The pathogenesis of functional tricuspid regurgitation.

Functional tricuspid regurgitation (TR) is a common etiology of TR. Functional TR results from geometrical distortion of the normal spatial relationships of the tricuspid leaflets, annulus, chords, papillary muscles, and right ventricular (RV) walls. Functional TR results most commonly from left-sided heart disease, including mitral valve abnormalities and cardiomyopathy and RV dysfunction secondary to pulmonary disease (Cor pulmonale). The tricuspid annulus, which has a normal bimodal or saddle shape, becomes larger, flatter, and more circular with the development of functional TR. RV dilation can lead to papillary muscle displacement and tethering of the tricuspid leaflets, resulting in incomplete coaptation and development of functional TR.