Application of color Doppler flow mapping to calculate effective regurgitant orifice area. An in vitro study and initial clinical observations

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.

Benefit of 3D Vena Contracta Area over 2D-Based Echocardiographic Methods in Quantification of Functional Mitral Valve Regurgitation

BACKGROUND

The two-dimensional proximal isovelocity surface area (2D PISA) method in the quantification of an effective regurgitation orifice area (EROA) has limitations in functional mitral valve regurgitation (FMR), particularly in non-circular coaptation defects.

OBJECTIVE

We aimed to validate a three-dimensional vena contracta area (3D VCA) against a conventional EROA using a 2D PISA method and anatomic regurgitation orifice area (AROA) in patients with FMR.

METHODS

Both 2D and 3D full-volume color Doppler data were acquired during consecutive transoesophageal echocardiography (TEE) examinations. The EROA 2D PISA was calculated as recommended by current guidelines. Multiplanar reconstruction was used for offline analysis of the 3D VCA (with a color Doppler) and AROA (without a color Doppler). Receiver operating characteristic (ROC) analysis was used to calculate a cut-off value for the 3D VCA to discriminate between moderate and severe FMR as classified by the EROA 2D PISA.

RESULTS

From 2015 to 2018, 105 consecutive patients with complete and adequate imaging data were included. The 3D VCA correlated strongly with the 2D PISA EROA and AROA (r = 0.93 and 0.94). In the presence of eccentric or multiple regurgitant jets, there was no significant difference in correlations with the 3D VCA. We found a 3D VCA cut-off of 0.43 cm² to discriminate between moderate and severe FMR (area under curve = 0.98). The 3D VCA showed a higher interobserver agreement than the EROA 2D PISA (interclass correlation coefficient: 0.94 vs. 0.81).

CONCLUSIONS

The 3D VCA has excellent validity and lower variability than the conventional 2D PISA in FMR. Compared to the 2D PISA, the 3D VCA was not affected by the presence of eccentric or multiple regurgitation jets or non-circular regurgitation orifices. With a threshold of 0.43 cm² for the 3D VCA, we demonstrated reliable discrimination between moderate and severe FMR.

Computational Analysis of Virtual Echocardiographic Assessment of Functional Mitral Regurgitation for Validation of Proximal Isovelocity Surface Area Methods

BACKGROUND

Mitral regurgitation (MR) quantification by the proximal isovelocity surface area (PISA) method remains challenging. Using computer models, the authors evaluated the accuracy of different PISA methods and quantified their errors.

METHODS

Five functional MR computer models of different geometric and tethering abnormalities were created, validated, and treated as phantom models, from which the reference values were directly obtained. Virtual two-dimensional (2D) PISA and three-dimensional (3D) PISA (both peak and integrated values) were performed on these phantom models. By comparing virtual PISA results with reference values, the accuracy of different PISA methods was evaluated, and their sources of errors were quantified.

RESULTS

Compared with reference values of regurgitant flow rate, excellent correlations were found for true PISA (r = 0.99, bias = 32.3 ± 35.3 mL/sec), 3D PISA (r = 0.97, bias = -24.4 ± 55.5 mL/sec), followed by multiplane 2D hemicylindrical PISA (r = 0.88, bias = -24.1 ± 85.4 mL/sec) and hemiellipsoidal PISA (r = 0.91, bias = -55.7 ± 96.6 mL/sec). Weaker correlations were found for single-plane 2D hemispherical PISA (parasternal long-axis: r = 0.71, bias = -77.6 ± 124.5 mL/sec; apical two-chamber: r = 0.69, bias = -52.0 ± 122.0 mL/sec; apical four-chamber: r = 0.82, bias = -65.5 ± 107.3 mL/sec). For regurgitant volume quantification, integrated PISA was more accurate than peak PISA. The bias of 3D PISA improved from -12.7 ± 7.8 mL (peak PISA) to -2.1 ± 5.3 mL (integrated PISA).

CONCLUSIONS

For functional MR quantification, 2D hemispherical PISA had significant underestimation, multiplane 2D hemiellipsoidal and hemicylindrical PISA showed improved accuracy, and 3D PISA was the most accurate. The PISA method is subject to both systematic underestimation due to the Doppler angle effect and systematic overestimation when regurgitant flow is not perpendicular to PISA contour. Integrated PISA is able to capture dynamic MR and is therefore more accurate than peak PISA. The sum of regurgitant flow rates is the most feasible way to perform integrated PISA.

Clinical Significance and Prognostic Value of Novel Echocardiographic Index for the Severity of Mitral Regurgitation

Background: Recently, the left ventricular early inflow-outflow index (LVEIO), calculated by dividing mitral E-wave velocity by the left ventricular outflow velocity time integral, has been proposed as a simple method for evaluating mitral regurgitation (MR). This study determined the optimal LVEIO threshold to assess severe MR with different etiologies and assessed its prognostic value.

Methods and Results: The records of 18,692 consecutive patients who underwent echocardiography were reviewed. MR was classified into 4 groups: Grade 0/1, no, trivial, or mild MR; Grade 2, moderate MR; Grade 3, moderate to severe MR; and Grade 4, severe MR. The mean (±SD) LVEIO of Grades 0/1, 2, 3, and 4 was 3.6±1.4, 6.0±2.5, 7.4±3.1, and 9.5±2.8, respectively. An optimal LVEIO threshold of 5.4 was determined to distinguish moderate to severe or severe MR from non-severe MR (sensitivity 84%, specificity 91%). Kaplan-Meier survival analysis revealed high mortality in the group with LVEIO ≥5.4 (P=0.009, hazard ratio 1.833). This was found only in primary MR when separate analyses were performed according to etiology. Multivariate analysis revealed that LVEIO was an independent predictor for all-cause death only in primary MR.

Conclusions: Using appropriate thresholds, LVEIO is a simple and useful method to diagnose severe MR regardless of etiology. LVEIO can also be useful for predicting prognosis in primary MR.

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.

Prognostic Implications of Magnetic Resonance-Derived Quantification in Asymptomatic Patients With Organic Mitral Regurgitation: Comparison With Doppler Echocardiography-Derived Integrative Approach

BACKGROUND

Magnetic resonance imaging (MRI) is an accurate method for the quantitative assessment of organic mitral regurgitation (OMR). The aim of the present study was to compare the discriminative power of MRI quantification and the recommended Doppler echocardiography (ECHO)-derived integrative approach to identify asymptomatic patients with OMR and adverse outcome.

METHODS

The study population consisted of 258 asymptomatic patients (63±14 years, 60% men) with preserved left ventricular ejection fraction (>60%) and chronic moderate and severe OMR (flail 25%, prolapse 75%) defined by using the ECHO-derived integrative approach. All patients underwent MRI to quantify regurgitant volume (RV) of OMR by subtracting the aortic forward flow volume from the total left ventricular stroke volume. Severe OMR was defined as RV≥60 mL.

RESULTS

Mean ECHO-derived RV was on average 17.1 mL larger than the MRI-derived RV (P<0.05). Concordant grading of OMR severity with both techniques was observed in 197 (76%) individuals with 62 (31%) patients having severe OMR (MRI SEV-ECHO SEV) and 135 (69%) patients having moderate OMR (MRI MOD-ECHO MOD). The remaining 61 (24%) individuals had discordant findings (MRI SEV-ECHO MOD or MRI MOD-ECHO SEV) between the 2 techniques. The majority of these differences in OMR classification were observed in patients with late systolic or multiple jets (both κ<0.2). Patients with eccentric jets showed moderate agreement (κ=0.53; 95% confidence interval, 0.41-0.64). In contrast, a very good agreement (κ=0.90; 95% confidence interval, 0.82-0.98) was observed in a combination of holosystolic, central, and single jet. During a median follow-up of 5.0 years (interquartile range, 3.5-6.0 years), 38 (15%) patients died and 106 (41%) either died or developed indication for mitral valve surgery. In separate Cox regression analyses, the MRI-derived left ventricular end-systolic volume index, RV, and OMR category (severe versus moderate), and the ECHO-derived OMR category were independent predictors of all-cause mortality (all P<0.05). The MRI-derived RV showed the largest area under the curve to predict mortality (0.72) or its combination with the development of indication for mitral valve surgery (0.83).

CONCLUSIONS

The findings of the present study suggest that the MRI-derived assessment of OMR can better identify patients with severe OMR and adverse outcome than ECHO-derived integrative approach warranting close follow-up and perhaps, early mitral valve surgery.

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.

Evaluation of Mitral Regurgitation

Transesophageal echocardiography (TEE) provides high-resolution images of the mitral valve apparatus, permitting detailed evaluation of its structure and function. Mitral valve evaluation is invaluable during mitral valve repair surgery, providing insight into the mechanism of valve dysfunction and formulation of a plan for repair. TEE provides immediate detection of inadequate repair after bypass and allows correction during the same operative setting. Intraoperative TEE is a valuable tool for improving patient outcome and offers the cardiovascular anesthesiologist a role in perioperative surgical decisions.

ASSESSMENT OF MITRAL REGURGITATION THROUGH DOPPLER ECHOCARDIOGRAPHY: FEASIBILITY, PITFALLS AND DIAGNOSTIC ADVANTAGES

Background: Echodoppler quantification of mitral regurgitation (MR) is still controversial, in particular little is known about correlation between quantitative and semi-quantitative methods. Methods and Results: 95 patients (pts) aged 58 +/- 13 years, 56% male, with at least moderate organic MR were enrolled in the period between Oct 2006 and Nov 2014. The etiology of MR was flail of MV leaflet. Regurgitant volume (RV) and effective regurgitant orifice (ERO) quantified by PISA (RV 56 ± 17 mL, ERO 0.32 ± 0.09 cm2), Doppler (RV 58 ± 17 mL, ERO 0.34 ± 0.12 cm2) and Volumetric (RV 48 ± 17 mL, ERO 0.27 ± 0.1 cm2) methods, were similar, particularly by quantitative Doppler and PISA (R2 0.89, p < 0.001). By semiquantitative methods jet area 4C was 9.1 ± 4.4 cm2, jet area/left atrium (LA) area 41 ± 20%, vena contracta (VC) was 5 ± 4.2 mm; pulmonary vein (PV) systolic flow reversal was present in 44% of patients. Only VC width among semiquantitative methods showed a sufficient correlation with RV (R2 0.52, p < 0.001), weaker with ERO (R2 0.46, p < 0.001). Conclusion: MR should be always evaluated by quantitative methods, particularly doppler and PISA RV and ERO, which showed the best correlation. Among semiquantitative methods only VC width represents a good option to RV or ERO evaluation by quantitative methods.

The role of echocardiography in the management of patients with myxomatous disease

Degenerative mitral regurgitation (MR), the leading cause of organic MR in western countries, is primarily characterized by mitral valve prolapse but encompasses a wide spectrum of anatomic lesions from fibroelastic deficiency (localized prolapse segment often associated with ruptured chordae) to diffuse myxomatous degeneration (Barlow's disease, diffuse excessive tissue with multiple valvular segments involved). Echocardiography is the method of choice to evaluate patients with degenerative MR and plays a crucial role in clinical management. It allows accurate assessment of MR severity, left ventricular and atrial consequences, etiology, mechanisms and anatomic lesions and consequently defines the probability of mitral valve repair.

Mitral Valve Prolapse With Mid-Late Systolic Mitral Regurgitation

Background—

Mitral regurgitation (MR) of mitral valve prolapse predominates in late systole but may be holosystolic or purely mid-late systolic, but the impact of MR timing on MR left ventricular and left atrial consequences and outcome is unknown. Whether effective regurgitant orifice (ERO) by the flow convergence method is similarly linked to outcome in mid-late systolic MR and holosystolic MR is uncertain.

Methods and Results—

We comprehensively and prospectively quantified MR in 111 patients with mitral valve prolapse and mid-late systolic MR and matched them to 90 patients with mitral valve prolapse and holosystolic MR for age, gender, atrial fibrillation, ejection fraction, and ERO (flow convergence). Mid-late systolic MR versus holosystolic MR groups were well matched, including for comorbidity, blood pressure, and heart rate (all P >0.10). Mid-late systolic MR versus holosystolic MR caused similar color jet area, midsystolic regurgitant flow, and peak velocity ( P >0.40). Despite identical ERO (0.25±0.15 versus 0.25±0.15 cm 2 ; P =0.53), the shorter duration of mid-late systolic MR (233±56 versus 426±50 ms; P <0.0001) yielded lower regurgitant volume (24.8±13.4 versus 48.6±25.6 mL; P <0.0001). MR consequences, systolic pulmonary pressure, and left ventricular and left atrial volume index (all P <0.001) were more benign in mid-late systolic MR versus holosystolic MR. Under medical management, fewer cardiac events (5 years: 15.8±4.6% versus 40.4±6.1%; P <0.0001) occurred in mid-late systolic MR versus holosystolic MR, requiring less mitral surgery. Multivariable analysis confirmed the independent association of mid-late systolic MR with benign consequences and outcomes (all P <0.01). Absolute ERO was not linked to outcome, in contrast to regurgitant volume.

Conclusions—

MR of mitral valve prolapse that is purely mid-late systolic causes more benign consequences and outcomes than holosystolic MR. Assessment may be misleading because jet area and ERO by flow convergence appear similar to those of holosystolic MR. However, shorter MR yields lower regurgitant volume, consequences, and benign outcomes. Instantaneous ERO by flow convergence should be interpreted in context, and in mid-late systolic MR, regurgitant volume provides information more reflective of MR severity. Therefore, for clinical management and surgical referral, clinicians should carefully take into account the timing and consequences of MR.

A three-dimensional insight into the complexity of flow convergence in mitral regurgitation: adjunctive benefit of anatomic regurgitant orifice area

Mitral effective regurgitant orifice area (EROA) using the flow convergence (FC) method is used to quantify the severity of mitral regurgitation (MR). However, it is challenging and prone to interobserver variability in complex valvular pathology. We hypothesized that real-time three-dimensional (3D) transesophageal echocardiography (RT3D TEE) derived anatomic regurgitant orifice area (AROA) can be a reasonable adjunct, irrespective of valvular geometry. Our goals were to 1) to determine the regurgitant orifice morphology and distance suitable for FC measurement using 3D computational flow dynamics and finite element analysis (FEA), and (2) to measure AROA from RT3D TEE and compare it with 2D FC derived EROA measurements. We studied 61 patients. EROA was calculated from 2D TEE images using the 2D-FC technique, and AROA was obtained from zoomed RT3DE TEE acquisitions using prototype software. 3D computational fluid dynamics by FEA were applied to 3D TEE images to determine the effects of mitral valve (MV) orifice geometry on FC pattern. 3D FEA analysis revealed that a central regurgitant orifice is suitable for FC measurements at an optimal distance from the orifice but complex MV orifice resulting in eccentric jets yielded nonaxisymmetric isovelocity contours close to the orifice where the assumptions underlying FC are problematic. EROA and AROA measurements correlated well (r = 0.81) with a nonsignificant bias. However, in patients with eccentric MR, the bias was larger than in central MR. Intermeasurement variability was higher for the 2D FC technique than for RT3DE-based measurements. With its superior reproducibility, 3D analysis of the AROA is a useful alternative to quantify MR when 2D FC measurements are challenging.

Progress in the treatment of severe mitral regurgitation

Organic mitral regurgitation (MR) is prevalent in the general population. Disease progression, involving potentially irreversible left ventricular dysfunction, implies a poor prognosis for patients who do not receive appropriate treatment. Immediate rescue surgery is indicated in those with severe MR in whom subclinical left ventricular dysfunction is suggested by echocardiographic measurements or the presence of symptoms, however minor. Patients whose symptomatology is unclear should be evaluated by exercise testing. Not all forms of severe organic MR are the same: the presence of risk factors in patients with severe asymptomatic MR and preserved ventricular function indicates a suboptimal prognosis over the medium-to-long term and should prompt early mitral repair if there is a low surgical risk and the probability of a successful repair is >90-95%. The patient should be referred to a specialized surgical center if necessary. Appropriate training of surgeons in mitral repair is essential. Ischemic MR carries a worse prognosis and the risk of surgery is higher. Consequently, treatment decisions must be patient-specific and take into account the possibility of repair, the risk of surgery, and the need for concomitant surgical revascularization. New percutaneous approaches to mitral repair are being developed for selected patient groups.

Mechanism of decrease in mitral regurgitation after cardiac resynchronization therapy: optimization of the force-balance relationship

BACKGROUND

Cardiac resynchronization therapy (CRT) has been shown to reduce functional mitral regurgitation (MR). It has been proposed that the mechanism of MR reduction relates to geometric change or, alternatively, changes in left ventricular (LV) contractile function. Normal mitral valve (MV) function relies on a balance between tethering and closing forces on the MV leaflets. Functional MR results from a derangement of this force-balance relationship, and CRT may be an important modulator of MV function by its ability to enhance the force-balance relationship on the MV. We hypothesized that CRT improves the comprehensive force balance acting on the valve, including favorable changes in both geometry and LV contractile function.

METHODS AND RESULTS

We examined the effect of CRT on 34 patients with functional MR before and after CRT (209+/-81 days). MR regurgitant volume, closing forces on MV (derived from Doppler transmitral pressure gradients), including dP/dt and a factor (closing pressure ratio) expressing how long the peak closing gradient is maintained over systole (closing pressure ratio=velocity time integral/MR peak velocityxmitral regurgitation time), and dyssynchrony by tissue Doppler were measured. End-diastolic volume, end-systolic volume, mitral valve annular area (MAA) and contraction (percent change in MAA from end-diastole to midsystole), leaflet closing area (leaflet area during valve closure), and tenting volume (volume under leaflets to annular plane) were measured by 3D echocardiography. After CRT, end-diastolic volume (253+/-111 versus 221+/-110 mL, P<0.001) and end-systolic volume (206+/-97 versus 167+/-91 mL, P<0.001) decreased and ejection fraction (19+/-6 versus 27+/-9%, P<0.001) increased. MR regurgitant volume decreased from 35+/-17 to 23+/-14 mL (P<0.001), MAA from 11.6+/-3.5 to 10.5+/-3.1 cm(2) (P<0.001), leaflet closing area from 15.4+/-5 to 13.7+/-3.8 cm(2) (P<0.001), and tenting volume from 5.7+/-2.6 to 4.6+/-2.2 mL (P<0.001). Peak velocity (and therefore transmitral closing pressure) was more sustained throughout systole, as reflected by the increase in the closing pressure ratio (0.77+/-0.1 versus 0.84+/-0.1 before CRT versus after CRT, P=0.01); dP/dt also improved after CRT. There was no change in dyssynchrony or MAA contraction.

CONCLUSIONS

Reduction in MR after CRT is associated with favorable changes in MV geometry and closing forces on the MV. It does so by favorably affecting the force balance acting on the MV in 2 ways: reducing tethering through reversal of LV remodeling and increasing the systolic duration of peak transmitral closing pressures.

The correlation between three-dimensional vena contracta area and aortic regurgitation index in patients with aortic regurgitation

OBJECTIVES

The aims of this study are to explore the correlation between the three-dimensional vena contracta (3D VC) area and the aortic regurgitation (AR) index and to determine AR severity using the 3D VC area.

BACKGROUND

The geometry of regurgitant jets is complex in patients with AR. The 3D VC area can be easily cropped using any plane and we can obtain the complex geometry of the VC area.

METHODS

Full-volume three-dimensional (3D) color flow datasets were generated using the trans-thoracic parasternal approach. The AR jet could be well visualized and analyzed in three orthogonal planes using dedicated software.

RESULTS

We consecutively analyzed 77 AR patients with comprehensive 2D and 3D echocardiographic data. The 3D VC area increased proportionately with increasing AR severity using the AR index method (F = 86.1, P < 0.001) and correlated well with effective regurgitant orifice (P < 0.001). The cutoff value of the VC area was < 30 mm(2) (sensitivity = 90% and specificity = 88%) for predicting mild AR and > 50 mm(2) (sensitivity = 92% and specificity = 87%) for predicting severe AR.

CONCLUSION

3D color flow VC area measurement provides a simple and accurate method for assessing the severity of AR.

Mitral regurgitation

Mitral regurgitation affects more than 2 million people in the USA. The main causes are classified as degenerative (with valve prolapse) and ischaemic (ie, due to consequences of coronary disease) in developed countries, or rheumatic (in developing countries). This disorder generally progresses insidiously, because the heart compensates for increasing regurgitant volume by left-atrial enlargement, causes left-ventricular overload and dysfunction, and yields poor outcome when it becomes severe. Doppler-echocardiographic methods can be used to quantify the severity of mitral regurgitation. Yearly mortality rates with medical treatment in patients aged 50 years or older are about 3% for moderate organic regurgitation and about 6% for severe organic regurgitation. Surgery is the only treatment proven to improve symptoms and prevent heart failure. Valve repair improves outcome compared with valve replacement and reduces mortality of patient with severe organic mitral regurgitation by about 70%. The best short-term and long-term results are obtained in asymptomatic patients operated on in advanced repair centres with low operative mortality (<1%) and high repair rates (>/=80-90%). These results emphasise the importance of early detection and assessment of mitral regurgitation.

Long-term follow-up of mitral valve regurgitation--importance of mitral valve pathology and left ventricular function on survival

BACKGROUND

Timing of surgery for mitral regurgitation (MR) is one of the more difficult decisions for the practicing cardiologist.

METHODS AND RESULTS

In order to determine useful clinical cut-offs, we investigated the influence of baseline echocardiographic predictors for survival in a long-time follow-up cohort. Data from 144 patients with MR were collected between 1989 and 1993. Five-year mortality for MR patients was 30% compared to 13% for age- and sex matched controls (p<0.001). Each mm increase in left ventricular end systolic diameter (LVESD increased mortality with 2.5% (p<0.05) and each percent decrease in ejection fraction (EF) increased mortality with 1.8% (p<0.05). These effects were not linear and this material suggests cut-off points for LVESD to be 40 mm and EF 50%. Degree of MR did not correlate with survival, but patients with severe MR were operated more often than those with moderate MR. Patients with functional MR had reduced survival compared to patients with structural MR (p<0.01).

CONCLUSIONS

MR is a disease with greatly increased mortality and these data suggest a more aggressive approach to surgery.

Direct assessment of size and shape of noncircular vena contracta area in functional versus organic mitral regurgitation using real-time three-dimensional echocardiography

BACKGROUND

Vena contracta width (VCW) as an estimate of effective regurgitant orifice area (EROA) is an accepted parameter of mitral regurgitation (MR) severity. However, uncertainty exists in cases in which VCW at the same time appears narrow in 4-chamber (4CH) view and broad in 2-chamber (2CH) view as common in functional MR with noncircular or slit-like regurgitant orifices. We therefore hypothesized that new real-time 3-dimensional color Doppler echocardiography (RT3DE) can be used for direct assessment of the size and shape of vena contracta area (VCA) in an en face view and to determine the potential error of conventional VCW measurement on estimation of EROA.

METHODS

RT3DE was performed in 57 patients with relevant MR of different etiologies. Manual tracing of VCA in a cross-sectional plane through the vena contracta was compared with VCW in 4CH and 2CH views. As a comparative approach to VCA-3D, EROA was calculated using the hemispheric and hemielliptic proximal isovelocity surface (PISA) area method.

RESULTS

Direct measurement of VCA-3D was feasible in all patients within 2.6 +/- 0.7 minutes. RT3DE revealed significant asymmetry of VCA in functional compared with organic MR (P < .001). Among all patients, VCW-4CH and VCW-2CH correlated only moderately to VCA-3D (r =.77; r =.80). Mean VCW correlated and agreed best with VCA-3D (r =.90). VCA-3D correlated and agreed well with EROA by hemielliptic PISA (r = .96, mean error: -0.09 +/- 0.14 cm(2)) compared with significant underestimation of hemispheric PISA in noncircular lesions.

CONCLUSIONS

Direct assessment of VCA using RT3DE revealed significant asymmetry of VCA in functional MR compared with organic MR, resulting in poor estimation of EROA by single VCW measurements.

Geometry of the proximal isovelocity surface area in mitral regurgitation by 3-dimensional color Doppler echocardiography: difference between functional mitral regurgitation and prolapse regurgitation

BACKGROUND

The geometry of the proximal isovelocity surface area (PISA) of functional mitral regurgitation (MR), which is conventionally assumed to be a hemisphere, remains to be clarified. We investigated the 3-dimensional (3D) geometry of PISA of functional MR as opposed to that of MR due to mitral valve prolapse (MVP) by real-time 3D echocardiography with color Doppler capability.

METHODS

Twenty-seven patients with functional MR and 27 patients with MVP were examined. The horizontal PISA length in the commissure-commissure plane and each PISA radius in 3 anteroposterior planes (medial, central, and lateral) were measured by real-time 3D echocardiography with 3D software. The effective regurgitant orifice (ERO) area was calculated with the maximum PISA radius and compared to that by 2D quantitative Doppler method.

RESULTS

En-face 3D color Doppler images showed an elongated and slightly curved PISA geometry along the leaflet coaptation in functional MR, whereas the geometry was rounder in MVP. The PISA horizontal length in functional MR was longer than that in MVP (2.3 +/- 0.4 vs 1.2 +/- 0.2 cm, P < .001). The PISA method with the maximum radius underestimated the ERO area by 2D quantitative Doppler method (by 24%) in functional MR, but not in MVP.

CONCLUSIONS

The geometry of PISA in functional MR was elongated, distinctly different from the more focal pathology of MVP, leading to underestimation of the ERO area by PISA method.

Quantification of mitral valve regurgitation in dogs with degenerative mitral valve disease by use of the proximal isovelocity surface area method

OBJECTIVE

To determine the within-day and between-day variability of regurgitant fraction (RF) assessed by use of the proximal isovelocity surface area (PISA) method in awake dogs with degenerative mitral valve disease (MVD), measure RF in dogs with MVD, and assess the correlation between RF and several clinical and Doppler echocardiographic variables.

DESIGN

Prospective study.

ANIMALS

6 MVD-affected dogs with no clinical signs and 67 dogs with MVD of differing severity (International Small Animal Cardiac Health Council [ISACHC] classification).

PROCEDURES

The 6 dogs were used to determine the repeatability and reproducibility of the PISA method, and RF was then assessed in 67 dogs of various ISACHC classes. Mitral valve regurgitation was also assessed from the maximum area of regurgitant jet signal-to-left atrium area (ARJ/LAA) ratio determined via color Doppler echocardiographic mapping.

RESULTS

Within- and between-day coefficients of variation of RF were 8% and 11%, respectively. Regurgitation fraction was significantly correlated with ISACHC classification and heart murmur grade and was higher in ISACHC class III dogs (mean +/- SD, 72.8 +/- 9.5%) than class II (57.9 +/- 20.1%) or I (40.7 +/- 19.2%) dogs. Regurgitation fraction and left atriumto-aorta ratio, fractional shortening, systolic pulmonary arterial pressure, and ARJ/LAA ratio were significantly correlated.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that RF is a repeatable and reproducible variable for noninvasive quantitative evaluation of mitral valve regurgitation in awake dogs. Regurgitation fraction also correlated well with disease severity. It appears that this Doppler echocardiographic index may be useful in longitudinal studies of MVD in dogs.

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.

Mitral Annular Remodeling with Varying Degrees and Mechanisms of Chronic Mitral Regurgitation

HYPOTHESES

Degree of mitral annular remodeling is directly associated with severity of chronic mitral regurgitation (MR). Mitral annular remodeling occurs in a symmetric fashion, regardless of MR severity. In addition to MR severity, MR mechanism plays a significant role in mitral annular remodeling.

BACKGROUND

Limited data exists on mitral annular remodeling in patients with MR. Identification of annular changes may be important in aiding surgical repair.

METHODS

Mitral annular dimensions (anteroposterior, intercommissural, surface area, and circumference) were measured in end systole and diastole using 3-dimensional reconstructive software in 83 patients: trace to no MR (23), mild MR (15), moderate MR (26), and severe MR (19). Annular sphericity indices were determined by dividing intercommissural by anteroposterior dimensions. Patients were further subgrouped by mechanism of MR.

RESULTS

With increasing MR severity, there was a corresponding increase in all annular measurements, most pronounced in the anteroposterior dimension, circumference, and area. Larger increases were seen in patients with prolapse/flail and dilated mechanisms. Furthermore, the mitral annulus became more circular (sphericity index approached 1.0) with increasing MR severity. Patients with prolapse/flail mechanisms exhibited normal left ventricular volumes despite significant annular enlargement.

CONCLUSIONS

Mitral annular remodeling is directly associated with MR severity and occurs in an asymmetric fashion, yet is not limited to one region of the annulus. Mechanism of MR plays a significant role in annular remodeling. Annular remodeling can occur independently of left ventricular remodeling.

Prognostic implication of valvular lesion and left ventricular size in asymptomatic patients with chronic organic mitral regurgitation and normal left ventricular performance

OBJECTIVE

To date, few studies have evaluated asymptomatic patients with organic mitral regurgitation (MR). The goal of the present study was to assess the presence of independent predictive factors for progression of symptoms and/or left ventricular dysfunction (SLVSD) in this population.

METHODS

We prospectively evaluated 128 consecutive patients (mean age 60 +/- 8 years, 68% men; ejection fraction 66 +/- 3%) who were asymptomatic, with severe organic MR. Mean follow-up was 29 +/- 12 months. The combined end point was SLVSD. Clinical and echocardiographic variables were evaluated. Follow-up data were also estimated considering the annualized rate (?) of the echocardiographic indices.

RESULTS

Thirty-seven patients (29%) had SLVSD during follow-up. Cox regression model identified the effective regurgitant orifice area (EROA) >55 mm2 (risk ratio 6.3, 95% CI 2.3-8.1, P < .001) and end-systolic diameter >22 mm/m2 (risk ratio 4.5, 95% CI, 1.8-9.4, P < .02) as the only independent predictors of SLVSD. When the follow-up data were added, the ?EROA (>15 mm2/y) was independently associated with the end point.

CONCLUSION

In asymptomatic patients with organic MR, the EROA and the end-systolic diameter are independent predictors of SLVSD and allow a better risk stratification in this group of patients. ANALYTICAL SUMMARY: The goal of this study was to determine the presence of independent predictors of symptomatic progression, and/or left ventricular dysfunction in asymptomatic patients with severe mitral regurgitation. We prospectively evaluated 128 consecutive patients (mean age 60 +/- 8 years, 68% male; ejection fraction 66 +/- 3%). During follow-up (mean 29 +/- 12 months). The end point occurred in 37 patients (29%). Multivariate analysis using Cox model identified the effective regurgitant orifice area (EROA) >55 mm2 (RR: 6.3; 95% CI: 2.3-8.1; P < .001) and an end-systolic diameter (ESD) >22 mm/m2 (RR: 4.5; 95%CI: 1.8-9.4; P < .02) as the only independent predictors of the end point. When the follow-up data were added, the annualized change rate of the EROA (>15 mm2/year) was independently associated with the end point. In asymptomatic patients with organic mitral regurgitation, the EROA and ESD at study entry were independent predictors of the combined end point and allowed a better risk stratification in this group of patients.

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.

Estimación de la severidad de la insuficiencia mitral según un método simplificado basado en el flujo de convergencia proximal

INTRODUCTION AND OBJECTIVES

Calculation of the effective regurgitant orifice (ERO) is regarded as the most accurate way of assessing the severity of mitral regurgitation (MR), but the technique's complexity limits its use. Our objective was to modify and validate a previously published semiquantitative method of assessment based on measurement of the proximal isovelocity surface area (PISA) in order to adapt it to recent recommendations from American and European cardiology societies.

METHODS

In the PISA method, maximum regurgitant flow (MRF) is a function of the radius and aliasing velocity (AV). Using this relationship, it is possible to construct a nomogram formed by lines of different MRF value, which can be easily derived by looking for radius values on the graph and observing where they cross with AV values. The MR severity limits on the nomogram were set to reflect the different severity grades and limits recommended for use with ERO measurements by American and European cardiology societies.

RESULTS

We studied 76 patients with MR using Doppler echocardiography. There was an excellent correlation between MRF and ERO (r=0.98, P< .001). Estimates of MR severity made using the new nomogram were in good agreement with those derived from the ERO: for a scale with three severity grades, kappa was 0.951 and the standard error was 0.11; for four grades, kappa was 0.969 and the standard error, 0.11.

CONCLUSIONS

Estimates of MR severity derived semiquantitatively from MRF using the nomogram proposed here were in excellent agreement with quantitative estimates obtained using the ERO, and the method was faster and easier to use.

Intraoperative Assessment of Mitral Regurgitation: Role of Phenylephrine Challenge

OBJECTIVES

We defined the effects of the operative (OP) state and phenylephrine challenge on the assessment of mitral regurgitation (MR) severity.

METHODS

In all, 57 patients underwent transesophageal echocardiographic assessment of MR severity pre-OP (PREOP) and intra-OP. MR severity was assessed PREOP under conscious sedation and intra-OP with general anesthesia, before and after hemodynamic manipulation with vasoactive agents, to match intra-OP and PREOP transesophageal echocardiographic mean arterial blood pressures.

RESULTS

Intra-OP MR and mean arterial pressure were less than PREOP in 27 patients (both P < .001). When PREOP and OP blood pressures were matched using phenylephrine, there was no significant difference in MR severity between the two states (P = 1.0). Nonetheless, MR severity was still underestimated in 6 patients and overestimated in 7 patients intra-OP.

CONCLUSIONS

Intra-OP transesophageal echocardiography underestimates MR severity. Phenylephrine reduces, yet does not eliminate, intra-OP underestimation of MR severity.

Prediction of severity of isolated aortic regurgitation by echocardiography: an aortic regurgitation index study

BACKGROUND

No single precise qualitative method is recommended for evaluating the severity of aortic regurgitation (AR). Quantitative methods for AR assessment are, typically, cumbersome and time-consuming. The purpose of this study was to develop a more comprehensive method for predicting the severity of AR.

METHODS

In all, 79 patients with normal left ventricular systolic function and at least mild AR were included in this prospective study. The standard references for evaluating AR severity were quantitative methods. The AR index consisted of 5 echocardiographic parameters: jet width ratio, vena contracta width, pressure half-time, jet density, and diastolic flow reversal in the descending aorta. Each parameter was scored on a 3-point scale from 1 to 3. The AR index was calculated as the sum of each score divided by the number of parameters. Thus, an increasing AR index score from 1 to 3 was indicative of increasing regurgitation.

RESULT

The study demonstrated that the numeric value of AR index increased proportionately to the quantitative grading of AR severity, and proved to be an accurate predictor for AR severity. A 1.8 threshold for the AR index offered a high level of sensitivity and negative predictive value for severe AR. The possibility of missing severe AR was low with AR index less than 1.8. A 2.6 threshold for the AR index provided high specificity and positive predictive value for severe AR. The possibility of diagnosing severe AR was extremely high with AR index of 2.6 or more.

CONCLUSION

AR index provided a more comprehensive method for predicting the degree of AR severity in this study. We suggest that the AR index should be considered for any evaluation of the severity of AR.