Functional tricuspid regurgitation and the right ventricle: what we do not know is more than we know

The tricuspid valve (TV) lies in between the right atrium and the right ventricle (RV), consisting of annulus, leaflets, chords and papillary muscles. The RV appears triangular-shaped in a lateral view and crescent-shaped in a cross-section one. In normal conditions, the septum is concave toward the left ventricle (LV) in both systole and diastole and the RV volume is larger than the LV volume, although its mass is a third of the LV. The strict relationship between the TV apparatus and the RV underlies the physiological mechanism of TV functioning, and so, the RV plays an important role in case of functional tricuspid regurgitation. Nevertheless, the systematic assessment of RV is still not performed mainly due to lack of standardization. Hence, new echocardiographic guidelines have recently been proposed to standardize the RV assessment using transthoracic 2D‑echocardiography. 3D-echocardiography and MRI are more useful to measure volumes and ejection fraction; in particular, MRI is able to provide a tissue evaluation. Today, surgical strategies are directed mainly to the annulus with fluctuating results because functional tricuspid regurgitation is not due only to the annulus but also to the RV, which is difficult to assess, due to its evolution being unpredictable and complicated by the interaction with LV.