Flexible transmission structure and percutaneous intervention type foldable blood pump thereof

Abstract

According to the flexible transmission structure capable of reducing friction and vibration and the percutaneous intervention type foldable blood pump thereof, the ball bearings are arranged in the axial direction of the flexible driving shaft at intervals to support the flexible driving shaft, it is guaranteed that the flexible driving shaft is located in the middle, and in the high-speed rotation process of the flexible driving shaft, the friction and vibration of the flexible driving shaft are reduced. Friction between the flexible driving shaft and the inner wall of the sleeve is avoided, on one hand, kinetic energy loss of the motor is reduced, transmission efficiency is high, on the other hand, friction is reduced, heat generated by friction is greatly reduced, the phenomena of thinning and high-heat deformation of the sleeve due to friction are avoided, the problems of hemolysis and thrombus are relieved, and therefore normal work of the blood pump is guaranteed. Meanwhile, the hard friction between the flexible driving shaft and the sleeve is reduced, the stability of power transmission is facilitated, the jerk value of the foldable impeller located at the far end of the flexible driving shaft is small, on one hand, blood can be stably pumped, on the other hand, damage to the blood is small, and operation safety is guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of medical equipment, in particular to a flexible transmission structure and a percutaneous interventional foldable blood pump thereof. Background Art

[0002] In the field of interventional cardiac blood pumps, the current mainstream products use a built-in motor working mode, but this mode is prone to the following risks: heating problems, intervention size problems, and the risk of motor damage after contact with the transcatheter aortic valve replacement stent in certain operations. Therefore, a percutaneous interventional foldable blood pump came into being. Its working principle is to enter the heart through the femoral artery intervention of the delivery system. After reaching the left ventricle, the foldable impeller at the head end is unfolded and fixed to the aortic valve. The motor located outside the body transmits power to the impeller located in the left ventricle through a flexible drive shaft to achieve blood pumping. However, since the length of the flexible drive shaft is more than 1m, there are at least the following two problems: First, the friction between the flexible drive shaft and the outer sleeve causes the loss of motor kinetic energy and low transmission efficiency. On the other hand, the friction generates large heat and the temperature rises. When the high-temperature part contacts the blood, it will destroy the blood cells, causing hemolysis and thrombosis problems, thereby affecting the normal operation of the blood pump. Second, the rotation speed of the flexible drive shaft is high, and the hard friction with the sleeve is easy to cause the transmission device to vibrate, affecting the safety of the operation. At the same time, the flexible drive shaft and its outer sheath need to enter the heart through the femoral artery along the winding blood vessels. Therefore, the trajectory of the entire flexible drive shaft is a curved shape that matches the physiological structure of the blood vessels, making the above two problems more obvious. It is urgent to find a flexible driving method that can reduce friction and vibration. Utility Model Content

[0003] One of the purposes of the utility model is to provide a flexible transmission structure which reduces friction and vibration.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a flexible transmission structure, including a flexible driving shaft and an external sleeve, the sleeve is a segmented structure, including a plurality of sleeve units and a supporting unit for connecting adjacent sleeve units, the supporting unit includes an outer tube and a ball bearing coaxially arranged in the inner cavity of the outer tube, the sleeve unit is inserted into the outer tube to form a fixed connection, the flexible driving shaft and the ball bearing form a supporting rotation fit, and the flexible driving shaft and the inner wall of the sleeve unit form a clearance fit.

[0005] Two retaining rings are arranged in the middle of the inner cavity of the outer tube, and the annular groove of the chamber between the two retaining rings constitutes an area for accommodating ball bearings. The connecting section of the sleeve unit is inserted into the outer tube and the end is abutted against the retaining ring. Adhesive is injected into the gap between the outer wall of the sleeve unit and the inner wall of the outer tube to form a fixed connection.

[0006] The connecting section is a variable diameter pipe section, whose diameter gradually increases toward the free end. The two sections of the outer wall of the outer tube are arc-shaped structures with gradually decreasing outer diameters, and the outer tube and the connecting section are smoothly transitioned through adhesive.

[0007] The support unit is arranged every 10 cm to 30 cm along the length direction of the sleeve, and the length of the support unit is 5 mm to 15 mm, the maximum outer diameter is 2 mm to 2.8 mm, the axial width of the ball bearing is 1 mm to 2 mm, the outer diameter is 1.8 mm to 2.3 mm, and the outer diameter of the sleeve unit is 1.8 mm to 2.3 mm.

[0008] The outer tube is made of TPU or silicone material, and the ball bearing is pre-embedded and integrally injection-molded with the outer tube. The ball bearing comprises an outer ring and an inner ring. An annular groove is provided on the outer wall of the inner ring, and the ball is embedded in the annular groove. The groove depth of the annular groove is smaller than the diameter of the ball and larger than the radius of the ball, and the inner diameter of the retaining ring is larger than the outer diameter of the inner ring.

[0009] The casing includes an outer layer, a middle layer and an inner lining layer, wherein the outer layer is made of PEBA material, the middle layer is woven from alloy wire, and the inner lining layer is made of PTFE material.

[0010] The flexible drive shaft has a double-layer hollow structure wound with alloy wires and an outer diameter of 0.9mm to 1.2mm, wherein the outer layer is wound with 4 to 6 alloy wires with an outer diameter of 0.16mm, and the inner layer is wound with 8 to 14 alloy wires with an outer diameter of 0.09mm.

[0011] Another object of the utility model is to provide a percutaneous interventional foldable blood pump which reduces friction and vibration.

[0012] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a percutaneous interventional foldable blood pump, the proximal end of the cannula is connected to the external handle, and the distal end is connected to the pumping assembly, the pumping assembly includes a foldable impeller and an expandable shell covering the outer periphery of the foldable impeller, the expandable shell is provided with a coating, the coating extends from the distal end of the expandable shell to the proximal end to the cannula, the inner cavity of the coating constitutes a blood cavity, and a blood outflow outlet is provided at the proximal end of the coating.

[0013] The foldable impeller includes a hard hub and its circumferential blades. The hard hub is in the shape of a hollow tube. The flexible drive shaft passes through the hollow tube and rotates synchronously. The two ends of the expandable shell are supported and matched with the flexible drive shaft through a proximal bearing and a distal bearing respectively. The proximal bearing includes a bearing sleeve and a bearing ring. The outer wall of the bearing sleeve is welded and fixed to the proximal end of the expandable shell. A limit card is provided at the proximal end of the bearing sleeve to limit the displacement of the flexible drive shaft in the proximal direction. The distal bearing includes a bearing sleeve and a bearing ring. Limit cards are provided at both ends of the bearing sleeve to limit the axial movement of the bearing ring.

[0014] An outer sleeve is sleeved on the flexible driving shaft at positions corresponding to the proximal bearing and the distal bearing. A boss is arranged at the proximal end of the outer sleeve. The boss abuts against the limit card of the bearing sleeve to form a limit fit.

[0015] In the above scheme, ball bearings are arranged at intervals in the axial direction of the flexible drive shaft to support it, so as to ensure that the position of the flexible drive shaft is centered. During the high-speed rotation of the flexible drive shaft, the friction between the flexible drive shaft and the inner wall of the outer casing is reduced and eliminated. On the one hand, the kinetic energy loss of the motor is reduced, and the transmission efficiency is high. On the other hand, the friction is reduced, and the heat generated by friction will be greatly reduced, and the hemolysis and thrombosis problems are alleviated, thereby ensuring the normal operation of the blood pump. At the same time, the hard friction between the flexible drive shaft and the casing is reduced, which is also conducive to the stability of power transmission. The foldable impeller at the far end of the flexible drive shaft has a small amount of beating, which can stably pump blood on the one hand, and cause less damage to the blood on the other hand, ensuring the safety of the operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the blood pump;

[0017] Figure 2 for Figure 1 A partially enlarged schematic diagram of

[0018] Figure 3 for Figure 2 A cross-sectional view of

[0019] Figure 4 is the outline drawing of the support unit;

[0020] Figure 5 for Figure 4 A cross-sectional view of

[0021] Figure 6 A partial structural diagram of the pumping unit. DETAILED DESCRIPTION

[0022] For ease of understanding, we first define the directions involved in the following text: "proximal" and "proximal side" refer to the side close to the operator / doctor, and "distal" and "distal side" refer to the side away from the operator / doctor, that is, the side close to the heart. Figure 1-Figure 6 The utility model is further discussed in detail.

[0023] Since the flexible drive shaft of the foldable blood pump needs to pass through the blood vessels in the bay area to enter the heart, the length of the flexible drive shaft is more than 1m and the diameter is extremely thin. While considering the friction problem of the flexible drive shaft, the assembly problem of the flexible drive shaft and the curvature of the interventional path cannot be ignored, which makes the design more difficult.

[0024] like Figure 1-Figure 6 As shown, a flexible transmission structure includes a flexible drive shaft 10 and an external sleeve 20. The sleeve 20 is a segmented structure, including a plurality of sleeve units 21 and a support unit 30 for connecting adjacent sleeve units 21. The support unit 30 includes an outer tube 31 and a ball bearing 32 coaxially arranged in the inner cavity of the outer tube 31. The sleeve unit 21 is inserted into the outer tube 31 to form a fixed connection. The flexible drive shaft 10 and the ball bearing 32 form a supporting rotation fit, and the flexible drive shaft 10 and the inner wall of the sleeve unit 21 form a gap fit. The ball bearings 32 are arranged at intervals in the axial direction of the flexible drive shaft 10 to support it, so as to ensure that the position of the flexible drive shaft 10 is centered. During the high-speed rotation of the flexible drive shaft 10, the friction between the flexible drive shaft 10 and the inner wall of the outer sleeve 20 is reduced and eliminated. On the one hand, the kinetic energy loss of the motor is reduced, and the transmission efficiency is high. On the other hand, the friction is reduced, and the heat generated by the friction is greatly reduced, and the hemolysis and thrombosis problems are alleviated, thereby ensuring the normal operation of the blood pump. At the same time, the hard friction between the flexible drive shaft 10 and the sleeve 20 is reduced, which is also beneficial to the stability of power transmission. The foldable impeller 41 located at the far end of the flexible drive shaft 10 has a small amount of vibration. On the one hand, it can pump blood stably, and on the other hand, it causes less damage to the blood, ensuring the safety of the operation.

[0025] Since the length of the sleeve 20 and the flexible drive shaft 10 is greater than 1m, and the outer diameter of the sleeve 20 is very small, about 3mm to 4mm, the arrangement and installation of the ball bearing 32 is also a big problem. In the utility model, the sleeve 20 is arranged as a segmented structure, including an outer tube 31 and a ball bearing 32 in the inner cavity. After the cast bearing 32 and the outer tube 31 are assembled into a whole in advance, they are assembled with the flexible drive shaft 10 and the sleeve unit 21, so that the assembly of the flexible drive shaft with the sleeve unit 21 and the ball bearing 32 in the support unit 30 can be easily realized.

[0026] Two adjacent sleeve units 21 are connected by a supporting unit 30. The outer tube 31 of the supporting unit 30 is used to connect the two sleeve units 21. Two retaining rings 311 are arranged in the middle of the inner cavity of the outer tube 31. The annular groove of the chamber between the two retaining rings 311 constitutes an area for accommodating the ball bearing 32. The connecting section 211 of the sleeve unit 21 is inserted into the outer tube 31 and the end thereof abuts against the retaining ring 311. Adhesive is injected into the gap between the outer wall of the sleeve unit 21 and the inner wall of the outer tube 31 to form a fixed connection. The setting of the two retaining rings 311, on the one hand, provides space for the installation of the ball bearing 32, and on the other hand, the end face of the retaining ring 311 also constitutes the limiting part of the connecting section 211. When the end face of the connecting section 211 abuts against the end face of the retaining ring 311, it means that the installation is in place. At this time, bonding is performed to ensure that the contact area between the two is large and the connection reliability is good. On the other hand, as a Class III medical device, the blood pump has high requirements on the accuracy of its size. Therefore, it must also be assembled in place. Marks will be set on the sleeve 20 to help doctors judge the intervention position of the blood pump. Therefore, the installation of the gym unit 21 and the support unit 30 must be in place to ensure the accuracy of the size of the sleeve 20.

[0027] The assembly process of the flexible transmission structure is as follows: first, the flexible drive shaft 10 passes through a sleeve unit 21, and then passes through the center of the ball bearing 32 of the support unit 30 to connect the sleeve unit 21 and the support unit 30; then, the flexible drive shaft 10 passes through the next sleeve unit 21 to connect the sleeve unit 21 and the support unit 30. This order of installation can avoid the problem that the flexible drive shaft 10 cannot be aligned with the center of the ball bearing 32 and affects smooth passing.

[0028] The connecting section 211 is a variable diameter pipe section, so as to reduce the connection gap between the connecting section 211 and the outer tube 31 of the supporting unit 30, which is conducive to bonding and fixing. The diameter of the connecting section 211 is gradually enlarged toward the free end, and the two sections of the outer wall of the outer tube 31 are arc-shaped structures with gradually decreasing outer diameters, and the outer tube 31 and the connecting section 211 are smoothly transitioned through the adhesive. Due to the presence of the adhesive, the connection between the outer tube 31 and the connecting section 211 is arc-shaped. In this way, although the outer surface of the entire sleeve 20 is not of equal diameter, each connection is smooth. On the one hand, it effectively prevents the sleeve 20 from damaging the blood vessels and other tissues during the intervention and removal process, and on the other hand, it also reduces the formation of thrombus, ensuring the smooth progress of the operation.

[0029] In order to realize the centering of the flexible drive shaft 10, the support unit 30 is arranged every 10 cm to 30 cm along the length direction of the sleeve 20, and the length of the support unit 30 is 5 mm to 15 mm, the maximum outer diameter is 2 mm to 2.8 mm, the axial width of the ball bearing 32 is 1 mm to 2 mm, the outer diameter is 1.8 mm to 2.3 mm, and the outer diameter of the sleeve unit 21 is 1.8 mm to 2.3 mm. It can be seen from the above data that the axial width of the ball bearing 32 is very small, and while supporting the flexible drive shaft 10 to ensure its centering, it does not affect the bending performance of the flexible drive shaft 10 at all; and the length of the support unit is 5 mm to 15 mm, which is also very small, and has a certain deformation capacity, so it will not affect the bending performance of the entire flexible transmission structure.

[0030] Since the blood vessels of the human body are tortuous, and the blood pump is inserted from the blood vessels into the heart, the bending performance requirements of the sleeve 20 and the flexible drive shaft 10 are relatively high. The outer tube 31 is made of TPU or silicone material and has a certain flexibility. The ball bearing 32 is pre-embedded and integrally injection-molded with the outer tube 31, which is assembly-free, has high precision and strong connection reliability. The ball bearing 32 includes an outer ring 321 and an inner ring 322. An annular groove 323 is provided on the outer wall of the inner ring 322. The ball 324 is embedded in the annular groove 323. The groove depth of the annular groove 323 is less than the diameter of the ball 324 and greater than the radius of the ball 324. The inner diameter of the retaining ring 311 is greater than the outer diameter of the inner ring 322. This structural form can ensure the reliability of the position of the ball bearing 32 without affecting the basic performance of the ball bearing 32.

[0031] Furthermore, the sleeve 20 includes an outer layer, an intermediate layer and an inner lining layer, wherein the outer layer is made of PEBA material, which is flexible and has good biocompatibility; the intermediate layer is woven of alloy wire, which supports the sleeve 20 and ensures the roundness; the inner lining layer is made of PTFE material to reduce possible friction. Ensuring the roundness of the sleeve 20 can reduce the probability of contact and friction between the flexible drive shaft 10 and the inner wall of the sleeve 20, and reducing the friction of the inner layer can reduce the friction when the flexible drive shaft 10 contacts and rubs against the inner wall of the sleeve 20. The two aspects complement each other, further reducing the hard friction of the flexible drive shaft 10 and improving the transmission efficiency of power.

[0032] Furthermore, the flexible drive shaft 10 has a double-layer hollow structure wound with alloy wires and has an outer diameter of 0.9mm to 1.2mm, wherein the outer layer is wound with 4 to 6 alloy wires with an outer diameter of 0.16mm, and the inner layer is wound with 8 to 14 alloy wires with an outer diameter of 0.09mm. The entire flexible drive shaft 10 has a spiral structure.

[0033] A percutaneous interventional foldable blood pump, the proximal end of the cannula 20 is connected to an external handle 50, and the distal end is connected to a pumping assembly 40, a motor and a flushing system are arranged in the external handle 50, wherein the motor provides power to drive the foldable impeller 41 to rotate through the flexible drive shaft 10, and the function of the flushing system is: the flexible drive shaft 10 may rub against the inner wall of the cannula 20 to produce debris when rotating at high speed, and heat will also be generated during the friction process, so the flushing fluid of the flushing system can take away these debris and heat in time, thereby ensuring the normal operation of the blood pump. Although the friction between the flexible drive shaft 10 and the inner wall of the cannula 20 can be reduced in the utility model, the friction cannot be eliminated, and the rotation between the flexible drive shaft 10 and the ball bearing 32 will also generate some heat, so it is better to set up a flushing system to dissipate the heat in time, since almost no debris is generated, no debris enters the blood, thereby improving the safety of the operation. The pumping assembly 40 includes a foldable impeller 41 and an expandable shell 42 covered on the periphery of the foldable impeller 41. The expandable shell 42 is made of nickel-titanium alloy and is formed by shaping and cutting a nickel-titanium tube. The cutting hole is rhombus-shaped. The superelastic properties of the nickel-titanium alloy are utilized. The cut expandable shell 42 is compressed by the sheath tube and enters the left ventricle of the heart. After the sheath tube is removed, the outer diameter is restored to its original size. The inner layer of the cylindrical region in the middle of the expandable shell 42 is coated as the outer cover of the blood pump. The membrane material is TPU and is heat-welded to the expandable shell 42. A coating 43 is provided on the expandable shell 42. The coating 43 extends from the distal end of the expandable shell 42 to the proximal end to the sleeve 20. The inner cavity of the coating 43 constitutes a blood cavity. A blood outflow outlet 431 is provided at the proximal end of the coating 43. Since the coating 43 also has the characteristics of being expanded and contracted, it can ensure that the blood channel is formed while being able to expand or contract synchronously with the expandable shell 42, and the proximal end of the coating 43 extends to the aorta. The motor drives the foldable impeller 41 to rotate to generate suction, and the blood enters the blood flow channel formed by the coating 43 from the blood inlet at the proximal end of the expandable shell 42, and then ejects from the blood outlet 431 at the proximal end of the coating 43 into the aorta, completing the blood pumping. At the same time, due to the softness of the coating 43, when it crosses the aortic valve, it will not cause damage to the aortic valve, thereby improving the patient's postoperative recovery ability.

[0034] The foldable impeller 41 includes a hard hub 411 and circumferential blades 412. In one embodiment, the foldable impeller 41 is injection molded with TPU material. The TPU material used is of medical intervention grade, and the hardness range is between 60D and 80D. It is selected according to the thickness of the designed blade 412. Of course, there can be other structural forms that can achieve folding. The hard hub 411 is in the shape of a hollow tube. The flexible drive shaft 10 passes through the hollow tube and rotates synchronously. The two ends of the expandable shell 42 are respectively supported and matched with the flexible drive shaft 10 through the proximal bearing 44 and the distal bearing 45. As an embodiment, the proximal bearing 44 includes a bearing sleeve and a bearing ring (not shown in the figure). The outer wall of the bearing sleeve is welded and fixed to the proximal end of the expandable shell 42. A limit card is set at the proximal end of the bearing sleeve to limit the displacement of the flexible drive shaft 10 in the proximal direction. The distal bearing 45 includes a bearing sleeve and a bearing ring. Limit cards are set at both ends of the bearing sleeve to limit the axial movement of the bearing ring. When the expandable shell 42 is folded, its axial length will become longer, and when the expandable shell 42 is expanded, its axial length will become shorter. In order to adapt to this function, one end of the expandable shell 41 is fixedly connected to the flexible drive shaft 10, and the other end forms a sliding fit with the flexible drive shaft 10. Since the distal bearing 45 is also connected to the pigtail tube, the distal bearing 45 is selected to be fixedly connected to the flexible drive shaft 10, which is achieved by arranging limit clamps at both ends of the bearing sleeve; the proximal bearing 44 and the flexible drive shaft 10 form a circumferential rotation and axial sliding fit.

[0035] In order to further reduce friction, an outer sleeve (not shown) is sleeved on the flexible drive shaft 10 at the positions corresponding to the proximal bearing 44 and the distal bearing 45. A boss (not shown) is arranged at the proximal end of the outer sleeve, and the boss abuts against the limit card of the bearing sleeve to form a limit fit. The limit card is used to limit the excessive movement of the flexible drive shaft in the proximal direction, and also facilitates the operation when the sheath is used to gather the expandable shell.

[0036] Of course, for those skilled in the art, the present invention is not limited to the details of the exemplary embodiments described above, but also includes the same or similar structures that can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, so it is intended to include all changes that fall within the meaning and scope of the equivalent elements of the claims. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0037] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A flexible transmission structure, comprising a flexible drive shaft (10) and an external sleeve (20), characterized in that: The sleeve (20) is a segmented structure, comprising a plurality of sleeve units (21) and a support unit (30) for connecting adjacent sleeve units (21); the support unit (30) comprises an outer tube (31) and a ball bearing (32) coaxially arranged in an inner cavity of the outer tube (31); the sleeve unit (21) is inserted into the outer tube (31) to form a fixed connection; the flexible drive shaft (10) and the ball bearing (32) form a supporting rotation fit; and the flexible drive shaft (10) and the inner wall of the sleeve unit (21) form a clearance fit.

2. A flexible transmission structure according to claim 1, characterized in that: Two retaining rings (311) are arranged in the middle of the inner cavity of the outer tube (31); an annular groove in the cavity between the two retaining rings (311) constitutes an area for accommodating a ball bearing (32); a connecting section (211) of the sleeve unit (21) is inserted into the outer tube (31) and an end thereof abuts against the retaining ring (311); and an adhesive is injected into the gap between the outer wall of the sleeve unit (21) and the inner wall of the outer tube (31) to form a fixed connection.

3. A flexible transmission structure according to claim 2, characterized in that: The connecting section (211) is a variable diameter pipe section, the diameter of which gradually increases towards the free end, the two sections of the outer wall of the outer tube (31) are arc-shaped structures with gradually decreasing outer diameters, and the outer tube (31) and the connecting section (211) are smoothly transitioned by adhesive.

4. A flexible transmission structure according to claim 1, characterized in that: The support units (30) are arranged at intervals of 10 cm to 30 cm along the length direction of the sleeve (20), and the length of the support units (30) is 5 mm to 15 mm, and the maximum outer diameter is 2.0 mm to 2.8 mm. The axial width of the ball bearing (32) is 1 mm to 2 mm, and the outer diameter is 1.8 mm to 2.3 mm. The outer diameter of the sleeve unit (21) is 1.6 mm to 2.2 mm.

5. A flexible transmission structure according to claim 2, characterized in that: The outer tube (31) is made of TPU or silicone material, and the ball bearing (32) is pre-embedded and integrally injection-molded with the outer tube (31). The ball bearing (32) comprises an outer ring (321) and an inner ring (322). An annular groove (323) is provided on the outer wall of the inner ring (322), and the ball (324) is embedded in the annular groove (323). The groove depth of the annular groove (323) is smaller than the diameter of the ball (324) and larger than the radius of the ball (324). The inner diameter of the retaining ring (311) is larger than the outer diameter of the inner ring (322).

6. A flexible transmission structure according to claim 1, characterized in that: The sleeve (20) comprises an outer layer, an intermediate layer and an inner lining layer, wherein the outer layer is made of PEBA material, the intermediate layer is woven from alloy wires, and the inner lining layer is made of PTFE material.

7. A flexible transmission structure according to claim 1, characterized in that: The flexible drive shaft (10) is a double-layer hollow structure made of alloy wires with an outer diameter of 0.9 mm to 1.2 mm, wherein the outer layer is made of 4 to 6 alloy wires with an outer diameter of 0.16 mm, and the inner layer is made of 8 to 14 alloy wires with an outer diameter of 0.09 mm.

8. A percutaneous interventional foldable blood pump, comprising the flexible transmission structure according to any one of claims 1 to 7, characterized in that: The proximal end of the sleeve (20) is connected to the external handle (50), and the distal end is connected to the pumping assembly (40). The pumping assembly (40) includes a foldable impeller (41) and an expandable shell (42) covered on the periphery of the foldable impeller (41). The expandable shell (42) is provided with a coating (43). The coating (43) extends from the distal end of the expandable shell (42) to the proximal end to the sleeve (20). The inner cavity of the coating (43) constitutes a blood cavity. The proximal end of the coating (43) is provided with a blood outflow outlet (431).

9. The percutaneous interventional foldable blood pump according to claim 8, characterized in that: The foldable impeller (41) comprises a hard hub (411) and circumferential blades (412), the hard hub (411) being in the shape of a hollow tube, the flexible drive shaft (10) passing through the hollow tube and rotating synchronously, the two ends of the expandable shell (42) respectively forming a support fit with the flexible drive shaft (10) through a proximal bearing (44) and a distal bearing (45), wherein the proximal bearing (44) comprises a bearing sleeve and a bearing ring, the outer wall of the bearing sleeve is welded and fixed to the proximal end of the expandable shell (42), a limit card is arranged at the proximal end of the bearing sleeve to limit the displacement of the flexible drive shaft (10) in the proximal direction, the distal bearing (45) comprises a bearing sleeve and a bearing ring, and limit cards are arranged at both ends of the bearing sleeve to limit the axial movement of the bearing ring.

10. The percutaneous interventional foldable blood pump according to claim 9, characterized in that: An outer sleeve is sleeved on the flexible drive shaft (10) at positions corresponding to the proximal bearing (44) and the distal bearing (45), and a boss is provided at the proximal end of the outer sleeve. The boss abuts against a limit clamp of the bearing sleeve to form a limit fit.

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