The various types of heart valve regurgitation via insufficiency are as follows: •
Aortic regurgitation: the backflow of blood from the
aorta into the left
ventricle, owing to insufficiency of the aortic semilunar valve; it may be
chronic or
acute. •
Mitral regurgitation: the backflow of blood from the left ventricle into the left
atrium, owing to insufficiency of the
mitral valve; it may be acute or chronic, and is usually due to mitral valve prolapse,
rheumatic heart disease, or a complication of cardiac dilatation. See also
Mitral regurgitation. •
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. Regurgitation in or near the heart is often caused by valvular insufficiency (insufficient function, with incomplete closure, of the
heart valves); for example,
aortic valve insufficiency causes regurgitation through that valve, called aortic regurgitation, and the terms
aortic insufficiency and
aortic regurgitation are so closely linked as usually to be treated as
metonymically interchangeable. ==Regurgitant fraction==