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American Society of Echocardiography: Recommendations for Evaluation of the Severity of Native Valvular Regurgitation with Two-dimensional and Doppler Echocardiography

American Society of Echocardiography: Recommendations for Evaluation of the Severity of Native Valvular Regurgitation with Two-dimensional and Doppler Echocardiography
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  GUIDELINESAmerican Society of Echocardiography:Recommendations for Evaluation of the Severityof Native Valvular Regurgitation withTwo-dimensional and Doppler Echocardiography A Report from the American Society of Echocardiography’sNomenclature and Standards Committee and The Task Forceon Valvular Regurgitation, Developed in Conjunction with theAmerican College of Cardiology Echocardiography Committee,The Cardiac Imaging Committee, Council on Clinical Cardiology,The American Heart Association, and the European Society ofCardiology Working Group on Echocardiography, Represented by: W. A. Zoghbi, M. Enriquez-Sarano, E. Foster, P. A. Grayburn, C. D. Kraft,R. A. Levine, P. Nihoyannopoulos, C. M. Otto, M. A. Quinones, H. Rakowski,W. J. Stewart, A. Waggoner and N. J. Weissman  American Society of Echocardiography, 1500 Sunday Drive, Suite 102, Raleigh, NC 27607, USA Introduction Valvular regurgitation has long been recognized as animportant cause of morbidity and mortality. Al-though the physical examination can alert theclinician to the presence of significant regurgitation,diagnostic methods are often needed to assess theseverity of valvular regurgitation and remodeling of the cardiac chambers in response to the volumeoverload state. Echocardiography with Doppler hasrecently emerged as the method of choice for thenoninvasive detection and evaluation of the severityand etiology of valvular regurgitation. This articleoffers a critical review of echocardiographic andDoppler techniques used in the evaluation of valvularregurgitation in the adult patient, and providesrecommendations for the assessment of severity of valvular regurgitation based on the scientific litera-ture and a consensus of a panel of experts. Issues of medical management and timing of surgical inter-vention will not be addressed in this article, as thesehave been recently published [1] . Two-dimensional and DopplerEchocardiography in ValvularRegurgitation: General Considerations Valvular regurgitation or incompetence results fromvarious etiologies including valvular degeneration,calcification, fibrosis or infection, alteration of thevalvular support apparatus or dilatation of the valveannulus. These conditions cause poor apposition of the valvular leaflets or cusps, and may lead to Reprinted from the Journal of the American Society of Echo-cardiography, July 2003, Vol. 16, No. 7, pp. 777 e 802.These recommendations are endorsed by the American College of Cardiology (ACC), the American Heart Association (AHA), andthe European Society of Cardiology (ESC). Representative fromthe ACC Echocardiography Committee: Elyse Foster, MD;representative from the Cardiac Imaging Committee, Council onClinical Cardiology, AHA: Miguel A. Quinones, MD; representa-tive from the ESC Working Group on Echocardiography: PetrosNihoyannopoulos, MD.Address document reprint requests to the American Society of Echocardiography, 1500 Sunday Drive, Suite 102, Raleigh, NC27607, USA. Tel: +1 919 787-5181. Received 17 June 2003; accepted 24 July 2003.Eur J Echocardiography  (2003)  4,  237 e 261doi:10.1016/j.euje.2003.07.0011525-2167/03/$30.00/0    2003 The American Society of Echocardiography. Published by Elsevier Ltd. All rights reserved.  b  y  g u e s  t   onM a y  8  ,2  0 1  6 D  ownl   o a d  e d f  r  om   prolapse, flail, restricted leaflet motion or valvularperforation. With the advent of Doppler techniquesthat are sensitive to detection of regurgitation, trivialand physiologic valvular regurgitation, even ina structurally normal valve, is now well recognizedand is noted to occur frequently in right-sided valves.The following sections describe general considera-tions of the role of echocardiographic and Dopplertechniques in the evaluation of regurgitant lesions. Role of Two-Dimensional Echocardiography Two-dimensional (2D) echocardiography allows anevaluation of the valvular structure as well as theimpact of the volume overload on the cardiacchambers. Calcifications, tethering, flail motion orvegetations can be readily assessed, which can giveindirect clues as to the severity of regurgitation.While prolapse, vegetations or calcifications are notnecessarily associated with significant regurgitation,a flail leaflet almost always is. In the cases of non-diagnostic transthoracic studies, transesophagealechocardiography (TEE) improves the visualizationof the valvular structure and delineates the mecha-nism and severity of regurgitation.The duration (acute or chronic) and severity of valvular regurgitation are among the most importantdeterminants of the adaptive changes that occur in thecardiac chambers in response to the regurgitantvolume. Thus, a chronic significant regurgitation isusually accompanied by an increase in size and hyper-trophy of the involved cardiac chambers whereassignificant regurgitation of acute onset from a condi-tion such as endocarditis may not result acutely in thisremodeling. While cardiac chamber remodeling is notspecific for the degree of regurgitation (i.e. occurs incoronary artery disease, congestive cardiomyopathyetc.), its absence in the face of chronic regurgitationshould imply a milder degree of valvular insufficiency.Once a diagnosis of significant regurgitation isestablished, serial 2D echocardiography is currentlythe method of choice for assessing the progression of the mechanical impact of regurgitation on cardiacchamber structure and function. Recommendationsfor determination of ventricular volumes and ejectionfraction have been previously published [2] . These,along with clinical evaluation are needed for ade-quate timing of surgical intervention. Doppler Methods for Evaluation of Valvular Regurgitation Doppler echocardiography is the most commontechnique used for the detection and evaluation of severity of valvular regurgitation. Several indices havebeen developed to assess the severity of regurgitationusing color Doppler, pulsed wave (PW) and contin-uous wave (CW) Doppler. Details of the Dopplertechniques and the methods involved in obtainingthese parameters are described in a recently publishedarticle from the American Society of Echocardiogra-phy on quantification of Doppler Echocardiogra-phy [3] . The following sections summarize the salientfeatures of these techniques for the purposes of evaluation and quantitation of valvular regurgitation. Color Doppler  Color flow Doppler is widely used for the detection of regurgitant valve lesions. This technique provides Figure 1.  Color flow recording of a mitral regurgitation jet obtained from a zoomed view in the parasternal long axisdepicting the three components of the regurgitant jet: flow convergence, vena contracta (VC), and jet area in the leftatrium. Measurement of the vena contracta is shown between the red arrows. 238 W. A. Zoghbi  et al. Eur J Echocardiography, Vol. 4, issue 4, December 2003  b  y  g u e s  t   onM a y  8  ,2  0 1  6 D  ownl   o a d  e d f  r  om   visualization of the srcin of the regurgitation jet andits width (vena contracta), the spatial orientation of the regurgitant jet area in the receiving chamber and,in cases of significant regurgitation, flow convergenceinto the regurgitant orifice (Fig. 1). Experience hasshown that attention to these three componentsof the regurgitation lesion by color Doppler  d  asopposed to the traditional regurgitant jet areaalone  d  significantly improves the overall accuracyof estimation and quantitation of the severity of regurgitation with color Doppler techniques. The sizeof the regurgitation jet by color Doppler and itstemporal resolution, however, are significantly affect-ed by transducer frequency and instrument settingssuch as gain, output power, Nyquist limit, size anddepth of the image sector [4] . Thus, full knowledge bythe sonographer and interpreting echocardiographerof these issues is necessary for optimal imageacquisition and accuracy of interpretation. Jet area   Visualization of the regurgitant jet area inthe receiving chamber can provide a rapid screeningof the presence and direction of the regurgitant jetand a semi-quantitative assessment of its severity. In-general, a larger area may translate into a moresignificant regurgitation. However, the sole relianceon this parameter can be quite misleading. Numeroustechnical, physiologic and anatomic factors affect thesize of the regurgitant area and therefore alter itsaccuracy as an index of regurgitation severity [4] . Jetsize is affected by instrument factors, especially pulserepetition frequency (PRF) and color gain. Standardtechnique is to use a Nyquist limit (aliasing velocity)of 50 e 60 cm/s, and a color gain that just eliminatesrandom color speckle from non-moving regions. Jetarea is inversely proportional to PRF, and substantialerror can be introduced with the use of higher orlower settings than the nominal settings to whichechocardiographers have become accustomed. Re-garding hemodynamic factors, eccentric, wall-im-pinging jets appear significantly smaller thancentrally directed jets of similar hemodynamicseverity, mainly because they flatten out on the wallof the receiving chamber. Their presence, however,should also alert to the possibility of structuralabnormalities of the valve (e.g. prolapse, flail, orperforation), frequently in the leaflet or cusp oppositeto the direction of the jet. Lastly, color flow area isalso influenced by flow momentum d the product of flow rate and velocity. Thus a jet may appear largerby increasing the driving pressure across the valve;hence the importance of measuring blood pressurefor left heart lesions at the time of the echocardio-graphic examination, particularly in the intraoper-ative setting. Vena contracta   The vena contracta is the narrowestportion of a jet that occurs at or just downstreamfrom the orifice (Fig. 1). It is characterized by highvelocity, laminar flow and is slightly smaller than theanatomic regurgitant orifice due to boundary effects.Thus, the cross-sectional area of the vena contractarepresents a measure of the effective regurgitantorifice area (EROA), which is the narrowest area of actual flow. The size of the vena contracta isindependent of  flow rate and driving pressure fora fixed orifice [5] . However, if the regurgitant orifice isdynamic, the vena contracta may change with hemo-dynamics or during the cardiac cycle [6] . Comprised of high velocities, the vena contracta is considerably lesssensitive to technical factors such as PRF comparedto the jet in the receiving chamber. To specificallyimage the vena contracta, it is often necessary toangulate the transducer out of the normal echocar-diographic imaging planes such that the area of proximal flow acceleration, the vena contracta, andthe downstream expansion of the jet can be distin-guished. It is preferable to use a zoom mode tooptimize visualization of the vena contracta andfacilitate its measurement. The color flow sectorshould also be as narrow as possible, with the leastdepth, to maximize lateral and temporal resolution.Because of the small values of the width of the venacontracta (usually  ! 1 cm), small errors in itsmeasurement may lead to a large percent error andmisclassification of the severity of regurgitation,hence the importance of accurate acquisition of theprimary data and measurement. Proximal isovelocity surface area (PISA) or flow convergence   The PISA method is derived from thehydrodynamic principle stating that, as blood ap-proaches a regurgitant orifice, its velocity increasesforming concentric, roughly hemispheric shells of increasing velocity and decreasing surface area [7] .Color flow mapping offers the ability to image one of these hemispheres that corresponds to the Nyquistlimit of the instrument. If a Nyquist limit can bechosen at which the flow convergence has a hemi-spheric shape, flow rate (ml/s) through the regurgi-tant orifice is calculated as the product of the surfacearea of the hemisphere (2 p r 2 ) and the aliasing velocity(Va) as 2 p r 2 ) Va (Fig. 2). Assuming that the maximalPISA radius occurs at the time of peak regurgitantflow and peak regurgitant velocity, the maximalEROA is derived as:EROA  ¼ ð 6 : 28r 2 ) Va Þ = PkV Reg where PkV Reg  is the peak velocity of the regurgitant jet by CW Doppler. The regurgitant volume can beestimated as EROA multiplied by the velocity timeintegral of the regurgitant jet. Since the PISAcalculation provides an instantaneous peak flow rate,EROA by this approach is the maximal EROA andmay be slightly larger than EROA calculated byother methods.Measurement of PISA by color flow mappingrequires adjustment of the aliasing velocity such thata well-defined hemisphere is shown. This is generallyRecommendations for Assessing Valvular Regurgitation 239 Eur J Echocardiography, Vol. 4, issue 4, December 2003  b  y  g u e s  t   onM a y  8  ,2  0 1  6 D  ownl   o a d  e d f  r  om   done by shifting the baseline toward the direction of flow, or by lowering the Nyquist limit, or both (thelatter reduces the wall filter, whereas the former doesnot) [8] . If the base of the hemisphere is not a flatsurface (180 ( ), then correction for wall constraintshould be performed, multiplying by the ratio of theangle formed by the walls adjacent to the regurgitantorifice and 180 ( . This has been shown to improve thereliability of the measurement [9] .The limitations of PISA have been reviewed indetail [10] . It is more accurate for central jets than foreccentric jets, and for regurgitation with a circularorifice. If the image resolution allows the flowconvergence to be seen well, and a Nyquist limitcan be chosen at which the flow convergence hasa hemispheric shape, it is easy to identify the aliasingline of the hemisphere. However, it can be difficult to judge the precise location of the orifice and the flowconvergence shape. Any error introduced is thensquared, which can markedly affect the resulting flowrate and EROA. Recent modifications of the de-scribed PISA method use the distance between twoaliasing contours to circumvent the errors fromimprecise location of the orifice in the standard PISAformula, and automate localizing the most hemi-spheric shape [11] . Although promising, further expe-rience is needed with these methods.All the color Doppler parameters discussed aboveprovide instantaneous measures of regurgitationseverity. Criteria for these maximum instantaneousmeasurements corresponding to the severity of eachlesion assume a pan-systolic (or pan-diastolic) dura-tion. However, in some circumstances, such as mitralvalve prolapse, the duration of regurgitation may bebrief  [12] and can be suspected from real-time, 2Dcolor Doppler. A time-based graphic, such as CWDoppler or color M mode, can better ascertain thisfinding. Although graphing the actual duration of such flow patterns has not been systematicallystudied, a correction of color flow indices of regurgi-tation for the duration of regurgitation is advised. Pulsed Doppler Quantitative Flow Methods  PW Doppler recordings of flow velocity can becombined with 2D measurements to derive flow ratesand stroke volume [13] . The technical details involvedin making these measurements and their sources of error are described in the article on Quantitation of Doppler Echocardiography [3] . This method is simplein theory but accurate results require individualtraining (e.g. practice in normal patients where thestroke volumes at different sites are equal). Briefly,stroke volume (SV) at any valve annulus d the leastvariable anatomic area of a valve apparatus  d  isderived as the product of cross-sectional area (CSA)and the velocity time integral (VTI) of flow at the Figure 2.  Schematic depiction of the flow convergence or proximal isovelocity surface area (PISA) method for quantitatingvalvular regurgitation. Va is the velocity at which aliasing occurs in the flow convergence towards the regurgitant orifice.PkV Reg  Z  peak velocity of the regurgitant jet, determined by continuous wave Doppler. Reg flow  Z  regurgitant flow;EROA  Z  effective regurgitant orifice area; Reg jet  Z  regurgitation jet. 240 W. A. Zoghbi  et al. Eur J Echocardiography, Vol. 4, issue 4, December 2003  b  y  g u e s  t   onM a y  8  ,2  0 1  6 D  ownl   o a d  e d f  r  om   annulus. Assumption of a circular geometry hasworked well clinically for most valves with theexception of the tricuspid annulus. Thus,SV  ¼  CSA ! VTI  ¼ p d 2 = 4 ! VTI  ¼  0 : 785d 2 ! VTIwhere d is the diameter of the annulus. Calculationsof stroke volume can be made at two or moredifferent sites  d  left ventricular outflow tract(LVOT), mitral annulus, and pulmonic annulus. Inthe absence of regurgitation, stroke volume determi-nations at these sites are equal. In the presence of regurgitation of one valve, without any intracardiacshunt, the flow through the affected valve is largerthan through other competent valves. The differencebetween the two represents the regurgitant vol-ume [14,15] . Regurgitant fraction is then derived asthe regurgitant volume divided by the forward strokevolume through the regurgitant valve. Thus,Regurgitant Volume  ¼  SV RegValv   SV CompValv Regurgitant Fraction ¼ ð SV RegValv   SV CompValv Þ = SV RegValv where SV RegValv  is stroke volume derived at theannulus of the regurgitant valve and SV CompValv  is thestroke volume at the competent valve. EROA can becalculated similar to the PISA method as regurgitantvolume divided by the velocity time integral of theregurgitant jet velocity (VTI RegJet ) recorded by CWDoppler as:EROA  ¼  Regurgitant Volume = VTI RegJet The most common errors encountered in determiningthese parameters are (1) failure to measure the valveannulus properly (error is squared in the formula), (2)failure to trace the modal velocity (brightest signalrepresenting laminar flow) of the pulsed Dopplertracing and (3) failure to position the sample volumecorrectly, and with minimal angulation, at the level of the annulus. Furthermore, in the case of significantcalcifications of the mitral annulus and valve, quan-titation of flow at the mitral site is less accurate andmore prone to errors.In left sided regurgitant lesions, SV RegValv  or totalstroke volume of the ventricle can also be measuredusing left ventricular volume calculations by 2Dechocardiography as end-diastolic volume minusend-systolic volume. Methods for calculation of leftventricular volumes have been previously detailed [2] .Measurement of left ventricular volumes by echocar-diography has the potential pitfall of underestimatingtrue left ventricular volume and therefore under-estimating regurgitation severity. Recently, the use of intravenous contrast agents that cross the pulmonarycirculation has shown promise in facilitating thetracing of the ventricular endocardium and improv-ing the accuracy and reproducibility of volume mea-surements [16,17] . Assessment of ventricular volumesbased on M-mode echocardiography has importantlimitations and is not recommended. Other Pulsed and Continuous Wave Doppler Methods  There are several pulsed and CW Doppler methodsthat give indirect clues to the significance of valvularregurgitation. In general, the density of the spectraldisplay of a regurgitant jet is proportional to thenumber of red cells exhibiting regurgitation and is aqualitative index of severity. Other parameters resultfrom the hemodynamic consequences of the severityof regurgitation and are more valve specific (atrio-ventricular valve vs aortic or pulmonic valve). Foratrio-ventricular valves, these parameters include themagnitude of the early inflow velocity (E), thepulmonary or hepatic venous inflow pattern, andthe contour or shape of the regurgitant jet by CWDoppler. For aortic and pulmonic valve insufficiency,the parameter used is the rate of deceleration of theregurgitant jet velocity (pressure half-time), whichreflects the rapidity of equilibration of diastolicarterial and ventricular pressures. Another index of severity of aortic insufficiency is the magnitude of diastolic flow reversal in the aorta. Although helpfulin the overall evaluation of regurgitation, theseparameters are in general sensitive but less specificfor the severity of regurgitation, as they are in-fluenced by other hemodynamic and clinical condi-tions. These methods will be discussed in detail foreach valve (see below). Doppler Methods in Acute vsChronic Regurgitation Color Doppler measures are particularly deceptive inacute regurgitation, leading to the clinical paradox of apparently small jet size in a critically ill patient,especially from the transthoracic echocardio-gram [18,19] . This is related in part to technical factors,particularly insufficient color Doppler temporalresolution in the tachycardic patient; practically,frame rate should therefore be maximized [20] . TEEhas been felt to provide a more sensitive view, and thedecreased depth also maximizes f rame rate particu-larly for mitral regurgitation [18,19] . More fundamen-tally, however, the short duration of regurgitationand small receiving chambers limit the maximaldevelopment of jet area, and the rapid equalizationof pressures diminishes orifice velocity, jet momen-tum, and therefore jet area [21,22] . The proximal jet orvena contracta remains reliable in this setting, as doespulsed Doppler quantitation. Doppler hemodynamicsigns of elevated receiving chamber pressures, such asshort aortic insufficiency pressure half-time, earlytruncation of mitral regurgitant velocities, and pul-monary venous flow reversal, are particularly inform-ative in this setting, and may provide the only clues tosignificant regurgitation. In this clinical scenario of Recommendations for Assessing Valvular Regurgitation 241 Eur J Echocardiography, Vol. 4, issue 4, December 2003  b  y  g u e s  t   onM a y  8  ,2  0 1  6 D  ownl   o a d  e d f  r  om 
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