Three-Dimensional Echocardiography: Rational Mode of Component Images for Left Ventricular Volume Quantitation

[Evaluation of the left ventricle with three-dimensional echocardiography: comparison with cardiac magnetic resonance]

OBJECTIVE

Three-dimensional echocardiography (3DE) is becoming increasingly common in clinical environments. However, the quality of the images depends on the acoustic window, and it can be difficult to identify the endocardial borders. The objective of this study was to evaluate the performance of 3DE in determining the volumes and left ventricular ejection fraction in unselected patients against the gold standard, cardiac magnetic resonance (CMR).

MATERIAL AND METHODS

In 47 unselected patients who underwent CMR, we performed 3DE using a real-time acquisition technique and semiautomatic border detection.

RESULTS

We excluded 4 patients (8.5%) because they had an extremely deficient acoustic window. In the remaining 43 patients, including those with a suboptimal acoustic window, we obtained the following correlations between 3DE and CMR: end-diastolic volume, 0.71; end-systolic volume, 0.77; ejection fraction, 0.74. Although the end-diastolic volume was systematically underestimated, no significant differences were observed in the ejection fraction. When the 11 patients with suboptimal acoustic windows were excluded, we observed a systematic underestimation of the end-diastolic and end-systolic volumes, which paradoxically gave rise to improved correlation coefficients (0.79, 0.92, and 0.84, respectively) and a more accurate ejection fraction.

CONCLUSIONS

Compared to CMR, 3DE systematically underestimates the ventricular volumes but enables adequate determination of the left ventricular ejection fraction regardless of the quality of the acoustic window.

Flow-volume loops derived from three-dimensional echocardiography: a novel approach to the assessment of left ventricular hemodynamics

Background

This study explores the feasibility of non-invasive evaluation of left ventricular (LV) flow-volume dynamics using 3-dimensional (3D) echocardiography, and the capacity of such an approach to identify altered LV hemodynamic states caused by valvular abnormalities.

Methods

Thirty-one patients with moderate-severe aortic (AS) and mitral (MS) stenoses (21 and 10 patients, respectively) and 10 healthy volunteers underwent 3D echocardiography with full volume acquisition using Philips Sonos 7500 equipment. The digital 3D data were post- processed using TomTec software. LV flow-volume loops were subsequently constructed for each subject by plotting instantaneous LV volume data sampled throughout the cardiac cycle vs. their first derivative representing LV flow. After correction for body surface area, an average flow-volume loop was calculated for each subject group.

Results

Flow-volume loops were obtainable in all subjects, except 3 patients with AS. The flow-volume diagrams displayed clear differences in the form and position of the loops between normal individuals and the respective patient groups. In patients with AS, an "obstructive" pattern was observed, with lower flow values during early systole and larger end-systolic volume. On the other hand, patients with MS displayed a "restrictive" flow-volume pattern, with reduced diastolic filling and smaller end-diastolic volume.

Conclusion

Non-invasive evaluation of LV flow-volume dynamics using 3D-echocardiographic data is technically possible and the approach has a capacity to identify certain specific types of alteration of LV flow-volume pattern caused by valvular abnormalities, thus reflecting underlying hemodynamic states specific for these abnormalities.

History of echocardiography and its future applications in medicine

This review concisely presents the chronology of events that shaped the development of echocardiography. The concept of "seeing" structures using "sound" dates back to the 1920s, when ultrasound produced by piezoelectric crystals was used to detect flaws in metals. In the early 1950s, Hertz and Edler described the use of ultrasound for assessing mitral-valve disease. Subsequently, Harvey Feigenbaum in the 1960s standardized the clinical use of M-mode echocardiography for quantitative assessment of left-ventricular dimensions. The advent of 2-dimensional echocardiography (1970s), pulsed Doppler (1970s), and color Doppler (1980s) introduced new methods for routine assessment of cardiac anatomy and hemodynamics at bedside. Flexible scopes and superior transducers further paved the way to the application of transesophageal echocardiography. Tissue Doppler and contrast echocardiography recently have emerged as important tools for evaluation of regional myocardial function and blood flow. Miniaturization and the ability to pack thousands of crystals in an electronic array have transformed the application of 3-dimensional echocardiography into a bedside tomographic tool. At the current pace of development, echocardiography will be able to provide complete assessment of the heart in terms of its anatomy, coronary flow, and physiology. Training people and making it available at every bedside may be the only remaining challenges.

Live/real time three-dimensional transthoracic echocardiographic assessment of left ventricular volumes, ejection fraction, and mass compared with magnetic resonance imaging

Due to reliance upon geometric assumptions and foreshortening issues, the traditionally utilized transthoracic two-dimensional echocardiography (2DTTE) has shown limitations in assessing left ventricular (LV) volume, mass, and function. Cardiac magnetic resonance imaging (MRI) has shown potential in accurately defining these LV characteristics. Recently, the emergence of live/real time three-dimensional (3D) TTE has demonstrated incremental value over 2DTTE and comparable value with MRI in assessing LV parameters. Here we report 58 consecutive patients with diverse cardiac disorders and clinical characteristics, referred for clinical MRI studies, who were evaluated by cardiac MRI and 3DTTE. Our results show good correlation between the two modalities.