Baldwin J T, Tarbell J M, Deutsch S, Geselowitz D B
Department of Chemical Engineering, Pennsylvania State University Park, 16802.
ASAIO Trans. 1989 Jul-Sep;35(3):429-33. doi: 10.1097/00002480-198907000-00083.
A laser Doppler anemometry system was used to measure fluid velocities at 127 locations within a plexiglas model of the 70 cm3 Penn State electric ventricular assist device (VAD) fitted with Bjork-Shiley convexo-concave tilting disk valves. The velocity measurements were made using a seeded blood analog fluid that matched the kinematic viscosity of blood and the refractive index of plexiglas. At each location, 250 instantaneous velocity realizations were collected at eight instances during the pump cycle. The data were filtered and averaged to calculate mean (ensemble averaged) velocities. The results indicate that the largest mean velocities are created during systole in the VADs outlet tract, and during diastole in the major orifice of the mitral valve. A single vortex centered roughly about the axis of the cylindrical portion of the pump is created during early diastole. This vortex, which persists into early systole, provides good washing of the VAD walls. However, it does appear to impede the flow entering the VAD through the minor orifice of the mitral valve. High velocities also occur during diastole along the minor orifice wall of the outlet tract and are directed into the chamber. These retrograde velocities suggest the presence of a regurgitant jet near the wall of the prosthetic valve.
使用激光多普勒风速仪系统，在配有 Bjork - Shiley 凸凹倾斜盘式瓣膜的 70 cm³ 宾夕法尼亚州立大学电动心室辅助装置（VAD）的有机玻璃模型内的 127 个位置测量流体速度。使用一种种子血液模拟流体进行速度测量，该流体与血液的运动粘度和有机玻璃的折射率相匹配。在每个位置，在泵循环的八个时刻收集 250 个瞬时速度数据。对数据进行滤波和平均以计算平均（总体平均）速度。结果表明，最大平均速度出现在 VAD 出口通道的收缩期以及二尖瓣大孔的舒张期。在舒张早期形成一个大致以泵圆柱形部分轴线为中心的单个涡流。这个持续到收缩早期的涡流对 VAD 壁有良好的冲洗作用。然而，它似乎确实阻碍了通过二尖瓣小孔进入 VAD 的血流。在舒张期，出口通道小孔壁沿线也会出现高速血流，并指向腔室。这些逆行速度表明在人工瓣膜壁附近存在反流射流。
