Abstract: A centrifugal blood pump has a face seal between a pump housing wall and a hub of an impeller which provides upon assembly a gas permeable seal at a seal interface surrounding a shaft defining the rotational axis of the impeller. This seal separates a blood pumping chamber from a separate chamber housing lubricants and bearings for impeller rotation. Prior to rotation of the impeller, the blood pump is sterilized by exposure to ethylene oxide gas which passes through the gas permeable seal interface to also sterilize the interior of the bearing chamber in the pump. Upon rotation of the impeller, the seal interface, which is perpendicular to the axis, is converted to a gas and liquid impermeable seal.

Abstract: A centrifugal blood pump has a tapered seal between a pump housing wall and a hub of an impeller which provides a fluid tight seal interface surrounding a drive shaft which is connected to the impeller and which extends through the pump housing wall. The tapered seal has a maximum radial dimension adjacent to the wall and a minimum radial dimension adjacent the hub so that air bubbles (which seek the smallest shaft diameter) will not insulate the seal interface edges from fluid flow. The seal interface, which is perpendicular to the drive shaft axis, is located in a high flow area between the wall and the hub to increase cooling effects.

Abstract: A centrifugal blood pump has an impeller with a hub, a blade support ring and alternating long and short blades. A tapered seal between a pump housing wall and a hub of an impeller which provides a fluid tight seal interface surrounding a shaft. The long blades of the impeller have rear edges which are closer to the wall than is the seal interface and inner edges which extend from the rear edges to the hub. This provides high flow in the vicinity of the seal interface to enhance heat dissipation from the seal interface.