Quantification of mitral valvular incompetence

Clinical Use of Doppler Echocardiography in Organic Mitral Regurgitation: From Diagnosis to Patients' Management

Knowledge of mitral regurgitation (MR) is essential for any care provider, and not only for those directly involved in the management of cardiovascular diseases. This happens because MR is the most frequent valvular lesion in North America and the second most common form of valve disease requiring surgery in Europe. Furthermore, due to the ageing of the general population and the reduced mortality from acute cardiovascular events, the prevalence of MR is expected to increase further. Doppler echocardiography is essential both for the diagnosis and the clinical management of MR. In the present article, we sought to provide a practical step-by-step approach to help either performing a Doppler echocardiography or interpreting its findings in light of contemporary knowledge on organic (but not only) MR.

Cardiovascular Magnetic Resonance for Direct Assessment of Anatomic Regurgitant Orifice in Mitral Regurgitation

Background— In patients with mitral regurgitation (MR), assessment of the severity of valvular dysfunction is crucial. Recently, regurgitant orifice area has been proposed as the most useful indicator of the severity of MR. The purpose of our study was to determine whether planimetry of the anatomic regurgitant orifice (ARO) in patients with MR is feasible by cardiovascular magnetic resonance (CMR) and correlates with invasive catheterization and echocardiography effective regurgitant orifice [ECHO-ERO] by proximal isovelocity surface area.

Methods and Results— Planimetry of ARO was performed with a 1.5-T CMR scanner using a breath-hold balanced gradient echo sequence true fast imaging with steady state precession (TrueFISP). CMR planimetry of ARO was possible in 35 of 38 patients and was closely correlated with angiographic grading ( r =0.84, P <0.0001). In patients with MR grade ≥III on catheterization, CMR-ARO (0.60�0.29 cm 2 versus 0.30�0.19 cm 2 , P <0.0001) as well as ECHO-ERO (0.49�0.17 cm 2 versus 0.27�0.10 cm 2 ) were significantly elevated in comparison with MR grade <III. Further, CMR-ARO was closely correlated to CMR regurgitant fraction and volume ( r =0.90 and r =0.91, P <0.0001, respectively) and catheterization regurgitant fraction and volume ( r =0.86 and 0.83, P <0.0001, respectively). The correlation between CMR-ARO and ECHO-ERO was 0.81 ( P <0.0001) and CMR slightly overestimated ECHO-ERO by 0.06 cm 2 ( P <0.05). As assessed by receiver operating characteristic analysis, CMR-ARO at a threshold of 0.40 cm 2 detected MR grade ≥III as defined by catheterization, with a sensitivity and specificity of 94% and 94%, respectively.

Conclusion— CMR planimetry of the anatomic mitral regurgitant lesion in patients with MR is feasible and permits quantification of MR with good agreement with the accepted invasive and noninvasive methods. Direct measurement by CMR is a promising new method for the precise assessment of ARO area and the severity of MR.

Quantification of Functional Mitral Valve Regurgitation in Patients With Congestive Heart Failure

OBJECTIVES

We sought to determine the agreement between electron-beam computed tomography (CT) and cardiac catheterization for the quantification of mitral regurgitation and to evaluate their association with echocardiographic assessment.

MATERIAL AND METHODS

Fifty patients with congestive heart failure were examined both by electron-beam CT and catheterization to calculate mitral regurgitation volume and fraction based on the difference between the left ventricular stroke and aortic flow volume. The severity of regurgitation was also compared with visual assessment by echocardiography (grade, 0-4+).

RESULTS

The mean values for the mitral regurgitation volume and fraction did not differ significantly between electron-beam CT and catheterization (mean differences: 0.2 mL/m2 and -0.9%, P > 0.05 each, limits of agreement: -14.0 to 14.4 mL/m2 and -26.3 to 24.5%, respectively) and showed a good correlation (r = 0.79 and r = 0.76, respectively; P < 0.05 each). Good levels of correlation were observed between echocardiographic severity grading and quantitative measurements of regurgitation volume and fraction, which were somewhat better between echocardiography and electron-beam CT (rS = 0.78 and rS = 0.84, respectively; P < 0.05 each) than between echocardiography and catheterization (rS = 0.72 and rS = 0.81, respectively; P < 0.05 each).

CONCLUSION

Our results suggest that electron-beam CT allows for quantification of mitral valve regurgitation with similar accuracy as cardiac catheterization. Measurements with both modalities correlated well with the results of echocardiographic assessment.

Quantification of mitral valve regurgitation by left ventricular volume and flow measurements using electron beam computed tomography: comparison with magnetic resonance imaging

PURPOSE

This study was designed to evaluate electron beam computed tomography (CT) for quantifying mitral regurgitation in comparison with magnetic resonance (MR) imaging as a reference method.

METHOD

Forty-three patients, among them 33 with known mitral regurgitation, underwent electron beam CT and MR imaging. Total left ventricular stroke volume (TSV), antegrade stroke volume (ASV), and mitral regurgitation volume (MRV) and fraction (MRF) were determined and compared between the two modalities. Additionally electron beam CT measurements were compared with the corresponding echocardiographic findings.

RESULTS

Significant differences between electron beam CT and MR imaging were found for measurements of TSV and MSV but not for ASV and MRF. There was a close linear correlation between both modalities for all parameters. Furthermore, there was good agreement between electron beam CT and echocardiography, although electron beam CT shows a tendency to overestimate mitral regurgitation slightly.

CONCLUSION

The results indicate that electron beam CT offers an additional procedure for quantifying mitral regurgitation and that it may be used as an alternative to MR imaging.

Quantitation of functional mitral regurgitation during bicycle exercise in patients with heart failure

OBJECTIVES

We sought to examine the feasibility and reliability of quantifying mitral regurgitation (MR) during exercise by Doppler echocardiography in patients with heart failure and to assess the relationship between dynamic MR and systolic pulmonary artery pressure changes.

BACKGROUND

The severity of MR can be quantified by using several echocardiographic methods. Quantitation of MR during dynamic exercise has not yet been performed.

METHODS

Symptom-limited, semi-supine two-dimensional and Doppler echocardiograms during bicycle exercise were obtained in 27 consecutive patients with heart failure and functional MR. Regurgitant volume was measured at rest and during exercise by the proximal isovelocity surface area (PISA) method and by quantitative Doppler echocardiography. Exercise-induced changes in regurgitant volume were compared with changes in the regurgitant jet area to left atrial area ratio, vena contracta width and trans-tricuspid pressure gradient.

RESULTS

The regurgitant volume measured by the PISA method increased from 21 +/- 12 ml (range 5 to 55) at rest to 39 +/- 23 ml (range 8 to 85) during exercise (p < 0.0001). The difference between two observers was low for both rest (2.0 +/- 2.7 ml) and exercise measurements (3.5 +/- 6.2 ml). The regurgitant volume measured by quantitative Doppler echocardiography increased from 29 +/- 13 to 49 +/- 24 ml (p = 0.0001). Excellent correlation between the two methods was obtained with exercise (r = 0.92). Exercise-induced changes in regurgitant volume, as measured by the PISA method, correlated well with regurgitant volume changes measured by quantitative Doppler echocardiography (r = 0.88), changes in vena contracta width (r = 0.82) and changes in trans-tricuspid pressure gradient (r = 0.73), but not with changes in regurgitant jet area to left atrial area ratio (r = 0.29). Seventeen patients stopped exercise because of fatigue and 10 because of dyspnea. These 10 patients exhibited greater increases in regurgitant volume (34 +/- 6 vs. 11 +/- 8 ml), corresponding to a significant elevation of the trans-tricuspid gradient (48 +/- 14 vs. 20 +/- 14 mm Hg).

CONCLUSIONS

Quantitation of functional MR during exercise is feasible in patients with heart failure. There is a good correlation between regurgitant volume measured during exercise by the PISA method and that obtained by quantitative Doppler echocardiography, suggesting that the technique is reliable. An increase in mitral regurgitant volume during dynamic exercise correlates well with elevation of systolic pulmonary artery pressure.

Quantitation of mitral regurgitation using the systolic/diastolic pulmonary venous flow velocity ratio

OBJECTIVES

The purpose of this study was to test the hypothesis that pulmonary venous flow velocity ratios during systole and diastole in patients with mitral regurgitation (MR) correctly predict the quantitative degree of MR.

BACKGROUND

Pulmonary venous flow velocity measurements have thus far been used only for the qualitative assessment of MR. Recent studies have evaluated this method using transesophageal echocardiography against semiquantitative references.

METHODS

In 100 patients without aortic regurgitation or atrial fibrillation and with left ventricular (LV) ejection fraction >45%, MR was assessed by quantitative echocardiographic Doppler and color Doppler, providing forward and total LV stroke volume for the calculation of the mitral regurgitant fraction (RFstandard), the reference parameter, and also supplying mitral regurgitant orifice area (ROA) values and the RF by the flow convergence method (RFPISA [proximal isovelocity surface area]). Measurements of pulmonary venous flow velocity time integral values during systole to diastole (VTIs/VTId) were obtained and tested for their predictibility of ROA, RFstandard and RFPISA.

RESULTS

There was an inverse and significant correlation between VTIs/VTId and ROA, RFPISA and RFstandard, respectively: RFstandard=49 - 20 VTIs/VTId, r=0.77, p=0.0001. A principal source of variability in the relation between VTIs/VTId and RFstandard was the presence of mitral valve prolapse as the cause of MR. Pulmonary venous flow reversal (VTIs/VTId <0) correctly identified severe MR with 52% sensitivity, 96% specificity and 80% positive and 87% negative predictive accuracy.

CONCLUSIONS

The VTIs/VTId ratio allows a moderately accurate assessment of the severity of MR.

Rapid estimation of regurgitant volume by the proximal isovelocity surface area method in mitral regurgitation: Can continuous-wave Doppler echocardiography be omitted?

The proximal isovelocity surface area (PISA) method is accurate for quantitating mitral regurgitation but requires recording both mitral maximal and integrated jet velocities using the same continuous-wave Doppler jet signal. In 272 consecutive patients with isolated mitral regurgitation, the mean ratio of maximal to integral of velocity had a narrow range of variation (mean +/- SD, 3.25 +/- 0.47). The estimated regurgitant volume, calculated as regurgitant flow/3.25, showed an excellent correlation with reference regurgitant volumes (r = 0.96 and r = 0.97; standard error of the estimate, 11 ml; both p < 0.0001), with limited overestimation and high sensitivity and specificity for severe mitral regurgitation. The estimated regurgitant volume is a useful measurement in patients in whom the continuous-wave Doppler signal of mitral regurgitation cannot be obtained.

Grading of mitral regurgitation by quantitative Doppler echocardiography: calibration by left ventricular angiography in routine clinical practice

BACKGROUND

Quantitative Doppler echocardiography and proximal flow convergence methods are validated techniques for quantifying mitral regurgitation. However, the clinical interpretation of the values calculated is hindered by the absence of calibration of ranges of severity in large numbers of patients.

METHODS AND RESULTS

In 180 consecutive patients (men, 62%; mean age+/-SD, 66+/-11 years), the results of Doppler quantification of isolated mitral regurgitation were calibrated by use of left ventricular angiographic grading performed within 3 months in routine practice and without intervening events. The thresholds of the quantitative variables corresponding to the angiographic grades were identified by maximizing the sum of sensitivity and specificity and minimizing their difference. The mitral regurgitation grade by angiography was 2.7+/-1.3. The mean value and correlation with angiographic grades for effective regurgitant orifice were 43+/-37 mm and r=.79 (P<.0001); for regurgitant volume, 62+/-45 mL and r=.80 (P<.0001); and for regurgitant fraction, 45+/-17% and r=.78 (P<.0001). Despite some overlap, differences between mitral regurgitation grades were all significant (all P<.05). The thresholds for severe mitral regurgitation (grade 4) were 60 mL, 50%, and 40 mm2 for regurgitant volume, regurgitant fraction, and orifice, respectively.

CONCLUSIONS

In routine practice in large numbers of patients in a clinical laboratory, Doppler echocardiographic quantification of mitral regurgitation shows highly significant correlation with qualitative angiographic grades. Despite an expected overlap between classes, the calibration by angiography of grading ranges for the quantitative variables provides a framework for their interpretation and allows the definition in clinical practice of thresholds for severe mitral regurgitation.

Intensity of murmurs correlates with severity of valvular regurgitation

PURPOSE

To evaluate the relationship between the intensity of murmurs and severity of mitral and aortic regurgitation.

PATIENTS AND METHODS

Consecutive patients with chronic isolated aortic (n = 40) or mitral (n = 170) regurgitation undergoing echocardiographic quantitation of regurgitation between 1990 and 1991 were studied. Regurgitant volume and fraction were measured using two simultaneous methods (quantitative Doppler echocardiography and quantitative two-dimensional echocardiography); the intensity of the regurgitant murmur (grade 0 to 6) was noted by physicians unaware of the study.

RESULTS

Correlations between murmur intensity and regurgitant volume and fraction were good in aortic regurgitation (r = .60 and r = .67, respectively; P < 0.001) and mitral regurgitation (r = .64 and r = .67, respectively; P < 0.001) but weaker (r = .47 and r = .45, respectively) in the subset of mitral regurgitation of ischemic or functional cause. Murmur intensity grades > or = 3 for aortic regurgitation and > or = 4 for mitral regurgitation predicted severe regurgitation (regurgitant fraction > or = 40%) in 71% and 91% of patients, respectively. Murmur grades < or = 1 for aortic regurgitation and < or = 2 for mitral regurgitation predicted "not severe" regurgitation in 100% and 88% of patients, respectively. Murmur grades 2 for aortic regurgitation and 3 for mitral regurgitation were not correlated to degree of regurgitation. The severity of regurgitation was the most powerful determinant of intensity of murmur.

CONCLUSIONS

Murmur intensity correlates well with the degree of chronic organic aortic and mitral regurgitation, and can be used as a predictor of regurgitation severity and as a simple guideline for diagnostic testing in these patients.

Effective mitral regurgitant orifice area: clinical use and pitfalls of the proximal isovelocity surface area method

OBJECTIVES

We attempted to determine the accuracy and pitfalls of calculating the mitral regurgitant orifice area with the proximal isovelocity surface area method in a clinical series that included patients with valvular prolapse and eccentric jets.

BACKGROUND

The effective regurgitant orifice area, a measure of lesion severity of mitral regurgitation, can be calculated by the proximal isovelocity surface area method, the accuracy and pitfalls of which have not been established.

METHODS

In 119 consecutive patients with isolated mitral regurgitation, effective regurgitant orifice area was measured by the proximal isovelocity surface area method and compared with measurements simultaneously obtained by quantitative Doppler and quantitative two-dimensional echocardiography.

RESULTS

The effective mitral regurgitant orifice area measured by the proximal isovelocity surface area method tended to be overestimated compared with that measured by quantitative Doppler and quantitative two-dimensional echocardiography (38 +/- 39 vs. 36 +/- 33 mm2 [p = 0.09] and 34 +/- 32 mm2 [p = 0.02], respectively). Overestimation was limited to patients with prolapse (61 +/- 43 vs. 56 +/- 35 mm2 [p = 0.05] and 54 +/- 34 mm2 [p = 0.014]) and was restricted to patients with nonoptimal flow convergence (n = 7; 137 +/- 35 vs. 84 +/- 34 mm2 [p = 0.002] and 79 +/- 33 mm2 [p = 0.002]). In patients with optimal flow convergence (n = 112), excellent correlations with both reference methods were obtained (r = 0.97, SEE 6 mm2 and r = 0.97, SEE 7 mm2, p < 0.0001).

CONCLUSIONS

In calculating the mitral effective regurgitant orifice area with the proximal isovelocity surface area method, the observed pitfall (overestimation due to nonoptimal flow convergence) is rare. Otherwise, the method is reliable and can be used clinically in large numbers of patients.

Effective regurgitant orifice area: a noninvasive Doppler development of an old hemodynamic concept

OBJECTIVES

The purpose of this study was to determine the feasibility, relation to other methods and significance of the effective regurgitant orifice area measurement.

BACKGROUND

Assessment of the severity of valvular regurgitation (effective regurgitant orifice area) has not been implemented in clinical practice but can be made by Doppler echocardiography.

METHODS

Effective regurgitant orifice area was calculated by Doppler echocardiography as the ratio of regurgitant volume/regurgitant jet time-velocity integral and compared with color flow Doppler mapping, angiography, surgical classification, regurgitant fraction and variables of volume overload.

RESULTS

In 210 consecutive patients examined prospectively, feasibility improved from the early to the late experience (65% to 95%). Effective regurgitant orifice area was 28 +/- 23 mm2 (mean +/- SD) for aortic regurgitation (32 patients), 22 +/- 13 mm2 for ischemic/functional mitral regurgitation (50 patients) and 41 +/- 32 mm2 for organic mitral regurgitation (82 patients). Significant correlations were found between effective regurgitant orifice and mitral jet area by color flow Doppler mapping (r = 0.68 and r = 0.63, p < 0.0001, respectively) and angiographic grade (r = 0.77, p = 0.0004). Effective regurgitant orifice area in surgically determined moderate and severe lesions was markedly different in mitral regurgitation (35 +/- 12 and 75 +/- 33 mm2, respectively, p = 0.009) and in aortic regurgitation (21 +/- 8 and 38 +/- 5 mm2, respectively, p = 0.08). Strong correlations were found between effective regurgitant orifice area and variables reflecting volume overload. A logarithmic regression was found between effective regurgitant orifice area and regurgitant fraction, underlining the complementarity of these indexes.

CONCLUSIONS

Calculation of effective regurgitant orifice area is a noninvasive Doppler development of an old hemodynamic concept, allowing assessment of the lesion severity of valvular regurgitation. Feasibility is excellent with experience. Effective regurgitant orifice area is an important and clinically significant index of regurgitation severity. It brings additive information to other quantitative indexes and its measurement should be implemented in the comprehensive assessment of valvular regurgitation.

Amplitude-weighted mean velocity: clinical utilization for quantitation of mitral regurgitation

OBJECTIVES

The purpose of this study was to determine the clinical usefulness of the amplitude-weighted mean velocity method for quantitation of mitral regurgitation.

BACKGROUND

Amplitude-weighted mean velocity is a nonvolumetric method for calculating the mitral regurgitant fraction. Its previous validation at one center mandated an independent assessment of its usefulness and limitations.

METHODS

In 56 patients with and 16 patients without mitral regurgitation, the regurgitant fraction was measured simultaneously by amplitude-weighted mean velocity, quantitative Doppler study and quantitative two-dimensional echocardiography. In 16 patients, multiple gain settings were used to determine the influence of this variable on amplitude-weighted mean velocity.

RESULTS

In patients without regurgitation, amplitude-weighted mean velocity showed more scattering of regurgitant fraction (-18% to 23%) than Doppler (p = 0.016) or two-dimensional echocardiography (p = 0.022). The absolute value of regurgitant fraction was (mean +/- SD) 8 +/- 6%, 4 +/- 2% and 4 +/- 3%, respectively (p = NS). With increasing gain, the amplitude-weighted mean velocity mitral and aortic integrals increased, but the calculated regurgitant fraction remained unchanged. In patients with mitral regurgitation, significant correlation was found between amplitude-weighted mean velocity and Doppler study (r = 0.79, p = 0.0001) and between amplitude-weighted mean velocity and two-dimensional echocardiography (r = 0.76, p = 0.0001) for calculated regurgitant fraction, but the standard error of the estimate (12%) was large.

CONCLUSIONS

The amplitude-weighted mean velocity-calculated regurgitant fraction is gain independent, whereas the aortic and mitral integrals are gain dependent. Compared with Doppler and two-dimensional echocardiography, it shows more scattering of values in patients without regurgitation, but the methods correlate significantly in patients with mitral regurgitation. Amplitude-weighted mean velocity can be used as a simple adjunctive tool for comprehensive, noninvasive quantitation of mitral regurgitation.

Application of color Doppler flow mapping to calculate effective regurgitant orifice area. An in vitro study and initial clinical observations

BACKGROUND

Analogous to stenotic valve area in the assessment of valvular stenosis, regurgitant orifice area (ROA) represents a fundamental parameter to assess valvular insufficiency. However, this parameter has not been routinely available up to now. In this study, we introduce the concept and provide the methodology to calculate regurgitant orifice area noninvasively, based on the analysis of the proximal flow convergence zone.

METHODS AND RESULTS

In an in vitro study, we showed the feasibility and the accuracy of calculating effective ROA by the proximal flow convergence method throughout a range of driving pressures. The calculated and true ROA showed an excellent correlation with r = .992, delta ROA = -1.4 +/- 2.9 mm2. We then applied this concept clinically in 77 patients with mitral regurgitation and showed a very good correlation between effective ROA calculated by the proximal flow convergence method and calculated by the Doppler echocardiographic method: r = .95, delta ROA = -0.2 +/- 3.9 mm2. The ROA also correlated very well with Doppler echocardiographic-derived regurgitant stroke volume (r = .93) and regurgitant fraction (r = .82). In a subgroup of 20 patients who underwent invasive evaluation, the calculated effective ROA also correlated well with the angiographic grade of mitral regurgitation (rho = .81).

CONCLUSIONS

We conclude that effective ROA represents unique information on the severity of a regurgitant lesion and can easily be calculated by the proximal flow convergence method. This new parameter should enhance our understanding and improve the serial assessment of valvular regurgitation.

Color flow imaging compared with quantitative Doppler assessment of severity of mitral regurgitation: influence of eccentricity of jet and mechanism of regurgitation

OBJECTIVES

To determine the influence of jet eccentricity and mechanism of mitral regurgitation, we examined 1) the relation between jet extent and severity of mitral regurgitation, and 2) the use of Doppler color flow imaging for quantitation of mitral regurgitation.

BACKGROUND

Doppler color flow imaging is widely used to assess mitral regurgitation. However, whether, how and in which subgroups it can quantify regurgitation remain controversial.

METHODS

In 80 patients with mitral regurgitation, results of color flow Doppler studies obtained in two orthogonal apical views were prospectively compared with quantitative Doppler measurement of the regurgitant volume and the regurgitant fraction. Comparisons were made according to the eccentricity of the jet (group 1 eccentric jets, n = 29; group 2 central jets, n = 51); group 2 was subdivided according to the mechanism of mitral regurgitation (group 2a organic, n = 27; group 2b ischemic or functional, n = 24).

RESULTS

Globally, weak correlations were found between regurgitant volume and jet area (r = 0.57) and regurgitant fraction and jet area/left atrial area ratio (r = 0.65). Groups 1 and 2 showed a correlation between regurgitant volume and jet area (r = 0.68 and r = 0.65, respectively, p < 0.0001), but the slope was steeper in group 2 than in group 1 (0.22 vs. 0.06, p < 0.0001). The same jet area corresponded to more severe regurgitation in group 1 than in group 2 (jet > or = 8 cm2, regurgitant volume 113 +/- 55 vs. 43 +/- 21 ml, p < 0.0001). Similarly, for comparable regurgitant volumes (24 +/- 22 vs. 29 +/- 11 ml, p = NS), group 2a had a smaller jet area than did group 2b (5.3 +/- 6 vs. 9.6 +/- 6 cm2, p < 0.02). Quantitation of regurgitation by Doppler color flow imaging was unreliable in group 1; in group 2b, the regression line between regurgitant fraction and jet area/left atrial area ratio was close to the identity line.

CONCLUSIONS

Mitral regurgitant jet eccentricity and mechanism influence jet extent. The same regurgitant volume produces smaller jet areas for eccentric compared with central jets and for central organic compared with ischemic or functional regurgitation. Quantitation of regurgitation using Doppler color flow imaging is possible in ischemic or functional regurgitation but inappropriate in eccentric jets, where quantitative Doppler study should be recommended.

Pitfalls in the color Doppler diagnosis of valvular regurgitation

Color Doppler flow mapping of the regurgitant jet is frequently used as a means of assessing the severity of valvular regurgitation. Although convenient, this method of assessing valvular regurgitation is subject to a number of hemodynamic and technical factors that may limit its accuracy. Variations in hemodynamic and structural factors such as orifice size, jet geometry, receiving chamber constraints, afterload, fluid viscosity, heart rate, and cardiac output may have profound effects on the measured regurgitant jet area. Variations in scanning and machine factors, such as scanning direction, Doppler angle, frame rate, color display algorithms, pulse repetition frequency (PRF), system gain, packet size, carrier frequency, wall filter, and transmit power have been shown to alter the measured regurgitant jet area significantly. Despite these limitations, color flow Doppler provides a relatively reliable noninvasive method for semiquantitative assessment of valvular regurgitation. Obviously, standardization of the design and application of the various available color mapping algorithms, as well as other machine and hemodynamic factors, would help provide more reliable and reproducible quantitative information about the degree of valvular insufficiency.

Quantitative Doppler assessment of valvular regurgitation

BACKGROUND

Quantitation of valvular regurgitation remains a challenge. The accuracy of quantitative Doppler is controversial, and its ability to measure regurgitant volume is unknown; therefore, it is not widely used.

METHODS AND RESULTS

In 120 patients (20 without regurgitation, 19 with aortic regurgitation, and 81 with mitral regurgitation), the stroke volume through the mitral annulus and left ventricular outflow tract were measured using pulsed-wave Doppler concurrently with left ventricular stroke volume calculated using left ventricular volumes measured by two-dimensional echocardiography Simpson's biapical method. Regurgitant volume and fraction were thus computed using Doppler or ventricular methods. In normal patients there were good correlations between Doppler and left ventricular measurements of stroke volume. Doppler regurgitant volume and fraction were 4.4 +/- 4.4 mL and 5.3 +/- 4.5%, respectively. In patients with aortic regurgitation, there were good correlations between Doppler and left ventricular measurements of stroke volume, regurgitant volume, and regurgitant fraction (r = 0.97, r = 0.95, and r = 0.93, respectively; p < 0.0001). In patients with mitral regurgitation, despite good correlations between Doppler and ventricular methods for stroke volume, regurgitant volume, and regurgitant fraction (r = 0.94, r = 0.93, and r = 0.94, respectively; p < 0.001), these variables were overestimated by Doppler. However, in the last 54 patients compared with the first 27, overestimation decreased significantly for regurgitant volume (5 +/- 10 mL versus 18 +/- 27 mL, p < 0.05) and regurgitant fraction (3.3 +/- 6.7% versus 6.2 +/- 6.8%, p = 0.05).

CONCLUSIONS

Quantitative Doppler can be performed in large numbers of patients in a clinical laboratory. Its potential limitation was identified as overestimation of mitral regurgitation, which is overcome with increased experience. Its achieved accuracy in mitral and aortic regurgitation allows measurement not only of regurgitant fraction but most importantly of regurgitant volume.

Quantification of mitral regurgitation with the proximal flow convergence method: a clinical study

Accurate quantitation of valvular incompetence remains an important goal in clinical cardiology. It has been shown previously that when color flow Doppler mapping is used, simple measurements of apparent jet size do not correlate closely with regurgitant flow rate and regurgitant fraction. Recently the proximal flow convergence method has been proposed to quantify valvular regurgitation by analysis of the converging flow field proximal to a regurgitant lesion. Flow rate Q can be calculated as Q = 2 pi r2v(a), where v(a) is the aliasing velocity at a distance r from the orifice. In 54 patients (43 with sinus rhythm and 11 with atrial fibrillation) who had at least mild mitral regurgitation according to semiquantitative assessment, regurgitant stroke volume, regurgitant flow rate, and regurgitant fraction were calculated with the proximal flow convergence method and compared with values that were obtained by the Doppler two-dimensional echocardiographic method. Regurgitant stroke volumes (Vr) as calculated by the proximal flow convergence method correlated very closely with values that were obtained by the Doppler two-dimensional method, with r = 0.93 (y = 0.95x + 0.55) and delta Vr = -0.3 +/- 4.0 cm3. Regurgitant flow rates (Q) as calculated by both methods showed a similar correlation: r = 0.93 (y = 0.95x + 54) and delta Q = -34 +/- 284 cm3/min. The correlation for regurgitant fraction (RF) as calculated by both techniques showed r = 0.89 (y = 0.98x + 0.006) and delta RF = -0.005 +/- 0.06. All correlations were slightly better for the group of patients with sinus rhythm than for the study group of patients with atrial fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive measurement of the regurgitant fraction by pulsed Doppler echocardiography in isolated pure mitral regurgitation

OBJECTIVE

To assess the usefulness of pulsed Doppler echocardiography as a method of measuring the regurgitant fraction in patients with mitral regurgitation.

PATIENTS AND METHODS

Twenty controls and 27 patients with isolated mitral regurgitation underwent Doppler studies. In the patients the study was performed within 48 hours of cardiac catheterisation. Aortic outflow was measured in the centre of the aortic annulus, and mitral inflow was derived from the flow velocity at the tip of the leaflets and the area of the elliptical mitral opening. The regurgitant fraction was calculated as the difference between the two flows divided by the mtiral inflow.

RESULTS

In the 20 controls the two flows were almost identical (mitral inflow, 4.44 (SD 0.88) l/min; aortic outflow, 4.58 (SD 0.84) l/min), with a mean regurgitant fraction of 4.2 (SD 8.4)%. In patients with mitral regurgitation, the mitral inflow was significantly higher than the aortic outflow (8.8 (3.6) v 4.3 (1.1) l/min). In most patients the Doppler-derived regurgitant fraction (45.8 (19.2)%) accorded closely with the regurgitant fraction (41.3 (SD 17.8)%) determined by the haemodynamic technique.

CONCLUSION

Pulsed Doppler echocardiography, with an instantaneous velocity-valve area method for calculating mitral inflow, reliably measured the severity of regurgitation in patients with mitral regurgitation.

Intraoperative transesophageal Doppler color flow imaging used to guide patient selection and operative treatment of ischemic mitral regurgitation

BACKGROUND

Intraoperative transesophageal Doppler color flow imaging (TDCF) affords the opportunity to assess mitral valve competency immediately before and after cardiopulmonary bypass (CPB). The purpose of this study was to assess the utility of TDCF to assist in the selection and operative treatment of ischemic mitral regurgitation (MR).

METHODS AND RESULTS

Two hundred forty-six patients undergoing surgery for ischemic heart disease were prospectively studied. All had preoperative cardiac catheterization. Catheterization and pre-CPB TDCF were discordant in their estimation of MR in 112 patients (46%). Compared with patients in whom both techniques agreed in estimation of MR, patients with discordance in MR were more likely to have had unstable clinical syndromes at the time of catheterization (79% versus 40%, p less than 0.05) or to have received thrombolytics (16% versus 8%, p less than 0.05). Pre-CPB TDCF resulted in a change in the operative plan with respect to the mitral valve in 27 patients (11%). Because less MR was found by TDCF than catheterization, 22 patients had only coronary bypass grafting when combined coronary bypass and mitral valve surgery had been planned. Because more MR was found by TDCF than catheterization, five patients had combined coronary bypass and mitral valve surgery when coronary bypass alone had been planned. Unsatisfactory results noted by TDCF following mitral valve surgery in five patients resulted in immediate corrective surgery. Cox regression analysis identified residual MR at the completion of surgery to be an important predictor of survival (chi 2 = 21.4) after surgery--more important than patient age (chi 2 = 8.3) or left ventricular ejection fraction (chi 2 = 5.3).

CONCLUSIONS

These results indicate that TDCF is useful in guiding patient selection and operative treatment of ischemic MR and that in such patients, intraoperative TDCF should be performed routinely.

Impact of impinging wall jet on color Doppler quantification of mitral regurgitation

BACKGROUND

In clinical color Doppler examinations, mitral regurgitant jets are often observed to impinge on the left atrial wall immediately beyond the mitral valve. In accordance with fluid dynamics theory, we hypothesized that a jet impinging on a wall would lose momentum more rapidly, undergo spatial distortion, and thus have a different observed jet area from that of a free jet with an identical flow rate.

METHODS AND RESULTS

To test this hypothesis in vivo, we studied 44 patients with mitral regurgitation--30 with centrally directed free jets and 14 with eccentrically directed impinging wall jets. Maximal color jet areas (cm2) (with and without correction for left atrial size) were correlated with mitral regurgitant volumes, flow rates, and fractions derived from pulsed Doppler mitral and aortic forward flows. The groups were compared by analysis of covariance. Mean +/- SD mitral regurgitant fraction, regurgitant volume, and mean flow rate averaged 37 +/- 17%, 3.06 +/- 2.65 l/min, and 147 +/- 118 ml/sec, respectively. The maximal jet area from color Doppler imaging correlated relatively well with the mitral regurgitant fraction in the patients with free mitral regurgitant jets (r = 0.74, p less than 0.0001) but poorly in the patients with impinging wall jets (r = 0.42, p = NS). Although the mitral regurgitant fraction was larger (p less than 0.05) in patients with wall jets (44 +/- 20%) than in those with free jets (33 +/- 15%), the maximal jet area was significantly smaller (4.78 +/- 2.87 cm2 for wall jets versus 9.17 +/- 6.45 cm2 for free jets, p less than 0.01). For the same regurgitant fraction, wall jets were only approximately 40% of the size of a corresponding free jet, a difference confirmed by analysis of covariance (p less than 0.0001).

CONCLUSIONS

Patients with mitral regurgitation frequently have jets that impinge on the left atrial wall close to the mitral valve. Such impinging wall jets are less predictable and usually have much smaller color Doppler areas in conventional echocardiographic views than do free jets of similar regurgitant severity. Jet morphology should be considered in the semiquantitative interpretation of mitral regurgitation by Doppler color flow mapping. Future studies of the three-dimensional morphology of wall jets may aid in their assessment.

Detection and quantification of aortic regurgitation during aortic valvuloplasty

The degree of aortic regurgitation, before and after balloon aortic valvuloplasty, was assessed in 32 patients, using double indicator dilution curves: a) the forward curve was obtained by dye injection into the left ventricle and sampling in the aorta; b) the regurgitant curve was obtained by dye injection in the aorta and sampling in the left ventricle. A regurgitant index (RI) was calculated by obtaining the ratio of the areas of the triangles from regurgitant and forward curves. Eight-five percent of the patients were 70 years or older. After valvuloplasty, aortic valve area increased from 0.5 +/- 0.3 cm2 to 0.7 +/- 0.3 cm2 (P = .0002) while left ventricular to aortic gradient decreased from 77 +/- 32 to 51 +/- 24 (P = .0001). RI did not significantly change in 58% of patients, increased in 25%, and decreased in 15.2%. We conclude that in most patients undergoing aortic valvuloplasty, regurgitation does not change after the procedure. In some patients it may increase significantly, and in a few it may even decrease. Indicator dilution curves technique seems to provide a sensitive, accurate, and reproducible method to detect and quantify aortic incompetence before and after valvuloplasty.

Current management of mitral valve incompetence associated with coronary artery disease

At a time when hospital mortality for adult cardiac operations is continuing to fall, the combined mitral valve coronary bypass subset remains at relatively high risk. Efforts to improve results should be directed toward a more general application of mitral reconstruction in this population, tailoring the type of repair to the pathological anatomy of valve dysfunction. Other promising therapeutic measures include the liberal use of reperfusion therapy in the acute papillary muscle dysfunction group, better selection patients for operation, and perhaps operative recommendation to a greater proportion of the more stable patients that previously were treated medically. Finally increasing the general awareness of this problem should hasten the development of improved management strategies.

Assessment of the severity of mitral regurgitation from the dynamics of retrograde flow

Sixty four consecutive patients with isolated mitral regurgitation referred for Doppler echocardiography were divided into three groups: group 1, 20 patients with severe mitral regurgitation that required operation; group 2, 22 patients with severe left ventricular dysfunction and secondary mitral regurgitation; and group 3, 22 patients with mild to moderate mitral regurgitation that did not require valve operation. M mode and continuous wave Doppler traces with a simultaneous electrocardiogram and phonocardiogram were analysed to identify time intervals that could be used to distinguish patients who needed valve operation from those who did not. An interval of less than 55 ms between the aortic component of the second heart sound (A2) and the cessation of mitral retrograde flow was a powerful predictor that the patient required operation (sensitivity 100% and specificity 86%). The mean (SD) value of this variable in group 1 (40(15) ms) was significantly lower than in group 2 (90(35)ms) and group 3 (75(20)ms). Mean isovolumic relaxation time was less than normal in group 1 but did not differ significantly between groups. Deceleration of regurgitant velocity at end ejection was greater in group 1. The pressure drop from the left ventricle to the left atrium at A2 of less than 50% of the peak gradient also identified patients who needed valve operation (sensitivity 75% and specificity 68%). These findings may help to identify patients who require operation. They suggest that there are significant differences in the dynamics of flow velocities in patients with mitral regurgitation, possibly related to the relative resistances to retrograde and anterograde and anterograde flow.

Determination of regurgitant fraction in isolated mitral or aortic regurgitation by pulsed Doppler two-dimensional echocardiography

Measurements of mitral and aortic valve flows were obtained with two-dimensional Doppler echocardiography in 25 patients with isolated mitral (n = 19) or aortic (n = 6) regurgitation and regurgitant fraction was calculated as the difference between the two flows divided by the flow through the regurgitant valve. Results were compared with measurements of regurgitant fraction determined by combined left ventricular angiography and thermodilution. Regurgitant fraction averaged 56 +/- 18% (range 19 to 79) by Doppler echocardiography and 48 +/- 17% (range 13 to 72) by angiography. A significant correlation was observed between the two methods (r = 0.91; SEE = 7%). In contrast, no significant correlation was found between regurgitant fraction measured by either method and the angiographic 1+ to 4+ qualitative classification of regurgitation. Doppler echocardiography appears to be an accurate method for the non-invasive quantification of severity of regurgitation in isolated left-sided valve lesions.