Prediction of the severity of aortic stenosis by Doppler aortic valve area determination: prospective Doppler-catheterization correlation in 100 patients

Two-dimensional and Doppler echocardiography was performed prospectively in 100 patients with aortic stenosis who were undergoing clinically indicated cardiac catheterization. The purpose of this study procedure was to determine various Doppler variables predictive of the severity of aortic stenosis and to compare Doppler- and catheterization-derived aortic valve areas. Doppler-derived mean gradient correlated well with corresponding gradient by catheterization (r = 0.86). Peak Doppler aortic flow velocity greater than or equal to 4.5 m/s and Doppler-derived mean aortic gradient greater than or equal to 50 mm Hg were specific (93 and 94%, respectively) for severe aortic stenosis (defined as catheterization-derived aortic valve area less than or equal to 0.75 cm2) but were not sensitive (44 and 48%, respectively). Doppler-derived aortic valve area calculated by the continuity equation correlated well with catheterization-derived aortic valve area calculated by the Gorlin equation when either the time-velocity integral ratio (r = 0.83) or the peak flow velocity ratio (r = 0.80) between the left ventricular outflow tract and the aortic valve was used in the continuity equation. A velocity ratio of less than or equal to 0.25 alone was sensitive (92%) in detecting severe aortic stenosis. Therefore, use of various Doppler-derived values allows reliable noninvasive estimation of the severity of aortic stenosis.     

Noninvasive quantification and classification of the severity of aortic stenosis using Doppler echocardiography]

The exact determination of the severity of valvular heart disease represents the basis for the indication for surgery. Apart from the clinical findings, the estimation of the severity has, up to now, been based on the chest x-ray, the electrocardiogram, and the carotid pulse curve. By means of cardiac catheterization, the aortic valve gradient is determined and the aortic valve area is calculated using the Gorlin equation. Doppler echocardiography allows for a noninvasive gradient assessment. The peak and mean pressure gradients as well as the aortic valve area can be calculated. Echocardiography provides additional information about the severity of the left-ventricular hypertrophy, the heart size, as well as about secondary complications. Doppler echocardiography was performed in 95 patients to determine the peak pressure gradient. This Doppler-derived gradient correlated well with the catheterization-derived invasive gradient. The correlation coefficient was r = 0.81, for the mean gradient r = 0.77, and for the aortic valve area r = 0.87. Based on the classical determination of the severity of aortic stenosis by means of cardiac catheterization, a Doppler-derived mean pressure gradient > 54 mm Hg or a peak pressure gradient > 89 mm Hg and an aortic valve area > 0.7 cm2 are specific for severe aortic stenosis. A mean pressure gradient between 40 and 54 mm Hg or a peak pressure gradient of 67 and 89 mm Hg and an aortic valve area of 0.7 and 1.3 cm2 indicate moderately aortic stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prediction of severity of aortic stenosis: accuracy of multiple noninvasive parameters

PURPOSE: As newer non-medical techniques are developed to treat older patients with severe aortic stenosis, reliable noninvasive diagnosis of the condition will become increasingly important. For this reason, the accuracy of multiple noninvasive indexes for quantitation of the severity of aortic stenosis was evaluated, relative to catheterization-determined aortic valve area. PATIENTS AND METHODS: To evaluate the accuracy of multiple noninvasive parameters in assessing the presence and extent of aortic valve narrowing, noninvasive and catheterization correlations of the severity of aortic stenosis were obtained on 121 occasions in 81 patients (mean age, 76 +/- 11 years). Forty patients had studies performed before and after valvuloplasty. Noninvasive studies included the time to one-half carotid upstroke and carotid ejection time, corrected for heart rate, measured from a carotid pulse tracing; M-mode echocardiographic aortic valve excursion; mean pressure gradient across the aortic valve assessed by Doppler technique; the ratio of the peak to mean pressure gradient by Doppler; and Doppler aortic valve area assessed using the following continuity equation: aortic valve area = A X V/V1, where A = left ventricular outflow tract area, V = peak left ventricular outflow tract velocity, and V1 = peak velocity in the aortic stenotic jet. Mean aortic valve gradients and area (calculated using the Gorlin formula) were also assessed at cardiac catheterization. RESULTS: The correlations between the catheterization measurement of aortic valve area and the various noninvasive measurements were as follows: time to one-half carotid upstroke (r = -0.32, p less than 0.001); corrected left ventricular ejection time (r = -0.24, p less than 0.05); aortic valve excursion (r = 0.51, p less than 0.001); mean gradient by Doppler study (r = -0.44, p less than 0.001); mean gradient by catheterization analysis (r = -0.55, p less than 0.001); peak to mean gradient ratio measured by continuous wave Doppler (r = 0.38, p less than 0.001); and aortic valve area assessed using the Doppler continuity equation (r = 0.85, p less than 0.001). CONCLUSION: Noninvasive determination of aortic valve area using the continuity equation is an accurate means of assessing the severity of aortic stenosis. Although multiple other noninvasive parameters also correlate with aortic valve area measured at catheterization, there is too much scatter of data points to permit accurate prediction of catheterization aortic valve area in any given patient.     

Color-guided Doppler echocardiographic assessment of aortic valve stenosis

The severity of valvular aortic stenosis was assessed by Doppler color flow mapping in 100 consecutive patients who underwent successful cardiac catheterization within 2 weeks of the Doppler study. The maximal width of the aortic stenosis jet seen in 61 of these patients (Group A) was measured at the aortic valve. Color-guided continuous wave Doppler examination was used to measure the mean transaortic pressure gradient, and the aortic valve area was estimated using the simplified continuity equation. The aortic stenosis jet was not seen in 39 patients (Group B), and the mean pressure gradient and aortic valve area in these patients were assessed by conventional Doppler echocardiography alone. The mean pressure gradient obtained by continuous wave Doppler study and cardiac catheterization in the 61 Group A patients correlated well (r = 0.90); the correlation was lower in the 39 Group B patients (r = 0.70). The overall correlation for the combined Groups A and B was good (r = 0.82). The aortic valve area estimated by continuous wave Doppler study and cardiac catheterization in 54 Group A patients correlated well (r = 0.92); the correlation in 22 Group B patients was lower (r = 0.71). The correlation for all 76 patients (Groups A and B) was good (r = 0.80). The maximal aortic stenosis jet width also correlated well with the aortic valve area estimated at catheterization in 54 patients (r = 0.90). Group C represented an additional 14 patients in whom the left ventricle could not be entered during cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantitative evaluation of aortic stenosis using continuous wave Doppler

Thirteen patients with suspected aortic stenosis were studied with left-heart catheterization and 2 D, Doppler echocardiography. Thickness and abnormal motion of aortic valve was detected by 2 D Echo in 12 cases. One case had thick aortic valve with normal motion. The causes of lesions included rheumatic heart disease in one patient, bicuspid aortic valve in one, and senile calcific aortic valves in eleven. The left ventricular and aortic pressure were recorded simultaneously with left-heart catheterization. Peak-to-peak, instant peak and mean pressure gradients were measured. The aortic velocity was obtained with Continuous Wave (CW) Doppler. Instant peak and mean pressure gradients were calculated from Bernoulli equation. Both catheterization and Doppler demonstrated significant pressure gradient between LV and aorta in twelve patients. The instant peak and mean pressure gradients calculated from CW Doppler were compared with catheterization data. Doppler pressure gradients correlated well with that measured at catheterization: Doppler instant peak pressure gradient compared with that by catheterization, r = 0.89, P less than 0.001, Doppler instant peak pressure gradient compared with peak-to-peak pressure gradient by catheterization, r = 0.79, P less than 0.001, Doppler mean pressure gradient compared with that by catheterization, r = 0.75, P = 0.002. This study demonstrates that CW Doppler provides a valuable method for assessment of the severity of aortic stenosis.     

Doppler diagnosis of valvular aortic stenosis in patients over 60 years of age

Twenty-five consecutive elderly patients with suspected aortic stenosis underwent continuous-wave Doppler echocardiography followed by cardiac catheterization. Doppler-derived calculations of peak and mean aortic valve gradients were compared with catheterization-derived values of peak-to-peak, peak and mean gradients. The best correlation was found between Doppler- and catheterization-derived mean gradients (r = 0.89). A Doppler-derived measure of the timing of peak aortic flow velocity (modified time-to-peak velocity/modified left ventricular ejection time) successfully separated those with gradients above or below 50 mm Hg and also helped to avoid over- or underestimation of aortic valve gradients by Doppler.     

Noninvasive evaluation of aortic stenosis severity utilizing Doppler ultrasound and electrical bioimpedance

Aortic valve area was calculated noninvasively in 30 patients with aortic stenosis undergoing cardiac catheterization. Continuous wave Doppler ultrasound was employed to estimate the mean transvalvular pressure gradient. The mean left ventricular outflow tract flow velocity and cross-sectional area were determined from pulsed Doppler and two-dimensional ultrasound recordings. Electrical transthoracic bioimpedance cardiography performed simultaneously with the ultrasonic study and repeated at the time of catheterization measured heart rate, systolic ejection period and cardiac output. These noninvasive data permitted calculation of aortic valve area using the Gorlin equation (range 0.21 to 1.75 cm2) and the continuity equation (range 0.25 to 1.9 cm2). Subsequent cardiac catheterization showed valve area to range from 0.21 to 1.75 cm2. The mean Doppler pressure gradient estimate was highly predictive of the gradient measured at catheterization (r = +0.92, SEE = 10). Bioimpedance cardiac output measurements agreed with the average of Fick and indicator dye estimates (r = +0.90, SEE = 0.52). Valve area estimates utilizing continuous wave Doppler ultrasound and electrical bioimpedance were superior (r = +0.91, SEE = 0.12) to estimates obtained utilizing the continuity equation (r = +0.76, SEE = 0.29) and were more reliable in the detection of patients with severe aortic stenosis (9 of 11 versus 6 of 11). These data show that 1) electrical bioimpedance methods accurately estimate cardiac output in the presence of aortic stenosis; 2) the hybridized bioimpedance-Doppler ultrasound method yields accurate estimates of aortic stenosis area; and 3) the speed, accuracy and cost-effectiveness of aortic stenosis evaluation may be improved by this hybridized approach.     

Determination of the stenotic aortic valve area in adults using Doppler echocardiography

The severity of aortic stenosis was evaluated by Doppler echocardiography in 48 adults (mean age 67 years) undergoing cardiac catheterization. Maximal Doppler systolic gradient correlated with peak to peak pressure gradient (r = 0.79, y = 0.63x + 25.2 mm Hg) and mean Doppler gradient correlated with mean pressure gradient (r = 0.77, y = 0.59x + 10.0 mm Hg) by manometry. The transvalvular pressure gradient is flow dependent, however, and associated left ventricular dysfunction was common in our patients (33%). Thus, of the 32 patients with an aortic valve area less than or equal to 1.0 cm2 at catheterization, 6 (19%) had a peak Doppler gradient less than 50 mm Hg. To take into account the influence of volume flow, aortic valve area was calculated as stroke volume, measured simultaneously by thermodilution, divided by the Doppler systolic velocity integral in the aortic jet. Aortic valve areas calculated by this method were compared with results at catheterization in the total group (r = 0.71). Significant aortic insufficiency was present in 71% of the population. In the subgroup without significant coexisting aortic insufficiency, closer agreement of valve area with catheterization was noted (n = 14, r = 0.91, y = 0.83x + 0.24 cm2). Transaortic stroke volume can be determined noninvasively by Doppler echocardiographic measures in the left ventricular outflow tract, just proximal to the stenotic valve. Aortic valve area can then be calculated as left ventricular outflow tract cross-sectional area times the systolic velocity integral of outflow tract flow, divided by the systolic velocity integral in the aortic jet.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hemodynamic evaluation of porcine bioprostheses in the mitral position by doppler echocardiography

Twenty-four patients with porcine bioprostheses in the mitral position were studied by Doppler echocardiography followed by cardiac catheterization within 24 hours. Doppler mean diastolic mitral valve gradient was calculated by a 3-point method and mitral valve area was determined by the pressure half-time method. Data from Doppler echocardiography and cardiac catheterization were compared. There was a strong correlation between Doppler echocardiography and catheterization-determined mean diastolic gradient: r = 0.9, standard error of estimate (SEE) = 1.4 mm/Hg (regression equation y = 0.63x + 1.41), p <0.001. There was also a strong correlation between Doppler echocardiography and catheterization-determined mitral valve area: r = 0.86, SEE = 0.18 cm² (regression equation y = 0.64x + 0.52), p <0.001. Fourteen patients whose valvular function was considered normal by clinical evaluation had Doppler-calculated mean diastolic gradients of 4.5 to 9.5 mm Hg (mean 6.5 ± 1.4); the Doppler-determined valve area was 1.15 to 2.0 cm² (mean 1.54 ± 0.3). Ten patients had a malfunctioning bioprosthesis, 7 had severe mitral regurgitation and 3 had stenosis. Valvular malfunction in all 10 patients was detected by Doppler echocardiography and confirmed by catheterization and angiocardiography. Nine patients underwent reoperation. Doppler hemodynamic evaluation of porcine bioprostheses in the mitral position provided noninvasive information comparable to that obtained by cardiac catheterization.     

Continuous-wave Doppler echocardiographic assessment of severity of calcific aortic stenosis: a simultaneous Doppler-catheter correlative study in 100 adult patients

Studies of the correlation of aortic valve gradient determined by continuous-wave Doppler echocardiography and that determined at catheterization have, to date, involved young patients and nonsimultaneous measurements. We therefore obtained simultaneous Doppler echocardiographic and catheter measurements of pressure gradient in 100 consecutive adults (mean age 69, range 50 to 89 years). In 63 patients pressure measurements were obtained with dual-catheter techniques and in 37 they were obtained by withdrawal of the catheter from the left ventricle to the ascending aorta. Forty-six of these patients also underwent an outpatient Doppler study 7 days or less before catheterization. The simultaneous pressure waveforms and Doppler spectral velocity profiles were digitized at 10 msec intervals and maximum, mean, and instantaneous gradients (mm Hg) were derived for each. The correlation between the Doppler-determined gradient and the simultaneously measured maximum catheter gradient was r = .92 (SEE = 15 mm Hg), that between the Doppler-determined and mean catheter gradient was r = .93 (SEE = 10 mm Hg), and that between the Doppler and peak-to-peak catheter gradient was r = .91 (SEE = 14). The correlation between the nonsimultaneously Doppler-determined gradient and the maximum gradient measured by catheter was not as strong (r = .79, SEE = 24). The continuous-wave Doppler echocardiographic velocity profile represents the instantaneous transaortic pressure gradient throughout the cardiac cycle. The best correlation with continuous-wave Doppler-determined gradient was obtained with maximum and mean gradients measured by catheter. Continuous-wave Doppler echocardiography can be used to reliably predict the pressure gradient in adults with calcific aortic stenosis.     

Evaluation of aortic stenosis severity: role of contrast echocardiography in comparison with conventional echocardiography and cardiac catheterization.

OBJECTIVES: To evaluate the role of contrast Doppler echocardiography in the assessment of aortic stenosis severity, in comparison with the conventional method and using the catheterization study as the gold standard. STUDY DESIGN: Prospective comparative study. SETTING: Echocardiography Laboratory of Cardiology Department. POPULATION: We included 36 consecutive patients, 20 male, aged 67 +/- 11 years, referred for catheterization study to evaluate aortic stenosis severity. METHODS: All patients underwent conventional and contrast Doppler echocardiography and catheterization study. For contrast Doppler, we used Levovist (300 mg/ml infusion). We analyzed the following echocardiographic parameters: a) left ventricle dimensions, wall thickness and function; b) aortic valve morphology; c) post-stenotic aortic valve flow--peak velocity, velocity-time integral, peak gradient, mean gradient; d) left ventricle outflow tract flow--peak velocity, velocity-time integral; e) aortic valve functional area; f) acquisition time and Doppler signal intensity for post-stenotic aortic valve flow. Catheterization parameters analyzed: a) peak aortic valve gradient; b) mean aortic valve gradient. RESULTS: Contrast Doppler yielded higher peak gradients than conventional Doppler (85.6 +/- 30.2 vs 72.6 +/- 26.1 mmHg, p < 0.001), as well as higher mean gradients (51.4 +/- 19.0 vs 44.2 +/- 15.9 mmHg, p < 0.001). Peak gradients obtained with contrast Doppler correlated with those obtained invasively (r = 0.88, p < 0.001), although the values were higher (85.6 +/- 30.2 vs 73.6 +/- 32.0 mmHg, p < 0.001). There was no difference between mean contrast Doppler gradients and mean catheterization gradients, which showed a high correlation (r = 0.89, p < 0.001). There was no difference between peak and mean gradients obtained by conventional Doppler and invasively, which yielded correlations of 0.73 and 0.75, respectively (p < 0.001). The sensitivity of contrast Doppler for detection of severe aortic stenosis was 100% for peak gradient and 84% for mean gradient, while for conventional Doppler it was 68% and 58%. The specificity of contrast Doppler was 65% for peak gradient and 88% for mean gradient, while for conventional Doppler it was, respectively, 58% and 88%. Acquisition time for aortic flow visualization was lower (p < 0.001) and flow intensity higher for contrast Doppler, in comparison with conventional Doppler. CONCLUSIONS: In this study, contrast Doppler yielded high correlations with invasive data and higher sensitivity and specificity for detection of severe aortic stenosis than conventional Doppler. It is a useful method for evaluation of aortic stenosis severity.     

Clinical usefulness of intravenous albunex for the Doppler assessment of aortic stenosis

Optimal Doppler recordings of stenotic aortic flow are not always easy to obtain. Therefore, the present study investigated how useful intravenous Albunex injections were for improving the Doppler assessment of pressure gradients for aortic stenosis in 20 consecutive patients who underwent Doppler and left-heart catheterization studies within a 1-week period. Continuous-wave Doppler echocardiography was performed using both a 2.5 MHz duplex and a 1.9MHz independent transducer before and after Albunex injections. The maximum and mean pressure gradients were calculated from the highest Doppler velocity tracings using the simplified Bernoulli equation. Pullback catheterization pressure tracings from the left ventricle to the ascending aorta were superimposed for determination of the maximum instantaneous and mean pressure gradients. The Doppler-derived peak and mean pressure gradients showed significant underestimation compared with the catheterization gradients (23+/-17 mmHg and 11+/-7 mmHg, respectively). However, this underestimation disappeared with Albunex injection (-2+/-7 mmHg and -1+/-4mmHg, respectively). Although the Doppler-derived instantaneous and mean pressure gradients correlated well with the catheterization gradients (r=0.909 and r=0.879, respectively), they became much closer with Albunex (r=0.987 and r=0.963, respectively). The improvements in the Doppler-derived peak pressure gradients were significant from an apical window (n=12, 84-120mmHg, p<0.001). but less so from non-apical windows (n=8, 84-91 mmHg, p=0.0146). Accordingly, Albunex is most useful for Doppler recordings of stenotic aortic flow available from the apical window, but not less so from other acoustic windows.     

Quantification of left-side intracardiac pressures and gradients using mitral and aortic regurgitant velocities by simultaneous left and right catheterization and continuous-wave doppler echocardiography

Noninvasive determination of left-side intracardiac pressures is of clinical importance in many cardiac diseases. To test the reliability and accuracy of left-side intracardiac pressure measurements by continuous-wave Doppler echocardiography, using left-side valvular regurgitations, 47 patients with mitral regurgitation, with or without associated aortic regurgitation, underwent simultaneous Doppler and left and right catheterization. Doppler-derived left atrial and ventricular end-diastolic pressures were respectively estimated by subtracting mitral regurgitant gradient from systolic blood pressure and by diastolic blood pressure minus aortic regurgitant gradient. There were high correlations of mitral (r = 0.961) and aortic regurgitant gradients (r = 0.896) and of left atrial (r = 0.945) and ventricular end-diastolic pressures (r=0.854) between noninvasive and invasive measurements. Also, agreement analyses showed that there was close agreement between the two technical measurements for each parameter. The present study concluded that continuous-wave Doppler echocardiography provides a reliable and accurate method for the noninvasive evaluation of left-side intracardiac pressures and gradients in patients with mitral and aortic regurgitations.     

Pivotal role of aortic valve area calculation by the continuity equation for Doppler assessment of aortic stenosis in patients with combined aortic stenosis and regurgitation

Aortic regurgitation (AR) may result in overestimation of the aortic pressure gradient by continuous wave Doppler in patients with mixed aortic valve disease. However, few data are available regarding the effect of AR on noninvasive estimates of aortic valve area by the continuity equation. Therefore, 25 patients with angiographically documented severe AR and peak systolic aortic velocities of greater than 2.5 m/s were studied by continuous wave Doppler to determine the accuracy of pressure gradient and aortic valve area calculations in assessing the severity of aortic stenosis (AS) in this patient population. Peak instantaneous pressure gradient showed a general correlation to but was overestimated by Doppler (r = 0.78, Doppler = 0.70 catheter + 19.9) and did not predict aortic valve area. Mean pressure gradient by Doppler correlated more closely with catheter mean gradient (r = 0.86, Doppler = 0.79 catheter + 6.1) but was a poor predictor of the severity of AS. In contrast, the continuity equation accurately predicted the aortic valve area by catheterization (r = 0.92, Doppler = 0.89 catheter -0.08). Thus, the continuity equation provides a reliable estimate of aortic valve area in patients with severe AR and should be used to evaluate the extent of AS in such patients when high systolic aortic velocities are present.     

A reconsideration of Doppler assessed gradients in suspected aortic stenosis

To further define the clinical role of continuous wave Doppler echocardiography for determining aortic valve gradient, we studied 60 consecutive adult patients (age range 22 to 81 years, mean age 63) with suspected aortic stenosis within 24 hours of catheterization. Blind comparisons of Doppler peak and mean gradients by the simplified Bernoulli equation were made with catheterization peak-to-peak (r = 0.84), peak (r = 0.87) and mean (r = 0.84) gradients in a double-blind fashion. Despite these favorable correlations, Doppler peak gradient generally overestimated catheterization peak-to-peak gradient (1 to 53 mm Hg), making it impractical for clinical use. Doppler-catheterization correlations of peak and mean gradients were more favorable, with the least scatter noticed for mean gradient. The results of analysis of pooled data indicated that mean gradient may also be most specific for differentiating severe from less severe aortic stenosis. In this consecutive series where a full range of catheterization gradients was encountered, seven patients with predicted Doppler gradients were found to have none, which is best explained by the use of the simplified Bernoulli equation in patients with aortic insufficiency. These data indicate that prudence should be maintained when Doppler gradients alone are used for the assessment of aortic stenosis.     

Experimental validation of Doppler echocardiographic measurement of volume flow through the stenotic aortic valve

In aortic stenosis, evaluation of aortic valve area by the continuity equation assumes that the volume of flow through the stenotic valve can be measured accurately in the left ventricular outflow tract. To test the accuracy of Doppler volume-flow measurement proximal to a stenotic valve, we developed an open-chest canine model in which the native leaflets were sutured together to create variable degrees of acute aortic stenosis. Left ventricular and aortic pressures were measured with micromanometer-tipped catheters. Volume flow was controlled and varied by directing systemic venous return through a calibrated roller pump and back to the right atrium. Because transaortic volume flow will not equal roller pump output when there is coexisting aortic insufficiency (present in 67% of studies), transaortic flow was measured by electromagnetic flowmeter with the flow probe placed around the proximal descending thoracic aorta, just beyond the ligated arch vessels. In 12 adult, mongrel dogs (mean weight, 25 kg), the mean transaortic pressure gradient ranged from 2 to 74 mm Hg, and transaortic volume flow ranged from 0.9 to 3.2 l/min. In four dogs, electromagnetic flow that was measured distal to the valve was accurate compared with volume flow determined by timed collection of total aortic flow into a graduated cylinder (n = 24, r = 0.97, electromagnetic flow = 0.87 Direct +0.13 l/min). In eight subsequent dogs, electromagnetic flow was compared with transaortic cardiac output measured by Doppler echocardiography in the left ventricular outflow tract as circular cross-sectional area [pi(D/2)2] x left ventricular outflow tract velocity-time integral x heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)     

Accurate noninvasive quantification of stenotic aortic valve area by Doppler echocardiography

Laminar flow through a conduit is equal to the mean velocity times the cross-sectional area of the orifice. Therefore, volume is equal to the time-velocity integral multiplied by the cross-sectional area. In aortic stenosis, flow in the stenotic jet is laminar and the aortic valve area should be equal to the volume of blood ejected through the valve divided by the time-velocity integral of the aortic jet velocity recorded by continuous-wave Doppler echocardiography. To test whether this concept can be used to accurately determine aortic valve area noninvasively by the Doppler method, 39 patients (age 35 to 82 years, mean 63) underwent pulsed Doppler combined with two-dimensional echocardiography for measurement of stroke volume at the aortic, pulmonic, and mitral anulus as well as continuous-wave Doppler recording of the aortic jet. Aortic valve area determined at cardiac catheterization by the Gorlin equation ranged between 0.4 and 2.07 cm2 (mean 0.89 +/- 0.45). Doppler-derived valve area, determined with the stroke volume value from either the aortic, pulmonic, or mitral anulus, correlated well with the area determined at cardiac catheterization (r = .95, .97, and .96, respectively). A simplified method for measuring aortic valve area derived as the cross-sectional area of the aortic anulus times peak velocity just proximal to the aortic valve divided by peak aortic jet velocity correlated well with measurements obtained at cardiac catheterization (r = .94). An excellent separation between critical and noncritical aortic stenosis was seen using either one of the Doppler methods.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler evaluation of aortic valve area in children with aortic stenosis

To evaluate the usefulness of the Doppler-derived aortic valve area calculated from the continuity equation in assessing the hemodynamic severity of aortic valve stenosis in infants and children, two-dimensional and Doppler echocardiographic examinations were performed on 42 patients (aged 1 day to 24 years) a median of 1 day before or after cardiac catheterization. The left ventricular outflow tract diameter was measured from the parasternal long-axis view at the base of the aortic cusps from inner edge to inner edge in early systole. The flow velocities proximal to the aortic valve were measured from the apical view with use of pulsed Doppler echocardiography; the jet velocities were recorded from the apical, right parasternal and suprasternal views by using continuous wave Doppler echocardiography. The velocity-time integral, mean velocity and peak velocity were measured by tracing the Doppler waveforms along their outermost margins. Seventeen patients (all less than or equal to 6 years old) had a very small left ventricular outflow tract diameter (less than or equal to 1.4 cm) and cross-sectional area (less than or equal to 1.5 cm2). The Doppler aortic valve area calculated with use of velocity-time integrals in the continuity equation (0.57 +/- 0.25 cm2/m2, mean value +/- SD) correlated well with the Doppler aortic valve area calculated by using mean (0.55 +/- 0.25 cm2/m2) and peak (0.54 +/- 0.24 cm2/m2) velocities, with correlations of r = 0.97 and 0.95, respectively. Thirty-four patients had sufficient catheterization data to calculate aortic valve area from the Gorlin formula.(ABSTRACT TRUNCATED AT 250 WORDS)     

Doppler echocardiographic evaluation of aortic stenosis

Doppler echocardiography allows accurate noninvasive measurement of transaortic velocity and pressure gradient in patients with valvular aortic stenosis. Because pressure gradients vary with transaortic volume flow, calculation of aortic valve area with the continuity equation is essential for complete echocardiographic evaluation of adult patients. The physician and sonographer should be aware of potential technical and physiologic pitfalls in applying Doppler echocardiographic techniques to the evaluation of the adult with aortic stenosis. With proper training and experience, however, the needed data can be obtained reliably and reproducibly. Doppler evaluation of patients with aortic stenosis has improved our understanding of the prevalence and natural history of this disease. In addition, Doppler measures of stenosis severity can be used in a cost-effective manner for clinical decision making regarding the need for valve replacement in symptomatic adults. It now has supplanted the need for invasive measures of stenosis severity in many of these patients.     

Value of multiple echocardiographic views in the evaluation of aortic stenosis in adults by continuous-wave Doppler

Fifty-two adults referred for evaluation of aortic stenosis (AS) were studied using continuous-wave and pulsed Doppler echocardiography. Three windows were used to determine which approach (apical, right parasternal or suprasternal) yielded optimal results. Doppler-derived peak aortic valve gradients were compared with the peak gradients measured at cardiac catheterization in 23 patients. High-velocity jets were best recorded from the cardiac apex and less frequently from the right parasternal and suprasternal areas. However, gradients from the right parasternal area correlated best with cardiac catheterization findings, although recordings could be made from this window in only 49% of the patients. Velocities from the suprasternal window were significantly (p less than 0.01) lower than those from the apex or right parasternal areas. Gradient underestimation from the suprasternal window tended to increase with age of the patient (p less than 0.01). When the maximal Doppler derived gradient from any window was compared with catheterization measurements, the correlation coefficient was 0.86. Gradients derived from Doppler velocities accurately predicted severe (more than 50 mm Hg) gradients at catheterization. Thus, Doppler echocardiography is useful in evaluation of AS when several windows are used for optimal assessment of aortic valve gradient.