Estimation Of Mitral Valve Area Research Articles

Variability among 2D and 3D methods of calculating mitral valve area: a comparative study with pressure half time method

Background and Aims: The aim of this study was to evaluate the feasibility, reproducibility and accuracy of Live Three dimensional Echocardiography (3DE), Two dimensional Echocardiography (2DE) and Three dimensional Xplane Echocardiography (3D Xplane) for the estimation of mitral valve area (MVA) and to assess which method has the best agreement with the MVA non- invasively evaluated by the Pressure half time (PHT) method in isolated rheumatic mitral valve stenosis (RMVS).Methods: In 40 patients with isolated RVMS in sinus rhythm (29 female) MVA was determined by Doppler PHT method and compared with measurements obtained by 2DE, Live 3DE and 3D Xplane method. All measurements were performed by two independent observers.Results: For both observers mean MVA was calculated minimum with 3DE (observer 1: 0.68±0.19, observer 2: 0.68±0.19 ). Intraobserver variability was least with 3D Xplane method (observer 1 cv 0.23 , observer 2 cv 0.23). Although there was no significant interobserver variability for each method, it was least for MVA by 3D Xplane method (difference -0.036) and maximum for 3DE method (-0.098) . Difference of each method with PHT showed lowest difference with 3D Xplane (-0.30) and highest with 3DE (-0.63).Conclusions: TTE 3D Xplane provides accurate and highly reproducible measurements of MVA and can easily be performed from optimal PLAX view and corresponding parasternal short-axis views acquired in the same bisected image using 3D Xplane technique . It was much easier and faster to define the image plane in short axis with the smallest orifice area when 3D Xplane method was used.Nepalese Heart Journal 2017; Vol 14(2), 13-17DOI

Three-dimensional proximal flow convergence automatic calculation for determining mitral valve area in rheumatic mitral stenosis.

Management of patients with mitral stenosis (MS) depends heavily on the accurate quantification of mitral valve area (MVA) using echocardiography. All currently used two-dimensional (2D) methods have limitations. Estimation of MVA using the proximal isovelocity surface area (PISA) method with real time three-dimensional (3D) echocardiography may circumvent those limitations. We aimed to evaluate the accuracy of 3D direct measurement of PISA in the estimation of MVA. Twenty-seven consecutive patients (median age of 63years; 77.8% females) with rheumatic MS were prospectively studied. Transthoracic and transesophageal echocardiography with 2D and 3D acquisitions were performed on the same day. The reference method for MVA quantification was valve planimetry after 3D-volume multiplanar reconstruction. A semi-automated software was used to calculate the 3D flow convergence volume. Compared to MVA estimation using 3D planimetry, 3D PISA showed the best correlation (rho=0.78, P<.0001), followed by pressure half-time (PHT: rho=0.66, P<.001), continuity equation (CE: rho=0.61, P=.003), and 2D PISA (rho=0.26, P=.203). Bland-Altman analysis revealed a good agreement for MVA estimation with 3D PISA (mean difference -0.03cm2 ; limits of agreement (LOA) -0.40-0.35), in contrast to wider LOA for 2D methods: CE (mean difference 0.02cm2 , LOA -0.56-0.60); PHT (mean difference 0.31cm2 , LOA -0.32-0.95); 2D PISA (mean difference -0.03cm2 , LOA -0.92-0.86). MVA estimation using 3D PISA was feasible and more accurate than 2D methods. Its introduction in daily clinical practice seems possible and may overcome technical limitations of 2D methods.

3D Xplane Echocardiographic Technique for Validation of Mitral Leaflet Separation to Assess Severity of Mitral Stenosis.

Determining the severity of mitral stenosis (MS) is important for both prognostic and therapeutic implications. Mitral valve area (MVA) calculation techniques have more limitations. Mitral leaflet separation (MLS) is a precise and operator friendly alternative to planimetry. In contrast to previous researchers, we have used a novel 3D Xplane technique to validate MLS for assessing the severity of MS. 3D Xplane is superior for validation of MLS due to simultaneous real time acquisition of MLS in parasternal long-axis view and corresponding MVA by planimetry in parsternal short-axis view. It was a prospective observational single center study. A total of 174 patients with MS were evaluated for MVA estimation by various echocardiographic modalities. Maximum leaflet separation and corresponding planimetered MVA were measured using novel 3D Xplane technique. With 3D Xplane technique, there was strong positive correlation between planimetered MVA and MLS (R = 0.925, P < 0.001), irrespective of coexisting MR (R = 0.886, P < 0.001) or AF (R = 0.912, P < 0.001). Receiver operating characteristic curves of MLS demonstrated AUC for mild and severe MS to be 0.966 and 0.995, respectively. MLS less than 8.62 mm predicted severe MS with 95.5% sensitivity and 94.7% specificity and MLS more than 12.23 mm predicted mild MS with 93.2% sensitivity and 91.4% specificity. In our study, a strong correlation between planimetered MVA and MLS was found using 3D Xplane technique. 3D Xplane thus validates and standardizes MLS by excluding errors due to temporal and spatial variations which are important limitations of 2D echocardiography.

Assessment of mitral valve area in patients with mitral stenosis with 3-dimensional proximal isovelocity surface area

Objective To determine the most suitable Nyquist velocity for applying the threedimensional proximal isovelocity surface area (PISA) (3d-PISA) to calculate mitral valve area (MVA) in patients with mitral stenosis (MS).Methods 20 patients with MS were studied by single-beat three-dimensional color Doppler echocardiography.The MVA was measured by the methods of planimetry (MVApl),two-dimensional PISA (MVA2d-PISA) and 3d-PISA (MVA3d-PISA).MVApl was used as reference methods.At the Nyquist velocities of 32,26 and 19 cm/s,the differences between MVA2d-PISA,MVA3d-PISA and MVApl were analyzed,and then the correlation between MVA2d-PISA,MVA3d-PISA and MVApl were analyzed respectively.Results The 3d-PISA method provided the most accurate estimation of MVA at the Nyquist velocity of 19 cm/s when compared with planimetry.MVA3d-PISA was more accurate than MVA2d-PISA.The acceptable correlations were observed between MVA3d-PISA,MVA2d-PISA and MVApl respectively (r =0.98,r =0.89).Conclusions The 3d-PISA method provided the most accurate estimation of MVA at the Nyquist velocity of 19 cm/s,which provided a new method to calculate mitral valve area with mitral stenosis. Key words: Echocardiography; Mitral valve stenosis; Three-dimensional proximal isovelocity surface area; Nyquist velocity

Impact of Cardiac Rhythm on Mitral Valve Area Calculated by the Pressure Half Time Method in Patients With Moderate or Severe Mitral Stenosis

The pressure half-time (PHT) method has been widely used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS), in the belief that this simple method provides reliable information on true MVA. However, its limitation has been repeatedly recognized under different circumstances. The aim of this study was to evaluate the effect of cardiac rhythm on PHT-derived MVA calculation in relation to net atrioventricular compliance (C(n)). Patients (n = 41) with rheumatic pure moderate or severe MS were consecutively recruited. Eighteen patients with sinus rhythm were allocated to group 1 and the remaining patients with chronic atrial fibrillation to group 2. MVA was obtained using the PHT method and by planimetry (considered the gold standard in this study). C(n) was calculated with a previously validated equation. There were no differences between the 2 groups in terms of age, gender, left ventricular dimensions or ejection fraction, or transmitral pressure gradient. Left atrial volume index (134.6 +/- 106.7 vs 79.2 +/- 16.8 mL; P = .003) and C(n) (6.6 +/- 1.5 vs 4.7 +/- 1.2 mL/mm Hg; P < .001) were higher in group 2 than in group 1. Disagreement of MVA estimation by PHT compared with that by 2-dimensional planimetry was 8.0 +/- 19.2% for group 1 and -24.9 +/- 13.9% for group 2 (P = .002). In addition, the extent of disagreement of PHT-derived MVA compared with that by 2-dimensional planimetry was significantly correlated with C(n) (r(2) = 0.71, P < .001). MVA by the PHT method was estimated to be substantially higher in patients with C(n) values < 4 mL/mm Hg, most of whom were in sinus rhythm. Multivariate analysis confirmed the independent association of cardiac rhythm with discrepancy of PHT-derived MVA compared with that by planimetry. Changes in cardiac rhythm with associated modifications of C(n) can alter the accuracy of the PHT method for estimating MVA. Given the limitation described here, 2-dimensional planimetry, not the PHT method, should be used as a primary echocardiographic tool for MVA calculation.

Transthoracic real-time three-dimensional echocardiography offers additional value in the assessment of mitral valve morphology and area following mitral valve repair

The accurate postoperative assessment of mitral valve repair is important not only to document operative outcome, but also to confirm the functional morphology of the repaired valve. We assessed 25 consecutive patients following mitral valve repair with transthoracic real-time 3-dimensional echocardiography (RT3DE) and 2-dimensional echocardiography (2DE). We compared the adequacy of the visualization of the mitral valve Carpentier segments, the site of the repair, and the accuracy of planimetry by RT3DE and 2DE in estimating the postoperative mitral valve area (MVA), compared to the Doppler-derived pressure half-time (PHT) value. Inter-observer variability and feasibility were also assessed for RT3DE. Adequate visualization of the mitral valve segments was more frequently obtained by 3DE imaging (163/170 by 3DE vs. 121/170 by 2DE, P < 0.001). In particular, the mitral valve commissures were more clearly identified with 3DE. 3DE also was significantly better at correctly identifying the site of the repaired segment (26/30 by 3DE vs. 19/30 by 2DE, P < 0.05). The difference in MVA (mean difference +/- SD) determined by 3DE planimetry, when compared to PHT was -0.21 +/- 0.46 cm(2) and -0.44 +/- 0.95 cm(2) for 2DE (P = 0.014). Planimetry by 3DE more closely correlated with the MVA calculated by PHT than 2DE planimetry (r = 0.89 for 3DE vs. r = 0.6 for 2DE). Imaging with RT3DE was both feasible, with a mean acquisition time of 4.02 +/- 1.68 min, and data analysis time of 15.82 +/- 3.9 min, and reproducible, with good inter-observer variability for segment scoring with 3DE (kappa = 0.79) and mean inter-observer difference in assessing MVA by 3DE planimetry of 0.18 +/- 0.12 cm(2) (P = NS). This study suggests that RT3DE offers additional morphological postoperative data of repaired mitral valves, and increases the accuracy of MVA estimation by planimetry. It is both feasible in a busy echocardiography department and reproducible.

Evaluation of mitral valve area by the proximal isovelocity surface area method in mitral stenosis: Could it be simplified?

One limitation for a wider use of the proximal isovelocity surface area method (PISA) for the evaluation of the mitral valve area (MVA) in patients with mitral stenosis (MS) is the requirement of an angle correction factor (angle alpha between the mitral leaflets) which cannot be obtained using the machine's built-in software and requires a manual measurement. The aim of the present study was to evaluate if the use of a fixed angle could provide an acceptable MVA estimation. In 48 patients (53 +/- 14 years, 75% female and 32% atrial fibrillation), MVA was prospectively measured by planimetry (MVA(2D)) and PISA (PISA(mes)). The angle alpha was manually measured on paper prints using a protractor. MVA(2D) was 1.38 +/- 0.56 cm(2) [0.5-2.40]. PISA(mes) (alpha = 104 +/- 13 degrees inter-quartiles 90-115) was 1.34 +/- 0.64 cm(2) [0.31-2.95] and did not differ from and correlated well with MVA(2D) (P = 0.25; r = 0.93, P < 0.0001). MVA estimated using the PISA method and a fixed angle value from 90 to 110 (MVA(alpha)(=90) to MVA(alpha)(=110)) progressively increased from 1.20 +/- 0.66 to 1.48 +/- 0.81 cm(2). Only MVA(alpha)(=100) (1.34 +/- 0.74 cm(2)) did not differ from and correlated well with both MVA(2D) and PISA(mes) (both P > 0.35 and r > 0.90, P < 0.0001). The angle formed by the mitral leaflet only slightly changes in between patients and use of a fixed angle value of 100 degrees provides an accurate estimation of the MVA by the PISA method in patients with MS. This simplification would facilitate and extend the use of the PISA as an additional method for the assessment of MS severity in routine practice.

Real-time three-dimensional echocardiography for rheumatic mitral valve stenosis evaluation: An accurate and novel approach

ObjectivesOur aim was to assess which echo-Doppler method has the best agreement with the mitral valve area (MVA) invasively evaluated by the Gorlin′s formula. We also evaluated the feasibility and reproducibility of real-time three-dimensional echocardiography (RT3D) for the estimation of MVA and the Wilkins score in patients with rheumatic mitral stenosis (RMVS). BackgroundReal-time three-dimensional echocardiography is a novel technique that allows us to visualize the mitral valvular anatomy in any desired plane orientation. The usefulness and accuracy of this technique for evaluating RMVS has not been established. MethodsWe studied a series of consecutive patients with RMVS from two tertiary care hospitals. Mitral valvular area was determined by conventional echo-Doppler methods and by RT3D, and their results were compared with those obtained invasively. Real-time three-dimensional echocardiography planimetry and mitral score were measured by two independent observers and then repeated by one of them. ResultsEighty patients with RMVS comprised our study group (76 women; 50.6 ± 13.9 years). Compared with all other echo-Doppler methods, RT3D had the best agreement with the invasively determined MVA (average difference between both methods and limits of agreement: 0.08 cm2[−0.48 to 0.6]). Interobserver variability was as good for RT3D (intraclass correlation coefficient [ICC] = 0.90) as for pressure half-time (PHT) (ICC = 0.95). For PHT and RT3D, the intraobserver variability was similar (ICC 0.92 and 0.96, respectively). Real-time three-dimensional echocardiography valvular score evaluation showed a better interobserver agreement with RT3D than with 2D echocardiography. ConclusionsReal-time three-dimensional echocardiography is a feasible, accurate, and highly reproducible technique for assessing MVA in patients with RMVS. Real-time three-dimensional echocardiography has the best agreement with invasive methods.

Application of the Vena contracta Method for the Calculation of the Mitral Valve Area in Mitral Stenosis

Objectives: The vena contracta is the narrowest region of the regurgitant or stenotic jet just downstream the orifice and reflects the size of that orifice. This study was performed to assess the accuracy of the vena contracta width (VCW) in evaluating the severity of mitral stenosis (MS) and to compare the mitral valve area (MVA) determined by VCW with MVAs obtained by other more traditional echocardiographic methods. Methods: We studied 59 patients (43 females, 42 ± 14 years) with MS. VCW was measured in the apical four chamber view by Doppler color flow mapping. The largest diameter of the VCW during diastole was measured for at least three cardiac cycles and averaged. MVA was calculated from the following equation: πr², where r = VCW/2. MVA was also determined by planimetry, the pressure half-time method, and by the Gorlin formula. Results: In this study, the width of the vena contracta ranged from 0.89 to 1.73 cm (mean 1.30 ± 0.21). MVA, calculated based on the VCW, ranged from 0.63 to 2.35 cm² (mean 1.36 ± 0.41). MVA by VCW (1.36 ± 0.41 cm²) showed good correlations with three comparative techniques: (1) the cross-sectional area by planimetry (1.35 ± 0.36 cm², mean difference = 0.21 ± 0.16 cm², y = 0.91x + 0.14, r = 0.79, SEE = 0.26 cm², p < 0.001); (2) the area derived from the Doppler pressure half-time (1.27 ± 0.32 cm², mean difference = 0.22 ± 0.19 cm², y = 0.97x + 0.13, r = 0.76, SEE = 0.27 cm², p < 0.001), and (3) the area derived from the Gorlin equation in the 18 patients who underwent catheterization (1.27 ± 0.35 cm², mean difference = 0.19 ± 0.16, y = 0.98x + 0.05, r = 0.81, SEE = 0.26 cm², p < 0.001). Conclusions: These findings suggest that Doppler color flow imaging of the MS jet in the vena contracta can provide an accurate estimation of MVA and appears to be potentially applicable in the assessment of the severity of MS.

Clinical application in routine practice of the proximal flow convergence method to calculate the mitral surface area in mitral valve stenosis.

Two-dimensional (2D) echocardiography planimetry, the Doppler pression half-time (PHT), and the continuity equation methods were used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS). Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA. The purpose of this study is (1) to compare in a large non-selected population the accuracy of the PISA and planimetry methods for echocardiographic estimation of MVA; (2) to determine the effect of atrial fibrillation (AF), Wilkins score, associated mitral regurgitation (MR), aortic regurgitation (AR), and of commissural calcifications on the accuracy of the PISA method. One hundred and eight consecutive patients with rheumatic MS were studied (76 females and 32 males; mean age: 36 +/- 12 years); 64 were in sinus rhythm; 51 had associated MR and 46 had AR. By the PISA method. MVA was calculated assuming a uniform radius flow convergence region along a hemispherical surface. The mean value of 2D MVA was 1.32 +/- 0.59 cm2 (0.4-3.1 cm2) and that of PISA MVA 1.33 +/- 0.62 cm2 (0.38-3 cm2). MVA calculated using the PISA method correlated well with 2D MVA (r = 0.93, y = 0.97x + 0.04, p < 0.0001, SEE = 0.21 cm2). The correlation was also good in patients with AF (r = 0.93, y = 0.99x + 0.03, p < 0.0001, SEE = 0.21 cm2), with MR (r = 0.94, y = 1.0 14x + 0.003, p < 0.0001, SEE = 0.19 cm2), with AR (r = 0.93, y = 0.90x + 0.11, p < 0.0001, SEE = 0.2 cm2), when Wilkins score was >8 (r = 0.92, = 0.96x + 0.06, p < 0.0001, SEE = 0.19 cm2), and in patients with commissural calcifications (r = 0.90, y = 0.88x + 0.009, p < 0.0001, SEE = 0.20 cm2). Our study shows that in routine practice, MVA calculated by the PISA method correlated well with the area obtained by planimetry even in the presence of commissural calcifications, associated MR, AR, AF and of high Wilkins score. Therefore, the PISA method provides a reliable measurement of the MVA in MS under different anatomic and clinical conditions and may be a useful alternative method for calculating MVA.

Improved assessment of mitral valve stenosis by volumetric real-time three-dimensional echocardiography

OBJECTIVESThis study was performed to determine the feasibility, accuracy and reproducibility of real-time volumetric three-dimensional echocardiography (3-D echo) for the estimation of mitral valve area in patients with mitral valve stenosis.BACKGROUNDPlanimetry of the mitral valve area (MVA) by two-dimensional echocardiography (2-D echo) requires a favorable parasternal acoustic window and depends on operator skill. Transthoracic volumetric 3-D echo allows reconstruction of multiple 2-D planes in any desired orientation and is not limited to parasternal acquisition, and could thus enhance the accuracy and feasibility of calculating MVA.METHODSIn 48 patients with mitral stenosis (40 women; mean age 61 ± 13 years) MVA was determined by planimetry using volumetric 3-D echo and compared with measurements obtained by 2-D echo and Doppler pressure half-time (PHT). All measurements were performed by two independent observers. Volumetric data were acquired from an apical view.RESULTSAlthough 2-D echo allowed planimetry of the mitral valve in 43 of 48 patients (89%), calculation of the MVA was possible in all patients when 3-D echo was used. Mitral valve area by 3-D echo correlated well with MVA by 2-D echo (r = 0.93, mean difference, 0.09 ± 0.14 cm2) and by PHT (r = 0.87, mean difference, 0.16 ± 0.19 cm2). Interobserver variability was significantly less for 3-D echo than for 2-D echo (SD 0.08cm2 versus SD 0.23cm2, p < 0.001). Furthermore, it was much easier and faster to define the image plane with the smallest orifice area when 3-D echo was used.CONCLUSIONSTransthoracic real-time volumetric 3-D echo provides accurate and highly reproducible measurements of mitral valve area and can easily be performed from an apical approach.

Validation of flow convergence region method in assessing mitral valve area in the course of transthoracic and transesophageal echocardiographic studies

The purpose of this study was to determine the diagnostic value of flow convergence region method (FCR) to complement well-accepted techniques in assessing mitral valve area (MVA). Fifty-three patients (39 women, 14 men) were enrolled in the study. Transesophageal echocardiography (TEE) was performed after transthoracic echocardiographic (TTE) evaluation, and all measurements were performed for each patient. Mean MVA values determined by different methods both in TEE and TTE studies did not differ ( p = not significant). In 51 (96%) patients, TEE and TTE were feasible and measurements of MVA with FCR correlated well with the conventional methods ( r = 0.87, standard error of the estimate = 0.13 cm 2). In TEE, MVA determined by FCR also correlated well with that obtained by the “pressure half time” method ( r = 0.90, standard error of the estimate = 0.11 cm 2). Results of our study confirmed the feasibility and accuracy of FCR. Because TEE provides reliable estimation of MVA by FCR, intraoperative monitoring by TEE should be considered as a comparative alternative method. (Am Heart J 1998;135:207-14.)

Comparison of proximal isovelocity surface area method with pressure half-time and planimetry in evaluation of mitral stenosis

Objectives. This study sought to 1) compare the accuracy of the proximal isovelocity surface area (PISA) and Doppler pressure half-time methods and planimetry for echocardiographic estimation of mitral valve area; 2) evaluate the effect of atrial fibrillation on the accuracy of the PISA method; and 3) assess factors used to correct PISA area estimates for leaflet angulation.Background. Despite recognized limitations of traditional echocardiographic methods for estimating mitral valve area, there has been no systematic comparison with the PISA method in a single cohort.Methods. Area estimates were obtained in patients with mitral stenosis by the Gorlin hydraulic formula, PISA and pressure half-time method in 48 patients and by planimetry in 36. Two different factors were used to correct PISA estimates for leaflet angle (θ): 1) plane-angle factor (θ/180 [θ in degrees]); and 2) solid-angle factor [1 — cos(θ/2)].Results. After exclusion of patients with significant mitral regurgitation, the correlation between Gorlin and PISA areas (0.88) was significantly greater (p < 0.04) than that between Gorlin and pressure half-time (0.78) or Gorlin and planimetry (0.72). The correlation between Gorlin and PISA area estimates was lower in atrial fibrillation than sinus rhythm (0.69 vs. 0.93), but the standard error of the estimate was only slightly greater (0.24 vs. 0.19 cm2). The average ratio of the solid- to the plane-angle correction factors was approximately equal to previously reported values of the orifice contraction coefficient for tapering stenosis.Conclusions. 1) The accuracy of PISA area estimates in mitral stenosis is at least comparable to those of planimetry and pressure half-time. 2) Reasonable accuracy of the PISA method is possible in irregular rhythms. 3) A simple leaflet angle correction factor, θ/180 (θ in degrees), yields the physical orifice area because it overestimates the vena contracta area by a factor approximately equal to the contraction coefficient for a tapering stenosis.

Biplane transesophageal color Doppler echocardiography for assessment of mitral valve area with mitral inflow jet widths

Biplane transesophageal color Doppler echocardiography can image the mitral valve orifice in two orthogonal views. If the maximal stenotic jet width through the mitral valve obtained with the vertical transducer represents the major axis, the stenotic jet width dissected by the horizontal transducer should be the minor axis of the mitral orifice. Thus the mitral valve area can be calculated assuming an oval shape of mitral orifice. Nineteen patients with mitral stenosis were investigated. Maximal mitral stenotic jet width (JW1) was searched on a vertical plane and the jet width from the orthogonal view (JW2) was obtained on a horizontal plane. Mitral valve areas from the color Doppler jet widths were calculated by pi.JW1/2.JW2/2 and compared with those derived from Gorlin's formula. Adequate quality of echocardiographic images could be obtained in all patients for transesophageal color Doppler jet width measurements or Doppler pressure half-time determinations and in 16 of 19 patients for transthoracic planimetery of the mitral orifice at the parasternal short axis. Mitral valve areas derived from biplane transesophageal color Doppler imaging (1.31 +/- 0.53 cm2) were not different from those calculated according to Gorlin's formula from the catheterization data (1.25 +/- 0.50 cm2), those determined by transthoracic echocardiographic planimetery (1.38 +/- 0.5 cm2), or those calculated from the Doppler pressure half-time method (1.32 +/- 0.41 cm2) (difference not significant by analysis of variance). There was a very strong correlation between transesophageal echocardiographic mitral valve areas and those derived from catheterization data (r = 0.94; standard error of the estimate = 0.13 cm2). A similar correlation was obtained for the planimetric echocardiographic method (r = 0.94; standard error of the estimate = 0.14 cm2). A slightly less strong correlation was found between mitral valve areas derived from the Doppler pressure half-time method and those derived from Gorlin's formula (r = 0.83; standard error of the estimate = 0.24 cm2). The pressure half-time method accurately predicted the mitral valve area in most (15/19) patients, but it significantly (> 0.4 cm2) overestimated mitral valve area in two patients with aortic regurgitation and underestimated (< 0.4 cm2) mitral valve area in two patients with left ventricular hypertrophy. Determination of mitral valve area by color Doppler biplane transesophageal echocardiography is an alternative for accurate estimation of mitral valve area and may be most useful in intraoperative monitoring during surgical or balloon mitral commissurotomy or in the case of inadequate imaging quality of transthoracic echocardiography.

Estimation of Mitral Valve Area in Patients with Mitral Stenosis by the Flow Convergence Region Method: Selection of Aliasing Velocity

Estimation of Mitral Valve Area in Patients with Mitral Stenosis by the Flow Convergence Region Method: Selection of Aliasing Velocity

Estimation of mitral valve area in patients with mitral stenosis by the flow convergence region method: Selection of aliasing velocity

Objectives. We attempted to determine the most suitable aliasing velocity for applying the hemispheric flow convergence equation to calculate the mitral valve area in mitral stenosis using a continuity equation.Background. The flow convergence region method has been used for calculating mitral valve area in patients with mitral stenosis. However, the effect of varying aliasing velocity on the accuracy of this method has not been investigated fully.Methods. We studied 42 patients with mitral stenosis using imaging and Doppler echocardiography. Aliasing velocities of 17, 21, 28, 34, 40 and 45 cm/s were used. The transmitral maximal flow rate (Q [ml/s]) was calculated using the hemispheric flow convergence equation Q = 2 × π × R2× AV × α/180, where R (cm) is the maximal radius of the flow convergence region, AV is the aliasing velocity, and α/180 is a factor accounting for the inflow angle (α). Mitral valve area (A [cm2]) was calculated according to the continuity equation A = Q/V, where V (cm/s) is the peak transmitral velocity by the continuous wave Doppler method.Results. Mitral valve area was progressively underestimated with increasing aliasing velocity. The actual and percent differences noted between the mitral valve area by the flow convergence region method and that by two-dimensional echocardiographic planimetry were −0.06 ± 0.23 cm2(mean ± SD) and 0.09 ± 15.7% at an aliasing velocity of 21 cm/s, increasing gradually with increasing aliasing velocity, and were −1.24 ± 0.9 cm2and −72.56 ± 16.4% at an aliasing velocity of 45 cm/s. Mitral valve areas estimated by the flow convergence region method at an aliasing velocity of 21 cm/s in 11 patients with associated > 2+ mitral regurgitation (2.12 ± 1.17 cm2) and 8 with associated > 2+ aortic regurgitation (1.28 ± 0.71 cm2) were not significantly different using planimetry (2.24 ± 1.39 cm2, p > 0.05 and 1.27 ± 0.74 cm2, p > 0.05, respectively) but were significantly different by the pressure half-time method (1.59 ± 1.12 cm2, p < 0.001 and 1.63 ± 0.93 cm2, p < 0.01, respectively).Conclusions. This study indicated the most appropriate aliasing velocity for the accurate estimation of mitral valve area in patients with mitral stenosis.

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Non-invasive assessment of mitral stenosis before and after percutaneous balloon mitral valvotomy by Doppler continuity equation.

The continuity equation was used to estimate non-invasively the stenotic mitral valve area by comparison with two other echocardiographic methods (planimetry and pressure half-time) and with Gorlin's formula as the gold standard. The accuracy of the equation of continuity was determined before and 24 h after valvuloplasty in a study group of 21 patients with severe mitral stenosis. According to the equation of continuity, mitral valve area was calculated by the product of the cross-sectional area and the aortic or pulmonary annulus and the ratio of the time velocity integral of the aortic or pulmonary flow to that of the mitral stenotic jet. In pre-valvotomy basal conditions, the Doppler continuity equation demonstrated significant correlations with 2D planimetry (r = 0.72, P less than 0.01), with the pressure half-time method (r = 0.62, P less than 0.01) and with the Gorlin formula (r = 0.66, P less than 0.01). There was no significant difference between the haemodynamic data and the echocardiographic measurements. Twenty-four hours after valvotomy, the Doppler continuity equation also demonstrated significant correlations with 2D planimetry (r = 0.83, P less than 0.01), with pressure half-time (r = 0.82, P less than 0.01) and with the Gorlin formula (r = 0.69, P less than 0.01). However, the haemodynamic measurements significantly overestimated (P less than 0.01) the echographic measurements. Thus, we conclude that the continuity equation provides an accurate estimation of mitral valve area in mitral stenosis before and after balloon valvotomy.

Estimation of mitral valve area from regression analysis of the pressure gradient in mitral stenosis

Estimation of mitral valve area (MVA) in the cardiac catheterization laboratory is prone to pitfalls because of the time required for calculations and inaccuracies in the measurement of cardiac output. Because the rate of decrease in the mitral gradient directly correlates with the severity of mitral stenosis, an on-line estimate of MVA at the time of catheterization may be possible with regression analysis of digitized pressure recordings. A total of 61 comparisons of mitral gradient measurements and MVA were obtained in 37 patients at diagnostic catheterization and in 24 patients after balloon mitral valvotomy. Linear and nonlinear regression parameters yielded pressure half-time values and empiric constants similar to those used in Doppler echocardiography for estimation of MVA. The correlations derived from linear analysis were as good as those obtained from nonlinear analysis: from linear analysis, MVA regression = 0.79 · MVA Grolin − 0.03; r 2 = 0.64, p = 0.0001; and from double exponential analysis, MVA regression = 0.86 · MVA Gorlin − 0.07; r 2 = 0.74; p = 0.0001. The correlations were not significantly affected by the presence of mild to moderate mitral regurgitation or whether they were obtained after balloon valvotomy. In summary, linear regression analysis yields accurate estimates of MVA despite the theoretical superiority of nonlinear methods. On-line digital analysis of mitral gradient tracings may thus be useful at the time of diagnostic cardiac catheterization or balloon mitral valvotomy to assess the severity of mitral stenosis and the response to interventions.

Doppler echocardiographic estimation of mitral valve area during changing hemodynamic conditions

Patients with mitral stenosis often present during periods of hemodynamic stress such as pregnancy or infections. The Doppler pressure half-time method of mitral valve area (MVA) determination is dependent on the net atrioventricular compliance as well as the peak transmitral gradient. The continuity equation method of MVA determination is based on conservation of mass and may be less sensitive to changes in the hemodynamic state. To test this hypothesis, 17 patients admitted for catheterization with symptomatic mitral stenosis and no more than mild regurgitation underwent Doppler echocardiography at rest and during supine bicycle exercise targeted to an increase in heart rate by 20 to 30 beats/minute. Net atrioventricular compliance was also estimated noninvasively. Cardiac output and transmitral gradient increased significantly during exercise (p < 0.001), while net atrioventricular compliance decreased (p < 0.001). MVA by the pressure half-time method increased significantly during exercise from 1.0 ± 0.2 to 1.4 ± 0.4 cm 2 (p < 0.001). There was no significant difference in MVA estimation using the continuity equation comparing rest to exercise, with the mean area remaining constant at 0.8 ± 0.3 cm 2 (p = 0.83). Thus, during conditions of changing hemodynamics, the continuity equation method for estimating MVA may be preferable to the pressure half-time method.