Regurgitation (insufficiency) is blood flow in the opposite direction from normal, as the backward flowing of blood into the heart or between heart chambers. Can be categorized by:
Pulmonic regurgitation: the backflow of blood from the pulmonary artery into the right ventricle, owing to insufficiency of the pulmonic semilunar valve.
Tricuspid regurgitation: the backflow of blood from the right ventricle into the right atrium, owing to imperfect functioning (insufficiency) of the tricuspid valve.