Rotary Seal for Cantilevered Rotor Pump and Methods for Axial Flow Blood Pumping

Abstract

Blood pump devices having improved rotary seals for sealing a bearing assembly supporting a rotor provided herein. Such rotary seals are particularly suited for use in blood pump devices that include rotors having cantilevered supported through a sealed mechanical bearing disposed outside a blood flow path of the device to avoid thrombus formation caused by blood contact with the bearing. The rotary seal can include a first and second face seal that are preloaded with a deflectable compliance member incorporated into the pump housing or a pair of magnets. Such rotary seals can instead or further utilize tight fitment between components or a bio-absorbable fill material to seal an interface between the rotor shaft and pump housing to seal the bearing assembly from fluid flowing through the pump.

1 . (canceled) 
     
     
         2 . An implantable blood pump comprising:
 a pump housing defining a blood flow passage therethrough;   a rotor including a rotatable shaft that extends into the blood flow passage;   a mechanical, non-blood washed bearing assembly coupled with a first portion of the rotatable shaft so as to allow rotation of the rotor during operation of the pump; and   a rotary blood seal disposed at an interface of a first portion of the pump housing and the rotatable shaft, wherein the rotary blood seal comprises a first face seal component disposed on the rotatable rotor shaft and a second face seal component disposed on the first portion of the pump housing, the first and second face seal components being slidably engaged so as to allow rotation of the rotor shaft, wherein the first and second face seal components are configured to inhibit any leakage path therebetween thereby avoiding contact between the bearing assembly and any blood flowing through the blood flow passage during operation of the pump.   
     
     
         3 . The blood pump of  claim 2 , wherein the rotary blood seal assembly further comprises a precision fitment between the rotatable shaft and the pump housing. 
     
     
         4 . The blood pump of  claim 3 , wherein the precision fitment is between an outside diameter of the rotatable shaft and an inside diameter of the pump housing that is defined to prevent blood flow to the bearing assembly. 
     
     
         5 . The blood pump of  claim 4 , where the first face seal component interfaces with the second face seal component along a flat, precision polished surface to form a rotary seal that prevents passage of any blood flow therebetween. 
     
     
         6 . The blood pump of  claim 3 , wherein the first portion of the pump housing comprises a rear cover removably coupleable with a second portion of the pump housing. 
     
     
         7 . The blood pump of  claim 6 , wherein the precision fitment is between the rotatable shaft and a portion of the rear cover. 
     
     
         8 . The blood pump of  claim 7 , wherein the precision fitment is defined between a curved portion or a shoulder region of the rear cover that substantially conforms with a corresponding feature in the rotatable shaft. 
     
     
         9 . The blood pump of  claim 7 , wherein the precision fitment is defined between interfacing flat surfaces or interfacing contour surfaces. 
     
     
         10 . The blood pump of  claim 9 , wherein formation of thrombus along the interface prevents blood flow beyond the interface into the bearing assembly. 
     
     
         11 . The blood pump of  claim 2 , wherein the rotary blood seal assembly further includes a biologics seal to inhibit intrusion of blood between the first and second face seal components. 
     
     
         12 . The blood pump of  claim 11 , wherein the first portion of the pump housing is a rear cover removably coupleable with a second portion of the pump housing. 
     
     
         13 . The blood pump of  claim 12 , wherein the biologics seal comprises a bio-absorbable material that fills the interface between rotatable shaft and a portion of the rear cover to prevent blood flow to the bearing assembly. 
     
     
         14 . The blood pump of  claim 13 , wherein the bio-absorbable material initiates formation of a pseudo neointimal layer or plug between rotatable shaft and the rear cover. 
     
     
         15 . The blood pump of  claim 14 , wherein the pseudo neointimal layer or plug inhibits passage of blood between the first and second face seal components and is maintained by flow of blood through the blood flow passage of the implantable pump. 
     
     
         16 . The blood pump of  claim 11 , wherein the biologics seal comprises a titanium sintered or textured surface along the interface between the rotatable shaft and pump housing. 
     
     
         17 . The blood pump of  claim 16 , wherein the titanium sintered surface initiates formation of a pseudo neointimal layer or plug between rotatable shaft and the rear cover. 
     
     
         18 . The blood pump of  claim 17 , wherein the pseudo neointimal layer or plug inhibits passage of blood between the first and second face seal components and is maintained by flow of blood through the blood flow passage of the implantable pump. 
     
     
         19 . The blood pump of  claim 13 , wherein the blood pump is an axial flow pump or a centrifugal pump. 
     
     
         20 . An implantable blood pump comprising:
 a pump housing defining a blood flow passage therethrough;   a rotor including a rotatable shaft that extends into the blood flow passage;   a mechanical, non-blood washed bearing assembly coupled with a first portion of the rotatable shaft so as to allow rotation of the rotor during operation of the pump; and   a rotary blood seal disposed at an interface of a first portion of the pump housing and the rotatable shaft, wherein the rotary blood seal comprises a bushing seal having a precision manufactured silicon carbide disc with a through hole having an inside diameter that engages with an outside diameter of the rotatable shaft, the bushing seal configured to inhibit any leakage path therebetween thereby avoiding contact between the bearing assembly and any blood flowing through the blood flow passage during operation of the pump.   
     
     
         21 . The blood pump of  claim 20 , wherein the rotatable shaft comprises a precision manufactured silicon carbide shaft.