Nygaard H, Hasenkam J M, Pedersen E M, Kim W Y, Paulsen P K
Department of Thoracic and Cardiovascular Surgery, Skejby Sygehus, Aarhus University Hospital, Denmark.
Med Biol Eng Comput. 1994 Jan;32(1):55-62. doi: 10.1007/BF02512479.
A pulsed Doppler ultrasound (PDU) multi-element system was developed for perivascular registration of velocity fields and turbulence in large vessels. In vivo evaluation and comparison with hot-film anemometry (HFA) was performed. C-shaped shells were designed with holes to fit five small 10 MHz ultrasonic probes directed at five measuring points along a diameter perpendicular to the vessel axis. By rotating the shell in 45 degrees steps, blood velocities were measured in 17 points covering the entire cross-sectional vessel area. Measurements were performed in the ascending aorta and at three axial locations in the descending thoracic aorta in pigs. Simultaneous PDU and HFA measurements were performed distal to induced vascular stenoses of different degrees. Three-dimensional visualisation of velocity profiles was made, and Reynolds normal stresses (RNS) were calculated for different levels of turbulence intensities based on the simultaneous PDU and HFA measurements. The velocity profiles in the ascending aorta were skewed at top systole with the highest velocities towards the posterior wall. In the descending thoracic aorta at the ligmentum of Botalli, the velocity profiles were skewed throughout the entire systole with the highest velocities at the right anterior vessel wall. Further downstream in the descending aorta the velocity profiles appeared blunter. The frequency response of the modified PDU system was determined by a 'random noise test' revealing an upper -3dB cut-off frequency of approximately 200 Hz. Regression analysis showed a linear relationship between RNS measured with PDU and RNS measured with HFA (r = 0.93). Two vessel diameters distal to a 75% stenosis RNS up to 28 N m-2 were measured.(ABSTRACT TRUNCATED AT 250 WORDS)
开发了一种脉冲多普勒超声（PDU）多元素系统，用于大血管周围速度场和湍流的记录。进行了体内评估并与热膜风速仪（HFA）进行了比较。设计了带有孔的C形外壳，以适配五个小型10 MHz超声探头，这些探头沿着垂直于血管轴的直径指向五个测量点。通过以45度步长旋转外壳，在覆盖整个血管横截面积的17个点上测量了血流速度。在猪的升主动脉和降主动脉胸段的三个轴向位置进行了测量。在不同程度的诱导血管狭窄远端同时进行了PDU和HFA测量。绘制了速度剖面的三维可视化图，并基于同时进行的PDU和HFA测量，针对不同水平的湍流强度计算了雷诺法向应力（RNS）。升主动脉在收缩期末期速度剖面呈偏态，后壁速度最高。在博塔利韧带处的降主动脉胸段，整个收缩期速度剖面均呈偏态，右前血管壁速度最高。在降主动脉更远端，速度剖面显得更钝。通过“随机噪声测试”确定了改进后的PDU系统的频率响应，显示-3dB截止频率上限约为200 Hz。回归分析表明，PDU测量的RNS与HFA测量的RNS之间存在线性关系（r = 0.93）。在75%狭窄远端两个血管直径处，测量到RNS高达28 N m-2。（摘要截短于250字）
