The echocardiographic assessment of functional mitral regurgitation.

Functional mitral regurgitation (MR) is common, clinically important, and mechanistically complex. Its assessment by echocardiography can be challenging, and particular care is needed in the quantification of severity. Echocardiographers need to be aware of the potential limitations of flow convergence and vena contracta methods in assessing severity and alert to the prognostic importance of even moderate functional MR. Three-dimensional echocardiography has the potential to improve both the understanding of the mechanisms of functional MR and the accuracy of its quantification.