Three-dimensional geometry of the tricuspid annulus in healthy subjects and in patients with functional tricuspid regurgitation - A real-time, 3-dimensional echocardiographic study

Background - Most rings currently used for tricuspid valve annuloplasty are formed in a single plane, whereas the actual tricuspid annulus (TA) may have a nonplanar or 3-dimensional (3D) structure. The purpose of this study was therefore to investigate the 3D geometry of the TA in healthy subjects and in patients with functional tricuspid regurgitation (TR). Methods and Results - This study consisted of 15 healthy subjects and 16 patients with functional TR who had real- time 3D echocardiography. With our customized software, 8 points along the TA were determined with the rotated plane around the axis at 45 degrees intervals. The TA was traced during a cardiac cycle. The distance between diagonals connecting 2 points was measured. The height was defined as the distance from the plane determined by least- squares regression analysis at all 8 points. Both the maximum (7.5 +/- 2.1 versus 5.6 +/- 1.0 cm(2)/m(2)) and minimum (5.7 +/- 1.3 versus 3.9 +/- 0.8 cm(2)/m(2)) TA areas in patients with TR were larger than those in healthy subjects (both P < 0.01). Healthy subjects had a nonplanar-shaped TA with homogeneous contraction. The posteroseptal portion was the lowest toward the apex from the right atrium, and the anteroseptal portion was the highest. In patients with functional TR, the TA was dilated in the septal to lateral direction, resulting in a more circular shape than in healthy subjects. A similar 3D pattern was observed in patients with TR, but it was more planar than that in healthy subjects. Conclusions - Real-time 3D echocardiography showed a complicated 3D structure of the TA, which appeared to be different from the "saddle- shaped" mitral annulus, suggesting an annuloplasty for TR different from that for mitral regurgitation.