Hasenkam J M, Nygaard H, Pedersen E M, Ostergaard J H, Paulsen P K, Johannsen G
Department of Thoracic and Cardiovascular Surgery, Skejby Sygehus, Aarhus University Hospital, Denmark.
J Card Surg. 1989 Mar;4(1):74-8. doi: 10.1111/j.1540-8191.1989.tb00259.x.
Because late valve-related complications such as hemolysis and thromboembolic events are considered related to flow disturbances caused by the inserted valve, velocity fields downstream of aortic valve prostheses were studied in pigs. Acute hemodynamic evaluation of size 25-mm porcine and pericardial aortic valve prostheses 1 diameter downstream of the valve ring was performed using dynamic three-dimensional visualization of velocity profiles and spatial distribution of turbulence. Point blood velocity signals obtained with a 1-mm hot-film anemometer needle probe were used to compute Reynolds normal stresses (RNS) by calculation of the turbulent velocity energy of the axial velocity component in the systole. The porcine valves caused a skewed velocity and turbulence profile revealing mean spatial systolic RNS at 70 nm-2 +/- 35 nm-2 (+/- SD). The spatial maximum RNS was 275 +/- 139 nm-2. Corresponding values for the pericardial valves were 20 +/- 11 nm-2 and 72 +/- 46 nm-2. The pericardial valves revealed plug-shaped velocity profiles and turbulent profiles with slightly higher RNS values at the stent posts. From a hemodynamic point of view, these acute studies indicate superiority of the pericardial valves compared to the porcine valves. The turbulent stresses found in this study are of a magnitude that may cause blood corpuscular and endothelial damage.
由于诸如溶血和血栓栓塞事件等晚期瓣膜相关并发症被认为与植入瓣膜引起的血流紊乱有关，因此对猪主动脉瓣假体下游的速度场进行了研究。使用速度剖面和湍流空间分布的动态三维可视化技术，对瓣膜环下游1个直径的25毫米猪心包主动脉瓣假体进行了急性血流动力学评估。用1毫米热膜风速计针式探头获得的点血流速度信号，通过计算收缩期轴向速度分量的湍流速度能量来计算雷诺正应力（RNS）。猪瓣膜导致速度和湍流剖面呈偏态，显示平均空间收缩期RNS为70nm-2±35nm-2（±标准差）。空间最大RNS为275±139nm-2。心包瓣膜的相应值分别为20±11nm-2和72±46nm-2。心包瓣膜显示出塞状速度剖面和湍流剖面，在支架柱处的RNS值略高。从血流动力学角度来看，这些急性研究表明心包瓣膜优于猪瓣膜。本研究中发现的湍流应力大小可能会导致血细胞和内皮损伤。
