Determination of vena contracta and its value in evaluating severity of aortic regurgitation

Recent studies evaluating the severity of valvular insufficiencies have focused on the effective regurgitant orifice area (EROA), which corresponds hydrodynamically to the cross-sectional area of the vena contracta (VC). The study aim was to quantify aortic regurgitation (AR) by using color Doppler imaging of the VC.

Fifty-five patients with chronic AR were enrolled into the study. VC was visualized by transthoracic echocardiography from the apical echocardiographic window. The quantitative Doppler (QD) method, depending on mitral and aortic stroke volumes, was taken as a reference method. EROA, regurgitant volume (RV) and regurgitant fraction (RF) were calculated using both VC and QD simultaneously in all patients, and the results obtained with each method were compared.

EROA(QD) (r = 0.96), RFQD (r = 0.84), RVQD (r = 0.82), and AR grade 3+ or 4+ (r = 0.74) were statistically significantly correlated with VC (4.8+/-1.2 mm). In the multivariate analysis, VC was related only to EROA(QD). The EROA (r = 0.96, p <0.001; mean difference 0+/-0.03 cm2, SEE = 0.004 and p >0.05), RV (r = 0.97, p <0.001; mean difference =1.3+/-4.8 cm3, SEE = 0.65 cm3 and p >0.05) and RF (r = 0.93, p <0.001; mean difference = 1.46+/-4.9%, SEE = 0.66% and p >0.05) obtained by both methods agreed well with each other. VC had a sensitivity of 80%, a specificity of 86%, and an accuracy of 84% in determining severe AR for VC > or =5.5 mm.

The vena contracta can be visualized using a transthoracic approach from the apical window. The severity of AR can be evaluated using the VC width itself, and also in combination with Doppler data.