Rotary blood pump

Abstract

A rotary blood pump comprises a housing and a rotor. The housing includes a blood inlet, a blood outlet, a blood flow conduit disposed between the blood inlet and the blood outlet, and a rotary bearing assembly disposed within and fixed to the housing. The rotor is rotatably disposed within the housing and includes one or more impellor blades disposed within the blood flow conduit for pumping blood through the conduit, and a shaft affixed to and rotating with the rotor. The shaft rotatably engages the bearing assembly to define an intersection between the rotor and the housing and to provide relative rotation between the rotor and the housing. In addition, the shaft further defines an axis of rotation for the rotor. In the rotary pump of the invention, at least one of the rotor and the housing defines a swirl region proximate to the intersection between the rotor and the housing. The swirl region includes a curved surface adapted to cause blood being pumped through the blood flow conduit to swirl about an axis that is transverse to and spaced apart from the axis of rotation of the rotor. This swirl washes the intersection between the housing and the rotor, and further provides blood flow in a region that would otherwise have low flow.

What is claimed is:  
     
         1 . A rotary blood pump, comprising: 
 a housing having: 
 a blood inlet;  
 a blood outlet;  
 a blood flow conduit disposed between the blood inlet and the blood outlet; and  
 a rotary bearing assembly disposed within and fixed to the housing; and  
   a rotor rotatably disposed within the housing, the rotor including: 
 one or more impellor blades disposed within the blood flow conduit, the one or more impellor blades adapted to pump blood through the blood flow conduit; and  
 a shaft affixed to and rotating with the rotor, the shaft rotatably engaged with the bearing assembly to define an intersection between the rotor and the housing and to provide relative rotation between the rotor and the housing, the shaft further defining an axis of rotation for the rotor;  
   wherein at least one of the rotor and the housing defines a swirl region proximate to the intersection between the rotor and the housing, the swirl region including a curved surface adapted to cause blood being pumped through the blood flow conduit to swirl about an axis that is transverse to and spaced apart from the axis of rotation of the rotor.    
     
     
         2 . The rotary blood pump of  claim 1 , wherein the swirl region is defined on a superior end by an inferior portion of the rotor and the swirl region is defined on an inferior end by the housing, the swirl region adapted to pump blood away from the axis of rotation of the rotor on the superior end and to pump blood toward the axis of rotation of the rotor on the inferior end.  
     
     
         3 . The rotary blood pump of  claim 1 , wherein the rotor includes a thick central region extending along the axis of rotation of the rotor and mated to the shaft, the thick central region having a thickness predetermined to fill a low flow region extending outward from the axis of rotation.  
     
     
         4 . The rotary blood pump of  claim 3 , wherein the thick central region defines at least a portion of the swirl region.  
     
     
         5 . The rotary blood pump of  claim 1 , wherein the impellor section is adapted to pump blood into the swirl region.  
     
     
         6 . The rotary blood pump of  claim 5 , wherein the impellor section comprises a central hub located on the axis of rotation of the rotor and a plurality of impellor blades extending outwardly from the central hub, the impellor blades being separated by channels that allow blood to flow through the rotor in a direction along the axis of rotation of the rotor.  
     
     
         7 . The rotary blood pump of  claim 6 , wherein the impellor blades have a cross-sectional shape proximate to the central hub adapted to encourage blood to flow in a direction parallel to the axis of rotation of the rotor into the swirl region.  
     
     
         8 . The rotary blood pump of  claim 7 , wherein the blood inlet is disposed proximate to the axis of rotation of the rotor and is angled so as to direct blood flowing into the rotary pump in a direction parallel to the axis of rotation of the rotor, the cross-sectional shape of the impellor blades proximate to the central hub configured to encourage blood flow in the direction parallel to the axis of rotation of the rotor and into the swirl region.  
     
     
         9 . The rotary blood pump of  claim 8 , wherein portions of the impellor blades proximate to the central hub are tilted to match a velocity of blood flowing from the blood inlet to the rotor.  
     
     
         10 . The rotary blood pump of  claim 1 , wherein a cross-sectional flow area through an intermediate portion of the blood flow conduit is smaller than a cross-sectional flow area of the blood inlet.  
     
     
         11 . The rotary blood pump of  claim 10 , wherein the cross-sectional flow areas through the intermediate portion of the blood flow conduit and blood inlet are sized so that for a nominal blood flow of approximately 5 liters per minute through the rotary blood pump, flow velocity of blood through the intermediate portion of the blood flow conduit is approximately 2 meters per second.  
     
     
         12 . The rotary pump of  claim 1 , wherein a gap is defined between the rotor and the housing, the gap having opening into the blood flow conduit.  
     
     
         13 . The rotary pump of  claim 12 , wherein the opening of the gap is located in a region of the blood flow conduit having high flow.  
     
     
         14 . The rotary pump of  claim 13 , wherein the opening of the gap is located in the swirl region.  
     
     
         15 . The rotary pump of  claim 13 , wherein a distance across the gap is approximately 25 microns.  
     
     
         16 . The rotary pump of  claim 12 , wherein the gap is configured proximate to its opening to extend in a direction transverse to the axis of rotation of the rotor.  
     
     
         17 . The rotary pump of  claim 16 , wherein the bearing assembly includes a magnetic thrust bearing.  
     
     
         18 . The rotary pump of  claim 16 , wherein opposed surfaces of the rotor and housing which define the gap in the region where the gap extends in a direction transverse to the axis of rotation of the rotor are configured to provide a hydrodynamic thrust bearing.  
     
     
         19 . The rotary pump of  claim 18 , wherein at least one of the opposed surfaces of the rotor and housing which define the gap is machined to have a wedge-shape to provide hydrodynamic thrust forces.  
     
     
         20 . A rotary flow blood pump, comprising: 
 a housing having: 
 a blood inlet;  
 a blood outlet; and  
 a blood flow conduit disposed between the blood inlet and the blood outlet; and  
   a rotor rotatable about a rotor axis of rotation disposed within the housing, the rotor including: 
 a central hub; and  
 one or more impellor blades disposed within the blood flow conduit, the one or more impellor blades extending outward from the central hub, being separated by channels that allow blood to flow through the rotor, and being adapted to pump blood through the blood flow conduit;  
   wherein at least a portion of the impellor blades proximate the central hub are configured to encourage blood flow through the rotor.    
     
     
         21 . The rotary blood pump of  claim 20 , wherein the rotor impellor blades have a cross-sectional shape proximate to the central hub adapted to encourage blood to flow in a direction parallel to the axis of rotation of the rotor.  
     
     
         22 . The rotary blood pump of  claim 21 , wherein the blood inlet is disposed proximate to the axis of rotation of the rotor and is angled so as to direct blood flowing into the rotary pump in a direction parallel to the axis of rotation of the rotor, the cross-sectional shape of the impellor blades proximate to the central hub configured to encourage blood flowing toward the rotor from the blood inlet in the direction parallel to the axis of rotation of the rotor.  
     
     
         23 . The rotary blood pump of  claim 22 , wherein portions of the impellor blades proximate to the central hub are tilted to match a velocity of blood flowing from the blood inlet to the rotor.  
     
     
         24 . The rotary blood pump of  claim 20 , wherein: 
 the housing further comprises a rotary bearing assembly disposed within and fixed to the housing; and    the rotor further comprises a shaft affixed to and rotating with the rotor, the shaft rotatably engaged with the bearing assembly to define an intersection between the rotor and the housing and to provide relative rotation between the rotor and the housing, the shaft extending along the axis of rotation for the rotor;    wherein at least one of the rotor and the housing defines a swirl region proximate to the intersection between the rotor and the housing, the swirl region including a curved surface adapted to cause blood being pumped through the blood flow conduit to swirl about an axis that is transverse to and spaced apart from an axis of rotation of the rotor.    
     
     
         25 . The rotary blood pump of  claim 24 , wherein the swirl region is defined on a superior end by an inferior portion of the rotor and the swirl region is defined on an inferior end by the housing, the swirl region adapted to pump blood away from the axis of rotation of the rotor on the superior end and to pump blood toward the axis of rotation of the rotor on the inferior end.  
     
     
         26 . The rotary blood pump of  claim 24 , wherein the rotor includes a thick central region extending along the axis of rotation of the rotor and mated to the shaft, the thick central region having a thickness predetermined to fill a low flow region extending outward from the axis of rotation.  
     
     
         27 . The rotary blood pump of  claim 26 , wherein the thick central region defines at least a portion of the swirl region.  
     
     
         28 . The rotary blood pump of  claim 24 , wherein the impellor section is adapted to pump blood into the swirl region.  
     
     
         29 . The rotary blood pump of  claim 20 , wherein a cross-sectional flow area through an intermediate portion of the blood flow conduit is smaller than a cross-sectional flow area of the blood inlet.  
     
     
         30 . The rotary blood pump of  claim 29 , wherein the cross-sectional flow areas through the intermediate portion of the blood flow conduit and blood inlet are sized so that for a nominal blood flow of approximately 5 liters per minute through the rotary blood pump, flow velocity of blood through the intermediate portion of the blood flow conduit is approximately 2 meters per second.  
     
     
         31 . A rotary flow blood pump, comprising: 
 a housing having: 
 a blood inlet;  
 a blood outlet; and  
 a blood flow conduit disposed between the blood inlet and the blood outlet; and  
   a rotor rotatable about a rotor axis of rotation disposed within the housing, the rotor including one or more impellor blades disposed within the blood flow conduit and being adapted to pump blood through the blood flow conduit;    wherein a cross-sectional flow area through an intermediate portion of the blood flow conduit is smaller than a cross-sectional flow area of the blood inlet.    
     
     
         32 . The rotary blood pump of  claim 32 , wherein the cross-sectional flow areas through the intermediate portion of the blood flow conduit and blood inlet are sized so that for a nominal blood flow of approximately 5 liters per minute through the rotary blood pump, flow velocity of blood through the intermediate portion of the blood flow conduit is approximately 2 meters per second.