Effect of surface roughness on hemolysis in a centrifugal blood pump.

Surface roughness of a blood pump is an important factor for blood cell damage. This study investigated the effect of surface roughness pertaining to hemolysis in a centrifugal pump. In vitro hemolysis tests were performed under cardiopulmonary bypass (CPB; 5 L/min, 350 mmHg) and left ventricular assist device (LVAD; 5 L/min, 100 mmHg) conditions using the pivot bearing supported Gyro centrifugal pump (C1E3). Seven types of pumps with impellers and housings with different surface roughness were prepared as follows: vapor polish (VP) housing and VP impeller; VP housing and sandpaper (SP) impeller; VP housing and fine sandblasting (FSB) impeller; VP housing and coarse sandblasting (CSB) impeller; SP housing and VP impeller; FSB housing and VP impeller; and CSB housing and VP impeller. The results revealed that 1) the effect of surface roughness on hemolysis was significantly larger with CPB than LVAD; 2) surface roughness, regardless of the impeller or housing, had little effect on hemolysis with LVAD; and 3) during CPB, the surface roughness of the pump housing had a larger effect on hemolysis than did that of the impeller. In conclusion, from a hemolytic point of view, it is likely that an extremely smooth pump housing is required for an impeller centrifugal pump for CPB. However, it is likely that a smooth surface is not as essential for this impeller centrifugal pump as for an LVAD.