Quantitation of valvular regurgitation remains an important goal in clinical cardiology. It has been described previously that with the use of color Doppler flow mapping, simple measurements of apparent jet size do not correlate closely with quantitative regurgitant indices. Recently the proximal flow convergence method has been proposed to quantify valvular regurgitation by analysis of the converging flow field proximal to a regurgitant lesion. Assuming hemispherical convergence, flow rate Q can be calculated as Q = 2πr2va, where va is the aliasing velocity at a distance r from the orifice. For maximal accuracy, previously validated correction factors must be used to account for the flattening effect of the isovelocity contours close to the orifice and for the actual sector angle subtended by the valve leaflets (α), to yield a flow rate formula Q = 2πr2va · ( vp vp - va) · ( α 180), where vp is the orifice velocity obtained by continuous wave Doppler. In 45 patients (35 in sinus rhythm, 10 with atrial fibrillation) with tricuspid regurgitation, regurgitant stroke volume, regurgitant flow rate, and regurgitant fraction were calculated using the proximal flow convergence method and were compared with values obtained by the Doppler two-dimensional echocardiographic method. Regurgitant stroke volumes (SV) calculated by the proximal flow convergence method correlated very closely with values obtained by the Doppler two-dimensional method with r = 0.95 (y = 0.94x + 0.99) and ΔSV = -0.3 ± 5.2 cm3. Regurgitant flow rates (Q) calculated by both methods showed a similar correlation: r = 0.96 (y = 0.97x + 45) and ΔQ = 1.6 ± 429 cm3/min. The correlation for regurgitant fraction (RF) calculated by both techniques was r = 0.90 (y = 1.07x - 0.02) and ΔRF = -0.002 ± 0.008. All correlations were slightly better for the group of patients in sinus rhythm than for the group in atrial fibrillation. This study demonstrates that the proximal flow convergence method is an accurate and reproducible technique for quantifying tricuspid regurgitation. This approach is easier and less time-consuming than the Doppler two-dimensional method. While improvements of this method are to be expected, flow calculations based on the proximal flow field show excellent results and appear appropriate for clinical use.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine