US20140322022A9 - Platinum-cobalt-boron blood pump element - Google Patents
Platinum-cobalt-boron blood pump element Download PDFInfo
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- US20140322022A9 US20140322022A9 US13/621,551 US201213621551A US2014322022A9 US 20140322022 A9 US20140322022 A9 US 20140322022A9 US 201213621551 A US201213621551 A US 201213621551A US 2014322022 A9 US2014322022 A9 US 2014322022A9
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- impeller
- cobalt
- rotatable impeller
- platinum
- alloy
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/02—Selection of particular materials
- F04D29/026—Selection of particular materials especially adapted for liquid pumps
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/18—Rotors
- F04D29/181—Axial flow rotors
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/10—Location thereof with respect to the patient's body
- A61M60/122—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body
- A61M60/165—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body implantable in, on, or around the heart
- A61M60/178—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body implantable in, on, or around the heart drawing blood from a ventricle and returning the blood to the arterial system via a cannula external to the ventricle, e.g. left or right ventricular assist devices
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/20—Type thereof
- A61M60/205—Non-positive displacement blood pumps
- A61M60/216—Non-positive displacement blood pumps including a rotating member acting on the blood, e.g. impeller
- A61M60/237—Non-positive displacement blood pumps including a rotating member acting on the blood, e.g. impeller the blood flow through the rotating member having mainly axial components, e.g. axial flow pumps
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/40—Details relating to driving
- A61M60/403—Details relating to driving for non-positive displacement blood pumps
- A61M60/422—Details relating to driving for non-positive displacement blood pumps the force acting on the blood contacting member being electromagnetic, e.g. using canned motor pumps
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/80—Constructional details other than related to driving
- A61M60/802—Constructional details other than related to driving of non-positive displacement blood pumps
- A61M60/804—Impellers
- A61M60/806—Vanes or blades
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/80—Constructional details other than related to driving
- A61M60/802—Constructional details other than related to driving of non-positive displacement blood pumps
- A61M60/81—Pump housings
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/80—Constructional details other than related to driving
- A61M60/802—Constructional details other than related to driving of non-positive displacement blood pumps
- A61M60/818—Bearings
- A61M60/824—Hydrodynamic or fluid film bearings
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/80—Constructional details other than related to driving
- A61M60/802—Constructional details other than related to driving of non-positive displacement blood pumps
- A61M60/818—Bearings
- A61M60/825—Contact bearings, e.g. ball-and-cup or pivot bearings
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M2205/00—General characteristics of the apparatus
- A61M2205/02—General characteristics of the apparatus characterised by a particular materials
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M60/00—Blood pumps; Devices for mechanical circulatory actuation; Balloon pumps for circulatory assistance
- A61M60/10—Location thereof with respect to the patient's body
- A61M60/122—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body
- A61M60/126—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body implantable via, into, inside, in line, branching on, or around a blood vessel
- A61M60/148—Implantable pumps or pumping devices, i.e. the blood being pumped inside the patient's body implantable via, into, inside, in line, branching on, or around a blood vessel in line with a blood vessel using resection or like techniques, e.g. permanent endovascular heart assist devices
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2300/00—Materials; Properties thereof
- F05D2300/10—Metals, alloys or intermetallic compounds
- F05D2300/11—Iron
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2300/00—Materials; Properties thereof
- F05D2300/10—Metals, alloys or intermetallic compounds
- F05D2300/14—Noble metals, i.e. Ag, Au, platinum group metals
- F05D2300/143—Platinum group metals, i.e. Os, Ir, Pt, Ru, Rh, Pd
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2300/00—Materials; Properties thereof
- F05D2300/10—Metals, alloys or intermetallic compounds
- F05D2300/17—Alloys
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
- F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- F05D2300/00—Materials; Properties thereof
- F05D2300/50—Intrinsic material properties or characteristics
- F05D2300/507—Magnetic properties
Definitions
- the present invention relates to an impeller comprising an alloy including effective amounts of platinum, cobalt, and boron for use in a blood pump such as a rotary Ventricular Assist Device (“VAD”).
- VAD rotary Ventricular Assist Device
- VADs Ventricular Assist Devices
- VADs may utilize a blood pump for imparting momentum to a patient's blood thereby driving the blood to a higher pressure.
- a rotary VAD is a blood pump containing an electromagnetically coupled impeller that spins to assist the patient's circulatory system.
- an improved blood pump impeller is provided for use in, for example, a rotary VAD. It has been found that an impeller comprising an alloy including predetermined amounts of platinum, cobalt, and boron results in an impeller that is highly effective and has superior magnetic, mechanical, and biocompatible properties. These superior properties make possible further miniaturization and streamlining of a VAD pump than has previously been impossible in the VAD industry.
- the magnetic impeller for a blood pump preferably comprises a magnetic alloy including platinum, cobalt, and boron. More preferably, the magnetic impeller comprises an alloy consisting essentially of about 12-14 atomic percent of boron, and platinum and cobalt in a platinum-to-cobalt atomic percent ratio of 0.90 to 1.2. Most preferably, the magnetic impeller comprises a magnetic alloy consisting essentially of about 13 atomic percent of boron, 42 atomic percent of platinum, and 45 atomic percent of cobalt.
- the ventricular assist device has an impeller comprising a magnetic alloy including platinum, cobalt, and boron.
- the impeller of the ventricular assist device comprises a unitary single body and has a biocompatible blood-contacting surface including a magnetic alloy consisting essentially of platinum, cobalt, and boron.
- the impeller comprises an alloy consisting essentially of about 12-14 atomic percent of boron, and platinum and cobalt in a platinum-to-cobalt atomic percent ratio of 0.90 to 1.2.
- the magnetic impeller comprises a magnetic alloy consisting essentially of about 13 atomic percent of boron, 42 atomic percent of platinum, and 45 atomic percent of cobalt.
- FIG. 1 illustrates an enlarged longitudinal sectional view of an implantable sealed rotary blood pump in accordance with one embodiment of the invention.
- FIG. 2 is an enlarged perspective view of the rotary impeller of the pump of FIG. 1 .
- FIGS. 3 and 4 are additional side views of the impeller of FIG. 2 in differing positions.
- FIG. 5 is a sectional view taken along line 5 - 5 of FIG. 2 .
- impeller is defined as the movable, fluid driving portion of a pump.
- impeller 14 may be positioned in an axial-flow rotary VAD pump 10 .
- impeller 14 comprises an alloy including platinum, cobalt, and boron. More preferably, the alloy comprises 12-14 atomic percent of boron, together with amounts of platinum and cobalt such that the atomic percent ratio of platinum to cobalt is from 0.90 to 1.2. In a preferred embodiment, the amount of platinum is slightly less than the amount of cobalt. Most preferably, the alloy consists essentially of platinum, cobalt and boron. For example, the alloy may include about 42 atomic percent platinum, 45 atomic percent of cobalt, and 13 atomic percent of boron.
- the platinum, cobalt, and boron alloy may be formed by rapid solidification of a homogeneous melt of platinum, cobalt and boron.
- the rapid solidification of a homogenous melt of platinum, cobalt and boron and heat-treatment of the solidified alloy can produce intrinsic coercivities in the range of 12-14 KOe for alloys containing 12-14 atomic percent boron and platinum to cobalt atomic ratio of 0.90 to 1.1.
- the alloy disclosed herein is biocompatible and has high resistance to corrosion, making it suitable for being in contact with blood.
- the alloy described above is magnetically isotropic
- the alloy can be highly magnetized with a plurality of magnetic poles in any geometric orientation.
- the alloy typically has Rockwell hardness on the order of 31 Rc, which eliminates the need for a hard, outer coating.
- impeller 14 may be formed by machining from a single solidified piece of the alloy, which may then be magnetized in the desired pole pattern.
- impeller 14 is formed as unitary single piece comprising the above described alloy, which can be fabricated into complex shapes using conventional metal working methods, unlike other “high strength” permanent magnets used in conventional rotary VADS.
- the use of a single piece impeller eliminates assembly procedures and hermeticity concerns which are associated with a traditional approach of placing magnetic materials within an impeller casing and laser welding closure caps to the casing.
- the single piece impeller may entirely consist of the biocompatible alloy essentially consisting of platinum, cobalt, and boron, thus ensuring that the entire impeller, including both the outer surface and the interior of the impeller, is biocompatible and suitable for contact with the blood.
- Impeller 14 may be magnetized with the North (N) and South (S) magnetic poles being as indicated on bladelike projections 20 ( FIG. 4 ).
- the impeller 14 disclosed in FIGS. 1-5 may operate in a VAD 10 ( FIG. 1 ) as described below.
- Impeller or rotor 14 may be positioned within the lumen of pump housing 12 and may have a hydrodynamic surface (specifically a series of hydrodynamic surfaces 16 that tend to propel blood in an axial direction as indicated by arrow 18 ) as impeller 14 is rotated clockwise.
- Blood pump 10 may be connected to the patient's vascular system to serve as a rotary VAD.
- impeller 14 may comprise blade-like projections 20 that extend radially outward and have walls 16 that define generally longitudinally extending spaces 22 between the projections 20 .
- the projections 20 and their side walls 16 constituting the hydrodynamic surfaces may be shaped to form curves in the longitudinally extending spaces 22 which are of a shape tending to drive blood in axial direction 18 as impeller 14 is rotated (clockwise in the embodiment depicted in FIG. 1 ).
- the longitudinally extending spaces 22 collectively may have a total circumferential width that is substantially less than the total circumferential width of the collective projections 20 .
- each of the longitudinally extending spaces 22 has a circumferential or peripheral width 26 .
- the four peripheral widths 26 of the four longitudinally extending spaces 22 together comprise a total peripheral width of all longitudinally extending spaces 22 .
- the distance of arc 28 represents the circumferential or peripheral width of the blade-like projection 20 .
- the total collective peripheral width of the longitudinally extending spaces 22 is substantially less than the total collective peripheral width of the respective bladelike projections 20 .
- the transverse sections of longitudinally extending spaces 22 to have generally parallel side walls 16 , although it can also be seen from FIG. 1 and other drawings that the overall width of longitudinally extending spaces 22 may vary along their lengths, being somewhat narrower at upstream areas 30 , and wider at downstream areas 32 , as shown in FIG. 1 . Clockwise rotation of rotor 14 will result in a flow of blood within the lumen of housing 12 from left to right in direction 18 .
- Blood pump 10 may further comprise a motor stator 36 ( FIG. 1 ) that includes an electrically conductive coil 38 within an enclosure 40 surrounding housing 12 and impeller or rotor 14 .
- the electromagnetic stator 36 serves to rotate impeller 14 by the conventional application of electric power to coil 38 , which is converted to a magnetic field that causes the impeller 14 to rotate either clockwise or counterclockwise depending on the polarity of the electric power.
- the specific technology for accomplishing this may be similar to that which is well known in the prior art.
- FIGS. 1-4 show radially outer faces 42 of bladelike projections 20 and also show a pair of hydrodynamic bearings 44 , 46 , which may be defined on projections 20 in the embodiment of FIGS. 1-5 , and which use fluid pressure to cause impeller 14 to be centered in the lumen of tubular housing 12 as the impeller 14 rotates without the need for physical bearings utilizing rubbing, solid surfaces.
- impeller 14 may rotate being held away from the inner wall of housing 12 by hydrodynamic bearings 44 , 46 on each of the blade-like projections 20 .
- an inner, annular ring 52 of housing 12 ( FIG. 1 ) may project inwardly from the inner wall cylinder housing 12 to limit the leftward motion of rotor 14 .
- Ring 52 may comprise an annular series of spaced projections, or it may comprise a solid ring with hydrodynamic bearings 44 serving to prevent contact between rotor 14 and ring 52 as the pump is operating with clockwise rotation of rotor 14 .
- a similar, annular ring 53 may be defined near the other end of housing 12 for similar purpose.
- Each of thrust bearings 44 , 46 may define a recessed curved outer surface which forms a recessed end portion relative to the outer face 42 of each projection 20 located at the forward end of each bearing 44 , 46 from the viewpoint of the (clockwise) spin of the rotor 14 a, so that the recessed end forms a leading edge of rotation.
- the recessed surface may taper in a gradual, curved manner outwardly to the rear end of each thrust bearing 44 , 46 , at which point, the bearing surface is not recessed, or only very slightly recessed, in a manner similar to that described in U.S. Pat. No. 6,234,772.
- each blade-like projection 20 scoop blood into a cross-sectional, recessed area of each bearing that decreases going from end to end, the effect of this being to pressurize the blood, and to thus repel each projection 20 from the inner wall of housing 12 as the impeller 14 rotates. Since the impeller 14 is spaced from the walls of housing 12 , the pressurized blood is released out of each bearing by passing across the end and out the sides of the recess. A pressure relief zone is provided at the trailing rotary end of each rotating projection 20 .
- stator 36 may comprise a separate hermetically-sealed coil-motor that slides over tubular housing 12 in position, and is secured thereto.
- stator 36 and coil 38 may be integrally attached to housing 12 .
- the stator may be reduced to one-half of the width necessary for This decrease in diameter increases the methods by which a VAD may be implanted into the body.
- the intravascular VADs of our earlier application has a diameter of 3 ⁇ 8 of an inch.
- the outer diameter of the VAD is 25 percent smaller than the device of the earlier application. This decrease in outer diameter made possible by the current invention will lead to less invasive surgical implantation techniques and consequently shorter recovery times for patients.
- FIGS. 1-5 The VAD 10 disclosed herein in FIGS. 1-5 is similar, but for the improvements disclosed herein, to that disclosed in U.S. patent application Ser. No. 11/003,810, filed Dec. 3, 2004, the disclosure of which is hereby incorporated by reference herein.
- the impeller 14 is formed entirely as a unitary single body comprising the biocompatible platinum, cobalt, and boron alloy.
- impeller 14 may include a non-unitary body formed from a combination of the biocompatible platinum, cobalt, and boron alloy disclosed herein, and other materials.
- ferromagnetic material such as iron or an iron-nickel alloy, which has desirable ferromagnetic properties, but which is not compatible with blood may be included in the interior of the impeller.
- the outer, blood-contacting surface of such an impeller including both biocompatible and non-biocompatible body portions may be defined by the biocompatible alloy including platinum, cobalt, and boron described above, thus ensuring that the blood-contacting surfaces of the impeller are biocompatible. If the alloy forms less than all of the outer surface, the remainder of the outer surface may be formed from another biocompatible material.
- the impeller may be magnetized with a plurality of magnetic poles in any geometric orientation.
- impeller comprising the alloy disclosed herein may be designed to rotate in the counterclockwise direction, making use of the principles and advantages described above.
- an impeller comprising the platinum, cobalt, and boron alloy disclosed herein, may be designed for use in both mixed-flow and centrifugal-flow ventricular assist devices, making use of the principles and advantages described above.
Abstract
Description
- The present application claims benefit of the filing date of U.S. Provisional Patent Applications Nos. 61/069,698, filed Mar. 17, 2008, and 61/065,141, filed Feb. 8, 2008, the disclosure of each of which is hereby incorporated by reference into this application.
- The present invention relates to an impeller comprising an alloy including effective amounts of platinum, cobalt, and boron for use in a blood pump such as a rotary Ventricular Assist Device (“VAD”).
- Clinical applications of Ventricular Assist Devices (“VADs”) to support patients with end-stage heart disease, as a bridge to cardiac transplantation, or as an end stage therapeutic modality have become an accepted clinical practice in cardiovascular medicine. It is estimated that greater than 35,000 persons suffering from end stage cardiac failure are candidates for cardiac support therapy.
- VADs may utilize a blood pump for imparting momentum to a patient's blood thereby driving the blood to a higher pressure. In particular, a rotary VAD is a blood pump containing an electromagnetically coupled impeller that spins to assist the patient's circulatory system.
- U.S. patent application Ser. No. 12/072,471, filed Feb. 26, 2008, the disclosure of which is hereby incorporated by reference into this application, provides an example of an intravascular rotary VAD that may be implanted in the patient to provide assistance in pumping blood for hearts that are afflicted with congestive heart failure or the like. This intravascular rotary VAD is a miniaturized VAD that has many uses due to it's small size. This miniaturization has made possible new techniques for less invasive implantation which in expected to shorten recovery times for patients following surgery.
- U.S. Patent Application Publication No. US 2007/0078293 A1, the disclosure of which is hereby incorporated by reference provides an example of a blood pump impeller including a platinum-cobalt alloy that is magnetizable to a high degree and may be manufactured as a single piece.
- U.S. Pat. No. 4,983,230, the disclosure of which is hereby incorporated by reference describes a magnetic platinum-cobalt-boron alloy having high coercivity for various uses.
- By this invention, an improved blood pump impeller is provided for use in, for example, a rotary VAD. It has been found that an impeller comprising an alloy including predetermined amounts of platinum, cobalt, and boron results in an impeller that is highly effective and has superior magnetic, mechanical, and biocompatible properties. These superior properties make possible further miniaturization and streamlining of a VAD pump than has previously been impossible in the VAD industry.
- One aspect of the invention provides a magnetic impeller for a blood pump, such as, for example, a rotary VAD. The magnetic impeller for a blood pump according to this aspect of the invention preferably comprises a magnetic alloy including platinum, cobalt, and boron. More preferably, the magnetic impeller comprises an alloy consisting essentially of about 12-14 atomic percent of boron, and platinum and cobalt in a platinum-to-cobalt atomic percent ratio of 0.90 to 1.2. Most preferably, the magnetic impeller comprises a magnetic alloy consisting essentially of about 13 atomic percent of boron, 42 atomic percent of platinum, and 45 atomic percent of cobalt.
- Another aspect of the invention provides a magnetically driven, implantable, rotary ventricular assist device for pumping blood of a patient. The ventricular assist device according to this aspect of the invention has an impeller comprising a magnetic alloy including platinum, cobalt, and boron. Preferably, the impeller of the ventricular assist device comprises a unitary single body and has a biocompatible blood-contacting surface including a magnetic alloy consisting essentially of platinum, cobalt, and boron. More preferably, the impeller comprises an alloy consisting essentially of about 12-14 atomic percent of boron, and platinum and cobalt in a platinum-to-cobalt atomic percent ratio of 0.90 to 1.2. Most preferably, the magnetic impeller comprises a magnetic alloy consisting essentially of about 13 atomic percent of boron, 42 atomic percent of platinum, and 45 atomic percent of cobalt.
- The increased magnetic properties of an impeller consisting essentially of about 13 atomic percent of boron, 42 atomic percent of platinum, and 45 atomic percent of cobalt or an impeller consisting essentially of platinum and cobalt, leads to greater efficiencies between the rotor and the stator. These efficiencies lead to further miniaturization which is medically advantageous.
- For a further understanding of the present invention, reference may be had to the accompanying drawings from which the nature and attendant advantages of the invention will be readily understood, and in which:
-
FIG. 1 illustrates an enlarged longitudinal sectional view of an implantable sealed rotary blood pump in accordance with one embodiment of the invention. -
FIG. 2 is an enlarged perspective view of the rotary impeller of the pump ofFIG. 1 . -
FIGS. 3 and 4 are additional side views of the impeller ofFIG. 2 in differing positions. -
FIG. 5 is a sectional view taken along line 5-5 ofFIG. 2 . - In describing the embodiments of the present invention illustrated in the drawings, specific terminology is employed for sake of clarity. However, the present disclosure is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner.
- Referring to
FIGS. 1-5 , an impeller orrotor 14 in accordance with various embodiments of the present invention is disclosed. An “impeller” is defined as the movable, fluid driving portion of a pump. As seen inFIG. 1 ,impeller 14 may be positioned in an axial-flow rotary VAD pump 10. - In one embodiment,
impeller 14 comprises an alloy including platinum, cobalt, and boron. More preferably, the alloy comprises 12-14 atomic percent of boron, together with amounts of platinum and cobalt such that the atomic percent ratio of platinum to cobalt is from 0.90 to 1.2. In a preferred embodiment, the amount of platinum is slightly less than the amount of cobalt. Most preferably, the alloy consists essentially of platinum, cobalt and boron. For example, the alloy may include about 42 atomic percent platinum, 45 atomic percent of cobalt, and 13 atomic percent of boron. - As disclosed in U.S. Pat. No. 4,983,230, the platinum, cobalt, and boron alloy may be formed by rapid solidification of a homogeneous melt of platinum, cobalt and boron. As further disclosed therein, the rapid solidification of a homogenous melt of platinum, cobalt and boron and heat-treatment of the solidified alloy can produce intrinsic coercivities in the range of 12-14 KOe for alloys containing 12-14 atomic percent boron and platinum to cobalt atomic ratio of 0.90 to 1.1. Additionally, the alloy disclosed herein is biocompatible and has high resistance to corrosion, making it suitable for being in contact with blood. Furthermore, as the alloy described above is magnetically isotropic, the alloy can be highly magnetized with a plurality of magnetic poles in any geometric orientation. Further still, the alloy typically has Rockwell hardness on the order of 31 Rc, which eliminates the need for a hard, outer coating. As a result of the foregoing advantages, an efficient and compact VAD design can be achieved which eliminates the need to build conventional assemblies of magnets and support structures, thus decreasing manufacturing costs. Further, by eliminating the need for conventional assemblies and support structures, we further increase the potential for miniaturization.
- The
entire impeller 14 may be formed by machining from a single solidified piece of the alloy, which may then be magnetized in the desired pole pattern. Preferably,impeller 14 is formed as unitary single piece comprising the above described alloy, which can be fabricated into complex shapes using conventional metal working methods, unlike other “high strength” permanent magnets used in conventional rotary VADS. The use of a single piece impeller eliminates assembly procedures and hermeticity concerns which are associated with a traditional approach of placing magnetic materials within an impeller casing and laser welding closure caps to the casing. The single piece impeller may entirely consist of the biocompatible alloy essentially consisting of platinum, cobalt, and boron, thus ensuring that the entire impeller, including both the outer surface and the interior of the impeller, is biocompatible and suitable for contact with the blood. -
Impeller 14 may be magnetized with the North (N) and South (S) magnetic poles being as indicated on bladelike projections 20 (FIG. 4 ). - The
impeller 14 disclosed inFIGS. 1-5 may operate in a VAD 10 (FIG. 1 ) as described below. - Impeller or
rotor 14 may be positioned within the lumen ofpump housing 12 and may have a hydrodynamic surface (specifically a series ofhydrodynamic surfaces 16 that tend to propel blood in an axial direction as indicated by arrow 18) asimpeller 14 is rotated clockwise. Blood pump 10 may be connected to the patient's vascular system to serve as a rotary VAD. - As illustrated in
FIG. 1 ,impeller 14 may comprise blade-like projections 20 that extend radially outward and havewalls 16 that define generally longitudinally extendingspaces 22 between theprojections 20. Theprojections 20 and theirside walls 16 constituting the hydrodynamic surfaces may be shaped to form curves in thelongitudinally extending spaces 22 which are of a shape tending to drive blood inaxial direction 18 asimpeller 14 is rotated (clockwise in the embodiment depicted inFIG. 1 ). - As can be seen from
FIG. 5 , thelongitudinally extending spaces 22 collectively may have a total circumferential width that is substantially less than the total circumferential width of thecollective projections 20. As illustrated inFIG. 5 , each of thelongitudinally extending spaces 22 has a circumferential orperipheral width 26. The fourperipheral widths 26 of the four longitudinally extendingspaces 22 together comprise a total peripheral width of all longitudinally extendingspaces 22. Similarly, the distance ofarc 28 represents the circumferential or peripheral width of the blade-like projection 20. The total collective peripheral width of thelongitudinally extending spaces 22 is substantially less than the total collective peripheral width of the respectivebladelike projections 20. - Preferably, the transverse sections of longitudinally extending
spaces 22 to have generallyparallel side walls 16, although it can also be seen fromFIG. 1 and other drawings that the overall width of longitudinally extendingspaces 22 may vary along their lengths, being somewhat narrower atupstream areas 30, and wider atdownstream areas 32, as shown inFIG. 1 . Clockwise rotation ofrotor 14 will result in a flow of blood within the lumen ofhousing 12 from left to right indirection 18. - Blood pump 10 may further comprise a motor stator 36 (
FIG. 1 ) that includes an electricallyconductive coil 38 within anenclosure 40 surroundinghousing 12 and impeller orrotor 14. Theelectromagnetic stator 36 serves to rotateimpeller 14 by the conventional application of electric power tocoil 38, which is converted to a magnetic field that causes theimpeller 14 to rotate either clockwise or counterclockwise depending on the polarity of the electric power. The specific technology for accomplishing this may be similar to that which is well known in the prior art. -
FIGS. 1-4 show radially outer faces 42 ofbladelike projections 20 and also show a pair ofhydrodynamic bearings projections 20 in the embodiment ofFIGS. 1-5 , and which use fluid pressure to causeimpeller 14 to be centered in the lumen oftubular housing 12 as theimpeller 14 rotates without the need for physical bearings utilizing rubbing, solid surfaces. - Thus,
impeller 14 may rotate being held away from the inner wall ofhousing 12 byhydrodynamic bearings like projections 20. At the rear ofimpeller 14, an inner,annular ring 52 of housing 12 (FIG. 1 ) may project inwardly from the innerwall cylinder housing 12 to limit the leftward motion ofrotor 14.Ring 52 may comprise an annular series of spaced projections, or it may comprise a solid ring withhydrodynamic bearings 44 serving to prevent contact betweenrotor 14 andring 52 as the pump is operating with clockwise rotation ofrotor 14. A similar,annular ring 53 may be defined near the other end ofhousing 12 for similar purpose. - Each of
thrust bearings outer face 42 of eachprojection 20 located at the forward end of each bearing 44, 46 from the viewpoint of the (clockwise) spin of the rotor 14a, so that the recessed end forms a leading edge of rotation. The recessed surface may taper in a gradual, curved manner outwardly to the rear end of each thrust bearing 44, 46, at which point, the bearing surface is not recessed, or only very slightly recessed, in a manner similar to that described in U.S. Pat. No. 6,234,772. - Thus, as the
impeller 14 rotates, therespective thrust bearings like projection 20 scoop blood into a cross-sectional, recessed area of each bearing that decreases going from end to end, the effect of this being to pressurize the blood, and to thus repel eachprojection 20 from the inner wall ofhousing 12 as theimpeller 14 rotates. Since theimpeller 14 is spaced from the walls ofhousing 12, the pressurized blood is released out of each bearing by passing across the end and out the sides of the recess. A pressure relief zone is provided at the trailing rotary end of each rotatingprojection 20. - In one embodiment,
stator 36 may comprise a separate hermetically-sealed coil-motor that slides overtubular housing 12 in position, and is secured thereto. Alternatively,stator 36 andcoil 38 may be integrally attached tohousing 12. - In one embodiment, the stator may be reduced to one-half of the width necessary for This decrease in diameter increases the methods by which a VAD may be implanted into the body. Previously, the intravascular VADs of our earlier application has a diameter of ⅜ of an inch. Using an impeller of the current invention, the outer diameter of the VAD is 25 percent smaller than the device of the earlier application. This decrease in outer diameter made possible by the current invention will lead to less invasive surgical implantation techniques and consequently shorter recovery times for patients.
- The VAD 10 disclosed herein in
FIGS. 1-5 is similar, but for the improvements disclosed herein, to that disclosed in U.S. patent application Ser. No. 11/003,810, filed Dec. 3, 2004, the disclosure of which is hereby incorporated by reference herein. - In the embodiments discussed above, the
impeller 14 is formed entirely as a unitary single body comprising the biocompatible platinum, cobalt, and boron alloy. However, this is not essential. For example,impeller 14 may include a non-unitary body formed from a combination of the biocompatible platinum, cobalt, and boron alloy disclosed herein, and other materials. For example, ferromagnetic material such as iron or an iron-nickel alloy, which has desirable ferromagnetic properties, but which is not compatible with blood may be included in the interior of the impeller. Some, or preferably all of the outer, blood-contacting surface of such an impeller including both biocompatible and non-biocompatible body portions may be defined by the biocompatible alloy including platinum, cobalt, and boron described above, thus ensuring that the blood-contacting surfaces of the impeller are biocompatible. If the alloy forms less than all of the outer surface, the remainder of the outer surface may be formed from another biocompatible material. The impeller may be magnetized with a plurality of magnetic poles in any geometric orientation. - It is contemplated that the impeller comprising the alloy disclosed herein may be designed to rotate in the counterclockwise direction, making use of the principles and advantages described above.
- It is further contemplated that an impeller comprising the platinum, cobalt, and boron alloy disclosed herein, may be designed for use in both mixed-flow and centrifugal-flow ventricular assist devices, making use of the principles and advantages described above.
- Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
Claims (27)
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US13/621,551 US10117981B2 (en) | 2008-02-08 | 2012-09-17 | Platinum-cobalt-boron blood pump element |
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US6514108P | 2008-02-08 | 2008-02-08 | |
US6969808P | 2008-03-17 | 2008-03-17 | |
US12/322,821 US20090204205A1 (en) | 2008-02-08 | 2009-02-06 | Platinum-cobalt-boron blood pump element |
US13/621,551 US10117981B2 (en) | 2008-02-08 | 2012-09-17 | Platinum-cobalt-boron blood pump element |
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US12/322,821 Continuation US20090204205A1 (en) | 2008-02-08 | 2009-02-06 | Platinum-cobalt-boron blood pump element |
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US20140079557A1 US20140079557A1 (en) | 2014-03-20 |
US20140322022A9 true US20140322022A9 (en) | 2014-10-30 |
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Families Citing this family (6)
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US10111994B2 (en) | 2013-05-14 | 2018-10-30 | Heartware, Inc. | Blood pump with separate mixed-flow and axial-flow impeller stages and multi-stage stators |
DE102018201030A1 (en) | 2018-01-24 | 2019-07-25 | Kardion Gmbh | Magnetic coupling element with magnetic bearing function |
DE102018211327A1 (en) | 2018-07-10 | 2020-01-16 | Kardion Gmbh | Impeller for an implantable vascular support system |
US11806518B2 (en) * | 2020-01-10 | 2023-11-07 | Heartware, Inc. | Passive thrust bearing angle |
DE102020102474A1 (en) | 2020-01-31 | 2021-08-05 | Kardion Gmbh | Pump for conveying a fluid and method for manufacturing a pump |
US20210378677A1 (en) * | 2020-06-08 | 2021-12-09 | White Swell Medical Ltd | Non-thrombogenic devices for treating edema |
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US1755321A (en) * | 1926-04-02 | 1930-04-22 | Welding Engineers | Welding hydraulic apparatus |
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US10117981B2 (en) | 2018-11-06 |
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