Real-time 3-dimensional volumetric ultrasound imaging of the vena contracta for stenotic valves with the use of echocardiographic contrast imaging: In vitro pulsatile flow studies

The purpose of our study was to investigate the utility of real-time 3-dime nsional volumetric ultrasound coupled with echo contrast imaging to visuali ze and quantify effective flow areas for stenotic valves in vitro. Real-tim e 3-dimensional ultrasound imaging has recently emerged as a promising meth od for increasing the quantitative accuracy of echocardiography. Since the technique currently does not process Doppler information, its use for quant ifying now has not been studied. However, the use of contrast agents to vis ualize cardiac flows with the use of echocardiography should allow determin ation of mass-dependent flow parameters such as effective now area (vena co ntracta area) for stenotic lesions. We used real-time S-dimensional imaging in an in vitro stenotic valve model (areas 0.785 to 1.767 cm(2)) under pul satile flow conditions (60 bpm; 40 to s0 mL/beat). An echo contrast agent w as used to visualize the distal jet. Real-time 3-dimensional imaging provid es simultaneous views of long-axis and short-axis (C-scan) image planes of the jet. The vena contracta was identified and measured by placing the C-sc an line immediately distal to the orifice and measuring the cross-sectional now area System gain and postprocessing curve shape affected 3-dimensional areas; minimal gain and a custom curve produced best agreement to actual v ena contracta areas measured with a previously validated laser method (y = 0.939x + 0.089; r = 0.98; standard error of estimate = 0.158 cm(2)). We con clude that real-time 3-dimensional ultrasound imaging coupled with a contra st agent can be used as an accurate yet simple clinical means of measuring effective now areas for stenotic valves.