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Visual Assessment of Valvular Regurgitation: Comparison With Quantitative Doppler Measurements
Visual Assessment of Valvular Regurgitation: Comparison With Quantitative Doppler Measurements J. Miguel Rivera, MD, PhD,' Pieter M. Vandervoort, MD, Eleanor Morris, BS, Arthur E. Weyman, MD, FACC, and James D. Thomas, MD, FACC, Cleveland, Ohio, and Boston, Massachusetts
To investigate which factors influence visual evaluation and how accurate it is in patients with valvular insufficiency, 83 patients were studied. All were in sinus rhytlun, 43 with mitral and 40 with tricuspid regurgitation. Categoric visual grading (mild, moderate, and severe) was compared with jet area method and regurgitant fraction and the factors that influenced the assigned rank were identified. With jet area method (mean of areas in three planes), the correlation with regurgitant fraction was r = 0.61 for free jets and r = 0.32 for wall jets (overall r = 0.47) in patients with mitral regurgitation, and r = 0.81 and r = 0.46 for free and wall jets, respectively, in patients with tricuspid regurgitation (overall, r = 0.65). With visual grading, the correlation was for free and wall jets, respectively, p = 0.80 and p = 0.74 (overall p = 0.76) in patients with mitral regurgitation, and p = 0.79 and p = 0.49 for free and wall jets, respectively (overall p = 0.62), in patients with tricuspid regurgitation. The jet area parameter found to have the most influence on visual grading was the average area in three planes divided by atrial area, with p = 0.80 and p = 0.51 in patients with mitral regurgitation (free and impinging jets respectively) and p = 0.60 and p = 0.46 in tricuspid regurgitation. We conclude that visual grading of valvular regurgitant jets correlates well with quantitative measures of valvular incompetence and better than any simple jet area method. Integrating additional information available from two-dimensional and Doppler images allows an accurate assessment of distorted wall jets in mitral regurgitation, but in tricuspid regurgitation the visual evaluation of impinging jets is less accurate. (J AM Soc EcHOCARDIOGR 1994; 7:480-7.)
N onvasive assessment of valvular insufficiency has improved substantially in recent years. The regurgitant jet Doppler color-flow mapping provides an easy, semiquantitative estimation of the severity of the lesion. 1•2 It is now well established that displayed regurgitant jet dimensions are influenced by physical factors other than the regurgitant flow, 3- 14 including constraining effects of the receiving chamber12•13 and
From the Department of Cardiology, Cleveland Clinic Foundation, and the Noninvasive Cardiac Laboratory, Massachusetts General Hospital. 'Supported in part by a Fondo de Investigaciones Sanitarias, Madrid, Spain. bSupported in part by the Bayer Fund for Cardiovascular Research, New York, New York. Reprint requests: J. M. Rivera, MD, c "- Periodista Badia ll, pt 1, Valencia 46010, Spain. Copyright© 1994 by the American Society ofEchocardiography. 0894-7317/94$3.00 + 0 27/1/55191
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instrumentation factors such as wall filter, gain, pulse repetition frequency, and transducer frequency. 15- 17 However, simple visual assessment of the regurgitant jet has become the most common approach to evaluate valvular insufficiency in clinical practice. With this method, the echocardiographer not only appreciates the regurgitant jet dimensions but also integrates information on jet dynamics and chamber geometry toward an educated semiquantitative assessment, which is of particular importance for the appraisal of eccentrically directed wall jets. To determine the factors that impact the echocardiographer in grading valvular regurgitation and to assess the accuracy of simple visual assessment, we studied 83 patients, 43 with mitral regurgitation and 40 with tricuspid regurgitation. To test the accuracy of both jet area and visual methods, regurgitant fraction was calculated from quantitative Doppler-echocardiographic measurements. Jet area parameters and visual grade were also correlated with each other to find
Journal of the American Society of Echocardiography Volume 7 Number 5
which jet area parameter most influences visual evaluation. MEmODS
Clinical Study Patient population. Patients were studied by one research technician and screened for the following selection criteria: ( 1) presence of mitral or tricuspid regurgitation in the color Doppler display and (2) availability of high-quality two-dimensional images and Doppler tracings to allow for accurate mitral, aortic, tricuspid, and pulmonary flow calculations by the Doppler I two-dimensional echocardiographic method. Patients with mitral or tricuspid stenosis, accompanying pulmonary or aortic valve disease, or intracardiac shunt flow were excluded. Eighty-three patients met the criteria for the study, 50 females and 33 males, with a mean age of 65 ± 17 years (age range 14 to 95 years). All83 patients were in sinus rhythm at the time of the study. The underlying cardiac diseases included ischemic heart disease in 45 patients, mitral valve prolapse in eight patients, mitral rheumatic heart disease in 17 patients, pericardial effusion in four patients, dilated cardiomyopathy in one patient, and absence of detectable morphologic lesions in eight patients. Echocardiographic data. All two-dimensional, pulsed, and Doppler color-flow data were obtained as part of the routine echocardiographic evaluation. Commercially available echo-Doppler machines (model 77020A or Sonos 1000; Hewlett-Packard Corp., Andover, Mass.) equipped with a standard 2.5 MHz transducer were used for the study. All images and spectral flow profiles were recorded on 1/2-inch videotape for off-line analysis. Color Doppler images for analysis of mitral regurgitation were obtained in apical four-chamber, parasternal short-axis, and parasternal long-axis views. For analysis of tricuspid regurgitation, images were obtained in apical four-chamber, parasternal right inflow, and parasternal short-axis views at pulse repetition frequencies of 3.9 to 4.8 kHz. The typical Nyquist velocity was 58 cm/ sec at a scanning depth of 16 cm. Doppler settings were kept constant during the examinations. Each color Doppler examination was performed with the narrowest sector angle possible (30 degrees) to maximize the color-flow imaging frame rate (15 to 17Hz). Data Analysis
All M-mode tracings, two-dimensional images, Doppler spectra, and color Doppler images were an-
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alyzed off-line with a computer analysis system (Sony SUM 1010). All measurements were averaged over three cardiac cycles. Right ventricular Doppler-two-dimensional echocardiographic method. Our overall approach to the pulsed Doppler quantification of tricuspid regurgitation has been detailed previously. According to the method of Meijboom et al. 18•19 and ValdesCruz et al., 20•21 we obtained tricuspid forward flow as the product of diastolic tricuspid orifice area, tricuspid inflow time-velocity integral, and heart rate. Pulmonary forward flow was obtained by multiplying systolic pulmonary annular area, pulmonic annular time-velocity integral, and heart rate. In the absence of pulmonic regurgitation or abnormal shunt flow, the tricuspid regurgitant flow is determined by the difference between tricuspid inflow and pulmonic outflow. 22•23 Validation. To validate this procedure in our laboratory, tricuspid stroke volume was calculated according to the previously described Doppler method in 14 patients without tricuspid or pulmonary regurgitation and compared with simultaneously acquired thermodilution data for stroke volumes ranging from 41.5 to 125 cm3 (71.8 ± 21.4 cm3 ); the difference (thermodilution minus tricuspid) in stroke volume was -3.4 ± 8.9 cm3 with an overall correlation of r = 0. 93. In another group of 13 patients without tricuspid or pulmonary regurgitation, tricuspid and pulmonary stroke volume were calculated. The difference (tricuspid minus pulmonary) in stroke volume for the two methods was found to be - 0.5 ± 3.29 cm3 with an overall correlation of r = 0.95. Left ventricular Doppler-two-dimensional echocardiographic method. Our overall approach to pulsed Doppler quantification of mitral regurgitation has recently been described in detail. 13 With the method of Fischer et al., 24 we obtained mitral forward flow as the product of mean diastolic mitral orifice area, mitral inflow time-velocity integral, and heart rate. Aortic forward flow was obtained by multiplying systolic aortic annular area, aortic annular time-velocity integral, and heart rate. 25 In the absence of aortic regurgitation or abnormal shunt flow, the mitral regurgitant flow is determined by the difference between mitral inflow and aortic outflow. 23 •26 Validation. To validate this procedure in our laboratory, mitral stroke volume was calculated according to the previously described Doppler method in 14 patients without mitral or aortic regurgitation and compared with simultaneously acquired thermodilution data. For stroke volumes ranging from 43 to
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131 cm3 (75.3 ± 27 cm3 ), the difference (thermodilution minus mitral; mean ± SD) in stroke volume was 2.0 ± 8.3 cm3 with an overall correlation of r = 0.96. In another group of 36 patients without mitral or aortic regurgitation, mitral and aortic stroke volume were calculated. The difference (mitral minus aortic) in stroke volume for the two methods was found to be 1. 7 ± 3.4 cm3 with an overall correlation ofr = 0.97. Jet area method. For jet areas, an optimal gain setting was obtained by maximizing the gain level without introducing signals in the nonflow areas. Videotape recordings of images were scanned frame by frame to find the largest regurgitant jet area. The contour of the maximal jet area was then traced with a light pen and measured by computerized planimetry. The traced jet area included the centrally aliased and peripherally nonaliased signals. 2•3 When it was possible, atrial area was measured by computerized planimetry in the same frame in which the maximal jet area was seen. Otherwise, a representative frame from the same view was analyzed during the same portion of systole. We also measured linear dimensions of the color-Doppler jet (length, width, and height), as well as its proximal width at the regurgitant orifice. Jets were classified into two types: free jets, in which the full regurgitant jet was contained within the cavity of the atrium in the three standard imaging planes (parasternal right ventricular inflow, apical four-chamber, and parasternal short-axis views for tricuspid regurgitation and parasternal long and short-axis and apical four-chamber axis views for mitral regurgitation), and wall jets, which struck the inferior, anterior, lateral, or septal lateral wall in one or more views. Jets that were constrained by the superior atrial wall alone were classified as free jets. 13 Visual grading method. As a part of clinical routine in the laboratory, regurgitation was graded as mild, moderate, and severe. 2 •3 For purposes of analysis, we assigned tht value 1 to mild, 2 to moderate, and 3 to severe regurgitation. Calculations On the left side, regurgitant stroke volume (SV, cm3 ) was calculated by the Doppler-echocardiographic method as the difference between mitral forward volume (VMv), determined by the Fisher method, and aortic stroke volume. On the right side, regurgitant stroke volume was calculated by the Doppler-echocardiographic method as the difference between tricuspid forward volume (VTV), determined by the tricuspid valve orifice method, and pulmonary stroke volume. Regurgitant fraction was calculated as SV/VMv 27 and SV/VTV, respectively.
Reproducibility of the Measurements Jet area method Interobserver variability. In the 83 patients studied, two observers, each blinded to the results obtained by the other, measured lOO nonselected regurgitant jet areas (50 mitral regurgitation and 50 tricuspid regurgitation). We calculated the interobserver variability as mean difference ± SD. Visual grading method Interobserver variability. In the 83 patients studied, two observers, each blinded to the r~sults obtained by the other, graded 31 nonselected studies (15 mitral regurgitation and 16 tricuspid regurgitation). We calculated interobserver variability with Spearman's rank correlation analysis. Statistics The calculated regurgitant fractions that were obtained with the Doppler echocardiographic method were compared with planimetered regurgitant jet area by means of linear regression analysis, and a correlation coefficient was calculated. Calculated regurgitant fractions obtained with the Doppler-echocardiographic method were also compared with visual grading with Spearman's rank correlation analysis. Visual grading was also rank correlated with planimetered regurgitant jet areas and dimensions (length, width, and height). 28
RESULTS In the group with mitral regurgitation, 15 had free jets and 28 had impinging jets; 15 were graded as mild, 20 as moderate, and eight as severe. In the group with tricuspid regurgitation, 16 had free jets and 24 impinging jets; 20 were graded as mild, 13 as moderate, and seven as severe regurgitation. Mean jet area in three planes divided by atrial area averaged 0.25 ± 0.11 in patients with mitral regurgitation (0.22 ± 0.13 in long-axis, 0.20 ± 0.12 in shortaxis, and 0.33 ± 0.11 in four-chamber views) and 0.25 ± 0.14 in patients with tricuspid regurgitation (0.20 ± 0.15 in right inflow, 0.23 ± 0.18 in shortaxis, and 0.31 ± 0.16 in four-chamber views). Mean mitral regurgitant fraction averaged 30% ± 13% (30% ± 16% in patients with free jets and 30% ± 11% in patients with impinging jets), and mean tricuspid regurgitant fraction averaged 33% ± 15% (30% ± 18% in patients with free jets and 34% ± 13% in patients with impinging jets). Comparing jet area with regurgitant fraction, we found that the best correlation was obtained with the mean of areas in three planes. For patients with mitral
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regurgitation, we found an overall correlation of r = 0.47 (r = 0.61 for free jets and r = 0.32 for impinging jets), whereas for tricuspid regurgitation we found r = 0.81 and r = 0.46 for free and impinging jets, respectively (overall r = 0.65). Rank correlating visual grading with regurgitant fraction, we found in mitral regurgitation p = 0.80 in patients with free jets and p = 0.74 in patients with impinging jets (overall p = 0.76) (Figure 1). In tricuspid regurgitation, p = 0.79 and 0.49, respectively (overall p = 0.62) (Figure 2). The planimetered regurgitant jet parameter that most influenced visual grading was the average area in three planes normalized to atrial area ( p = 0.80 in patients with mitral regurgitation and free jets; p = 0.51 in patients with impinging jets) (Figure 3). In tricuspid regurgitation we obtained p = 0.60 in free jets and p = 0.46 in impinging jets (Figure 4). Of the other dimensions studied (length, width, and height), the length in four chambers influenced the most ( p = 0.54 in free and p = 0.58 in impinging jets) in mitral regurgitation and (p = 0.50 and p = 0.50, respectively) tricuspid regurgitation. Mean atrial size was found not to influence the score ( p = - 0.16 and p = 0.04) (overall p = 0.04) in mitral regurgitation and (p = -0.01 and p = -0.06) (overall p =
- 0.001) tricuspid regurgitation, whereas it has some positive correlation with regurgitant fraction (r = 0.20 for the overall cohort of mitral regurgitation and r = 0.21 for tricuspid regurgitation). Jet Area Method Interobserver Variability
The interobserver variability for the jet area method was 3.45% ± 10.8%. Visual Grading Interobserver Variability
Of the 31 patients studied, the two observers disagree in two patients by one grade. The Spearman rank correlation wasp = 0.92. DISCUSSION
The accurate assessment of valvular regurgitation remains an important and imperfectly met goal of clinical and research cardiology. Because of its simplicity and ease of use, simple visual assessment of the calor Doppler defined regurgitant jet is currently the most common method in practice. Although studies have been done comparing regurgitant jet dimensions with angiographic grading2 •3 •5 ·6 and regurgitant flow 13 •29 in both tricuspid and mitral regurgitation,
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Journal of the American Society of Echocardiography Volume 7 Number 5
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critical examination of the accuracy of simple visual assessment has not been undertaken. In this study, we sought to define the accuracy of visual assessment of mitral and tricuspid regurgitation and the features of the jet that impacted the ·echocardiographers' grading. Results of the Study
Overall, we found that visual assessment of the regurgitant jet correlated well with regurgitant fraction calculated from quantitative Doppler echocardiographic means. Indeed, the rank correlation of the visual grade of mitral and tricuspid regurgitation was better than that obtained with any linear or area measurement of the regurgitant jet itself. In general, we found that visual grading had an accuracy rate similar to that of jet area measurements in patients with free jets, but in wall jets the visual grade proved a much more reliable estimate of regurgitant severity than jet area, particularly in mitral regurgitation. This likely reflects the echocardiographers recognition that wall jets frequently are smaller than free jets of the same regurgitant flow rate.13 In assessing the jet feature that most impacted the echocardiographers' visual grade, we noted that the
average jet area (normalized to left atrial area) from three views correlated best with the visual grade. Of the three views taken individually, it was the jet area from the apical four-chamber view that provided the highest correlation (Figure 5). This may reflect the fact that mitral and tricuspid regurgitant jets generally are directed away from the apex and thus appear largest from this vantage because of a more complete Doppler reconstruction of the jet morphology. For jets with similar areas, we estimated from a multilinear analysis of jet area, eccentricity, and grading that the original echocardiographic reader added approximately one fourth of a point to the mitral regurgitant grades and one eighth to the tricuspid regurgitant grades when a wall jet was observed. Limitations and Future Directions
A clear limitation of any clinical study evaluating regurgitation is the lack of an accurate gold standard against which to compare the results of different methods. In this study we chose to use the Dopplertwo-dimensional echocardiographic method as the gold standard because, even if it is limited because it relies on measurements of a single diameter in threedimensional structures and requires high-quality im-
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Figure 5 Clinical examples of free jet (left) and impinging jet (right) in patient with mitral regurgitation. Notice appearance of more severe regurgitation in patient on right even though regurgitant jet areas are similar.
ages, in experimental studies it has correlated closely with roller pump and electromagnetic flowmeter measurements of cardiac output and regurgitant volume. 18. 21 It is also widely recognized that standard angiographic grading is affected by many variables including catheter position, ventricular arrhythmias, volume and rate of injection of contrast medium, atrial chamber size, forward flow, and radiographic penetration. 22•23•30•31 A particular problem in the right side is that the catheter crossing the tricuspid anulus interferes with the valve motion, creating an iatrogenic incompetence and making the angiographic quantitation prone to error. 30•31 The Doppler echocardiographic method has previously been validated as an accurate quantitative standard, 18. 21 •24•25 and our measured correlation with regurgitant stroke volumes in normal control patients without regurgitation demonstrates its applicability in this study. Conclusions
Visual evaluation of mitral and tricuspid and regurgitant jets correlates well with quantitative measure
of valvular incompetence and is superior to simple measurement of jet dimensions. Integrating the additional information available from the two-dimensional echocardiographic images and jet morphology allows a more accurate assessment of the severity in mitral regurgitation even in the presence of distorted wall jets. In tricuspid regurgitation, visual assessment of impinging jets was not as accurate as that for free jets, perhaps indicating that a full appreciation of the jet distortion induced by wall impingement is not as well known on the right side of the heart as it is on the left side.
REFERENCES l. Omoto R, Yokote Y, Takamoto S, et al. The development of real time two-dimensional Doppler echocard.iography and its clinical significance in acquired valvular diseases: with special reference to the evaluation of valvular regurgitation. Jpn Heart J 1984;25 :325-40. 2. Miyatake K, Izumi S, Okarnoto M, et al. Semiquantitative grading of severity of mitral regurgitation by real-time two-
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dimensional Doppler flow imaging technique. J Am Coil Cardial 1986;7:82-8. 3. Helmcke F, Nanda NC, Hsuin MC, et al. Color Doppler assessment of mitral regurgitation with orthogonal planes. Circulation 1987;75:175-83. 4. Otsuji Y, Tei C, Kisanuki A, Natsugoe K, Kawazoe Y. Color Doppler echocardiographic assessment of the change in mitral regurgitant volume. Am Heart J 1987;114:349-54. 5. Spain MG, Smith MD, Graybum PA, Harlamert EA, DeMaria AN. Quantitative assessment of mitral regurgitation by Doppler color flow imaging: angiographic and hemodynamic correlations. JAm Coil Cardiol 1989;13:585-90. 6. Suzuki Y, Kambara H, Kadoka K, et al. Detection and evaluation of tricuspid regurgitation using a real-time, two-dimensional, color-coded, Doppler flow imaging system: comparison with contrast two-dimensional echocardiography and right ventriculography. Am J Cardiol 1986;57:811-5. 7. Thomas JD, Liu CM, FlachskampfFA, O'Shea JP, Davidoff R, Weyman AE. Quantification of jet flow by momentum analysis: an in vitro color Doppler flow study. Circulation 1990;81:247-59. 8. Cape EG, Yoganathan AP, Levine RA. A new method for noninvasive quantification of valvular regurgitation based on conservation of momentum: an in vitro validation. Circulation 1989;79:1343-53. 9. Yoganathan AP, Cape EG, Sung H-V, Williams FP, Jimoh A. Review of hydrodynamic principles for the cardiologist: applications to the study of blood flow and jets by imaging techniques. JAm Coil Cardiol1988;12:1344-53. 10. Simpson lA, Valdes-Cruz LM, Sahn DJ, Murillo A, Tamura T, Chung KY. Doppler color flow mapping of simulated in vitro regurgitant jets: evaluation of the effects of orifice size and hemodynamic variables. J Am Coil Cardiol 1989; 13:1195-207. 11. Thomas JD, DavidoffR, Wilkins GT, Choong CY, Svizzero T, Weyman AE. The volume of a color flow jet varies directly with flow rate and inversely with orifice size: a hydrodynamic in vitro assessment [Abstract]. J Am Coil Cardiol 1988;11(suppl): 19A. 12. Cape EG, Yoganathan AP, Weyman AE, Levine RA. Adjacent solid boundaries alter the size of regurgitant jets on Doppler color flow maps. J Am Coil Cardiol1991; 17: 1094102. 13. Chen C, Thomas JD, Anconina J, et al. Impact of impinging wall jet on color Doppler quantification of mitral regurgitation. Circulation 1991;84:712-20. 14. Rivera JM, V andervoort PM, Mele D, V azquez de Prada JA, Weyman AE, Thomas JD. Which physical factors determine mitral regurgitation jet area in the clinical setting? [Abstract]. JAm Coil Cardiol1993;21:144A. 15. Sahn DJ. Instrumentation and physical factors related to visualization of stenotic and regurgitant jets by Doppler color flow mapping. JAm Coil Cardiol1988;12:1354-65. 16. Mohr-Kahaly S, Lotter R, Brennecke R. Influence of color Doppler instrument set-up on the minimal encoded velocity: an in vitro study [Abstract]. Circulation 1988;78(suppl):II12.
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17. Stevenson JG. Two-dimensional color-Doppler estimation of the severity of atrioventricular valve regurgitation: important effects of instrument gain setting, pulse repetition frequency, and carrier frequency. JAM Sac ECHOCARDIOGR 1989;2:110. 18. Meijboom EJ, Horowitz S, Valdes-Cruz L, Sahn D, Larson DF, Oliveira C. A Doppler echocardiographic method for calculating volume flow across the tricuspid valve: correlative laboratory and clinical studies. Circulation 1985;71:551-6. 19. Meijboom EJ, Valdes-Cruz LM, Horowitz S, et al. A twodimensional Doppler echocardiographic method for calculation of pulmonary and systemic blood flow in a canine model with a variable-sized left-to-right extracardiac shunt. Circulation 1983;68:437-45. 20. V aldes-Cruz LM, Horowitz S, Mesel E, et al. A pulsed Doppler-echocardiographic method for calculation of pulmonary and systemic flow: accuracy in a canine model with ventricular septal defect. Circulation 1983;68:597-602. 21. Valdes-Cruz LM, Horowitz S, Mesel E, Sahn DJ, Fisher DC, Larson D. A pulsed Doppler-echocardiographic method for calculating pulmonary and systemic blood flow in atrial level shunts: validation studies in animals and initial human experience. Circulation 1984;69:80-6. 22. Lingarnneni R, Cha SD, Maranhao V, Gooch AS, Goldberg H. Tricuspid regurgitation: clinical and angiographic assessment. Cathet Cardiovasc Diagn 1979;5:7-14. 23. Hansing CE, Rowe GG. Tricuspid insufficiency: a study of hemodynamics and pathogenesis. Circulation 1972;45: 793-9. 24. Fischer DC, Sahn DJ, Freidman MJ, et al. The mitral valve orifice method for non-invasive two-dimensional Doppler determination of cardiac output. Circulation 1983;67:872-7. 25. Dittman H, Voelker W, Karsch K, Seipel L. Influence of sampling site and flow area on cardiac output measurements by Doppler echocardiography. J Am Coil Cardiol 1987;10:818-23. 26. Ascah KJ, Stewart WJ, Jiang L, et al. A Doppler-two-dimensional echocardiographic method for quantification of mitral regurgitation. Circulation 1985;72:377-83. 27. Rokey R, Sterling LL, Zoghbi W. Determination of the regurgitant fraction in isolated mitral or aortic regurgitation by pulsed Doppler two-dimensional echocardiography. J Am Coil Cardiol 1986;7:1273-8. 28. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1:307-10. 29. Mugge A, Daniel W, Herrmann G, Simon R, Lichtlen P. Quantification of tricuspid regurgitation by Doppler color flow mapping after cardiac transplantation. Am J Cardiol 1990;66:884-7. 30. Cairns KB, Kloster FE, Bristow JD, Lees MH, Griswold HE. Problems in the hemodynamic diagnosis of tricuspid insufficiency. Am Heart J 1968;75:173-9. 31. Stewart D, Leman R, Kaiser J, Mann D. Catheter-induced tricuspid regurgitation: incidence and clinical significance. Chest 1991;99:651-5.
To investigate which factors influence visual evaluation and how accurate it is in patients with valvular insufficiency, 83 patients were studied. All were in sinus rhytlun, 43 with mitral and 40 with tricuspid regurgitation. Categoric visual grading (mild, moderate, and severe) was compared with jet area method and regurgitant fraction and the factors that influenced the assigned rank were identified. With jet area method (mean of areas in three planes), the correlation with regurgitant fraction was r = 0.61 for free jets and r = 0.32 for wall jets (overall r = 0.47) in patients with mitral regurgitation, and r = 0.81 and r = 0.46 for free and wall jets, respectively, in patients with tricuspid regurgitation (overall, r = 0.65). With visual grading, the correlation was for free and wall jets, respectively, p = 0.80 and p = 0.74 (overall p = 0.76) in patients with mitral regurgitation, and p = 0.79 and p = 0.49 for free and wall jets, respectively (overall p = 0.62), in patients with tricuspid regurgitation. The jet area parameter found to have the most influence on visual grading was the average area in three planes divided by atrial area, with p = 0.80 and p = 0.51 in patients with mitral regurgitation (free and impinging jets respectively) and p = 0.60 and p = 0.46 in tricuspid regurgitation. We conclude that visual grading of valvular regurgitant jets correlates well with quantitative measures of valvular incompetence and better than any simple jet area method. Integrating additional information available from two-dimensional and Doppler images allows an accurate assessment of distorted wall jets in mitral regurgitation, but in tricuspid regurgitation the visual evaluation of impinging jets is less accurate. (J AM Soc EcHOCARDIOGR 1994; 7:480-7.)
N onvasive assessment of valvular insufficiency has improved substantially in recent years. The regurgitant jet Doppler color-flow mapping provides an easy, semiquantitative estimation of the severity of the lesion. 1•2 It is now well established that displayed regurgitant jet dimensions are influenced by physical factors other than the regurgitant flow, 3- 14 including constraining effects of the receiving chamber12•13 and
From the Department of Cardiology, Cleveland Clinic Foundation, and the Noninvasive Cardiac Laboratory, Massachusetts General Hospital. 'Supported in part by a Fondo de Investigaciones Sanitarias, Madrid, Spain. bSupported in part by the Bayer Fund for Cardiovascular Research, New York, New York. Reprint requests: J. M. Rivera, MD, c "- Periodista Badia ll, pt 1, Valencia 46010, Spain. Copyright© 1994 by the American Society ofEchocardiography. 0894-7317/94$3.00 + 0 27/1/55191
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instrumentation factors such as wall filter, gain, pulse repetition frequency, and transducer frequency. 15- 17 However, simple visual assessment of the regurgitant jet has become the most common approach to evaluate valvular insufficiency in clinical practice. With this method, the echocardiographer not only appreciates the regurgitant jet dimensions but also integrates information on jet dynamics and chamber geometry toward an educated semiquantitative assessment, which is of particular importance for the appraisal of eccentrically directed wall jets. To determine the factors that impact the echocardiographer in grading valvular regurgitation and to assess the accuracy of simple visual assessment, we studied 83 patients, 43 with mitral regurgitation and 40 with tricuspid regurgitation. To test the accuracy of both jet area and visual methods, regurgitant fraction was calculated from quantitative Doppler-echocardiographic measurements. Jet area parameters and visual grade were also correlated with each other to find
Journal of the American Society of Echocardiography Volume 7 Number 5
which jet area parameter most influences visual evaluation. MEmODS
Clinical Study Patient population. Patients were studied by one research technician and screened for the following selection criteria: ( 1) presence of mitral or tricuspid regurgitation in the color Doppler display and (2) availability of high-quality two-dimensional images and Doppler tracings to allow for accurate mitral, aortic, tricuspid, and pulmonary flow calculations by the Doppler I two-dimensional echocardiographic method. Patients with mitral or tricuspid stenosis, accompanying pulmonary or aortic valve disease, or intracardiac shunt flow were excluded. Eighty-three patients met the criteria for the study, 50 females and 33 males, with a mean age of 65 ± 17 years (age range 14 to 95 years). All83 patients were in sinus rhythm at the time of the study. The underlying cardiac diseases included ischemic heart disease in 45 patients, mitral valve prolapse in eight patients, mitral rheumatic heart disease in 17 patients, pericardial effusion in four patients, dilated cardiomyopathy in one patient, and absence of detectable morphologic lesions in eight patients. Echocardiographic data. All two-dimensional, pulsed, and Doppler color-flow data were obtained as part of the routine echocardiographic evaluation. Commercially available echo-Doppler machines (model 77020A or Sonos 1000; Hewlett-Packard Corp., Andover, Mass.) equipped with a standard 2.5 MHz transducer were used for the study. All images and spectral flow profiles were recorded on 1/2-inch videotape for off-line analysis. Color Doppler images for analysis of mitral regurgitation were obtained in apical four-chamber, parasternal short-axis, and parasternal long-axis views. For analysis of tricuspid regurgitation, images were obtained in apical four-chamber, parasternal right inflow, and parasternal short-axis views at pulse repetition frequencies of 3.9 to 4.8 kHz. The typical Nyquist velocity was 58 cm/ sec at a scanning depth of 16 cm. Doppler settings were kept constant during the examinations. Each color Doppler examination was performed with the narrowest sector angle possible (30 degrees) to maximize the color-flow imaging frame rate (15 to 17Hz). Data Analysis
All M-mode tracings, two-dimensional images, Doppler spectra, and color Doppler images were an-
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alyzed off-line with a computer analysis system (Sony SUM 1010). All measurements were averaged over three cardiac cycles. Right ventricular Doppler-two-dimensional echocardiographic method. Our overall approach to the pulsed Doppler quantification of tricuspid regurgitation has been detailed previously. According to the method of Meijboom et al. 18•19 and ValdesCruz et al., 20•21 we obtained tricuspid forward flow as the product of diastolic tricuspid orifice area, tricuspid inflow time-velocity integral, and heart rate. Pulmonary forward flow was obtained by multiplying systolic pulmonary annular area, pulmonic annular time-velocity integral, and heart rate. In the absence of pulmonic regurgitation or abnormal shunt flow, the tricuspid regurgitant flow is determined by the difference between tricuspid inflow and pulmonic outflow. 22•23 Validation. To validate this procedure in our laboratory, tricuspid stroke volume was calculated according to the previously described Doppler method in 14 patients without tricuspid or pulmonary regurgitation and compared with simultaneously acquired thermodilution data for stroke volumes ranging from 41.5 to 125 cm3 (71.8 ± 21.4 cm3 ); the difference (thermodilution minus tricuspid) in stroke volume was -3.4 ± 8.9 cm3 with an overall correlation of r = 0. 93. In another group of 13 patients without tricuspid or pulmonary regurgitation, tricuspid and pulmonary stroke volume were calculated. The difference (tricuspid minus pulmonary) in stroke volume for the two methods was found to be - 0.5 ± 3.29 cm3 with an overall correlation of r = 0.95. Left ventricular Doppler-two-dimensional echocardiographic method. Our overall approach to pulsed Doppler quantification of mitral regurgitation has recently been described in detail. 13 With the method of Fischer et al., 24 we obtained mitral forward flow as the product of mean diastolic mitral orifice area, mitral inflow time-velocity integral, and heart rate. Aortic forward flow was obtained by multiplying systolic aortic annular area, aortic annular time-velocity integral, and heart rate. 25 In the absence of aortic regurgitation or abnormal shunt flow, the mitral regurgitant flow is determined by the difference between mitral inflow and aortic outflow. 23 •26 Validation. To validate this procedure in our laboratory, mitral stroke volume was calculated according to the previously described Doppler method in 14 patients without mitral or aortic regurgitation and compared with simultaneously acquired thermodilution data. For stroke volumes ranging from 43 to
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482 Rivera et al.
131 cm3 (75.3 ± 27 cm3 ), the difference (thermodilution minus mitral; mean ± SD) in stroke volume was 2.0 ± 8.3 cm3 with an overall correlation of r = 0.96. In another group of 36 patients without mitral or aortic regurgitation, mitral and aortic stroke volume were calculated. The difference (mitral minus aortic) in stroke volume for the two methods was found to be 1. 7 ± 3.4 cm3 with an overall correlation ofr = 0.97. Jet area method. For jet areas, an optimal gain setting was obtained by maximizing the gain level without introducing signals in the nonflow areas. Videotape recordings of images were scanned frame by frame to find the largest regurgitant jet area. The contour of the maximal jet area was then traced with a light pen and measured by computerized planimetry. The traced jet area included the centrally aliased and peripherally nonaliased signals. 2•3 When it was possible, atrial area was measured by computerized planimetry in the same frame in which the maximal jet area was seen. Otherwise, a representative frame from the same view was analyzed during the same portion of systole. We also measured linear dimensions of the color-Doppler jet (length, width, and height), as well as its proximal width at the regurgitant orifice. Jets were classified into two types: free jets, in which the full regurgitant jet was contained within the cavity of the atrium in the three standard imaging planes (parasternal right ventricular inflow, apical four-chamber, and parasternal short-axis views for tricuspid regurgitation and parasternal long and short-axis and apical four-chamber axis views for mitral regurgitation), and wall jets, which struck the inferior, anterior, lateral, or septal lateral wall in one or more views. Jets that were constrained by the superior atrial wall alone were classified as free jets. 13 Visual grading method. As a part of clinical routine in the laboratory, regurgitation was graded as mild, moderate, and severe. 2 •3 For purposes of analysis, we assigned tht value 1 to mild, 2 to moderate, and 3 to severe regurgitation. Calculations On the left side, regurgitant stroke volume (SV, cm3 ) was calculated by the Doppler-echocardiographic method as the difference between mitral forward volume (VMv), determined by the Fisher method, and aortic stroke volume. On the right side, regurgitant stroke volume was calculated by the Doppler-echocardiographic method as the difference between tricuspid forward volume (VTV), determined by the tricuspid valve orifice method, and pulmonary stroke volume. Regurgitant fraction was calculated as SV/VMv 27 and SV/VTV, respectively.
Reproducibility of the Measurements Jet area method Interobserver variability. In the 83 patients studied, two observers, each blinded to the results obtained by the other, measured lOO nonselected regurgitant jet areas (50 mitral regurgitation and 50 tricuspid regurgitation). We calculated the interobserver variability as mean difference ± SD. Visual grading method Interobserver variability. In the 83 patients studied, two observers, each blinded to the r~sults obtained by the other, graded 31 nonselected studies (15 mitral regurgitation and 16 tricuspid regurgitation). We calculated interobserver variability with Spearman's rank correlation analysis. Statistics The calculated regurgitant fractions that were obtained with the Doppler echocardiographic method were compared with planimetered regurgitant jet area by means of linear regression analysis, and a correlation coefficient was calculated. Calculated regurgitant fractions obtained with the Doppler-echocardiographic method were also compared with visual grading with Spearman's rank correlation analysis. Visual grading was also rank correlated with planimetered regurgitant jet areas and dimensions (length, width, and height). 28
RESULTS In the group with mitral regurgitation, 15 had free jets and 28 had impinging jets; 15 were graded as mild, 20 as moderate, and eight as severe. In the group with tricuspid regurgitation, 16 had free jets and 24 impinging jets; 20 were graded as mild, 13 as moderate, and seven as severe regurgitation. Mean jet area in three planes divided by atrial area averaged 0.25 ± 0.11 in patients with mitral regurgitation (0.22 ± 0.13 in long-axis, 0.20 ± 0.12 in shortaxis, and 0.33 ± 0.11 in four-chamber views) and 0.25 ± 0.14 in patients with tricuspid regurgitation (0.20 ± 0.15 in right inflow, 0.23 ± 0.18 in shortaxis, and 0.31 ± 0.16 in four-chamber views). Mean mitral regurgitant fraction averaged 30% ± 13% (30% ± 16% in patients with free jets and 30% ± 11% in patients with impinging jets), and mean tricuspid regurgitant fraction averaged 33% ± 15% (30% ± 18% in patients with free jets and 34% ± 13% in patients with impinging jets). Comparing jet area with regurgitant fraction, we found that the best correlation was obtained with the mean of areas in three planes. For patients with mitral
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Rivera et al. 483
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regurgitation, we found an overall correlation of r = 0.47 (r = 0.61 for free jets and r = 0.32 for impinging jets), whereas for tricuspid regurgitation we found r = 0.81 and r = 0.46 for free and impinging jets, respectively (overall r = 0.65). Rank correlating visual grading with regurgitant fraction, we found in mitral regurgitation p = 0.80 in patients with free jets and p = 0.74 in patients with impinging jets (overall p = 0.76) (Figure 1). In tricuspid regurgitation, p = 0.79 and 0.49, respectively (overall p = 0.62) (Figure 2). The planimetered regurgitant jet parameter that most influenced visual grading was the average area in three planes normalized to atrial area ( p = 0.80 in patients with mitral regurgitation and free jets; p = 0.51 in patients with impinging jets) (Figure 3). In tricuspid regurgitation we obtained p = 0.60 in free jets and p = 0.46 in impinging jets (Figure 4). Of the other dimensions studied (length, width, and height), the length in four chambers influenced the most ( p = 0.54 in free and p = 0.58 in impinging jets) in mitral regurgitation and (p = 0.50 and p = 0.50, respectively) tricuspid regurgitation. Mean atrial size was found not to influence the score ( p = - 0.16 and p = 0.04) (overall p = 0.04) in mitral regurgitation and (p = -0.01 and p = -0.06) (overall p =
- 0.001) tricuspid regurgitation, whereas it has some positive correlation with regurgitant fraction (r = 0.20 for the overall cohort of mitral regurgitation and r = 0.21 for tricuspid regurgitation). Jet Area Method Interobserver Variability
The interobserver variability for the jet area method was 3.45% ± 10.8%. Visual Grading Interobserver Variability
Of the 31 patients studied, the two observers disagree in two patients by one grade. The Spearman rank correlation wasp = 0.92. DISCUSSION
The accurate assessment of valvular regurgitation remains an important and imperfectly met goal of clinical and research cardiology. Because of its simplicity and ease of use, simple visual assessment of the calor Doppler defined regurgitant jet is currently the most common method in practice. Although studies have been done comparing regurgitant jet dimensions with angiographic grading2 •3 •5 ·6 and regurgitant flow 13 •29 in both tricuspid and mitral regurgitation,
484
Journal of the American Society of Echocardiography September-Ocrober 1994
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Journal of the American Society of Echocardiography Volume 7 Number 5
Rivera et al. 485
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critical examination of the accuracy of simple visual assessment has not been undertaken. In this study, we sought to define the accuracy of visual assessment of mitral and tricuspid regurgitation and the features of the jet that impacted the ·echocardiographers' grading. Results of the Study
Overall, we found that visual assessment of the regurgitant jet correlated well with regurgitant fraction calculated from quantitative Doppler echocardiographic means. Indeed, the rank correlation of the visual grade of mitral and tricuspid regurgitation was better than that obtained with any linear or area measurement of the regurgitant jet itself. In general, we found that visual grading had an accuracy rate similar to that of jet area measurements in patients with free jets, but in wall jets the visual grade proved a much more reliable estimate of regurgitant severity than jet area, particularly in mitral regurgitation. This likely reflects the echocardiographers recognition that wall jets frequently are smaller than free jets of the same regurgitant flow rate.13 In assessing the jet feature that most impacted the echocardiographers' visual grade, we noted that the
average jet area (normalized to left atrial area) from three views correlated best with the visual grade. Of the three views taken individually, it was the jet area from the apical four-chamber view that provided the highest correlation (Figure 5). This may reflect the fact that mitral and tricuspid regurgitant jets generally are directed away from the apex and thus appear largest from this vantage because of a more complete Doppler reconstruction of the jet morphology. For jets with similar areas, we estimated from a multilinear analysis of jet area, eccentricity, and grading that the original echocardiographic reader added approximately one fourth of a point to the mitral regurgitant grades and one eighth to the tricuspid regurgitant grades when a wall jet was observed. Limitations and Future Directions
A clear limitation of any clinical study evaluating regurgitation is the lack of an accurate gold standard against which to compare the results of different methods. In this study we chose to use the Dopplertwo-dimensional echocardiographic method as the gold standard because, even if it is limited because it relies on measurements of a single diameter in threedimensional structures and requires high-quality im-
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Journal of the American Society of Echocardiography September-October 1994
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Figure 5 Clinical examples of free jet (left) and impinging jet (right) in patient with mitral regurgitation. Notice appearance of more severe regurgitation in patient on right even though regurgitant jet areas are similar.
ages, in experimental studies it has correlated closely with roller pump and electromagnetic flowmeter measurements of cardiac output and regurgitant volume. 18. 21 It is also widely recognized that standard angiographic grading is affected by many variables including catheter position, ventricular arrhythmias, volume and rate of injection of contrast medium, atrial chamber size, forward flow, and radiographic penetration. 22•23•30•31 A particular problem in the right side is that the catheter crossing the tricuspid anulus interferes with the valve motion, creating an iatrogenic incompetence and making the angiographic quantitation prone to error. 30•31 The Doppler echocardiographic method has previously been validated as an accurate quantitative standard, 18. 21 •24•25 and our measured correlation with regurgitant stroke volumes in normal control patients without regurgitation demonstrates its applicability in this study. Conclusions
Visual evaluation of mitral and tricuspid and regurgitant jets correlates well with quantitative measure
of valvular incompetence and is superior to simple measurement of jet dimensions. Integrating the additional information available from the two-dimensional echocardiographic images and jet morphology allows a more accurate assessment of the severity in mitral regurgitation even in the presence of distorted wall jets. In tricuspid regurgitation, visual assessment of impinging jets was not as accurate as that for free jets, perhaps indicating that a full appreciation of the jet distortion induced by wall impingement is not as well known on the right side of the heart as it is on the left side.
REFERENCES l. Omoto R, Yokote Y, Takamoto S, et al. The development of real time two-dimensional Doppler echocard.iography and its clinical significance in acquired valvular diseases: with special reference to the evaluation of valvular regurgitation. Jpn Heart J 1984;25 :325-40. 2. Miyatake K, Izumi S, Okarnoto M, et al. Semiquantitative grading of severity of mitral regurgitation by real-time two-
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dimensional Doppler flow imaging technique. J Am Coil Cardial 1986;7:82-8. 3. Helmcke F, Nanda NC, Hsuin MC, et al. Color Doppler assessment of mitral regurgitation with orthogonal planes. Circulation 1987;75:175-83. 4. Otsuji Y, Tei C, Kisanuki A, Natsugoe K, Kawazoe Y. Color Doppler echocardiographic assessment of the change in mitral regurgitant volume. Am Heart J 1987;114:349-54. 5. Spain MG, Smith MD, Graybum PA, Harlamert EA, DeMaria AN. Quantitative assessment of mitral regurgitation by Doppler color flow imaging: angiographic and hemodynamic correlations. JAm Coil Cardiol 1989;13:585-90. 6. Suzuki Y, Kambara H, Kadoka K, et al. Detection and evaluation of tricuspid regurgitation using a real-time, two-dimensional, color-coded, Doppler flow imaging system: comparison with contrast two-dimensional echocardiography and right ventriculography. Am J Cardiol 1986;57:811-5. 7. Thomas JD, Liu CM, FlachskampfFA, O'Shea JP, Davidoff R, Weyman AE. Quantification of jet flow by momentum analysis: an in vitro color Doppler flow study. Circulation 1990;81:247-59. 8. Cape EG, Yoganathan AP, Levine RA. A new method for noninvasive quantification of valvular regurgitation based on conservation of momentum: an in vitro validation. Circulation 1989;79:1343-53. 9. Yoganathan AP, Cape EG, Sung H-V, Williams FP, Jimoh A. Review of hydrodynamic principles for the cardiologist: applications to the study of blood flow and jets by imaging techniques. JAm Coil Cardiol1988;12:1344-53. 10. Simpson lA, Valdes-Cruz LM, Sahn DJ, Murillo A, Tamura T, Chung KY. Doppler color flow mapping of simulated in vitro regurgitant jets: evaluation of the effects of orifice size and hemodynamic variables. J Am Coil Cardiol 1989; 13:1195-207. 11. Thomas JD, DavidoffR, Wilkins GT, Choong CY, Svizzero T, Weyman AE. The volume of a color flow jet varies directly with flow rate and inversely with orifice size: a hydrodynamic in vitro assessment [Abstract]. J Am Coil Cardiol 1988;11(suppl): 19A. 12. Cape EG, Yoganathan AP, Weyman AE, Levine RA. Adjacent solid boundaries alter the size of regurgitant jets on Doppler color flow maps. J Am Coil Cardiol1991; 17: 1094102. 13. Chen C, Thomas JD, Anconina J, et al. Impact of impinging wall jet on color Doppler quantification of mitral regurgitation. Circulation 1991;84:712-20. 14. Rivera JM, V andervoort PM, Mele D, V azquez de Prada JA, Weyman AE, Thomas JD. Which physical factors determine mitral regurgitation jet area in the clinical setting? [Abstract]. JAm Coil Cardiol1993;21:144A. 15. Sahn DJ. Instrumentation and physical factors related to visualization of stenotic and regurgitant jets by Doppler color flow mapping. JAm Coil Cardiol1988;12:1354-65. 16. Mohr-Kahaly S, Lotter R, Brennecke R. Influence of color Doppler instrument set-up on the minimal encoded velocity: an in vitro study [Abstract]. Circulation 1988;78(suppl):II12.
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17. Stevenson JG. Two-dimensional color-Doppler estimation of the severity of atrioventricular valve regurgitation: important effects of instrument gain setting, pulse repetition frequency, and carrier frequency. JAM Sac ECHOCARDIOGR 1989;2:110. 18. Meijboom EJ, Horowitz S, Valdes-Cruz L, Sahn D, Larson DF, Oliveira C. A Doppler echocardiographic method for calculating volume flow across the tricuspid valve: correlative laboratory and clinical studies. Circulation 1985;71:551-6. 19. Meijboom EJ, Valdes-Cruz LM, Horowitz S, et al. A twodimensional Doppler echocardiographic method for calculation of pulmonary and systemic blood flow in a canine model with a variable-sized left-to-right extracardiac shunt. Circulation 1983;68:437-45. 20. V aldes-Cruz LM, Horowitz S, Mesel E, et al. A pulsed Doppler-echocardiographic method for calculation of pulmonary and systemic flow: accuracy in a canine model with ventricular septal defect. Circulation 1983;68:597-602. 21. Valdes-Cruz LM, Horowitz S, Mesel E, Sahn DJ, Fisher DC, Larson D. A pulsed Doppler-echocardiographic method for calculating pulmonary and systemic blood flow in atrial level shunts: validation studies in animals and initial human experience. Circulation 1984;69:80-6. 22. Lingarnneni R, Cha SD, Maranhao V, Gooch AS, Goldberg H. Tricuspid regurgitation: clinical and angiographic assessment. Cathet Cardiovasc Diagn 1979;5:7-14. 23. Hansing CE, Rowe GG. Tricuspid insufficiency: a study of hemodynamics and pathogenesis. Circulation 1972;45: 793-9. 24. Fischer DC, Sahn DJ, Freidman MJ, et al. The mitral valve orifice method for non-invasive two-dimensional Doppler determination of cardiac output. Circulation 1983;67:872-7. 25. Dittman H, Voelker W, Karsch K, Seipel L. Influence of sampling site and flow area on cardiac output measurements by Doppler echocardiography. J Am Coil Cardiol 1987;10:818-23. 26. Ascah KJ, Stewart WJ, Jiang L, et al. A Doppler-two-dimensional echocardiographic method for quantification of mitral regurgitation. Circulation 1985;72:377-83. 27. Rokey R, Sterling LL, Zoghbi W. Determination of the regurgitant fraction in isolated mitral or aortic regurgitation by pulsed Doppler two-dimensional echocardiography. J Am Coil Cardiol 1986;7:1273-8. 28. Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986;1:307-10. 29. Mugge A, Daniel W, Herrmann G, Simon R, Lichtlen P. Quantification of tricuspid regurgitation by Doppler color flow mapping after cardiac transplantation. Am J Cardiol 1990;66:884-7. 30. Cairns KB, Kloster FE, Bristow JD, Lees MH, Griswold HE. Problems in the hemodynamic diagnosis of tricuspid insufficiency. Am Heart J 1968;75:173-9. 31. Stewart D, Leman R, Kaiser J, Mann D. Catheter-induced tricuspid regurgitation: incidence and clinical significance. Chest 1991;99:651-5.