Morphologic Types of Tricuspid Regurgitation: Characteristics and Prognostic Implications

Tricuspid regurgitation (TR) is classified according to different morphologic types based on the underlying mechanisms: primary, secondary, and isolated TR. Primary TR is caused by an anatomical abnormality of the tricuspid valve apparatus. Secondary TR is caused by dilation of the tricuspid valve annulus, related to right ventricular (RV), or right atrial remodeling and increased RV pressures (often secondary to left-sided heart disease). Isolated TR can exist in patients without increased RV pressures and is frequently associated with atrial fibrillation. Two-dimensional echocardiography plays a pivotal role in the assessment of the etiology and severity of TR. Views from 3-dimensional techniques have significantly increased the understanding of the pathophysiology of each morphologic type of TR (leaflet damage, annular dilation, and distinct patterns of right-heart remodeling). The following review will describe the etiology, anatomical and functional characteristics, and outcomes of each morphologic type of TR, and furthermore addresses challenging pitfalls in the referral for tricuspid valve intervention.