Introduction 1 2 3 4 5 6 7 8 9 Subjects and methods 1 Fig. 1 TomTec quadri screen display of the tricuspid valve. The upper two images represent two-dimensional views created from the 3D data set (4-chamber, left and orthogonal view, right). The lower left image represents a two-dimensional short axis view and the lower right image represents the 3D image  For quantitative assessment of TV the following RT3DE data were obtained: 1) TV annulus diameter defined as the widest diameter that could be measured from an end-diastolic still frame, 2) maximal TV annulus area obtained from an end-diastolic still frame and measured by manual planimetry, 3) TV area defined as the narrowest part of the TV at the time of maximal opening and measured by manual planimetry, and 4) TV commissural width obtained from a late-diastolic still frame using zoom function to avoid underestimation. The images were optimized for each commissure along its plane to measure the maximal width of the angle formed by the two adjacent TV leaflets. 1 Statistical analysis 10 1 Table 1 Scores for real-time three-dimensional echocardiography visualization of TV structures Score TV annulus TV leaflets TV area TV commissures Good (4) 60% 80% 55% 50% Sufficient (3) 30% 10% 30% 20% Inadequate (2) 10% 10% 15% 20% Not visualized (1) 0% 0% 0% 10% Mean score 3.5 ± 0.7 3.7 ± 0.6 3.4 ± 0.7 3.1 ± 1.0 Median score 3.0 3.0 3.0 2.5 Abbreviations: TV = tricuspid valve Results Acquisition and analysis of the RT3DE data was performed in approximately 10 min per patient. The TV could be visualized in 90% of patients enface from both ventricular and atrial aspects in relation to adjacent cardiac structures. In these 90 patients detailed analysis of the TV was performed including tricuspid annulus shape and size, TV leaflets shape, size, and mobility, and commissural width. Tricuspid annulus 2 2 Fig. 2 Oval-shaped Tricuspid annulus (the line represent the tricuspid annulus diameter, the dots demark the area)  Tricuspid valve leaflets Visualization of the three TV leaflets (in motion) was good in 72 patients (80%), sufficient in 9 patients (10%), and inadequate in another 9 patients (10%). The anterior leaflet was the largest and most mobile of the three leaflets and had a nearly semicircular shape. The septal leaflet was the least mobile and had a semi-oval shape. Its position was parallel to the interventricular septum. The posterior leaflet was the smallest one with variable shape. It was clearly separated from the septal leaflet in all patients but in 10% of patients it was hard to discriminate the posterior leaflet from the anterior leaflet even during maximal TV opening. 3 Fig. 3 Identification of the tricuspid valve leaflets seen on two-dimensional imaging. Below the 2D images, percentage of leaflet identification in each standard view depending the RT3DE images  Tricuspid valve area 4 2 Fig. 4 Triangular shape TV area and commissural views  Tricuspid valve commissures 4 2 Table 2 Normal (absolute and index) values of tricuspid valve annulus (diameter and area), Tricuspid valve area and the width of the 3 commissures Parameter Absolute value Index value Tricuspid annulus diameter  4.0 ± 0.7 (cm) 2 Tricuspid annulus area  2 2 2 Tricuspid valve area  2 2 2 Antero-septal commissure  5.4 ± 1.5 (mm) 2 Postero-septal commissure 5.2 ± 1.5 (mm) 2 Antero-posterior commissure  5.1 ± 1.1 (mm) 2 Interobserver variability 5 r P r P r P 2 Fig. 5 Interobserver correlations (top) and Bland–Altman analysis (bottom) of TV annulus, leaflets, and commissures  Intraobserver variability 2 Discussion 11 13 9 14 15 16 6 17 16 17 3 6 Fig. 6 Surgical view of the heart valves demonstrating the range of the two-dimensional echocardiographic 4-chamber and short-axis planes  18 19 20 21 2 3 7 22 Fig. 7 A B C  Limitation of study The main limitation of this study is that RT3DE data were not compared with a “gold standard” such as magnetic resonance imaging, autopsy or surgical findings. Also, RT3DE images more critically depend on 2DE image quality and could be obtained only in patients with sinus rhythm during hold breath that limits its application to all. The study included patients with narrow age range (21–39 years), and thus the normal findings in this study is confined to this age group and could not be applied to both extremities (<21 and >39 years). Conclusion Three-dimensional imaging of the TV is feasible in a large number of patients. RT3DE may add to functional 2DE data in description of TV anatomy and providing highly reproducible and actual reality (anatomic and functional) measurements.