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.