Doppler echocardiographic assessment of the valve area in patients with atrioventricular valve stenosis by application of the continuity equation

The orifice area was non-invasively assessed in 19 patients with mitral or mitral and tricuspid stenosis by combined cross-sectional and Doppler echocardiography. Stroke volume was calculated as the product of aortic or pulmonic cross-sectional area and the time velocity integral of the flow across that valve, and the stenotic valve area was obtained as the stroke volume divided by the time velocity integral of the stenotic valve. In addition, the mitral valve area was estimated by the pressure half-time method of Hatle et al. The non-invasive determinations were compared with those calculated by the Gorlin formula at cardiac catheterization. The valve area obtained by combined cross-sectional and Doppler echocardiography showed a close correlation with the Gorlin area, r = 0.90, SEE = 0.13 cm2, n = 20. In contrast, the valve area estimated by the pressure half-time method showed only a moderate correlation with the Gorlin area, r = 0.68, SEE = 0.38 cm2, n = 18, and estimates by this method tended to significantly overestimate the Gorlin area. In conclusion, non-invasive valve area determinations based on combined cross-sectional and Doppler echocardiography can be used to accurately quantify the severity of the lesion in patients with atrioventricular valve stenosis, while determinations by the pressure half-time method may show errors of a magnitude that limits its clinical applicability.     

Quantification of aortic regurgitation utilizing continuous wave Doppler ultrasound

Aortic regurgitation and mitral stenosis are hemodynamically similar, insofar as both result in passive ventricular filling across a narrow orifice driven by a declining pressure gradient. Because mitral stenosis is successfully characterized by Doppler ultrasound determination of the velocity half-time, or time constant, aortic regurgitation might be quantified in an analogous fashion. Eighty-six patients with diverse causes of aortic regurgitation underwent continuous wave Doppler examination before cardiac catheterization or urgent aortic valve replacement. The Doppler velocity half-time was defined as the time required for the diastolic aortic regurgitation velocity profile to decay by 29%, whereas catheterization pressure half-time was calculated as the time required for transvalvular pressure to decay by 50%. Doppler velocity and catheterization pressure half-times were linearly related (r = 0.91). Doppler velocity half-times were inversely related to regurgitant fraction (r = -0.88). Angiographic severity (1+ = mild to 4+ = severe) was also inversely related to pressure and velocity half-time; a Doppler half-time threshold of 400 ms separated mild (1+, 2+) from significant (3+, 4+) aortic regurgitation with high specificity (0.92) and predictive value (0.90). The Doppler velocity half-time was independent of pulse pressure, mean arterial pressure, ejection fraction and left ventricular end-diastolic pressure. Estimation of transvalvular aortic pressure half-time utilizing continuous wave Doppler ultrasound is a reliable and accurate method for the noninvasive evaluation of the severity of aortic regurgitation.     

Reproducibility of Doppler echocardiographic quantification of aortic and mitral valve stenoses: comparison between two echocardiography centers

Doppler echocardiography has been widely used as a noninvasive method to quantify valvular heart diseases. This study assessed the variability between 2 echocardiography centers concerning 2-dimensional and Doppler echocardiographic results in the quantification of mitral and aortic valve stenoses. Forty-two patients were studied by 2 different echocardiography centers in a blinded, independent fashion. In patients with aortic and mitral valve stenosis, mean and maximal flow velocities were measured. The aortic valve orifice area was calculated according to the continuity equation. Mitral valve orifice area was determined by direct planimetry and by pressure half-time. In patients with an aortic valve stenosis, a close relation between the 2 centers was found for the maximal and mean flow velocities (coefficient of correlation, r = 0.72 to 0.92; coefficient of variation, 3.7 to 7.7%). A close correlation and a small observer variability was found for the flow velocity ratio determined by flow velocities measured in the left ventricular outflow tract and over the stenotic valve (r = 0.88; coefficient of variation, 0.01 +/- 0.009). In contrast, there was a poor correlation between the diameter of the left ventricular outflow tract and the aortic orifice area (r = 0.36 and 0.59, respectively). In patients with a mitral valve stenosis, mean and maximal velocities were closely correlated (r = 0.85 and 0.77, respectively). Velocities were not found to be significantly different between the 2 centers. Variability between the 2 centers for the mitral valve orifice area was 9.8% (2-dimensional echocardiography) and 5.7% (pressure half-time).(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler echocardiography determination of the severity of tricuspid valve stenosis

To evaluate the diagnostic usefulness of Doppler echocardiography for assessment of tricuspid stenosis, data of eleven patients were compared with hemodynamic results. Using the pressure half-time method, stenotic tricuspid orifice area was calculated as the quotient of 220 divided by the pressure half-time. The pressure gradient across the stenotic valve was determined according to the modified Bernoulli equation using four times the square of the maximal velocity of the stenotic jet. A close correlation was found between the Doppler echocardiographically and invasively determined orifice areas (r = 0.97, SEE = 0.23 cm2). There was also a good linear relationship between the pressure gradients derived from both methods (r = 0.89, SEE = 1 mmHg). Thus, the assessment of tricuspid stenosis can be achieved reliably by noninvasive means with the aid of Doppler echocardiography.     

Noninvasive assessment of valve lesions with Doppler ultrasound

Noninvasive assessment of valvular lesions with Doppler echocardiography is based on determination of velocities of blood flow in the region of cardiac valves, adjacent cardiac chambers and in the large vessels. Obstructions lead to an increase in the velocity of flow in the region of the stenosis which can be registered with the Doppler technique. Through application of the Bernoulli equation, from the maximal velocity, the pressure gradient across the stenotic valve can be calculated. Additionally, the severity of the stenosis is reflected in the temporal course of the velocity curve of the jet through the stenosed valve. For this purpose, in mitral stenosis, the pressure half-time is employed and, in aortic stenosis, the peak of the velocity curve during systole is used. The severity of tricuspid and pulmonic stenosis can also be classified with a method analogous to that used in obstruction of the left heart. The diagnosis of valvular incompetence is based on the detection of regurgitant flow. The extent of regurgitant flow into the proximal cardiac chamber enables semiquantitative classification of severity. The intensity of the jet through the incompetent valve is also indicative of the size of the regurgitant volume. Similar to that in obstructive lesions, the temporal course of the velocity curve is also related to the severity. In association with high-grade regurgitant lesions, there is a premature decrease in the velocity curve. Additionally, the severity of aortic regurgitation can be assessed on the basis of the extent of regurgitant flow in the descending aorta or the subclavian arteries.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of valvular heart disease by Doppler echocardiography

Doppler echocardiography provides direct hemodynamic data that are often complementary to those demonstrated by M-mode and two-dimensional echocardiographic imaging. This relatively new noninvasive technique has a number of important uses in patients with valvular heart disease. In both adults and children, Doppler measures of peak flow velocity through a stenotic valve allow accurate prediction of the pressure gradient across the valve, and the technique has particular promise for screening patients with suspected aortic or pulmonic stenosis. In patients with mitral stenosis but parasternal short-axis images of limited quality, Doppler velocity measures can provide novel data about the pressure gradient and mitral orifice area. Doppler techniques can also provide direct evidence for or against the presence of valvular regurgitation, and several approaches allow clinically useful estimation of the extent of aortic, mitral, or tricuspid regurgitation. In patients with known disease of one cardiac valve, Doppler is accurate for evaluating the integrity of a second valve. Finally, Doppler techniques have great promise for defining the nature, and perhaps the severity, of suspected prosthetic valve malfunction. Hence, we believe that Doppler echocardiography should become a routine part of the noninvasive evaluation of patients with known or suspected valvular heart disease.     

Application of Doppler color flow imaging to determine valve area in mitral stenosis.

This study was undertaken to examine whether Doppler color flow imaging could accurately estimate the valve area in mitral stenosis. Doppler color flow assessments were performed in both an in vitro model and in 30 patients with mitral stenosis undergoing cardiac catheterization. In the experimental Doppler study using a circuit model, color jet width correlated well with actual orifice diameter (r = 0.99). In the clinical Doppler study, the mitral valve orifice was assumed to be elliptic and the mitral valve area was calculated from the following equation: (pi/4) (a x b), where a = color jet width at the mitral valve orifice in the apical long-axis view (short diameter) and b = the width in the 90 degrees rotated view (long diameter). Mitral valve area was also determined by two-dimensional echocardiography and the pressure half-time method, and the results for all three noninvasive methods were compared with those obtained at cardiac catheterization. By Doppler color flow imaging, mitral valve area could be determined in all patients and there was a significant correlation between the Doppler jet and catheterization estimates of mitral valve area (r = 0.93). Valve area determined by two-dimensional echocardiography correlated well with catheterization measurements in 26 patients (r = 0.84). However, the area could not be determined in 4 (13%) of the 30 patients because of technical problems. Although there was a fair correlation between the valve area determined by the pressure half-time method and catheterization (r = 0.79), this method tended to overestimate valve area in patients with aortic regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler echographic evaluation of mitral valve stenosis with atrial fibrillation. Construction of a nomogram]

Doppler echocardiographic evaluation of mitral stenosis is often difficult in patients with atrial fibrillation. Sixteen patients were examined by transthoracic Doppler echocardiography and the relation between the variations in transmitral end diastolic pressure gradient and the length of the corresponding cardiac cycles was analysed. Mitral valve surface area (1.65 +/- 0.73 cm2) was determined by the pressure half-time method. The end diastolic transmitral pressure gradient was calculated from the simplified Bernouilli formula applied to end diastolic mitral flow velocity. In each patient, a linear relationship was observed between the end diastolic mitral gradient and the corresponding RR interval. The slope and intercept of the graph correlated significantly to mitral valve surface area (r = 0.72, p < 0.002 and r = 0.93, p < 0.00001, respectively). Using regression equations describing these correlations, it has been possible to construct a nomogramme indicating mitral valve surface area as a function of mitral end diastolic pressure gradient and the duration of the corresponding RR cycle. This nomogramme facilitates Doppler evaluation of mitral stenosis in atrial fibrillation.     

Doppler echocardiography determination of the pressure gradient and valve orifice area in mitral valve stenosis

Pressure gradient and orifice area of stenosed mitral valves can be determined with Doppler echocardiography using the modified Bernoulli equation and the pressure half-time method, respectively (Figures 1 and 2). There was a close linear correlation between Doppler-echocardiographically determined pressure gradients and valve orifice areas with those obtained by invasive methods. In this study, in 85 patients with mitral stenosis of various severity, the valve orifice areas, as derived by the two methods respectively, correlated well (y = 0.89x + 0.15) with a correlation coefficient r = 0.96 and standard error of the estimate SEE = 0.12 cm2 (Figure 3). The correlation was not influenced by the prevailing cardiac rhythm, ventricular function, left ventricular mass or coexistent mitral or aortic regurgitation (Table 1). Accordingly, the Doppler echocardiographic method also appears applicable in the presence of concomitant mitral and aortic regurgitation which precludes an exact determination of valve orifice area with invasive methods. The Doppler echocardiographic method is currently so well validated that it can be regarded as a reliable noninvasive procedure for determination of the severity of mitral stenosis.     

Doppler sonographic determination of the degree of severity of mitral valve stenoses

Using combined two-dimensional echocardiography and Doppler technique in 30 patients with pure mitral valve stenosis or combined valve disease with prevailing mitral stenosis, the mitral valve area and diastolic pressure gradient were determined, and compared to the invasively recorded values obtained during heart catheterization. Four patients were examined by Doppler ultrasound before and after mitral valve replacement. The determination of the mitral valve area was performed 1) invasively by means of the formula derived by Gorlin (and measured between 0.5 and 2.9 cm2), 2) by means of planimetry by integration of the two-dimensional echo in the short-axis view (between 0.7 and 2.8 cm2), and 3) by Doppler ultrasound based on the formula 220/t1/2, whereby the pressure half-time was obtained by dividing maximum flow velocity by square root 2. Here, the mitral valve area was between 0.5 and 2.8 cm2. The correlation between values obtained invasively and by means of Doppler ultrasound was good (r = 0.86), and compared well to the correlation between two-dimensional echocardiography and heart catheterization (r = 0.88). The best correlation of r = 0.89 was found between the mitral valve areas obtained by Doppler ultrasound and two-dimensional echocardiography. The diastolic pressure gradient was calculated by means of the formula derived from the Bernoulli equation, which is: delta P = 4Vmax2, whereby Vmax equals the maximum transmitral flow velocity. The invasively measured pressure gradients were between 2 and 30 mm Hg, the values obtained by Doppler ultrasound were between 6 and 29 mm Hg.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of aortic regurgitation on the assessment of mitral valve orifice area by Doppler pressure half-time in mitral stenosis

Evaluation of the severity of mitral stenosis by continuous-wave Doppler pressure half-time measurement is now well established. However, few data exist regarding the effect of aortic regurgitation (AR) on the validity of this method. Therefore, 73 patients were studied in whom cardiac catheterization and Doppler echocardiographic examinations were performed. Mitral valve orifice area was determined by the Gorlin equation, 2-dimensional echocardiography and Doppler pressure half-time. Doppler pressure half-time and catheterization estimates of mitral valve area correlated well (r = 0.85) in patients without significant mitral regurgitation. This correlation was maintained in patient subgroups with and without significant (at least 2+) AR (r = 0.86 and 0.83, respectively). Similarly, Doppler and 2-dimensional echocardiographic assessment of mitral valve area showed a strong correlation (r = 0.84). Again, the correlation between the 2 methods was similar in patients with and without significant AR (r = 0.86 and 0.82, respectively). Thus, Doppler pressure half-time estimates of mitral valve orifice area are accurate even in patients with AR.     

Assessment of valvular lesions with M-mode, two-dimensional and Doppler echocardiography

M-mode, two-dimensional and Doppler echocardiography enable evaluation of morphologic changes in valvular structures, detection of secondary changes in cardiac chambers and left ventricular function and quantification of blood flow patterns. In mitral stenosis, with M-mode echocardiography the diagnosis can be established on the basis of defined criteria, two-dimensional echocardiography enables planimetric calculation of the orifice area and Doppler echocardiography allows determination of the transvalvular pressure gradient and estimation of orifice area as well as detection of concomitant lesions. In mitral regurgitation, M-mode and two-dimensional echocardiography are less sensitive in its detection but they may be useful in delineating the etiology and whether the disease is of acute onset or chronic; the severity can only be judged indirectly on the basis of chamber dimensions. Doppler techniques render extremely sensitive and specific detection of mitral regurgitation as well as a means of quantifying severity. In this lesion, echocardiographic parameters have proven useful in the timing of valve replacement through early detection of myocardial dysfunction. In aortic regurgitation, M-mode and two-dimensional echocardiography may be useful in establishing the diagnosis, etiology, duration and, through assessment of dimensions and motion, estimating the severity as well. Doppler echocardiography is extremely sensitive and specific in the detection of aortic regurgitation and, additionally, provides a quantitative means for evaluation of severity. In aortic stenosis, both M-mode and two-dimensional echocardiography are sensitive in detection of changes in valve structure and motion but these methods are not capable of rendering reliable quantification of severity. Doppler techniques readily identify aortic stenosis and render, in addition, a close estimation of the transvalvular pressure gradient.     

Noninvasive assessment of an aortic bioprosthesis malfunction with Doppler echocardiography

A 27-year-old patient with aortic stenosis received a Carpentier Edwards bioprosthesis and a reconstruction of the mitral valve, in 1978. With auscultation, M-mode and two-dimensional echocardiography, we diagnosed in 1985 a malfunction of the aortic prosthesis with restenosis, insufficiency and mitral insufficiency. A reliable qualitative and quantitative non-invasive assessment, however, was only possible with Doppler echocardiography. The velocity of blood flow over the aortic valve was measured with the continuous-wave Doppler technique; the aortic valve pressure gradient and the valve area were determined. The pulsed Doppler allowed a semi-quantitative evaluation of the severity of the aortic and mitral insufficiency. The intraoperative and pathological anatomical results confirmed the results from Doppler echocardiography: aortic valve prosthesis malfunction with restenosis and insufficiency and mild haemodynamically insignificant mitral valve insufficiency. The need for cardiac catheterization in patients with valvular heart disease and prosthesis is discussed.     

Comparison of hemodynamic pressure half-time method and Gorlin formula with Doppler and echocardiographic determinations of mitral valve area in patients with combined mitral stenosis and regurgitation

Mitral valve area determined by the Gorlin formula in patients with combined mitral stenosis and regurgitation underestimates the true orifice size. Recent data suggest Doppler ultrasound and two-dimensional echocardiography more accurately estimate the mitral valve area in patients with mixed mitral valvular disease. This study assessed the accuracy of an alternate method, the hemodynamic pressure half-time method, for mitral valve area determination in such patients. In 22 patients, 28 separate mitral valve areas were calculated by the hemodynamic pressure half-time method, the Gorlin formula, and the Gorlin formula corrected for mitral regurgitation, and were compared with results calculated by the Doppler pressure half-time method. Six patients were studied both before and after balloon mitral valvuloplasty. In addition, mitral valve areas calculated by all four methods were compared with results obtained by planimetry in 15 patients with technically optimal echocardiograms. The mitral valve areas determined by hemodynamic pressure half-time corretated closely with the valve areas determined by Doppler (r = 0.90), whereas mitral valve areas determined by the Gorlin formula (both without and with correction for mitral regurgitation) did not correlate as well with the Doppler-estimated valve areas (r = 0.47 and r = 0.56, respectively). Correlation between the Doppler-derived mitral valve areas and the planimetered valve areas was also good (r = 0.84), as was that between the mitral valve areas calculated by hemodynamic pressure half-time and those calculated by planimetry (r = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)     

Noninvasive assessment of atrioventricular pressure half-time by Doppler ultrasound.

The mean pressure drop across the mitral valve and atrioventricular pressure half-time were measured noninvasively by Doppler ultrasound in 40 normal subjects, in 17 patients with mitral regurgitation, 32 patients with mitral stenosis and 12 with combined stenosis and regurgitation. In normal subjects pressure half-times were 20--60 msec, in patients with isolated mitral regurgitation 35--80 msec and in patients with mitral stenosis 90--383 msec. There was no significant change in pressure half-time with exercise or on repeat examinations, indicating relative independence of mitral flow. In 25 patients with mitral stenosis and seven with combined stenosis and regurgitation, pressure half-time was related to mitral valve area calculated from catheterization data. Increasing pressure half-times occurred with decreasing mitral valve area, and this relationship was not influenced by additional mitral regurgitation. Noninvasive measurement of pressure half-time together with mean pressure drop was useful for evaluating patients with mitral valve disease.     

Doppler echocardiography in the evaluation of valvular heart disease

Doppler echocardiography is a relatively new non-invasive technique which provides direct hemodynamic data that is complementary to M-Mode and 2-Dimensional echocardiography. This technique allows measurement of peak flow velocity through a stenotic valve and allows accurate prediction of the pressure gradient across the valve. It is a promising technique for screening patients with suspected pulmonic and aortic stenosis. It allows quantitation of gradient and valve area in patients with mitral stenosis. Doppler techniques are also valuable in detecting and semi-quantitating valvular regurgitation. Pulsed Doppler echocardiography is accurate in evaluating patients with multi-valvular disease. Finally, Doppler techniques are finding an important role in the evaluation of suspected prosthetic valve malfunction. In summary, Doppler echocardiography offers a complementary approach for direct evaluation of intracardiac hemodynamics in patients with valvular heart disease.     

Comparison of two-dimensional and Doppler echocardiography and intracardiac hemodynamics for quantification of mitral stenosis

Forty-three patients with mitral stenosis (MS) were studied to assess the relation of catheter-derived pressure gradient half-time (P 1/2), mitral valve areas (calculated by the Gorlin formula and 2-dimensional echocardiography [2-D echo]) to mitral valve areas derived from Doppler pressure half-time (T 1/2) in order to establish an accurate line-drawing method in nonlinear velocity tracings and to revalidate the use of the empiric constant of 220 ms as the T 1/2 that predicts a 1.0-cm2 mitral valve area. Mitral valve area could be quantified by 2-D echo in 39 of 43 patients and by Doppler in 31 of 34 patients, for a success rate of 91%. A reliable technique for measuring Doppler T 1/2 in nonlinear Doppler velocity tracings was a "mid-diastolic" line-drawing method, validated with the "anatomic" mitral valve area by 2-D echo (r = 0.89) and with the "hemodynamic" mitral valve area by the Gorlin formula (in pure MS without regurgitation) (r = 0.95). By both Doppler T 1/2 and hemodynamic P 1/2, the use of 220 ms to predict a mitral valve area of 1.0 cm2 was validated. Each T 1/2 and P 1/2 had an exponential inverse relation to the mitral valve area by the Gorlin formula in pure MS. Doppler and 2-D echocardiographic quantification of MS are complementary. Reliable measurement of T 1/2 in nonlinear velocity tracings is achieved by a mid-diastolic line-drawing method and use of the equation 220 ms/T 1/2 = mitral valve area accurately quantifies MS.     

Comparative accuracy of two-dimensional echocardiography and Doppler pressure half-time methods in assessing severity of mitral stenosis in patients with and without prior commissurotomy

This study was undertaken to compare the accuracies of the two-dimensional echocardiographic (2DE) and Doppler pressure half-time methods for the noninvasive estimation of cardiac catheterization measurements of mitral valve area in patients with pure mitral stenosis both with and without a previous commissurotomy. Data were retrospectively obtained from 74 consecutive patients who underwent cardiac catheterization within a 30 month period for evaluation of mitral stenosis, and who had two-dimensional echocardiograms performed before catheterization. Six patients (8.1%) had technically inadequate 2DE images and their data were excluded from analysis. Two of these patients had undergone commissurotomy, while the remaining four had not. Continuous-wave Doppler echocardiographic examinations were attempted in 45 patients and adequate measurements of pressure half-times were obtained in all patients studied. Mitral valve area by two-dimensional echocardiography was measured as the planimetered area along the inner border of the smallest mitral orifice visualized during short-axis scanning, while pressure half-time was calculated as the interval between the peak transmitral velocity and velocity/square root 2 as measured from the envelope of the Doppler spectral signal. Calculations from catheterization represented the minimal valve area at rest as derived from the Gorlin formula with the use of pressure gradients and thermodilution measurements of cardiac output. Thirty-seven of the patients had had a previous mitral commissurotomy a mean of 11.2 +/- 5.4 years before, while the remaining 37 patients were previously unoperated. Mean valve area as determined at catheterization for the total group of patients ranged from 0.37 to 2.30 cm2 (mean = 1.08 +/- 0.42 cm2).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of atrial fibrillation and mitral regurgitation on calculated mitral valve area in mitral stenosis

Forty-nine patients with mitral stenosis (MS) were studied by Doppler echocardiography and 2-dimensional (2-D) echocardiography to assess the ability of Doppler ultrasound to accurately measure mitral valve orifice area and to assess whether atrial fibrillation (AF) or mitral regurgitation (MR) affected the calculation. Twenty-four patients underwent cardiac catheterization. Mitral valve area by Doppler was determined by the pressure half-time method. Mean mitral valve area of all 49 patients by Doppler and 2-D echocardiography correlated well (r = 0.90). There was good correlation between Doppler and 2-D echocardiography in patients with pure MS in sinus rhythm (r = 0.88), in patients with MR (r = 0.93) and in patients with AF (r = 0.96). In the 7 patients with pure MS in sinus rhythm, there was good correlation between Doppler, 2-D echocardiography and cardiac catheterization (r = 0.95). In patients with either MR or AF, cardiac catheterization appeared to underestimate mitral valve orifice compared with both Doppler and 2-D echocardiography (p less than 0.05). Doppler echocardiography can estimate valve area in patients with MS regardless of the presence of MR or AF.     

Comparison of accuracy of mitral valve area in mitral stenosis by real-time, three-dimensional echocardiography versus two-dimensional echocardiography versus Doppler pressure half-time

Mitral valve area (MVA) in 30 patients with mitral stenosis (MS) and 34 normal controls was calculated by real-time, 3-dimensional echocardiography (RT3DE); MVA in patients with MS correlated well with the mitral area determined by 2-dimensional echocardiography (r = 0.98) and by pressure half-time (r = 0.90). MVA in normal controls on RT3DE correlated well with MVA on 2-dimensional echocardiography (r = 0.94) and pressure half-time (r = 0.91). There were significant differences between the orifice areas in patients with MS and normal controls. RT3DE can provide not only the anatomic structure of mitral valve apparatus, but also the optimal plane of the smallest mitral valve orifice, and can thus accurately measure the MVA.