Grading of mitral regurgitation by quantitative Doppler echocardiography: calibration by left ventricular angiography in routine clinical practice

[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.

Impact of early changes in left ventricular filling pattern on long-term outcome after acute myocardial infarction

BACKGROUND

In patients with heart failure due to chronic ischemic heart disease improvement of diastolic function indicates improved survival and a reduced morbidity, but whether this is also the case after acute myocardial infarction is not known.

METHODS

To assess the prognostic importance of changes in left ventricular filling pattern, assessed with mitral deceleration time and colour M-mode flow propagation velocity, on cardiac death and readmission due to heart failure serial Doppler echocardiography was carried out in 103 patients with a first myocardial infarction. Based on echocardiography on hospital admission and after 1 month, patients were divided into three groups: group A (n=29) comprised patients with normal filling at either examination, group B (n=29) comprised patients with improvement of initially abnormal filling, and group C (n=45) patients with deterioration or no change of an abnormal filling pattern.

RESULTS

One-year survival free of cardiac death or hospitalisation for heart failure was 97% in group A, 86% in group B and 64% in group C (P<0.0001). In Cox analysis persistence of abnormal filling or deterioration of left ventricular filling was still a predictor of the combined endpoint (risk ratio 4.4, 95% CI 1.8-12.0, P=0.003) after adjustment of LV filling on admission, left ventricular systolic function and clinical variables. Serial analyses of left ventricular systolic function demonstrated a significant improvement after 1 year in ejection fraction in groups A and B, whereas ejection fraction remained unchanged in group C.

CONCLUSION

Patients with a persistently abnormal or a deterioration of left ventricular filling pattern as opposed to improved or normal filling are at increased risk of cardiac death and readmission due to heart failure after acute myocardial infarction.

[Quantification of mitral regurgitation]

The echographic methods of quantification of mitral regurgitation are various. Semiquantitative methods using the color Doppler extension of the regurgitant jet are now replaced by more quantitative methods, including PISA, jet width, and regurgitant fraction. Although sometimes difficult, accurate quantification of mitral regurgitation is now possible in a majority of patients using transthoracic echocardiography.

[Prognosis of organic mitral regurgitation and implications for surgical indications]

The term organic Mitral Regurgitation (MR) relates to MR secondary to anatomic alteration of the valvular or subvalvular mitral apparatus and refers to rheumatic MR and degenerative MR, i.e. mitral valve prolapse, which has become in the past 20 years the 1st cause of severe MR leading to surgery in western countries. Recent publications on the prognosis of patients with MR secondary to flail leaflet, showed that these patients incur excess mortality rates as compared to expected and that ten years after diagnosis, 90% of those will either be dead or operated on for severe symptoms. On the other hand, analysis of postoperative prognosis showed that the best results of surgical correction were observed in asymptomatic patients with normal pre-operative left ventricular function. The prognosis of these patients was then similar to that expected if a valvular repair was performed, making of mitral repair the hinge point of early surgical strategies.

A new automated method for the quantification of mitral regurgitant volume and dynamic regurgitant orifice area based on a normalized centerline velocity distribution using color M-mode and continuous wave Doppler imaging

Previous echocardiographic techniques for quantifying valvular regurgitation (PISA) are limited by factors including uncertainties in orifice location and hemispheric convergence assumption. Using computational fluid dynamics simulations, we developed a new model for the estimation of orifice diameter and regurgitant volume without the aforementioned assumptions of the PISA technique. Using experimental data obtained from the in vitro flow model we successfully validated our new model. The model output (y) and reference (x) values were in close agreement (y = 0.95x + 0.38, r = 0.96, error = 1.68 +/- 7.54% for the orifice diameter and y = 1.18x - 4.72, r = 0.93, error = 6.48 +/- 16.81% for the regurgitant volume).

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

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

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

Isolated annular dilation does not usually cause important functional mitral regurgitation: comparison between patients with lone atrial fibrillation and those with idiopathic or ischemic cardiomyopathy

OBJECTIVES

We sought to test whether isolated mitral annular (MA) dilation can cause important functional mitral regurgitation (MR).

BACKGROUND

Mitral annular dilation has been considered a primary cause of functional MR. Patients with functional MR, however, usually have both MA dilation and left ventricular (LV) dilation and dysfunction. Lone atrial fibrillation (AF) can potentially cause isolated MA dilation, offering a unique opportunity to relate MA dilation to leaflet function.

METHODS

Mid-systolic MA area, MR fraction, LV volumes and papillary muscle (PM) leaflet tethering length were compared by echocardiography among 18 control subjects, 25 patients with lone AF and 24 patients with idiopathic or ischemic cardiomyopathy (ICM).

RESULTS

Patients with lone AF had a normal LV size and function but MA dilation (isolated MA dialtion) significant and comparable to that of patients with ICM (MA AREA: 8.0 +/- 1.2 vs. 11.6 +/- 2.3 vs. 12.5 +/- 2.9 cm(2) [control vs. lone AF vs. ICM]; p < 0.001 for both lone AF and ICM). However, patients with lone AF had only modest MR, compared with that of patients with ICM (MR fraction: -3 +/- 8% vs. 3 +/- 9% vs. 36 +/- 25%; p < 0.001 for patients with ICM). Multivariate analysis identified PM tethering length, not MA dilation, as an independent primary contributor to MR.

CONCLUSIONS

Isolated annular dilation does not usually cause moderate or severe MR. Important functional MR also depends on LV dilation and dysfunction, leading to an altered force balance on the leaflets, which impairs coaptation.

Should mild-to-moderate and moderate ischemic mitral regurgitation be corrected in patients with impaired left ventricular function undergoing simultaneous coronary revascularization?

INTRODUCTION

Mitral valve regurgitation (MR) occurring as a result of myocardial ischemia and global left ventricular (LV) dysfunction predicts poor outcome. This study assessed the feasibility of mitral valve (MV) surgery concomitant with coronary artery bypass grafting (CABG) in patients with mild-to-moderate and moderate ischemic MR and impaired LV function.

MATERIALS AND METHOD

From January 1996 to July 2000, 49 patients (group 1) and 50 patients (group 2) with grade II and grade III ischemic MR and LV ejection fraction (EF) between 17% and 30% underwent combined MV surgery and CABG (group 1) or isolated CABG (group 2). LVEF (%), LV end-diastolic diameter (EDD) (mm), LV end-diastolic pressure (EDP) (mmHg), and LV end-systolic diameter (ESD) (mm) were 27.5 +/- 5, 67.7 +/- 7,27.7 +/- 4, and 51.4 +/- 7, respectively in group 1 versus 27.8 +/- 4, 67.5 +/- 6, 27.5 +/- 5, and 51.2 +/- 6, respectively in group 2. Groups 1 and 2 were divided into Groups 1A and 2A with mild-to-moderate MR (22 [45%] and 28 [56%] patients, respectively) and groups 1B and 2B with moderate MR (27 [55%] and 22 [46%], respectively). In group 1, MV repair was performed in 43 (88%) patients and MV replacement in 6 (12%) patients.

RESULTS

Preoperative data analysis did not reveal any difference between groups. Five (10%) patients in group 1 died versus 6 (12%) in group 2 (p = ns). Within 6 months after surgery, LV function and its geometry improved significantly in group 1 versus group 2 (LVEF, p < 0.001; LVEDD, p = 0.002; LVESD, p = 0.003; and LVEDP (p < 0.001) improved significantly in group 1 instead of a mild improvement in Group 2). The regurgitation fraction decreased significantly in group 1 patients after surgery (p < 0.001). There was an inverse strong correlation between postoperative forward cardiac output and regurgitation fraction (p < 0.001). LVEF and LVESD improved significantly in group 1 versus group 2 patients (p = 0.04 and p = 0.02, respectively). The cardiac index increased significantly in group 1 and 2 (p < 0.001 and p = 0.03, respectively). LV function and geometry improved significantly postoperatively in group 1B versus group 2B (LVEDD, p = 0.027; LVESD, p = 0.014; LVEDP, p = 0.034; and LVEF, p = 0.02), instead of a mild improvement in group 1A versus group 2A (LVESD, p = 0.015; LVEF, p = 0.046; and LVEDD and LVEDP, p = 0.05). At follow-up, 4 (67%) of 6 patients undergoing MV replacement died versus 5 (11.5%) of 43 patients undergoing MV repair in group 1 (p = 0.007). The overall survival at 3 years in Group 2 was significantly lower than group 1 (p < 0.009).

CONCLUSION

MV repair and replacement-preserving subvalvular apparatus in patients with impaired LV function offered acceptable outcomes in terms of morbidity and survival. Surgical correction of mild-to-moderate and moderate MR in patients with impaired LV function should be taken into consideration since it yields better survival and improved LV function.

Mitral regurgitation and left ventricular diastolic dysfunction similarly affect mitral and pulmonary vein flow Doppler parameters: the advantage of end-diastolic markers

Enhanced early mitral flow and reduced systolic pulmonary vein flow may be caused both by increased left ventricular pressure as the result of diastolic dysfunction and by increased transmitral flow as the result of mitral regurgitation. Nevertheless, Doppler parameters are widely used to predict left ventricular filling pressure. We aimed to analyze the interference of mitral regurgitation with Doppler parameters usually used to estimate left ventricular filling pressure and to identify markers independent of mitral regurgitation, which could reliably estimate increased left ventricular filling pressure. Eighty-four patients (age, 62 +/- 9 years; 82% men) had a complete echocardiographic Doppler examination. Transmitral E- and A-wave velocity, E deceleration time and A duration, pulmonary vein systolic and diastolic velocities, and reversal flow duration and maximal and minimal left atrial volumes were measured. The difference between the duration of pulmonary vein and mitral A waves was calculated (A'-A). Mitral regurgitant volume was quantitatively assessed by echocardiography. Left ventricular end-diastolic pressure was measured invasively. Patients had a wide range of left ventricular ejection fraction (14% to 70%), mitral regurgitant volume (0 to 94 mL), and left ventricular end-diastolic pressure (3 to 37 mm Hg). E velocity, E/A, pulmonary vein systolic and diastolic, and systo-diastolic ratios were significantly and independently correlated with both left ventricular end-diastolic pressure and mitral regurgitant volume. A'-A showed a strong correlation with left ventricular end-diastolic pressure (r = 0.70; P <.0001), but the relation with mitral regurgitant volume was not significant (r = 0.19; P =.08). Mitral regurgitation affects the majority of Doppler parameters widely used to predict filling pressure but does not influence Ad'-Ad, which proved to be the strongest predictor of left ventricular end-diastolic pressure.

Timing of surgery in patients with chronic, severe mitral regurgitation

Patients with severe mitral regurgitation (MR) who are managed conservatively sustain excess mortality and morbidity. With improved mortality and morbidity rates being achieved with surgical management, cardiologists and cardiac surgeons are becoming more aggressive in treating patients with severe MR with surgery. Recent data indicate that even in the absence of symptoms or left ventricular dysfunction, surgery should be offered as a treatment for MR, provided that the regurgitation is severe, the valve seems to be repairable, and the surgeon is experienced in valve repair and is aided by intraoperative transesophageal echocardiography.

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.

Pseudonormal and restrictive filling patterns predict left ventricular dilation and cardiac death after a first myocardial infarction: a serial color M-mode Doppler echocardiographic study

OBJECTIVES

We sought to assess the prognostic value of left ventricular (LV) filling patterns, as determined by mitral E-wave deceleration time (DT) and color M-mode flow propagation velocity (Vp), on cardiac death and serial changes in LV volumes after a first myocardial infarction (MI).

BACKGROUND

Combined assessment of DT and Vp allows separation of the effects of compliance and relaxation on LV filling, thereby allowing identification of pseudonormal filling. This may be valuable after MI, where abnormal LV filling is frequently present.

METHODS

Echocardiography was performed within 24 h, five days and one and three months after MI in 125 unselected consecutive patients. Normal filling was defined as DT 140 to 240 ms and Vp > or =45 cm/s; impaired relaxation as DT > or =240 ms; pseudonormal filling as DT 140 to 240 ms and Vp <45 cm/s; and restrictive filling as DT <140 ms.

RESULTS

Left ventricular filling was normal in 38 patients; impaired relaxation in 38; pseudonormal in 23; and restrictive in 26. End-systolic and end-diastolic volume indexes were significantly increased during the first three months after MI in patients with pseudonormal or restrictive filling (37+/-15 vs. 47+/-19 ml/m2, p<0.0005 and 71+/-20 vs. 88+/-24 ml/m2, p<0.0005, respectively). During a follow-up period of 12+/-7 months, 33 patients died. Mortality was significantly higher in patients with impaired relaxation (p = 0.02), pseudonormal filling (p<0.00005) and restrictive filling (p<0.00005), compared with patients with normal filling. On Cox analysis, restrictive filling (p = 0.003), pseudonormal filling (p = 0.006) and Killip class > or =II (p = 0.008) independently predicted cardiac death, compared with clinical and echocardiographic variables.

CONCLUSIONS

Pseudonormal or restrictive filling patterns are related to progressive LV dilation and predict cardiac death after a first MI.

Ratio of left ventricular peak E-wave velocity to flow propagation velocity assessed by color M-mode Doppler echocardiography in first myocardial infarction: prognostic and clinical implications

OBJECTIVES

To determine the ability of the ratio of peak E-wave velocity to flow propagation velocity (E/Vp) measured with color M-mode Doppler echocardiography to predict in-hospital heart failure and cardiac mortality in an unselected consecutive population with first myocardial infarction (MI).

BACKGROUND

Several experimental studies indicate color M-mode echocardiography to be a valuable tool in the evaluation of diastolic function, but data regarding the clinical value are lacking.

METHODS

Echocardiography was performed within 24 h of arrival at the coronary care unit in 110 consecutive patients with first MI. Highest Killip class was determined during hospitalization. Patients were divided into groups according to E/Vp <1.5 and > or =1.5.

RESULTS

During hospitalization 53 patients were in Killip class > or =II. In patients with E/Vp > or =1.5, Killip class was significantly higher compared with patients with E/Vp <1.5 (p < 0.0001). Multivariate logistic regression analysis identified E/Vp > or =1.5 to be the single best predictor of in-hospital clinical heart failure when compared with age, heart rate, E-wave deceleration time (Dt), left ventricular (LV) ejection fraction, wall motion index, enzymatic infarct size and Q-wave MI. At day 35 survival in patients with E/Vp <1.5 was 98%, while for patients with E/Vp > or =1.5, it was 58% (p < 0.0001). Cox proportional hazards model identified Dt <140 ms, E/Vp > or =1.5 and age to be independent predictors of cardiac death, with Dt < 140 ms being superior to age and E/Vp.

CONCLUSIONS

In the acute phase of MI, E/Vp > or =1.5 measured with color M-mode echocardiography is a strong predictor of in-hospital heart failure. Furthermore, E/Vp is superior to systolic measurements in predicting 35 day survival although Dt <140 ms is the most powerful predictor of cardiac death.

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.

Determinants of pulmonary venous flow reversal in mitral regurgitation and its usefulness in determining the severity of regurgitation

Pulmonary venous flow (PVF) reversal is observed in mitral regurgitation (MR) and can be detected by Doppler echocardiography. However, the determinants of PVF alterations in MR have not been analyzed with simultaneous quantitative methods, and the diagnostic accuracy of flow reversal is uncertain. Prospectively, in 128 patients with isolated MR of various degrees (regurgitant fraction 4% to 81%), Doppler echocardiography was used to measure PVF velocity simultaneously to quantify MR by 2 methods and to perform a comprehensive hemodynamic assessment. Systolic PVF velocity was 4 +/- 56 cm/s (systolic flow reversal in 39 patients) and showed the strongest correlations with mitral effective regurgitant orifice (r = -0.56, p <0.0001). In multivariate analysis, larger effective regurgitant orifice (p <0.0001), eccentric jets (p = 0.0023), longer jets (p = 0.0033), and lower mitral regurgitant velocity (p = 0.0015) were independent determinants of decreased systolic PVF velocity. In organic MR, increased filling pressures were associated with systolic PVF reversal. Blunted systolic flow was associated with shorter mitral deceleration time (p <0.0001) and enlarged left atrium (p = 0.0007). For the diagnosis of severe MR (regurgitant orifice > or = 35 mm2, regurgitant fraction > or = 50%), systolic flow reversal sensitivity was 61% and 60%, and specificity was 92% and 85%, respectively. Among 29 patients in whom surgery demonstrated severe mitral lesions, 12 (41%) had no systolic flow reversal preoperatively. In patients with MR, the determinants of systolic PVF are complex and, in addition to the degree of MR, include the hemodynamic consequences of MR, jet characteristics, left ventricular filling, and left atrial volume alterations. Consequently, systolic PVF reversal is a useful sign of severe MR but of relatively low sensitivity, emphasizing the importance of quantifying MR.

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.

Effects of afterload reduction on vena contracta width in mitral regurgitation

OBJECTIVES

We used color Doppler flow mapping to determine whether vena contracta width (VCW) is a load-independent measure of the severity of mitral regurgitation.

BACKGROUND

VCW has been proposed to be a relatively load-independent measure of mitral regurgitation severity in flow models using a fixed orifice. However, in patients with mitral regurgitation, VCW may not be load independent because of a dynamic regurgitant orifice.

METHODS

VCW, effective regurgitant orifice area and regurgitant volume were measured by quantitative Doppler mapping in 31 patients with chronic mitral regurgitation at baseline and during nitroprusside infusion. Patients with rheumatic heart disease, annular calcification or endocarditis were considered to have a fixed regurgitant orifice, whereas patients with mitral valve prolapse, dilated cardiomyopathy or ischemia were considered to have a dynamic regurgitant orifice.

RESULTS

Systolic blood pressure (148 +/- 27 to 115 +/- 25 mm Hg) and end-systolic wall stress (121 +/- 50 to 89 +/- 36) decreased with nitroprusside (p < 0.05). Although nitroprusside did not significantly change mean values for VCW (0.5 +/- 0.2 to 0.5 +/- 0.2 cm), regurgitant volume (69 +/- 47 to 69 +/- 56 ml) or effective regurgitant orifice area (0.5 +/- 0.4 to 0.5 +/- 0.6 cm2), individual patients exhibited marked directional variability. Specifically, VCW decreased in 16 patients (improved mitral regurgitation), remained unchanged in 7 patients and increased in 8 patients (worsened mitral regurgitation) with nitroprusside. Also, the VCW response to nitroprusside was concordant with changes in effective regurgitant orifice area and regurgitant volume, and was not different between dynamic and fixed orifice groups.

CONCLUSIONS

Contrary to the results from in vitro studies, VCW is not load independent in patients with mitral regurgitation caused by dynamic changes in the regurgitant orifice. The origin of mitral regurgitation does not predict accurately whether the regurgitant orifice is fixed or dynamic. Finally, short-term vasodilation with nitroprusside may significantly worsen the severity of mitral regurgitation in some patients.