Shandas R, Kwon J
Dept. of Cardiology, Children's Hospital, Denver, CO 80218, USA.
Biomed Sci Instrum. 1996;32:161-7.
Although velocity profiles downstream of mechanical valves have been measured in-vitro using Laser Doppler Anemometry (LDA), these studies have not measured velocities in the immediate proximity of the leaflets since the LDA technique prevents velocities from being measured in the immediate vicinity of any structure. Laser based Digital Particle Image Velocimetry (DPIV) is a new technique that allows for accurate measurement of an entire two-dimensional velocity field with no beam angulation. DPIV was used to measure two-component velocity vectors immediately proximal and distal to a 25 mm bileaflet mechanical valve (St. Jude) mounted in a transparent steady flow in-vitro model. Measurements of flow similar in Reynolds number (Re) to mitral inflow (Re = 2000-4000) showed clear hemi-elliptical isovelocity convergence zones proximal to each of the three orifices. DPIV measurements of flow distal to the orifice revealed clear vortex rollups generated from the internal ring of the valve with separate velocity profiles immediately distal to the leaflets. These studies prove the feasibility of the DPIV technique to provide accurate velocity measurements of flow profiles through mechanical valves.
尽管已使用激光多普勒测速仪（LDA）在体外测量了机械瓣膜下游的速度分布，但由于LDA技术无法在任何结构的紧邻区域测量速度，这些研究并未测量瓣叶紧邻区域的速度。基于激光的数字粒子图像测速技术（DPIV）是一项新技术，它能够在无光束角度偏差的情况下精确测量整个二维速度场。DPIV被用于测量安装在透明稳定流体外模型中的25毫米双叶机械瓣膜（圣犹达）紧邻近端和远端的双分量速度矢量。对雷诺数（Re）与二尖瓣流入相似（Re = 2000 - 4000）的血流测量显示，在三个孔口近端均有清晰的半椭圆形等速收敛区。对孔口远端血流的DPIV测量显示，从瓣膜内环产生了清晰的涡旋卷起，在瓣叶紧邻远端有单独的速度分布。这些研究证明了DPIV技术用于精确测量通过机械瓣膜的血流剖面速度的可行性。
