Echocardiographic insights into atrial and ventricular mechanisms of functional tricuspid regurgitation

Background: The etiology of functional tricuspid regurgitation (TR) is thought to be annular dilatation and tethering of tricuspid valve (TV) leaflets. However, mechanisms of leaflet tethering are incompletely understood. The purpose of this study was therefore to investigate the relationships between TV annular dilatation and leaflet tethering with the severity of functional TR and to investigate factors that influence these TV deformations. Methods: Two hundred forty-five patients with functional TR had 2-dimensional echocardiography. Echocardiographic investigations focused on the ventricles and on the TV. Ventricular measurements included left ventricular (LV) volume, right ventricular (RV) area, and RV spherical index. Valvular measurements included systolic TV annular dimension and apical displacement (tethering height), as well as severity of TR (vena contracta width). Results: Tethering height (r² = 0.25) was related to the severity of TR (P < .001). The RV and right atrium areas influenced both annular dimension and tethering height. However, LV ejection fraction and RV spherical index affected tethering height but not annular dimension. Conclusions: Tethering of TV leaflets, a determinant of functional TR, is associated with changes in right-sided cavity size as well as RV sphericity and LV function, emphasizing the impact of changes in ventricular geometry and function on the severity of functional TR.