CN109549758A

CN109549758A - A kind of sheath core

Info

Publication number: CN109549758A
Application number: CN201710913847.2A
Authority: CN
Inventors: 曾敏; 罗拉里
Original assignee: Qiming Medical Devices (shanghai) Co Ltd
Current assignee: Qiming Medical Devices (shanghai) Co Ltd
Priority date: 2017-09-26
Filing date: 2017-09-26
Publication date: 2019-04-02

Abstract

The invention discloses a kind of sheath core, one end of the core pipe is the distal end for connecting intervention apparatus, and the other end is proximal end；The core pipe at adjacent distal end there is bending stiffness to reduce section.Intervention apparatus conveying system of the present invention, the sheath core including sheath and in sheath.Sheath core of the invention, flexibility is good, in valve replacement surgery, is more easier to turn, has evaded operation risk, is particularly suitable for cusps of pulmonary valve displacement technique.

Description

Sheath core

Technical Field

The invention relates to the technical field of medical instruments, in particular to a sheath core and an interventional instrument conveying system comprising the same.

Background

When the heart valve (mitral valve, tricuspid valve, aortic valve or pulmonary valve) of a patient is mutated due to congenital or acquired diseases, the valve cannot be normally opened and closed, and the healthy life and even life are affected. The variation of heart valves can be divided into incompetence and incompetence, both of which can cause the heart to be loaded, and whether the heart can work normally under the load is the main basis for determining whether the heart valve of a human body should be replaced.

When a patient needs to replace a valve, the existing method adopts an open surgical operation to replace the valve, and a doctor opens the chest of the patient to stop the heart and connects the heart and lung circulation system in vitro. The patient's heart is then opened to remove the diseased heart valve, the prosthetic heart valve is then sutured in place, and finally the heart and chest are sutured closed. The operation process is a very traumatic operation process, has a certain death risk, has long recovery time for patients, and many patients cannot bear the operation process due to the fact that the operation wound is large and cannot perform the operation process although the valve needs to be replaced.

In view of the disadvantages of open surgery, the way of implanting a prosthetic heart valve through an interventional operation is receiving more attention due to its advantages of less trauma and less invasiveness to the human body. This procedure, without an incision, creates a small opening in the patient's skin of a few millimeters in diameter, thereby accessing the body's vasculature, establishing a delivery channel, and then delivering a prosthetic heart valve, i.e., a stent, to the heart and replacing the defective native valve with a specialized delivery system.

Generally, a stent is fixed on a stent fixing head, the stent fixing head is connected to one end of a core tube, the front end of the stent fixing head is provided with a streamline guide head, an installation section for sleeving the stent is arranged between the guide head and the stent fixing head, the core tube, the stent fixing head, the installation section and the guide head jointly form a sheath core, when a valve is implanted, the stent is firstly clamped on the stent fixing head of a conveying device, a sheath tube is sleeved outside the sheath core to keep the compressed state of the stent, the sheath tube and the sheath core carry the stent to be pushed to a diseased valve part from an entrance of a blood vessel, then the stent is released, the stent can expand under the action of body temperature, blades of a human valve are pushed to the blood vessel wall to complete positioning, and then the sheath tube and the sheath core are pulled out.

In valve replacement surgery, a delivery system carrying a stent needs to pass through a tortuous and complex human vascular system to reach an implantation site, for example, when an aortic valve is replaced, the delivery system generally firstly punctures from a femoral artery, passes through an abdominal aorta and a descending aorta, then passes through an aortic arch and moves backwards to the root of the aorta to replace the valve, the delivery system forms a large bend when passing through the aortic arch, and similarly, in the replacement process of a mitral valve and a tricuspid valve, the delivery system also passes through at least one bent part of a vessel, so that the delivery system is required to have enough flexibility to ensure that the stent can track to the autologous valve part and must also have enough flexibility to ensure that the stent tracks through the bent part of the human vascular to prevent mechanical damage to the inside of a human body.

Compliance of the delivery system is particularly important in pulmonary valve replacement procedures. When the pulmonary valve is replaced, firstly puncture is carried out from the femoral vein, the pulmonary valve is replaced through the inferior vena cava, the right atrium, the tricuspid valve and the right ventricle, the pulmonary valve is implanted, the implantation path of the pulmonary valve is S-shaped, the whole implantation process is obviously different from that of the aortic valve, the mitral valve and the tricuspid valve, the delivery system passes through two bending parts, and the bending degree of the two bending parts is larger than that of the aorta.

Obviously, the requirement for the compliance of the delivery system is higher, but in the current pulmonary valve replacement, the same delivery system as the aortic valve replacement is still adopted, so that the blood vessels, the cardiac muscle and the tricuspid valve are more easily damaged during the process of advancing or withdrawing the delivery system from the human body, and even the dislocation of the stent can be caused, and the operation risk is increased.

Although the improvement of the flexibility of the delivery system is never completed, research is focused on the improvement of the structure or material of the sheath, and the sheath needs to resist the expansion state of the stent, maintain the compression state of the stent and maintain the axial pushing performance in the process of recovering and releasing the stent, so that the sheath has high requirements on the pressure bearing performance and the folding resistance and has certain axial supporting strength, so that the space for improving the flexibility of the sheath is extremely limited, and the effect is not good.

Disclosure of Invention

The sheath core provided by the invention has good flexibility, is easier to turn in a valve replacement operation, avoids mechanical damage to the inside of a human body, avoids operation risks and reduces operation difficulty.

A sheath core comprises a core tube, wherein one end of the core tube is a far end used for being connected with an interventional instrument, and the other end of the core tube is a near end; the core tube has a reduced bending stiffness section adjacent the distal end. I.e. a section of the core tube adjacent the distal end has a lower bending stiffness than the rest of the core tube.

The bending stiffness represents the capability of the object to resist bending deformation, the larger the bending stiffness is, the less the sheath core is easy to bend, and conversely, the smaller the bending stiffness is, the sheath core is easy to deform and deform, and the better the compliance is (namely, the sheath core is easy to deform and bend under the action of radial force and has radial flexibility).

Because a general interventional device (hereinafter, a stent is taken as an example) has a short length, for example, the length of the stent is about 60mm, the difficulty of bending the part of the sheath core where the stent is installed in a human body is small, and the part of the core tube adjacent to the distal end is subjected to a complicated bending process, for example, in a pulmonary valve replacement, the part needs to be bent twice to form an S shape.

Therefore, the bending rigidity reducing section provided by the invention enables the conveying system to be easy to bend when passing through a complex and tortuous vascular system, so that the conveying system can run more smoothly in the turning process, the operation risk that the conveying system damages blood vessels, cardiac muscles and tricuspid valves or the stent is misplaced is avoided, meanwhile, other parts (parts except the bending rigidity reducing section) of the core tube of the sheath core still keep relatively large bending rigidity, the axial pushing performance (namely, the axial non-easy compression) of the sheath core is ensured, and the conveying system is ensured to push the stent to an implantation site in the operation.

It will be understood by those skilled in the art that the distal end of the present invention refers to the end of the core tube distal to the operating handle in the delivery system, and the proximal end refers to the end of the core tube proximal to the operating handle in the delivery system.

The reduced bending stiffness section should be as close as possible to the distal end of the core tube, although a smaller distance may be allowed, typically no more than 50 mm.

The distance is the distance from the end of the reduced bending stiffness section adjacent to the distal end of the core tube.

For ease of processing and also for better compliance of the sheath core, it is further preferred that the reduced bending stiffness section is located immediately adjacent the interventional instrument, i.e. the distal end of the core tube is one end of the reduced bending stiffness section.

The bending stiffness of the bending stiffness reduction section can be uniform (i.e. the same) or different, i.e. show a certain variation, and the variation can be random or regular.

Alternatively, the bending rigidity decreasing section gradually decreases the bending rigidity in the distal direction. The reduced bending stiffness section has a gradually decreasing bending stiffness in the direction towards the distal end, meaning that the closer the sheath core is to the distal end, the more compliant the sheath core is, where the gradual decrease may be either continuous or stepwise.

The low bending rigidity of the bending rigidity reduction section can be realized by various means such as material selection, structural change and the like.

Usually, the core tube of the sheath core is a steel wire braided spring tube structure, and the structure ensures the propelling property and the compliance of the sheath core. Obviously, in the present invention, the bending stiffness reduction section may also be a spring tube made of steel wires, and the bending stiffness of the section is reduced by changing the weaving manner, such as changing a plurality of steel wires into a single steel wire, or changing the diameter of the steel wires.

It should be noted that the processing of the core tube including the reduced bending stiffness section is not limited to the weaving process, and a laser engraving process or other processing means may be used.

In addition, the bending rigidity can be reduced by selecting the material with weaker bending rigidity.

The basic pushability and safety of the sheath core should be maintained regardless of the change of structure or material, and particularly the material should be selected to meet the relevant standard requirements of medical devices.

The bending rigidity ratio of the bending rigidity reducing section to the other parts of the core pipe is 1: 3-1: 6, preferably 1: 3-1: 4, and more preferably 1: 4.

The bending rigidity can be calculated by a conventional method or a simple method.

If the ratio is too small, the bending rigidity of the bending rigidity reduction section is large, and the flexibility of the sheath core is insufficient;

if the ratio is too large, the bending rigidity of the bending rigidity reduction section is small, the sheath core is too soft, and the pushing force is insufficient.

The bending rigidity reducing section is generally 125-175 mm in length, preferably 140-160 mm in length, and more preferably 150mm in length.

The bending rigidity reducing section is too long, the pushing force of the sheath core is insufficient, and the length is too short, so that the compliance of the sheath core is affected.

Obviously, the length of the bending stiffness reduction section can be adaptively set according to a specific operation path, for example, the replacement of the pulmonary valve, and the implantation path is "S" shaped, so that two curves can be set according to the distance between two curves to be rotated by the delivery system, and the two curves are generated in the bending stiffness reduction section.

The bending stiffness reduction section and the other parts of the core tube may be connected by connecting members or may be integrally formed.

Although the bending rigidity reducing section differs in the ability to resist bending deformation from the other parts of the core tube, it is preferable that the bending rigidity reducing section has the same outer diameter as the other parts of the core tube. The outer diameter of the whole core pipe can be ensured to be consistent, so that a gap is prevented from being generated between the sheath pipe and the core pipe, and the sheath pipe is prevented from being bent in the operation process.

The far end of the core pipe is connected with a support fixing head, and the support fixing head is connected with a guide head through an installation section for sleeving a support.

Preferably, the periphery of the core tube is covered with a resistance reducing layer made of tetrafluoroethylene material.

The sheath core is also sleeved with the sheath tube when in use, and obviously, the resistance reducing layer is a structural layer for reducing the sliding friction resistance between the sheath core and the sheath tube.

The resistance reducing layer is arranged on the core tube of the sheath core, so that the resistance of the sheath core during movement can be reduced, namely the friction force between the sheath core and the sheath tube is reduced, the relative movement between the sheath core and the sheath tube is smoother, the releasing force of the support is reduced, and the support is easy to recover and reposition.

Meanwhile, the resistance reducing layer is of a continuously distributed layer structure, the periphery of the core pipe is wrapped, so that the sealing effect is exerted, when water is injected and air is exhausted, air is exhausted more thoroughly, and blood leakage is avoided to form thrombus.

The resistance reducing layer can cover the partial periphery of the core pipe, and preferably, the resistance reducing layer covers the whole periphery of the core pipe.

Tetrafluoroethylene has self-lubricating property and low friction coefficient, and has excellent performances of wear resistance, chemical corrosion resistance, good sealing property, no hydrolysis, no hardening and the like, and the safety is high.

For convenience of processing, the resistance reducing layer is preferably a tetrafluoroethylene pipe. The polytetrafluoroethylene tube which is processed and formed is conveniently sleeved outside the core tube.

The thickness of the resistance reducing layer is 0.01-0.2 mm.

The resistance reducing layer is too thick, the radial flexibility of the sheath core can be influenced, the conveying system is not favorable for turning in the valve replacement process, the injury to the vascular wall, cardiac muscle, valve and the like of a human body can be easily caused, and even the dislocation of the stent can be caused;

the resistance reducing layer is too thin, so that the sealing effect is influenced, the exhaust is not thorough, and the abrasion of the surface of the resistance reducing layer is inevitably caused in the use process of the sheath core, so that air leakage and blood leakage are caused.

The invention also provides an interventional device conveying system which comprises a sheath tube and the sheath core positioned in the sheath tube.

In order to avoid the bending of the sheath tube, the thickness of the resistance reducing layer covered by the core tube of the sheath core is adapted to the gap between the core tube and the sheath tube.

The sheath core has good flexibility, avoids operation risks, reduces operation difficulty, and is particularly suitable for pulmonary valve replacement, but obviously, the sheath core and the delivery system are not limited to replacement of pulmonary valves, and can be used for replacement of other valves such as aortic valves, mitral valves and tricuspid valves, or the structure is applied to other interventional surgical instruments, so that the requirement of a complicated and tortuous operation path is met.

Drawings

FIG. 1 is a schematic structural view of a sheath core of the present invention;

FIG. 2 is a schematic view of a reduced bending strength section of the core barrel of FIG. 1;

FIG. 3 is a cross-sectional view taken along A-A of FIG. 2;

FIG. 4 is a schematic view of the internal structure of the delivery system of the present invention after loading the stent;

FIG. 5 is a schematic view of the internal structure of the delivery system of the present invention prior to loading the stent;

FIG. 6 is a schematic view of the internal configuration of the delivery system of the present invention with the stent partially extended from the sheath;

FIG. 7 is a schematic view of the internal structure of the delivery system of the present invention after loading the stent;

FIG. 8 is a schematic view of the internal structure of the delivery system of the present invention prior to loading the stent;

FIG. 9 is a schematic view of the internal configuration of the delivery system of the present invention with the stent partially extended from the sheath;

FIG. 10 is a cross-sectional view of the tip portion of the sheath tube of the delivery system of the present invention.

Wherein,

200-sheath; 300-a scaffold; 102-a guide head;

103-core tube; 104-a mounting section; 105-a stent fixation head;

106-resistance reducing layer; 107-positioning grooves; 108-section of reduced flexural strength;

222-a helical wire; 223-reinforcing fibers.

Detailed Description

The invention is further explained below with reference to the drawings.

Fig. 1 shows a sheath core of the present invention, which includes a core tube 103, one end of the core tube 103 is a distal end for connecting an interventional device (hereinafter, taking a stent as an example), the other end is a proximal end, the distal end of the core tube 103 is connected with a stent fixing head 105, and the stent fixing head 105 is connected with a guiding head 102 through a mounting section 104 for sleeving a stent.

The bracket fixing head 105 is provided with a through hole and is a cylindrical structure formed by a head part with a slightly larger diameter and a tail part with a slightly smaller diameter, and the outer wall of one end of the bracket fixing head 105 is also provided with a positioning groove 107 matched with the bracket.

The core tube 103 is a hollow tube with a through hole through which a guide wire (not shown) is passed, and during surgery, the delivery system can be advanced along a track established by the guide wire into the surgical implantation site. The core tube 103 has a proximal end, here the end closer to the operating handle, and a distal end, here the end further away from the operating handle (not shown in the drawings).

An installation section 104 is arranged between the bracket fixing head 105 and the guide head 102, the installation section 104 is also a hollow pipe with a through hole, and the installation section 104 is communicated with the core pipe 103 through the through hole inside.

The guide head 102 is a dome-shaped conical structure, the dome of the guide head 102 has a streamline shape, the inner wall of a blood vessel can be prevented from being scratched, the whole conveying device can be guided to advance along the blood vessel, and the tail of the guide head 102 is of a planar structure and used for abutting against a stent.

As shown in FIG. 1, the portion of the core tube 103 near the distal end is a reduced bending stiffness section 108, and the reduced bending stiffness section 108 is attached to the stent fixing head 105 and has a length of 150mm, although the length can be set according to a specific surgical path.

The bending rigidity of the bending rigidity decreasing section 108 is the same at each point, and the bending rigidity ratio to the other parts of the core tube 103 (the parts other than the bending rigidity decreasing section 108) is 1: 4. The reduced bending stiffness sections 108 are welded to the rest of the core tube 103, although other connections are obviously possible, but it is ensured that the outside diameter is the same throughout the core tube 103.

In order to conveniently evaluate the bending rigidity ratio, the invention provides the following test method: according to the internal structure characteristics of the heart, a core tube with one end long enough is taken, the core tube is bent into a semicircle with the diameter R equal to 25mm, and the elastic thrust generated by one end of the semicircle is measured.

According to the formula of bending rigidity

Wherein K is the bending stiffness;

m is the applied torque;

theta is a rotation angle;

f is elastic thrust generated by one end of the semicircle;

d is the diameter of the semicircle, i.e. 50 mm.

The above formula yields: the bending rigidity has a linear proportional relation with the elastic thrust generated by one end of the semicircle, so the ratio of the elastic thrust value of the bending rigidity reducing section to the elastic thrust value of the other part of the core tube is the bending rigidity ratio.

Referring to fig. 2, the bending stiffness reduced section 108 of the core tube 103 is a helical tubular structure made of single-strand steel wires, which not only provides sufficient pushing force for the sheath core to push the stent into the valve implantation site, but also provides better radial flexibility for the sheath core to smoothly pass through the tortuous vasculature, and the other parts of the core tube 103 are helical tubular structures made of multiple-strand steel wires (or single-strand steel wires with thicker wire diameter), so as to ensure the variation of bending stiffness. The outer periphery of the core tube 103 (the bending rigidity reducing section is regarded as a part of the core tube) is covered with the resistance reducing layer 106, the resistance reducing layer 106 is made of tetrafluoroethylene material, the friction force between the core tube 103 and the sheath tube can be reduced, the movement is smoother, the release and the positioning of the support are convenient, and the thickness of the resistance reducing layer is generally adapted to the gap between the core tube 103 and the sheath tube, so that the sheath tube is prevented from being bent. As shown in fig. 2 to 3, the resistance-reducing layer 106 is completely attached to the outer peripheral surface of the core tube 103, the thickness of the resistance-reducing layer is generally 0.01 to 0.2mm, and the thickness of the resistance-reducing layer generally refers to the difference (H) between the highest point of the resistance-reducing layer and the highest point of the outer surface of the core tube.

The resistance reducing layer 106 is typically made of tetrafluoroethylene, and for ease of processing, the resistance reducing layer 106 may be a tetrafluoroethylene tube.

Fig. 4-6 illustrate a delivery system for valve replacement surgery provided by the present invention, including a sheath 200 and a sheath core positioned within the sheath 200. In this delivery system, the sheath core is of the above-mentioned structure, the sheath 200 is required to maintain the necessary tensile strength, and the internal patency is also avoided when the sheath is bent, therefore, referring to fig. 10, the helical wire 222 is distributed around the axis of the sheath 200 in the sheath 200, and when the sheath 200 is bent, the helical wire 222 can support the shell thereof to maintain the internal patency. The sheath 200 also has a net-shaped reinforcing fiber 223 distributed therein, so that it can maintain a high tensile strength and avoid unnecessary deformation.

Fig. 4 shows the stent installed in the delivery system with the stent 300 compressed by the sheath 200. fig. 6 shows that the sheath 200 can slide axially relative to the other components, sliding backwards away from the guide head 102, gradually exposing the stent 300 for release.

When the bracket 300 is used, the bracket 300 is firstly loaded on a conveying system, the bracket fixing head 105 firstly extends out of the sheath tube 200, the guide head 102 penetrates through the bracket 300, the bracket 300 is fixed in the positioning groove 107 on the outer wall of the bracket fixing head 105, and then the sheath tube 200 completely wraps the bracket 300.

After the stent 300 is loaded, the delivery system is delivered to the valve implantation site along with the stent 300 along the already established guidewire track. After the delivery system reaches the implantation site, the sheath 200 is withdrawn for a certain distance, so that the stent 300 is partially exposed in the human environment for positioning, and after the positioning is completed, the stent 300 is continuously released, and the released stent 300 can expand under the action of the body temperature and is fixed at the implantation site to replace the autologous valve to perform the function. In the relative sliding process of the sheath core and the sheath tube, the resistance reducing layer plays a role in buffering and reducing sliding friction, so that the release of the bracket is easier.

Taking the replacement of the pulmonary valve as an example, after entering the right atrium from the femoral vein, the stent needs to turn once and then passes through the tricuspid valve to enter the right ventricle, and then needs to turn again to enter the pulmonary valve in sequence, and the bending rigidity reducing section is in an S shape after turning twice, and the bending rigidity reducing section has better compliance relative to other parts of the core tube, so the stent is more convenient to be in place in the delivery stage, and the sheath tube can be smoothly withdrawn relative to the sheath core when the stent is released, thereby avoiding scraping and even butting.

Claims

1. A sheath core comprises a core tube, wherein one end of the core tube is a far end used for being connected with an interventional instrument, and the other end of the core tube is a near end; characterized in that the core tube has a reduced bending stiffness section adjacent to the distal end, the reduced bending stiffness section having a length of 125-175 mm.

2. The sheath-core of claim 1, wherein the reduced bending stiffness section is of a helical tubular structure having the same outer diameter as the rest of the core tube.

3. The sheath-core of claim 1, wherein the reduced bending stiffness section progressively reduces in bending stiffness in a distal direction.

4. The sheath-core of claim 1, wherein the bending stiffness of the reduced bending stiffness section is the same at each point.

5. The sheath-core of claim 3, wherein the bending stiffness ratio of the reduced bending stiffness section to the rest of the core tube is 1: 3 to 1: 6.

6. The sheath core according to any one of claims 1 to 5, wherein a stent fixing head is connected to a distal end of the core tube, and the stent fixing head is connected to a guide head through a mounting section for fitting a stent.

7. The sheath-core of claim 1 wherein the outer circumference of the core tube is coated with a drag reducing layer of tetrafluoroethylene material.

8. The sheath-core of claim 7 wherein the drag reducing layer has a thickness of 0.01 to 0.2 mm.

9. An interventional device delivery system comprising a sheath and a sheath core according to any one of claims 1 to 8 disposed within the sheath.