Adjacent solid boundaries alter the size of regurgitant jets on Doppler color flow maps

Clinical application of transthoracic volume-rendered three-dimensional echocardiography in the assessment of mitral regurgitation

Two-dimensional echocardiography (2-DE) and Doppler methods are generally used for assessing mechanisms and severity of mitral regurgitation (MR). Recently, 3-dimensional echocardiography (3-DE) has been applied successfully in various cardiac disorders, but its value in evaluating the mechanism and the severity of MR are not known. We studied 30 patients with MR using 2-DE and 3-DE. Volume-rendered gray-scale 3-DE images of the mitral valve apparatus and MR jets were reconstructed. Maximal volume of the MR jet by 3-DE was compared with mitral regurgitant volume and fraction, regurgitant jet area and the ratio of jet area to left atrial area, and semiquantitative grading derived from 2-DE methods. Our results demonstrated that 3-DE aided in a better depiction of the mitral apparatus and its abnormalities in 70% of the patients. The origin, direction, and morphology of the MR jet were better delineated in 3-DE volumetric display. Quantitative analysis, however, showed only a weak to moderate correlation between 3-DE maximal MR jet volume and 2-DE mitral regurgitant volume (y = 0.5x + 11.4, r = 0.7), regurgitant fraction (y = 0.5x + 8.2, r = 0.65), mitral regurgitant jet area (y = 0.2x + 5, r = 0.51), jet area to left atrial area ratio (y = 0.53x + 7.6, r = 0.54), and semiquantitative grading of MR (y = 9.1x - 1.8, r = 0.74). In conclusion, 3-DE aids in a better understanding of the mechanisms of MR and morphology of the regurgitant jets. Its quantitative ability, when reconstruction of the jet alone is used, may be limited.

Quantification of mitral regurgitation by the automated cardiac output method: an in vitro and in vivo study

BACKGROUND

Recently, the automated cardiac output method (ACM) was introduced for the calculation of blood flow at the left ventricular outflow tract (LVOT). This study was performed to examine the possibility of using ACM for flow calculation at the level of the mitral valve and for the quantification of mitral regurgitation (MR) in vitro and in vivo.

METHODS AND RESULTS

In a computer-controlled in vitro model of the human heart, aortic and mitral normal bioprosthetic valves were inserted. ACM and electromagnetic probe flow measurements correlated well at the LVOT and at the mitral level (r2 = 0.79 and 0.77, respectively). For stroke volumes ranging from 30 to 100 ml/beat, there was no statistically significant bias between ACM and electromagnetic flow probe (-1.5 and 1.3 ml for LVOT and mitral level, respectively). Limits of agreement were [-14; +11] ml and [-18; +16] ml, respectively. We evaluated 68 patients in our in vivo study. They were divided into three groups according to the results of "standard" echocardiographic Doppler methods for the semiquantification of MR: echocardiographic color Doppler cartography, intensity of the continuous wave Doppler spectra, and in some patients, pulmonary venous flow, conventional Doppler, and proximal isovelocity surface area quantitative data. Group 1 consisted of 35 patients without MR or a physiologic one; the 17 patients in group 2 had a mild MR (1-2/4) and in group 3, 16 patients with MR 3-4/4 were included. Regurgitant volume (RV) was calculated as the difference between ACM mitral flow and ACM aortic flow, and regurgitant fraction (RF) was defined as the ratio between RV and ACM mitral flow. When mitral flow was measured only from the four-chamber view, we found in group 1, RV = -0.57 (0.67) L/min and RF = -16% (19%); in group 2, RV = -0.31 (1.06) L/min and RF = -8% (19%); and in group 3, RV = 1.53 (0.94) L/min and RF = 23% (13%). RV and RF were statistically higher in group 3 compared with group 2 or group 1 (p < 0.0005), but no significant difference was found between groups 1 and 2. When mitral flow was measured by the mean value of ACM four-chamber and two-chamber views, this resulted in group 1, RV = -0.26 (0.63) L/min and RF = -8% (15%); in group 2, RV = 0.01 (1.04) L/min and RF = -2% (18%); and in group 3, RV = 2.07 (1.21) L/min and RF = 34% (19%). RV and RF were again significantly higher in group 3 (p < 0.0001). There was no significant difference between group 1 and group 2, but in group 1 RF was no longer statistically different from 0%.

CONCLUSIONS

(1) In our in vitro setting, ACM is reliable both at the LVOT and at the mitral valve. (2) In the in vivo situation, some overlapping does exist between the three groups of MR. However, ACM is a very easy, rapid, and objective method to differentiate hemodynamic nonsignificant (<3/4) from significant (> or =3/4) MR. Together with other well-known methods for the quantification of MR, it should facilitate the gradation of MR in the clinical setting. The absence of significant differences between group 1 and group 2 proves that the accuracy of ACM measurements at the mitral valve needs to be ameliorated before ACM can be used as a gold standard for the noninvasive measurement of RV and RF.

Vena contracta imaged by Doppler color flow mapping predicts the severity of eccentric mitral regurgitation better than color jet area: a chronic animal study

OBJECTIVES

This study sought to evaluate the relation between the color Doppler-imaged vena contracta and the severity of mitral regurgitation (MR) in a chronic animal model of MR.

BACKGROUND

The vena contracta, which is defined as the smallest connection between the laminar flow acceleration zone and the turbulent regurgitant jet, has been reported to be a clinically useful marker for evaluating the severity of valvular regurgitation.

METHODS

Six sheep with chronic MR produced by previous operation severing the chordae tendineae were examined. MR jet flows and vena contracta widths were imaged using a Vingmed 775 scanner with a 5-MHz transducer. Image data were directly transferred in digital format to a microcomputer for off-line measurement. MR was quantified as peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions determined using mitral and aortic electromagnetic flow probes and flowmeters balanced against each other.

RESULTS

Vena contracta width correlated well with regurgitant severity determined by electromagnetic flowmeters (r = 0.95, SEE = 0.05 cm, p < 0.0001 for peak regurgitant flow rate; r = 0.85, SEE = 0.08 cm, p < 0.0001 for regurgitant stroke volume; r = 0.90, SEE = 0.07 cm, p < 0.0001 for regurgitant fraction).

CONCLUSIONS

This study shows that the vena contracta width method is useful for predicting the severity of MR. It is simple and conveniently available with high resolution equipment. The quantitative comparisons in the present study lay the foundation for future clinical and research studies using this vena contracta technique.

Transthoracic echocardiographic assessment of periprosthetic mitral regurgitation using intravenous injection of sonicated albumin

Mechanical prostheses induce artifacts that decrease the accuracy of conventional transthoracic echocardiographic imaging for the detection and quantitation of periprosthetic mitral regurgitation. In 15 patients undergoing transthoracic echocardiography, injection of sonicated albumin significantly enhanced the assessment of periprosthetic mitral regurgitation with an accuracy similar to that of transesophageal echocardiography.

Echocardiographic assessment of mitral stenosis and its associated valvular lesions in 205 patients and lack of association with mitral valve prolapse

To date, the relation between mitral stenosis (MS) and other associated cardiac valvular lesions has been reported by angiography and surgical pathologic study in patients with more advanced disease but has not been studied systematically by two-dimensional echocardiography and Doppler color flow mapping in a large referral population with a broader spectrum of severity. In addition, prior reports have suggested that up to 40% of patients with MS have mitral valve prolapse (MVP); however, because of recent developments in two-dimensional echocardiographic imaging and the definition of MVP, this association must now be reconsidered. The purpose of this study was to explore the association of other valvular lesions with MS and their relation to its severity and in particular to test whether MS is in fact associated with MVP with the frequency reported previously. We reviewed the studies of 205 consecutive patients (aged 61 +/- 14 years; range 26 to 87 years) with MS who were studied from 1992 to 1994 by two-dimensional echocardiography and Doppler color flow mapping to assess valvular stenosis, regurgitation, and MVP in patients with a range of severity of MS (28% mild, 34% moderate, and 38% severe MS based on mitral valve area). MS was associated with at least mild mitral regurgitation in 78% of patients (160/205), and pure MS was correspondingly uncommon (22%). There was an inverse relationship between the severity of MS and the degree of mitral regurgitation (p < 0.001). MS was frequently associated (54% of patients) with significant lesions of other valves, including aortic stenosis (17%), at least moderate aortic regurgitation (8%) and tricuspid regurgitation (38%), and tricuspid stenosis (4%). Tricuspid stenosis was associated with more severe MS (p < 0.01), and tricuspid regurgitation was more common in patients with mixed MS and regurgitation than in those with pure stenosis (60% versus 26% for at least moderate tricuspid regurgitation; p < 0.001). Mitral valve prolapse was present in only one patient (0.5%). Superior systolic bulging of the midportion of the anterior mitral leaflet toward the left atrium (but not superior to the annular hinge points) was seen in 22 patients (11%). Patients with such superior bulging had significantly lower mitral valve scores but a similar degree of mitral regurgitation compared with those without bulging. The majority of patients with MS (78%) have associated mitral regurgitation and significant lesions of the other cardiac valves (54%). The frequency of true MVP associated with chronic MS is much lower than reported previously. This may provide insight into the underlying pathophysiologic process, tending to shorten the chordae tendineae and leaflets to produce stenosis rather than elongate them to produce prolapse.

Usefulness of color Doppler proximal isovelocity surface area method in quantitating valvular regurgitation

To define the clinical utility of the color Doppler proximal isovelocity surface area (PISA) method for estimating regurgitant stroke volume (SV), 160 regurgitant lesions were evaluated in 104 patients with mitral (MR), aortic (AR), and tricuspid (TR) regurgitation. Regurgitant SV by PISA was calculated as 2 pi R2 x V x (time-velocity integral/peak flow velocity), where R is the radius corresponding to the first blue-red interface velocity of the maximal PISA during the cardiac cycle. The time-velocity integral and peak flow velocity from the continuous-wave Doppler recording of the regurgitant jet were used to correct PISA for phasic variations in regurgitant flow. Fifteen lesions were excluded because of difficulty in tracing the continuous-wave Doppler regurgitant curve. Among 145 remaining regurgitant lesions, PISA was measurable in 50 (78%) of 64 cases of MR and 24 (69%) of 35 cases of TR but in only 12 (26%) of 46 cases of AR (p < 0.001). Regurgitant SV by PISA correlated modestly well with jet area/atrial area in all atrioventricular valve lesions (MR: r = 0.55; TR: r = 0.65; p < 0.001). However, the correlation improved if only central jets were considered (MR: r = 0.70; TR; r = 0.75; p < 0.001). These findings are not unexpected because jet area/atrial area underestimates the true severity of regurgitation in cases of eccentric (wall-impinging) jets. PISA was detected in all severe cases of regurgitation but in only 64% of cases of mild MR, 45% of cases of mild TR, and 6% of cases of mild AR (p < 0.01). The color Doppler PISA method is clinically useful in estimating regurgitant SV in MR and TR, including mild cases, but is less useful in AR.

Tricuspid Regurgitation and Right Heart Dimensions at Early and Late Follow-Up After Orthotopic Cardiac Transplantation

Tricuspid regurgitation is common immediately after cardiac transplantation, but its course over long-term follow-up is not known. This study was performed to determine the prevalence of valvular regurgitation and to evaluate if pulmonary hypertension or right ventricular enlargement were associated with the severity of tricuspid regurgitation at early and late follow-up after cardiac transplantation. Fifty-five patients had hemodynamic and echocardiographic studies performed at 1 week and 2.4 +/- 1.3 years after cardiac transplantation. Right ventricular dimensions were measured and related to the severity of tricuspid regurgitation as assessed by Doppler color flow. There was a fall in right heart filling pressures with decreases in the systolic pulmonary artery pressure (31 mmHg +/- 7 mmHg vs 27 mmHg +/- 7 mmHg, P = 0.0001) and right atrial pressure (8 +/- 5 mmHg vs 6 +/- 4 mmHg, P < 0.01). Sixty-three percent of patients had mild or higher grade tricuspid regurgitation initially and 71% at follow-up (P = NS). The major determinant of tricuspid regurgitation severity at late follow-up was the presence of flail tricuspid leaflets (P < 0.0001). There was an association between the change in grade of tricuspid regurgitation and the change in right ventricular diastolic area (P = 0.002) and the change in tricuspid annulus diameter (P < 0.0001). The prevalence of tricuspid regurgitation remains high at late follow-up after cardiac transplantation and neither pulmonary hypertension nor right ventricular dilatation are prerequisites for tricuspid regurgitation, which can persist in their absence. Flail tricuspid leaflets are the most important predictors of the severity of tricuspid regurgitation following cardiac transplantation.

Effect of physiological factors on proximal flow convergence upstream of an incompetent valve: an in-vitro study

The flow (Q) through regurgitant valves may be quantified by multiplying the area of an isovelocity contour (isovel) by its velocity. This was tested computationally and experimentally (using MRI). Q = 14 to 141 ml/s, using flat and conical orifice plates. Plotting Q versus isovelocity radius, a plateau was found which, for low flow, corresponded to the true Q. At higher flow or large confinement, Q was overestimated. For conical plates, angle correction worked at low Q but not at higher values due to the formation of separation regions. These converted the cone plate into a flat plate. MRI produced similar results at 57 ml/s in that Q was correct with no angle correction. At low flow, MRI was too noisy to produce a clear plateau consistently.

Quantitative Assessment of Simulated Regurgitant Flow Using Direct Digital Acquisition of Doppler Color Flow Images

Analysis of jet momentum and proximal isovelocity surface area (PISA) have been shown to be accurate in quantitating regurgitant flow for axisymmetric free jets. However, eccentric jets directed against chamber walls are often encountered in clinical practice and could confound the assessment of regurgitant flow. Thus, we used direct digital color flow mapping to calculate flow by the momentum method and PISA in a flow model. Steady flow jets were driven through a 2-mm round orifice at flow rates of 3, 6, 9, 12, 15, and 20 mL/sec. Jets were directed centrally and against the lateral wall of a 150 mL chamber. The raw data from a 3.25/2.5 MHz transducer (Vingmed CFM 750) was digitally transferred to a Macintosh IIci computer for analysis of the velocities comprising the jets. By linear regression, PISA was accurate in assessing flow for both free jets and wall jets (r(2) = 0.98) with regression lines approximating unity. The momentum method was highly accurate for free jets (r(2) = 0.98) but systematically underestimated flow for wall jets (r(2) = 0.70, y = 0.21x + 0.88). Thus, analysis of simulated regurgitant flow using digital display of velocities encoded in the color flow jet is accurate for free jets by both the PISA and momentum techniques. In wall jets, the momentum technique underestimates flow because the requirement for jet axisymmetry is not met.

Quasisteady behavior of pulsatile, confined, counterflowing jets: implications for the assessment of mitral and tricuspid regurgitation

Mitral and tricuspid regurgitation create turbulent jets within the atria. Clinically, for the purpose of estimating regurgitant severity, jet size is assumed to be proportional to peak jet flow rate and regurgitant volume. Unfortunately, the relationship is more complex because the determinants of jet size include interactions between jet pulsatility, jet momentum, atrial width, and the velocity of ambient atrial counterflows. These effects on fluorescent jet penetration were measured using an in vitro simulation. Both steady and pulsatile jets were driven into an opposing counterflow velocity field peak jet length (Ljp) measurements made as a function of (1) peak orifice velocity (Ujp), (2) the time required for the jet to accelerate from zero to peak velocity and begin to decelerate (Tjp), (3) jet orifice diameter (Dj), (4) counterflow velocity (Uc), and (5) counterflow tube diameter (Dc). A compact mathematical description was developed using dimensional analysis. Results showed that peak jet length was a function of the counterflow tube diameter, the ratio of peak jet to counterflow momentum, (Mjp/Mc) = (U2jpD2j)/(U2cD2c), and a previously undescribed jet pulsatility parameter, the pulsatility index (PI), PI = D2c/(TjpUjpDj). For the same jet orifice flow conditions, jet penetration decreased as chamber diameter decreased, as the jet PI increased, and as the momentum ratio decreased. These interactions provide insight into why regurgitant jet size is not always a good estimate of regurgitant severity.

Evaluation of eccentric aortic regurgitation by color Doppler jet and color Doppler-imaged vena contracta measurements: an animal study of quantified aortic regurgitation

To evaluate the utility of measurements of the color Doppler jet area, jet length, and width of the color Doppler-imaged vena contracta (the smallest flow diameter in any part of the flow acceleration field) as methods for quantifying aortic regurgitation (AR), eight sheep with surgically induced AR were studied. AR was quantified as peak and mean regurgitant flow rates, regurgitant stroke volumes, and regurgitant fractions as determined with pulmonary and aortic electromagnetic flow probes and flowmeters balanced against each other. Simple linear regression analysis between the maximal color jet areas, jet length, and flowmeter data showed only moderately good correlation (jet area: 0.42 < or = r < or = 0.57, SEE = 2.85 cm2; jet length: 0.42 < or = r < or = 0.59, SEE = 1.23 cm). In contrast, the width of color Doppler-imaged vena contracta was a better indicator of the severity of AR on the basis of the electromagnetic flowmeter methods (0.73 < or = r < or = 0.90, SEE = 0.15 cm). Therefore the color Doppler jet length and jet area methods have limited use for determining AR, whereas the width of the color Doppler-imaged vena contracta can be used for quantifying the severity of AR.

Transesophageal echocardiography

This article presents an overview of the benefits and efficacy of transesophageal echocardiography (TEE) in the critically ill patient. The echocardiographic evaluation of ventricular function both regional and global, is discussed with special emphasis on ischemic heart disease; assessment of preload, interrogation of valvular heart disease (prosthetic and native) and its complications; endocarditis and its complications; intracardiac and extracardiac masses, including pulmonary embolism; aortic diseases (e.g., aneurysan, dissection, and traumatic tears); evaluation of patent foramen ovale and its association with central and peripheral embolic events; advancements in computer technology; and finally, the effect of TEE on critical care.

Computational simulations of mitral regurgitation quantification using the flow convergence method: comparison of hemispheric and hemielliptic formulae

Mitral regurgitation results from the incomplete closure of the mitral valve, and the noninvasive diagnosis of this disease remains an important clinical goal. In this study, steady flow computer simulations were used to evaluate flow convergence method for flow rate estimation. The hemispheric and hemielliptic formulae were compared for accuracy in the presence of complicating factors such as ventricular confinement, orifice shape, and aortic outflow. Results showed that in the absence of aortic outflow and ventricular confinement, there was a plateau zone where the hemispheric formula approximated the true flow rate, independent of orifice shape. However, in the presence of complicating factors such as aortic outflow and ventricular confinement, there was no clear zone where the hemispheric formula could be applied. The hemielliptic formula, however, worked in all cases, regardless of chamber size or magnitude of aortic outflow. Therefore, application of the hemielliptic formula should be considered in future clinical studies.

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

OBJECTIVES

The purpose of this study was to determine, in a large referral population, the rate of echocardiographic change in mitral valve area (MVA) without interim intervention, to determine which factors influence progression of narrowing and to examine associated changes in the right side of the heart.

BACKGROUND

Little information is currently available on the echocardiographic progression of mitral stenosis, particularly on progressive changes in the right side of the heart and the ability of a previously proposed algorithm to predict progression.

METHODS

We studied 103 patients (mean age 61 years; 74% female) with serial two-dimensional and Doppler echocardiography. The average interval between entry and most recent follow-up study was 3.3 +/- 2 years (range 1 to 11).

RESULTS

During the follow-up period, MVA decreased at a mean rate of 0.09 cm2/year. In 28 patients there was no decrease, in 40 there was only relatively little change (< 0.1 cm2/year) and in 35 the rate of progression of mitral valve narrowing was more rapid (> or = 0.1 cm2/year). The rate of progression was significantly greater among patients with a larger initial MVA and milder mitral stenosis (0.12 vs. 0.06 vs. 0.03 cm2/year for mild, moderate and severe stenosis, p < 0.01). Although the rate of mitral valve narrowing was a weak function of initial MVA and echocardiographic score by multivariate analysis, no set of individual values or cutoff points of these variables or pressure gradients could predict this rate in individual patients. There was a significant increase in right ventricular diastolic area (17 to 18.7 cm2) and tricuspid regurgitation grade (2 + to 3 +; p < 0.0001 between entry and follow-up studies). Progression in right heart disease occurred even in patients with minimal or no change in MVA. Patients with associated aortic regurgitation had a higher rate of decrease in MVA than did those with trace or no aortic regurgitation (0.19 vs. 0.086 cm2/year, p < 0.05).

CONCLUSIONS

The rate of mitral valve narrowing in individual patients is variable and cannot be predicted by initial MVA, mitral valve score or transmitral gradient, alone or in combination. Right heart disease can progress independent of mitral valve narrowing.

In vitro flow mapping of regurgitant jets. Systematic description of free jet with laser Doppler velocimetry

BACKGROUND

Color Doppler and magnetic resonance imaging give pictures of abnormal jets within which the respective contribution of fluid mechanics and image artifacts are difficult to establish because of current technical limitations of these modalities. We conducted the present study to provide numerical descriptions of the velocity fields within regurgitant free jets.

METHODS AND RESULTS

Laser Doppler measurements were collected in rigid models with pulsatile flow conditions, giving several series of two-dimensional flow images. The data were studied with the use of two-dimensional or M-mode flow images as well as regular plots. Numerical descriptions validated in steady flow conditions were tested at the various times of the cycle. In these free jets, the momentum was conserved throughout the cycle. The transverse velocity profiles were approximately similar. A central laminar core was found at peak ejection and during the deceleration. Its length (l = 4.08 d-0.036 mm, r = .99) and its diameter (d) were proportional to the orifice diameter. At peak ejection, the velocity decay was hyperbolic, and the transverse velocity profiles were clearly gaussian. The different relations that were tested could be combined in a single formula describing the velocity field: V(x,y,t peak) = V(O,O,t peak).4.(d/x).10(-45(y/x)2) (r = .92).

CONCLUSIONS

These in vitro measurements demonstrated the presence of a central laminar core and similar transverse velocity profiles in free turbulent jets. This allowed us to validate a series of numerical relations that can be combined to describe the velocity fields at peak ejection. On the other hand, further studies are needed to describe the various singularities often encountered in pathology.

Color Doppler and two-dimensional echocardiographic determination of the mechanism of aortic regurgitation with surgical correlation

The character of the color flow Doppler jet provides information on the mechanism and pathologic elements of valve dysfunction. This has been useful in the evaluation of mitral regurgitation, a repairable problem, but has not been described comprehensively for the aortic valve. The purpose of our study was to correlate the color flow Doppler characteristics of the aortic regurgitant jet and two-dimensional echocardiographic findings of valve mobility with surgical pathology. Prepump intraoperative echocardiography and color flow Doppler echocardiography were performed on 124 patients with aortic regurgitation and used to categorize leaflet motion as excessive, restricted, or normal, jet direction as eccentric or central, and jet origin between the cusps as eccentric, central, or diffuse. Bicuspid disease and tricuspid aortic valve prolapse were associated with excessive valve mobility and eccentric jet direction and origin. Conversely, annular dilation, rheumatic disease, sclerosis, and perforation were associated with normal or reduced cusp mobility and a central jet direction and origin (p = 0.001). Overall, an eccentric jet direction occurred in 69% of patients with excessive cusp mobility, whereas 71% of patients with normal or reduced cusp mobility had a central jet (p = 0.001). Therefore color flow Doppler determination of the eccentricity of regurgitant jet direction and origin is useful in predicting the mechanism and disease of aortic valve dysfunction. These observations may suggest the presence of prolapse and thus the potential for aortic valve repair.

Quantification of Mitral and Tricuspid Regurgitation Using Jet Centerline Velocities: An In Vitro Study of Jets in an Ambient Counterflow

A method for quantifying mitral and tricuspid regurgitant volume that utilizes a measure of jet orifice velocity U(0) - m/sec), a distal centerline velocity (U(m) - m/sec), and the intervening distance (X - cm) was recently developed; where jet flow rate (Q(cal) - L/min) is calculated as Q(cal) = (U(m)X)(2)/(26.46U(o)). This method, however, modeled the regurgitant jet as a free jet, whereas many atrial jets are counterflowing jets because of jet opposing intra-atrial flow fields (counterflows). This study concentrated on the feasibility of using the free jet quantification equation in the atrium where ambient flow fields may alter jet centerline velocities and reduce the accuracy of jet flow rate calculations. A 4-cm wide chamber was used to pump counterflows of 0, 4, and 22 cm/sec against jets of 2.3, 4.8, and 6.4 m/sec originating from a 2-mm diameter orifice. For each counterflow-jet combination, jet centerline velocities were measured using laser Doppler anemometry. For free jets (no counterflow), flow rate was calculated with 98% mean accuracy. For all jets in counterflow, the calculation was less accurate as: (i) the ratio of jet orifice velocity to counterflow velocity decreased (U(o)/U(c), where U(c) is counterflow velocity), i.e., the counterflow was relatively more intense, and (ii) centerline measurements were made further from the orifice. But although counterflow lowered jet centerline velocities beneath free jet values, it did so only significantly in the jet's distal portion (X/D > 16, i.e., >16 orifice diameters from the origin of the jet). Thus, the initial portion (X/D < 16) of a jet in counterflow behaved essentially as a free jet. As a result, even in significant counterflow, jet flow rate was calculated with >93% accuracy and >85% for jets typical of mitral and tricuspid regurgitation, respectively. Counterflow lowers jet centerline velocities beneath equivalent free jet values. This effect, however, is most significant in the distal portion of the jet. Therefore, regurgitant jets, although not classically free because of systolic atrial inflow or jet-induced intra-atrial swirling flows, will decay in their initial portions as free jets and thus are candidates for quantification with the centerline technique. (ECHOCARDIOGRAPHY, Volume 13, July 1996)

Biopsy-induced flail tricuspid leaflet and tricuspid regurgitation following orthotopic cardiac transplantation

Damage to the tricuspid valve apparatus has been described after endomyocardial biopsy and may be associated with hemodynamically significant tricuspid regurgitation (TR). This study was performed to determine the prevalence of TR and flail tricuspid leaflet in cardiac transplant recipients and to evaluate the use of a 45 cm sheath placed directly in the right ventricle during endomyocardial biopsy to reduce the incidence of these complications. Echocardiograms and right heart catheterization data of 72 orthotopic cardiac transplant recipients were assessed for the presence of flail tricuspid leaflet, TR, and right-sided cardiac dysfunction 29 +/- 20 months (mean +/- SD) after transplantation. Moderate or severe TR was present in 23 patients (32%). Ten patients (14%) had flail tricuspid leaflet, with 7 of these having severe TR. Right atrial pressure (10 +/- 5 vs 6 +/- 5 mm Hg, p < 0.05) was higher, cardiac index (2.0 +/- 0.2 vs 2.5 +/- 0.7 L/min/m2, p < 0.05) was lower, and right-sided cardiac dimensions were greater in patients with flail leaflets than in those without flail leaflets. Both the prevalence of flail tricuspid leaflet (41% to 6%, p < 0.0001) and mean grade of TR (2 to 1, p < 0.0001) were reduced after the use of a 45 cm sheath. We conclude that TR secondary to biopsy-induced damage to the valve apparatus occurs in cardiac transplant recipients and is associated with signs of early right-sided heart failure. Use of a 45 cm sheath during endomyocardial biopsy reduces the prevalence of flail tricuspid leaflet and the severity of TR.

Aortic valve regurgitation after surgical versus percutaneous balloon valvotomy for congenital aortic valve stenosis

To compare characteristics of aortic regurgitation (AR), the results of 213 procedures (110 balloon aortic valvotomies [BAV] and 103 surgical aortic valvotomies [SAV]) for treatment of congenital aortic valve stenosis were reviewed. These procedures were performed in 187 patients from June 1981 to September 1993. Echocardiograms recorded immediately before, within 6 months afterward, and at latest follow-up were compared. Color Doppler was used to assess the degree of AR and was quantified as the ratio of the regurgitant jet width to valve annulus, the jet width ratio. Whereas BAV patients were older (median age 5.7 years vs 3 months; p = 0.0001), there was no significant difference in median follow-up interval (3.1 years [range 0.5 to 7.2] for BAV vs 3.6 years [range 0.6 to 10.4] for SAV; p = 0.44). The mean balloon-to-annulus ratio for BAV was 0.99 +/- 0.09. An open valvotomy was performed in 83% of surgical cases. Acute systolic gradient reduction and subsequent increase at late follow-up was similar for both groups. Acutely, the mean jet width ratio increased similarly (p = 0.84) for BAV (+9 +/- 15%; p = 0.0001) and SAV (+9 +/- 12%; p = 0.0003) and was not related to age at procedure. At late follow-up, mean jet width ratio further increased significantly in both groups, although there was no difference (p = 0.17) in amount of progression (BAV +10 +/- 12%; p = 0.0001, SAV +15 +/- 13%; p = 0.0002). Thus, BAV and SAV produce AR of similar severity with similar rates of progression.

Three-dimensional reconstruction of color Doppler flow convergence regions and regurgitant jets: an in vitro quantitative study

OBJECTIVES

This study sought to investigate the applicability of a current implementation of a three-dimensional echocardiographic reconstruction method for color Doppler flow convergence and regurgitant jet imaging.

BACKGROUND

Evaluation of regurgitant flow events, such as flow convergences or regurgitant jets, using two-dimensional imaging ultrasound color flow Doppler systems may not be robust enough to characterize these spatially complex events.

METHODS

We studied two in vitro models using steady flow to optimize results. In the first constant-flow model, two different orifices were each mounted to produce flow convergences and free jets--a circular orifice and a rectangular orifice with orifice area of 0.24 cm(2). In another flow model, steady flows through a circular orifice were directed toward a curved surrounding wall to produce wall adherent jets. Video composite data of color Doppler flow images from both free jet and wall jet models were reconstructed and analyzed after computer-controlled 180 degrees rotational acquisition using a TomTec computer.

RESULTS

For the free jet model there was an excellent relation between actual flow rates and three-dimensional regurgitant jet volumes for both circular and rectangular orifices (r = 0.99 and r = 0.98, respectively). However, the rectangular orifice produced larger jet volumes than the circular orifice, even at the same flow rates (p < 0.0001). Calculated flow rates by the hemispheric model using one axial measurement of the flow convergence isovelocity surface from two-dimensional color flow images underestimated actual flow rate by 35% for the circular orifice and by 44% for the rectangular orifice, whereas a hemielliptic method implemented using three axial measurements of the flow convergence zone derived using three-dimensional reconstruction correlated well with and underestimated actual flow rate to a lesser degree (22% for the circular orifice, 32% for the rectangular orifice). In the wall jet model, the jets were flattened against and spread along the wall and had reduced regurgitant jet volumes compared with free jets (p < 0.01).

CONCLUSIONS

Three-dimensional reconstruction of flow imaged by color Doppler may add quantitative spatial information to aid computation methods that have been used for evaluating valvular regurgitation, especially where they related to complex geometric flow events.

Transesophageal echocardiographic evaluation of native valvular disease and repair

Surgery for valvular heart disease corrects systolic or diastolic dysfunction of the mitral, aortic, or tricuspid valves. The intraoperative echocardiographic assessment of the native heart valve is aimed at defining the pathology of valve disease, determining the mechanism of valve dysfunction, and quantitating the degree (grade) of valvular stenosis or insufficiency.

Assessment of aortic regurgitation by color flow and continuous-wave Doppler echocardiography

This study describes a Doppler echocardiographic method for assessing the severity of aortic regurgitation based on the product of the velocity time integral and cross-sectional area of the aortic regurgitation jet. This method was found to be highly productive of the angiographic grade of aortic regurgitation with minimal overlap between grades.

Effects of exercise on left ventricular performance determined by echocardiography in chronic, severe mitral regurgitation secondary to mitral valve prolapse

Data on the effects of exercise on left ventricular (LV) volumes and ejection performance in patients with severe mitral regurgitation (MR) are limited. With use of a matched-pairs design, 10 asymptomatic patients with chronic, severe MR and normal LV systolic function who were not receiving vasodilator therapy (group 1) and 10 matched normal control subjects with no structural heart disease (group 2) performed symptom-limited upright bicycle ergometry with quantitative echocardiographic analysis. An additional 8 patients with severe, chronic MR and normal LV systolic function who were receiving vasodilator therapy at the time of testing (group 3) were studied for comparison. The 3 cohorts exercised for similar periods of time. Group 1 and 3 patients had similar end-diastolic volumes at rest, both of which were significantly greater than those of normal controls. Although resting LV end-systolic volume was greater in groups 1 and 3 than in normal controls, the 3 groups had similar relative percent reductions in end-systolic volume during exercise (30 +/- 12%, 32 +/- 13%, and 30 +/- 24%; p = NS). A similar percent increase in LV ejection fraction was also observed in all 3 cohorts (18 +/- 9%, 15 +/- 9%, and 14 +/- 6%; p = NS). Forward stroke volume increased significantly in group 1 (59 +/- 21 and 71 +/- 18 ml; p <0.001) and in group 3 (59 +/- 17 and 68 +/- 13 ml; p < 0.05). Thus, in asymptomatic patients with chronic, severe MR and normal LV ejection fraction at rest, there is an improvement in LV ejection fraction and an increase in forward stroke volume during exercise. These effects are comparable to those observed in normal controls. Directional differences in the cohort receiving no activity therapy were indistinguishable from either patients receiving vasodilator therapy or normal control subjects.

Current status of flow convergence for clinical applications: is it a leaning tower of "PISA"?

Spatial appreciation of flow velocities using Doppler color flow mapping has led to quantitative evaluation of the zone of flow convergence proximal to a regurgitant orifice. Based on the theory of conservation of mass, geometric analysis, assuming a series of hemispheric shells of increasing velocity as flow converges on the orifice--the so-called proximal isovelocity surface area (PISA) effect--has yielded methods promising noninvasive measurement of regurgitant flow rate. When combined with conventional Doppler ultrasound to measure orifice velocity, regurgitant orifice area, the major predictor of regurgitation severity, can also be estimated. The high temporal resolution of color M-mode can be used to evaluate dynamic changes in orifice area, as seen in many pathologic conditions, which enhances our appreciation of the pathophysiology of regurgitation. The PISA methodology is potentially applicable to any restrictive orifice and has gained some credibility in the quantitative evaluation of other valve pathology, particularly mitral and tricuspid regurgitation, and in congenital heart disease. Although the current limitations of PISA estimates of regurgitation have tempered its introduction as a valuable clinical tool, considerable efforts in in vitro and clinical research have improved our understanding of the problems and limitations of the PISA methodology and provided a firm platform for continuing research into the accurate quantitative assessment of valve regurgitation and the expanding clinical role of quantitative Doppler color flow mapping.

New method for accurate calculation of regurgitant flow rate based on analysis of Doppler color flow maps of the proximal flow field. Validation in a canine model of mitral regurgitation with initial application in patients

OBJECTIVES

The purpose of this study was to develop a rational and objective method for selecting a region in the proximal flow field where the hemispheric formula for calculating regurgitant flow rates by the flow convergence technique is most accurate.

BACKGROUND

A major obstacle to clinical implementation of the proximal flow convergence method is that it assumes hemispheric isovelocity contours throughout the Doppler color flow map, whereas contour shape depends critically on location in the flow field.

METHODS

Twenty mitral regurgitant flow rate stages were produced in six dogs by implanting grommet orifices into the anterior mitral leaflet and varying driving pressures so that actual peak flow rate could be determined from the known effective regurgitant orifice times the orifice velocity. Because plotting flow rate calculated by using a hemispheric formula versus alias velocities produces underestimation near the orifice and overestimation far from it, this plot was fitted to a polynomial function to allow identification of an inflection point within a relatively flat intermediate zone, where factors causing overestimation and underestimation are expected to be unimportant or balanced. The accuracy of flow rate calculation by the inflection point was compared with unselective and selective averaging techniques. Clinical relevance, initial feasibility and correlation with an independent measure were tested in 13 consecutive patients with mitral regurgitation who underwent cardiac catheterization.

RESULTS

1) The accuracy of single-point calculations was improved by selecting points in the flat portion of the curve (y = 1.15x - 3.34, r = 0.87, SEE = 22.1 ml/s vs. y = 1.34x - 1.99, r = 0.71, SEE = 45.6 ml/s, p < 0.01). 2) Selective averaging of points in the flat portion of the curve further improved accuracy and decreased scatter compared with unselective averaging (y = 1.08x + 4.8, r = 0.96, SEE = 11.6 ml/s vs. y = 1.30x + 0.6, r = 0.90, SEE = 20.9 ml/s, p < 0.01). 3) The proposed algorithm for mathematically identifying the inflection point provided the best results (y = 0.96x + 4.5, r = 0.96, SEE = 9.9 ml/s), with a mean error of 1.6 +/- 9.7 ml/s vs. 11.4 +/- 11.7 ml/s for selective averaging (p < 0.01). In patients, the proposed algorithm identified an inflection point at which calculated regurgitant volume agreed best with invasive measurements (y = 1.1x - 0.61, r = 0.93, SEE = 17 ml).

CONCLUSIONS

The accuracy of the proximal flow convergence method can be significantly improved by analyzing the flow field mathematically to identify the optimal isovelocity zone before using the hemispheric formula to calculate regurgitant flow rates. Because the proposed algorithm is objective, operator independent and, thus, suitable for automatization, it could provide the clinician with a powerful quantitative tool to assess valvular regurgitation.

Accuracy of intraoperative transesophageal echocardiography for estimating the severity of functional mitral regurgitation

Although intraoperative transesophageal echocardiography (TEE) is used to guide mitral valve reconstructive procedures, the effects of hemodynamic alterations accompanying general anesthesia on mitral regurgitation (MR) are unknown. This study was performed to evaluate the effect of general anesthesia on MR jet size using TEE with color Doppler imaging in patients undergoing mitral valve surgery. Matched preoperative TEEs performed with the patient under intravenous conscious sedation, and intraoperative studies performed with the patient under general anesthesia were retrospectively reviewed in 46 patients undergoing mitral valve surgery. Patients were divided into groups based on etiology of MR, including 21 patients with myxomatous degeneration and leaflet flail, 19 patients with structurally normal leaflets and functional regurgitation due to abnormal leaflet coaptation, and 6 patients with rheumatic mitral disease. On both preoperative and intraoperative studies, regurgitation was quantified using maximal jet area and jet diameter at the vena contracta on color flow Doppler. Patients with leaflet flail and patients with functional MR had similar measures of regurgitation severity on preoperative imaging. On intraoperative imaging, regurgitant jet size was unchanged compared with preoperative studies among patients with leaflet flail (jet diameter 1.04 +/- 0.26 vs 1.10 +/- 0.28 cm, area 9.8 +/- 4.5 vs 10.1 +/- 5.2 cm2 on preoperative studies), although jet size decreased significantly in patients with functional MR (jet diameter 0.79 +/- 0.33 vs 1.10 +/- 0.29 cm [p < 0.001], area 5.7 +/- 3.5 vs 10.0 +/- 3.8 cm2 [p < 0.001] on preoperative studies). These findings were not accounted for by variation in heart rate, blood pressures, echocardiographic instrumentation, or Doppler Nyquist limit.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of pulmonary venous flow direction on mitral regurgitation jet area as imaged by color Doppler flow mapping. An in vitro study

BACKGROUND

Although the effects of adjacent walls and left atrial pressure on mitral regurgitation (MR) jet area imaged by color Doppler have been examined, few data exist regarding the influence of pulmonary venous (PV) filling flow on regurgitant jets. Therefore, we designed a left atrial model to examine the relation between PV flow direction and MR jet area.

METHODS AND RESULTS

The left atrial chamber (7.6 cm in diameter) was built with a PV inflow (1.0 cm in diameter) and mitral valve regurgitant orifice in the same plane. The MR jet was simulated as fixed in volume and velocity (3.5 m/s) and directed with a pulsatile pump into the left atrial model. PV flow with a constant velocity (30 cm/s) was driven by gravity (83 cm H2O). With left atrial mean pressure at either 10, 30, or 50 mm Hg, four flow patterns were examined: (1) PV flow away from the mitral valve, MR jet toward the pulmonary vein; (2) PV flow toward the mitral valve, MR jet toward the pulmonary vein; (3) PV flow away from the mitral valve, MR jet away from the pulmonary vein; and (4) PV flow toward the mitral valve, MR jet away from the pulmonary vein. MR color Doppler images were recorded with a 3.5-mHz frequency transducer and at 7-kHz pulse repetition frequency. For each condition, we compared jet area, length, and width of the MR signal. MR jet areas for conditions 3 and 4 were larger at 10 mm Hg than at 30 or 50 mm Hg left atrial pressure. Especially at the lower pressures, PV flow diminished the MR jet area in condition 4 compared with that in condition 3, such that MR jets were smaller in condition 4. In conditions 1 and 2, the jets were imaged at an oblique angle and were smaller than in conditions 3 and 4 (P < .001), but they were not significantly different from each other as imaged.

CONCLUSIONS

In this model, factors including the direction of PV flow, the direction of MR as relates to the angle of interrogation, and the level of left atrial pressure influenced the size of MR jets. The effect of PV flow direction was diminished by increased left atrial pressure. PV flow directed away from the mitral valve was associated with larger MR jets than when PV flow was directed toward it (condition 4), probably because of jet distortion and flattening.

Proximal jet size by Doppler color flow mapping predicts severity of mitral regurgitation. Clinical studies

BACKGROUND

Recent studies have shown that many instrument and physiological factors limit the ability of color Doppler total jet area within the receiving chamber to predict the severity of valvular regurgitation. In contrast, the proximal or initial dimensions of the jet as it emerges from the orifice have been shown to increase directly with orifice size and to correlate well with the severity of aortic insufficiency. Only limited data, however, are available regarding the value of proximal jet size in mitral regurgitation, and it has not been examined in short-axis or transthoracic views. The purpose of the present study, therefore, was to evaluate the relation between proximal jet size and other measures of the severity of mitral regurgitation.

METHODS AND RESULTS

In 49 patients, the anteroposterior height of the proximal jet as it emerges from the mitral valve was measured in the parasternal long-axis view; proximal jet width and area were measured in the short-axis view at the same level. Results were compared with regurgitant volume and fraction by pulsed Doppler subtraction of aortic and mitral flows in 47 patients without more than trace aortic insufficiency; with angiographic grade determined within 24 hours in 33 catheterized patients; and with angiographic regurgitant fraction in 13 patients who were in normal sinus rhythm and had no significant aortic and tricuspid insufficiency. Proximal jet height, width, and area correlated well with Doppler regurgitant volume and fraction (r = .86 to .95; SEE = 7.7 to 9.0 mL; 5.9% to 7.3%). Proximal jet size could also be used to distinguish angiographic grades of mitral regurgitation with minimal overlap (P < .0001) and correlated well with angiographic regurgitant fraction (r = .85 to .91; SEE = 4.1% to 5.1%).

CONCLUSIONS

Proximal jet size correlates well with established measures of the severity of mitral regurgitation. It is conveniently available with transthoracic clinical scanning and should be useful in the routine evaluation of patients with mitral regurgitation.

Atrial inflow can alter regurgitant jet size: in vitro studies

Recent studies have attempted to predict the severity of regurgitant lesions from color Doppler jet size, which is a function of orifice momentum for free jets. Jets of mitral and tricuspid regurgitation, however, are opposed by flows entering the atria. Despite their low velocities, these counterflows may have considerable momentum that can limit jet penetration. The purpose of this study was to address the hypothesis that such counterflow fields influence regurgitant jet size. Steady flow was driven through 2.4- and 5.1-mm-diameter circular orifices at 2 to 6 m/s. At a constant orifice velocity and flow rate, the velocity of a uniform counterflow field was varied from 5 to 30 cm/s. Jet dimensions were measured by both fluorescent dye visualization and Doppler color flow mapping. The results showed that despite its relatively low velocities, counterflow dramatically curtailed jet length and area. Jet dimensions were functions of the ratio of jet to counterflow momentum. Thus, atrial inflow may participate in determining jet size and can alter the relation between jet size and lesion severity in mitral and tricuspid regurgitation.

Observations suggesting a high incidence of exercise-induced severe mitral regurgitation in patients with mild rheumatic mitral valve disease at rest

OBJECTIVES

The aim of this study was to determine the hemodynamic effects of upright bicycle ergometry in symptomatic patients with mild, mixed mitral stenosis and regurgitation.

BACKGROUND

Patients with seemingly mild rheumatic mitral valve disease often complain of exertional dyspnea or fatigue. These symptoms are usually ascribed to flow-dependent increases in the gradient across the stenotic mitral valve. Although catheterization studies in these patients may demonstrate an increase in mitral valve gradient proportional to an increase in cardiac output, this approach does not specifically address the underlying mechanism of any observed increases in mitral gradient or left atrial (i.e., pulmonary capillary wedge) pressure. Exercise echocardiography is uniquely suited to the dynamic assessment of exercise-induced hemodynamic changes.

METHODS

Fourteen symptomatic patients with exertional dyspnea and mild mitral stenosis and regurgitation at rest performed symptom-limited upright bicycle ergometry with quantitative two-dimensional, Doppler and color Doppler echocardiographic analysis.

RESULTS

Average pulmonary artery systolic pressure in the 13 patients with adequate spectral signals of tricuspid regurgitation increased from 36 +/- 5 mm Hg (mean +/- SD) at rest to 63 +/- 14 mm Hg at peak exercise (p < 0.001). The mean transmitral pressure gradient in all patients increased from 4.5 +/- 1.4 mm Hg at rest to 12.7 +/- 2.7 mm Hg at peak exercise (p < 0.001). Five patients developed severe mitral regurgitation during exercise.

CONCLUSIONS

Patients with exertional dyspnea and mild mitral stenosis and regurgitation at rest demonstrate a marked increase in pulmonary artery systolic pressure and mean transmitral pressure gradient during dynamic exercise. In a subset of these patients, marked worsening of mitral regurgitation appears to be the underlying mechanism of this hemodynamic deterioration. Because of the small sample size, this novel observation must be considered preliminary with respect to the true prevalence of exercise-related development of severe mitral regurgitation. If additional studies confirm the importance of this phenomenon, it has important implications for the management of patients with rheumatic mitral valve disease.

Overestimation of severity of ischemic/functional mitral regurgitation by color Doppler jet area

Color Doppler jet analysis is widely used to characterize the degree of mitral regurgitation (MR), but the validity of this approach in patients with ischemic or functional MR has not been established. It was hypothesized that color Doppler jet area overestimates the magnitude of MR of ischemic or functional origin. The severity of isolated MR in 170 patients was measured by using Doppler/echocardiography. Group 1 (n = 58) included patients with ischemic or functional MR, and group 2 (n = 112) included those with organic MR. The regurgitant jet area and 2 methods of quantitation (quantitative Doppler and quantitative 2-dimensional echocardiography) were measured simultaneously. In group 1, color jet area was larger (10.6 +/- 5.3 vs 8.2 +/- 5.3 cm2, p = 0.004) but corresponded to a smaller regurgitant volume and regurgitant fraction by quantitative Doppler (28 +/- 14 vs 55 +/- 46 ml, p = 0.0006, and 31 +/- 12% vs 38 +/- 20%, p = 0.02, respectively) and by quantitative 2-dimensional echocardiography (22 +/- 11 vs 49 +/- 40 ml, p < 0.0001, and 27 +/- 12% vs 36 +/- 20%, p = 0.005, respectively). Enlargement of the left-sided chambers was more marked in group 1. In ischemic/functional MR, the diagnosis of severe regurgitation by color Doppler (jet area > 8 cm2) was confirmed by quantitative methods (regurgitant fraction > or = 50%) in only 6% to 11% of patients, whereas it was confirmed in 60% to 73% of patients with organic MR (p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Significant tricuspid regurgitation is a marker for adverse outcome in patients undergoing percutaneous balloon mitral valvuloplasty

OBJECTIVES

This study examined the association between the presence of tricuspid regurgitation and immediate and late adverse outcomes in patients undergoing balloon mitral valvuloplasty.

BACKGROUND

Significant tricuspid regurgitation has an adverse impact on morbidity and mortality in patients undergoing mitral valve surgery for mitral stenosis.

METHODS

We studied 318 consecutive patients (mean [+/- SD] age 54 +/- 15 years) who underwent balloon mitral valvuloplasty and had color Doppler echocardiographic studies before the procedure. Patients were classified into three groups: 221 with no or mild (69%), 60 with moderate (19%) and 37 with severe (12%) tricuspid regurgitation. Clinical follow-up ranged from 6 to 62 months.

RESULTS

Before mitral valvuloplasty, increasing degrees of tricuspid regurgitation were associated with a smaller initial mitral valve area (p < 0.05), higher echocardiographic score (p < 0.05), lower cardiac output (p < 0.01) and higher pulmonary vascular resistance (p < 0.01). Although the initial success rate did not differ significantly between groups, patients with a higher degree of tricuspid regurgitation had less optimal results, as reflected by a smaller absolute increase in mitral valve area (1.02 vs. 0.9 vs. 0.7 cm2, p < 0.01). The estimated 4-year event-free survival rate (freedom from death, mitral valve surgery, repeat valvuloplasty and heart failure) was lower for the group with severe tricuspid regurgitation (68% vs. 58% vs. 35%, p < 0.0001). At 4 years, 94% of patients with mild tricuspid regurgitation were alive compared with 90% and 69%, respectively, of patients with moderate or severe tricuspid regurgitation (p < 0.0001). Cox proportional analysis identified tricuspid regurgitation as an independent predictor of late outcome (p < 0.001).

CONCLUSIONS

Patients with mitral stenosis and severe tricuspid regurgitation undergoing mitral valvuloplasty have advanced mitral valve and pulmonary vascular disease, suboptimal immediate results and poor late outcome.

Visual assessment of valvular regurgitation: comparison with quantitative Doppler measurements

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

Color Doppler regurgitant jet area for evaluating eccentric mitral regurgitation: an animal study with quantified mitral regurgitation

OBJECTIVES

The purpose of the present study was to rigorously evaluate the accuracy of the color Doppler jet area planimetry method for quantifying chronic mitral regurgitation.

BACKGROUND

Although the color Doppler jet area has been widely used clinically for evaluating the severity of mitral regurgitation, there have been no studies comparing the color jet area with a strictly quantifiable reference standard for determining regurgitant volume.

METHODS

In six sheep with surgically produced chronic mitral regurgitation, 24 hemodynamically different states were obtained. Maximal color Doppler jet area for each state was obtained with a Vingmed 750. Image data were directly transferred in digital format to a microcomputer. Mitral regurgitation was quantified by the peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions determined using mitral and aortic electromagnetic flow probes.

RESULTS

Mean regurgitant volumes varied from 0.19 to 2.4 liters/min (mean [+/- SD] 1.2 +/- 0.59), regurgitant stroke volumes from 1.8 to 29 ml/beat (mean 11 +/- 6.2), peak regurgitant volumes from 1.0 to 8.1 liters/min (mean 3.5 +/- 2.1) and regurgitant fractions from 8.0% to 54% (mean 29 +/- 12%). Twenty-two of 24 jets were eccentric. Simple linear regression analysis between maximal color jet areas and peak and mean regurgitant flow rates, regurgitant stroke volumes and regurgitant fractions showed correlation, with r = 0.68 (SEE 0.64 cm2), r = 0.63 (SEE 0.67 cm2), r = 0.63 (SEE 0.67 cm2) and r = 0.58 (SEE 0.71 cm2), respectively. Univariate regression comparing regurgitant jet area with cardiac output, stroke volume, systolic left ventricular pressure, pressure gradient, left ventricular/left atrial pressure gradient, left atrial mean pressure, left atrial v wave pressure, systemic vascular resistance and maximal jet velocity showed poor correlation (0.08 < r < 0.53, SEE > 0.76 cm2).

CONCLUSIONS

This study demonstrates that color Doppler jet area has limited use for evaluating the severity of mitral regurgitation with eccentric jets.

Determinants of functional tricuspid regurgitation in incomplete tricuspid valve closure: Doppler color flow study of 109 patients

OBJECTIVES

The aim of this study was to investigate the association between the pattern of incomplete tricuspid valve closure and the presence of tricuspid regurgitation and to identify factors that determine the severity of regurgitation associated with this pattern.

BACKGROUND

The incomplete tricuspid valve closure pattern (defined as apical displacement of the leaflets) has been described by two-dimensional echocardiography. However, whether this pattern is universally associated with tricuspid regurgitation and the determinants of severity of regurgitation in its presence have not been studied by Doppler color flow mapping.

METHODS

We identified 109 consecutive patients (mean age 62 +/- 17 years) with incomplete tricuspid valve closure who were studied by Doppler color flow mapping. We measured the linear apical displacement of the coaptation point from the tricuspid annulus and the area of displacement between the leaflets and annulus. Right atrial, ventricular and annular dimensions were measured and compared with those in a group of normal subjects.

RESULTS

Tricuspid regurgitation was present in all patients with the incomplete closure pattern; it was mild in 14%, moderate in 19% and severe in 67%. Apical displacement was significantly greater (p < 0.02) in those with severe regurgitation than in those with mild regurgitation or in normal subjects. Tricuspid annulus dilation was the only independent predictor of severity of regurgitation. The right ventricle was not significantly dilated in 32% of patients, and right ventricular systolic pressure was not correlated with the severity of regurgitation and was < 30 mm Hg in 11% of patients.

CONCLUSIONS

Tricuspid regurgitation was associated with incomplete tricuspid valve closure in all patients studied and was moderate to severe in 86%. Impaired coaptation is best reflected by the displacement area between the leaflets and the annulus. High pulmonary pressure and significant right ventricular dilation are not prerequisites for functional tricuspid regurgitation. Annular dilation is the most consistent and important determinant of this lesion.

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

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

Quantification of cardiac jets: theory and limitations

Jet flows are consequences of many cardiac lesions. With the advent of color Doppler flow mapping, these jet flows can be visualized noninvasively. Currently, an intense effort is underway to quantify cardiac jet flows as a means to assess the severity of jet forming lesions. Two techniques, PISA and jet centerline decay, have been suggested as methods to quantify jet flow volume. Although both techniques are theoretically sound, both formulations are based on ideal flow conditions that may not be completely realized in cardiac chambers. Thus, the complex dynamics of cardiac jet flows must be considered as they may diminish the accuracy of flow rate calculations. However, realistic in vitro experiments that mimic the impact of cardiac flow conditions on converging flows and jets, combined with carefully controlled in vivo testing of both PISA and centerline techniques, may eventually produce clinically useful quantification formulations.

New method for quantitatively determining aortic regurgitant volume using Doppler color flow imaging: experimental validation study

We have developed a method to provide the two-dimensional distribution of blood flow velocity and the blood flow volume rate in the ascending aorta from the cross-sectional Doppler color flow image. Regional blood flow velocities were determined by converting color intensities of the cross-sectional Doppler color flow image into the corresponding flow velocities with the correction with the spatial ultrasound beam incident angle. The spatial ultrasound beam incident angle was estimated from the geometric characteristics of the color flow image contour. The method was validated in a steady flow model circuit comparing the calculated flow volume rates by the method with those simultaneously measured by an electromagnetic flowmeter. We performed an open chest dog experiment and calculated the blood flow volume rate at the ascending aorta before and after the aortic regurgitation was made. The calculated ejection flow volume rate and regurgitant volume were validated by the comparison with those simultaneously measured by an electromagnetic flowmeter. Based on these data, we can conclude that the current method provides accurate measurements of regurgitant volume as well as ejection flow volume rate in the ascending aorta.

Assessment of tricuspid regurgitation by Doppler color flow imaging: angiographic correlation

The correlation between data obtained by Doppler color flow imaging and angiographic severity has been investigated in mitral and aortic regurgitation. However, similar studies have not been performed for tricuspid regurgitation (TR). This study was performed to establish the correlation between measurements of regurgitant jet area by Doppler color flow imaging and the angiographic severity of TR. Fifty-four patients with rheumatic heart disease who underwent right ventriculography and transthoracic Doppler color flow imaging were studied. The regurgitant jet area was measured as the largest clearly definable flow disturbance in apical four-chamber and right ventricle inflow views, and expressed in both views as the absolute jet area or as the ratio of maximal jet area to right atrial area. Correlation of all Doppler color flow measurements with angiographic grades of TR were comparable, absolute jet area in apical four-chamber view being closest at r = 0.80. A regurgitant jet area in apical four-chamber view < 5 cm2 predicted minimal or mild TR by angiography with a sensitivity of 78% and a specificity of 100%, whereas a regurgitant jet area > 10 cm2 predicted severe TR with a sensitivity of 92% and a specificity of 91%. Values between 5 and 10 cm2 predicted moderate TR with a sensitivity of 89% and a specificity of 89%. Sensitivity and specificity were not improved with use of the ratio of jet area to right atrial area or with use of right ventricle inflow view. Thus, Doppler color flow jet measurements correlate closely with angiographic results in the evaluation of TR.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic assessment of artificial heart valves: British Society of Echocardiography position paper

Images

Cardiac motion can alter proximal isovelocity surface area calculations of regurgitant flow

OBJECTIVES

This study addressed the hypothesis that motion of the surface containing a regurgitant orifice relative to the Doppler ultrasound transducer can cause differences between actual flow rate and calculations based on the proximal flow convergence technique.

BACKGROUND

In vitro studies quantitating regurgitant flow rate by proximal flow convergence have been limited to stationary orifices. Clinically, however, valve leaflets generally move relative to the ultrasound transducer during the cardiac cycle and can move at velocities important relative to the measured color aliasing velocities. The transducer therefore senses the vector sum of actual flow velocity toward the orifice and orifice velocity relative to the transducer. This can cause potential overestimation or underestimation of true flow rate, depending on the direction of surface motion.

METHODS

The hypothesis was explored computationally and tested by pumping fluid at a constant flow rate through an orifice in a plate moving at 0 to 8 cm/s (velocities comparable to those described clinically for mitral and tricuspid annulus motion toward an apical transducer).

RESULTS

Surface motion in the same direction as flow caused overestimation of the aliasing radius and calculated flow rate. Surface motion opposite to the direction of flow (typical for mitral and tricuspid regurgitation viewed from the apex or esophagus) caused underestimation of actual flow rate. The underestimation was greater for lower aliasing velocities (36 +/- 11% for 10 cm/s vs. 23 +/- 6% for 20 cm/s). Correcting for surface motion provided excellent agreement with actual values (y = 0.97x + 0.10, r = 0.99, SEE = 0.17 liters/min).

CONCLUSIONS

Physiologic motion of the surface containing a regurgitant orifice can cause substantial differences between actual flow rate and that calculated by the proximal flow convergence technique. Los aliasing velocities used to optimize that technique can magnify this effect. Such errors can be minimized by using higher aliasing velocities (compatible with the need to measure the aliasing radius) or eliminated by correcting for surface velocity determined by an M-mode ultrasound scan.

Effects of adjacent surfaces of different shapes on regurgitant jet sizes: an in vitro study using color Doppler imaging and laser-illuminated dye visualization

OBJECTIVES

The present study was designed to estimate the influence of different-shaped adjacent surfaces on regurgitant jets as assessed by color Doppler imaging and laser-illuminated dye optical visualization.

BACKGROUND

Because color Doppler techniques provide real-time two-dimensional imaging of flow, the evaluation of valvular regurgitation by analysis of variance-encoded regurgitant jets by this method has been widely used in clinical studies. However, recent studies have demonstrated that color Doppler jet sizes are affected not only by several hemodynamic factors and instrument settings but also by the interaction between jets and adjacent wall surfaces. In clinical conditions, jets may interact with adjacent walls of variable shapes that might have different effects on the jet size.

METHODS

An in vitro model was constructed consisting of a rigid, optically clear receiving chamber that had no outlet resistance and had a pulsatile pump ejecting through 1.5, 2.3 and 3.1 mm2 inflow orifices into the chamber. The surfaces were flat or smoothly and equally curved, convex and concave aluminum positioned at 0, 2 and 4 mm from and to the side of the inflow orifices. The pump was run with stroke volumes from 0.5 to 3.0 ml and with a pulse frequency of 70 beats/min. The echocardiographic and laser beams were aimed at the inflow orifice imaging jets perpendicular to the surfaces (vertical view) through the central plane of the jet flows. Maximal jet areas were measured by both color Doppler techniques and laser-illuminated dye visualization.

RESULTS

Color Doppler study showed fair correlation between the jet areas and the stroke volumes (r = 0.83 to 0.99), but the jet sizes under different surface conditions were variable. All the surface jet areas at a jet-surface distance of 0 and 2 mm were smaller than free jet areas at the same stroke volume for both flat and convex surfaces (p < 0.001). Flow constraint by the concave surface resulted in the smallest jet areas (p < 0.001). The color Doppler jet areas on the curved surfaces were significantly smaller than the laser-illuminated dye visualization jet areas (p < 0.01 to 0.0001). However, at intermediate jet-surface distances (4 mm and sometimes 2 mm with higher velocity flows), jet interaction with the flat and especially with the convex surface resulted in larger jets. This effect was most pronounced on dye fluorescence studies because flow around these jets consisted mainly of low velocity vortical events with only partial surface adherence and these low velocity swirling flows were not well imaged by color Doppler technique.

CONCLUSIONS

Our study suggests that the different-shaped adjacent surfaces with different degrees of flow alterations resulted in variable decreases in jet size and that color Doppler imaging could not encode and image the angled and low velocity swirling events well when jets flowed along the curved surfaces. These effects need to be taken into account when interpreting color Doppler images.

Evaluation of mitral valve repair by intraoperative transoesophageal echocardiography

BACKGROUND

Mitral valve repair is the procedure of choice in the surgical management of mitral regurgitation. Intraoperative confirmation of successful repair is essential to the effectiveness of this procedure.

AIMS

The aims of this study were: (a) to compare intraoperative transoesophageal echocardiography (TOE) with the surgeon's assessment of valve competence; (b) to assess the impact of routine intraoperative imaging on the hospital echocardiography laboratory.

METHODS

Eighty-six consecutive patients undergoing mitral valve repair formed the study population. Valve competence following repair was assessed intraoperatively by: TOE; saline insufflation of the flaccid left ventricle; and evaluation of the pulmonary capillary wedge pressure for the presence of a significant V wave.

RESULTS

TOE demonstrated successful valve repair (< or = 1 + residual regurgitation) in 75 patients (87%) and detected significant residual regurgitation (> or = 3+) in seven (8.2%). The mechanism of regurgitation was also clearly shown. Of these seven patients, four underwent immediate valve replacement, two had successful revision of the initial repair and one required valve replacement one week later. In all seven patients the valve repair had been assessed as successful by saline testing and only one had a post-repair V wave 10 mmHg above the mean pulmonary capillary wedge pressure. In 30 non-selected patients the imaging equipment was required in theatre for 43 +/- 18 minutes.

CONCLUSIONS

TOE is currently the most sensitive method for detection and quantitation of residual mitral regurgitation following valve repair. Evaluation can be performed within a similar time to that required for one complete transthoracic study and can usually be performed with minimal disruption to the hospital echocardiography laboratory.

Color flow imaging compared with quantitative Doppler assessment of severity of mitral regurgitation: influence of eccentricity of jet and mechanism of regurgitation

OBJECTIVES

To determine the influence of jet eccentricity and mechanism of mitral regurgitation, we examined 1) the relation between jet extent and severity of mitral regurgitation, and 2) the use of Doppler color flow imaging for quantitation of mitral regurgitation.

BACKGROUND

Doppler color flow imaging is widely used to assess mitral regurgitation. However, whether, how and in which subgroups it can quantify regurgitation remain controversial.

METHODS

In 80 patients with mitral regurgitation, results of color flow Doppler studies obtained in two orthogonal apical views were prospectively compared with quantitative Doppler measurement of the regurgitant volume and the regurgitant fraction. Comparisons were made according to the eccentricity of the jet (group 1 eccentric jets, n = 29; group 2 central jets, n = 51); group 2 was subdivided according to the mechanism of mitral regurgitation (group 2a organic, n = 27; group 2b ischemic or functional, n = 24).

RESULTS

Globally, weak correlations were found between regurgitant volume and jet area (r = 0.57) and regurgitant fraction and jet area/left atrial area ratio (r = 0.65). Groups 1 and 2 showed a correlation between regurgitant volume and jet area (r = 0.68 and r = 0.65, respectively, p < 0.0001), but the slope was steeper in group 2 than in group 1 (0.22 vs. 0.06, p < 0.0001). The same jet area corresponded to more severe regurgitation in group 1 than in group 2 (jet > or = 8 cm2, regurgitant volume 113 +/- 55 vs. 43 +/- 21 ml, p < 0.0001). Similarly, for comparable regurgitant volumes (24 +/- 22 vs. 29 +/- 11 ml, p = NS), group 2a had a smaller jet area than did group 2b (5.3 +/- 6 vs. 9.6 +/- 6 cm2, p < 0.02). Quantitation of regurgitation by Doppler color flow imaging was unreliable in group 1; in group 2b, the regression line between regurgitant fraction and jet area/left atrial area ratio was close to the identity line.

CONCLUSIONS

Mitral regurgitant jet eccentricity and mechanism influence jet extent. The same regurgitant volume produces smaller jet areas for eccentric compared with central jets and for central organic compared with ischemic or functional regurgitation. Quantitation of regurgitation using Doppler color flow imaging is possible in ischemic or functional regurgitation but inappropriate in eccentric jets, where quantitative Doppler study should be recommended.

Increased heart rate can cause underestimation of regurgitant jet size by Doppler color flow mapping

OBJECTIVES

This study addressed the hypothesis that at a constant peak flow rate, an increasing heart rate could decrease the maximal apparent jet size by Doppler color flow mapping.

BACKGROUND

Recent studies have attempted to predict the severity of regurgitation from maximal jet area by Doppler color flow mapping, which correlates with flow rate for free jets at constant driving pressure and steady flow. In patients, however, maximal jet area exists for only a limited time per beat and the likelihood of visualizing it by Doppler color flow mapping depends on its duration relative to the color frame sampling rate. Increased heart rate could potentially diminish apparent jet size, particularly at slow frame rates that may not permit visualization of the maximal jet area in all beats.

METHODS

This interaction was examined in pulsatile flow, holding orifice size and peak flow rate constant and varying pump pulse rate (70 to 180 beats/min) and frame rate (three rates) for jets of low and high momentum. Maximal jet area was measured in 10 consecutive beats at each pulse rate and frame rate and averaged.

RESULTS

For the low momentum jet, the 10-beat average of peak jet area decreased progressively with increasing pulse rate. As pulse rate increased from 70 to 180 beats/min, maximal jet area decreased 23% at the fastest frame rate and 42% at the slowest frame rate, with prominent beat to beat variability. Jet area decreased 13% to 20% at pulse rates as low as 90 beats/min. In contrast, for the high momentum jet, maximal jet area decreased by < or = 9% from low to high pulse rate at any frame rate.

CONCLUSIONS

Increased heart rate can cause underestimation of apparent jet size by Doppler color flow mapping for a given peak flow rate, particularly for jets with low momentum and delayed penetration into the receiving chamber. This observation may be relevant to acute severe regurgitation with increased heart rate in which such underestimation has been reported, as well as to right-sided lesions and children with rapid heart rates. It will also affect new techniques proposed to quantify regurgitation on the basis of velocities derived from Doppler color flow images. In practice, this effect can be reduced by increasing frame rate and selecting maximal apparent jet size at rapid heart rates and should be considered in relating jet size to the severity of regurgitation.