percutaneous ventricular assist device

Abstract

This invention provides a percutaneous ventricular assist device, comprising a blood pump, an outer cannula assembly, a flexible drive shaft, and a protective structure. The outer cannula assembly is connected to the blood pump. The flexible drive shaft is housed within the outer cannula assembly, with its distal end connected to the blood pump and its proximal end used for connecting an external motor. The protective structure is disposed on the outer circumferential surface of the flexible drive shaft, and the coefficient of friction between the protective structure and the outer cannula assembly is between 0.04 and 0.20. In this percutaneous ventricular assist device, the motor drives the flexible drive shaft to rotate, thereby transferring kinetic energy to the blood pump. By controlling the coefficient of friction between the protective structure and the cannula within the aforementioned preferred range, the frictional resistance is reduced when the protective structure and the cannula slide relative to each other, thus reducing the amount of abrasive debris generated after contact and preventing the large accumulation of abrasive debris from entering the patient's body and harming the patient's health.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a percutaneous ventricular assist device. Background Technology

[0002] The core of a ventricular assist device (VAD) is an artificial blood pump connected in parallel with the heart. It simulates the ejection function of the ventricles, pumping blood from the ventricles into the arterial system, thus partially or completely replacing cardiac function. The blood pump is implanted in the patient's body, while the motor that powers it is located outside the body. Typically, a flexible shaft transmits the motor's energy to the internal blood pump, providing the necessary power for its normal operation.

[0003] A flexible shaft is a type of stainless steel flexible shaft that can flexibly transmit torsional motion to the desired position. In blood pump drives, one end of the flexible shaft connects to the internal blood pump, and the other end connects to an external motor, transferring the motor's kinetic energy to the internal blood pump. The flexible shaft has an outer sleeve around its periphery, and the flexible shaft passes through this sleeve. During the torsional transmission process, the flexible shaft will inevitably come into contact with the sleeve; that is, the flexible shaft cannot always remain in the center position of the sleeve during torsion.

[0004] When the torsion flexible shaft comes into contact with the cannula, it will wear down the inner wall of the cannula. Over time, the wear debris will accumulate. If the wear debris particles enter the patient's body, they will form a thrombus, endangering the patient's life and health.

[0005] In existing technologies, perfusion fluid is used to flush away abrasive debris. However, as the debris accumulates, the perfusion fluid becomes insufficient to remove the large amount of deposited debris, leading to blockage of the flushing channels. More seriously, because the flexible shaft does not always maintain a straight line when entering the body from outside the body, some sections of the flexible shaft are curved. Debris accumulates more easily in these curved sections, further narrowing the flushing channels. In the curved sections, more and more debris accumulates in the gap between the flexible shaft and the cannula, and the debris does not accumulate evenly around the circumference of the flexible shaft; instead, it accumulates on the inner side of the curve. The flexible shaft continuously wears down the inner wall of the cannula on the outer side of the curve. Consequently, the inner wall of the cannula on the outer side of the curve is quickly worn away, leading to perfusion fluid leakage and the failure of the entire percutaneous ventricular assist device. Summary of the Invention

[0006] The purpose of this invention is to provide a percutaneous ventricular assist device to solve the problem in the prior art that the flexible shaft generates a large amount of abrasive debris after colliding with the outer tube during the process of transmitting the kinetic energy of the motor to the blood pump, which endangers the life and health of patients and shortens the effective operating time of the percutaneous ventricular assist device.

[0007] To address the aforementioned technical problems, based on one aspect of the present invention, the present invention provides a percutaneous ventricular assist device, comprising:

[0008] Blood pump;

[0009] An outer tubing assembly, which is connected to the blood pump;

[0010] A flexible drive shaft is housed in the outer tube assembly, the distal end of the flexible drive shaft is connected to the blood pump, and the proximal end of the flexible drive shaft is used for connecting an external motor.

[0011] A protective structure is provided on the outer circumferential surface of the flexible transmission shaft, and the coefficient of friction between the protective structure and the outer tube assembly is between 0.04 and 0.20.

[0012] Optionally, the protective structure includes a coating and / or heat shrink tubing; the coating is applied to the outer peripheral surface of the flexible drive shaft; the heat shrink tubing is heat-shrink formed on the outer peripheral surface of the flexible drive shaft.

[0013] Optionally, the thickness of the coating is between 5 micrometers and 10 micrometers.

[0014] Optionally, the material of the protective structure includes FEP, PTFE, or PEEK.

[0015] Optionally, the outer tube assembly includes a sheath and a sleeve, the sleeve being housed within the sheath, the flexible drive shaft being housed within the sleeve, a radial gap between the sheath and the sleeve being configured as an infusion inflow channel, and a radial gap between the flexible drive shaft and the sleeve being configured as an infusion outflow channel. The blood pump has a diversion channel, the infusion inflow channel, the diversion channel, and the infusion outflow channel being sequentially connected. The diversion channel is used to split the perfusion fluid into two paths, allowing one path of the perfusion fluid to flow to the infusion outflow channel and the other path of the perfusion fluid to flow to the distal end of the blood pump.

[0016] Optionally, the sleeve material includes FEP, PTFE, PEEK, or PI.

[0017] Optionally, the outer tube assembly includes a sheath, and the flexible drive shaft is located within the sheath. The flexible drive shaft is hollow and tubular. The inner cavity of the flexible drive shaft is configured as a perfusion inflow channel. The blood pump has a diversion channel. The radial gap between the sheath and the flexible drive shaft is configured as a perfusion outflow channel. The perfusion inflow channel, the diversion channel, and the perfusion outflow channel are sequentially connected. The diversion channel is used to split the perfusion fluid into two paths, allowing one path of the perfusion fluid to flow to the perfusion outflow channel and the other path of the perfusion fluid to flow to the distal end of the blood pump.

[0018] Optionally, the sheath material includes FEP, PTFE, PEEK, or PI.

[0019] Optionally, a sealing tube is provided between the flexible drive shaft and the protective structure.

[0020] Optionally, the outer circumferential surface of the heat shrink tubing is provided with a first corrugation; the first corrugation is threaded or annular, and the heat shrink tubing includes the threaded first corrugation and / or a plurality of annular first corrugations arranged axially; the helical direction of the threaded first corrugation is the same as the rotation direction of the flexible drive shaft.

[0021] The percutaneous ventricular assist device described above uses a motor to drive a flexible drive shaft to rotate, thereby transferring kinetic energy to the blood pump. By setting a protective structure on the flexible drive shaft, and the friction coefficient between the protective structure and the outer tube assembly being between 0.04 and 0.20, the friction coefficient between the protective structure and the cannula is controlled within the above-mentioned preferred range. This results in lower frictional resistance when the protective structure and the cannula slide relative to each other, reducing the amount of abrasive debris generated after they come into contact. This prevents a large amount of abrasive debris from accumulating and entering the patient's body, thus avoiding harm to the patient's health. Attached Figure Description

[0022] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:

[0023] Figure 1 This is an axial cross-sectional view of the percutaneous ventricular assist device according to Embodiment 1 of the present invention;

[0024] Figure 2 This is a radial cross-sectional view of the percutaneous ventricular assist device according to Embodiment 1 of the present invention;

[0025] Figure 3 This is a partial axial cross-sectional view of the outer periphery of the flexible transmission shaft according to Embodiment 1 of the present invention;

[0026] Figure 4 This is a schematic diagram of a protective structure provided on a flexible transmission shaft according to Embodiment 1 of the present invention;

[0027] Figure 5 This is a first schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention;

[0028] Figure 6 and Figure 7 This is a second schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention;

[0029] Figure 8 This is a third schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention;

[0030] Figure 9 This is a fourth schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention;

[0031] Figure 10 This is an axial cross-sectional view of the percutaneous ventricular assist device according to Embodiment 2 of the present invention.

[0032] In the attached image:

[0033] 10-Blood pump; 11-Housing; 12-Drive shaft;

[0034] 20 - Outer tube assembly; 21 - Sheath; 22 - Sleeve;

[0035] 30 - Flexible drive shaft; 31 - Steel wire;

[0036] 40 - Protective structure; 41 - Heat shrink tubing; 42 - First corrugation;

[0037] 51-Injection inflow channel; 52-Diversion channel; 53-Injection outflow channel. Detailed Implementation

[0038] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.

[0039] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. “One end” and “the other end,” as well as “proximal end” and “distal end,” generally refer to two corresponding parts, including not only endpoints. The terms “installed,” “connected,” and “joined” should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral part; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements or an interaction between two elements. Furthermore, as used in this invention, the phrase "one element is disposed on another element" generally only indicates that there is a connection, coupling, cooperation, or transmission relationship between the two elements, and the connection, coupling, cooperation, or transmission between the two elements can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0040] In this article, "proximal" and "distal" are defined as follows: "proximal" usually refers to the end of the medical device that is close to the operator during normal operation, while "distal" usually refers to the end of the medical device that first enters the patient's body during normal operation.

[0041] Example 1

[0042] Figure 1 This is an axial cross-sectional view of the percutaneous ventricular assist device according to Embodiment 1 of the present invention. Figure 2 This is a radial cross-sectional view of the percutaneous ventricular assist device according to Embodiment 1 of the present invention. (See also...) Figure 1 and Figure 2This embodiment provides a percutaneous ventricular assist device, which includes a blood pump 10, an outer tubing assembly 20, a flexible drive shaft 30, and a protective structure 40. The blood pump 10 has a housing 11, a drive shaft 12, and an impeller (not shown). At least a portion of the drive shaft 12 is located within the housing 11, and the impeller is disposed at the distal end of the drive shaft 12. The outer tubing assembly 20 is connected to the blood pump 10. Specifically, the outer tubing assembly 20 is connected to the housing 11 of the blood pump 10. Further, the outer tubing assembly 20 includes a sheath 21 and a sleeve 22. The sheath 21 is connected to the housing 11 of the blood pump 10, and the sleeve 22 is housed in the sheath 21 and fixedly connected to the proximal end of the blood pump 10. The flexible drive shaft 30 is housed in the sleeve 22. The distal end of the flexible drive shaft 30 is connected to the blood pump 10. Specifically, the distal end of the flexible drive shaft 30 is connected to the drive shaft 12 of the blood pump 10, and the proximal end of the flexible drive shaft 30 is connected to a motor. The flexible drive shaft 30 may be made of stainless steel.

[0043] Thus, the motor drives the flexible transmission shaft 30 to rotate, which in turn drives the drive shaft 12 to rotate the impeller located at the distal end of the drive shaft 12. This generates power in the direction of blood flow in the ventricle, drawing blood out of the ventricle and assisting the heart in pumping blood throughout the body. In other words, the motor transmits torque to the impeller through the flexible transmission shaft 30 and the drive shaft 12. The motor is located outside the patient's body.

[0044] Figure 3 This is a partial axial cross-sectional view of the outer periphery of the flexible drive shaft according to Embodiment 1 of the present invention. For the specific structure of the flexible drive shaft 30, please refer to [reference needed]. Figure 3 The flexible drive shaft 30 includes a single spiral layer or at least two coaxial and stacked spiral layers. The spiral layer is configured to be formed by a single strand of steel wire 31 (stainless steel wire 31) wound in a spiral shape; or, the spiral layer is configured to be formed by at least two strands of steel wire 31 wound in a spiral shape.

[0045] Further reading Figure 1 , Figure 2 and Figure 3The percutaneous ventricular assist device of this embodiment also includes a protective structure 40. The protective structure 40 is disposed on the outer peripheral surface of the flexible drive shaft 30 and completely covers the outer peripheral surface of the flexible drive shaft 30. The coefficient of friction between the protective structure 40 and the outer tube assembly 20 is greater than or equal to 0.04 and less than or equal to 0.20. The outer tube assembly 20 includes a sleeve 22 and a sheath 21 from the inside out. The coefficient of friction between the outer peripheral surface of the protective structure 40 and the inner wall of the sleeve 22 is between 0.04 and 0.20. During the transmission of torsional motion by the flexible drive shaft 30, the flexible drive shaft 30 will inevitably come into contact with the sleeve 22, that is, the flexible shaft cannot always remain at the center position of the sleeve 22 during torsion. When the torsional flexible drive shaft 30 comes into contact with the outer sleeve 22, it will wear down the inner wall of the sleeve 22. Over time, wear debris will accumulate. If the wear debris particles enter the patient's body, they will form a thrombus, endangering the patient's life and health. Furthermore, the perfusion fluid is also unlikely to flush out a large amount of wear debris. The friction coefficient between the protective structure 40 and the sleeve 22 is between 0.04 and 0.20. By controlling the friction coefficient between the protective structure and the sleeve within the above-mentioned preferred range, the frictional resistance is small when the protective structure and the sleeve slide relative to each other, and the amount of wear debris generated after they come into contact is reduced, thus preventing a large amount of wear debris from accumulating and entering the patient's body and endangering the patient's health.

[0046] In one embodiment, the protective structure 40 is configured as a coating, which is applied and molded onto the outer peripheral surface of the flexible drive shaft 30. The coating can be an FEP coating (perfluoroethylene propylene copolymer coating), a PTFE coating (polytetrafluoroethylene coating), or a PEEK coating (polyetheretherketone coating). The thickness of the coating is greater than or equal to 5 micrometers and less than or equal to 10 micrometers. In an alternative embodiment, the protective structure 40 is configured as a heat shrink tubing, which is heat-shrink molded onto the outer peripheral surface of the flexible drive shaft 30. The heat shrink tubing can be an FEP heat shrink tubing (perfluoroethylene propylene copolymer heat shrink tubing), a PTFE heat shrink tubing (polytetrafluoroethylene coated heat shrink tubing), or a PEEK heat shrink tubing (polyetheretherketone heat shrink tubing). The outer tubing assembly 20 includes a sleeve 22 and a sheath 21 from the inside out. The material of the sleeve 22 includes FEP, PTFE, PEEK, or PI. When the material of the protective structure on the surface of the flexible drive shaft 30 is FEP, PTFE or PEEK, and the material of the sleeve 22 is FEP, PTFE, PEEK or PI, the coefficient of friction between the protective structure on the surface of the flexible drive shaft 30 and the sleeve 22 is between 0.04 and 0.20. When the protective structure and the sleeve slide relative to each other, the frictional resistance is small, and the wear debris generated after they come into contact is reduced.

[0047] Specifically, the sleeve 22 can be a single-layer sleeve made of a single material or a multi-layer composite sleeve. The inner layer material of the multi-layer composite sleeve is preferably FEP, PTFE, PEEK, or PI. For example, the sleeve 22 is a three-layer composite sleeve, with an inner layer of PTFE, a middle layer of stainless steel braided layer, and an outer layer of Pebax. The coefficient of friction between the inner layer and the protective structure is between 0.04 and 0.20, resulting in low frictional resistance when the inner layer slides relative to the protective structure, reducing the amount of debris generated after contact. The middle layer of the sleeve is a stainless steel braided layer, which undergoes elastic bending at bends in the implantation path. The radius of curvature of this elastic bending is between 20 and 40 mm, so the cross-section of the sleeve does not deform significantly at bends, keeping the flushing channel unobstructed. The outer layer of the sleeve is Pebax, a biocompatible material that easily adheres to the middle stainless steel braided layer and the inner PTFE tube.

[0048] In a preferred embodiment, the protective structure 40 includes a coating and heat shrink tubing. Specifically, a portion of the outer peripheral surface of the flexible drive shaft 30 is coated, and another portion is covered with heat shrink tubing. Alternatively, the entire outer peripheral surface of the flexible drive shaft 30 may be coated, with heat shrink tubing only used in areas requiring rigidity. In clinical use, different rigidity requirements may exist for different sections of the flexible drive shaft 30. For example, the distal end of the flexible drive shaft 30 requires sufficient rigidity to support the blood pump 10 implanted in the patient; the proximal end requires sufficient rigidity to push the flexible drive shaft 30 into the body; and the bending points along the implantation path of the flexible drive shaft 30 within the patient's body require sufficient flexibility to allow the flexible drive shaft 30 to smoothly navigate bends. Thus, heat shrink tubing can be used at both the distal and proximal ends of the flexible drive shaft 30, while a coating is used in the middle portion. Figure 5 (As shown).

[0049] Further reading Figure 1The sheath 21 and the sleeve 22 have a radial gap, which is configured as an infusion inlet channel 51. The flexible drive shaft 30 and the sleeve 22 also have a radial gap, which is configured as an infusion outlet channel 53. The blood pump 10 has a diversion channel 52, which is disposed inside the housing 11 of the blood pump 10. The infusion inlet channel 51, the diversion channel 52, and the infusion outlet channel 53 are sequentially connected, and the diversion channel 52 is used to divide the perfusion fluid into two paths, allowing one path of perfusion fluid to flow to the infusion outlet channel 53 and the other path of perfusion fluid to flow to the distal end of the blood pump 10. Thus, the perfusion fluid flows in from the perfusion inlet channel 51, and after passing through the diversion channel 52, it is divided into two perfusion fluids. One perfusion fluid flows to the far end of the blood pump 10 to flush the impeller on the drive shaft 12 and prevent blood from clotting on the impeller. The other perfusion fluid flows to the perfusion outlet channel 53 to flush the wear debris generated between the flexible drive shaft 30 and the sleeve 22.

[0050] Figure 5 This is a first schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention. Preferably, see [reference needed]. Figure 5 When the protective structure 40 is configured as a heat shrink tubing, a first corrugation 42 is provided on the outer peripheral surface of the heat shrink tubing 41. The heat shrink tubing 41 and the first corrugation 42 can be integrally manufactured. For example, during the heat shrinking process, a torsional torque is applied to the heat shrink tubing to form thread-like folds (i.e., the first corrugation 42). Alternatively, metal wire is wound around the surface of the flexible drive shaft 30, and then a heat shrinking process is performed. Since metal wire is embedded between the heat shrink tubing and the flexible drive shaft, the surface of the heat shrink tubing is not smooth, forming folds (i.e., the first corrugation 42). The shape of the folds (i.e., the first corrugation 42) depends on the winding path of the metal wire on the surface of the flexible drive shaft.

[0051] Figure 6 and Figure 7 This is a second schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention. In one embodiment, see [reference needed]. Figure 5 , Figure 6 and Figure 7The first corrugation 42 is threaded, and the spiral direction of the first corrugation 42 is the same as the rotation direction of the flexible drive shaft 30. For example, if the rotation direction of the flexible drive shaft 30 is clockwise, then the first thread is spirally wound on the outer circumference of the heat shrink tubing 41 in a clockwise direction. The effect of this arrangement is twofold: Firstly, when the flexible drive shaft 30 rotates, the flow-guiding effect of the first corrugation 42 in the same direction will cause the surrounding injection fluid to rotate accordingly, resulting in smoother fluid flow and a more unobstructed flow channel, which can better flush away the wear debris. Secondly, when the flexible drive shaft 30 transmits a large torque from the motor, the flexible drive shaft 30 has a tendency to unwind (the steel wire 31 also has a tendency to unwind). The heat shrink tubing with the first corrugation 42 has a clamping force on the flexible drive shaft 30, which can effectively resist the unwinding of the flexible drive shaft 30. The threaded first corrugation 42 can have a single thread extending from the proximal end to the distal end of the heat shrink tubing 41. Figure 5 As shown), preferably, the first corrugation 42, which is threaded, has at least two threads. Figure 6 and Figure 7 As shown in the diagram, the more threads there are, the stronger the guiding effect on the injection fluid, thus improving the flow capacity of the injection fluid. At least two threads should have the same helical shape, and at least two threads should be arranged side by side extending from the proximal end to the distal end.

[0052] Figure 8 This is a third schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention. In another embodiment, see [reference needed]. Figure 8 The first corrugation 42 is closed in a ring shape along the circumference of the heat shrink tubing 41, and the heat shrink tubing 41 includes a plurality of annular first corrugations 42 arranged axially. Figure 9 This is a fourth schematic diagram of the first corrugation of the protective structure in Embodiment 1 of the present invention. In optional embodiments, see [reference needed]. Figure 9 The heat shrink tubing 41 includes both annular first corrugations 42 and threaded first corrugations 42.

[0053] The advantage of the first corrugation 42 is that the rotation of the flexible drive shaft 30 allows the first corrugation 42 to scrape the wear debris on the inner circumferential wall of the sleeve 22. Especially at the bend of the flexible drive shaft 30, wear debris is more likely to accumulate in the bend of the flexible drive shaft 30, and the flushing channel becomes narrower. The protruding first corrugation 42, driven by the rotation of the flexible drive shaft 30, can scrape the wear debris like a brush, thus preventing the accumulation of wear debris.

[0054] Preferably, the inner circumferential wall of the sleeve 22 is provided with a protruding second corrugation (not shown, but roughly refer to the threaded first corrugation 42). The second corrugation is threaded, which can also be understood as the inner cavity of the sleeve 22 being threaded. The helical direction of the second corrugation is the same as the helical direction of the threaded first corrugation 42, thereby making the helical direction of the second corrugation, the helical direction of the threaded first corrugation 42, and the rotation direction of the flexible drive shaft 30 all in the same direction. The effect of this arrangement is that, on the one hand, under the guiding effect of the second corrugation in the inner cavity of the sleeve 22, the injection fluid flows more smoothly and can better flush out the wear debris. On the other hand, the flexible drive shaft 30 does not always maintain a straight line when entering the patient's body from outside the body; that is, a portion of the flexible drive shaft 30 is curved. In the curved portion of the flexible drive shaft 30, the surface of the coating / heat shrink tubing inevitably comes into contact with the inner peripheral wall of the sleeve 22. Compared to the case where both the surface of the coating / heat shrink tubing and the inner peripheral wall of the sleeve 22 are flat structures, the thread peaks of the first corrugation 42 and the second corrugation collide, reducing the contact area between the two surfaces and thus reducing the amount of abrasive debris. In some other embodiments, the inner peripheral wall of the sleeve 22 may also be flat, without the second corrugation.

[0055] Preferably, a hydrophobic layer (not shown) is provided on the protective structure 40, and a hydrophobic layer can also be provided on the inner peripheral wall of the sleeve 22. As the injection fluid carries the wear debris out, the amount of wear debris accumulates, which easily deposits on the surface of the flexible drive shaft 30. The design of the hydrophobic layer reduces the accumulation of wear debris, making it easier for the injection fluid to flush out the wear debris more smoothly through the injection outflow channel 53.

[0056]

Example 2

[0057] This embodiment only describes the differences from Embodiment 1. For the same or similar aspects, please refer to the description of Embodiment 1.

[0058] Figure 10 This is an axial cross-sectional view of the percutaneous ventricular assist device according to Embodiment 2 of the present invention. (See also...) Figure 10In this embodiment, the outer tube assembly 20 includes only the sheath 21 and does not include the sleeve 22. The flexible drive shaft 30 is located in the sheath 21. The flexible drive shaft 30 is hollow and tubular. The inner cavity of the flexible drive shaft 30 is configured as an infusion inlet channel 51. The blood pump 10 has a diversion channel 52, that is, a diversion channel 52 is configured inside the outer shell 11 of the blood pump 10. The radial gap between the sheath 21 and the flexible drive shaft 30 is configured as an infusion outlet channel 53. The infusion inlet channel 51, the diversion channel 52 and the infusion outlet channel 53 are connected in sequence. The diversion channel 52 is used to divide the perfusion fluid into two paths, allowing one path of perfusion fluid to flow to the infusion outlet channel 53 and the other path of perfusion fluid to flow to the distal end of the blood pump 10. Thus, the perfusion fluid flows in from the perfusion inlet channel 51 (the inner cavity of the flexible drive shaft 30), and after passing through the diversion channel 52, it is divided into two perfusion fluids. One perfusion fluid flows to the far end of the blood pump 10 to flush the impeller on the drive shaft 12 and prevent blood from clotting on the impeller. The other perfusion fluid flows to the perfusion outlet channel 53 to flush the wear debris generated between the flexible drive shaft 30 and the sheath 21.

[0059] The material of the protective structure 40 on the surface of the flexible drive shaft 30 includes FEP, PTFE or PEEK, and the material of the sheath 21 includes FEP, PTFE, PEEK or PI. The coefficient of friction between the protective structure on the surface of the flexible drive shaft and the sheath is between 0.04 and 0.20. When the protective structure and the sheath slide relative to each other, the frictional resistance is small, and the wear debris generated after the two come into contact is reduced.

[0060] Specifically, the sheath 21 can be a single-layer tube made of a single material or a multi-layer composite tube, wherein the inner layer material of the multi-layer composite tube is preferably FEP, PTFE, PEEK, or PI. For example, the sheath 21 is a three-layer composite tube, with PTFE as the inner layer, a stainless steel braided layer as the middle layer, and Pebax as the outer layer. The coefficient of friction between the inner layer of the sheath 21 and the protective structure is between 0.04 and 0.20, resulting in low frictional resistance when the inner layer slides relative to the protective structure, thus reducing the amount of debris generated after contact. The middle layer of the sheath 21 is a stainless steel braided layer, which undergoes elastic bending at bends in the implantation path. The radius of curvature of this elastic bending is between 20 and 40 mm, so the cross-section of the sheath 21 does not deform significantly at bends, and the flushing channel remains unobstructed. The outer layer of the sheath 21 is Pebax, which is biocompatible and easily adheres to the middle stainless steel braided layer and the inner PTFE tube.

[0061] On the one hand, the design of the perfusion inflow channel 51 and perfusion outflow channel 53 in this embodiment, compared with the first embodiment, eliminates the need for the cannula 22, which further reduces the radial dimension of the entire percutaneous ventricular assist device, facilitating implantation into the patient's blood vessels. On the other hand, the inner cavity of the flexible drive shaft 30 and the gap between the flexible drive shaft 30 and the sheath 21 are filled with perfusion fluid, which allows the perfusion fluid to act as a vibration buffer for the high-speed rotating flexible drive shaft 30, thus helping to isolate vibration and reduce noise.

[0062] Furthermore, regarding the specific structure of the flexible drive shaft 30, the flexible drive shaft 30 includes a single spiral layer or at least two coaxially stacked spiral layers. The spiral layer is configured as a single strand of steel wire 31 (stainless steel wire 31) wound in a spiral shape; or, the spiral layer is configured as at least two strands of steel wire 31 wound in a spiral shape. A sealing tube (not shown) is provided between the flexible drive shaft 30 and the protective structure 40 to prevent the injection fluid from seeping out of the inner cavity of the flexible drive shaft 30 to the surrounding area. It should be noted that heat shrink tubing can play a sealing role, and a sufficiently dense coating can also play a sealing role. In this embodiment, the flexible drive shaft 30 formed by the spiral winding of steel wire 31 can be sealed by heat shrink tubing or coating, so it is not necessary to use an additional sealing tube.

[0063] While the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the content of the present invention, shall still fall within the scope of protection of the present invention.

Claims

1. A percutaneous ventricular assist device, characterized in that, include: Blood pump; An outer tubing assembly, which is connected to the blood pump; A flexible drive shaft is housed in the outer tube assembly, the distal end of the flexible drive shaft is connected to the blood pump, and the proximal end of the flexible drive shaft is used for connecting an external motor. A protective structure is provided on the outer circumferential surface of the flexible transmission shaft, and the coefficient of friction between the protective structure and the outer tube assembly is between 0.04 and 0.

20. The protective structure includes a heat shrink tubing, which is heat-shrinkable and formed on the outer peripheral surface of the flexible drive shaft. The outer tube assembly includes a sheath and a sleeve, the sleeve being housed in the sheath, the flexible drive shaft being housed in the sleeve, the radial gap between the sheath and the sleeve being configured as an infusion inflow channel, and the radial gap between the flexible drive shaft and the sleeve being configured as an infusion outflow channel. The heat shrink tubing has a first corrugation on its outer circumferential surface. The heat shrink tubing includes a threaded first corrugation and a plurality of annular first corrugations arranged axially. The spiral direction of the threaded first corrugation is the same as the rotation direction of the flexible drive shaft. The inner circumferential wall of the tubing has a protruding second corrugation, and the spiral direction of the second corrugation is the same as the spiral direction of the threaded first corrugation.

2. The percutaneous ventricular assist device according to claim 1, characterized in that, The protective structure includes a coating; the coating is applied and formed on the outer peripheral surface of the flexible drive shaft.

3. The percutaneous ventricular assist device according to claim 2, characterized in that, The thickness of the coating is between 5 micrometers and 10 micrometers.

4. The percutaneous ventricular assist device according to claim 1, characterized in that, The protective structure is made of materials including FEP, PTFE, or PEEK.

5. The percutaneous ventricular assist device according to claim 1, characterized in that, The blood pump has a diversion channel, wherein the infusion inflow channel, the diversion channel, and the infusion outflow channel are connected in sequence. The diversion channel is used to split the infusion fluid into two paths, allowing one path of the infusion fluid to flow to the infusion outflow channel and the other path of the infusion fluid to flow to the distal end of the blood pump.

6. The percutaneous ventricular assist device according to claim 5, characterized in that, The sleeve is made of FEP, PTFE, PEEK or PI.

7. The percutaneous ventricular assist device according to claim 1, characterized in that, The sheath material includes FEP, PTFE, PEEK, or PI.

8. The percutaneous ventricular assist device according to claim 1, characterized in that, A sealing tube is provided between the flexible drive shaft and the protective structure.

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