Departments of Bioengineering & Surgery, Cardiovascular Innovation Institute, University of Louisville, Louisville, KY 40202, USA.
Med Eng Phys. 2011 Dec;33(10):1193-202. doi: 10.1016/j.medengphy.2011.05.008. Epub 2011 Jun 15.
Historically, single port valveless pneumatic blood pumps have had a high incidence of thrombus formation due to areas of blood stagnation and hemolysis due to areas of high shear stress.
To ensure minimal hemolysis and favorable blood washing characteristics, particle image velocimetry (PIV) and computational fluid dynamics (CFD) were used to evaluate the design of a new single port, valveless counterpulsation device (Symphony). The Symphony design was tested in 6-h acute (n=8), 5-day (n=8) and 30-day (n=2) chronic experiments in a calf model (Jersey, 76 kg). Venous blood samples were collected during acute (hourly) and chronic (weekly) time courses to analyze for temporal changes in biochemical markers and quantify plasma free hemoglobin. At the end of the study, animals were euthanized and the Symphony and end-organs (brain, liver, kidney, lungs, heart, and spleen) were examined for thrombus formations.
Both the PIV and the CFD showed the development of a strong moving vortex during filling phase and that blood exited the Symphony uniformly from all areas during ejection phase. The laminar shear stresses estimated by CFD remained well below the hemolysis threshold of 400 Pa inside the Symphony throughout filling and ejection phases. No areas of persistent blood stagnation or flow separation were observed. The maximum plasma free hemoglobin (<10mg/dl), average platelet count (pre-implant = 473 ± 56 K/μl and post-implant = 331 ± 62 K/μl), and average hematocrit (pre-implant = 31 ± 2% and post-implant = 29 ± 2%) were normal at all measured time-points for each test animal in acute and chronic experiments. There were no changes in measures of hepatic function (ALP, ALT) or renal function (creatinine) from pre-Symphony implantation values. The necropsy examination showed no signs of thrombus formation in the Symphony or end organs.
These data suggest that the designed Symphony has good washing characteristics without persistent areas of blood stagnation sites during the entire pump cycle, and has a low risk of hemolysis and thrombus formations.
由于血液停滞和高剪切应力区域的溶血，历史上，单端口无阀气动血泵血栓形成的发生率很高。
为了确保最小的溶血和良好的血液清洗特性，使用粒子图像测速（PIV）和计算流体动力学（CFD）来评估新的单端口、无阀反搏装置（交响乐）的设计。交响乐设计在小牛模型（泽西，76 公斤）中进行了 6 小时急性（n=8）、5 天（n=8）和 30 天（n=2）慢性实验测试。在急性（每小时）和慢性（每周）时间过程中收集静脉血样，以分析生化标志物的时间变化，并定量血浆游离血红蛋白。研究结束时，处死动物，检查交响乐和终末器官（脑、肝、肾、肺、心和脾）是否有血栓形成。
PIV 和 CFD 均显示，在填充阶段形成了一个强大的移动涡，并且在喷射阶段血液从交响乐的所有区域均匀地流出。CFD 估计的层流剪切应力在整个填充和喷射阶段都保持在交响乐内溶血阈值 400Pa 以下。未观察到持续的血液停滞或流动分离区域。最大血浆游离血红蛋白（<10mg/dl）、平均血小板计数（植入前=473±56K/μl 和植入后=331±62K/μl）和平均红细胞压积（植入前=31±2%和植入后=29±2%）在急性和慢性实验的每个测试动物的所有测量时间点均正常。与植入前相比，肝肾功能（碱性磷酸酶、丙氨酸氨基转移酶）或肾功能（肌酐）均无变化。尸检检查显示交响乐或终末器官内无血栓形成迹象。
这些数据表明，设计的交响乐在整个泵循环过程中具有良好的清洗特性，没有持续的血液停滞区域，并且溶血和血栓形成的风险较低。
