CN114010937B

CN114010937B - Catheter pump and impeller and pump body thereof

Info

Publication number: CN114010937B
Application number: CN202111436271.8A
Authority: CN
Inventors: 齐献山; 张家良; 颜翊凡
Original assignee: Magassist Inc
Current assignee: Xinqing Medical Suzhou Co ltd
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-11-22
Anticipated expiration: 2041-11-29
Also published as: CN114010937A; CN115970150A; CN115779259A

Abstract

A conduit pump and its impeller and pump body are disclosed; the impeller can be accommodated in a pump shell of the catheter pump and comprises a hub and blades arranged on the hub; the blade is provided with a blade root arranged on the hub, a blade top far away from the hub and a reverse-folding part positioned between the blade root and the blade top; the blade root extends in a radial direction obliquely in a first circumferential direction towards the reflection portion, which extends in a radial direction obliquely in a second circumferential direction opposite to the first circumferential direction towards the tip of the blade.

Description

Catheter pump and impeller and pump body thereof

Technical Field

The present disclosure relates to the field of medical devices, and more particularly to a device for cardiac assist, and more particularly to a catheter pump and an impeller and a pump body thereof.

Background

An interventional catheter pump device (blood pump for short) can pump blood. Taking left ventricle assistance as an example, in the prior art, a pump of an interventional catheter pump device is generally disposed in a left ventricle of a subject, an impeller of the pump is driven to rotate by a flexible shaft, and the flexible shaft is driven by a motor to transmit power to the pump.

To ensure stable contraction and expansion, existing catheter pumps are capable of being inserted into a patient's blood vessel and expanded after insertion. During compression and expansion, the rotor (e.g., impeller) and the housing are typically deformed accordingly, and stability of the size of the lobe tip clearance (also known as pump clearance, i.e., the spacing gap between the radially outer end of the impeller and the inner wall of the pump body housing) is an important factor in the operational stability of the blood pump. Through simulation analysis, the size change of the external bracket (shell) of the pump body is small, and the largest influence on the top clearance is the change of the outer diameter of the impeller.

Along with the increase of the rotating speed, the outer diameter of the impeller can be continuously increased, the hydraulic performance can be rapidly improved due to the continuous increase of the outer diameter of the impeller, the increase of the diameter of the impeller can be reversely pushed due to the improvement of the hydraulic performance, the stable and efficient working range of the impeller is very small, and negative influence is generated on the efficiency of the pump.

Moreover, along with the increase of the rotating speed, the continuous increase of the outer diameter of the impeller easily exceeds the designed working point, so that the impeller and the bracket generate scraping, and the blood pump fails to work.

Disclosure of Invention

In view of the above-mentioned deficiencies, it is an object of the present disclosure to provide a duct pump, an impeller thereof, and a pump body capable of reducing an amount of change in an outer diameter of the impeller during operational rotation.

It is still another object of the present disclosure to provide a duct pump, an impeller thereof, and a pump body thereof, which can stably maintain a pump gap.

In order to achieve at least one of the above purposes, the invention adopts the following technical scheme:

an impeller for a catheter pump, the impeller being rotatable within a pump housing of the catheter pump, comprises a hub and blades provided on the hub. The blade has a blade tip, a blade root disposed on the hub, and a reverse fold portion between the blade root and the blade tip. The blade root extends in a radial direction obliquely in a first circumferential direction towards the reflection portion, which extends in a radial direction obliquely in a second circumferential direction opposite to the first circumferential direction towards the blade root of the blade. The first circumferential direction is opposite to the direction of rotation of the impeller.

Preferably, the impeller has a natural deployed state when not rotating and an operating state when rotating corresponding to a maximum operating speed. The impeller is switched from the naturally unfolded state to the working state, and the variation of the outer diameter of the blade tip (impeller outer diameter) is less than 0.5mm, preferably less than 0.3mm, and more preferably less than 0.1mm. Further, when the impeller is switched from the minimum working rotation speed to the maximum working rotation speed in the working state, the variation of the outer diameter of the blade tip is less than 0.3mm, and more preferably less than 0.1mm.

Preferably, the blade comprises a first portion located between the blade root and the reflection portion, and a second portion located between the reflection portion and the blade tip. The radial length La of the first portion is greater than 0.5 times the radial length of the second portion, preferably the radial length La of the first portion is greater than the radial length of the second portion.

Preferably, the blade comprises a first portion located between the blade root and the reflection portion, and a second portion located between the reflection portion and the blade tip. The vane has opposite concave upstream and convex downstream surfaces, and the maximum thickness of the second part is greater than 0.7 times the maximum thickness of the first part, and further the maximum thickness of the second part is greater than the maximum thickness of the first part. Wherein, the thickness direction is the normal direction of the contour line of the concave incident flow surface or the convex back flow surface on the cross section.

Preferably, the blade comprises a first portion located between the blade root and the reflection portion, and a second portion located between the reflection portion and the blade tip. The cross-sectional area of the first portion is more than 0.5 times, preferably more than 0.8 times the cross-sectional area of the second portion.

Preferably, in a cross-section of the blade, the blade comprises a first portion between the blade root and the inflected section, and a second portion between the inflected section and the blade tip. The tangent line of the reverse bending part passes through the circle center of the hub; the length of the first portion in the direction perpendicular to the tangent is more than 0.3 times, preferably more than 0.5 times the length of the second portion in the direction perpendicular to the tangent.

Preferably, the blade comprises a first portion located between the blade root and the inflection, a second portion located between the inflection and the tip; the blades are provided with concave flow-facing surfaces and convex flow-backing surfaces which are opposite; wherein, any point on the concave incident flow surface or the convex incident flow surface of the first part defines that the tangent of the any point has a tangent vector far away from the second part

The tangent line of any point has a contact point with the outer contour line of the hub, and the center of the hub is defined to have a ray vector facing the contact point

Tangential vector

And ray vector

The included angle beta therebetween is greater than 90 degrees and less than 180 degrees.

Preferably, the point on the concave or convex incident flow surface of the first part has a larger angle β closer to the inflection portion. Preferably, the blade root is provided with a circular arc transition between the concave inflow surface and the hub, and/or the blade root is provided with a circular arc transition between the concave inflow surface and the hub.

An impeller for a catheter pump, the impeller being receivable for rotation within a pump casing of the catheter pump, comprises a hub and blades provided on the hub. The blade is provided with a blade top, a blade root arranged on the hub and a reverse-folding part positioned between the blade root and the blade top. The blade root of the blade extends in a radial direction along a first circumferential direction opposite to the rotation direction of the impeller and slantly towards the inflection part on the cross section with the largest outer diameter of the blade; the turnback portion extends obliquely in a radial direction toward the tip of the blade in a second circumferential direction opposite to the first circumferential direction.

An impeller for a catheter pump, the impeller being rotatably receivable within a pump housing of the catheter pump; the impeller includes a hub and blades disposed on the hub. The blade top is provided with a blade root arranged on the hub. When the impeller is switched from the minimum working rotating speed to the maximum working rotating speed in the working state, the variation of the outer diameter of the blade top is smaller than 0.3mm. Furthermore, the variation of the outer diameter of the blade tip is less than 0.1mm.

A pump body of a catheter pump, the pump body having a blood outlet and a blood inlet, an impeller housed within the pump body and operable to rotate to pump blood from the blood inlet to the blood outlet; the pump body has a radially collapsed state adapted for intervention or delivery within a subject's vasculature, a naturally expanded state when the corresponding impeller is not rotating, and an operational state when the corresponding impeller is rotating. During the switching of the pump body from the naturally deployed state to the operating state, the impeller is configured such that its outer diameter varies by less than 0.5mm, preferably less than 0.3mm, and still more preferably less than 0.1mm.

Preferably, the impeller is configured such that its outer diameter remains the same or increases by less than 0.3mm.

Preferably, the pump housing includes a membrane defining a blood flow passage and a stent supporting the deployed membrane; the impeller is accommodated in the bracket; the stent is configured not to participate in causing elastic deformation and plastic deformation of the graft film during switching of the pump body from the naturally deployed state to the operating state, or the stent is configured not to participate in causing elastic deformation and plastic deformation of the graft film in the operating state of the pump body.

Preferably, the rate of increase of the outer diameter of the bracket does not exceed 1% during the switching of the pump body from the naturally deployed state to the operating state.

Preferably, in the process of switching the pump body from the natural expansion state to the working state, the deformation of the coating film does not exceed the elastic deformation limit thereof, or, in the working state of the pump body, the deformation of the coating film does not exceed the elastic deformation limit thereof.

Preferably, the impeller comprises a hub fixedly sleeved on the impeller shaft and blades arranged on the hub; the blade is provided with a blade root arranged on the hub and a blade top far away from the hub; a pump gap is defined between the blade top and the inner wall of the bracket; the pump gap has a gap width in the radial direction of less than 1.5mm.

Preferably, the gap width variation in the radial direction of the pump gap is less than 0.5mm during switching of the pump body from the naturally deployed state to the operating state.

Preferably, the pump body of the catheter pump comprises an impeller as described in any one of the above.

A catheter pump comprising: a motor, a drive shaft extending through the catheter and having a proximal end drivingly connected to the output shaft of the motor, and a pump body adapted to pump blood through the catheter and to deliver the pumped blood to a desired location in the heart. The pump body includes: an impeller and a pump casing which houses the impeller as in any of the above, or a pump body as in any of the above; the pump housing of the pump body is connected to the distal end of the catheter and the impeller is connected to the distal end of the drive shaft.

Adopt the scheme of this embodiment, the blade of the impeller of this embodiment utilizes the first portion that is located the inside of inflection portion to come the balanced radial expansion volume that is located the second portion in the inflection portion outside, through being equipped with the inflection portion and set up the radial diameter change that produces when the part of inside and outside different extending direction comes the balanced rotation, it makes impeller external diameter transition change to reduce the impeller because of the increase of rotational speed, can make the hydraulics performance of impeller remain stable, and then keep that the impeller can last stable high-efficient work when the work of operating speed within range.

The impeller of this embodiment has better outer diameter steady maintenance ability at work rotational speed within range outer diameter variation volume unchangeable or be located less variation range, makes the blood pump keep the stability of work in the rotational speed within range of broad, and the usable degree of performance and rotational speed improves the blood pump.

Drawings

FIG. 1 is a schematic perspective view of a catheter pump provided in accordance with an embodiment of the present disclosure;

FIG. 2 is a schematic view of the pump casing of FIG. 1;

FIG. 3 is a schematic view of a pump casing provided by another embodiment of the present disclosure;

FIG. 4 is a front view of FIG. 3;

FIG. 5 is a schematic view of the stent structure of FIG. 4;

FIG. 6 is a front view of FIG. 5;

FIG. 7 isbase:Sub>A cross-sectional view A-A of FIG. 6;

FIG. 8 is a perspective view of a bracket provided by another embodiment of the present disclosure;

FIG. 9 is a cross-sectional view of FIG. 8;

FIG. 10 is a partial schematic view of FIG. 1;

FIG. 11 is a schematic view of the bracket of FIG. 10 assembled with the impeller;

FIG. 12 is a schematic view of the impeller assembly of FIG. 10;

FIG. 13 is a perspective view of the impeller of FIG. 12;

FIG. 14 is a side view of FIG. 13;

FIG. 15 is a cross-sectional view of the pump body of FIG. 10;

fig. 16 isbase:Sub>A sectional view taken along linebase:Sub>A-base:Sub>A of fig. 15.

Description of reference numerals:

1. a power assembly; 2. a coupler; 3. a conduit; 4. a pump body; 5. a non-invasive support; 6. a distal bearing chamber; 106. A blood inlet; 320. a proximal bearing chamber; 310. a drive shaft; 355. an impeller shaft;

100. coating a film; 101. a tapered section; 102. coating the distal end of the membrane; 103. a cylinder section; 105. a blood outlet;

200. a support; 201. a carrier section; 202. a tapered stent proximal end; 203. a tapered stent distal end; 204. connecting the supporting legs; 2041. a rod body; 2042. a leg end; 205. connecting the secondary pipe; 210. connecting holes; 211. positioning buckles; 300. an anti-spreading element;

410. an impeller; 411. a blade; 412. a hub; 418. the head-on surface; 419. a back flow surface; A. a first portion; b. A second portion; d2, an external reverse-folding position point; d3, inward inflection position points; 450. a track circle; 4111. leaf tops; 4112. a blade root; 4113. an outer diameter-unchanged section; 4115. a transition line; 4116. a transition site; 4121. a hub proximal end; 4122. a hub distal end.

Detailed Description

In order to make those skilled in the art better understand the technical solutions in the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below with reference to the drawings in the embodiments of the present disclosure, and it is obvious that the described embodiments are only a part of the embodiments of the present disclosure, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments disclosed herein without making any creative effort, shall fall within the protection scope of the present disclosure.

It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a single embodiment.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein in the description of the disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

The terms "proximal", "distal" and "anterior", "posterior" are used herein with respect to a clinician operating an interventional catheter pump. The terms "proximal" and "posterior" refer to portions that are relatively close to the clinician, and the terms "distal" and "anterior" refer to portions that are relatively far from the clinician. For example, the extracorporeal portion is proximal and posterior, and the interventional intracorporeal portion is distal and anterior.

The catheter pump provided by the embodiment of the invention is used for assisting in heart failure, and can pump blood to the heart to realize partial blood pumping function of the heart. In a scenario suitable for left ventricular assist, a catheter pump pumps blood from the left ventricle into the aorta, providing support for blood circulation, reducing the workload of the subject's heart, or providing additional continuous pump hemodynamic support when the heart pump capacity is insufficient.

Of course, the catheter pump may also be introduced into other target locations of the subject, such as the right ventricle, blood vessels, or other organs, as desired, by interventional procedures.

Referring to fig. 1 and 2, a catheter pump according to an embodiment of the present disclosure includes a power assembly 1 and a working assembly. The power assembly 1 includes a housing and a motor accommodated in the housing and having an output shaft, and the working assembly includes a guide tube 3, a drive shaft 310 inserted into the guide tube 3, and a pump body 4.

The pump body 4 is deliverable through the catheter 3 to a desired location of the heart, such as the left ventricle for pumping blood, and includes a pump housing having a blood inlet 106 and a blood outlet 105, and an impeller 410 housed within the pump housing. The motor is provided at the proximal end of the catheter 3, is connected to the catheter 3 through the coupler 2, and drives the impeller 410 to pump blood by rotating the drive shaft 310. The pump housing of the pump body 4 is connected to the distal end of the guide tube 3, and the impeller 410 is connected to the distal end of the drive shaft 310.

The pump housing includes a cover 100 defining a blood flow passage, and further includes a stent 200 for supporting the deployed cover 100, with a proximal end of the stent 200 being connected to a distal end of the catheter 3. The proximal end of the stent 200 is provided with a connection sub-tube 205, and the connection sub-tube 205 is provided with a connection hole 210 constituting a female buckle, thereby forming a mechanical connection structure of a snap-fit type with the catheter 3.

The blades 411 are made of flexible elastic materials, and store energy when being folded, and after the external constraint is removed, the stored energy of the blades 411 is released, so that the blades 411 are unfolded. The number of the blades 411 is plural, and the plurality of blades 411 are uniformly arranged in the circumferential direction.

As shown in fig. 12-14, the blades 411 are disposed closer to the distal end 4122 on the hub 412. The blade 411 has a section 4113 with constant outer diameter. The blades 411 have a leading edge (first water inlet edge) and a trailing edge (second water inlet edge) at both ends in the axial direction, respectively. The constant outer diameter section 4113 is located between the leading edge and the trailing edge and extends curvilinearly between the leading edge and the trailing edge. The outer diameter of the outer diameter-unchanged section 4113 is the maximum outer diameter of the blade 411. The section 4113 with constant outer diameter and the leading edge and the trailing edge respectively have a transition portion 4116, and the transition portion 4116 may be a rounded structure. The constant outer diameter section 4113 extends over 0.5 times, even over 0.8 times the length of the blade 411. The outer invariant segment has a transition line 4115 at both ends. The tip 4111 has a tip edge that extends curvilinearly in the axial direction. The edge of the tip 4111 extends between the leading edge (leading edge) and the trailing edge (trailing edge). When the blade 411 rotates, the blade tip 4111 (blade tip) forms a circular trajectory (trajectory circle 450), and the outer diameter of the impeller 410, the outer diameter of the blade tip 4111, or the diameter of the blade tip 4111 is the diameter of the circular trajectory.

As shown in fig. 10-16, the impeller 410 can be housed for rotation within a pump housing of a catheter pump. The impeller 410 includes a hub 412 and blades 411 provided on the hub 412. The blade 411 has a blade root 4112 disposed on the hub 412, a blade tip 4111 away from the hub 412, and a reverse fold D2D3 between the blade root 4112 and the blade tip 4111 (blade tip). The blade root 4112 of the blade 411 extends radially in the first circumferential direction obliquely towards the inflection D2D3. The turnback D2D3 extends obliquely toward the blade tip 4111 of the blade 411 in a second circumferential direction opposite to the first circumferential direction in the radial direction. The first circumferential direction is opposite to the rotation direction of the impeller 410. The second circumferential direction is the same as (parallel to) the rotational direction of the impeller 410.

As shown in fig. 16, the vane 411 has an opposite concave incident flow surface 418 and an opposite convex back flow surface 419, the incident flow surface 418 of the vane 411 is concave, and the back flow surface 419 is convex. The blade 411 has at least one cross section (a section perpendicular to the axial direction) which is a C-shaped structure. In this cross section, the blade root 4112 of the blade 411 extends radially in a first circumferential direction obliquely to the inflection D2D3. The turnback D2D3 extends obliquely in the radial direction toward the tip 4111 of the blade 411 in a second circumferential direction opposite to the first circumferential direction.

In the cross-section where the vane 411 has the largest outer diameter. The cross-section is taken from the constant outer diameter section 4113. Preferably, any cross section of the section 4113 with constant outer diameter has a reverse folding portion D2D3, and the reverse folding portion D2D3 forms corresponding reverse folding position points D2 and D3 on the inner and outer surfaces (inner and outer contours). The inflection portion D2D3 forms a continuous outer inflection line consisting of the outer inflection point D2 on the back flow surface 419, and a continuous inner inflection line consisting of the inner inflection point D3 on the incident flow surface 418. The blade root 4112 of the blade 411 extends radially in the first circumferential direction obliquely to the inflection D2D3. The turnback D2D3 extends obliquely in the radial direction toward the tip 4111 of the blade 411 in a second circumferential direction opposite to the first circumferential direction.

The blade 411 comprises a first portion a between the blade root 4112 and the inflection D2D3, and a second portion B between the inflection D2D3 and the blade tip 4111. The first part a and the second part B extend entirely in the radial direction, and the circumferential extension directions are opposite.

As a result of research by the inventors, when the impeller 410 rotates, the first portion a and the second portion B of the impeller are subjected to a centrifugal force due to rotation, and a plurality of forces such as a reaction force given to the blades 411 by the fluid and a fluid back pressure, and the effects generated by the first portion a and the second portion B are different due to the fact that the first portion a and the second portion B extend in opposite directions in the circumferential direction under the combined action of the plurality of forces (common forces). Wherein the second portion B, which is radially outward of the first portion a, expands radially outward to some extent under the common force, such that the impeller 410 has a tendency to increase in diameter. The first portion a, which is located radially inward of the second portion B, contracts radially inward to some extent under the common force, so that the vane 411 has a tendency to decrease in diameter.

The reaction force (resistance) given to the blade 411 by the fluid is a main force, the first circumferential direction in which the first portion a extends is substantially parallel to the direction of the reaction force, and the reaction force acts on the first portion a to press the first portion a down toward the hub 412, thereby promoting the first portion a to move toward the hub 412 and forming a contraction tendency. The second circumferential direction in which the second portion B extends is generally opposite to the direction of a reaction force which, when acting on the second portion B, pushes the second portion B rearwardly so that it expands outwardly, causing the second portion B to expand radially, tending to expand.

Therefore, the vane 411 of the impeller 410 of the present embodiment utilizes the first portion a located inside the reverse folding portion D2D3 to balance the radial expansion amount of the second portion B located outside the reverse folding portion D2D3, and utilizes the reverse folding portion D2D3 to provide portions with different extending directions inside and outside to balance the radial diameter change generated during rotation, so as to reduce the transitional change of the outer diameter of the impeller 410 due to the increase of the rotation speed of the impeller 410, so that the hydraulic performance of the impeller 410 can be kept stable, and further, the impeller 410 can be kept to continuously, stably and efficiently operate when operating within the operating rotation speed range.

The impeller 410 has the advantages that the variation of the outer diameter is kept unchanged or is within a small variation range within the working rotating speed range, and the impeller has good outer diameter stability keeping capability, so that the blood pump keeps working stability within a wide rotating speed range, the performance is linearly matched with the rotating speed, and the usability of the blood pump is improved.

In this embodiment, the outer diameter variation of the impeller 410 is small during the rotation, and thus the pump gap can be stably maintained during the operation of the catheter pump. Specifically, a pump gap is defined between the blade tip 4111 and the inner wall of the bracket 200. The pump gap has a gap width in the radial direction of less than 1.5mm.

The impeller 410 has a natural deployed state when not rotating and an operating state when rotating corresponding to a maximum operating speed. Wherein, impeller 410 switches to the operating condition from the natural development state, and the diameter variation of blade tip 4111 is less than 0.5mm, that is, the outer diameter variation of impeller 410 is within ± 0.5mm (the outer diameter increase is within 0.5mm, and the outer diameter decrease is within 0.5 mm). Preferably, the variation of the outer diameter of the impeller 410 is less than 0.3mm (± 0.3mm range), and further, the variation of the outer diameter of the impeller 410 is less than 0.1mm (± 0.1mm range).

It is noted that the above numerical values include all values of lower and upper values that are incremented by one unit from the lower limit value to the upper limit value, and that there may be an interval of at least two units between any lower value and any higher value.

For example, the variation of the outer diameter of the impeller 410 is illustrated to be within a range of ± 0.5mm, preferably within a range of ± 0.3mm, and more preferably within a range of ± 0.1mm, for the purpose of illustrating values such as +0.08, -0.05, -0.03, which are not explicitly enumerated above.

As described above, the example range of 0.1 as the interval unit cannot exclude the increase of the interval in an appropriate unit, for example, a numerical unit such as 0.01, 0.02, 0.03, 0.04, 0.05, etc. These are only examples of what is intended to be explicitly recited and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be explicitly recited in this specification in a similar manner.

Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. The use of "about" or "approximately" with a range applies to both endpoints of the range. Thus, "about 20 to about 30" is intended to cover "about 20 to about 30", including at least the endpoints specified.

For other definitions of numerical ranges appearing herein, reference is made to the above description and further description is omitted.

As shown in fig. 16, the (projected) length La of the first portion a in the radial direction is greater than 0.5 times the (projected) length Lb of the second portion B in the radial direction. That is, the radial length La of the first portion A is greater than 0.5 times the radial length of the second portion B, la > 0.5Lb. Preferably, the (projected) length La of the first portion a in the radial direction is longer than the (projected) length Lb of the second portion B in the radial direction.

In some embodiments, the thickness of the vanes 411 in the first portion a is greater than the thickness of the vanes 411 in the second portion B. The first portion a has a more stable self-structure than the second portion B, thereby enhancing the structural strength of the vane 411 to secure the fluid pumping efficiency. Whereas in this embodiment the maximum thickness of the second portion B is greater than 0.7 times the maximum thickness of the first portion a. The thickness direction is the normal direction of the contour line of the concave incident flow surface 418 or the convex back flow surface 419 on the cross section. Further, the maximum thickness of the second portion B is greater than the maximum thickness of the first portion a. Thus, the thickness of the second portion B is increased, so that the deformation resistance of the second portion B is increased, and the outward expansion degree is avoided, thereby stably maintaining the outer diameter of the impeller 410.

In order to balance the radial variation of the first portion a and the second portion B, the outer diameter of the impeller 410 is stably maintained, and the cross-sectional area of the first portion a is more than 0.5 times that of the second portion B. Preferably, the cross-sectional area of the first portion a is more than 0.8 times the cross-sectional area of the second portion B. The cross-sectional area of the first portion a is 1.2 times or less the cross-sectional area of the second portion B. By increasing the first portion a and decreasing the second portion B, the ratio of the first portion a to the second portion B is balanced, thereby balancing the radial variation of the first portion a and the second portion B.

Further, as shown in fig. 16, in a cross section of the blade 411, a tangent of the inflection portion D2D3 passes through a center O of the hub 412. The first part A being perpendicular to the tangent line OO ₂ A length H1 in the direction of the second portion B perpendicular to the tangent OO ₂ The length H2 in the direction is 0.3 times or more, preferably, H1 is 0.5 times or more of H2.

The convex back flow surface 419 has a location point D2 on a cross section of the impeller 410. Tangent line OO of the point ₂ Through the centre O of the hub 412, wherein the cross-section of the blade 411 lies on the tangent line OO ₂ Or a straight line passing through the point and the center of the hub 412 is defined, wherein (all of) the cross section of the blade 411 is located on one circumferential side of the straight line. The position point D2 is located between the blade root 4112 and the blade tip 4111, and is an external inflection position point formed by the inflection portion D2D3 on the profile of the cross sectionD2。

As shown in FIG. 16, at any point on the concave incident flow surface 418 or the convex incident flow surface 418 of the first portion A, the tangent defining the any point has a tangent vector in a direction away from the second portion B

The tangent of the arbitrary point has a contact point with the outer contour of the hub 412, and defines the center of the hub 412 with a radial vector toward the contact point

Tangent vector

And ray vector

The included angle β between the concave incident flow surface 418 and the convex incident flow surface 418 of the first portion a is larger as the position point is closer to the inflection portion D2D3 than the included angle β of 90 degrees and less than 180 degrees.

The blade root 4112 may have a radiused transition between the concave upstream surface 418 and the hub 412, and/or the blade root 4112 may have a radiused transition between the concave upstream surface 418 and the hub 412. Wherein the radius of curvature of the circular arc transition is smaller than the radius of curvature of the first portion a.

Bearing in mind the above description, impeller 410 is an impeller 410 that is operable to rotate within the pump housing to pump blood from blood inlet 106 to blood outlet 105. The pump body 4 has a radially collapsed state suitable for intervention or delivery within a subject's vasculature, a naturally expanded state when the corresponding impeller 410 is not rotating, and an operational state when the corresponding impeller 410 is rotating.

Wherein, in the process of switching the pump body 4 from the naturally deployed state to the operating state, the impeller 410 is configured such that the variation of the outer diameter thereof is less than 0.5mm. That is, the outer diameter of the impeller 410 varies within ± 0.5mm. Preferably, the impeller 410 is configured to have a variation of the outer diameter thereof of less than 0.3mm, and further, the impeller 410 is configured to have a variation of the outer diameter thereof of less than 0.1mm. The impeller 410 is configured such that its outer diameter remains the same or increases by less than 0.3mm.

Further, the operating state of the impeller 410 may be the operating state at the maximum operating speed (maximum speed). As such, in the process of switching the pump body 4 from the naturally deployed state (the impeller 410 is stationary) to the maximum rotation speed operating state, the impeller 410 is configured such that the amount of change in the outer diameter (outer diameter) thereof is less than 0.5mm.

In the present embodiment, the pump casing has a small change in the inner diameter during the operational rotation of the impeller 410, and the outer diameter of the mount 200 does not increase by more than 1% during the switching of the pump body 4 from the naturally deployed state to the operational state. Specifically, in the process of switching the pump body 4 from the naturally deployed state to the operating state, the deformation of the film 100 does not exceed the elastic deformation limit thereof, or, when the pump body 4 is in the operating state, the deformation of the film 100 does not exceed the elastic deformation limit thereof.

Bearing in mind the above description, the pump housing includes a cover 100 defining a blood flow channel and a stent 200 for supporting the deployed cover 100. The tip 4111 gap is located between the edge of the tip 4111 of the impeller 410 and the inner wall of the foldable support 200. In other embodiments, the stent 200 is integrated with the graft 100, such as a helical support integrated within the graft 100, with She Dingxi (pump gap) between the inner wall of the graft 100 and the tip 4111.

In the process of switching the pump body 4 from the naturally unfolded state to the working state, the variation of the gap width H3 of the pump gap in the radial direction is less than 0.5mm, and further less than 0.3mm. Specifically, the outer diameter of the impeller 410 does not increase more than 0.3mm from a stationary rotation to a maximum operating speed. The impeller 410 has an outer diameter varying by 0.3mm within an operating rotational speed range (e.g., 10000 to 30000 rpm). When the impeller 410 rotates at the lowest operating rotational speed (10000 rpm) to the highest operating rotational speed (30000 rpm), the variation of the outer diameter of the impeller 410 is within 0.3mm, and further, the variation of the outer diameter of the impeller 410 is within 0.1mm, so as to stabilize the pump gap.

In this embodiment, the stent 200 may be disposed within the cover 100 or disposed outside the cover 100. The impeller is housed within the stent 200 and within the graft 100, the stent 200 is supported at the distal end 102 of the graft 100, a portion of the stent 200 is located outside the distal end 102 of the graft 100, and another portion of the stent 200 is located within the graft 100.

When the stent 200 applies a deployment force to the stent graft 100, the stent graft 100 does not undergo elastic deformation or plastic deformation, and the stent graft 100 has a good deformation resistance. Furthermore, the shape is better maintained in the blood pumping process, and the impeller which is stably maintained in the shape is matched, so that the pump clearance is kept constant, and the pump efficiency is maintained to be in the best working efficiency.

The covering membrane 100 has a cylindrical section 103 as a main structure and a tapered section 101 located at a proximal end of the cylindrical section 103, and the proximal end of the tapered section 101 is sleeved outside the catheter 3 and fixed to the outer wall of the catheter 3. The catheter 3 is connected to the proximal end of the stent 200 by a proximal bearing chamber at its distal end, in which proximal bearings are provided for rotatably supporting the drive shaft 310. In one embodiment, the connecting sub-tube 205 directly forms the proximal bearing chamber and is positioned and secured to the proximal bearing by the retaining buckle 211.

The distal end of the support frame 200 is provided with a distal bearing chamber 6, and a distal bearing for rotatably supporting the distal end of the drive shaft 310 is provided in the distal bearing chamber 6. The support 200 maintains the spacing of the proximal bearing chamber 320 and the distal bearing chamber 6, thereby providing stable rotational support for the drive shaft 310. The driving shaft 310 includes a flexible shaft passing through the catheter 3 and a hard shaft 355 (impeller shaft 355) connected to the distal end of the flexible shaft, the hub 412 of the impeller 410 is fitted over the hard shaft 355, and the proximal end and the distal end of the hard shaft 355 are respectively passed through the proximal bearing and the distal bearing. The rigid shaft 355 and the bearings at both ends provide a stable strength support for the impeller in the pump casing, maintaining the position of the impeller in the pump casing stable.

The coupler 2 is connected with the near end of the guide tube 3, a liquid flow passage is arranged between the guide tube 3 and the flexible shaft, and perfusion liquid input through the liquid flow passage can provide lubrication for the rotation of the flexible shaft and avoid the heat generation of rotation friction. The coupler 2 is provided with a perfusate input part 20 communicated with the liquid flow channel, and the perfusate input part 20 is communicated with the liquid flow channel. The distal end of the coupler 2 is provided with a retaining sleeve 260 for the catheter 3 to pass through, and the retaining sleeve 260 may serve to fix the catheter 3.

The distal end of distal end bearing room 6 is connected with does not have wound support piece 5, it is a flexible pipe body structure to not have wound support piece 5, it is circular-arc or the flexible arch of coiling form to represent for the tip, thereby it supports on the ventricle inner wall with the mode of not having wound or not damaged to not have wound support piece 5, separate the blood import 106 and the ventricle inner wall of the heart chamber of the pump body 4, avoid the pump body 4 to make the suction inlet laminating of the pump body 4 on the ventricle inner wall because the reaction force of blood in the course of the work, guarantee the effective area of pump suction.

The pump housing includes a radially collapsed state adapted for intervention or delivery within a subject's vasculature, a natural deployed state when the corresponding impeller is not rotating, and an operational state when the corresponding impeller is rotating. In the process of switching the pump casing from the radially collapsed state to the naturally expanded state, or in the process of switching from the naturally expanded state to the operating state, the deformation of the coating film 100 does not exceed the plastic deformation limit thereof.

Bearing the above description, the pump housing includes a cover 100 defining a blood flow channel and a stent 200 supporting the deployed cover 100. The impeller 410 is housed within the holder 200. During the switching of the pump body 4 from the naturally deployed state to the operating state, the stent 200 is configured not to participate in causing elastic deformation and plastic deformation of the coating film. Alternatively, the pump body 4 is in the operating state, and the stent 200 is configured not to participate in causing elastic deformation and plastic deformation of the graft film 100.

The pump body 4 has an intervention configuration and an operating configuration. In the intervention configuration of the pump body 4, the pump housing and the impeller are radially collapsed, such that the pump body 4 is inserted into or delivered within the vasculature of a subject at a first outer diameter dimension. In the corresponding operating configuration of the pump body 4, the pump casing and the impeller are in a radially expanded condition, so that the pump body 4 pumps blood at a desired location with a second outer diameter dimension greater than the first outer diameter dimension.

The pump body 4 includes a radially collapsed state and a radially expanded state, and the pump housing is operable to be switched between the radially collapsed state and the radially expanded state. The cover 100 does not plastically deform when the pump casing is in a radially expanded state, as compared to an unstressed state.

The pump shell which can be folded is arranged, so that the pump shell has smaller folded size and larger unfolded size, the pain of a testee is relieved in the process of intervention/delivery, the intervention is easy, and the requirement of large flow is met.

The multi-mesh, and in particular diamond-shaped mesh design of the stent 200 allows for superior folding while allowing for deployment with the memory properties of nitinol. The blades are made of flexible elastic materials, energy is stored when the blades are folded, and the stored energy of the blades is released after external restraint is removed, so that the blades are unfolded.

The pump shell is folded by means of external constraint, and the pump shell is self-unfolded after the constraint is removed. The application of the external restraint described above is accomplished by a folded sheath (not shown) that is slidably fitted over the catheter 3. When the folding sheath pipe moves forwards outside the catheter 3, the pump shell can be integrally contained in the folding sheath pipe, so that the pump shell is forcibly folded. When the folded sheath moves backwards, the radial constraint on the pump shell disappears, and the pump shell self-unfolds.

As described above, the pump case is folded by the radial constraint force exerted by the folded sheath tube, and the impeller included in the pump case is housed in the pump case. Thus, in essence, the collapsing process of the pump housing is: the folding sheath pipe exerts radial constraint force on the pump shell, and when the pump shell is compressed in the radial direction, the radial constraint force is exerted on the impeller.

That is, the pump casing is folded directly under the action of the folding sheath tube, and the impeller is folded directly under the action of the pump casing. As described above, the impeller has elasticity. Therefore, although in the folded state, the impeller is folded to store energy so that the impeller always has the tendency of radial expansion, and then the impeller is contacted with the inner wall of the pump shell and applies reaction force to the pump shell.

After the constraint of the folding sheath is removed, the pump shell supports the elastic coating film 100 to be unfolded under the action of the self memory characteristic, and the impeller is automatically unfolded under the action of released energy storage. In the deployed state, the outer diameter of the impeller is smaller than the inner diameter of the pump casing.

Thus, the radially outer end of the impeller (i.e., the tip of the blade) is spaced from the inner wall of the pump casing (specifically, the inner wall of the carrier 200), which is the pump clearance. The presence of the pump gap allows for unimpeded rotation of the impeller without wall impingement.

Furthermore, it is desirable that the pump gap size be of a small value and maintained for hydrodynamic considerations. In this embodiment, the outer diameter of the impeller is slightly smaller than the inner diameter of the bracket as the bracket 200, so that the pump gap is as small as possible while satisfying that the impeller rotates without hitting the wall. The main means for maintaining the pump gap is the supporting strength provided by the stent 200 and the expansion deformation resistance of the cover film 100, which can resist the action of the blood back pressure without excessive deformation, and the shape of the pump housing is kept stable, so that the pump gap is also stably maintained.

In order to ensure the toughness of the film 100, a more stable pump clearance is provided, the pump efficiency is stabilized, and the stress of the critical point of the plastic deformation limit of the film 100 is greater than or equal to the force applied to the film 100 by the blood backpressure caused by the rotation of the impeller when the pump body is in the maximum working condition. The maximum operating condition of the pump body corresponds to the maximum rotational speed at the rated power of the impeller. At this time, the pump flow rate corresponds to the maximum value, and the blood back pressure is also at the maximum value.

In this embodiment, the maximum value of the blood back pressure still does not exceed the critical point stress of the plastic deformation limit of the film 100, and further, in the operating state of the rotation of the impeller, the film 100 still does not exceed the plastic deformation limit, so as to reduce the change of the pump gap and stabilize the pump efficiency.

Further, during the switching of the pump casing from the radially collapsed state to the naturally expanded state, the deformation of the cover film 100 does not exceed its elastic deformation limit. During the switching of the pump casing from the naturally expanded state to the operating state, the deformation of the coating film 100 does not exceed its elastic deformation limit.

The stress at the critical point at which the film 100 is elastically deformed is equal to or greater than the force applied to the film 100 by the blood back pressure due to the rotation of the impeller when the pump body 4 is in the maximum operating condition. Thus, when the impeller stops rotating or the fluid back pressure disappears, the film 100 can still be restored to the initial state by the elasticity, the pump efficiency is stable, and the service life is longer.

It should be understood that the deformation of the film 100 in the present invention refers to the circumferential length deformation of the film 100, and the deformation may include flattening of wrinkles, and may also include elastic deformation or even plastic deformation. When subjected to a radial force, the film 100 is deformed so that the circumferential length (circumferential length) becomes large.

In the process of switching the pump case from the naturally expanded state to the operating state, the diameter of the coating film 100 is increased by not more than 1mm, and the diameter increase rate is not more than 5%, and further, not more than 3%. Thereby, the expansion deformation of the film 100 under the fluid back pressure does not exceed its plastic deformation limit, and the pump gap is stably maintained in cooperation with the impeller 410.

During the switching of the pump casing from the naturally deployed state to the operating state, the stent is configured not to participate in causing the deformation of the covering membrane 100. Alternatively, the stent is configured not to participate in causing deformation of the covering film 100 in the operating state of the pump housing. The deformation includes elastic deformation and plastic deformation. That is, the stent does not participate in causing either plastic deformation of the cover film 100 or elastic deformation of the cover film 100 during switching of the pump casing from the naturally expanded state to the operating state.

In the naturally deployed state, the inner diameter of the cover 100 is equal to or slightly larger than the outer diameter of the stent. For example, the diameter of the cover 100 is 1 to 1.1 times the outer diameter of the stent. Thus, the entire process from the collapsed state to the expanded state, the expanded stent graft 100 does not reach or exceed its own original shape (original diameter) due to radial expansion of the stent. Thus, the stent does not cause circumferential stretching of the cover 100. It will be appreciated that the stent is configured to not participate in causing deformation of the stent 100 because the stent 100 does not elastically or plastically deform in its naturally expanded state.

In the present embodiment, the material of the coating film 100 is TPU (thermoplastic polyurethane elastomer rubber), PEBAX (polyethylene elastomer), or PTFE (polytetrafluoroethylene). Preferably, the film 100 is made of a block polyether amide resin material such as PEBAX. The film 100 has no loss of mechanical properties under repeated deformation and is fatigue resistant, possessing good spring back and elastic recovery properties and precise dimensional stability. And further, the deformation cannot exceed the plastic deformation limit or the elastic deformation limit under the action of the fluid back pressure, and the pump clearance is stably kept.

The distal end of the holder 200 is formed with a plurality of legs 204 having a generally T-shaped configuration, the legs 204 being disposed between a generally vertical stem 2041 and a leg end 2042. The outer wall of the distal bearing chamber 6 is provided with a receiving groove comprising a plurality of axial grooves extending substantially axially and a circumferential groove communicating with the distal ends of the plurality of axial grooves. The rods 2041 are respectively inserted into the corresponding axial grooves, and the leg ends 2042 are inserted into the circumferential grooves. The outer cover of distal end bearing room 6 still establishes the hoop cover of tightly wrapping up the landing leg 204 fixedly in order to prevent it from accomodating the groove and popping out, and the hoop cover can form for the pyrocondensation pipe after the heating to will connect landing leg 204 and tie on distal end bearing room 6 outer wall, realize the anticreep of the two fixed.

The stent 200 has a support portion that contactingly supports the covering membrane 100. In the naturally deployed state, at least a portion of the support is in contact with the cover film 100. In the operating state, at least part of the support part is detached from the cover film 100.

Specifically, in the pump casing, when the impeller rotates to drive blood to flow, the film 100 is partially flattened by the fluid back pressure, or is elastically or plastically deformed, and the inner diameter is increased to be separated from the support portion. And under the obdurability of the coating 100, the deformation increase rate is limited, even if elastic deformation or plastic deformation occurs to cause the coating 100 to extend in the circumferential direction, the change of the extension rate is less than 3%, the change of the circumferential extension is small, and further, the interval gap between the impeller and the coating 100 can be maintained in a working state, so that the continuous stability of the pump effect is maintained.

The stent 200 comprises a generally conical stent proximal end 202 and a stent distal end 203, and a generally cylindrical stent segment 201 located between the stent proximal end 202 and the stent distal end 203. Wherein at least part of the axial length of the carrier section 201 constitutes a support. The distal end of the covering membrane 100 is sleeved outside the stent section 201 and is supported by the stent section 201 in a contact manner to construct a stable cylindrical pump shell. The distal end face of the cover 100 does not extend beyond the stent segment 201.

During the transition of the pump casing from the radially collapsed state to the radially expanded state, relative movement between the struts and the cover 100 is permitted, and the location where the cover 100 makes contact with a strut, such as the stent segment 201, is permitted to change. The relative position of the stent 200 and the cover film 100 is fixed and does not change.

The supporting portion and the film 100 are only supported in contact without fixed connection, and thus a certain degree of relative movement is formed between the supporting portion and the film 100 during the unfolding process of the film 100, thereby realizing the desired unfolding of each other. Moreover, the supporting portion provides circumferential supporting force for the covering membrane 100 without providing radial and circumferential relative movement constraints, and allows the covering membrane 100 to generate radial or circumferential relative movement relative to the supporting portion, so that the contact part of the covering membrane 100 and the supporting portion or the stent is changed in the unfolding process.

When the impeller rotates to drive blood to flow, the diameter of the stent graft 100 is increased mainly by the back pressure of blood, so that the stent graft 100 is separated from the stent 200 and does not contact with the stent 200, and the stent 200 loses the support of the stent graft 100 and does not participate in the deformation of the stent graft 100.

During the switching of the pump casing from the naturally deployed state to the operating state, the stent 200 is increased less in the radial direction than the cover 100. Specifically, the rate of increase in the outer diameter of the stent 200 is equal to or less than the rate of increase in the inner diameter of the stent 100, or the outer diameter increase of the stent 200 is smaller than the increase in the inner diameter of the stent 100. The rate of increase of the outer diameter of the bracket 200 during switching of the pump casing from the naturally deployed state to the operating state does not exceed 2%. Further, in the process of switching the pump casing from the naturally deployed state to the operating state, the rate of increase in the outer diameter of the bracket 200 does not exceed 1%.

In a possible embodiment as shown in fig. 3 to 9, the pump housing is further provided with an anti-expansion element 300 for limiting the radial expansion of the stent 200, in order that the stent does not participate in causing elastic or plastic deformation of the cover 100, limiting the amount of deformation of the stent 200 over the operating rotational speed range of the impeller. In the working state, the stent 200 with the anti-expansion element 300 is smaller in outer diameter than without the anti-expansion element 300.

In this embodiment, the natural deployed state of the stent 200 is constrained by the anti-expansion elements 300. That is, radial expansion of the stent 200 causes the expansion-resistant elements 300 to stretch. However, once the expansion-resistant element 300 is stretched to some extent, the stent reaches a maximum diameter when the stent can no longer be expanded.

The fluid backpressure affects the radial expansion of the anti-expansion element 300 and the stent 200, but is limited in its radial expansion amplitude, which is lower than that of the cover 100. In the operative condition, the anti-expansion element 300 limits the radial expansion of at least part of the support, causing it to separate from the covering membrane 100. In addition to the anti-expansion element 300, the anti-expansion element 300 restricts the stent 200 from increasing in the radial direction to a magnitude lower than that of the cover 100.

The diameter of the anti-expansion element 300 is smaller than the diameter of the cover film 100. The anti-expansion element 300 may be provided inside the stent or outside the stent. An anti-expansion element 300 is disposed around the stent 200 within the cover 100. Specifically, the anti-expansion element 300 is disposed around the stent segment 201.

The anti-expansion element 300 comprises a hoop secured around the stent section 201. The hoop may be welded or snap-fitted to the outside of the carrier section 201. As shown in the embodiment of fig. 3 to 7, a plurality of hoops are separately sleeved on the outside of the stent section 201. As in the embodiment shown in fig. 8 and 9, a single hoop (cuff) is centered over the stent section 201. The hoop is made of metal or other anti-expansion materials, the circumferential anti-expansion deformation capacity of the hoop is stronger than that of the stent, even stronger than that of the covering film 100, and further under the action of the anti-expansion element 300 in the working state, the radial increasing rate of the stent is smaller, so that the hoop is separated from the covering film 100 which is further expanded in the radial direction and does not contact with each other.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego such subject matter, nor should the inventors be construed as having contemplated such subject matter as being part of the disclosed subject matter.

Claims

1. An impeller for a catheter pump, the impeller being receivable within a pump housing of the catheter pump, comprising a hub and blades provided on the hub; the blade is provided with a blade top, a blade root arranged on the hub and a reverse-folding part positioned between the blade root and the blade top; the impeller has a natural deployed state when not rotating in which the blade root extends obliquely in a radial direction in a first circumferential direction toward the inflected section, and the inflected section extends obliquely in a radial direction in a second circumferential direction opposite to the first circumferential direction toward the blade tip.

2. The impeller of claim 1, wherein the impeller has an operating condition when rotating corresponding to a maximum operating speed; and the impeller is switched to a working state from the natural unfolding state, and the outer diameter of the blade is increased by less than 0.5mm.

3. An impeller according to claim 2 wherein the impeller switches from the naturally deployed state to the operational state, the outer diameter of the blades increasing by less than 0.3mm.

4. An impeller according to claim 2, wherein the impeller is switched from the naturally deployed state to the operational state, the outer diameter of the blades increasing by less than 0.1mm.

5. The impeller of claim 1, wherein the blade comprises a first portion between the blade root and the inflection, a second portion between the inflection and the tip; the radial length of the first portion is greater than 0.5 times the radial length of the second portion.

6. The impeller of claim 5, wherein the radial length of the first portion is greater than the radial length of the second portion.

7. The impeller of claim 1 wherein said blade includes a first portion between said blade root and said reverse fold, a second portion between said reverse fold and a blade tip; the maximum thickness of the second portion is greater than 0.7 times the maximum thickness of the first portion; the blades are provided with concave incident flow surfaces and convex back flow surfaces which are opposite to each other; the thickness direction is the normal direction of the contour line of the concave incident flow surface or the convex back flow surface on the cross section.

8. The impeller of claim 7, wherein the maximum thickness of the second portion is greater than the maximum thickness of the first portion.

9. The impeller of claim 1 wherein said blade includes a first portion between said blade root and said reverse fold, a second portion between said reverse fold and a blade tip; the cross-sectional area of the first portion is greater than 0.5 times the cross-sectional area of the second portion.

10. An impeller according to claim 9, wherein the cross-sectional area of the first portion is more than 0.8 times the cross-sectional area of the second portion.

11. The impeller of claim 1, wherein, in a cross-section of the blade, a tangent to the inflection passes through a center of the hub; the blade comprises a first part positioned between the blade root and the reverse fold, and a second part positioned between the reverse fold and the blade tip; the length of the first portion in the direction perpendicular to the tangent is 0.3 times or more the length of the second portion in the direction perpendicular to the tangent.

12. The impeller of claim 11, wherein the length of the first portion perpendicular to the tangential direction is more than 0.5 times the length of the second portion perpendicular to the tangential direction.

13. The impeller of claim 1, wherein the blade comprises a first portion between the blade root and the inflection, a second portion between the inflection and the tip; the blades are provided with concave flow-facing surfaces and convex flow-backing surfaces which are opposite;

wherein, any point on the concave upstream surface or the convex downstream surface of the first part defines that the tangent of the any point has a tangent vector far away from the second part

(ii) a The tangent vector

And the ray vector

14. An impeller according to claim 13, wherein a point on the concave flow-facing surface or convex flow-backing surface of the first portion has a larger angle of β closer to the turn-back.

15. An impeller according to claim 13, wherein the blade root is provided with a rounded transition between the concave upstream surface and the hub and/or the blade root is provided with a rounded transition between the convex downstream surface and the hub.

16. A catheter pump impeller, which is receivable within a pump housing of the catheter pump, comprising a hub and blades provided thereon; the blade is provided with a blade top, a blade root arranged on the hub and a reverse-folding part positioned between the blade root and the blade top; the impeller has a natural developed state when not rotating, in which the blade root extends obliquely in a radial direction toward the inflected section in a first circumferential direction opposite to the impeller rotation direction, and the inflected section extends obliquely in a radial direction toward the blade tip in a second circumferential direction opposite to the first circumferential direction, on a cross section where the blade has the largest outer diameter.

17. A catheter pump comprising:

a motor;

a conduit;

the driving shaft penetrates through the catheter, and the near end of the driving shaft is in transmission connection with the output shaft of the motor;

a pump body deliverable through the catheter to a desired location of a heart to pump blood, comprising: an impeller according to any one of claims 1 to 16 and a pump casing which houses the impeller; the pump housing is connected to the distal end of the catheter and the impeller is connected to the distal end of the drive shaft.