Hydrodynamic thrust bearings for rotary blood pumps

A rotary blood pump comprising:

• a pumping chamber having an interior wall;
• a rotatable impeller within said pumping chamber, said impeller having a plurality of sectors, adjacent sectors adjoining a blood flow path therebetween;
• each of said sectors having a peripheral surface spaced by a gap from a portion of said interior wall of said pumping chamber when said impeller is rotating;
• one or more of said peripheral surfaces of said impeller having a first inclined tapered region for capturing blood flow and a second oppositely inclined tapered region for ejecting blood flow, said first and second tapered regions being in tandem fluid flow communication across a flat bridging surface area therebetween, the taper depth of each of said tapered regions varying along its length in the direction of rotation of said impeller, each of said first and second tapered regions having a leading end and a trailing end, the leading end of said first tapered region being substantially perpendicular to the trailing end of said second tapered region, the taper depth of said first tapered region increasing hydrodynamic pressure on blood in said gap acting axially on said impeller when said impeller rotates, the taper depth of said second tapered region relieving hydrodynamic pressure on blood in said gap when said impeller rotates.