Three-dimensional color Doppler echocardiography for assessing shunt volume in atrial septal defects

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.

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 Color Doppler Echocardiography Overcomes the Inaccuracies of Spectral Doppler for Stroke Volume Calculation

Real-time 3-dimensional echocardiography is increasingly used in clinical cardiology. Studies have been shown that this technique can be accurately used to assess both cardiac mass and chamber volumes. We review the work showing that real-time 3-dimensional Doppler echocardiography can be used to accurately calculate intracardiac flow volumes that can potentially be used to assess cardiac function, intracardiac shunt, and valve regurgitation.

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.

Feasibility and Utility of Three-Dimensional Color Flow Echocardiography of the Aortic Arch: The “Echocardiographic Angiogram”

Two-dimensional transthoracic echocardiography (2DE) is the most commonly used diagnostic modality to evaluate congenital and acquired abnormalities of the aortic arch. However, 2DE is frequently limited in this ability due to the three-dimensional character of the arch and its interrelationships with other vascular structures. Recently, three-dimensional echocardiography (3DE) with 3D color flow Doppler became commercially available. We examined the feasibility and utility of 3DE with 3D color Doppler in the evaluation of patients with congenital (native and postoperative) abnormalities of the aortic arch. We found that 3DE color flow provides important diagnostic information in patients with aortic arch anomalies, in a manner that is quick and user-friendly. In addition, 17 of the 26 patients had their 3DE findings confirmed by additional modalities, providing reasonably significant validation for our findings with 3DE.

Characterization of Atrial Septal Defect Assessed by Real-time 3-Dimensional Echocardiography

OBJECTIVE

The aim of this study was to describe a quantitative evaluation by real-time 3-dimensional (3D) echocardiography (RT-3DE) of atrial septal defect (ASD) and atrial septum that is important for patient selection for transcatheter closure, and to assess the reliability of RT-3DE findings compared with operation.

METHODS

Forty-five patients, who were scheduled for surgical or transcatheter closure of an ASD, were included in the study.

RESULTS

In 43 patients (96%), 3D reconstructions allowed optimal imaging of the ASD. The correlations between the ASD maximal diameter by RT-3DE and operation or balloon sizing were excellent (r > 0.95). All surrounding rims of the atrial septum could be assessed on 3D reconstruction; except for the aortic rim, a cross-sectional reconstruction was created mimicking the transesophageal echocardiographic cross section (r > 0.92).

CONCLUSION

RT-3DE allows accurate determination of ASD location, ASD size, and surrounding tissue of the atrial septum, and might replace transesophageal echocardiography for patient selection for surgical or transcatheter closure.

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.

Update on pediatric echocardiography

PURPOSE OF REVIEW

The past year was dominated by developments in echocardiographic assessment of myocardial function in children, and this paper reviews some of these major advancements in pediatric echocardiography as a guide to those interested in imaging of the pediatric heart and vascular system.

RECENT FINDINGS

Characterization of myocardial function using Doppler tissue imaging, both in the normal child and in the child with congenital or acquired heart disease, was a primary focus of pediatric echocardiographic investigation. Other new technologies, including integrated backscatter analysis and three-dimensional echocardiography, appear to hold significant promise as tools to improve myocardial assessment echocardiographically. Three-dimensional echocardiography also is developing into a powerful technique in fetal echocardiography, allowing rapid data acquisition and extensive image postprocessing with opportunities for both anatomic and functional assessment. Childhood fitness and diseases have a significant impact on the heart and vascular bed, and descriptions of echocardiographic findings in obese children, children engaged in athletic activities, children with renal disease, children who have undergone cardiac transplantation, and those with aortic valve disease were better characterized by investigations published over the past year.

SUMMARY

Pediatric echocardiography has clearly expanded from a diagnostic tool used to describe anatomic abnormalities associated with congenital heart disease to a noninvasive myocardial monitoring tool that allows serial assessment of the pathologic effects of both cardiac and noncardiac disease.

Real-time 3-Dimensional Doppler Echocardiography for the Assessment of Stroke Volume: An In Vivo Human Study Compared with Standard 2-Dimensional Echocardiography

BACKGROUND

Invasive monitors and noninvasive 2-dimensional echocardiography are the standard clinical methods for stroke volume (SV) and cardiac output computation. We studied the use of real-time color Doppler 3-dimensional (3D) echocardiography (3DE) for the assessment of SV in human beings.

METHODS

In all, 55 pediatric and adult patients with good transthoracic windows and a normal aortic valve were studied. Real-time 3DE color Doppler volumes incorporating the left ventricular outflow tract and aortic valve were taken. SV was calculated from the color Doppler data in the 3DE DICOM dataset. This was compared with 2-dimensional echocardiography SV calculation from the pulsed wave velocity through the aortic valve along with the left ventricular outflow tract diameter.

RESULTS

Five patients were excluded because of mismatching of the 3D color Doppler segments in the 3D volume. The 3D Doppler volumes from the remaining 50 patients were analyzed. There was good correlation between the patients' averaged 3DE SV calculations and the 2-dimensional echocardiography pulsed wave SV estimation (y = 0.84x + 7.8, r2 = 0.90).

CONCLUSION

Real-time 3D Doppler echocardiography can be used to accurately calculate SV and cardiac output, compared with conventional pulsed Doppler measurement, in pediatric and adult patients from transthoracic imaging.

[Improved analysis of left ventricular function using three-dimensional echocardiography]

Left ventricular geometry and function are important pathophysiologic and prognostic parameters. However, especially in patients with cardiac pathologies left ventricular geometry can be complex. Quantification of left ventricular volumes using conventional two-dimensional echocardiography is only possible when simplifying assumptions of left ventricular geometry are made. In contrast three-dimensional echocardiography allows direct quantification of left ventricular volumes even in complex distortions of left ventricular shape. The availability of real-time three-dimensional echocardiography has brought this technique into clinical practice. Three-dimensional echocardiography is a technique that may be used as a routine echocardiographic method in the near future.