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

Echocardiographic 3D-guided 2D planimetry in quantifying left-sided valvular heart disease

Echocardiographic 3D-guided 2D planimetry can improve the accuracy of valvular disease assessment. Acquisition of 3D pyramidal dataset allows subsequent multiplanar reconstruction with accurate orthogonal plane alignment to obtain the correct borders of an anatomic orifice or flow area. Studies examining the 3D-guided 2D planimetry approach in left-sided valvular heart disease were identified and reviewed. The strongest evidence exists for estimating mitral valve area in patients with rheumatic mitral valve stenosis and vena contracta area in patients with mitral regurgitation (both primary and secondary). 3D-guided approach showed excellent feasibility and reproducibility in most studies, as well as time efficiency and good correlation with reference and comparator methods. Therefore, 3D-guided 2D planimetry can be used as an important clinical tool in quantifying left-sided valvular heart disease, especially mitral valve disorders.

Anatomic regurgitant orifice area obtained using 3D-echocardiography as an indicator of severity of mitral regurgitation in dogs with myxomatous mitral valve disease

OBJECTIVES

To determine feasibility and repeatability of measuring the anatomic regurgitant orifice area (AROA) using real-time three-dimensional transthoracic echocardiography (RT3DE) in dogs with myxomatous mitral valve disease (MMVD), and to investigate differences in the AROA of dogs with different disease severity and in different American College of Veterinary Internal Medicine (ACVIM) stages.

ANIMALS

Sixty privately-owned dogs diagnosed with MMVD.

METHODS

The echocardiographic database of our institution was retrospectively searched for dogs diagnosed with MMVD and RT3DE data set acquisition. Dogs were classified into mild, moderate, or severe MMVD according to a Mitral Regurgitation Severity Score (MRSS), and into stage B1, B2 or C according to ACVIM staging. The RT3DE data sets were imported into dedicated software and a short axis plane crossing the regurgitant orifice was used to measure the AROA. Feasibility, inter- and intra-observer variability of measuring the AROA was calculated. Differences in the AROA between dogs in different MRSS and ACVIM stages were investigated.

RESULTS

The AROA was measurable in 60 data sets of 81 selected to be included in the study (74%). The inter- and intra-observer coefficients of variation were 26% and 21%, respectively. The AROA was significantly greater in dogs with a severe MRSS compared with dogs with mild MRSS (p=0.045). There was no difference between the AROA of dogs in different ACVIM clinical stages.

CONCLUSIONS

Obtaining the AROA using RT3DE is feasible and might provide additional information to stratify mitral regurgitation severity in dogs with MMVD. Diagnostic and prognostic utility of the AROA deserves further investigation.

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

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

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

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

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

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

Valve anatomy and function with transthoracic three-dimensional echocardiography: advantages and limitations of instantaneous full-volume color Doppler imaging

Three-dimensional echocardiography (3DE) is becoming part of everyday clinical practice worldwide. However, 3DE requires adequate electrocardiographic and respiratory gating and it complements instead of replacing bidimensional echocardiography (2D). The instantaneous full-volume echocardiography technique is trying to overcome some of these limitations and to present an effective alternative to 2D echocardiography. In this article we aim to review the contribution of 3DE to our knowledge of anatomic and functional valvular anatomy and the potential advantages of instantaneous full-volume color Doppler echocardiography.

Use of real time three-dimensional transesophageal echocardiography in intracardiac catheter based interventions

BACKGROUND

Real-time three-dimensional (RT3D) echocardiography is a recently developed technique that is being increasingly used in echocardiography laboratories. Over the past several years, improvements in transducer technologies have allowed development of a full matrix-array transducer that allows acquisition of pyramidal-shaped data sets. These data sets can be processed online and offline to allow accurate evaluation of cardiac structures, volumes, and mass. More recently, a transesophageal transducer with RT3D capabilities has been developed. This allows acquisition of high-quality RT3D images on transesophageal echocardiography (TEE). Percutaneous catheter-based procedures have gained growing acceptance in the cardiac procedural armamentarium. Advances in technology and technical skills allow increasingly complex procedures to be performed using a catheter-based approach, thus obviating the need for open-heart surgery.

METHODS

The authors used RT3D TEE to guide 72 catheter-based cardiac interventions. The procedures included the occlusion of atrial septal defects or patent foramen ovales (n=25), percutaneous mitral valve repair (e-valve clipping; n=3), mitral balloon valvuloplasty for mitral stenosis (n=10), left atrial appendage obliteration (n=11), left atrial or pulmonary vein ablation for atrial fibrillation (n=5), percutaneous closures of prosthetic valve dehiscence (n=10), percutaneous aortic valve replacement (n=6), and percutaneous closures of ventricular septal defects (n=2). In this review, the authors describe their experience with this technique, the added value over multiplanar two-dimensional TEE, and the pitfalls that were encountered.

RESULTS

The main advantages found for the use RT3D TEE during catheter-based interventions were (1) the ability to visualize the entire lengths of intracardiac catheters, including the tips of all catheters and the balloons or devices they carry, along with a clear depiction of their positions in relation to other cardiac structures, and (2) the ability to ability to demonstrate certain structures in an "en face" view, which is not offered by any other currently available real-time imaging technique, enabling appreciation of the exact nature of the lesion that is undergoing intervention.

CONCLUSION

RT3D TEE is a powerful new imaging tool that may become the technique of choice and the standard of care for guidance of selected percutaneous catheter-based procedures.

A multiplanar three dimensional echocardiographic study of mitral valvar annular function in children with normal and regurgitant valves

INTRODUCTION

The mitral valvar complex is difficult to visualise accurately in only two dimensions. Three-dimensional echocardiography gives new insight into the dynamic changes of intra-cardiac structures during the cardiac cycle. The aim of this study was to study the mitral annulus in systole and diastole in normal children using three-dimensional echocardiography, and to analyse the effect of regurgitation on annular function.

MATERIALS AND METHODS

Three-dimensional echocardiographic datasets, acquired in 11 consecutive subjects with mitral regurgitation, and 20 normal subjects, were analysed offline using simultaneous multiplanar review.

RESULTS

The mitral valvar annular area decreased in diastole, and increased in systole, in both groups. The annulus in patients with mitral regurgitation is dilated compared to normal subjects, the systolic value for those with regurgitation having a mean of 6.79 plus or minus 2.55 centimetres2/metres2, and the diastolic value a mean of 5.01 plus or minus 1.78 centimetres2/metres2, as opposed to a systolic mean value of 5.28 centimetres2/metres2 plus or minus 1.68, p = 0.091, and diastolic mean value of 3.05 centimetres2/metres2 plus or minus 0.90, in normal subjects (p less than 0.0001). The proportional change in mitral valvar annular area from systole to diastole showed a trend towards being smaller in those with mitral regurgitation, although this did not reach significance (24.8% versus 41.13%, p equal to 0.249). Analysis of subgroups of patients with moderate or severe mitral regurgitation showed mitral excursion, expressed as percentage of left ventricular length, to be significantly less than in normal subjects, at 12.78 plus or minus 5.10% versus 15.84 plus or minus 4.23% (p equal to 0.012).

CONCLUSIONS

Mitral valvar annular area in children decreases in diastole, and increases in systole. In those with mitral regurgitation, the annulus is dilated and the dynamic annular function is depressed.

Three-dimensional adult echocardiography: where the hidden dimension helps

The introduction of three-dimensional (3D) imaging and its evolution from slow and labor-intense off-line reconstruction to real-time volumetric imaging is one of the most significant developments in ultrasound imaging of the heart of the past decade. This imaging modality currently provides valuable clinical information that empowers echocardiography with new levels of confidence in diagnosing heart disease. One major advantage of seeing the additional dimension is the improvement in the accuracy of the evaluation of cardiac chamber volumes by eliminating geometric modeling and the errors caused by foreshortened views. Another benefit of 3D imaging is the realistic views of cardiac valves capable of demonstrating numerous pathologies in a unique, noninvasive manner. This article reviews the major technological developments in 3D echocardiography and some of the recent literature that has provided the scientific basis for its clinical use.

Real-time three-dimensional echocardiography: an update

Real-time three-dimensional echocardiography (RT3DE) is the only on-line 3D method based on real-time volumetric scanning, as compared with other 3D imaging techniques such as computed tomography and magnetic resonance imaging, which are based on post-acquisition reconstruction and not on volumetric scanning. In recent years, several studies have revealed possible advantages of 3DE in daily clinical practice. The aim of this manuscript is to give a brief review of the development of the clinical applications of RT3DE.

Evaluation of hypoxemic patients with transesophageal echocardiography

OBJECTIVE

To summarize the use of transesophageal echocardiography when investigating hypoxemic patients in the intensive care unit, to assess its risks and benefits, and to evaluate which diseases of the cardiopulmonary system, mediastinum, and thorax it will help to guide therapeutic decisions.

DESIGN

A review of current literature and practice guidelines was performed.

RESULTS

Hypoxemia, due to a number of different reasons, is common in critically ill patients. Many diagnoses and therapeutic decisions have to rely on good-quality imaging. However, transthoracic echocardiography often produces poor-quality pictures; other imaging modalities involve transferring unstable patients to the imaging suite. Transesophageal echocardiography can safely be performed at the bedside and generates excellent image quality.

CONCLUSION

Transesophageal echocardiography is a safe procedure that can be performed at the bedside and that produces high-quality images of the heart, its related structures, and its function. It helps detect extracardiac pathology leading to hypoxemia and may be used to guide fluid resuscitation and optimize tissue oxygenation.

[Three-dimensional echography: cardiovascular applications]

Real-time three-dimensional echocardiography is currently used in a standard echocardiographic examination. Volume-rendered images better identify and locate anatomic structures and improve our comprehensive approach to various heart diseases. The assessment of mitral valve disease and congenital cardiopathies and the measurement of left ventricular mass, volume, and ejection fraction are the three main applications of three-dimensional echocardiography. Three-dimensional vascular imaging is an emerging and promising application of three-dimensional echography. The near future of three-dimensional echography requires the integration of all modalities of conventional echography in three dimensional probes, a higher image resolution compared to the current situation, as well as the development of real-time three-dimensional probes dedicated to transesophageal cardiac or vascular examination.

Three-Dimensional Echocardiography

Over the past 3 decades, echocardiography has become a major diagnostic tool in the arsenal of clinical cardiology for real-time imaging of cardiac dynamics. More and more, cardiologists' decisions are based on images created from ultrasound wave reflections. From the time ultrasound imaging technology provided the first insight into the human heart, our diagnostic capabilities have increased exponentially as a result of our growing knowledge and developing technology. One of the most significant developments of the last decades was the introduction of 3-dimensional (3D) imaging and its evolution from slow and labor-intense off-line reconstruction to real-time volumetric imaging. While continuing its meteoric rise instigated by constant technological refinements and continuing increase in computing power, this tool is guaranteed to be integrated in routine clinical practice. The major proven advantage of this technique is the improvement in the accuracy of the echocardiographic evaluation of cardiac chamber volumes, which is achieved by eliminating the need for geometric modeling and the errors caused by foreshortened views. Another benefit of 3D imaging is the realistic and unique comprehensive views of cardiac valves and congenital abnormalities. In addition, 3D imaging is extremely useful in the intraoperative and postoperative settings because it allows immediate feedback on the effectiveness of surgical interventions. In this article, we review the published reports that have provided the scientific basis for the clinical use of 3D ultrasound imaging of the heart and discuss its potential future applications.

Comparison of orifice area by transthoracic three-dimensional Doppler echocardiography versus proximal isovelocity surface area (PISA) method for assessment of mitral regurgitation

Effective regurgitant orifice area is a useful index of the severity of mitral regurgitation (MR). The calculation of regurgitant orifice area using the proximal isovelocity surface area (PISA) method has some technical limitations. Three-dimensional reconstruction of the MR jet was performed using the Live 3D system on a Sonos 7500 to measure regurgitant orifice area directly in 109 cases of MR. Regurgitant orifice area was also measured by quantitative 2-dimensional echocardiography and by the PISA method. To analyze the shape of the regurgitant orifice, the ratio of the long axis to the short axis of the orifice (the L/S ratio) was calculated. Regurgitant orifice area on 3-dimensional echocardiography showed an almost identical correlation with that obtained by quantitative echocardiography (r = 0.91, p <0.0001, slope = 0.97) regardless of the L/S ratio. It was also significantly correlated with orifice area obtained using the PISA method (r = 0.93, p <0.0001). However, orifice area on 3-dimensional echocardiography was significantly larger than that obtained using the PISA method in the whole study group and in the 62 cases of MR with L/S ratios >1.5, whereas the correlation was almost identical in cases of MR with L/S ratios < or =1.5. Orifice area obtained using the PISA method also underestimated that obtained by quantitative echocardiography in cases of MR with L/S ratios >1.5. Three-dimensional echocardiography provided robust values independent of the eccentricity of the MR jet or of cardiac rhythm. In conclusion, the direct measurement of the regurgitant orifice area of MR with 3-dimensional Doppler echocardiography could be a promising method to overcome the limitations of the PISA method, especially in cases of MR with elliptic orifice shapes.

Recurrent hemiparesis due to anterior mitral leaflet myxomas

Strokes, cardiac or noncardiac, generally affect the elderly and only occasionally occur in children. A tendency to stroke occurs in cyanotic congenital heart disease; however, this report describes two female patients, aged 6 years and 4 years, who had no cyanotic disease. The first patient was admitted to the hospital after the first stroke but suffered a second one after admission. Her initial cardiac examination was normal. The other patient was admitted after a second right-sided hemiparesis. A mild pansystolic ejection murmur was observed at the lower left sternal border on auscultation; slight late diastolic murmurs with opening snap were found in the mitral valve area, and the second heart sound was increased. Transthoracic echocardiography revealed a mass in the anterior mitral valve in both patients. These masses were completely removed surgically and pathology revealed myxomas. Hemiparesis completely resolved after surgical and medical treatment. The clinical manifestations of cardiac tumors primarily depend on their number, size, location, and histology. Strokes and anterior mitral valve masses are extremely rare in children. In the two cases reported here, anterior mitral valve myxomas caused systemic embolization as a result of their location. Echocardiography should be performed early in patients presenting with recurrent strokes to exclude such pathology.

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

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

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Pointwise assessment of three-dimensional computer reconstruction of mitral leaflet surfaces from rotationally scanned echocardiograms in vitro

Three-dimensional transesophageal echocardiography offers promise for improved understanding of mitral leaflet pathology, but it has not been validated quantitatively, nor has the minimum number of imaging planes for satisfactory reconstruction been determined with a rotational scanning geometry. This study assessed its accuracy in vitro by comparing, on a 1 x 1-mm grid, the surfaces of mitral leaflets derived from 5-degree rotational ultrasonic scans with those derived from laser scans of casts of the atrial side of the leaflets. Overall, the ultrasonically derived surface had a mean absolute deviation of 0.65 +/- 0.12 mm from the laser-derived surface. Using only alternate imaging planes (10-degree increments) made no significant difference in the overall distribution of deviations (P =.56), although the distributions on some individual specimens differed markedly. We conclude that 5-degree rotational scanning in vitro can reconstruct the mitral valve leaflets with sufficient accuracy and detail to render clinically important features.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Three-dimensional echocardiography: historical development and current applications

Three-dimensional (3D) echocardiography facilitates spatial recognition of intracardiac structures, potentially enhancing diagnostic confidence of conventional echocardiography. The accuracy of 3D images has been validated in vitro and in vivo. In vitro, a detail 1.0 mm in dimension and 2 details separated by 1.0 mm can be identified from a volume-rendered 3D image. In vitro 3D volume measurements are underestimated by approximately 4.0 mL. In vivo, left ventricular volume measurements correlate highly with both cineventriculography (limits of agreement +/-18 mL for end diastole and +/-10 mL for end systole) and magnetic resonance imaging, including measurements for patients with functionally single ventricles. Studies on congenital heart lesions have shown good accuracy and good reproducibility of dynamic "surgical" reconstructions of septal defects, aortoseptal continuity, atrioventricular junction, and both left and right ventricular outflow tract morphology. Transthoracic 3D echocardiography was shown feasible in 81% to 96% of patients with congenital heart defects and provided additional information to that available from conventional echocardiography in 36% of patients, mainly in more detailed description of mitral valve morphology, aortoseptal continuity, and atrial septum. In patients with mitral valve insufficiency, 3D echocardiography was shown to be accurate in the quantification of the dynamic mechanism of mitral regurgitation and in the assessment of mitral commissures in patients with mitral stenosis. This includes not only valve tissue reconstruction but also color flow intracardiac jets. Three-dimensional reconstructions of the aortic valve were achieved in 77% of patients, with an accuracy of 90%. In conclusion, the role of 3D echocardiography, which continues to evolve, shows promise in the assessment of congenital and acquired heart disease.

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

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

Quantitative assessment of severity of ventricular septal defect by three-dimensional reconstruction of color Doppler-imaged vena contracta and flow convergence region

BACKGROUND

The aim of the present study was to investigate the feasibility and potential value of the computer-controlled, 3D, echocardiographic reconstruction of the color Doppler-imaged vena contracta (CDVC) and the flow convergence (FC) region as a means of accurately and quantitatively estimating the severity of a ventricular septal defect (VSD).

METHODS AND RESULTS

We performed a 3D reconstruction of the CDVC and the FC region in 19 patients with an isolated VSD using an ultrasound system interfaced with a Tomtec computer. The variable asymmetric geometry of the CDVC and the FC region could be 3D-visualized in all patients. The 3D-measured areas of CDVC correlated well with volumetric measurements of the severity of VSD (r=0.97, P:<0.001). Regression analysis between the shunt flow rate (calculated from the product of the area of CDVC and the continuous Doppler-derived velocity time integral) and the corresponding reference results (calculated by cardiac catheterization) demonstrated a close correlation (r=0.95, P:<0.001). There was also a good correlation between shunt flow rates calculated using the conventional 2D, 1-axis measurement of the FC isovelocity surface area with the hemispheric assumption (r=0.95, P:<0.001); shunt flow rates calculated using 3D, 3-axis measurements of the FC region (r=0.97, P:<0.01); and reference results by cardiac catheterization. However, the 2D method substantially underestimated the actual shunt flow rate.

CONCLUSIONS

The 3D reconstruction of the CDVC and the FC region may aid in quantifying the severity of VSD.

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

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Evaluation of left ventricular systolic function by 3D echocardiography: a comparative study with X-ray angiography and radionuclide angiography

OBJECTIVE

the aim of this study was to evaluate left ventricular systolic function by 3D ultrasound as compared to with radionuclide and X-ray angiographies.

METHODS

one hundred and four patients were examinated by 3D ultrasound (3D-US) but only 72 examinations were successful. Thirty patients were investigated by 3D-US, M-mode US or bidimensional (2D) US, and X-ray angiography (group I) and 42 patients were investigated by 3D-US, M-mode, or 2D, and radionuclide angiography (group II).

RESULTS

the correlation between ejection fraction (EF) evaluated by 3D-US and reference methods was found to be good and similar for the two groups (r=0.75; P<10(-4) for group I and r=0.76; P<10(-4) for group II). The correlation between EF calculated by conventional 2D-US and by reference methods was lower (r=0.60; P=0.04 for group I and r=0.54; P=0.001 for group II). The correlation between EF evaluated by 3D- and 2D-US was modest (r=0. 55; P=0.001 for the whole group). The correlation between 3D-US left ventricle end-diastolic volume (EDV) and end-systolic volume (ESV) and those evaluated by X-ray angiography was also modest (r=0.33; NS for EDV and r=0.60; P<10(-4) for ESV). The correlations between EDV and ESV in 3D-US, and those evaluated from radionuclide angiography were fairly good and in the same range (r=0.76; P<10(-4) and r=0.87; P<10(-4)).

CONCLUSION

the 3D-US system using a rotating probe in an apical view is valuable for evaluation of left ventricular systolic function.