The Vena Contracta in Functional Tricuspid Regurgitation: A Real-Time Three-Dimensional Color Doppler Echocardiography Study

VALVULAR H
EART DISEASE
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doi:10.1016/j.

The Vena Contracta in Functional TricuspidRegurgitation: A Real-Time Three-Dimensional Color

Doppler Echocardiography Study

Jong-Min Song, MD, PhD, Min-Kyoung Jang, RDCS, Yoon-Sil Choi, RDCS, Yun-Jeong Kim, RDCS,Sun-Yang Min, MD, Dae-Hee Kim, MD, PhD, Duk-Hyun Kang, MD, PhD, and Jae-Kwan Song, MD, PhD,

Seoul, South Korea

Background: The aims of this study were to evaluate the three-dimensional features and geometric determi-nants of the vena contracta (VC) in functional tricuspid regurgitation (TR) and to identify optimal width cutoffvalues for assessing functional TR severity.

Methods: Real-time three-dimensional full-volume and color Doppler and two-dimensional Doppler echocar-diographic images were obtained in 52 patients with various degrees of functional TR and in sinus rhythm. Thetricuspid valve and right ventricle were geometrically analyzed. VC widths parallel to the septal-lateral andanteroposterior directions, VC area, and effective regurgitant orifice area (EROA) using proximal isovelocitysurface area methods on real-time three dimensional color Doppler images were measured.

Results: The septal-lateral VC width was 0.396 0.37 cm smaller than the anteroposterior VC width (P < .001).VC widths and area were strongly correlated with EROA. The optimal cutoff values for the septal-lateral VCwidth, anteroposterior VCwidth, and VC areawere 0.63 cm, 0.76 cm, and 0.37 cm2, respectively, for moderatefunctional TR (EROA$0.2 cm2) and were 0.84 cm, 1.26 cm, and 0.57 cm2, respectively, for severe functionalTR (EROA $0.4 cm2). Multiple linear regression analyses showed that the septal leaflet tenting angle andseptal-lateral annular diameter independently determined septal-lateral VC width, while the anterior leaflettenting angle and anteroposterior annular diameter independently determined the anteroposterior VC width.

Conclusions: Different VC width cutoff values should be applied according to the plane of view in functional TR,because theVCcross-sectional shape isellipsoidalwitha longanteroposteriordirection.VCwidthsaredeterminedby annular dilation and leaflet tenting in the corresponding directions. (J Am Soc Echocardiogr 2011;24:663-70.)

Keywords: Vena contracta, Tricuspid regurgitation, Echocardiography

Tricuspid regurgitation (TR) is associated with a poor prognosis irre-spective of underlying disease.1,2 The American Society ofEchocardiography recommends that the vena contracta width beused in quantification of TR.3,4 Although a vena contracta width>0.7 cm is regarded as a marker for severe TR, there is noestablished vena contracta width cutoff value for differentiatingbetween moderate and mild TR. The vena contracta cross-sectionalshape was reported to be more ellipsoid in TR compared with mitralregurgitation.5,6 It appears, however, that no study has examined thevena contracta in functional TR, a major etiology of TR. If the venacontracta cross-sectional shape in functional TR is not circular, thendifferent cutoff values should be applied on the basis of the two-dimensional plane used for viewing. However, this issue has not

ion of Cardiology, Asan Medical Center, University of Ulsan College

eoul, South Korea.

ts: Jong-Min Song, MD, PhD, Division of Cardiology, Asan Medical

sity of Ulsan College of Medicine, 388-1 Poongnap2-dong, Songpa-gu,

, South Korea (E-mail: [email protected]).

6.00

1 by the American Society of Echocardiography.

echo.2011.01.005

been resolved yet. The tricuspid valve has three leaflets, which resultsin coaptation along three radial lines between the leaflets. It is notknownwhether the vena contracta cross-sectional shape in functionalTR is triangular or ellipsoidal. If it is ellipsoidal, the direction of themaximal vena contracta width should be identified. Furthermore, al-though annular dilation and leaflet tethering have been suggested ascauses of functional TR,7-11 the effect of remodeling of the rightventricle on functional TR severity remains to be clarified. Inaddition, the effect of geometric factors in tricuspid valve apparatusand the right ventricle on vena contracta width in functional TRhave not been determined. Therefore, we sought to evaluate three-dimensional features of vena contracta in functional TR andgeometric determinants for vena contracta and to determine theoptimal cutoff values of vena contracta width obtained from differentviews for assessment of functional TR severity, using real-time three-dimensional color Doppler echocardiography.

METHODS

We enrolled 52 adult patients (mean age, 54617 years; 30 women)with various degrees of functional TR and in sinus rhythm. Excludedfrom the study were patients with definite organic deformation,

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http://dx.doi.org/10.1016/j.echo.2011.01.005

Abbreviations

EROA = Effective regurgitantorifice area

PISA = Proximal isovelocitysurface area

RV = Right ventricular

TR = Tricuspid regurgitation

664 Song et al Journal of the American Society of EchocardiographyJune 2011

restricted tricuspid valve motion,in atrial fibrillation, or withfrequent premature beats. Areal-time three-dimensionalechocardiography system(Sonos 7500 or iE33; PhilipsMedical Systems, Andover,MA) with a 2-MHz to 4-MHz3,000-element xMATRIX trans-thoracic transducer was used to

acquire three-dimensional full-volume and color Doppler images.Images were obtained from the low parasternal or apical views withgain, compression controls, and time gain compensation settings op-timized for image quality. Care was taken to include the entire rightventricle and tricuspid valve apparatus in the full-volume data set.Full-volume data sets were acquired in wide-angle acquisition mode(93� � 80�), in which four wedge-shaped subvolumes (93� � 20�

each) were obtained from four different cardiac cycles during heldrespiration. Three-dimensional color Doppler image volumes wereacquired as seven subvolumes gated to form a full Doppler volume(30� � 30�). Care was taken to include proximal convergence andthe entire vena contracta in the color Doppler image set. All imageswere stored digitally and analyzed offline.

Geometric analyses of the right ventricle and tricuspid valve wereperformed using TomTec software (TomTec GmbH, Munich,Germany). On the multiplanar reconstruction images, the tentingangles of the three tricuspid valve leaflets, septal-lateral, and antero-posterior tricuspid annular diameters and right ventricular (RV) inletdimensions, septal-lateral mid-RV dimension, and the distancebetween the annulus and apex were measured in a midsystolic frame,when tricuspid valve tenting was smallest. By the guidance of a mov-ing cross-sectional image of tricuspid valve, three longitudinal planesthat crossed the midportions of three leaflets were obtained(Figure 1A). The tenting angle of each leaflet was measured oneach longitudinal plane. By adjusting the orientation of the cross-sectional short-axis plane at the annular level, we generated septal-lateral and anteroposterior longitudinal planes that were mutuallyperpendicular (Figure 1B). On these two longitudinal planes, annulardiameters and RV inlet dimensions were measured. RV inlet dimen-sions were measured 1 cm apart from, and parallel to, annular lines.Septal-lateral mid-RV dimension was measured, but mid-RV dimen-sion on the anteroposterior plane could not be consistently measuredbecause the RVoutflow tract was located on the anterior side. The dis-tances from the annular plane to RV apex on the two longitudinalplanes were measured. If those two values were not equal, the largernumber was chosen. All measurement points marked on real-timethree-dimensional echocardiographic still frames were verified byoverlap with moving images. We also measured end-diastolic andend-systolic RV volumes and RV ejection fraction using a four-dimensional RV analysis program.12

QLAB (Philips Medical Systems) software was used for analysis ofreal-time three-dimensional colorDoppler images. From those images,we generated cross-sectional images of the vena contracta usingmulti-planar reconstruction images (Figure 2A). In detail, septal-lateral andanteroposterior longitudinal planes were generated by adjusting thelongitudinal plane axes on the cross-sectional short-axis image (greenand red lines in the bottom left panel) by the guidance ofmoving cross-sectional color and color-suppressed images of tricuspid annulus.Then, the location and direction of the longitudinal plane axes (redand green lines in the top panels) were adjusted along the longitudinalmid-portion of the TR jets in a midsystolic frame, and the cross-

sectional planes (blue lines in the upper panels) were moved tobecome orthogonal to the jet direction and consequently parallel tothe vena contracta. The location of the cross-sectional planewas deter-minedby the guidance of longitudinal and cross-sectional color imagesand set to the point at which the jet widths and cross-sectional areawere smallest. Generally, the location of the vena contracta wasmore easily noticed in the septal-lateral than in the anteroposterior lon-gitudinal plane in most cases. We confirmed using color-suppressedimages that the locations of the cross-sectional planes (blue lines inthe upper panels) were on the right atrial side of the tricuspid valvetips on the longitudinal planes (Figure 2B). The cross-sectional imageswere used to measure the septal-lateral vena contracta width, theanteroposterior vena contracta width, and the vena contracta area(Figure 3). Care was taken not to include blurred color signal artifactsinto the vena contracta area by double-checking with the color andcolor-suppressed longitudinal and cross-sectional images. The venacontracta circular index was defined as the septal-lateral vena con-tracta width divided by the anteroposterior vena contracta width.For quantification of functional TR severity, the effective regurgitantorifice area (EROA) was calculated using a proximal isovelocity sur-face area (PISA) method with the aliasing isovelocity set to about 28cm/s.3 EROA was calculated as follows: EROA = (2pr2 � Va)/PkVTR, where r is the radius from the orifice to the PISA outer shell ob-tained from real-time three-dimensional color Doppler images, Va isthe aliasing velocity, and PkVTR is the maximal velocity of the regurgi-tation TR jet obtained from two-dimensional continuous-waveDoppler echocardiography. Moderate TR was defined as EROA$0.2 cm2, while severe TRwas defined as EROA$0.4 cm2. For eval-uation of interobserver variability, septal-lateral and anteroposteriorvena contractawidths, vena contracta area, andEROAweremeasuredby two independent investigators using real-time three-dimensionalcolor Doppler images of 15 randomly selected patients.

Vena contractawidthswere alsomeasured from the lowparasternalfour-chamber and parasternal RV inflow views using two-dimensionalcolor Doppler echocardiography in 10 patients (Figure 4).

Statistical analyses were performed using SPSS (SPSS, Inc.,Chicago, IL). Data are expressed as mean 6 SD. Interobserver vari-ability was evaluated bymeans of the intraclass correlation coefficient.Comparisons between two paired variables were performed usingpaired t tests. Receiver operating characteristic curve analysis was per-formed to determine the best cutoff values for the identification ofmoderate and severe TR. Univariate linear regression analysis wasused to evaluate the correlation between two continuous variables.Multivariate analysis was used to identify independent geometric de-terminants of vena contracta widths and EROA. That based on step-wise multiple linear regression analysis was implemented, and thefinal model, which included variables with P values < .10, was derived.P values < .05 were considered to indicate significance.

RESULTS

Table 1 shows the mean absolute measurement values of echocardio-graphic parameters. As indicators of interobserver variability in three-dimensional measurements of TR severity, intraclass correlationcoefficientswere0.863 (P< .001) for septal-lateral vena contractawidth,0.894 (P < .001) for anteroposterior vena contracta width, 0.780(P = .004) for vena contracta area, and 0.939 (P < .001) for EROA.

Vena contracta widths measured on the septal-lateral (r = 0.782,P < .001) and anteroposterior (r = 0.761, P < .001) planes were found

Figure 1 Geometric measurements using full-volume images from three-dimensional echocardiography. (A) Three longitudinalplanes that perpendicularly cross the middle of each leaflet were generated using guidance from the short-axis image of the tricuspidvalve (top). On each of these three longitudinal planes, the leaflet tenting angle between the tricuspid annular line and the leaflet wasmeasured on a midsystolic frame (bottom). (B) Mutually perpendicular septal-lateral and anteroposterior longitudinal planes werecreated to measure septal-lateral and anteroposterior tricuspid annular diameters, RV inlet dimensions and mid-RV septal-lateraldimension.

Figure 2 Three-dimensional analysis of vena contracta using three-dimensional color Doppler images. (A) Septal-lateral and ante-roposterior longitudinal planes were generated by adjusting the longitudinal plane axes on the cross-sectional short-axis image (bot-tom left, green and red lines). Then, the location and direction of the longitudinal plane axes (top, red and green lines) were adjustedalong the longitudinal midportion of the TR jets in a midsystolic frame, and the cross-sectional planes (top, blue lines) were moved tobecome orthogonal to the jet direction and consequently parallel to the vena contracta. The location of the cross-sectional plane wasdetermined by the guidance of longitudinal and cross-sectional color images and set to the point at which the jet widths and cross-sectional area were smallest. (B) It was confirmed using color-suppressed images that the locations of the cross-sectional planes(top, blue lines) were on the right atrial side of the tricuspid valve tips (arrows) on the longitudinal planes.

Journal of the American Society of EchocardiographyVolume 24 Number 6

Song et al 665

to strongly correlate with EROA (Figure 5). Vena contracta area alsostrongly correlated with EROA (r = 0.808, P < .001), but the formerwas significantly larger than the latter (0.61 6 0.67 vs 0.22 6 0.22cm2, P < .001). The anteroposterior vena contracta width was foundto be 0.39 6 0.37 cm larger than the septal-lateral vena contracta

width (P < .001), and the difference between the twowidth values in-creased as EROA increased. The mean vena contracta circular indexwas 0.68 6 0.30 (range, 0.21–2.00) for the whole study populationand was 0.57 6 0.18 (range, 0.21–0.95) for patients with moderateand severe functional TR.

Figure 3 Measurements of vena contracta widths and area using three-dimensional color Doppler images in the same patient as inFigure 2. (A) Anterior, posterior, and septal tricuspid leaflets are identified in the color-suppressed cross-sectional image. (B) Septal-lateral vena contracta width (green arrow), anteroposterior vena contracta width (red arrow), and vena contracta area (white circle) aremeasured. Care was taken not to include blurred color signal artifacts into the vena contracta area by double-checking with the colorand color-suppressed longitudinal and cross-sectional images.

Figure 4 A representative example of measurement of venacontracta width (arrows) using two-dimensional color Dopplerimaging.


In receiver operating characteristic curve analysis, the areas underthe curves for the septal-lateral vena contracta width, anteroposteriorvena contracta width, and vena contracta area as determined byEROAwere 0.878, 0.910, and 0.903, respectively, for moderate func-tional TR (Figure 6), and 0.891, 0.896, and 0.889, respectively, for se-vere TR. The optimal cutoff values for septal-lateral vena contractawidth, anteroposterior vena contracta width, and vena contractaarea were found to be 0.63 cm (sensitivity, 82%; specificity, 83%),0.76 cm (sensitivity, 100%; specificity, 66%), and 0.37 cm2 (sensitiv-ity, 100%; specificity, 69%), respectively, for moderate functional TR,and 0.84 cm (sensitivity, 75%; specificity, 91%), 1.26 cm (sensitivity,88%; specificity, 80%), and 0.57 cm2 (sensitivity, 100%; specificity,64%), respectively, for severe functional TR.

Vena contracta widths measured from the low parasternal four-chamber view on two-dimensional color Doppler images tended tobe smaller than those measured from the RV inflow view, but therewas no statistical significance (0.97 6 0.34 vs 1.02 6 0.44 cm,P = .651) in 10 patients. Septal-lateral and anteroposterior vena con-tracta widthsmeasured from three-dimensional color Doppler imagescorrelated significantly with vena contracta widths measured from thelow parasternal four-chamber view and the RV inflow view on two-dimensional color Doppler images (r = 0.641, P = .046, andr = 0.810, P = .004), respectively (Figure 7). Anteroposterior venacontracta width was significantly larger than vena contracta widthmeasured from the RV inflow view (1.33 6 0.41 vs 1.02 6 0.44cm, P = .005), whereas septal-lateral vena contracta width tendedto be smaller than vena contracta width measured from the low para-sternal four-chamber view (0.786 0.29 vs 0.976 0.34 cm, P= .051).

Univariate analysis identified a number of variables that correlatedsignificantly with septal-lateral vena contracta width (Table 2) and an-teroposterior vena contracta width (Table 3). Multiple stepwise re-gression analysis showed that the septal leaflet tenting angle and theseptal-lateral annular diameter were independent determinants ofthe septal-lateral vena contracta width (Table 2), while the anteriorleaflet tenting angle and the anteroposterior annular diameter wereindependent determinants of the anteroposterior vena contractawidth (Table 3). In addition, the septal leaflet tenting angle, septal-lateral annular diameter, and septal-lateral RV inlet dimension werefound to be major determinants of EROA (Table 4).

DISCUSSION

Although vena contracta width is regarded as a useful parameter inTR quantification using two-dimensional color Doppler echocardiog-raphy, the two-dimensional view best suited to measure that widthhas not been established.3,4 In general, low parasternal four-chamber views and RV inflow views are used to visualize TR. Theseptal-lateral plane used in the present study is comparable witha low parasternal four-chamber view, while the present anteroposte-rior plane is similar to an RV inflow view, although the imaging planesacquired from three-dimensional and two-dimensional echocardiog-raphy should not be identical.

Table 1 Mean absolute measurement values ofechocardiographic parameters (n = 52)

Variable Value

Septal-lateral VC width (cm) 0.54 6 0.35

Anterolateral VC width (cm) 0.93 6 0.63

VC area (cm2) 0.61 6 0.67

EROA (cm2) 0.22 6 0.22

Maximal velocity of TR (cm/sec) 295 6 71

Tenting angles (�)Septal 24 6 17Anterior 21 6 13

Posterior 26 6 12Annular diameters (cm)

Septal-lateral 3.2 6 0.7Anteroposterior 3.5 6 0.7

RV dimensions (cm)Septal-lateral RV inlet 3.7 6 1.0

Anteroposterior RV inlet 4.8 6 1.0Septal-lateral mid-RV 3.1 6 1.0

Annulus to apical distance (cm) 6.1 6 1.2RV volumes (mL)

RV end-diastolic 158 6 76RV end-systolic 100 6 60

RV ejection fraction (%) 40 6 10

Data are expressed as mean 6 SD.VC, Vena contracta.


Song et al 667

In the present study, we found that the vena contracta cross-sectional shape in functional TR is ellipsoid with a long anteroposte-rior dimension. This finding indicates that different width valuesshould be used depending on the two-dimensional view when deter-mining the cutoff values for TR severity. We identified the optimalvena contracta width cutoff values for moderate and severe func-tional TR on the basis of the EROA calculated using the PISAmethod.The cutoff value was larger for the anteroposterior plane than theseptal-lateral plane. In clinical practice, the vena contracta width inTR is usually measured in a two-dimensional plane, where proximalconvergence and the distal jet can be best visualized, but the locationand angle of the planemay differ in each case, especially if the TR jet iseccentric.

We found that septal-lateral and anteroposterior vena contractawidths were closely linked to leaflet tenting and annular dilation inthe corresponding directions; that is, septal-lateral vena contractawidth was determined by septal-lateral annular diameter and sepalleaflet tenting, while anteroposterior vena contracta width was deter-mined by anteroposterior annular diameter and anterior leaflet tent-ing. These results suggest that vena contracta width in one directionis not simply proportional to another direction but is rather deter-mined by geometric alteration of the tricuspid apparatus located inthe corresponding direction. Consistent with this, we found that thevena contracta circular index range was quite wide, even thoughthe overall vena contracta cross-sectional shape was ellipsoidal oroval.

Another intriguing finding of the present study was that the venacontracta cross-sectional shape in functional TR was not triangularbut was ellipsoidal along the septal leaflet in most cases. This findingsuggests that functional TR stems from the gap between the septalleaflet and two other leaflets, and largely not from the gap betweenthe anterior and posterior leaflets (Figures 1 and 3). This may be at

least in part because the length between the annulus and the septalleaflet tip is short compared with those of the anterior and posteriorleaflets.13 Thus, the coaptation surface (i.e., the area of contact be-tween leaflets) may be larger in the junction between the anteriorand posterior leaflet than in the junction between the septal and othertwo leaflets in a normal tricuspid valve. Furthermore, there is no for-mal septal papillary muscle, as with the anterior and posterior papil-lary muscles.13,14 Because the small septal wall leaflet is fairly fixed,there is little room for movement if the free wall of the RV/tricuspid annulus should dilate. These anatomic characteristics ofthe RV and tricuspid apparatus may make the gap between theseptal and the other two leaflets most susceptible to thedevelopment of functional TR in cases of dilated annulus andleaflet tethering. Thus, it could be argued that tricuspid valveannuloplasty or repair should be carried out mainly to reduce thegap between the septal leaflet and the other two leaflets. Thathypothesis may be supported by the present finding that the septalleaflet tenting angle, septal-lateral annular diameter, and septal-lateral RV inlet dimension, which can be regarded as the main deter-minants of the distance between the septal and other two leaflets, alsoappeared to be major determinants of EROA. These results revealthat annular and RV dilation in the direction of the free wall, and sepalleaflet tenting and tethering, are more important in determining func-tional TR severity than anteroposterior annular and RV dilation ortethering of other leaflets.

Regarding vena contracta area, 0.75 or 1.0 cm2 was suggested asa marker of severe TR in a previous study,6 and those values werelarger than the cutoff value presented in our current study(0.57 cm2). This discrepancy might be at least in part attributed tothe differences in methods used for quantification of TR (distal jetarea/right atrial area vs EROA by PISA method) and in study popula-tions (functional TR in this study). Furthermore, as mentioned above,we tried our best not to include blurred color signal artifacts into thevena contracta area by double-checking with the color and color-suppressed longitudinal and cross-sectional images.

Study Limitations

The present study had several limitations. There was a substantial dif-ference between EROA by the PISAmethod and vena contracta areain this study. In principle, if the TR orifice is circular, the two measuresshould be almost identical. The differences we found here are difficultto explain, but there might be some potential reasons for the discrep-ancy. The PISA calculation presumes an axisymmetric flow conver-gence region, so that the surface area of a hemispheric region atwhich velocity aliasing can be demonstrated by color Doppler canbe calculated by knowing its radius. However, three-dimensionalechocardiographic studies in functional mitral regurgitation haveshown that the flow convergence region is often not circular butcan be elliptical and in some cases can be quite complex.15 The hemi-spheric PISA method was reported to underestimate asymmetricvena contracta area in patients with mitral regurgitation, and this dis-crepancy was relatively large in functional regurgitation.16,17 Withregard to TR, vena contracta of TR was reported to have more ofan elliptic shape, whereas that of mitral regurgitation is morecircular or oval.5 Therefore, ellipsoidal shape of vena contracta infunctional TR presented here might have resulted in the differencebetween the EROA by the PISA method and vena contracta area.Because the PISAmethod has pitfalls to be considered a gold standardin quantification of TR, it remains uncertain which method more ac-curately represents EROA of functional TR: direct measurement of

Figure 5 Correlations between EROA and the vena contracta (VC) widths in the anteroposterior (A-P) and septal-lateral (S-L) direc-tions (left) and between the EROA and the VC area (right).

Figure 6 Receiver operating characteristic curve analyses of septal-lateral (S-L) and anteroposterior (A-P) vena contracta (VC) widthsand VC area for moderate (left) and severe (right) functional TR determined by EROA. Arrows indicate best cutoff values.


vena contracta area or EROA by the PISAmethod. However, the factthat measurement variability appeared to be reasonably small (partic-ularly for EROA) might suggest that whether or not the three-dimensional method provides an accurate measure of TR severity,it might nonetheless be valuable for serial surveillance of TR severityin an individual patient. Inherent poor lateral spatial resolution ofcolor Doppler mapping with multiple aliasing in TR color Dopplerjet might at least in part lead to overestimation of a real orifice areaby vena contracta measurement,18-20 although lateral resolution ofvena contracta is considered to be highly accurate and feasible inmodern ultrasound systems. In a study using in vitro model, three-dimensional vena contracta reconstructed using color Dopplerimages overestimated gold standard EROAs quantified with laserflow visualization by approximately 25% because of the poor lateralresolution of the color Doppler system, which caused bleeding of theflow signal past the edges of the proximal jet.20 Dealiasing colorDoppler flow or multibeam high pulse repetition frequency three-dimensional color Doppler may help overcome this pitfall of colorDoppler mapping.21,22 The timing of measurement mightcontribute to the discrepancy between the two measurements.

PISA radius was measured at the midsystolic frame, when thetricuspid valve tenting appeared to be smallest, and maximalvelocity of the TR jet was measured using two-dimensional continu-ous-wave Doppler profile. Although vena contracta was measuredat the midsystolic frame, the time of the frame might be deviatedfrom the peak systole time concordant with the peak continuous-wave velocity, because of a low temporal resolution of the three-dimensional color Doppler images. Because there must be dynamicvariation of EROA of functional TR during a systole phase, the dis-crepancy between the times of measurements leads to overestimationof the vena contracta area. The color Doppler images obtained usingthe real-time three-dimensional echocardiography might overesti-mate the true orifice size more than might two-dimensional colorDoppler images, because of relatively lower spatial and temporal res-olutions of three-dimensional echocardiography. Therefore, the cut-off values of vena contracta widths and area identified here maynot be directly applicable to clinical practice using two-dimensionalcolor Doppler echocardiography.

We were not able to confirm ellipsoidal vena contracta of func-tional TR using two-dimensional color Doppler images. Even though

Figure 7 (A) Correlation between septal-lateral vena contracta (VC) widths measured from three-dimensional color Doppler imagesand VC widths measured from low parasternal four-chamber view on two-dimensional color Doppler images, and (B) correlation be-tween anteroposterior VC widths measured from three-dimensional color Doppler images and VC widths measured from RV inflowview on two-dimensional color Doppler images.Red lines represent lines of identity, while black lines and dashed lines represent linesof linear regression and 95% confidence interval, respectively.

Table 2 Univariate and multivariate linear regressionanalyses for septal-lateral vena contracta in functional TR

Variable r Univariate P Multivariate P

Age 0.098 .488Maximal velocity of TR 0.358 .009

Tenting anglesSeptal 0.553 <.001 .003

Anterior 0.558 <.001Posterior 0.539 <.001

Annulus diametersSeptal-lateral 0.585 <.001 .001

Anteroposterior 0.387 .005RV dimensions

Septal-lateral RV inlet 0.459 .001Anteroposterior RV inlet 0.363 .008

Septal-lateral mid-RV 0.390 .004Annulus to apical distance 0.341 .013

RV volumesRV end-diastolic 0.406 .003

RV end-systolic 0.448 .001RV ejection fraction �0.480 <.001

Table 3 Univariate and multivariate linear regressionanalyses for anteroposterior vena contracta in functional TR

Variable r Univariate P Multivariate P


Tenting anglesSeptal 0.562 <.001

Anterior 0.633 <.001 <.001

Posterior 0.571 <.001

Annulus diametersSeptal-lateral 0.571 <.001

Anteroposterior 0.427 .002 .017

RV dimensions

Septal-lateral RV inlet 0.505 <.001Anteroposterior RV inlet 0.465 <.001

Septal-lateral mid-RV 0.431 <.001Annulus to apical distance 0.346 .012


RV end-systolic 0.497 <.001RV ejection fraction �0.560 <.001


Song et al 669

good correlations were found between vena contracta widths mea-sured using three-dimensional and two-dimensional color Dopplerimages, anteroposterior vena contracta width was significantly largerthan vena contracta width measured from the RV inflow view,whereas septal-lateral vena contracta width tended to be smallerthan vena contracta width measured from the low parasternal four-chamber view. We believe this was caused by the difference betweenimaging planes of those two views, because investigators obtainedstandard views without knowing three-dimensional vena contractashape during implementation of this study. This difference might beminimized if the appropriate septal-lateral and anteroposterior planesthat showed the minimal and maximal vena contracta widths couldbe obtained with the best effort by means of rotating and tilting thetwo-dimensional echocardiographic probe. Furthermore, considering

the echocardiographic valvular anatomy, we suggest that the antero-posterior plane derived from the present study must be obtained us-ing two-dimensional echocardiography by rotating probe moreclockwise from the standard RV inflow view, while the septal-lateralplane can be generated by rotating probe a bit more counterclockwisefrom the standard parasternal low four-chamber view. Furtherinvestigations are necessary to apply the results presented here usingthree-dimensional color Doppler images to two-dimensional venacontracta measurements.

PISAwas not used as referencemethod for assessing TR severity butwas used as a comparative method that is not established for quantify-ing TR. The choice of EROA$0.2 cm2 to describe moderate TRmaybe arbitrary, and calculating EROA is not an established method forquantifying TR at this moment.3,23 Therefore, the cutoff values of

Table 4 Univariate and multivariate linear regressionanalyses for EROA in functional TR

r Univariate P Multivariate P


Tenting anglesSeptal 0.548 <.001 <.001

Anterior 0.471 <.001Posterior 0.400 .003

Annulus diametersSeptal-lateral 0.572 <.001 <.001

Anteroposterior 0.392 .004RV dimensions

Septal-lateral RV inlet 0.388 .004 .004

Anteroposterior RV inlet 0.286 .040

Septal-lateral mid-RV 0.280 .045Annulus to apical distance 0.294 .035


RV end-systolic 0.377 .006RV ejection fraction �0.287 .041


EROA for mitral regurgitation had to be used for TR in this study.3

EROA was calculated using the PISA method under the assumptionthat the PISA shape was hemispherical. However, we found that thePISA projectional shape was ellipsoidal, like that of the vena contractacross-section, and therefore the true EROA might be larger than theEROA calculated using a hemispherical shape assumption.However, the hemispherical geometric assumption had to be usedin calculating the EROA, because there is no validated method of cal-culating the EROAwith an oval-shaped PISA in TR patients.

CONCLUSIONS

This investigation using three-dimensional color Doppler images indi-cated that different vena contracta width cutoff values should beapplied according to the plane of view in functional TR, becausethe vena contracta cross-sectional shape is ellipsoidal with a longanteroposterior direction. Vena contracta widths are determined byannular dilation and leaflet tenting in the corresponding directions.We believe these findings will have a significant impact in the assess-ment of functional TR.

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The Vena Contracta in Functional Tricuspid Regurgitation: A Real-Time Three-Dimensional Color Doppler Echocardiography Study