Two-dimensional transesophageal echocardiographic determination of aortic valve area in adults with aortic stenosis

To determine if aortic stenosis severity could be accurately measured by two-dimensional transesophageal echocardiography (TEE), 62 adult subjects (mean age 66 +/- 12 years) with aortic stenosis had their aortic valve area (AVA) determined by direct planimetry using TEE, and with the continuity equation using combined transthoracic Doppler and two-dimensional echocardiography (TTE). Eighteen subjects had AVA calculated by the Gorlin method during catheterization. An excellent correlation (r = 0.93, SEE = 0.17 cm2) was found between AVA determined by TEE (mean 1.24 +/- 0.49 cm2; range 0.40 to 2.26 cm2) and TTE (mean 1.23 +/- 0.46 cm2; range 0.40 to 2.23 cm2). The absolute (0.13 +/- 0.12 cm2) and percent (10.8 +/- 8.9%) differences between AVA determined by TEE versus TTE were small. Excellent correlations between AVA by TEE and TTE were also found in subjects with normal systolic function (r = 0.95, SEE = 0.14 cm2; n = 38) and impaired function (r = 0.91, SEE = 0.21 cm2; n = 24). AVA determined by catheterization correlated better with AVA measured by TEE (r = 0.91, SEE = 0.15 cm2) than AVA measured with TTE (r = 0.84, SEE = 0.19 cm2). These data demonstrate that AVA can be accurately measured by direct planimetry using TEE in subjects with aortic stenosis. TEE may become an important adjunct to transthoracic echocardiography in the assessment of aortic stenosis severity.     

Aortic Stenosis

Noninvasive assessment of aortic valve area by echocardiography has become the standard of practice over the past few years. The advent of transesophageal echocardiography (TEE) has provided a new method for the assessment of aortic valve area (AVA) using planimetry by two-dimensional imaging. Clear visualization of the anatomy of the valve, as well as accuracy of AVA assessment, makes TEE an invaluable tool for the evaluation of aortic valve stenosis. TEE is especially helpful in clinical settings when there is a discrepancy between the AVA obtained by transthoracic echocardiography and cardiac catheterization. TEE is particularly helpful in the assessment of the aortic valve during intraoperative echocardiography. This review discusses the techniques, imaging planes, and details for assessing AVA by TEE. The role of TEE in AVA assessment is described, with specific clinical case examples cited.     

Influence of ejection fraction and valvular regurgitation on the accuracy of aortic valve area determination

OBJECTIVE: To examine the influence of left ventricular dysfunction, aortic regurgitation, and mitral regurgitation on commonly used methods for aortic valve area (AVA) determination. BACKGROUND: Each method for AVA determination has its inherent limitations. METHODS: AVA determinations by transesophageal echocardiography (TEE) using planimetry, transthoracic echocardiography (TTE) with application of the continuity equation, and cardiac catheterization applying the Gorlin formula were performed in 74 patients with aortic stenosis. The severity of the aortic stenosis was defined by consensus of at least two methods. Over- or underestimation of AVA associated with ejection fraction, aortic regurgitation, mitral regurgitation, or severity of the aortic stenosis for each method in relation to the other two methods was assessed. RESULTS: Mean AVAs were 1.05 +/- 0.51 by TEE, 1.06 +/- 0.51 by TTE, and 1.08 +/- 0.53 by cardiac catheterization. An overestimation of the severity of the aortic stenosis by the Gorlin formula in patients with moderate-to-severe aortic regurgitation as compared to TEE-derived data was found (P = 0.014). A similar trend of overestimation by catheterization in comparison with the TTE data was found. In the context of moderate-to-severe mitral regurgitation, AVA determination by TTE overestimated the degree of aortic stenosis as compared to TEE (P = 0.011) and cardiac catheterization (P = 0.023). CONCLUSIONS: Overall mean AVA did not differ between methods, suggesting that these three methods are equally accurate in a nonselected clinical patient group. However, in the presence of significant aortic regurgitation, the two echocardiographic methods appear more accurate. Our observation of an overestimation of the severity of aortic stenosis by TTE in the presence of moderate-to-severe mitral regurgitation indicates that this possibility should be accounted for in clinical decisions based on TTE determinations of AVA.     

Comparison of accuracy of aortic valve area assessment in aortic stenosis by real time three-dimensional echocardiography in biplane mode versus two-dimensional transthoracic and transesophageal echocardiography

Our aim was to validate the clinical feasibility of assessment of the area of the aortic valve orifice (AVA) by real time three-dimensional echocardiography (RT3DE) in biplane mode by planimetry and to compare it with the echo-Doppler methods more commonly used to evaluate valvular aortic stenosis (AS).RT3DE in biplane mode is a novel technique that allows operators to visualize the aortic valve orifice anatomy in any desired plane orientation. Its usefulness and accuracy have not previously been established.Using this technique, we studied a series of patients with AS and compared the results with those obtained by two-dimensional transesophageal echocardiography (TEE) planimetry and two-dimensional transthoracic echocardiography using the continuity equation (TTE-CE). RT3DE planimetries in biplane mode were measured by two independent observers. Bland-Altman analysis was used to compare these two methods.Forty-one patients with AS were enrolled in the study (15 women, 26 men, mean age 73.5 +/- 8.2 years). RT3DE planimetry was feasible in 92.7%. Average AVA determined by TTE-CE was 0.76 +/- 0.20 cm, by TEE planimetry 0.73 +/- 0.1 cm, and by RT3DE planimetry 0.76 +/- 0.20 cm(2). The average differences in AVA were-0.001 +/- 0.254 cm(2) and 0.03 +/- 0.155 cm(2) (RT3DE/TEE). The correlation coefficient for AVA (RT3DE/TTE-CE) was 0.82 and for AVA (RT3DE/TEE) it was 0.94, P < 0.0001. No significant intra- and interobserver variability was observed. In conclusion, RT3DE in biplane mode provides a feasible and reproducible method for measuring the area of the aortic valve orifice in aortic stenosis.     

Magnetic resonance to assess the aortic valve area in aortic stenosis: how does it compare to current diagnostic standards?

OBJECTIVES: The purpose of the present study was to evaluate whether magnetic resonance (MR) planimetry of the aortic valve area (AVA) may prove to be a reliable, non-invasive diagnostic tool in the assessment of aortic valve stenosis, and how the results compare with current diagnostic standards.BACKGROUND: Current standard techniques for assessing the severity of aortic stenosis include transthoracic and transesophageal echocardiography (TEE) as well as transvalvular pressure measurements during cardiac catheterization. METHODS: Forty consecutive patients underwent cardiac catheterization, TEE, and MR. The AVA was estimated by direct planimetry (MR, TEE) or calculated indirectly via the peak systolic transvalvular gradient (catheter). Pressure gradients from cardiac catheterization and Doppler echocardiography were also compared. RESULTS: By MR, the mean AVA(max) was 0.91 +/- 0.25 cm(2); by TEE, AVA(max) was 0.89 +/- 0.28 cm(2); and by catheter, the AVA was calculated as 0.64 +/- 0.26 cm(2). Mean absolute differences in AVA were 0.02 cm(2) for MR versus TEE, 0.27 cm(2) for MR versus catheter, and 0.25 cm(2) for TEE versus catheter. Correlations for AVA(max) were r = 0.96 between MR and TEE, r = 0.47 between TEE and catheter, and r = 0.44 between MR and catheter. The correlation between Doppler and catheter gradients was r = 0.71. CONCLUSIONS: Magnetic resonance planimetry of the AVA correlates well with TEE and less well with the catheter-derived AVA. Invasive and Doppler pressure correlated less well than those obtained from planimetric techniques. Magnetic resonance planimetry of the AVA may provide an accurate, non-invasive, well-tolerated alternative to invasive techniques and transthoracic echocardiography in the assessment of aortic stenosis.     

Noninvasive determination of the valvar area in aortic valve disease by Doppler echocardiography and radionuclide angiography

To assess the severity of outlfow obstruction in patients with aortic valve disease, the aortic valvar area was noninvasively determined in 22 patients with isolated aortic stenosis or combined stenosis and regurgitation. The ejection time (ET), maximal velocity (Vmax), and systolic velocity integral (SVI) of the aortic flow was obtained by continuous wave Doppler ultrasound. Left ventricular stroke volume (SV) was determined by radionuclide angiography, using a counts-based nongeometric technique with individual attenuation correction. Aortic valve area (AVA) was calculated using a modified Gorlin formula; AVA = SV/(71.2 X ET X Vmax), and also by dividing the stroke volume by the systolic velocity integral; AVA = SV/SVI. The two noninvasive determinations correlated closely with the valve areas obtained by invasive measurements; r = 0.95, SEE = +/- 0.13 cm2 by the modified Gorlin formula, and r = 0.94, SEE = +/- 0.14 cm2 by the integration method. The two noninvasive calculations showed almost uniform results; r = 0.98, SEE = +/- 0.09 cm2. In conclusion, aortic valve area can be determined with reasonable accuracy by combining Doppler echocardiography and radionuclide angiography. This noninvasive approach may reduce the need for invasive measurements in patients with suspected aortic valve disease. In addition, radionuclide angiography provides important information about left ventricular function.     

Aortic valve area discrepancy by Gorlin equation and Doppler echocardiography continuity equation: relationship to flow in patients with valvular aortic stenosis

BACKGROUND: In vitro studies have shown a discrepancy between aortic valve area (AVA) measurements derived invasively by Gorlin equation (Gorlin AVA) and noninvasively by Doppler echocardiography (Doppler-echo) continuity equation (Doppler AVA) during low flow states. OBJECTIVE: To assess whether a flow-related discrepancy between Gorlin AVA and Doppler AVA occurs in the clinical setting in patients with isolated valvular aortic stenosis. PATIENTS AND METHODS: Seventy-five consecutive patients with isolated valvular aortic stenosis, who had AVA determined both invasively by Gorlin equation and noninvasively by Doppler-echo continuity equation, were retrospectively reviewed. RESULTS: Gorlin AVA and Doppler AVA correlated (r=0.68) over the narrow AVA range (Gorlin AVA 0.30 to 1.22 cm2); however, Doppler AVA was systematically larger than Gorlin AVA (0.80+/-0.21 versus 0.70+/-0.23 cm2, AVA difference = 0.10+/-0.17 cm2, P<0.0001). The AVA difference was inversely related to invasive cardiac index (r=-0.51) and was significantly greater at low flow states (cardiac index less than 2.5 L/min/m2) than at normal flow states (cardiac index 2.5 L/min/m2 or more) (0.16+/-0.15 versus -0.03+/-0.15 cm2, P<0.0001). Independent predictors of the AVA difference were the difference between Doppler-echo and invasive cardiac output (P<0.0001); the difference between Doppler-echo and invasive mean transvalvular pressure gradient (P=0.0002); and the average cardiac output (Doppler-echo plus invasive cardiac output/2, P=0.001) at the time of the hemodynamic assessments. The AVA difference was not related to average pressure gradient, average AVA or patient characteristics. CONCLUSIONS: A flow-related discrepancy between Gorlin AVA and Doppler AVA occurs in the clinical setting of patients with isolated valvular aortic stenosis. This discrepancy should be considered when assessing aortic stenosis severity during low flow states, where Gorlin AVA may be significantly smaller than Doppler AVA.     

Comparison of magnetic resonance imaging of aortic valve stenosis and aortic root to multimodality imaging for selection of transcatheter aortic valve implantation candidates

The purpose of the present study was to compare the aortic valve area, aortic valve annulus, and aortic root dimensions measured using magnetic resonance imaging (MRI) with catheterization, transthoracic echocardiography (TTE), and transesophageal echocardiography (TEE). An optimal prosthesis--aortic root match is an essential goal when evaluating patients for transcatheter aortic valve implantation. Comparisons between MRI and the other imaging techniques are rare and need validation. In 24 consecutive, high-risk, symptomatic patients with severe aortic stenosis, aortic valve area was prospectively determined using MRI and direct planimetry using three-dimensional TTE and calculated by catheterization using the Gorlin equation and by Doppler echocardiography using the continuity equation. Aortic valve annulus and the aortic root dimensions were prospectively measured using MRI, 2-dimensional TTE, and invasive aortography. In addition, aortic valve annulus was measured using TEE. No differences in aortic valve area were found among MRI, Doppler echocardiography, and 3-dimensional TTE compared with catheterization (p = NS). Invasive angiography underestimated aortic valve annulus compared with MRI (p <0.001), TEE (p <0.001), and 2-dimensional TTE (p <0.001). Two-dimensional TTE tended to underestimate the aortic valve annulus diameters compared to TEE and MRI. In contrast to 2-dimensional TTE, 3 patients had aortic valve annulus beyond the transcatheter aortic valve implantation range using TEE and MRI. In conclusion, MRI planimetry, Doppler, and 3-dimensional TTE provided an accurate estimate of the aortic valve area compared to catheterization. MRI and TEE provided similar and essential assessment of the aortic valve annulus dimensions, especially at the limits of the transcatheter aortic valve implantation range.     

Using Cardiac Magnetic Resonance Tomography for Assessment of Aortic Valve Area in Aortic Valve Stenosis

Calcified aortic valve stenosis (AS) is the most common valvular disease in the elderly population and constitutes a significant health and socioeconomic problem. Doppler echocardiography is the recommended diagnostic tool for the initial evaluation of AS. Transvalvular pressure gradients and aortic valve area have been used as quantitative parameters for grading the severity of AS, but the latter one is less susceptible to changes in flow dynamics and therefore considered the more independent and reliable parameter. The aortic valve area can be assessed directly by transesophageal echocardiography (TEE), which reflects the anatomic or geometric orifice area, or it can be calculated noninvasively by transthoracic echocardiography (TTE) using the continuity equation, or, invasively, by cardiac catheterization (CC) using the Gorlin formula, both reflecting the effective orifice area.Assessment of aortic valve area by TTE can be limited in some patients due to inadequate acoustic window. Similarly, TEE as a semi-invasive technique is not well tolerated by some patients and the planimetry is limited in patients with heavily calcified aortic valve leaflets. CC is an invasive procedure associated with a substantial risk of cerebral embolism and the Gorlin formula has been shown to be susceptible to changes in flow dynamics.Cardiac magnetic resonance tomography (CMR) is a new imaging technique capable of imaging the aortic valve with high resolution and has recently been used for assessment of the aortic valve area in AS. This review focuses on the feasibility of CMR for the assessment of aortic valve area in AS compared to current standard techniques and discusses some of the typical pitfalls and the sources for the discrepant results observed between the different techniques for assessment of the aortic valve area.     

Noninvasive quantification of the aortic valve area in aortic stenosis by Doppler echocardiography

To develop a noninvasive approach to the quantification of thestenotic aortic valve area, Doppler echocardiography and cardiaccatheterisation were performed in 24 patients with pure aorticstenosis. The transmitral volumetric flow was measured by Dopplerechocardiography and calculated as the product of the correctedmitral orifice area (CM A) and the diastolic velocity integral(DVI). The maximal aortic jet velocities were recorded by Dopplertechnique and integrated to obtain the systolic velocity integral(SVl). Assuming that the aortic and mitral volumetric flowsare equal, the aortic valve area (A VA) was calculated as: AVA= CM A x DVI/SVI. Mean pressure gradient and cardiac outputwere measured during catheterisation and the aortic valve areawas calculated by the Gorlin formula. Comparison between theaortic valve area determined by Doppler technique and catheterisationyielded a close correlation (r = 0.92, P<0.001), and therewas no significant difference between the two measurements.Good correlations of the instantaneous pressure gradient andthe stroke volume were also obtained between the two techniques(r = 0.91 and r = 0.90, respectively, P<0.001). These resultsdemonstrate that our Doppler echocardiographic method providesa promising approach to the noninvasive quantification of theaortic valve area in aortic stenosis     

Valve orifice area in aortic stenosis evaluated by planimetry, Gorlin and continuity equations: a prospective study.

In evaluation of the severity of aortic valve stenosis, multiple parameters can be determined. All of them, except valve orifice area, are influenced by other factors such as cardiac output, heart rate or aortic insufficiency. OBJECTIVES: This is a prospective study which proposes, in the determination of the valve orifice area in aortic stenosis, to evaluate the accuracy of and correlation between three methods--planimetry by multiplane transesophageal echocardiography, the continuity equation by transthoracic echocardiography, and invasive measurement using the Gorlin formula. METHODS: Forty-five patients with known calcified valvular aortic stenosis 27 men, mean age 70 +/- 10 years, (range 27-82), were studied. In all patients the area was determined by planimetry and by the continuity equation. In 25 (56%) patients invasive measurements were obtained using the Gorlin formula. RESULTS: Evaluation of the valve orifice area by planimetry was easily performed and did not prolong the duration of the exam, except in five patients (11%). The area determined by the continuity equation had a mean value of 0.74 +/- 0.25 cm2, by planimetry 0.74 +/- 0.24 cm2 and by the Gorlin formula 0.65 +/- 0.17 cm2. Correlations between areas obtained by the three methods used were: continuity equation and planimetry 0.82; continuity equation and Gorlin formula 0.51; and planimetry and Gorlin formula 0.80. Concordance analysis (Bland and Altman's method) gave mean (Mn) values for the differences in the areas determined by the Gorlin formula and the continuity equation of 0.01 +/- 0.15 cm2 (Mn - 2SD = -0.29, Mn + 2SD = 0.30). The estimated value by the Gorlin formula and planimetry was 0.02 +/- 0.10 (Mn - 2SD = -0.19, Mn + 2SD = 0.23). CONCLUSIONS: 1) Planimetry of the valve orifice area by transesophageal echocardiography is feasible and does not prolong the duration of the exam in the majority of patients. 2) The strong correlation and the results of concordance analysis, in the determination of valve orifice area, between traditional invasive methods and planimetry, support the use of this noninvasive method in clinical practice.     

Comparison of feasibility and accuracy of transthoracic echocardiography versus computed tomography in patients with known ascending aortic aneurysm

Aortic valve diseases, hypertension, and connective tissue disorders may be causes of ascending aortic aneurysms. Aortic enlargement monitoring is essential for surgical timing and for operative design. In this regard, several imaging techniques may have limitations: magnetic resonance is not widespread and is expensive, computed tomography uses radiation, and transesophageal echocardiography is a semi-invasive method. The aim of this study was to analyze the feasibility of transthoracic echocardiography in the evaluation of aortic dimensions and its accuracy in comparison with multidetector computed tomography. In 44 patients with known ascending aortic aneurysms, transthoracic echocardiographic and computed tomographic measurements were obtained and compared at different levels: the annulus, sinuses of Valsalva, sinotubular junction, ascending aorta, and aortic arch. Transthoracic echocardiographic diameters were obtained in all patients, apart from the aortic arch, which was measured in 40 cases. Transthoracic echocardiographic and computed tomographic diameters correlated significantly (p <0.001), with very small SEEs: for the annulus, r = 0.846 (SEE 0.37); for the sinuses of Valsalva, r = 0.967 (SEE 0.35); for the sinotubular junction, r = 0.965 (SEE 0.33); for the ascending aorta, r = 0.976 (SEE 0.41); and for the aortic arch, r = 0.87 (SEE 0.50). In conclusion, transthoracic echocardiography is a feasible and accurate technique for the assessment and follow-up of thoracic aortic diameters in patients with ascending aortic aneurysms.     

Factors affecting Doppler echocardiographic valve area assessment in aortic stenosis

Doppler echocardiographic assessment of the aortic valve area (AVA) using the continuity equation was performed before cardiac catheterization in 100 patients with suspected aortic stenosis. Doppler echocardiographic AVA correlated closely with AVA calculated by the Gorlin equation at catheterization (r = 0.96). However, Doppler echocardiography slightly but systematically underestimated the AVA (p less than 0.001) and did so most markedly in patients with mild stenosis (greater than 1.0 cm2). In multivariate analysis, the difference in AVA by the 2 techniques was positively associated with left ventricular (LV) stroke volume and inversely with the difference between mean catheterization and Doppler gradients, LV ejection fraction and LV outflow tract velocity. Furthermore, the AVA difference also was related to gender, being larger in women. Thus, overall Doppler echocardiography reliably assesses AVA, but the usefulness of the method is somewhat reduced by its underestimation of AVA in mild stenosis. This drawback, however, is usually overcome by taking patients' symptoms into account. Furthermore, lacking a "gold standard," this underestimation need not imply errors of the Doppler echocardiographic method alone, but also may reflect known inaccuracies of the catheterization technique.     

Contribution of the continuity equation for the assessment of mitral valve area in mitral stenosis]

The aim of this study was to evaluate the continuity equation in the quantification of mitral valve area in mitral stenosis, the area being considered as the product of the area of the left ventricular outflow tract multiplied by the ratio of the velocity time integrals of the aortic or pulmonary flow to that mitral flow. The continuity equation was compared to two other echocardiographic methods, planimetry and Hatle's method, and to the results obtained at catheterization using the Gorlin formula in a population of 44 patients with mitral stenosis. All were in sinus rhythm; twelve had Grade I mitral regurgitation and 9 patients had Grade I aortic regurgitation. Excellent correlation were observed between the values obtained by the continuity equation and planimetry (r = 0.91; SEE = 0.19 cm2; p less than 0.001) and Hatle's method (r = 0.87; SEE = 0.20 cm2, p less than 0.001). The correlation with the catheter values were also excellent (r = 0.83; SD = 0.22 cm2, p less than 0.001), better than those observed with Hatle's method (r = 0.73; SEE = 0.27 cm2, p less than 0.001) and very similar to those obtained with planimetry (r = 0.87; SEE = 0.23 cm2, p less than 0.001). The sensibility and specificity of the continuity equation for the diagnosis of severe mitral stenosis (surface less than 1.5 cm2) were 90% and 100% respectively, when those of Hatle's method were 88% and 91% respectively. The continuity equation in the evaluation of mitral valve area in mitral stenosis seems to be reliable and accurate compared with catheter data, and superior to Hatle's method.     

Real Time Triplane Echocardiography in Aortic Valve Stenosis: Validation,Reliability, and Feasibility of a New Method for Valve Area Quantification

Aims: The aim of the study was to validate a novel formula for aortic valve area (AVA) based on the principle of continuity equation, that substitutes Doppler‐derived stroke volume (SV) by SV directly measured with real time simultaneous triplane three‐dimensional echocardiography (RT3P). RT3P has proved accuracy for left ventricular volume calculation. So far, however, neither this potential has been applied to hemodynamic assessment, nor RT3P has succeeded in the evaluation of aortic valve disease. Methods and results: AVA was measured in 21 patients with aortic stenosis using Gorlin's equation, Doppler continuity equation (two‐dimensional echocardiography), the novel RT3P method, and by substituting Doppler‐derived SV by SV measured with two‐dimensional stroke volume (2DSV). RT3P has the best linear association (R²= 0.61) and the best correlation with Gorlin of all noninvasive methods (even if not statistically significant). RT3P carries significantly lower mean differences with catheterization, as compared with 2D and 2DSV (Table 4). Standard deviations of mean differences between RT3P and catheterization and between the other echocardiographic methods are not statistically different, even if RT3P seems to be nearer to catheterization. Inter‐ and intraobserver variability were, respectively, 0.03 ± 0.11 cm² and 0.02 ± 0.03 cm², better than 2D and 2DSV. Conclusions: RT3P has revealed to be more accurate than two‐dimensional method in AVA quantification, with a better intraobserver agreement. In addition, it allows simple and fast image acquisition. (Echocardiography 2010;27:644‐650)     

Images in geriatric cardiology. Usefulness of live three-dimensional transthoracic echocardiography in aortic valve stenosis evaluation

Aortic valve stenosis (AS) severity can be estimated by various modalities. Due to some of the limitations of the currently available methods, the usefulness of live three-dimensional transthoracic echocardiography (3D TTE) in the assessment of AS was explored. Live 3D TTE was able to visualize the aortic valve orifice in all 11 patients studied. Live 3D TTE correctly estimated the severity of AS in all 10 patients in whom AS severity could be evaluated at surgery. These included eight patients with severe AS and two with moderate AS. Two of these 10 patients with AS had associated hypertrophic cardiomyopathy and underwent myectomy at the time of aortic valve replacement. Aortic valve orifice area measurements by live 3D TTE correlated well with intraoperative three-dimensional transesophageal echocardiographic reconstruction measurements (r=0.85) but not as well with two-dimensional transesophageal echocardiography measurements (r=0.64). Live 3D TTE measurements of the aortic valve orifice area also did not correlate well with two-dimensional transthoracic echocardiography measurements (r=0.46) but the number of patients studied with two-dimensional transthoracic echocardiography was smaller (only seven) and four of these did not undergo two-dimensional transthoracic echocardiography at the authors' institution. Altogether, four patients with severe AS by live 3D TTE, and subsequently confirmed at surgery, were misdiagnosed as having moderate AS by two-dimensional transthoracic echocardiography. Because it is completely noninvasive and views the aortic valve in three dimensions, 3D TTE could be a useful complement to the existing modalities in the evaluation of AS severity.     

Comparison of left ventricular outflow geometry and aortic valve area in patients with aortic stenosis by 2-dimensional versus 3-dimensional echocardiography

The present study sought to elucidate the geometry of the left ventricular outflow tract (LVOT) in patients with aortic stenosis and its effect on the accuracy of the continuity equation-based aortic valve area (AVA) estimation. Real-time 3-dimensional transesophageal echocardiography (RT3D-TEE) provides high-resolution images of LVOT in patients with aortic stenosis. Thus, AVA is derived reliably with the continuity equation. Forty patients with aortic stenosis who underwent 2-dimensional transthoracic echocardiography (2D-TTE), 2-dimensional transesophageal echocardiography (2D-TEE), and RT3D-TEE were studied. In 2D-TTE and 2D-TEE, the LVOT areas were calculated as π × (LVOT dimension/2)(2). In RT3D-TEE, the LVOT areas and ellipticity ([diameter of the anteroposterior axis]/[diameter of the medial-lateral axis]) were evaluated by planimetry. The AVA is then determined using planimetry and the continuity equation method. LVOT shape was found to be elliptical (ellipticity of 0.80 ± 0.08). Accordingly, the LVOT areas measured by 2D-TTE (median 3.7 cm(2), interquartile range 3.1 to 4.1) and 2D-TEE (median 3.7 cm(2), interquartile range 3.1 to 4.0) were smaller than those by 3D-TEE (median 4.6 cm(2), interquartile range 3.9 to 5.3; p <0.05 vs both 2D-TTE and 2D-TEE). RT3D-TEE yielded a larger continuity equation-based AVA (median 1.0 cm(2), interquartile range 0.79 to 1.3, p <0.05 vs both 2D-TTE and 2D-TEE) than 2D-TTE (median 0.77 cm(2), interquartile range 0.64 to 0.94) and 2D-TEE (median 0.76 cm(2), interquartile range 0.62 to 0.95). Additionally, the continuity equation-based AVA by RT3D-TEE was consistent with the planimetry method. In conclusion, RT3D-TEE might allow more accurate evaluation of the elliptical LVOT geometry and continuity equation-based AVA in patients with aortic stenosis than 2D-TTE and 2D-TEE.     

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.