CN111672010A

CN111672010A - Micro-catheter

Info

Publication number: CN111672010A
Application number: CN202010677736.8A
Authority: CN
Inventors: 红好; 王吉成; 蔡传奇; 宋东辉; 邢岩鹏; 张新波
Original assignee: Hemu China Biological Engineering Co ltd
Current assignee: Hemu China Biological Engineering Co ltd
Priority date: 2020-07-15
Filing date: 2020-07-15
Publication date: 2020-09-18

Abstract

The invention provides a micro-catheter which comprises an inner tube and an outer tube sleeved outside the inner tube, wherein the outer diameter of the outer tube gradually becomes thicker from the far end to the near end, an intermediate layer is arranged between the inner tube and the outer tube, and the wall thickness of the inner tube at the far end is smaller than that of the inner tube at the near end. The invention has the advantages that by adopting the technical scheme, the micro catheter can provide durable and stable near-end support, good pushing property and torsion transmission effect, excellent far-end lumen shape retention force and excellent far-end tensile property.

Description

Micro-catheter

Technical Field

The invention relates to the technical field of medical instruments, in particular to a micro catheter.

Background

The microcatheter is a medical instrument commonly used in interventional therapy, and the application range thereof comprises: complex lesions such as completely occluded or sub-completely occluded lesions, bifurcation lesions, severe calcified lesions, and severe twisted lesions.

The known methods for treating ischemic stroke and cerebral thrombosis can be carried out by means of thrombolytic drugs, intervention, and the like. In the interventional approach, a channel is established between the outside of the body and the location of the intravascular lesion in order to reach the location of the intravascular lesion, usually by means of a microcatheter.

Because the micro catheter needs to shuttle in the blood vessel and cope with various complex intravascular environments, the flexibility, the pushing anti-torsion performance, the tensile performance and the like of the micro catheter are indexes representing the performance of the micro catheter.

When the microcatheter goes to a target blood vessel region, the microcatheter cannot pass through a certain region at one time when encountering the conditions of blood vessel bifurcation, lesion, embolism and the like, needs to be pulled to the near end, and then goes forward in the blood vessel again after being temporarily withdrawn; or after the microcatheter is used, the microcatheter is pulled outwards, and in the process, the microcatheter is required to have certain tensile property. Especially at the distal end of the microcatheter, tensile properties are particularly important. For reasons of improved passability and pushability, the outer diameter of the microcatheter is generally gradually thicker from the distal end to the proximal end, the thinner distal end has a smaller tensile strength than the proximal end in most cases, and the distal end of the microcatheter has a certain risk of breaking when a tensile force that can be withstood by the proximal end is applied to the proximal end.

In addition, the microcatheter with excellent performance should also ensure good flexibility, kink resistance and ovality resistance at the distal end, while higher pushability and kink resistance are required at the proximal end.

Flexibility refers to the performance of the catheter in bending bifurcated vessels, lesions and embolism; passability refers to the smooth nature of reaching a given location or removing a catheter through a blood vessel; pushability refers to the pushing force applied by the operator at the proximal end of the catheter in order to bring the distal end of the catheter to a given position; kink resistance refers to the ability to twist the proximal end of the catheter without kinking the catheter as a whole; the tensile property means that each section of the conduit needs to meet a certain peak breaking force so as to ensure that the conduit does not break in the process of pushing or taking out the conduit; ovality refers to the resistance of the catheter to crushing deformation.

Disclosure of Invention

The present invention is directed to a microcatheter having excellent tensile properties and flexibility at the distal end and excellent pushability and ovality resistance at the proximal end.

The technical scheme of the invention is as follows:

a microcatheter comprises an inner tube and an outer tube sleeved outside the inner tube, wherein the outer diameter of the outer tube becomes thicker gradually from the far end to the near end, an intermediate layer is arranged between the inner tube and the outer tube, and the wall thickness of the inner tube at the far end is smaller than that of the inner tube at the near end.

In one aspect of the present invention, the substrate is,

the wall thickness of the inner tube becomes thinner gradually from the far end to the near end;

in another aspect of the present invention, there is provided,

the inner pipe comprises a thick section, a gradual change section and a thin section in sequence in the direction from the far end to the near end, the thickness of the inner pipe wall of the thick section is smaller than that of the inner pipe wall of the thin section, and the thickness of the inner pipe wall is gradually transited in the gradual change section.

The size of inner tube limited inner chamber, the material of inner tube is polytetrafluoroethylene, and the inner chamber is the passageway that seal wire and various apparatus got into the blood vessel from the distal end, and polytetrafluoroethylene friction coefficient is low, and surface tension is little, has better propelling movement effect. More importantly, the polytetrafluoroethylene has excellent tensile property, and the increase of the wall thickness of the inner tube at the far end has important significance for improving the overall tensile property of the far end of the microcatheter. The wall thickness of the inner tube is gradually thinned from the far end to the near end, so that the peak breaking force at the far end and the peak breaking force at the near end are basically equal, a stress concentration area is avoided, and the micro catheter is prevented from breaking under extreme conditions.

The intermediate layer mainly serves as a support.

The microcatheter sequentially comprises a distal end part, an overlapping part and a proximal end part in the direction from the distal end to the proximal end, wherein the middle layer of the distal end part is a spring ring, the middle layer of the proximal end part is a braided fabric, and the middle layer of the overlapping part is a double-layer structure of the braided fabric covering the spring ring.

Preferably, the length of the overlapping portion is not less than 1 cm.

The middle layer is used for reinforcing the catheter, the braided fabric reinforcing catheter has the advantages that the torque transmission effect is good, the braided fabric is arranged at the near end, so that the torque transmission efficiency of the near end and the far end is higher, and the supporting force of the near end is good. If the braid is placed at the distal end, ovalization tends to occur as the distal end passes through a tortuous path, and therefore, the intermediate layer is provided with a kink-resistant, ovalization-resistant coil at the distal end.

During manufacturing, the spring ring and the braided fabric are tightly wound and attached on the inner tube, and the spring ring and the braided fabric are fixed on the inner tube by using a proper amount of adhesive. Then the outer pipe is sleeved on the middle layer, and the protective pipe is sleeved on the outer pipe. The whole guide pipe is heated, the protective pipe can protect the outer pipe from being melted and the middle layer from being melted into a whole (the middle layer can not be exposed on the surface of the outer pipe), and finally the protective pipe is removed from the outer pipe.

The coil includes a distal section and a proximal section in a distal to proximal direction, the coil pitch of the coil of the distal section being greater than the coil pitch of the proximal section, the braid includes a distal section and a proximal section in a distal to proximal direction, the braid density of the proximal section being greater than the braid density of the distal section.

The micro-catheter has better supporting force due to small spring pitch and high weaving density; the micro-catheter has better flexibility due to small weaving density and large spring pitch. The utility model discloses a little pipe, including the overlap portion, the overlap portion is equipped with the spring coil, the spring coil is equipped with the knitting, the overlap portion is equipped with the spring coil, the near-end knitting, the knitting covers the spring coil at the overlap portion, the spring coil is on far-end to near-end direction, spring coil pitch reduces gradually, the knitting is on far-end to near-end direction, the density of knitting crescent, above-mentioned setting can make little pipe's far-end to near-end at the even transition of overlap portion.

The coils of the intermediate layer of the distal section are wound from at least 2 spring wires.

One of the spring rings is made of any one of platinum-iridium alloy, gold, tantalum-plated stainless steel and tungsten film stainless steel.

Compared with the design that the developing ring is only arranged at the end part of the micro catheter in the prior art, the developing effect of the invention is better, and the position of the micro catheter can be conveniently tracked by a doctor in the operation.

Preferably, the material of at least 2 weaving wires in the weaving fabric is any one of platinum-iridium alloy, gold, tantalum-plated stainless steel and tungsten film stainless steel.

The microcatheter sequentially comprises a TPU section, a Pebax section and a PA section from the far end to the near end, wherein the outer tube of the TPU section is made of TPU, the outer tube of the Pebax section is made of Pebax, and the outer tube of the PA section is made of PA.

The TPU is a thermoplastic polyurethane elastomer rubber, is a high polymer material between rubber and plastic, has wide hardness range, can obtain products with different hardness by changing the proportion of each reaction component of the TPU, and still keeps good elasticity and wear resistance along with the increase of the hardness. And has high tensile strength, large elongation and low long-term compression set.

Pebax is a trade name determined by ATOFINA company of France for a block polyether amide resin product, and is a substitute name of the block polyether amide resin because the utilization rate in the field of medical appliances is very high. It is the lightest engineering thermoplastic elastomer with the following characteristics: good and stable consistent performance at low temperatures; no loss of mechanical properties under repeated deformation and fatigue resistance; good resilience and elastic recovery; precise dimensional stability; excellent processing performance. Is the first major plastic variety in the fields of food packaging, sports goods, medical appliances and the like.

PA is short for polyamide and is commonly called nylon. Has good comprehensive properties including mechanical property, heat resistance, abrasion resistance, chemical resistance and self-lubricity, and has low friction coefficient. And the variety is various, and different requirements in various industry fields can be met.

Furthermore, in the direction from the far end to the near end, the Pebax section comprises a second section, the middle section sequentially comprises a third section, a fourth section and a fifth section, the near end section sequentially comprises a sixth section and a seventh section, and the shore hardness of the outer tube of the second section is smaller than that of the outer tube of the third section, smaller than that of the outer tube of the fourth section, and smaller than that of the outer tube of the fifth section, and smaller than that of the outer tube of the sixth section, and smaller than that of the outer tube of the seventh section.

The length of the PA section is 70-85 cm.

In an alternative aspect of the invention, the intermediate layer is a coil comprising a distal section and a proximal section in the distal to proximal direction, the coil pitch of the distal section being greater than the coil pitch of the proximal section.

In an alternative aspect of the present invention, the intermediate layer is a braid comprising a distal section and a proximal section in a distal to proximal direction, the braid density of the proximal section being greater than the braid density of the distal section

The invention has the advantages and positive effects that: due to the adoption of the technical scheme, the micro-catheter can provide durable and stable near-end support, good pushing performance and torque transmission effect, excellent far-end official cavity shape retention force and excellent far-end tensile property.

Drawings

FIG. 1 is a schematic view of the structure of the present invention in which the intermediate layer is a mixture of a coil and a braid

FIG. 2 is a schematic view of a radial cross-section of a microcatheter

FIG. 3 is a schematic representation of a taper in wall thickness from the distal end to the proximal end of the inner tube

FIG. 4 is a schematic representation of a distal to proximal intermediate layer

FIG. 5 is a schematic view of the configuration of the coil in the middle layer at the distal end portion

FIG. 6 is a schematic view of the structure of the braid in the intermediate layer of the proximal section

FIG. 7 is a schematic diagram of the structural principle of the present invention in which the middle layer is a coil only

FIG. 8 is a schematic view of the structural principle of the present invention in which the middle layer is only a braid

In the figure:

1. distal section 2, overlap section 3, proximal section

4. Inner tube 5, intermediate layer 6, outer tube

7. Spring ring 8, braided fabric

Detailed Description

As shown in FIG. 2, the present invention

A microcatheter comprises an inner tube and an outer tube sleeved outside the inner tube, wherein the outer diameter of the outer tube gradually becomes thicker from the far end to the near end, and an intermediate layer is arranged between the inner tube and the outer tube;

as shown in fig. 3, the inner tube wall thickness at the distal end is less than the inner tube wall thickness at the proximal end.

As shown in FIG. 1, the microcatheter comprises a distal portion, an overlapping portion and a proximal portion in sequence from the distal end to the proximal end, the middle layer of the distal portion is a coil, the middle layer of the proximal portion is a braid, and the middle layer of the overlapping portion is a double-layer structure in which the braid covers the coil.

As shown in fig. 4, 5, 6, the coil includes a distal section and a proximal section in the distal to proximal direction, the coil pitch of the coil of the distal section is greater than the coil pitch of the proximal section, and the braid has a gradually increasing braid density in the distal to proximal direction.

The spring ring is formed by winding 2 spring wires, one is made of platinum-iridium alloy and the other is made of nickel-titanium alloy.

In the direction from the far end to the near end, the microcatheter is sequentially divided into a TPU section, a second section, a third section, a fourth section, a fifth section, a sixth section, a seventh section and a PA section;

as the present application is directed to,

the unit of the knitting density is PPI, which is defined as the number of crossing points of knitting filaments contained in each inch of length, the larger the PPI value is, the larger the knitting density is, the smaller the PPI value is, the larger the knitting density is; the pitch of the spring is the axial distance between the centers of two adjacent circles of the spring, also called the pitch, and the larger the pitch, the smaller the density of the spring, and the smaller the pitch, the larger the density of the spring.

Example 1

Example 2

Example 3

Example 4

Example 5

Example 6

EXAMPLES 1-6 Performance testing of microcatheters

All data are the test average of 22 test samples; a push-to-withdraw test is performed in a simulated blood vessel; kink resistance testing involves securing the distal end of the microcatheter and rotating the microcatheter luer hub or proximal end. Maximum number of turns of the microcatheter without kinking; the bending test is to surround the cylindrical tool for a whole circle respectively at the far end, the connecting section and the near end of the microcatheter and observe whether the phenomena of fracture, bending and the like occur.

Control group

Performance test data for control microcatheter

The control group was identical to example 5 except for the thickness of the inner tube.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims

1. The utility model provides a microcatheter, includes, the outer tube outside inner tube and cover inner tube, and the external diameter of outer tube is by distal end to near-end thickening gradually, is equipped with intermediate level, its characterized in that between inner tube and the outer tube: the distal end has a smaller inner tube wall thickness than the proximal end.

2. The microcatheter of claim 1, wherein: the microcatheter sequentially comprises a distal end part, an overlapping part and a proximal end part in the direction from the distal end to the proximal end, wherein the middle layer of the distal end part is a spring ring, the middle layer of the proximal end part is a braided fabric, and the middle layer of the overlapping part is a double-layer structure of the braided fabric covering the spring ring.

3. The microcatheter of claim 2, wherein: the coil includes a distal section and a proximal section in a distal to proximal direction, the coil pitch of the coil of the distal section being greater than the coil pitch of the proximal section, the braid includes a distal section and a proximal section in a distal to proximal direction, the braid density of the proximal section being greater than the braid density of the distal section.

4. The microcatheter of claim 3, wherein: the coil of the middle layer of the distal section is wound with at least 2 spring wires.

5. The microcatheter of any of claims 1-3, wherein: the microcatheter sequentially comprises a TPU section, a Pebax section and a PA section from the far end to the near end, wherein the outer tube of the TPU section is made of TPU, the outer tube of the Pebax section is made of Pebax, and the outer tube of the PA section is made of PA.

6. The microcatheter of claim 5, wherein: in the direction from the far end to the near end, the Pebax section comprises a second section, the middle section sequentially comprises a third section, a fourth section and a fifth section, the near end section sequentially comprises a sixth section and a seventh section, and the Shore hardness of the outer tube of the second section is smaller than that of the outer tube of the third section and smaller than that of the outer tube of the fourth section and smaller than that of the outer tube of the fifth section and smaller than that of the outer tube of the sixth section and smaller than that of the outer tube of the seventh section.

7. The microcatheter of claim 4, wherein: one of the spring rings is made of any one of platinum-iridium alloy and gold.

8. The microcatheter of claim 5, wherein: the length of the PA section is 70-85 cm.

9. The microcatheter of claim 1, wherein: the intermediate layer is a coil comprising a distal section and a proximal section in a distal to proximal direction, the coil pitch of the distal section being greater than the coil pitch of the proximal section.

10. The microcatheter of claim 1, wherein: the intermediate layer is a braid comprising a distal section and a proximal section in a distal to proximal direction, the proximal section having a braid density greater than the braid density of the distal section.