Title: ENDURANCE PERFORMANCE OF GYRO CENTRIFUGAL BLOOD PUMP
Abstract: Purpose: Our group is developing a double-pivot bearing centrifugal pump for long-term ventricular assistance. Previous studies have estimated bearing life at 5 years for LVAD and 8 years for RVAD. Endurance testing for 1-year demonstrated that top female bearing wear was 3 times greater for LVAD than RVAD. Top bearing is critical because pump impeller is maintained at top contact position during operation. To improve bearing life, the top female bearing radius was increased, and magnet coupling force was increased. We report endurance test results of modified double-pivot bearing centrifugal pump. Methods: Eight Gyro pumps are being operated in LVAD mode. Test stations consist of mock ventricle, arterial compliance, arterial resistor, and atrial chamber. Pumps are operated at 5 L/min at peak outflow pressure of 100 mmHg. Mock ventricles are operated at 78 beats/min with stoke volume of ∼30 ml/beat. Pump fluid is normal saline at 37oC. Results: As of January 14, 2005, pumps have accumulated test periods of 331(n=4), 322 (n=1), 313 (n=1), 212 (n=1), and 73 days (n=1). Measured pump flows are 5.03 + 0.06 L/min at mean outflow pressure of 93 + 3 mmHg and mean filling pressure of 26 + 5 mmHg. Pump speed averaged 1810 + 50 RPM with power consumption of 0.29 + 0.03 amps and a system efficiency of 19.2 + 1.7%. There have been no pump/actuator malfunctions without noticeable vibration or noise. Conclusion: Eight centrifugal pumps have 6.1 cumulative years of in vitro testing without failure. Studies will be continued for another year to validate 2-year endurance of double-pivot bearing Gyro centrifugal blood pump.