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Br Heart J 1986; 56: 33-44

Echocardiographic measurement of the normal adultright ventricle

RODNEY FOALE, PETROS NIHOYANNOPOULOS, WILLIAM McKENNA,ANGELIKA KLIENEBENNE, ALEXANDER NADAZDIN,EDWARD ROWLAND,* GILLIAN SMITH

From St Mary's Hospital and the Hammersmith Hospital, London

SUMMARY In studies of the right ventricle the complexities of chamber shape may be overcome

by use ofmultiple tomographic imaging planes. An established protocol for the echocardiographicdescription of the heart was used to examine the right ventricle in an ordered series of transducerlocations and orientations. Diastolic measurements were made ofthe right ventricular inflow tract,outflow tract, and right ventricular body, and the range and reproducibility of normal values forcavity size and right ventricular free wall thickness were established. These measurements ofcavity size in 41 normal subjects were highly reproducible and the views that were used correctlydescribed the truncated and ellipsoidal shape of the right ventricular inflow tract and body witha separately aligned outflow tract. Cavity trabeculation prevented measurement of the free wallthickness in some areas; however, values of nearly twice the previously reported upper limit ofnormal for anterior regions were measured from the apex or lateral right ventricular wall.These normal data provide a basis for future echocardiographic studies of the right ventricle.

Evaluation of the structure of the right ventricle byavailable imaging methods presents a formidableproblem. This is partly due to the complex geometryof the chamber, which has separate outflow andinflow portions and a main body which is crescenticand truncated.' The right ventricular free wall alsohas a variable trabecular pattern that further limitsprecise measurement of cavity size and wall thick-ness. Additional factors, such as its retrosternal pos-ition and an anterior relation to the left heart thatmay vary according to the cardiac axis, make theright ventricle less accessible to the generally avail-able diagnostic techniques whose orientationdepends upon extemal landmarks. For example, theinterpretation of studies of right ventricular functionusing technetium 99m gated blood pool imaging maybe limited by difficulties in separating the right ven-tricular blood pool signal from that of other cardiacchambers.2 Conventional contrast cineangiographic

Requests for reprints to Dr Rodney Foale, St Mary's Hospital,Praed Street, London W2 INY.

*Present address: National Heart Hospital, Westunoreland Street, London WI.

Accepted for publication 24 February 1986

assessment of the right ventricle fails to considervariations in chamber orientation in individualpatients, and is further constrained by an inherentdependence upon a cavity silhouette made up byoverlapping regions of the ventricular wall.The use of tomographic methods that con-

ventionally use a fixed transverse or sagittal orien-tation, such as nuclear magnetic resonance imaging,positron emission tomography, and computedtomographic scanning, is also limited in the evalu-ation of chamber shape, size, and wall thicknessbecause their orientation depends on external land-marks. Thus, oblique cuts across an asymmetricright ventricular chamber obtained from transversewhole body image acquisition inevitably provide acavity dimension and wall thickness measurementsthat are difficult to standardise between patients.EarlyMmode echocardiographic studies of the rightventricle have necessarily relied upon an evaluationof a single dimension and wall thickness3 withoutconsideration of the complex geometry of the cham-ber and the variable trabecular pattern of its wall.The more recent development of cross sectional

echocardiography has renewed interest in the exam-ination of the right ventricle4'5 and offers the advan-

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Foale, Nihoyannopoulos, McKenna, Klienebenne, Nadazdin, Rowland, Smith

tages of multiple tomographic views of the heart ina beat by beat display, without identifiable risk ordiscomfort to the patient. Furthermore, it may bethat because with these methods reference to internalintracavitary landmarks is obligatory, right ventricu-lar measurements obtained by echocardiography aremore reliable that those obtained by techniqueswhich image the right ventricular chamber withoutreference to peculiarities of internal structure or toits oblique orientation. To date, however, theapproach to the cross sectional echocardiographicexamination of the right ventricle has not been stan-dardised.We propose a systematic approach to the evalu-

ation of the right ventricle with regard to its cavitysize and measurement of its free wall thickness thatmay be easily used as part of a standardised echo-cardiographic examination protocol. The normalrange of right ventricular cavity dimension and wallthickness taken from right ventricular projections in41 subjects are provided, the reproducibility of themeasurements is assessed, and the potential lim-itations of the technique are discussed.

Subjects and methods

The subjects were selected from healthy volunteerswho were normal on clinical evaluation and who hada normal resting 12 lead electrocardiogram and chestx ray. Technically adequate echocardiographic stud-ies were used from 41 adult subjects aged from 19 to46 years (mean 32 years). Twenty one were femaleand 20 male. Studies were considered to be of anadequate technical quality when the major part ofthecavities of four cardiac chambers and each of fourcardiac valves were identified both from the para-sternal and from apical transducer locations.

Echocardiographic studies were performed by ahigh resolution cardiac ultrasound system with a 3-3MHz transducer that was dynamically focusedthroughout the depth ofthe imaged field (GE Pass C,

International General Electric Company, Slough,Berkshire, UK). With this ultrasound system

M mode and cross sectional echocardiographicimages may be simultaneously displayed and theMmode beam may be positioned with reference to

the cross sectional image. In this way accurate mea-

surements along a known axis ofthe ventricle may bemade. Each study was performed in accordance witha protocol modified at our hospital from that pro-

posed by other groups.68 In this, images of themajor and minor axes of each cardiac chamber were

obtained in accordance with a strictly performedsequence outlined in Table 1. Each view is alignedaccording to internal reference points so thatreproducible images of each cardiac chamber or theirseparate parts can be generated. In the course of thisexamination procedure specific right ventricularviews are obtained, and it was from these and otherviews used in the protocol that right ventriculardiastolic dimension and right ventricular free wallthickness were measured.

RIGHT VENTRICULAR CHAMBER SIZEThe three regions of the right ventricle were mea-sured as follows:

Right ventricular inflow tractMeasurements of this region were obtained in fourseparate transducer orientations (Table 1).

Right ventricular inflow tract view-With thetransducer in the third or fourth intercostal space atthe left sternal edge, the long axis ofthe left heart wasimaged with the interventricular septum and ante-rior aortic wall lying parallel to the chest wall. A shiftin transducer position to a point approximately mid-way between the parasternal edge and cardiac apexwith medial and downward tilt results in the ultra-sound plane slipping across the sagittally orientatedinterventricular septum. Thus a view of the rightventricular inflow tract and right ventricular body inthe major axis was obtained (Fig. 1). The region of

Table 1 Standardised echocardiographic examination sequence

Transducer location Axis of chamber or Viewsvessel

Left parasternal edge Major (or long) LV, aorta,* RV inflow,tt RV outflow*Minor (or short) Aortic root,* mitral valve, tricuspid

valve,t LV serial viewsCardiac apex Major Four chambert§ (left and right heart),

two chamber (left heart)Subcostal Major Four chamber,t LV serial views

Minor Mitral valves, tricuspid valve, aortaSuprasternal or upper stemal edge Major Aortic arch

Minor Aortic arch

Views from which RV outflow tract,* inflow tract,t tricuspid valve annulus,t and RV body§ measurements were obtained. RV, rightventricle.

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Echocardiographic measurement of the normal adult right ventricle

T7

Fig. 1 Parasternal right ventricular infow tract view. Fig. 2 Parasternal tricuspid valve short axis view.See text for measurements and abbreviations. See text for measurements and abbreviations.

the right ventricular apex and the tricuspid valveannulus were used as the internal reference points ashas been previously described,7 so that the inflowpart of the right ventricle from the tricuspid annulusto at least the proximal right ventricular body wasclearly defined. By scanning the ultrasound planeacross the major axis of this region of the ventricle,maximum dimensions were measured of (a) the tri-cuspid valve annulus (RVA1), defined in this view asthe region of the atrioventricular junction to whichthe anterior and posterior tricuspid valve leafletsattach and (b) the major axis of the right ventricularinflow tract (RVIT1), a measurement taken withinone third of the distance below the annulus towardsthe region of the right ventricular apex. Care was

taken to exclude the proximal right ventricularoutflow tract from this view.

Parasternal short axis view of the tricuspidvalve7-From the parasternal short axis view of theleft ventricle at mitral valve level, medial and inferiortilting of the transducer results in a minor axis viewof the right ventricular inflow tract immediatelybelow the tricuspid valve leaflets (Fig. 2). The mea-surement of this region (RVIT2) was defined as themaximum perpendicular distance from the right sideof the mid-interventricular septum to the right ven-tricular free wall.

Apical four chamber view9-From an apical fourchamber view the ultrasound beam was orientated toobtain the maximum dimensions ofthe right ventric-

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T10

Fig. 3 Apical four chamber view. See text formeasurements and abbreviations.

ular chamber (Fig. 3). Measurements were made ofthe tricuspid valve annulus (RVA2), defined as thepoint of attachment of the septal and posteriorleaflets to the atrioventricular junction, and of theminor axis of the right ventricular inflow tract(RVIT3) taken within one third of the distancebelow the tricuspid valve annulus towards the rightventricular apex.

Subcostalfour chamber view-With both atria andventricles viewed in a long axis projection (Fig. 4),the right ventricle was aligned to obtain the maxi-mum dimensions of the minor axis of the right ven-tricular inflow tract (RVIT4), measured just belowthe tricuspid valve within one third of the distancetowards the cardiac apex.

Fig. 4 Subcostal four chamber view. See text formeasurements and abbreviations.

Right ventricular outflow tractMeasurements of this region were taken from threeseparate transducer locations.

Parasternal view of the left heart-We usedMmode echocardiography to measure the right ven-tricle anteriorly to the echoes which represent theintraventricular septum.3 The parasternal long axisview of the left ventricle obtained by cross sectionalechocardiography (Fig. 5) identifies this Mmodedimension as the proximal region of the right ven-tricular outflow tract (RVOT1). Measurements weremade from the right side of the interventricular sep-tum to the anterior right ventricular free wall.

Right ventricular outflow tract view6-From theparasternal long axis view of the left heart the true

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TI

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l. LV

_LV

Fig. 5 Parasternal view of the left heart (withproximal right ventricular outflow tract). See textfor measurements and abbreviations.

long axis of the right ventricular outflow tract wasvisualised by leftward and superior angulation of thetransducer (Fig. 6). With this manoeuvre the maxi-mum dimensions of the pulmonary annulus andproximal main pulmonary artery were kept in thesame imaging plane. Measurements were taken ofthe right ventricular outflow tract from the regionapproximately 2 cm below the annulus where theright ventricular anterior wall myocardium was dis-cernible (RVOT2) and from just beneath the pul-monary valve annulus (RVOT3). This region of theright heart may also be viewed from the subcostaltransducer position and has been well described ininfants and children.'0 In the adults of our study,however, the location of the outflow tract in the far

Fig. 6 Right ventricular outflow tract view. Seetext for measurements and abbreviations.

field of this view, while allowing for gross mor-phological description of the area, provided too pooran edge discrimination for reliable measurement.

Parasternal short axis view of the aortic root-Theright ventricular outflow tract from this view wasmeasured anteriorly to the aortic root as the maxi-mum dimension between the anterior aortic wall andthe right ventricular free wall endocardium(RVOT4) (Fig. 7).

Right ventricular bodyOne transducer location only was used for mea-surement of this region of the ventricle.

Apicalfour chamber view-The middle third oftheright ventricle was identified as lying below the

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RVOT ,

Fig. 7 Parasternal short axis view of the aorticroot. See text for measurements and abbreviations.

inflow tract region (Fig. 3). A measurement of themaximum dimension of this portion of the chamber,defined as the body, was taken (RV SAX). From thisview both the lateral free wall of the ventricle and theright side of the interventricular septum lie parallelwith the ultrasound beam; thus the endocardial echo,particularly that from the lateral wall, may on occa-sion spread over 3-5 mm. In these cases the mid-point of this signal was taken as the point from whichto measure the distance between right ventricularseptal surface and free wall. The major axis of theright ventricle (RV LAX) was also measured fromthis view and was defined as the distance between theright ventricular apex to the mid-point of the tri-cuspid valve annulus.

RIGHT VENTRICULAR WALL THICKNESSA total of ten different regions of right ventricularfree wall were measured from the four transducerpositions and orientations described above (Figs. 1to 7).Measurements T1-5 were taken from the views

which imaged the right ventricular outflow tract(Figs. 5-7). Measurements T6-10 were of the freewall of the right ventricular inflow tract and body(Figs. 1, 3 and 4). Measurements T6-8 were takenfrom the parasternal right ventricular inflow tractview (Fig. 1), T6 and T7 were measurements of theanterior wall of this region of the right ventricle, andT8 was a measuremnent of the posteromedial wall.The thickness ofthe lateral wall ofthe right ventricle(T9) was measured from the apical four chamberview (Fig. 3). T10 was a measurement of thediaphragmatic wall of the right ventricle taken fromthe subcostal four chamber view (Fig. 4).

ECHOCARDIOGRAPHIC ANALYSISVideo recordings of optimal M mode and cross sec-tional echocardiographic images from each part ofthe examination sequence, together with standardlead II of an electrocardiogram, were stored on vid-eotape for subsequent analysis.Measurements from M mode or cross sectional

echocardiographic images were performed by a com-mercially available offline analysis system (Micro-sonics, Indianapolis, Indiana, USA). This uses ajoystick operated cursor which minimises the mea-surement errors due to parallax. Measurements weretaken from the Mmode recording when this coin-cided with the major or minor axis of the right ven-tricle; when it did not measurements were takendirectly from the cross sectional image in stop-frameformat. All measurements were performed at enddiastole, which was defined as the frame closest tothe onset of the R wave of the electrocardiogram.Right ventricular cavity dimension and right ven-tricular wall thickness were measured from the lead-ing edge to the leading edge of the endocardial orepicardial signals. Three values for each dimensionor thickness were made from three consecutive car-diac cycles. The measurements were averaged andthe resulting value was used in the statistical anal-ysis.

STATISTICAL ANALYSISAbsolute measurements and those corrected forbody surface area were expressed as mean (2 SD).The coefficient of variation was calculated for eachdimension and wall thickness as:

Standard deviation x 100%Mean x10

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Table 2 Right ventricular chamber size: absolute measureentsfrom 41 norml suects at end diastok

No (41) Mean (cm) 2 SD Range Coefficiet of variation(within measurmnts) (%)

RVIT1 40 4*5 0-5 3-7-54 10-6RVIT2 29 3*0 0*3 2*4-3.9 12-2RVIT3 38 2 4 0 4 1-5-3-0 16-1RVIT4 29 5-1 0*5 4-0-7*0 11-2

RVOT1 41 2*2 0 3 1*8-3-0 13-4RVOT2 41 2-3 0 3 18-2-9 13-0RVOT3 41 2-0 0 3 1-4-2-6 15-0RVOT4 41 2-7 0-2 2-0-3-2 10-1

RV LAX 40 7-6 0 5 6-9-89 5 9RV SAX 40 3-0 03 24-3*7 10-2

RVA1 41 3-4 03 25-4.0 95RVA2 41 2-4 0*3 1'6-3*1 14-1

Coefficient of vaiation (between measurements) mean (1 SD) 51 (12)%, range 36-72%.

Table 3 Right ventricular chamber size: measurements from 41 normal subjects at end diastole corrected for body surfacearea

No (41) Mean (cm) 2 SD Range Coefii of variation(within measuremnts) (%)

RVIT1 40 2-6 0*3 2-0-3-3 11-8RVIT2 29 1-7 0-2 1-4-2-0 10-8RVIT3 38 1-4 0-2 1-0-1-8 16-1RVIT4 29 2-9 0 4 2-3-3-6 12-3

RVOTI 41 1-3 0-2 1-0-1-7 12 6RVOT2 41 1-3 0-3 1-02-9 22-5RVOT3 41 11 0-1 09-1-4 12-4RVOT,4 41 1-6 0-2 1-2-2-0 12-7

RV LAX 40 4-4 04 3-65-4 91RV SAX 40 1-8 0-2 1-4-2-2 12-7

RVAI 41 2-0 0-2 1-6-2-4 10-2RVA2 41 1-5 0-2 1-1-15 14-3

Coefficient of variation (between measurements) mean (1 SD) 51 (12)%, range 37-72%.

This value expresses the spread of values about themean. The coefficient of variation may be used tomeasure regional asymmetry of cavity size or wall

thickness when calculated for the different mea-

surements within individuals. When calculated forthe same measurement between individuals, thecoefficient of variation shows the normal variabilityof the measurement in a population. If it is assumedthat, like other cardiac dimensions, this variability isrelatively small, then the coefficient of variation mayalso be considered as a function of the ease of stan-dardisation of that view from which the mea-

surement was made-that is the ease ofobtaining thesame "on axis" view for different patients.

Intraobserver variability was tested by a secondanalysis of 10 randomly selected studies. Mea-surements were performed blindly by the firstobserver at least 14 days after the first analysis. Inter-

observer variability was tested by a second observerfor the same randomly selected studies. Inter-observer and intraobserver variability wereexpressed both as the range of absolute differenceand the percentage difference between the two mea-surements.

Results

RIGHT VENTRICULAR CHAMBER SIZETables 2 and 3 show the results for absolute mea-surements of the right ventricular cavity and thosecorrected for body surface area. The frequency withwhich each measurement was made is shown. Table4 shows the results for interobserver and intra-observer variability for the absolute measurement.Of the right ventricular inflow tract views,

RVIT2, from the parasternal short axis view, and

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40 Foale, Nihoyannopoulos, McKenna, Klienebenne, Nadazdin, Rowland, Smith

Table 4 Inter- and intraobsewer variability of the absolute measurements of right ventricular chamber size

Interobsever Intraobserver

Absolute difference % of differen Absolute difference % of differenac

Mean 2 SD Mean 2 SD Mean 2 SD Mean 2 SD(cm) (cm)

RVIT1 0-04 0-4 1-5 0-1 0-03 0-5 0-03 0-1RVIT2 1-0 0-4 54 0*4 0-08 0-4 2-4 0-1RVIT3 0-2 0-3 5-7 0-1 0-07 0-3 2-8 0-1RVIT4 0.1 0-7 0-8 0-1 0-2 0-7 4-5 0-1

RVOT1 0-2 0-3 5-7 0-1 0-1 0-2 6-1 0-1RVOT2 0-3 0-3 14 0-1 0-3 0-2 13 0-1RVOT3 0-2 0-3 7-1 0-1 0-09 0-3 5-2 0-1RVOT4 0-2 0-4 12 0-2 0-05 0-2 1-4 0-1

RV LAX 0-3 0-6 3-8 0.1 0-3 0-5 3-8 0-1RV SAX 0-2 0-7 10 0-3 0-04 0-4 1-1 0-2

RVA1 0-06 0-5 0-6 0-1 0-2 0-2 5-9 0-1RVA2 0-2 0-3 6-0 0.1 0-1 0-3 3-0 0-1

Table 5 Right ventricular wall thickness: end diastolic measurements from 41 normal subjects

RV wall Absolute values (cm) Correctedfor BSA (m2)region

Mean 2 SD Range Coefficient of Mean 2 SD Range Coefficient ofvariation (within variation (withinmeasurements) (%) measurements) (%)

Ti 0 3 0 07 0-2-0-5 20-7 0-2 0 04 0-1-0-3 22-4T2 0 3 0 07 0-2-0-5 21-5 0-2 0 05 0-1-0-3 23-6T3 0 3 0*05 0 3-0 5 15-9 0-2 0 04 0-1-0-3 20-1T4 0-4 0 07 0-2-05 18-6 0-2 0-04 0-1-0-3 22-0T5 0 3 0-08 0-2-0-5 21-8 0-2 0 05 0-1-0-3 25-8T6 0 3 0-06 0-2-0-5 17.7 0-2 0 04 0-1-0-3 21-1T7 04 007 0-3-05 20-2 0-2 005 0-1-0-3 24-1T8 0 4 1-0 0-3-0-6 25-5 0-2 0-06 0-1-0-4 26-6T9 0 4 0 07 0-3-0-6 16-7 0-2 0^05 0-1-0-3 21-1T1O 0 4 1-0 0 3-0 7 24-5 0-2 0-06 0-1-0-4 27-4

Coefficient of variation (between measurements) mean (1 SD) 17 (14%), range 3-31% for absolute values; 17 (14)%, range 8-35% forBSA corrected values. BSA, body surface area.

Table 6 Inter- and intraobserver variability of the absolute measurements of right ventricular wall thickness

RV wall Interobserver Intraobserverregion

Absolute difference % of difference Absolute difference % of difference

Mean 2 SD Mean 2 SD Mean 2 SD Mean 2 SD(cm) (cm)

Ti 0-04 0-2 18 74 0-1 0-14 26 32T2 0-01 0-12 6 21 0-02 0-16 4 48T3 0-05 0-18 23 70 0-07 0-1 19 28T4 0-02 0-18 11 52 0-05 0-1 13 26T5 0.0 0-2 11 100 0-05 0-2 12 56T6 0-02 0-2 15 41 0-04 0-14 9 38T7 0-03 0-18 4 56 0-0 0-1 1 32T8 0-06 0-2 9 64 0-01 0-2 8 58T9 0-02 0-4 6 96 0-07 0-2 14 74T1O 0-09 0-18 19 36 0-04 0-1 13 32



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Fig. 8 Coefficient of variation for measurements corrected for body surface area (a) and absolute measurements (b) ofright ventricular cavity size and right ventricular free wall thickness.

RVIT4, from the subcostal view, were least oftenobtained (29 (70%) of41 studies for each view). Theabsolute measurement of inflow tract with the leastvariability, as measured by a coefficient of variationof 10 6%, was RVIT1; differences between mea-

surements of this value were < 5%. The results forRVIT1, RVIT3, and RVIT4 showed a high degreeof reproducibility (Table 4) with an interobserverand intraobserver variability of < 10%. The inter-observer variability for measurement of RVIT2 was

poor, however, at 54%.Measurements of the right ventricular outflow

tract were obtained in all patients and fell within a

narrow range. The spread of values indicated by acoefficient of variation for absolute values of < 15%was also small. The results for all four measurementsmostly showed acceptable reproducibility. ForRVOT2, however, interobserver and intraobservervariability were 14% and 13% respectively. The

interobserver variability for RVOT4 was 12%. Bothmeasurements of the right ventricular body showeda good coefficient of variation (in the region of 10%)and interobserver and intraobserver variabilitieswere low.The measurements of tricuspid annulus from

orthogonal planes showed an acceptable spread ofvalues with coefficient of variations of < 15% andgood interobserver and intraobserver variability.The coefficient of variation measured within indi-

viduals for different measurements of cavity size(Fig. 8) showed a high degree of variability(51(12)%, range 36-72%), as was expected given themarkedly asymmetrical shape of the chamber.

RIGHT VENTRICULAR WALL THICKNESS

Tables 5 and 6 show the results for right ventricularwall thickness in the ten measured regions of rightventricular free wall. Although earlier echo-

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cardiographic studies have suggested that normalwall thickness for the right ventricle is < 0 4cm(range 0-2-0-4cm), our results indicate that rightventricular wall thickness may show a regional vari-ation of between 0-2cm and 0-7cm. Values of thecoefficient of variation of > 25% for different mea-surements within subjects suggest that the right ven-tricular free wall is asymmetric in some normalindividuals (Fig. 8). The values for the coefficient ofvariation for the same measurement between sub-jects of mostly > 20% were less satisfactory than forright ventricular cavity dimensions, suggesting thatthese measurements will be less easily standardised.Furthermore, the reproducibility of some of thesemeasurements was poor, with interobserver andintraobserver variations of up to 23% and 26%respectively.These results for wall thickness, however, repre-

sent differences of 0.1 or 0-2 cm, which fall near theresolution limits of most echocardiographic systems.Also although efforts were made to exclude tra-becular echoes from the assessment ofwall thickness,failure to have done so may easily account for theapparent limited reproducibility of some of thesemeasurements.

Discussion

Disorders of right ventricular function may resultfrom many disease states that directly affect heartmuscle or which impose abnormal loading condi-tions upon the right sided chambers. Recently therehas been considerable interest in the investigation ofsuch abnormalities by various non-invasive tech-niques.45 Echocardiography is one which hasbecome increasingly used in the measurement of car-diac structure and function as methodology andimage quality have advanced. Our study wasprompted by the need for a standardised approach tothe echocardiographic examination of the rightventricle' and to obtain a range of normal values forintemal cavity dimension and right ventricular freewall thickness from the several views that we used.We believe that an evaluation ofthe right ventricle

should be part of every routine echocardiographicstudy. We hold this view because, firstly, many dis-orders ofthe right ventricle may not result in obviousclinical signs or may be overshadowed by left sidedabnormalities. Secondly, the right ventricularspecific views may be difficult to obtain, and theexperience gained by the echocardiographer inattempting these views in every study should pro-vide the necessary expertise when the clinical indi-cation calls for a specific examination of the rightsided chambers.

NORMAL RIGHT VENTRICULAR END DIASTOLICCHAMBER DIMENSIONSBecause the inflow tract, ventricular body, andoutflow tract are three distinct regions of the rightventricle that are orientated in different axes, mea-surements of each region should be obtained fromseparate views.The measurements of the right ventricular inflow

tract that we have used mostly show little variationaround the mean, as shown by coefficients of vari-ations in the order of 15%. RVIT2, the measurementfrom the parasternal short axis of the left ventriclewith tilt towards the tricuspid valve, showed aninterobserver variability of 54%, suggesting that itmay be difficult to standardise. Furthermore, it wasonly available in a limited number ofpatients (70%).Similarly, RVIT4, the measurement from the sub-costal view, was available in 70% of patients and itshowed a low coefficient of variation with goodreproducibility. Of all the right ventricular inflowtract measurements, the most easily obtained andreproducible measurements of the right ventricularinflow tract came from the two views in orthogonalplanes-RVIT, from the specific parasternal rightventricular inflow tract view and RVIT3 from theapical four chamber view.Most measurements of the right ventricular

outflow tract showed satisfactory degrees ofreproducibility and little variation. The right ven-tricular outflow tract measurement RVOT1, as takenby M mode and cross sectional echocardiographyfrom a parasternal long axis view of the left heart, isneither true outflow tract nor true right ventricularbody. Because it is desirable to relate the results ofMmode studies to those obtained with cross sectionalechocardiography, however, this measurement wasincluded in our protocol. Indeed, RVOT, showed ahigh degree of reproducibility and also had a lowcoefficient of variation. The measurement of thissame region from the parasternal short axis view ofthe aortic root (RVOT4) was larger and was lessreproducible, with an interobserver variation of12%. These minor discrepancies may be explainedby the differences in obtaining images from shortaxis and long axis projections. A short axis plane ismore likely to pass obliquely through this region andthus provide a larger measurement because there areno satisfactory internal landmarks upon which toorientate the image with precision. By keeping theinterventricular septum and anterior aortic wall par-allel to the chest wall in the parasternal long axis viewof the left heart, better "on axis" measurements maybe made. Thus, RVOT1 is a better measure ofoutflow tract than RVOT4. The specific right ven-tricular oudlow tract view from which RVOT2 andRVOT3 were derived was obtained in all patients in

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the study group. RVOT2, however, had less satis-factory interobserver and intraobserver variability,although absolute differences were no more than03 cm. RVOT3, the measurement of the outflowtract immediately below the pulmonary valveannulus, was highly reproducible and showed littlevariation in normal subjects.

Difficulties were experienced in obtaining preciseon axis views for the right ventricular body fromprojections other than the apical four chamber view.Even from this view it was not always clear where theminor axis of the right ventricular body should bemeasured. Schnittger et al" have followed othergroups7 by taking this measurement at a fixed dis-tance in the chamber-that is one third of the waydown the major axis from the atrioventricular ring.In our experience, however, this fixed distance mea-surement does not always coincide with the max-

imum short axis diameter.We measured the maximum short axis diameter of

the body ofthe ventricle taken below the inflow mea-surement but within the middle third of this imagedcavity. Nuances of apex identification and chambershape are taken into account by this approachalthough it is clear that precise identification ofendocardial signal may not always be possible fromthis view. Our measurements of the minor axis, how-ever, showed little variation and had satisfactoryreproducibility. Similarly, the long axis mea-

surement of the right ventricular body was satis-factory in most cases.

NORMAL RIGHT VENTRICULAR END DIASTOLICWALL THICKNESSIn our group of normal subjects, the mean rightventricular free wall thickness was not > 04 cm.Individual values, however, ranged up to 0-7 cm.The mean coefficient of variation of 17% in indi-

vidual measurements between subjects showed thatthe right ventricular free wall is fairly symmetrical.Several individuals, however, had values > 25% andthus a degree of free wall asymmetry should beexpected in some normal subjects. The variations infree wall thickness are seen particularly in the lateraland diaphragmatic regions. In performing thesemeasurements, we have attempted to exclude densetrabecular patterns by careful review of the study inreal time format. During replay the trabeculaeshould easily be distinguished from true right ven-

tricular free wall; however, it is possible thatdifferences in trabecular patterns could explain theexaggerated wall thickness measurements in some

cases. Accurate measurements of abnormallyincreased right ventricular wall thickness are difficultto obtain in regions other than the outflow tractwhere, despite absence of heavy trabeculation, nor-

mal wall thickness of 04A0-5 cm are described.12 Afurther explanation for the regional variation inwall thickness measurements may be limitedreproducibility (< 23%); however, measurementsbelow 05 cm in echocardiography are of small abso-lute differences which may be at the resolution limitof most ultrasound systems. We consider that valuesof > 07 cm for right ventricular wall thickness (or04cm/rM2) should certainly be regarded as abnor-mal; but if they are isolated and obtained from thelateral or diaphragmatic walls they should be inter-preted with caution.Our results for normal right ventricular cavity

dimensions at end diastole and for normal values ofright ventricular diastolic wall thickness do not varygreatly from those measured by other groups.13 -15Our observations are taken from 41 subjects, how-ever, the largest normal population studied to dateand include a specific measurement of the right ven-tricular inflow tract (RVIT1) and a detailed mea-surement of right ventricular wall thickness notpreviously described. We have also performed amore structured analysis of the right ventricle thanthe single plane orientation reported in the recentstudy by Schnittger et al" or by others in the deter-mination of right ventricular volumes'4 16 or ejec-tion fractions.17 18 From approximately similarprojections our values for RVIT, resemble thosethat were measured by Bommer et al'3 and differ inonly minor degrees from the results of Watanabe etal.'5 These groups and others,'8 however, have usedas an equivalent to our specific right ventricularinflow tract view an orientation with the transducerpositioned at the cardiac apex. Weyman has obtainedthis projection from the left parasternal edge, but hassuggested that measurements of the inflow tractderived from this position may be difficult to stan-dardise.'4 Although we agree in part with this opin-ion, we believe that the measurements of this inflowtract plane from the cardiac apex often containoutflow tract as illustrated by Panidis et al'8 and somay be equally difficult to standardise. We were suc-cessful in imaging the long axis of the inflow tract ofthe right ventricle, including the tricuspid valveannulus and excluding outflow tract, from a trans-ducer location approximately midway between theparastemal and apical positions. This measurementhas a low coefficient of variation and wasreproducible. Thus minor differences between ourRVIT, measurements and those of others'5 can beexplained by our having excluded the proximaloutflow tract from this view by careful positioning ofthe transducer between the parasternal and apicallocations.Unlike Starling et al'7 we did not achieve success

using subcostal views of the right ventricle as advo-

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44 Foale, Nihoyannopoulos, McKenna, Klienebenne, Nadazdin, Rowland, Smithcated by Tajik et al.' These views are undoubtedlyuseful in children and in patients with severe chronicairways disease. The latter group invariably have alow diaphragm, and so the heart is closer to thetransducer when it is in a subcostal location andimage quality is enhanced. Although these views aredeemed to be suitable for gross evaluation of rightventricular chamber anatomy, our experience in anormal adult population did not allow for more thanone measurement of the cavity, that of the inflowtract (RVIT4), and one measurement of right ven-tricular wall (T10) to be obtained. These views maybe more useful in elderly patients in whom echo-cardiographic study from the parasternal and apicaltransducer positions may be technically moredifficult than in patients of the age group that westudied.We have not attempted to extend our mea-

surements to those of systolic function because of thelimitations imposed by chamber shape on the extra-polation of end diastolic and end systolic dimensionsto overall right ventricular systolic function.14Although difficulties in finding the appropriatemodel upon which an algorithm for this calculationshould be based contribute to the problems of evalu-ating overall right ventricular function, there mustalso be uncertainty, caused by the rotation of theheart throughout the cardiac cycle, that the dimen-sion obtained from systole is in the same plane of theright ventricular cavity as from diastole.These factors are less limiting in the derivation of

an ejection fraction index for the left ventriclebecause this cavity, at least in its normal condition,is a symmetrical ellipsoid. The perversities of rightventricular geometry must, however, limit thereliability of similar calculations for right ventricularfunction. Furthermore, most of the functional activ-ity of the right ventricle comes from the body of thechamber. As this is the most difficult region of theright ventricle to measure, the functional status ofthe right ventricle may be better evaluated by tech-niques, such as radionuclide imaging methods,which despite their limitations are independent ofgeometric assumptions; that is until a satisfactoryechocardiographic model is developed and theregional contribution to overall right ventricularfunction can be assessed.

References

1 Foale R, Stefanini L, Rickards A, Somerville J. Leftand right ventricular morphology in complex congenitalheart disease defined by two dimensional echo-cardiography. Am J Cardiol 1982; 49: 93-9.

2 Berger HJ, Matthay RA, Loke J, Marshall RC, Gotts-chalk A, Zaret BL. Assessment of cardiac performancewith quantitative radionuclide angiography: right ven-tricular ejection fraction with reference to findings inchronic obstructive pulmonary disease. Am J Cardiol1978; 41: 897-905.

3 Feigenbaum H. Echocardiography. 2nd ed. Philadel-phia: Lea and Febiger, 1976: 255-66.

4 Manno BV, Iskandrian AS, Hakki AH. Right ventricu-lar function: methodological and clinical considerationsin non invasive scintigraphic assessment. J Am CollCardiol 1984; 3, 4: 1072-81.

5 Cohen M, Fuster V. What do we gain from the analysisof right ventricular function? J Am Coll Cardiol 1984;3, 4: 1082-4.

6 Tajik AJ, Seward JB, Hagler DJ, Mair DD, Lie JT.Two dimensional real time ultrasonic imaging of theheart and great vessels: technique, image orientation,structure identification and validation. Mayo Clin Proc1978; 53: 271-303.

7 Weyman AE. Cross sectional echocardiography. Phila-delphia: Lea and Febiger, 1982: 497-504.

8 Report of the American Society of EchocardiographyCommittee on nomenclature and standards in two di-mensional imaging. Circulation 1980; 62: 212-9.

9 Silverman NH, Schiller NB. Apex echocardiography. Atwo dimensional technique for evaluating congenitalheart disease. Circulation 1978; 57: 583-7.

10 Lange LW, Sahn DJ, Allen HD, Goldberg SJ. Sub-xiphoid cross sectional echocardiography in infants andchildren with congenital heart disease. Circulation 1979;59: 513.

11 Schnittger I, Gordon EP, Fitzgerald PJ, Popp RL.Standardised intracardiac measurements of two dimen-sional echocardiography. J Am Coll Cardiol 1983; 2, 5:934-8.

12 Hudson REB. Cardiovascular pathology. Vol 1. Lon-don: Edward Arnold, 1965: 15.

13 Bommer W, Weinert L, Newmann A, Neef J, MasonDT, Demaria A. Determination of right atrial and rightventricular size by two dimensional echocardiography.Circulation 1979; 60: 91-100.

14 Weyman AE. Cross sectional echocardiography. Phila-delphia: Lea and Febiger, 1982: 382-95.

15 Watanabe T, Katsume H, Matsukobo H, Furukawa K,Ijichi H. Estimation of right ventricular volume withtwo dimensional echocardiography. AmJ Cardiol 1982;49: 1946-53.

16 Hiraishi S, Disessa TG, Jarmakani J, Nakanishi T,Isabel-Jones JB, Friedman WF. Two dimensionalechocardiographic assessment of right ventricular vol-ume in children with congenital heart disease. Am JCardiol 1982; 50: 1360-75.

17 Starling MR, Crawford MN, Sorensen SG, O'RourkeRA. A new two dimensional echocardiographic tech-nique for evaluating right ventricular size and per-formance in patients with obstructive lung disease.Circulation 1982; 66: 612-20.

18 Panidis I, Ren JF, Kotler MN, et al. Two dimensionalechocardiographic estimation of right ventricular ejec-tion fraction in patients with coronary artery disease. JAm Coll Cardiol 1983; 2, 5: 911-8.



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Br Heart J 1986;56:298

Notices

British Cardiac Society

The Autumn Meeting will be held at the WembleyConference Centre, London, on 25 to 27 November1986, and the closing date for receipt of abstractswas 11 July 1986.The Annual General Meeting for 1987 will take

place in Dundee on 8 and 9 April 1987, and the clos-ing date for receipt of abstracts will be 6 January1987.

Cardiac Doppler

The 2nd International Congress on Cardiac Dopplerwill be held in Kyoto, Japan, from 25 to 29 Novem-ber 1986. Further information from: Denise Liesse,Acting Secretary, ICDS, Department of Cardiology,Fondation A de Rothschild, 25-29 rue Manin, 75940Paris, Cedex 19, France.

Aortic stenosis

The European Society of Cardiology WorkingGroup on Valvular Prostheses will be holding a con-gress at the Palais des Congres in Paris on 22 and 23May 1987 on Aortic Stenosis in Adults-NewTrends. Further information and registration formsfrom Professor J Acar, Hopital Tenon, 4 rue de laChine, 75980 Paris Cedex 20, France.

CorrectionEchocardiographic measurement of the normal adultright ventricle R Foale, P Nihoyannopoulos, WMcKenna, A Kleinebenne, A Nadazdin, E Rowland,G Smith - Dr Angelika Kleinebenne's name wasmisspelt in our July issue (p 33).

396 Correspondencetaneous and completely independent, and possiblynot the first reported.

William L Proudfit,The Cleveland Clinic Foundation,9500 Euclid Avenue,Cleveland,Ohio 44106,USA.

References

1 Regulations and transactions of the GloucestershireMedical Society. London: Royal College of Physi-cians.

2 Jenner E. Letter to Caleb H Parry, 1805. The AlanMason Chesney Medical Archives, The Johns Hop-kins Medical Institutions, Baltimore.

NoticesBritish Cardiac Society

The Annual General Meeting for 1987 will takeplace in Dundee on 8 and 9 April 1987, and the clos-ing date for receipt of abstracts was 6 January 1987.The Autumn Meeting will be held at the

Wembley Conference Centre, London, on 24 to 26November 1987, and the closing date for receipt ofabstracts will be 10 July 1987.

Blood vessel imaging

A residential course/workshop on Blood VesselImaging Using Ultrasound Techniques will be heldat the Dolphin Hotel, Southampton on 11 to 13 May1987. Details from: Mr K N Humphries, BloodVessel Imaging Course, 5 Mossleigh Avenue,Rownhams, Southampton SO1 8FU.

CorrectionEchocardiographic measurement of the normaladult right ventricle R Foale, P Nihoyannopoulos,W McKenna, A Kleinebenne, A Nadazdin, E Row-land, G Smith-The authors apologise for errors intheir tables in this article published in the July issue(volume 56: pages 33-44). In tables 2, 3, 4, 5, and 61 SD should be shown; and in table 5 the value of1 SD for absolute values (cm) in rows T8 and T10 is0.1.

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