WO2021218903A1

WO2021218903A1 - Stent crimping method and stent system

Info

Publication number: WO2021218903A1
Application number: PCT/CN2021/089856
Authority: WO
Inventors: 张万谦; 李海锋
Original assignee: 元心科技(深圳)有限公司
Priority date: 2020-04-28
Filing date: 2021-04-26
Publication date: 2021-11-04
Also published as: CN113558833A; CN113558833B

Abstract

A stent (10) crimping method for crimping a stent (10) onto a balloon (20), with the stent (10) having an inner cavity, and the method comprising the steps of inserting the balloon (20) into the inner cavity of the stent (10), placing the balloon (20) and the stent (10) in a crimping cavity of a crimping machine, and blowing air into the balloon (20) while reducing the inner diameter of the crimping cavity for first crimping for the stent (10); and stopping air blowing and the drawing of air from the balloon (20), increasing the inner diameter of the crimping cavity and stopping crimping, continuing to draw air from the balloon (20), and making the crimping cavity contract again for second crimping. In the method, the balloon (20) is crimped twice, and air blowing and negative pressure evacuation operations are respectively carried out for the balloon (20) during the two crimping processes, such that stent rods (12) are uniformly distributed on the balloon (20), and the area of contact between the balloon (20) and the stent (10) is increased, thereby increasing the removal force for the stent (10).

Description

Bracket pressing method and bracket system

Technical field

The invention relates to the field of medical equipment, in particular to a method for pressing and holding a stent and a stent system.

Background technique

Percutaneous transluminal arterioplasty is currently the most effective way to treat diseases caused by vascular stenosis and insufficient blood supply (such as coronary heart disease). To transport the stent to the diseased location, the stent needs to be mounted on the delivery system. For balloon-expandable stents, a balloon catheter is often used to transport the stent to the diseased location, and then the balloon is filled to expand the stent held on the balloon to achieve the purpose of supporting the blood vessel.

A key consideration for the performance of a balloon-expandable stent is the stent removal force, which is defined as the maximum force required for the stent to detach from the delivery system. When the stent is mounted on the delivery system to pass through complex lesions (such as calcified lesions), sometimes it will encounter some resistance. If the removal force is too low, the stent will easily slide on the balloon, resulting in uneven or incomplete expansion of the stent. Effectiveness of the stent; or cause the stent to be unloaded from the delivery system, causing embolism, myocardial infarction, etc. Therefore, the removal force of the stent is an important index to evaluate the safety and effectiveness of the stent system, and the larger the index value is, the better when other performances are met.

There are currently three common directions for increasing the removal force. The first direction is to change the design of the bracket, such as the surface treatment of the bracket to improve the surface roughness of the material. However, at this time, in order to ensure the support performance of the stent, it is usually necessary to change the wall thickness design of the stent, which will bring a lot of evaluation work on clinical safety and effectiveness, which is time-consuming and labor-intensive. The second direction is to change the design of the balloon, such as modifying the surface of the balloon to improve the surface roughness of the balloon material. However, the balloon processing technology in this way is extremely complicated. The third is to optimize the process of pressing and holding production, such as increasing the value of the pressing and holding radial force. However, increasing the value of the crimping radial force is a bottleneck for different stent designs. The smaller the stent is crimped in the circumferential direction, because the balloon often uses flaps to reduce the size of the balloon. The surface of the balloon is uneven, which will cause the stent rod to be easily embedded in the balloon during the crimping process, and some parts are difficult to embed. Damage the coating or cause the stent rods to overlap.

Based on this, it is necessary to provide a method for pressing and holding the stent, which can greatly improve the removal force of the stent without increasing the complexity and difficulty of the process.

Summary of the invention

The method for pressing and holding a stent provided by the present invention includes the following steps:

The balloon is inserted into the inner cavity of the stent, and the balloon and the stent are placed in the compression cavity of the crimping machine to inflate into the balloon while reducing the Crimp the inner diameter of the cavity to crimp the stent for the first time;

Stop inflating, and evacuate the balloon, increase the inner diameter of the crimp cavity to stop crimping, keep the balloon inflated, and contract the crimp cavity again to perform the first step on the stent. Squeeze twice.

In one embodiment, before inserting the balloon into the lumen of the stent, the method further includes the step of folding the wings of the balloon.

In one embodiment, before inserting the balloon into the lumen of the stent, after folding the balloon, it further includes the step of pre-compressing the stent, so that the pre-compression of the stent is pre-compressed. The difference between the compressed inner diameter and the outer diameter of the balloon after folding wings is within ±5%.

In one embodiment, after the stent is pre-compressed and before the stent is crimped for the first time, the method further includes the step of reducing the inner diameter of the crimping cavity, so that the inner diameter of the crimping cavity is smaller than that of the stent. The outer diameter of the pre-compression is less than 5% smaller.

In one embodiment, when the balloon is inflated, the inflation pressure ranges between 50 psig and 140 psig.

In an embodiment, the bracket includes a metal bracket or a metal composite bracket.

In one embodiment, after performing the first and second crimping, respectively, the step of maintaining the crimping radial force of the crimping machine for pressure keeping is further included.

The present invention also provides a stent system. The stent system includes a stent and a balloon, the stent is pressed on the outer surface of the balloon, the stent includes a plurality of stent units, and the stent unit includes a plurality of mutual Connected stent rods, when the stent is pressed and held on the balloon, the multiple stent rods are substantially parallel to each other, and the multiple stent rods are approximately evenly distributed in the circumferential direction, and the balloon part protrudes Between the plurality of bracket rods.

In one embodiment, the plurality of stent rods form pinch marks on the surface of the balloon.

In one embodiment, the stent also carries therapeutic drugs.

The method for crimping the stent provided by the present invention is that the balloon is crimped twice, and the balloon is inflated and the negative pressure is sucked during the two crimping, so that the stent rods are evenly distributed on the balloon and increase The contact area between the balloon and the stent is large, thereby increasing the removal force of the stent. In the stent system prepared according to the above method provided by the present invention, when the stent is crimped on the balloon, the multiple stent rods on the stent unit are substantially parallel to each other and the multiple stent rods are evenly distributed in the circumferential direction, and the balloon partly protrudes With multiple stent rods, that is, the stent rods are basically evenly distributed on the outer surface of the balloon, thereby increasing the contact area between the balloon and the stent, increasing the removal force of the stent, improving the stability and effectiveness of the stent Sex and safety.

Description of the drawings

Figure 1 is a partial structural diagram of the stent system of the present invention, including a stent and a balloon;

Fig. 2 is a schematic diagram of a part of the structure of the stent shown in Fig. 1;

Fig. 3 is a schematic cross-sectional structure diagram of the stent system of Fig. 1;

4 to 6 are schematic diagrams of structural changes of the stent and the balloon during the crimping process of the stent according to Embodiment 1 of the present invention;

7 to 8 are schematic diagrams of the partial structure and cross-sectional structure of the stent after being crimped according to the crimping method of Comparative Example 1;

9 is a comparison diagram of the removal force of the stent after being crimped according to the crimping method of the embodiment of the present invention and the comparative example;

Fig. 10 is a comparison diagram of the maximum cross-sectional size of the stent after being crimped according to the crimping method of the embodiment of the present invention and the comparative example.

Detailed ways

In order to better understand the technical solutions and effective effects of the present invention, the present invention will be further described below in conjunction with specific embodiments.

-Fold the wings of the balloon to make the balloon form multi-valve uniform balloon wings, and keep the balloon in the state of folding wings;

-Put the stent on the liner rod and place it in the pressing cavity of the pressing machine, and pre-compress the stent so that the pre-compressed inner diameter of the stent after pre-compression is approximately equal to the size of the flaps of the balloon;

-Take out the stent and insert the balloon after the flaps into the lumen of the pre-compressed stent to realize the preliminary assembly of the balloon and the stent;

-Put the balloon and stent together in the crimping cavity of the crimping machine, reduce the inner diameter of the crimping cavity so that the inner diameter of the crimping cavity is slightly smaller than the pre-compression outer diameter of the stent;

-Set the crimping radial force and crimping speed, and connect the pressurizing valve to set the inflation pressure to inflate the balloon, and at the same time to perform the first crimping of the stent at a certain speed;

-After the crimping radial force reaches the set value, keep the crimping radial force of the crimping machine for a short time holding;

-Close the pressurizing valve, connect the pumping valve, set the pumping pressure, pump the balloon, increase the inner diameter of the crimping cavity, stop the crimping, and set the crimping radial force again after the stent is stable in size and does not rebound , Keep pumping, and hold the stent for the second time;

-Increase the inner diameter of the crimping cavity of the crimping machine, close the pumping valve, and take the stent and balloon out of the crimping cavity together to complete the crimping of the stent.

Among them, the specifications of the above-mentioned stent and balloon can be selected according to actual needs, and correspondingly, the crimping parameters can also be changed according to the specifications of the stent and balloon. Generally speaking, the length of the balloon needs to be greater than the length of the stent, and the longer the length of the stent, the greater the radial force of the crimping set during crimping.

For example, the number of balloon wings formed after the flaps of the balloon of the present invention can be 2 to 10 flaps; the size of the flaps of the balloon after the flaps (that is, the maximum outer contour diameter after the flaps) ranges from 0.040 inches to 0.082 inches; stent specifications can be selected according to actual needs, such as stent deployment specifications (that is, the expansion size of the stent under a nominal pressure of 8 atm), the stent diameter ranges from 2 mm to 10 mm, and the stent length ranges from 8 mm to 118 The stent wall thickness ranges from 50 micrometers to 150 micrometers between millimeters; the radial force of the pressure grip can range from 450N to 2670N; the pressure grip speed ranges from 0.01 inch/sec to 0.001 inch/sec; air pressure The range can be selected from 50 psi (pound force per square inch) to 140 psi; the pumping pressure range can be selected from -0.1 psi to -15 psi; the pressure holding time after one pressing can be 20 seconds to 60 seconds.

In addition, the crimping radial force, the crimping speed, and the holding time after the crimping of the stent during the first crimping and the second crimping may be the same or different.

The stent of the present invention includes a metal stent or a metal composite stent, such as an iron stent, a magnesium stent, a cobalt-chromium alloy stent, and the like. Among them, the metal coverage on the stent is about 8%-18%.

The balloon material of the present invention may include at least one of nylon 11, nylon 12, PEBAX7233, PEBAX7033, PEBAX6333, PEBAX5533, polyurethane, polyethylene phthalate or polyethylene, and the thickness of the balloon is about 0.005. Between millimeters and 0.1 millimeters.

The partial structure of the stent system 100 prepared according to the above method provided by the present invention is shown in FIG. 1. The stent system 100 includes a stent 10, a balloon 20, and a catheter assembly 30. The two ends of the balloon 20 are fixedly connected to the catheter assembly 30; the stent 10 is pressed on the outer surface of the balloon 20, and the axial length of the balloon 20 is greater than the axial length of the stent 10. The part of the catheter assembly 30 covered by the balloon 20 is also provided with a developing structure 40. The number of developing structures can be two, and the two developing structures 40 are located at both ends of the stent, and both are arranged on the catheter assembly 30 without being stent. 10 The covered part is used to indicate the position of the stent during the implantation process under the imaging device to improve the accuracy of the implantation position of the stent.

As shown in combination with FIG. 1 and FIG. 2, the bracket 10 includes a plurality of bracket units 11 and connecting units. A plurality of bracket units 11 are arranged along the length direction of the bracket 10 and connected by connecting units. In some embodiments, the connection unit may include a first connection unit 13 and a second connection unit 14. Among them, the first connecting unit 13 includes an Ω structure, which can provide a certain margin and cushion for the deformation of the stent 10;

The bracket unit 11 includes a plurality of bracket rods 12 and connecting pieces 16. The proximal end of any stent rod 12 is connected to the proximal end of an adjacent stent rod 12 through a connecting piece 16, and the distal end of any stent rod 12 is connected to another adjacent stent rod through another connecting piece 16 The distal ends of the brackets are connected, so that the stent unit 11 forms a closed structure in the circumferential direction.

2 and 3, when the stent 10 is pressed and held on the balloon 20, the plurality of stent rods 12 are substantially parallel to each other, and the plurality of stent rods 12 are approximately evenly distributed in the circumferential direction, and the balloon 20 partially protrudes Between the multiple stent rods 12, so that the balloon 20 not only contacts the inner surface of the stent rod 12, but also contacts the side surface of the stent rod 12, thereby increasing the contact area between the balloon 20 and the stent 10, so that two The friction between the two increases, which improves the removal force of the stent. Furthermore, the stent rod 12 can also form a pinch mark on the surface of the balloon 20, so that the portion of the balloon 20 protruding between the stent rods 12 is stable in shape.

In some embodiments, the surface of the stent 10 may also carry therapeutic drugs, such as sirolimus, everolimus, paclitaxel, and the like.

Specific embodiments and comparative examples will be listed below to further describe the pressing method of the stent of the present invention and the effects brought by the method in further detail. The following specific embodiments and comparative examples all take a stent with a crimping specification of 3.5×8.0 (that is, the deployment specification of the stent is that the outer diameter of the stent is about 3.5 mm and the length is about 8 mm) as an example.

Example 1

With reference to Figures 4 to 6, the method for pressing and gripping the stent of this embodiment includes the following steps:

S1. Fold the wings of the balloon 20 so that the balloon 20 forms a three-valve uniform balloon wing 21, and keep the balloon 20 in a folded wing state;

Step S1 is to fold the wings of the balloon 20, especially to make the balloon form a multi-valve uniform balloon wing 21, so as to ensure that the overall contour of the balloon is symmetrical after folding, and to ensure that the subsequent stent can be crimped to a smaller size. Thus, a smaller delivery sheath can be used to deliver the stent to the lesion. At the same time, the balloon that is always kept in a uniformly folded state can also ensure that when the stent is expanded, the force of the balloon on the stent is uniform, and the uniformity of the stent expansion is better. When the balloon is folded, the number of balloon wings can be 2-10 flaps, preferably 3-5 flaps. In this embodiment, the size of the balloon flaps after uniformly flapping the balloon 20 is about 0.046 inches (about 1.1684 mm).

S2. Put the stent 10 on the liner rod, and coat the stent 10 with a layer of PTFE film to protect the stent 10 from being scratched, and then place it in the pressing cavity of the pressing machine to pre-determine the stent 10 Pressure, so that the pre-compressed inner diameter of the stent 10 after pre-compression is approximately equal to the size of the flaps of the balloon 30;

In step S2, the cut and shaped stent is pre-compressed to appropriately reduce the inner diameter and outer diameter of the stent 10, so that during subsequent crimping, the gap between the stent 10 and the balloon 20 is reduced, and the pre-compressed inner diameter of the stent It can be roughly the same size as the flaps of the balloon, so as to avoid relative movement between the two when crimping. For stents of different specifications, the size of the preload is different, so the force applied during the preload is also different. In this embodiment, since the flap size of the balloon after the flap is about 0.046 inches, a 50 psi cylinder is used to drive the press to pre-compress the stent. After pre-compression, the pre-compressed inner diameter of the stent 10 is about 0.048 inches. The outer diameter of the pre-compression is approximately 0.056 inches. It should be understood that the balloon 20 needs to be inserted into the lumen of the stent 10 subsequently, so the pre-compressed inner diameter of the stent is slightly larger than the flap size of the balloon. Therefore, the “substantially equal” in the present invention refers to the distance between the stent and the balloon. The gap between the stent and the balloon is small, and the stent and the balloon will not easily move relative to each other when it is not pulled by external force; or it can be understood that the difference between the inner diameter of the stent and the outer diameter of the balloon is within ±5%.

S3. Take out the stent 10 from the squeeze cavity of the squeeze machine, and insert the balloon 20 after the flaps into the inner cavity of the pre-compressed stent 10 to realize the preliminary assembly of the balloon 20 and the stent 10;

As shown in FIG. 4, before the crimping, the circumferential distance between the bracket rods 12 is relatively large. After the balloon 20 is inserted into the inner cavity of the stent 10, basically each stent rod 12 can contact the balloon wings 21, and the balloon wings 21 are evenly distributed, and the ends of the balloon wings 21 are located exactly between the two stent rods 12 Between the gaps. In addition, before inserting the balloon into the stent, it is necessary to peel off the film outside the stent to observe whether the appearance of the stent is complete and whether there is damage such as scratches.

S4. Place the balloon 20 and the stent 10 together in the crimping cavity of the crimping machine to reduce the inner diameter of the crimping cavity so that the inner diameter of the crimping cavity is less than 5% smaller than the pre-compressed outer diameter of the stent 10;

Before the formal crimping, reduce the inner diameter of the crimping cavity to a position slightly smaller than the pre-compressed outer diameter of the stent 10, and reduce the distance between the inner wall of the crimping cavity and the stent 10, so as to avoid the ball in the subsequent crimping process. When the balloon is inflated, the stent is expanded by the balloon, and the stent rod is deformed or even the stent fails. In this embodiment, the pre-compressed outer diameter of the stent 10 is about 0.056 inches, so the pressing cavity in step S4 can be reduced to 0.055 inches.

S5. Set the crimping radial force of the crimping machine to 944N and the crimping speed to 0.001 inch/sec; and connect the pressurizing valve, set the inflation pressure to 30 psi, start to inflate the balloon 20, and then start to stent 20 Perform the first press grip;

As shown in Fig. 5, when the relevant parameters are set and the pressure is started, the balloon 20 expands due to the inflated part, thereby generating a reverse force against the deformation of the stent 10 (that is, the force opposite to the radial force of the pressure and grip), especially It is the side of the balloon wing 21 that is close to the inner surface of the stent 10, and a protrusion that blocks the deformation of the stent rod 12 is initially formed in the part that is not blocked by the stent rod 12, so that the stent rod 12 can always be pressed and gripped for the first time. Keep evenly distributed in the circumferential direction without shifting or overlapping. In addition, since the inflated balloon 20 can generate a reverse force against the deformation of the stent 10, the compression and grip radial force for the stent 10 and the balloon 20 to reach the compression limit is increased, so that the stent and the balloon are compressed more tightly, and the stent is removed. Power is higher.

S6. After pressing and holding until the radial force of pressing and holding reaches the set value of 944N, maintain the radial force of pressing and holding of the press and hold the pressure for a short time, and the holding time is 30 seconds;

In step S6, after the crimping radial force of the crimping machine reaches the set value, the crimping cavity of the crimping machine is still kept in the crimping state, the stent is kept crimped, and the shape of the stent is further consolidated to make the stent The compression and grip shape of the stent is stable, which further makes the pinch marks on the balloon wings due to the restriction and blocking of the stent rod more stable. If the crimping radial force is reached, the crimping will be released. At this time, the crimping shape of the stent is unstable. After increasing the inner diameter of the crimping cavity, the stent may rebound quickly, or even detach from the balloon surface, making the crimping fail.

S7. Close the pressurizing valve, connect the pumping valve, set the pumping pressure to -12psi, and pump the balloon, then increase the inner diameter of the press and grip cavity and stop the press and grip for about 5 seconds until the stent is stable in size and does not rebound. , Once again set the crimping radial force of the crimping machine to 944N and the crimping speed to 0.001 inch/sec, keep air suction, and perform a second crimping on the stent;

In step S7, first close the pressurizing valve, stop the inflating operation of the balloon 20, and then evacuate the balloon 20. After the remaining air in the balloon is extracted, the inner diameter of the crimping cavity is increased to avoid removing the pressure. After the grip cavity is crimped, the balloon expands to deform the stent. At the same time, increase the inner diameter of the crimping cavity to stop crimping to stabilize the size of the stent before crimping again, and always keep the balloon inflated during the crimping process, so that the air in the balloon will not resist the pressure of the crimping cavity to the balloon. The pressure grip. When the stent is pressed for the second time, the air in the balloon is completely extracted, so that the stent can be compressed to a smaller size. At this time, since the bulges between the stent rods have been formed on the balloon during the first crimping, and the balloon wings have formed stable clamping marks, the air will not be sucked during the second crimping. Change the position of the balloon material on the stent rod stent or the pinch marks on the balloon wings disappear.

S8. After the pressing and gripping radial force reaches the set value, keep the pressing and gripping radial force of the press and hold the pressure for a short time, and the holding time is 30 seconds;

Similar to step S6, the purpose of maintaining pressure in step S8 is also to further consolidate the shape of the stent and stabilize the stent's crimping shape.

S9. Increase the inner diameter of the crimping cavity of the crimping machine, stop crimping, close the pumping valve, take out the stent and balloon from the crimping cavity together to complete the crimping of the stent.

As shown in FIG. 6, the circumferential distance between the stent rods 12 on the stent after the two crimping is completed is smaller, and the diameter of the stent 10 is also smaller. Compared with the balloon wing 21 when it was first crimped, the protrusions formed on the balloon wing 21 are more obvious after the crimping is completed, and can even be located on the same outer contour line as the stent rod 12. Therefore, according to the stent after pressing and gripping in this embodiment, not only the stent rods are evenly distributed in the circumferential direction, but the force is uniform when the stent expands, and the stent deployment shape is good; and the protrusions formed on the balloon can increase the gap between the stent and the balloon. The contact area increases the removal force of the stent, and the protrusions can also form a physical barrier, which increases the resistance of the stent rod to the relative movement.

It should be understood that the pressing machine used for pre-pressing the stent and the pressing machine used for the first pressing and the second pressing may be the same or different, and when the pressing machine itself is attached with a film When the system is used, it is no longer necessary to cover the stent before pre-compression or crimping. In addition, the pressing time and pressing speed in step S5 and step S7 may be the same or different, and the holding time in step S6 and step S8 may be the same or different.

Example 2

The pressing method of the stent of this embodiment is basically the same as the pressing method of embodiment 1, the difference is only that when the first pressing and holding is performed in step S5 in this embodiment, the blast pressure is set to be higher than that of the drum of embodiment 1. The air pressure is large, and the blast pressure is set to 140 psi. In this embodiment, a larger inflation pressure can be set to make the balloon produce a greater reverse force against deformation of the stent during the first crimping, so that the stent and the balloon’s compressive radial force at the compression limit is also obtained. Increase, and ultimately increase the removal force of the stent. At the same time, the higher the inflation pressure, the more balloon material is bulged between the stent rods to form protrusions. The protrusions are closer to the outer contour line of the stent rod, and there is less balloon material on the inner side of the stent. The maximum cross-sectional size is also smaller.

In order to better reflect the beneficial effects and advantages of the pressing method of the present invention, some comparative examples are also listed below for comparison with the above-mentioned embodiments.

Comparative example 1

This comparative example uses two pressing operations but neither inflating nor exhausting during the pressing process. It includes the following steps:

S3. Take out the stent 10 from the squeeze cavity of the squeeze machine, and insert the balloon 20 with the flaps into the inner cavity of the pre-compressed stent 10 to realize the preliminary assembly of the balloon 20 and the stent 10;

S4. Set the crimping radial force of the crimping machine to 674N and the crimping speed to 0.001 inch/sec, and start the first crimping of the stent 20;

S5. Keep pressing until the radial force of pressing and holding reaches the set value of 674N, then keep the radial force of pressing and holding of the press and hold the pressure for a short time, and the holding time is 30 seconds;

S6. Increase the inner diameter of the crimping cavity and stop crimping for about 5 seconds. After the stent is stable in size and does not rebound, set the crimping radial force of the crimping machine to 674N and the crimping speed to 0.001 inch/sec. Perform a second press grip;

S7. After the pressing and gripping radial force reaches the set value, the pressing and gripping radial force of the pressing and gripping machine is maintained, and the pressure is maintained for a short period of time for 30 seconds;

S8. Increase the inner diameter of the crimping cavity of the crimping machine to stop crimping, and take out the stent and the balloon from the crimping cavity together to complete the crimping of the stent.

Although the steps S1 to S3 in this comparative example are the same as the steps S1 to S3 of the above-mentioned embodiment 1, because the balloon was not inflated during the first pressing and gripping, even if the balloon was uniformly squeezed. Folding wings, even after pressing and holding, can’t ensure that the support rods are evenly distributed in the circumferential direction. Just because the outer contour of the balloon flaps is not a regular circle, there is a size difference near the ends of the balloon wings. As shown in Figures 7 and 8, the stent after being crimped according to Comparative Example 1, because no inflation was performed during the first crimping, no protrusions were formed on the balloon wings to block the deformation and displacement of the stent rod, so that the stent The rods move toward the end of the balloon more or less, causing uneven distribution of the stent rods 12 in the circumferential direction. During subsequent stent implantation, the stent rods may even overlap.

It should be noted that, since the balloon is not inflated during crimping in this comparative example, the step of reducing the inner diameter of the crimping cavity is omitted before crimping.

Comparative example 2

The difference between this comparative example and comparative example 1 is only that a greater radial force of pressing and gripping is used during the two pressing and gripping, and the same radial force of pressing and gripping of 944N as in the above-mentioned embodiment 1 is used in this comparative example for two pressing and gripping.

Compared with Comparative Example 1, because of the larger radial force of pressing and gripping, the removal force of the stent after pressing and holding according to the method of Comparative Example 2 is greater than that of the stent of Comparative Example 1, and the maximum force of the stent is The cross-sectional size is smaller than the maximum cross-sectional size of Comparative Example 1.

Comparative example 3

In this comparative example, a press-squeeze operation was used to inflate the air during the press-squeeze, and the air was pumped after the press-squeeze was completed, but the second press-squeeze operation was not performed. It includes the following steps:

S5. Set the crimping radial force of the crimping machine to 944N and the crimping speed to 0.001 inch/sec; and connect the pressurizing valve, set the inflation pressure to 30 psi, start to inflate the balloon 20, and then start to stent 20 to press and hold;

S7. Close the pressurizing valve, connect the pumping valve, set the pumping pressure to -12psi, pump the balloon, and then increase the inner diameter of the press and grip cavity to stop the press and grip for about 5 seconds until the stent is stable in size and does not rebound;

S8. Increase the inner diameter of the crimping cavity of the crimping machine to stop crimping, close the pumping valve, and take out the stent and the balloon from the crimping cavity together to complete the crimping of the stent.

Compared with Example 1, the difference in this comparative example is only that step S7 only performs air extraction, but does not perform a second crimping on the stent. This makes the clamping marks on the balloon wings shallower, and the maximum cross-sectional size of the stent after crimping is also larger.

Comparative example 4

This comparative example adopts the operation of inflating during the first pressing and holding and not pumping during the second pressing and holding. The difference from Embodiment 1 is only in step S7. The step S7 of this comparative example is:

S7. Close the pressurizing valve, then increase the inner diameter of the crimping cavity and stop crimping for about 5 seconds. After the stent size is stable and does not rebound, set the crimping radial force of the crimping machine to 944N and the crimping speed to 0.001 again. Inch/second, press and hold the stent for the second time;

Compared with comparative example 2, the difference of this comparative example is only that in step S7, the air is not pumped during the second pressing and gripping, so during the second pressing and gripping, the residual gas in the balloon will still produce resistance to the stent to a certain extent. The opposing force of compression. As a result, the clamping marks on the balloon wings are shallower, and the maximum cross-sectional size of the stent after crimping is also larger.

Compared with Comparative Example 3, although the balloon was not evacuated in this Comparative Example, the second compression grip was performed, which can increase the removal force of the stent to a certain extent, while slightly reducing the maximum cross-sectional size of the stent.

Figures 9 to 10 visually show the effects of the above-mentioned embodiments and comparative examples on the removal force of the stent and the maximum cross-sectional size. It can be seen from Figure 9 that increasing the radial force of the crimping can increase the removal force to a certain extent; performing a second crimping of the stent and drawing air during the crimping can increase the removal force of the stent and reduce the stent The maximum cross-sectional size of the stent; increasing the blast pressure can greatly enhance the removal force of the stent, and can also reduce the maximum cross-sectional size of the stent.

The removal force of the stent can be tested by the following method, which conforms to the standards ASTM F2394-07 and YY/T-0807.

Specifically, before the test, the liner was used to pass through the guide wire cavity, and two pieces of tape were used to glue, and the stent part of the stent system was fixed between the two pieces of tape. The fixed sample is clamped on the tensile machine for pulling. During clamping, the lower clamp of the tensile machine clamps the proximal end of the stent system (that is, the proximal end of the catheter assembly), and the upper end of the tensile machine The clamp clamps the tape away from the support system. Keep the sample upright and in the middle of the fixture, and start the test. When a peak of tensile force appears on the test display, the test can be stopped, and this peak is the maximum removal force of the stent.

In summary, the stent crimping method of the present invention is to crimp the stent twice, and the balloon is inflated during the first crimping, and the balloon is evacuated during the second crimping. After crimping, the stent rods are evenly distributed in the circumferential direction, and the removal force of the stent is increased, so that the force of the stent rods is uniform during subsequent implantation, and the shape of the stent after implantation is good; and the maximum cross-sectional size of the stent can be reduced. Use a smaller delivery sheath to deliver the stent, reducing the damage caused by the sheath during the implantation process.

It should be understood that the above-mentioned specific embodiments are only preferred embodiments of the present invention. They are only for explaining the technical solutions of the present invention and are not intended to limit the present invention. Several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention. The protection scope of the present invention is subject to the claims.

Claims

A method for pressing and holding a stent, which is used for pressing and holding the stent on a balloon, the stent has an inner cavity, and is characterized in that it comprises the following steps:

The balloon is inserted into the inner cavity of the stent, and the balloon and the stent are placed in the compression cavity of the crimping machine to inflate into the balloon while reducing the Crimp the inner diameter of the cavity to crimp the stent for the first time;

Stop inflating, and evacuate the balloon, increase the inner diameter of the crimp cavity to stop crimping, keep the balloon inflated, and contract the crimp cavity again to perform the first step on the stent. Squeeze twice.
The method of crimping the stent according to claim 1, wherein before inserting the balloon into the lumen of the stent, it further comprises a step of folding the wings of the balloon.
The method of crimping the stent according to claim 2, wherein before inserting the balloon into the lumen of the stent, after folding the wings of the balloon, it further comprises the step of pre-compressing the stent , So that the difference between the pre-compressed inner diameter of the stent after the pre-compression and the outer diameter of the balloon flaps is within ±5%.
The method of crimping a stent according to claim 3, wherein after pre-compressing the stent and before the first crimping of the stent, the method further comprises the step of reducing the inner diameter of the crimping cavity to make The inner diameter of the crimping cavity is less than 5% smaller than the pre-compressed outer diameter of the stent.
The method for pressing and holding the stent according to claim 1, wherein when inflating into the balloon, the inflation pressure ranges between 50 psig and 140 psig.
The method for pressing and holding a stent according to any one of claims 1 to 5, wherein the stent comprises a metal stent or a metal composite stent.
The method for crimping the stent according to any one of claims 1 to 5, wherein after performing the first crimping and the second crimping, respectively, the method further comprises maintaining the crimping machine. The pressing and holding radial force is used to hold the pressure.
A stent system prepared according to the method of claim 1, the stent system comprising a stent and a balloon, the stent is pressed on the outer surface of the balloon, the stent includes a plurality of stent units, and the stent unit includes A plurality of interconnected stent rods, characterized in that, when the stent is pressed and held on the balloon, the plurality of stent rods are substantially parallel to each other, and the plurality of stent rods are substantially evenly distributed in the circumferential direction, so The balloon part protrudes between the plurality of stent rods.
The stent system according to claim 8, wherein the plurality of stent rods form a pinch mark on the surface of the balloon.
The stent system according to claim 8, wherein the stent is also loaded with therapeutic drugs.