Tricuspid Valve Remodeling in Pressure versus Volume Overload and its Relationship with Tricuspid Regurgitation Severity: A 3-Dimensional Echocardiographic Study

Objective:
To compare the extent of tricuspid valve (TV) remodeling in patients with pressure versus volume overload [pulmonary hypertension (PH) versus severe pulmonary regurgitation in operated tetralogy of Fallot (TOF)] and the relationship of TV remodeling with tricuspid regurgitation (TR) severity.

Methods:
Thirty-one patients with pre-capillary PH (TR pressure gradient 74±23 mmHg) and 23 patients with operated TOF underwent 3-dimensional (3D) transthoracic echocardiography of the right heart (Vivid E9, GE Medical Systems, Horten, Norway). Using 3D-derived multi-plane reconstruction (“Flexi-slice” function) the TV was imaged in 3 planes, each plane dissecting the middle of a TV leaflet and the center of the TV. Effective leaflet length (e-LL, distance from posterior coaptation point to annulus hinge point), coaptation length (CL, distance between leaflet tip and posterior coaptation point), total leaflet length (t-LL = e-LL + CL), tricuspid annulus (TA) diameter, tenting height, and tenting area were measured in each plane and averaged for the 3 leaflets. Right ventricular (RV) and right atrial (RA) volumes were measured by 3D echocardiography. TR was assessed quantitatively by the proximal isovelocity surface area method.

Results:
Significant TR was more frequent in PH than in TOF [> moderate TR in 17 (55%) versus 3 patients (13%), respectively, P <0.001]. TV remodeling was more prominent in PH, mainly measures of leaflet tethering (Table 1). By multi-variable linear regression, TV remodeling variables were strongly associated with TR severity (effective regurgitant orifice, ERO) in both groups (Table 2), more so in PH (larger model R²). RV end-diastolic volumes (but not end-systolic volumes or ejection fraction) and RA end-systolic volumes correlated with TV tethering (Figure).

Conclusions:
RV pressure results in significant right-heart and TV remodeling and, eventually, TR. These processes are less pronounced in RV volume overload, thereby explaining the lower frequency of significant TR in RV volume (versus pressure) overload.