The Characteristics of a Spiral Blood Pump

From 1997 to 1999, we developed a spiral blood pump. The spiral pump consists of a brushless DC motor, the pump housing, a magnetic-fluid seal, bearings and a spiral impeller. The maximum diameter of the impeller is 21.8 mm and minimum is 9.8 mm, the cone angle of the impeller threads is 41.8 degrees. The housing has a maximum diameter of 30 mm. The pump was made from Titanium alloy, the total volume of pump housing and motor was 76 ml and its weight 220g. Methods used: The hydrodynamic performance of the spiral pump was examined from 8 000 to 10 000rpm rotation speeds in a closed circuit loop. This circuit consists of a reservoir, a clamp, two pressure transducers, an electric-magnetic flow rate transducer and glycerin-water solution. The damage test to blood was studied in a smaller circuit loop, that used fresh sheep blood and polyvinyl chloride bag instead of the glycerin-water solution and the reservoir. In this test, the damage of the spiral pump was compared with an axial flow blood pump. Furthermore the simulated condition was 5.0 L/ min flow rate and 100 mmHg pressure. Summarize Results: 1. The flow rate was 4.0 L/min against 120 mmHg pressure when pump rotated 10000 rpm. So the hydrodynamic performance of the spiral blood pump was enough to meet a patient’s need when the blood pump was used as a left ventricular assistant device. 2. The NIH results of three gaps were 0.074±0.022g/100L,0.086±.026g/100L and 0.111±0.034g/100L(n=40) respectively. The best hemolysis result was been at the gap of 0.14 mm. 3. The NIH result of the spiral pump with 0.40gap was 0.111±0.034g/100L, n=40; and the axial flow pump was 0.131±0.030g/100L, n=40 respectively; The mean fibrinogen decreases of two pumps between half of an hour were 4.281±2.098mg/100L and 9.625±5.630mg/100L(n=40). So we can conclude that the damage of the spiral pump to blood was less than the axial flow pump. (P<0.05).