Vena contracta for quantification of mitral regurgitation
Measurement of the Vena Contracta is one of the methods for quantification of mitral regurgitation. Vena contracta is the narrowest region of the neck of the mitral regurgitation flow at the regurgitant orifice. The width of vena contracta will correspond to the diameter of the effective regurgitant orifice (ERO).
It may be noted that current guidelines of American Society of Echocardiography and European Association of Echocardiography suggest that color Doppler jet assessment should be used only for the diagnosis of mitral regurgitation, and not for exact quantification. This is because the color Doppler jet method is not excellent for quantification, though it will not be erroneous at both extremes – in the trivial and severe situations.
Finer details of measurement of vena contracta
Vena contracta is measured in a view with the ultrasound beam perpendicular to the flow.
Parasternal long axis view is used for measurement in case of mitral regurgitation. In this view the ultrasound beam is perpendicular to the mitral regurgitation flow. In certain eccentric mitral regurgitation jets, it may be measured well in the apical four chamber view.
A zoomed image visualising the proximal flow convergence, the vena contracta and the downstream flow jet is needed for the measurement.
Assessment of severity of mitral regurgitation from vena contracta
This is how the severity of mitral regurgitation is assessed:
In severe mitral regurgitation, the vena contracta usually measures 7 mm or more.
Values less than 3 mm excludes severe mitral regurgitation.