Three-dimensional echocardiography: historical development and current applications

Additive value of 3D-echo in prediction of immediate outcome after percutaneous balloon mitral valvuloplasty

Background

Results of percutaneous balloon mitral valvuloplasty (BMV) are basically dependent on suitable patient selection. Currently used two-dimensional (2D) echocardiography (2DE) scores have many limitations. Three-dimensional (3D) echocardiography (3DE)-based scores were developed for better patient selection and outcome prediction. We aimed to compare between 3D-Anwar and 2D-Wilkins scores in mitral assessment for BMV, and investigate the additive value of 3DE in prediction of immediate post-procedural outcome. Fifty patients with rheumatic mitral stenosis and candidates for BMV were included. Patients were subjected to 2D- and real-time 3D-transthoracic echocardiography (TTE) before and immediately after BMV for assessing MV area (MVA), 2D-Wilkins and 3D-Anwar score, commissural splitting, and mitral regurgitation (MR). Transesophageal echocardiography (TEE) was also undertaken immediately before and intra-procedural. Percutaneous BMV was performed by either multi-track or Inoue balloon technique.

Results

The 2DE underestimated post-procedural MVA than 3DE (p = 0.008). Patients with post-procedural suboptimal MVA or significant MR had higher 3D-Anwar score compared to 2D-Wilkins score (p = 0.008 and p = 0.03 respectively). The 3D-Anwar score showed a negative correlation with post-procedural MVA (r = − 0.48, p = 0.001). Receiver operating characteristic (ROC) curve analysis for both scores revealed superior prediction of suboptimal results by 3D-Anwar score (p < 0.0001). The 3DE showed better post-procedural posterior-commissural splitting than 2DE (p = 0.004). Results of both multi-track and Inoue balloon were comparable except for favorable posterior-commissural splitting by multi-track balloon (p = 0.04).

Conclusion

The 3DE gave valuable additive data before BMV that may predict immediate post-procedural outcome and suboptimal results.

Electronic supplementary material

The online version of this article (10.1186/s43044-019-0019-x) contains supplementary material, which is available to authorized users.

Comprehensive echocardiographic imaging of atrioventricular valves in children with atrioventricular septal defect: Accuracy of 2D and 3D imaging and reasons for disagreement

OBJECTIVE

To compare the accuracy and reasons for disagreement of two-dimensional (2D) and three-dimensional (3D) echocardiography findings in the assessment of the atrioventricular valve complex in patients with atrioventricular septal defect.

METHODS

A total of 20 children (mean age 8 months) with atrioventricular septal defect were enrolled prospectively into this study. The accuracy of and the reasons for disagreement in the assessment of the atrioventricular valve features were analyzed between 2D and 3D echocardiography and surgical findings.

RESULTS

We found that in assessing the Rastelli type and the extension of the inferior leaflet into the right ventricle, 3D echocardiography was more accurate compared to 2D echocardiography. In all other features, 2D and 3D echocardiography showed similar accuracy. A significant reason for inaccuracy by both echo modalities was that the technique itself could not visualize the feature, although the image quality was considered to be adequate. In most cases, where it was not possible to visualize the atrioventricular feature by 2D, it was possible by 3D, and vice versa.

CONCLUSION

The accuracy of 2D and 3D echocardiography and understanding the potential reasons for disagreements in assessing the atrioventricular valve complex with 2D and 3D can guide the use of those two techniques when combining them in the clinical practice.

Three-Dimensional Reconstruction of Intracardiac Anatomy Using CTA and Surgical Planning for Double Outlet Right Ventricle: Early Experience at a Tertiary Care Congenital Heart Center

BACKGROUND

Although transthoracic echocardiography (TTE) routinely establishes the diagnosis of double outlet right ventricle (DORV), it can be suboptimal for depicting exact ventricular septal defect (VSD) position, especially with respect to the outflow tracts. Advanced imaging with computed tomography angiography (CTA) can help visualize structures and relationships not easily seen by echo. Using computer-aided design, we have the ability to create three-dimensional (3D) models of the intracardiac anatomy, which can be helpful for better depicting the overall anatomy to assist surgical planning.

METHODS

Patients with a diagnosis of DORV were retrospectively reviewed at our institution from October 2013 to April 2015. Patients who preoperatively underwent both TTE and CTA with 3D reconstruction of the intracardiac anatomy were included. Computed tomography angiography findings with 3D intracardiac model creation were compared to the surgical findings.

RESULTS

Twenty-five patients underwent surgical repair of DORV during the study period. Five patients had CTA with 3D reconstruction, in addition to the standard TTE images, and were included in the study. In all five cases, CTA with 3D reconstruction of the intracardiac anatomy accurately depicted the VSD position relative to important adjacent structures, including the outflow tracts.

CONCLUSION

Three-dimensional reconstruction of the intracardiac anatomy using CTA data can provide accurate data for presurgical planning of DORV repair and has the potential for being especially useful in patients for whom intracardiac anatomy and VSD position cannot be well seen by TTE. A larger prospective analysis is warranted to help validate this approach.

Reproducibility of a novel echocardiographic 3D automated software for the assessment of mitral valve anatomy

Background

3D transesophageal echocardiography (TEE) is superior to 2D TEE in quantitative anatomic evaluation of the mitral valve (MV) but it shows limitations regarding automatic quantification. Here, we tested the inter-/intra-observer reproducibility of a novel full-automated software in the evaluation of MV anatomy compared to manual 3D assessment.

Methods

Thirty-six out of 61 screened patients referred to our Cardiac Imaging Unit for TEE were retrospectively included. 3D TEE analysis was performed both manually and with the automated software by two independent operators. Mitral annular area, intercommissural distance, anterior leaflet length and posterior leaflet length were assessed.

Results

A significant correlation between both methods was found for all variables: intercommissural diameter (r = 0.84, p < 0.01), mitral annular area (r = 0.94, p > 0, 01), anterior leaflet length (r = 0.83, p < 0.01) and posterior leaflet length (r = 0.67, p < 0.01). Interobserver variability assessed by the intraclass correlation coefficient was superior for the automatic software: intercommisural distance 0.997 vs. 0.76; mitral annular area 0.957 vs. 0.858; anterior leaflet length 0.963 vs. 0.734 and posterior leaflet length 0.936 vs. 0.838. Intraobserver variability was good for both methods with a better level of agreement with the automatic software.

Conclusions

The novel 3D automated software is reproducible in MV anatomy assessment. The incorporation of this new tool in clinical MV assessment may improve patient selection and outcomes for MV interventions as well as patient diagnosis and prognosis stratification. Yet, high-quality 3D images are indispensable.

Novel Echocardiographic Indices as Predictors of Immediate Recurrence after Undersized Ring Annuloplasty for Ischemic Mitral Regurgitation

BACKGROUND AND AIM

Ischemic mitral regurgitation (IMR) is among the most serious complications of myocardial infarction which doubles the late mortality; mainly treated by undersizing ring annuloplasty. To find some preoperative echocardiographic indices that predict immediate failure of mitral valve annuloplasty (MVA), we designed the present study with more focusing on some novel parameters.

METHOD

Transthoracic echocardiography (TTE) indices of consecutive patients referred with 3+ or 4+ IMR were registered 24 hours before surgery. Thirty days later, a second TTE was performed. According to the results, the patients were categorized as the "successful" group (with 1+ or less mitral regurgitation) and the "unsuccessful" group (with 2+ or higher MR). Preoperative TTE indices were compared among the two groups using suitable statistical tests.

RESULTS

Of the total of 126 cases, 68 had successful and 58 had unsuccessful MVA. Statistically significant differences were found between the two groups for left ventricular ejection fraction (LVEF) (P = 0.007), left ventricular end systolic volume (LVESV) (P = 0.044), and basal-interpapillary muscle distance (IPMD) diastolic-to-systolic ratio (DSR) (P = 0.008). Receiver Operating Characteristic analysis demonstrated 37.5%, 3.85 cm(3) , and 1.25, as the best cutoff points for LVEF (P = 0.03, sensitivity: 81%, specificity: 69%), LVESV (P = 0.023, sensitivity: 83%, specificity: 57%), and basal-IPMD DSR (P = 0.001, sensitivity: 100%, specificity: 95%), respectively.

CONCLUSION

Among all TTE indices, LVEF, LVESV, and basal-IPMD DSR were helpful to differentiate between the successful and unsuccessful MVA results. We believe the basal-IPMD DSR as a novel index could be targeted in the future studies.

3D echocardiography in congenital heart disease: a valuable tool for the surgeon

Real-time 3D echocardiography has been used increasingly in the assessment of patients with congenital heart disease. A number of studies have confirmed that this modality can be used as a complementary method to delineate morphology and spatial relationships of simple and more complex congenital heart lesions during surgical planning. Communication between the echocardiographer and surgeon can be simplified as simulation of surgical views can be achieved, thus minimizing the potential for error related to mental reconstruction. This review summarizes the available evidence for the role of real-time 3D echocardiography in congenital heart disease as an imaging modality to assist surgeons.

Procedural guidance using advance imaging techniques for percutaneous edge-to-edge mitral valve repair

The complexity of structural heart disease interventions such as edge-to edge mitral valve repair requires integration of multiple highly technical imaging modalities. Real time imaging with 3-dimensional (3D) echocardiography is a relatively new technique that first, allows clear volumetric imaging of target structures such as the mitral valve for both pre-procedural diagnosis and planning in patients with degenerative or functional mitral valve regurgitation. Secondly it provides intra-procedural, real-time panoramic volumetric 3D view of structural heart disease targets that facilitates eye-hand coordination while manipulating devices within the heart. X-ray fluoroscopy and RT 3D TEE images are used in combination to display specific targets and movement of catheter based technologies in 3D space. This integration requires at least two different image display monitors and mentally fusing the individual datasets by the operator. Combined display technology such as this, allow rotation and orientation of both dataset perspectives necessary to define targets and guidance of structural disease device procedures. The inherently easy concept of direct visual feedback and eye-hand coordination allows safe and efficient completion of MitraClip procedures. This technology is now merged into a single structural heart disease guidance mode called EchoNavigator(TM) (Philips Medical Imaging Andover, MA). These advanced imaging techniques have revolutionized the field of structural heart disease interventions and this experience is exemplified by a cooperative imaging approach used for guidance of edge-to-edge mitral valve repair procedures.

Identification of prolapsing mitral valve scallops by a three-dimensional multiplanar reconstruction method

BACKGROUND

The objectives of this study were twofold: to assess the diagnostic utility of three-dimensional (3D) multiplanar reconstruction (MPR) in identifying prolapsing mitral valve (MV) scallops, and (2) to compare two-dimensional (2D) transthoracic echocardiography (TTE) and 3DMPR to (2D) transesophageal echocardiography (TEE) approaches among patients with mitral valve prolapse (MVP).

METHODS

Fifty-five patients with MVP who underwent MV repair or replacement were retrospectively analyzed using 3 types of echocardiographic studies (2DTEE, 2DTTE, 3DMPR). The operative (OR) findings were considered the gold standard.

RESULTS

When 3DMPR was combined with 2DTTE, the agreement with the OR findings was moderately strong for the A2 scallop (P < 0.001) and strong for the A3 scallop (P = 0.001), entire anterior leaflet (P < 0.001), P2 scallop (P < 0.001) and the entire posterior leaflet (P < 0.001). In comparison to the OR findings, 2DTEE demonstrated moderately strong agreement for the A2 scallop (P = 0.010) and the entire anterior leaflet (P < 0.001), and strong agreement for the P2 scallop (P < 0.001) and entire posterior leaflet (P < 0.001).

CONCLUSIONS

Three-dimensional MPR should be added to the armamentarium of complementary echo techniques in the evaluation of MVP. There is increased benefit in combining 3DMPR with 2DTTE findings as part of the preoperative evaluation of patients with MVP.

The use of echocardiography in congenital heart surgery and intervention

Echocardiography has revolutionized the management of pediatric and adult heart disease, especially in the diagnosis of congenital heart defects. Although the early methods of echocardiography (M-mode and Doppler imaging) were limited in their ability to define the defect in question, the advent of 2D, and now 3D, imaging have clearly equaled or surpassed traditional methods of diagnosis (e.g., noninvasively obtained plain chest radiographs and electrocardiograms) and invasive tests (e.g., cardiac catheterization and angiography). Confidence in the images obtained using echocardiography has continued to increase, with many patients referred for corrective or palliative surgery on the basis of echocardiographic imaging alone. Echocardiography has eliminated the need, decreased the frequency, or improved the timing or performance of invasive studies in other patients. Specifically, it is used to definitively diagnose a cardiac defect and any associated lesions. It will also provide quantitative information for the assessment of the hemodynamic severity of the lesion. This review outlines the manner in which echocardiography is used to plan and guide congenital heart surgery or intervention, along with some of the advantages and disadvantages (pitfalls) of which to be aware. The use of echocardiography within the cardiac catheterization or surgical theater, as well as in the intensive care unit, is discussed, as is the use of echocardiography as a means of monitoring recovery and follow-up following cardiac surgery. Finally, the authors discuss who is best qualified or suited to perform these tests.

Imaging in mitral stenosis: assessment before, during and after percutaneous balloon mitral valvuloplasty

Detailed assessment of mitral valve morphology is required to select patients for successful percutaneous balloon mitral valvuloplasty (PBMV). The mitral valve is routinely imaged using transthoracic and transesophageal echocardiography, which have more recently been supplemented with magnetic resonance imaging, 3D echocardiography and intracardiac echocardiography. The scope of PBMV is expanding and it is increasingly used for patients previously considered to have unfavorable mitral morphology. Here we review the evidence to support the examination of each component of the mitral valve and its surrounding structures and the advantages of each imaging modality. Appropriate echocardiographic views are recommended and periprocedural and postprocedural imaging techniques are discussed.

Usefulness of the multiplanar reformatting mode of three-dimensional echocardiography in evaluating valvular and structural heart disease: An experience from Saudi Arabia

OBJECTIVE

The aim of this study is to compare the feasibility and capacity of multiplanar reformatting (MPR) mode of three-dimensional echocardiography (3DE-MPR technique) with two-dimensional echocardiography (2DE) for visualizing morphological details during evaluation of congenital heart disease (CHD). The study also seeks to validate the accuracy of 3DE MPR in determining cardiac valvular lesions and the application of the 3DE-MPR technique in daily clinical practice.

METHODS

A cross-sectional study was carried out at Madinah Cardiac Centre, Saudi Arabia from May to December 2012. Various forms of CHD were diagnosed in 43 patients by conventional 2DE, and the patients were then examined with the 3DE-MPR technique using dedicated software and a standard protocol.

RESULTS

Of the 43 patients, 23 (53.5%) were males and 20 (46.5%) females. Their age varied from 30 days to 146 months (mean age, 70.2 months and SD = 42.5 months) and their weight from 4 to 42 kg (mean weight, 20.2 kg and SD = 9.7 kg). The 2DE showed left heart lesions in nine patients (20.9%), right heart lesions in 23 (53.5%), atrial septal defects in five (11.6%) and complex CHD in six patients (14%). The 3DE MPR technique application and analysis was possible in all patients. The study demonstrated the fields where 3DE MPR was of additive value to conventional 2DE for the vena contracta area in valvular regurgitation severity and the planimetry for the valvular stenosis precise estimation, enface views of atrial septal defects with direct visualisation of shape and size of the defect, and segmental analysis of complex CHD using one window. The clinician and surgeon were then able to determine the mechanism and severity of the lesions and thus decide on appropriate treatment and management.

CONCLUSION

The study demonstrated the usefulness of 3DE-MPR as a complement to conventional 2DE. The technique is a significant technological breakthrough that allows instant visualization of morphological details and precise determination of cardiac valvular lesions, which were less clearly delineated by 2DE alone.

Three-dimensional echocardiography in the electrophysiology laboratory

The use of three-dimensional echocardiography (3DE) during electrophysiology (EP) procedures is the end product of years of growth in two diverse cardiology subspecialties; namely, advanced cardiac imaging and the EP. During the past decade, progress in both fields has resulted in many important advances that have culminated in their union for a new area of growth and development. Imaging advances have provided the cardiovascular specialist with enhanced cardiac volume and function data, and more recently, 3DE capabilities with improved spatial and temporal resolution providing unprecedented spatial relationships. This latter development is valued by EP specialists in need of hitherto never required anatomic knowledge as they press forward with extraordinary expansion in their capabilities. It makes sense that by combining these two rapidly growing subspecialties, future capabilities in patient care may be achieved that would otherwise not be possible. This paper discusses the value of 3DE during EP procedures and offers the readers insight into this novel multispecialty hybrid arena. Using this model as a template, it is likely that the readers may identify other areas within their practices where periprocedural advanced imaging may afford significant dividends in patient outcomes.

The applications of non-ECG-gated MSCT angiography in children with congenital heart disease

BACKGROUND

To minimize radiation exposure during a multi-slice computed tomography (MSCT) examination in children with congenital heart disease (CHD), we assessed diagnostic value and the various applications of MSCT without electrocardiography (ECG)-gated image acquisition.

METHODS

Three-dimensional (3D) images were reconstructed to include volume rendering and differential color-coding of the arteries and veins. The vessel diameter in MSCT was measured with CT attenuation profiles and compared with that of angiography. Ventricular volumetry was initially validated by phantom experiment and followed by comparison with that of cine-angiography (n=15). Simulation for surgical operation was performed to evaluate the possibility of an intraventricular conduit in patients diagnosed with a double outlet right ventricle.

RESULTS

Differential color-coding was able to provide accurate and understandable anatomical structure in CHD. The diameter of the descending aorta measured in MSCT correlated well with the values obtained by angiography (r(2)=0.86). According to the results of the phantom experiment, ventricular volume was studied in patients whose heart rate was faster than 120 beat/min. The left and the right ventricular volume in MSCT correlated well with values obtained by cine-angiography (r(2)=0.98 for RV, r(2)=0.94 for LV). Simulative operation of intraventricular rerouting provided appropriate indication for biventricular repair in patients diagnosed with a double outlet right ventricle.

CONCLUSIONS

Non-ECG-gated MSCT angiography is applicable for precise anatomical diagnosis, ventricular volumetric study, and simulation surgery in children with CHD.

The basics of echocardiography

Cardiac echocardiography is becoming an essential diagnostic tool for a variety of cardiac pathology. Acquiring the necessary knowledge will help non cardiac and the cardiac specialist to understand the echocardiography images and reports and in return will improve the care of the patients. The aim of these of publication is to address the basic knowledge of cardiac echocardiography and the recent advances of its applications.

Haemodynamics and blood flow measured using ultrasound imaging

Visualization of, and measurements related to, haemodynamic phenomena in arteries may be made using ultrasound systems. Most ultrasound technology relies on simple measurements of blood velocity taken from a single site, such as the peak systolic velocity for assessment of the degree of lumen reduction caused by an arterial stenosis. Real-time two-dimensional (2D) flow field visualization is possible using several methods, such as colour flow, blood flow imaging, and echo particle image velocimetry; these have applications in the examination of the flow field in diseased arteries and in heart chambers. Three-dimensional (3D) and four-dimensional ultrasound systems have been described. These have been used to provide 2D velocity profile data for the estimation of volumetric flow. However, they are limited for haemodynamic evaluation in that they provide only one component of the velocity. The provision of all seven components (three space, three velocity, and one time) is possible using image-guided modelling, in which 3D ultrasound is combined with computational fluid dynamics. This method also allows estimation of turbulence data and of relevant quantities such as the wall shear stress.

Computational cardiac atlases: from patient to population and back

Integrative models of cardiac physiology are important for understanding disease and planning intervention. Multimodal cardiovascular imaging plays an important role in defining the computational domain, the boundary/initial conditions, and tissue function and properties. Computational models can then be personalized through information derived from in vivo and, when possible, non-invasive images. Efforts are now established to provide Web-accessible structural and functional atlases of the normal and pathological heart for clinical, research and educational purposes. Efficient and robust statistical representations of cardiac morphology and morphodynamics can thereby be obtained, enabling quantitative analysis of images based on such representations. Statistical models of shape and appearance can be built automatically from large populations of image datasets by minimizing manual intervention and data collection. These methods facilitate statistical analysis of regional heart shape and wall motion characteristics across population groups, via the application of parametric mathematical modelling tools. These parametric modelling tools and associated ontological schema also facilitate data fusion between different imaging protocols and modalities as well as other data sources. Statistical priors can also be used to support cardiac image analysis with applications to advanced quantification and subject-specific simulations of computational physiology.

Head to head comparison of 2D vs real time 3D dipyridamole stress echocardiography

Real-time three-dimensional (RT-3D) echocardiography has entered the clinical practice but true incremental value over standard two-dimensional echocardiography (2D) remains uncertain when applied to stress echo. The aim of the present study is to establish the additional value of RT-3D stress echo over standard 2D stress echocardiography. We evaluated 23 consecutive patients (age = 65 ± 10 years, 16 men) referred for dipyridamole stress echocardiography with Sonos 7500 (Philips Medical Systems, Palo, Alto, CA) equipped with a phased – array 1.6–2.5 MHz probe with second harmonic capability for 2D imaging and a 2–4 MHz matrix-phased array transducer producing 60 × 70 volumetric pyramidal data containing the entire left ventricle for RT-3D imaging. In all patients, images were digitally stored in 2D and 3D for baseline and peak stress with a delay between acquisitions of less than 60 seconds. Wall motion analysis was interpreted on-line for 2D and off-line for RT-3D by joint reading of two expert stress ecocardiographist. Segmental image quality was scored from 1 = excellent to 5 = uninterpretable. Interpretable images were obtained in all patients. Acquisition time for 2D images was 67 ± 21 sec vs 40 ± 22 sec for RT-3D (p = 0.5). Wall motion analysis time was 2.8 ± 0.5 min for 2D and 13 ± 7 min for 3D (p = 0.0001). Segmental image quality score was 1.4 ± 0.5 for 2D and 2.6 ± 0.7 for 3D (p = 0.0001). Positive test results was found in 5/23 patients. 2D and RT-3D were in agreement in 3 out of these 5 positive exams. Overall stress result (positive vs negative) concordance was 91% (Kappa = 0.80) between 2D and RT-3D. During dipyridamole stress echocardiography RT-3D imaging is highly feasible and shows a high concordance rate with standard 2D stress echo. 2D images take longer time to acquire and RT-3D is more time-consuming to analyze. At present, there is no clear clinical advantage justifying routine RT-3D stress echocardiography use.

3D and 4D echo--applications in EP laboratory procedures

INTRODUCTION

3D echocardiography allows imaging and analysis of cardiovascular structures as they move in time and space, thus creating possibility for creation of 4D datasets (3D + time). Intracardiac echocardiography (ICE) further broadens the spectrum of echocardiographic techniques by allowing detailed imaging of intracardiac anatomy with 3D reconstructions. The paper reviews the current status of development of 3D and 4D echocardiography in electrophysiology. In ablation area, 3D echocardiography can enhance the performance of catheter ablation for complex arrhythmias such as atrial fibrillation. Currently, several strategies to obtain 3D reconstructions from ICE are available. One involves combination with electroanatomical mapping system; others create reconstruction from standard phased-array or single-element ICE catheter using special rotational or pull-back devices. Secondly, 3D echocardiography may be used for precise assessment of cardiac dyssynchrony before cardiac resynchronization therapy. Its reliable detection is expected to minimize number of non-responders to this treatment and optimize left ventricular lead positioning to get maximum hemodynamic benefit.

CONCLUSION

The main potential benefit of 3D and 4D echocardiography in electrophysiology lie in real-time guidance of complex ablation procedures and precise assessment of cardiac dyssynchrony.

Atrioventricular Valve Morphology and Dynamics in Congenital Heart Disease as Imaged with Real-time 3-Dimensional Matrix-array Echocardiography: Comparison with 2-Dimensional Imaging and Surgical Findings

OBJECTIVE

We sought to describe our initial experience with real-time 3-dimensional echocardiographic (RT3DE) imaging of atrioventricular valve (AVV) anomalies in pediatric patients to resolve a specific morphologic or dynamic detail, which, although suggested, could not be well resolved during the conventional 2-dimensional (2D)/Doppler examination.

METHODS

In all, 41 patients (age range 1 day-24 years) with different AVV anomalies underwent RT3DE as part of their comprehensive echocardiographic assessment. Matrix-array transducers with a frequency range of 1 to 4 MHz were used. The first 27 patients were not consecutive, and the RT3DE findings interpreted by one examiner were compared directly with the 2D findings interpreted by a different examiner. In the following consecutive 14 patients, the RT3DE findings were compared with the surgical findings and with the interpretations of their corresponding 2D examinations by 3 examiners who were blinded to the findings of RT3DE for more objective comparison.

RESULTS

RT3DE imaging was successful in resolving the raised question in all patients. The morphology of the valve leaflets and their chordal attachments, the mechanism and origin of regurgitation, and the geometry of the regurgitant volume were well delineated by RT3DE imaging. In the second group of patients, there was agreement between the morphologic details delineated by RT3DE (a total of 21 specific questions raised) and the surgical findings in those patients who had immediate surgery. On the other hand, RT3DE showed prominent AVV chordal attachments in the left ventricular outflow tract in one patient, which was not considered surgically relevant during the repair.

CONCLUSIONS

Although RT3DE is still in its initial phase, has some technical limitations, and does not change the basic diagnosis made by 2D imaging, echocardiographic examination using the matrix-array transducer is a useful adjunct in delineating specific morphologic and dynamic details of the AVV in congenital heart disease.

Volume stitching in three-dimensional echocardiography: distortion analysis and extension to real time

Three-dimensional (3D) echocardiography is challenging due to limitation of the data acquisition rate caused by the speed of sound. ECG-gated stitching of data from several cardiac cycles is a possible technique to achieve higher resolution. The aim of this work is two-fold: it is, firstly, to provide a method for real-time presentation of stitched echocardiographic images acquired over several cardiac cycles and, secondly, to demonstrate that the geometrical distortion of the images is decreased when stitching is applied to 3D ultrasonic data of the left ventricle (LV). We present a volume stitching algorithm that merges data from N consecutive heart cycles into an assembled data volume. The assembly is performed in real time, making immediate volume rendering of the full volume possible. In-vivo images acquired with this technique are presented. Through simulations with a kinematic model of the LV wall, geometrical distortion and volume estimation errors due to long image capture time was quantified for 3D recordings of the LV. Curves showing the variation throughout the cardiac cycle of the maximal geometrical distortion in the LV walls are presented, as well as curves showing the volume estimates compared with the true LV volume of the model. We conclude that real-time display of stitched 3D ultrasound data is feasible and that it is an adequate technique for increasing the volume acquisition rate at a given spatial resolution. Furthermore, the geometrical distortion decreases substantially for data with higher volume rate and, for a full scan of the LV, stitching over at least four cycles is recommended.

[Three-dimensional echocardiography in cardiac surgery. Current status and perspectives]

Three-dimensional (3D) echocardiography is a new imaging technique that can provide useful information about cardiovascular morphology, pathology, and function. Recent refinements in instrumentation, data acquisition, post-processing, and computation speed allow 3D echocardiography to play an important role in cardiac imaging. These modalities provide comprehensive information on ventricular and valve morphology and function. Combined with 3D color Doppler sonography, further assessment of valvular function and determination of flow in the left ventricular outflow tract and cross-septal defects are now possible. Three-dimensional color flow imaging also makes echocardiography accurate for assessing the severity of mitral regurgitation. The purpose of this review is to describe technical developments in 3D echocardiography and its clinical application in cardiac surgery. Moreover, based on clinical studies at our centre, we describe the morphology of the mitral valve, its flow pattern, and function of the mitral annulus.

Left ventricular volume and function in cynomolgus monkeys using real-time three-dimensional echocardiography

BACKGROUND

The purpose of this study was to investigate the feasibility of evaluating cardiac function by real time three-dimensional (RT3D) echocardiography in isoflurane-anesthetized male cynomolgus monkeys. Additionally differences between inhibitory effects of beta-blockers and a Ca channel blocker on left ventricular (LV) function were examined.

METHODS AND RESULTS

End-diastolic volume (EDV), end-systolic volume (ESV) and ejection fraction (EF) in the control (without any drug effect) were not significantly changed by repetitive measurement at a 30-day interval. Propranolol and metoprolol (0.1 and 0.3 mg/kg/10 minutes, i.v.) caused a dose-dependent increase in ESV, but little effect on EDV, resulting in a decrease in EF. Verapamil (0.1 and 0.3 mg/kg/10 minutes, i.v.) increased both EDV and ESV, but decreased EF was noted at 0.3 mg/kg.

CONCLUSIONS

These results demonstrate the feasibility of RT3D echocardiography in providing reproducible estimations of LV volume and EF in monkeys when evaluating drugs that may affect cardiac function.

[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.

Feasibility and clinical impact of live three-dimensional echocardiography in the management of congenital heart disease

BACKGROUND

Precise assessment of congenital heart lesions requires inferential evaluation from multiple two-dimensional echocardiographic images (2DE). The aim of our study was to assess the usefulness of transthoracic live three-dimensional echocardiography (3DE) in the evaluation of congenital heart disease.

METHODS

Eighty-two patients (from 4 months to 31 years, mean age 12 +/- 7.5, 38 males and 44 females), known to have congenital heart lesions, prospectively underwent both 2DE and 3DE. Conventional data acquisition by 2DE and "full volume" 3DE acquisition (apical four chambers, parasternal long and short axes, subcostal windows) were carried out by two independent and blinded operators. Data derived from 3DE were compared to 2DE, and 3DE results were graded into three categories: (A) new findings not seen on 2D echo studies, but not critical to therapeutic decision making; (B) additional anatomic information useful in therapeutic decision making; and (C) information equivalent to 2D echo studies.

RESULTS

Two out of 82 patients (2%) were excluded because of suboptimal 3DE images. In comparison with 2DE studies, 3DE was graded A in 23 patients (29%), B in 28 patients (35%), and C in 29 patients (36%). In the patients with group B results, atrial and ventricular septal defects, endocardial cushion defects, and l-transposition of great vessels were the most represented pathologies in which 3DE aided medical or surgical therapeutic options. While the new findings in group A did not influence therapy, they defined the whole spectrum of abnormalities in those patients. In patients who fell under group C results, 3DE provided a direct realistic display of the pathology detected by 2DE.

CONCLUSIONS

Our study demonstrates that live 3DE, easily performed at the bedside, provides incremental information on patients with a variety of congenital heart lesions. In the clinical scenario, it clarifies the pathology in all its dimensions, particularly in complex lesions with the incremental information having impact on therapeutic decision making.

The Emerging Role of Three-Dimensional Echocardiography in Mitral Valve Repair

Although three-dimensional (3D) echocardiography is still in its evolution, cutting edge advances that allow quantifiable images of cardiac structures to be created in real-time will begin to increase its use drastically. One of the most promising uses of the technology is in the planning, optimization, and postoperative surveillance of mitral valve repair techniques and devices. This article reviews the development of 3D echocardiography and presents illustrations of how it may be applied to improving mitral valve repair techniques. It is conceivable in the near future that mitral repair procedures will be designed and customized for each patient preoperatively using data obtained from 3D echo images and computerized virtual surgery techniques. Such tools will allow the surgeon to design operations that thoroughly analyze valve geometry and stress distribution before ever entering the operating room.

Real-time 3-dimensional echocardiographic imaging of congenital heart disease using matrix-array technology: freehand real-time scanning adds instant morphologic details not well delineated by conventional 2-dimensional imaging

OBJECTIVE

We sought to investigate whether real-time (RT) 3-dimensional echocardiography (RT3D) using matrix-array technology could resolve a specific morphologic detail that could not be well resolved during conventional 2-dimensional (2D)/Doppler echocardiographic imaging of congenital heart disease.

BACKGROUND

Although 2D echocardiography is currently the primary imaging modality of congenital heart disease, there are still some anatomic details that cannot be well delineated by that modality.

METHODS

In all, 70 patients underwent RT3D examination using matrix-array transducer. Applying the standard sweeping technique as for 2D imaging, freehand RT imaging was used for immediate feedback. The 2D examinations of the last 23 consecutive patients were used to validate the additional value of RT3D by 3 examiners blinded to the findings of RT3D.

RESULTS

The adequacy of 2D imaging to resolve the morphologic detail in question ranged from 30% to 70%, whereas RT3D imaging was considered successful in delineating the morphologic detail in 80% to 100% of patients instantly. The image resolution was superior or equivalent to that obtained by 2D imaging. Heart valves, septal defects, and volumetric valvular and vascular color flow morphologies were well delineated by RT3D.

CONCLUSION

Matrix-array RT3D is a significant breakthrough technology that allowed instant visualization of cardiac anatomic details that could not be well delineated by 2D imaging. Further improvements of some technical limitations should make RT3D matrix-array cardiac imaging a significant modality in the field of echocardiographic imaging of congenital cardiac anomalies.

Live three-dimensional paediatric intraoperative epicardial echocardiography as a guide to surgical repair of atrioventricular valves

Real-time three dimensional echocardiography is increasingly used for imaging patients with congenital cardiac malformations. One of the limitations of a transthoracic approach is that intervening structures can impact on the quality of the images obtained. We hypothesised that, during surgery, epicardial three-dimensional echocardiography would provide images of high quality. We report our findings in eight children or young adults, with weights ranging from 2.8 to 70 kilograms, in whom we used this approach. In all cases, we obtained images of good quality, which could be analysed rapidly in the operating room. Of the eight cases, seven had echocardiographic findings which matched exactly the surgical findings. The remaining child had been diagnosed echocardiographically with a cleft in the aortic leaflet of the mitral valve, but was found at surgery to have a double orifice in the valve.

Feasibility and Accuracy of Real-time 3-Dimensional Echocardiographic Assessment of Ventricular Septal Defects

The aim of this study was to evaluate feasibility, accuracy, and clinical applicability of real-time (RT) transthoracic 3-dimensional (3D) echocardiography (3DE) in the determination of the position, size, and shape of a ventricular septal defect (VSD). In all, 34 patients (age: 2 months-46 years), who were scheduled for surgical closure of a VSD, were enrolled in the study. VSD localization, shape, and dimensions were assessed and compared with measurements performed by the surgeon. Acquisition of RT-3DE datasets was feasible in 30 of 34 (88%) patients. Duration of 3D data acquisition was 6 +/- 2 minutes. Reconstruction time was 23 +/- 16 minutes. Localization and number of VSD were determined correctly by RT-3DE in all patients. There was a good correlation for VSD measurements between RT-3DE and operation (r = 0.95). RT-3DE allows accurate determination of VSD size, shape, and location. The short acquisition time and acceptable reconstruction time make this technique clinically applicable.

Three-dimensional echocardiography–guided beating-heart surgery without cardiopulmonary bypass: A feasibility study

BACKGROUND

There is no current acceptable approach for intracardiac beating-heart interventions. We have adapted real-time 3-dimensional echocardiography with specialized instrumentation to facilitate beating-heart repair of atrial septal defects and mitral valve plasty to investigate the feasibility of real-time 3-dimensional echocardiography-guided cardiac surgery.

METHODS

In experiment I a modified real-time 3-dimensional echocardiography system with x4 matrix transducer was compared with 2-dimensional echocardiography in the performance of common surgical tasks. Completion times, deviation from an ideal trajectory, and an echogenic target were measured. In experiment II porcine atrial septal defects were closed with an original semiautomatic suturing device (n = 4) and with a 5-mm endoscopic stapler and a pericardial or polytetrafluoroethylene patch (n = 4). In experiment III a pulsatile porcine mitral valve model was developed, and suture placement through the anterior and posterior mitral leaflets was performed (n = 8). During all experiments, the operator was blinded to the target and operated on only with ultrasonic guidance.

RESULTS

In experiment I, compared with 2-dimensional echocardiographic guidance, completion times improved by 21% ( P <.01) with high-trajectory accuracy, and suture deviation was significantly smaller (2-dimensional echocardiography, 5.4 +/- 2.7 mm; 3-dimensional echocardiography, 1.7 +/- 0.7 mm; P <.05) in real-time 3-dimensional echocardiography-guided tasks. In experiments II and III in both atrial septal defect closure and mitral valve plasty, real-time 3-dimensional echocardiography provided satisfactory images and sufficient anatomic detail for suturing and patch deployment. All surgical tasks were successfully performed with accuracy.

CONCLUSIONS

Real-time 3-dimensional echocardiography provides adequate imaging and anatomic detail to act as a sole guide for surgical task performance. These initial experiments demonstrate the feasibility of beating-heart direct or patch closure of atrial septal defects and mitral valve plasty without cardiopulmonary bypass.

Three-dimensional echocardiography–guided atrial septectomy: An experimental study

OBJECTIVES

The surgical feasibility of beating-heart atrial septectomy under the guidance of two different types of real-time 3-dimensional echocardiography systems was examined.

METHODS

A modified real-time 3-dimensional echocardiography system with a x4 matrix transducer (Sonos 7500; Philips Medical Systems, Andover, Mass) or a mechanical 1-dimensional array transducer (SSD-5500; Aloka Co, Ltd, Tokyo, Japan) was used. Small porcine atrial septal defects (n = 8) were enlarged with a Kerrison bone punch in the tank model. In the animal studies, small atrial septal defects (n = 8) were enlarged with the same device through a transatrial port. In both experiments, the area of the atrial septal defect measured by real-time 3-dimensional echocardiography was compared with the area measured directly.

RESULTS

Real-time 3-dimensional echocardiography provided satisfactory images and sufficient anatomic detail for the atrial septectomy in both experimental settings. All the atrial septal defects were successfully enlarged; an increase of as much as 293% of the preoperative atrial septal defect area was achieved in the tank experiment, and an increase of as great as 449% of the preoperative area was achieved in the animal experiment. The size of the atrial shunt was increased significantly after the atrial septectomy relative to that before the surgery (P <.0001). The percentage enlargement of the atrial septal defect measured by real-time 3-dimensional echocardiography was strongly correlated with that measured directly (both r(2) = 0.997, P <.0001) Bland-Altman analysis showed close agreement between the results obtained by the two measurement methods in both models.

CONCLUSIONS

Real-time 3-dimensional echocardiography provides satisfactory images and sufficient anatomic detail for atrial septectomy. This experiment demonstrates the surgical feasibility of a beating-heart intracardiac procedure such as atrial septectomy under real-time 3-dimensional echocardiographic guidance.

Left atrial and left ventricular function in healthy children and young adults assessed by three dimensional echocardiography

OBJECTIVE

To establish normal values of left atrial and left ventricular volumes and function in children and young adults using three dimensional echocardiography (3DE).

METHODS

169 healthy subjects aged 2 to 27 years were studied by digitised 3DE. 3DE was achieved using rotational acquisition of planes at 18 degrees intervals from the parasternal view for the left atrium and from the transthoracic apical view for the left ventricle with ECG gating and without respiratory gating. Left atrial and left ventricular volumes could be calculated throughout the heart cycle, and the respective time-volume curves were reconstructed in each subject.

RESULTS

For the analysis the subjects were divided into five groups according to body surface area: 0.5-0.75 m2, 0.75-1.0 m2, 1.0-1.25 m2, 1.25-1.5 m2, and over 1.5 m2. Mean (SD) left atrial maximum volume/body surface area was 19.6 (3.5), 21.7 (3.7), 22.0 (4.7), 24.5 (4.8), and 27.4 (6.4) ml/m2; left ventricular maximum volume/body surface area was 50.1 (8.8), 54.9 (10.1), 56.4 (9.9), 58.7 (11.0), and 64.4 (10.3) ml/m2. Left atrial active emptying increased from 19% to 35% with age (r = 0.34, p < 0.001) and with decreasing heart rate (r = -0.28, p < 0.001).

CONCLUSIONS

Transthoracic 3DE is well suited for studying the phasic changes in left atrial and left ventricular volumes in young children as well as in adults. The data obtained from 169 healthy subjects will serve as a reference for further studies in patients with various cardiac abnormalities.

Quantitative assessment of pericardial effusion volume by two-dimensional echocardiography

The clinical applicability of a method for quantifying pericardial effusion (PE) was studied. The pericardial and cardiac volumes were determined from border tracings of 2-dimensional echocardiograms fitted with 3-dimensional disk models. The PE volume was the difference between pericardial and cardiac volumes. A phantom study included 54 cases with different volumes and viewing geometry showed a correlation coefficient r = 0.98 and an accuracy of +/- 6%. A clinical study included 20 cases showing that the estimated PE volume correlated well with that drained surgically (between 100 mL and 1200 mL): y = 0.81 x + 120 mL; r = 0.91, P <.0001. The percent error, determined by the standard error of the estimate (114 mL) over mean (548 mL), was 20%. Intraobserver variability was 4% and interobserver variability 6%. The 3-dimensional disk method provides a quick and convenient way to quantify PE from 2-dimensional echocardiograms with acceptable accuracy and reproducibility.