Vena contracta width (VCW) in aortic regurgitation (AR) is the width of the narrowest part of the regurgitant blood jet immediately at or just below the leaking aortic valve, measured with color Doppler echocardiography.

It is a semi-quantitative surrogate for the size of the effective regurgitant orifice: a wider vena contracta generally means more severe leakage.

Measure it in a well-aligned, zoomed parasternal long-axis or transesophageal long-axis view, at the jet neck, not at the widest downstream portion of the jet. Jet length and overall jet area alone are less reliable because they depend on loading conditions and eccentricity.

Important caveats: multiple jets should not simply be added by width, and irregular or noncircular regurgitant orifices can make a single 2D width misleading. Interpret VCW alongside flow reversal in the descending aorta, regurgitant volume/fraction, effective regurgitant orifice area, and left-ventricular response. The ESC AR echocardiography review gives the same <3 mm, 3-6 mm, and >6 mm thresholds.

Goldman-Cecil Medicine International Edition, section “Valvular Regurgitation,” states that VC <3 mm indicates mild AR and >6 mm indicates severe AR.