Cannula for use in a catheter pump and minimizing fiber pull-out and method of making same, catheter pump

Abstract

A cannula is disclosed comprising a polymer layer and a reinforcing layer embedded within the polymer layer, the polymer layer having a first channel therein for passage of a sensor cable, at least a portion of the first channel being located inwardly of the reinforcing layer.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to an intubation cannula and its manufacturing method, and a catheter pump. Background Technology

[0002] In embodiments where a distal sensor is configured in a catheter pump, the optical fiber passes through a fiber optic sheath positioned on the catheter. During catheter pump intervention, the catheter repeatedly bends and straightens to conform to the tortuous course of the patient's blood vessels, causing the optical fiber to move axially within the sheath. However, since the optical fiber is typically fixed at both ends of the catheter along its axial direction, it can only absorb this axial movement through its own deformation or outward bending. The outward bending of the optical fiber acts on the wall of the sheath. Clinically, it has been observed that this force is significant enough to puncture the sheath, leading to fiber exposure.

[0003] In the solution provided by CN118450921A, the fiber optic sleeve is placed on the outer surface of the insertion tube. By increasing the inner diameter and wall thickness of the fiber optic sleeve, redundant space for axial movement of the fiber is provided within the sleeve to prevent fiber detachment. However, this results in an increase in the outer diameter of the insertion tube, leading to an increase in the insertion dimensions.

[0004] In the solution provided by CN219148951U, the fiber optic sheath is placed inside the wall of the insertion tube. This solution does not increase the outer diameter of the insertion tube, but it reduces the wall thickness of both the fiber optic sheath and the insertion tube, making the fiber more susceptible to puncture and detachment. Summary of the Invention

[0005] This invention provides a cannula and its manufacturing method, as well as a catheter pump, which aims to improve the radial strength of the cannula without significantly increasing or even increasing the outer diameter of the cannula, thereby preventing sensor cables inserted into its wall from coming out.

[0006] To achieve the above objectives, the present invention proposes the following solution:

[0007] The cannula includes a polymer layer and a reinforcing layer embedded in the polymer layer. The polymer layer has a first channel for the sensor cable to pass through, and at least part of the first channel is located radially inside the reinforcing layer.

[0008] The method for fabricating the cannula includes placing a first tube body, a reinforcing layer, and an outer polymer tube radially outside an inner polymer tube, with the first tube body at least partially located radially inside the reinforcing layer. A heat reflow process is performed to form the inner polymer tube, outer polymer tube, and first tube body into an inner polymer layer, an outer polymer layer, and a first channel, respectively. The inner and outer polymer layers are fused together, encapsulating the reinforcing layer and the first tube body within them.

[0009] The catheter pump includes a cannula as described above or a cannula manufactured using the method described above. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the catheter pump of the present invention applied to left ventricular assist;

[0011] Figure 2 for Figure 1 Schematic diagram of the intermediate pump assembly;

[0012] Figure 3 This is a schematic diagram of the cannula structure of the present invention;

[0013] Figure 4 A three-dimensional view of the inner and outer metal spring wires of the cannula;

[0014] Figure 5 for Figure 4 The main view;

[0015] Figure 6 for Figure 4 Radial cross-sectional view;

[0016] Figure 7 This is a schematic diagram of the assembly of the first tube, the second tube, and the inner metal spring wire;

[0017] Figure 8 for Figure 7 Top view;

[0018] Figure 9 This is a schematic diagram of the flattening and forming process of the first tube.

[0019] Figure 10 This is a schematic diagram illustrating the test of whether the optical fiber is damaged after the insertion tube of the present invention and the insertion tube of the comparative example are subjected to violent bending.

[0020] Figure 11 This is a timing diagram showing the continuous output of optical signals by the optical fiber after the insertion tube of the present invention is subjected to violent bending.

[0021] Figure 12 This is a schematic diagram showing the anti-kink performance test of the cannula of the present invention and the cannula of the comparative example;

[0022] Figure 13 This is a schematic diagram of the radial compression test of the cannula of the present invention and the cannula of the comparative example;

[0023] Figure 14 According to Figure 13 The force-displacement curve obtained from the test;

[0024] Figure 15 This is a schematic diagram showing the three-point bending performance test of the cannula of the present invention and a comparative cannula;

[0025] Figure 16 According to Figure 15 The force-displacement curve obtained from the test;

[0026] Figure 17 This is a schematic diagram showing the straight section bending performance test of the cannula of the present invention and the comparative cannula;

[0027] Figure 18 According to Figure 17 The force-displacement curve obtained from the test;

[0028] Figure 19 This is a schematic diagram showing the cannula of the present invention and a comparative cannula with respect to cantilever bending performance tests;

[0029] Figure 20 According to Figure 19 The force-displacement curve obtained from the test. Detailed Implementation

[0030] The terms "proximal" and "distal" are relative to the physician operating the catheter pump. "Proximal" refers to the portion relatively close to the physician, and "distal" refers to the portion relatively far from the physician. For example, the catheter may be located proximally to the pump assembly, and the pump assembly may be located distally to the catheter. It should be understood that these directional terms are defined for ease of description and are not restrictive or absolute.

[0031] like Figures 1 to 2 As shown, the catheter pump includes a catheter 50, a pump assembly 90 located at the distal end of the catheter 50, and a controller 70 located outside the patient's body for controlling the operation of the pump assembly 90. The pump assembly 90 includes a cannula 10, a first blood window 33 and a second blood window 32 connected to the proximal and distal ends of the cannula 10, an impeller (not shown) located within the first blood window 33, a motor 20 connected between the catheter 50 and the first blood window 33, and a protective structure 40 (a pigtail tube or a round blunt-tipped structure) connected to the distal end of the second blood window 32. The first blood window 33 has a first opening 331, and the second blood window 32 has a second opening 321. One of the openings 331 and 332 constitutes an inlet and the other a bleeding outlet, depending on the application of the catheter pump. When the catheter pump is used for left ventricular assist, opening 331 is the bleeding outlet and opening 321 is the inlet. When the catheter pump is used for right ventricular assist, opening 331 is the inlet and opening 321 is the bleeding outlet. Taking a catheter pump for left ventricular assist as an example, the pump assembly 90 is inserted into the patient's body percutaneously. It is pushed forward by the catheter 50 in the patient's aorta AO until the distal end of the pump assembly 90 passes through the aortic valve AV and enters the left ventricle LV, so that the cannula 10 crosses the aortic valve AV, with opening 321 located in the left ventricle LV and opening 331 located in the aorta AO. The motor 20 drives the impeller to rotate, drawing blood from the left ventricle LV into the cannula 31 through opening 321 and pumping it from opening 331 to the aorta AO to assist the heart's pumping function and reduce the burden on the heart.

[0032] The use of a catheter pump for left ventricular assist is only one feasible application scenario. It can also be used for right ventricular assist (opening 331 is located in the right ventricle, and opening 321 is located in the pulmonary artery) or kidney assist, and this embodiment is not limited to this. The following description mainly focuses on the use of a catheter pump for left ventricular assist, but based on the above description, the scope of protection of this embodiment is not limited thereto. The above is an embodiment of a catheter pump using a built-in motor, but an external motor can also be used. The motor is connected to the proximal end of the catheter 50, and the rotation is transmitted to the impeller through a flexible shaft passing through the catheter 50.

[0033] The pump assembly 90 also includes a distal sensor 80 adjacent to the second opening 321, and may also include a proximal sensor 30 adjacent to the first opening 331. After the pump assembly 90 is correctly positioned, sensor 80 is used to measure the actual pressure LVP in the location of opening 321 (left ventricle LV), and sensor 30 is used to measure the actual pressure AOP in the location of opening 331 (aorta AO).

[0034] A cable 60 is threaded through the conduit 50 for electrical and signal connection between the pump assembly 90 and the controller 70. The cable 60 includes a wire connected to the motor 20 for transmitting electrical signals to the motor 20 to drive its rotation. The cable 60 also includes sensing cables connected to sensors 30 and 80 for transmitting signals measured by the sensor heads of sensors 30 and 80 to the controller 70. The controller 70 can store the electrical signals from the drive motor 20 and the pressure signals measured by sensors 30 and 80 in its memory, and can correlate the electrical and pressure signals with time for display on a screen.

[0035] Sensors 30 and 80 can adopt any suitable existing structure, including but not limited to piezoelectric pressure sensors, piezoresistive pressure sensors, optical pressure sensors, etc., and this embodiment does not limit them. The sensing cables corresponding to the various types of pressure sensors mentioned above are cables, optical fibers, and optical fibers, respectively. The following description mainly uses optical fibers as the main scenario, and the scope of protection of this embodiment is not limited thereto.

[0036] like Figure 3 As shown, the cannula 10 includes a curved section 101 and a straight section connected to at least one end of the curved section 101. Preferably, there are two straight sections: a proximal straight section 1021 connected to the motor 20 via a first blood window 33, and a distal straight section 1022 connected to the motor 20 and via a second blood window 32. The curved section 101 is approximately arc-shaped with a central angle of 135°-155°, and the two straight sections 1021 and 1022 are respectively connected to the two ends of the curved section 101, forming an included angle of 135°-155° between the two straight sections 1021 and 1022.

[0037] like Figures 3 to 7 As shown, the cannula 10 includes a polymer layer and a reinforcing layer embedded within the polymer layer. The polymer layer contains a first channel 151 for the optical fiber 821 of the sensor 80 to pass through, with at least a portion of the first channel 151 located radially inside the reinforcing layer. By placing the first channel 151 within the wall of the cannula 10, it does not occupy additional space on the outer side of the cannula 10, and the outer diameter of the cannula 10 does not increase significantly or even at all. This is advantageous for reducing the interventional size of the catheter pump. Since the first channel 151 is at least partially located radially inside the reinforcing layer, the reinforcing layer enhances its resistance to radial forces. The outward flexing deformation of the optical fiber 821 within the first channel 151 due to bending of the cannula 10 is limited by the reinforcing layer, preventing the optical fiber 821 from piercing the cannula wall and detaching from the cannula 10.

[0038] The polymer layer includes an inner polymer layer 111 and an outer polymer layer 121 located radially outside the inner polymer layer 111. The first channel 151 is located between the inner polymer layer 111 and the outer polymer layer 121. As described below, the inner and outer polymer layers 111 and 121 are formed by inner and outer polymer tubes 11 and 12, respectively, through a hot reflow process. The outer polymer tube 12 and the first tube body 15 for defining the first channel 151 are pre-positioned outside the inner polymer tube 11. During subsequent hot reflow, the inner and outer polymer tubes 11 and 12 fuse together to form a whole, namely the polymer layer, which encloses the first tube body 15 within it.

[0039] Therefore, the first channel 151 is positioned between the inner and outer polymer layers 111 and 112. This not only meets the needs of the manufacturing process of the cannula 10, which is beneficial to improving manufacturing efficiency, but also avoids structural defects in the final cannula 10 caused by the introduction of the first tube body 15 used to define the first channel 151. For example, if the first tube body 15 is pre-formed or embedded in the wall of a polymer tube, this will not only result in low material acquisition efficiency and increased costs, but the polymer tube embedded in the first tube body 15 will also undergo secondary heat reflow and melt again, which may cause the position of the first tube body 15 to change. The displacement of the first tube body 15 may be accompanied by other adverse consequences, such as bending or even kinking / collapse / kneading of the first tube body 15 due to different displacement amounts in different tube segments, and the formation of cavitation in the tube wall. These adverse consequences are unacceptable. For example, bending, kinking, or twisting of the first tube 15 will make it difficult or even impossible for the optical fiber 821 to pass through the first channel 151; cavitation will reduce the strength of the cannula 10, making it prone to breakage and causing gas to escape from the cavitation. The escaped gas can form a gas embolism, which is extremely harmful to the patient. Therefore, the positioning of the first channel 151 between the inner and outer polymer layers 111 and 112 is beneficial to improving product yield.

[0040] Furthermore, the outer polymer layer 121 is thicker than the inner polymer layer 111, and the first channel 151 is formed in the outer polymer layer 121 and adjacent to the inner polymer layer 111. Thus, the thicker outer polymer layer 121 provides sufficient space to fix the first channel 151, which facilitates the stability of the first channel 151's position. In addition, the positioning of the first channel 151 in the outer polymer layer 121 and adjacent to the inner polymer layer 111 allows the polymer material to be stacked as far as possible on the outside of the first channel 151, providing at least a partial radial strength gain to the first channel 151 and further reducing the risk of the optical fiber 821 piercing the insertion tube wall and detaching.

[0041] As described above, the inner and outer polymer tubes 11 and 12 essentially fuse together after heat reflow, forming a single polymer layer. Therefore, it should be understood that there is actually no structural distinction between inner and outer polymer layers 111 and 121 in the insertion tube 10; this limitation is used in this embodiment only for ease of description. To ensure optimal fusion of the inner and outer polymer tubes 11 and 12 after heat reflow, certain material properties of both, especially melting temperature / melting temperature range, coefficient of thermal expansion, surface tension, chemical compatibility, and rheological properties, should be approximately the same. A more preferred approach is to use the same type of tube, such as, but not limited to, any one of polyurethane (PU), polyethylene (PE), polyvinyl chloride (PVC), polyetheretherketone (PEEK), or polyether block amide (PEBAX).

[0042] The reinforcing layer includes an inner metal spring wire 13 spirally arranged circumferentially and axially, and an outer metal spring wire 14 located outside the inner metal spring wire 13. The inner metal spring wire 13 is embedded between the inner and outer polymer layers 111 and 121, and the outer metal spring wire 14 is embedded within the outer polymer layer 121. The first channel 151 is located at least partially radially inside the reinforcing layer in two ways: the first channel 151 is entirely located radially inside the reinforcing layer, i.e., the first channel 151 is located inside the inner metal spring wire 13. Alternatively, the first channel 151 is partially located radially inside the reinforcing layer, i.e., the first channel 151 is located between the inner metal spring wire 13 and the outer metal spring wire 14, i.e., only radially inside the outer metal spring wire 14. In the first method, the first channel 151 is provided with stronger radial strength support, enabling the insertion tube 10 to withstand greater bending stress on the optical fiber 821 without being punctured, thus better preventing the optical fiber 821 from detaching. In the second scheme, the first channel 151 sandwiched between two layers of metal coiled wires 13 and 14 is simultaneously provided with radial inward and outward strength gains, which makes up for the deficiency of insufficient strength on the inner surface of the insertion tube 10, thereby providing the insertion tube 10 with the function of preventing the optical fiber 821 from piercing both the inner and outer surfaces.

[0043] The first channel 151 is formed by the first tube 15, which, together with the second tube 16 and the third tube 17 described below, is a polyimide (PI) tube. Figures 6 to 7 As shown, in one embodiment, at least a portion of the radial cross-sectional shape of the first channel 151 is a notched annular shape extending circumferentially. The notched annular shape refers to a shape that extends in a ring shape circumferentially, but not to a full circle. Thus, the notched annular channel section of the first channel 151 provides circumferential displacement space for the optical fiber 821. When the insertion tube 10 deforms, causing the optical fiber 821 to be compressed axially, the optical fiber 821 can move circumferentially within the notched annular channel section of the first channel 151 to counteract the deflection of the optical fiber 821, rather than pushing against the wall of the first channel 151 radially outward, thus avoiding puncturing the tube wall and detaching. Simultaneously, the notched annular channel section of the first channel 151 also provides redundant configuration space for the optical fiber 821. When the insertion tube 10 deforms, causing the optical fiber 821 to be stretched axially, the redundantly configured optical fiber 821 within the notched annular channel section of the first channel 151 can be moved out to counteract the axial stretch, preventing the optical fiber 821 from being broken.

[0044] like Figure 2As shown, in another embodiment, the sensing head 81 of the distal sensor 80 can be fixed to the second blood window 32 by adhesive bonding. The distal end of the optical fiber 821 is connected to the sensing head 81 and is therefore fixed to the second blood window 32 as well. The portion of the optical fiber 821 that extends out of the first channel 151 is axially movable relative to the first channel 151. Therefore, the distal end of the optical fiber 821 is fixed, while the portion extending from the proximal end of the cannula 10 (hereinafter referred to as the proximal end) is relatively movable. In this way, when the cannula 10 bends and deforms, the optical fiber 821, with only its distal end fixed, can counteract axial stretching or compression through the axial movement of its free proximal end, thereby preventing the optical fiber 821 from being pulled off or punctured by the cannula 10.

[0045] The near-end axially movable aspect of the optical fiber 821 is achieved via a third tube 17 extending from the motor 20. In one embodiment, such as Figure 2 As shown in A1, the inner diameter of the third tube 17 is greater than or equal to the outer diameter of the first tube 15, and the proximal end of the first tube 15 is inserted into the distal end of the third tube 17. Alternatively, in another embodiment, as... Figure 2 As shown in Figure A2, the diameter of the third tube 17 is approximately the same as that of the first tube 15 (including both inner and outer diameters), and the proximal end of the first tube 15 is joined to the distal end of the third tube 17. The length of the first tube 15 is greater than the length of the insertion tube 10, and both ends of the first tube 15 protrude beyond the ends of the insertion tube 10, so that both ends can be fixed at corresponding rigid structures. The first tube 15 and the third tube 17 can be bonded together with adhesive material Z, or they can be fixed by heat fusion by applying heat shrink tubing over both (not shown in the figure). The optical fiber 821 is led out to the controller 70 sequentially through the first tube 15, the third tube 17, and the conduit 50.

[0046] The outer diameter of the optical fiber 821 is smaller than the inner diameter of the first tube 15. By configuring a third tube 17 with a larger inner diameter to be sleeved with the first tube 15, or by having a third tube 17 of approximately the same diameter to be mated with the end of the first tube 15, an axially movable channel is constructed for the optical fiber 821, which is not fixed at the proximal end. This counteracts the axial tension or compression of the optical fiber 821 caused by the bending of the insertion tube 10. In addition, the connection between the third tube 17 and the first tube 15 is located on the rigid outer wall of the first blood window 33 or the motor 20. This facilitates the stability of the position and shape of the two tubes, thereby ensuring that the movable channel remains unobstructed for a long time and that the optical fiber 821 can move smoothly axially when needed.

[0047] like Figure 10 and Figure 11 The test shown demonstrates whether the optical fiber is damaged after the cannula is subjected to violent bending. Among other things... Figure 10 (a) to Figure 10 (c) is the cannula 10 in this embodiment, with the far end of the optical fiber 821 fixed and the near end not fixed. Figure 10 (d) to Figure 10(e) is a comparative example where both the distal and proximal ends of the optical fiber are fixed. By bending the cannula to different sides, the optical fiber is observed to see if it leaks light or punctures the cannula and comes out, thus verifying the degree of forceful bending that would damage the optical fiber. Figure 10 As shown in (d), the comparative cannula only bends approximately 90° inwards towards the bend, and the optical fiber then exhibits the following behavior: Figure 10 The light leakage phenomenon shown by the elliptical box in (e) indicates that the optical fiber has broken. In this embodiment, the insertion tube 10 experiences... Figure 10 (a) shows a bend of approximately 90° towards the inside of the curved section, as shown in the image. Figure 10 (b) shows a bend of approximately 30° to the outside of the curved section, as shown in [example]. Figure 10 (c) After bending in three directions—lateral bending of approximately 45° towards the bent section—the fiber optic cable 821 did not break or detach from the cannula 10. Figure 11 The diagram shows the optical signal output timing of the optical fiber 821 configured on the insertion tube 10 in this embodiment during the test. It can be seen that from the start of the bending test at 786 seconds to the end of the bending test at 898 seconds, the optical fiber 821 continuously output an optical signal without interruption. This indicates that the optical fiber 821 did not suffer any structural damage during the 112 seconds of the bending test. It should be noted that... Figure 10 (b) Figure 10 (c) Figure 10 The exposed optical fiber in (d) was not detached from the cannula 10, but rather the applicant simplified the assembly of the sample under test for testing purposes and did not insert the optical fiber into the motor.

[0048] like Figures 3 to 7 As shown, the inner metal spring wire 13 is a single-strand flat wire with a radial cross-sectional shape that extends elongatedly along the circumference, roughly rectangular in shape. The outer metal spring wire 14 is as follows... Figure 3 The single-strand round wire shown or as Figures 4 to 7The multi-strand round wires shown have a roughly circular radial cross-sectional shape. The circumferential width or cross-sectional area of ​​the inner metal spring wire 13 is larger than that of the outer metal spring wire 14. Furthermore, the pitch of the inner metal spring wire 13 is smaller than the minimum pitch of the outer metal spring wire 14 (as described below, this minimum pitch is the pitch of the outer metal spring wire 14 at the proximal end of the straight section 1021), for example, the pitch of the inner metal spring wire 13 is only 10% or even less of the minimum pitch of the outer metal spring wire 14. Therefore, the inner metal spring wire 13 is more dense than the outer metal spring wire 14. Thus, the wider and denser inner metal spring wire 13 provides high radial stiffness to the cannula 10, maintaining the high toughness of the cannula 10 to ensure that the cannula 10 has better pushability. Compared to traditional cannulas with a single-layer metal spring wire, the newly introduced outer metal spring wire 14 in the cannula 10 of this embodiment further increases the radial stiffness of the cannula 10, and causes the cannula 10 to require greater force to bend in certain directions (hereinafter referred to as...). Figure 12-18 (As demonstrated by the experimental introduction). Therefore, the narrower and sparser outer metal spring wire 14 is used to further improve the radial stiffness of the cannula 10 and the beneficial bending resistance in certain directions, while avoiding excessive expansion of the bending resistance of the cannula 10, so that the cannula 10 can maintain its flexibility, thereby enabling the cannula 10 to adapt to the tortuous course of the blood vessel and deform, so as to achieve smooth intervention of the pump assembly 90.

[0049] like Figures 12 to 18 As shown, the experiment also proved that the above-mentioned double-layer metal spring wire structure can not only minimize the fiber 821 from coming out, but also greatly improve the anti-kink properties, radial stiffness, and bending properties of the cannula 10. These performance improvements are very important for the cannula 10 to be used in catheter pumps.

[0050] like Figure 12 The anti-kink performance test shown, and as shown Figure 13 and Figure 14 The radial stiffness test is shown. Among them, Figure 12 (a) Figure 12 (b) and Figure 13 (a) is the insertion cannula 10 using double-layer metal coiled wire in this embodiment. Figure 12 (c) Figure 12 (d) and Figure 13 (b) is a comparative example of a conventional cannula using a single-layer metal spring wire. For example... Figure 12 As shown, by twisting the insertion tube around a conical test workpiece with a gradually changing outer diameter and observing the kinking of the tube, the anti-kinking performance of different insertion tubes can be compared visually or qualitatively. Figure 13 As shown, by placing the cannula on a flat test platform and pressing it down with a pressure head, the following result is obtained: Figure 14The curve showing the relationship between the indenter displacement and the compressive force can quantitatively reflect the radial stiffness of different insertion tubes. Figure 12 (c) Figure 12 (d) It can be seen that the comparative example shows a kink when the insertion tube is wound around the test workpiece with a diameter of φ15mm, while the insertion tube 10 in this embodiment does not show a kink when wound around the test workpiece with a diameter of φ15mm (e.g., Figure 12 (b) As shown, even when twisted around a test workpiece with a smaller diameter (φ14mm), the radial structure remains intact (as shown). Figure 12 (as shown in (a)). And from Figure 13 As can be seen, with the increase of the compression amount, the compression force applied to the cannula 10 in this embodiment is always greater than that applied to the cannula in the comparative embodiment, and the rate of increase of the compression force with the compression amount is also significantly greater. This indicates that, to achieve the same amount of radial collapse, the cannula 10 in this embodiment can withstand a greater compression force; or, for the same compression force, the cannula 10 in this embodiment experiences less radial collapse. Therefore, in summary, the cannula 10 in this embodiment has greater radial stiffness, better performance in maintaining its radial shape, and can maintain the integrity of its radial structure without easily collapsing when subjected to greater bending or compression, exhibiting better anti-kinking performance. This is advantageous for maintaining smooth blood flow, ensuring the normal operation of the catheter pump, and preventing kinking to facilitate the smooth delivery of the pump assembly 90.

[0051] like Figure 15 and Figure 16 The three-point bending performance test is shown. Among them, Figure 15 (a) is the cannula 10 in this embodiment. Figure 15 (b) A comparative example using a traditional insert with a single-layer metal spring wire. By placing the bent section of the insert on the notched test workpiece and pressing the insert down with an indenter, the following result is obtained: Figure 16 The curve showing the relationship between the indenter displacement and the downward pressure quantitatively reflects the performance of different cannulas in maintaining their bending configuration. It can be seen that, except in the initial stage of displacement (approximately 0-2 mm), as the downward displacement increases, the downward pressure applied to the cannulas 10 in this embodiment is greater than that applied to the cannulas in the comparative embodiment, and the rate of increase in downward pressure with displacement is also significantly greater. This indicates that, to achieve the same displacement bending in the bending section, the cannulas 10 of this embodiment can withstand a greater force; or, with the same force, the cannulas 10 of this embodiment bends to a lesser degree in the bending section. In other words, the cannulas 10 of this embodiment maintains its existing bending configuration better. Figure 1As shown, the purpose of configuring the cannula 10 in a curved shape is to point the protective structure 40 approximately towards the apex of the heart, thereby positioning the blood inlet in the center of the ventricle to avoid contact with the ventricular wall. Therefore, the cannula 10 in this embodiment maintains its existing curved configuration better, meaning that even with external forces, the pump assembly 90 will not easily change its curved configuration after insertion into the patient's heart. This ensures that the pump assembly 90 maintains a stable position in the patient's heart, preventing adverse events such as tissue damage, decreased pump flow, and suction caused by the blood inlet contacting the ventricular wall.

[0052] like Figure 17 and Figure 18 The straight section bending performance test is shown. Figure 17 (a) is the cannula 10 in this embodiment. Figure 17 (b) A comparative example using a traditional insert with a single-layer metal spring wire. By placing the straight section of the insert on the notched test workpiece and pressing the insert down with an indenter, the following result is obtained: Figure 18 The curve showing the relationship between the pressure head displacement and the downward pressure quantitatively reflects the straight-section bending performance of different cannulas. It can be seen that as the displacement increases, the downward pressure applied to the cannulas 10 in this embodiment is consistently greater than that applied to the cannulas in the comparative embodiment, and the rate of increase in downward pressure with displacement is also significantly greater. This indicates that, to achieve the same radial indentation in the straight section, the cannulas 10 in this embodiment can withstand a greater force; or, with the same force, the cannulas 10 in this embodiment exhibits a smaller degree of radial indentation in the straight section. In other words, the straight section of the cannulas 10 in this embodiment maintains its straight configuration better. Therefore, the straight section of the cannulas 10 has better axial stiffness or toughness, which means better pushability; the cannulas 10 will not easily bend or twist during forward push within the patient's blood vessel, ensuring smooth intervention of the pump assembly 90.

[0053] As described above, the curved section 101 of the cannula 10 is used to maintain the curved configuration of the cannula 10 after the pump assembly 90 is correctly positioned in the patient's heart. However, during the process of pushing the pump assembly 90 into the heart through the patient's tortuous blood vessels, the cannula 10 needs to deform to conform to the vessel's course. Due to the introduction of the outer metal spring wire 14, the bending resistance of the straight sections 1021 and 1022 of the cannula 10 is improved. Furthermore, since the two straight sections are respectively connected to the rigid motor 20 and the second blood window 32, it is unrealistic to expect either straight section 1021 or 1022 to bend significantly to conform to the blood vessel during the pushing process to achieve the insertion of the pump assembly 90. Therefore, the insertion of the pump assembly 90 can only be achieved by using the curved section 101 to conform to the bending deformation of the blood vessel.

[0054] As explained and demonstrated above, a narrower and sparser outer metal coil wire 14 can partially prevent excessive expansion of the bending resistance of the cannula 10. In order to further improve the flexibility of the bending section 101, the pitch of the outer metal coil wire 14 at the bending section 101 is configured to be greater than the pitch at the straight sections 1021 and 1022, so that the winding density of the outer metal coil wire 14 at the bending section 101 is further sparsed.

[0055] To verify the effectiveness of the above solution, the applicant performed the following intubation procedure: Figure 19 and Figure 20 The cantilever bending performance test is shown. Among them, Figure 19 (a) is the cannula 10 in this embodiment. Figure 19 (b) A comparative example is a traditional cannula using a single-layer metal coiled wire. The proximal straight section of the cannula is clamped and fixed by a chuck, while the distal straight section is suspended. A pressure head is used to press down on the end of the distal straight section, resulting in... Figure 20 The curve showing the relationship between the pressure applied by the indenter and the bending force quantitatively reflects the bending performance of different cannula sections. Since the proximal end of the cannula is connected to a rigid motor, the cantilever bending test accurately reflects the bending situation where the proximal end of the cannula is fixed and the distal end is free during pump assembly insertion. It can be seen that, for the same pressure applied, the cannula 10 in this embodiment requires less force (the scattered peaks on the curve are due to slippage of the distal straight section of the cannula against the indenter during the gradual pressure application, which does not affect the overall trend of the curve), and the lower bending force indicates that the cannula has better bending performance during pump assembly insertion.

[0056] The test results were surprising. Based on conventional understanding, the applicant believed that the introduction of the outer metal spring wire 14 would lead to a comprehensive improvement in the bending resistance of the cannula 10. However, the test results were unexpected: while the outer metal spring wire 14 improved the desired bending resistance, namely the straight section bending resistance that ensures cannula pushing and the three-point bending resistance that maintains the bending configuration of the cannula in a static state, it also reduced the undesirable bending resistance, namely the bending resistance of the curved section that ensures better bending performance of the cannula.

[0057] See Figure 1As described above, although both straight segments 1021 and 1022 are connected to a rigid structure, the distal straight segment 1022, after the pump assembly 90 is correctly positioned, is suspended in the patient's heart. The rigid structure connected to it—the second blood window 32—does not exert any force on it. Therefore, the distal straight segment 1022 hardly twists after the pump assembly 90 is successfully positioned. The rigid structure connected to the proximal straight segment 1021—the motor 20—is further connected to the catheter 50. Since the catheter 50 is located in the tortuous aorta AO, it will have a tendency to spring back due to the toughness of its own material, thereby exerting a transverse force F on the motor 20 in the aorta AO. Because the cannula 10 passes through the aortic valve LV and is clamped and fixed laterally by the aortic valve LV, the force F applied to the motor 20 is transmitted to the proximal straight section 1021 of the cannula 10 connected to it, but cannot cause the cannula 10 to move laterally. Instead, it can only act on the proximal straight section 1021, which makes the proximal part of the connection between the proximal straight section 1021 and the motor 20 very easy to twist.

[0058] In view of this, such as Figure 3 As shown, in one embodiment, the outer metal spring wire 14 of the near-end straight section 1021 is configured with variable pitch winding, specifically, the pitch gradually increases from near to far. That is, the outer metal spring wire 14 is denser at the near end of the near-end straight section 1021 and sparser at the far end. The dense outer metal spring wire 14 at the near end is used to increase the radial stiffness of the near-end portion of the near-end straight section 1021, thereby improving the kink resistance of the near end of the cannula 10 and preventing the cannula 10 from buckling at the connection with the second blood window 32 due to the lateral force F, ensuring the continuous normal operation of the pump assembly 90. The gradually sparse outer metal spring wire 14 provides a gradual transition of radial stiffness for the near-end straight section 1021, avoiding a significant radial stiffness gradient between the far end of the near-end straight section 1021 and the curved section 101, because practice has shown that a significant radial stiffness gradient is more likely to cause kinking.

[0059] The method for manufacturing the cannula 10 includes the following steps:

[0060] Material acquisition step S100 includes inner polymer tube 11, outer polymer tube 12, reinforcing layer, and first tube body 15.

[0061] Material preparation step S200: A first tube body 15, a reinforcing layer, and an outer polymer tube 12 are disposed outside the inner polymer tube 11, and the first tube body 15 is at least partially located on the radial inner side of the reinforcing layer.

[0062] Material forming step S300: Perform a heat reflow process to form an inner polymer layer 111 in the inner polymer tube 11 and an outer polymer layer 121 in the outer polymer tube 12. The first tube body 15 defines the first channel 151. The inner polymer layer 111 and the outer polymer layer 121 are fused together to form a polymer layer, which encapsulates the reinforcing layer and the first tube body 15.

[0063] In step S100, the reinforcing layer includes an inner metal coiled wire 13 and an outer metal coiled wire 14. Because the inner metal coiled wire 13 is densely arranged, it has a generally tubular profile when obtained. Conversely, the outer metal coiled wire 14 is subsequently sparsely arranged with variable pitch, making it difficult to present a similar tubular profile as the inner metal coiled wire 13 when obtained; it is mostly presented as a linear or coiled raw material.

[0064] The inner diameter of the outer polymer tube 12 and the inner metal spring wire 13 of the tubular profile should be slightly larger than the outer diameter of the inner polymer tube 11, so that the two can be smoothly connected to the outside of the inner polymer tube 11 during the material preparation step.

[0065] like Figure 9 As shown, in order to form at least a partially notched annular first channel 151, at least a portion of the first tube 15 needs to be flattened beforehand. It can be understood that the initial cross-sectional shape of the first tube 15 is as follows: Figure 9 The circle shown on the left. The flattening die includes a die M1 with a concave arc portion located at the bottom and a die M2 with a convex arc portion located at the top. The first tube 15 with an initial circular cross-section is placed on the lower die M1, and the two dies are operated to gradually approach and compress the first tube 15, flattening a portion of the first tube 15 into a notched ring shape as described above.

[0066] In step S200, one configuration involves the inner metal spring wire 13, the first tube 15, the outer metal spring wire 14, and the outer polymer tube 12 being arranged sequentially from the inside to the outside radially outside the inner polymer tube 11, forming a first channel 151 partially located inside the reinforcing layer as described above. Alternatively, the first tube 15, the inner metal spring wire 13, the outer metal spring wire 14, and the outer polymer tube 12 can be arranged sequentially from the inside to the outside radially outside the inner polymer tube 11, forming a first channel 151 entirely located inside the reinforcing layer as described above. The outer metal spring wire 14, which has a non-tubular profile, is directly wound around the outside of the inner polymer tube 11, with its pitch controlled during the winding process.

[0067] In step S300, the first tube 15 needs to be wrapped by the polymer material provided by the inner and outer polymer tubes 11 and 12 after melting. However, the introduction of the first tube 15 will adversely affect the fluidity of the polymer material after melting, causing the molten polymer material to flow more towards the circumference of the first tube 15 or even the opposite side. This will lead to problems such as material loss, incomplete wrapping, thinning of the wall thickness of the insertion tube 10 on the side where the first tube 15 is located, or even exposure of the first tube 15.

[0068] Therefore, as Figure 7 As shown, the outer wall of the inner polymer tube 11 forms two axially extending, circumferentially spaced first protrusions 112, defining a first groove 113 between the two first protrusions 112 that fits into the first tube body 15. The first protrusions 112 are part of the structure of the inner polymer tube 11 to ensure material consistency. In step S200, the first tube body 15 is placed within the first groove 113. The two first protrusions 112 defining the first groove 113 are melted and encapsulate the first tube body 15 in the subsequent step S300.

[0069] As described above, the stability of the position and shape of the first tube 15 is crucial, and regardless, other materials will always need to be placed into the inner polymer tube 11 after the first tube 15. The two first protrusions 112 can limit the first tube 15 when it is placed outside the inner polymer tube 11, preventing the first tube 15 from shifting or deforming due to the placement of subsequent materials. This contributes to the stability of the final position and shape of the first tube 15, ensuring the smooth insertion of the optical fiber 821. Furthermore, and more importantly, the two first protrusions 112 construct a larger wall thickness for the inner polymer tube 11 corresponding to the first tube 15. This provides material replenishment during hot reflow, allowing the first tube 15 to be more tightly wrapped by the molten polymer material, avoiding the aforementioned problems that occur when using an inner polymer tube with a uniform wall thickness during the hot reflow process.

[0070] In one embodiment, the outer wall of the inner polymer tube 11 forms two axially extending, circumferentially spaced second protrusions 114, defining a second groove 115 adapted to the second tube body 16 between the two second protrusions 114. The second groove 115 is located radially opposite to the first groove 113. Similarly, the second protrusions 114 are part of the structure of the inner polymer tube 11 to ensure material consistency. In step S200, the second tube body 16 is adapted to be placed within the second groove 115. The two second protrusions 114 defining the second groove 115 are melted and encapsulate the second tube body 16 in a subsequent step S300.

[0071] The second protrusion 114 can achieve the same or similar effect as the first protrusion 112, which will not be described in detail here. It should be emphasized that the second protrusion 114 is provided on the radial opposite side of the first protrusion 112, which can at least partially balance the material supplement provided by the first tube body 15 side of the insertion tube 10 due to the provision of the first protrusion 112, so that the final wall thickness of the insertion tube 10 is as uniform as possible on the side where the first tube body 15 is located, the side where the second tube body 16 is located, and the area between the two.

[0072] Similar to the first channel 151, a second channel 161 defined by the second tube 16 is formed within the polymer layer. The second channel 161 allows a wire / filament L to pass through, giving the cannula 10 and the catheter pump configured with the cannula 10 more practical functions. For example, a bending guidewire for adjusting the direction of the blood inlet 321, a cable for an electromagnetic position sensor for detecting the position of the blood inlet 321, a cable for an electrical sensor for sensing cardiac electrical impulses, and a cable for electrodes for sensing ECG / defibrillation / pacing can be passed through the second channel 161.

[0073] Furthermore, such as Figures 7 to 8 As shown, in some embodiments, the height of the protrusions 112 and 114 is greater than the thickness of the inner metal spring wire 13. The radially outer ends of the protrusions 112 and 114 are recessed inward to form multiple axially spaced notches Q. The recess depth of the notches Q is preferably approximately equal to the height of the protrusions 112 / 114. In this way, in the material arrangement sequence in which the inner metal spring wire 13, the tube body 15 / 16, the outer metal spring wire 14, and the outer polymer tube 12 are arranged from the inside to the outside of the inner polymer tube 11, the inner metal spring wire 13 can be embedded in the notches Q, avoiding the presence of the protrusions 112 / 114 causing the inner metal spring wire 13, which is arranged outside the inner polymer tube 11 first, to block the tube body 15 / 16 from entering the grooves 113 / 115.

[0074] The notch Q is adapted to the helical shape of the inner metal coiled wire 13, and the distance between adjacent notches Q is configured to be approximately equal to the pitch of the inner metal coiled wire 13. In this way, the notch Q can be used to provide a limiting and uniform pitch configuration for the inner metal coiled wire 13, preventing subsequent material configuration from causing changes in the axial position of the inner metal coiled wire 13, and maximizing the uniformity of the radial stiffness of the insertion tube 10.

[0075] It should be noted that in this specification, "approximately" can be understood as close to, approximately, or within a predetermined range from the target value. For example, the distance between adjacent notches Q being approximately equal to the pitch of the inner metal winding wire 13 can be a difference of 5%, or further, within 2%.

[0076] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cannula configured for use as a catheter pump, comprising a polymer layer and a reinforcing layer embedded within the polymer layer, the polymer layer having a first channel for a sensor cable to pass through, at least a portion of the first channel being located radially inside the reinforcing layer; The cannula includes a curved section and a straight section connected to at least one end of the curved section, the straight section including a proximal straight section connected to a motor of the catheter pump; The reinforcing layer includes an inner metal coiled wire and an outer metal coiled wire. The pitch of the outer metal coiled wire gradually increases from near to far in the straight section near its end. The pitch of the inner metal coiled wire is less than the minimum pitch of the outer metal coiled wire.

2. The cannulation according to claim 1, wherein the polymer layer comprises an inner polymer layer and an outer polymer layer, and the first channel is located between the inner polymer layer and the outer polymer layer.

3. The cannula of claim 2, wherein the thickness of the outer polymer layer is greater than the thickness of the inner polymer layer, and the first channel is formed in the outer polymer layer and adjacent to the inner polymer layer.

4. The cannula as claimed in claim 1, wherein the first channel is located between the inner metal spring wire and the outer metal spring wire; or, the first channel is located radially inside the inner metal spring wire.

5. The cannula as described in claim 1, wherein the pitch of the outer metal spring wire in the curved section is greater than the pitch in the straight section.

6. The cannula as described in claim 1, wherein the radial cross-sectional shape of the inner metal spring wire is approximately rectangular, and the radial cross-sectional shape of the outer metal spring wire is approximately circular.

7. The cannula of claim 1, wherein at least a portion of the radial cross-section of the first channel extends circumferentially along the cannula in a notched loop shape, so that the sensing cable has at least a degree of freedom of circumferential movement within the corresponding channel segment in the notched loop shape.

8. The cannula of claim 2, further comprising a second channel disposed within the polymer layer, the second channel and the first channel being disposed opposite each other in the same radial direction of the cannula.

9. A method for fabricating a cannula as described in any one of claims 1 to 8, comprising: Material configuration: A first tube body, a reinforcing layer, and an outer polymer tube are disposed radially outside the inner polymer tube, and the first tube body is at least partially located radially inside the reinforcing layer; Material forming: A hot reflow process is performed to form the inner polymer tube, the outer polymer tube, and the first tube body into an inner polymer layer, an outer polymer layer, and a first channel, respectively; wherein the inner polymer layer and the outer polymer layer are fused together and enclose the reinforcing layer and the first tube body therein.

10. The method of claim 9, wherein the reinforcing layer comprises an inner layer of metal spring wire and an outer layer of metal spring wire; In the material preparation step, the inner metal spring wire, the first tube, the outer metal spring wire, and the outer polymer tube are arranged sequentially from the inside to the outside; or, the first tube, the inner metal spring wire, the outer metal spring wire, and the outer polymer tube are arranged sequentially from the inside to the outside.

11. The method of claim 9, wherein the outer wall of the inner polymer tube forms two circumferentially spaced first protrusions, the first protrusions extending axially, and a first groove is defined between the two first protrusions; In the material preparation step, the first tube is placed in the first groove; In the material forming step, the two first protrusions deform and wrap around the first tube body during the hot reflow process.

12. The method of claim 9, further comprising, prior to the material preparation step: A flattening process is performed on at least a portion of the first tube body so that the radial cross section at at least a portion of the first tube body extends in a notched annular shape along the circumference of the insertion tube.

13. The method of claim 11, wherein the outer wall of the inner polymer tube forms two circumferentially spaced second protrusions, the second protrusions extending axially, and a second groove is defined between the two second protrusions; the second groove is located on the radially opposite side of the first groove; In the material preparation step, the second tube is placed in the second groove; In the material forming step, the two second protrusions deform and wrap around the second tube body during the hot reflow process.

14. The method of claim 13, wherein the height of the first protrusion and the second protrusion is greater than the thickness of the inner metal spring wire, and the radially outer ends of the first protrusion and the second protrusion are recessed inward to form a plurality of axially spaced notches, the recess depth of the notches being approximately equal to the height of the first protrusion and the second protrusion. In the material preparation step, the inner metal spring wire is embedded in the notch.

15. The method of claim 14, wherein the notches are arranged at axial spiral intervals, and the distance between two adjacent notches is approximately equal to the pitch of the inner metal spring wire.

16. A catheter pump comprising a cannula as described in any one of claims 1 to 8; or comprising a cannula made using the method described in any one of claims 9 to 15.

17. The duct pump of claim 16, further comprising: catheter; The pump assembly includes a motor connected between the catheter and the cannula, a second blood window connected to the distal end of the cannula, and an impeller driven by the motor to rotate for pumping blood. The sensor includes a sensing head and a sensing cable connected to the sensing head; the sensing head is disposed on the second blood window, and the sensing cable passes through the first channel; The distal end of the sensing cable is fixed to the second blood window via the sensing head, and the proximal portion of the sensing cable that extends out of the first channel is axially movable relative to the first channel.

18. The catheter pump of claim 17, further comprising a third tube extending from the motor, the cannula comprising a first tube defining the first channel; the outer diameter of the sensing cable being smaller than the inner diameters of the first tube and the third tube; the sensing cable being led out sequentially through the first tube, the third tube and the catheter to a controller located outside the patient's body.

19. The duct pump of claim 18, wherein the inner diameter of the third tube is greater than or equal to the outer diameter of the first tube, and the proximal end of the first tube is inserted into the distal end of the third tube; or, The diameter of the third tube is approximately the same as that of the first tube, and the proximal end of the first tube is connected to the distal end of the third tube.

20. The duct pump as claimed in claim 17, wherein the sensor is an optical pressure sensor and the sensing cable is an optical fiber.

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