Background: The geometric and hemodynamic determinants of functional tricuspid regurgitation (FTR) have not yet been established. Geometric alterations in the tricuspid valve can be accurately determined using 3-dimensional echocardiography.
Methods: Real-time 3-dimensional echocardiography was performed in 54 patients with various degrees of FTR to obtain real-time zoom 3D images of the tricuspid valve. The angles between the tricuspid annulus plane and the 3 leaflets (anterior: Aalpha, posterior: Palpha, septal: Salpha), the septal-lateral and anterior-posterior annulus diameters, and the tricuspid tenting volume were measured on a mid-systole frame. Pulmonary artery systolic pressure (PASP) was assessed using the maximal velocity of FTR, and the severity of FTR was quantified as the ratio of the distal jet area to the right atrial area (DJ/RA) using color Doppler 2D echocardiographic images.
Results: In patients with mild (DJ/RA<0.2) and moderate (0.2< or =DJ/RA<0.5) FTR, Palpha and Salpha were significantly larger than Aalpha, whereas in patients with severe (DJ/RA> or =0.5) FTR, only Salpha was larger than Aalpha. All geometric variables and PASP correlated significantly with DJ/RA. Multiple stepwise regression analysis showed that Salpha, septal-lateral annulus diameter and PASP were independent determinants of FTR severity. The tricuspid tenting volume strongly correlated (r=0.84, p<0.001) with the FTR distal jet area, and was the only determinant of the jet area.
Conclusion: FTR severity is mainly determined by septal leaflet tethering, septal-lateral annular dilatation, and the severity of pulmonary hypertension.