Impact of three-dimensional echocardiography in valvular heart disease

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.

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.

Contrast-enhanced, real-time volumetric ultrasound imaging of tissue perfusion: preliminary results in a rabbit model of testicular torsion

Contrast-enhanced ultrasound (US) imaging is potentially applicable to the clinical investigation of a wide variety of perfusion disorders. Quantitative analysis of perfusion is not widely performed, and is limited by the fact that data are acquired from a single tissue plane, a situation that is unlikely to accurately reflect global perfusion. Real-time perfusion information from a tissue volume in an experimental rabbit model of testicular torsion was obtained with a two-dimensional matrix phased array US transducer. Contrast-enhanced imaging was performed in 20 rabbits during intravenous infusion of the microbubble contrast agent Definity® before and after unilateral testicular torsion and contralateral orchiopexy. The degree of torsion was 0° in 4 (sham surgery), 180° in 4, 360° in 4, 540° in 4, and 720° in 4. An automated technique was developed to analyze the time history of US image intensity in experimental and control testes. Comparison of mean US intensity rate of change and of ratios between mean US intensity rate of change in experimental and control testes demonstrated good correlation with testicular perfusion and mean perfusion ratios obtained with radiolabeled microspheres, an accepted 'gold standard'. This method is of potential utility in the clinical evaluation of testicular and other organ perfusion.

Comparing image processing techniques for improved 3-dimensional ultrasound imaging

OBJECTIVE

The purpose of this study was to compare volumetric image processing techniques for reducing noise and speckle while retaining tissue structures in 3-dimensional (3D) gray scale ultrasound imaging.

METHODS

Eighty subjects underwent a clinically indicated abdominal or obstetric 3D ultrasound examination (20 hepatic, 20 renal, and 40 obstetric cases). Volume data were processed on a pixel ("2-dimensional [2D] processing") or a voxel ("3D processing") basis using commercially available image enhancement software (ContextVision AB, Linköping, Sweden). Randomized, side-by-side comparisons of the image processing techniques were performed for each subject. An independent and blinded reader scored the volumes for image quality on a 3-point scale from 1 (worst) to 3 (best) and compared the results using a nonparametric Wilcoxson signed rank test.

RESULTS

The 40 subjects with abdominal 3D imaging received a mean score (+/- 1 SD) of 1.52 +/- 0.51, 2.45 +/- 0.60, and 2.75 +/- 0.44 for the original, the 2D processed, and the 3D processed volumes, respectively. The differences between the unprocessed and the processed volumes were highly statistically significant (P < .0001), as was the difference between the 2D and 3D processing methods (P = .002). Similar results were obtained for the obstetric data sets (n = 39 due to an acquisition problem) with a mean score of 1.03 +/- 0.16 for the original, 2.33 +/- 0.48 for the 2D processed, and 2.79 +/- 0.47 for the 3D processed volumes (P < .003).

CONCLUSIONS

A new volumetric ultrasound image enhancement technique has been assessed in abdominal and obstetric applications. Compared to unprocessed volumes and volumes processed with 2D image enhancement software, the new 3D processing technique performed best.

Mitral valve regurgitation and 3D echocardiography

The mitral valve is a complex, dynamic and functional apparatus that can be altered by a wide range of disorders leading to stenosis or regurgitation. Surgical management of mitral valve disease may be difficult. Planned intervention may not always be feasible when the surgeon is faced with complex pathology that cannot be assessed fully by conventional 2D echocardiography. Transthoracic and transesophageal 3D echocardiography can provide a more reliable functional and anatomical assessment of the different valve components and evaluation of its geometry, which can aid the surgeon in planning a more suitable surgical intervention and improve outcomes. Although 3D echocardiography is a new technology, it has proven to be an important modality for the accurate assessment of valvular heart disease and in the future, it promises to be an essential part in the routine assessment of cardiovascular patients.

Impact of three-dimensional echocardiography in complex congenital heart defect cases: the surgical view

Other authors have demonstrated the ability of three-dimensional (3D) echocardiography to produce "en face" views of anomalies such as atrioventricular valve disease and atrial and ventricular septal defects. Few data exist about the usefulness of 3D images for more complex congenital heart defects and the surgical impact of this relatively new technology. This study, covering a period of 8 months and including 43 young patients affected by complex congenital heart defects, demonstrated that the routine use of 3D echocardiography is feasible and valuable for some types of cardiac defects. In fact, 3D images have provided more detailed anatomic definition of interrelations between structures in about one-third (15/43) of our cases, yielding new insight into the anatomy analogous to what can be derived from examining a heart specimen. Our surgeons found the 3D images particularly helpful for providing a realistic and almost specimen-like preview of the surgical anatomy that facilitates planning of the surgical program.

Three-Dimensional Echo for the Assessment of Valvular Heart Disease

Three-dimensional echocardiography (3DE) is a valuable tool to be used in addition to and not instead of two-dimensional echocardiography by providing complementary information and improved quantitative accuracy and reproducibility compared with two-dimensional techniques. 3DE has the potential to become the standard echocardiographic examination procedure for the assessment of valvular disease. This article describes applications of 3DE.

[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.

Quantitative Real-time 3-Dimensional Stress Echocardiography: A Preliminary Investigation of Feasibility and Effectiveness

BACKGROUND

Use of rapidly emerging real-time 3-dimensional (3D) echocardiography promises to improve the diagnostic accuracy of stress echocardiography (SE). However, widespread acceptance of 3D-SE, based on real-time 3D echocardiography, is hampered in part by lack of efficient, accurate, and objective analysis tools.

METHODS

We propose novel algorithms for interactive visualization, registration (alignment), and quantitative analysis of prestress and poststress real-time 3D echocardiography to facilitate an objective diagnosis. In a preliminary evaluation, two experts independently performed wall-motion analysis in 15 patients with known/suspected coronary artery disease, using the novel quantitative 3D-SE methods.

RESULTS

Compared with previously reported values for conventional 2-dimensional SE, improved interexpert agreement (kappa = 0.85) was observed for segment-wise classification of normal/abnormal wall motion using the novel 3D-SE methods. Overall, 6 of 6 patients with abnormal myocardial segments were correctly identified by both experts with 3D-SE, compared with 4 of 6 with conventional 2-dimensional SE.

CONCLUSION

Initial results are promising and indicate the feasibility and potential of our proposed quantitative 3D-SE methodologies for improving diagnosis of wall-motion abnormalities.

Epicardial Real-Time Three-Dimensional Echocardiography in Cardiac Surgery: A Preliminary Experience

PURPOSE

Intraoperative two-dimensional transesophageal echocardiography (2DTEE) is a widely accepted method to guide cardiac valve surgery. The aim of our study was to evaluate the feasibility, effectiveness, and incremental value of intraoperative epicardial real-time three-dimensional echocardiography (RT3DE).

DESCRIPTION

Thirty consecutive patients (18 aortic and 12 mitral valve diseases) underwent intraoperative 2DTEE and RT3DE before and after cardiopulmonary bypass. Five observers compared independently 2DTEE to live and full volume images and to the surgical view, to assess the incremental value of RT3DE in depicting the different anatomic structures.

EVALUATION

Epicardial RT3DE was feasible in all patients. Qualitative evaluation determined RT3DE superiority in depicting aortic cusp morphologic lesions; left ventricular outflow tract spatial relationships with mitral apparatus and aortic root; and both anterior and posterior mitral leaflet scallops, particularly posterior commissure.

CONCLUSIONS

In our study, epicardial RT3DE has been demonstrated to improve morphologic definition of anatomic valvular lesions and their relationship with cardiac adjacent structures. It may be a valid substitute when the 2DTEE approach is contraindicated, or it could have a complementary role, coupled with 2DTEE, to give additional information for surgical planning.

Applications of 2-dimensional matrix array for 3- and 4-dimensional examination of the fetus: a pictorial essay

OBJECTIVES

Two-dimensional (2D) matrix array is a new technology for the performance of 3-dimensional and 4-dimensional (4D) ultrasonography. In this study, we report the use of a 2D matrix array transducer for examination of fetal structures including the fetal heart.

METHODS

Thirty-four fetuses without abnormalities and 19 fetuses with congenital anomalies were examined with a 2D matrix array transducer (x3-1, IE-33; Philips Medical Systems, Bothell, WA). Median gestational age was 25 6/7 weeks (range, 13 0/7-40 1/7 weeks).

RESULTS

(1) A 360 degrees rotation and examination of selected structures was possible in the second trimester. (2) Structures were examined by maintaining the transducer in a fixed position and rotating the volume using the system trackball. (3) Dorsal and ventral parts of the hands and feet were visualized in a single volume data set, in real time, without moving the transducer. (4) Real-time en face visualization of atrioventricular valves was possible from the ventricular or atrial chambers. (5) Four-dimensional images of bones were obtained by decreasing gain settings only, with no need for cropping. (6) Four-dimensional reconstruction of vascular structures was possible with color Doppler imaging. Two limitations were identified: (1) lower resolution than mechanical volumetric transducers, and (2) narrow volume display.

CONCLUSIONS

Real-time direct 4D imaging with 360 degrees rotation for examination of fetal anatomic structures is feasible. This technology allows examination of fetal structures from multiple perspectives, in real time, without the need to move the transducer in the maternal abdomen. Further technological developments may overcome the limitations identified in this study.

Cardiac computed tomography compared to transthoracic echocardiography in the management of congenital heart disease

OBJECTIVES

To compare cardiac CT and transthoracic echocardiography (TTE) as diagnostic utilities in congenital heart disease (CHD) and to determine their advantages and limitations.

BACKGROUND

TTE is widely used in the evaluation of CHD. Recent reports suggested an increasing role of CT. However, there are few quantitative data on its diagnostic accuracy.

METHODS

We investigated a total of 162 patients (51.24% male; mean age: 16.06 +/-+/- 17.92) with congenital heart defects, who underwent electron beam CT (EBCT) and TTE between March 2002 and June 2005. We retrospectively analyzed a total of 667 findings, stratified for age and anatomic categories.

RESULTS

EBCT and TTE findings are concordant in patients below 1 year of age (85.43% agreement). EBCT had poor sensitivity and specificity in detecting anomalies of cardiac chambers (0.68, 0.58), but was useful for great arteries (0.91, 0.85). Furthermore, sensitivity and specificity were remarkably different in systemic venous return (0.93, 0.3) and coronary vessels (0.8, 0.33) because of "false positive" findings, which were later found to be most likely real findings not detectable by reference standard. The opposite was true for cardiac valves (0.66, 0.89) and septa (0.76, 0.91).

CONCLUSIONS

EBCT delineates findings related to systemic venous return and coronary vessels well due to simultaneous visualization of complex anatomy. This advantage does not seem to apply in patients below 1 year of age with better acoustic windows. TTE was found more suitable for cardiac valves and septal defects because of the availability of flow imaging.