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Circulation. 1995;91:746-754

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(Circulation. 1995;91:746-754.)
© 1995 American Heart Association, Inc.

Articles

Proximal Jet Size by Doppler Color Flow Mapping Predicts Severityof Mitral Regurgitation

Clinical Studies

Donato Mele, MD; Pieter Vandervoort, MD; Igor Palacios, MD; J. Miguel Rivera, MD; Robert E. Dinsmore, MD; Ehud Schwammenthal, MD; Jane E. Marshall, BS; Arthur E. Weyman, MD; Robert A. Levine, MD

From the Noninvasive (D.M., P.V., J.M.R., E.S., J.E.M., A.E.W., R.A.L.) and Invasive (I.P., R.E.D.) Cardiac Laboratories, Massachusetts General Hospital and Harvard Medical School, Boston, Mass.


*    Abstract
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 *Abstract
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Background Recent studies have shown that many instrument and physiological factors limit the ability of color Doppler total jet area within the receiving chamber to predict the severity of valvular regurgitation. In contrast, the proximal or initial dimensions of the jet as it emerges from the orifice have been shown to increase directly with orifice size and to correlate well with the severity of aortic insufficiency. Only limited data, however, are available regarding the value of proximal jet size in mitral regurgitation, and it has not been examined in short-axis or transthoracic views. The purpose of the present study, therefore, was to evaluate the relation between proximal jet size and other measures of the severity of mitral regurgitation.

Methods and Results In 49 patients, the anteroposterior height of the proximal jet as it emerges from the mitral valve was measured in the parasternal long-axis view; proximal jet width and area were measured in the short-axis view at the same level. Results were compared with regurgitant volume and fraction by pulsed Doppler subtraction of aortic and mitral flows in 47 patients without more than trace aortic insufficiency; with angiographic grade determined within 24 hours in 33 catheterized patients; and with angiographic regurgitant fraction in 13 patients who were in normal sinus rhythm and had no significant aortic and tricuspid insufficiency. Proximal jet height, width, and area correlated well with Doppler regurgitant volume and fraction (r=.86 to .95; SEE=7.7 to 9.0 mL; 5.9% to 7.3%). Proximal jet size could also be used to distinguish angiographic grades of mitral regurgitation with minimal overlap (P<.0001) and correlated well with angiographic regurgitant fraction (r=.85 to .91; SEE=4.1% to 5.1%).

Conclusions Proximal jet size correlates well with established measures of the severity of mitral regurgitation. It is conveniently available with transthoracic clinical scanning and should be useful in the routine evaluation of patients with mitral regurgitation.


Key Words: echocardiography • regurgitation • mitral valve • mapping


*    Introduction
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 *Introduction
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down arrowDiscussion
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Noninvasive assessment of the presence and severity of mitral regurgitation is important for clinical decision making.1 2 3 4 Recent studies have shown that jet area imaged by Doppler color flow mapping within the receiving chamber5 6 is limited in its ability to predict severity because jet area varies with driving pressure, jet interactions with the receiving chamber, and instrument settings.3 4 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 In contrast, the proximal or initial size of the jet as it emerges from the orifice has been shown to increase directly with the size of the regurgitant orifice.27 28 29 30 31 This relation is relatively independent of driving pressure and flow rate in the clinical range.27 28 30 31 Proximal jet size has also been shown, both clinically and experimentally, to be useful in assessing the severity of aortic insufficiency.7 28 32 33 Clinical observations have suggested that the size of proximal mitral regurgitant jets could also be assessed in two-dimensional views. To date, however, this has not been examined by transthoracic echocardiography, the approach used in the vast majority of patients studied by cardiac ultrasound. It has only recently been explored by monoplane transesophageal imaging, looking at a single dimension of the proximal jet, which showed good correlation with angiography but with substantial overlap between grades34 ; this may reflect the variable relation between a single dimension and the actual orifice area in two dimensions29 30 35 as well as the use of a maximal dimension as opposed to a dimension in a single standard view.34 Furthermore, as recent studies have shown, transthoracic and transesophageal techniques may show jet images of different sizes in comparable views.36 37 The purpose of the present study, therefore, was to evaluate the relation between proximal jet size by transthoracic echocardiography (including both linear dimensions and area) and other independent angiographic and Doppler echocardiographic measures of the severity of mitral regurgitation.


*    Methods
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 *Methods
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Patient Population
We prospectively evaluated 49 patients selected to have at least mild mitral regurgitation whose echocardiograms had image quality suitable for measurement of the proximal regurgitant jet for quantitative comparison with independent measures. Of these patients, 33 were selected as a consecutive group in whom echocardiography was performed within 24 hours of angiography and the above criteria were satisfied. Another 16 consecutive patients studied only noninvasively were added to the study at the end of the angiographic collection. Patients with aortic or mitral valve prostheses were excluded. A total of 47 studies were suitable for pulsed Doppler quantification of mitral regurgitant flow by subtraction of integrated mitral inflow and aortic outflow, in the absence of more than trace aortic insufficiency.23 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 There were 17 men and 32 women with a mean age of 57±16 years (range, 31 to 80 years). Twenty-two patients were in atrial fibrillation. The etiology of mitral regurgitation included ischemic heart disease, rheumatic disease, dilated cardiomyopathy, and mitral valve prolapse with flail leaflet.

Echocardiography
Two-dimensional echocardiography, Doppler ultrasound, and color flow mapping were performed with the patients in the left lateral decubitus position using Hewlett-Packard 77020A and Sonos 1000 phased-array sector scanners at 2.5 to 3.5 MHz with a standard velocity map. A Nyquist velocity of 58 cm/s was used at a scanning depth of 16 cm at 2.5 MHz (39 cm/s at 3.5 MHz). Color Doppler studies were performed with the narrowest sector angle (30 degrees) to maximize the color flow imaging frame rate (15 to 17 Hz). Color gain was adjusted to eliminate random color in areas without flow.

The anteroposterior height of the proximal jet as it emerges from the orifice was evaluated at its peak systolic extent in the parasternal long-axis view (Fig 1Down). The plane of view was scanned side-to-side to maximize the view of proximal jet; then, in this maximal view, the narrowest height along the direction of flow was taken to measure the jet as it emerges between the leaflets. Turning the color display off and on was helpful in some instances to clarify the location of the leaflets and the emerging jet, although the leaflet structures generally did not provide a directly visualized and complete orifice in individual two-dimensional views. Transducer position was then adjusted so that the scan plane would traverse the jet along this narrowest proximal dimension in a short-axis or cross-sectional orientation. The transducer was tilted to image the smallest cross-sectional area of the jet as it emerges between the leaflets. Proximal jet width and area were measured at their peak systolic extent in this view (Fig 2Down). Imaging required less than 5 minutes (generally 2 to 3 minutes) per patient. Measurements were made off-line using a Sony SUM 1010 analysis system by an observer unaware of the clinical conditions or the results of angiography. They were averaged over 5 beats in sinus rhythm and over 6 to 10 beats in atrial fibrillation. If more than one jet origin was seen (two patients), jet dimensions were added.



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  		Figure 1. Parasternal long-axis color Doppler echocardiographic view of a patient with mitral regurgitation (left) showing measurement of proximal jet height (right, arrows) as it emerges from the mitral leaflets into the left atrium (right of image).



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  		Figure 2. Parasternal short-axis color Doppler echocardiographic scan through the narrowest proximal jet of mitral regurgitation (right) showing measurement of proximal jet area (dashes around proximal jet on right) and width (widest side-to-side dimension of traced area).

Doppler Studies
Mitral regurgitant stroke volume was calculated as the difference between mitral and aortic forward stroke volume integrated by pulsed Doppler23 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 ; regurgitant fraction was calculated as mitral regurgitant stroke volume divided by mitral forward stroke volume. Stroke volume across the aortic valve was calculated by multiplying the cross-sectional area at the level of the aortic annulus by the time-velocity integral of flow across that valve. Area was calculated from the peak diameter at the insertion of the aortic leaflets in the parasternal long-axis view, assuming a circular configuration.45 46 47 48 49 50 Outflow velocities were obtained by pulsed Doppler echocardiography from the apex with the sample volume at the level of the measured diameter and scanned radially for optimal alignment with flow. The time-velocity integral was calculated by tracing the modal velocity (darkest portion of the velocity spectrum, representing the greatest number of scatterers) and averaging over 5 beats (6 to 10 in atrial fibrillation). The product of area and time-velocity integral provided stroke volume.38 39 45 46 47 48 49 50 Mitral stroke volume was calculated by the method of Fisher et al41 as the product of peak mitral valve cross-sectional area at the level of the leaflet tips from the parasternal short-axis view multiplied by the mean-to-maximum ratio of mitral valve excursion from an M-mode tracing at that level multiplied by the time-velocity integral of modal velocity at the level of the leaflet tips by pulsed Doppler echocardiography in the apical four-chamber view (mean of 5 beats in sinus rhythm).41 43 45 46 47 48 49 50

Mitral regurgitant jet velocities were measured by continuous wave Doppler directed from the apex through the jet origin to provide the highest, most continuous velocity envelope. Peak velocity and time-velocity integral were measured on a Sony off-line analysis system and averaged in 5 beats (6 to 10 in atrial fibrillation). Effective regurgitant orifice area was calculated as pulsed Doppler regurgitant stroke volume divided by the time-velocity integral of continuous wave Doppler orifice velocity.53 54

Catheterization
Right- and left-side cardiac catheterization and left ventriculography were performed in 33 patients by standard techniques within 24 hours of echocardiography. Left ventriculography was performed in a 30-degree right anterior oblique projection in 12 patients and 30-degree right and 60-degree left anterior oblique projections in 21 patients, with injection of 40 mL of contrast through a pigtail catheter in the central left ventricular cavity. Care was taken to avoid assessment of regurgitation in relation to premature or postpremature contractions. The severity of mitral insufficiency was graded by two independent observers who had no knowledge of the results of the echocardiographic studies according to standard criteria55 : grade I, mild; grade II, moderate; and grade III, severe. In 13 patients who were in sinus rhythm without significant aortic or tricuspid insufficiency, regurgitant stroke volume was calculated as the difference between angiographic left ventricular stroke volume and forward stroke volume by thermodilution in the absence of significant tricuspid or aortic insufficiency.56 57 Because regurgitant jet size may be affected by changes in driving pressure,3 10 11 14 15 16 17 18 heart rate and systolic blood pressure were routinely recorded during each examination. Mean heart rate and systolic blood pressure were 68±11 beats per minute and 135.9±13.5 mm Hg at the time of transthoracic Doppler studies and were not significantly different at the time of cardiac catheterization (70±12 beats per minute; 136.8±14.9 mm Hg; P>.05), with good correlations at the two times (for heart rate, y=1.0x+1.4, r=.93, SEE=5; for blood pressure, y=0.87x+17, r=.96, SEE=4.0).

Statistical Analysis
Linear regression analysis was performed of proximal jet size measures (height, width, and area) versus both regurgitant fraction and regurgitant volume by Doppler. Linear regression analysis was also performed for proximal jet area multiplied by continuous wave Doppler peak velocity as well as by continuous wave time-velocity integral, considering that the regurgitant flow rate and volume of a jet might relate to both its proximal size and its orifice velocity.31 The values of each measure of the proximal jet were also plotted versus angiographic grade to display their potential to separate different grades. One-way ANOVA was performed to test for differences in jet size between the different grades, with two-way comparisons performed using Student's t test for unpaired data with the Bonferroni correction. Proximal jet measures were also compared with angiographic regurgitant fraction by linear regression. The degree of correlation between each of the proximal jet measures and the measures of regurgitant volume and fraction were compared by Z-transformation of the correlation coefficients for height versus width versus area. The variances about the regression lines and the variances of each measure among angiographic grades were also compared by F test for height versus width versus area.

Observers
Doppler Studies
The observer variability for mitral regurgitant fraction has been reported to be <7% by our group and others.23 51 52 53 As a baseline reference for the present study, mitral and aortic forward volume were calculated in 10 patients without mitral and aortic regurgitation. The difference (mitral minus aortic) in stroke volume was -1.1±3.0 mL (mean±SD), and the calculated regurgitant fraction was -1.5±6.7%.

Color Doppler Studies
Two observers independently measured proximal jet size in 10 patients; their observer variability, expressed as the standard deviation of the differences in their measurements, was 5.6% for jet height, 5.2% for width, and 6.6% for area.


*    Results
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*Results
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Proximal Jet Height
Proximal jet height correlated well with regurgitant fraction by Doppler echocardiography (r=.93, SEE=6.5%, Fig 3ADown) and could distinguish all three angiographic grades of regurgitation (Fig 4ADown). (At the low end of the graph in Fig 3ADown, there is a spread in the data points, presumably reflecting measurement variability by both techniques for mild regurgitation.) A height of 0.55 cm or less corresponded to a regurgitant fraction of 25% or less and to mild angiographic regurgitation; and a height of 0.8 cm or less corresponded to a regurgitant fraction of 45% or less and to angiographic grades 1 to 2. Jet height values were 0.3±0.08 cm for patients with angiographic grade 1, 0.66±0.11 cm for angiographic grade 2, and 0.9±0.09 cm for patients with grade 3 (F=80, P<.0001 by ANOVA). Height also correlated well with regurgitant stroke volume by Doppler (r=.90, SEE=7.7 mL). In the 13 patients with angiographic volumes, jet height also correlated well with angiographic regurgitant fraction (r=.85, SEE=5.1%). The parasternal long-axis views in Fig 5ADown illustrate the increase in proximal jet height with increasing regurgitation from mild to moderate and then severe. The patient on the right had a flail posterior mitral leaflet; turning the color on and off allowed us to recognize the anterior leaflet more clearly and to identify the point at which the jet emerged from between the leaflets before spreading behind the anterior leaflet.



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  		Figure 3. Plots of linear regression analyses of Doppler regurgitant fraction versus proximal jet height (A), width (B), and area (C). (Spread of data points at lower left presumably reflects measurement variability by both techniques at the level of low regurgitant fraction.)



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  		Figure 4. Plots of values for proximal (prox) jet height (A), width (B), and area (C) versus angiographic grade of mitral regurgitation (MR).



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  		Figure 5. A, Parasternal long-axis color Doppler echocardiographic views illustrating increase in proximal jet height with increasing severity of regurgitation from mild (left) to moderate and severe (right). Patient represented on the right had a flail posterior mitral leaflet; turning the color on and off allowed us to recognize the anterior leaflet more clearly and to identify the point at which the jet emerged from between the leaflets (arrows) before spreading behind the anterior leaflet. B, Parasternal short-axis color Doppler echocardiographic scans through proximal mitral regurgitant jets illustrating the increase in proximal jet area with increasing severity of regurgitation from mild (left: small, brightest orange-yellow flow just posterior to the midline of the cavity) to moderate and severe (right).

Proximal Jet Width
Proximal jet width correlated well with regurgitant fraction by Doppler echocardiography (r=.95, SEE= 5.9%, Fig 3BUp) and could separate all three angiographic grades of regurgitation (Fig 4BUp). A width of 0.8 cm or less corresponded to a regurgitant fraction of 25% or less and to mild angiographic regurgitation; a width of 1.5 cm or less corresponded to a regurgitant fraction less than 45% and to angiographic grades 1 to 2. Jet width values were 0.39±0.13 cm for patients with angiographic grade 1, 1.01±0.25 cm for angiographic grade 2, and 2.01±0.22 cm for patients with grade 3 (F=170, P<.0001 by ANOVA). Width also correlated well with regurgitant stroke volume by Doppler (r=.88, SEE=8.2 mL). In the 13 patients with angiographic volumes, jet width also correlated well with angiographic regurgitant fraction (r=.91, SEE=4.1%).

Proximal Jet Area
Proximal jet area also correlated well with regurgitant fraction by Doppler echocardiography (r=.92, SEE=7.3%, Fig 3CUp). The correlation coefficient and standard error were virtually unchanged for the regression of Doppler regurgitant fraction versus jet area multiplied by the continuous wave Doppler peak velocity as well as multiplied by the time-velocity integral. Proximal jet area could also distinguish all three angiographic grades of regurgitation (Fig 4CUp). An area of less than 0.3 cm2 corresponded to a regurgitant fraction of 25% or less and to mild angiographic regurgitation in the large majority of patients in this range (30 of 31); an area of less than 0.8 cm2 corresponded to a regurgitant fraction of less than 45% and to angiographic grades 1 to 2. Jet area values were 0.13±0.07 cm2 for patients with angiographic grade 1, 0.4±0.15 cm2 for angiographic grade 2, and 1.01±0.19 cm2 for patients with grade 3 (F=127, P<.0001 by ANOVA). Area also correlated well with regurgitant stroke volume by Doppler (r=.86, SEE=9.0 mL). In the 13 patients with angiographic volumes, jet area also correlated well with angiographic regurgitant fraction (r=.91, SEE=4.1%). Proximal jet area correlated well with Doppler effective regurgitant orifice area, with consistent overestimation (y=2.69x-0.01, r=.91, SEE=0.19, so that using proximal jet area/2.69 gave an effective orifice area with an SEE of 0.07 cm2). The parasternal short-axis views in Fig 5BUp show increasing proximal jet area in patients with mild, moderate, and severe regurgitation.

Wall and Free Jets
Of the total of 49 patients, 35 had central or free jets (not attaching to atrial walls or only impacting on the distal superior wall) and 14 had wall jets.22 23 24 Multiple linear regression analysis showed no difference in the relation between proximal jet dimensions and Doppler regurgitant fraction or angiographic grade for free versus wall jets (P>.05).

Height, Width, and Area
There was no significant difference between proximal jet height, width, or area in the degree of correlation or variance about the regression line relating each proximal jet measure and regurgitant volume or fraction (P>.05). The variance in proximal jet width among angiographic grades was significantly higher than that for height (P<.05); there were no significant differences in variance among grades between proximal jet area and either height or width.


*    Discussion
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*Discussion
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Proximal Jet Size
The results of the present study indicate that proximal jet size by Doppler color flow mapping correlates well with independent measures of regurgitant volume and fraction by quantitative Doppler echocardiography and left ventriculography and can distinguish patients with different angiographic degrees of regurgitation. This was true for the anteroposterior height of the jet, reflecting malcoaptation in that orientation; the mediolateral extent or width over which regurgitation occurs; and the cross-sectional area of the proximal jet. Since the beginning of our study, Tribouilloy et al34 have independently reported a similar relation between proximal jet dimension measured by monoplane transesophageal echocardiography and angiographic severity. The value that best distinguished milder from more severe regurgitation in their study, 0.55 cm, presumably largely in long-axial views, is similar to the jet height value, 0.55 cm, separating mild from moderate and severe regurgitation in Figs 3AUp and 4AUp. The present study confirms that this approach can be applied by the conventional transthoracic approach as well, which is the approach of first choice in the vast majority of patients studied by echocardiography. It also establishes the relation between proximal jet cross-sectional area and severity of regurgitation, as well as describing standardized measures in perpendicular views. Although the proximal jet dimensions correlated equally well with measures of regurgitant volume and fraction, width had the greatest variance among angiographic grades, reflecting the mediolateral extent of impaired coaptation that can be appreciated in short-axis scans; the variance among grades for area was not significantly different from that for width. Proximal jet size has gained widespread acceptance as a useful clinical adjunct in the routine evaluation of aortic insufficiency7 27 29 35 ; we believe that it has similar potential for mitral regurgitation, and the results of the present study would support such use.

Concept of Proximal Jet Area
We specifically examined proximal jet area only, as an observable measurement provided by Doppler color flow mapping, not regurgitant orifice area. Nevertheless, several groups have shown that the size of the jet as it emerges from an orifice bears a consistent relation to the size of the orifice itself, which is a fundamental measure of the regurgitant lesion, with overestimation the rule,27 30 31 albeit less so when imaging jet height with the axial resolution of the transducer.28 30 The limited lateral resolution of echocardiography resulting from finite beam width will necessarily increase apparent proximal jet dimension perpendicular to the beam, as well as its area, consistent with the observed overestimation of effective regurgitant orifice area, which was similar in slope to that reported in vitro.30 The contraction of the jet from orifice to vena contracta can act in the opposite direction,58 59 60 as can the tissue priority algorithm of the imaging device, which will limit color display to regions bounded by leaflet structures. This may account, for example, for the accuracy of proximal mitral stenotic jet dimensions imaged with lateral resolution in a prior study.61 In any event, it was our aim simply to examine the observable proximal jet at its narrowest point, thereby taking into account any contraction that may have occurred, although not evident from the images.34 Lateral resolution effects should be relatively similar among the patients studied, with comparable transducer frequencies and scanning depths.

Advantages of Proximal Jet
In vivo studies have shown that the location and extent of the mitral regurgitant jet origin reflect the underlying extent of the valvular lesion and can therefore guide surgical intervention.62 Other studies have shown that, in general, proximal jet dimensions have an important advantage over the size of the jet within the receiving chamber, which varies with driving pressure for a given regurgitant flow rate.3 11 14 15 18 27 30 63 Proximal jet size has been found to be relatively unaffected by flow rate and driving pressure within the clinically meaningful range,27 28 30 31 in which the velocity component recorded does not fall below the color Doppler display threshold. The propagating distal jet is also highly affected by interaction with atrial walls and flows and by instrument gain and wall filter settings, which can alter the display of low velocities in the jet periphery. The proximal jet, in contrast, should be relatively protected from interactions that develop within the atrium, and the high velocities at the jet origin are relatively resistant to changes in instrument settings.28 Although the limiting influence of atrial size on the distal jet suggests potential value to normalizing jet area to atrial area,6 the proximal jet is not so limited and therefore normalization was not used. Although techniques based on convergence of flow proximal to the orifice are now being developed to quantify regurgitant flow, they require further analysis to determine the site or method for optimal flow rate calculation,64 65 66 67 68 69 70 71 whereas the proximal jet technique described can be applied at this time to provide a rapid visual assessment and grading of the lesion.

Although the pulsed Doppler subtraction of aortic forward flow from mitral inflow38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 is a quantitative standard,23 52 53 72 there are several motivations for evaluating proximal jet size: it should apply even in the presence of aortic insufficiency; it is a complementary measure, related to defect size, that can increase our confidence in the noninvasive assignment of severity52 ; and it provides a rapid visual assessment that can also potentially aid in the quantitative Doppler learning curve.52

Study Limitations and Future Directions
It was not our aim to determine how often the proximal jet could be seen but rather to provide quantitative measurements and comparisons with other independent assessments of the severity of regurgitation in a group of patients with clearly visualized proximal jets, as in similar studies of aortic insufficiency.7 28 Our clinical impression is that this technique should be readily and widely applicable in patients with mitral regurgitation, but further study is required to confirm this.

There was no additional value in combining proximal jet size with orifice velocity in the present study or that of Tribouilloy et al.34 This most likely reflects the relatively narrow range of clinically encountered orifice velocities (typically 4 to 5 m/s), which relate to the square root of the driving pressure. Nevertheless, it is conceivable that in patients with aortic stenosis, for example, higher driving pressures may result in higher flows for the same proximal jet size.

The method used examined only one point in the cardiac cycle, reflecting the maximal size of the proximal jet. Potential future developments, such as high frame rate, high-resolution Doppler color flow mapping, could potentially allow us to explore temporal variation in proximal jet size72 and its physiological dependence on hemodynamics and ventricular geometry73 ; however, this was not the intent of the present study.

It is important to recognize the technical limitations of methods based on the proximal jet. First, irregularity and variation in orifice shape can produce a variable relation between any single jet dimension and total area,29 30 although in the present study both linear dimensions and area produced comparable results. Second, rapid divergence of the jet beyond the orifice needs to be recognized, as in the case of aortic insufficiency.27 30 34 However, this can be clearly displayed in the long-axis view, allowing rapid visual selection of the narrowest jet height, and careful scanning of the cross-sectional view can be used to find the minimal jet size. This will also take into account any contraction that occurs beyond the orifice as a function of leaflet geometry proximal to it.58 59 60 Limitations of acoustic window may preclude obtaining precisely oriented short-axis cuts of the proximal jets, and motion of the orifice during systole may account for additional variability30 ; nevertheless, good agreement with other methods was noted by the techniques used to scan for minimal proximal dimension. Third, eccentric jets may rapidly attach to atrial and leaflet structures; it is then important to make measurements and scan across the narrowest dimension of the jet, guided by its visualized region of passage between the leaflets and emergence from them. Results for free and wall jets in the present study were comparable, reflecting this technique. Fourth, the limited video bandwidth of the color display can potentially be overcome by direct examination of digital color flow maps, with the added potential for automated quantitation of proximal jet size and three-dimensional reconstruction of the flow field to obtain the most accurate sections.

Because of the well-recognized limitations of clinical standards for quantifying mitral regurgitation,74 we used a combination of invasive and noninvasive methods. The noninvasive regurgitant stroke volume, in particular, has now been reported to be accurate by multiple groups for research purposes23 47 48 49 52 53 and produced essentially no apparent measurable regurgitation in healthy subjects in the present study.

Summary
Proximal jet size correlates well with other established measures of the severity of mitral regurgitation. It can be assessed by conventional transthoracic echocardiography with current equipment in a rapid and convenient manner. As in the case of the proximal jet in aortic insufficiency, therefore, it should be useful in the routine evaluation of patients with mitral regurgitation. The quantitative comparisons in the present study lay the foundation for future clinical and research studies using this technique.


*    Acknowledgments
 
This work was supported in part by a grant of the American Heart Association, Dallas, Tex, with funds contributed in part by its Massachusetts Affiliate, Natick, Mass and by contributions from Rena M. Shulsky, New York, NY. Dr Mele was supported in part by a grant from Accademia delle Scienze, Ferrara, Italy. Dr Levine is an Established Investigator of the American Heart Association, Dallas, TX.


*    Footnotes
 
Reprint requests to Robert A. Levine, MD, Noninvasive Cardiac Laboratory, Massachusetts General Hospital, Vincent-Burnham 5, Boston, MA 02114.

Received February 2, 1994; accepted September 23, 1994.


*    References
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 up arrowAbstract
 up arrowIntroduction
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up arrowResults
up arrowDiscussion
*References
 

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