Direct assessment of size and shape of noncircular vena contracta area in functional versus organic mitral regurgitation using real-time three-dimensional echocardiography

Background: Vena contracta width ( VCW) as an estimate of effective regurgitant orifice area ( EROA) is an accepted parameter of mitral regurgitation ( MR) severity. However, uncertainty exists in cases in which VCW at the same time appears narrow in 4-chamber ( 4CH) view and broad in 2-chamber ( 2CH) view as common in functional MR with noncircular or slit-like regurgitant orifices. We therefore hypothesized that new real-time 3-dimensional color Doppler echocardiography ( RT3DE) can be used for direct assessment of the size and shape of vena contracta area ( VCA) in an en face view and to determine the potential error of conventional VCW measurement on estimation of EROA. Methods: RT3DE was performed in 57 patients with relevant MR of different etiologies. Manual tracing of VCA in a cross-sectional plane through the vena contracta was compared with VCW in 4CH and 2CH views. As a comparative approach to VCA-3D, EROA was calculated using the hemispheric and hemielliptic proximal isovelocity surface ( PISA) area method. Results: Direct measurement of VCA-3D was feasible in all patients within 2.6 +/- 0.7 minutes. RT3DE revealed significant asymmetry of VCA in functional compared with organic MR ( P <.001). Among all patients, VCW-4CH and VCW-2CH correlated only moderately to VCA-3D ( r =.77; r =.80). Mean VCW correlated and agreed best with VCA-3D ( r =.90). VCA-3D correlated and agreed well with EROA by hemielliptic PISA ( r =.96, mean error: -0.09 +/- 0.14 cm(2)) compared with significant underestimation of hemispheric PISA in noncircular lesions. Conclusions: Direct assessment of VCA using RT3DE revealed significant asymmetry of VCA in functional MR compared with organic MR, resulting in poor estimation of EROA by single VCW measurements.