Intravascular blood pump with intake filter

Abstract

An intravascular blood pump having an intake filter that reduces the risk of cardiac tissue being aspirated into the pump's intake port. The filter defines a plurality of apertures through which blood flows and passes through the filter. The apertures are sized to prevent cardiac tissue from being aspirated by the input port. The filter includes a plurality of generally helical first struts wound around the longitudinal axis of the filter and a plurality of second struts. The first and second struts collectively define the plurality of apertures therebetween. The struts may be woven filaments; alternatively, the apertures may be defined in a thin film (foil) tube, with the material remaining between the apertures forming the struts. TIFF2023514544000002.tif53166

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 62 / 970,004, filed on February 4, 2021, the entire disclosure of which is incorporated herein by reference.

[0002] Technical Field The present invention relates to an intravascular blood pump, and more specifically, to an intravascular blood pump including an intake filter.

Background Art

[0003] Background An intravascular blood pump is a pump that can be advanced through a patient's blood circulation system, i.e., through veins and / or arteries, to a position within the patient's heart or to other locations within the patient's circulatory system. For example, an intravascular blood pump may be inserted via a catheter and positioned to straddle a heart valve. An intravascular blood pump is typically disposed at the end of a catheter. Once in a predetermined position, the pump may be used to pump blood through the circulatory system and thereby temporarily reduce the workload on the patient's heart, such as to enable the heart to recover after a heart attack.

[0004] A typical intravascular blood pump includes an impeller disposed within a pump housing. When rotating, the impeller draws blood into an intake port and expels the blood through an output port. In some cases, the impeller is driven by an electric motor disposed within the intravascular blood pump via a relatively short drive shaft. In other cases, the impeller is driven by a relatively long flexible drive shaft that extends through the catheter to a motor outside the patient's body. In either case, during operation, the impeller and the drive shaft rotate at a relatively high speed.

[0005] In use, the intake port may be relatively close to the inner wall of the heart chamber. As a result, there is a risk that the spinning impeller will draw heart tissue, such as trabeculae or chordae tendineae, into the intake port. If heart tissue is sucked into the intake port, it can result in damage to the heart tissue, damage to the intravascular blood pump, and / or an increased risk of blood clotting. The heart tissue may become entangled around the drive shaft, which can lead to damage to the heart tissue and / or stalling of the pump. Thus, one technical problem is how to prevent the suction of heart tissue into the intake port of the intravascular blood pump. Accordingly, there is a need for an intravascular blood pump that reduces the risk of heart tissue being drawn into the intake port. SUMMARY OF THE INVENTION

[0006] SUMMARY OF ASPECTS One aspect of the present invention provides an intravascular blood pump. The intravascular blood pump includes a catheter, a pump housing, an impeller, and a filter. The catheter is configured for insertion into a blood vessel. The blood vessel defines an internal volume through which blood flows. The pump housing is attached to the catheter. The pump housing defines an input port and an output port. The pump housing has a longitudinal axis. The impeller is disposed within the pump housing. The impeller is configured to pump blood from the input port to the output port when rotating.

[0007] The filter is in fluid communication between (a) the internal volume of the blood vessel outside the pump housing and (b) the input port. The filter includes a plurality of generally helical first struts. The plurality of generally helical first struts are wound around the longitudinal axis. The filter also includes a plurality of second struts. The first and second struts collectively define a plurality of apertures therebetween.

[0008] In any aspect, the pump housing, the impeller, and the filter may each be alternately compressible and extensible in the radial direction. In any aspect, the pump housing, the impeller, and the filter may each be configured to alternately undergo radial compression and radial extension.

[0009] In any aspect where the pump housing is compressible or configured to be compressed, the pump housing may be configured to extend longitudinally by an amount corresponding to the amount of radial compression of the pump housing when radially compressed. In such an aspect, the pump housing extends longitudinally by an amount corresponding to the amount of radial compression of the pump housing when radially compressed. In such an aspect, the filter is configured to extend longitudinally by an amount corresponding to the amount of radial compression of the filter when radially compressed such that for a given amount of radial compression, the filter and the pump housing extend longitudinally by approximately equal amounts. In such an aspect, the filter is configured to extend longitudinally by an amount corresponding to the amount of radial compression of the filter when radially compressed such that for a given amount of radial compression, the filter and the pump housing extend longitudinally by approximately equal amounts.

[0010] In any aspect, the catheter, the pump housing, the impeller, and the filter may be configured to be used or may be used within the body of a living patient. Each of the plurality of apertures may be sized to prevent suction of the heart tissue of the living patient by the input port.

[0011] In any aspect, each of the plurality of apertures may have a maximum dimension equal to or less than about 0.5 mm, or equal to or less than about 0.4 mm.

[0012] In any aspect, each of the plurality of apertures is about 0.09 mm 2may be equal to or less than, or about 0.16 mm 2 and may have an area equal to or less than that.

[0013] In any embodiment, the aperture size of the plurality of apertures may increase along the vertical axis. The increase may be monotonic, but does not necessarily have to be. The increase may be monotonic.

[0014] In any embodiment, the first strut may be wound clockwise around the vertical axis. The second strut may be wound generally spirally counterclockwise around the vertical axis.

[0015] In any embodiment having a first strut wound generally spirally, the first strut may be wound in a first direction around the vertical axis, and the second strut may be wound generally spirally in the first direction around the vertical axis. That is, the first and second struts may be wound in the same direction.

[0016] In any embodiment having a first strut wound generally spirally, each strut of at least a subset of the second struts may be in a respective plane containing the vertical axis.

[0017] In any embodiment, each aperture of at least a subset of the plurality of apertures may have a generally rhombic or obliquely rhombic shape.

[0018] In any aspect, the first strut may include a plurality of first filaments. The second strut may include a plurality of second filaments. The first and second filaments may be woven together such that the plurality of apertures are defined between respective adjacent first and second woven filaments. Although reference is made to first and second filaments, a single continuous filament, such as a single continuous wire, may function as both the first and second filaments. Separate portions of a single filament may function as the first and second filaments. Those separate portions need not be continuous. For example, alternating portions of a single filament may function as the first filament, and the portions of the single filament therebetween may function as the second filament.

[0019] In some aspects, the filter may include a tube. The tube has a wall. The plurality of apertures includes a plurality of openings defined through the wall.

[0020] In any aspect having a filter including a tube, the tube may include a generally funnel-shaped tube.

[0021] In any aspect having a filter including a tube, the wall may be about 10 to 100 μm thick.

[0022] In any aspect having a filter including a tube, the pump housing may include a plurality of third struts. The third struts collectively define a plurality of third apertures therebetween. At least some of the first and second struts may be radially aligned on respective ones of the third struts.

[0023] In any embodiment having a filter including a tube, each strut of at least a subset of the first struts may include a fork. The fork may include a plurality of teeth. A plurality of first struts and a plurality of second struts may extend between pairs of teeth and may collectively define a plurality of apertures therebetween.

[0024] In any embodiment having a forked strut within a filter, each first strut including a fork may be wider than each first strut not including a fork.

[0025] In any embodiment having a filter including a tube, the apertures may be arranged in a plurality of generally circumferential rows. The rows are circumferential with respect to the longitudinal axis. The rows may have apertures of equal size. Some of the rows may have a different number of apertures than other rows.

[0026] In any embodiment having generally circumferential rows, a first row of the plurality of generally circumferential rows may include more apertures than a second row of the plurality of generally circumferential rows. Each aperture of the first row may have a smaller area than each aperture of the second row.

[0027] In any embodiment having generally circumferential rows, the apertures may be arranged in a plurality of generally circumferential bands. The bands may be circumferential with respect to the longitudinal axis. The bands may have apertures of approximately equal size. The size of the apertures in each of the plurality of bands may increase along the longitudinal axis. The increase may be monotonic, but need not necessarily be so. The filter may have a distal portion and a proximal portion. The distal portion may have a diameter that monotonically increases in the proximal direction along the longitudinal axis. The proximal portion may have a diameter that monotonically decreases in the proximal direction along the longitudinal axis. At least a portion of the plurality of apertures may be disposed on the distal portion. In some embodiments, there are no apertures in the proximal portion.

[0028] In any aspect, the first struts and the second struts may lack struts that are circumferential with respect to the longitudinal axis. Each first strut and each second strut may form a non-zero angle with a virtual ring that is circumferential with respect to the longitudinal axis, respectively.

[0029] Another aspect of the present invention provides a method for making a filter for an intravascular blood pump. A catheter is provided. The catheter is configured for insertion into a blood vessel. The blood vessel defines an internal volume through which blood flows. A pump housing is attached to the catheter. The pump housing defines an input port and an output port. The pump housing has a longitudinal axis. An impeller is disposed within the pump housing. The impeller is configured to pump blood from the input port to the output port when rotating.

[0030] A filter is provided in fluid communication between (a) the internal volume of the blood vessel outside the pump housing and (b) the input port. The filter includes a plurality of generally helical first struts wound around the longitudinal axis. The filter also includes a plurality of second struts. The first and second struts collectively define a plurality of apertures therebetween.

[0031] In any such method, the filter may include a woven filter.

[0032] In any such method, the filter may include a filter of a molded tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be more fully understood by reference to the following detailed description of specific embodiments in conjunction with the accompanying drawings. The present invention will be described by way of example with reference to the accompanying drawings. The accompanying drawings are not necessarily to scale. In the drawings, the same or corresponding components shown in the various figures are represented by the same numerals. For clarity, not all components may be labeled in all of the figures.

[0034]

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DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS Aspects of the present invention provide an intravascular blood pump having an intake filter that reduces the risk of cardiac tissue being aspirated into the intake port of the intravascular blood pump. The filter defines a plurality of apertures through which blood flows through the filter. The apertures are sized to prevent aspiration of cardiac tissue of a living patient or a living animal patient by the input port.

[0036] The intravascular blood pump is configured for insertion into a patient's blood vessel. For example, the intravascular blood pump may be configured for percutaneous insertion into a patient's femoral artery and guided through the patient's vasculature to the heart, for example, to support and / or replace the pumping action of the heart.

[0037] The filter is in fluid communication between (a) the internal volume of the blood vessel outside the intravascular blood pump and (b) the input port. The filter includes a plurality of generally helical first struts wound around the longitudinal axis of the intravascular blood pump. The filter also includes a plurality of second struts. The first and second struts collectively define a plurality of apertures therebetween through which blood is drawn into the input port.

[0038] In some embodiments, the first and second struts are individual filaments, such as wires, woven together in a relatively coarse weave. In other embodiments, the filter includes a shaped foil tube having apertures defined therein. The apertures are positioned on the tube such that the material between the apertures forms the first and second struts.

[0039] The present invention will be described in the context of an intravascular blood pump having an expandable housing in which an expandable impeller is stored and driven by an extracorporeal motor via a long flexible drive shaft. However, the present invention is also applicable to other types of intravascular blood pumps, such as intravascular blood pumps having a non-expandable housing and / or intravascular blood pumps having a motor located within a patient's body.

[0040] Expandable intravascular blood pumps are known, for example, as described in U.S. Patent Application Publication No. 2013 / 0303969 (the '969 application) and U.S. Patent No. 8,439,859 (the '859 patent), the entire contents of each of which are hereby incorporated by reference for all purposes. The '969 patent describes a catheter-pump-assembly. An expandable housing is located at the distal end of the catheter. The expandable housing surrounds an expandable impeller driven by a flexible drive shaft. The drive shaft extends through a first lumen of the catheter. The distal portion of the catheter-pump-assembly may be placed inside the heart via percutaneous access, such as using the Seldinger technique. The drive shaft contains a central lumen; the central lumen may allow a guide wire to be passed therethrough along with its guide through the drive shaft to enable accurate positioning of the catheter pump assembly inside the heart. The impeller may be rotatably supported within a proximal bearing arranged at the catheter end and in the vicinity of the impeller.

[0041] Expandable intravascular blood pump FIG. 1 is a partial cutaway view of an expandable intravascular blood pump 100 positioned within the left ventricle 102 of a patient's heart 104. In other applications, the expandable intravascular blood pump 100 may be positioned in other locations within the patient's body, such as within the left atrium or other locations within the patient's vasculature that are not necessarily within the heart 104. The intravascular blood pump 100 includes a catheter 106 and a pump section 108 disposed at or near the end of the catheter 106. The catheter 106 is configured for insertion into a blood vessel, such as the aorta 110, that defines an internal volume 112; blood flows through the internal volume 112 in a blood flow direction, such as the direction indicated by arrow 114. As used herein, the term "blood vessel" includes a cardiac chamber or other lumen. The catheter 106 is connected to a controller 116, such as an Automatic Impella Controller ("AIC") available from Abiomed, Inc., Danvers, MA 01923. The controller 116 provides a user interface for controlling and monitoring the intravascular blood pump 100.

[0042] As indicated by the arrow in FIG. 1, as used herein, the term "distal" refers to a direction or position away from the controller 116 or the user of the controller 116 along the catheter 106, and the term "proximal" refers to a direction or position toward the controller 116 or the user of the controller 116 along the catheter 106.

[0043] During insertion, as shown in FIG. 1, the intravascular blood pump 100 may be positioned to extend through the aortic valve 118. However, in other applications, the intravascular blood pump 100 may be positioned at other locations within the vasculature of a patient that are not necessarily within the heart 104. Further, FIG. 1 depicts the intravascular blood pump 100 inserted such that the blood flow direction 114 is away from the distal end of the catheter 106. However, in other applications, the intravascular blood pump 100 may be inserted such that the blood flow direction 114 is toward the distal end of the catheter 106. For example, the intravascular blood pump 100 may be inserted from the left atrium, through the mitral valve, and into the left ventricle 102. In the application depicted in FIG. 1, the valve leaflets of the aortic valve 118 close around the intravascular blood pump 100.

[0044] The intravascular blood pump 100 may be placed inside the heart 104 using percutaneous and transluminal techniques. For example, the intravascular blood pump 100 may be introduced through the femoral artery (not shown). However, alternative vascular accesses, such as access through the subclavian artery, are equally possible. After passing through the femoral artery, the catheter 106 may be pushed into the aorta 110 such that the pump section 108 reaches inside the heart 104 through the aortic valve 118. The positioning of the pump section 108 in FIG. 1 is merely an example, and different placements, such as positioning the pump section 108 inside the right ventricle of the heart 104, are possible.

[0045] A flexible atraumatic tip 120 having a configuration such as a pigtail or J-shape extends distally from the distal end of the pump section 108. The atraumatic tip 120 needs to be sufficiently flexible so that the pump section 108 can abut against the inner wall of the left ventricle 102 in an atraumatic manner and support itself.

[0046] The pump section 108 includes an impeller (not visible in the figure) disposed within the housing 122. The housing 122 and the impeller may be extensible, but need not necessarily be so. The impeller may be mechanically coupled to an external motor 124 via a flexible drive shaft (not shown) that extends through the catheter 106. The motor 124 may be within the controller 116 or elsewhere. Alternatively, the impeller may be mechanically coupled to a motor (not shown) disposed within the pump section 108 via a relatively short drive shaft (not shown). In either case, the motor rotates the impeller via the drive shaft so that blood from the internal volume 112 flows from the blood flow inlet (input port) 126 at the distal end of the pump section 108 to the blood flow outlet (output port) 128 located downstream of the blood flow inlet 126, as indicated by the arrow. As described above, the term "interior volume" 112 includes heart cavities such as the left ventricle 102.

[0047] The filter 130 is disposed in fluid communication between (a) the internal volume 112 of a blood vessel external to the pump housing 122, which in this case is the left ventricle 102, and (b) the input port 126. The filter 130 will be described in the context of the extensible housing 122 and the impeller, but the filter 130 may also be used with a non-extensible housing 122 and impeller.

[0048] Figure 2 is a more detailed partial cutaway side view of the intravascular blood pump 100, including the catheter 106. The impeller 200 is shown located within the housing 122 and mechanically coupled to the motor 124 via a flexible drive shaft 202.

[0049] FIG. 2 also shows a flexible collapsible outflow hose (downstream tubing) 204 that provides fluid communication between the output of the impeller 200 and the output port 128. As seen in FIG. 1, the pump section 108 is positioned such that the aortic valve 118 closes on the downstream tubing 204. The downstream tubing 204 is flexible enough that the aortic valve 118 can collapse it against the catheter 106 when the left ventricle 102 finishes contracting and begins to relax. Closure of the aortic valve 118 prevents blood from flowing back into the left ventricle 102.

[0050] Conventionally, intravascular blood pumps have not included such downstream tubing. Thus, such conventional intravascular blood pumps have a relatively long intake cannula upstream of the impeller to make the intravascular blood pump long enough to span the cardiac valve at the insertion site. This length allows for some longitudinal displacement due to cardiac motion and patient movement, etc., without the risk of displacing the intake port and the output port to the same side of the cardiac valve. Such a long intake cannula also makes it nearly impossible to damage cardiac tissue by the impeller, although it was not intentionally designed that way. However, such a long intake cannula results in hydraulic losses, which are particularly problematic in the suction tube.

[0051] The downstream tubing solves the problem of hydraulic losses by making it possible to position the impeller much closer to the input port. However, this position of the impeller increases the risk of damaging cardiac tissue and also increases the risk of cardiac tissue getting entangled around the impeller or drive shaft, which can stall the pump. To avoid this, a filter 130 is placed on the input port. It was not previously recognized that positioning the impeller close to the intake port increases the risk of cardiac tissue damage or pump stall.

[0052] Figures 3 and 4 are enlarged side views of the expandable housing 122 and the expandable filter 130 of the intravascular blood pump 100. FIG. 3 shows the expandable housing 122 and the expandable filter 130 in an expanded state, and FIG. 4 shows them in a compressed state. When the housing 122 and the impeller 200 are expandable, the housing 122 may include a plurality of struts represented by struts 300, 302, and 304 made of a suitable shape memory and highly elastic or superelastic material such as Nitinol. Highly elastic materials are typically elastomers. Many of such elastomers can be elastically deformed up to about 100% at most. Some of the superelastic materials can be elastically deformed up to about 6-8% at most. Nitinol is a trade name for a nickel-titanium alloy that is distinguished from other materials by its shape memory properties and superelastic properties.

[0053] Struts 300-304 may be made of wire or other filaments. As shown in FIGS. 3 and 4, the housing 122 provides a cage around the impeller 200. When expanded radially (FIG. 3), the length 306 of the housing 122 may be shorter than the length 400 when the housing 122 is compressed radially (FIG. 4). The change from length 400 to 306 may be due to the struts 300-304 unwinding when the housing 122 expands. In some embodiments, the change from length 400 to 306 may be about 1-2 mm.

[0054] The expandable housing 122, the expandable impeller 200, and the expandable filter 130 may be kept in a compressed state by a suitable compression sleeve 308 slid over the expandable housing 122, the expandable impeller 200, and the expandable filter 130. The intravascular blood pump 100, together with the expandable housing 122, the expandable impeller 200, and the expandable filter 130, may be transported through the patient's vasculature while the housing 122, the impeller 200, and the filter 130 are in a compressed state. Once the pump section 108 reaches the target position, the housing 122, the impeller 200, and the filter 130 can be expanded, for example, by pushing the pump section 108 in the forward (distal) direction out of the compression sleeve 308 or pulling back the compression sleeve 308 (in the proximal direction). When the compression sleeve 308 is removed, as shown in FIG. 3, the housing 122 expands due to its shape memory and superelastic or highly elastic properties. At the same time, the impeller 200 expands due to its elasticity. As the housing 122 expands radially away from the drive shaft 202, it may contract longitudinally to a length 306.

[0055] The inner central portion of the housing 122 may have a sleeve or coating 310 (best seen in FIG. 11) that defines a channel through which blood is pumped by the impeller 200. At the proximal and distal sides of this channel, the housing 122 enables blood to be drawn into the housing 122 and to be pushed out of the housing 122 and into the downstream tubing 204 (FIG. 2), respectively.

[0056] When the intravascular blood pump 100 is in an extended state and needs to be removed from the patient, the housing 122 is retracted into the compression cannula 308, which compresses the housing 122 radially; and it may also longitudinally extend the housing 122 up to a length of 400. The filter 130 and the impeller 200 are also compressed. The smaller diameter of the housing 122 thus realized facilitates removing the intravascular blood pump 100 from the patient through the vascular structure. Thus, the pump housing 122, the impeller 200, and the filter 130 are each configured to alternately undergo radial compression and radial extension. Additional details of the expandable intravascular blood pump are provided in the '859 patent.

[0057] FIG. 5 is a cross-sectional view of the expandable housing 122 and the expandable mesh filter 130 of FIGS. 3 and 4 in an extended state. The housing 122 includes several parts connected to each other. These parts are, from proximal to distal, a proximal tubular housing portion 500, a proximal tapered housing portion 502, an intermediate tubular housing portion 504, a distal tapered housing portion 506, and a distal tubular housing portion 508. As used herein, "tapered" means having a shape in which the outer diameter changes smoothly and monotonically, but not necessarily linearly. Thus, the tapered shape may include convex and / or concave portions in the profile. Being tapered includes, but is not limited to, being conical.

[0058] The proximal tubular housing portion 500 is connected to the catheter 106 and contains the proximal bearing 510. The proximal tubular housing portion 500 has an essentially cylindrical shape. The proximal tapered housing portion 502 connects the intermediate tubular housing portion 504 to the proximal tubular housing portion 500. The intermediate tubular housing portion 504 has an approximately cylindrical shape and surrounds the impeller 200. The exact cross-sectional shape of the intermediate tubular housing portion 504 may depend on the number of struts 300-304 in the housing 122. Generally, its cross-sectional shape may be a polygon that may also have rounded corners.

[0059] The distal tapered housing portion 506 connects the intermediate tubular housing portion 504 to the distal tubular housing portion 508 and defines the blood flow inlet (inlet port) 126 of the housing 122. The proximal tapered housing portion 502 has a cross-section that is nearly circular, and its radius increases in the distal direction. Similar to the intermediate tubular housing portion 504, the exact cross-sectional shape of the proximal tapered housing portion 502 may depend on the number of struts 300-304, and generally, its cross-sectional shape may be a polygon that may also have rounded corners.

[0060] Similarly, the distal tapered housing portion 506 also has a cross-section that is nearly circular, but its radius decreases in the distal direction. Similar to the intermediate tubular housing portion 504, the exact cross-sectional shape of the distal tapered housing portion 506 may depend on the number of struts 300-304, and generally, its cross-sectional shape may be a polygon that may also have rounded corners.

[0061] The distal tubular housing portion 508 contains the distal bearing 512 and is connected to the proximal section of the flexible atraumatic tip 120.

[0062] Expandable filter Mounted outside the extended housing 122 and thus shown in an extended state is the expandable filter 130. The filter 130 includes a distal tubular filter section 514 having a relatively small diameter and a proximal tubular filter section 516 having a larger diameter. Similar to the intermediate tubular housing portion 504, the exact cross-sectional shape of the filter 130 may depend on the number of struts 300 - 304 and / or the number of struts in the filter 130, including the exact cross-sectional shapes of the distal tubular filter section 514 and the proximal tubular filter section 516. Generally, the cross-sectional shape may be a polygon that may also have rounded corners.

[0063] The tapered filter section 518 connects the two tubular filter sections 516 and 514. The expandable filter 130 covers the entire distal tapered housing portion 506, i.e., the blood flow inlet (input port) 126, with the tapered filter section 518; covers a part of the intermediate tubular housing portion 504 with the proximal tubular filter section 516; and covers a part or all of the distal tubular housing portion 508 with the distal tubular filter section 514.

[0064] A distal tubular filter section 514 is arranged on the distal tubular housing part 508, and a distal outer foil 520 is arranged thereon. The distal outer foil 520 may prevent damage to the expandable filter 130, for example, if the expandable filter 130 is made of a mesh of struts, it can prevent fraying. If the distal tubular filter section 514 defines an aperture, the distal outer foil 520 may be directly attached via the aperture to a structure below the distal tubular filter section 514, such as the flexible atraumatic tip 120. For example, the flexible atraumatic tip 120 and the distal outer foil 520 may be made of the same or similar materials, and the materials may be welded together via the aperture. Since the flexible atraumatic tip 120 is typically made of polyether block amide (PEBA) or polyurethane, the distal outer film 520 may also be made of PEBA or polyurethane, and the materials may be heat-sealed together.

[0065] A proximal outer foil 522 is disposed on the intermediate tubular housing part 504. The proximal tubular section 516 of the expandable filter 130 is sandwiched between the proximal outer foil 522 and the intermediate tubular housing part 504, although only in the distal region of the proximal outer foil 522. The proximal outer foil 522 may prevent damage to the proximal tubular section 516 of the expandable filter 130. In addition, the proximal outer foil 522 is heat-sealed to the inner sleeve or coating 310 of the housing 122 through an aperture in the expandable filter 130. The inner sleeve or coating 310 may be made of polyurethane (PU). When the inner sleeve or coating 310 is made of PU, it is preferable that the proximal outer foil 522 is also made of PU. When the filter 130 is made of a shaped foil tube that defines an aperture, the proximal outer foil 522 may be integrally formed with the filter 130.

[0066] The distal end of the downstream tubing 204 may be attached to the proximal section of the proximal outer foil 522. Alternatively, the downstream tubing 204 may be integrally formed with the proximal outer foil 522. When the filter 130 is made of a shaped foil tube that defines an aperture, the proximal outer foil 522 may be integrally formed with the filter 130 and the downstream tubing 204.

[0067] Filter of helically woven filaments FIG. 6 contains a perspective view of the distal section of the intravascular blood pump 100 with the intermediate tubular housing portion 504, the distal tapered housing portion 506, and the distal tubular housing portion 508. In this embodiment, the expandable filter 130 is a mesh made of filaments that are woven or connected to each other. Weaving is a production method in which two separate sets of filaments (warp and weft) are angled and intertwined to form a fabric. The warp is made of longitudinal filaments, and the weft (filling) is made of transverse filaments. The manner in which the warp filaments and the weft filaments are intertwined with each other is called weaving. The majority of woven products are produced in one of three basic weaves: plain weave, twill weave, or satin weave.

[0068] In plain weave, the warp filaments and the weft filaments are angled and cross each other, aligned to form a simple cross pattern. Each weft filament crosses the warp filaments such that it is above one warp filament and below the next warp filament. The next weft filament passes under the warp that the adjacent weft filament passed over, and vice versa. The filaments of the fabric filter 130 are preferably plain woven, although twill weave, satin weave, or other weaves may be used. Preferably, the mesh does not contain loops and is not knitted.

[0069] Rib weaving is characterized in that four or more weft filaments float on the warp filaments, and four or more warp filaments float on a single weft filament. A float is a place that is not an organizational point, such as when the warp filament is on the weft filament in a warp-faced rib. Twill weaving is characterized by a pattern of diagonal parallel ribs. Twill weaving is created by passing the weft filament over one or more warp filaments and then under two or more warp filaments, and a "step" or offset is provided between the rows to create a characteristic diagonal pattern.

[0070] Referring to FIG. 6, the filter 130 may be made of filaments represented by filaments 600, 602, 604, 608, 610, 612, 614, 616, and 618. Filaments 600-608 are generally helical first struts wound clockwise around the longitudinal axis 620 of the housing 122. The "generally helical" curve used in this specification is a generally smooth space curve. However, the pitch, radius, curvature, and twist used in this specification may vary along the length of the helical curve. The helical curve may be wound more or less than 360° around the axis, or it may not be. Further, the generally helical curve may include small zigzags that are not necessarily all the same, as illustrated by generally helical curves 714 and 716 (FIG. 7).

[0071] Returning to FIG. 6, filaments 610-618 are generally spiral-shaped second struts wound counterclockwise around the vertical axis 620. Filaments 600-618 are shown as thick dashed lines for clarity in the figure. These filaments 600-618 are also reproduced in the inset in FIG. 6 for clarity. The first struts 600-608 and the second struts 610-618 collectively define a plurality of apertures represented by apertures 622, 624, and 626 therebetween. The first struts 600-608 and the second struts 610-618 are woven together such that the plurality of apertures 622-626 are defined between respective adjacent first and second fabric filaments 600-618.

[0072] Each aperture of at least a subset of the plurality of apertures 622-626 may have a generally rhombic or rhomboid, or rectangular shape. As used herein, a rhomboid is a parallelogram in which adjacent sides are not equal in length and the angle between adjacent sides is not a right angle. As used herein, a rhombus is a parallelogram in which adjacent sides are equal in length and the angle between adjacent sides is not a right angle. A rhomboid, rhombus, and rectangle need not necessarily be planar. A rhomboid, rhombus, and rectangle may exist on a curved surface as illustrated by apertures 622-626. The sides of a rhomboid, rhombus, or rectangle need not be perfectly straight and the sides need not necessarily intersect at an angle; i.e., there may be a small radius where two sides intersect, as will be described in more detail later with respect to the corners of the apertures defined by the filter of a formed foil tube.

[0073] In at least the middle portion 628 of the tapered filter section 518, the apertures 622-626 are preferably approximately square. As the diameter of the filter 130 decreases, such as in the distal direction within the tapered filter section 518, the apertures 622-626 may gradually become smaller, and the apertures may become obliquely rhombic with the major axis extending in the longitudinal direction. At the minimum diameter portion of the tapered filter section 518, the smaller interior angle of the rhombic or obliquely rhombic aperture may be less than about 75°.

[0074] As the diameter of the filter 130 increases, such as in the proximal direction within the tapered filter section 518, the apertures 622-626 may gradually become larger. At the maximum diameter portion of the tapered filter section 518, the larger interior angle of the rhombic or obliquely rhombic aperture may be greater than about 110°. The aperture may become obliquely rhombic with the major axis extending in the circumferential direction. These numbers correspond to an embodiment where the larger diameter of the filter 130 is about 2.5 times the smaller diameter of the filter 130. For cases where the large diameter:small diameter of the filter 130 is another ratio, the angles may be adjusted.

[0075] The pump housing 122 may be configured to extend longitudinally by an amount corresponding to the amount of radial compression of the pump housing 122 when radially compressed. The filter 130 may be configured to extend longitudinally by an amount corresponding to the amount of radial compression of the filter 130 when radially compressed. The filter 130 may be configured such that for a given amount of radial compression, the filter 130 and the pump housing 122 extend longitudinally by approximately equal amounts.

[0076] Filaments 600 - 618 may be wires such as nitinol, suitable polymers such as polyethylene terephthalate (PET) or PU, fibers, or another suitable material. The material of filaments 600 - 618 is preferably a shape memory material. Each individual filament 600 - 618 may have a thickness of about 10 μm to about 80 μm, such as about 40 μm, or about 20 μm to about 60 μm. The catheter 106, pump housing 122, impeller 200, and filter 130 may be configured for use within a living patient's body such that each aperture 622 - 626 of the plurality of apertures is sized to prevent suction of the living patient's heart tissue by the input port 126.

[0077] In some embodiments where the filter 130 is formed of a mesh, the mesh may be ironed (pressed under heat) before attaching the filter 130 to the housing 122. Such ironing may fuse the intersecting filaments 600 - 618, particularly if the filaments 600 - 618 are made of a suitable heat - fusible plastic. The filaments 600 - 618 fused in such a manner form a stronger mesh.

[0078] In some embodiments, for the woven fabric, when the filter 130 is in an extended state, the maximum distance between two adjacent filaments 600 - 618 is about 0.3 mm (300 μm) to about 0.4 mm (400 μm). In some embodiments, each aperture 622 - 626 of the plurality of apertures has a maximum dimension equal to or less than about 0.5 mm (500 μm) when the filter 130 is in an extended state. In some embodiments, each aperture 622 - 626 of the plurality of apertures has a maximum dimension equal to or less than about 0.4 mm (400 μm) when the filter 130 is in an extended state. In some embodiments, each aperture 622 - 626 of the plurality of apertures has a maximum dimension equal to or less than about 0.09 mm 2has an area equal to or less than. In some embodiments, each of the plurality of apertures 622-626 has an area of about 0.16 mm when the filter 130 is in the extended state 2 has an area equal to or less than.

[0079] As used herein, "maximum dimension" includes diagonal dimensions such as the dimension between two opposite corners on the diagonal of a quadrilateral. As used herein, the "diameter" of a convex shape means the maximum distance that can be formed between two opposing parallel lines tangent to the boundary of the convex shape. As used herein, "width" means such minimum distance.

[0080] Filter of the formed foil tube FIG. 7 is a side view of an expandable filter 130 formed of a filter tube, and FIG. 8 is an axial (longitudinal) view thereof. FIG. 7 also includes an inset showing an enlarged portion of the expandable filter 130. As noted, in some embodiments, the filter 130 includes a formed foil tube 700 with apertures. Examples of apertures are shown at 702, 704, and 706. The expandable filter 130 made from the formed foil tube 700 is compressed by folding some or all of the parts of the filter 130, i.e., becoming smaller in the radial direction. The filter 130 is expanded from the compressed state by opening the previously folded parts. The compression and expansion rely mainly on this folding and opening stage rather than elastic compression and elongation.

[0081] Apertures 702 - 706 are positioned on the tube such that the material between apertures 702 - 706, exemplified by materials 708, 710, and 712, forms first and second struts. Two exemplary struts 714 and 716 are shown by thick dashed lines in FIG. 7. As noted, the generally helical curves may include small zigzags that are not necessarily all the same, as exemplified by generally helical curves 714 and 716. These zigzags are more clearly seen in struts 718 and 720, shown, for example, by thick solid and dashed lines in the inset of FIG. 7.

[0082] Although housing 122 is not shown in FIGS. 7 and 8, FIGS. 7 and 8 show an extended filter 130 as it would appear when mounted on an extended housing 122 (e.g., FIG. 6). Filter 130 made from formed foil tube 700 may be made of a polymer such as PET or PU. The wall of foil tube 700 may be about 10 μm to about 100 μm thick, preferably about 15 μm to about 75 μm thick, and more preferably about 20 μm to about 50 μm thick. The wall thickness of foil tube 700 may continuously decrease distally in tapered filter section 518 as a result of, for example, blow molding manufacture.

[0083] As shown in FIG. 9, foil tube 700 may be shaped on mandrel 900. Mandrel 900 should have the desired shape of the completed filter 130 in the extended state. Next, apertures 702 - 706 may be defined in the formed tube, such as by cutting or punching. Apertures 702 - 706 may have a generally diamond or off - diamond, or rectangular shape. The interior angles of apertures 702 - 706 in filter 130 based on foil tube 700 should have a radius of at least about 5 μm, preferably at least about 20 μm.

[0084] As discussed herein, additional holes may be defined in the shaped tube, such as to facilitate attachment of the shaped tube to other components of the intravascular blood pump 100. Next, as shown in FIGS. 10, 11, and 12, a shaped apertured tube may be mounted on the housing 122 (the housing 122 is not visible in FIG. 12). FIG. 10 is a cross-sectional view of the distal end region of the expandable housing 122 with the expandable filter 130 mounted thereon. FIG. 11 is a cross-sectional view similar to FIG. 10, but includes the internal coating 310 of the expandable housing not shown in FIG. 10 for clarity. FIG. 12 is a perspective view of the distal end region of the expandable housing 122 with the expandable filters of FIGS. 7-8 mounted thereon.

[0085] Returning to FIGS. 7 and 8, the shape and size of the holes may vary in different parts of the expandable filter 130. In the distal tubular filter section 514, the holes exemplified by the holes 722 may be longer (in the longitudinal direction) than wide (in the circumferential direction). The holes 722 may be defined as a circumferential row. As shown in FIG. 7, the holes 722 in adjacent rows may be staggered in the circumferential direction and may overlap in the longitudinal and circumferential directions. Such staggering and overlapping allows the distal tubular section 514 to be easily expanded during assembly without the need for elastic stretching of the material. This expansion may facilitate insertion of the impeller 200 into the housing 122 through the distal end of the housing 122. Further, such staggering generally allows the holes 722 to be placed closer together, thus increasing the permeability of the filter 130 to blood flow.

[0086] The distal outer foil 520 (FIG. 10) may be heat sealed, such as by welding, through the holes 722 of the distal tubular filter section 514 that extends to the proximal section of the flexible atraumatic tip 120. Each hole 722 in the distal tubular filter section 514 has an enlarged portion positioned centrally within a longitudinal slot. The enlarged portion has the advantage of having a relatively large open contact area for attaching the distal outer foil 520 to the flexible atraumatic tip 120 after the impeller 200 is inserted and the distal tubular section 514 returns to its normal diameter.

[0087] The expandable filter 130 further includes a transition zone 724 (FIG. 7) where the distal tubular filter section 514 and the tapered filter section 518 meet. The holes in the transition zone 724, exemplified by the holes 726, are longer and wider than the adjacent holes in the tapered filter section 518. Preferably, the holes 726 in the transition zone 724 are at least twice as large as the adjacent holes in the tapered filter section 518, exemplified by the holes 728. In one embodiment, for each pair of circumferentially adjacent holes 728 within one row of the tapered filter section 518, the transition zone 724 has one hole 726 that spans the two holes 728 in the circumferential direction. Thus, the number of holes in the circumferential row within the transition zone 724 is half the number of holes in the circumferential row within the tapered filter section 518. In some other embodiments, other ratios such as 3:1, 4:1, or 3:2 may be used. Each hole 726 in the transition zone 724 may be approximately 2 times, 3 times, or another multiple in length (in the longitudinal direction) and approximately 2 times, 3 times, or another multiple in width (in the circumferential direction) of the holes 728 in the tapered filter section 518, depending on the ratio of the number of holes 728 within one row of the tapered filter section 518 to the number of holes 726 within one row of the transition zone 724.

[0088] The dimensions and shapes of the holes 702 - 706 and 728, and the dimensions of the struts 714 - 716 should be selected such that the housing 122 can be inserted into the tapered filter section 518 without exceeding the elastic deformation limit of the material when the tapered filter section 518 is fully open. For example, taking into account the local elastic deformation of the filter material, the length of two adjacent struts 714 - 716 (on the zigzags of the zigzag circumferential ring) in the circumferential direction, multiplied by the number of apertures 702 - 706 in the circumferential row, should be approximately equal to the circumference of the fully extended housing 122.

[0089] Adjacent holes 726 within the transition zone 724 are separated from each other by struts that are wider than the adjacent struts 714 - 716 of the tapered filter section 518. These wider struts stabilize the larger holes 726. When the distal outer foil 520 is placed longitudinally and proximally onto the distal tubular filter section 514 up to the transition zone 724, the distal outer foil 520 at least partially covers the first one or more rows of holes 726 in the transition zone 724, thus reducing their effective size. In some cases, these reduced hole sizes can lead to blood damage or an increased risk of blood clotting. Therefore, the holes 726 in the transition zone 724 should be selected to be larger than the holes in the tapered filter section 518.

[0090] As can be seen in FIG. 7, the holes 728 in the distal region of the tapered filter section 518 are circumferentially narrower than the holes 702-706 in the proximal region of the tapered filter section 518. In other words, the sizes of the apertures 702-706 increase monotonically in the proximal direction along the longitudinal axis. Additionally, in the distal tubular filter section 514, the holes 722 take the form of narrow axial slits that are offset from each other circumferentially. This is advantageous because when the impeller 200 is inserted into the housing 122 or when the expandable filter 130 is expanded at the distal regions of the distal tubular filter section 514 and the tapered filter section 518, the narrow holes can expand. The wider holes border the thicker struts, especially in the tapered filter section 518. The struts have a width ranging from approximately 30 μm in the distal region of the tapered filter section 518 to approximately 60 μm in the proximal region. Preferably, the maximum diameter of the holes in the tapered filter section 518 is from about 300 μm to about 500 μm.

[0091] In the embodiment shown in FIG. 7, the proximal tubular filter section 516 does not have holes. However, holes in the proximal tubular filter section 516 may be desirable, such as when the proximal outer foil 522 is placed on the proximal tubular filter section 516 located on the intermediate tubular housing portion 504 (FIG. 5). The proximal outer foil 522 secures the expandable filter 130 to the housing 122, and since the tubular housing portion 504 is coated with PU and the proximal outer foil 522 is also made of PU, they can be easily heat-sealed or welded through such holes. However, if both the filter 130 and the proximal outer foil 522 are made of a suitable material such as PU, the filter 130 and the proximal outer foil 522 may be directly joined together by the application of heat or the like.

[0092] When the expandable filter 122 in FIGS. 7 and 8 is disposed on the expanded housing 122 as shown, for example, in FIG. 10, the distal tubular filter section 514 is preferably disposed over the distal bearing 512 and the flexible atraumatic tip 120. The distal tubular filter section 514 is covered by a distal outer foil 520 to secure the expandable filter 130 to the intravascular blood pump 100.

[0093] The proximal tubular filter section 516 has a relatively large diameter. If this diameter is not likely to change significantly during the assembly of the intravascular blood pump 100, i.e., if the proximal opening of the filter 130 is not likely to be significantly stretched, the holes defined in this section will not undergo significant deformation during assembly. Thus, these holes may be square or of another shape, and the holes may be at least partially defined by a circumferential ring of struts. One such embodiment is shown in FIG. 13. FIG. 13 is a side view of the expandable filter 130 of FIGS. 7 and 8, based on an alternative embodiment of the present invention.

[0094] The expandable filter 130 of FIG. 13 includes a band 1300 of several parallel rings of holes, exemplified by holes 1302, 1304, and 1306, and rings 1308 and 1310. All of the rings 1308 - 1310 have the same number of holes 1302 - 1306, and the holes 1302 - 1306 are approximately the same size. As a result, the ratio of the total area of the holes to the total area of the struts within the band 1300 is relatively high compared to other portions of the filter 130. A high ratio of holes to struts is advantageous as it increases the permeability of the filter 130 to blood flow, which reduces the risk of hemolysis and clotting. The ratio of the total area of the holes to the total area of the filter 130 exposed to blood should be at least about 60%, preferably at least about 70%, and more preferably at least about 80%. This band 1300 may be combined with the large holes 726 in the transition zone 724 discussed herein with respect to FIG. 7.

[0095] The description of the shape of the holes and the apertures pertains to the extended filter 130. When the filter 130 is compressed, such as by being folded, the shape of the holes may change drastically. In fact, being bendable is the ability of the struts to facilitate compression of the filter 130.

[0096] FIG. 14 is a perspective view of the distal end region of the extensible housing of FIGS. 10 - 11 with an extensible filter mounted thereon that is similar to FIGS. 7 - 8 and / or 13 but has a different aperture pattern. For example, as illustrated by strut 1400, some of the struts are fork-shaped. Some of the struts, such as fork-shaped strut 1400, may be wider than other struts. Some of the struts, illustrated by struts 1402 and 1404, extend between respective pairs of the teeth of the fork. Thus, a plurality of first struts and a plurality of second struts extend between the pairs of teeth and collectively define a plurality of apertures therebetween. Each first strut that includes a fork may be wider than each first strut that does not include a fork.

[0097] One or more of the struts may be aligned on respective struts of the housing 122. As shown in FIG. 10, the housing 122 includes struts represented by struts 300 as discussed with respect to FIGS. 3 and 4. The struts 300 of the housing are referred to herein as third struts. A group of these third struts, represented by strut 1000 (FIG. 10), collectively define an aperture therethrough, represented by aperture 1002 (FIG. 10). At least some of the first and second struts, i.e., the struts in the filter such as fork-shaped strut 1400 (FIG. 14) (see FIG. 7), may be radially aligned on respective struts of the third struts for support.

[0098] FIG. 15 is a perspective view of the distal end region of the expandable housing of FIGS. 10-11 with an expandable filter similar to FIG. 14 mounted thereon but with a different aperture pattern.

[0099] FIG. 16 is a side view of the distal end region of the expandable housing of FIGS. 10-11 with an expandable filter similar to FIG. 14 mounted thereon, according to another alternative embodiment of the present invention.

[0100] FIG. 17 is a side view of the distal end region of the expandable housing of FIGS. 10-11 with a long inflow cannula 1701 and a bulbous expandable filter 1700 having an enlarged inflow area 1702 mounted thereon. FIG. 18 is a side view of the distal end region of the expandable housing of FIGS. 10-11 with downstream tubing instead of a long inflow cannula and a bulbous expandable filter 1802 having an enlarged inflow area 1800 mounted thereon, which is similar to FIG. 17 in other respects.

[0101] The bulbous expandable filters 1700 and 1800 provide enlarged inflow areas 1702 and 1802 to the intravascular blood pump 100, which improves the flow characteristics of the pump. The enlarged inflow areas 1702 and 1802 are covered by a filter 1704, which is similar to the filters of FIGS. 10, 11, and 12 but with even larger apertures.

[0102] Filter 130 includes a distal portion 1706 and a proximal portion 1708. The distal portion 1706 monotonically increases in diameter in the proximal direction along the longitudinal axis. The proximal portion 1708 monotonically decreases in diameter in the proximal direction along the longitudinal axis.

[0103] At least a portion of the plurality of apertures 702-706 is disposed on the distal portion 1706. In some embodiments, the proximal portion 1708 is without apertures.

[0104] Generally, the sizes of the apertures 702 - 706 of the plurality of apertures increase in the distal direction along the vertical axis, but the increase does not necessarily have to be monotonic. The apertures 702 - 706 are arranged in a plurality of columns of apertures of equal size, exemplified by columns 1710, 1712, and 1714, which are generally circumferential with respect to the vertical axis. Some of the columns 1710 - 1714 have a different number of apertures 702 - 706 than other columns of 1710 - 1714. For example, the first column 1710 (shown in dashed lines) of the plurality of generally circumferential columns includes more apertures 702 than the second column 1712 of the plurality of generally circumferential columns. Each aperture 702 of the first column 1710 has a smaller area than each aperture 704 of the second column 1712.

[0105] The apertures 702 - 706 may be arranged in a plurality of bands of apertures of approximately equal size, exemplified by bands 1716, 1718, and 1720, which are generally circumferential with respect to the vertical axis. The size of the apertures 702 - 706 in each of the plurality of bands 1718 - 1722 increases monotonically along the vertical axis. That is, generally, the apertures in band 1720 are larger than the apertures in band 1718. However, an aperture in a given column may be larger or smaller than an aperture in another column of the same band; because the two columns may have the same number of apertures but may have different circumferences. In the embodiment shown in FIG. 17, the size of the apertures 702 - 706 in each of the plurality of bands 1718 - 1722 increases monotonically in the distal direction along the vertical axis. Other aspects of the size and arrangement of the apertures are similar to those discussed with respect to FIG. 7.

[0106] As noted, the distal end region of the expandable housing shown in FIG. 18 is similar to that shown in FIG. 17, except that the expandable housing in FIG. 18 includes downstream tubing rather than a long inflow cannula.

[0107] FIG. 19 is a perspective view of the distal end region of the expandable housing of FIGS. 10-11, with an expandable filter similar to FIG. 14 but with several vertical struts exemplified by vertical strut 1900. Each vertical strut 1900 lies in a respective plane containing the longitudinal axis 620, as exemplified by plane 1902. As used herein, the phrase "plane containing a line" means that the line lies entirely within that plane. Although FIG. 19 shows only one vertical strut 1900, filter 130 may include additional vertical struts (not shown).

[0108] Although the invention has been described through the above exemplary embodiments, modifications and variations to the illustrated embodiments are possible without departing from the concepts of the invention disclosed herein. For example, although specific parameter values such as dimensions and materials may be recited in connection with the disclosed embodiments, within the scope of the invention, the values of all parameters can vary widely to suit different applications. Unless otherwise indicated in the context or otherwise understood by one of ordinary skill in the art, terms such as "about" mean within ±20%.

[0109] In this specification and the claims, the terms "and / or" used in connection with a list of items means one or more of the items in the list, i.e., at least one of the items in the list, but not necessarily all of the items in the list. In this specification and the claims, the term "or" used in connection with a list of items means one or more of the items in the list, i.e., at least one of the items in the list, but not necessarily all of the items in the list. "Or" does not mean "exclusive or".

[0110] Aspects of the present disclosure, or portions thereof, may be combined in ways not enumerated above and / or not explicitly claimed. Additionally, the aspects disclosed herein may be suitably implemented in the absence of any element not specifically disclosed herein. Accordingly, the invention should not be seen as limited to the disclosed aspects.

[0111] As used herein, terms such as "first," "second," and "third" with respect to numbers are used to distinguish respective struts, aperture rings, and / or aperture bands from one another and are not intended to indicate any particular order or total number of struts, aperture rings, and / or aperture bands in any particular aspect. Thus, for example, a given aspect may include only a second strut, aperture ring, and / or aperture band, as well as a third strut, aperture ring, and / or aperture band.

Claims

1. A catheter configured for insertion into a blood vessel, the catheter defining an internal volume through which blood flows and being defined by the blood vessel; A pump housing attached to the catheter and defining an input port and an output port, the pump housing having a longitudinal axis; An impeller disposed within the pump housing and configured to pump blood from the input port to the output port when rotating; A filter attached outside the pump housing and in fluid communication between (a) the internal volume of the blood vessel outside the pump housing and (b) the input port, the filter including a plurality of generally helical first struts wound around the longitudinal axis and a plurality of second struts, the plurality of generally helical first and plurality of second struts collectively defining a plurality of apertures therebetween; An intravascular blood pump including the above.

2. The intravascular blood pump according to claim 1, wherein the pump housing, the impeller, and the filter are each alternately compressible and expandable in the radial direction.

3. Such that for a given amount of radial compression, the filter and the pump housing extend longitudinally by approximately equal amounts, The pump housing is configured to extend longitudinally by an amount corresponding to the amount of radial compression of the pump housing when radially compressed, and The filter is configured to extend longitudinally by an amount corresponding to the amount of radial compression of the filter when radially compressed. The intravascular blood pump according to claim 2.

4. The catheter, the pump housing, the impeller, and the filter are configured to be used within the living patient's body such that each of the plurality of apertures is sized to prevent suction of the living patient's heart tissue by the input port. The intravascular blood pump according to any one of claims 1 to 3.

5. The intravascular blood pump according to any one of claims 1 to 4, wherein each of the plurality of apertures has a maximum dimension equal to or less than about 0.5 mm in the extended state.

6. The intravascular blood pump according to any one of claims 1 to 5, wherein each of the plurality of apertures has a maximum dimension equal to or less than about 0.4 mm in the extended state.

7. The intravascular blood pump according to any one of claims 1 to 6, wherein each of the plurality of apertures has an area equal to or less than about 0.09 mm ２ in the extended state.

8. The intravascular blood pump according to any one of claims 1 to 7, wherein each of the plurality of apertures has an area equal to or less than about 0.16 mm ２ in the extended state.

9. The intravascular blood pump according to any one of claims 1 to 8, wherein the plurality of apertures have a size that monotonically increases in the proximal or distal direction along the longitudinal axis.

10. The intravascular blood pump according to any one of claims 1 to 9, wherein the generally helical first strut is wound clockwise around the longitudinal axis and the second strut is wound generally helically counterclockwise around the longitudinal axis.

11. The intravascular blood pump according to any one of claims 1 to 9, wherein the generally helical first strut is wound in a first direction around the longitudinal axis and the second strut is wound generally helically in the first direction around the longitudinal axis.

12. The intravascular blood pump according to any one of claims 1 to 9, wherein each strut of at least a subset of the second struts is arranged in a plane including the vertical axis.

13. The intravascular blood pump according to any one of claims 1 to 12, wherein each aperture of at least a subset of the plurality of apertures has a generally rhombic or rhomboid shape.

14. The plurality of generally helical first struts include a plurality of first filaments; the plurality of second struts include a plurality of second filaments; and the plurality of first filaments and the plurality of second filaments are woven together such that the plurality of apertures are defined between the respective adjacent plurality of first filaments and plurality of second filaments. The intravascular blood pump according to any one of claims 1 to 13.

15. The intravascular blood pump according to any one of claims 1 to 13, wherein the filter includes a tube having a wall; and the plurality of apertures include a plurality of openings defined through the wall.

16. The intravascular blood pump according to claim 15, wherein the tube includes a generally funnel-shaped tube.

17. The intravascular blood pump according to any one of claims 15 to 16, wherein the wall has a thickness of about 10 to 100 μm.

18. The pump housing includes a plurality of third struts that collectively define a plurality of third apertures therebetween; and at least some of the plurality of generally helical first struts and the plurality of second struts are radially aligned on each of the plurality of third struts. The intravascular blood pump according to any one of claims 15 to 17.

19. Each strut of at least a subset of the first struts includes a fork that includes a plurality of teeth; at least a portion of the plurality of generally helical first struts and at least a portion of the plurality of second struts extend between pairs of the teeth and collectively define a plurality of apertures therebetween, the intravascular blood pump according to any one of claims 15 to 18.

20. At least a portion of each of the plurality of generally helical first struts that includes a fork is wider than each of the plurality of generally helical first struts that do not include a fork, the intravascular blood pump according to claim 19.

21. The plurality of apertures are arranged in a plurality of rows of apertures of equal size that are generally circumferential with respect to the longitudinal axis; some of the plurality of generally circumferential rows have a different number of apertures than the other plurality of generally circumferential rows, the intravascular blood pump according to any one of claims 15 to 20.

22. The first row of the plurality of generally circumferential rows includes more apertures than the second row of the plurality of generally circumferential rows; and each aperture of the plurality of first rows that are generally circumferential has a smaller area than each aperture of the plurality of second rows that are generally circumferential, the intravascular blood pump according to any one of claims 21.

23. The apertures are arranged in a plurality of bands of apertures of approximately equal size that are generally circumferential with respect to the longitudinal axis; the size of the apertures in each of the plurality of generally circumferential bands increases monotonically along the longitudinal axis, the intravascular blood pump according to any one of claims 15 to 20.

24. The filter includes a distal portion and a proximal portion; the distal portion has a diameter that increases monotonically in the proximal direction along the longitudinal axis; the proximal portion has a diameter that decreases monotonically in the proximal direction along the longitudinal axis; and at least a portion of the plurality of apertures is disposed on the distal portion, the intravascular blood pump according to claim 23.

25. The intravascular blood pump according to any one of claims 1 to 24, wherein any struts that are substantially helical and a plurality of second struts are absent and are circumferential with respect to the longitudinal axis.

26. A method for making a filter for an intravascular blood pump, the method comprising the following steps: Providing a catheter configured for insertion into a blood vessel, the blood vessel defining an internal volume through which blood flows; Attaching a pump housing defining an input port and an output port and having a longitudinal axis to the catheter; Placing an impeller configured to pump blood from the input port to the output port when rotating within the pump housing; and Providing a filter in fluid communication between (a) the internal volume of the blood vessel outside the pump housing and (b) the input port, the filter including a plurality of substantially helical first struts wound around the longitudinal axis and a plurality of second struts, the first and second struts collectively defining a plurality of apertures therebetween.

27. The method according to claim 26, wherein the filter includes a woven filter.

28. The method according to claim 26, wherein the filter includes a filter of a molded tube.

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