Eleanor Morris

Diagnostic Value of Vena Contracta Area in the Quantification of Mitral Regurgitation Severity by Color Doppler 3D Echocardiography

Background— Accurate quantification of mitral regurgitation (MR) is important for patient treatment and prognosis. Three-dimensional echocardiography allows for the direct measure of the regurgitant orifice area (ROA) by 3D-guided planimetry of the vena contracta area (VCA). We aimed to (1) establish 3D VCA ranges and cutoff values for MR grading, using the American Society of Echocardiography–recommended 2D integrative method as a reference, and (2) compare 2D and 3D methods of ROA to establish a common calibration for MR grading. Methods and Results— Eighty-three patients with at least mild MR underwent 2D and 3D echocardiography. Direct planimetry of VCA was performed by 3D echocardiography. Two-dimensional quantification of MR included 2D ROA by proximal isovelocity surface area (PISA) method, vena contracta width, and ratio of jet area to left atrial area. There were significant differences in 3D VCA among patients with different MR grades. As assessed by receiver operating characteristic analysis, 3D VCA at a best cutoff value of 0.41 cm2 yielded 97% of sensitivity and 82% of specificity to differentiate moderate from severe MR. There was significant difference between 2D ROA and 3D VCA in patients with functional MR, resulting in an underestimation of ROA by 2D PISA method by 27% as compared with 3D VCA. Multivariable regression analysis showed functional MR as etiology was the only predictor of underestimation of ROA by the 2D PISA method. Conclusions— Three-dimensional VCA provides a single, directly visualized, and reliable measurement of ROA, which classifies MR severity comparable to current clinical practice using the American Society of Echocardiography–recommended 2D integrative method. The 3D VCA method improves accuracy of MR grading compared with the 2D PISA method by eliminating geometric and flow assumptions, allowing for uniform clinical grading cutoffs and ranges that apply regardless of etiology and orifice shape.

Doppler echocardiographic assessment of long-term progression of mitral stenosis in 103 patients: Valve area and right heart disease

OBJECTIVES The purpose of this study was to determine, in a large referral population, the rate of echocardiographic change in mitral valve area (MVA) without interim intervention, to determine which factors influence progression of narrowing and to examine associated changes in the right side of the heart. BACKGROUND Little information is currently available on the echocardiographic progression of mitral stenosis, particularly on progressive changes in the right side of the heart and the ability of a previously proposed algorithm to predict progression. METHODS We studied 103 patients (mean age 61 years; 74% female) with serial two-dimensional and Doppler echocardiography. The average interval between entry and most recent follow-up study was 3.3 +/- 2 years (range 1 to 11). RESULTS During the follow-up period, MVA decreased at a mean rate of 0.09 cm2/year. In 28 patients there was no decrease, in 40 there was only relatively little change (< 0.1 cm2/year) and in 35 the rate of progression of mitral valve narrowing was more rapid (> or = 0.1 cm2/year). The rate of progression was significantly greater among patients with a larger initial MVA and milder mitral stenosis (0.12 vs. 0.06 vs. 0.03 cm2/year for mild, moderate and severe stenosis, p < 0.01). Although the rate of mitral valve narrowing was a weak function of initial MVA and echocardiographic score by multivariate analysis, no set of individual values or cutoff points of these variables or pressure gradients could predict this rate in individual patients. There was a significant increase in right ventricular diastolic area (17 to 18.7 cm2) and tricuspid regurgitation grade (2 + to 3 +; p < 0.0001 between entry and follow-up studies). Progression in right heart disease occurred even in patients with minimal or no change in MVA. Patients with associated aortic regurgitation had a higher rate of decrease in MVA than did those with trace or no aortic regurgitation (0.19 vs. 0.086 cm2/year, p < 0.05). CONCLUSIONS The rate of mitral valve narrowing in individual patients is variable and cannot be predicted by initial MVA, mitral valve score or transmitral gradient, alone or in combination. Right heart disease can progress independent of mitral valve narrowing.

Which physical factors determine tricuspid regurgitation jet area in the clinical setting

The visual assessment of jet area has become the most common method used in daily clinic practice to evaluate valvular regurgitation. Despite the high prevalence of tricuspid regurgitation, however, few studies have systematically compared TR jet areas with a quantitative standard. To evaluate this, 40 patients in sinus rhythm with tricuspid regurgitation were analyzed: 16 with centrally directed free jets and 24 with impinging wall jets. The size of the maximal planimetered color jet area (cm2) was compared with parameters derived using the pulsed Doppler 2-dimensional echocardiographic method: regurgitant fraction and the flow convergence method (peak flow rate, effective regurgitant orifice area and momentum). Mean tricuspid regurgitant fraction averaged 33 +/- 15%, peak flow rate 76 +/- 54 cm3/s, effective regurgitant orifice area 27 +/- 21 mm2 and momentum 21,717 +/- 15,014 cm4/s2. An average of 4-chamber, and long- and short-axis areas in free jets correlated well with regurgitant fraction (r = 0.81, p < 0.001), better with peak flow rate (r = 0.94, p < 0.001), effective regurgitant orifice (r = 0.92, p < 0.001) and momentum (r = 0.94, p < 0.001). The correlation was worse, but still significant, in wall jets. For the same peak flow rate, wall jets were 75% of the size of a corresponding free jet. Jet area measurement is a good semiquantitative tool to measure tricuspid regurgitation in free jets, which correlates well with regurgitant fraction and better with new parameters available from analysis of the proximal acceleration field. In patients with eccentrically directed wall jets the correlation with planimetered jet area was worse, but still significant.

Quantification of tricuspid regurgitation by means of the proximal flow convergence method: A clinical study

Quantitation of valvular regurgitation remains an important goal in clinical cardiology. It has been described previously that with the use of color Doppler flow mapping, simple measurements of apparent jet size do not correlate closely with quantitative regurgitant indices. Recently the proximal flow convergence method has been proposed to quantify valvular regurgitation by analysis of the converging flow field proximal to a regurgitant lesion. Assuming hemispherical convergence, flow rate Q can be calculated as Q = 2 pi r2va, where va is the aliasing velocity at a distance r from the orifice. For maximal accuracy, previously validated correction factors must be used to account for the flattening effect of the isovelocity contours close to the orifice and for the actual sector angle subtended by the valve leaflets (alpha), to yield a flow rate formula Q = 2 pi r2va.(vp/vp - va).(alpha/180), where vp is the orifice velocity obtained by continuous wave Doppler. In 45 patients (35 in sinus rhythm, 10 with atrial fibrillation) with tricuspid regurgitation, regurgitant stroke volume, regurgitant flow rate, and regurgitant fraction were calculated using the proximal flow convergence method and were compared with values obtained by the Doppler two-dimensional echocardiographic method. Regurgitant stroke volumes (SV) calculated by the proximal flow convergence method correlated very closely with values obtained by the Doppler two-dimensional method with r = 0.95 (y = 0.94x + 0.99) and delta SV = -0.3 +/- 5.2 cm3. Regurgitant flow rates (Q) calculated by both methods showed a similar correlation: r = 0.96 (y = 0.97x + 45) and delta Q = 1.6 +/- 429 cm3/min.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitral valve enlargement in chronic aortic regurgitation as a compensatory mechanism to prevent functional mitral regurgitation in the dilated left ventricle.

OBJECTIVES The aim of this study was to test the hypothesis that mitral valve (MV) enlargement occurring in chronic aortic regurgitation (AR) prevents functional mitral regurgitation (FMR). BACKGROUND Chronic AR causes left ventricular (LV) dilation, creating the potential for FMR. However, FMR is typically absent during compensated AR despite substantial LV enlargement. Increased mitral leaflet area has been identified in AR, but it is unknown whether increased MV size can represent a compensatory mechanism capable of preventing FMR. METHODS Database review of 816 patients with at least moderate AR evaluated the prevalence of FMR. A total of 90 patients were enrolled prospectively for 3-dimensional echocardiography (30 AR, 30 FMR, and 30 controls) to assess MV geometry including total leaflet area. RESULTS FMR was present in 5.6% of AR patients by database review. Prospectively, only 1 AR patient had more than mild FMR despite increased LV end-diastolic volume (82 ± 22, 86 ± 23, and 51 ± 12 cm(3)/m(2), respectively, for AR, FMR vs. control patients; p < 0.01) and similar sphericity index, annular area, and tethering distances compared with FMR. Total MV area was largest in AR (31.3% greater than normal), increasing significantly more than in FMR. The ratio of valve size to closure area was maintained in AR, whereas decreases in this ratio and LV ejection fraction independently predicted FMR. CONCLUSIONS FMR prevalence is low in chronic AR. MV leaflet area is significantly increased compared with control and FMR patients, preserving a normal relationship to the area needed for closure in the dilated LV. Understanding the mechanisms underlying this adaptation could lead to new therapeutic interventions to prevent FMR.

Effective regurgitant orifice area in tricuspid regurgitation: Clinical implementation and follow-up study

Analysis of the flow-convergence zone proximal to a regurgitant orifice permits the noninvasive, quantitative measurement of clinically useful parameters of valvular insufficiency. However, many indexes such as flow rate reflect not only the size of the regurgitant lesion but are also highly dependent on the hemodynamic loading conditions. The effective regurgitant orifice area (ROA) in contrast is a more fundamental parameter, less dependent on hemodynamics and more reflective of real changes in the geometry of the valve, making it a promising index for serial assessment of patients. In this study, the measurement of regurgitant orifice area by the flow-convergence method was tested in tricuspid regurgitation and then used to monitor patients noninvasively over time. The effective ROA was calculated in 45 patients with tricuspid regurgitation by means of the flow-convergence method and compared with the ROA obtained with pulsed Doppler echocardiographic methods. An excellent correlation was obtained between the two assessments of ROA (r = 0.96, delta ROA = -0.09 +/- 6.5 mm2). ROA also showed an excellent correlation with other indexes of valvular insufficiency such as regurgitant stroke volume (r = 0.89) and regurgitant fraction (r = 0.88). In a subgroup of 22 patients thought to be clinically stable, ROA was calculated serially over a mean follow-up period of 2 months and its variability compared with that of other flow-based parameters obtainable from proximal acceleration. The variation between the two studies in regurgitant stroke volume and regurgitant flow rate was 5% +/- 20.6% and 5.2% +/- 35.7%, respectively. The effective ROA showed significantly less variability at 1.8% +/- 15%.(ABSTRACT TRUNCATED AT 250 WORDS)

Insights From Three-dimensional Echocardiographic Laser Stereolithography Effect of Leaflet Funnel Geometry on the Coefficient of Orifice Contraction, Pressure Loss, and the Gorlin Formula in Mitral Stenosis

BACKGROUND Three-dimensional echocardiography can allow us to address uniquely three-dimensional scientific questions, for example, the hypothesis that the impact of a stenotic valve depends not only on its limiting orifice area but also on its three-dimensional geometry proximal to the orifice. This can affect the coefficient of orifice contraction (Cc = effective/anatomic area), which is important because for a given flow rate and anatomic area, a lower Cc gives a higher velocity and pressure gradient, and Cc, routinely assumed constant in the Gorlin equation, may vary with valve shape (60% for a flat plate, 100% for a tube). To date, it has not been possible to study this with actual valve shapes in patients. METHODS AND RESULTS Three-dimensional echocardiography reconstructed valve geometries typical of the spectrum in patients with mitral stenosis: mobile doming, intermediate conical, and relatively flat immobile valves. Each geometry was constructed with orifice areas of 0.5, 1.0 and 1.5 cm2 by stereolithography (computerized laser polymerization) (total, nine valves) and studied at physiological flow rates. Cc varied prominently with shape and was larger for the longer, tapered dome (more gradual flow convergence proximal and distal to the limiting orifice): for an anatomic orifice of 1.5 cm2, Cc increased from 0.73 (flat) to 0.87 (dome), and for an area of 0.5 cm2, from 0.62 to 0.75. For each shape, Cc increased with increasing orifice size relative to the proximal funnel (more tubelike). These variations translated into important differences of up to 40% in pressure gradient for the same anatomic area and flow rate (greatest for the flattest valves), with a corresponding variation in calculated Gorlin area (an effective area) relative to anatomic values. CONCLUSIONS The coefficient of contraction and the related net pressure loss are importantly affected by the variations in leaflet geometry seen in patients with mitral stenosis. Three-dimensional echocardiography and stereolithography, with the use of actual information from patients, can address such uniquely three-dimensional questions to provide insight into the relations between cardiac structure, pressure, and flows.

Visual assessment of valvular regurgitation: comparison with quantitative Doppler measurements.

To investigate which factors influence visual evaluation and how accurate it is in patients with valvular insufficiency, 83 patients were studied. All were in sinus rhythm, 43 with mitral and 40 with tricuspid regurgitation. Categoric visual grading (mild, moderate, and severe) was compared with jet area method and regurgitant fraction and the factors that influenced the assigned rank were identified. With jet area method (mean of areas in three planes), the correlation with regurgitant fraction was r = 0.61 for free jets and r = 0.32 for wall jets (overall r = 0.47) in patients with mitral regurgitation, and r = 0.81 and r = 0.46 for free and wall jets, respectively, in patients with tricuspid regurgitation (overall, r = 0.65). With visual grading, the correlation was for free and wall jets, respectively, rho = 0.80 and rho = 0.74 (overall rho = 0.76) in patients with mitral regurgitation, and rho = 0.79 and rho = 0.49 for free and wall jets, respectively (overall rho = 0.62), in patients with tricuspid regurgitation. The jet area parameter found to have the most influence on visual grading was the average area in three planes divided by atrial area, with rho = 0.80 and rho = 0.51 in patients with mitral regurgitation (free and impinging jets respectively) and rho = 0.60 and rho = 0.46 in tricuspid regurgitation. We conclude that visual grading of valvular regurgitant jets correlates well with quantitative measures of valvular incompetence and better than any simple jet area method.(ABSTRACT TRUNCATED AT 250 WORDS)