Three-dimensional echocardiography in adult patients: comparison between transthoracic and transesophageal reconstructions

Global longitudinal strain and global circumferential strain by speckle-tracking echocardiography and feature-tracking cardiac magnetic resonance imaging: comparison with left ventricular ejection fraction

BACKGROUND

Left ventricular (LV) ejection fraction (EF) is a routine clinical standard to assess cardiac function. Global longitudinal strain (GLS) and global circumferential strain (GCS) have emerged as important LV functional measures. The objective of this study was to determine the relationships of GLS and GCS by speckle-tracking echocardiography and featuring-tracking cardiac magnetic resonance (CMR) to CMR EF as a standard of reference in the same patients.

METHODS

A total of 73 consecutive patients aged 55 ± 15 years clinically referred for both CMR and echocardiography (EF range, 8%-78%) were studied. Routine steady-state free precession CMR images were prospectively analyzed offline using feature-tracking software for LV GLS, GCS, volumes, and EF. GLS was averaged from three standard longitudinal views and GCS from the mid-LV short-axis plane. Echocardiographic speckle-tracking was used from the similar imaging planes for GLS, GCS, LV volumes, and EF.

RESULTS

Feature-tracking CMR strain was closely correlated with speckle-tracking strain in the same patients: GLS, r = -0.87; GCS, r = -0.92 (P < .0001). End-diastolic and end-systolic volumes and EF by feature-tracking CMR were significantly correlated with standard manual tracing of multiple CMR short-axis images (r = 0.97, r = 0.98, and r = 0.97, P < .0001 for all). GLS and GCS by echocardiography and CMR feature-tracking were closely correlated with standard CMR EF: r = -0.85 and r = -0.95, respectively (P < .001). Global strain measures (in absolute values) were correlated with EF using the formula EF = 3(GLS) + 8% or EF = 2.5(GCS) + 8%.

CONCLUSIONS

GLS and GCS by feature-tracking CMR analysis was a rapid means to obtain myocardial strain similar to speckle-tracking echocardiography. GLS and GCS were closely correlated with CMR EF in this patient series and may play a role in the clinical assessment of LV function.

Pre-operative transthoracic real-time three-dimensional echocardiography in patients undergoing mitral valve repair: accuracy in cases with simple vs. complex prolapse lesions

AIMS

The aim of this study, undertaken in patients who underwent mitral valve (MV) repair surgery, was to evaluate the accuracy of pre-operative three-dimensional (3D) transthoracic echocardiography (TTE) in the evaluation of MV pathology in cases with simple or complex lesions.

METHODS AND RESULTS

Two hundred consecutive patients with severe mitral regurgitation due to degenerative MV prolapse underwent a complete 3DTTE the day before surgery. Three-dimensional TTE data were compared with MV surgical inspection. Three-dimensional echocardiography was feasible in a relatively short time (5 ± 3 min) with good (67%) and optimal (21%) imaging quality in the majority of cases. Three-dimensional TTE allowed an accurate identification (95% accuracy) of all MV lesions. Seventy-three (36.5%) patients had simple lesions at 3DTTE and 71 of them (97.2%) underwent a simple surgical procedure; 127 (63.5%) had complex lesions at 3DTTE and, in these cases, surgeons performed either simple procedures (48%) or complex procedures (47.2%) or valve replacement in 4.7% (after a first attempt for repair).

CONCLUSION

Three-dimensional TTE is feasible, not time-consuming, and accurate in identifying cases with simple vs. complex MV lesions.

Head-to-head comparison of two- and three-dimensional transthoracic and transesophageal echocardiography in the localization of mitral valve prolapse

OBJECTIVES

The aim of this study, undertaken in patients who underwent mitral valve (MV) repair surgery, was to evaluate the feasibility and accuracy of 3-dimensional (3D) transthoracic (TTE) and transesophageal (TEE) echocardiography in the evaluation of MV pathology.

BACKGROUND

A pre-operative assessment of MV anatomy is essential to surgical design in patients undergoing MV repair. Although 2-dimensional (2D) echocardiography provides precise information regarding MV anatomy, 3D TTE and 3D TEE could increase the understanding of MV apparatus and individual scallop identification.

METHODS

One-hundred-twelve consecutive patients with severe mitral regurgitation due to MV prolapse underwent a complete 2D and 3D TTE the day before surgery and a complete 2D and 3D TEE in the operating room. Echocardiographic data obtained by the different techniques were compared with surgical inspection.

RESULTS

Three-dimensional techniques were feasible in a relatively short time (3D TTE: 7 +/- 4 min; 3D TEE: 8 +/- 3 min), with good (3D TTE 55%; 3D TEE 35%) and optimal (3D TTE 21%; 3D TEE 45%) imaging quality in the majority of cases. Three-dimensional TEE allowed more accurate identification (95.6% accuracy) of all MV lesions in comparison with other techniques. Three-dimensional TTE and 2D TEE had similar accuracies (90% and 87%, respectively), whereas the accuracy of 2D TTE (77%) was significantly lower.

CONCLUSIONS

Three-dimensional TTE and TEE are feasible and useful methods in identifying the location of MV prolapse. They were superior in the description of pathology in comparison with the corresponding 2D techniques and should be regarded as an important adjunct to standard 2D examinations in decisions regarding MV repair.

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.

Use of Real-time 3-dimensional Transthoracic Echocardiography in the Evaluation of Mitral Valve Disease

Three-dimensional (3D) echocardiography (3DE) provides unique orientations of the mitral valve (MV) not obtainable by routine 2-dimensional echocardiography. However, this modality has not been adopted in routine clinical practice because of its cumbersome and time-consuming process. The recent introduction of a full matrix-array transducer has enabled online real-time 3DE (RT3DE) and rendering. This study was designed to: (1) determine the clinical use of RT3DE in patients with MV pathology and in a control group selected for their good acoustic windows (protocol I); and (2) to investigate the feasibility of imaging the MV apparatus in a large group of consecutively imaged patients to determine the acoustic window or perspective from which the MV leaflets, commissures, and orifice are best visualized (protocol II). In protocol I, 65 patients were selected based on MV pathology and good 2-dimensional echocardiography image quality. Protocol II included 150 patients who were consecutively imaged using RT3DE. Images were viewed online (protocol I) and offline on a digital review station (protocol II). RT3DE visualization of the MV apparatus was graded based on the percentage of leaflet dropout and definition. In protocol I, 78% of patients had adequate 3D MV reconstructions with complete visualization of the anterior mitral leaflet (AML) in 84% versus the posterior mitral leaflet (PML) in 77%. The mitral leaflets, commissures, and MV orifice were well seen in 98%; however, the submitral apparatus was only observed in 76% of the patients. RT3DE: (1) correctly identified the prolapsed/flailed scallop in 6 of 8 patients; (2) obtained en face orientation of the MV orifice in 9 of 11 patients with mitral stenosis, allowing accurate measurements of the orifice area and evaluation of the immediate effects of balloon mitral valvuloplasty; and (3) allowed postoperative evaluation of MV repair and the integrity of the struts of a bioprosthetic leaflet. In protocol II, 70% of patients had adequate RT3DE with complete visualization of the AML noted in 55% versus 51% for PML. The mitral leaflets, commissures, and MV orifice were observed in 69%. Irrespective of acquisition window, the AML was best seen from a ventricular perspective. In contrast, the PML was optimally examined from a parasternal window. Both the medial and lateral commissures were equally assessed from either imaging window. In conclusion, RT3DE of the MV is feasible in a large majority of patients. Using different MV acquisitions RT3DE provides important clinical information such as: (1) identification of a prolapsed/flail scallop; (2) measurement of stenotic valve areas; (3) evaluation of MV leaflet integrity postrepair; and (4) identification of a MV perforation. In general the AML is better visualized than the PML. The parasternal window is the optimal approach to visualize both AML and PMLs.

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.

Left atrial volume determination by three-dimensional echocardiography reconstruction: validation and application of a simplified technique

Left atrial (LA) size assessment by anteroposterior dimension is limited in accuracy. Conventional 3-dimensional (3D) reconstruction has been validated, but the process is time-consuming and the 3D system is not widely available. We developed an algorithm to simplify 3D reconstruction of LA on the basis of 3 standard apical views, tested it in 44 hemodynamic stages of 8 open-chest dogs, and compared it with LA volumes assessed by conventional 3D reconstruction. Simplified 3D reconstruction provided an accurate LA volume measurement (y = 0.93x + 0.7, r = 0.95, standard error of the estimate [SEE] = 3.6) with more than 60% of time saved. Cubic equation of anteroposterior dimension and biplane modified Simpson's method were less accurate (for biplane modified Simpson's method, y = 0.8x + 2.6, r = 0.88, SEE = 5.0; for cubic equation of anteroposterior dimension, y = 0.65x + 2.6, r = 0.76, SEE = 8.2). Without the need for a 3D-imaging acquisition tool, simplified 3D reconstruction can be applied in the clinical setting for LA size quantitation with significant time saved.

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.