CN217724303U - Catheter assembly - Google Patents

Abstract

Disclosed herein is a catheter assembly including: the impeller comprises an impeller and a sleeve covered outside the impeller, wherein the sleeve comprises a covering film and a bag structure arranged at least at a position facing the impeller, and the bag structure comprises at least one filling cavity for providing supporting force and a filling flow channel for filling fluid into the filling cavity; the impeller can be expanded from a compressed state to an expanded state through axial tension energy, the sleeve can be radially expanded through the filling flow channel to fill the filling cavity with fluid, and a working gap is formed between the inner wall of the sleeve and the impeller. The catheter assembly provided by the present application can maintain a small radial dimension during transport and can be deployed to a desired location to reliably perform a blood pumping function.

Description

Catheter assembly

Technical Field

The present application relates to the technical field of medical equipment, in particular to a catheter assembly.

Background

The catheter assembly may serve as a temporary circulatory support system for the natural heart, and may be inserted into an artery of a patient and transported through the artery to the natural heart to assist in performing the blood pumping function of the natural heart, particularly when the natural heart is unable to provide sufficient oxygenated blood to the body.

The smaller the radial dimension of the catheter assembly is advantageous because the catheter assembly requires transport through the artery of the patient prior to formal use. When the catheter assembly reaches the designated location of the heart, it is desirable that the catheter assembly reliably perform the blood pumping function under the driving force provided by the driving means.

How to ensure that the catheter assembly reliably maintains a small radial dimension in the delivery state to facilitate transport; while returning to its original size in the operative state to reliably perform the blood pumping function is a direction that currently remains optimized for catheter assemblies.

SUMMERY OF THE UTILITY MODEL

In view of the above-mentioned deficiencies, it is an object of the present application to provide a catheter assembly that can be deployed to reliably perform a blood pumping function after a specified position has been reached while maintaining a small radial dimension in a shipping state.

The technical scheme is as follows:

a catheter assembly, comprising: the impeller comprises an impeller and a sleeve covered outside the impeller, the sleeve comprises a covering film and a bag structure arranged at least at a position facing the impeller, and the bag structure comprises at least one filling cavity for providing supporting force and a filling flow channel for filling fluid into the filling cavity;

the impeller can be expanded from a compressed state to an expanded state through axial tension, the sleeve can be radially expanded by filling fluid into the filling cavity through the filling flow channel, and a working gap is formed between the inner wall of the sleeve and the impeller.

In a preferred embodiment, the cannula has a distal end and a proximal end opposite to each other in an axial direction, the impeller is located at the distal end of the cannula, the axial length of the balloon structure is smaller than the axial length of the cannula, the membrane is provided downstream of the impeller, the impeller draws blood from the distal end toward the proximal end when rotating, and the membrane is inflated by positive pump pressure when the impeller rotates.

In a preferred embodiment, the balloon structures have an axial length substantially equal to the axial length of the cannula, the impeller being located at the proximal end of the cannula, adjacent balloon structures being connected by the membrane.

In a preferred embodiment, the cannula has axially opposite distal and proximal ends, and the first port of the inflation channel is adapted to communicate with a fluid source and the second port communicates with the inflation lumen nearest the distal end.

In a preferred embodiment, the bladder structure includes a plurality of inflation chambers in series and/or parallel communication with the inflation channel.

In a preferred embodiment, each of the filling chambers is directly communicated with the filling flow passage; or a plurality of filling cavities are communicated with each other, and the filling flow passage is communicated with at least one filling flow passage.

As a preferred embodiment, the inflation lumen of the balloon structure comprises any one of the following forms: a plurality of ring structures arranged along the axial direction at intervals, a structure arranged in a grid manner, and a structure arranged along the axial direction in a spiral manner.

As a preferred embodiment, the catheter assembly further comprises: a conduit, an axial operating mechanism at least partially disposed within the conduit, the conduit having a first end proximal to the sleeve and a second end distal from the sleeve, the impeller and the sleeve being received within the conduit when the axial operating mechanism is in a first state; when the axial actuator is transitioned from the first state to the second state, the impeller and the cannula extend from the catheter, and the impeller is deployed from the compressed configuration to the expanded configuration.

In a preferred embodiment, the conduit is a hollow tube, and a cavity communicated with the filling flow passage is arranged in the side wall of the tube; the axial operating mechanism comprises a sheath tube capable of moving axially, and the catheter is sleeved outside the sheath tube.

A catheter assembly, comprising: the impeller and a sleeve pipe covered outside the impeller; the impeller is expandable from a compressed configuration to an expanded configuration by axial tension; the cannula including a covering membrane, an expandable structure disposed at least in a position facing the impeller, the expandable structure having a collapsed state and an expanded state;

the cannula having opposite distal and proximal ends along an axial direction thereof, the impeller being located at the distal end of the cannula, the expandable structure having an axial length less than the axial length of the cannula, the covering membrane being disposed downstream of the impeller; blood is drawn out from the distal end to the proximal end when the impeller rotates, and the coating film is expanded by positive pressure output of the pump when the impeller rotates.

Has the advantages that:

one embodiment of the present application provides a catheter assembly that, during use, can maintain a small radial dimension during transport and then deploy to a desired position to reliably perform a blood pumping function.

Specifically, when the catheter assembly is delivered in an artery, the sleeve and the impeller are both accommodated in the catheter, and after the catheter assembly reaches the working position, the sleeve and the impeller can be driven by the axial operating mechanism to extend out of the sleeve. The impeller can be expanded from a compression state to an expansion state through axial tension by the axial tension provided by the axial operating mechanism, and in addition, the sleeve can support the filling cavity of the bag structure after filling fluid into the filling flow channel, so that the sleeve is radially expanded, a working gap is formed between the inside of the sleeve and the impeller, and the impeller is ensured not to interfere with the sleeve in the rotating process.

Specific embodiments of the present invention are disclosed in detail with reference to the following description and drawings, indicating the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the present invention are not limited in scope thereby.

Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments, in combination with or instead of the features of the other embodiments.

It should be emphasized that the term "comprises/comprising" when used herein, is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps or components.

Drawings

In order to illustrate the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.

FIG. 1 is a schematic structural view of a catheter assembly provided in accordance with an embodiment of the present application;

FIG. 2 is a top view of the catheter assembly of FIG. 1;

FIG. 3 isbase:Sub>A cross-sectional view A-A of the catheter assembly of FIG. 2;

FIG. 4 is a schematic structural view of a cannula of a catheter assembly provided in one embodiment of the present application;

FIG. 5 is a schematic cross-sectional view of the catheter of FIG. 3;

fig. 6 is a schematic structural view of a cannula of a catheter assembly provided in another embodiment of the present application.

Description of reference numerals:

1. an impeller; 2. a sleeve; 21. a distal end; 22. a proximal end; 3. coating a film; 4. a bladder structure; 41. filling the cavity; 42. filling a flow channel; 421. a second port; 5. a conduit; 51. a lumen; 6. a sheath tube; 7. a pigtail catheter; 8. and coupling the connector.

Detailed Description

In order to make the technical solutions in the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "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 represent the only embodiments.

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 invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Please refer to fig. 1, fig. 2, and fig. 3. The present specification provides a catheter pump, which mainly comprises: the impeller comprises an impeller 1 and a sleeve 2 which covers the impeller 1.

The cannula 2 comprises a coating 3, a capsule structure 4 arranged at least in a position facing the impeller 1. The capsule structure 4 includes at least one inflation chamber 41 for providing a supporting force, and an inflation channel 42 for inflating the inflation chamber 41 with a fluid. The impeller 1 can be expanded from a compressed state to an expanded state through axial tension, the sleeve 2 can be radially expanded by filling fluid into the filling cavity 41 through the filling flow passage 42, and a working gap is formed between the inner wall of the sleeve 2 and the impeller 1.

In this specification, the impeller 1 may comprise one or more blades. The one or more blades may be at least partially made of a deformable material. In particular, the deformable material may comprise an elastic material such that the impeller 1 may be switched between a compressed configuration and an expanded configuration. In addition, in order to ensure the stability of the impeller 1 during operation, the blades may be made of a plurality of materials such as a flexible material, a hard material, and a flexible material.

In the present specification, the sleeve 2 is mainly used as a pump housing of the catheter pump, and the inner wall of the sleeve 2 forms a receiving chamber for mounting the impeller 1 and circulating blood. The sleeve 2 may comprise: a cover 3 and a capsule structure 4 connected by the cover 3. The capsule structure 4 needs to be arranged at least opposite the impeller 1. After the sac structure 4 is filled with fluid through the filling flow passage 42, the filling cavity 41 can be supported, so that the sleeve 2 is radially expanded, a working gap is formed between the inside of the sleeve 2 and the impeller 1, and the impeller 1 is ensured not to interfere with the sleeve 2 in the rotation process.

The cannula 2 extends lengthwise along the axial direction as a whole, the cannula 2 having opposite distal and proximal ends 21, 22 along the axial direction. The distal end 21 and the proximal end 22 can refer to the direction of blood flow, and relatively speaking, along the direction of blood flow, the end at the upstream is the distal end 21, and the end at the downstream is the proximal end 22. Wherein, the impeller 1 can be located near the distal end 21 of the casing 2, the impeller 1 can be located near the proximal end 22 of the casing 2, and the impeller 1 can also be located at the middle of the casing 2.

In one embodiment, as shown in fig. 4, the impeller 1 is located near the distal end 21, and the balloon structure 4 is disposed in a position facing the impeller 1 for drawing blood from the distal end 21 toward the proximal end 22 when the impeller 1 is rotated.

In this embodiment, the axial length of the balloon structure 4 is smaller than the axial length of said cannula 2 when the impeller 1 is close to the distal end 21 of the cannula 2. The capsule structure 4 may be provided only at a position facing the impeller 1, and the other position may be a through-coating film 3. Since the penetrating coating 3 is located at a position downstream of the impeller 1 and in a positive pressure region, the positive pressure generated by the impeller 1 can be reliably spread out after the impeller 1 rotates, that is, the coating 3 expands by the positive pump pressure when the impeller 1 rotates, and therefore the reliability of the position in the operating state of the catheter pump is not affected. And after the capsule structure 4 is only arranged at the position facing the impeller 1, the outer diameter of the sleeve 2 is favorably reduced on one hand, and the difficulty of the manufacturing process and the manufacturing cost are favorably reduced after the distributed area of the capsule structure 4 is reduced on the other hand.

In other embodiments, the balloon structure 4 may be replaced with other inflatable forms, for example, the balloon structure 4 may be replaced with an inflatable structure. Correspondingly, the casing 2 comprises a coating 3, an expandable structure provided at least at a position facing the impeller 1, the expandable structure having a contracted state and an expanded state. The cannula 2 has opposite distal and proximal ends 21, 22 in the axial direction thereof, the impeller 1 is located at the distal end 21 of the cannula 2, the axial length of the expandable structure is smaller than the axial length of the cannula 2, and the coating 3 is provided downstream of the impeller 1; when the impeller 1 rotates, blood is drawn from the distal end 21 to the proximal end 22, and the coating 3 is expanded by positive pressure of a pump when the impeller 1 rotates.

In the present embodiment, the following differences from the above-described embodiment are: the bladder structure 4 is replaced with an inflatable structure to achieve the same technical effect as the bladder structure 4 embodiment described above. The expandable structure may in particular be a stent structure made of a memory alloy material, or possibly in other expandable forms.

In other embodiments, as shown in fig. 1, 2 or 3, the axial length of the balloon structure 4 is substantially equal to the axial length of the cannula 2, the impeller 1 is located at the proximal end of the cannula 2, and adjacent balloon structures 4 are connected by the cover membrane 3.

When the capsule structure 4 is arranged along the axial length of the casing 2, the axial length of the capsule structure 4 is substantially equal to the axial length of the casing 2, and specifically, the axial length of the capsule structure 4 may be at least 80% of the axial length of the casing 2. The balloon structures 4 may be centrally distributed in the sleeve 2. The impeller 1 may be disposed near the proximal end 22 to ensure that the length of the drive shaft connected to the impeller 1 is shortened as much as possible when the impeller 1 rotates, thereby ensuring the reliability of the impeller 1 in use.

In the present description, the bladder structure 4 mainly includes at least one inflation chamber 41 for providing a supporting force, and the inflation chamber 41 may be formed of a thin-walled material. Specifically, the material forming the bladder structure 4 is not specifically limited in this application.

In one embodiment, the bladder structure 4 may include a plurality of inflation chambers 41, and the inflation chambers 41 may be in communication with the inflation channel 42 in series and/or in parallel.

In this embodiment, the capsule structure 4 may include a plurality of filling cavities 41, and the filling cavities 41 may be connected in series with the filling channel 42 or in parallel with the filling channel 42; alternatively, a portion of charging chamber 41 may be in series communication with charging channel 42, and a portion of charging chamber 41 may be in parallel communication with charging channel 42. Specifically, a plurality of the filling chambers 41 communicate with each other, and the filling flow passage 42 communicates with at least one of the filling flow passages 42. Alternatively, in order to ensure high filling efficiency during filling, each filling chamber 41 is directly communicated with the filling flow passage 42.

In the present description, the inflation lumen 41 of the balloon structure 4 may include any one or a combination of the following: a plurality of ring structures arranged along the axial direction at intervals, a structure arranged in a grid manner, and a structure arranged along the axial direction in a spiral manner. Of course, the inflation lumen 41 may take other possible forms, and preferably, the particular form of the inflation lumen 41 of the balloon structure 4 may be selected to facilitate fluid ingress and egress.

In the present description, the filling channel 42 is mainly used to fill the filling chamber 41 with fluid, so that the sleeve 2 expands in the radial direction. Specifically, the filling channel 42 may be filled with a liquid, such as saline, or a gas, such as air.

In this specification, the catheter pump may further include: a conduit 5, an axial operating mechanism at least partially arranged inside said conduit 5.

In particular, the conduit 5 has a first end close to the casing 2 and a second end remote from the casing 2. When the axial operating mechanism is in a first state, the impeller 1 and the sleeve 2 are accommodated in the conduit 5; when the axial operating mechanism is switched from the first state to the second state, the impeller 1 and the cannula 2 are extended from the catheter 5, the impeller 1 being deployed from the compressed configuration to the expanded configuration.

As shown in fig. 5, in particular, the axial operating mechanism includes a sheath 6 capable of moving axially, and the catheter 5 is sleeved outside the sheath 6. When the sheath 6 is in the clamping state, the impeller 1 and the sleeve 2 are contained in the catheter 5, and the maximum size of the catheter pump is the outer diameter of the catheter 5; when the joe is in the release position, the impeller 1 and the cannula 2 extend from the catheter 5, the impeller 1 expanding from the compressed configuration to the expanded configuration.

Of course, the axial operating mechanism may be in other forms, and the specific application is not limited herein.

As shown in fig. 5, further, the conduit 5 is a hollow tube having a sidewall with a certain thickness, and a cavity 51 communicating with the filling channel 42 is formed in the sidewall. When it is desired to expand the sleeve 2, fluid may be injected into the inflation lumen 41 of the bladder structure 4 through the lumen 51, inflation channel 42, causing the sleeve 2 to expand radially.

In addition, the catheter pump may further include a motor for providing a rotational force, and a transmission mechanism for transmitting the rotational force of the motor to the impeller 1. Wherein, the transmission mechanism can comprise a driving shaft matched with the impeller 1, an output shaft matched with the motor, a coupling connector 8 which is arranged outside the output shaft and is matched with the guide pipe 5, and the like.

In one embodiment, the cannula 2 extends longitudinally along an axial direction in its entirety, the cannula 2 having opposite distal and proximal ends 21, 22 along the axial direction, the distal end 21 being provided with the pigtail catheter 7. The pigtail catheter 7 is arranged at the most far end 21 or the most front end of the whole catheter pump, and when the catheter pump is conveyed to the heart through an artery, the pigtail catheter 7 can be used for guiding to protect the inner wall of the artery.

In this description, the inflation channel 42 is provided with a first port for communicating with a fluid source, and a second port 421 for communicating with an inflation chamber, where the second port 421 may be an opening formed in one of the inflation chambers 41 of the bladder structure 4; in addition, at least one longitudinal flow channel may be disposed on the body of the sleeve 2, the flow channel may be in communication with the filling chamber 41, and the second port 421 may also be an opening formed on the flow channel. Of course, the specific location and arrangement of the second port 421 can be adjusted and arranged according to the relative fit relationship between the balloon structure 4 and the inflation channel 42 in the sleeve 2, and the application is not limited in this application.

Wherein the sleeve 2 extends lengthwise along the axial direction, and the sleeve 2 has a distal end 21 and a proximal end 22 opposite to each other along the axial direction, and the opening can be arranged at a position close to the distal end 21, or at a position close to the proximal end 22, or between the distal end 21 and the proximal end 22.

In one embodiment, as shown in fig. 6, the sleeve 2 extends lengthwise along the axial direction, the sleeve 2 has a distal end 21 and a proximal end 22 opposite to each other along the axial direction, and the second port 421 of the filling channel 42 is disposed closest to the distal end 21.

In this embodiment, when the second port 421 of the filling channel 42 is located near the distal end 21 and the cannula 2 is received in the catheter 5, the moving direction of the cannula 2 is opposite to the discharging direction of the fluid (air or saline, etc.), which is beneficial to efficiently discharge the fluid in the filling cavity 41 of the cannula 2 from the opening.

In a specific use scenario, when the catheter pump is used for delivering in an artery, the cannula 2 and the impeller 1 are both accommodated in the catheter 5, and after the catheter pump reaches the working position, the sheath 6 can be released, and the sheath 6 drives the cannula 2 and the impeller 1 to extend out of the cannula 2. The sheath 6 provides an axial tension force that enables the impeller 1 to expand from a compressed state to an expanded state through an axial tension force, and in addition, the sleeve 2 can support the filling cavity 41 of the capsule structure 4 after filling the filling flow channel 42 with fluid, so that the sleeve 2 radially expands, a working gap is formed between the inside of the sleeve 2 and the impeller 1, and the impeller 1 is ensured not to interfere with the sleeve 2 in a rotating process.

In general, the catheter pump provided by the application can keep a small radial size in a conveying state during use, and can be unfolded to reliably complete a blood pumping function after reaching a specified position.

Any numerical value recited herein includes all values from the lower value to the upper value, in increments of one unit, provided that there is a separation of at least two units between any lower value and any higher value. For example, if it is stated that the number of a component or a value of a process variable (e.g., temperature, pressure, time, etc.) is from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, it is intended that equivalents such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also expressly enumerated in this specification. For values less than 1, one unit is suitably considered to be 0.0001, 0.001, 0.01, 0.1. 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 that are explicitly recited in the specification in a similar manner are to be considered.

Unless otherwise indicated, all ranges are inclusive of 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.

All articles and references disclosed, including patent applications and publications, are hereby incorporated by reference for all purposes. The term "consisting essentially of 8230to describe a combination shall include the identified element, ingredient, component or step and other elements, ingredients, components or steps that do not materially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe combinations of elements, components, or steps herein also contemplates embodiments that consist essentially of such elements, components, or steps. By using the term "may" herein, it is intended to indicate that any of the described attributes that "may" include are optional.

A plurality of elements, components, parts or steps can be provided by a single integrated element, component, part or step. Alternatively, a single integrated element, component, part or step may be divided into separate plural elements, components, parts or steps. The disclosure of "a" or "an" to describe an element, ingredient, component or step is not intended to foreclose other elements, ingredients, components or steps.

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 will 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 a disclaimer of such subject matter, nor is it to be construed that the inventors do not consider such subject matter to be part of the disclosed inventive subject matter.

Claims (10)

1. A catheter assembly, comprising: the impeller comprises an impeller and a sleeve covered outside the impeller, the sleeve comprises a covering film and a bag structure arranged at least at a position facing the impeller, and the bag structure comprises at least one filling cavity for providing supporting force and a filling flow channel for filling fluid into the filling cavity;

the impeller can be expanded from a compressed state to an expanded state through axial tension, the sleeve can be radially expanded by filling fluid into the filling cavity through the filling flow channel, and a working gap is formed between the inner wall of the sleeve and the impeller.

2. The catheter assembly of claim 1, wherein the cannula has axially opposite distal and proximal ends, the impeller is located at the distal end of the cannula, the balloon structure has an axial length less than the axial length of the cannula, the membrane is disposed downstream of the impeller, the impeller draws blood from the distal end toward the proximal end when rotated, and the membrane is inflated by positive pump pressure when the impeller is rotated.

3. The catheter assembly of claim 1, wherein the balloon structure has an axial length substantially equal to an axial length of the sleeve, the impeller being located at a proximal end of the sleeve, adjacent balloon structures being connected by the covering membrane.

4. The catheter assembly of claim 1, wherein the cannula has axially opposed distal and proximal ends, a first port of the inflation channel for communication with a fluid source, and a second port in communication with an inflation lumen nearest the distal end.

5. The catheter assembly of claim 1, wherein the balloon structure includes a plurality of inflation lumens in series and/or parallel communication with the inflation channel.

6. The catheter assembly of claim 5, wherein each of the inflation lumens is in direct communication with the inflation channel, respectively; or a plurality of the filling cavities are communicated with each other, and the filling flow passage is communicated with at least one filling flow passage.

7. The catheter assembly of claim 1, wherein the inflation lumen of the balloon structure comprises any one of the following forms: a plurality of ring structures arranged along the axial direction at intervals, a structure arranged in a grid manner, and a structure arranged along the axial direction in a spiral manner.

8. The catheter assembly of claim 1, further comprising: a conduit, an axial operating mechanism disposed at least partially within the conduit, the conduit having a first end proximal to the sleeve and a second end distal to the sleeve, the impeller and the sleeve being received within the conduit when the axial operating mechanism is in a first state; when the axial actuator is transitioned from the first state to the second state, the impeller and the cannula extend from the catheter, and the impeller is deployed from the compressed configuration to the expanded configuration.

9. The catheter assembly as set forth in claim 8, wherein the catheter is a hollow tube having a lumen disposed in a sidewall thereof for communicating with the filling channel;

the axial operating mechanism comprises a sheath tube capable of moving axially, and the catheter is sleeved outside the sheath tube.

10. A catheter assembly, comprising: the impeller and a sleeve pipe covered outside the impeller; the impeller is expandable from a compressed configuration to an expanded configuration by axial tension; the cannula includes a covering membrane, an expandable structure disposed at least in a position facing the impeller, the expandable structure having a collapsed state and an expanded state;

the cannula having opposite distal and proximal ends along an axial direction thereof, the impeller being located at the distal end of the cannula, the expandable structure having an axial length less than that of the cannula, the cover being disposed downstream of the impeller; blood is drawn out from the distal end to the proximal end when the impeller rotates, and the coating film is expanded by positive pressure output of the pump when the impeller rotates.

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