心尖轴流泵的结构和性能的比较

Comparative study of miniature apex axial flow blood pumps with different structures

目的:比较不同结构心尖轴流泵的流体力学及溶血特性差异。方法 :在体外模拟循环台上测试外形尺寸相似的4种不同结构的轴流泵(包括单滑动面球支点、双滑动面球支点心尖轴流泵及保留后导叶和无后导叶的全悬浮心尖轴流泵)的流体力学和溶血特性。结果:单滑动面球支点心尖轴流泵和双滑动面球支点心尖轴流泵的流体力学特性及溶血特性相似,均可在11 000 r/min条件下产生100 mm Hg(1 mm Hg=133.32 Pa)的压力输出和5 L/min的流量输出,标准溶血指数(normalized index of hemolysis,NIH)分别为0.023和0.025 g/100 L。在产生相同压力和流量输出条件下,两型全悬浮心尖轴流泵转速明显增加,保留后导叶的全悬浮心尖轴流泵和无后导叶的全悬浮心尖轴流泵转速分别为17 000和23 000 r/min,NIH分别为0.072和0.13 g/100 L。结论:单滑动面球支点心尖轴流泵结构简单、效率高、溶血强度低,可作为心尖轴流泵的结构选择;双滑动面球支点心尖轴流泵结构优势尚需在长时间体内植入实验中证实。悬浮心尖轴流泵体积较小,但效率较低,溶血作用强,保留后导叶可明显提高悬浮心尖轴流泵效率,降低溶血强度。

Objective To compare the hydrodynamics and hemolytic characteristics of four types of miniature apex axial flow pumps. Methods Four types of axial flow pumps with similar boundary dimensions were fabricated, including two axial flow pumps with mechanical contacting bearings and two suspending axial flow pumps. The mechanical contacting bearing was designed as pivot ball bearing with either double sliding surface or single sliding surface, while the suspending axial flow pumps were constructed as one with either a tail flow straighter or without it. The four prototypes of axial flow pumps were tested on a mock circle for the hydrodynamic and hemolytic characteristics. Results The two prototypes of axial flow pumps with mechanical contacting bearings were similar in performance, and both could yield a flow rate of5 L/min at 100 mmHg pressure with a rotating speed of 11 000 r/min. The normalized index of hemolysis（NIH） was0.025 g/100 L for the pump of pivot ball bearing with double sliding surface, and 0.023 g/100 L for that with single sliding surface. For producing same hydrodynamic output of 5 L/min at 100 mmHg pressure, the two prototypes of suspending axial flow pumps needed a much higher rotational speed, which reached 17 000 and 23 000 r/min for the suspending axial flow pump with or without a tail flow straighter respectively, correspondently the NIH reached 0.072 g/100 L for the former and 0.13 g/100 L for the latter, significantly higher than the axial flow pump with mechanical contact bearing.Conclusion The axial flow pump with pivot ball bearing has high efficiency and low NIH, suitable as an apex axial flow blood pump. The tail flow straighter is necessary for the suspending axial flow to achieve high hydrodynamic and hemolysis performance.