AN IMPROVED FLOW EVALUATION SCHEME IN ORIFICES OF DIFFERENT ASPECT RATIOS

An accurate and reliable method of regurgitant flow calculation is cur rently unavailable, The goal of this study was to define a new general method of flow calculation for orifices of different aspect ratios, T he success of the method relies on matching the imaged flow field dist ribution obtained by color flow mapping (CFM) to a three-dimensional ( 3D) numerical how field distribution of known geometry, The flow field in three orifices of identical cross-sectional area with aspect ratio s of 1 (circular), 2 and 4 (elliptical) was evaluated by: (a) CFM, (b) 3D echocardiographic imaging, and (c) 3D finite element modeling (FEM ), The orifice shape and size were accurately estimated by 3D echocard iographic imaging, FEM showed that the normalized centerline velocity profile of the flow field depends on the orifice aspect ratio, CFM pro vided a good description of the centerline profile for each case, For a given distance from the orifice center, the equivelocity contour sur face area increases with increasing aspect ratio, A simple flow calcul ation scheme was developed to calculate regurgitant flow independent o f orifice shape, This improved method showed better results than previ ous studies and may prove to be advantageous when analyzing in vivo fl ow fields with complex geometries. (C) 1997 World Federation for Ultra sound in Medicine & Biology.