Quantification of mitral regurgitation by the proximal convergence method using transesophageal echocardiography. Clinical validation of a geometric correction for proximal flow constraint

Imaging of the Mitral Valve

Echocardiographic imaging is the foundation for the evaluation of mitral valve dysfunction. Both transthoracic and transesophageal echocardiography provide insight into the anatomy, pathology, and classification mitral valve dysfunction. Echocardiography also provides a multi-parametric approach with semi-quantitative and quantitative parameters to assess the severity of mitral regurgitation and mitral stenosis. Transesophageal imaging is essential in the assessment of patients considered for surgical or transcatheter interventional strategies to treat mitral valve dysfunction. Cardiac computed tomography (CT) and cardiac MRI are useful adjunctive imaging techniques in mitral valve disease with CT providing detailed procedural specificity and MRI providing detailed ventricular and regurgitant flow analysis.

Quantification of primary mitral regurgitation by echocardiography: A practical appraisal

The accurate quantification of primary mitral regurgitation (MR) and its consequences on cardiac remodeling is of paramount importance to determine the best timing for surgery in these patients. The recommended echocardiographic grading of primary MR severity relies on an integrated multiparametric approach. It is expected that the large number of echocardiographic parameters collected would offer the possibility to check the measured values regarding their congruence in order to conclude reliably on MR severity. However, the use of multiple parameters to grade MR can result in potential discrepancies between one or more of them. Importantly, many factors beyond MR severity impact the values obtained for these parameters including technical settings, anatomic and hemodynamic considerations, patient's characteristics and echocardiographer' skills. Hence, clinicians involved in valvular diseases should be well aware of the respective strengths and pitfalls of each of MR grading methods by echocardiography. Recent literature highlighted the need for a reappraisal of the severity of primary MR from a hemodynamic perspective. The estimation of MR regurgitation fraction by indirect quantitative methods, whenever possible, should be central when grading the severity of these patients. The assessment of the MR effective regurgitant orifice area by the proximal flow convergence method should be used in a semi-quantitative manner. Furthermore, it is crucial to acknowledge specific clinical situations in MR at risk of misevaluation when grading severity such as late-systolic MR, bi-leaflet prolapse with multiple jets or extensive leak, wall-constrained eccentric jet or in older patients with complex MR mechanism. Finally, it is debatable whether the 4-grades classification of MR severity would be still relevant nowadays, since the indication for mitral valve (MV) surgery is discussed in clinical practice for patients with 3+ and 4+ primary MR based on symptoms, specific markers of adverse outcome and MV repair probability. Primary MR grading should be seen as a continuum integrating both quantification of MR and its consequences, even for patients with presumed “moderate” MR.

Impact of assuming a circular orifice on flow error through elliptical regurgitant orifices: computational fluid dynamics and in vitro analysis of proximal flow convergence

Grounded in hydrodynamic theory, proximal isovelocity surface area (PISA) is a simplistic and practical technique widely used to quantify valvular regurgitation flow. PISA provides a relatively reasonable, though slightly underestimated flow rate for circular orifices. However, for elliptical orifices frequently seen in functional mitral regurgitation, PISA underestimates the flow rate. Based on data obtained with computational fluid dynamics (CFD) and in vitro experiments using systematically varied orifice parameters, we hypothesized that flow rate underestimation for elliptical orifices by PISA is predictable and within a clinically acceptable range. We performed 45 CFD simulations with varying orifice areas 0.1, 0.3 and 0.5 cm², orifice aspect ratios 1:1, 2:1, 3:1, 5:1, and 10:1, and peak velocities (V_max) 400, 500 and 600 cm/s. The ratio of computed effective regurgitant orifice area to true effective area (EROA_C/EROA) against the ratio of aliasing velocity to peak velocity (V_A/V_max) was analyzed for orifice shape impact. Validation was conducted with in vitro imaging in round and 3:1 elliptical orifices. Plotting EROA_C/EROA against V_A/V_max revealed marginal flow underestimation with 2:1 and 3:1 elliptical axis ratios against a circular orifice (< 10% for 8% V_A/V_max), rising to ≤ 35% for 10:1 ratio. In vitro modeling confirmed CFD findings; there was a 8.3% elliptical EROA underestimation compared to the circular orifice estimate. PISA quantification for regurgitant flow through elliptical orifices produces predictable, but generally small, underestimation deemed clinically acceptable for most regurgitant orifices.

Quantification of mitral regurgitation after transcatheter edge-to-edge repair: Comparison of echocardiography and patient-specific in silico models

BACKGROUND

Doppler echocardiographic (echo) assessment of residual mitral regurgitation (MR) after transcatheter edge-to-edge repair (TEER) is challenging and often subjective. This study aimed to evaluate the accuracy and feasibility of standardized quantitative echo methods for assessment of MR severity after MitraClip repair by comparing measurements against a reference MR severity obtained from patient-specific in silico models.

METHODS

Post-procedure hemodynamics were simulated under five different MitraClip configurations in previously validated patient-specific in silico models for the treatment of functional MR. The residual regurgitant volume was calculated as in clinical practice using four quantitative virtual echo methods: pulsed Doppler, volumetric, proximal isovelocity surface area (PISA) and vena contracta area (VCA). Multiple permutations were performed for each method. Virtual echo MR results were evaluated against reference MR values directly extracted from the 5 patient-specific in silico models.

RESULTS

The echo methods with the greatest accuracy were the three-dimensional (3D) volumetric method (r = 0.957, bias -0.8 ± 1.2 ml, p = 0.01), the 3D VCA method wherein velocity time integrals were evaluated for each jet assessed (r = 0.919, bias -1.5 ± 1.7 ml, p = 0.03), and the 3D PISA method integrating surface areas throughout systole (r = 0.98, bias -2.0 ± 0.9 ml, p = 0.003). The pulsed Doppler and 2D volumetric methods had technical limitations that may result in a high underestimation or overestimation of the MR severity after TEER. In the case of multiple regurgitant jets, a more accurate MR assessment was obtained when all significant jets were evaluated.

CONCLUSIONS

Clinically, the 3D volumetric, 3D VCA and 3D PISA methods gave the most accurate MR quantification after TEER. Three-dimensional echo technologies harbor the potential of becoming the non-invasive imaging tool of choice for MR quantification after complex transcatheter mitral interventions.

Impact of correcting the 2D PISA method on the quantification of functional tricuspid regurgitation severity

AIMS

In functional tricuspid regurgitation (FTR) patients, tricuspid leaflet tethering and relatively low jet velocity could result in proximal flow geometry distortions that lead to underestimation of TR. Application of correction factors on two-dimensional (2D) proximal isovelocity surface area (PISA) equation may increase its reliability. This study sought to evaluate the impact of the corrected 2D PISA method in quantifying FTR severity.

METHODS AND RESULTS

In 102 patients with FTR, we compared both conventional and corrected 2D PISA measurements of effective regurgitant orifice area [EROA vs. corrected (EROAc)] and regurgitant volume (RegVol vs. RegVolc) with those obtained by volumetric method (VM) using three-dimensional echocardiography (3DE), as reference. Both EROAc and RegVolc were larger than EROA (0.29 ± 0.26 vs. 0.22 ± 0.21 cm2; P < 0.001) and RegVol (24.5 ± 20 vs. 18.5 ± 14.25 mL; P < 0.001), respectively. Compared with VM, both EROAc and RegVolc resulted more accurate than EROA [bias = -0.04 cm2, limits of agreement (LOA) ± 0.02 cm2 vs. bias = -0.15 cm2, LOA ± 0.31 cm2] and RegVol (bias = -3.29 mL, LOA ± 2.19 mL vs. bias = -10.9 mL, LOA ± 13.5 mL). Using EROAc and RegVolc, 37% of patients were reclassified in higher grades of FTR severity. Corrected 2D PISA method led to a higher concordance of TR severity grade with the VM method (ĸ = 0.84 vs. ĸ = 0.33 for uncorrected PISA, P < 0.001).

CONCLUSION

Compared with VM by 3DE, the conventional PISA underestimated FTR severity in about 50% of patients. Correction for TV leaflets tethering angle and lower velocity of FTR jet improved 2D PISA accuracy and reclassified more than one-third of the patients.

Intraoperative comparison of 2D versus 3D transesophageal echocardiography for quantitative assessment of mitral regurgitation

Background:

Effective regurgitant orifice area (EROA) can be represented by 3D echocardiographic vena contracta cross-sectional area (3D-VCA) as a reference method for the quantification of mitral regurgitation (MR) without making any geometrical assumptions. EROA can also be derived from 3D PISA technique with a hemispherical (HS) or hemielliptical (HE) assumption of the proximal flow convergence. However, it is not clear whether HS-PISA and HE-PISA has better agreement with 3D-VCA.

Aims:

This study was conducted to compare the EROA and Rvol obtained from 3D-VCA with those obtained from 2D-VC, 2D-HS-PISA, 3D-HS-PISA, and 3D-HE-PISA.

Setting:

Tertiary care hospital.

Design:

Prospective observational study.

Materials and Methods:

After anesthesia induction, 43 consecutive patients were evaluated with RT-3D-TEE after acquiring images from midesophegeal views and performing the offline analysis of volume dataset. 3D-VCA was measured using multiplanar reconstruction mode and EROA and regurgitant volume were estimated using HS-PISA and HE-PISA methods. The HE-PISA was calculated by using the Knud Thomsen formula.

Statistical Analysis:

Agreement between methods to estimate EROA and regurgitant volumes were tested using Bland–Altman analysis. The interobserver variability and intraobserver variability were assessed using an intraclass correlation coefficient.

Results:

The EROA estimated by 3D-VCA was larger than EROA obtained by 2D-HS-PISA and 3D-HS-PISA, which were significantly greater than 3D-HE-PISA. 3D-HS-PISA-EROA showed the best agreement with 3D-VCA (bias: 0.21; limits of agreement: −0.01 to 0.41; SD: 0.1). Correlation between various methods as compared to 3D-VCA was better in the organic MR group than functional MR group.

Conclusion:

3D-HS-PISA showed the best agreement with 3D-VCA compared to other PISA methods. Better correlation between PISA-EROA and 3D-VCA was observed in patients with organic MR than functional MR.

Quantification of regurgitation in mitral valve prolapse with automated real time echocardiographic 3D proximal isovelocity surface area: multimodality consistency and role of eccentricity index

Three-dimensional transthoracic echocardiography (3D-TTE) provides a semi-automated proximal isovelocity surface area method (3D-PISA) to obtain quantitative parameters. Data assessing regurgitation severity in mitral valve prolapse (MVP) are scarce, so we assessed the 3D-PISA method compared with 2D-PISA and cardiovascular magnetic resonance (CMR) and the role of an eccentricity index. We evaluated the 3D-PISA method for assessing MR in 54 patients with MVP (57 ± 14 years; 42 men; 12 mild/mild-moderate; 12 moderate-severe; and 30 severe MR). Role of an asymmetric (i.e. eccentricity index ≥ 1.25) flow convergence region (FCR) and inter-modality consistency were then assessed. 3D-PISA derived regurgitant volume (RVol) showed a good correlation with 2D-PISA and CMR derived parameters (r = 0.86 and r = 0.81, respectively). The small mean differences with 2D-PISA derived RVol did not reach statistical significance in overall population (5.7 ± 23 ml, 95% CI - 0.6 to 12; p = 0.08) but differed in those with asymmetric 3D-FCR (n = 21; 2D-PISA: 72 ± 36 ml vs. 3D-PISA: 93 ± 47 ml; p = 0.001). RVol mean values were higher using PISA methods (CMR 57 ± 33 ml; 2D-PISA 73 ± 39 ml; and 3D-PISA 79 ± 45 ml) and an overestimation was observed when CMR was used as reference (2D-PISA vs. CMR: mean difference: 15.8 ml [95% CI 10-22, p < 0.001]; and 3D-PISA vs. CMR: 21.5 ml [95% CI 14-29, p < 0.001]). Intra- and inter-observer reliability was excellent (ICC 0.91-0.99), but with numerically lower coefficient of variation for 3D-PISA (8%-10% vs. 2D-PISA: 12%-16%). 3D-PISA method for assessing regurgitation in MVP may enable analogous evaluation compared to standard 2D-PISA, but with overestimation in case of asymmetric FCR or when CMR is used as reference method.

Reproducibility of reading echocardiographic parameters to assess severity of mitral regurgitation. Insights from a French multicentre study

BACKGROUND

Poor reproducibility in assessment of mitral regurgitation (MR) has been reported.

AIM

To investigate the robustness of echocardiographic MR assessment in 2019, based on improvements in technology and the skill of echocardiographists regarding MR quantification.

METHODS

Reproducibility in parameters of MR severity and global rating were tested using transthoracic echocardiography in 25 consecutive patients independently analysed by 16 junior and senior cardiologists specialized in echocardiography (400 analyses per parameter).

RESULTS

Overall interobserver agreement for mechanism definition, effective regurgitant orifice area (EROA) and regurgitant volume (RVol) was moderate, and was lower in secondary MR. Interobserver agreement was substantial for EROA [0.61, 95% confidence interval (CI) 0.45-0.75] and moderate for RVol with the PISA method (0.50, 95% CI 0.33-0.56) in senior physicians and was fair in junior physicians (0.33, 95% CI 0.19-0.51 and 0.36, 95% CI 0.36-0.43, respectively). Using a multiparametric approach, overall interobserver agreement for grading MR severity was fair (0.30), was slightly better in senior than in junior physicians (0.31 vs. 0.28, respectively) with substantial or almost perfect agreement more frequently observed in senior versus junior physicians (52% vs. 36%, respectively).

CONCLUSION

Reproducible transthoracic echocardiography MR quantification remains challenging in 2019, despite the expected high skills of echocardiographers regarding MR at the time of dedicated percutaneous intervention. The multiparametric approach does not entirely alleviate the substantial dispersion in measurement of MR severity parameters, whereas reader experience seems to partially address the issue. Our study emphasizes the continuing need for multimodality imaging and education in the evaluation of MR among cardiologists.

Comparative quantification of primary mitral regurgitation by computer modeling and simulated echocardiography

Clinical investigations have demonstrated that mitral regurgitation (MR) quantification using echocardiography (echo) may significantly underestimate or overestimate the regurgitant volume, especially for two-dimensional (2D) echo. Computer modeling and simulated echo were conducted to evaluate the fundamental assumptions in the echo quantification of primary MR that is due to posterior mitral leaflet prolapse. The theoretical flaw of the proximal isovelocity surface area (PISA) method originates from the assumption that the MR flow rate is the product of the isovelocity surface area and aliasing velocity, which is only valid when the velocity vectors are perpendicular to the isovelocity surface. Other factors such as the Doppler angle effect, the view planes of 2D echo, and the single time instant of PISA were also analyzed. We find that the hemielliptic PISA method gives the smallest error for moderate and severe MR cases compared with other PISA methods. Compared with the PISA method, the volumetric technique (VT) is theoretically more robust. By considering correction factors that are caused by nonflat velocity profiles and the closing volume of the aortic valve, the accuracy of the VT method can be significantly improved. The corrected volumetric technique provides more accurate results compared with the PISA methods, especially for mild MR.NEW & NOTEWORTHY We evaluate the accuracy of common echocardiography techniques for the quantification of primary mitral regurgitations using computer modeling. The hemielliptic proximal isovelocity surface area (PISA) method gives the smallest error (within 15%) for moderate and severe mitral regurgitation cases compared with other PISA methods. The volumetric method is theoretically more robust than the PISA method. The accuracy of the volumetric method can be improved by a correction factor around 0.7 because of the nonflat velocity profiles and the closing volume of the aortic valve.

Clinical Situations Associated with Inappropriately Large Regurgitant Volumes in the Assessment of Mitral Regurgitation Severity Using the Proximal Flow Convergence Method in Patients with Chordae Rupture

BACKGROUND

Regurgitant volume (RVol) calculated using the proximal flow convergence method (proximal isovelocity surface area [PISA]) has been accepted as a key quantitative parameter for the diagnosis of and clinical decision-making with regard to severe mitral regurgitation (MR). However, a recent prospective study showed a significant overestimation of RVol by the echocardiographic PISA method compared with the MR volume measured using magnetic resonance imaging. We aimed to evaluate the frequency of overestimation of RVol by the PISA method and the clinical conditions that require a different quantitative method to correct the overestimation.

METHODS

We retrospectively enrolled 166 consecutive patients with degenerative MR and chordae rupture, in whom RVol was measured using both the PISA and two-dimensional Doppler volumetric methods. The volumetric method was used to measure total stroke volume using the two-dimensional Simpson biplane method, and forward stroke volume was measured using pulsed Doppler tracing at the left ventricular (LV) outflow tract. RVol by the volumetric method was calculated using total stroke volume - forward stroke volume. Severe MR was defined as an RVol >60 mL.

RESULTS

All patients had severe MR based on RVol by the PISA method, but 68 (41.1%) showed RVol by the volumetric method values of <60 mL, resulting in discordant results. The patients with discordant results were characterized by a higher prevalence of female sex, lower body surface area, smaller LV diastolic and systolic dimensions and volumes, smaller left atrial volume, smaller PISA angle, and lower frequency of flail leaflets (39.7% vs 62.2%, P = .004). Multivariate analysis revealed that LV end-diastolic volume (LVEDV) and PISA angle were independent factors, with the best cutoff LVEDV and PISA angle being 173 mL and 103°, respectively. During follow-up (median, 3.4 years; interquartile range, 2.0-4.8 years), mitral valve repair and replacement were performed in 103 and six patients, respectively. The 2-year mitral valve surgery-free survival rate was higher in the discordant group (51.8% ± 0.06% vs 31.2% ± 0.05%, P < .001).

CONCLUSIONS

Even in the patients with documented chordae rupture, the PISA method alone resulted in inappropriate overestimation of MR severity in a significant proportion of patients. Thus, an additive quantitative method is absolutely necessary in patients with a small LVEDV or narrow PISA angle.

A Comparative Assessment of Echocardiographic Parameters for Determining Primary Mitral Regurgitation Severity Using Magnetic Resonance Imaging as a Reference Standard

BACKGROUND

The American Society of Echocardiography (ASE) guidelines suggest the use of several echocardiographic methods to assess mitral regurgitation severity using an integrated approach, without guidance as to the weighting of each parameter. The purpose of this multicenter prospective study was to evaluate the recommended echocardiographic parameters against a reference modality and develop and validate a weighting for each echocardiographic measure of mitral regurgitation severity.

METHODS

This study included 112 patients who underwent evaluation with echocardiography and magnetic resonance imaging (MRI). Echocardiographic parameters recommended by the ASE were included and compared with MRI-derived regurgitant volume (MRI-RV).

RESULTS

Echocardiographic parameters that correlated best with MRI-RV were proximal isovelocity surface area (PISA) radius (r = 0.65, P < .0001), PISA-derived effective regurgitant orifice area (r = 0.65, P < .0001), left ventricular end-diastolic volume (r = 0.56, P < .0001), and PISA-derived regurgitant volume (r = 0.52, P < .0001). In the linear regression models PISA-derived effective regurgitant orifice area, PISA-derived regurgitant volume, left ventricular end-diastolic volume, and the presence of a flail leaflet independently predicted MRI-RV.

CONCLUSION

Echocardiographic parameters of mitral regurgitation as recommended by the ASE had moderate correlations with MRI-RV. The best predictors of MRI-RV were PISA-derived effective regurgitant orifice area, PISA-derived regurgitant volume, left ventricular end-diastolic volume, and the presence of a flail leaflet, suggesting that these parameters should be weighted more heavily than other echocardiographic parameters in the application of the ASE-recommended integrated approach.

Impact of a Geometric Correction for Proximal Flow Constraint on the Assessment of Mitral Regurgitation Severity Using the Proximal Flow Convergence Method

Background

Overestimation of the severity of mitral regurgitation (MR) by the proximal isovelocity surface area (PISA) method has been reported. We sought to test whether angle correction (AC) of the constrained flow field is helpful to eliminate overestimation in patients with eccentric MR.

Methods

In a total of 33 patients with MR due to prolapse or flail mitral valve, both echocardiography and cardiac magnetic resonance image (CMR) were performed to calculate regurgitant volume (RV). In addition to RV by conventional PISA (RV_PISA), convergence angle (α) was measured from 2-dimensional Doppler color flow maps and RV was corrected by multiplying by α/180 (RV_AC). RV measured by CMR (RV_CMR) was used as a gold standard, which was calculated by the difference between total stroke volume measured by planimetry of the short axis slices and aortic stroke volume by phase-contrast image.

Results

The correlation between RV_CMR and RV by echocardiography was modest [RV_CMR vs. RV_PISA (r = 0.712, p < 0.001) and RV_CMR vs. RV_AC (r = 0.766, p < 0.001)]. However, RV_PISA showed significant overestimation (RV_PISA - RV_CMR = 50.6 ± 40.6 mL vs. RV_AC - RV_CMR = 7.7 ± 23.4 mL, p < 0.001). The overall accuracy of RV_PISA for diagnosis of severe MR, defined as RV ≥ 60 mL, was 57.6% (19/33), whereas it increased to 84.8% (28/33) by using RV_AC (p = 0.028).

Conclusion

Conventional PISA method tends to provide falsely large RV in patients with eccentric MR and a simple geometric AC of the proximal constraint flow largely eliminates overestimation.

Assessment of the severity of native mitral valve regurgitation

Mitral regurgitation (MR) is a major cause of cardiovascular morbidity and mortality. MR is classified as primary (organic) if it is due to an intrinsic valve abnormality, or secondary (functional) if the etiology is because of remodeling of left ventricular geometry and/or valve annulus. Transthoracic echocardiography (TTE) is the initial modality for MR evaluation. Parameters used for the assessment of MR include valve structure, cardiac remodeling, and color and spectral Doppler. Quantitative measurements include effective regurgitant orifice area, regurgitant volume, and regurgitant fraction. Knowledge of advantages and limitations of echo-Doppler parameters is essential for accurate results. An integrative approach is recommended in overall grading of MR as mild, moderate, or severe since singular parameters may be affected by several factors. When the mechanism and/or grade of MR is unclear from the TTE or is discrepant with the clinical scenario, further evaluation with transesophageal echocardiography or cardiac magnetic resonance imaging is recommended, the latter emerging as a powerful MR quantitation tool.

Mechanisms of functional mitral regurgitation in ischemic cardiomyopathy determined by transesophageal echocardiography (from the Surgical Treatment for Ischemic Heart Failure Trial)

The mechanisms underlying functional mitral regurgitation (MR) and the relation between mechanism and severity of MR have not been evaluated in a large, multicenter, randomized controlled trial. Transesophageal echocardiography (TEE) was performed in 215 patients at 17 centers in the Surgical Treatment for Ischemic Heart Failure (STICH) trial. Both 2-dimensional (n = 215) and 3-dimensional (n = 81) TEEs were used to assess multiple quantitative measurements of the mechanism and severity of MR. By 2-dimensional TEE, leaflet tenting area, anterior and posterior leaflet angles, mitral annulus diameter, left ventricular (LV) end-systolic volume index, LV ejection fraction (LVEF), and sphericity index (p <0.05 for all) were significantly different across MR grades. By 3-dimensional TEE, mitral annulus area, leaflet tenting area, LV end-systolic volume index, LVEF, and sphericity index (p <0.05 for all) were significantly different across MR grades. A multivariate analysis showed a trend for annulus area (p = 0.069) and LV end-systolic volume index (p = 0.071) to predict effective regurgitant orifice area and for annulus area (p = 0.018) and LV end-systolic volume index (p = 0.073) to predict vena contracta area. In the STICH trial, multiple quantitative parameters of the mechanism of functional MR are related to MR severity. The mechanism of functional MR in ischemic cardiomyopathy is heterogeneous, but no single variable stands out as a strong predictor of quantitative severity of MR.

Comparison of accuracy of mitral valve regurgitation volume determined by three-dimensional transesophageal echocardiography versus cardiac magnetic resonance imaging

Direct planimetry of anatomic regurgitation orifice area (AROA) using 3-dimensional transesophageal echocardiography (TEE) has been described. This study sought to (1) compare mitral valve regurgitant volume (RV) derived by AROA using 3-dimensional TEE with RV obtained by cardiac magnetic resonance (CMR) imaging and (2) determine the impact of AROA and flow velocity changes throughout systole on the dynamic variation in mitral regurgitation. In 43 patients (71 ± 11 years old) with mild to severe mitral regurgitation, 3-dimensional TEE and CMR were performed. Mitral valve RV was determined based on (1) AROA at 5 subintervals of systole and analysis of the regurgitant continuous-wave Doppler signal at equal durations of systole, (2) effective regurgitation orifice area (EROA) using the proximal isovelocity surface area method, (3) CMR with subtraction of aortic outflow volume from left ventricular stroke volume. RV calculated by AROA tended to overestimate RV less than RV calculated by EROA compared to RV by CMR (average bias +20 ml, 95% confidence interval [CI] -41 to +81, vs +13 ml, 95% CI -22 to 47). In patients with RV >30 ml by CMR, overestimation of RV using the AROA method was less than using the EROA method (difference in means +18 ml, 95% CI 4 to 32, p <0.001). AROA determined by 3-dimensional TEE varied by only 18% among the 5 subintervals of systole, and the velocity time integral of the subinterval with the highest flow was 120% of the subinterval with the lowest flow. In conclusion, 3-dimensional TEE allows accurate analysis of mitral valve RV. In the clinically relevant group of patients with RV >30 ml as defined by CMR, the AROA method results in less overestimation of RV than the EROA method. Changes in AROA during systole contribute much less to dynamic variation in mitral regurgitation severity than changes in regurgitant flow velocity.

Mechanism and severity of mitral regurgitation by transesophageal echocardiography in patients referred for percutaneous valve repair

Percutaneous mitral valve repair with the MitraClip has been shown to decrease mitral regurgitation (MR) severity, left ventricular volumes, and functional class in patients with severe (3+ or 4+) MR. Determination of which patients are optimal candidates for MitraClip therapy versus surgery has not been rigorously evaluated. Transesophageal echocardiography was prospectively performed in 113 consecutive patients referred for potential MitraClip therapy under the REALISM continued access registry. MR severity was assessed quantitatively in all patients. Mitral valve anatomy and feasibility of MitraClip placement were assessed by transesophageal echocardiography and clinical parameters. MR was degenerative (mitral valve prolapse) in 60 patients (53%), functional (anatomically normal) in 44 (39%), and thickened with restricted motion (Carpentier IIIB classification) in 9 (8%). MR was mild in 19 patients (17%), moderate in 27 (24%), and severe (3 to 4+) in 67 (59%) by Transesophageal echocardiography. MitraClip placement was performed in only 17 of 113 patients (15%); all were successful. Surgical mitral valve repair was performed in 25 patients (22%), mitral valve replacement in 12 (11%). Most patients (59 of 113, 52%) were treated medically, usually because MR was not severe enough to warrant intervention. In conclusion, most patients referred for MitraClip therapy do not have severe enough MR to warrant intervention. Of those with clinical need for intervention, surgery is more often recommended for anatomic or clinical reasons. Three-dimensional transesophageal echocardiography with quantitative assessment of MR severity is helpful in evaluating these patients.

Comparison of direct planimetry of mitral valve regurgitation orifice area by three-dimensional transesophageal echocardiography to effective regurgitant orifice area obtained by proximal flow convergence method and vena contracta area determined by color Doppler echocardiography

Direct measurement of anatomic regurgitant orifice area (AROA) by 3-dimensional transesophageal echocardiography was evaluated for analysis of mitral regurgitation (MR) severity. In 72 patients (age 70.6 ± 13.3 years, 37 men) with mild to severe MR, 3-dimensional transesophageal echocardiography and transthoracic color Doppler echocardiography were performed to determine AROA by direct planimetry, effective regurgitant orifice area (EROA) by proximal convergence method, and vena contracta area (VCA) by 2-dimensional color Doppler echocardiography. AROA was measured with commercially available software (QLAB, Philips Medical Systems, Andover, Massachusetts) after adjusting the first and second planes to reveal the smallest orifice in the third plane where planimetry could take place. AROA was classified as circular or noncircular by calculating the ratio of the medial-lateral distance above the anterior-posterior distance (≤1.5 compared to >1.5). AROA determined by direct planimetry was 0.30 ± 0.20 cm², EROA determined by proximal convergence method was 0.30 ± 0.20 cm², and VCA was 0.33 ± 0.23 cm². Correlation between AROA and EROA (r = 0.96, SEE 0.058 cm²) and between AROA and VCA (r = 0.89, SEE 0.105 cm²) was high considering all patients. In patients with a circular regurgitation orifice area (n = 14) the correlation between AROA and EROA was better (r = 0.99, SEE 0.036 cm²) compared to patients with noncircular regurgitation orifice area (n = 58, r = 0.94, SEE 0.061 cm²). Correlation between AROA and EROA was higher in an EROA ≥0.2 cm² (r = 0.95) than in an EROA <0.2 cm² (r = 0.60). In conclusion, direct measurement of MR AROA correlates well with EROA by proximal convergence method and VCA. Agreement between methods is better for patients with a circular regurgitation orifice area than in patients with a noncircular regurgitation orifice area.

Accuracy of the flow convergence method for quantification of aortic regurgitation in patients with central versus eccentric jets

Proximal isovelocity surface area (PISA) has been proposed as a quantitative method to assess the severity of aortic regurgitation (AR). Yet the accuracy of this method in patients with eccentric AR jets is unknown. The aims of this study were to compare the accuracy of the PISA method for the quantification of AR severity in patients with central versus eccentric AR jets and to verify whether imaging from the left parasternal instead of the apical window improves the accuracy of the PISA method in patients with eccentric jets. Fifty patients with AR (21 with central jets and 29 with eccentric jets) underwent PISA and phase-contrast cardiac magnetic resonance (CMR) measurements of AR volume. In patients with eccentric AR jets, PISA measurements obtained from the left parasternal and apical windows were compared. In patients with central AR jets, CMR- and PISA-derived AR volumes were similar (28 +/- 19 vs 30 +/- 20 ml, p = 0.34), were strongly correlated (r = 0.92, p <0.0001), and differed minimally from each other (by 2 +/- 8 ml). In patients with eccentric AR jets, PISA-derived AR volumes underestimated those measured by CMR (38 +/- 22 vs 51 +/- 27 ml, bias -13 +/- 20 ml) and were correlated only fairly (r = 0.69, p <0.001). Imaging from the left parasternal window eliminated the differences between CMR- and PISA-derived AR volumes (51 +/- 27 vs 53 +/- 26 ml, p = 0.24) and improved the correlation between the 2 measures (r = 0.95). In conclusion, in patients with eccentric AR jets imaged from the apical window, the PISA method significantly underestimated AR severity. This was no longer the case when imaging was performed from the left parasternal instead of the apical window.

Diagnostic Value of Color Flow Mapping and Doppler Echocardiography in the Quantification of Mitral Regurgitation in Patients with Mitral Valve Prolapse or Rheumatic Heart Disease

OBJECTIVES

The objective was to analyze the diagnostic value of the echocardiographic methods used for quantification of mitral regurgitation (MR) in patients with mitral valve prolapse (MVP) or rheumatic heart disease (RHD).

METHODS

The study included 50 patients with MR (mean age of 46.1 years; 35 women), 27 (54%) with RHD and 23 (46%) with MVP. Quantification of the mitral valve regurgitation was obtained by regurgitant orifice area (ROA) and regurgitant volume (RV) by the flow convergence region (FCR) and two-dimensional Doppler echocardiographic methods, regurgitant fraction, jet area (JA), jet area/left atrial area ratio (JA/LAA), and vena contracta (VC). Patients were clinically followed to identify cardiovascular events. Data were analyzed by Pearson, kappa, and receiver operator characteristic curve tests; significance was defined as a P value less than .05.

RESULTS

The correlation between the two methods for ROA and RV were r = 0.79 and r = 0.80, respectively, and between these parameters and regurgitant fraction, VC, JA, and JA/LAA varied from r = 0.54 to r = 0.94 (P lt; .05); the agreement varied from kappa = 0.19 to kappa = 0.83. The highest accuracy to identify patients with clinically significant MR (events at follow-up) was 96% for ROA by FCR, 94% for VC, 86% for RV by FCR, and 86% for JA. No method showed a significant difference between MVP and RHD.

CONCLUSIONS

The methods analyzed had significant correlation and good agreement. ROA by FCR and VC had the best performance to identify severe MR; no significant difference between MVP and RHD was observed.

Quantification of mitral regurgitation by the proximal flow convergence method--comparison of transthoracic and transesophageal echocardiography

BACKGROUND

No dataexist to indicate whether transthoracic (TTE) and transesophageal echocardiography (TEE) are of comparable value for the detection and quantification of mitral regurgitation using the proximal flow convergence method.

HYPOTHESIS

The study was performed to compare the value of TTE and TEE for the detection and quantification of mitral regurgitation using this method.

METHODS

The study included 57 patients with and 11 patients without mitral regurgitation. In all patients, the proximal flow convergence region was imaged by transthoracic and transesophageal color Doppler echocardiography, and proximal isovelocity surface area radii were determined. In 19 patients, monoplane TEE and in 49 patients multiplane TEE was performed. Thirty-one patients with mitral regurgitation underwent cardiac catheterization.

RESULTS

Both methods had a comparable sensitivity for the detection of mitral regurgitation. Proximal isovelocity surface area radii derived from TTE and TEE agreed moderately (mean difference -0.5 +/- 1.3 mm). TTE and TEE correlated significantly with the angiographic grade (rank correlation coefficients 0.83 and 0.81), and both differentiated mild to moderate from severe mitral regurgitation with an accuracy of 90%. Regurgitant volumes derived from both echocardiographic techniques and cardiac catheterization correlated moderately (correlation coefficients between 0.67 and 0.81).

CONCLUSIONS

TTE and TEE were of comparable value for the detection and quantification of mitral regurgitation using the proximal flow convergence method.

A practical approach to the quantification of valvular regurgitation

This article reviews the methods of determining the severity of mitral and aortic regurgitation, primarily the quantitation using Doppler echocardiography. The Doppler methods, including spatial mapping, proximal flow convergence, vena contracta, continuous-wave Doppler density, and upstream or downstream effects are explained. Various practical pitfalls and performance issues that impact the reliability of these techniques are discussed.

Assessment of left ventricular function by cardiac ultrasound

Our understanding of the physical underpinnings of the assessment of cardiac function is becoming increasingly sophisticated. Recent developments in cardiac ultrasound permit exploitation of many of these newer physical concepts with current echocardiographic machines. This review will first focus on the current approach to the assessment of cardiovascular hemodynamics by cardiac ultrasound. The next focus will be the assessment of global cardiac mechanics in systole and diastole. Finally, relationships between the cardiac structure and regional myocardial function, and the way regional function can be quantified by ultrasound, will be presented. This review also discusses the clinical impact of echocardiography and its future directions and developments.

An initial application of transesophageal Doppler echocardiography in experimental small animal models

This study examined whether an intracardiac echocardiography catheter could be used for transesophageal echocardiography (TEE) examinations in normal rats, and intraoperative TEE in small animal models of disease. The study used 30 Sprague-Dawley normal rats, 10 rats undergoing coronary artery ligation, and 10 rats with experimentally induced mitral regurgitation. The rats were anesthetized with isoflurane and intubated. An intracardiac echocardiographic catheter was inserted into the esophagus. M-mode, 2-dimensional, and Doppler studies were performed in multiple views. TEE probe insertions were successful in all animals. Intraoperative TEE was safely performed in the rat models of myocardial infarction or mitral regurgitation. Mitral regurgitation was well assessed using color Doppler and pulmonary venous flow. This study demonstrates that TEE (including intraoperative TEE) can be safely performed in rats using an intracardiac echocardiographic catheter. It provides a new approach to the assessment of cardiac function and valvular regurgitation in small animals.

Transthoracic and Transesophageal Echocardiographic Assessment of Mitral Regurgitation Severity: Usefulness of Qualitative and Semiquantitative Techniques

In this report, we review the advantages, limitations, and optimal utilization of various transthoracic and transesophageal echocardiographic (TTE and TEE) methods used for assessing mitral regurgitation (MR) as published in full-length, peer-reviewed articles since the color Doppler era began in 1984. In addition, comparison is made to other imaging modalities including catheter-based, magnetic resonance and surgical assessment of MR. Although left ventricular (LV) angiography has been traditionally used for validation of various TTE methods and is time-honored, its considerable limitations preclude it from being a real "gold standard." Based on the reviewed literature, no clear "gold standard" for the assessment of MR can be identified at present, but newly emerging TTE and TEE techniques, such as three-dimensional color Doppler, may have the potential to overcome some of the limitations of the two-dimensional methods.

Development of a new animal model of chronic mitral regurgitation in rats under transesophageal echocardiographic guidance

Large animal models (dog and sheep) are often used for the investigation of the pathophysiology of chronic mitral regurgitation (MR). A major limitation of large animal models is cost. The aim of this study was to develop a new animal model of chronic MR. Left thoracotomy was performed in 34 rats. Under the guidance of transesophageal echocardiography, a fine needle was inserted into the left ventricle (LV) to damage the mitral leaflets and produce MR. Serial transthoracic echocardiography was performed to assess LV remodeling and function. Left atrial and LV diameters were significantly larger, and LV fractional shortening was lower in the MR group than in the sham group. The 150-day survival was 59% in the MR group and 100% in the sham group (P < .01). This new animal model of chronic MR may be used in the study of the pathophysiology of chronic MR and pharmacologic therapies.

Value of the proximal flow convergence method for quantification of the regurgitant volume in mitral regurgitation Influence of the mechanism of regurgitation, the imaging of the flow convergence region, and different calculation modalities

The purpose of this study was to evaluate whether the underlying mechanism of mitral regurgitation influences the reliability of the proximal flow con- vergence method to assess the regurgitant volume. Furthermore, the mode of imaging the flow convergence region and different correction algorithms for calculation of the regurgitant volume were compared.

METHODS

Regurgitant volume was assessed in 45 patients (age 61+/-13 years) with organic (n=19) and functional (n=26) mitral regurgitation by the proximal flow convergence method for aliasing velocities between 14 and 64 cm/s using two-dimensional color Doppler imaging. Different correction and calculation algorithms were compared. In addition, regurgitant volume was determined using color Doppler M-mode for an aliasing velocity of 28 cm/s. The quantitative Doppler method was used as reference.

RESULTS

In organic mitral regurgitation correlation coefficients (mean differences) between the proximal flow convergence method and the reference method were 0.25-0.43/ 0.58-0.67 (46-111 ml/15-17 ml) before/after geometric correction of the regurgitant volume for the aliasing velocities investigated. The correlation coefficient (mean difference) using color Doppler M-mode imaging was 0.68 (85 ml). The corresponding values in functional mitral regurgitation were 0.74-0.88/0.74-0.88 (-5-8 ml/-7-5 ml) for two-dimensional color Doppler and 0.88 (-1 ml) for M-mode imaging.

CONCLUSIONS

The regurgitant volume was overestimated by the proximal flow convergence method in organic mitral regurgitation irrespective of the application of different correction algorithms or the use of color Doppler M-mode. A sufficiently reliable determination of the regurgitant volume by the proximal flow convergence method was possible in functional mitral regurgitation. In that case a simplified calculation of the regurgitant volume based on the proximal flow convergence method was feasible.

Determinant of left atrial dilation in patients with hypertrophic cardiomyopathy: A real-time 3-dimensional echocardiographic study

To identify the determinants of left atrial (LA) dilation for patients with hypertrophic obstructive cardiomyopathy (HOCM), first we validated LA volume determination by real-time 3-dimensional echocardiography using magnetic resonance imaging in patients. Subsequently, real-time 3-dimensional echocardiography and 2-dimensional Doppler echocardiography were performed in 60 patients with HOCM and in 17 age-matched control subjects. LA volumes and left ventricular (LV) filling pressures were higher for patients with HOCM than in control subjects. By stepwise multilinear regression analysis, LV end-diastolic pressure, resting LV outflow tract pressure gradient, and LV wall thickness were significant determinants of LA dilation. However, tau, -dP/dt, LV stiffness, provokable pressure gradient, and mitral regurgitation did not have any independent relationship with LA volumes. Therefore, it is concluded that LA volume can be accurately determined by real-time 3-dimensional echocardiography; and LA dilation in patients with HOCM is related to LV filling pressure, LV outflow tract pressure gradient, and LV wall thickness.

Assessment of severity of mechanical prosthetic mitral regurgitation by transoesophageal echocardiography

OBJECTIVE

To evaluate the ability of colour Doppler transoesophageal echocardiography (TOE) to assess quantitatively prosthetic mitral valve insufficiency.

METHODS

47 patients were studied with multiplane TOE and cardiac catheterisation. Proximal jet diameter was measured as the largest diameter of the vena contracta. Regurgitant area was measured by planimetry of the largest turbulent jet during systole. Flow convergence zone was considered to be present when a localised area of increased systolic velocities was apparent on the left ventricular side of the valve prosthesis. Pulmonary vein flow velocity was measured at peak systole and diastole.

RESULTS

Mean (SD) proximal jet diameter was 0.63 (0.16) cm, with good correlation with angiographic grades (r = 0.83). Mean (SD) maximum colour jet area was 7.9 (2.5) cm2 (r = 0.69) with worse correlation if a single imaging plane was used for measurements (r = 0.62). The ratio of systolic to diastolic peak pulmonary flow velocity averaged 0.7 (1.3) cm (r = -0.66) with better correlation (r = -0.71) if patients with atrial fibrillation were excluded. Mean (SD) regurgitant flow rate was 168 (135) ml/s and regurgitant orifice area was 0.56 (0.43) cm2, with good correlation with angiography (r = 0.77 and r = 0.78, respectively).

CONCLUSIONS

TOE correctly identified angiographically severe prosthetic mitral regurgitation, mainly by the assessment of the flow convergence region and the proximal diameter of the regurgitant jet.

Reproducibility of the proximal flow convergence method in mitral and tricuspid regurgitation

BACKGROUND

The follow-up of patients with mitral and tricuspid regurgitation is important for their clinical treatment. We aimed to evaluate the reproducibility of the flow convergence method in mitral and tricuspid regurgitation.

METHODS

The proximal flow convergence region was imaged with color Doppler ultrasound scanning echocardiography in 83 patients with mitral regurgitation, tricuspid regurgitation, or both. Proximal isovelocity surface area radii for aliasing velocities of 27 to 29 cm/s and 41 to 43 cm/s were repeatedly measured by the same experienced investigator on different days and by experienced and less experienced investigators at 1 day.

RESULTS

In mitral regurgitation, the intraobserver variability rate was 0.2% +/- 13.5% (2.8% +/- 13.3%) and the interobserver variability was 0.1% +/- 13.8% (1.7% +/- 18.0%) for an aliasing velocity of 27 to 29 cm/s (41-43 cm/s). For the aliasing velocity of 27 to 29 cm/s (41-43 cm/s), the 95% ranges for change of the proximal isovelocity surface area radii were +/- 2.7 mm (+/- 1.8 mm) for measurements repeated by the same investigator and +/- 2.7 mm ( +/- 2.4 mm) for different investigators. Interobserver variability was independent of the investigators' experience. Similar data were achieved in tricuspid regurgitation.

CONCLUSIONS

The proximal flow convergence method is acceptably reproducible in mitral and tricuspid regurgitation independent of the investigators experience. For the aliasing velocity of 27 to 29 cm/s (41-43 cm/s), the proximal isovelocity surface area radius has to change for >2.7 (2.4) mm before an altered severity of mitral or tricuspid regurgitation in a single patient can be assumed.

Color flow imaging of the vena contracta in mitral regurgitation: technical considerations

Qualitative grading of mitral regurgitation severity has significant pitfalls secondary to hemodynamic variables, sonographic technique, blood pool entrainment, and the Coanda effect. Volumetric and proximal isovelocity surface area methods can be used to quantitate regurgitant orifice area, regurgitant volume, and regurgitant fraction, but have several limitations and can pose technical challenges. The vena contracta width method provides a rapid and accurate quantitative assessment of mitral regurgitation severity, but is clinically underused. This article is intended to generate an understanding of the flow mechanics of the vena contracta and the sonographic technique required to provide consistent and accurate measurements of vena contracta width in patients with mitral regurgitation.

Determinants of the development of mitral regurgitation in pacing-induced heart failure

The pacing-induced heart failure model provides an opportunity to assess the structural and functional determinants of mitral regurgitation (MR) in dilated cardiomyopathy. This study aimed to evaluate MR to better understand the multitude of factors contributing to its development. Heart failure was induced by rapid ventricular pacing (230 beats/min) in 40 mongrel dogs. Left ventricular (LV) size and MR were evaluated echocardiographically. LV contractility was analyzed using a conductance catheter. MR increased to mild in 12 animals (regurgitant orifice area, 0.06+/-0.05 cm(2)), moderate in 15 (0.14+/-0.07 cm(2)), and severe in 13 (0.34+/-0.16 cm(2)). The grade of MR had an inverse relationships with E(max) (the slope of the end-systolic pressure-volume relationship, p<0.01) and dE/dt (the slope of the maximum rate of change of pressure-end-diastolic volume [V(ED)] relationship, p<0.01) and positive relationships with V(ED) and end-diastolic cross-sectional areas and lengths (p<0.05) by univariate analysis. The dE/dt had an independently significant (p<0.01) relationship by multivariable logistic regression. Many factors influence the development of MR and because of its similarity to the clinical situation, this model can be used to investigate MR and heart failure, as well as new surgical therapies.

Real-time three-dimensional color doppler evaluation of the flow convergence zone for quantification of mitral regurgitation: Validation experimental animal study and initial clinical experience

BACKGROUND

Pitfalls of the flow convergence (FC) method, including 2-dimensional imaging of the 3-dimensional (3D) geometry of the FC surface, can lead to erroneous quantification of mitral regurgitation (MR). This limitation may be mitigated by the use of real-time 3D color Doppler echocardiography (CE). Our objective was to validate a real-time 3D navigation method for MR quantification.

METHODS

In 12 sheep with surgically induced chronic MR, 37 different hemodynamic conditions were studied with real-time 3DCE. Using real-time 3D navigation, the radius of the largest hemispherical FC zone was located and measured. MR volume was quantified according to the FC method after observing the shape of FC in 3D space. Aortic and mitral electromagnetic flow probes and meters were balanced against each other to determine reference MR volume. As an initial clinical application study, 22 patients with chronic MR were also studied with this real-time 3DCE-FC method. Left ventricular (LV) outflow tract automated cardiac flow measurement (Toshiba Corp, Tokyo, Japan) and real-time 3D LV stroke volume were used to quantify the reference MR volume (MR volume = 3DLV stroke volume - automated cardiac flow measurement).

RESULTS

In the sheep model, a good correlation and agreement was seen between MR volume by real-time 3DCE and electromagnetic (y = 0.77x + 1.48, r = 0.87, P <.001, delta = -0.91 +/- 2.65 mL). In patients, real-time 3DCE-derived MR volume also showed a good correlation and agreement with the reference method (y = 0.89x - 0.38, r = 0.93, P <.001, delta = -4.8 +/- 7.6 mL).

CONCLUSIONS

real-time 3DCE can capture the entire FC image, permitting geometrical recognition of the FC zone geometry and reliable MR quantification.

Quantification of mitral regurgitation orifice area by 3-dimensional echocardiography: comparison with effective regurgitant orifice area by PISA method and proximal regurgitant jet diameter

BACKGROUND

The evaluation of mitral regurgitation (MR) by 3-dimensional (3D) echo has generally been performed by reconstruction of Doppler regurgitant jets but there are little data on measuring anatomic regurgitant orifice area (AROA) directly from 3D mitral valve (MV) reconstructions.

METHODS AND RESULTS

Transoesophageal echo (TOE) 3D images were acquired from 38 unselected patients (age 59+/-11 years, ten in atrial fibrillation) with various degrees of MR. In all patients MV was reconstructed en face from the left atrium (LA) and the left ventricle (LV). AROA was measured by planimetry from 3D pictures and compared to the effective regurgitant orifice area (EROA) by proximal isovelocity surface area and proximal MR jet width from 2D echo. AROA was measured in 95% of patients from LA, 89% from LV and in 84% from both LA and LV. Good correlation was found between EROA and AROA measured from both LA (r=0.97, P<0.0001) and LV (r=0.87, P<0.0001). The mean difference between LA-AROA and EROA was -3.01+/-6.12 mm(2) and -7.18+/-13.84 mm(2) for LV-AROA (P<0.01, respectively). An acceptable correlation was found between the proximal MR jet width and AROA from LA (r=0.71, P<0.0001) and LV perspective (r=0.68, P<0.0001). AROA>or=25 mm(2) differentiated mild MR (graded 1-2) from moderately severe (graded 3-4) with 80-90% accuracy.

CONCLUSIONS

3D TOE provides important quantitative information on both the mechanism and the severity of MR in an unselected group of patients. AROA enables quantification of MR with excellent agreement with the accepted clinical method of proximal flow convergence.

Contrasting effect of similar effective regurgitant orifice area in mitral and tricuspid regurgitation: a quantitative Doppler echocardiographic study

We compared the effect of similar effective regurgitant orifice (ERO) areas in tricuspid regurgitation (TR) and mitral regurgitation (MR) on hemodynamics and volume overload, and examined the impact on grading of TR and MR severity. In a prospective study, 95 patients with TR in sinus rhythm were compared with 95 patients with MR in sinus rhythm matched for ERO area, age, and body surface area. We found that similar ERO area was associated with decreased volume overload in TR compared with MR. There were more women with TR than with MR, but comparison stratified by sex confirmed that regurgitant volume (RVol) was smaller in TR than in MR for similar ERO area. However, patients with systolic venous flow reversal (hepatic for TR and pulmonary for MR) had lower RVol but similar ERO area in TR compared with MR. Therefore, optimal diagnostic thresholds for severe regurgitation (maximum sum of sensitivity and specificity) in TR and MR were different for RVol (45 and 60 mL/beat, respectively) but similar for ERO area (40 mm(2)). We conclude that similar ERO areas induce less RVol in TR than in MR because of the decreased driving force in TR, but have similar consequences with regard to venous flow reversal. Therefore, a similar ERO area grading scheme can be used, and an ERO area of 40 mm(2) or greater is consistent with severe regurgitation in both TR and MR.

Quantitative assessment of regurgitant flow with total digital three-dimensional reconstruction of color Doppler flow in the convergent region: in vitro validation

BACKGROUND

This study was designed to develop and test a total digital 3-dimensional (3D) color flow map reconstruction for proximal isovelocity surface area (PISA) measurement in the convergent region.

METHODS

Asymmetric flow convergent velocity field was created in an in vitro pulsatile model of mitral regurgitation. Image files stored in the echocardiographic scanner memory were digitally transferred to a computer workstation, and custom software decoded the file format, extracted velocity information, and generated 3D flow images automatically. PISA and volume flow rate were calculated without geometric assumption. For comparison, regurgitant volume was also calculated, using continuous wave Doppler, 2-dimensional (2D), and M-mode color flow Doppler with the hemispheric approach.

RESULTS

Flows from 3D digital velocity profiles showed a closed, excellent relation with actual flow rates, especially for instantaneous flow rate. Regurgitant volume calculated with the 3D method underestimated the actual flow rate by 2.6%, whereas 2D and the M-mode method show greater underestimation (44.2% and 32.1%, respectively).

CONCLUSION

Our 3D reconstruction of color flow Doppler images gives more exact information of the flow convergent zone, especially in complex geometric flow fields. Its total digital velocity process allows accurate measurement of convergent surface area and improves quantitation of valvular regurgitation.