blood pump

Abstract

This application relates to a blood pump. The blood pump includes a pump housing and an impeller; the pump housing has a proximal opening; the impeller is rotatably disposed within the pump housing. The pump housing includes an expansion tube housing the impeller, the expansion tube comprising a first shape memory material to give the expansion tube an initial shape and an expanded shape relative to its initial shape; the first shape memory material is capable of deforming under blood temperature conditions, causing the expansion tube to expand from its initial shape to its expanded shape. The blood pump of this application can reduce hemolysis and improve the safety performance of the blood pump.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a blood pump. BACKGROUND

[0002] Blood pumps are often used to push blood from blood vessels to the heart of a patient to assist the heart of the patient to pump blood from the heart chamber to the artery, so as to provide support for the blood circulation of the patient. The blood pump has an impeller, and driving the impeller to rotate can drive the blood flow. When the blood pump is working, hemolysis problem is more likely to occur in the process of blood flowing through the impeller, which causes some safety hazards of the blood pump. SUMMARY

[0003] Therefore, it is necessary to provide a blood pump, which aims to reduce hemolysis and improve the safety performance of the blood pump.

[0004] An embodiment of the blood pump provided by the present application comprises a pump shell and an impeller. The pump shell is provided with a proximal opening. The impeller is rotatably arranged in the pump shell. The pump shell comprises an expansion pipe for accommodating the impeller. The expansion pipe comprises a first shape memory material, so that the expansion pipe has an initial shape and an expanded shape relative to the initial shape. The first shape memory material can deform under the temperature condition of blood, so that the expansion pipe expands from the initial shape to the expanded shape.

[0005] In some embodiments, the expansion pipe further has at least one of the following characteristics:

[0006] The first shape memory material is a shape memory metal;

[0007] The temperature at which the first shape memory material deforms is 34℃-39℃;

[0008] The shape of the expansion pipe in the initial shape is a circular tube shape;

[0009] The expansion pipe in the initial shape does not need external force to maintain;

[0010] The expansion pipe in the expanded shape can be accommodated in the aorta;

[0011] The maximum outer diameter of the expansion pipe in the expanded shape allows the expansion pipe to pass through the narrowest position on the in-vivo pushing path.

[0012] In some embodiments, the impeller comprises a second shape memory material, so that the impeller also has an initial shape and an expanded shape relative to the initial shape. The second shape memory material can deform under the temperature condition of blood, so that the impeller expands from the initial shape to the expanded shape.

[0013] In some embodiments, the impeller further has at least one of the following features:

[0014] The second shape memory material is a shape memory metal.

[0015] The second shape memory material deforms at a temperature of 34-39℃.

[0016] The impeller is maintained in the initial shape without external force.

[0017] In some embodiments, the inner diameter of the expansion tube in the initial shape is a contracted inner diameter D 1a , the diameter of the impeller in the initial shape is an initial diameter D 5a , and the diameter of the impeller in the expanded shape is a working diameter D 5b , wherein D 5b >D 5a , and D 5b ≥D 1a .

[0018] In some embodiments, the diameter of the impeller in the expanded shape is a working diameter D 5b ; the pump housing further comprises a proximal tube connected to the proximal end of the expansion tube and provided with the proximal opening, the proximal tube being a non-deformable structure, the working diameter D 5b being greater than the inner diameter of the proximal tube; and / or,

[0019] The pump housing further comprises a distal tube connected to the distal end of the expansion tube, the distal tube being a non-deformable structure, the working diameter D 5b being greater than the inner diameter of the distal tube.

[0020] In some embodiments, the impeller is a non-deployable rigid impeller; the radial gap between the inner wall surface of the expansion tube and the impeller in the initial shape of the expansion tube is 0-0.06mm or 0.08-2mm in width.

[0021] In some embodiments, the radial gap between the inner wall surface of the expansion tube and the impeller in the expanded shape of the expansion tube is 0.1-0.3mm in width.

[0022] In some embodiments, the expansion tube is provided with a deformation hole extending along the axial direction of the pump housing, and a flexible membrane covering the deformation hole is arranged in the deformation hole; when the expansion tube recovers from the initial shape to the expanded shape, the flexible membrane can be stretched or unfolded along the circumferential direction of the pump housing.

[0023] In some embodiments, the expansion tube is provided with a plurality of deformation holes, and the plurality of deformation holes are arranged in a circumferential direction of the pump shell.

[0024] In some embodiments, the deformation hole has a first width extending in a circumferential direction of the pump shell, the deformation lobe has a second width extending in the circumferential direction of the pump shell, and the second width is greater than the first width when the expansion tube is in the initial state; and / or, the outer diameter of the expansion tube in the initial state is a contracted outer diameter D 2a , and W≥0.25πD 2a .

[0025] In some embodiments, the expansion tube further has at least one of the following features:

[0026] The number of deformation lobes is 2-5;

[0027] The flexible membrane is fixedly connected to the periphery of the deformation hole;

[0028] The flexible membrane is folded in the deformation hole when the expansion tube is in the initial state.

[0029] In some embodiments, the impeller includes a hub and blades arranged on the hub, and the blades are located in the expansion tube; wherein,

[0030] The deformation hole has a first length extending in an axial direction of the pump shell, the blade has a second length extending in the axial direction of the pump shell, the first length is greater than the second length, and the two ends of the deformation hole extend beyond the two ends of the blade;

[0031] And / or, the blade is completely accommodated in the expansion tube, and the proximal end of the blade and the proximal end of the expansion tube are spaced apart in the axial direction of the pump shell by a first distance, and the distal end of the blade and the distal end of the expansion tube are spaced apart in the axial direction of the pump shell by a second distance.

[0032] In some embodiments, the expansion tube includes a first tube segment, a second tube segment, and a main tube segment connected between the first tube segment and the second tube segment; the diameter of the first tube segment gradually decreases in a direction from the distal end to the proximal end of the pump shell when the expansion tube is in the expanded state; and the diameter of the second tube segment gradually decreases in a direction from the proximal end to the distal end of the pump shell.

[0033] In some embodiments, the blood pump further includes a drive unit, the drive unit includes a housing and a rotating shaft connected to the impeller; the pump shell further includes a proximal tube connected to the proximal end of the expansion tube, the proximal tube is fixedly connected to the housing, and the proximal tube is provided with the proximal opening.

[0034] In some embodiments, the pump housing also has at least one of the following features:

[0035] The proximal tube is a non-deformable structure;

[0036] The proximal tube and the expansion tube are an integral structure;

[0037] The outer diameter of the expansion tube in its initial state is the contracted outer diameter D. 2a The contracted outer diameter D 2a The same as the outer diameter of the proximal tube;

[0038] The outer diameter of the expansion tube when it is in the expansion state is the expansion outer diameter D. 2b The expanded outer diameter D 2b The ratio of the outer diameter of the proximal tube to the outer diameter of the tube is 1.1 to 1.5.

[0039] In some embodiments, the pump housing further includes a cannulation assembly having a blood flow channel; the pump housing also includes a distal tube connected to the distal end of the expansion tube, the distal tube being fixed to the proximal end of the cannulation assembly.

[0040] In some embodiments, the pump housing also has at least one of the following features:

[0041] The distal tube is a non-deformable structure;

[0042] The distal tube and the expansion tube are an integral structure;

[0043] The outer diameter of the expansion tube in its initial state is the contracted outer diameter D. 2a The contracted outer diameter D 2a The outer diameter D7 of the distal tube is the same;

[0044] The outer diameter of the expansion tube when it is in the expansion state is the expansion outer diameter D. 2b The expanded outer diameter D 2b The ratio of the outer diameter D7 of the distal tube to the outer diameter of the distal tube is 1.1 to 1.5.

[0045] The aforementioned blood pump, because its expansion tube includes a first shape memory material, allows the expansion tube to have an initial shape and an expanded shape relative to that initial shape. The first shape memory material can deform under blood temperature conditions, causing the expansion tube to expand from its initial shape to its expanded shape, thereby increasing the inner diameter of the expansion tube. This allows the blood pump to appropriately reduce the initial width of the radial clearance between the inner wall of the expansion tube and the impeller in its initial state, or even eliminate the radial clearance altogether. This allows the blood pump to use a large-diameter impeller instead of the traditional small-diameter impeller. Since the large-diameter impeller has higher hydraulic performance, the blood pump can appropriately reduce the impeller speed to decrease the collision between the impeller blades and blood cells, thereby reducing blood cell damage and effectively reducing hemolysis.

[0046] Of course, blood pumps can also use traditional impellers with small diameters. After the expansion tube expands from its initial form to its expanded form, the width of the radial gap between the impeller and the inner wall of the expansion tube becomes larger, so that blood cells can pass through the radial gap smoothly and quickly. This can greatly reduce the damage of the impeller to the blood cells passing through the radial gap and reduce hemolysis. Attached Figure Description

[0047] Figure 1 This is a structural diagram of the pump housing of the blood pump according to the first embodiment of this application in its initial state.

[0048] Figure 2 for Figure 1 The provided diagram shows the structural breakdown of a blood pump.

[0049] Figure 3 for Figure 1 A schematic diagram of the longitudinal section of the blood pump is provided.

[0050] Figure 4 for Figure 1 A schematic diagram of the cross-section of the blood pump is provided.

[0051] Figure 5 for Figure 1 The provided isometric view of the pump housing.

[0052] Figure 6 This is a structural diagram of the pump housing of the blood pump according to the first embodiment of this application in an expanded state.

[0053] Figure 7 for Figure 6 The provided diagram shows the structural breakdown of a blood pump.

[0054] Figure 8 for Figure 6 A schematic diagram of the longitudinal section of the blood pump is provided.

[0055] Figure 9 forFigure 6 A schematic diagram of the cross-section of the blood pump is provided.

[0056] Figure 10 for Figure 6 The provided isometric view of the pump housing.

[0057] Figure 11 This is a schematic diagram of the expansion tube of the blood pump in the first embodiment of this application, in its initial and expanded states, housing a large-diameter rigid impeller.

[0058] Figure 12 This is a schematic diagram of the expansion tube of the blood pump in the second embodiment of this application, in its initial and expanded states, housing a small-diameter rigid impeller.

[0059] Figure 13 This is a schematic diagram of the expansion tube of the blood pump in the third embodiment of this application, showing the expansion tube housing the deployable impeller in its initial and expanded states.

[0060] Figure 14 This is a structural diagram of the pump housing of the blood pump according to the third embodiment of this application in its initial state.

[0061] Figure 15 for Figure 14 The provided diagram shows the structural breakdown of a blood pump.

[0062] Figure 16 for Figure 14 A schematic diagram of the longitudinal section of the blood pump is provided.

[0063] Figure 17 for Figure 14 A schematic diagram of the cross-section of the blood pump is provided.

[0064] Figure 18 for Figure 14 The provided isometric view of the pump housing.

[0065] Figure 19 for Figure 18 The provided front view of the pump casing.

[0066] Figure 20 This is a structural diagram of the pump housing of the blood pump according to the third embodiment of this application in an expanded state.

[0067] Figure 21 for Figure 20 The provided diagram shows the structural breakdown of a blood pump.

[0068] Figure 22 for Figure 20 A schematic diagram of the longitudinal section of the blood pump is provided.

[0069] Figure 23 for Figure 20 A schematic diagram of the cross-section of the blood pump is provided.

[0070] Figure 24 for Figure 20 The provided isometric view of the pump housing.

[0071] Figure 25 for Figure 24 The provided front view of the pump casing.

[0072] Figure 26 for Figure 25 The provided front view of the pump casing along II.

[0073] Figure 27 This is a schematic diagram of the initial insertion of the blood pump into the body according to this application.

[0074] Figure 28 This is a schematic diagram illustrating the blood pump of this application pushing blood to the target location within the body.

[0075] Figure 29 The manufacturing process of the pump housing for the blood pump provided in this application. Detailed Implementation

[0076] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0077] In the description of this application, it should be understood that if terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" appear, these terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0078] Furthermore, where the terms "first" and "second" appear, these terms are for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, where the term "multiple" appears, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0079] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0080] In this application, unless otherwise expressly specified and limited, the use of descriptions such as "above" or "below" the second feature indicates that the first and second features are in direct contact or indirect contact via an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. Similarly, "below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0081] It should be noted that if an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. If so, the terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used in this application are for illustrative purposes only and do not represent the only possible implementation.

[0082] It should be noted that the terms "distal" and "proximal" in the text are only used to indicate relative positional relationships. The "distal" end of a component refers to the end that enters the patient's body first and / or is farther away from the operator during normal operation, while the "proximal" end refers to the end that enters the patient's body later and / or is closer to the operator.

[0083] In related technologies, blood pumps contain an impeller inside the pump casing; driving the impeller to rotate drives blood flow. During operation, hemolysis can easily occur as blood flows through the impeller, posing some safety hazards to the blood pump.

[0084] Therefore, this application studies this problem and analyzes its causes. The study found that a radial clearance is usually reserved between the inner wall of the pump casing and the impeller. This radial clearance allows the impeller to rotate freely, preventing it from contacting the inner wall of the pump casing during rotation. On the one hand, if the impeller diameter is designed to be large, the reserved radial clearance will be small. Blood cells will not flow smoothly through this radial clearance and are more likely to collide and damage the impeller blades, thus causing hemolysis. On the other hand, if the radial clearance is designed to be large, the impeller diameter must be reduced. Small-diameter impellers have poor hydraulic performance (i.e., low flow rate). In this case, to meet the hydraulic performance requirements of the blood pump, the impeller speed must be increased. However, increasing the impeller speed intensifies the collision between the impeller and blood cells, thus increasing the risk of hemolysis.

[0085] See Figure 1 , Figure 27 and Figure 28 In view of the above, this application provides a blood pump 10, which aims to reduce the hemolysis rate of the blood pump 10 and improve its safety performance. This blood pump 10 is mainly suitable for being pushed via the aorta 20 to the left ventricle 40 to assist the left ventricle in pumping blood. Of course, in other embodiments, it can also be applied to be pushed via the right ventricle to the pulmonary artery to assist the right ventricle in pumping blood. The following provides a detailed description of various embodiments of the blood pump of this application.

[0086] Figures 1 to 11 A first embodiment of the blood pump of this application is shown. See also Figures 1 to 3 The blood pump 10 of the first embodiment includes a pump housing 100 and an impeller 400A. The pump housing 100 is provided with a proximal opening 101; the impeller 400A is rotatably disposed within the pump housing 100.

[0087] See Figure 3 , Figure 27 and Figure 28 When the blood pump 10 pushes blood into the left ventricle 40 via the aorta 20, the distal end of the blood pump 10 is located within the left ventricle 40, while the proximal opening 101 of the blood pump 10 is located within the aorta 20. When the impeller 400A is rotated, blood from the left ventricle 40 flows from the distal end of the blood pump 10 into the interior of the pump housing 100 and flows out through the proximal opening 101 into the aorta 20, thus assisting the blood pump in delivering blood.

[0088] See Figures 1 to 3The impeller 400A includes a hub 410 and blades 420 disposed on the hub 410. The number of blades 420 can be two, three, or four. When the impeller 400A rotates, a certain radial clearance 102 needs to be maintained between the blades 420 of the impeller 400A and the inner wall surface 103 of the pump casing 100. This radial clearance 102 allows the impeller 400A to rotate within the pump casing 100 without contacting the inner wall surface 103 of the pump casing 100.

[0089] In this embodiment, the impeller 400A is a non-deployable rigid impeller. That is, the impeller 400A has a constant shape, and its shape will not deform before and after the blood pump 10 enters the patient's body. Of course, in other embodiments (such as the third embodiment described below), the impeller 400A can be replaced with a deployable impeller 400A.

[0090] See Figure 1 and Figure 2 , Figure 6 and Figure 7 The pump casing 100 includes an expansion tube 110, and the impeller 400A is housed inside the expansion tube 110. The expansion tube 110 includes a first shape memory material, such that the expansion tube 110 has an initial shape and an expanded shape relative to its initial shape. Figure 1 and Figure 2 The expansion tube 110 in its initial state is shown; Figure 6 and Figure 7 The expansion tube 110 in an expanded state is shown.

[0091] The first shape memory material can deform under blood temperature conditions, thereby causing the expansion tube 110 to expand from its initial state to its expanded state. After the expansion tube 110 expands from its initial state to its original expanded state at blood temperature, the inner diameter of the expansion tube 110 can increase.

[0092] It is understood that after undergoing plastic deformation through heat treatment, the first shape memory material can automatically recover to its pre-heat-treatment form under the stimulation of a predetermined temperature (such as blood temperature). Therefore, for the expansion tube 110 including the first shape memory material, the expanded form of the expansion tube 110 is its pre-heat-treatment form, which is a pre-fabricated working form. When the expansion tube 110 in its expanded form undergoes plastic deformation during heat treatment, the diameter of the expansion tube 110 shrinks, causing the expansion tube 110 to deform from its expanded form back to its initial form. This initial form is the form that the expansion tube 110 presents from the time it undergoes heat treatment until it is inserted into the patient's body. When the expansion tube 110 in its initial form is heated to a predetermined temperature (such as blood temperature), the expansion tube 110 automatically recovers from its initial expansion form to its expanded form (i.e., its working form).

[0093] The blood temperature mentioned refers to the normal blood temperature of a human body, such as 36℃~37.5℃. However, in order to ensure that the expansion tube 110 can also expand normally in patients with blood temperatures that are too low or too high, the deformation temperature of the first shape memory material is 34℃~39℃, so that the expansion tube 110 can be set to expand from the initial form to the expanded form within a temperature range of 34℃~39℃.

[0094] Furthermore, the first shape memory material can be a shape memory polymer or a shape memory alloy. The shape memory polymer can achieve transition temperature control by adjusting its molecular structure. The shape memory polymer can be PLC, PU, ​​or PLA, etc. The shape memory alloy can achieve transition temperature control by adjusting its alloy composition. The shape memory alloy can be a nickel-containing alloy, a titanium-containing alloy, etc. It should be noted that the first shape memory material should be selected as a material that is harmless to the human body and can be applied to the human body. Specifically, in this embodiment, the expansion tube 110 is made of a shape memory alloy, such as a nickel-titanium alloy.

[0095] See Figure 4 and Figure 9 After the expansion tube 110 expands from its initial state to its expanded state, the inner diameter of the expansion tube 110 increases; that is, the inner diameter of the expansion tube 110 in its expanded state is greater than the inner diameter of the expansion tube 110 in its initial state. The inner diameter of the expansion tube 110 in its initial state is denoted as the contracted inner diameter D. 1a The inner diameter of the expansion tube 110 when it is in the expansion state is denoted as the expansion inner diameter D. 1b Then D 1b >D 1a .

[0096] When manufacturing the blood pump 10, the expansion tube 110 of the pump housing 100 can be pre-formed into the desired expansion shape; then the pump housing 100 can be heat-treated to cause the expansion tube 110 to undergo plastic deformation and shrink back to its initial shape; finally, the expansion tube 110 can be assembled onto the blood pump 10 in its initial shape. In other embodiments, the expansion tube 110 can also be assembled onto the blood pump 10 in its expanded shape first; then the expansion tube 110 can be heat-treated to cause it to undergo plastic deformation and shrink back to its initial shape.

[0097] See Figure 11In its initial state, the width of the radial gap 102 between the inner wall surface 103 of the expansion tube 110 and the impeller 400A is denoted as the initial width K1; in its expanded state, the width of the radial gap 102 between the inner wall surface 103 of the expansion tube 110 and the impeller 400A is denoted as the final width K2. When the expansion tube 110 expands from its initial state to its expanded state, the inner diameter of the expansion tube 110 increases; while the diameter of the impeller 400A remains unchanged, so the width of the radial gap 102 increases, i.e., K2 > K1. Thus, the initial width K1 of the radial gap 102 that the blood pump 10 needs to reserve can be small, even equal to 0 mm, allowing the blood pump to use an impeller 400A with a large diameter D3 to replace the traditional impeller 400B with a small diameter D4 (e.g., Figure 12 The large-diameter D3 impeller 400A has high hydraulic performance, so the blood pump 10 can appropriately reduce the speed of the impeller 400A to reduce the degree of collision between the blades 420 of the impeller 400A and blood cells, thereby reducing blood cell damage and effectively reducing hemolysis.

[0098] See Figure 27 When the blood pump 10 is pushed into the body through the wound, the expansion tube 110 enters the patient's body in its initial form. See also Figure 28 When the blood pump 10 pushes blood into the left ventricle 40 via the aorta 20, the distal end of the blood pump 10 is pushed into the left ventricle 40, and the expansion tube 120 and the proximal opening 101 are both housed within the aorta 20. After the expansion tube 110 comes into contact with the blood, the heat of the blood gradually heats the expansion tube 110. Once the expansion tube 110 reaches the blood temperature, it gradually expands, causing it to automatically return from its initial shape to its expanded shape. This increases the inner diameter of the expansion tube 110, and the width of the radial gap 102 increases from the initial width K1 to the final width K2. It can be understood that the initial width K1 is greater than or equal to 0 mm; the final width K2 is greater than the initial width K1. As for the size of the final width K2, it is sufficient that the final width K2 allows the impeller 400A to rotate without easily contacting the inner wall surface of the expansion tube 110.

[0099] Therefore, in the blood pump 10 of this application, the expansion tube 110 of the pump housing 100 includes a first shape memory material, which gives the expansion tube 110 an initial shape and an expanded shape relative to its initial shape. Furthermore, the first shape memory material can deform under blood temperature conditions, causing the expansion tube 110 to expand from its initial shape to its expanded shape, thereby increasing the inner diameter of the expansion tube 110. This allows the initial width K1 of the radial clearance 102 that the blood pump 10 needs to reserve to be small, even equal to 0 mm. Thus, the blood pump 10 can use an impeller 400A with a large diameter D3 instead of the traditional impeller 400B with a small diameter D4. Since the large-diameter D3 impeller 400A has higher hydraulic performance, the blood pump 10 can appropriately reduce the rotational speed of the impeller 400A to reduce the collision degree between the blades 420 of the impeller 400A and blood cells, thereby reducing blood cell damage and effectively reducing hemolysis.

[0100] like Figure 11 As shown in (a), in the initial state, the width of the radial gap 102 between the inner wall surface 103 of the expansion tube 110 and the impeller 400A (i.e., the initial width K1) can be set to K1 < 0.08 mm. At this time, the impeller 400A has not yet started working, so although K1 is small, it does not affect the impeller 400A.

[0101] Optionally, the initial width K1 is set to 0 ≤ K1 ≤ 0.06 mm. The initial width K1 can be, but is not limited to, 0 mm, 0.01 mm, 0.02 mm, 0.03 mm, 0.05 mm, 0.06 mm, etc. When K1 = 0 mm, the diameter D3 of the impeller 400A is at its maximum; the diameter D3 of the impeller 400A is equal to the inner diameter of the expansion tube 110 in its initial state (i.e., the contracted inner diameter D). 1a ), that is, D3=D 1a Therefore, for the rigid impeller 400A, the maximum value of the impeller 400A's diameter D3 can be taken to be the same as the inner diameter of the expansion tube 110 in its initial state (i.e., the contracted inner diameter D). 1a )same.

[0102] like Figure 11 As shown in (a) and (b), after the expansion tube 110 expands from its initial state to its expanded state, the width of the radial gap 102 increases from the initial width K1 to the final width K2, where K2 > K1. The final width K2 only needs to be sufficient to ensure the safe and stable rotation of the impeller 400A. For example, the final width K2 can be set to 0.08mm~0.3mm, i.e., 0.08mm ≤ K2 ≤ 0.3mm. Alternatively, 0.1mm ≤ K2 ≤ 0.3mm. The value of the final width K2 can be, but is not limited to, 0.09mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.25mm, 0.28mm, 0.3mm, etc.

[0103] Because the expansion tube 110 includes the first shape memory material, which is deformable under blood temperature conditions, the expansion tube 110 expands from its initial shape to an expanded shape. In other words, the first shape memory material deforms through temperature stimulation. Therefore, the first shape memory material will not deform when it is not subjected to corresponding temperature stimulation. Based on this, when the expansion tube 110 is not subjected to thermal stimulation (i.e., blood temperature stimulation) in its initial shape, it can maintain a contracted shape relative to its expanded shape without external force; that is, the initial shape of the expansion tube does not require external force to maintain. The shape of the expansion tube 110 in its initial shape is sufficient to allow it to enter the body relatively smoothly. Thus, the expansion tube 110 can maintain a contracted shape relative to its expanded shape without the need for external force compression from a sheath. Subsequently, after being stimulated by blood temperature, the expansion tube 110 gradually expands, and when it reaches the target location (such as one end of the aortic valve 30 adjacent to the aortic valve 20) within the expected time, it expands to an expanded shape.

[0104] It should be noted that, under normal circumstances, when the expansion tube 110 has not reached the target position before the expected time, the expansion tube 110 is in its initial form or in a partially expanded form, and the outer diameter of the expansion tube 110 remains small to facilitate the advancement of the expansion tube 110 within the body; only when the expansion tube 110 reaches the target position at the expected time will the expansion tube 110 fully expand to the expanded form, so that the width of the radial gap 102 increases from the initial width K1 to the final width K2.

[0105] However, in certain unexpected situations, such as when the physician operating the blood pump 10 is inexperienced or when there is significant resistance in the delivery path within the patient's body, these factors may prolong the time it takes for the blood pump 10 to be pushed into the body. In such cases, the expansion tube 110 may expand to its expanded state before reaching the target position. The larger outer diameter of the expansion tube 110 may affect the subsequent advancement of the expansion tube 110 toward the target position.

[0106] To reduce the occurrence of the above situation, the maximum outer diameter of the expansion tube 110 in its expanded state can be set to allow the expansion tube 110 to pass through the narrowest point of the internal delivery path. Thus, if an unexpected situation causes the blood pump 10 to take longer to be inserted into the body, and if the expansion tube 110 fully expands to its expanded state before reaching the aorta 20, then because the maximum outer diameter of the expansion tube 110 in its expanded state allows it to pass through the narrowest point of the internal delivery path, the expansion tube 110 can also pass smoothly through the narrowest point of the internal delivery path in its expanded state. Furthermore, when the blood pump 10 is withdrawn from the patient's body, the expansion tube 110 can also pass smoothly through the narrowest point of the internal delivery path in its expanded state, thus eliminating the need to insert an auxiliary sheath to cover and compress the expansion tube 110 to reduce its outer diameter.

[0107] It is understandable that the narrowest point of the delivery path varies among different patients, such as the elderly and children, obese patients, or emaciated patients. Therefore, the maximum outer diameter of the expansion tube 110 in its expanded state should be rationally designed according to the narrowest point of the delivery path in the actual patient's body, which will not be detailed here.

[0108] Of course, in other embodiments, to prevent the expansion tube 110 from expanding to its expanded state before reaching the target position, an auxiliary sheath can be used to wrap the expansion tube 110, and the auxiliary sheath and the expansion tube 110 can be pushed together to the target position before the auxiliary sheath is removed from the body. After the auxiliary sheath separates from the expansion tube 110, the expansion tube 110 expands to its expanded state.

[0109] It is also worth mentioning that, since the dilator 110 is housed within the aorta 20 in its dilated state, it does not cross the aortic valve 30. Thus, when the blood pump 10 enters or exits the patient's body, the dilated dilator 110 does not need to pass through the aortic valve 30, thereby reducing the likelihood of the dilator 110 compressing and dilating the aortic valve 30, and consequently reducing the damage to the aortic valve 30 caused by the blood pump 10.

[0110] Figure 12 A second embodiment of the blood pump of this application is shown. This second embodiment differs from the first embodiment in that the blood pump 10 of the second embodiment still uses a conventional impeller 400B with a small diameter D4. The diameter D4 of the impeller 400B is smaller than the diameter D3 of the impeller 400A, i.e., D4 < D3. The impeller 400B is also a non-expandable rigid impeller. That is, the impeller 400B has a constant shape, and its shape will not deform before and after the blood pump enters the patient's body.

[0111] Because the diameter D4 of the impeller 400B is relatively small (D4 < D3), the initial width K1 of the radial gap 102 is not 0 mm in the initial state of the expansion tube 110, i.e., K1 > 0 mm. After the expansion tube 110 expands from its initial state to its expanded state, the width of the radial gap 102 increases from the initial width K1 to the final width K2. Obviously, K2 > K1. Due to the increased width of the radial gap 102, when the impeller 400B is started to rotate, blood cells can pass through the radial gap 102 smoothly and quickly. Blood cells will not be congested in the radial gap 102, thus reducing the risk of blood cells being scratched by the blades 420 of the impeller 400B and also reducing hemolysis.

[0112] Therefore, in the blood pump 10 of this application, the expansion tube 110 of the pump housing 100 includes a first shape memory material, which gives the expansion tube 110 an initial shape and an expanded shape relative to its initial shape. Furthermore, the first shape memory material can deform under blood temperature conditions, causing the expansion tube 110 to expand from its initial shape to its expanded shape, thereby increasing the inner diameter of the expansion tube 110. Thus, even if the blood pump 10 uses a conventional impeller 400B with a small diameter D4, after the expansion tube 110 expands from its initial shape to its expanded shape, the width of the radial gap 102 between the impeller 400B and the inner wall surface 103 of the expansion tube 110 can be increased. This allows blood cells to pass smoothly and quickly through the radial gap 102 without congestion, significantly reducing damage to blood cells passing through the radial gap 102 caused by the impeller 400B and reducing hemolysis.

[0113] As can be seen from the first and second embodiments, by providing the expansion tube 110 with a first shape memory material, the expansion tube 110 has an initial shape and an expanded shape relative to its initial shape. The first shape memory material can deform under blood temperature conditions, causing the expansion tube 110 to expand from the initial shape to the expanded shape. This allows the blood pump 10 to reduce damage to blood cells and reduce hemolysis, regardless of whether it uses a rigid impeller 400A with a large diameter D3 or a rigid impeller 400B with a small diameter D4.

[0114] As mentioned above, the impeller 400B in the second embodiment is also a non-expandable rigid impeller. That is, the impeller 400B has a constant shape, and its shape will not deform due to blood temperature before and after the blood pump 10 enters the patient's body. Preferably, the expansion tube 110 is cylindrical in its initial form, so that the expansion tube 110 can accommodate the rigid impeller 400B.

[0115] like Figure 12As shown in (a), in this embodiment, the initial width K1 of the radial clearance 102 between the inner wall surface 103 of the expansion tube 110 and the impeller 400B can be set to at least 0.08 mm. For example, the initial width K1 can be 0.08 mm to 0.2 mm, that is, 0.08 mm ≤ K1 ≤ 0.2 mm. The value of the initial width K1 can be, but is not limited to, 0.09 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, and 0.2 mm.

[0116] Under normal circumstances, when the dilator tube 110 reaches the target position (such as one end of the aortic valve 30 adjacent to the aortic valve 20), it can expand normally to the expanded shape, so that the width of the radial gap 102 increases from the initial width K1 to the final width K2. If an unexpected situation occurs when the dilator tube 110 reaches the target position, such as the dilator tube 110 not expanding or expanding only slightly, this will result in the dilator tube 110 not fully returning to the expanded shape. In this case, since the impeller 400B is a rigid impeller and the width of the radial gap 102 is at least 0.08 mm, even if the dilator tube 110 does not return to the expanded shape, the initial width K1 of the radial gap 102 is sufficient to allow the impeller 400B to rotate stably within the dilator tube 110 and allow blood to flow through the dilator tube 110, preventing the blood pump 10 from becoming completely paralyzed and unable to work.

[0117] like Figure 12 As shown in (b), in the expanded state, the final width K2 of the radial clearance 102 between the inner wall surface 103 of the expansion tube 110 and the impeller 400B is greater than 0.08 mm, i.e., K2 > 0.08 mm. When K2 > K1, the final width K2 can be set to 0.08 mm < K2 ≤ 0.3 mm. The value of the final width K2 can be, but is not limited to, 0.09 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.25 mm, 0.28 mm, 0.3 mm, etc. Preferably, 0.1 mm < K2 ≤ 0.3 mm.

[0118] Figures 13 to 26 A third embodiment of the blood pump of this application is shown. See also Figure 13 In the third embodiment, the difference between this third embodiment and the first embodiment is that the blood pump 10 uses a deformable impeller 400C. Specifically, the impeller 400C includes a second shape memory material, so that the impeller 400C has an initial shape and an expanded shape relative to its initial shape. The second shape memory material can deform under blood temperature conditions, thereby allowing the impeller 400C to expand from the initial shape to the expanded shape.

[0119] It is understood that after undergoing plastic deformation through heat treatment, the second shape memory material can automatically recover its shape before heat treatment by being heated to a predetermined temperature (such as blood temperature). Therefore, for the impeller 400C including the second shape memory material, the expanded form of the impeller 400C is its shape before heat treatment, which is also its pre-fabricated working form. When the impeller 400C in its expanded form undergoes plastic deformation after heat treatment, the blades 420 of the impeller 400C contract or fold, causing the impeller 400C to deform from its expanded form back to its initial form. This initial form is also the form that the impeller 400C presents from the time it undergoes heat treatment until it enters the patient's body. When the impeller 400C in its initial form is heated to a predetermined temperature (such as blood temperature), the impeller 400C automatically recovers its expanded form (i.e., its working form) from its initial expansion.

[0120] The blood temperature mentioned generally refers to the normal blood temperature of a human body, such as 36℃~37.5℃. However, in order to ensure that the impeller 400C can also expand normally in the bodies of patients with low or high blood temperatures, the deformation temperature of the second shape memory material is 34℃~39℃, so that the impeller 400C can expand from its initial form to its expanded form within a blood temperature range of 34℃~39℃.

[0121] The second shape memory material may be the same as or different from the first shape memory material. The second shape memory material may be a shape memory polymer or a shape memory alloy. The shape memory polymer can achieve transition temperature control by adjusting its molecular structure. The shape memory polymer may be PLC, PU, ​​or PLA, etc. The shape memory alloy can achieve transition temperature control by adjusting its alloy composition. The shape memory alloy may be a nickel-containing alloy, a titanium-containing alloy, etc. It should be noted that the first shape memory material should be selected as a material that is harmless to the human body and can be applied to the human body. Specifically, in this embodiment, the impeller 400C is made of a shape memory alloy, such as a nickel-titanium alloy. This gives the impeller 400C a certain degree of hardness, ensuring that the impeller 400C can rotate stably.

[0122] See Figure 14 and Figure 15 ,as well as Figure 20 and Figure 21 After the impeller 400C expands from its initial shape back to its original expanded shape, the blades 420 of the impeller 400C unfold, making the diameter of the impeller 400C larger.

[0123] See Figure 13 (a) or Figure 17 The diameter of the impeller 400C in its initial state is denoted as the initial diameter D. 5a See also Figure 13 (b) orFigure 23 The diameter of the impeller 400C in its expanded state is denoted as the working diameter D. 5b Then we have D 5b >D 5a This allows the impeller 400C to have a larger diameter, resulting in higher hydraulic performance. Under these conditions, reducing the rotational speed of the impeller 400C within a certain range can also meet the hydraulic performance requirements of the blood pump 10. Because the rotational speed of the impeller 400C is reduced, the blades 420 of the impeller 400C collide with and damage blood cells, effectively reducing hemolysis.

[0124] See Figures 14 to 16 When the blood pump 10 is pushed into the body through the wound, the expansion tube 110 and the impeller 400C both enter the body in their initial state. See also Figures 20 to 22 The blood is pushed to the left ventricle 40 via the aorta 20, so that the distal end of the blood pump 10 is located within the left ventricle 40, while the expansion tube 120 and the proximal opening 101 are both housed within the aorta 20. After the expansion tube 110 and the impeller 400C come into contact with the blood, the heat of the blood gradually heats the impeller 400C and the expansion tube 110. When the impeller 400C and the expansion tube 110 reach the blood temperature, they gradually expand, causing the impeller 400C and the expansion tube 110 to automatically return from their initial state to their expanded state. As a result, the diameter of the impeller 400C increases, and the inner diameter of the expansion tube 110 also increases, allowing the expansion tube 110 to accommodate the expanded impeller 400C with the blades 420.

[0125] Because the impeller 400C includes a second shape memory material, which can deform under blood temperature conditions, the impeller 400C unfolds from its initial form to its expanded form. In other words, the second shape memory material deforms through temperature stimulation. Therefore, the second shape memory material will not deform when it is not subjected to a corresponding temperature stimulus. Based on this, when the impeller 400C is not stimulated by a corresponding temperature (such as blood temperature) in its initial form, the impeller 400C can maintain its folded shape relative to its expanded form without external force. That is, the initial form of the impeller 400C does not require external force to maintain. The diameter of the impeller 400C in its initial form only needs to be small enough to be housed within the expansion tube 110 in its initial form. This allows the impeller 400C to maintain its common folded shape relative to its expanded form without the need for external force compression from a sheath. Subsequently, when the impeller 400C is stimulated by blood temperature, it can gradually expand to its expanded form.

[0126] It is understandable that when both the expansion tube 110 and the impeller 400C are in their initial state, the initial width K1 of the radial clearance 102 between the impeller 400C and the inner wall surface 103 of the expansion tube 110 can be 0 mm or greater than 0 mm, i.e., K1 ≥ 0 mm. After the expansion tube 110 and the impeller 400C return to their expanded state, the width of the radial clearance 102 increases from the initial width K1 to the final width K2. The final width K2 is sufficient to allow the impeller 400C to rotate stably without contacting the inner wall surface 103 of the expansion tube 110.

[0127] In particular, when the initial width K1 is 0mm, after the expansion tube 110 and impeller 400C return to their expanded state, the working diameter D of impeller 400C will... 5a The inner diameter D of the expansion tube is larger than the initial shrinkage diameter of the expansion tube 110. 1a This allows the impeller 400C to have a larger diameter, significantly improving its hydraulic performance. Consequently, while meeting the hydraulic performance requirements of the blood pump 10, the rotational speed of the impeller 400C can be reduced, making it less likely for the blades 420 of the impeller 400C to collide with and damage blood cells, effectively reducing hemolysis. Therefore, optionally, the expansion tube 110 has a contracted inner diameter D in its initial state. 1a The initial diameter D of the impeller 400C 5a Greater than or equal to the shrinkage inner diameter D 1a D 5a ≥D 1a .

[0128] Optionally, in the expanded state, the width K2 of the radial clearance 102 between the inner wall surface 103 of the expansion tube 110 and the impeller 400C can be 0.08mm to 0.3mm, i.e., 0.08mm ≤ K2 ≤ 0.3mm. Alternatively, 0.1mm ≤ K2 ≤ 0.3mm. The value of K2 can be, but is not limited to, 0.09mm, 0.1mm, 0.12mm, 0.15mm, 0.18mm, 0.2mm, 0.25mm, 0.28mm, 0.3mm, etc.

[0129] See Figures 14 to 16 The pump housing 100 also includes a proximal tube 120, which is connected to the proximal end of the expansion tube 110. The proximal tube 120 has a proximal opening 101 and is a non-deformable structure. The proximal tube 120 has a certain degree of rigidity, meaning it will not deform due to blood flow after entering the body. This gives the proximal tube 120 strong rigidity, improving the connection between the proximal tube 120 and the drive unit 500 and preventing the connection from loosening or falling off.

[0130] Preferably, the working diameter D of the impeller 400C is... 5aThe inner diameter is larger than that of the proximal tube 120. This allows the impeller 400C to have a larger diameter, resulting in higher hydraulic performance. While meeting the hydraulic performance requirements of the blood pump 10, the rotational speed of the impeller 400C can be reduced to a significant extent, thereby reducing the damage to blood cells caused by the rotation of the impeller 400C.

[0131] See Figures 14 to 16 The pump housing 100 also includes a distal tube 130, which is connected to the distal end of the expansion tube 110. The distal tube 130 is a non-deformable structure, meaning it will not deform due to blood flow after entering the body. The distal tube 130 can be connected to a cannulation assembly 200 with a distal opening 201. Alternatively, in other embodiments, the distal opening 201 can be directly provided in the distal tube 130.

[0132] Preferably, the initial diameter D 5a The inner diameter is larger than that of the distal tube 130. This allows the impeller 400C to have a larger diameter, resulting in higher hydraulic performance. While meeting the hydraulic performance requirements of the blood pump 10, the rotational speed of the impeller 400C can be reduced to a significant extent, thereby reducing the damage to blood cells caused by the rotation of the impeller 400C.

[0133] In this embodiment, the proximal tube 120 and the distal tube 130 are located on the same cylindrical tube, so the proximal tube 120 and the distal tube 130 have the same inner diameter and the same outer diameter.

[0134] In such Figures 1 to 11 The first embodiment of the blood pump shown Figure 12 The second embodiment of the blood pump shown, or Figures 13 to 26 In the third embodiment of the blood pump shown, the blood pump 10 may further include any one of the cannulation assembly 200, the catheter 300, and the drive unit 500. The pump housing 100 of the blood pump 10 may further include any one of the proximal tube 120 and the distal tube 130. The expansion tubes 110 of the pump housing 100 may each be provided with a deformable orifice 11a, a deformable valve 11b, and a flexible membrane located in the deformable orifice 11a. To avoid redundancy, the following description mainly refers to... Figures 14 to 26 The blood pump 10 of the illustrated embodiment is used as an example for description; the blood pump 10 of other embodiments can be implemented accordingly, and will not be listed separately here.

[0135] See Figures 14 to 15 and Figure 18The blood pump 10's expansion tube 110 is provided with a deformation hole 11a. The deformation hole 11a allows the expansion tube 110 to have higher ductility, making it easier for the expansion tube 110 to deform under heat. During the process of the expansion tube 110 shrinking from an expanded state to its initial state through heat treatment, the deformation hole 11a provides contraction space for the tube wall of the expansion tube 110 to shrink. During the process of the expansion tube 110 expanding from its initial state to its expanded state due to the influence of blood temperature, the deformation hole 11a can reduce the stress on the tube wall of the expansion tube 110, making the expansion tube 110 easier to expand under heat.

[0136] See Figures 14 to 15 and Figure 18 The deformation hole 11a is elongated. The deformation hole 11a extends axially along the pump housing 100. Specifically, the deformation hole 11a has a first width W1 extending circumferentially along the pump housing 100 and a first length L1 extending axially along the pump housing 100, the first length L1 being greater than the first width W1. This allows the expansion tube 110 to expand radially more easily, thereby increasing the diameter of the expansion tube 110. Of course, in other embodiments, the shape of the deformation hole 11a can also be elliptical, corrugated, or slit-shaped, as long as the length direction of the deformation hole 11a is the same as the axial direction of the pump housing 100.

[0137] See Figures 16 to 18 The number of deformation holes 11a can be multiple. Multiple deformation holes 11a are arranged at intervals along the circumferential direction of the expansion tube 110. Of course, in other embodiments, there may be only one deformation hole 11a.

[0138] See Figures 16 to 18 Optionally, multiple deformation holes 11a are arranged at equal intervals along the circumferential direction of the expansion tube 110. This ensures that the stress or strength of the tube wall on both sides of the deformation hole 11a is approximately the same, so that when the expansion tube 110 deforms, all positions around the circumference of the expansion tube 110 contract or expand radially by an equal amount, ensuring that it remains a circular tube before and after deformation. This, in turn, ensures that the inner wall surface 103 of the expansion tube 110 and the impeller 400 maintain a uniform radial clearance 102 along the circumferential direction. The number of deformation holes 11a can be 2 to 6. For example, the number of deformation holes 11a can be, but is not limited to, 2, 3, or 4.

[0139] See Figures 16 to 18A flexible membrane (not shown in the figure) covering the deformation hole 11a is also provided in the expansion tube 110. In the initial state, the flexible membrane can be contracted or folded in the deformation hole 11a. When the expansion tube 110 returns to the expanded state from the initial state, the flexible membrane can be stretched or unfolded along the circumference of the pump housing 100. Since the flexible membrane covers the deformation hole 11a, it can be ensured that when the expansion tube 110 expands to the expanded state, the impeller 400C drives the blood to flow through the expansion tube 110, a higher pressure can be formed in the expansion tube 110, which helps to improve the blood flow rate.

[0140] Preferably, the periphery of the flexible membrane is fixedly connected to the periphery of the deformation hole 11a, making the flexible membrane less prone to detachment. For example, the periphery of the flexible membrane and the periphery of the deformation hole 11a can be bonded by adhesive or heat fusion. The periphery of the flexible membrane and the periphery of the deformation hole 11a are also sealed together to seal and cover the deformation hole 11a, preventing blood from flowing out of the deformation hole 11a. The material of the flexible membrane can be Teflon. A PTFE membrane may also be used.

[0141] See Figures 16 to 18 A deformable flap 11b extending axially along the pump housing 100 is formed between two adjacent deformable holes 11a. The deformable flap 11b is part of the wall of the expansion tube 110. The deformable flap 11b has a second width W2 extending a certain distance circumferentially along the pump housing 100. In this embodiment, in the initial state of the expansion tube 110, the second width W2 of the deformable flap 11b is greater than the first width W1 of the deformable hole 11a, i.e., W2 > W1. Alternatively, the second width W2 is greater than the radial thickness of the deformable flap 11b. This allows the deformable flap 11b to obtain a larger cross-sectional area without occupying the radial space of the expansion tube 110, giving the deformable flap 11b, i.e., the expansion tube 110, a certain degree of rigidity. In this way, the expansion tube 110 can better maintain the shape of the relatively expanded shape in the initial state, making it easier for the expansion tube 110 to enter the body in the initial state and less likely to be squeezed and collapsed by the body tissue. On the other hand, when the expansion tube 110 is stimulated by blood temperature, the expansion tube 110 slowly expands from the initial state to the expanded state, thereby avoiding the expansion tube 110 from the initial state to the expanded state too quickly after being stimulated by blood temperature.

[0142] Furthermore, after the expansion tube 110 expands to its expanded state, the second width W2 of the deformable lobe 11b is also relatively large. Compared to the elastic metal wire in the shape of a filament, the deformable lobe 11b of the expansion tube 110 in its expanded state has greater hardness, so the deformable lobe 11b is not easily crushed and comes into contact with the impeller 400C.

[0143] Optionally, the cross-section of the deformable lobe 11b obtained by the plane perpendicular to the central axis of the pump housing 100 is arc-shaped, not circular. Furthermore, in its initial state, the deformable lobe 11b is part of the wall of the cylindrical tube 110, and the second width W2 of the deformable lobe 11b remains constant along the axial direction of the pump housing 100. In its expanded state, the second width W2 of the expansion tube 110 gradually decreases from its middle portion towards both ends along its axial direction, causing the deformable lobe 11b to take on an arc-shaped, boat-shaped, or crescent-shaped form that convexes outward relative to the central axis of the pump housing 100.

[0144] Optionally, the number of deformation lobes 11b is 2 to 4. The number of deformation lobes 11b is consistent with the number of deformation holes 11a. For example, the number of deformation lobes 11b can be 2, 3, or 4. Since the multiple deformation holes 11a are evenly spaced along the circumference of the expansion tube 110, the second width W2 of the multiple deformation lobes 11b is substantially the same. When the expansion tube 110 deforms, the multiple deformation lobes 11b shrink or expand equally in the radial direction, so that the expansion tube 110 remains a cylindrical tube before and after deformation, thereby ensuring that the inner wall surface 103 of the expansion tube 110 and the impeller 400 maintain a uniform radial gap in the circumference direction.

[0145] See Figure 18 The outer diameter of the expansion tube 110 in its initial state is denoted as the contracted outer diameter D. 2a The second width W2 of the deformed lobe 11b can be W2 ≥ 0.25 × π × D 2a This design ensures that the deformable lobe 11b has a large width, which in turn gives the wall of the expansion tube 110 better strength, ensuring that the expansion tube 110 has high strength before and after deformation and is not easily deformed by external forces.

[0146] Optionally, 0.25×π×D 2a ≤W2≤0.5×π×D 2a .

[0147] See Figure 16 and Figure 18 The expansion pipe 110 includes a main pipe section 111 and a first pipe section 112, the first pipe section 112 being connected to the proximal end of the main pipe section 11. See also Figures 24 to 26 In its expanded state, the diameter of the first tube segment 112 gradually decreases from the distal end to the proximal end of the pump housing 100. This gives the first tube segment 112 a certain inclination. On one hand, the inner wall surface 103 of the first tube segment 112 forms a conical guide surface, which can guide blood from the main tube segment 111 to the first tube segment 112, facilitating blood discharge from the proximal opening 101 near the first tube segment 112. On the other hand, the outer wall surface of the first tube segment 112 forms a conical narrowing surface, which helps reduce the difficulty of removing the expansion tube 110 from the blood vessel during the process of the blood pump 10 being withdrawn from the body.

[0148] See Figure 16 and Figure 18 The expansion pipe 110 may also include a main pipe section 111 and a second pipe section 113, the second pipe section 113 being connected to the distal end of the main pipe section 11. See also Figures 24 to 26 In its expanded state, the diameter of the second tube segment 113 gradually decreases from the proximal end to the distal end of the pump housing 100. This gives the second tube segment 113 a certain inclination. On one hand, the inner wall surface 103 of the second tube segment 113 forms a conical guide surface, which can guide blood from the second tube segment 113 into the main tube segment 111, thus improving the efficiency of blood flow to the impeller 400C. On the other hand, the outer wall surface of the second tube segment 113 forms a conical narrowing surface, which facilitates the movement of the expansion tube 110 back and forth after the blood pump 10 pushes it into the human body to fine-tune its position in the blood vessel.

[0149] Of course, the expansion pipe 110 can simultaneously have a main pipe section 111, a first pipe section 112, and a second pipe section 113.

[0150] See Figure 16 The impeller 400C has a hub 410 and blades 420 disposed on the hub 410. The blades 420 have a second length L2 extending axially along the pump casing 100; the first length L1 is greater than the second length L2 (i.e., L1 > L2), so that the two ends of the deformation hole 11a extend beyond the two ends of the blades 420. This allows effective deformation of the radially opposing pipe walls of the expansion tube 110 and the blades 420, ensuring that the radial clearance 102 between any position of the outer edge of the blades 420 and the inner wall surface 103 of the expanded expansion tube 110 can be increased.

[0151] See Figure 16 The blade 420 is completely housed within the expansion tube 110. A first distance ΔL1 is maintained between the proximal end of the blade 420 and the proximal end of the expansion tube 110 along the axial direction of the pump casing 100. Since the deformation of the first section 112 of the expansion tube 110 is slightly smaller than that of the main section 111, maintaining a first distance ΔL1 between the proximal end of the blade 420 and the proximal end of the expansion tube 110 along the axial direction of the pump casing 100 prevents contact and interference between the blade 420 and the proximal end of the expansion tube 110.

[0152] Similarly, the distal end of the blade 420 and the distal end of the expansion tube 110 are spaced apart by a second distance ΔL2 along the axial direction of the pump casing 100. Since the deformation of the second section 113 of the expansion tube 110 is slightly smaller than that of the main section 111, by spaced apart by a second distance ΔL2 along the axial direction of the pump casing 100, the blade 420 and the distal end of the expansion tube 110 can be prevented from contacting and interfering with each other.

[0153] See Figures 14 to 16 The pump housing 100 has a proximal opening 101 at its proximal end. The blood pump 10 has a distal opening 201 at its distal end. See also Figure 28 When the blood pump 10 pushes blood into the left ventricle 40 via the aorta 20, the distal end of the distal opening 201 of the blood pump 10 is located within the left ventricle 40, while the proximal opening 101 is located within the aorta 20. Blood from the left ventricle 40 flows into the blood flow channel within the pump housing 100 from the distal opening 201 of the blood pump 10, and flows out into the aorta 20 from the proximal opening 101, thus assisting the left ventricle in pumping blood.

[0154] See Figures 14 to 16 The blood pump 10 also includes a cannulation assembly 200, which includes a cannula 210, the proximal end of which is fixed to the distal end of the pump housing 100. The lumen of the cannula 210 forms a blood flow channel. The cannulation assembly 200 may also include a distal tube 220, which has a distal opening 201. The cannula 210 is a flexible tube that can be bent and deformed to adapt to the shape of the blood vessel. In its natural state, the cannula 210 can be a straight tube or a pre-shaped curved tube with a certain bending angle. After the blood pump 10 is pushed into the body, the cannula 210 passes through the aorta 20, crosses the aortic valve 30, and extends into the left ventricle 40, so that the distal opening 201 is located in the left ventricle, while the expansion tube 110 and the proximal opening 101 of the pump housing 100 are both located in the aorta 20.

[0155] It is understood that the distal cannula 220 is not essential. In other embodiments, a distal opening 201 can be directly formed at the distal end of the cannula 210. Of course, the blood pump 10 can also eliminate the entire cannula assembly 200. Because the expansion tube 110 of the pump housing 100 has a large diameter after expanding to its expanded state, the expansion tube 110 can be adapted and positioned in the aorta 20. In this way, the blood pump 10 eliminates the cannula assembly 200 and directly forms a distal opening 201 at the distal end of the pump housing 100. The distal end of the pump housing 100 only needs to extend slightly into the left ventricle 40 so that the distal opening 201 of the pump housing 100 enters the left ventricle 40, without the need for the cannula assembly 200 to be inserted into the bottom of the left ventricle 40 for support and positioning.

[0156] See Figures 14 to 16 The blood pump 10 also includes a drive unit 500, which is capable of driving the impeller 400C to rotate. The drive unit 500 is fixed to the proximal end of the pump housing 100 and can be inserted into the patient's blood vessel together with the pump housing 100.

[0157] See Figures 14 to 16The drive unit 500 includes a housing 510 and a rotating shaft 520. The housing 510 is connected to the pump housing 100; the rotating shaft 520 is rotatably mounted on the housing 510, extending out of the housing 510 and having a connecting end 521 housed within the pump housing 100, which is fixedly connected to an impeller 400C. Specifically, the connecting end 521 is fixedly connected to the hub 410 of the impeller 400C. The proximal opening 101 of the pump housing 100 is typically located adjacent to the distal end of the housing 510.

[0158] See Figures 14 to 16 The drive unit 500 may further include a rotor 540 and a stator 530. The rotor 540 and stator 530 are housed in the housing 510 and are arranged axially at intervals. A rotating shaft 520 rotatably passes through the stator 530 and is fixedly connected to the rotor 540. The number of stators 530 can be one, two, or more; the number of rotors 540 can also be one, two, or more. When the stator 530 is operating, it generates a rotating magnetic field that causes at least one rotor 540 to rotate. Under this rotating magnetic field, the rotor 540 drives the rotating shaft 520 to rotate, and the impeller 400C also rotates accordingly.

[0159] Of course, the drive unit 500 may also exclude the rotor 540 and stator 530. In other embodiments, the drive unit 500 may include a coupling and a flexible shaft (not shown); the coupling is housed within a housing 510; the proximal end of the flexible shaft is connected to an external motor, and the distal end of the flexible shaft is connected to the coupling, which connects to the proximal end of the rotating shaft 520. Thus, the external motor drives the flexible shaft to rotate, causing the flexible shaft to drive the rotating shaft 520 to rotate together via the coupling. The coupling may be a magnetic coupling or a conventional coupling. For example, the coupling is a magnetic coupling, specifically including a driving magnet and a driven magnet; the driving magnet is fixed to the flexible shaft; the driven magnet is fixed to the proximal end of the rotating shaft 520, and the driving magnet and the driven magnet have a mutual magnetic attraction.

[0160] See Figures 14 to 16 and Figure 18 The proximal tube 120 of the pump housing 100 is fixedly connected to the outer shell 510 of the drive unit 500, and the proximal tube 120 is provided with a proximal opening 101. Optionally, the proximal tube 120 and the expansion tube 110 are integrally formed. The proximal tube 120 can be made of the same material as the expansion tube 110 or a different material. For example, both the proximal tube 120 and the expansion tube 110 are made of shape-memory metal. However, during manufacturing, the proximal tube 120 is not subjected to plastic deformation treatment, so the proximal tube 120 does not have an initial shape and an expanded shape. Therefore, the proximal tube 120 will not deform when it comes into contact with blood, ensuring that the connection between the proximal tube 120 and the drive unit 500 is firm and not easy to fall off.

[0161] See Figure 16 and Figure 18 A first crease T1 is formed at the connection between the first pipe section 112 of the expansion pipe 110 and the proximal pipe 120; a second crease T2 is formed at the connection between the first pipe section 112 and the main pipe section 111. See also Figure 22 and Figures 24 to 26 When the expansion tube 110 deforms from its initial form to its expanded form, the expansion tube 110 bends and deforms at the first crease T1 and the second crease T2, so that the diameter of the first tube segment 112 gradually increases from the first crease T1 to the second crease T2 in the expanded form.

[0162] See Figure 19 Optionally, the outer diameter of the expansion tube 110 in its initial state is denoted as the contracted outer diameter D. 2a The contracted outer diameter D 2a The outer diameter D6 is the same as that of the proximal tube 120. That is, D... 2a =D6. This ensures that the internal volume of the expansion tube 110 in its initial state is large enough to accommodate impellers 400A or 400C with larger diameters. Furthermore, it allows the outer surface of the expansion tube 110 and the outer surface of the proximal tube 120 to lie on the same cylindrical surface, enabling a smoother connection between their outer surfaces.

[0163] See Figure 19 and Figure 25 Optionally, the outer diameter of the expansion tube 110 when it is in the expansion state is denoted as the expansion outer diameter D. 2b The expanded outer diameter D 2b The ratio of the outer diameter D6 of the proximal tube 120 to the outer diameter D6 is 1.1~1.5. That is, 1.1 ≤ D. 2b / D6≤1.5. This ratio can be, but is not limited to, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.49, etc. This can prevent the outer diameter of the expansion tube 110 from being too large in the expansion mode.

[0164] See Figures 14 to 16 and Figure 18The distal tube 130 of the pump housing 100 is fixedly connected to the proximal end of the cannula 210. The distal tube 130 is a non-deformable structure. The distal tube 130 has a certain degree of rigidity. Optionally, the distal tube 130 and the expansion tube 110 are integrally formed. The distal tube 130 can be made of the same material as the expansion tube 110 or a different material. For example, both the distal tube 130 and the expansion tube 110 are made of shape-memory metal. However, since no plastic deformation treatment is performed on the distal tube 130 during manufacturing, the distal tube 130 does not have an initial shape or an expanded shape. Therefore, the distal tube 130 will not deform when it comes into contact with blood, ensuring that the connection between the distal tube 130 and the cannula 210 is firm and not easily detached.

[0165] See Figure 18 and Figures 24 to 26 A third crease T3 is formed at the connection between the second pipe segment 113 of the expansion pipe 110 and the distal pipe 130; a fourth crease T4 is formed at the connection between the second pipe segment 113 and the main pipe segment 111. When the expansion pipe 110 deforms from its initial form to its expanded form, the expansion pipe 110 bends and deforms at the third crease T3 and the fourth crease T4, so that in the expanded form, the diameter of the second pipe segment 113 gradually increases from the third crease T3 to the fourth crease T4.

[0166] See Figure 19 The outer diameter of the expansion tube 110 in its initial state is denoted as the contracted outer diameter D. 2a The contracted outer diameter D 2a The outer diameter D7 is the same as that of the distal tube 130. That is, D... 2a =D6. This allows the expansion tube 110 to have a larger diameter in its initial state, resulting in a larger internal space that can accommodate an impeller 400C with a larger diameter. On the other hand, it allows the outer surface of the expansion tube 110 and the outer surface of the proximal tube 120 to be located on the same cylindrical surface, and the two outer surfaces can be connected relatively smoothly.

[0167] See Figure 19 and Figure 25 Optionally, the outer diameter of the expansion tube 110 when it is in the expansion state is denoted as the expansion outer diameter D. 2b The expanded outer diameter D 2b The ratio of the outer diameter D7 of the distal tube 130 to the outer diameter D7 is 1.1~1.5. That is, 1.1 ≤ D. 2b / D7≤1.5. This ratio can be, but is not limited to, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.49, etc. This can prevent the outer diameter of the expansion tube 110 from being too large in the expansion mode.

[0168] It is understandable that the proximal tube 120 is not necessary. The proximal opening 101 can be located at the proximal end of the expansion tube 110, that is, the proximal opening 101 is located on the first tube segment 111; the proximal end of the first tube segment 111 is fixedly connected to the housing 510 of the drive unit 500. The distal tube 130 is also not necessary, and can be connected from the distal end of the expansion tube 110 to the insertion cannula 210.

[0169] See Figures 14 to 16 The blood pump 10 also includes a catheter 300, which is connected to the proximal end of the drive unit 500. The catheter 300 has an inner lumen that can accommodate flushing lines, sensor optical fibers, conductors of the stator 530, and other cables.

[0170] See Figure 14 and Figure 15 The blood pump 10 also includes a pressure sensor 600, which is used to detect blood pressure. In some conventional technologies, the pressure sensor 600 is fixed to the pump housing 100 with adhesive. However, considering that if the pressure sensor 600 is still installed on the pump housing 100 in this embodiment, the expansion tube 110 of the pump housing 100 may stretch and deform, potentially pulling on the pressure sensor 600, and the adhesive on the pressure sensor 600 may detach.

[0171] Therefore, in this embodiment, the pressure sensor 600 is installed on the drive unit 500, so that when the expansion tube 110 of the pump housing 100 expands and deforms, it will not pull the pressure sensor 600, and thus the pressure sensor 600 is not easy to fall off, and the installation is more stable.

[0172] Specifically, the pressure sensor 600 includes a probe and an optical fiber connected to the probe; the optical fiber is housed inside the catheter 300. The probe is installed inside the housing 510 of the drive unit 500. A detection window is provided on the side wall of the housing 510; the probe corresponds to the detection window to sense blood pressure.

[0173] See Figure 29 This application also provides a method for manufacturing the pump housing 100 of the blood pump 10:

[0174] First step, such as Figure 29 As shown in (a), take a cylindrical tube M made of shape memory material.

[0175] The second step, as Figure 29 As shown in (b), the cylindrical tube M is divided into a proximal tube 120, a distal tube 130, and an expansion tube 110 located between the proximal tube 120 and the distal tube 130 as required by the plan.

[0176] Specifically, the expansion tube 110 is further divided into a first part P1, a second part P2 and a third part P3 arranged along the axial direction. The first part P1 is connected to the proximal tube 120 and the second part P2 is connected to the distal tube 130.

[0177] The third step, as Figure 29 As shown in (c), the expansion tube 110 of the cylindrical tube M is expanded radially, while the proximal tube 120 and the distal tube 130 remain unchanged and are not expanded, so that only the expansion tube 110 obtains the expanded shape.

[0178] Specifically, the third portion P3 of the expansion tube 110 is radially expanded to form the main pipe section 111. During this process, the diameter of the first portion P1 gradually increases from the distal end of the proximal tube 120 towards the main pipe section 111, thus forming the first pipe section 112. The diameter of the second portion P2 gradually increases from the proximal end of the distal tube 130 towards the main pipe section 111, thus forming the second pipe section 113 of the expansion tube 110. A first crease T1 and a second crease T2 are formed at both ends of the first pipe section 112, respectively; a third crease T3 and a fourth crease T4 are formed at both ends of the second pipe section 113, respectively.

[0179] Step four, as Figure 29 As shown in (d), the pump casing 100 is heat-treated, and the expansion tube 110 of the pump casing 100 is compressed to its initial shape after heat treatment. Since the proximal tube 120 and the distal tube 130 were not expanded in the third step, they will not deform during the heat treatment in this fourth step. The expansion tube 110 shrinks to approximately the same size as the proximal tube 120 and the distal tube 130, thus the expansion tube 110 of the pump casing 100 obtains its initial shape. In this shape, the proximal tube 120, the distal tube 130, and the expansion tube 110 are approximately a single cylindrical tube.

[0180] After the fourth step of the above process, the expansion tube 110 of the pump housing 100 can be stably maintained in its initial form without heating. After the pump housing 100 is pushed into the body by the blood pump 10 in this form, the expansion tube 110 of the pump housing 100 gradually expands and returns to its expanded form under the influence of blood temperature.

[0181] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0182] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A blood pump, characterized in that, The blood pump comprises: a pump housing provided with a proximal opening; and an impeller rotatably arranged in the pump housing; wherein the pump housing comprises a volume-expanding tube accommodating the impeller, the volume-expanding tube comprises a first shape memory material, the volume-expanding tube has an initial shape and an expanded shape expanded relative to the initial shape, and the first shape memory material is capable of deforming at a blood temperature to expand the volume-expanding tube from the initial shape to the expanded shape; the volume-expanding tube is provided with a deformation hole extending along an axial direction of the pump housing, and the deformation hole is provided with a flexible membrane covering the deformation hole; and the volume-expanding tube is capable of stretching or unfolding the flexible membrane along a circumferential direction of the pump housing when the volume-expanding tube recovers from the initial shape to the expanded shape; the impeller comprises a hub and blades arranged on the hub, and the blades are located in the volume-expanding tube; wherein the deformation hole has a first length extending along the axial direction of the pump housing, the blades have a second length extending along the axial direction of the pump housing, the first length is greater than the second length, and both ends of the deformation hole extend beyond both ends of the blades.

2. The blood pump of claim 1, wherein, The volume-expanding tube further has at least one of the following characteristics: the first shape memory material is a shape memory metal; the temperature at which the first shape memory material deforms is 34-39°C; the volume-expanding tube has a circular tube shape in the initial shape; the initial shape of the volume-expanding tube does not need to be maintained by external force; the volume-expanding tube can be accommodated in the aorta in the expanded shape; the maximum outer diameter of the volume-expanding tube in the expanded shape allows the volume-expanding tube to pass through the narrowest position on the in-vivo pushing path.

3. The blood pump of claim 1, wherein, The impeller comprises a second shape memory material, and the impeller also has an initial shape and an expanded shape unfolded relative to the initial shape; the second shape memory material is capable of deforming at a blood temperature to unfold the impeller from the initial shape to the expanded shape.

4. The blood pump of claim 3, wherein, The impeller further has at least one of the following characteristics: the second shape memory material is a shape memory metal; the temperature at which the second shape memory material deforms is 34-39°C; the initial shape of the impeller does not need to be maintained by external force.

5. The blood pump of claim 3, wherein, The inner diameter of the expansion pipe in the initial form is a contraction inner diameter D 1a , the diameter of the impeller in the initial form is an initial diameter D 5a , the diameter of the impeller in the expanded form is a working diameter D 5b , wherein D 5b >D 5a , and D 5b ≥D 1a .

6. The blood pump of claim 3, wherein, the diameter of the impeller in the expanded configuration is a working diameter D 5b ; the pump housing further comprises a proximal tube connected to a proximal end of the expansion tube and provided with the proximal opening, the proximal tube being a non-deformable structure, the working diameter D 5b being greater than an inner diameter of the proximal tube; and / or, The pump housing further comprises a distal tube connected to a distal end of the expansion tube, the distal tube being a non-deformable structure, the working diameter D 5b greater than an inner diameter of the distal tube.

7. The blood pump of claim 1, wherein, The impeller is a non-unfoldable rigid impeller; when the volume-expanding tube is in the initial shape, the width of a radial gap between the inner wall surface of the volume-expanding tube and the impeller is 0-0.06 mm or 0.08-2 mm.

8. The blood pump of claim 1, wherein, When the volume-expanding tube is in the expanded shape, the width of the radial gap between the inner wall surface of the volume-expanding tube and the impeller is 0.1-0.3 mm.

9. The blood pump of claim 1, wherein, The volume-expanding tube is provided with a plurality of deformation holes, and the plurality of deformation holes are arranged at intervals along a circumferential direction of the volume-expanding tube; adjacent two deformation holes form a deformation lobe extending along an axial direction of the pump housing, and a cross section of the deformation lobe cut by a plane perpendicular to a central axis of the pump housing is arc-shaped and non-circular.

10. The blood pump of claim 1, wherein, The volume-expanding tube is provided with a plurality of deformation holes, and the plurality of deformation holes are arranged at intervals along a circumferential direction of the volume-expanding tube; adjacent two deformation holes form a deformation lobe extending along an axial direction of the pump housing.

11. The blood pump of claim 10, wherein, The deformation hole has a first width W1 extending along the circumference of the pump shell, the deformation lobe has a second width W2 extending along the circumference of the pump shell, and the expansion pipe has a contracted outer diameter D in the initial form 2a ; wherein W2 > W1; and / or, W2 ≥ 0.25πD 2a .

12. The blood pump of claim 10, wherein, The volume-expanding tube further has at least one of the following characteristics: The number of the deformation petals of the expansion pipe is 2-5; The periphery of the flexible membrane of the expansion pipe is fixedly connected with the periphery of the deformation hole; The expansion pipe is in an initial shape, and the flexible membrane is folded in the deformation hole.

13. The blood pump of claim 1, wherein, The impeller comprises a hub and blades arranged on the hub, and the blades are located in the expansion pipe; wherein, The deformation hole has a first length extending along the axial direction of the pump shell, and the blade has a second length extending along the axial direction of the pump shell, the first length is greater than the second length, and the two ends of the deformation hole extend beyond the two ends of the blade; And / or, the blade is completely accommodated in the expansion pipe, and the proximal end of the blade and the proximal end of the expansion pipe are spaced apart by a first distance along the axial direction of the pump shell, and the distal end of the blade and the distal end of the expansion pipe are spaced apart by a second distance along the axial direction of the pump shell.

14. The blood pump of any one of claims 1 to 8, characterized in that The expansion pipe comprises a first pipe segment, a second pipe segment, and a main pipe segment connected between the first pipe segment and the second pipe segment; in an expanded shape, the diameter of the first pipe segment gradually decreases along the direction from the distal end to the proximal end of the pump shell; the diameter of the second pipe segment gradually decreases along the direction from the proximal end to the distal end of the pump shell.

15. The blood pump of claim 1, wherein, The blood pump further comprises a driving unit, the driving unit comprising a housing and a rotating shaft connected with the impeller; the pump shell further comprises a proximal pipe connected with the proximal end of the expansion pipe, the proximal pipe is fixedly connected with the housing, and the proximal pipe is provided with the proximal opening; wherein, the pump shell further has at least one of the following characteristics: The proximal pipe is a non-deformable structure; The proximal pipe and the expansion pipe are an integral structure; The outer diameter of the expansion tube in the initial form is a constricted outer diameter D 2a , which is the same as the outer diameter of the proximal tube 2a . The outer diameter of the expansion tube in the expanded form is an expanded outer diameter D 2b The ratio of the expanded outer diameter D 2b to the outer diameter of the proximal tube is 1.1 to 1.

5.

16. The blood pump of any one of claims 1 to 8, characterized in that The pump shell further comprises a cannula assembly having a blood flow channel; the pump shell further comprises a distal pipe connected with the distal end of the expansion pipe, and the distal pipe is fixedly connected with the proximal end of the cannula assembly; wherein, the pump shell further has at least one of the following characteristics: The distal pipe is a non-deformable structure; The distal pipe and the expansion pipe are an integral structure; The outer diameter of the expansion tube in the initial form is a constricted outer diameter D 2a , which is the same as the outer diameter D7 of the distal tube 2a . The outer diameter of the expansion tube in the expanded form is an expanded outer diameter D 2b The ratio of the expanded outer diameter D 2b to the outer diameter D7 of the distal tube is 1.1 to 1.5.

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