JP4964854B2 - Sealless blood pump with thrombus formation prevention means - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

  The present invention relates generally to the field of blood pumps, and more particularly to a rotary flow continuous flow pump suitable for permanent implantation in humans for use as a device for assisting the ventricle over time.

Conventional technology

  Thousands of heart patients suffering from severe left ventricular disease can be recovered by heart transplantation. However, due to donor heart defects, many of these patients shorten their lives due to frequent hospital discharges, serious disability, and death from congestive insufficiency or cardiogenic shock. By using a left ventricular assist device that is effective over time, many of these patients can be extended in life, enabling a productive life.

  Such left ventricular assist devices are specifically shown in the inventor's currently pending US patent application Ser. Nos. 08 / 603,536 and 08 / 910,375. These patent applications disclose rotary pumps with a continuous flow design rather than a pulsating flow design. The disclosed rotary blood pump solves many clinical problems, has significant advantages for use as a left ventricular assist device, eliminates the need to seal the drive shaft, and prevents thrombus formation In order to have an axial thrust bearing that is always washed with fresh blood flow.

  However, blood flow across the rotor ends of such rotary pumps and other designs of rotary pumps can be increased, and blood flow is low at dwell points such as the pump rotor end region near the axis of rotation. It is desirable to further reduce the chance of clotting at the site.

  The present invention provides a blood pump having a pump housing and a rotor mounted for rotation within the housing, the rotor having a rotational axis and an impeller attached thereto.

  The blood pump has a blood flow path that passes around the rotor, and the rotor has a peripheral edge that forms an end face. The end face has a profiled surface that increases the outward radial flow of blood from the central portion of the end face toward the periphery as the rotor rotates, compared to a flat end face. Thus, in particular, a sealless blood pump in which blood flow surrounds the rotor in operation can improve blood circulation across the end face of the rotor by the shaped surface of the present invention. This is especially true when the rotor is provided with thrust bearings or other types of bearings at the same end of the rotor, especially when the rotor is axially back and forth over a short distance, as taught in the above-mentioned patent application. Can be used even when translating to.

  Preferably, the shaped surface provided at the end of the rotor includes a channel extending from a central portion of the end surface. This channel constitutes a flow channel and increases the flow of blood radially outward from the end of the rotor when the rotor is rotating in use.

  The channel may extend outward in multiple directions, typically in two different directions extending from the central portion of the end face toward the periphery. However, if desired, a branch channel with three, four, or more branches extending radially outward from the center can be used.

  Typically, the channel extends toward the periphery at least at a pair of spaced apart positions. The channel at the first of these positions forms a predetermined angle with the adjacent perimeter, which is the angle formed between the channel and the adjacent perimeter at the second of the positions. Is different. In other words, the channel in the first position may be substantially perpendicular to the circumferential surface. However, the channel in the second of the spaced positions typically approaches the periphery with an acute angle of about 60 °, so that the ends of the channel are at different angles, Make flow characteristics asymmetric during rotation.

  In another aspect, the channel has a closed end in the central portion of the end face so that the flow through the channel during rotation of the rotor is unidirectional from the central portion toward the peripheral open end of the channel.

  Further, in some cases, it may be desirable to provide at least one conduit passing through the rotor between the channel and the surface of the rotor spaced from the end face to enhance blood circulation across the end face.

  In yet another aspect, the shaped surface at the end of the rotor has protruding ribs extending outwardly from the central portion of the end surface toward the periphery. This also increases the flow of blood from the central portion of the rotor end toward the periphery of the rotor as the rotor rotates.

  A pump housing typically has an elongated inlet tube at one end and an impeller casing at the other end, and the impeller casing portion has a drain tube so that blood flow is pumped through the inlet tube. And exit the pump through the drain tube.

  The rotor may have an elongated shaft portion, and the impeller is attached to the shaft portion at a predetermined location disposed within the impeller casing portion. The main blood flow channel is formed by an annular space or volume between the shaft portion and the housing.

  The end face of the blood pump rotor constitutes a thrust bearing for restraining the rotor so that the rotor does not translate beyond a predetermined position along its longitudinal axis. The thrust bearing includes a pair of bearing surfaces supported by a rotor and a pump housing, respectively. The shaped surface is provided with a channel extending across the periphery from the central portion of the end surface outwardly within the thrust bearing, as described above.

The motor stator may be positioned in the housing adjacent to the impeller to generate an electromagnetic field.
Roughly speaking, the shaped surface of the rotor end face constitutes a flow recess that occupies at least a position substantially intersecting the rotational axis. This recess allows the inside of the recess to flow radially outward when the rotor rotates.

  Thus, a blood pump of the type described in the above-mentioned patent application can be improved by providing a shaped surface at the end of the rotor to eliminate the stagnant area found in a rotor having a flat end. In the residence area, blood flows only slowly and thus clotting is likely to occur. The present invention can be similarly used with different types of rotary blood pumps.

BEST MODE FOR CARRYING OUT THE INVENTION

  Referring now to FIGS. 1-11 of the accompanying drawings, the rotary sealless blood pump 11 includes a housing 12 having an elongated inlet tube 13 and an impeller casing or volute 14. A discharge tube 16 passes through the housing and communicates with the inner periphery of the casing 14. Tube 16 is oriented tangentially with respect to the radius of the casing in order to effectively flow blood output from the pump.

  A pump rotor 17 is arranged in the housing 12, that is, in the casing 14. The rotor includes an elongate cylindrical support shaft or spindle 18 with a true circular cross section attached to a disk-like impeller 19. Rotor 17 is mounted for rotation about a longitudinal axis extending through both shaft 18 and impeller 19. It should be noted that the preferred embodiment disclosed herein includes a centrifugal design impeller and casing. However, the structural and operational features of the present invention can also be advantageously applied to an axial flow design rotary blood pump.

  The pump 11 of the present invention includes a front magnetic bearing 21 and a rear magnetic bearing 22 to float the rotor 17 and maintain it in a properly radial alignment with respect to its longitudinal axis. A radial magnetic bearing structure is shown in U.S. Pat. No. 4,072,370, assigned to Wasson. By touching the patent, the contents disclosed in the patent are incorporated in the present specification. The pre-magnetic bearing 21 described herein is completely formed in accordance with the teachings of US Pat. No. 4,072,370. However, several simplifications and improvements to the structure shown in US Pat. No. 4,072,370 are disclosed herein. For example, the practice of the present invention does not require the radially polar ring magnets (represented by reference numerals 44 and 46) of US Pat. No. 4,072,370. Further, as will be described below, for purposes of the present invention, an axial line instead of a ring magnet magnetized in the axial direction of the apparatus of U.S. Pat. No. 4,072,370 (denoted by reference numeral 22). A disk magnet magnetized in the direction may be used.

  Accordingly, the front magnetic bearing 21 includes a plurality of rings including a ferromagnetic pole piece 23 and a permanent magnet 24 having an axial polarity. As shown most clearly in FIGS. 7 and 8, the pole pieces 23 and the magnets 24 are alternately arranged with the same polarity facing between the outer side wall 26 and the inner side wall 27 of the inlet tube 13. . The opposite magnets have the same polarity and induce the same polarity in each pole piece in between. The combination of strong adhesive and the side wall of the tube that surrounds it keeps the magnet and pole piece in a face-to-face arrangement, regardless of the strong magnetic force that pushes the ring apart.

  Further, the front magnetic bearing 21 includes a plurality of disks including a ferromagnetic pole piece 28 and a permanent magnet 29 having an axial polarity. The pole pieces 28 and the magnets 29 are also alternately arranged so that the same poles face each other so as to form a magnet structure that is mirror-symmetrical with the polarities and axial positions of the pole pieces and magnets of the surrounding ring. First, the magnet structure is assembled and secured together using a strong adhesive and then placed in the hollow volume of the shaft or spindle 17. The polarities of the magnets and pole pieces of the front magnetic bearing 21 and the repulsive force generated by them are determined so that the support shaft 18 is magnetically levitated.

  A rear magnetic bearing 22 is further provided to further constrain the rotor 17 in the radial direction. The bearing 22 includes a first ring magnet 31 attached to the outer wall of the casing 14 and a second ring magnet 32 embedded in a base 33 of a circular casing. The bottom portion of the casing 14 is attached to and sealed to the base 33 to form a fluid impermeable enclosure for the impeller 19 (see FIG. 7). Both magnets 31 and 32 have an axial polarity, but each of these magnets faces the impeller 19 with a different polarity. The bearing 22 includes a plurality of bar magnets 34 that extend laterally from an upper surface portion 36 to a lower surface portion 37 of the impeller 19. These bar magnets 34 are adjacent to the outer periphery 38 of the impeller 19 and are arranged in a circular shape spaced apart from each other. The polarities between the ends of the magnet 34 and the adjacent surfaces of the magnets 31 and 32 are opposite and generate attraction, but apply equal and opposite magnetic forces to the impeller. When the impeller moves in the radial direction (deviates from the rotational axis), a restoring force is generated by the attractive force that the magnet 34 acts on the magnets 31 and 32. The axial magnetic force is roughly balanced with respect to each other by the magnetic attraction of the magnet 34 to the magnet 31 and the magnetic attraction of the magnet 34 to the magnet 32. However, the effect of magnetic force in the axial direction is not restored.

  In addition, it should be noted that other features, positions, numbers, and polar orientations can be used for the components forming the back magnetic bearing 22. For example, the magnet 34 may be an arc magnet instead of a bar magnet. Furthermore, the polarities of the magnets 31, 32, and 34 can be arranged to generate repulsive forces rather than the attractive forces specifically disclosed herein.

  In the drawing, the magnets 32 and 34 are shown such that some of them are in direct contact with blood, but in fact these parts are thin wall non-magnetic so that the magnet and blood are not in direct contact. Covered with jacket or plastic coating. When such contact occurs, an undesirable effect of degrading blood occurs. However, for clarity, the jackets or coatings referred to herein are not shown in the accompanying drawings.

  A first thrust bearing 39 and a second thrust bearing 41 are provided to mechanically limit the axial translation of the rotor. The first thrust bearing 39 includes a threaded plug 42 installed in the base 33 of the casing. The plug 42 can be screw-adjusted along the longitudinal axis of the rotor 17 and has a recessed bearing surface 43. The surface 43 is formed so that the corresponding bearing tip 44 matches the lower surface portion of the impeller 14. The particular shape of the bearing 39 is not critical and in another aspect a flat bearing surface can be used in this application.

  The second thrust bearing 41 is fixed in the blood inlet end of the inlet tube 13 and includes a spider 46, an adjacent knob 47, and a ball 48. The rotation of the knob 47 is transmitted to the ball 48 along the longitudinal axis of the rotor 17.

  Alternative positions and structures for the second thrust bearing 41 are also conceivable. For example, the surface of the annular thrust bearing can be provided on the inner wall of the casing 14 adjacent to the upper surface portion 36 of the impeller 19. In this construction, the portion 36 is slidably in contact with the annular thrust bearing surface. By eliminating the upstream thrust bearing spider 46 and associated components, blood deposits are not likely to form on these structures.

  It will be appreciated that the thrust bearings 39 and 41 not only provide a limiting stop that prevents the rotor 17 from moving axially, but are also effective in adjusting certain operational features of the pump. In the accompanying drawings, the upstream end of the support shaft 18 is shown in contact with the ball 48. However, it is not always in contact during operation of the pump. For example, it may be desirable to be able to adjust these bearings so that the distance between the two thrust bearings is slightly greater than the overall length of the rotor. This allows the rotor to “return” between axial restraints by thrust bearings according to each heart cycle of the user. Each such cycle produces a pumping action, putting fresh blood into the touchdown or thrust bearing area.

  The present invention typically does not use journal bearings to restrain the rotor. Inevitably, the journal bearings radially surround at least a portion of the rotor support shaft or spindle. In prior art devices, it is in this thin annular volume between the shaft and the bearing surface that the thrombus occurs due to heat and excessive convection time in the bearing. The bistable operation of the pump and rotor of the present invention allows blood to flow continuously around each thrust bearing, eliminating the thrombus formation effect of prior art journal bearings.

  Furthermore, there is an important physical relationship between the rotor and magnetic bearings of the apparatus disclosed herein. This relationship is established and maintained by properly positioning the adjustable thrust bearing in the axial direction. In operation of the pump, the pressure gradient generated by the rotating impeller applies an upstream axial force to the rotor. This force must be substantially balanced in the reverse direction in order to be able to produce sufficient pressure fluctuations through the pump due to the heartbeat in order to provide stable operation in both directions. By adjusting the axial relationship of pole piece 23 and magnet 24 with respect to pole piece 28 and magnet 29, a downstream axial force is generated. Because the force in the front magnetic bearing 21 is repulsive, when the magnet and pole piece in the shaft are translated slightly downstream from the magnet and pole piece in the inlet tube (see FIGS. 7 and 8), the desired downstream A load is obtained. Thus, the second thrust bearing is effective in shifting or shifting the rotor downstream by a sufficient amount so that the magnetic repulsive force is opposite to the hydrodynamic axial force generated by the rotating pump impeller. Substantially balance in direction.

  We now turn to the special design considerations and operational features of the impeller 19. As can be seen in particular in FIG. 6, the impeller includes a plurality of large blade sectors 49. Blood is a liquid that is particularly difficult to pump because it is relatively viscous and easily damaged by heat and mechanical action.

  In general, large centrifugal pumps with a large number of thin, sharp blades and relatively large voids or passages between the blades are preferred for passing low viscosity liquids. However, such conventional designs are not desirable for small centrifugal pumps that must pump viscous liquids such as blood.

  When blood flows axially to the leading edge of the impeller blade, it is susceptible to mechanical action and turbulent damage associated with the impeller blade. Thus, one design consideration of the present invention is to reduce such hemolysis by reducing the number of impeller blades and leading edges.

  In order to maintain the efficiency of such a small pump with a small number of blades, it is necessary to increase the effective working area of the blades. This is done in this design by changing the size and shape of the conventional blade in two ways. First, the blade sector 49 is relatively wide, i.e., wide with respect to rotation (see FIG. 6). In other words, the outer periphery of each blade sector 49 occupies a rotation angle of about 80 ° to 85 °. It should be noted that another design contemplated by this application has only two blade sectors, each of which occupies a rotation angle of about 175 °. In any case, the width of the impeller blade sector in this embodiment is significantly different from the prior art blades.

  The second change relates to the thickness or height of the blade sector. In particular, as shown in FIGS. 4 and 7, the blade sector 49 is relatively thick in the axial direction. As a result of these changes, a narrow and deep impeller blood flow path or passage 51 is formed between adjacent edges of the blade sector 49. By increasing the thickness of the blade sector and narrowing the blood passage, the ratio between the working surface area of the blade and the volume of the passage is increased. Furthermore, the average distance of the liquid in the passage from the working surface of the blade is reduced. Both of these advantageous results provide a small blood pump that maintains a sufficient efficiency, although few blades damage blood.

  Furthermore, due to the size and shape of the impeller blades, a number of features can be structurally integrated directly into the impeller 19. For example, after discussed above, the magnetic bearing 22 includes a plurality of bar magnets 34 of considerable length. Due to the thickness of the blade sector, it is easy to accommodate these magnets in the sector. Further, in order to reduce the mass of the impeller and reduce the load due to gravity acting on the thrust bearing (see FIG. 6), each sector may be provided with a hollow chamber 52.

  Finally, the brushless rotor motor 53 includes an arcuate magnetic segment 54 embedded in the upper surface portion 36 of the blade sector 49. As discussed above, when no measures are taken, the portion of the sector 54 that is in fluid communication with the pumped blood prevents chemical reaction between the blood and the magnetic segment. Wrapped with a jacket or coating (not shown). With reference to FIGS. 6 and 8, the segments 54 are oriented with alternating polarity and are directed to adjacent motor stators 56. Within the stator 56 is a winding 57 and a circular pole piece or back iron 58 which are attached to the outer surface of the impeller casing 14. As shown in FIG. 5, the winding wire 57 is connected to the control device 59 and the power source 61 by a percutaneous lead. Instead of using wires, transcutaneous power transfer can be used. The control device 59 and the power source 61 may be worn outside the user or may be completely implanted in the user's body.

  The controller 59 may comprise a simple circuit that can variably control the voltage or current manually or programmatically to determine the operating speed of the pump. However, the control device 59 may be interactive and automatic. For example, the controller 59 is connected to sensors provided in various organs of the user to automatically and instantaneously adjust the operation of the pump according to the user's physical activity and condition. Also good.

  The winding wire 57 is energized by the electric output of the control device 59 to generate an electromagnetic field. This electromagnetic field is concentrated by the magnetic pole piece 58. The electromagnetic field is effective for rotationally driving the magnet 54 and the rotor 17. The control device detects a back electromotive force (back EMF) generated by the magnet 54 passing through the side of the winding. The control device uses this back electromotive force no voltage to continuously generate an electromagnetic field in synchronization with further rotation of the rotor. The motor 53 is then brushlessly operated by electromagnetic interaction between the stator and the magnet embedded in the impeller blade of the pump.

  The motor 53 having the winding wire 57 and the magnetic pole piece 58 performs not only a function of transmitting torque but also a function of giving a restoring radial magnetic force acting as a radial bearing together with the magnet 54. As shown in FIGS. 7 and 8, the magnet 54 is supported by the blade sector 49 and is positioned in radial alignment with the pole piece 58. The magnet 54 is attracted to the stator iron pole piece 58. Any attempt to shift the impeller radially increases the restoring force between the pole piece 58 and the magnet 54 which attempts to return the impeller to the neutral position.

  When the rotor 17 including the shaft 18 and the impeller 19 rotates, blood flow in the direction of the arrow 62 passing through the inlet tube 13 is generated. The blood continues to flow from the upper edge of the passage 51 into the casing 14. The discharge tube 16 delivers blood from the casing to the user's cardiovascular system.

  The anatomical arrangement of the pump 11 is shown in FIG. The schematic view of the human heart 63 includes a left ventricle 64 and an aorta 67. The inlet tube 16 serves as an inflow cannula and is placed at the apex of the left ventricle 64. One end of the arterial tube graft 66 is connected to the tube 16 and the other end is connected to the aorta 67 by end-to-side anastomosis.

  Due to the centrifugal design of the pump, the implantation can be done quite freely. Due to the axial inflow and radial outflow of the pump, the direction of the blood changes by 90 ° without the need for elbow joints that restrict the flow. In addition, the pump can be rotated about its longitudinal axis to adjust the orientation of the drain tube and minimize vascular graft twisting and hydraulic loss. The pump casing is compact and disc-shaped and is well fitted between the apex of the heart and the adjacent diaphragm, so that good anatomical compatibility can be obtained.

  In accordance with the present invention, FIG. 9 shows one embodiment of the end face 71 of the pump rotor 17 when interacting with the ball 48 to form the thrust bearing 41. A narrow annular space 73 is formed around the ball 48 near the end surface 71 (see FIG. 6). This space includes a region where blood collects in a stagnant state even if the rotor 17 of the pump rotates as described above. The rotor 17 can reciprocate back and forth along its longitudinal axis during operation, which circulates blood, but increases the circulation of blood into and out of the annular space 73. It may be desirable.

  In accordance with the present invention, the end surface 71 provides a flow of blood from the central portion 73a of the rotor surface (which may be a recess engaging the ball 48) radially outward to or across the periphery 75 of the rotor 17. Construct a shaped surface that promotes (or a shaped surface).

  Specifically, the shaped surface is provided with a channel 77 that extends substantially radially outward from the central portion 73 of the end surface 71 toward the peripheral edge 75, such that the channel extends across the peripheral edge. It is open at the periphery. Thus, when the rotor 17 rotates, blood is collected in the channel 77 from the residence region 73 and is pushed outward by the rotation of the channel 77 and flows across the peripheral edge 75, thus improving blood circulation in the annular space 73. A pattern is formed.

  This simple embodiment can greatly increase the blood circulation at the end of the rotor 17 or at each end. In particular, a similar shaped surface and in particular a similar type of channel is provided on the end surface 79 of the rotor 17 opposite the end surface 71 and out of the residence area adjacent to this end surface 79 and the thrust bearing 39. Blood flow can be increased as well.

  Referring to FIG. 10, a modification of the end surface 71 is shown, and here, a reference number 71a is attached to the end surface. Here, a rib 81 is provided instead of a channel on the shaped surface of the end face, and this rib extends along substantially the same path as the channel 77 of the above-described embodiment shown in FIG. When the pump rotor 17 rotates, the ribs 81 form a blood circulation in the space 73. This circulating flow forms an outward flow of blood, forms a circulating flow pattern of blood through the annular region 17, greatly reduces stagnation, and greatly increases the tendency of blood to clot within the region or space 73. Make it smaller. Again, similar changes can be made to the rotor face 79 (see FIG. 7) to obtain similar results.

  Referring to FIG. 11, there is shown another embodiment of an end face 71 for the rotor 17, which is provided with a reference number 71b. The channel 83 provided on the shaped surface of the end surface extends from the central portion of the surface 71b across the peripheral edge 75 of the rotor 17 as in the above-described embodiment. It does not extend directly towards, and thus deviates to some extent from the radial direction. However, the channel 83 still collects blood from the central region of the rotating surface 71b when the rotor is operating in a pumping action and flows it as a continuous flow radially outward across the periphery 75 of the rotor.

  Accordingly, each of the embodiments of FIGS. 9, 10, and 11 increases the amount of blood exchange through the annular space 73, thereby reducing the stagnation and thus the tendency of the blood to clot.

A shaped surface similar to that shown in FIG. 11 can be applied to the end face 79 of the rotor 17 to obtain similar advantages.
One or more conduits such as drill holes 85 may be provided to further facilitate blood circulation across the end face of the rotor, such as end face 79. These conduits pass through the central portion of the end face 79 and communicate through the surface of the rotor spaced from the end face. Thus, the presence of such a conduit that can be formed as a drill hole can further enhance blood circulation from the restricted area adjacent to the end face 79.

  If desired, the plug 42 can be replaced with an electromagnet or a permanent magnet that serves as a magnetic bearing that holds the rotor 17 in magnetically spaced relationship from the plug.

  In a specific example, but not intended to be limiting, the thickness of the blood channel 62a shown in FIG. 7 is between 1.524 mm and 2.54 mm (0.06 inches and 0.1 inches). The fluid gap 70 that forms the gap between the impeller and the housing is between 0.127 mm and 0.508 mm (0.005 inch and 0.02 inch). The impeller has a diameter of 25.4 mm to 38.1 mm (1.0 inch to 1.5 inch). The diameter of the rotor is between 0.25 inch and 0.4 inch. The outer diameter of the annular channel is between 8.89 mm and 13.97 mm (0.35 inch to 0.55 inch). The outer diameter of the housing adjacent to the front end of the pump is 21.59 mm to 31.75 mm (0.85 inch to 1.25 inch). The overall axial length of the pump is 44.45 mm to 76.2 mm (1.75 inches to 3.0 inches). The axial length of the rotor spindle is 25.4 mm to 38.1 mm (1.0 inch to 1.5 inch), and the impeller axial length is 5.08 mm to 12.7 mm (0.2 inch). To 0.5 inches). By using a thick (long axial length) impeller, the fluid gap 70 can be increased, which also makes the pumping action highly efficient.

  An enlarged view of another design of the impeller used in the pump of the present invention is shown in FIGS. Referring to FIGS. 12 and 13, these figures show an impeller 74 having a number of blade sectors 76, 78, and 80. Blade sectors 76 and 78 are separated by slot 82, blade sectors 78 and 80 are separated by slot 84, and blade sectors 80 and 76 are separated by slot 86. By using blade sectors 76, 78, and 80 having a relatively large axial thickness, a relatively narrow and deep impeller blood flow path is provided by slots 82, 84, and 86 between adjacent edges of the blade sector. It is formed. By increasing the thickness of the blade sector and by narrowing the blood passage, the ratio between the working surface area of the blade and the volume of the passage is increased. Furthermore, the average distance of the liquid in the passage from the working surface of the blade is reduced. Both of these advantages provide a small blood pump with a small number of blades that can damage blood, which is small but yet sufficiently efficient.

  Although not intended to be limiting, as a specific example, the impeller diameter is 25.4 mm to 38.1 mm (1 inch to 1.5 inch) and the blade depth bd (see FIG. 12) is: The magnet width mw (see FIG. 12) is 3.81 mm to 7.62 mm (0.15 inch to 0.3 inch). The spindle diameter sd (see FIG. 12) is 6.35 mm to 12.7 mm (0.25 inch to 0.5 inch), and the inner diameter id (see FIG. 12) of the impeller inlet is 11.43 mm. 15 to 24 mm (0.45 inch to 0.6 inch). The width w of the slot (see FIG. 13) is about 0.075 inch, preferably in the range of 0.05 inch to 0.2 inch. . The exit angle a (see FIG. 13) is preferably in the range of 30 ° to 90 °.

  Another advantage of a thick impeller is that it can use pole pieces 88 that are inserted so that the stator can be placed on either side of the impeller 74. Referring to FIGS. 14 and 15, the blood pump 11 shown in these figures is similar in many respects to the blood pump 11 shown in FIGS. 1-11, with an elongated inlet tube 13a and a scroll-like impeller casing or volute 14a. And a housing 12a. A discharge tube 16a passes through the housing and communicates with the inner periphery of the casing 14a. Tube 16a is oriented tangentially with respect to the radius of the casing to effectively flow blood output from the pump.

  The pump rotor 17 is disposed in the housing 12 and the casing 14 and includes an elongated true circular cylindrical support shaft or spindle 18 attached to the impeller 74. The rotor 17 is mounted so as to rotate about a longitudinal axis passing through both the shaft 18a and the impeller 74.

  Magnetic bearings for levitating the rotor 17a and maintaining it properly aligned in the radial direction with respect to its longitudinal axis are shown in FIGS. It may be the same as the magnetic bearing shown in the embodiment of the pump described above.

  14 and 15, a first motor stator 90 including a conductive coil or motor winding 91 is disposed at the rear of the impeller 74. A ring of the back metal 92 is disposed behind the winding 91. As shown in the figure, the first motor stator 90 and the back metal 92 are fixed between the housing 12a and the casing 14a.

  The second motor stator 94 having the saddle wire 95 is positioned on the front side of the impeller 74. As shown in FIG. 14, the winding wire 95 is fixed to the casing 14 a, and the back iron 96 is positioned in front of the winding wire 95. Further details are described in US patent application Ser. No. 08 / 910,375, cited above.

  The motor stators 90 and 94 are arranged on both sides of the casing 14 so that each of them is adjacent to the magnetic pole surface of the motor rotor magnet 88. Back iron 92 and back iron 96 help complete the magnetic circuit. The windings 91 and 95 of the stators 90 and 94 may be in series, or each stator 90 and 94 may be adjusted independently of each other. This method has several advantages listed below.

First, as long as the pole face of the motor rotor magnet is centered between the faces of the motor stator, the net axial force is relatively small.
Second, the restoring force in the radial direction due to the attractive force of the motor rotor magnet to the motor stator is approximately twice the restoring force when only one stator is provided. The total volume and weight of the motor is smaller than the single stator design.

  Third, the two-stator design is designed to provide system redundancy for the failsafe mode. This is because each stator is made to operate independently when a system failure occurs.

  Fourth, hydrodynamic bearings can be placed on the surface of the impeller to constrain axial movement and to provide radial support when an eccentric movement or impact is applied to the device. With particular reference to FIGS. 14 and 14a, a hydrodynamic bearing in the form of raised pads 100, 101 and contact surfaces 102 and 103 is shown. Such hydrodynamic bearings are arranged symmetrically about the impeller.

  The raised pad is rectangular or wedge shaped and is preferably formed of a hardened or wear resistant material such as ceramic, diamond coating, titanium nitride or the like. In another aspect, the raised pad can be formed of a variety of materials with alumina or other ceramic coatings or inserts.

  The raised pad is supported by either the impeller or casing, or an attachment to the casing. 14 and 14a, the raised pad 100 is supported by an impeller, and the raised pad 101 is supported by a cup-like member 104 attached to the casing. The cup-shaped member 104 is used as a reinforcement for a casing that does not have sufficient structural stability to support the raised pad itself.

  The hydrodynamic bearing is formed by a raised pad that is spaced from the contact surface by a blood gap. While there may be contact between the impeller and the casing at rest, each hydrodynamic bearing has a fluid dynamics of the thin film of fluid during relative movement between the raised pad and the contact surface once rotation has begun. The pressure in the bearing gap rises due to the mechanical action, and the raised pad and the contact surface are forcibly separated from each other.

  Depending on its location, the hydrodynamic bearing can assist in axial support, radial support or both axial and radial support. For example, if the bearings are perpendicular to the axis of rotation, these bearings primarily assist in axial support, but if they are at a predetermined angle with respect to the axis of rotation, they are radial and axial. Support in both directions. In the embodiment of FIGS. 14 and 15, the hydrodynamic bearing is positioned outside the axis of rotation as shown.

  According to the present invention, the rotor end surface 110 is recessed, particularly as shown in FIG. This end surface is a portion of the cup-shaped member 104 of the casing, and has a cup-shaped space 112 having a relatively narrow width between the cup-shaped member 104 and the rotor 74. This space is filled with blood. The present invention improves blood circulation through the cup-shaped space 112 by profiling 114 of the recessed end face 110 (see FIG. 12).

  Profiling the end face 110 is illustrated in the embodiment of FIG. 16 in which the end face 110 is provided with channels 116 extending outwardly in a plurality of directions from the end face central portion 118 toward the periphery of the end face. In addition, the flow characteristics at each end of the channel is different because the angle at which the radially outer end of the segment 120 of the channel 118 is directed toward the edge of the end face is different from the corresponding angle of the segment 122 of the channel 118. You can see that they are different. The angle of segment 120 is approximately 90 ° and the angle of segment 122 is approximately 60 °.

  The channel 118 is shown as a specific example of a possible shaping of the end face 110 with the recess of FIG. 13, which is different from the shaping shown in FIG. Yes.

  Referring to FIG. 17, another example of shaping the end face 110 is shown as channel 118a. The channel extends from the central portion 116a of the end face substantially radially outward toward its end. Blood in channel 118a is pumped outward by rotating end face 110 and channel 118a that are part of rotor 74 during operation of the pump.

  FIG. 18 shows a third embodiment for shaping the end face 110. This particular shaping 114a may be the same as that shown in FIG. 12 and includes a substantially radial protrusion that extends from the center of the end face 110 provided with a recess to the edge of the end face. .

  Thus, during rotation of the rotor, the shaping bar 114a moves so as to sweep in a 360 ° arc across the bottom portion of the cup-shaped space 112 to form an outward circulation of blood, thereby Blood continuously circulates and moves across the cup-shaped space 112. This is done to suppress blood clotting.

  While exemplary embodiments of the present invention have been shown and described, it should be understood that various changes and substitutions can be made by those skilled in the art without departing from the novel spirit and scope of the invention. is there.

It is the perspective view which looked at the blood pump of the present invention from the left front. FIG. 2 is a partial cross-sectional perspective view of the pump of FIG. 1 showing a plurality of ring magnets that form part of a magnetic bearing assembly. FIG. 2 is a partial cross-sectional perspective view of the pump of FIG. 1 showing a shaft and impeller. FIG. 2 is a partial cross-sectional perspective view of the pump of FIG. 1 with the shaft and impeller removed from the housing. 1 is a schematic diagram of a human heart showing a pump implanted in the left ventricle of the heart. FIG. FIG. 6 is a cross-sectional view of the housing, impeller, and impeller chamber taken along line 6-6 of FIG. FIG. 7 is a longitudinal cross-sectional view of the pump along line 7-7 in FIG. FIG. 3 is a schematic longitudinal sectional view of the pump showing the respective polarities of the passive radial magnetic bearing and the magnets and pole pieces of the elements of the pump motor including the rotor magnet and motor stator. FIG. 9 is a schematic view showing one embodiment of an end face of a thrust bearing constituting the shaped face of the present invention at the end face of the rotor shown in FIGS. 1 to 8. FIG. 9 is a schematic view showing another embodiment of the end face of the thrust bearing constituting the shaped face of the present invention at the end face of the rotor shown in FIGS. 1 to 8. FIG. 9 is a schematic view showing still another embodiment of the end face of the thrust bearing constituting the shaped face of the present invention at the end face of the rotor shown in FIGS. 1 to 8. 1 is a longitudinal sectional view of an impeller formed in accordance with the principles of the present invention. It is the end elevation seen from the right side of FIG. FIG. 14 is a schematic longitudinal sectional view of another embodiment of a pump using the same impeller as in FIGS. 12 and 13, and a is an enlarged view of a portion surrounded by a circle in FIG. 14. FIG. 12 is an end cross-sectional view of the pump of FIG. 11 with the housing and end of the casing removed for clarity. FIG. 13 is a schematic diagram illustrating one embodiment of a central end surface portion of the impeller of the pump of FIG. 12 and a shaped surface of the present invention. FIG. 13 is a schematic diagram illustrating another embodiment of the central end surface portion of the impeller of the pump of FIG. 12 and the shaped surface of the present invention. FIG. 13 is a schematic diagram illustrating yet another embodiment of the central end surface portion of the impeller of the pump of FIG. 12 and the shaped surface of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Rotary sealless blood pump 12 Housing 13 Inlet tube 14 Impeller casing 16 Exhaust tube 17 Pump rotor 19 Disc-shaped impeller 18 Spindle 21, 22 Magnetic bearing 23 Ferromagnetic pole piece 24 Magnet 26 Side wall 27 Side wall 38 Ferromagnetic pole piece 28 Magnetic pole Piece 29 Permanent magnet 31 First ring magnet 32 Second ring magnet 33 Circular casing base 34 Bar magnet

Claims (11)

A blood pump comprising: a pump housing; a rotor mounted for rotation within the housing; and a thrust bearing including a ball for constraining the rotor in an axial direction, the rotor including a rotation axis and an impeller attached The blood pump has a blood flow path that passes around the rotor, the rotor has a peripheral edge surrounding the end face, the ball is adjustable along the axis of rotation, and the end face is Including a recess configured to receive the ball, the end surface interacting with the ball to form an annular space along the axis of rotation for translation of the ball, and the end surface includes the rotor said increasing the flow of blood in the annular space towards the periphery radially outwardly from a central portion of the end face during rotation, from the recess of the end face Having shaped by surface extending toward the serial peripheral blood pump, characterized in that.   The blood pump according to claim 1, wherein the shaped surface has a channel extending outward from the central portion of the end surface toward the peripheral edge.   The blood pump according to claim 2, wherein the channel extends outward in a plurality of directions from the central portion of the end surface toward the peripheral edge.   The channel engages the periphery at least at a pair of spaced positions, and the channel forms a predetermined angle with the periphery at a first position of the positions, the angle being The blood pump according to claim 3, wherein the blood pump is different in angle between the channel and the periphery at a second position.   The blood pump of claim 2, wherein the channel has a closed end at the central portion of the end face.   The at least one conduit extends through the rotor between the channel and a surface of the rotor spaced from the end face to enhance blood circulation across the end face. The blood pump as described in any one of them.   The blood pump according to any one of claims 1 to 6, wherein the shaped surface is asymmetric.   The blood pump according to claim 1, wherein the shaped surface has a protruding rib extending outward from the central portion of the end surface toward the peripheral edge.   The end surface has a pair of bearing surfaces configured to receive the ball, and the shaped surface extends within the bearing surface outward from the central portion of the end surface. 8. A blood pump according to any one of the preceding claims, having a channel extending across.   The blood pump according to any one of claims 1 to 9, wherein the motor stator in the housing is positioned adjacent to the impeller to generate an electromagnetic field. The shaped surface of the end surface constitutes a flow recess that occupies a predetermined position at least substantially intersecting the rotational axis, and the flow recess causes a radius within the flow recess during rotation of the rotor. The blood pump of claim 1, wherein a directional outward flow is formed.

Images