Geometric determinants of functional tricuspid regurgitation: Insights from 3-dimensional echocardiography

BACKGROUND - Tricuspid regurgitation (TR) is an important predictor of morbidity and mortality in heart failure. We aimed to examine the 3D geometry of the tricuspid valve annulus (TVA) in patients with functional TR, comparing them with patients with normal tricuspid valve function and relating annular geometric changes to functional TR. METHODS AND RESULTS - TVA shape was examined by real-time 3D echocardiography in 75 patients: 35 with functional TR and 40 with normal tricuspid valve function (referent group). The 3D shape of the TVA was reconstructed from rotated 2D planes, and the annular plane was computed by least-squares fitting. Annular area and mediolateral, anteroposterior, and high (superior)-low (inferior) distances were calculated. TR was assessed by vena contracta width. The normal TVA has a bimodal pattern (high-low distance=7.23±1.05 mm). High points were located anteroposteriorly, and low points were located mediolaterally. With moderate or greater TR (vena contracta width 5.80±2.62 mm), the TVA became dilated (17.24±4.75 versus 9.83±2.18 cm, P<0.0001, TR versus referent), more planar with decreased high-low distance (4.14±1.05 mm), and more circular with decreased ratio of mediolateral/anteroposterior (1.11±0.09 versus 1.32±0.09, P<0.0001, TR versus referent). CONCLUSIONS - The normal TVA has a bimodal shape with distinct high points located anteroposteriorly and low points located mediolaterally. With functional TR, the annulus becomes larger, more planar, and circular. These changes in annular shape with TR have potentially important mechanistic and therapeutic implications for tricuspid valve repair.