CN117017404A

CN117017404A - Stent delivery system

Info

Publication number: CN117017404A
Application number: CN202311215235.8A
Authority: CN
Inventors: 刘香东
Original assignee: Juhui Medical Technology Shenzhen Co ltd
Current assignee: Juhui Medical Technology Shenzhen Co ltd
Priority date: 2023-09-19
Filing date: 2023-09-19
Publication date: 2023-11-10
Anticipated expiration: 2043-09-19
Also published as: CN117017404B

Abstract

The stent delivery system of the present application comprises a delivery catheter, a delivery device, and a stent loaded within the delivery catheter. Each open-loop supporting unit of the support body comprises a first wave ring and a second wave ring adjacent to the first wave ring, a supporting rod forming the first wave ring is thicker than a supporting rod forming the second wave ring, and a near-end developing part and a far-end developing part of the support are both arranged on the inner side of the support. The conveying device comprises a delivery guide wire and a distal spring sleeved at the distal end of the delivery guide wire. The distal spring penetrates the body of the stent, and the delivery guidewire cooperates with the proximal end of the distal spring to limit the proximal visualization structure of the stent. Defining the wall thickness of the stent as a, the inner diameter of the delivery catheter as B, and the diameters of the distal springs as C, A, B and C satisfy: a > B-2A-C > 0. The support rods of adjacent wave rings of the support can not be mutually extruded and piled in the conveying process.

Description

Stent delivery system

Technical Field

The application relates to the field of cardiovascular interventional medical instruments, in particular to a stent conveying system.

Background

Intracranial aneurysms are tumor-like projections on the wall of an intracranial arterial vessel that are formed by gradual expansion under the action of vascular dynamic loads and other factors due to abnormal changes in local blood vessels of the cerebral artery, which are the main causes of subarachnoid hemorrhage. The cerebral vasospasm can be induced after the rupture and bleeding of the intracranial aneurysm, and the symptom is usually generated 3-14 days after the bleeding of the subarachnoid space. Blood clots can irritate the walls of blood vessels, causing strong contractions of blood vessels, and severe persons can cause ischemic necrosis, coma, and hemiplegia in brain tissue. Intracranial aneurysms, which are manifested as headache and nausea, can occur in congenital arterial dysplasia, infection, arteriosclerosis, craniocerebral trauma, etc., and are often treated in a surgical manner.

Interventional therapy and surgical craniotomy are two major surgical modes of intracranial aneurysms. The interventional therapy is to release a metal spring ring made of special alloy materials from an artery into an aneurysm, so that thrombus is caused in the cavity, the purpose of embolizing the aneurysm is achieved, the blood flow impact pressure of the wall of the aneurysm can be relieved, and the hemostatic effect is achieved. However, the coil stability is low, resulting in poor surgical results.

Stent-assisted coil embolization is an important technique in intracranial aneurysm interventional embolization procedures. With the assistance of the stent, the intracranial wide-neck, tiny and fusiform aneurysms which can not be plugged densely even can not be plugged can obtain good treatment effect, the embolism proportion can be increased, the recurrence of the aneurysms can be prevented, and the healing can be promoted.

The stent mainly plays the following roles in the previous operation: 1. the aneurysm-carrying artery is protected, so that the spring ring can be well stuffed in the aneurysm, and postoperative cerebral infarction caused by stenosis and occlusion of the aneurysm-carrying artery is prevented; 2. the density of the tumor neck embolism is increased, and the spring ring can be plastic at the tumor neck according to the shape of the carrying tumor artery due to the blocking of the bracket, so that the aneurysm neck is completely covered, and the thrombosis and the healing are promoted; 3. changing the shape of the aneurysm-carrying artery, guiding blood flow, reducing blood flow from entering the aneurysm, and promoting healing; 4. stimulating the growth of angiogenic endothelium and promoting the healing of aneurysms.

The parent carrying artery for reconstructing the cerebral aneurysm is treated by implanting a vascular stent, and the reconstructed stent of the cerebral aneurysm must have the following characteristics: 1) The stent can be compressed and loaded into the inner cavity of the micro-conveyor, and the stent is soft enough to be conveyed to a target through tortuous, slim and complex cerebral vessels after compression; 2) The stent has enough compliance after implantation and conforms to tortuous cerebral vessels; 3) Stent meshes significantly affect the hemodynamics within an aneurysm while maintaining patency of the normal branch artery where the parent artery is covered by the stent. That is, a dedicated intracranial stent is required to have better flexibility. In order to increase the flexibility of the intracranial stent, a plurality of wave rings which are arranged along the length direction of the stent are often made of metal supporting rods in design in the industry, and the mesh area of each wave ring framework is larger.

Fig. 1 shows an intracranial stent 110 comprising a stent body 111, a proximal visualization structure 115, and a distal visualization structure 116. The holder body 111 includes a plurality of open loop support units 112. Each of the open-loop support units 112 includes a plurality of thick support rods 113 and a plurality of thin support rods 114, wherein the plurality of thick support rods 113 constitute a first wave ring and the plurality of thin support rods 114 constitute a second wave ring, and the first wave ring is adjacent to the second wave ring and alternately arranged in the axial direction of the stent body 111. The terms "thick" and "thin" are used herein in contrast to the width of the strut on the circumferential surface of the stent 110, rather than the thickness of the stent in the radial direction (i.e., the "wall thickness" of the stent, which is commonly known in the art). The number of thick support bars 113 is smaller than the number of thin support bars 114 in the circumferential direction of the support 110. Adjacent open loop support units 112 are connected using connecting rods (not shown).

Both the proximal visualization structure 115 and the distal visualization structure 116 are provided with a visualization element 117 as shown in fig. 2 for visualization under clinical X-rays, so as to facilitate the operator in knowing the position of the stent 110 within the vessel in real time. The developing member 117 is disposed at both the inner side and the outer side of the bracket 110. The outer side refers to a side of the stent 110 for direct contact with the wall of a blood vessel after being implanted in the blood vessel, and the inner side refers to a side of the stent 110 for passage of blood flow without direct contact with the wall of the blood vessel after being implanted in the blood vessel.

The main tool for implanting stents into intracranial arterial vessels is the delivery system. Prior to surgery, the stent has been preloaded into a particular location of the introducer sheath. During operation, a doctor firstly determines the position, shape and size of an aneurysm through an image method, and selects proper stent specifications according to related parameters; then, under the guidance of the image, a proper stent is conveyed into the micro-catheter through the guiding sheath and then conveyed to a lesion point through the micro-catheter; releasing the stent at the lesion point, supporting the vessel wall after the stent self-expands, reducing blood flow flowing into the aneurysm, inducing thrombosis in the aneurysm, promoting vascular endothelialization of the neck of the aneurysm, and occluding the aneurysm; finally, the delivery system is withdrawn from the body.

For the intracranial stent 110 shown in fig. 1, since the thickness of the support rods of the open loop support unit 112 is different, when the stent 110 is compressively preloaded in the delivery catheter, the pressure generated by the thick support rods 113 and the thin support rods 114 against the inner wall of the delivery catheter is different. Therefore, when the support 110 is pushed and pulled along the conveying path in the conveying duct, the coarse support rods 113 and the fine support rods 114 are subjected to different frictional resistance given by the conveying duct, which easily causes inconsistent advancing steps of the coarse support rods and the fine support rods along the inner wall of the conveying duct, and further causes adjacent support rods to be stacked.

In addition, the developing member provided at the outer side of the rack 110 may have bad results on the conveyance of the rack. Taking the proximal developing member 117 as an example, referring to fig. 2, since the proximal developing member 117 is partially located outside the stent, it is equivalent to separating the open-loop supporting unit 112 from the inner wall of the delivery catheter 130 at the proximal end of the stent, so that the open-loop supporting unit 112 cannot be completely adhered to the inner wall of the delivery catheter 130 during the delivery of the stent. When the operator applies a pushing force to the open loop support unit 112 at the proximal end of the stent via the proximal developing ring 144, an obliquely outward pushing force 150 is generated. The thrust force 150 breaks down radially of the stent to create an outward pressure against the inner wall of the vertical delivery catheter 130 that not only causes increased frictional resistance during stent delivery, but also causes uneven stent delivery in curved vessels. In addition, during the conveying process of the stent, the developing part 117 positioned at the outer side of the stent may scratch the inner wall of the conveying conduit 130, so as to damage the inner wall of the conveying conduit 130 and form scraps, and also increase the pushing force of the stent, thereby bringing clinical risks. At the same time, the stent is released at the lesion site, and the visualization member 117 positioned outside the stent also stimulates the inner wall of the blood vessel, resulting in thrombus and intimal hyperplasia.

In summary, in the intracranial stent shown in fig. 1, the supporting rods of two adjacent waverings are mutually pressed and stacked together due to the different thicknesses of the supporting rods of the open-loop supporting unit 112 and the separation of the open-loop supporting unit 112 and the inner wall of the delivery catheter 130 by the developing member positioned outside the stent 110 during the delivery process, so that the stent is difficult to push or can not be opened at the lesion site and can not be completely released.

Disclosure of Invention

In view of the foregoing deficiencies of the prior art vascular stent delivery systems, the present application provides a stent delivery system that avoids tangling of the struts of an intracranial stent during delivery of the stent to a lesion.

The application adopts a technical scheme that: a stent delivery system includes a delivery catheter, a delivery device, and a stent. The bracket comprises a bracket main body, a proximal developing structure and a distal developing structure, wherein the proximal developing structure and the distal developing structure are respectively arranged at the proximal end and the distal end of the bracket main body. The support body includes a plurality of open-loop supporting units, every open-loop supporting unit includes a first wave circle and with the adjacent second wave circle of first wave circle, form the bracing piece of first wave circle is thicker than the bracing piece of second wave circle. The proximal development structure includes a proximal development member and the distal development structure includes a distal development member. The conveying device comprises a delivery guide wire and a distal spring sleeved at the distal end of the delivery guide wire. The stent is compressively loaded within the delivery catheter. The distal spring penetrates through the bracket along the axial direction of the bracket. The delivery guidewire cooperates with the proximal end of the distal spring to limit the proximal visualization structure of the stent. The proximal developing part and the distal developing part of the bracket are both arranged on the inner side of the bracket. Defining the wall thickness of the stent to be a minimum, the inner diameter of the delivery catheter to be B maximum, and the diameter of the distal spring to be C minimum, A, B and C satisfy the following inequality: a > B-2A-C > 0.

In the stent delivery system provided by the embodiment of the application, the delivery device further comprises a proximal end limiting ring and a distal end limiting ring, wherein the proximal end limiting ring and the distal end limiting ring are sleeved on the delivery guide wire, the distal end of the distal end limiting ring is fixedly connected with the proximal end of the distal end spring, and the proximal end limiting ring is positioned at the proximal end of the distal end limiting ring. The proximal end limiting ring and the distal end limiting ring are matched to limit the proximal end developing structure, namely, the proximal end of the bracket is clamped. In this way, the stent is prevented from shifting a predetermined path during delivery and a uniform pushing force is ensured to be applied to the proximal end of the stent.

The stent conveying system provided by the embodiment of the application can pull back the stent in the stent conveying process and after releasing the stent, the conveying device further comprises a limiting spring, the limiting spring is rotatably arranged on the delivery guide wire and is positioned between the proximal limiting ring and the distal limiting ring, and the proximal developing part of the stent is positioned on the limiting spring. When the delivery guide wire is twisted in the conveying process, the proximal developing part and the limiting spring of the stent can not be twisted along with the delivery guide wire, so that the twisting of the stent in the conveying process can be reduced.

The stent conveying system provided by the embodiment of the application can pull back the stent after releasing the stent so as to adjust the position of the stent in the conveying catheter and ensure that the stress on the proximal end of the stent main body is uniform, the thickness of the proximal end developing part is defined as D, the diameter of the proximal end limiting ring is defined as E, the diameter of the distal end limiting ring is defined as F, and the diameter of the limiting spring is defined as G, wherein B is larger than E and larger than B-2 (A+D); B-2A > F > B-2 (A+D); b-2 (A+D) > G.

In one embodiment of the stent delivery system provided by the present application, the proximal stop collar has an outer diameter that is approximately equal to the inner diameter of the delivery catheter. Therefore, in the process of conveying the stent, the proximal limiting ring can move at a constant speed along the inner diameter of the conveying guide pipe, and the conveying smoothness of the stent main body is improved.

In the stent conveying system provided by the embodiment of the application, the proximal developing structure and the distal developing structure each comprise a fixing piece, the proximal developing piece and the distal developing piece are respectively fixed on the inner sides of the fixing pieces, and the fixing pieces are arranged at the proximal end and the distal end of the stent main body and are integrally cut with the stent main body.

The stent delivery system provided by the application is suitable for intracranial stents with various wall thicknesses. It is understood that the wall thickness refers to the thickness of the support bar constituting the stent in the radial direction of the stent.

In the stent delivery system provided by an embodiment of the present application, the delivery device may further comprise a proximal spring. The proximal end of the proximal spring is connected to the distal end of the delivery guidewire, and the proximal development ring is disposed at the distal end of the proximal spring. Therefore, compared with the pushing part of the guide wire made of plastic materials, the whole flexibility of the guide wire can be further improved, and the pushing force is ensured to be more uniform.

In the stent delivery system provided by an embodiment of the present application, the distal spring includes a developing portion and a non-developing portion connected to the developing portion, the developing portion being closer to a distal end of the distal spring than the non-developing portion; the diameter of the developing portion is the same as the diameter of the non-developing portion.

In the stent delivery system provided by an embodiment of the present application, the length of the distal spring is equal to or smaller than the length of the stent body. It is understood that the length of the stent body refers to the length of the stent as a whole from which the distal developing member and the proximal developing member are removed.

Compared with the prior art, the wall thickness value of the stent conveying system provided by the application is larger than the gap between the far-end spring and the stent when the stent is preloaded in the conveying device by designing the stent, and the near-end developing part and the far-end developing part are both positioned at the inner side of the stent, so that the adherence of the stent and a conveying catheter is improved, the difference of friction force between support rods with different thicknesses and the conveying catheter is reduced, the mutual extrusion and accumulation of the support rods of adjacent waverings in the process of conveying the stent to a lesion point are avoided, the uniform stress of the stent is ensured, and smooth pushing and pulling can be realized.

Drawings

FIG. 1 is a schematic diagram of the structure of an intracranial stent.

FIG. 2 is a schematic view of the intracranial stent shown in FIG. 1 when subjected to a pushing force during delivery.

Fig. 3 is a schematic structural diagram of a stent delivery system according to an embodiment of the present application.

FIG. 4 is a schematic view of an intracranial stent according to an embodiment of the present application.

FIG. 5 is an enlarged schematic view of a portion of the proximal visualization structure of the intracranial stent shown in FIG. 4.

Fig. 6 is a schematic diagram of a conveying device of a stent conveying system according to an embodiment of the present application.

Fig. 7 is an enlarged partial schematic view of a delivery catheter, stent body, distal spring of the stent delivery system of fig. 3.

Fig. 8 is an enlarged partial schematic view of the delivery catheter, stent body, distal spring, proximal developing member, distal developing member and stop spring of the stent delivery system of fig. 3.

Detailed Description

In order to make the above objects, technical solutions and advantages of the present application more comprehensible, the present application is described in detail below with reference to the accompanying drawings and examples.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application to those skilled in the art. It will be appreciated that the application can be practiced in many other ways than those herein described and that those of ordinary skill in the art will be able to make similar modifications without departing from the spirit of the application, and therefore the application is not limited to the specific implementations disclosed below.

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 application belongs. The terminology used in the description presented herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

In this specification, the end of the stent delivery system provided by the present application that is closer to the operator is referred to as the "proximal end", the end that is farther from the operator is referred to as the "distal end", and the "proximal end" and "distal end" of any component in the stent delivery system are defined according to this principle. "axial" generally refers to the length of the stent as it is delivered, and "radial" generally refers to the direction of the stent perpendicular to its "axial" direction.

An embodiment of the present application provides a stent delivery system comprising a stent 210 as shown in fig. 4, a delivery device 220 as shown in fig. 3, and a delivery catheter 230.

Fig. 4 shows a structure of the stent 210 in a self-expanding state, i.e. an unconstrained state, according to an embodiment of the present application, which includes a stent body 211, a proximal developing structure 2150 and a distal developing structure, wherein the proximal developing structure 2150 and the distal developing structure are disposed at the proximal end and the distal end of the stent body 211, respectively.

The stent body 211 is implanted in a lesion of a human body to support a blood vessel of the lesion, reduce blood flow into an aneurysm, and induce thrombosis in the aneurysm. The bracket main body 211 is engraved by a metal pipe (such as a nickel-titanium pipe), and the pipe wall of the metal pipe forms a plurality of hollow grids. The holder body 211 includes a plurality of open loop support units 2111. Each of the open-loop support units 2111 includes a first pulsator 213 and a second pulsator 214 which are axially arranged along the stent body 211 and are adjacent. Wherein the support bars constituting the first pulsator 213 are thicker than the support bars constituting the second pulsator 214. That is, the first and second pulsators 213 and 214 are alternately arranged in the axial direction of the holder body 211. "thick" as used herein refers to the width of the support rod on the circumferential surface of the stent 210, rather than the thickness (i.e., wall thickness) of the stent 210 in the radial direction. By designing the stent in this way, the flexibility of the stent can be adjusted. The support bar 212 is hereinafter collectively referred to as a support bar constituting the first pulsator 213 and a support bar constituting the second pulsator 214.

It is understood that the thickness of any one of the support rods at any location, i.e., the thickness of that portion of the support rod in the radial direction of the stent 210, is designated in the art as the wall thickness of the stent 210 at that location. For stents with different strut thicknesses, there are correspondingly a plurality of wall thickness values.

Proximal visualization structure 2150 and distal visualization structure are used to visualize stent 210 under clinical X-ray conditions, facilitating the physician's identification of the implant status and implant location of stent 210. In the present application, the proximal developing structure 2150 and the distal developing structure are identical in structure and identical in connection relationship and positional relationship to the bracket 210. The connection and positional relationship between the proximal developing structure 2150 and the holder main body 211 will be described by way of example.

Referring to fig. 5, proximal developing structure 2150 includes proximal developing member 215, a fixture 2151, and a locator pin 2152. The fixing member 2151 is integrally formed with the bracket body 211, for example, integrally cut from the same nickel-titanium alloy, that is, the fixing member 2151 is part of the bracket 210. The fixtures 2151 are located at the proximal and distal ends of the holder body 211. The proximal developing member 215 and the fixing member 2151 are both in a sheet structure, and the proximal developing member 215 is disposed on a side close to the central axis of the holder main body 211, i.e., the proximal developing member 215 is disposed inside the holder 210. The thickness of the holder 2151 is identical to the wall thickness of the holder body 211. Specifically, the proximal developing member 215 is located inside the fixing member 2151 at the proximal end of the holder main body 211. The fixture 2151 is provided with a first alignment aperture (blocked by alignment pin 2152) and the proximal developer 215 is provided with a second alignment aperture (blocked by alignment pin 2152). The positioning pins 2152 are inserted into the first and second positioning holes, whereby the proximal developing member 215 and the fixing member 2151 are fixed to each other by the positioning pins 2152. The locating pin 2152 may be nickel titanium wire.

In another embodiment, after the positioning pin 2152 passes through the first positioning hole and the second positioning hole, the two ends of the positioning pin 2152 are fixed to the proximal developing member 215 and the fixing member 2151 by laser welding, respectively.

In yet another embodiment, the edges of the proximal developer 215 and the fixture 2151 are laser welded to form a weld 2153. Weld 2153 eliminates gaps between proximal shaft section 215 and anchor 2151 and prevents crevice corrosion caused by the gaps after stent 210 is implanted in a vessel.

In other embodiments, the connection between the proximal developing member 215 and the fixing member 2151 may be other than a dowel, such as by welding the proximal developing member 215 directly to the side of the fixing member 2151 near the center axis of the bracket 210, i.e., inside the bracket 210.

Likewise, the distal development structure also includes a distal development member 216 as shown in fig. 4, a fixing member 2151 as shown in fig. 5, and a positioning pin 2152 as shown in fig. 5. The distal developing member 216 is disposed inside the fixing member 2151 at the distal end of the bracket main body 211, and the specific structure of the distal developing structure can refer to the proximal developing structure, which is not described herein.

In the conveying process of the stent 210, since the proximal developing member 215 and the distal developing member 216 are both positioned on the inner side of the stent 210, the supporting rod of the stent main body 211 will directly contact with the inner wall of the conveying conduit 230, and has good adhesion with the inner wall of the conveying conduit 230 and good compliance. The proximal end of the holder body 211 is uniformly forced by the pushing of the transport pushing force, which does not generate a pressure perpendicular to the radial direction of the holder body 211. Moreover, since the proximal developing member 215 and the distal developing member 216 are disposed inside the stent body 211 and do not contact the delivery catheter 230, the inner wall of the delivery catheter 230 can be prevented from being scratched, the pushing force of the stent 210 can be reduced, and the clinical risk can be reduced; and when the stent 210 is released at the vascular lesion site, the proximal visualization element 215 and the distal visualization element 216 will not be in direct contact with the inner wall of the blood vessel, so that the inner wall of the blood vessel is prevented from being stimulated by the visualization material, and the risk of thrombus and intimal hyperplasia is reduced.

As shown in fig. 6, the delivery device 220 includes a delivery guidewire 221, a proximal spring 223, a proximal stop collar 224, a stop spring 225, a distal stop collar 226, a distal spring, and a distal weld 229. The proximal spring 223, proximal stop collar 224, stop spring 225, distal stop collar 226, and distal spring are sequentially sleeved on the delivery guidewire 221 from proximal to distal, with the distal weld 229 at the distal end of the distal spring.

The delivery guidewire 221 includes a distal portion 2211 and a proximal portion 2212 connected to the distal portion 2211, the diameter of the distal portion 2211 is smaller than the diameter of the proximal portion 2212, so that the distal end of the delivery guidewire 221 has better flexibility and the proximal end has better pushing performance. The delivery guidewire 221 may be made of stainless steel with a length marker 222 provided at its proximal end to facilitate the physician's immediate knowledge of the advancing displacement of the stent along the predetermined delivery path as the stent is implanted.

The proximal spring 223 is sleeved over the distal end 2211 of the delivery guidewire 221 near the proximal end 2212 and is fixedly attached to the delivery guidewire 221, e.g., welded, to the delivery guidewire 221. In one embodiment, the proximal spring 223 is made of stainless steel spring. The inner diameter of the proximal spring 223 matches the outer diameter of the delivery guidewire 221 at that location. In one embodiment, the outer diameter of the proximal spring 223 is 0.35.+ -. 0.05mm.

The proximal stop collar 224 is fixedly sleeved on the distal end portion 2211 of the delivery guide wire 221, and the proximal end of the proximal stop collar 224 is connected with the distal end of the proximal spring 223. The proximal stop collar 224 is of annular configuration. In one embodiment, the outer diameter of the proximal stop collar 224 is approximately the inner diameter of the delivery catheter 230, i.e., the outer diameter of the proximal stop collar 224 is equal to the inner diameter of the delivery catheter 230, or the outer diameter of the proximal stop collar 224 is less than the inner diameter of the delivery catheter 230, with a difference of no more than 0.06mm. In one embodiment, the proximal stop collar 224 has an outer diameter of 0.40.+ -. 0.03mm. The proximal stop ring 224 is made of a developing material, and in one embodiment, the proximal stop ring 224 is made of platinum iridium alloy.

The distal stop collar 226 is fixedly sleeved on the distal end 2211 of the delivery guide wire 221 and is closer to the distal end than the proximal stop collar 224, and the outer diameter of the distal stop collar 226 is smaller than the outer diameter of the proximal stop collar 224. In one embodiment, the outer diameter of the distal stop collar 226 is 0.28.+ -. 0.03mm. The distal stop ring 226 is also made of a developing material, and in one embodiment, the distal stop ring 226 is made of platinum iridium alloy.

A stop spring 225 is rotatably disposed at the distal end 2211 of the delivery guidewire 221 between the proximal stop ring 224 and the distal stop ring 226. The stop spring 225 prevents the carrier 210 from twisting during delivery. The length of the spacing spring 225 may be slightly greater than the length of the proximal development member 215 of the carrier 210. The outer diameter of the stop spring 225 is less than the outer diameter of the distal stop collar 226. In one embodiment, the outer diameter of the stop spring 225 is 0.13.+ -. 0.02mm. In one embodiment, the spacing spring 225 is made of stainless steel.

The distal spring is sleeved on the distal end of the delivery wire 221, and the distal end of the distal spring is fixed on the distal end face of the distal end portion 2211 of the delivery wire 221 by a distal welding point 229. Referring to fig. 6, the length of the distal spring is less than or equal to the length of the holder 210 minus the proximal developing member 215 and the distal developing member 216, i.e., the length 217 of the holder body 211 shown in fig. 4.

In this embodiment, the distal spring includes a non-developing portion 227 and a developing portion 228 connected to the non-developing portion 227, the developing portion 228 being closer to the distal end of the delivery guidewire 221 than the non-developing portion 227, the proximal end of the non-developing portion 227 being fixedly connected to the distal end of the distal stop ring 226.

The developing part 228 is made of a developing material, for example, platinum iridium alloy, the non-developing part 227 may be made of stainless steel, the developing part 228 and the non-developing part 227 are integrally connected by welding, the developing part 228 is used for marking the position of the distal end of the delivery guide wire 221, and the non-developing part 227 may improve the toughness of the distal end of the delivery guide wire 221. In one embodiment, the diameter of the developing portion 228 is the same as the diameter of the non-developing portion 227.

It should be noted that in some embodiments, the distal spring may also include only the developing portion 228, i.e., the distal spring is entirely a developing portion made of developing material, and the non-developing portion 227 formed of non-developing material is not required.

The distal end of the distal stop collar 226 is fixedly connected to the proximal end of the distal spring, the proximal stop collar 224 is located proximal of the distal stop collar 226, and the proximal stop collar 224 matingly engages the distal stop collar 226 to stop the proximal development feature 2150. Since the fixing member of the proximal developing structure is integrally formed with the holder main body 211, the proximal developing structure is schematically represented by a proximal developing member 215 in fig. 3 and 8.

Referring to fig. 3 and 7, when the stent 210 is compressively assembled within the delivery catheter 230, the distal spring passes through the stent body 211 in the axial direction of the stent 210, and the delivery guidewire 221 cooperates with the proximal end of the distal spring to limit the proximal development structure (schematically represented by proximal development 215) of the stent 210. The wall thickness 241 of the stent 210 (illustrated in fig. 7 as support bar 212) is greater than the gap 242 between the distal spring and the support bar 212 of the stent 210, i.e., defining the wall thickness 241 of the stent as a, the inner diameter of the delivery catheter 230 as B, and the diameter 243 of the distal spring as C, A, B and C satisfy: a > B-2A-C > 0. By such design, the adherence of the stent body 211 and the delivery catheter 230 is good, the friction force between the supporting rod forming the first wave ring 213 and the supporting rod forming the second wave ring 214 and the inner wall of the delivery catheter 230 is not great, even if the distal spring deviates from the central axis of the stent 210 in the process of pushing the stent 210, the supporting rod 212 is not extruded into the gap between the supporting rod 212 and the distal spring of the delivery guide wire 221, the supporting rods 212 with different thicknesses are prevented from being stacked with each other in the delivery process of the stent 210, and smooth pushing of the stent 210 is ensured.

In this embodiment, the wall thickness of the stent 210 is 0.055mm, the inner diameter of the delivery catheter 230 is 0.43mm, and the diameter of the distal spring is 0.28mm.

Referring to fig. 3, 6 and 8, when the stent 210 and the delivery guidewire 221 are assembled together into the delivery catheter 230 for delivery, the proximal visualization element 215 of the stent 210 is positioned between the proximal stop collar 224 and the distal stop collar 226 of the delivery guidewire 221. In this way, the proximal stop ring 224, the distal stop ring 226 and the stop spring 225 perform a stop action on the proximal developing member 215, so that the delivery guide wire 221 can push and retract the stent 210, and the stent 210 can be ensured to be delivered to the lesion along a predetermined path. The distal visualization structure of the stent 210 exceeds the distal end of the distal spring on the delivery guidewire 221, and in the delivery catheter, the distal visualization structure of the stent 210 is located at the position of the delivery catheter 230 closest to the distal end, i.e., the distal end of the distal spring has no limitation or fixation on the stent 210, so as to facilitate the deployment and overall release of the distal end of the stent 210 in the blood vessel where the lesion is located, and no additional visualization spring is required at the distal end, so that the inner wall of the distal blood vessel is not stimulated. In one embodiment, the holder body 211 is sleeved on a distal spring, the length of the distal spring is approximately equal to the length of the holder body 211, and the proximal end of the distal developing member 216 of the holder 210 just protrudes from the distal spring.

Specifically, the dimensions of the components of the stent delivery system satisfy the following dimensional relationships: defining the wall thickness of the bracket main body 211 as A, the inner diameter of the delivery catheter 230 as B, the thickness of the proximal developing member 215 as D, the diameter of the proximal stop ring 224 as E, the diameter of the distal stop ring 226 as F, and the diameter of the stop spring 225 as G, B > E > B-2 (A+D); B-2A > F > B-2 (A+D); b-2 (A+D) > G. Preferably, the outer diameter of the proximal stop collar 224 is approximately equal to the inner diameter of the delivery catheter 230.

In this embodiment, the wall thickness of the stent body 211 is 0.055mm, the inner diameter of the delivery catheter 230 is 0.43mm, and the thickness of the proximal development member 215 is 0.06mm, i.e., 0.43mm > the diameter of the proximal stop collar 224 > 0.2mm,0.32mm > the diameter of the distal stop collar 226 > 0.2mm,0.2mm > the diameter of the stop spring 225.

In the stent delivery system of the present embodiment, in the delivery process of the stent, it can be ensured that the pushing force 240 as shown in fig. 8 transmitted by the delivery guide wire can directly act on the stent main body 211 in a direction parallel to the axis of the stent main body 211 through the proximal stop ring 224, thereby realizing uniform stress when the stent is pushed and retracted in a curved vessel, and smooth push-pull process.

The above embodiments describe the stent delivery system provided by the present application in detail. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application.

Claims

1. The bracket conveying system comprises a conveying guide pipe, a conveying device and a bracket, and is characterized in that the bracket comprises a bracket main body, a proximal developing structure and a distal developing structure, wherein the proximal developing structure and the distal developing structure are respectively arranged at the proximal end and the distal end of the bracket main body, the bracket main body comprises a plurality of open-loop supporting units, each open-loop supporting unit comprises a first wave ring and a second wave ring adjacent to the first wave ring, a supporting rod forming the first wave ring is thicker than a supporting rod forming the second wave ring, the proximal developing structure comprises a proximal developing piece, and the distal developing structure comprises a distal developing piece; the conveying device comprises a delivery guide wire and a distal spring sleeved at the distal end of the delivery guide wire; the stent is compressively loaded in the delivery catheter, the distal spring penetrates through the stent main body along the axial direction of the stent, and the delivery guide wire and the proximal end of the distal spring cooperatively limit the proximal development structure of the stent; the proximal developing part and the distal developing part of the bracket are both arranged on the inner side of the bracket; defining the wall thickness of the stent as a, the inner diameter of the delivery catheter as B, and the diameters of the distal springs as C, A, B and C satisfy: a > B-2A-C > 0.

2. The stent delivery system of claim 1, wherein the proximal developing structure and the distal developing structure each comprise a fixing member, the proximal developing member and the distal developing member are respectively fixed to inner sides of the fixing member, and the fixing member is disposed at a proximal end and a distal end of the stent body and integrally formed with the stent body.

3. The stent delivery system of claim 1, wherein the delivery device further comprises a proximal stop collar and a distal stop collar, wherein the proximal stop collar and the distal stop collar are both sleeved on the delivery guidewire, the distal end of the distal stop collar is fixedly connected to the proximal end of the distal spring, the proximal stop collar is positioned proximal to the distal stop collar, and the proximal stop collar and the distal stop collar cooperatively limit the proximal development structure.

4. The stent delivery system of claim 3, wherein the delivery device further comprises a stop spring rotatably disposed on the delivery guidewire between the proximal stop collar and the distal stop collar.

5. The stent delivery system of claim 4, wherein the proximal developing member is defined as having a thickness D, the proximal stop ring is defined as having a diameter E, the distal stop ring is defined as having a diameter F, and the stop spring is defined as having a diameter G, then B > E > B-2 (a+d); B-2A > F > B-2 (A+D); b-2 (A+D) > G.

6. The stent delivery system of claim 3, wherein an outer diameter of the proximal stop collar is equal to an inner diameter of the delivery catheter.

7. The stent delivery system of claim 3, wherein the delivery device further comprises a proximal spring, wherein the proximal spring is sleeved on and fixedly connected to the delivery guidewire, and wherein the proximal stop collar is disposed at a distal end of the proximal spring.

8. The stent delivery system of claim 1, wherein the distal spring comprises a developing portion and a non-developing portion connected to the developing portion, the developing portion being closer to a distal end of the distal spring than the non-developing portion; the diameter of the developing portion is the same as the diameter of the non-developing portion.

9. The stent delivery system of claim 1, wherein the distal spring has a length equal to or less than a length of the stent body.