CN110811735A - A locally enhanced nickel-titanium alloy intracranial stent - Google Patents

Abstract

The invention relates to a locally enhanced nickel-titanium alloy intracranial stent, which can be used for assisting coil embolization in the treatment of intracranial aneurysm, and belongs to the field of medical devices. The main body of the intracranial stent is composed of a single rhombus unit composed of a sine wave structure and a connecting rod, and a tubular structure composed of a double rhombus unit formed by merging the two single rhombus units. The double diamond unit can improve the flexibility of the stent, and the single diamond structure can ensure the stable support performance of the stent to a certain extent. In addition, by adjusting the positions and numbers of units with different shapes, a variety of stent structures can be designed and changed to achieve different mechanical properties. The design of the locally enhanced Nitinol intracranial stent based on the hybrid unit structure can design an optimized unit ratio for different use environments, and realize the specific position (such as the tumor diameter at the premise of ensuring the compliance of the stent). ), which can be used to assist coil plugging.

Description

A locally enhanced nickel-titanium alloy intracranial stent

technical field

The invention relates to a locally enhanced nickel-titanium alloy intracranial stent, which can be used for assisting coil embolization in the treatment of intracranial aneurysm, and belongs to the field of medical devices.

Background technique

Intracranial aneurysm is an abnormal bulge of cerebral blood vessels caused by hypertension, atherosclerosis, potential vascular lesions, trauma, infection, tumor and other incentives, and is also the primary cause of hemorrhagic cerebrovascular disease. With the continuous innovation of endovascular interventional materials and the continuous development of related technologies, the treatment of intracranial aneurysms has become simpler and safer, and more intracranial aneurysms can be completely embolized by interventional means. However, for complex intracranial aneurysms, such as: huge, wide-necked, fusiform, dissection, and perforated vessels, interventional treatment is still very difficult; the existing products are difficult to coordinate flexibility and support performance, and the rigidity is large. The overall stiffness of the stent is poor after implantation, which can easily lead to excessive endothelial hyperplasia. Stents with good compliance often have insufficient supporting performance, and complications such as stent displacement, poor stent expansion, and collapse may occur in complex lesions.

SUMMARY OF THE INVENTION

The purpose of the present invention is to propose a local reinforced nickel-titanium alloy intracranial stent, which can be used to assist coil embolization. The intracranial stent includes a flexible double diamond unit and a strong support single diamond unit. By adjusting the position, shape and quantity ratio of different units, a variety of stent structures can be designed and changed to achieve different mechanical properties; under the premise of ensuring the compliance of the stent, the support of specific positions (such as the diameter of the tumor) can be enhanced. .

In order to achieve the above object, technical scheme of the present invention is as follows:

A locally reinforced nickel-titanium alloy intracranial stent. The main body of the intracranial stent is composed of a single diamond unit composed of a sine wave structure and a connecting rod, and a tubular structure formed by combining two single diamond units to form a double diamond unit.

In the locally reinforced nickel-titanium alloy intracranial stent, the single rhombus unit and the double rhombus unit are arranged in a central reinforcement manner, that is, a single rhombus unit structure is designed in the middle of the intracranial stent; the span of the single rhombus unit is >4mm, A single diamond-shaped unit occupies 12.5-50% of the surface area of the entire intracranial scaffold.

In the locally reinforced nickel-titanium alloy intracranial stent, the single rhombus unit and the double rhombus unit are arranged in a uniform reinforcement manner, that is, the single rhombus unit structure is uniformly filled on the entire surface of the intracranial stent, and the single rhombus unit occupies 0 to 33.3% of the entire intracranial stent surface area.

In the locally enhanced nickel-titanium alloy intracranial stent, in the process of merging the single diamond-shaped unit into a double diamond-shaped unit, the connecting rod of the original structure is retained, and the connecting rod is rounded, and the fillet radius is 0.02-0.05 mm.

In the locally enhanced nickel-titanium alloy intracranial stent, the ratio of the height dimension to the width dimension of the single rhombus unit composed of the sine wave structure and the connecting rod is 1-1.5.

In the locally enhanced nickel-titanium alloy intracranial stent, the sine wave structure wire width of the intracranial stent is 0.03-0.07 mm, the height of the connecting rod is 0.05-0.1 mm, and the width is 0.05-0.1 mm.

In the locally enhanced nickel-titanium alloy intracranial stent, the vertices of the units at both ends of the intracranial stent are semi-circular arc structures, and the diameter of the arc is 0.15-0.25 mm.

The locally enhanced nickel-titanium alloy intracranial stent has a wall thickness of 0.05-0.085 mm, a length of 15-40 mm, and a nominal diameter of 2-7 mm.

In the locally enhanced nickel-titanium alloy intracranial stent, the intracranial stent is made of superelastic nickel-titanium alloy material, and its elasticity range is 10% to 15%.

The design idea of the present invention is:

The present invention designs the overall structure of the intracranial artery stent based on the hybrid unit method. First, a diamond-shaped unit and a double-diamond-shaped unit composed of a sine wave structure and a connecting rod are designed. Different mechanics can be obtained by adjusting the wire width of the unit and the aspect ratio. Support strength. The double diamond unit gives the stent better flexibility, and the single diamond unit improves the stability and support strength of the stent to a certain extent, and can achieve mechanical enhancement to a specific position. The present invention designs two typical hybrid cell arrangements: central reinforcement and uniform reinforcement. The design method of central reinforcement is to add a certain number of single diamond structures in the middle of the intracranial stent. By adjusting the span and density of the single diamond units in the middle, different mechanical properties of the stent can be achieved. The intracranial stent reinforced in the middle can provide strong support at the neck of complex aneurysms such as giant arteries and wide-necked aneurysms, and effectively support the parts that need to be over-packed with coils to prevent stent expansion. Bad or collapsed. The method of uniform reinforcement is to uniformly add single diamond-shaped units on the entire surface of the intracranial stent. The uniformly reinforced intracranial stent can increase the radial support force on the basis of maintaining the flexibility of the stent, enhance the fit of the stent to the blood vessel after release, and reduce the possibility of the stent being displaced when it is released into a blood vessel with a larger diameter. sex.

The advantages and beneficial effects of the present invention are embodied in:

1. The design method of the hybrid unit of the present invention can realize an intracranial stent with a combination of various unit structures, and the position and number of the hybrid unit can be adjusted according to different usage conditions to realize different mechanical properties of the intracranial stent.

2. The double diamond-shaped unit of the present invention increases the softness of the stent, and the single diamond-shaped unit improves the stability of the stent to a certain extent; therefore, the design method based on the combined unit can make the stent both flexible and supportive.

3. The intracranial stent reinforced in the middle of the present invention can provide a strong support force at the neck of complex aneurysms such as giant arteries and wide-necked aneurysms, and can effectively support the parts that need to be excessively stuffed with coils. Prevent the stent from under-expanding or collapsing. The uniformly reinforced intracranial stent can increase the radial support force on the basis of maintaining the flexibility of the stent, enhance the fit of the stent to the blood vessel after release, and reduce the possibility of the stent being displaced when it is released into a blood vessel with a larger diameter. sex. The design of the hybrid unit can expand the adaptability of a single stent and reduce the difficulty of surgical operation and the incidence of complications.

Description of drawings

Figure 1(a) is a schematic diagram of the structure of the intracranial stent unit, Figure 1(b) is an enlarged view of the details of the connecting rod of the stent, and Figure 1(c) is an enlarged view of the details of the connecting rod after the unit is merged. In the figure, 1 sine wave structure, 2 connecting rods, 3 single diamond units, 4 double diamond units, 5 connecting rod height, 6 connecting rod width.

Figures 2(a) to 2(d) are plan development views of the intracranial stent designed in Example 1. Among them, Fig. 2(a) is a simple double-diamond unit stent, Fig. 2(b) is a 8.3% single-diamond unit middle reinforced stent, Fig. 2(c) is a 16.7% single-diamond unit middle reinforced stent, and Fig. 2( d) is a 33.3% single-diamond unit middle reinforced bracket.

FIG. 3 is a graph showing the finite element simulation result of the bracket designed in Example 1. FIG. Among them, Figure 3(a) is a three-point simulation of the contact force cloud diagram of the indenter during the bending process of the four scaffolds (single double-diamond unit, 8.3% single-diamond unit, 16.7% single-diamond unit, and 33.3% single-diamond unit structure), and Figure 3(b) shows the contact force cloud diagram of the indenter during the simulated extrusion process of four scaffolds (simple double-diamond unit, 8.3% single-diamond unit, 16.7% single-diamond unit, and 33.3% single-diamond unit structure).

Figure 4(a) is a plan development view of the uniformly reinforced stent (20% single diamond unit structure) designed in Example 2, and Figure 4(b) is a physical view of the uniformly reinforced stent designed in Example 2.

FIG. 5 is the stress cloud diagram of the blood vessel after the stent is designed in Example 2 to simulate implantation. Among them, Fig. 5(a) is a blood vessel under the action of a 20% single-diamond unit uniformly reinforced stent, and Fig. 5(b) is a vessel under the action of a simple double-diamond unit stent.

FIG. 6 is a graph showing the results of the finite element simulation of the radial compression process of the stent designed in Example 3. FIG.

FIG. 7 is a graph showing the results of the finite element simulation of the radial compression process of the stent designed in Example 4. FIG.

Detailed ways

As shown in Fig. 1(a)-Fig. 1(c), the local reinforced nickel-titanium alloy intracranial stent of the present invention firstly designs a single diamond-shaped unit 3 composed of a sine wave structure 1 and a connecting rod 2. By adjusting the sine wave The wire width and aspect ratio of structure 1 can obtain different mechanical support strengths. Wherein, the wire width of the sine wave structure 1 is preferably 0.03-0.07 mm, the height dimension to width dimension ratio of the single diamond unit 3 is preferably 1-1.5; the connecting rod width 6 is preferably 0.05-0.1 mm, and the connecting rod height 5 is preferably 0.05～0.1mm. Two adjacent single diamond units 3 are merged to form a double diamond unit 4, the connecting rod of the original structure is retained during the merging process, and the connecting rod 2 is rounded, and the fillet radius is preferably 0.02-0.05mm.

There are various combinations of the single diamond unit 3 and the double diamond unit 4. The present invention designs two typical unit arrangements: 1. The design method of central reinforcement, that is, a certain number of single diamond units 3 are added to the middle of the intracranial stent. , to form a middle-enhanced intracranial stent. By adjusting the span and density of the single diamond-shaped unit 3 in the middle, different mechanical properties of the stent can be realized. The intracranial stent reinforced in the middle can provide strong support at the neck of complex aneurysms such as giant arteries and wide-necked aneurysms to prevent poor expansion or collapse of the stent. In the middle-enhanced intracranial stent, the span of the single diamond-shaped unit is more than 4 mm, and the single diamond-shaped unit accounts for 12.5-50% of the surface area of the entire intracranial stent. 2. The design method of uniform reinforcement, that is, the single diamond-shaped unit is uniformly filled on the entire surface of the intracranial stent. The uniformly reinforced intracranial stent can increase the radial support force on the basis of maintaining the flexibility of the stent, enhance the fit of the stent to the blood vessel after release, and reduce the possibility of the stent being displaced when it is released into a blood vessel with a larger diameter. sex. A single diamond-shaped unit occupies 0-33.3% (excluding 0) of the surface area of the entire intracranial stent, preferably 12.5-25%.

In order to prevent the top of the stent from being too sharp to damage the blood vessel during the stent release process, the vertices of the units at both ends of the intracranial stent are designed as semi-circular arc structures, and the diameter of the arc is preferably 0.15-0.25 mm.

After laser cutting on the nickel-titanium tube according to the set drawing, the final intracranial stent can be obtained after cleaning, heat treatment setting, polishing and cleaning again. According to the size characteristics of the intracranial blood vessel, the wall thickness of the intracranial stent is preferably 0.5-0.85 mm, the length of the intracranial stent is preferably 15-40 mm, and the nominal diameter of the stent is preferably 2-7 mm.

In the present invention, the definitions of related terms are as follows:

The height of a single rhombus unit refers to the height value of a single rhombus unit along the axial direction of the stent in the plan development view of the stent.

The width of a single rhombus unit refers to the width value of a single rhombus unit along a direction perpendicular to the axial direction of the stent in a plan development view of the stent.

The span of a single diamond unit refers to the projected distance along the stent axis between the geometric center of the single diamond unit closest to the proximal end of the stent to the geometric center of the single diamond unit closest to the distal end of the stent.

The height of the connecting rod refers to the height value of the connecting rod along the axial direction of the stent in the plan development view of the stent.

The width of the connecting rod refers to the width value of the connecting rod along the direction perpendicular to the axial direction of the stent in the plane development view of the stent.

The wire width of the sine wave structure refers to the minimum value of the length of the line connecting any two points on both sides of the sine wave structure.

Hereinafter, the technical solutions of the present invention will be further described with reference to the embodiments and the accompanying drawings.

Example 1

As shown in Fig. 2(a)-Fig. 2(d), three types of middle-enhanced intracranial stents are designed in this embodiment, the span of the single diamond-shaped unit is designed to be 8 mm, and the proportion of the single diamond-shaped unit in the surface area of the entire intracranial stent is adjusted. The proportions were 8.3%, 16.7% and 33.3%, respectively, and the simple double-diamond cell design scaffold served as a control. The length of the intracranial stent was 22.5 mm, the outer diameter was 4.43 mm, and the wall thickness of the intracranial stent was 0.8 mm. The sine wave structure wire width of the intracranial stent is 0.05mm, the width of the connecting rod is 0.05mm, and the height of the connecting rod is 0.045mm. The ratio of the height dimension to the width dimension of a single diamond cell is 1.03. The three-point bending process and extrusion process of the bracket are simulated by finite element.

As shown in Fig. 3, the finite element results show that the bending moments of the four structures in the three-point bending experiment are 0.93 N·mm (simple double diamond element), 1.07 N·mm (8.3% single diamond element), 1.23 N·mm, respectively. mm (16.7% single rhombus unit) and 1.42 N mm (33.3% single rhombus unit), the compliance performance of the scaffold decreases with the increase of the single rhombus unit density, see Fig. 3(a) for four cases from top to bottom . At the same time, the results of the extrusion experiment showed that the supporting force of the stent to the indenter was 0.15N (single double diamond element), 0.17N (8.3% single diamond element), 0.19N (16.7% single diamond element) and 0.25N (33.3% single diamond element), respectively. diamond cells), the supporting force of the scaffold increases with the increase of the density of single diamond cells, as shown in Fig. 3(b) for four cases from top to bottom.

Example 2

In Example 2, the length of the designed stent was 22.5 mm, the outer diameter was 4.43 mm, and the wall thickness of the intracranial stent was 0.8 mm. The intracranial stent is uniformly enhanced. According to the simulation results in Example 1, when the proportion of single rhombus units is between 16.7% and 33.3%, the stent has both good flexibility and support performance. Therefore, in this embodiment, the design method in which the area of a single diamond-shaped unit accounts for 20% of the entire surface area of the stent is used to verify the effect of the uniform reinforcement design. The sine wave structure wire width of the intracranial stent is 0.05mm, the width of the connecting rod is 0.05mm, and the height of the connecting rod is 0.05mm. The ratio of the height dimension to the width dimension of a single diamond cell is 1.03.

As shown in Figure 4(a)-Figure 4(b), after laser cutting on the NiTi tube according to the set drawing, the final intracranial stent can be obtained after cleaning, heat treatment, polishing, and cleaning again.

As shown in Fig. 5(a)-Fig. 5(b), the interaction process of the stent with the blood vessel after implantation is simulated by finite element. The results showed that compared with the non-reinforced scaffold, the stress on the tissue after implantation was significantly enhanced.

Example 3

Example 3 Designing intracranial stents with different wire widths, the sine wave structure wire widths of the intracranial stent are 0.025mm, 0.05mm and 0.075mm respectively, the wall thickness of the intracranial stent is 0.85mm, the width of the connecting rod is 0.05mm, and the connecting rod The height is 0.05mm. The ratio of the height dimension to the width dimension of a single diamond cell is 1.5.

Some stents were selected for radial compression simulation to explore the effect of different wire widths on the support performance of stents. The results show that the radial forces of the four stents are: 0.009N·mm ^-1 (0.025mm wire width), 0.015N·mm ^-1 (0.05mm wire width), 0.021N·mm ^-1 (0.075mm wire width) . The radial support force increases with the increase of the wire width, see Figure 6.

Example 4

In Example 4, the sizes of the fillets at the joints of the stents were respectively set to be 0.02mm and 0.05mm without fillet treatment, the wire width of the sine wave structure of the intracranial stent was 0.05mm, and other parameters were the same as those of Example 3. Some stents were selected for radial compression simulation to explore the effect of different wire widths on the local stress distribution of the stent. The results show that the stent without rounded corners has more serious stress concentration, as shown in Figure 7.

The results of the examples show that the present invention provides a local reinforced nickel-titanium alloy intracranial stent, the stent is made of superelastic nickel-titanium alloy material, the main body of the intracranial stent is a single diamond-shaped unit composed of a sine wave structure and a connecting rod, and The double-diamond unit is formed by combining two single-diamond units. The double diamond unit can improve the flexibility of the stent, and the single diamond structure can ensure the stable support performance of the stent to a certain extent. In addition, by adjusting the positions and numbers of units with different shapes, a variety of stent structures can be designed and changed to achieve different mechanical properties. The design of the locally enhanced Nitinol intracranial stent based on the hybrid unit structure can design an optimized unit ratio for different use environments, and realize the specific position (such as tumor diameter) under the premise of ensuring the compliance of the stent. ), which can be used to assist coil embolization.

Claims (9)

1. A local reinforced nickel-titanium alloy intracranial stent is characterized in that an intracranial stent main body is of a tubular structure consisting of a single rhombus unit formed by a sine wave structure and a connecting rod and a double rhombus unit formed by combining two single rhombus units.

2. The locally enhanced nickel-titanium alloy intracranial support according to claim 1, wherein the single diamond-shaped unit and the double diamond-shaped unit are arranged in a middle reinforcing mode, namely a single diamond-shaped unit structure is added to the middle of the intracranial support; the span of the single diamond-shaped unit is larger than 4mm, and the single diamond-shaped unit accounts for 12.5-50% of the surface area of the whole intracranial support.

3. The locally enhanced nickel-titanium alloy intracranial stent as defined in claim 1, wherein the single diamond units and the double diamond units are uniformly arranged in a reinforcing manner, that is, the single diamond units are uniformly added on the surface of the whole intracranial stent, and the single diamond units account for 0-33.3% of the surface area of the whole intracranial stent.

4. The locally enhanced nickel-titanium alloy intracranial support according to claim 1, wherein in the process of combining the single diamond-shaped units into the double diamond-shaped units, the connecting rods of the original structure are retained, and the connecting rods are subjected to fillet treatment, and the fillet radius is 0.02-0.05 mm.

5. The locally enhanced nitinol intracranial stent of claim 1, wherein the ratio of the height dimension to the width dimension of the single diamond-shaped unit of the sinusoidal structure and the connecting rod is 1-1.5.

6. The locally reinforced Ni-Ti alloy intracranial stent as defined in claim 1, wherein the sinusoidal wave structure of the intracranial stent has a wire width of 0.03-0.07 mm, a connecting rod height of 0.05-0.1 mm, and a width of 0.05-0.1 mm.

7. The locally enhanced nickel-titanium alloy intracranial support according to claim 1, wherein the vertex of the unit at both ends of the intracranial support is in a semi-circular arc structure, and the diameter of the circular arc is 0.15-0.25 mm.

8. The locally enhanced nickel-titanium alloy intracranial support according to claim 1, wherein the intracranial support has a wall thickness of 0.05-0.085 mm, a length of 15-40 mm, and a nominal diameter of 2-7 mm.

9. The locally enhanced nitinol intracranial stent of claim 1, wherein the intracranial stent is a superelastic nitinol material with an elasticity in the range of 10% to 15%.

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