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

Dynamic Quantitative Echocardiographic Evaluation of Mitral Regurgitation in the Operating Department

Hemodynamic modifications induced by general anesthesia could lead to underestimation of mitral regurgitation (MR) severity in the operating department and potentially serious consequences. The intraoperative severity of MR was prospectively compared with the preoperative baseline evaluation using dynamic quantitative transesophageal echocardiography in 25 patients who were stable with MR 2/4 or greater undergoing coronary bypass, mitral valve operation, or both. Significant changes in the severity of MR using transesophageal echocardiographic criteria occurred after the induction of general anesthesia and with phenylephrine. Quantitative transesophageal echocardiographic evaluation of MR using effective orifice area and vena contracta, and the use of phenylephrine challenge, were useful to avoid underestimating MR severity in the operating department.

Relationship of Mitral Annular Remodeling to Severity of Chronic Mitral Regurgitation

HYPOTHESES

(1) Mitral regurgitation (MR) severity is directly associated with mitral annular remodeling as evidenced by mitral annular enlargement. (2) Increasing severity of chronic MR will result in symmetric enlargement of the mitral annulus as measured by annular shape indices.

BACKGROUND

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

METHODS

The mitral annulus was measured in several planes using transthoracic echocardiography in 173 patients: trace to no MR (34), mild MR (48), moderate MR (45), and severe MR (46). Patients were subgrouped by mechanism of MR and annular shape indices were determined.

RESULTS

With increasing MR severity, there was a corresponding symmetric increase in all systolic and diastolic measurements, but no significant differences in annular shape indices between subgroups by MR severity or by MR mechanism.

CONCLUSIONS

Mitral annular remodeling is symmetric, regardless of degree or mechanism of MR.

Quantification of annular dilatation and papillary muscle separation in functional mitral regurgitation: role of anterior mitral leaflet length as reference

BACKGROUND

We hypothesized that anterior mitral leaflet length (ALL) does not differ significantly between normal subjects and patients with functional mitral regurgitation (FMR) and hence may be used as a reference measurement to quantify annular dilatation and papillary muscle separation.

METHODS AND RESULTS

We prospectively studied 50 controls, 15 patients with systolic left ventricular dysfunction (LVD) with significant FMR, and 15 patients with LVD without significant FMR. Significant MR was defined as an effective regurgitant orifice area > or = 0.2 cm2 as measured by the flow convergence method. Annular diameter, interpapillary distance, and ALL were measured, and the following ratios were derived: annular diameter indexed to ALL (ADI) and interpapillary distance indexed to ALL (IPDI). There was no significant difference in ALL among the three groups. The mean ADI was 1.26 times controls in patients with LVD without significant FMR compared to 1.33 times controls in patients with LVD with significant FMR (P = 0.06, no significant difference between groups). The mean IPDI was 1.42 times controls in patients with LVD without significant FMR compared to 2.1 times controls in patients with LVD with significant FMR (P < 0.0001, significant difference between groups).

CONCLUSION

There was no significant difference in ALL between controls and patients with LVD. ALL can be used as a reference measurement to quantify annular dilatation and papillary muscle separation in patients with FMR. Interpapillary distance but not annular diameter indexed to ALL correlates with severity of FMR.

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.

Quantitative determinants of the outcome of asymptomatic mitral regurgitation

BACKGROUND

The clinical outcome of asymptomatic mitral regurgitation is poorly defined, and the treatment is uncertain. We studied the effect on the outcome of quantifying mitral regurgitation according to recent guidelines.

METHODS

We prospectively enrolled 456 patients (mean [+/-SD] age, 63+/-14 years; 63 percent men; ejection fraction, 70+/-8 percent) with asymptomatic organic mitral regurgitation, quantified according to current recommendations (regurgitant volume, 66+/-40 ml per beat; effective regurgitant orifice, 40+/-27 mm2).

RESULTS

The estimated five-year rates (+/-SE) of death from any cause, death from cardiac causes, and cardiac events (death from cardiac causes, heart failure, or new atrial fibrillation) with medical management were 22+/-3 percent, 14+/-3 percent, and 33+/-3 percent, respectively. Independent determinants of survival were increasing age, the presence of diabetes, and increasing effective regurgitant orifice (adjusted risk ratio per 10-mm2 increment, 1.18; 95 percent confidence interval, 1.06 to 1.30; P<0.01), the predictive power of which superseded all other qualitative and quantitative measures of regurgitation. Patients with an effective regurgitant orifice of at least 40 mm2 had a five-year survival rate that was lower than expected on the basis of U.S. Census data (58+/-9 percent vs. 78 percent, P=0.03). As compared with patients with a regurgitant orifice of less than 20 mm2, those with an orifice of at least 40 mm2 had an increased risk of death from any cause (adjusted risk ratio, 2.90; 95 percent confidence interval, 1.33 to 6.32; P<0.01), death from cardiac causes (adjusted risk ratio, 5.21; 95 percent confidence interval, 1.98 to 14.40; P<0.01), and cardiac events (adjusted risk ratio, 5.66; 95 percent confidence interval, 3.07 to 10.56; P<0.01). Cardiac surgery was ultimately performed in 232 patients and was independently associated with improved survival (adjusted risk ratio, 0.28; 95 percent confidence interval, 0.14 to 0.55; P<0.01).

CONCLUSIONS

Quantitative grading of mitral regurgitation is a powerful predictor of the clinical outcome of asymptomatic mitral regurgitation. Patients with an effective regurgitant orifice of at least 40 mm2 should promptly be considered for cardiac surgery.

Contribution of ischemic mitral regurgitation to congestive heart failure after myocardial infarction

OBJECTIVES

The purpose of this study was to define the contribution of ischemic mitral regurgitation (IMR) to the occurrence of congestive heart failure (CHF) after myocardial infarction (MI).

BACKGROUND

After MI, CHF is a frequent and serious complication, but its determinants and, particularly, the role of IMR are poorly defined.

METHODS

We analyzed 173 asymptomatic patients with previous Q-wave MI (>16 days) with echocardiographic quantitation of IMR (measuring effective regurgitant orifice [ERO] and regurgitant volume). The 102 patients with IMR were matched to 71 patients without IMR for age (71 +/- 11 years vs. 68 +/- 9 years; p = 0.11), gender (76% vs. 82% males; p = 0.41), and left ventricular ejection fraction (EF) (37 +/- 14% vs. 36 +/- 11%; p = 0.92).

RESULTS

Five-year rates of CHF and of CHF or cardiac death (CD) were 36 +/- 5% and 52 +/- 5%, respectively. Independent determinants of CHF were EF, sodium plasma level, and presence and degree of IMR (p < 0.0001). Five-year CHF rates were 18 +/- 5% without mitral regurgitation (MR), 53 +/- 7% with IMR, 46 +/- 9% with ERO 1 to 19 mm(2) and 68 +/- 12% with ERO > or =20 mm(2) (all p < 0.0001). The adjusted relative risk of CHF was 3.65 (95% confidence interval [CI] 1.86 to 7.75) for IMR presence and 4.42 (95% CI 1.9 to 10.5) for ERO > or =20 mm(2). The adjusted relative risk of CHF/CD was 2.97 (95% CI 1.77 to 5.16) for IMR presence and 4.4 (95% CI 2.4 to 8.2) for ERO > or =20 mm(2).

CONCLUSIONS

After MI, incidence of CHF and of CHF/CD are high even in patients with no or minimal symptoms at baseline and are higher in patients with IMR. Congestive heart failure is independently determined by larger ERO of IMR. These data suggest that detecting and quantifying IMR is essential for risk stratification after MI. Value of IMR treatment in improving post-MI outcome should be investigated.

What does transesophageal echocardiography add to valvular heart surgery?

No single monitoring tool in the last decade has had more of an effect on intraoperative decision making and surgical management of cardiac valvular pathologies than has TEE. It has become the standard of care for evaluating reparative valvular procedures, thus providing an immediate gauge of the surgical results and helping to avoid suboptimal surgical outcomes. As the technology of TEE and its application advance, so too should the ability to diagnose and manage valvular pathologies, broaden the range of surgical options, and ultimately improve patient outcomes.

[Role of echocardiography in the detection and prognosis of ischemic mitral regurgitation]

Ischemic mitral regurgitation (IMR) is mitral regurgitation (MR) due to complications of coronary artery disease and not fortuitously associated with it. Acute MR secondary to ruptured papillary muscle after myocardial infarction is rare and often fatal. We focus on functional MR, much more common, which occurs without any intrinsic valve disease. It was often underrated because of low murmur intensity but with the use of echocardiography this complication is observed between 15%-20% after a myocardial infarction. Recent advances in noninvasive Doppler echocardiography allow accurate assessment of regurgitant volume and effective regurgitant orifice and thus provide the tools to reliably evaluate the prognosis and mechanisms of IMR. IMR presence is associated with excess mortality. The mortality risk is directly related to the degree of regurgitation and a regurgitant volume > or = 30 ml or an effective regurgitant orifice > or = 20 mm2; define a high-risk group. Presence and degree of the regurgitation are related to local left ventricular remodeling. The apical and posterior displacement of papillary muscles leads to excess valvular tenting which in turn, in association with loss of systolic annular contraction, determines the severity of the regurgitation. In current clinical practice, IMR is mainly corrected by ring annuloplasty. However, this technique does not correct local alterations of left ventricular remodeling and its benefits on long-term outcome remains to be demonstrated.

Vena contracta width measurement: theoretic basis and usefulness in the assessment of valvular regurgitation severity

In patients with valvular regurgitation, the regurgitation jet can be observed by Doppler color flow imaging. Vena contracta is defined as the narrowest part of the jet, just distal to the regurgitant orifice. Vena contracta dimensions reflect the severity of regurgitation. Vena contracta diameter, usually easy to measure in clinical practice, is well correlated with the effective regurgitant orifice area and the regurgitant volume. Cutoff values have been determined to identify severe regurgitation for mitral, aortic, and tricuspid valves. In clinical practice, determination of vena contracta diameter is a useful and simple method for assessment of valvular regurgitation. In the future, assessment of complex jet regurgitations will probably benefit from the contribution of three-dimensional Doppler flow imaging, which should improve the performances of the method.

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

BACKGROUND

Two-dimensional (2D) echocardiography planimetry, the Doppler pression half-time (PHT), and the continuity equation methods were used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS). Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA. The purpose of this study is (1) to compare in a large non-selected population the accuracy of the PISA and planimetry methods for echocardiographic estimation of MVA; (2) to determine the effect of atrial fibrillation (AF), Wilkins score, associated mitral regurgitation (MR), aortic regurgitation (AR), and of commissural calcifications on the accuracy of the PISA method.

METHODS

One hundred and eight consecutive patients with rheumatic MS were studied (76 females and 32 males; mean age: 36 +/- 12 years); 64 were in sinus rhythm; 51 had associated MR and 46 had AR. By the PISA method. MVA was calculated assuming a uniform radius flow convergence region along a hemispherical surface.

RESULTS

The mean value of 2D MVA was 1.32 +/- 0.59 cm2 (0.4-3.1 cm2) and that of PISA MVA 1.33 +/- 0.62 cm2 (0.38-3 cm2). MVA calculated using the PISA method correlated well with 2D MVA (r = 0.93, y = 0.97x + 0.04, p < 0.0001, SEE = 0.21 cm2). The correlation was also good in patients with AF (r = 0.93, y = 0.99x + 0.03, p < 0.0001, SEE = 0.21 cm2), with MR (r = 0.94, y = 1.0 14x + 0.003, p < 0.0001, SEE = 0.19 cm2), with AR (r = 0.93, y = 0.90x + 0.11, p < 0.0001, SEE = 0.2 cm2), when Wilkins score was >8 (r = 0.92, = 0.96x + 0.06, p < 0.0001, SEE = 0.19 cm2), and in patients with commissural calcifications (r = 0.90, y = 0.88x + 0.009, p < 0.0001, SEE = 0.20 cm2).

CONCLUSION

Our study shows that in routine practice, MVA calculated by the PISA method correlated well with the area obtained by planimetry even in the presence of commissural calcifications, associated MR, AR, AF and of high Wilkins score. Therefore, the PISA method provides a reliable measurement of the MVA in MS under different anatomic and clinical conditions and may be a useful alternative method for calculating MVA.

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.

Automated quantification of aortic regurgitant volume and regurgitant fraction using the digital colour Doppler velocity profile integration method in patients with aortic regurgitation

BACKGROUND

The recently introduced automated cardiac flow measurement (ACM) technique provides a quick and an accurate automated calculation of stroke volume and cardiac output. This is obtained by spatio-temporal integration of digital Doppler velocity profile data.

OBJECTIVE

To evaluate the use of the ACM method in the non-invasive assessment of aortic regurgitant volume and per cent regurgitant fraction (%RF) in patients with aortic regurgitation.

METHODS

Aortic outflow volume and mitral inflow volume were calculated by the ACM method in 22 patients with isolated aortic regurgitation. Aortic regurgitant volume and %RF were calculated using the following equations: aortic regurgitant volume = [aortic outflow volume] - [mitral inflow volume]; %RF = [aortic regurgitant volume]/[aortic outflow volume] x 100. The results were compared with those obtained using pulsed Doppler cross sectional echocardiography (PD-2D).

RESULTS

Aortic regurgitant volumes measured by the ACM method showed a good correlation with the PD-2D measurements (r = 0.95, y = 0.9x + 3.9, SEE = 8.6 ml); the mean (SD) difference between the two methods was -1.5 (8.5) ml. %RF estimated by the ACM method also correlated well with the values obtained by the PD-2D method (r = 0.91, y = 0.9x + 4.9, SEE = 6.0%); the mean difference between the two methods was -1.5 (6.0)%. Total time required for aortic regurgitant volume (for one cardiac cycle) by the ACM method was significantly shorter than by the PD-2D method (130 (16) v 230 (32) s, p < 0.01).

CONCLUSIONS

The newly developed the ACM method is quick and accurate in the automated assessment of aortic regurgitant volume and per cent regurgitant fraction in patients with isolated aortic regurgitation.

Quantification of instantaneous flow rate and dynamically changing effective orifice area using a geometry independent three-dimensional digital color Doppler method: An in vitro study mimicking mitral regurgitation

OBJECTIVE

Our study was intended to test the accuracy of a 3-dimensional (3D) digital color Doppler flow convergence (FC) method for assessing the effective orifice area (EOA) in a new dynamic orifice model mimicking a variety of mitral regurgitation.

BACKGROUND

FC surface area methods for detecting EOA have been reported to be useful for quantifying the severity of valvular regurgitation. With our new 3D digital direct FC method, all raw velocity data are available and variable Nyquist limits can be selected for computation of direct FC surface area for computing instantaneous flow rate and temporal change of EOA.

METHODS

A 7.0-MHz multiplane transesophageal probe from an ultrasound system (ATL HDI 5000) was linked and controlled by a computer workstation to provide 3D images. Three differently shaped latex orifices (zigzag, arc, and straight slit, each with cutting-edge length of 1 cm) were used to mimic the dynamic orifice of mitral regurgitation. 3D FC surface computation was performed on parallel slices through the 3D data set at aliasing velocities (14-48 cm/s) selected to maximize the regularity and minimize lateral dropout of the visualized 3D FC at 5 points per cardiac cycle. Using continuous wave velocity for each, 3D-calculated EOA was compared with EOA determined by using continuous wave Doppler and the flow rate from a reference ultrasonic flow meter. Simultaneous digital video images were also recorded to define the actual orifice size for 9 stroke volumes (15-55 mL/beat with maximum flow rates 45-182 mL/s).

RESULTS

Over the 9 pulsatile flow states and 3 orifices, 3D FC EOAs (0.05-0.63 cm(2)) from different phases of the cardiac cycle in each pump setting correlated well with reference EOA (r = 0.89-0.92, SEE = 0.027-0.055cm(2)) and they also correlated well with digital video images of the actual orifice peak (r = 0.97-0.98, SEE = 0.016-0.019 cm(2)), although they were consistently smaller, as expected by the contraction coefficient.

CONCLUSION

The digital 3D FC method can accurately predict flow rate, and, thus, EOA (in conjunction with continuous wave Doppler), because it allows direct FC surface measurement despite temporal variability of FC shape.

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.

Quantitation of functional mitral regurgitation during bicycle exercise in patients with heart failure

OBJECTIVES

We sought to examine the feasibility and reliability of quantifying mitral regurgitation (MR) during exercise by Doppler echocardiography in patients with heart failure and to assess the relationship between dynamic MR and systolic pulmonary artery pressure changes.

BACKGROUND

The severity of MR can be quantified by using several echocardiographic methods. Quantitation of MR during dynamic exercise has not yet been performed.

METHODS

Symptom-limited, semi-supine two-dimensional and Doppler echocardiograms during bicycle exercise were obtained in 27 consecutive patients with heart failure and functional MR. Regurgitant volume was measured at rest and during exercise by the proximal isovelocity surface area (PISA) method and by quantitative Doppler echocardiography. Exercise-induced changes in regurgitant volume were compared with changes in the regurgitant jet area to left atrial area ratio, vena contracta width and trans-tricuspid pressure gradient.

RESULTS

The regurgitant volume measured by the PISA method increased from 21 +/- 12 ml (range 5 to 55) at rest to 39 +/- 23 ml (range 8 to 85) during exercise (p < 0.0001). The difference between two observers was low for both rest (2.0 +/- 2.7 ml) and exercise measurements (3.5 +/- 6.2 ml). The regurgitant volume measured by quantitative Doppler echocardiography increased from 29 +/- 13 to 49 +/- 24 ml (p = 0.0001). Excellent correlation between the two methods was obtained with exercise (r = 0.92). Exercise-induced changes in regurgitant volume, as measured by the PISA method, correlated well with regurgitant volume changes measured by quantitative Doppler echocardiography (r = 0.88), changes in vena contracta width (r = 0.82) and changes in trans-tricuspid pressure gradient (r = 0.73), but not with changes in regurgitant jet area to left atrial area ratio (r = 0.29). Seventeen patients stopped exercise because of fatigue and 10 because of dyspnea. These 10 patients exhibited greater increases in regurgitant volume (34 +/- 6 vs. 11 +/- 8 ml), corresponding to a significant elevation of the trans-tricuspid gradient (48 +/- 14 vs. 20 +/- 14 mm Hg).

CONCLUSIONS

Quantitation of functional MR during exercise is feasible in patients with heart failure. There is a good correlation between regurgitant volume measured during exercise by the PISA method and that obtained by quantitative Doppler echocardiography, suggesting that the technique is reliable. An increase in mitral regurgitant volume during dynamic exercise correlates well with elevation of systolic pulmonary artery pressure.

Contrast echocardiography improves the accuracy and reproducibility of left ventricular remodeling measurements: a prospective, randomly assigned, blinded study

OBJECTIVES

We sought to assess the impact of contrast injection and harmonic imaging, on the measure by echocardiography of left ventricular (LV) remodeling.

BACKGROUND

Left ventricular remodeling is a precursor of LV dysfunction, but the impact of contrast injection and harmonic imaging on the accuracy or reproducibility of echocardiography is unclear.

METHODS

We prospectively collected LV images by using simultaneous methods. Then, LV volumes were measured off-line, in blinded manner and in random order. The accuracy of echocardiography was determined in comparison to electron beam computed tomography (EBCT) in 26 patients. The reproducibility of echocardiography was assessed by three blinded observers with different training levels in 32 patients.

RESULTS

End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and ejection fraction (EF), as measured by EBCT (195 +/- 55, 58 +/- 24 and 137 +/- 35 ml and 71 +/- 5%, respectively) and echocardiography with harmonic imaging and contrast injection (194 +/- 51, 55 +/- 20 and 140 +/- 35 ml and 72 +/- 4%, respectively), showed no differences (all p > 0.15) and excellent correlations (all r > 0.87). In contrast, echocardiography using harmonic imaging without contrast injection underestimated the EBCT results (all p < 0.01). Reproducibility was superior with rather than without contrast injection for intraobserver and interobserver variabilities (all p < 0.001). Values measured by different observers were different without contrast injection, but were similar with contrast injection (all p > 0.18). Consequently, intrinsic patient differences represented a larger and almost exclusive proportion of global variability with contrast injection for EDV (94 vs. 79%), ESV (93 vs. 82%), SV (87 vs. 53%) and EF (84 vs. 41%), as compared with harmonic imaging without contrast injection (all p < 0.005).

CONCLUSIONS

For assessment of LV remodeling, echocardiography with harmonic imaging and contrast injection improved the accuracy and reproducibility, as compared with imaging without contrast injection. With contrast injection, variability was almost exclusively due to intrinsic patient differences. Therefore, when evaluation of LV remodeling is deemed important, assessment after contrast injection should be the preferred echocardiographic approach.

Hemielliptic proximal isovelocity surface area method modified for clinical application: more accurate quantification of mitral regurgitation in Doppler echocardiography

The proximal isovelocity surface area (PISA) method is one of the various methods used for quantitatively estimating mitral regurgitation. The PISA shape is hemielliptic rather than hemispheric on a slit-like orifice, and the hemielliptic method is more accurate than the hemispheric method for in vitro studies. Nevertheless, the hemispheric method is used clinically because of its simplicity, whereas the hemielliptic method is difficult to approach from 3 orthogonal directions. The present study tries to establish a modified hemielliptic method for use in clinical applications. A closed-circuit, constant flow system was designed to simulate PISA, and various types of slit-like orifices were selected. Three orthogonal PISA radii were measured and flow rates were calculated using the original hemielliptic formula from the 3 orthogonal radii. Flow rates were also calculated indirectly using a linear regression formula, and PISA radii from a bird's eye approach and lateral approaches (modified hemielliptic method) were compared. Flow rates that were determined using the original hemielliptic method correlated significantly with actual flow rates (r = 0.92, p < 0.0001; y = 1.1x - 13; SEE = 13.63 ml/s). Similarly, flow rates calculated using the modified hemielliptic method correlated significantly with actual flow rates (r = 0.90, p < 0.001; y = 0.94x - 0.78; SEE = 14.13 ml/s). The study's results imply that the modified hemielliptic method can be used to accurately quantify mitral regurgitation and could be applied for clinical examinations.

Echocardiographic assessment of mitral regurgitation

Although the natural history of mitral regurgitation (MR) is poorly defined, evidence has been found for excess mortality and morbidity in patients with severe MR who are managed conservatively. With improved mortality and morbidity in the surgical management of this condition, we are becoming increasingly aggressive in offering surgery to patients with severe MR. Surgery may be offered even in the absence of symptoms or left ventricular dysfunction, provided that the valve seems reparable, the patient's MR is severe, and the surgical team is experienced in valve repair. Echocardiography is critically important in determining the feasibility of valve repair and accurately assessing the severity of the patient's MR. It also allows assessment of the effect of MR on the left ventricle and the left atrium.

Effects of blood viscosity on proximal flow convergence calculations of regurgitant flow rate and jet dimensions as evaluated by color Doppler flow mapping: an in vitro study

There are limited data on the potential influence of blood viscosity on the quantification of valvular regurgitation by color Doppler in the clinical setting. This study was designed to evaluate the effects of blood viscosity on jet dimensions and the proximal flow convergence (proximal isovelocity surface area, PISA) method of estimating valvular insufficiency severity. We used an in vitro flow model filled with human blood at varying hematocrits (15%, 35%, and 55%) and blood viscosity (blood/water viscosity: 2.6, 4.8, 9.1) in which jets were driven through a known orifice (16 mm(2)) into a 110-mL compliant receiving chamber (compliance: 2.2 mL/mm Hg) by a power injection pump. Blood injections (2 and 4 mL) at flow rates of 4, 6, 8, 10, and 12 mL/s were performed. Proximal flow convergence and spatial distribution of jets were imaged by a 3.5-MHz transducer. Pressure and volume in the flow model were kept constant before each injection. Ultrasound settings were the same for all experiments. Jet area decreased significantly with increasing blood viscosity, but the difference in jet dimensions was much larger for lower than for higher flow rates and for highest blood viscosity. Estimation of flow rate by the PISA method was not significantly influenced by blood viscosity. Blood viscosity has a major influence in jet area, especially for lower flow rates, but did not change significantly the grading of regurgitation by the PISA method. Thus this factor should be considered for determining the method of choice when quantification of valvular regurgitation is performed in patients with anemia or polycythemia.

Short-term hemodynamic performance of the mitral Carpentier-Edwards PERIMOUNT pericardial valve. Carpentier-Edwards PERIMOUNT Investigators

BACKGROUND

Although long-term durability data exist, little data are available concerning the hemodynamic performance of the Carpentier-Edwards PERIMOUNT pericardial valve in the mitral position.

METHODS

Sixty-nine patients who were implanted with mitral PERIMOUNT valves at seven international centers between January 1996 and February 1997 consented to participate in a short-term echocardiography follow-up. Echocardiographs were collected at a mean of 600+/-133 days after implantation (range, 110 to 889 days); all underwent blinded core lab analysis.

RESULTS

At follow-up, peak gradients were 9.09+/-3.43 mm Hg (mean, 4.36+/-1.79 mm Hg) and varied inversely with valve size (p < 0.05). The effective orifice areas were 2.5+/-0.6 cm2 and tended to increase with valve size (p = 0.08). Trace mitral regurgitation (MR) was common (n = 48), 9 patients had mild MR, 1 had moderate MR, none had severe MR. All MR was central (n = 55) or indeterminate (n = 3). No paravalvular leaks were observed. Mitral regurgitation flow areas were 3.4+/-2.8 cm2 and were without significant volumes.

CONCLUSIONS

In this multicenter study, these mitral valves are associated with trace, although physiologically insignificant, central MR. Despite known echocardiographic limitations, the PERIMOUNT mitral valves exhibit similar hemodynamics to other prosthetic valves.

Progress in mitral and aortic regurgitation

Over the past 15 years there has been rapid and dramatic change in the therapy for valvular heart disease. When mitral and aortic regurgitation are severe, they inevitably cause left ventricular damage, eventually resulting in death. However, when surgical correction of these lesions is timed appropriately, longevity can approach that of a normal population after surgery. As surgical techniques have improved, surgery is now indicated earlier in the course of these diseases. It is clear that some patients with mitral and aortic regurgitation require surgery even though they are entirely asymptomatic. However, it must be emphasized that mitral and aortic regurgitation are quite different from one another. These different lesions result in different loading conditions, different pathophysiologies, and have different means for surgical correction. All of these issues impact on the proper timing of surgery and are discussed.

Assessment of aortic regurgitation by transesophageal color Doppler imaging of the vena contracta: validation against an intraoperative aortic flow probe

OBJECTIVES

This study was performed to validate the accuracy of color flow vena contracta (VC) measurements of aortic regurgitation (AR) severity by comparing them to simultaneous intraoperative flow probe measurements of regurgitant fraction (RgF) and regurgitant volume (RgV).

BACKGROUND

Color Doppler imaging of the vena contracta has emerged as a simple and reliable measure of the severity of valvular regurgitation. This study evaluated the accuracy of VC imaging of AR by transesophageal echocardiography (TEE).

METHODS

A transit-time flow probe was placed on the ascending aorta during cardiac surgery in 24 patients with AR. The flow probe was used to measure RgF and RgV simultaneously during VC imaging by TEE. Flow probe and VC imaging were interpreted separately and in blinded fashion.

RESULTS

A good correlation was found between VC width and RgF (r = 0.85) and RgV (r = 0.79). All six patients with VC width >6 mm had a RgF >0.50. All 18 patients with VC width <5 mm had a RgF <0.50. Vena contracta area also correlated well with both RgF (r = 0.81) and RgV (r = 0.84). All six patients with VC area >7.5 mm2 had a RgF >0.50, and all 18 patients with a VC area <7.5 mm2 had a RgF <0.50. In a subset of nine patients who underwent afterload manipulation to increase diastolic blood pressure, RgV increased significantly (34 +/- 26 ml to 41 +/- 27 ml, p = 0.042) while VC width remained unchanged (5.4 +/- 2.8 mm to 5.4 +/- 2.8 mm, p = 0.41).

CONCLUSIONS

Vena contracta imaging by TEE color flow mapping is an accurate marker of AR severity. Vena contracta width and VC area correlate well with RgF and RgV obtained by intraoperative flow probe. Vena contracta width appears to be less afterload-dependent than RgV.

A semiautomated objective technique for applying the proximal isovelocity surface area method to quantitate mitral regurgitation: Clinical studies with the digital flow map

BACKGROUND

Clinical application of the color Doppler proximal isovelocity surface area (PISA) method to quantify mitral regurgitation (MR) has been limited by the often inaccurate assumption that isovelocity surfaces are hemispheric. This study applied an objective method for selecting the region where the hemispheric geometry holds best on the basis of mathematic analysis of results at different distances from the orifice. We aimed to demonstrate this approach can be applied accurately in the clinical setting and can be semiautomated to promote routine use by extracting velocities from the digital Doppler output and then performing all the calculations automatically.

METHODS

In 75 patients with isolated MR, centerline velocities (V(r)) at each distance (r) from the orifice in the proximal flow field were extracted digitally. The automated analysis calculated peak MR flow rates as 2pir(2)V(r) and plotted these against their respective velocities. The optimal value for peak flow rate was obtained mathematically at the site where the slope of this curve was minimal (least inaccuracy). This value was combined with continuous wave Doppler data to provide regurgitant stroke volume (RSV) and orifice area (ROA), which were compared with quantitative Doppler in 75 patients and angiography in 42.

RESULTS

RSV and ROA by this optimized, semiautomated PISA method correlated and agreed well with values from quantitative Doppler (y = 0.9x + 1.9, r = 0.90, standard error of the estimate [SEE] = 8.1 mL, mean difference = -0.7 +/- 8.5 mL for RSV; y = 0.9x + 0.02, r = 0.90, SEE = 0.048 cm(2), mean difference = -0.005 +/- 0.1 cm(2) for ROA) and correlated well with angiography (rho = 0.90 for both RSV and ROA).

CONCLUSIONS

This objective PISA method for quantifying MR is accurate in the clinical setting and has been semiautomated by use of analysis of digital velocity data to provide a rapid and practical technique suitable to facilitate more extensive application in routine practice.

Calculation of mitral regurgitant orifice area with use of a simplified proximal convergence method: initial clinical application

To validate a previously proposed simplified proximal flow convergence method for calculating mitral regurgitant orifice area (ROA), a prospective study was conducted in ambulatory patients and in patients undergoing open heart surgery. Assuming a pressure difference between the left ventricle and left atrium of approximately 100 mm Hg (jet velocity [v(p)] 500 cm/s) and setting the color aliasing velocity (v(a)) to 40 cm/s, we simplified the conventional proximal convergence method formula (ROA = 2pi(r2)v(a)/v(p)) to r2/2, where r is the radius of the proximal convergence isovelocity hemisphere. For 57 ambulatory patients with a wide range of mitral regurgitant severity (1 to 4+), ROA was calculated by the conventional (x) and simplified (y) methods, demonstrating excellent accuracy (r = 0.92; P <.001; DeltaROA [y - x] = 0.004 +/- 0.08 cm2). For 24 intraoperative patients, ROA calculated by the simplified formula (y) correlated well with the pulsed Doppler-thermodilution method (x) (r = 0.84; P <.01; DeltaROA [y - x] = -0.002 +/- 0.08cm2). This simplified proximal convergence formula yields an accurate assessment of ROA for a wide range of regurgitant severity, while the time required for this measurement is shortened by half (1.5 +/- 0.5 minutes versus 3.2 +/- 0.7 minutes). This may increase the frequency of calculating ROA in the clinical laboratory.

Effect of losartan on degree of mitral regurgitation quantified by echocardiography

The objective of this study was to determine the effect of oral losartan on the degree of mitral regurgitation (MR). The regurgitant volume and effective regurgitant orifice were quantified using 3 methods (flow convergence, quantitative Doppler, and quantitative 2-dimensional echocardiography) in 32 patients (26 men, mean age 67 +/- 14 years) with MR, both at baseline and 4 hours after losartan (50 mg orally). Twenty-eight patients were also reevaluated after 1 month of continued treatment with losartan (50 mg/day). With treatment, systolic blood pressure decreased from 143 +/- 16 to 130 +/- 18 mm Hg and left ventricular end-systolic wall stress from 173 +/- 46 to 156 +/- 44 g/cm2 (both p < 0.001). With treatment, regurgitant volume decreased (from 77 +/- 28 to 64 +/- 26 ml, - 18 +/- 10%; p < 0.001) in direct relation to the effective regurgitant orifice change (from 43 +/- 16 to 37 +/- 15 mm2, -17 +/- 10%; p < 0.001) but without significant change in regurgitant gradient or duration. Wide individual variability in response was observed unrelated to the magnitude of blood pressure changes. Larger reduction in regurgitant volume was observed in patients with a marked decrease in wall stress (r = 0.47, p = 0.01) and higher baseline end-diastolic volume index (r = -0.38, p = 0.03) and regurgitant volume (r = -0.45, p = 0.01). Acute improvements were sustained and unchanged at 1 month (all p > 0.15). Treatment of MR using the angiotensin receptor antagonist losartan produces a significant and sustained decrease in the degree of MR, with decreases in regurgitant volume and effective regurgitant orifice. However, the changes are of modest and variable magnitude.

Comparison of quantitative and semiquantitative methods for assessing mitral regurgitation by transesophageal echocardiography

Semiquantitative grading of mitral regurgitation (MR) by transesophageal echocardiography (TEE) is widely used for clinical decision making. However, the relation between semiquantitative grading by biplane or multiplane TEE and quantitative measures remains undetermined. Biplane or multiplane TEE was performed in 113 patients in the operating room. MR severity was graded from 1 to 4+ by Doppler color flow mapping. MR was quantified using the thermodilution-Doppler method as mitral regurgitant stroke volume (RSV) derived from the difference between total mitral inflow measured by pulsed Doppler and forward flow measured by thermodilution. Mitral regurgitant orifice area (ROA) was calculated by RSV divided by mitral regurgitant velocity. RSV and ROA were also calculated using the proximal isovelocity surface area method. RSV and ROA significantly correlated with the semiquantitative grading either by TEE or angiogram in a nonlinear fashion, with the best fit being given by an exponential model with correlation coefficients from 0.73 to 0.87 (p <0.001). Substantially increased RSV and ROA were observed in MR grades of > or =3+. In the same grades of 3+ or 4+ MR, the largest RSV was 4 times larger than the smallest (190 to 220 vs 44 to 45 ml), and the largest ROA (1.82 to 2.0 vs 0.26 to 0.27 cm2) was sixfold larger than the smallest. Patients with 2 to 3+ MR had significantly variable RSV and ROA (range 21 to 91 ml and 0.12 to 0.65 cm2, respectively). Color flow mapping by biplane or multiplane TEE or angiography is able to categorize precisely mild (< or =2+) and severe (> or =3+) MR, but cannot accurately determine actual hemodynamic load of MR in more severe degrees of MR.

Quantification of tricuspid regurgitation by measuring the width of the vena contracta with Doppler color flow imaging: a clinical study

OBJECTIVE

We sought to evaluate the vena contracta width (VCW) measured using color Doppler as an index of severity of tricuspid regurgitation (TR).

BACKGROUND

The VCW is a reliable measure of mitral and aortic regurgitation, but its value in measuring TR is uncertain.

METHODS

In 71 consecutive patients with TR, the VCW was prospectively measured using color Doppler and compared with the results of the flow convergence method and hepatic venous flow, and its diagnostic value for severe TR was assessed.

RESULTS

The VCW was 6.1+/-3.4 mm and was significantly higher in patients with, than those without, severe TR (9.6+/-2.9 vs. 4.2 +/- 1.6 mm, p<0.0001). The VCW correlated well with the effective regurgitant orifice (ERO) by the flow convergence method (r = 0.90, SEE = 0.17 cm2, p<0.0001), even when restricted to patients with eccentric jets (r = 0.93, p < 0.0001). The VCW also showed significant correlations with hepatic venous flow (r = 0.79, p < 0.0001), regurgitant volume (r = 0.77, p<0.0001) and right atrial area (r = 0.46, p< 0.0001). A VCW > or =6.5 mm identified severe TR with 88.5% sensitivity and 93.3% specificity. In comparison with jet area or jet/right atrial area ratio, the VCW showed better correlations with ERO (both p<0.01) and a larger area under the receiver operating characteristic curve (0.98 vs. 0.88 and 0.85, both p<0.02) for the diagnosis of severe TR.

CONCLUSIONS

The VCW measured by color Doppler correlates closely with severity of TR. This quantitative method is simple, provides a high diagnostic value (superior to that of jet size) for severe TR and represents a useful tool for comprehensive, noninvasive quantitation of TR.

Mitral regurgitation: comprehensive assessment by echocardiography

Two-dimensional and Doppler echocardiography have become the major modalities for the assessment of mitral regurgitation. The combined use of these techniques provides information regarding the morphology of the valvular apparatus as well as the severity of regurgitation. Transesophageal and three-dimensional echocardiography provide a more-detailed evaluation of valve morphology, which can be valuable in determining suitability for valve repair. In patients with severe mitral regurgitation, echocardiographic assessment of ventricular size and function plays a critical role in determining the optimal timing of surgery.

Intraoperative echocardiographic detection of regurgitant jets after valve replacement

BACKGROUND

Paravalvular jets, documented by intraoperative transesophageal echocardiography, have prompted immediate valve explantation by others, yet the significance of these jets is unknown.

METHODS

Twenty-seven patients had intraoperative transesophageal two-dimensional color Doppler echocardiography, performed to assess the number and area of regurgitant jets after valve replacement, before and after protamine. Patients were grouped by first time versus redo operation, valve position and type.

RESULTS

Before protamine, 55 jets were identified (2.04+/-1.4 per patient) versus 29 jets after (1.07+/-1.2 per patient, p = 0.0002). Total jet area improved from 2.0+/-2.2 cm2 to 0.86+/-1.7 cm2 with protamine (p<0.0001). In all patients jet area decreased (average decrease, 70.7%+/-27.0%). First time and redo operations had similar improvements in jet number and area (both p>0.6). Furthermore, mitral and mechanical valves each had more jets and overall greater jet area when compared to aortic and tissue valves, respectively.

CONCLUSIONS

Following valve replacement, multiple jets are detected by intraoperative transesophageal echocardiography. They are more common and larger in the mitral position and with mechanical valves. Improvement occurs with reversal of anticoagulation.

Flow convergence flow rates from 3-dimensional reconstruction of color Doppler flow maps for computing transvalvular regurgitant flows without geometric assumptions: An in vitro quantitative flow study

OBJECTIVE

This study was designed to develop and test a 3-dimensional method for direct measurement of flow convergence (FC) region surface area and for quantitating regurgitant flows with an in vitro flow system.

BACKGROUND

Quantitative methods for characterizing regurgitant flow events such as flow convergence with 2-dimensional color flow Doppler imaging systems have yielded variable results and may not be accurate enough to characterize those more complex spatial events.

METHOD

Four differently shaped regurgitant orifices were studied: 3 flat orifices (circular, rectangular, triangular) and a nonflat one mimicking mitral valve prolapse (all 4 orifice areas = 0.24 cm(2)) in a pulsatile flow model at 8 to 9 different regurgitant flow rates (10 to 50 mL/beat). An ultrasonic flow probe and meter were connected to the flow model to provide reference flow data. Video composite data from the color Doppler flow images of the FC were reconstructed after computer-controlled 180 degrees rotational acquisition was performed. FC surface area (S cm(2)) was calculated directly without any geometric assumptions by measuring parallel sliced flow convergence arc lengths through the FC volume and multiplying each by the slice thickness (2.5 to 3.2 mm) over 5 to 8 slices and then adding them together. Peak regurgitant flow rate (milliliters per second) was calculated as the product of 3-dimensional determined S (cm(2)) multiplied by the aliasing velocity (centimeters per second) used for color Doppler imaging.

RESULTS

For all of the 4 shaped orifices, there was an excellent relationship between actual peak flow rates and 3-dimensional FC-calculated flow rates with the direct measurement of the surface area of FC (r = 0.99, mean difference = -7.2 to -0.81 mL/s, % difference = -5% to 0%), whereas a hemielliptic method implemented with 3 axial measurements of the flow convergence zone from 2-dimensional planes underestimated actual flow rate by mean difference = -39.8 to -18.2 mL/s, % difference = -32% to -17% for any given orifice.

CONCLUSIONS

Three-dimensional reconstruction of flow based on 2-dimensional color Doppler may add quantitative spatial information, especially for complex flow events. Direct measurement of 3-dimensional flow convergence surface areas may improve accuracy for estimation of the severity of valvular regurgitation.

Progression of mitral regurgitation: a prospective Doppler echocardiographic study

OBJECTIVES

This study was performed to define the rates and determinants of progression of organic mitral regurgitation (MR).

BACKGROUND

Severe MR has major clinical consequences, but the rates and determinants of progression of the degree of regurgitation are unknown. Quantitative Doppler echocardiographic methods allow the quantitation of regurgitant volume (RVol), regurgitant fraction (RF) and effective regurgitant orifice (ERO) to define progression of MR.

METHODS

In a prospective study of MR progression, 74 patients had two quantitative Doppler echocardiographic examinations of MR (with at least two methods) 561 +/- 423 days apart without an intervening event.

RESULTS

Progression of MR was observed, with increase in RVol (77 +/- 46 ml vs. 65 +/- 40 ml, p < 0.0001), RF (47 +/- 16% vs. 43% +/- 15%, p < 0.0001), and ERO (50 +/- 35 mm2 vs. 41 +/- 28 mm2, p < 0.0001). Annual rates (95% confidence interval) were, respectively, 7.4 ml/year (5.1, 9.7), 2.9%/year (1.9, 3.9) and 5.9 mm2/year (3.9, 7.8). However, wide individual variation was observed, and regression and progression of RVol >8 ml was found in 11% and 51%, respectively. In multivariate analysis, independent predictors of progression of RVol were progression of the lesions, particularly a new flail leaflet (p = 0.0003), and progression of mitral annulus diameter (p = 0.0001). Regression of MR was associated with marked changes in afterload, particularly decreased blood pressure (p = 0.008). No significant effect of treatment was detected.

CONCLUSIONS

Organic MR tends to progress over time with increase in volume overload (RVol) due to increase in ERO. Progression of MR is variable and determined by progression of lesions or mitral annulus size. These data should help plan follow up of patients with organic MR and future intervention trials.

The value of assessing pulmonary venous flow velocity for predicting severity of mitral regurgitation: A quantitative assessment integrating left ventricular function

Although alteration in pulmonary venous flow has been reported to relate to mitral regurgitant severity, it is also known to vary with left ventricular (LV) systolic and diastolic dysfunction. There are few data relating pulmonary venous flow to quantitative indexes of mitral regurgitation (MR). The object of this study was to assess quantitatively the accuracy of pulmonary venous flow for predicting MR severity by using transesophageal echocardiographic measurement in patients with variable LV dysfunction. This study consisted of 73 patients undergoing heart surgery with mild to severe MR. Regurgitant orifice area (ROA), regurgitant stroke volume (RSV), and regurgitant fraction (RF) were obtained by quantitative transesophageal echocardiography and proximal isovelocity surface area. Both left and right upper pulmonary venous flow velocities were recorded and their patterns classified by the ratio of systolic to diastolic velocity: normal (>/=1), blunted (<1), and systolic reversal (<0). Twenty-three percent of patients had discordant patterns between the left and right veins. When the most abnormal patterns either in the left or right vein were used for analysis, the ratio of peak systolic to diastolic flow velocity was negatively correlated with ROA (r = -0.74, P <.001), RSV (r = -0.70, P <.001), and RF (r = -0.66, P <.001) calculated by the Doppler thermodilution method; values were r = -0.70, r = -0.67, and r = -0.57, respectively (all P <.001), for indexes calculated by the proximal isovelocity surface area method. The sensitivity, specificity, and predictive values of the reversed pulmonary venous flow pattern for detecting a large ROA (>0.3 cm(2)) were 69%, 98%, and 97%, respectively. The sensitivity, specificity, and predictive values of the normal pulmonary venous flow pattern for detecting a small ROA (<0.3 cm(2)) were 60%, 96%, and 94%, respectively. However, the blunted pattern had low sensitivity (22%), specificity (61%), and predictive values (30%) for detecting ROA of greater than 0.3 cm(2) with significant overlap with the reversed and normal patterns. Among patients with the blunted pattern, the correlation between the systolic to diastolic velocity ratio was worse in those with LV dysfunction (ejection fraction <50%, r = 0.23, P >.05) than in those with normal LV function (r = -0.57, P <.05). Stepwise linear regression analysis showed that the peak systolic to diastolic velocity ratio was independently correlated with RF (P <.001) and effective stroke volume (P <.01), with a multiple correlation coefficient of 0.71 (P <.001). In conclusion, reversed pulmonary venous flow in systole is a highly specific and reliable marker of moderately severe or severe MR with an ROA greater than 0.3 cm(2), whereas the normal pattern accurately predicts mild to moderate MR. Blunted pulmonary venous flow can be seen in all grades of MR with low predictive value for severity of MR, especially in the presence of LV dysfunction. The blunted pulmonary venous flow pattern must therefore be interpreted cautiously in clinical practice as a marker for severity of MR.

The Mitral Regurgitation Index: an echocardiographic guide to severity

OBJECTIVES

The purpose of this study was to develop a semiquantitative index of mitral regurgitation severity suitable for use in daily clinical practice and research.

BACKGROUND

There is no simple method for quantification of mitral regurgitation (MR). The MR Index is a semiquantitative guide to MR severity. The MR Index is a composite of six echocardiographic variables: color Doppler regurgitant jet penetration and proximal isovelocity surface area, continuous wave Doppler characteristics of the regurgitant jet and tricuspid regurgitant jet-derived pulmonary artery pressure, pulse wave Doppler pulmonary venous flow pattern and two-dimensional echocardiographic estimation of left atrial size.

METHODS

Consecutive patients (n = 103) with varying grades of MR, seen in the Adult Echocardiography Laboratory at UCSF, were analyzed retrospectively. All patients were evaluated for the six variables, each variable being scored on a four point scale from 0 to 3. The reference standards for MR were qualitative echocardiographic evaluation by an expert and quantitation of regurgitant fraction using two-dimensional and Doppler echocardiography. A subgroup of patients with low ejection fraction (EF < 50%) were also analyzed.

RESULTS

The MR Index increased in proportion to MR severity with a significant difference among the three grades in both normal and low EF groups (F = 130 and F = 42, respectively, p < 0.0001). The MR Index correlated with regurgitant fraction (r = 0.76, p < 0.0001). An MR Index > or =2.2 identified 26/29 patients with severe MR (sensitivity = 90%, specificity = 88%, PPV = 79%). No patient with severe MR had an MR Index <1.8 and no patient with mild MR had an MR Index >1.7.

CONCLUSIONS

The MR Index is a simple semiquantitative estimate of MR severity, which seems to be useful in evaluating MR in patients with a low EF.

Clinical value of parameters derived by the application of the proximal isovelocity surface area method in the assessment of mitral regurgitation

To determine the clinical value of several parameters derived by application of the proximal isovelocity surface area method in the assessment of mitral regurgitation (MR), 28 consecutive patients with angiographic diagnosis of MR underwent color Doppler echocardiography within 48 h of cardiac catheterization. Aliasing velocities (V(N)) were baseline-shifted to 25 cm/s and the maximal radius (R) was measured from the first aliasing boundary to the tips of the mitral valve. By continuity, the regurgitant orifice area (ROA) and regurgitant stroke volume (RSV(PISA)) were obtained. We have related them to the angiographic grade, and with determination of the regurgitant stroke volume (RSV(DE)) and the regurgitant fraction (RF), we calculated the volume of the transmitral flow according to Fisher's method.

RESULTS

RSV(DE) correlated well with RSV(PISA) (r = 0.98). A clear relation existed between the isovelocity radius and the RSV(DE) and RF (r = 0.95 and 0.88, respectively). A radius of 8 mm or more was identified well with an RSV(DE) of 40 cm3 or more (sensitivity: 100%, specificity: 95%) and an RF of 35% or more (sensitivity: 88%, specificity: 94%). The ROA was closely related to the RSV(DE) and RF, with r = 0.92 and 0.88, respectively. An ROA of 20 mm2 or more identified well patients with RSV(DE) values of 40 cm3 or more and RF values of 35% or more. The radius, RSV(PISA) and ROA were closely related to the angiographic grade of MR (r = 0.91, 0.83 and 0.92, respectively). A radius of 7 mm or more identified patients with grade III or IV of regurgitation (sensitivity: 82%, specificity: 94%), while an ROA of 15 mm2 or more discriminated well significant regurgitation (sensitivity: 91%, specificity: 94%).

CONCLUSIONS

Parameters derived by application of the proximal isovelocity surface area method provide quantitative information that can be helpful in predicting the severity of mitral regurgitation noninvasively.

Morphological evaluation of a regurgitant orifice by 3-D echocardiography: applications in the quantification of valvular regurgitation

The clinical evaluation of blood flow regurgitation through a heart valve or stenotic lesion is an unresolved problem. The proximal flowfield region has been the study focus in the last few years; however, investigators have failed to identify an accurate and reliable calculation scheme due to lack of geometric information about the shape and size of the regurgitating or stenotic orifice. Presented here is a superior method of calculation, by using three-dimensional (3-D) echocardiography combined with Doppler velocimetry. The geometric structure of the orifice in a regurgitating porcine prosthetic valve in vitro was formulated by 3-D image construction of sequentially obtained 2-D images. The velocity flowfield was accessed by color Doppler flow mapping (CD) and continuous-wave Doppler (CW). Two accurate methods of calculation of regurgitant variables were developed. The first method calculated peak regurgitant flow rate from CD and the second method calculated regurgitant flow volume from CW. Both methods showed excellent correlation with the corresponding true values from an electromagnetic flowmeter. The promising preliminary results in such a realistic porcine model indicate the possibility of establishing a routine procedure to be tested in the clinical setting.

Mechanism of dynamic regurgitant orifice area variation in functional mitral regurgitation: physiologic insights from the proximal flow convergence technique

OBJECTIVES

We used the Doppler proximal flow convergence technique as a physiologic tool to explore the effects of the time courses of mitral annular area and transmitral pressure on dynamic changes in regurgitant orifice area.

BACKGROUND

In functional mitral regurgitation (MR), regurgitant flow rate and orifice area display a unique pattern, with peaks in early and late systole and a midsystolic decrease. Phasic changes in both mitral annular area and the transmitral pressure acting to close the leaflets, which equals left ventricular-left atrial pressure, have been proposed to explain this dynamic pattern.

METHODS

In 30 patients with functional MR, regurgitant orifice area was obtained as flow (from M-mode proximal flow convergence traces) divided by orifice velocity (v) from the continuous wave Doppler trace of MR, transmitral pressure as 4v(2), and mitral annular area from two apical diameters.

RESULTS

All patients had midsystolic decreases in regurgitant orifice area that mirrored increases in transmitral pressure, while mitral annular area changed more gradually. By stepwise multiple regression analysis, both mitral annular area and transmitral pressure significantly affected regurgitant orifice area; however, transmitral pressure made a stronger contribution (r2 = 0.441) than mitral annular area (added r2 = 0.008). Similarly, the rate of change of regurgitant orifice area more strongly related to that of transmitral pressure (r2 = 0.638) than to that of mitral annular area (added r2 = 0.003). A similar regurgitant orifice area time course was observed in four patients with fixed mitral annuli due to Carpentier ring insertion.

CONCLUSIONS

In summary, the time course and rate of change of regurgitant orifice area in patients with functional MR are predominantly determined by dynamic changes in the transmitral pressure acting to close the valve. Thus, although mitral annular area helps determine the potential for MR, transmitral pressure appears important in driving the leaflets toward closure, and would be of value to consider in interventions aimed at reducing the severity of MR.

An integrated approach to the quantification of aortic regurgitation by Doppler echocardiography

BACKGROUND

Although different Doppler methods have been proposed for the quantification of aortic regurgitation, no study has prospectively compared these methods with each other and their correlation with angiography. The aim of this study was to prospectively analyze the usefulness of different Doppler echocardiography parameters by testing all such parameters in each patient.

METHODS

Fifty-one patients with aortic regurgitation underwent 2-dimensional and Doppler echocardiographic studies and catheterization. The following Doppler indexes were analyzed and compared with aortography. Color Doppler: (1) jet color height/left ventricular outflow tract height in parasternal long-axis view, and (2) jet color area/left ventricular outflow tract area in short-axis view. Continuous Doppler: (3) regurgitant flow pressure half-time, (4) regurgitant flow time velocity integral (in centimeters), and (5) regurgitant flow time velocity integral (in centimeters)/diastolic period (in milliseconds). Pulsed Doppler in thoracic and abdominal aorta: (6) time velocity integral of diastolic reverse flow (in centimeters), (7) time velocity integral of systolic anterograde flow/integral of diastolic reverse flow, (8) (time velocity integral of diastolic reverse flow/diastolic period) x 100, and (9) diastolic reverse flow duration/diastolic period (as a percentage). We compared these parameters with severity of regurgitation measured by angiography and classified as mild, moderate, or severe.

RESULTS

The most useful parameters were (1) jet color height/left ventricular outflow tract height (correctly classified 42 of 49 patients), (2) (time velocity integral of diastolic reverse flow/diastolic period) x 100 in the thoracic aorta (correctly classified 41 of 46 patients), and (3) (time velocity integral of diastolic reverse flow/diastolic period) x 100 in the abdominal aorta (correctly classified 42 of 49 patients). Sequential integration of these 3 parameters correctly classified 96% of patients (44 of 46 patients) and was achieved in 90% of cases.

CONCLUSION

An integrated combination of several Doppler parameters can quickly and accurately classify the degree of aortic regurgitation as determined by angiography.

The mechanism of decrease in dynamic mitral regurgitation during heart failure treatment: importance of reduction in the regurgitant orifice size

OBJECTIVES

The purpose of this study was to quantify and characterize the regurgitant flow pattern and regurgitant orifice area in patients undergoing therapy for severe heart failure using contemporary echocardiographic techniques.

BACKGROUND

Mitral regurgitation may be dynamic in patients with heart failure and ultimately correlate with outcome in a group of patients.

METHODS

Fourteen patients with severe heart failure felt to require hemodynamic monitoring for the optimization of medical therapy were enrolled. Two-dimensional and Doppler echocardiograms were performed before and following invasively guided therapy. Hemodynamics and standard echocardiographic dimensions were determined as well as regurgitant volume and regurgitant orifice area derived from color M-mode and Doppler measurements.

RESULTS

Invasively guided therapy for heart failure was associated with a reduction in weight, filling pressures of the left and right heart, systemic vascular resistance, and echocardiographic left atrial, left ventricular and mitral annular dimensions. The mitral regurgitant volume decreased from 47+/-27 ml before therapy to 14+/-14 ml after therapy; p < 0.001. While therapy for heart failure markedly attenuated the volume of regurgitation, the pattern of regurgitant flow across the mitral valve was not significantly altered. In contrast, there was no difference in the velocity time integral of the continuous-wave Doppler spectra of mitral regurgitation with therapy (128+/-23 cm to 123+/-25 cm, p = 0.23). In all patients, the regurgitant orifice area decreased with therapy from 0.55+/-0.38 cm2 to 0.21+/-0.20 cm2 (p < 0.001).

CONCLUSIONS

Pharmacologic reduction in filling pressure and systemic vascular resistance leads to a reduction in the dynamic mitral regurgitation of heart failure through a reduction in the regurgitant orifice area but not through a change in the gradient across the mitral valve. Reduction of the regurgitant orifice area is likely related to decreased left ventricular volumes and decreased annular distention.

Temporal variability of vena contracta and jet areas with color Doppler in aortic regurgitation: a chronic animal model study

OBJECTIVE

The purpose of our study was to determine the temporal variability of regurgitant color Doppler jet areas and the width of the color Doppler imaged vena contracta for evaluating the severity of aortic regurgitation.

METHODS

Twenty-nine hemodynamically different states were obtained pharmacologically in 8 sheep 20 weeks after surgery to produce aortic regurgitation. Aortic regurgitation was quantified by peak and mean regurgitant flow rates, regurgitant stroke volumes, and regurgitant fractions determined using pulmonary and aortic electromagnetic flow probes and meters balanced against each other. The regurgitant jet areas and the widths of color Doppler imaged vena contracta were measured at 4 different times during diastole to determine the temporal variability of this parameter.

RESULTS

When measured at 4 different temporal points in diastole, a significant change was observed in the size of the color Doppler imaged regurgitant jet (percent of difference: from 31.1% to 904%; 233% +/- 245%). Simple linear regression analysis between each color jet area at 4 different periods in diastole and flow meter-based severity of the aortic regurgitation showed only weak correlation (0.23 < r < 0.49). In contrast, for most conditions only a slight change was observed in the width of the color Doppler imaged vena contracta during the diastolic regurgitant period (percent of difference, vena contracta: from 2.4% to 12.9%, 5.8% +/- 3.2%). In addition, for each period the width of the color Doppler imaged vena contracta at the 4 different time periods in diastole correlated quite strongly with volumetric measures of the severity of aortic regurgitation (0.81 < r < 0.90) and with the instantaneous flow rate for the corresponding period (0.85 < r < 0.87).

CONCLUSIONS

Color Doppler imaged vena contracta may provide a simple, practical, and accurate method for quantifying aortic regurgitation, even when using a single frame color Doppler flow mapping image.

Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation

OBJECTIVES

To develop and validate an automated noninvasive method to quantify mitral regurgitation.

BACKGROUND

Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR).

METHODS

First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied.

RESULTS

In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml).

CONCLUSIONS

We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.

Application of the proximal flow convergence method to calculate the effective regurgitant orifice area in aortic regurgitation

OBJECTIVES

We sought to determine the reliability of the proximal isovelocity surface area (PISA) method for calculation of effective regurgitant orifice (ERO) of aortic regurgitation (AR).

BACKGROUND

The ERO area can be calculated by the PISA method, but this method has not been validated in AR.

METHODS

ERO calculation by the PISA method was undertaken prospectively in 71 consecutive patients with isolated AR and achieved in 64 and compared with two simultaneous reference methods (quantitative Doppler and quantitative two-dimensional echocardiography). In addition, this method was compared with angiography in 12 patients, with surgical assessment in 18 patients and with ventricular volumes in all patients.

RESULTS

Good correlations between PISA and reference methods were obtained (both r=0.90, both p < 0.0001), but a trend toward underestimation of the ERO by the PISA method was noted (24+/-19 vs. 26+/-22 mm2 and 27+/-23 mm2, respectively, both p=0.04). However, this trend was confined to five patients with an obtuse flow convergence angle (>220 degrees), and on multivariate analysis this variable was the only independent determinant of underestimation of the ERO. In contrast, in 59 patients with a flat flow convergence (< or =220 degrees ), the PISA method, in comparison with reference methods, showed excellent correlations, with a narrow standard error of the estimate (r=0.95, SEE 5.4 mm2, and r=0.95, SEE 5.8 mm2; all p < 0.0001) and no trend toward underestimation (22+/-18 vs. 23+/-16 mm2, p=0.44, and vs. 23+/-18 mm2, p=0.34).

CONCLUSIONS

In patients with AR, the PISA method can be used to measure the ERO with reasonable feasibility. Underestimation of the ERO by PISA may occur in patients with an obtuse flow convergence angle. However, in most patients with appropriate flow convergence, PISA provides reliable measurement of the ERO of AR.

Three-dimensional echocardiographic planimetry of maximal regurgitant orifice area in myxomatous mitral regurgitation: intraoperative comparison with proximal flow convergence

OBJECTIVES

We sought to validate direct planimetry of mitral regurgitant orifice area from three-dimensional echocardiographic reconstructions.

BACKGROUND

Regurgitant orifice area (ROA) is an important measure of the severity of mitral regurgitation (MR) that up to now has been calculated from hemodynamic data rather than measured directly. We hypothesized that improved spatial resolution of the mitral valve (MV) with three-dimensional (3D) echo might allow accurate planimetry of ROA.

METHODS

We reconstructed the MV using 3D echo with 3 degrees rotational acquisitions (TomTec) using a transesophageal (TEE) multiplane probe in 15 patients undergoing MV repair (age 59 +/- 11 years). One observer reconstructed the prolapsing mitral leaflet in a left atrial plane parallel to the ROA and planimetered the two-dimensional (2D) projection of the maximal ROA. A second observer, blinded to the results of the first, calculated maximal ROA using the proximal convergence method defined as maximal flow rate (2pi(r2)va, where r is the radius of a color alias contour with velocity va) divided by regurgitant peak velocity (obtained by continuous wave [CW] Doppler) and corrected as necessary for proximal flow constraint.

RESULTS

Maximal ROA was 0.79 +/- 0.39 (mean +/- SD) cm2 by 3D and 0.86 +/- 0.42 cm2 by proximal convergence (p = NS). Maximal ROA by 3D echo (y) was highly correlated with the corresponding flow measurement (x) (y = 0.87x + 0.03, r = 0.95, p < 0.001) with close agreement seen (AROA (y - x) = 0.07 +/- 0.12 cm2).

CONCLUSIONS

3D echo imaging of the MV allows direct visualization and planimetry of the ROA in patients with severe MR with good agreement to flow-based proximal convergence measurements.

Assessment of valvular regurgitation with Doppler echocardiography

Echocardiography is routinely performed for the evaluation of valvular regurgitation. Different applications of Doppler echocardiography have been successfully applied to detect and quantify valvular regurgitation. Recent advances in color Doppler made possible the study of the dynamic behavior of the regurgitant orifice and, along with continuous wave Doppler, can provide data on the regurgitant volume and fraction. Doppler echocardiography can also be used to follow serial changes in these hemodynamically important parameters after medical or surgical therapy.

The role of intraoperative echocardiography in valve surgery

The widespread use and popularity of intraoperative echocardiography (IOE) has resulted from advances in cardiac surgery, reparative procedures for valvular heart disease and, most specifically, mitral valve repair. IOE has grown exponentially and is becoming an integral part of the planning and evaluation of many types of surgical procedures such that it is now considered standard of care especially for the perioperative management of patients undergoing mitral and aortic valve repair. This article discusses the application of intraoperative echocardiography and focus specifically on valvular heart disease as this represents the most widely accepted indication for the procedure in current clinical practice.