddition, specific measurements may be clinicallypertinent or conversely irrelevant in differentclinic scenarios. This article reviews the technicalaspects on how to perform quantitative chambermeasurements and is not intended to describe thestandard of care of which measurements shouldbe performed in individual clinical studies. How-ever, evaluation of chamber size and function is acomponent of every complete echocardiographicexamination and these measurements may have an

impact on clinical management.

From University of Chicago Hospitals, Chicago, IL (R.L., K.S.);St. Louis University Health Science Center, St. Louis MO (M.B.);Weill Medical College of Cornell University, New York, NY (R.D.,M.R.); Universityof Erlangen, Erlangen, Germany (F.F.);Univer-

sity of California, San Francisco, CA (E.F.); Mayo Clinic, Roches-ter, Minn (P.P., J.S.); Massachusetts General Hospital, Boston,Mass (M.H.P.); Columbia University, New York, NY (J.S.S.);Bringham and Womens University, Boston, Mass (S.S.)Universityof Pennsylvania, Philadelphia, PA (M.S.J.S.); Cleveland ClinicFoundation, Cleveland, OH (W.S.).

Address reprint requests to the American Society of Echocardiog-raphy, 1500 Sunday Drive, Suite 102, Raleigh, NC 27607 (919)864-7754.

J Am Soc Echocardiogr 2005;18:1440-1463.

0894-7317/$30.00

Copyright 2005 by the American Society of Echocardiography.

Property of ASE. Reprintof these documents, beyondsingleuse, isprohibited without prior written authorization of the ASE.

doi:10.1016/j.echo.2005.10.005

1440


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GENERAL OVERVIEW

Enhancements in imaging have followed technologicimprovements such as broadband transducers, har-monic imaging, and left-sided contrast agents. None-

theless, image optimization still requires considerableexpertise and attention to certain details that arespecific to each view (Table 1). In general, imagesoptimized for quantitation of one chamber may notnecessarily be optimal for visualization or measure-ment of other cardiac structures. The position of thepatient during image acquisition is important. Opti-mal views are usually obtained with the patient inthe steep left lateral decubitus position using acut-out mattress to permit visualization of the trueapex while avoiding left ventricular (LV) foreshort-ening. The patients left arm should be raised tospread the ribs. Excessive translational motion can

be avoided by acquiring images during quiet respi-ration. If images are obtained during held end expi-ration, care must be taken to avoid a Valsalva maneu-

ver, which can degrade image quality.Digital capture and display of images on the

echocardiographic system or on a workstationshould optimally display images at a rate of at least30 frames/s. In routine clinical practice a represen-tative cardiac cycle can be used for measurement aslong as the patient is in sinus rhythm. In atrialfibrillation, particularly when there is marked R-R

variation, multiple beats should be used for measure-ments. Averaging measurements from additional cy-

cles may be particularly useful when R-R intervals

are highly irregular. When premature atrial or ven-tricular contractions are present, measurementsshould be avoided in the postectopic beat becausethe length of the preceding cardiac cycle can influ-ence ventricular volume and fiber shortening.

Harmonic imaging is now widely used in clinicallaboratories to enhance images, especially in pa-tients with poor acoustic windows. Although thistechnology reduces the dropout of endocardial bor-ders, the literature suggests that there is a systemictendency for higher measurements of LV wall thick-ness and mass, and smaller measurements of internaldimensions and volumes.3,4 When analyzing serialstudies on a given patient, differences in chamberdimension potentially attributable to imaging changesfrom the fundamental to the harmonic modality areprobably smaller than the interobserver and intraob-server variability of these measurements. The best

technique for comparing serial changes in quantita-tion is to display similar serial images side by sideand make the same measurement on both images bythe same person, at the same time.5 It is importantto note that most measurements presented in thismanuscript are derived from fundamental imaging asnormative values have not been established usingharmonic imaging.

Left-sided contrast agents used for endocardial bor-der delineation are helpful and improve measurementreproducibility for suboptimal studies and correlation

with other imaging techniques. Although the use ofcontrast agents has been reviewed elsewhere in

detail,6

a few caveats regarding their use deservemention. The mechanical index should be loweredto decrease the acoustic power of the ultrasoundbeam, which reduces bubble destruction. The imageshould be focused on the structure of interest.Excessive shadowing may be present during theinitial phase of bubble transit and often the bestimage can be recorded several cardiac cycles afterthe appearance of contrast in the LV. When less than80% of the endocardial border is adequately visual-ized, the use of contrast agents for endocardialborder delineation is strongly recommended.7 Byimproving visualization of the LV apex, the problem

of ventricular foreshortening is reduced and corre-lation with other techniques improved. Contrast-enhanced images should be labeled to facilitate thereader identification of the imaging planes.

Quantitation using transesophageal echocardiog-raphy (TEE) has advantages and disadvantages com-pared with transthoracic echocardiography (TTE).

Although visualization of many cardiac structures isimproved with TEE, some differences in measure-ments have been found between TEE and TTE.These differences are primarily attributable to theinability to obtain from the transesophageal ap-proach the standardized imaging planes/views used

when quantifying chamber dimensions transthorac-

Table 1 Elements of image acquisition and measurementfor 2-dimensional quantitation

Aim Method

Minimize translationalmotion

Quiet or suspended respiration(at endexpiration)

Maximize image resolution Image at minimum depthnecessary

Highest possible transducerfrequency

Adjust gains, dynamic range,transmit, and lateral gaincontrols appropriately

Frame rate 30/sHarmonic imagingB-color imaging

Avoid apical foreshortening Steep lateral decubitus position

Cut-out mattressAvoid reliance on palpable apical

impulse

Maximize endocardialborder Contrast enhancement delineation

Identify end diastole andend systole

Mitral valve motion and cavitysize rather than reliance onECG

ECG, Electrocardiogram.

Journal of the American Society of EchocardiographyVolume 18 Number 12 Lang et al 1441


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ically.8,9 It is the recommendation of this writinggroup that the same range of normal values forchamber dimensions and volumes apply for bothTEE and TTE. In this article, recommendations forquantification using TEE will primarily focus on

acquisition of images that allow measurement ofcardiac structures along imaging planes that areanalogous to TTE.

In addition to describing a parameter as normal orabnormal (reference values), clinical echocardio-graphers most often qualify the degree of abnormal-ity with terms such as mildly, moderately, orseverely abnormal. Such a description allows theclinician to not only understand that the parameteris abnormal but also the degree to which theirpatients measurements deviate from normal. Inaddition to providing normative data it would bebeneficial to standardize cutoffs for severity of ab-

normality across echocardiographic laboratories,such that the term moderately abnormal had thesame implication in all laboratories. However, mul-tiple statistical techniques exist for determiningthreshold values, all of which have significant limi-tations.10

The first approach would be to define cutoffsempirically for mild, moderate, and severe abnor-malities based on SD above or below the referencelimit derived from a group of healthy people. Theadvantage of this method is that these data readily existfor most echocardiographic parameters. However, thisapproach has several disadvantages. Firstly, not all

echocardiographic parameters are normally distrib-uted (or gaussian) in nature, making the use of SDquestionable. Secondly, even if a particular parame-ter is normally distributed in control subjects, mostechocardiographic parameters, when measured inthe general population, have a significant asymmet-ric distribution in one direction (abnormally largefor size or abnormally low for function parameters).Using the SD derived from healthy people leads toabnormally low cut-off values, which are inconsis-tent with clinical experience, as the SD inadequatelyrepresents the magnitude of asymmetry (or range of

values) toward abnormality. This is the case with LVejection fraction (EF) where 4 SD below the mean(64 6.5) results in a cutoff for severely abnormalof 38%.

An alternative method would be to define abnor-malities based on percentile values (eg, 95th, 99th)of measurements derived from a population thatincludes both healthy people and those with diseasestates.11 Although these data may still not be gauss-ian, they account for the asymmetric distributionand range of abnormality present within the generalpopulation. The major limitation of this approach isthat large enough population data sets simply do not

exist for most echocardiographic variables.

Ideally, an approach that would predict outcomesor prognosis would be preferred. That is, defining a

variable as moderately deviated from normal wouldimply that there is a moderate risk of a particularadverse outcome for that patient. Although suffi-cient data linking risk and cardiac chamber sizesexist for several parameters (ie, EF, LV size, left atrial[LA] volume), risk data are lacking for many otherparameters. Unfortunately, this approach continuesto have several limitations. The first obstacle is howto best define risk. The cutoffs suggested for a single

parameter vary broadly for the risk of death, myo-cardial infarction (MI), and atrial fibrillation, amongothers. In addition, much of the risk literatureapplies to specific populations (eg, post-MI, elderly),and not general cardiovascular risk readily applica-ble to consecutive patients studied in an echocardi-ography laboratory. Lastly, although having dataspecifically related to risk is ideal, it is not clear thatthis is necessary. Perhaps cardiac risk increasesinherently as echocardiographic parameters becomemore abnormal. This has been shown for severalechocardiographic parameters (LA dimension, wallthickness, LV size, and LV mass) which, when

partitioned based on population estimates, demon-strated graduated risk, which is often nonlinear.11

Lastly, cut-off values may be determined fromexpert opinion. Although scientifically least rigor-ous, this method takes into account the collectiveexperience of having read and measured tens ofthousands of echocardiograms.

No single methodology could be used for allparameters. The tables of cutoffs represent a con-sensus of a panel of experts using a combination ofthe methods described above (Table 2). The consen-sus values are more robust for some parameters thanothers and future research may redefine the cut-off

values. Despite the limitations, these partition values

Table 2 Methods used to establish cut-off values ofdifferent echocardiographic parameters

SD Percentile Risk

Expert

opinion

Septal wall thickness

LV mass LV dimensions LV volumes LV function linear

method

Ejection fraction RV dimensions PA diameters RV areas RV function LA dimensions LA volumes RA dimensions

LA, Left atrial; LV, left ventricular; RA, right atrial; RV, right ventricular.

Journal of the American Society of Echocardiography1442 Lang et al December 2005


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represent a leap toward the standardization of clin-ical echocardiography.

QUANTIFICATION OF THE LV

LV dimensions, volumes, and wall thicknesses areechocardiographic measurements widely used inclinical practice and research.12,13 LV size and per-formance are still frequently visually estimated.However, qualitative assessment of LV size andfunction may have significant interobserver variabil-ity and is a function of interpreter skill. Therefore, itshould regularly be compared with quantitative mea-surements, especially when different views qualita-tively suggest different degrees of LV dysfunction.Similarly, it is also important to cross-check quanti-

tative data using the eyeball method, to avoid over-emphasis on process-related measurements, whichat times may depend on structures seen in a singlestill frame. It is important to account for the integra-tion over time of moving structures seen in oneplane, and the integration of 3-dimensional (3D)space obtained from viewing a structure in multipleorthogonal planes. Methods for quantitation of LVsize, mass, and function using 2-dimensional (2D)imaging have been validated.14-17

There are distinct advantages and disadvantages toeach of the accepted quantitative methods (Table 3).For example, linear LV measurements have been

widely validated in the management of valvular

heart disease, but may misrepresent dilatation anddysfunction in patients with regional wall-motionabnormalities as a result of coronary artery disease.Thus, laboratories should be familiar with all avail-

able techniques and peer-review literature andshould apply them on a selective basis.

General Principles for Linear and VolumetricLV Measurements

To obtain accurate linear measurements of interven-tricular septal wall thickness (SWT), posterior wallthickness (PWT), and LV internal dimension, record-ings should be made from the parasternal long-axisacoustic window. It is recommended that LV inter-nal dimensions (LVIDd and LVIDs, respectively) and

wall thicknesses be measured at the level of the LVminor axis, approximately at the mitral valve leaflet

tips. These linear measurements can be made di-rectly from 2D images or using 2D-targeted M-modeechocardiography.

By virtue of their high pulse rate, M-mode record-ings have excellent temporal resolution and maycomplement 2D images in separating structuressuch as trabeculae adjacent to the posterior wall,false tendons on the left side of the septum, andtricuspid apparatus or moderator band on the rightside of the septum from the adjacent endocardium.However, it should be recognized that even with 2Dguidance, it may not be possible to align the M-modecursor perpendicular to the long axis of the ventri-

cle, which is mandatory to obtain a true minor-axis

Table 3 Left ventricular quantification methods: Use, advantages, and limitations

Dimension/volumes Use/advantages Limitations

LinearM-mode Reproducible - Beam orientation frequently off axis

- High frame rates

- Wealth of accumulated data

- Single dimension may not be representative in

distorted ventricles- Most representative in normally shaped ventricles

2D-Guided - Assures orientation perpendicular to ventricular longaxis

- Lower frame rates than in M-mode- Single dimension only

VolumetricBiplane Simpsons - Corrects for shape distortions - Apex frequently foreshortened

- Minimizes mathematic assumptions - Endocardial dropout

- Relies on only two planes- Few accumulated data on normal population

Area length - Partial correction for shape distortion - Based on mathematic assumptions- Few accumulated data

MassM-mode or 2D-guided - Wealth of accumulated data - Inaccurate in ventricles with regional

abnormalities

- Beam orientation (M-mode)- Small errors magnified- Overestimates LV mass

Area length - Allows for contribution of papillary muscles - Insensitive to distortion in ventricular shape

Truncated ellipsoid - More sensitive to distortions in ventricular shape - Based on a number or mathematicassumptions

- Minimal normal data

2D, Two-dimensional; LV, left ventricular.



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dimension measurement. Alternatively, chamber di-mension and wall thicknesses can be acquired fromthe parasternal short-axis view using direct 2D mea-surements or targeted M-mode echocardiographyprovided that the M-mode cursor can be positionedperpendicular to the septum and LV posterior wall.

A 2D method, useful for assessing patients withcoronary artery disease, has been proposed. Whenusing this method, it is recommended that LV inter-

nal dimensions (LVIDd and LVIDs, respectively) andwall thicknesses be measured at the level of the LVminor dimension, at the mitral chordae level. Theselinear measurements can also be made directly from2D images or using 2D-targeted M-mode echocardi-ography. Direct 2D minor-axis measurements at thechordae level intersect the interventricular septumbelow the LV outflow tract2,5,18 and, thus, provide aglobal assessment in a symmetrically contracting LV,and evaluate basal regional function in a chamber

with regional wall-motion abnormalities. The direct2D minor-axis dimensions are smaller than the M-mode measurements with the upper limits of normal

of LVIDd being 5.2 versus 5.5 cm and the lowerlimits of normal for fractional shortening (FS) being0.18 versus 0.25. Normal systolic and diastolic mea-surements reported for this parameter are 4.7 0.4cm and 3.3 0.5 cm, respectively.2,18

LVID, SWT, and PWT are measured at end diastoleand end systole from 2D or M-mode recordings,1,2

preferably on several cardiac cycles (Figure 1).1,2

Refinements in image processing have allowed im-proved resolution of cardiac structures. Consequently,it is now possible to measure the actual visualizedthickness of the ventricular septum and other cham-ber dimensions as defined by the actual tissue-blood

interface, rather than the distance between the

leading edge echoes, which had previously beenrecommended.5 Use of 2D echocardiographicallyderived linear dimensions overcomes the commonproblem of oblique parasternal images resulting inoverestimation of cavity and wall dimensions fromM-mode. If manual calibration of images is required,6 cm or larger distances should be used to minimizeerrors caused by imprecise placement of calibrationpoints.

To obtain volumetric measurements, the most

important views for 2D quantitation are the midpap-illary short-axis view and the apical 4- and 2-chamber

views. Volumetric measurements require manualtracing of the endocardial border. The papillarymuscles should be excluded from the myocardiumin the LV mass calculation (Figure 6). Accuratemeasurements require optimal visualization of theendocardial border to minimize the need for extrap-olation. It is recommended that the basal border ofthe LV cavity area be delineated by a straight lineconnecting the mitral valve insertions at the lateraland septal borders of the annulus on the 4-chamber

view and the anterior and inferior annular borders

on the 2-chamber view.

Figure 1 Measurement of left ventricular end-diastolicdiameter (EDD) and end-systolic diameter (ESD) from

M-mode, guided by parasternal short-axis image (upperleft) to optimize medial-lateral beam orientation.

Figure 2 Transesophageal measurements of left ventricu-lar length (L) and minor diameter (LVD) from midesopha-geal 2-chamber view, usually best imaged at multiplaneangle of approximately 60 to 90 degrees.

Figure 3 Transesophageal echocardiographic measure-ments of left ventricular (LV) minor-axis diameter (LVD)from transgastric 2-chamber view of LV, usually best im-aged at angle of approximately 90 to 110 degrees afteroptimizing maximum obtainable LV size by adjustment ofmedial-lateral rotation.



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End diastole can be defined at the onset of theQRS, but is preferably defined as the frame after

mitral valve closure or the frame in the cardiac cyclein which the cardiac dimension is largest. In sinusrhythm, this follows atrial contraction. End systole isbest defined as the frame preceding mitral valveopening or the time in the cardiac cycle in whichthe cardiac dimension is smallest in a normal heart.In the 2-chamber view, mitral valve motion is notalways clearly discernible and the frames with thelargest and smallest volumes should be identified asend diastole and end systole, respectively.

The recommended TEE views for measurement ofLV diameters are the midesophageal (Figure 2) andtransgastric (Figure 3) 2-chamber views. LV diame-

ters are measured from the endocardium of theanterior wall to the endocardium of the inferior wallin a line perpendicular to the long axis of the

ventricle at the junction of the basal and middlethirds of the long axis. The recommended TEE viewfor measurement of LV wall thickness is the trans-gastric midshort-axis view (Figure 4). With TEE, thelong-axis dimension of the LV is often foreshortened inthe midesophageal 4-chamber and long-axis views;therefore, the midesophageal 2-chamber view is pre-ferred for this measurement. Care must be made toavoid foreshortening TEE views, by recording theimage plane that shows the maximum obtainable

chamber size, finding the angle for diameter mea-surement that is perpendicular to the long axis ofthat chamber, then measuring the maximum obtain-able short-axis diameter.

Calculation of LV Mass

In clinical practice, LV chamber dimensions arecommonly used to derive measures of LV systolicfunction, whereas in epidemiologic studies andtreatment trials, the single largest application ofechocardiography has been the estimation of LVmass in populations and its change with antihyperten-sive therapy.13,19 All LV mass algorithms, whether

using M-mode, 2D, or 3D echocardiographic measure-

ments, are based on subtraction of the LV cavityvolume from the volume enclosed by the LV epicar-dium to obtain LV muscle or shell volume. This shell

volume is then converted to mass by multiplying by

myocardial density. Hence, quantitation of LV massrequires accurate identification of interfaces be-tween the cardiac blood pool and endocardium, andbetween epicardium and pericardium.

To date, most LV mass calculations have beenmade using linear measurements derived from 2D-targeted M-mode or, more recently, from 2D linearLV measurements.20 The ASE-recommended formulafor estimation of LV mass from LV linear dimensions(validated with necropsy r 0.90, P .00121) isbased on modeling the LV as a prolate ellipse ofrevolution:

LV mass 0.8 {1.04[(LVIDd PWTd SWTd)3

(LVIDd)3]} 0.6 g

where PWTd and SWTd are posterior wall thicknessat end diastole and septal wall thickness at enddiastole, respectively. This formula is appropriatefor evaluating patients without major distortions ofLV geometry (eg, patients with hypertension). Be-cause this formula requires cubing primary measure-ments, even small errors in these measurements aremagnified. Calculation of relative wall thickness(RWT) by the formula (2PWTd)/LVIDd permitscategorization of an increase in LV mass as eitherconcentric (RWT 0.42) or eccentric (RWT

0.42) hypertrophy and allows identification of con-

Figure 4 Transesophageal echocardiographic measure-ments of wall thickness of left ventricular (LV) septal wall(SWT) and posterior wall (PWT) from transgastric short-axis view of LV, at papillary muscle level, usually bestimaged at angle of approximately 0 to 30 degrees.

Figure 5 Comparison of relative wall thickness (RWT).Patients with normal left ventricular (LV) mass can haveeither concentric remodeling (normal LV mass with in-creased RWT 0.42) or normal geometry (RWT 0.42)and normal LV mass. Patients with increased LV masscan have either concentric (RWT 0.42) or eccentric(RWT 0.42) hypertrophy.These LV mass measurementsare based on linear measurements.



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centric remodeling (normal LV mass with increasedRWT) (Figure 5).22

The most commonly used 2D methods for mea-

suring LV mass are based on the area-length formulaand the truncated ellipsoid model, as described indetail in the 1989 ASE document on LV quantita-tion.2 Both methods were validated in the early1980s in animal models and by comparing premor-bid echocardiograms with measured LV weight atautopsy in human beings. Both methods rely onmeasurements of myocardial area at the midpapil-lary muscle level. The epicardium is traced to obtainthe total area (A1) and the endocardium is traced toobtain the cavity area (A2). Myocardial area (Am) iscomputed as the difference: Am A1 A2. Assuminga circular area, the radius is computed: b A2/,

and a mean wall thickness derived (Figure 6). LV masscan be calculated by one of the two formulas shownin Figure 6. In the presence of extensive regional

wall-motion abnormalities (eg, MI), the biplaneSimpsons method may be used, although thismethod is dependent on adequate endocardial andepicardial definition of the LV, which often is chal-lenging from this window. Most laboratories obtainthe measurement at end diastole and exclude thepapillary muscles in tracing the myocardial area.

TEE evaluation of LV mass is also highly accurate,but has minor systematic differences in LV PWT. Inparticular, LV mass derived from TEE wall-thickness

measurements is higher by an average of 6 g/m

2

.

8

LV Systolic Function: Linear and VolumetricMeasurement

Many echocardiography laboratories rely on M-modemeasurements or linear dimensions derived from the2D image for quantification. Linear measurements

from M-mode and 2D images have proven to bereproducible with low intraobserver and interobserver

variability.20,23-26 Although linear measures of LVfunction are problematic when there is a markedregional difference in function, in patients withuncomplicated hypertension, obesity, or valvulardiseases, such regional differences are rare in theabsence of clinically recognized MI. Hence, FS andits relationship to end-systolic stress often provideuseful information in clinical studies.27 The previ-ously used Teichholz or Quinones methods of cal-culating LV EF from LV linear dimensions may resultin inaccuracies as a result of the geometric assump-

tions required to convert a linear measurement to a3D volume.28,29 Accordingly, the use of linear mea-surements to calculate LV EF is not recommendedfor clinic practice.

Contraction of muscle fibers in the LV midwallmay better reflect intrinsic contractility than con-traction of fibers at the endocardium. Calculation ofmidwall rather than endocardial FS is particularlyuseful in revealing underlying systolic dysfunction inthe setting of concentric hypertrophy.30 Midwallfraction and shortening (MWFS) may be computedfrom linear measures of diastolic and systolic cavitysizes and wall thicknesses based on mathematic

models,

30,31

according to the following formulas:

Figure 6 Two methods for estimating LV mass based onarea-length (AL) formula and the truncated ellipsoid (TE)formula, from short-axis (left) and apical four-chamber(right) 2-D echo views. Where A1 total LV area; A2

LV cavity area, Am myocardial area, a is the long orsemi-major axis from widest minor axis radius to apex, b isthe short-axis radius (back calculated from the short-axiscavity area) and d is the truncated semimajor axis fromwidest short-axis diameter to mitral anulus plane. Assuminga circular area, the radius (b) is computed and mean wallthickness (t) derived from the short-axis epicardial andcavity areas. See text for explanation.

Figure 7 Two-dimensional measurements for volume cal-culations using biplane method of disks (modified Simp-sons rule) in apical 4-chamber (A4C) and apical 2-cham-ber (A2C) views at end diastole (LV EDD) and at endsystole (LV ESD). Papillary muscles should be excludedfrom the cavity in the tracing.



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Inner shell [(LVIDd SWTd 2 PWTd 2)3 LVIDd3 LVIDs3]13 LVIDs

MWFS([LVIDd SWTd 2 PWTd 2] [LVIDs inner shell])

LVIDd SWTd 2 PWTd 2) 100

The most commonly used 2D measurement forvolume measurements is the biplane method of disks(modified Simpsons rule) and is the currently rec-ommended method of choice by consensus of thiscommittee (Figure 7). The principle underlying thismethod is that the total LV volume is calculated fromthe summation of a stack of elliptical disks. The

height of each disk is calculated as a fraction (usually1/20) of the LV long axis based on the longer of thetwo lengths from the 2- and 4-chamber views. Thecross-sectional area of the disk is based on the twodiameters obtained from the 2- and 4-chamber

views. When two adequate orthogonal views are notavailable, a single plane can be used and the area ofthe disk is then assumed to be circular. The limita-tions of using a single plane are greatest whenextensive wall-motion abnormalities are present.

An alternative method to calculate LV volumeswhen apical endocardial definition precludes ac-curate tracing is the area-length method where the

LV is assumed to be bullet-shaped. The mid-LVcross-sectional area is computed by planimetry inthe parasternal short-axis view and the length ofthe ventricle taken from the midpoint of the annulusto the apex in the apical 4-chamber view. Thesemeasurements are repeated at end diastole and endsystole, and the volume is computed according to theformula: volume [5 (area) (length)]/6. The most

widely used parameter for indexing volumes is thebody surface area (BSA) in square meters.

End-diastolic volume (EDV) and end-systolic vol-ume (ESV) are calculated by either of the twomethods described above and the EF is calculated

as follows:

Ejection fraction (EDV ESV) EDV

Partition values forrecognizing depressed LV systolicfunction in Table 6 follow the conventional practice ofusing the same cutoffs in women and men; however,emerging echocardiographic and magnetic reso-nance imaging (MRI) data suggest that LV EF andother indices are somewhat higher in apparentlyhealthy women than in men.32,33 Quantitation of LV

volumes using TEE is challenging because of difficul-ties in obtaining a nonforeshortened LV cavity from

the esophageal approach. However, when carefullyacquired, direct comparisons between TEE and TTE

volumes and EF have shown minor or no significantdifferences.8,9

References Values for LV Measurements

As shown in Tables 4-6, reference values for LVlinear dimensions have been obtained from an ethni-cally diverse population of 510 normal-weight, normo-tensive, and nondiabetic white, African American, and

American Indian adults without recognized cardiovas-cular disease (unpublished data). The populationsfrom which these data have been derived have been

described in detail previously.20,34-36

Reference val-ues for volumetric measurements have also beenobtained in a healthy adult population.37

Normal values for LV mass differ between menand women even when indexed for BSA (Table 4).The best method for normalizing LV mass measure-ments in adults is still debated. Although BSA hasbeen most often used in clinical trials, this method

will underestimate the prevalence of LV hypertro-phy in overweight and obese individuals. The abilityto detect LV hypertrophy related to obesity and tocardiovascular diseases is enhanced by indexing LVmass for the power of its allometric or growth

relation with height (height

2.7

). Data are inconclusive

Table 4 Reference limits and partition values of left ventricular mass and geometry

Women Men

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Linear MethodLV mass, g 67162 163186 187210 211 88224 225258 259292 293

LV mass/BSA, g/m2 4395 96108 109121 >122 49115 116131 132148 >149

LV mass/height, g/m 4199 100115 116128 129 52126 127144 145162 163LV mass/height2,7, g/m2,7 1844 4551 5258 59 2048 4955 5663 64Relative wall thickness, cm 0.220.42 0.430.47 0.480.52 0.53 0.240.42 0.430.46 0.470.51 0.52Septal thickness, cm 0.60.9 1.01.2 1.31.5 >1.6 0.61.0 1.11.3 1.41.6 >1.7

Posterior wall thickness, cm 0.60.9 1.01.2 1.31.5 >1.6 0.61.0 1.11.3 1.41.6 >1.7

2D MethodLV mass, g 66150 151171 172182 193 96200 201227 228254 255LV mass/BSA, g/m2 4488 89100 101112 >113 50102 103116 117130 >131

BSA, Body surface area; LV, left ventricular; 2D, 2-dimensional.

Bold italic values: Recommended and best validated.



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as to whether such indexing of LV mass may improve

or attenuate prediction of cardiovascular events. Ofnote, the reference limits for LV mass in Table 4 arelower than those published in some previous echocar-diographic studies, yet are virtually identical to thosebased on direct necropsy measurement and cut-off

values used in clinical trials.19,20,36,38,39 Althoughsome prior studies have suggested racial differencesin LV mass measurement, the consensus of theliterature available indicates that no significant dif-ferences exist between clinically healthy African

American and Caucasian people. In contrast, a re-cent study has shown racial-ethnic differences in LVstructure in adults with hypertension.40 Although

the sensitivity, specificity, and predictive value of LVwall-thickness measurements for detection of LVhypertrophy are lower than for calculated LV mass,it is sometimes easiest in clinical practice to identifyLV hypertrophy by measuring an increased LV pos-terior and septal thickness.41

The use of LV mass in children is complicated bythe need for indexing the measurement relative topatient body size. The intent of indexing is toaccount for normal childhood growth of lean bodymass without discounting the pathologic effects ofpatients who are overweight or obese. In this way,an indexed LV mass measurement in early childhood

can be directly compared with a subsequent mea-

surement during adolescence and adulthood. Divid-

ing LV mass by height (meters) increased to a powerof 2.5 to 3.0 is the most widely accepted indexingmethod in older children and adolescents because itcorrelates best to indexing LV mass to lean bodymass.42 Currently an intermediate value of 2.7 isgenerally used.43,44 In younger children (8 yearsold), the most ideal indexing factor remains an areaof research, but height increased to a power of 2.0appears to be the most appropriate.45

Three-dimensional Assessment of Volumeand Mass

Three-dimensional chamber volume and mass areincompletely characterized by 1-dimensional or 2Dapproaches, which are based on geometric assump-tions. Although these inaccuracies have been con-sidered inevitable and of minor clinical importancein the past, in most situations accurate measure-ments are required, particularly when following thecourse of a disease with serial examinations. Duringthe last decade, several 3D echocardiographic tech-niques became available to measure LV volumes andmass.46-59 These can be conceptually divided intotechniques, which are based on offline reconstruc-tion from a set of 2D cross sections, or online data

acquisition using a matrix-array transducer, also

Table 5 Reference limits and partition values of left ventricular size

Women Men

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

LV dimensionLV diastolic diameter 3.95.3 5.45.7 5.86.1 6.2 4.25.9 6.06.3 6.46.8 6.9LV diastolic diameter/BSA, cm/m2 2.43.2 3.33.4 3.53.7 3.8 2.23.1 3.23.4 3.53.6 3.7

LV diastolic diameter/height, cm/m 2.53.2 3.33.4 3.53.6 3.7 2.43.3 3.43.5 3.63.7 3.8LV volume

LV diastolic volume, mL 56104 105117 118130 131 67155 156178 179201 201LV diastolic volume/BSA, mL/m2 3575 7686 8796 >97 3575 7686 8796 >97

LV systolic volume, mL 1949 5059 6069 70 2258 5970 7182 83LV systolic volume/BSA, mL/m2 1230 3136 3742 >43 1230 3136 3742 >43

BSA, body surface area; LV, left ventricular.


Table 6 Reference limits and values and partition values of left ventricular function

Women Men

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Linear methodEndocardial fractional shortening, % 2745 2226 1721 16 2543 2024 1519 14Midwall fractional shortening, % 1523 1314 1112 10 1422 1213 1011 10

2D Method

Ejection fraction, % >55 4554 3044 55 4554 3044


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known as real-time 3D echocardiography. After ac-quisition of the raw data, calculation of LV volumesand mass requires identification of endocardial bor-ders (and for mass epicardial border) using manualor semiautomated algorithms. These borders arethen processed to calculate the cavity or myocardial

volume by summation of disks54,56 or other meth-ods.46-48

Regardless of which acquisition or analysis methodis used, 3D echocardiography does not rely on geo-metric assumptions for volume/mass calculationsand is not subject to plane positioning errors,

which can lead to chamber foreshortening. Stud-

ies comparing 3D echocardiographic LV volumes

or mass with other gold standards (eg, MRI) haveconfirmed 3D echocardiography to be accurate.Compared with magnetic resonance data, LV andright ventricular (RV) volumes calculated from 3Dechocardiography showed significantly betteragreement (smaller bias), lower scatter, and lowerintraobserver and interobserver variability than 2Dechocardiography.46,54,57,60 The superiority of 3Dechocardiographic LV mass calculations over valuescalculated from M-mode or 2D echocardiographyhas been convincingly shown.55,57,59 RV volume andmass have also been measured by 3D echocardiogra-phywith good agreement with magnetic resonance

data.

58,61

Current limitations include the require-

Figure 8 Segmental analysis of LV walls based on schematic views, in a parasternal short- and long-axisorientation, at 3 different levels. The apex segments are usually visualized from apical 4-chamber, apical2 and 3-chamber views. The apical cap can only be appreciated on some contrast studies. A 16-segmentmodel can be used, without the apical cap, as described in an ASE 1989 document.2A 17-segment model,including the apical cap, has been suggested by the American Heart Association Writing Group onMyocardial Segmentation and Registration for Cardiac Imaging.62

Figure 9 Typical distributions of the right coronary artery (RCA), the left anterior descending (LAD),and the circumflex (CX) coronary arteries. The arterial distribution varies between patients. Somesegments have variable coronary perfusion.



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ment of regular rhythm, relative inferior image qual-ity of real-time 3D echocardiography compared with2D images, and the time necessary for offline dataanalysis. However, the greater number of acquireddata points, the lack of geometric assumptions,

increasingly sophisticated 3D image, and measure-ments solutions offset these limitations.

Regional LV Function

In 1989, the ASE recommended a 16-segment modelfor LV segmentation.2 This model consists of 6segments at both basal and midventricular levels and4 segments at the apex (Figure 8). The attachmentof the RV wall to the LV defines the septum,

which is divided at basal and mid-LV levels intoanteroseptum and inferoseptum. Continuingcounterclockwise, the remaining segments atboth basal and midventricular levels are labeled asinferior, inferolateral, anterolateral, and anterior.The apex includes septal, inferior, lateral, andanterior segments. This model has become widelyused in echocardiography. In contrast, nuclear per-fusion imaging, cardiovascular magnetic resonance,and cardiac computed tomography have commonlyused a larger number of segments.

In 2002, the American Heart Association WritingGroup on Myocardial Segmentation and Registrationfor Cardiac Imaging, in an attempt to establish segmen-tation standards applicable to all types of imaging,recommended a 17-segment model (Figure 8).62 Thisdiffers from the previous 16-segment model predom-inantly by the addition of a 17th segment, the apicalcap. The apical cap is the segment beyond the endof the LV cavity. Refinements in echocardiographicimaging, including harmonics and contrast imaging,are believed to permit improved imaging of theapex. Either model is practical for clinical applica-tion yet sufficiently detailed for semiquantitativeanalysis. The 17-segment model should be predom-inantly used for myocardial perfusion studies or anytime efforts are made to compare between imagingmodalities. The 16-segment model is appropriate forstudies assessing wall-motion abnormalities, as the

tip of the normal apex (segment 17) does not move.The mass and size of the myocardium as assessedat autopsy is the basis for determining the distribu-tion of segments. Sectioned into basal, midventricu-lar, and apical thirds, perpendicular to the LV longaxis, with the midventricular third defined by thepapillary muscles, the measured myocardial mass inadults without cardiac disease was 43% for the base,36% for the midcavity, and 21% for the apex.63 The16-segment model closely approximates this, creat-ing a distribution of 37.5% for both the basal andmidportions and 25% for the apical portion. The17-segment model creates a distribution of 35.3%,

35.3%, and 29.4% for the basal, mid, and apical

portions (including the apical cap) of the heart,respectively.

Variability exists in the coronary artery bloodsupply to myocardial segments. Nevertheless, thesegments are usually attributed to the 3 major

coronary arteries are shown in the TTE distributionsof Figure 9.62

Since the 1970s, echocardiography has been usedfor the evaluation of LV regional wall motion duringinfarction and ischemia.64-66 It is recognized thatregional myocardial blood flow and regional LVsystolic function are related over a wide range ofblood flows.67Although regional wall-motion abnor-malities at rest may not be seen until the luminaldiameter stenosis exceeds 85%, with exercise, acoronary lesion of 50% can result in regional dys-function. It is recognized that echocardiography canoverestimate the amount of ischemic or infarcted

myocardium, as wall motion of adjacent regions maybe affected by tethering, disturbance of regionalloading conditions, and stunning.68 Therefore, wallthickening and motion should be considered. More-over, it should be remembered that regional wall-motion abnormalities may occur in the absence ofcoronary artery disease.

It is recommended that each segment be analyzedindividually and scored on the basis of its motionand systolic thickening. Ideally, the function of eachsegment should be confirmed in multiple views. Seg-ment scores are as follows: normal or hyperkinesis 1, hypokinesis 2, akinesis (negligible thickening) 3, dyskinesis (paradoxical systolic motion) 4, andaneurysmal (diastolic deformation) 5.1 Wall-motionscore index can be derived as a sum of all scoresdivided by the number of segments visualized.

Assessment of LV Remodeling and the Use ofEchocardiography in Clinical Trials

LV remodeling describes the process by which theheart changes its size, geometry, and function overtime. Quantitative 2D TTE enables characterizationof LV remodeling that occurs in healthy individualsand in a variety of heart diseases. LV remodeling maybe physiologic when the heart increases in size but

maintains normal function during growth, physicaltraining, and pregnancy. Several studies have dem-onstrated that both isometric and isotonic exercisecause remodeling of the LV and RV chamber sizesand wall thicknesses.69-73 These changes in highlytrained, elite athlete hearts are directly related to thetype and duration of exercise and have been char-acterized echocardiographically. With isometric ex-ercise, a disproportionate increase occurs in LVmass compared with the increase in LV diastolic

volume, resulting in significantly greater wall thick-ness to cavity size ratio (h/R ratio) than takes placein healthy nonathletic individuals with no change in

ejection phase indices of LV contractile func-



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tion.69-73 This physiologic hypertrophic remodelingof the athlete heart is reversible with cessation ofendurance training and is related to the total in-crease in lean body weight,70 and triggered byenhanced cardiac sympathetic activity.74 Remodel-

ing may be compensatory in chronic pressure over-load because of systemic hypertension or aorticstenosis resulting in concentric hypertrophy (in-creased wall thickness, normal cavity volume, andpreserved EF) (Figure 5). Compensatory LV remod-eling also occurs in chronic volume overload asso-ciated with mitral or aortic regurgitation, whichinduces a ventricular architecture characterized byeccentric hypertrophy, LV chamber dilatation, andinitially normal contractile function. Pressure and

volume overload may remain compensated by ap-propriate hypertrophy, which normalizes wall stresssuch that hemodynamics and EF remain stable dur-

ing the long term. However, in some patients,chronically increased afterload cannot be normal-ized indefinitely and the remodeling process be-comes pathologic.

Transition to pathologic remodeling is heraldedby progressive ventricular dilatation, distortion ofcavity shape, and disruption of the normal geometryof the mitral annulus and subvalvular apparatusresulting in mitral regurgitation. The additional vol-ume load from mitral regurgitation escalates thedeterioration in systolic function and developmentof heart failure. LV dilatation begets mitral regurgi-tation and mitral regurgitation begets further LV

dilatation, progressive remodeling, and contractiledysfunction.Changes in LV size and geometry caused by hyper-

tension (Figure 5) reflect the dominant underlyinghemodynamic alterations associated with blood pres-sure elevation.22,75 The pressure overload pattern ofconcentric hypertrophy is uncommon in otherwisehealthy individuals with hypertension and is associ-ated with high systolic blood pressure and highperipheral resistance. In contrast, eccentric LV hy-pertrophy is associated with normal peripheral re-sistance but high cardiac index consistent withexcess circulating blood volume. Concentric remod-

eling (normal LV mass with increased RWT) is charac-terized by high peripheral resistance, low cardiacindex, and increased arterial stiffness.76,77

A unique form of remodeling occurs after MI asa result of the abrupt loss of contracting myo-cytes.22,78 Early expansion of the infarct zone isassociated with early LV dilatation as the increasedregional wall stress is redistributed to preservestroke volume. The extent of early and late postin-farction remodeling is determined by a number offactors, including size and location of infarction,activation of the sympathetic nervous system, andup-regulation of the renin/angiotensin/aldosterone

system and natriuretic peptides. Between a half and

a third of patients postinfarction experience pro-gressive dilatation79,80 with distortion of ventriculargeometry and secondary mitral regurgitation. Mitralregurgitation further increases the propensity for dete-rioration in LV function and development of conges-tive heart failure. Pathologic LV remodeling is the finalcommon pathway to heart failure, whether the initialstimulus is chronic pressure, chronic volume overload,

genetically determined cardiomyopathy, or MI. Thecause of LV dysfunction in approximately two thirds ofthe 4.9 million patients with heart failure in the UnitedStates is coronary artery disease.81

Although LV remodeling in patients with chronicsystemic hypertension, chronic valvular regurgita-tion, and primary cardiomyopathies has been de-scribed, the transition to heart failure is less wellknown because the time course is so prolonged. Bycontrast, the time course from MI to heart failure isshorter and has been clearly documented.

The traditional quantitative echocardiographic mea-surements recommended for the evaluation of LV

remodeling included estimates of LV volumes either

Figure 10 Methods of measuring right ventricular wallthickness (arrows) from M-mode (left) and subcostal trans-thoracic (right) echocardiograms.

Figure 11 Midright ventricular diameter measured in api-cal 4-chamber view at level of left ventricular papillarymuscles.



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from biplane or single plane images as advocated bythe ASE. Although biplane and single plane volumeestimations are not interchangeable, both estimates areequally sensitive for detecting time-dependent LV re-modeling and deteriorating contractile function.77 LV

volumes and derived EF have been demonstrated topredict adverse cardiovascular events at follow-up,including death, recurrent infarction, heart failure,

ventricular arrhythmias, and mitral regurgitation innumerous postinfarction and heart failure trials.78-81

This committee recommends the use of quantitativeestimation of LV volumes, LV EF, LV mass, and shape asdescribed in the respective sections above to follow LVremodeling induced by physiologic and pathologicstimuli. In addition, these measurements provide prog-nostic information incremental to that of baselineclinical demographics.

QUANTIFICATION OF THE RV AND RVOUTFLOW TRACT

The normal RV is a complex crescent-shapedstructure wrapped around the LV and is incom-pletely visualized in any single 2D echocardio-

graphic view. Thus, accurate assessment of RV

morphology and function requires integration ofmultiple echocardiographic views, includingparasternal long- and short-axis, RV inflow, apical4-chamber, and subcostal. Although multiplemethods for quantitative echocardiographic RVassessment have been described, in clinical prac-tice assessment of RV structure and functionremains mostly qualitative. Nevertheless, numer-ous studies have recently emphasized the impor-tance of RV function in the prognosis of a varietyof cardiopulmonary diseases suggesting that moreroutine quantification of RV function is warrantedunder most clinical circumstances.

Compared with the LV, the RV is a thin-walledstructure under normal conditions. The normalRV is accustomed to a low pulmonary resistanceand, hence, low afterload; thus, normal RV pres-sure is low and RV compliance high. The RV is,therefore, sensitive to changes in afterload, andalterations in RV size and function are indicatorsof increased pulmonary vascular resistance andload transmitted from the left-sided chambers.Elevations in RV afterload in adults are manifestedacutely by RV dilatation and chronically by con-centric RV hypertrophy. In addition, intrinsic RVabnormalities, such as infarction or RV dysplasia82

can cause RV dilatation or reduced RV wall thick-

Figure 12 Transesophageal echocardiographic measure-ments of right ventricular (RV) diameters from midesopha-geal 4-chamber view, best imaged afteroptimizing maximumobtainable RV size by varying angles from approximately 0 to20 degrees.

Table 7 Reference limits and partition values of right ventricular and pulmonary artery size

Reference range Mildly abnormal Moderately abnormal Severely abnormal

RV dimensions (Figure 12)Basal RV diameter (RVD 1), cm 2.02.8 2.93.3 3.43.8 3.9Mid-RV diameter (RVD 2), cm 2.73.3 3.43.7 3.84.1 4.2

Base-to-apex length (RVD 3), cm 7.17.9 8.08.5 8.69.1 9.2RVOT diameters (Figure 13, 14)

Above aortic valve (RVOT 1), cm 2.52.9 3.03.2 3.33.5 3.6Above pulmonic valve (RVOT 2), cm 1.72.3 2.42.7 2.83.1 3.2

PA diameterBelow pulmonic valve (PA 1), cm 1.52.1 2.22.5 2.62.9 3.0

RV, Right ventricular; RVOT, right ventricular outflow tract; PA, pulmonary artery.

Data from Foale et al.76

Table 8 Reference limits and partition values of rightventricular size and function as measured in the apical4-chamber view

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

RV diastolic area,

cm21128 2932 3337 38

RV systolic area,cm2

7.516 1719 2022 23

RV fractional areachange, %

3260 2531 1824 17

RV, Right ventricular.

Data from Weyman.80



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ness. Thus, assessment of RV size and wall thick-ness is integral to the assessment of RV function.

RV free wall thickness, normally less than 0.5cm, is measured using either M-mode or 2Dimaging. Although RV free wall thickness can beassessed from the apical and parasternal long-axis

views, the subcostal view measured at the peak ofthe R wave at the level of the tricuspid valvechordae tendinae provides less variation andclosely correlates with RV peak systolic pressure

(Figure 10).75

Care must be taken to avoid over-measurement because of the presence of epicar-dial fat deposition and coarse trabeculations

within the RV.Qualitative assessment of RV size is easily ac-

complished from the apical 4-chamber view (Fig-ure 11). In this view, RV area or midcavity diam-eter should be smaller than that of the LV. In casesof moderate enlargement, the RV cavity area issimilar to that of the LV and it may share the apexof the heart. As RV dilation progresses, the cavityarea will exceed that of the LV and the RV will beapex forming. Quantitative assessment of RV size

is also best performed in the apical 4-chamber

view. Care must be taken to obtain a true nonfore-shortened apical-4 chamber view, oriented toobtain the maximum RV dimension, before mak-ing these measurements. Measurement of the mid-cavity and basal RV diameter in the apical 4-cham-

ber view at end diastole is a simple method toquantify RV size (Figure 11). In addition, RVlongitudinal diameter can be measured from this

view. Table 7 provides normal R V dimensionsfrom the apical 4-chamber view.76,80,83

RV size may be assessed may be assessed withTEE in the midesophageal 4-chamber view (Figure12). Midesophageal 4-chamber view, which gen-erally parallels what is obtainable from the apical4-chamber view, should originate at the mid-LAlevel and pass through the LV apex with themultiplane angle adjusted to maximize the tricus-pid annulus diameterusually between 10 and 20

degrees.RV systolic function is generally estimated qual-itatively in clinical practice. When the evaluationis based on a qualitative assessment, the displace-ment of the tricuspid annulus should be observed.In systole, the tricuspid annulus will normallydescend toward the apex 1.5 to 2.0 cm. Tricuspidannular excursion of less than 1.5 cm has beenassociated with poor prognosis in a variety ofcardiovascular diseases.84 Although a number oftechniques exist for accurate quantitation, directcalculation of RV volumes and EF remains prob-lematic given the complex geometry of the RV

and the lack of standard methods for assessing RVvolumes. Nevertheless, a number of echocardio-graphic techniques may be used to assess RVfunction. RV fractional area change measured inthe apical 4-chamber view is a simple method forassessment of RV function that has correlated withRV EF measured by MRI (r 0.88) and has beenrelated to outcome in a number of diseasestates.81,85 Normal RV areas and fractional areachange are shown in Table 8. Additional assess-ment of the RV systolic function includes tissueimaging of tricuspid annular velocity or RV indexof myocardial performance (Tei index).86

RV outflow tract (RVOT) extends from theanterosuperior aspect of the RV to the pulmonaryartery, and includes the pulmonary valve. It is bestimaged from the parasternal long-axis view angledsuperiorly, and the parasternal short axis at thebase of the heart. It can also be imaged from thesubcostal long and transverse windows and theapical window. Measurement of the RVOT is mostaccurate from the parasternal short axis (Figure13) just proximal to the pulmonary valve. MeanRVOT measurements are shown in Table 7.75 WithTEE, the midesophageal RV inflow-outflow viewusually provides the best image of the RVOT just

proximal to the pulmonary valve (Figure 14).

Figure 13 Measurement of right ventricular outflow tractdiameter at subpulmonary region (RVOT1) and pulmonicvalve annulus (RVOT2) in midesophageal aortic valveshort-axis view, using multiplane angle of approximately 45to 70 degrees.

Figure 14 Measurement of right ventricular outflow tractat pulmonic valve annulus (RVOT2) and main pulmonary

artery from parasternal short-axis view.



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QUANTIFICATION OF LEFT ATRIAL ANDRIGHT ATRIAL SIZE

The LA fulfills 3 major physiologic roles that impacton LV filling and performance. The LA acts as acontractile pump that delivers 15% to 30% of the LVfilling, as a reservoir that collects pulmonary venous

return during ventricular systole, and as a conduitfor the passage of stored blood from the LA to the LVduring early ventricular diastole.87 Increased LA size isassociated with adverse cardiovascular outcomes.88-90

An increase in atrial size most commonly is related toincreased wall tension as a result of increased fillingpressure.91,92 Although increased filling volumes cancause an increase in LA size, the adverse outcomesassociated with increased dimension and volume aremore strongly associated with increased filling pres-sure. Relationships exist between increased LAsize and the incidence of atrial fibrillation andstroke,93-101 risk of overall mortality after MI,102,103

and risk of death and hospitalization in patients withdilated cardiomyopathy.104-108 LA enlargement is amarker of both the severity and chronicity of dia-stolic dysfunction and magnitude of LA pressureelevation.88,91,92

The LA size is measured at the end-ventricularsystole when the LA chamber is at its greatestdimension. While recording images for computingLA volume, care should be taken to avoid foreshort-ening of the LA. The base of the LA should be at itslargest size indicating that the imaging plane passesthrough the maximal short-axis area. The LA lengthshould also be maximized ensuring alignment along

the true long axis of the LA. When performing

planimetry, the LA, the confluences of the pulmo-nary veins, and LA appendage should be excluded.With TEE, the LA frequently cannot fit in its

entirety into the image sector. Measurements of LAvolume from this approach cannot be reliably per-formed; however, LA dimension can be estimatedcombining measurements from different imagingplanes.

LA Linear Dimension

The LA can be visualized from multiple echocardio-graphic views from which several potential LA di-mensions can be measured. However, the large

volume of prior clinical and research work used

Figure 15 Measurement of left atrial diameter (LAD)

from M-mode, guided by parasternal short-axis image (up-per right) at level of aortic valve. Linear method is notrecommended.

Figure 16 Measurement of left atrial (LA) volume fromarea-length (L) method using apical 4-chamber (A4C) andapical 2-chamber (A2C) views at ventricular end systole(maximum LA size). L is measured from back wall to lineacross hinge points of mitral valve. Shorter L from eitherA4C or A2C is used in equation.



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M-mode or 2D anteroposterior (AP) linear dimen-sion obtained from the parasternal long-axis view,making this the standard for linear LA measurement(Figure 15).93,95,96,98,104,105 The convention for M-mode measurement is to measure from the leadingedge of the posterior aortic wall to the leading edgeof the posterior LA wall. However, to avoid the

variable extent of space between the LA and aorticroot, the trailing edge of the posterior aortic isrecommended.

Although these linear measurements have beenshown to correlate with angiographic measure-ments and have been widely used in clinical practiceand research, they inaccurately represent true LAsize.109,110 Evaluation of the LA in the AP dimensionassumes that a consistent relationship is maintainedbetween the AP dimension and all other LA dimen-sions as the atrium enlarges, which is often not thecase.111,112 Expansion of the LA in the AP dimensionmay be constrained by the thoracic cavity betweenthe sternum and the spine. Predominant enlarge-ment in the superior-inferior and medial-lateral di-mensions will alter LA geometry such that the AP

dimension may not be representative of LA size. Forthese reasons, AP linear dimensions of the LA as thesole measure of LA size may be misleading andshould be accompanied by LA volume determina-tion in both clinical practice and research.

LA Volume Measurements

When LA size is measured in clinical practice,volume determinations are preferred over lineardimensions because they allow accurate assessmentof the asymmetric remodeling of the LA chamber.111

In addition, the strength of the relationship betweencardiovascular disease is stronger for LA volume

than for LA linear dimensions.

97,113

Echocardio-

graphic measures of LA volume have been com-pared with cinecomputed tomography, biplane con-trast ventriculography, and MRI.109,114-116 Thesestudies have shown either good agreement or atendency for echocardiographic measurements to

underestimate comparative LA volumes.The simplest method for estimating LA volume is

the cube formula, which assumes that the LA volumeis that of a sphere with a diameter equal to the LA APdimension. However, this method has proven to beinferior to other volume techniques.109,111,117 LA vol-umes are best calculated using either an ellipsoidmodel or Simpsons rule.88,89,97,101,102,109-111,115-117

The ellipsoid model assumes that the LA can beadequately represented as a prolate ellipse with a

volume of 4/3 (L/2) (D1/2) (D2/2), where L is thelong axis (ellipsoid) and D1 and D2 are orthogonalshort-axis dimensions. LA volume can be estimated

using this biplane dimension-length formula by sub-stituting the LA AP diameter acquired from theparasternal long axis as D1, LA medial-lateral dimen-sion from the parasternal short-axis as D2, and the LAlong-axis from the apical 4-chamber for L.117-119

Simplified methods using nonorthogonal linear mea-surements for estimation of LA volume have beenproposed.113 Volume determined using linear di-mensions is very dependent on careful selection ofthe location and direction of the minor-axis dimen-sions and has been shown to significantly underes-timate LA volume.117

To estimate the LA minor-axis dimension of the

ellipsoid more reliably, the long-axis LA areas can betraced and a composite dimension derived. Thisdimension takes into account the entire LA border,rather than a single linear measurement. Whenlong-axis area is substituted for minor-axis dimen-sion, the biplane area-length formula is used: 8 (A1)(A2)/3 (L), where A1 and A2 represent the maximalplanimetered LA area acquired from the apical 4- and2-chamber views, respectively, and L is length. Thelength remains the LA long-axis length determinedas the distance of the perpendicular line measuredfrom the middle of the plane of the mitral annulus tothe superior aspect of the LA (Figure 16). In the

area-length formula the length is measured in boththe 4- and 2-chamber views and the shortest of these2 length measurements is used in the formula.

The area-length formula can be computed from asingle plane, typically the apical 4-chamber, byassuming A1 A2, such that volume 8 (A1)

2/3(L) (Figure 16).120 However, this method makesgeometric assumptions that may be inaccurate. Inolder individuals the diaphragm lifts the cardiacapex upward, which increases the angle between

ventricle and atrium. Thus, the apical 4-chamberview will commonly intersect the atria tangentiallyin older individuals and result in underestimation of

volume using a single plane technique. Because the

Figure 17 Measurement of left atrial (LA) volume frombiplane method of disks (modified Simpsons rule) using

apical4-chamber (A4C) and apical 2-chamber (A2C) viewsat ventricular end systole (maximum LA size).



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majority of prior research and clinical studies haveused the biplane area-length formula, it is the rec-ommended ellipsoid method (Figures 15 and 16).

LA volume may also be measured using Simpsonsrule, similar to its application for LV measurements,

which states that the volume of a geometric figurecan be calculated from the sum of the volumes of

smaller figures of similar shape. Most commonly,Simpsons algorithm divides the LA into a series ofstacked oval disks whose height is h and whoseorthogonal minor and major axes are D1 and D2(method of disks). The volume of the entire LA canbe derived from the sum of the volume of theindividual disks. Volume /4 (h) (D1) (D2). Theformula is integrated with the aid of a computer andthe calculated volume provided by the softwarepackage online (Figure 17).

The use of the Simpsons method in this wayrequires the input of biplane LA planimetry to derivethe diameters. Optimal contours should be obtained

orthogonally around the long axis of the LA using

TTE apical views. Care should be taken to excludethe pulmonary veins from the LA tracing. The infe-rior border should be represented by the plane ofthe mitral annulus. A single plane method of diskscould be used to estimate LA volume by assumingthe stacked disks are circular V /4 (h) (D1).

2

However, as noted above, this makes the assump-

tion that the LA width in the apical 2- and 4-chamberare identical, which is often not the case and,therefore, this formula is not preferred.

Three-dimensional echocardiography should pro-vide the most accurate evaluation of LA volume andhas shown promise; however, to date no consensusexists on the specific method that should be usedfor data acquisition and there is no comparison withestablished normal values.121-123

Normal Values of LA Measurements

The nonindexed LA linear measurements are takenfrom a Framingham Heart Study cohort of 1099

participants between the ages of 20 and 45 years

Figure 18 Measurement of aortic root diameters at aorticvalve annulus (AV ann) level, sinuses of Valsalva (SinusVal), and sinotubular junction (ST Jxn) from midesopha-geal long-axis view of aortic valve, usually at angle ofapproximately 110 to 150 degrees. Annulus is measured by

convention at base of aortic leaflets. Although leading edgeto leading edge technique is demonstrated for theSinus Valand ST Jxn, some prefer inner edge to inner edge method.(See text for further discussion.)

Figure 19 Measurement of aortic root diameter at sinusesof Valsava from 2-dimensional parasternal long-axis image.Although leading edge to leading edge technique is shown,some prefer inner edge to inner edge method. (See text forfurther discussion.)

Table 9 Reference limits and partition values for left atrial dimensions/volumes

Women Men

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Reference

range

Mildly

abnormal

Moderately

abnormal

Severely

abnormal

Atrial dimensionsLA diameter, cm 2.73.8 3.94.2 4.34.6 4.7 3.04.0 4.14.6 4.75.2 5.2LA diameter/BSA, cm/m2 1.52.3 2.42.6 2.72.9 3.0 1.52.3 2.42.6 2.72.9 3.0

RA minor-axis dimension, cm 2.94.5 4.64.9 5.05.4 5.5 2.94.5 4.64.9 5.05.4 5.5RA minor-axis dimension/BSA, cm/m2 1.72.5 2.62.8 2.93.1 3.2 1.72.5 2.62.8 2.93.1 3.2

Atrial areaLA area, cm2 20 2030 3040 40 20 2030 3040 40

Atrial volumesLA volume, mL 2252 5362 6372 73 1858 5968 6978 79

LA volume/BSA, mL/m2 22 6 2933 3439 >40 22 6 2933 3439 >40

BSA, Body surface area; LA, left atrial; RA, right atrial.




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who were not obese, of average height, and withoutcardiovascular disease (Table 9).11 Slightly higher

values have been reported in a cohort of 767 partici-pants without cardiovascular disease in which obesityand height were not exclusion criteria.113 Both body

size and aging have been noted to influence LAsize.10,87,113 There are also sex differences in LA size;however, these are nearlycompletelyaccounted forby variation in body size.87,113,120,124 The influenceof body size on LA size is typically corrected byindexing to some measure of body size. In fact, fromchildhood onward the indexed atrial volumechanges very little.125 Several indexing methodshave been proposed, such as height, weight, esti-mated lean body mass, and BSA.10,113 The mostcommonly used convention, and that recommendedby this committee, is indexing LA size by dividing byBSA.

Normal indexed LA volume has been determinedusing the preferred biplane techniques (area-length ormethod of disks) in a number of studies involv-ing several hundred patients to be 22 6cc/m2.88,120,126,127 Absolute LA volume has alsobeen reported; however, in clinical practice in-dexing to BSA accounts for variations in body sizeand should, therefore, be used. As cardiac risk andLA size are closely linked, more importantly thansimply characterizing the degree of LA enlarge-ment, normal reference values for LA volumeallow prediction of cardiac risk. There are nowmultiple peer-reviewed articles that validate theprogressive increase in risk associated with havingLA volumes greater than these normative val-ues.89,97,99-103,106-108,128 Consequently, indexedLA volume measurements should become a rou-tine laboratory measure because they reflect theburden and chronicity of elevated LV filling pres-sure and are a strong predictor of outcome.

Right Atrium

Much less research and clinical data are available onquantifying right atrial (RA) size. Although the RAcan be assessed from many different views, quanti-fication of RA size is most commonly performed

from the apical 4-chamber view. The minor-axisdimension should be taken in a plane perpendicularto the long axis of the RA and extends from thelateral border of the RA to the interatrial septum.Normative values for the RA minor axis are shown inTable 9.80,129 Although RA dimension may vary bysex, no separate male and female reference valuescan be recommended at this time.

Although limited data are available for RA vol-umes, assessment of RA volumes would be morerobust and accurate for determination of RA sizethan linear dimensions. As there are no standardorthogonal RA views to use an apical biplane calcu-

lation, the single plane area-length and method of

disks formulas have been applied to RA volumedetermination in several small studies.120,130,131 Webelieve there is too little peer-reviewed validatedliterature to recommend normal RA volumetric val-ues at this time. However, limited data on a small

number of healthy individuals revealed that indexedRA volumes are similar to LA normal values in men(21 mL/m2) but appear to be slightly smaller in

women.120

QUANTIFICATION OF THE AORTA ANDINFERIOR VENA CAVA

Aortic Measurements

Recordings should be made from the parasternallong-axis acoustic window to visualize the aorticroot and proximal ascending aorta. Two-dimen-sional images should be used to visualize the LVoutflow tract and the aortic root should be recordedin different views in varying intercostal spaces and atdifferent distances from the left sternal border. Rightparasternal views, recorded with the patient in aright lateral decubitus position, are also useful.Measurements are usually taken at: (1) aortic valveannulus (hinge point of aortic leaflets); (2) the maximaldiameter in the sinuses of Valsalva; and (3) sinotubular

junction (transition between the sinuses of Valsalvaand the tubular portion of the ascending aorta).

Views used for measurement should be those that

show the largest diameter of the aortic root. Whenmeasuring the aortic diameter, it is particularlyimportant to use the maximum diameter measuredperpendicular to the long axis of the vessel in that

view. Some experts favor inner edge to inner edgetechniques to match those used by other methods ofimaging the aorta, such as MRI and computedtomography scanning. However, the normative datafor echocardiography were obtained using the lead-ing edge technique (Figure 18). Advances in ultra-sound instrumentation that have resulted in improvedimage resolution should minimize the difference be-tween these measurement methods.

Two-dimensional aortic diameter measurements arepreferable to M-mode measurements, as cyclic motionof the heart and resultant changes in M-mode cursorlocation relative to the maximum diameter of thesinuses of Valsalva result in systematic underestimation(by2 mm) of aortic diameter by M-mode in compar-ison with the 2D aortic diameter.132 The aortic annulardiameter is measured between the hinge points of theaortic valve leaflets (inner edge-inner edge) in theparasternal or apical long-axis views that reveal thelargest aortic annular diameter with color flow map-ping to clarify tissue-blood interfaces if necessary.132

The thoracic aorta can be better imaged using TEE

than TTE, as most of it is in the near field of the



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transducer. The ascending aorta can be seen in longaxis using the midesophageal aortic valve long-axis

view at about 130 degrees and the midesophagealascending aorta long-axis view. The short-axis viewof the ascending aorta is obtained using themidesophageal views at about 45 degrees. For mea-surements of the descending aorta, short-axis viewsat about 0 degrees, and long-axis views at about 90degrees, can be recorded from the level of thediaphragm up to the aortic arch (Figure 19). Thearch itself and origins of two of the great vessels can

be seen in most patients. There is a blind spot in theupper ascending aorta and the proximal arch that isnot seen by TEE because of the interposed trachealbifurcation.

Identification of Aortic Root Dilatation

Aortic root diameter at the sinuses of Valsalva isrelated most strongly to BSA and age. Therefore, BSAmay be used to predict aortic root diameter in 3 agestrata: younger than 20 years, 20 to 40 years, andolder than 40 years, by published equations.132

Aortic root dilatation at the sinuses of Valsalva isdefined as an aortic root diameter above the upper

limit of the 95% confidence interval of the distribu-tion in a large reference population.132 Aortic dila-tation can be easily detected by plotting observedaortic root diameter versus BSA on previously pub-lished nomograms (Figure 20).132 Equations to de-termine the expected aortic diameter at the sinusesof Valsalva in relation to body surface area for eachof the 3 age strata are found in Figure 20. The aorticroot index, or ratio of observed to expected aorticroot diameter, can be calculated by dividing theobserved diameter by the expected diameter. Aorticdilatation is strongly associated with the presenceand progression of aortic regurgitation133 and with

the occurrence of aortic dissection.

134

The presence

of hypertension appears to have minimal impact onaortic root diameter at the sinuses of Valsalva,133,135

but is associated with enlargement of more distalaortic segments.

Evaluation of the Inferior Vena Cava

Examination of the inferior vena cava (IVC) from thesubcostal view should be included as part of theroutine TTE examination. It is generally agreed thatthe diameter of the IVC should be measured withthe patient in the left decubitus position at 1.0 to 2.0

cm from the junction with the RA, using the long-axis view. For accuracy, this measurement should bemade perpendicular to the IVC long axis. The diam-eter of the IVC decreases in response to inspiration

when the negative intrathoracic pressure leads to anincrease in RV filling from the systemic veins. Thediameter of the IVC and the percent decrease in thediameter during inspiration correlate with RA pres-sure. The relationship has been called the collapsibilityindex.136 Evaluation of the inspiratory response oftenrequires a brief sniff, as normal inspiration may notelicit this response.

The normal IVC diameter is less than 1.7 cm.

There is a 50% decrease in the diameter when theRA pressure is normal (0-5 mm Hg). A dilated IVC(1.7 cm) with normal inspiratory collapse (50%)is suggestive of a mildly elevated RA pressure(6-10 mm Hg). When the inspiratory collapse isless than 50%, the RA pressure is usually between10 and 15 mm Hg. Finally, a dilated IVC withoutany collapse suggests a markedly increaseed RApressure of greater than 15 mm Hg. In contrast, asmall IVC (usually 1.2 cm) with spontaneous col-lapse often is seen in the presence of intravascular

volume depletion.137

There are several additional conditions to be

considered in evaluating the IVC. Athletes have been

Figure 20 The 95%confidence intervals for aortic rootdiameter at sinuses ofValsalvabased onbodysurfacearea in children and adolescents (A), adults aged 20 to 39 years (B), and adults aged 40 years or older (C).(Reprinted from American Journal of Cardiology, Volume 64, Roman et al., Two-dimensional echocardio-graphic aortic root dimensions in normal children and adults, 507-12, 1989, with permission from Excerpta

Medica, Inc.)



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shown to have dilated IVCs with normal collapsibil-ity index. Studies137,138 have found that the meanIVC diameter in athletes was 2.31 .46 compared

with 1.14 0.13 in aged-matched control subjects.The highest diameters were seen in highly trained

swimmers.One study showed that a dilated IVC in themechanically ventilated patient did not always indi-cate a high RA pressure. However, a small IVC (1.2cm) had a 100% specificity for a RA pressure of lessthan 10 mm Hg with a low sensitivity.139 A morerecent study suggested that there was a bettercorrelation when the IVC diameter was measured atend expiration and end diastole using M-mode echo-cardiography.140

The use of the IVC size and dynamics is encour-aged for estimation of RA pressure. This estimateshould be used in estimation of the pulmonaryartery pressure based on the tricuspid regurgitant jet

velocity.

The authors wish to thank Harvey Feigenbaum, MD, and

Nelson B. Schiller for their careful review and thoughtful

comments.

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