The vena contracta in functional tricuspid regurgitation: a real-time three-dimensional color Doppler echocardiography study.

BACKGROUND: The aims of this study were to evaluate the three-dimensional features and geometric determinants of the vena contracta (VC) in functional tricuspid regurgitation (TR) and to identify optimal width cutoff values for assessing functional TR severity.

METHODS: Real-time three-dimensional full-volume and color Doppler and two-dimensional Doppler echocardiographic images were obtained in 52 patients with various degrees of functional TR and in sinus rhythm. The tricuspid valve and right ventricle were geometrically analyzed. VC widths parallel to the septal-lateral and anteroposterior directions, VC area, and effective regurgitant orifice area (EROA) using proximal isovelocity surface area methods on real-time three dimensional color Doppler images were measured.

RESULTS: The septal-lateral VC width was 0.39 ± 0.37 cm smaller than the anteroposterior VC width (P < .001). VC widths and area were strongly correlated with EROA. The optimal cutoff values for the septal-lateral VC width, anteroposterior VC width, and VC area were 0.63 cm, 0.76 cm, and 0.37 cm(2), respectively, for moderate functional TR (EROA ≥0.2 cm(2)) and were 0.84 cm, 1.26 cm, and 0.57 cm(2), respectively, for severe functional TR (EROA ≥0.4 cm(2)). Multiple linear regression analyses showed that the septal leaflet tenting angle and septal-lateral annular diameter independently determined septal-lateral VC width, while the anterior leaflet tenting angle and anteroposterior annular diameter independently determined the anteroposterior VC width.

CONCLUSIONS: Different VC width cutoff values should be applied according to the plane of view in functional TR, because the VC cross-sectional shape is ellipsoidal with a long anteroposterior direction. VC widths are determined by annular dilation and leaflet tenting in the corresponding directions.