Blood pump impellers, associated cages and assemblies

Abstract

An impeller and associated impeller cage for a blood pump, comprising an impeller flowpath contour having an outlet impeller blade portion, the contour extending radially outward from a nose and terminating in a straight outer edge, the straight outer edge being parallel to an axial centerline of the impeller and facing a window in the impeller cage, the impeller and impeller cage providing improved outflow and / or increased hydraulic efficiency over current commercially available devices.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 476,025, filed December 19, 2022, the contents of which are incorporated herein by reference as if fully set forth herein.

[0002] The present invention relates to a blood pump, and is particularly suitable for an intravascular blood pump such as a catheter blood pump. [Background technology]

[0003] Over the years, various types of blood pumps have been developed to augment or replace the blood pumping action of a damaged or diseased heart. These pumps may be designed to provide right ventricular assist and / or left ventricular assist, although left ventricular assist is more common because diseased or damaged left ventricles are far more common than right ventricles.

[0004] A blood pump must pump fluid at an appropriate rate without subjecting the fluid to excessive Reynolds shear stress. As is well known to those skilled in the art, cell lysis and destruction can result from shear stress on the cell membrane. Red blood cells are particularly susceptible to shear stress damage because their cell membranes do not contain a reinforcing cytoskeleton that maintains cell shape.

[0005] Intravascular blood pumps typically include miniature blood pumps that can be percutaneously or surgically introduced into a patient's vascular system to provide left ventricular and / or right ventricular assist. See, for example, U.S. Pat. Nos. 4,625,712 and 4,846,152, the contents of which are incorporated herein by reference as if fully set forth herein. U.S. Pat. No. 4,625,712 describes a multistage intravascular axial blood pump that can be percutaneously inserted into an artery for cardiac assist, while U.S. Pat. No. 4,846,152 describes a single-stage intravascular axial blood pump. These blood pumps utilize long cable drives with the drive unit / motor located outside the body (extracorporeal). The maneuverability and / or durability of these types of blood pumps often are less than desirable. The components of these devices tend to deteriorate prematurely during use due to the rotational and pulsating forces imposed on the blood pumps.

[0006] Another intravascular blood pump is configured such that the drive unit / motor and impeller are directly coupled to each other and the outer diameters of the motor and impeller (pump) housings are approximately the same. See, for example, U.S. Patent No. 6,176,848, the contents of which are incorporated herein by reference as if fully set forth herein.

[0007] While these systems have been used successfully to pump blood, the flow rates achieved are typically expected to be less than 3 liters per minute (except for peak outputs for limited periods) at a counter pressure of about 100 mmHg. Pumping speed is limited by torque limitations of the small "micro" motors and / or impeller configuration.

[0008] There is a need for a blood pump that can increase blood flow without applying excessive shear forces. Summary of the Invention [Means for solving the problem]

[0009] An embodiment of the present invention couples a curved impeller with a relatively large window in the impeller cage for blood outflow in a blood pump.

[0010] The curved shape may include an outlet blade portion having a straight outer edge, the straight outer edge having a length that is approximately 50-110% of the length of the impeller cage window.

[0011] The impeller cage may have only three struts with windows extending between adjacent struts. The impeller cage may also have only three circumferentially spaced windows.

[0012] The impeller may be in communication with a motor, which rotates the impeller to pump blood through the patient's heart.

[0013] The impeller may be in communication with an extracorporeal motor. A multi-lumen shaft may enclose a long torque cable, the torque cable being coupled at one end to the motor and at the other end to the impeller shaft of the impeller, the multi-lumen shaft including inlet and outlet (purge) fluid paths for cooling and / or lubrication of the long torque cable.

[0014] The impeller may be in communication with an adjacent in-vivo motor, eliminating the need for long drive cables.

[0015] An embodiment of the present invention is directed to an impeller for a blood pump, the impeller including an impeller body having a curvilinear shape extending from a distal nose portion to a pair of vanes located proximal to the nose portion, each vane having an outlet blade portion with a constant maximum radius measured from an axial centerline of the impeller body over the length of the outlet blade portion.

[0016] The length of the outlet blade portion may be in the range of 3.7mm to 3.8mm.

[0017] The outlet blade portion may be perpendicular to the axially extending centerline throughout its span.

[0018] The impeller blades may have an axial length of about 9.15 mm.

[0019] The impeller blades may have a wrap angle of approximately 130 degrees.

[0020] The impeller may be combined with an impeller cage at least partially surrounding the impeller body, and the outlet blade portion may be longitudinally aligned with a cage window of the impeller cage.

[0021] The impeller cage may have only three windows and only three struts, and the windows may be longitudinally aligned and circumferentially spaced apart, and the struts may be longitudinally aligned and circumferentially spaced apart.

[0022] Each of the three windows may have a longitudinal length and a circumferential width, thereby defining a respective window area. The window area may be 10 mm 2 ~14mm 2 It may be in the range of.

[0023] The outlet blade portion may have a length that is approximately 80-110% of the length of the window.

[0024] The length of the outlet blade portion may be the same as the length of the three windows.

[0025] The cage window may have an outer peripheral angle in the circumferential direction in the range of 90 to 100 degrees.

[0026] The circumferentially extending outer periphery angle may be approximately 98 degrees.

[0027] The impeller body may have an overall length in the range of 8.5mm to 9.5mm.

[0028] The overall length may be about 9.15 mm.

[0029] The impeller may be configured to taper outward from a nose portion to a spaced apart, longitudinally aligned peak portion, and then taper radially inward proximally to merge with the vanes, which may have a radius the same as the maximum radius of the peak portion.

[0030] The impeller cage is the stage length (L STAGE ) and this stage length is longer than the total length of the impeller. This stage length may be longer than the impeller by less than 0.25 mm.

[0031] The impeller may have an impeller cage surrounding the impeller, and the gap distance between the inner surface of the impeller cage and the peak portion may be about 0.75 mm.

[0032] The impeller body may have a maximum outer diameter of about 4.15 mm.

[0033] The impeller cage may have a window area / cylinder area ratio of 0.8043.

[0034] The outlet blade portion may terminate adjacent the proximal end of the window.

[0035] Yet another embodiment is directed to an impeller assembly for a catheter blood pump. The impeller assembly has a curvilinear shape extending from a distal nose portion to a pair of proximally located vanes. Each vane has an outlet blade portion having a constant maximum radius measured from an axially extending centerline of the impeller body over the length of the outlet blade portion. The impeller assembly also includes an impeller cage at least partially surrounding the impeller. The outlet blade portion is longitudinally aligned with a cage window of the impeller cage.

[0036] The impeller cage may have only three windows and only three struts, the windows being longitudinally aligned and circumferentially spaced apart, and the struts being longitudinally aligned and circumferentially spaced apart.

[0037] Each of the three windows has a length extending in the longitudinal direction and a width extending in the circumferential direction, thereby defining a respective window area. The window area of ​​each window is 10 mm 2 ~14mm 2 It may be in the range of.

[0038] The outlet blade portion may have a length that is approximately 80-110% of the length of the window.

[0039] The outlet blade portion may define an outlet flow angle of 90 degrees.

[0040] The length of the outlet blade portion may be the same as the length of the three windows.

[0041] The cage window may have an outer peripheral angle in the circumferential direction in the range of 90 to 100 degrees.

[0042] The circumferential angle may be 98 degrees.

[0043] The impeller may have an overall length in the range of 8.5mm to 9.5mm.

[0044] The overall length may be about 9.15 mm.

[0045] The nose portion may blend with an adjacent blade portion, which tapers outward to a peak portion. The blade may then taper radially inward proximally to blend with a vane. The vane may have a radius corresponding to (or approximately the same as) the peak portion.

[0046] The cage is the stage length (L STAGE) and this stage length may be less than 0.25 mm longer than the overall length of the impeller.

[0047] The gap distance between the inner surface of the impeller cage and the peak portion may be about 0.75 mm.

[0048] The impeller body may have a maximum outer diameter of about 4.15 mm.

[0049] The impeller cage may have a window area / cylinder area ratio of 0.8043.

[0050] The outlet blade portion may terminate adjacent the proximal end of the window.

[0051] The impeller cage may have only three windows and only three struts, the windows being longitudinally aligned and circumferentially spaced apart, and the struts being longitudinally aligned and circumferentially spaced apart.

[0052] The window may have straight upper and lower peripheries in the circumferential dimension.

[0053] Each of the three windows may have a longitudinal length and a circumferential width, thereby defining a respective window area, the window area being 10 mm 2 ~14mm 2 It may be in the range of.

[0054] The cage window may have an outer peripheral angle in the circumferential direction in the range of 90 to 100 degrees.

[0055] The circumferential angle may be approximately 98 degrees.

[0056] The three struts may have a circumferential width in the range of 0.4 mm to 0.7 mm and a longitudinal length in the range of 3.7 mm to 4.0 mm.

[0057] The length of the struts may be 3.75 mm.

[0058] Yet another embodiment is directed to an in vivo impeller for a blood pump having an impeller body configured to have outlet blades with a 90 degree straight outlet blade angle over at least 30% of the length of the impeller body.

[0059] Those skilled in the art will appreciate additional features, advantages and details of the present invention from a review of the following drawings and detailed description of the preferred embodiments, which are merely exemplary of the invention.

[0060] It should be noted that aspects of the invention described with respect to one embodiment may be incorporated into other embodiments not specifically described. That is, all embodiments and / or all features of any embodiment may be combined in any manner and / or in any combination. Applicant reserves the right to modify any originally filed claims or to submit any new claims accordingly, including the right to amend any originally filed claims to depend on and / or incorporate any feature of any other claim not originally so claimed. The detailed description set forth below sets forth these and other objects and / or aspects of the invention in detail. [Brief explanation of the drawings]

[0061] [Figure 1] FIG. 1 is a side view of a blood pump according to an embodiment of the present invention, with a portion of the shell handle removed to reveal the internal components. [Figure 2] 2 is another side view of the blood pump shown in FIG. 1, rotated 90 degrees from the orientation shown in FIG. 1. [Figure 3A] ~ [Figure 3C] FIG. 1 is an enlarged view of a prior art axial impeller and cage of a catheter blood pump. [Figure 4A]FIG. 2 is an enlarged side view of an impeller and cage according to an embodiment of the present invention. [Figure 4B] FIG. 4B is a side perspective view of the impeller and cage shown in FIG. 4A. [Figure 4C] FIG. 4B is a distal end view of the impeller and cage shown in FIG. 4A. [Figure 4D] FIG. 4B is a side perspective view of the impeller shown in FIG. 4A. [Figure 4E] FIG. 4B is a side perspective view of the cage shown in FIG. 4A. [Figure 4F] 1 is a basic schematic diagram of a turbomachine with corresponding outlet angles for an impeller according to an embodiment of the present invention; FIG. [Figure 4G] FIG. 2 is a schematic diagram of a portion of an impeller providing blade sections that define a 90 degree exit flow angle, according to an embodiment of the present invention. [Figure 4H] FIG. 4H is a side perspective view of the impeller and impeller cage (transparent) showing imaginary intersection lines corresponding to the exit flow angles shown in FIG. 4G. [Figure 4I] FIG. 4D is a distal end view of the impeller and impeller cage shown in FIG. 4H with imaginary intersection lines corresponding to the outlet flow angles shown in FIG. 4G. [Figure 5A] 6A is an enlarged side view of the impeller and cage shown in FIGS. 4A-4C, shown adjacent to FIG. 6A for ease of reference. [Figure 5B] FIG. 6B is an end view of the impeller and cage shown in FIG. 5A, shown adjacent to FIG. 6B for ease of reference. [Figure 6A] FIG. 3D is an enlarged side view of the prior art impeller and cage shown in FIGS. 3A-3C. [Figure 6B] FIG. 6B is an end view of the prior art impeller and cage shown in FIG. 6A. [Figure 7] 5A / 5B and 6A / 6B in accordance with an embodiment of the present invention. [Figure 8] 4E is a graph of the meridional profile of the impeller blade shown in FIG. 4D. [Figure 9]3A-3C are graphs of the meridional contours of the prior art impeller shown in FIGS. [Figure 10] FIG. 1 is a side perspective view of an impeller showing a meridional flow surface with meridional and tangential coordinates relative to the local radius that can be mapped to a plane by a coordinate transformation. [Figure 11] 4A-4C and the prior art impeller shown in FIGS. 3A-3C are graphs of blade airfoil centerlines (inner span, mid span, outer span) m, t. [Figure 12] 4A-4C are graphs illustrating the blade angle β distribution (inner span, mid span, outer span) (β vs. m / Max) of the impellers shown in FIGS. 3A-3C and 4A-4C according to an embodiment of the present invention. [Figure 13] ~ [Figure 16] FIG. 1 is a side perspective view of an exemplary impeller cage configuration, according to an embodiment of the present invention. [Figure 17] FIG. 1 is a side perspective view of a prior art impeller cage. [Figure 18A] FIG. 14 is a close-up side perspective view of finite element analysis (FEA) results color-coded by von Mises stress results (psi) for the narrow, three-strut impeller cage shown in FIG. 13 in accordance with an embodiment of the present invention. [Figure 18B] FIG. 18B is a greatly enlarged view of the proximal portion of the FEA results for the impeller cage shown in FIG. 18A. [Figure 18C] FIG. 18C is a close-up view of the proximal portion of the strut shown in FIG. 18B. [Figure 19A] FIG. 18B is a side perspective view of FEA results color-coded by deflection URES (mm) of the narrow three-strut impeller cage shown in FIG. 18A, graphically showing deflections amplified by 50 times, in accordance with an embodiment of the present invention. [Figure 19B] FIG. 19B is a side perspective view of FIG. 19A modified to show "true deflection" and reduced clearance to the impeller. [Figure 20A]FIG. 15 is a close-up side perspective view of finite element analysis (FEA) results color-coded by von Mises stress results (psi) for the wide three-strut impeller cage shown in FIG. 14 in accordance with an embodiment of the present invention. [Figure 20B] FIG. 20B is a greatly enlarged view of the proximal portion of the FEA results for the impeller cage shown in FIG. 20A. [Figure 20C] FIG. 20B is an enlarged view of the proximal portion of the strut shown in FIG. 20A. [Figure 21A] FIG. 15 is a side perspective view of FEA results color-coded by deflection URES (mm) for the wide three-strut impeller cage shown in FIG. 14, graphically showing deflections amplified by 70 times, in accordance with an embodiment of the present invention. [Figure 21B] FIG. 21B is a side perspective view of the impeller cage and FEA results shown in FIG. 21A modified to show "true deflection" and reduced clearance to the impeller. [Figure 22A] FIG. 16 is a close-up side perspective view of finite element analysis (FEA) results color-coded by von Mises stress results (psi) for the narrow, four-strut impeller cage shown in FIG. 15 in accordance with an embodiment of the present invention. [Figure 22B] FIG. 22B is a greatly enlarged view of the proximal portion of the FEA results for the impeller cage shown in FIG. 22A. [Figure 22C] FIG. 22C is a close-up view of the proximal portion of the strut shown in FIG. 22B. [Figure 23A] FIG. 16 is a side perspective view of FEA results color-coded by deflection URES (mm) for the narrow four-strut impeller cage shown in FIG. 15, graphically showing deflections amplified by 70 times, in accordance with an embodiment of the present invention. [Figure 23B] FIG. 23B is a side perspective view of FIG. 23A modified to show "true deflection" and reduced clearance to the impeller. [Figure 24A] FIG. 17 is a close-up side perspective view of finite element analysis (FEA) results color-coded by von Mises stress results (psi) for the wide four-strut impeller cage shown in FIG. 16 in accordance with an embodiment of the present invention. [Figure 24B] FIG. 24B is a greatly enlarged view of the proximal portion of the FEA results for the impeller cage shown in FIG. 24A. [Figure 25A] FIG. 17 is a side perspective view of FEA results color-coded by deflection URES (mm) for the wide four-strut impeller cage shown in FIG. 16, graphically showing deflections amplified by 70 times, in accordance with an embodiment of the present invention. [Figure 25B] FIG. 25B is a side perspective view of FIG. 25A modified to show "true deflection" and reduced clearance to the impeller. [Figure 26A] FIG. 2 is a greatly enlarged side perspective view of an exemplary impeller housing / outlet cage, in accordance with an embodiment of the present invention. [Figure 26B] FIG. 26B is a greatly enlarged side view of the exemplary impeller housing / outlet cage shown in FIG. 26A. [Figure 27A] FIG. 10 is a greatly enlarged side perspective view of another exemplary impeller housing / outlet cage, in accordance with an embodiment of the present invention. [Figure 27B] FIG. 27B is a greatly enlarged side view of the exemplary impeller housing / outlet cage shown in FIG. 27A. DETAILED DESCRIPTION OF THE INVENTION

[0062] The present invention will now be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference characters refer to like elements throughout. The abbreviation "FIG." may be used interchangeably with "Fig." and the word "Figure" in the specification and drawings. It should be understood that features or operations of one embodiment may be described with respect to a particular embodiment and may also apply to other embodiments.

[0063] In the figures, the thickness of lines, layers, features, components, and / or regions may be exaggerated for clarity, and dashed lines (e.g., dashed lines indicated as ranges in flow diagrams) indicate optional features or operations unless otherwise noted. Furthermore, the order of operations (or steps) is not limited to the order presented in the claims unless another order is specifically indicated.

[0064] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present invention. As used herein, the singular forms "a," "an," and "the" are intended to encompass the plural forms as well, unless the context clearly dictates otherwise. Furthermore, it should be understood that the words "comprises" and / or "comprising," when used herein, specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0065] Unless otherwise defined, the meaning of all terms (including technical and scientific terms) used herein is the same as that commonly understood by one of ordinary skill in the art to which this invention belongs. It should be further understood that words and phrases, for example, those defined in commonly used dictionaries, should be interpreted as having a meaning consistent with the meaning of those words and phrases in the context of this specification and the related art, and should not be interpreted as idealized or overly formal unless expressly defined as such herein. Well-known functions and structures may not be described in detail for the sake of brevity and / or clarity.

[0066] It should be understood that when a feature, such as a layer, region, or substrate, is referred to as being "on" another feature or element, the feature may be directly on the other element, or there may be intervening elements. Conversely, when an element is referred to as being "directly on" another feature or element, there are no intervening elements. It should also be understood that when a feature or element is referred to as being "connected" or "coupled" to another feature or element, the element may be directly connected to the other element, or there may be intervening elements. Conversely, when a feature or element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements. Features so described or illustrated are described or illustrated with respect to one embodiment, but may also apply to other embodiments. The term "about" means that the stated numerical value may vary by ±20%.

[0067] 1 and 2, an exemplary blood pump 10 is shown. The blood pump 10 includes a motor 14, a multi-lumen shaft 30 enclosing a torque cable 25, an inlet cage 23 (blood intake), a (snorkel) tube 21 extending between the inlet cage 23 and an impeller 40, and an impeller housing / outlet cage 33 (pumped blood outlet). A snorkel 21s may be attached to the snorkel tube 21, which may be located at the distal end 10d of the blood pump 10. The snorkel / snorkel tube may be provided in several configurations. The snorkel tube 21 may be fused to or include a pigtail. The snorkel tube 21 may be fused distally to or include a circular 3D spacer. See U.S. Provisional Patent Application No. 63 / 518,163, filed August 8, 2023, the contents of which are incorporated herein by reference as if fully set forth herein.

[0068] The blood pump 10 may also include a manifold 110 coupled to the motor 14. The manifold 110 includes a manifold chamber. The manifold 110 may sealably enclose a portion of the length of the multi-lumen shaft 30 (typically, at least a portion of the proximal end portion 30p of the multi-lumen shaft 30) and may define at least a portion of the (purge) fluid inflow path of the multi-lumen shaft 30 that extends into at least one inflow lumen 133 provided by the multi-lumen shaft 30. The term "in-flow" may be used interchangeably herein with the term "inflow." The term "out-flow" may be used interchangeably herein with the term "outflow."

[0069] In the exemplary embodiment, the blood pump 10 may also include a bearing housing 50 adjacent the impeller 40 , with a bearing housing adapter 52 coupling the outer wall 30 w of the multi-lumen shaft 30 to the bearing housing 50 .

[0070] Multi-lumen shaft 30 has a proximal end portion 30p adjacent motor 14 and an opposite distal end portion 30d terminating next to impeller 40. Torque cable 25 also has a proximal end portion 25p adjacent motor 14 and an opposite distal end portion 25d terminating next to impeller 40. Torque cable 25 may also be referred to interchangeably as a "drive cable." Torque cable 25 may be attached, directly or indirectly, to impeller 40 at distal end portion 25d of torque (drive) cable 25 and may be attached, directly or indirectly, to motor 14 at proximal end portion 25p of torque (drive) cable 25.

[0071] The motor 14 may be held within a housing 16. The housing 16 may be provided as a cooperating pair of handle shells 16s.

[0072] The internal portion of the blood pump 10 (distal to the housing 16) is configured to be inserted into the aorta from a remote entry point (e.g., an incision below the groin, providing access into the femoral artery). The internal portion of the blood pump 10 (leading snorkel 21) then passes through the descending aorta and reaches the ascending aorta near the heart. The multi-lumen shaft 30 encloses the torque cable 25 and may be of sufficient length to position the motor 14 outside the body. The proximal end portion 30p of the multi-lumen shaft 30, at the end opposite the impeller 40 and snorkel 21, may reside outside the body (typically near the patient's groin).

[0073] In an exemplary operating configuration, the blood intake cage 23 and snorkel 21 reside in the left ventricle (LV) of the patient's heart, and the impeller 40 and blood outlet cage 33 (also referred to interchangeably herein as the "impeller cage") are located within the aorta above the aortic valve, immediately adjacent to the coronary arteries, for ejecting pumped blood into the aorta. The motor 14 may reside within the patient's body adjacent to the impeller 40, although having an extracorporeal motor may be preferable for improved torque output. Thus, in some embodiments, the motor 14 and motor housing 16 may be external to the patient's body.

[0074] Generally, when the proximal end portion of torque cable 25 is mechanically rotated by the motor shaft of motor 14 (typically outside the patient's body), the rotational force is transmitted along the length of multi-lumen shaft 30, causing impeller 40 to spin at high speeds within or near the heart.

[0075] The blood pump 10 may be particularly suitable for providing ventricular assist during surgery or for providing temporary bridge support to help a patient survive a crisis.

[0076] The motor 14 may be configured to drive a torque cable 25 within the multi-lumen shaft 30, which in turn drives the impeller 40 / pump unit. The motor 14 may be of any desired size, provided it operates outside the body. The multi-lumen shaft 30 provides constant lubrication with a biocompatible (purging) liquid. Some of this liquid may exit through the bearing housing / impeller shaft interface and enter the bloodstream. The remainder of the liquid may be directed through an outflow path and collected outside the body after passing through a lumen within the multi-lumen shaft 30 that holds the drive cable 25.

[0077] The dimensions of the multi-lumen shaft 30 and impeller 40 may be tailored to any suitable diameter for intravascular applications. For example, a size range may include, but is not necessarily limited to, 9 Fr to 30 Fr, with this range typically being 12 Fr to 24 Fr, and more typically being 12 Fr to 18 Fr. Thus, cardiologists can minimally invasively insert small CBP devices. In some preferred embodiments, the diameter may be 12 Fr (4.0 mm) or less, resulting in a low-profile device that may minimize bleeding.

[0078] The blood pump 10 may include first and second support wires 119, 219, which are longitudinally spaced apart within the torque cable 25. Referring to FIG. 1 , the first support wire 119 may terminate at its distal end 119e within a range of 1 to 3 inches from the manifold 110 and extend at least partially through the motor shaft. The second support wire 219 may terminate at its proximal end 219e within a range of 1 to 3 inches from the proximal end of the impeller shaft. The first support wire 119 may support the torque cable 25 in high torque locations (of the motor 14) to prevent the torque cable 25 from collapsing under load. The first support wire 119 may also act as a strain relief when it exits the distal end of the manifold 110. The second support wire 219 can allow the impeller shaft and torque cable 25 to be crimped together using a proximal bushing without crushing the (hollow) torque cable 25. The second support wire 219 can also act as a strain relief.

[0079] In some embodiments, the first and second support wires 119, 219 may be provided as a single support wire rather than separate support wires, and this single support wire may extend over substantially the entire length of the torque cable 25, or may be present only in the proximal end portion or only in the distal end portion of the torque cable 25.

[0080] Further details of the exemplary blood pump 10 are provided in co-pending U.S. Provisional Patent Application No. 63 / 374,426, filed September 2, 2022, and PCT / US23 / 21351, filed May 8, 2023, the contents of which are incorporated by reference as if fully set forth herein. However, the impeller 40 and outlet / impeller cage 33 may be used in other blood pump systems and are not limited to those disclosed in the above-referenced provisional patent applications.

[0081] 3A-3C, which illustrate a prior art blood pump impeller and cage, the present inventors have engaged in extensive research and development efforts to develop an impeller 40 having a novel impeller configuration and a novel configuration of impeller cage 33 that provides improved flow over the prior art impeller and cage shown in FIGS. 3A-3C, based on computational fluid dynamic (hydraulic) evaluation.

[0082] 4A-4E show examples of impellers 40 and impeller cages 33 according to embodiments of the present invention.

[0083] 7 is a table showing exemplary geometric and dimensional characteristics of the device shown in Figures 4A-4C (the column immediately to the left of the right-most column) and the prior art device shown in Figures 3A-3C (the right-most column). As known to those skilled in the art, slight changes in the size and / or configuration of the impeller and impeller cage, as well as their shape, can have a significant effect on the flow rate, hemolysis rate, and / or structural integrity of the device.

[0084] 4A-4C, 5A, and 5B, impeller 40 is mounted within impeller cage 33. Impeller cage 33 has a plurality of circumferentially spaced windows (i.e., openings) 34 separated by respective struts 36.

[0085] As shown, the impeller 40 has an impeller body 40b having impeller blades including a curved shape with a pair of vanes 47, each with an outlet blade portion 47s that may be aligned to fit within a respective window 34 between adjacent struts 36 of the impeller cage 33. The vanes 47 have respective outlet blade portions 47s that may project radially outward and have a constant maximum radius, thereby defining a radially maximum end (or edge) 47e that extends along the length of the window (W in FIG. 5A ). CAGE) and the distal end 47d of the outlet blade portion 47 is adjacent to or longitudinally aligned with the distal end 34d of the window 34. The proximal end 47p of the outlet blade portion 47 may terminate adjacent to or longitudinally aligned with the proximal end 34p of the window 34. The vane 47 with the outlet blade portion 47s may be structurally rigid and non-deformable during normal operation.

[0086] 5A, the distal end 47d of the straight portion of the outlet blade portion 47s may be a short distance "d" from the distal end 34d of the window 34, and typically the distal end 34d may be only 0.00 mm to about 0.05 mm distal to the distal end 47d. The proximal end 47p of the outlet blade portion 47s may be 0.00 mm to about 0.05 mm from the proximal end 34p of the window 34. The straight outlet blade portion 47s may be longitudinally spaced apart from the proximal end 34p of the window 34 by approximately the entire length W of the window 34. CAGE Aligning them can improve runoff and increase hydraulic efficiency.

[0087] 4D, each vane 471, 472 may have an outlet blade portion 47s with a constant maximum radius Rc measured from an axial centerline C / L AA of the impeller body 40b over a length L providing a straight section. In some embodiments, the length L may be in the range of 3.7 to 3.8 mm, for example, approximately 3.75 mm. Rc may be the same as the maximum outer diameter of the impeller 40. Rc may be approximately 2.15 mm. Rc may be approximately the same (±10%) as the maximum radius of the peak portion 44p.

[0088] Each outlet blade portion 47s may define a 90 degree outlet face facing the window 34 on all sides of the impeller blade, such that blood is directed through the entire longitudinal length W of the window 34. CAGE The pump 30 may be directed outwardly toward the window 34 over the entire length, which may improve pump performance.

[0089] Referring to Figures 4F-4I, the outlet blade portion 47s may define an outlet blade (outflow) angle β2 (β2B), which is equal to 90 degrees, which may improve pump performance. Figure 4F summarizes the calculation of the outlet angle relative to turbomachinery fundamentals (e.g., parameters), and as one skilled in the art will appreciate, efficiencies vary. Thus, in the context of a pump, the impeller outlet blade angle (which may also be referred to as the "outlet blade angle") refers to the angle between the blades (vanes) at the outer diameter of the impeller 40 and the circumferential (rotational) direction. Figures 4G-4I illustrate preferred outlet blade angles for impeller 40 according to embodiments of the present invention. As shown by the dashed lines (phantom lines) in Figures 4H and 4I, the outlet blade angle is 90 degrees and is defined by the intersection of the tangential direction (dashed line) at the outer diameter with the circumferential (rotational) direction.

[0090] Impeller 40 may have only two circumferentially spaced vanes 47, each with its own straight (uncurved) outlet blade portion 47s, and there may be fewer vanes 47 than windows 34, e.g., two impeller vanes 471, 472 and three windows 341, 342, 343. This configuration prevents pressure fluctuations that may occur if there were an equal number of vanes and struts.

[0091] The outlet blade portion 47s may be adjacent to, at, or distal to the distal end 34d of the window 34 and merge with the curved portion 45, which extends radially outward to a peak 44p portion that extends radially outward toward the nose 42 of the impeller blade 40b. The struts 36 may be parallel to the straight impeller outlet blade portion 47s of the vane 47 and the longitudinal centerline of the window.

[0092] The impeller cage 33 may have only three circumferentially spaced windows / openings 34, each with an open window area of ​​10-14 mm 2 For example, it is in the range of about 13.97 mm2 , which, according to operational model simulations, can provide lower pressure loss than the impeller cage shown in the prior art device of Figures 3A-3C with five smaller windows / openings (which are approximately half the size of the larger windows contemplated by embodiments of the present invention). Impeller cage 33 requires only three circumferentially spaced struts (361, 362, 363 in Figure 5B). Finite element analysis calculations confirm that with three windows 341, 342, 343 and three struts 361, 362, 363, impeller cage 33 has sufficient structural integrity to withstand typical cardiac pulsation forces and bending moments as it is deployed along a tortuous path to a desired location within the body.

[0093] The three windows 341, 342, 343 may have a cumulative total window area ranging from about 40 mm to about 43 mm, for example, about 41.91 mm.

[0094] The impeller cage 33 may be cylindrical and has an area ratio W corresponding to the ratio of window area to cylinder area. A / C A The window area may be defined as the cumulative surface area of ​​the windows 34, and the cylindrical area may be defined as the W of the cage 33 in FIG. 5A. CAGE is defined as the area of ​​the cylindrical portion of cage 33 surrounding window 34 (in area).

[0095] The window 34 may have an axial length in the range of 3.6 mm to 3.8 mm, preferably about 3.75 mm, and a circumferential angle in the range of about 80 to 98 degrees, preferably about 90 to 98 degrees, for example about 98 degrees.

[0096] The impeller cage 33 may have a proximal end 33p and an axially opposite distal end 33d. The impeller cage 33 may have an axial pump stage length L extending from the distal end 33d to the proximal end 34p of the window 34. STAGEThe impeller 40 may have an axial length L IMP , which may range from 9 mm to about 9.15 mm, and preferably about 9.15 mm. The impeller length is significantly longer (typically 1 mm or more longer) than the prior art device of Figures 3A-3C, which, according to operational model simulations, may improve pump performance.

[0097] Impeller 40 has a (distal) tip 42 that may be inside impeller cage 33, a short distance from distal end 33d of cage 33, or inside cage 33, or flush with distal end 33d of impeller cage 33. Tip 42 may be in the range of 0.07 mm to 0.1 mm from distal end 33d of impeller cage 33, typically about 0.075 mm.

[0098] 4A and 5A, the impeller 40 may have impeller blades 40b with a curved blade shape 41, when viewed from the side, extending longitudinally from the tip 42 of the impeller 40 to a proximal end 40p. The curved blade shape 41 includes a first curved portion 44 extending radially outward to a peak 44p where it merges with a second curved portion 45, and then extending radially inward to merge with an outlet blade portion 47. The first curved portion 44 tapers radially outward from an end 44e near the tip 42 to the peak 44p. The end 44e may be 0.1 mm to 0.3 mm from the tip 42, typically about 0.285 mm.

[0099] 4A and 5A, the outlet blade portion 47 has a constant maximum radius from the axial centerline AA of the impeller 40. The outlet blade portion 47s may be parallel to the axial centerline AA of the impeller 40 along the entire length of the outlet blade portion 47s. The length of the outlet blade portion 47 is determined by the axial length W of each window 34. CAGEand more typically, the axial length W CAGE It may be 70 to 110% of the above.

[0100] 5A and 5B, the impeller 40 has a maximum outer diameter D IMP The impeller cage 33 has an inner diameter "D CAGE " is D IMP In some embodiments, D CAGE may be 4.30 mm, and D IMP The impeller cage 33 may have a wall thickness (radial, front-to-back dimension) in some embodiments ranging from about 0.0097 inches to about 0.005 inches. The impeller cage 33 may be metal, for example, 304 stainless steel or 316L stainless steel. The blade clearance S at the maximum outer diameter of the impeller (corresponding to peak 44p) is TIP may be about 0.75 mm.

[0101] The impeller 40 has an axial length L IMP , which may range from about 8.5 mm to about 9.2 mm, and may typically be about 9.15 mm.

[0102] Impeller 40 may have an axial stage length of about 9.30 mm, which is about 0.05 mm shorter than the prior art device shown in Figure 6A.

[0103] Impeller 40 may have a major winding angle in the range of about 120 degrees to about 130 degrees, preferably 130 degrees, which is greater than the 113 degree winding angle of the prior art impeller shown in Figures 3A-3C.

[0104] Referring to Figure 10, the blades of impeller 40 may be longer than those of the prior art shown in Figures 3A-3C, thereby increasing the meridional flow surface by approximately 45%. The spatially curved meridional flow surface can be mapped to a plane by coordinate transformation. The coordinate system has the circumferential angle "t" as the abscissa and the dimensionless meridional extent "m" as the ordinate. Both quantities are generated by referencing the absolute meridional distance (M) and absolute tangential distance (T) with the local radius "r" as follows: dm=dM / r dt=dT / r tanβ=dm / dt where "m" is the meridional coordinate, "t" is the tangential coordinate, and m / max is the meridional coordinate associated with the meridional coordinate at the trailing edge.

[0105] 11 and 12, there are shown graphs of an axial pump comparison of the devices shown in Figures 3A and 4A. The line marked "PA" and the solid line with solid circles correspond to the baseline / prior art device shown in Figure 3A. The line with broken dashes corresponds to the device shown in Figure 4A.

[0106] Figure 11 shows a graph of the blade airfoil centerline (m, t) at the inner span, mid-span, and outer span of the impeller blade. Figure 12 shows the distribution of the blade angle β at the inner span, mid-span, and outer span of the impeller blade, i.e., β [°] against m / Max [%].

[0107] 13-16, side perspective views of an exemplary impeller cage 33 are shown, according to some embodiments of the present invention. FIG. 17 is a side perspective view of a prior art impeller cage. FIGs. 13-16 show exemplary struts 36, which are taller and fewer in number than the prior art device shown in FIG. 17.

[0108] Figure 13 shows a configuration with three struts 36, each with a narrow strut width "W" of approximately 0.4 mm. Figure 14 shows a configuration with three wider struts 36 than those in Figure 13, each with a width "W" of approximately 0.70 mm.

[0109] Figure 15 shows a configuration with four struts 36, each with a narrow strut width "W" of approximately 0.40 mm. Figure 16 shows a configuration with four wider struts 36 than those in Figure 15, each with a width "W" of approximately 0.70 mm.

[0110] A finite element analysis (FEA) was performed on various impeller cage 33 configurations to assess their structural integrity under load. The FEA assumed a 304 stainless steel (SS) hypotube cage structure. For the load analysis, a nylon tube was bonded to the SS impeller cage, and a bending moment was applied to the nylon tube during tortuous insertion through the anatomy. Loads during use were asymmetric, and the worst-case deflection direction was assumed for the analysis. Fillets were also removed, but corner fillets were retained, as in the prior art device of Figure 17. It was assumed that the inner and outer window fillets of Figures 13-16 have minimal effect on strut strength. The goal of the FEA was to determine the yield point of the load applied to the prior art design of Figure 17 and to evaluate the new, taller impeller cage with fewer struts, shown in Figures 13-16, using the same load. A load force 333F was applied to the distal end, i.e., tube 333. The radial wall thickness (front to back) in the FEA was based on a reference model (eg, a prior art device (FIG. 17)).

[0111] Referring to Figures 18A-18C, FEA results for the "narrow" three-strut 36 configuration of Figure 13 are shown, highlighting the maximum yield location, providing a color-coded overlay and legend (von Mises (psi)) of the yield range, and showing an imaginary plane. A 0.65 N load 333F was applied at the indicated location, resulting in a stress of 37 Kpsi (yield is 32 K) at the base 36b of each strut 36. Figures 19A-19B graphically illustrate the deflection of the impeller cage 33 and tube 333, magnified by 50 times, with color coding indicating the deflection (URES (mm)). Figure 19B shows the "true" deflection, with the clearance to the impeller reduced to approximately 0.03 mm.

[0112] Referring to FIGS. 20A-20C, FEA results for the "wide" three-strut 36 configuration of FIG. 14 are shown, highlighting the maximum yield location, providing a color-coded overlay and legend of the yield range (von Mises (psi)), and showing an imaginary plane. A 0.65 N load 333F was applied at the indicated location, resulting in a stress of 16 Kpsi (yield is 32 K) at the base 36b of each strut 36. FIGS. 21A-21B graphically illustrate the deflection of the impeller cage 33 and tube 333, magnified by 70 times, with color coding indicating the deflection (URES (mm)). FIG. 21B shows the "true" deflection, with the clearance to the impeller reduced to approximately 0.012 mm (baseline is approximately 0.007 mm).

[0113] Referring to Figures 22A-22C, FEA results for the "narrow" four-strut 36 configuration of Figure 15 are shown, highlighting the maximum yield location, providing a color-coded overlay and legend (von Mises (psi)) of the yield range, and showing an imaginary plane. A 0.65 N load 333F was applied at the indicated location, resulting in a stress of 53 Kpsi (yield is 32 K) at the base 36b of each strut 36. Figures 23A-23B graphically illustrate the deflection of the impeller cage 33 and tube 333, magnified by 70 times, with color coding indicating the deflection (URES (mm)). Figure 23B shows the "true" deflection, with the clearance to the impeller reduced to approximately 0.020 mm (baseline 0.007 mm).

[0114] Referring to Figures 24A-24C, FEA results for the "wide" four-strut 36 configuration of Figure 16 are shown, highlighting the maximum yield location, providing a color-coded overlay and legend of the yield range (von Mises (psi)), and showing an imaginary plane. A 0.65 N load 333F was applied at the indicated location, resulting in a stress of 15 Kpsi (yield is 32 K) at the base 36b of each strut 36. Figures 25A-25B graphically illustrate the deflection of the impeller cage 33 and tube 333, magnified by 50 times, with color coding indicating the deflection (URES (mm)). Figure 25B shows the "true" deflection, with the clearance to the impeller reduced to approximately 0.006 mm (baseline is 0.007 mm).

[0115] The blood pump 10 may be sized and configured for transvalvular applications (e.g., for left and / or right ventricular assist procedures). By way of example only, such ventricular assist procedures may be used in cardiac procedures, including, but not limited to, coronary artery bypass graft surgery (CABG), cardiopulmonary bypass surgery (CPB), open-chest and closed-chest (minimally invasive) surgery, bridge-to-transplant procedures, and / or treatment for failed weaning from bypass. However, it should be understood that the intravascular blood pump assembly and method of the present invention are not limited to such applications. Furthermore, while primarily illustrated and described with respect to left ventricular assist applications, it should be understood that the principles of the present invention apply equally to right ventricular assist applications, which are also contemplated within the scope of the present invention. These and other variations and additional features are described below.

[0116] The blood pump 10 may be configured to pump blood through the outlet cage 44 at a flow rate ranging from approximately 3.5 to 7 liters per minute for at least two hours, and in another embodiment, for continuous intravascular use for several days (e.g., six days or more). The operating configuration may also continuously supply a biocompatible fluid from at least one inflow lumen to the inflow pathway and to the outflow pathway.

[0117] The impeller 40 and / or cage 33 may be used with a blood pump 10 configured with an in vivo motor rather than an ex vivo (outside the body) motor.

[0118] The blood pump 10 may be configured to provide axial or mixed flow, and the term "axial flow" is intended herein to encompass flow characteristics that include both an axial component and a slight radial component.

[0119] The blood pump 10 may be configured to provide right and / or left ventricular assist, whereby blood is intentionally rerouted through the right and / or left ventricles to somehow reduce the amount of blood pumped by a particular ventricle. While "unloading" a ventricle in this manner may be desirable in some cases, it should be understood that the pump and cannula arrangements described herein may also be used to "preload" a ventricle. Preloading a ventricle can be achieved by placing an outflow cage from the pump within the desired ventricle so that the pump can be used to fill or prefill the ventricle with blood. This can be particularly useful in the case of the right ventricle. At times, the right ventricle is not supplied with a sufficient level of blood from the right atrium, resulting in an insufficient amount of blood being delivered from the right ventricle to the pulmonary artery during contraction. This can occur when the right ventricle and / or right atrium are under stress or strain during surgery. Preloading overcomes this problem. This is done by actively pumping blood into the right ventricle to facilitate delivery of blood to the pulmonary artery. The same technique can be used to preload the left ventricle, thereby facilitating delivery of blood from the left ventricle to the aorta.

[0120] In laboratory testing using water as a blood surrogate and a laboratory test system environment, an impeller and cage equivalent to that shown in FIG. 5A and a prior art impeller and cage shown in FIG. 6A were evaluated for flow rate (liters per minute) over a range of pressures (mmHg) from 40 mmHg to 140 mmHg at 50,000 rpm. The impeller and cage of the present invention generated improved flow rates over that of the prior art shown in FIG. 6A throughout this range. Furthermore, while pumping against a clinically typical pressure differential of 100 mmHg, the catheter blood pump of the present invention was capable of delivering a continuous flow of approximately 3.7 liters per minute, which is considered a 23.33% increase over that of the prior art shown in FIG. 6A, which is significant and clinically meaningful, potentially representing the difference between recovery and failure to recover.

[0121] Hemolysis is the breakdown of red blood cells. The ability to minimize hemolysis is important. Computer model evaluation of the catheter blood pumps of the present invention indicates that they cause less hemolysis than the prior art devices shown in Figures 3A-3C, even while delivering greater flow rates over longer continuous periods (including but not limited to lower peak output volumes). In animal studies of a catheter blood pump (CBP) using the cage and impeller configuration shown in Figure 5A, the animals' hematocrit (a measure of red blood cell mass) did not decrease over the two-hour study. In humans, physicians typically use CBPs for periods of two hours or less.

[0122] 26A and 26B show close-up views of an exemplary impeller (outlet) cage 33. The window 34 has a proximal end 34p and a distal end 34d. In this embodiment, two pairs of three struts 36 form the long perimeter of the window. The relatively large opening of the window 34 provides a large (unobstructed) exit path for pumped blood. The struts 36 may have flat surfaces 36f between their inner and outer edges 36i and 36o, and the lateral boundary walls 34w of the window 34 may also have flat surfaces 34f. The window 34 may have rounded corners 34c that blend the struts 36 with the lateral boundary walls 34w. The window 34 may have straight lateral portions between the corners 34c (this contrasts with the smaller longitudinally arcuate windows of prior art housings shown, for example, in FIGS. 3A and 6A).

[0123] One of the struts 36 may have an axially extending recess or channel that can be used to guide the pressure sensor wire into the inflow cage 23 (FIG. 1). For example, the impeller cage 33 may have a stepped configuration such that the outer diameter of the distal end portion is smaller than the outer diameter at the location of the strut 36. The polymer and / or plastic tube of the snorkel 21 (FIG. 1) may be glued or bonded to this reduced outer diameter portion. The snorkel tube 21 may also have an internal or external channel or recess aligned to guide the pressure sensor wire into the inflow cage 23.

[0124] Figures 27A and 27B show an impeller (outlet cage) 33, which is similar to Figures 26A and 26B, but shows rounded surfaces 36r, 34r instead of flat surfaces 34f, 36f. Rounding sharp edges to avoid sharp corners and edges is a well-known manufacturing / design option for devices, as is well known to those skilled in the art.

[0125] Notably, computer model evaluation of the struts 36 of Figures 26A, 26B and 27A, 27B showed minimal differences in hemolysis. Without wishing to be bound by any particular theory, this may be due to the relatively large windows 34 and / or the shape and position of the outlet blades 47 (Figure 6A) such that there is no significant interaction between the struts 36 and the blood flow from the outlet blades 47 (Figure 6A), regardless of whether the struts 36 have flat surfaces 36f (Figures 26A, 26B) or rounded surfaces 36r (Figures 27A, 27B).

[0126] In the drawings and specification, there have been disclosed embodiments of the invention, and although specific terms have been used, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.

[0127] Therefore, the foregoing is illustrative of the present invention and should not be construed as limiting thereof. Although only a few exemplary embodiments of the present invention have been described, those skilled in the art will readily appreciate that various modifications can be made in those exemplary embodiments without substantially departing from the novel teachings and advantages of the present invention.

[0128] Accordingly, all such modifications are intended to be included within the scope of the present invention as defined in the claims. In the claims, means-plus-function clauses are intended to cover structures described herein as performing the recited function and to encompass not only structural equivalents but also equivalent structures. Therefore, it should be understood that the foregoing is an illustration of the present invention and should not be construed as limited to the particular embodiments disclosed; modifications of the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims. The present invention is defined by the following claims, with equivalents of the claims to be encompassed therein.

Claims

1. 1. An impeller for a blood pump, comprising: An impeller body having a curvilinear shape extending from a distal nose portion to a pair of vanes located proximal to the distal nose portion, each vane having an outlet blade portion, the outlet blade portion having a maximum radius measured from an axial centerline of the impeller body that is constant over the length of the outlet blade portion. Including an impeller.

2. The impeller of claim 1 , wherein the length is in the range of about 3.7 mm to about 3.8 mm.

3. The impeller of claim 1 , wherein the outlet blade portion is perpendicular to the axially extending centerline throughout its span.

4. 10. The impeller of claim 1, wherein the axial length is about 9.15 mm.

5. 10. The impeller of claim 1, wherein the wrap angle is about 130 degrees.

6. The impeller of claim 1 , in combination with an impeller cage at least partially surrounding the impeller body, the outlet blade portion being longitudinally aligned with a cage window of the impeller cage.

7. 7. The impeller of claim 6, wherein the impeller cage has only three windows, the windows being longitudinally aligned and circumferentially spaced apart, and the impeller cage has only three struts, the three struts being longitudinally aligned and circumferentially spaced apart.

8. The three windows have a length extending in a longitudinal direction and a width extending in a circumferential direction to define a window area, and the window area of ​​each window is about 10 mm ２ ~ approx. 14 mm ２ 7. The impeller of claim 6, wherein the impeller has a diameter in the range of 1 / 2.

9. 7. The impeller of claim 6, wherein the outlet blade portion has a length that is approximately 80-110% of the length of the window, and the outlet blade portion defines a 90 degree outlet flow angle.

10. The impeller of claim 8 , wherein the length of the outlet blade portion is the same as the longitudinal extent of the three windows.

11. The impeller according to claim 6, wherein the cage window has an outer peripheral angle extending in the circumferential direction in the range of 90 to 100 degrees.

12. The impeller of claim 11 , wherein the circumferentially extending peripheral angle is 98 degrees.

13. The impeller of claim 1 , wherein the impeller body has an overall length in the range of about 8.5 mm to about 9.5 mm.

14. 10. The impeller of claim 1, wherein the overall length is about 9.15 mm.

15. 2. The impeller of claim 1, wherein the impeller tapers proximally outward from the nose portion of each of the vanes to a respective peak portion, after which the vanes taper proximally radially inward to blend with the corresponding outlet blade.

16. The impeller cage has a stage length (L ＳＴＡＧＥ 7. The impeller of claim 6, wherein the stage length is greater than the overall length of the impeller but less than the overall length of the impeller plus 0.25 mm.

17. 12. The impeller of claim 11, further comprising an impeller cage surrounding the impeller, wherein the gap distance between an inner surface of the impeller cage and the peak portion is about 0.75 mm.

18. The impeller of claim 1 , wherein the impeller has a maximum outer diameter of 4.15 mm.

19. The impeller of claim 6 , wherein the impeller cage has a window area / cylinder area ratio of 0.8043.

20. The impeller of claim 6 , wherein the outlet blade portion terminates adjacent a proximal end of the window.

21. 1. An impeller assembly for a catheter blood pump, comprising: an impeller including a curvilinear shape extending from a distal nose portion to a pair of vanes extending proximally of the distal nose portion, each vane having an outlet blade portion having a maximum radius measured from an axially extending centerline of the impeller body that is constant over the length of the outlet blade portion; an impeller cage at least partially surrounding the impeller, the outlet blade portion being longitudinally aligned with a cage window of the impeller cage; an impeller assembly including:

22. 22. The impeller assembly of claim 21, wherein the impeller cage has only three windows, the windows being longitudinally aligned and spaced circumferentially apart by three struts, the three struts being longitudinally aligned and spaced circumferentially apart.

23. Each of the three windows has a length extending in a longitudinal direction and a width extending in a circumferential direction, thereby defining a respective window area, and the window area of ​​each window is 10 mm ２ ~14mm ２ 22. The impeller assembly of claim 21, wherein the impeller width is in the range of

24. 22. The impeller assembly of claim 21, wherein the outlet blade portion has a length that is approximately 80-110% of a length of the window, and wherein the outlet blade portion defines an outlet flow angle of 90 degrees.

25. 22. The impeller assembly of claim 21, wherein the length of the outlet blade portion is the same as the length of the cage window.

26. The impeller assembly of claim 21 , wherein the cage window has a circumferential angle in the range of approximately 90 to 100 degrees.

27. 27. The impeller assembly of claim 26, wherein the circumferential angle is 98 degrees.

28. The impeller assembly of claim 21 , wherein the impeller has an overall length in the range of about 8.5 mm to about 9.5 mm.

29. 22. The impeller assembly of claim 21, wherein the impeller has an overall length of about 9.15 mm.

30. 22. The impeller assembly of claim 21, wherein the impeller tapers outward from the nose portion to first and second peak portions, then tapers radially inward proximally to merge with the outlet blades, the outlet blade portions extending 85-110% of the length of the window in the impeller cage.

31. The cage has a stage length (L ＳＴＡＧＥ 22. The impeller assembly of claim 21, wherein the stage length is greater than the overall length of the impeller but less than the overall length of the impeller plus 0.25 mm.

32. 31. The impeller assembly of claim 30, wherein the gap distance between the inner surface of the impeller cage and the peak portion is about 0.75 mm.

33. 22. The impeller assembly of claim 21, wherein the impeller has a maximum outer diameter of 4.15 mm.

34. 22. The impeller assembly of claim 21, wherein the impeller cage has a window area / cylinder area ratio of 0.8043.

35. 22. The impeller assembly of claim 21, wherein the outlet blade portion terminates adjacent a proximal end of the window, the window having upper and lower peripheries that extend straight in the circumferential dimension.

36. An impeller cage for a catheter blood pump, the impeller cage having only three windows and only three struts, the windows being aligned longitudinally and spaced circumferentially apart, and the struts being aligned longitudinally and spaced circumferentially apart by pairs of the three struts on opposite sides of each window.

37. The three windows have a length extending in a longitudinal direction and a width extending in a circumferential direction, thereby defining a window area, and the window area of ​​each window is 10 mm ２ ~14mm ２ 37. The impeller cage of claim 36, wherein the impeller cage has a diameter in the range of

38. The impeller cage according to claim 36, wherein each of the three windows has an outer peripheral angle in the circumferential direction in the range of 90 to 100 degrees.

39. 37. The impeller cage of claim 36, wherein the circumferential outer periphery angle is 98 degrees.

40. 37. The impeller cage of claim 36, wherein the three struts have a circumferential width ranging from about 0.40 mm to about 0.70 mm and a longitudinal length ranging from 3.7 mm to 4.0 mm.

41. 41. The impeller cage of claim 40, wherein the longitudinal extension is 3.75 mm.

42. 37. The impeller cage of claim 36, wherein the window has upper and lower peripheries that extend straight in the circumferential dimension.

43. 1. An in vivo impeller for a blood pump, comprising:

1. An impeller body configured such that the angle of the straight exit blades is 90 degrees over at least 30% of the length of the impeller body. An in vivo impeller comprising:

Images