US Patent 7189260 Ventricular assist system secondary impeller

In a centrifugal flow blood pump, usable in left ventricular assist applications, blood is pumped from an inlet (16) to an outlet (22) by a primary impeller (18). A portion of the blood that enters the pump follows a secondary channel (24) where a secondary impeller (70) routes the blood to lubricate a bearing between an impeller assembly (14) and a post formed by a component of the pump housing. The unique shape of the secondary impeller (70) prevents blood stagnation and provides for a well-washed fluid bearing.