Health & Medical Cardiovascular Health

Real-time Three-dimensional Transthoracic Echocardiography

Real-time Three-dimensional Transthoracic Echocardiography


A total of 320 patients (mean age 45 ± 8.4 years, 75% males) were enrolled in this study for evaluation of their cardiac condition using RT3D-TTE. The number of patients in each group of cardiac abnormalities was depending on the referral rate. The average time required for 3D data acquisition was 3.2 ± 1.5 min. Data analysis by Q-lab software was widely varied (4.5 to 15 min) according to the target structure.

LV Analysis

LV assessment of 90 cases with different diagnosis (15 normals, 35 patients with different types of cardiomyopathy, 35 patients with ischemic heart disease, and 5 patients with adult congenital heart disease) was performed by both 2D-TTE and RT3D-TTE. Visualization adequacy by both techniques was good in 51 cases (57%), and fair in 26 cases (29%). LV endocardial borders were not visualized in 13 cases (14%), and therefore excluded from the analysis. Interobserver and intraobserver agreement for adequacy of analysis by both techniques were very good (kappa: 0.81 and 0.83 for 2D-TTE) and (0.85 and 0.87 for RT3D-TTE). Complete offline analysis using 3DQ-Advanced software required 3–5 minutes.

The RT3D-TTE measurements of end-diastolic, end-systolic volumes and ejection fraction were well correlated with 2D-TTE measurements (r = 0.94) with significant underestimation of end-systolic volume by 2D-TTE (p = 0.01). RT3D-TTE measurement correlated better with CMR than with 2D-TTE (r = 0.95 vs 0.88). Compared to CMR, all 2D-TTE measurements and end-systolic volume by RT3D-TTE were significantly underestimated. However, the mean difference by Bland& Altman method between CMR and both 2D-TTE and RT3D-TTE measurement showed no significant difference ( Table 2 ).

RT3D-TTE assessment of LV synchronization was performed in 15 patients scheduled for cardiac resynchronization therapy (CRT) according to European society of cardiology guideline. The time-volume curves were obtained for the 16-segments before CRT to identify the dyssynchrony index and dyssynchronous segments. In 12 patients, RT3D-TTE detected interventricular and intraventricular dys-synchrony while in 3 patients; no dyssynchrony was detected. RT3D-TTE was repeated for those patients after CRT implant to assess the immediate result. The RT3D-TTE time volume curves became synchronized in the 12 patients who had dys-synchrony before CRT.

RV Analysis

Assessment of RV shape, volume, and function was performed in 20 cases (5 normals, 6 patients with pulmonary hypertension, 5 patients with RV dysplasia and 4 patients with dilated cardiomyopathy). Adequate visualization and complete analysis were obtained in 11 cases (55%), (5 normals, 3 patients with RV dysplasia and 3 patients with pulmonary hypertension). In the remaining 9 patients (45%), the analysis was not completed because the sector width of full volume 3D images could not include the whole dilated RV. Both 2D-TTE and RT3D-TTE measurements of RV volumes were well correlated (r = 0.87) but the RT3D-TTE values were higher than by 2D-TTE. CMR was performed in 7 patients for comparison, 2D-TTE measurements were significantly underestimated (Table 2). RT3D-TTE values had better correlation with CMR measurements than 2D-TTE (r = 0.86 vs 0.91)

Valvular Heart Disease

Mitral Valve (MV) Forty patients (20 with rheumatic mitral stenosis, 10 with mitral regurgitation, 5 with mitral valve prolapse and 5 normals) were studied. Adequate visualization was achieved in all patients. In patients with rheumatic mitral stenosis, both 2D-TTE and RT3D-TTE measurement of MV area were comparable (0.91 ± 0.13 cm vs. 0.92 ± 0.14 cm). RT3D-TTE provided more information about leaflets mobility, thickness, distribution and extent of calcification. Assessment of both commissures was clearly obtained by RT3D-TTE. Assessment of balloon mitral commissurotomy results in 6 patients by RT3D-TTE showed its ability to visualize and assess the degree of commissural splitting in the en face view with rotation of image from right to left (swivel mode) (Figure 2). By 2D-TTE, it was essential to modify the probe position to achieve visualization of each MV commissure separately because both commissures are not at the same level

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Figure 2.

Example of patient with mitral stenosis showing the stenotic valve orifice before (A) and after balloon valvuloplasty (B). (C) Side view of partially splitted commissure.

In 10 patients with mitral regurgitation, it was possible to assess the annulus size and function through cropping of the full 3D volume. The assessment of regurgitant jet (s) was performed by color flow RT3D-TTE. It was possible to visualize the shape and size of vena contracta in all 10 patients. Different shapes of vena contracta were found e.g. oval, circular, and irregular. Calculation of regurgitant jet volume was obtained only in 4 patients with central regurgitation. In the remaining 6 patients, the regurgitant volume could not be obtained because the jet was eccentric and directed posteriorly in 4 patients and multiple in 3 patients.

In 5 patients with MV prolapse, The RT3D-TTE enface view from its atrial and ventricular aspects could localize the prolapsed scallop (s) and chordae. The RT3D-TTE findings in 3 patient underwent MV surgery were similar to that obtained by intraoperative 2D-TEE and guided towards the proper surgical techniques of repair.

Aortic Valve (AV) Assessment of AV cusps, commissures and area was obtained in 35 patients (10 cases with rheumatic AV stenosis and 25 cases with congenital malformed AV). Good visualization was achieved in 31 patients (88%) by RT3D-TTE while, achieved in 22 patients (62%) by 2D-TTE. Visualization of AV cusps morphology (number, thickness and calcification) and measurements of AV area by planimetry were comparable for both 2D-TTE and RT3D-TTE. In 10 patients with rheumatic AV stenosis, measurement of AV area by planimetery was obtained in 80% and 46% of patients by RT3D-TTE and 2D-TTE respectively. The RT3D-TEE measurement of AV area was correlated well with the 2D-TTE measurement by continuity equation in all cases (r = 0.89; p < 0.0001).

Among the 25 patients with malformed AV, the valve morphology was bicuspid in 19 patients, quadricuspid in 2 patients, tricuspid in 3 patients and unicuspid in 1 patient (Figure 3). RT3D-TTE and 2D-TTE measurements of AV annulus and LV outflow tract were well correlated (r = 0.85; p < 0.001) but the RT3D-TTE measurements of aortic annulus and LVOT diameters were significantly larger than that obtained by 2D-TTE (2.05 ± 0.7 cm and 2.5 ± 0.86 vs. 1.94 ± 0.67 and 1.98 ± 0.74; p < 0.01). Measurement of AV area by planimetery could be obtained in 76% and 44% of patients by RT3D-TTE and 2D-TTE respectively. In the remaining 24% of cases the AV area could not be obtained by RT3D-TTE due to heavy calcification. RT3D-TEE measurement of AV area correlated well with the measurement obtained by continuity equation in all cases (r = 0.90; p < 0.0001).

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Figure 3.

Morphology of malformed aortic valve cusps: Tricuspid (A) and Bicuspid (B).

Tricuspid Valve (TV) RT3D-TTE assessment of TV was performed in 32 patients. 2D-TTE examination of those patients demonstrated that 10 patients had normal right- side heart, 7 with pulmonary hypertension, 10 with rheumatic TV involvement, and 5 with dilated cardiomyopathy involving RV. Adequate visualization of the three TV leaflets in the en face view was obtained in 26 patients (81%), while one of the TV leaflets was missed in the remaining 6 patients (19%). The RT3D enface view helped in identification of all TV leaflets in addition to the assessment of leaflets mobility, thickness and calcification and viewing the commissures (Figure 4A). The mechanism of tricuspid regurgitation could be identified in 20 patients as annular dilatation in 10 patients, leaflets thickening and restriction in 4 patients and mixed in 6 patients. In 6 patients with rheumatic tricuspid stenosis, measurement of TV area by planimetery could be obtained with good interobserver agreement.

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Figure 4.

Enface view of tricuspid valve (A) and pulmonary valve (B) showing all valve leaflets and commissures.

Pulmonary Valve (PV) RT3D-TTE assessment of PV could be performed in 5 patients with an established diagnosis of pulmonary stenosis. RT3D-TTE short axis view could visualize the abnormalities of PV three cusps through analysis of their thickness, mobility and commissures (Figure 4B). Measurement of PV annulus (area and diameter) could be obtained in all patients while PV area by planimetery was obtained in three of them.

Prosthetic Heart Valves and Ring Thirty patients with previous valve surgery were studied (10 bioprosthetic aortic valve, 9 bioprosthetic mitral valve, 3 metallic prosthetic valve and 8 C-rings). RT3D-TTE was performed for the assessment of valve function and to exclude infective endocarditis. RT3D-TTE was of great value in studying the valve mobility, calcification and detection of either vegetation or thrombus. RT3D-TTE with color was performed to assess valvular regurgitation and presence of paravalvular leakage. In every patient, adequate visualization of prosthetic valves and rings was achieved. Well functioning bioprosthetic valve was detected in 7 patients (4 in mitral position and 3 in aortic position). In 13 patients with high clinical suspicion of infective endocarditis, RT3D-TTE could clearly delineate the vegetations (size, site, attachment and number) in 6 patients and para-aortic abscesses (size, site, extension, wall thickness and points of communication) in 7 patients with bioprosthetic aortic valve. RT3D-TTE had additional value for complete definition of paravalvular leakage (site, size and extension) in 6 patients (Figure 5).

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Figure 5.

(A) Morphology of bi-leaflet metallic prosthetic valve in mitral position, (B) bioprosthetic valve with loose attachment to annulus that led to paravalvular leakage (arrows), and (C) Quadscreen of paraaortic abscess due to infective endocarditis of bioprosthetic valve.

Septal Defects (ASD and VSD)

A total of 30 cases with suspicious and/or definitive diagnosis of septal defects by 2D-TTE were evaluated by RT3D-TTE. RT3D-TTE could rule out septal defects in three cases and proved the diagnosis of ASD in 18 cases, patent foramen ovale in three cases, and VSD in 6 cases. Through the RT3D-TTE enface view; a comprehensive assessment of septal defects with its relation to adjacent structures was obtained. In addition, enface view allowed accurate measurements of the defect size and rims to assess the suitability for device closure (Figure 6). 14 patients with ASD underwent percutaneous closure with Amplatzer device and 4 patients underwent surgical closure. The RT3D-TTE measurement of defect size showed excellent correlation with that obtained at surgery and by balloon occlusive diameter (r = 0.930, p ≤ 0.0001). In patients with VSD, two patients underwent device closure and four patients underwent surgical closure. Post-procedure RT3D-TTE assessment of the 16 patients who underwent device implantation was valuable in the assessment of device position and ruling out residual shunt.

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Figure 6.

Enface view of ASD before (A) and after (B) device closure, and muscular VSD(C).

Intra-cardiac Thrombi

Forty five intracardiac thrombi were detected by both 2D-TTE and RT3D-TTE (34 in the LV, 6 in the LA, 4 in LAA, 4 in the RA, and 2 in the RV). RT3D-TTE could detect 7 additional thrombi in 5 patients (3 in the LAA and 4 in the LV apex). Examination of LV and LA was obtained from apical views. Assessment of LAA was performed through modification of short axis at aortic valve level, apical 4 and apical 2-chamers views. RT3D-TTE images provided a comprehensive description of the different shapes of the thrombi (horse-shoe shape, bilobed, multi-lobulated, oval, and irregular), attachment to the cardiac wall and their mobility. Multiple cut sections at different levels helped in identification of the thrombus consistency, presence of degeneration and/or calcification in chronic organized thrombi (Figure 7-left panel).

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Figure 7.

Left panel showing different examples of intracardiac thrombi into LV (A, B), RV(C), and LA appendage (D). Right panel showing quadscreen of RA myxoma.

Both 2D-TTE and RT3D-TTE techniques showed good correlation for the measurement of the maximum diameter of the thrombus (R = 0.89, P < 0.001). However, RT3D-TTE measurements were larger than 2D-TTE (27.6 ± 9.9 mm vs. 22.4 ± 7.1 mm; p < 0.0001). Volume quantification of the thrombi was only obtained by RT3D-TTE (9.4 ± 6.7 mm). Transesophageal 2DE was performed for the assessment of 13 thrombi detected by RT3D-TTE (7 inside LAA and 6 inside LA). There was an excellent agreement between both techniques for visualization of thrombi (Kappa: 0.90) with no significant difference between the measurements of the maximum diameter of thrombi (23.6 ± 6.7 mm and 22.4 ± 8.1 mm respectively; P = 0.7). RT3D-TTE showed very good interobserver agreement for visualization of LV and LA thrombi (Kappa: 0.81), while it was good for LAA, RA and RV thrombi (Kappa: 0.41). 2D-TTE showed good interobserver agreement for LV thrombi (Kappa: 0.46), and poor agreement for LAA, RA and RV thrombi (Kappa: 0.31). The 2DE and RT3D-TTE measurement of maximum diameter by the 2 observers showed good correlation (R = 0.95; p < 0.0001 and R = 0.99; p < 0.0001 respectively). According to Bland and Altman method for interobserver agreement, RT3D-TTE measurements showed better agreement (2.88,-1.92) than that of 2DE (5.33,-3.87).

Intra-cardiac Tumors

LA myxoma was detected in three patients and RA myxoma in two patients. Cardiac metastasis was detected inside RA in two cases with advanced hepatoma. In all cases, 2D-TTE could identify the masses location and anatomical relationship with the surrounding structures. RT3D-TTE identified the site of attachment, the extent of the intracardiac tumors, and their influence on valvular function. Volume calculation of intracardiac masses could be obtained only with RT3D-TTE. Surgical view could be obtained by RT3D-TTE through electronically dissect cardiac structures which was very helpful pre-operatively in facilitating surgical planning (Figure 7-right panel).

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