EVALUATING HEAT GENERATION AT PIVOT BEARING OF THE GYRO C1E3

Abstract

Excessive heat generation above 50°C is considered critical for blood pumps because temperature causes aggregation of the heat-denatured fibrinogen and may lead to complications. The Gyro C1E3 is a centrifugal blood pump for CPB and long-term cardiac assist. This pump has pivot bearings inside the housing to suspend the impeller. Therefore, it is important to evaluate heat generation from these bearings. The heat distribution inside the C1E3 was simulated 3 dimensionally by computed heat flow analysis. The elements and nodes for the analysis were 2.67 ± 105 and 3.27 ± 105, respectively. The highest temperature was 41°C at the top female bearing surface. Then the temperature of the top female bearing was directly measured during pumping. The pump was driven in a mock circuit for 7 days at 3000 RPM to generate 5 L/min flow. The fluid temperature in the circuit was maintained at 37°C. A platinum thermocouple was inserted inside the bearing to continuously measure the temperature. The measurement was repeated at the center, 0.71 mm offset and 1.5mm offset from the center of die bearing. The temperature increased from 28±32°C to 32±34°C in 2 minutes and plateaued approximately 30 minutes after pumping. The 0.71 mm offset position exhibited the highest temperature at 34.3°C. This position is in the shaft attached area and substantiates the computed heat flow analysis. The pivot bearings of the C1E3 do not generate excessive heat and substantially avoid heat-related complications.