KR20120138976A - Bio-metallic tube type subsidiary stent for the treatment of peripheral neurovascular aneurysm and delivery system - Google Patents

Abstract

PURPOSE: A bio-metallic tube type subsidiary stent for treating peripheral neurovascular aneurysm and a delivery system for the same are provided to ensure sufficient tension to the columnar direction and sufficient flexibility to the longitudinal direction. CONSTITUTION: A bio-metallic tube type subsidiary stent includes a plurality of link parts(10) and band parts(20). The link parts are expanded to the columnar direction of the stent and become curved to form wave shapes along the longitudinal direction of the stent. The band parts are arranged at the middle parts of adjacent link parts and are expandable to the columnar direction. The link parts are integrated with the band parts. The connecting parts of the link parts and the band parts are < or >-shaped.

Description

Bio-Metallic tube type subsidiary stent for the Treatment of Peripheral Neurovascular Aneurysm and delivery system

The present invention relates to a stent, a tubular medical device used in the surgical procedure for minimally penetrating the human body for the treatment of aneurysms in cerebrovascular disease, and more specifically, the coil for embolization used for the treatment of cerebral aneurysm. The present invention relates to a stent that prevents deviation of the coil into the mother artery and maintains it normally without disturbing the flow of blood in the mother artery.

In addition, the present invention relates to a vascular stent used as an auxiliary for treating a cerebral aneurysm using a coil, and a stent that is coaxially inserted with a blood vessel and a stent deliverable microcatheter configured to be used in a surgical procedure.

In general, vascular disease is a general term for a disease of blood vessels. Sudden blood flow disorder is a disease that causes local neuropathy evaporation such as loss of consciousness, paraplegia, and speech impairment and, in severe cases, causes death. For example, a disease that causes abnormalities in the cerebrovascular system that supplies blood to the brain is called cerebrovascular disease.

Cerebrovascular disease is caused by ischemic diseases such as cerebral infarction caused by blood circulation obstruction due to blood clots accumulated in narrowed cerebral arteries, and astrocytes caused by cerebral aneurysms that explode when a part of the blood vessels swells like a balloon. There is a hemorrhagic disease such as arachnoid bleeding.

Cerebral aortic aneurysms are diseases in which the weak areas of the cerebrovascular that carry blood in the heart swell or otherwise swell, causing hemorrhagic disease.

In order to overcome this problem of cerebrovascular disease, a coil procedure has been used to insert a coil into the cerebral aneurysm to block the inflow of blood into the cerebral aneurysm and to color the inside of the cerebral aneurysm to prevent cerebral hemorrhage. However, when the neck diameter of cerebral aneurysm is large, the inserted coil may deviate to the mother artery. Therefore, a coil stent secondary stent is required to prevent deviation of the coil into the cerebral mammary artery after the coiling procedure. The present invention relates to an auxiliary stent for such coil embolization.

Intervention, an invasive procedure for the treatment of cerebral aneurysms, involves accessing the affected area by inserting a wire (guide wire), a small catheter, and a delivery wire with stents through the vessel under X-ray vision. After a path is secured by a metal stent to a diseased part, the blood flow is normalized, and a coil is treated to treat an aneurysm by inducing an embolic in the aneurysm through a stent mesh of a neck that is an entrance of a cerebral aneurysm.

In order for the stent to function stably during or after implantation, the elasticity, recoil, and collapse associated with flexibility and radial resistance to withstand blood vessels in the vessel Must have good resistance to

As the prior art of the stent, Korean Patent Publication Nos. 10-1999-010304 and 10-1999-0013858 (Korean Patent No. 10-0271231, registered date 2008.08.11) have been described in order to improve the flexibility of the stent. A stent with wavy protrusions is disclosed in a branch, and Korean Patent Publication No. 10-2001-0035531 (published on May 7, 2001) discloses a stent having improved longitudinal flexibility.

However, the prior arts do not satisfy the excellent flexibility in the longitudinal direction and the expandability in the longitudinal direction and the circumferential direction at the same time, there is a problem that it is difficult to apply to curved lumens or blood vessels.

Accordingly, the present invention has been invented to solve the above-described problems of the prior art, and an object of the present invention is to provide a stent capable of sufficiently satisfying the longitudinal force and the expansion force in the circumferential direction at the same time.

Another object of the present invention is to adjust the position of the stent even during the procedure by a stent pusher or the like, and the cell size and structure suitable for passing the coil catheter for inserting the color-only coil into the aneurysm into the cell of the stent of the present invention. It is to provide a stent having.

According to an aspect of the present invention for achieving the above objects, the stent of the present invention is a circumferentially expandable stent, after the expansion of the stent in the circumferential direction, bent to form a wave shape along the longitudinal direction of the stent And a plurality of link portions formed and a plurality of band portions arranged and connected in a center between adjacent link portions among the plurality of link portions and expandable in a circumferential direction, wherein the link portion and the band portion are integrally formed. Wherein, the link portion and the connecting portion of the band portion is formed to form a <or> shape, the band portion is characterized in that it is formed to form a> shape after expansion.

In the present invention, the plurality of link portions are formed such that the phase of the wave of the link portion is alternately located between the peaks and valleys along the circumferential direction of the stent, and both ends of the band portion are disposed in the same phase along the circumferential direction of the stent. Thus, one end may be connected to a hill or valley of one of the link portions of the plurality of link portions, and the other end may be respectively connected to a valley or hill of the link portion adjacent to the one of the link portions.

Eight bands are arranged along the circumferential direction of the stent, and the inner radius of curvature R1 of the central tip of the band portion of the compressed stent is 0.025 mm, and the outer radius of curvature R2 is 0.075 mm. The inner curvature radius R3 is characterized in that 0.025mm.

The band portion and the link portion can be manufactured by laser cutting the nitinol cylindrical tube, wherein the diameter of the nitinol cylindrical tube is characterized in that 0.525 ~ 0.6mm.

The end of the stent is preferably coiled platinum (Pt) wire which is an X-ray impermeable material.

According to another aspect of the present invention, a delivery system used for repositioning a stent upon insertion of the stent of the present invention into a human blood vessel includes a catheter, a delivery pusher wire, and a retrieval section (C). , X-ray opaque RO (radiopacity) is characterized in that it consists of a tip (D).

According to an embodiment of the present invention, since it is excellent in flexibility in the longitudinal direction compared to the conventional stents by the link portion forming a sinus shape after expansion, there is an advantage that it can be applied to curved blood vessels in which a cerebral aneurysm occurs. .

In addition, due to the configuration of the band portion, it can be crimped to a minimum range before expansion and at the same time, the mechanical properties of nitinol can exert sufficient expansion force in the vascular deployment or in the circumferential direction. Since the cell shape of the post stent is a closed cell structure, there is an advantage that a fine position adjustment is possible by using a delivery system including a catheter during the procedure.

Further, according to the shape and arrangement of the wave pattern of the link portion described above and the shape and arrangement of the band portion described above, each cell constituting the stent is a mixed type in which a so-called open cell and a closed cell are mixed. Because of the cell structure, the flexibility and the expansion force when compressing the stent is appropriate, in the case of the stent according to the present invention, there is an advantage that the coiling catheter for embolization has an optimal size of the cell area that can pass through the cell.

In addition, as described above, by winding a platinum (Pt) coil, which is an X-ray impermeable material, on the distal end portion or the link portion of the stent, there is an advantage that the stent position information can be confirmed in the procedure state and the X-ray transmission state.

Figure 1a is a state after the stent is expanded according to the present invention, Figure 1b is a case where there is no notch (notch) in the center of the link portion, Figure 1c is a view showing a case where there is a notch in the center of the link portion.
Figure 2a is a state before the stent is expanded according to the present invention, Figure 2b is a case where there is no notch in the center of the link portion, Figure 2c is a view showing a case where there is a notch in the center of the link portion.
FIG. 3 is an enlarged view of portion A of FIG. 2A.
4 is a view showing that the coil for aneurysm embolization is inserted through a cell of the stent according to the present invention.
5 is a diagram of a platinum coiling marker for improving X-ray opacity.
6a and 6b are views showing that the radius of the adjacent circle inside the cell of the stent according to the present invention is R: 0.86, R: 0.81, respectively,
FIG. 7 illustrates a cantilever beam for flexibility evaluation. FIG.
8 is a diagram illustrating a stent compression model for evaluating expansion force.
9 is a view showing the evaluation of the expansion force of the stent according to the present invention.
10 is a view showing the evaluation of the flexibility of the stent according to the present invention.
11 is a view showing after the expansion of the stent according to the prior art.
12 is a view showing the evaluation of the expansion force of the conventional stent.
13 is a view showing the evaluation of the flexibility of the conventional stent.
14 shows a delivery system in which the stent of the present invention is inserted and delivered. The upper figure shows a microcatheter and the lower figure shows a delivery wire for moving the stent.
FIG. 15 is a diagram showing detailed structure names and specifications of the catheter of the FIG. 14 delivery system into which the stent is inserted.
FIG. 16 illustrates a delivery pusher wire of the FIG. 14 delivery system for moving the stent.

Hereinafter, with reference to the accompanying drawings will be described in detail the operation of the embodiment according to the present invention. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

Figure 1 shows after the expansion of the compressed stent according to the invention, Figures 2 and 3 shows before the stent according to the invention is expanded, Figure 4 shows the stent produced by the present invention and the cells of the stent The embolization coil is inserted into the cerebral aneurysm through, and FIG. 5 illustrates a delivery system in which the stent of the present invention is inserted and delivered.

The stent according to an embodiment of the present invention has been described as an example of a self-expanding stent using a nitinol alloy as a shape memory material. However, the present invention is not limited thereto, but may be applied to a stent applied to balloon dilation.

As shown in Figures 1 to 3, the stent 1 according to the present invention is composed of a plurality of link portions 10 and a plurality of band portions 20, and has a net-shaped cylindrical shape in which both ends are open as a whole. It is coming true.

Each of the plurality of link portions 10 is bent to form a sinus curve along the longitudinal direction of the stent 1 when the stent 1 of the present invention is expanded.

In addition, the plurality of link portions 10 are formed such that peaks and valleys are alternately located along the circumferential direction of the stent 1 in the phase of the wave of each link portion 10. That is, as shown in FIG. 1, when viewed along an imaginary circumference at a predetermined distance L from one end of the stent 1, the phases of the waves of the link portions 10 are arranged so that the peaks and valleys alternate alternately. .

On the other hand, a plurality of band portion 20 is disposed between the link portion 10 adjacent to each other, is formed in a substantially <or> shape along the longitudinal direction of the stent (1) to be able to expand in the circumferential direction of the stent (1). .

As shown in Figures 1 to 3, both ends of the <or> shape of the band portion 20 is connected to each of the plurality of link portions 10, the stent 1 of the present invention by the self-expansion force after compression It expands, and after expansion, it is formed to have a substantially <-shape.

In the present embodiment, eight band portions 20 are arranged along one circumferential direction of the stent 1, and as can be seen from FIG. 4, the central tip portion 21 of the band portion 20 of the compressed stent is provided. ), The inner curvature radius R1 is 0.025 mm, and the outer curvature radius R2 is 0.075 mm.

In addition, both ends of the band portion 20 are installed to be located at the same phase along the circumferential direction of the stent 1, one end of which is the peak or valley of any one of the link portion 10 of the plurality of link portions 10; Is connected to, the other end is configured to be connected to each of the valleys or hills of the link portion 10 adjacent to any one of the link portion 10.

That is, in FIG. 1, the upper end of the band portion 22 is connected to the wavy portion 12a of the wavy link portion 12 of the upper link portion 12 in the drawing, and the lower end is connected to the peak of the lower link portion 13. It is configured to be connected to the portion 13a.

By the configuration and arrangement of the link portion 10 and the band portion 20 as described above, as shown in Fig. 3, when the stent 1 is manufactured, that is, before the expansion of the stent 1, the link portion ( 10) and the band part 20 can be optimally arranged, and the band part 20 and the link part 10 can be disposed so that the micro-catheter for the coil can pass between the cells 30 of the stent 1 during the color only coil procedure. It can be optimally placed.

Moreover, the link part 10 and the band part 20 are integrally formed, and the connection part of the link part 10 and the band part 20 is formed so that it may become << shape as shown in FIG. Accordingly, at the time of manufacture, the link portion 10 having a smooth unevenness as shown in FIG. 3 is a link portion 10 during a heat shaping processing, which is a process for obtaining a shape after the expansion of the stent 1. In addition, the angle between the hill or valley portion of the link portion 10 and the link portion 10 and the band portion 20 is configured to form a sinus curve while expanding by the band portion 20 connected integrally with Even if it is narrowed or widened, the excessive stress is not concentrated at the branched portion and is configured to smoothly expand.

In the present embodiment, the inner curvature radius R3 of the connection portion between the link portion 10 and the band portion 20 is 0.025 mm.

By the above configuration, before the expansion of the stent (1) can be compressed to the minimum range and at the same time can exert the maximum expansion force in the circumferential direction, after the expansion the central tip 21 or the link portion of the band portion 20 The connection portion 10 and the band portion 20 are formed to have a <or> shape, and thus fine position adjustment is possible by using a hook or a pusher of a delivery device such as a catheter during the procedure.

In addition, in the stent (1) according to the present invention, the band portion 20, which gives an expansion force during compression and serves as a strut, is disposed between two link portions 10 adjacent to each other, and two band portions adjacent to each other ( 20 defines one cell 30.

The cell 30 of the stent 1 of the present invention has a structure in which the cell of the stent according to the prior art shown in FIG. 11 is closed, that is, a closed cell, and the band part 20 has a central tip 21. Bent at the both ends of the band portion 20 are connected to the hills or valleys of the link portion 10 on the same position line from the end of the stent 1, so-called open and closed cells. ) Forms a hybrid cell type and has a heart-shaped cell.

Accordingly, since the link portion 10 forming the sinus form is not directly connected to the adjacent link portion 10, but the center portion is connected by the bent band portion 20, the link portion 10 Flexibility is not limited or hindered by adjacent link portions 20.

Therefore, the flexibility in the longitudinal direction of the stent according to the present invention is superior to the flexibility in the longitudinal direction of the stent according to the prior art, and can be applied to curved lumens.

On the other hand, the diameter of the cylinder formed by the stent (1) is a value that takes into account the diameter of the blood vessels after the thickness and narrowing of the cerebral blood vessel in which the aneurysm occurred. The diameter of the nitinol tube, which is the raw material on which the stent 1 was manufactured, was 0.525 to 0.6 mm, and the diameter of the stent 1 after expansion was 4 mm and 5 mm.

The stent 1 is a biocompatible metal having biocompatibility and super-elasticity. The stent 1 is formed by cutting a laser into a tube made of a material such as a shape memory alloy, for example, a nitinol alloy, shaping, A cylindrical tube shape is manufactured by forming the shape of the link portion 10 and the band portion 20 through electropolishing or the like. Here, the thickness of the tube that becomes the thickness of the link portion 10 and the band portion 20 is set to 0.08 mm. In addition, the nitinol tube has a diameter of 0.5 to 0.6 mm, and the laser processed tube has a desired stent shape through heat shaping. In addition, etching and electropolishing operations are performed to treat the stent surface, and platinum (as a radiopacity marker) on the crowns of both ends of the stent to increase the radiopacity of the stent when inserted into the body. It is preferable to coil Pt). Of course, in addition, it may be a platinum wire made of a radiopaque material or gold, tungsten, tantalum and an alloy. In FIG. 5, a nitinol tube having a diameter of 0.525 mm was used for preparing the stent, and the end of the stent was coiled with platinum (Pt) wire, which is an X-ray impermeable material.

The coil catheter for coil insertion passes through the cell 30 of the stent 1 of the present invention. In order to prevent the inserted coil from deviating from the aneurysm to the mother artery, an appropriate size after the expansion of the stent 1 is achieved. It must have a cell size of.

In the case of the stent 1 of the present invention, the area of the cell 30 may be adjusted by adjusting the length of the link portion 10. 6A and 6B show the expanded stent. When the circle of the coil catheter cross section is shown in the cell 30, the stent 1 can be manufactured while maintaining the radius R of the circle at about 0.7 to 0.9 mm which is slightly larger than the diameter of the coil catheter.

(Flexibility test and expansion force evaluation)

In order to judge the flexibility, one end of the stent 1 is fixed, and the deflection amount d is calculated by computer finite analysis (FEM) when the load P is applied to the other side. The method of obtaining the bending stiffness was chosen.

In this case, the smaller the bending stiffness value EI is, the more flexible it can be. As shown in FIG. 7, it is assumed that the stent is assumed to be a cantilever beam like a cantilever beam, and the flexibility is determined by the bending stiffness. The bending stiffness (EI) of the stent 1 is the stent. It becomes one of the physical-property values fixed by the shape of (1).

The specific bending stiffness value EI is expressed as in Equation 1 below.

EI = PL ³ / 3d (Equation 1)

In Equation 1, P is a load, L is the length of the stent, d represents the amount of deflection.

The flexibil- ity test calculates the deflection, d, when the end of the stent is fixed and the load P on the other side, through structural analysis, and obtains the bending stiffness from these values.

In addition, the evaluation of the expansion force after the compression of the stent was fixed to the lower part of the stent, the load was applied to the upper part P. At this time, the expansion force of the stent was evaluated by the decrease in diameter, and the smaller the radial displacement value (RD) with respect to the load, the better the expansion force.

Computer simulations (FEM) evaluated the stent model as a decrease in the radial direction when an external pressure of 100 KPa was applied. As shown in FIG. 8, when the same pressure is applied in the load direction, the smaller the reduction amount for the diameter, the greater the expansion force. That is, the smaller the length of displacement of the compressed radius, the greater the expansion force. The greater the swelling force, the greater the stent's resistance to blood vessels.

The method for evaluating the flexibility and expansion force of the stent according to the present invention will be described in detail with reference to FIGS. 9 and 10.

The expansion force of the stent according to the present invention was evaluated by compression (100 KPa) to a stent having a diameter of 5 mm, a thickness of 0.08 mm, and a total length of 26.7 mm, as shown in FIG.

Flexibility of the stent according to the present invention was evaluated as shown in Fig. 10 as a result of bending the stent having a total length (26.7mm), thickness (0.08mm), the width of the link portion and the band portion of 0.05mm with 0.1N force.

In contrast, in the case of evaluating the expansion force of the conventional stent, the change in length was measured by applying pressure (100 KPa) to a stent having a diameter of 4 mm, a thickness of 0.08 mm, and a total length of 21 mm, and the result can be confirmed from FIG. 12.

In the case of the flexibility evaluation of the conventional stent, the diameter 4mm, total length (21mm), thickness (0.08mm), the stent was bent by computer simulation with 0.1N force, the results can be seen from FIG.

Table 1 shows the results of evaluating the flexibility and the expansion force of the stent according to the prior art and the stent according to the present invention.

Stent name Strut
Thickness
(mm) Expanded
Diameter
(mm) Total
Length
(mm) Material Bending
Stiffness
(EI) Expanding
Force
(Expansion) Cell type Conventional stent
Enterprise
( Cordis ) 0.09 4 21 Ni-Ti 4.25E-04 1.25E-5 Closed NV -A-01 0.08 5 26.7 Ni-Ti 5.62 E-05 1.46E-5 Hybrid

As shown in Table 1, the stent according to the present invention can be seen that the expansion force is similar to the conventional stent but excellent in flexibility. Therefore, it can be said that it has superior performance compared to the conventional stent.

On the other hand, Figure 14 is a delivery system (delivery system) in which the stent is inserted and delivered according to the present invention, Figure 15 shows a catheter, Figure 16 shows a delivery pusher wire (delivery pusher wire). The delivery system of the present invention is used for repositioning when the stent of the present invention is inserted into human blood vessels, and includes a catheter, a delivery pusher wire, a retrieval section (C), and an X-ray light. It consists of a radiopacity (RO) tip (D) that is permeable. In the case of the delivery system of the present invention, as shown in Fig. 14, the outer diameter of the distal section of the catheter is smaller than 3F or less, and the inside of the catheter is braiding nitinol metal. It is divided into one part and coiled part to have both intravascular tractability and flexibility.

As such, the delivery system of the present invention enables repositioning when the stent is not mounted at a desired position during surgery by a retrival section C in the pusher wire.

Specifically describing the function of the pusher wire, the wire is slightly stiff in order to facilitate the movement of the straight portion in the blood vessel below the portion A in FIG. 16. However, sections A and B are coiled with thin wires for easy movement of the bent blood vessels, and are highly flexible. The platinum (Pt) coiling marker of the stent is located between B and C, and is fixed between B and C until the sheath of the micro-catheter is peeled off to the C part, thereby retracting the stent and recovering the stent. Upon completion, the stent can be redeployed by moving the catheter to the modified lesion site. This operation is called stent repositioning. Part D is a coiled platinum wire to check the position of the transfer wire and stent in the human body, and coiled to move the cerebrovascular flexibly.

On the other hand, the principle of positioning the stent through the delivery system is that if the tip of the delivery wire is distal, the platinum coil is placed on the stent in an empty space opposite the end of the retrieval section. The wound coiling marker portion is positioned and then the stent is crimped and inserted into the micro catheter. Since the marker part is sandwiched between the recovery part and the pusher part, the stent is fixed to the transfer wire unless the outer sheath of the microcatheter is completely removed to the position of the pusher and the stent is not deployed. In addition, when the transfer wire is pulled again, the stent is retracted to be inserted back into the catheter's shell, and the stent-containing catheter can be repositioned according to the lesion position.

As described above is only one preferred embodiment of the stent according to the present invention, the present invention is not limited to the above embodiment, without departing from the gist of the present invention as claimed in the following claims Anyone with ordinary knowledge in the field of the present invention will have the technical spirit of the present invention to the extent that various modifications can be made.

1: stent 10: link part
20: band portion 21: central tip portion
30: cell

Claims (7)

A circumferentially expandable stent,
After the expansion of the stent in the circumferential direction, a plurality of link portions are bent to form a wave shape along the longitudinal direction of the stent,
It is configured to include a plurality of bands arranged and connected in the center between the link portion adjacent to each other of the plurality of link portion, the circumferential direction,
The link portion and the band portion are formed integrally,
The link portion and the connection portion of the band portion is formed to form a <or> shape,
The band portion is formed to form a> -shaped after expansion
Stent.
The method of claim 1,
The plurality of link portions are formed such that peaks and valleys of the link portions are alternately located along the circumferential direction of the stent.
Both ends of the band portion are installed in the same phase along the circumferential direction of the stent, one end is connected to the peak or valley of any one of the plurality of link portions, the other end is any one of the links Characterized in that connected to each of the valleys or mountains of the link portion adjacent to the portion
Stent.
The method of claim 1,
Eight of the bands are arranged along the circumferential direction of the stent, and the inner radius of curvature R1 of the central tip of the band portion of the compressed stent is 0.025 mm, the outer radius of curvature R2 is 0.075 mm, and the link portion is connected to the band portion. Inner curvature radius R3 of the portion is characterized in that 0.025mm
Stent.
The method of claim 1,
The band portion and the link portion is characterized in that for manufacturing by laser cutting the nitinol cylindrical tube
Stent.
The method of claim 4, wherein
The diameter of the nitinol cylindrical tube is characterized in that 0.525 ~ 0.6mm
Stent.
The method of claim 1,
The end of the stent is to coil the platinum (Pt) wire which is an X-ray impermeable material
Stent.
A delivery system used for repositioning of the stent when the stent is inserted into the human blood vessel according to any one of claims 1 to 6,
Catheter, delivery pusher wire, retrieval section (C), X-ray impermeable radiopacity (RO) tip (D), characterized in that
Delivery system.

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