Reinforced catheter-based blood pump

Abstract

SUMMARY OF THE INVENTION It is an object of the present invention to provide an intravascular blood pump for percutaneous insertion having a catheter that is resistant to kinking. An intravascular blood pump for percutaneous insertion includes a catheter (10) and a pumping device (1) attached to the catheter (10). The catheter (10) extends along a longitudinal axis and has a distal end (11) and a proximal end (12) opposite the distal end (11). The catheter (10) includes an elongated stiffening structure (15) extending continuously longitudinally along the length of the catheter (10) between the proximal and distal ends (12 and 11). The stiffening structure (15) may include a shape-memory material such as nitinol. The stiffening structure (15) may take the form of a wire that extends in a relaxed state through the lumen of the catheter, avoiding or significantly reducing kinking in the catheter.

Description

[Technical field]

[0001] The present invention relates to an intravascular blood pump for percutaneous insertion into a patient's blood vessel, comprising a catheter and a pumping device attached to the distal end of the catheter. [Background technology]

[0002] A blood pump for percutaneous insertion is designed to support a patient's heart and is inserted into the patient's heart through a blood vessel, such as the aorta or femoral artery, by a catheter through a vascular access in the patient's skin, i.e. percutaneously. An intravascular blood pump for percutaneous insertion typically comprises a catheter and a pumping device attached to the catheter. The catheter may extend from a distal end to a proximal end along a longitudinal axis, and the pumping device is attached to the catheter at the end remote from an operator, such as a surgeon. The pumping device may be inserted into the left ventricle of the patient's heart by the catheter, for example, through the femoral artery and the aorta. A blood pump placed inside the patient's heart may also be called an intracardiac blood pump.

[0003] While relatively stiff catheters have less risk of kinking, soft catheters better conform to the shape of blood vessels such as the aorta, especially the aortic arch. However, soft catheters are prone to kinking, especially during catheter insertion, due to their low stiffness. If the catheter kinks, this creates a weakened spot on the catheter, making it more likely to kink again at the same spot. This can be particularly problematic during the operation of a blood pump. For example, the blood pump may be pushed out of the heart and back into the aorta, which can cause kinking of the catheter, especially if the catheter was already kinked during insertion. This can result in severe kinking at the weakened spot, which in turn causes kinking of structures inside the catheter, such as the purge line that supplies the purge fluid to the pumping device. The purge line can block and the blood pump can fail due to increased purge pressure or even complete blockage of the purge line. Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE PRESENT EMBODIMENT It is therefore an object of the present invention to provide an intravascular blood pump for percutaneous insertion having a catheter that is resistant to kinking. [Means for solving the problem]

[0005] This object is achieved according to the invention by a blood pump for percutaneous insertion having the features of independent claim 1. Preferred embodiments and further developments of the invention are specified in the dependent claims. Throughout this disclosure, the term "distal" refers to a direction away from the user towards the heart and the term "proximal" refers to a direction towards the user.

[0006] In accordance with the present invention, an intravascular blood pump catheter for percutaneous insertion includes an elongated stiffening structure extending continuously longitudinally along the length of the catheter between a proximal end and a distal end of the catheter. The stiffening structure has a stiffening force of about 0.00005 Nm. 2~about 0.01Nm 2 , preferably about 0.0001 Nm 2 ~about 0.001Nm 2 , more preferably about 0.0001 Nm 2 ~about 0.0005Nm 2 , more preferably about 0.0001 Nm 2 ~about 0.0007Nm 2 , or approximately 0.00005 Nm 2 ~about 0.0004Nm 2 Song The catheter has a bending stiffness of 10 mm and does not undergo plastic deformation when bent with a minimum bending radius of 10 mm. Therefore, the catheter is reinforced by the elongated stiffening structure and is prevented from kinking.

[0007] In one embodiment, the stiffening structure comprises a shape memory material. The continuous stiffening structure of the shape memory material prevents the catheter from kinking while at the same time providing sufficient flexibility to allow bending so that the catheter can be directed through a blood vessel such as the aorta. This occurs due to the so-called superelastic property of the material. Shape memory materials have temperature-dependent and temperature-independent properties. Shape memory is a temperature-dependent property that allows a shape memory material to undergo deformation at a certain temperature and then recover to its original undeformed shape when heated above the "deformation temperature". The temperature change causes a transformation between the martensite and austenite phases of the material. Superelasticity is a temperature-independent property that allows a shape memory material to undergo a mechanical deformation due to an external force applied to the shape memory material and then recover to its original undeformed shape when the external force is released. Superelasticity, also referred to as pseudoelasticity, is caused by a transformation between the martensite and austenite phases that occurs due to an external load. As a result, these materials can reversibly deform to very high strains. A preferred shape memory material is Nitinol.

[0008] In particular, during percutaneous insertion of the blood pump, where the surgeon / cardiologist pushes the catheter through the blood vessel, kinking is prevented. Weakened places on the catheter are avoided so that there is less risk of kinking of the catheter during the operation of the blood pump. If the catheter nevertheless kinks during the procedure, it can flex back and recover its shape over time. In particular, since kinking is a plastic deformation of the catheter, i.e. an irreversible deformation, whereas bending is an elastic deformation that allows the catheter to return to its initial shape, the stiffening structure allows the catheter to deform elastically with a minimum bending radius of 10 mm without plastic deformation. The bending radius is measured relative to the central axis of the catheter. Approximately 0.00005 Nm 2 ~about 0.01Nm 2 In combination with the bending stiffness of the stiffening structure, this results in an effective avoidance of twisting, or at least a significant reduction of twisting.

[0009] Bending stiffness (or flexural stiffness) is a mechanical value of a stiffening structure that depends on the material and dimensions, more specifically the product of the modulus of elasticity ("Young's modulus") and the moment of inertia, which in turn depends on the cross-sectional area (size and shape). Typical diameters of stiffening wires are, for example, 0.5 mm to 0.6 mm. Assuming a wire with a circular cross-sectional shape, this results in a stiffening diameter of about 0.0031 mm. 4 ~ approx. 0.0064mm 4 Exemplary values ​​of the elastic modulus can be about 70 GPa to 90 GPa for austenitic nitinol and about 20 GPa to 45 GPa for martensitic nitinol. This results in a moment of inertia of about 0.0002 Nm for austenitic nitinol. 2 ~about 0.0006Nm 2 For martensitic nitinol, the bending stiffness is approximately 0.00006 Nm 2 ~about 0.0003Nm 2 A bending stiffness of 100 mm can be obtained.

[0010] In a preferred embodiment, the stiffening structure is a wire having a cross-sectional shape with a diameter of 0.54 mm to 0.56 mm, the material having an elastic modulus of 73 GPa to 85 GPa for austenitic nitinol and 23 GPa to 42 GPa for martensitic nitinol.

[0011] The stiffening structure may extend along the length of the catheter, at least in the area where high bending forces may occur, such as at least 20 cm, preferably at least 30 cm from the distal end of the catheter. Preferably, the stiffening structure extends along the area of ​​the catheter that is placed in the patient's body, such as at least 40 cm from the distal end of the catheter. More preferably, the stiffening structure extends further into the area of ​​the catheter that will be handled by the surgeon, i.e. at least 50 cm from the distal end of the catheter. Most preferably, the stiffening structure extends along the entire length of the catheter. A typical length of a catheter for percutaneous insertion via femoral access (artery or vein) to the patient's heart may be 100 cm to 150 cm. The stiffening structure may also have a length of 100 cm to 150 cm. The catheter and stiffening structure may have a length of 25 cm to 50 cm when the catheter is designed to be inserted into the left ventricle through the subclavian or axillary artery, or into the right ventricle through the jugular vein.

[0012] The stiffening structure can be configured to remain in the catheter during operation of the blood pump to support the catheter and prevent kinking during the entire procedure and during operation of the blood pump. This can be advantageous in applications where the movement of the heart or the pumping action of the blood pump tend to push the blood pump out of the heart during operation of the blood pump. In applications where there is no or less tendency to push the blood pump out of the heart, the stiffening structure can be configured to be removed from the catheter after placement of the blood pump in the patient's body. This allows the catheter to be more flexible during operation of the blood pump and allows the catheter to better conform to the shape of the respective blood vessel, such as the aorta. This reduces contact between the inner wall of the vessel and the catheter and can also reduce the force with which the pump may push against the valve structure.

[0013] As mentioned above, the stiffening structure preferably comprises or is made of a material with superelastic properties, in particular a shape memory material, i.e. a material that has the ability to return to its original shape after being deformed and is resistant to permanent twisting. The shape memory material can be a shape memory alloy, preferably Nitinol. In particular, Nitinol exhibits superelastic properties that help to prevent twisting. However, other shape memory materials may be used for the stiffening structure, such as polymeric materials with shape memory properties. Carbon fiber reinforced materials may also be used.

[0014] The use of Nitinol structures on the outside of the catheter is described in International Patent Application No. WO 2013 / 160443 A1. The optical fiber extends through the catheter, exits the catheter and further extends along the outside of the cannula in a Nitinol tube. The optical fiber is located inside the catheter without a Nitinol tube. In contrast, the present invention provides a stiffening structure made of a shape memory material, such as a Nitinol rod or wire or tube, which extends continuously along the length of the catheter to avoid kinking of the catheter. The stiffening structure may be provided solely for stiffening purposes. In particular, the stiffening structure is preferably separate from the pumping device, i.e. not connected to the pumping device. However, in some embodiments, the stiffening structure may have additional functions, such as a guiding or protective function.

[0015] The catheter may have a lumen, such as at least one lumen, extending through the catheter from the proximal end to the distal end. The stiffening structure is preferably disposed within the lumen of the catheter. If the catheter has more than one lumen, the stiffening structure may be disposed within a lumen separate from the lumen containing other lines, e.g., electrical wires, purge lines, etc. Thus, a common catheter may be used and the stiffening structure may be provided thereon by inserting the stiffening structure through the catheter lumen. Preferably, the stiffening structure is substantially free-floating or loose, i.e., not fixed within the lumen of the catheter. In particular, the distal end of the stiffening structure may be free, i.e., not attached to or interlocked with other parts of the blood pump, e.g., the pumping device. This increases the flexibility of the catheter while at the same time effectively preventing the catheter from kinking, since the stiffening structure may move and slide within the catheter lumen as the catheter bends to follow the shape of the blood vessel. This has the further advantage that due to the stiffening structure not being fixedly attached to one side of the catheter, the flexibility of the catheter can have isotropic behavior, i.e. the flexibility can be the same in any bending direction.

[0016] Alternatively, the stiffening structure may be housed or embedded in the wall of the catheter, or may be disposed on the exterior surface of the catheter without insertion into the lumen of the catheter. The stiffening structure may be fixed at least in the radial direction. The stiffening structure may be axially movable, such as axially slidable along the length of the catheter, for example, as the catheter bends. For example, the stiffening structure may be fixed to the exterior surface of the catheter by any suitable attachment, such as rings, loops, eyelets, etc. Alternatively, the stiffening structure may be fixed to the exterior surface of the catheter along its entire length.

[0017] In one embodiment, the stiffening structure includes at least one rod or wire. In another embodiment, the stiffening structure includes multiple rods or wires, such as two, three, four or more rods or wires. It will be understood that the bending stiffness properties of one or more rods or wires add up to provide a desired overall bending stiffness.

[0018] Preferably, at least one rod or wire is solid, preferably each of the rods or wires is solid. A solid rod is an easy to manufacture and inexpensive structure to provide a stiffening structure. In another embodiment, the rod may have a hollow cross section, i.e., tubular. In the case of a tubular rod or wire, the tube may be used to supply, for example, a purge fluid to a blood pump. At least one rod, preferably each of the rods, may have a diameter of about 0.3 mm to 0.6 mm, preferably about 0.54 mm to 0.56 mm. The diameter of the rod or rods need not be constant along the length, but may be variable to achieve variable flexibility along the length. For example, in areas where the catheter should be stiffer, the rod or rods may have a larger diameter than areas where the catheter should be softer, or there may be multiple rods acting simultaneously in said areas. Variable flexibility may also be created by providing different materials along the length of the rod, or by providing a jacket that provides increased bending stiffness in desired areas. Preferably, the stiffening structure provides greater stiffness at its proximal end, i.e., the end that is manipulated by the user, which may require a higher bending stiffness. The distal end may have a lower bending stiffness than the proximal end to allow the catheter to be advanced into the blood vessel. To this end, the stiffening structure may be tapered towards the distal end.

[0019] The rod or rods may have any suitable cross-sectional shape, in particular circular, or other shapes such as oval or polygonal, in particular triangular, rectangular, pentagonal, hexagonal or octagonal. It will be understood that one relatively thick rod can achieve the same or approximately the same effect as multiple thinner rods, such as two, three, four or more. When the stiffening structure includes two or more rods, the rods can be braided to form a substantially solid braid, or a braided tube, i.e. a hollow tubular body. Depending on the number of rods, for example when three rods are braided, the braided tube can provide the same bending stiffness in all directions and provide high torsional stiffness, whereas a solid braid can have different bending stiffness in different directions.

[0020] The cross section of the stiffening structure may have at least two, in particular two, intersecting, preferably orthogonal, axes of symmetry. Such a cross section may be, for example, oval or rectangular. In one embodiment, the stiffening structure may have a cross-section that is not rotationally symmetric. .child A kind of symmetry can also be achieved by placing two or more rods, for example two rods with circular cross-sections, adjacent to each other. More generally, the bending stiffness of the stiffening structure can be made different for bending of the stiffening structure in different planes. This can be useful in catheter navigation. In particular, the catheter may be curved in a plane, and the stiffening structure may have a minimum bending stiffness for bending in the plane in which the catheter is curved. This means that in the plane in which the catheter is curved, the catheter can bend more easily, whereas bending in other planes is more difficult.

[0021] Preferably, at least one rod or wire is straight or linear, meaning that it does not have any undulations or the like, except for any curvature resulting from the curvature of the catheter.

[0022] The foregoing summary, as well as the following detailed description of the preferred embodiments, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the disclosure, reference is made to the drawings. However, the scope of the disclosure is not limited to the specific embodiments disclosed in the drawings. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 illustrates a patient's heart with a blood pump inserted into the left ventricle through the aorta. [Diagram 2] FIG. 2 is a schematic diagram of a catheter of the blood pump of FIG. 1 having a stiffening structure. [Diagram 3] 1A-1D are schematic diagrams illustrating catheters having stiffening structures according to different embodiments. [Figure 4] 1A-1D are schematic diagrams illustrating catheters having stiffening structures according to different embodiments. [Diagram 5] 1A-1D are schematic diagrams illustrating catheters having stiffening structures according to different embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] In FIG. 1, a blood pump is shown to be inserted into a patient's heart H. More specifically, the blood pump comprises a pumping device 1 attached to a catheter 10 by which the pumping device 1 is inserted into the left ventricle LV of the patient's heart H via the aorta AO, including the descending aorta DA and the aortic arch AA. The catheter 10 has a distal end 11 and a proximal end 12. The blood pump has a blood flow outlet 3 disposed outside the patient's heart H in the aorta AO, while the blood flow inlet 2 is in fluid communication with a flow cannula 4 located inside the left ventricle LV. An impeller (not shown) is provided in the pumping device 1 to generate blood flow from the blood flow inlet 2 to the blood flow outlet 3. At the distal end of the blood pump, a soft tip 5, such as a pigtail or J-tip, is disposed to facilitate the insertion of the blood pump into the patient's heart H without causing damage to the surrounding tissue. The soft tip 5 also helps to keep soft tissue away from the blood inlet 2 and support the pumping device 1 against the inner wall of the left ventricle LV.

[0025] Referring now to FIG. 2, there is shown a catheter 10 of the blood pump of FIG. 1. The catheter 10 extends from a distal end 11 to a proximal end 12 and has a lumen 13 extending therethrough. The pumping device 1 attached to the distal end 11 of the catheter 10 as shown in FIG. 1 is not shown in FIG. 2. The lumen 13 of the catheter 10 is defined by a wall 14 of the catheter 10, which may have a wall thickness of about 0.1 mm to 1 mm, for example 0.5 mm. The catheter 10 may have an outer diameter of 2 mm to 4 mm, for example about 3 mm (corresponding to a 9 French dimension). Thus, the inner diameter of the catheter may be, for example, about 2 mm (corresponding to a 7 French dimension). A stiffening structure in the form of an elongated rod 15 is disposed within the catheter lumen 13 and extends from a distal end 16 to a proximal end 17. A tubular stiffening structure 15 extends continuously through the catheter 10 from the catheter's distal end 11 to its proximal end 12. Other structures that may extend through the catheter 10, such as purge lines or electrical wires, are omitted from FIG. 2 for clarity.

[0026] The rod 15 is made, in particular, from Nitinol, and provides sufficient bending stiffness to prevent the catheter 10 from kinking, while allowing the catheter 10 to bend to conform to the shape of the blood vessel, such as the aorta AO, and in particular the aortic arch AA. As shown in FIG. 2, the rod 15 is free-floating within the lumen 13 of the catheter 10, i.e., loose and not fixed inside the catheter 10. This allows the rod 15 to follow a slightly different radius of curvature than the catheter 10 while moving inside the catheter lumen 13. The rod 15 is also allowed to slide, in particular axially, inside the lumen 13, which may be advantageous for the flexibility of the catheter 10. The distal end 16 of the rod 15 is free, in particular not attached to the pumping device 1 or any part of the pumping device 1. Both the distal and proximal ends of the rod 15, or at least one of them, may be protected or wrapped with a soft tip to avoid penetrating the catheter 10 or other adjacent structures.

[0027] The rod-like stiffening structure preferably has a solid cross-section, ie no lumens or the like extending therethrough, but may have different cross-sectional shapes.

[0028] In another embodiment (not shown), the rod can be tubular and can function as a line for a purge fluid or for supplying a gas, and thus the tubular rod can be attached to a pump or other structure that requires the presence of a transported fluid or gas.

[0029] As shown in Figure 3, the cross-sectional shape is preferably circular or substantially circular. In another embodiment, the rod 15A can have a rectangular or square cross-section, as shown in Figure 4. In yet another embodiment, multiple rods 15B can be provided, such as three rods 15B as shown in Figure 5. The rods 15B can be identical or different in terms of shape and size. In another embodiment (not shown), the multiple rods can be braided. The bending stiffness of the rods 15B add up to the desired total bending stiffness of the stiffening structure.

[0030] It will be understood that any of the stiffening structures 15, 15A and 15B may be combined with one another. As shown in Figures 3-5, a purge fluid line 18 for supplying purge fluid to the pumping device 1, and an electrical wire 19 for supplying power to the pumping device 1 may be inserted into the catheter lumen 13. The stiffening structure 15 is particularly useful for preventing the catheter 10 from kinking, which could block the purge line 18 and lead to blood pump failure due to excessive purge pressure or lubrication being cut off.

[0031] As explained above, rod 15 may extend linearly longitudinally through catheter 10 to increase the catheter's resistance to kinking. Rod 15 may be inserted into catheter 10 during insertion of pumping device 1 into a patient. Rod 15 may remain in the catheter or may be removed after insertion to make catheter 10 flexible and therefore less traumatic to the surrounding tissue.

[0032] Regardless of its shape, size and configuration, the stiffening structure 15 comprises or is made from a shape memory material, preferably a shape memory alloy, in particular Nitinol. Due in particular to this material, the stiffening structure 15 allows the catheter 10 to bend, i.e., to elastically deform, with a bending radius of 10 mm or less, without kinking, i.e., without plastic deformation occurring. The bending radius is measured relative to the central axis of the catheter. For this reason, a catheter 10 having a stiffening structure 15 made of a shape memory material, for example a catheter having a Nitinol wire, provides better bending stiffness. The desired bending stiffness properties result primarily from the superelastic properties of Nitinol. Preventing kinking of the catheter is important, for example, to prevent the blocking of the tubular line inside the catheter.

Claims

1. An intravascular blood pump for percutaneous insertion into a blood vessel of a patient, comprising a catheter (10) and a pumping device (1) attached to the catheter (10), the catheter (10) extending along a longitudinal axis and having a distal end (11) and a proximal end (12) opposite the distal end (11) along the longitudinal axis, the catheter (10) including an elongated stiffening structure (15) extending longitudinally and continuously along the length of the catheter (10) between the proximal end (12) and the distal end (11) of the catheter (10), the stiffening structure (15) having a stiffening force of about 0.00005 Nm ２ ~Approx. 0.01Nm ２ When bent with a minimum bending radius of 10 mm, it does not undergo plastic deformation. The stiffening structure includes at least one rod or wire (15); A blood pump, characterized in that the cross section of said at least one rod or wire (15) is not rotationally symmetric.

2. 2. The blood pump of claim 1, wherein the catheter (10) has at least one lumen (13) extending through the catheter (10) from the proximal end (12) to the distal end (11), and the stiffening structure (15) is disposed within the lumen (13) of the catheter (10).

3. 3. A blood pump according to claim 2, characterized in that the stiffening structure (15) is loose inside the lumen (13) of the catheter (10).

4. A blood pump according to any one of claims 1 to 3, characterized in that the stiffening structure comprises a plurality of rods or wires (15B).

5. 2. The blood pump of claim 1, wherein the at least one rod or wire is solid.

6. 2. The blood pump of claim 1, wherein said at least one rod or wire (15) has a diameter of about 0.3 mm to 0.6 mm.

7. 7. Blood pump according to claim 6, characterized in that said at least one rod or wire (15) has a diameter of about 0.5 mm.

8. 2. A blood pump according to claim 1, characterized in that said at least one rod or wire (15) is straight.

9. 5. The blood pump of claim 4, wherein the plurality of rods or wires are braided.

10. A blood pump according to any one of claims 1 to 3, characterized in that the bending stiffness of the stiffening structure (15) is different for bending of the stiffening structure (15) in different planes.

11. 11. The blood pump of claim 10, wherein the catheter (10) is curved in a plane and the stiffening structure (15) has a minimum bending stiffness for bending in the plane in which the catheter (10) is curved.

12. A blood pump according to any one of the preceding claims, characterized in that the stiffening structure (15) comprises a shape memory material.

13. 13. The blood pump according to claim 12, characterized in that the stiffening structure (15) comprises Nitinol as shape memory material.

14. A blood pump according to any one of claims 1 to 3, characterized in that the stiffening structure (15) is configured to remain within the catheter (10) during operation of the blood pump.

15. A blood pump according to any one of claims 1 to 3, characterized in that the stiffening structure (15) is configured to be removed from the catheter (10) after the blood pump has been placed in the patient's body.

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