WO2005099967A1

WO2005099967A1 - Device for reducing the diameter of a stent

Info

Publication number: WO2005099967A1
Application number: PCT/DE2004/002787
Authority: WO
Inventors: Thomas Nissl
Original assignee: Qualimed Innovative Medizinprodukte Gmbh
Priority date: 2004-04-16
Filing date: 2004-12-21
Publication date: 2005-10-27
Also published as: DE102004019254B8; DE102004019254B3

Abstract

The invention relates to a device (1a) for reducing the diameter of a stent (2). Said device comprises pressure pieces (9a) which are supported on a peripheral abutment (3a) and act at least directly on the outer surface of the stent (2) in a radial manner. Flexible clamping bodies (15) that can be subjected to a pressurised fluid against an elastic restoring force (21) are provided between the radially inwardly displaceable segmented pressure pieces (9a) and the abutment (3a).

Description

Device for reducing the diameter of a stent

The invention relates to a device for reducing the diameter of a stent according to the features in the preamble of claim 1.

Such a device is part of the prior art from DE 297 14 857 U1. It comprises a collet with two legs which can be moved relative to one another and in which conical openings are formed. The openings widen towards the central transverse plane of the collet.

Furthermore, the device comprises a deforming body for a stent, which can be received in the openings of the collet. This means that it has a central, short, cylindrical section, two adjoining sections, which taper conically towards the end faces, and two cylindrical end sections. A central opening runs through the deforming body, which serves to receive a stent.

In the radial direction, the deformed body is divided into interconnected pressure pieces by a plurality of longitudinal slots. The cross section of the pressure pieces is wedge-shaped, with the pressure pieces narrowing in the direction of the central axis of the deforming body.

In the known device, it is necessary to set the reduction in the diameter of the stent manually using an adjusting screw on the legs of the collet. Errors caused by human inadequacies cannot be avoided. Since stents are generally applied to catheters and both the stents and the catheters have tolerances, it is very difficult to always achieve a uniform result by reducing the diameter of a stent (crimping). So far, it has only been possible with the known device to reduce a stent over its entire length by the same amount in diameter. Individual areas or lengths cannot be specifically reduced in diameter.

Another device for crimping stents is known from US Pat. No. 6,629,350 B2. Stents are inserted into a cylindrical opening in the front of this device. By actuating a lever on the right side, which is done by another device, the radius of the cylindrical opening is reduced by a mechanism and the stent is compressed. In this way, uniform compression of the stent is achieved. The degree of compression can be precisely determined and reproduced.

A disadvantage of this device is that only stents up to a defined length can be inserted and that the stent can only be compressed evenly over the entire length.

Starting from the prior art, the invention is based on the object of creating a device for reducing the diameter of a stent which always enables an exactly reproducible result and, moreover, allows individual length sections of a stent to be reduced in diameter in a targeted manner.

This object is achieved with the features specified in the characterizing part of claim 1. The core idea of the invention is the use of a pressure fluid (compressed air or pressure fluid) which can be set exactly, and also reproducibly, with regard to the desired or necessary pressure level. The pressure fluid is introduced into flexible clamping bodies which are arranged between radially inwardly displaceable, segment-like pressure pieces and an abutment located on the circumference of the pressure pieces. When the clamping fluid is acted upon by the pressure fluid, the pressure pieces are displaced radially inwards, supported on the abutment, and reduce the diameter of a stent exactly to the extent desired.

In this context, the invention also allows a stent to be loaded at least indirectly over the circumference with different pressures. That is, a stent is e.g. on opposite circumferential sections with a certain pressure on the clamping bodies provided there and on the other circumferential sections with a different pressure. In this way, the stent can be given a certain ovality.

The invention creates the preconditions for a stent to be reduced in diameter (crimped) on its own and then pushed onto a catheter. However, the invention also allows a stent to be pressed directly onto a catheter. The invention can be used particularly advantageously in the case of stents coated with medicaments. Since in such a case the drug-coated stent is surrounded by a tube as a protective sheath, the drug coating cannot be damaged with the device according to the invention. If the stent is securely attached to a catheter, the tube can then be easily removed.

The resilient elastic restoring force ensures that after the pressure in the clamping bodies has been released, the pressure pieces are shifted back into the starting position, so that the processed stent can then optionally be removed from the device together with a catheter. In view of the fact that the radial displacements of the pressure pieces are only limited distances, it is advantageous according to claim 2 if the clamping bodies are formed by balloons or stretchable hoses.

A preferred incorporation of the clamping body into the device according to the invention is given according to claim 3 if the pressure pieces have concave contact surfaces directed towards the circumferential abutment and the abutment has concave curved counter surfaces open towards its central axis. Contact surfaces and mating surfaces then form almost closed chambers on the circumference for the clamping bodies, in which the clamping bodies expand when a pressure fluid is applied to them and can thereby move the pressure pieces radially inward with support on the abutment.

A particularly advantageous embodiment of the invention is seen in the features of claim 4. Thereafter, the pressure pieces are arranged in at least two planes running parallel to one another and can be radially displaced in each plane independently of the pressure pieces of an adjacent plane. Such an embodiment makes it possible, irrespective of the number of levels, to shift the pressure pieces there more or less strongly in relation to the adjacent pressure pieces in predetermined levels. In this way, different crimp configurations can be achieved over the length of a stent. For balloon catheters, for example, it is often advisable to crimp a stent more at the ends than in the middle section.

In this embodiment, too, a stent - viewed over the circumference - can be loaded with different pressures. In the different levels, however, these pressure conditions are preferably always identical.

The axial length of the levels can be selected differently depending on the respective requirements. The abutment then preferably extends over all levels.

According to the features of claim 6, it is advantageous that the pressure pieces each encompass a radially inwardly directed web of the cylindrical abutment and are resiliently supported on the web. The Resiliently elastic support therefore always ensures the initial position, in which a stent can be inserted into or removed from the device. On the other hand, the webs serve for the exact guidance of the pressure pieces in the radial direction. This prevents jamming and jamming.

In this context, a preferred embodiment according to the features of claim 7 is characterized in that the pressure pieces are designed as hollow circular sections, with their radially directed, diverging legs and mutually facing projections adjacent to the abutment directly on the webs and with inward Support directed spring tongues on the cross legs of the webs.

In this embodiment, therefore, several, for example eight or twelve, pressure pieces with a configuration similar to a pie piece are arranged on the circumferential side of a stent to be deformed and can be displaced radially by the clamping bodies between the pressure pieces and the webs on the abutment. The material-thickened sections having the counter surfaces on the webs directly contact the diverging legs of the pressure pieces. At the radially outer end, the legs of the pressure pieces are provided with projections to be pointed towards one another, possibly in pairs. This ensures exact radial displaceability. The inwardly directed spring tongues on the legs of the pressure pieces preferably have a slightly arcuate contour and lie on the cross legs of the webs on their sides facing the circumferential abutment. These spring tongues ensure that the pressure pieces are in principle constantly loaded in the direction of the abutment. Their spring force can be overcome by the pressure fluid in the clamping bodies.

In this embodiment, both the pressure pieces and the abutment can be formed from a metal, in particular a steel. However, a suitable plastic is preferably used for the pressure pieces, while the abutment consists of a special steel. A further advantageous embodiment of the basic concept of the invention is seen in the features of claim 9. The pressure pieces then form components of a metallic spring band which extends in a meandering manner in the circumferential direction and which is supported with trapezoidal regions on two adjacent webs of the abutment consisting of a metal.

The elasticity of the spring band is such that when the tensioning body is pressurized, the trapezoidal regions are clamped in a wedge shape between two webs of the abutment that are adjacent in the circumferential direction. If the pressure in the tensioning bodies is subsequently reduced, the resetting force inherent in these trapezoidal areas ensures that the pressure pieces are moved radially outward again and the deformed stent is released.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. Show it:

Figure 1 is a schematic perspective of a device for reducing the diameter of a stent;

Figure 2 is a plan view of the device of Figure 1;

Figure 3 is a plan view of a detail of the device of Figures 1 and 2;

Figure 4 is a plan view of a further detail of the device of Figures 1 and 2;

FIG. 5 shows a top view of a further embodiment of a device for reducing the diameter of a stent;

FIG. 6 shows a detail of the device of FIG. 5 in a top view;

Figure 7 in plan view a further detail of the device of Figures 5 and

Figure 8 is a plan view of another embodiment of a device for reducing the diameter of a stent

1 and 2, 1 denotes a device for reducing the diameter of a stent 2, which is not illustrated in any more detail. According to FIGS. 1 to 3, the device 1 comprises a cylindrical abutment 3 made of steel. From the inner surface 4 of the abutment 3 project radially inwardly directed webs 5, which have concave cylindrical-section-shaped counter surfaces 8 open at the inner widened end 6 towards the central axis 7.

The abutment 3 shown in FIGS. 1 to 3 with the webs 5 is coupled by axially pushing them together with segment-like pressure pieces 9 (FIGS. 1, 2 and 4), which form components of a metallic spring band 10 which extends in a meandering manner in the circumferential direction. The pressure pieces 9 have diverging legs 11 extending from the central axis 7. Adjacent to the central axis 7, the pressure pieces 9 are reinforced in terms of material and provided with radial elongated holes 12. At the radially outer ends, the respective adjacent legs 11 of two pressure pieces 9 merge into trapezoidal areas 13 which, as can be seen in FIGS. 1 and 2, can be supported on adjacent webs 5 of the abutment 3.

Frontal to the counter surfaces 8 at the widened ends 6 of the webs 5, the pressure pieces 9 are provided with contact surfaces 14 concave towards the trapezoidal regions 13, the curvature of which corresponds to the curvature of the counter surfaces 8.

As can be seen from FIGS. 1 and 2, cylindrical receiving areas are formed by the contact surfaces 14 and the counter surfaces 8, into which flexible clamping bodies 15 in the form of tubes are introduced (FIG. 2). A pressure fluid in the form of compressed air or a pressure fluid can be applied to these clamping bodies 15. The tubes are omitted in FIG. 1.

A receiving area for a stent 2 is formed centrally by the end faces 16 of the pressure pieces 9 facing the central axis 7, as shown in FIGS. 1, 2 and 4. This receiving area can also be so large that a catheter with a stent 2 pushed onto it can be used.

In order to reduce the diameter of the stent 2, that is to say to press the stent 2 onto a catheter, for example, the clamping bodies 15 are acted upon by the pressure fluid. As a result, the pressure pieces 9 are displaced radially inwards, supported on the webs 5, and the stent 2 is pressed onto the catheter. After the pressure in the clamping bodies 15 has been reduced, the trapezoidal regions 13, due to their configuration in cooperation with the material of the spring band 10 and the webs 5 adjacent to the trapezoidal regions 13, ensure that the pressure pieces 9 again radially outwards in the direction of the abutment 3 in the standby position will be shifted.

FIG. 1 shows that in a single cylindrical abutment 3, several meandering spring bands 10 can also be arranged one above the other in parallel planes E, E1, etc. In such a case, it is then possible to arrange clamping bodies 15 in each plane E, E1 etc. between the contact surfaces 14 on the pressure pieces 9 and the opposite counter surfaces 8, for example in the form of balloons, which can then be pressurized with a pressure fluid. In this way, it is possible to reduce the diameter of a stent 2 in some areas, as is appropriate, for example, at the end sections of balloon catheters.

The device 1a shown in FIGS. 5 to 7 for reducing the diameter of a stent 2 in turn has a cylindrical abutment 3a, from which webs 5a project in the direction of the central axis 7a. This abutment 3a and the webs 5a are also made of steel.

In the approximately central longitudinal section, the webs 5a, as can be seen in particular from FIG. 7, have laterally projecting transverse limbs 17. The widened ends 6a of the webs 5a directed towards the central axis 7a have convex counter surfaces 8a in the form of cylindrical sections, as in the embodiment of FIGS ,

The webs 5a according to Figures 5 and 7 are coupled with segment-like pressure pieces 9a made of plastic, which are designed as hollow circular sections (Figures 5 and 6).

The pressure pieces 9a have diverging legs 11a extending from the material-reinforced ends 18 adjacent to the central axis 7a. At the ends 19 of the legs 11a, projections 20 to be pointed towards one another are provided in a parallel arrangement. These projections 20 serve to guide the pressure pieces 9a on the webs 5a together with the legs 11a and the widened ends 6a of the webs 5a.

In addition, the pressure pieces 9a adjacent to the projections 20 have inwardly directed arcuate spring tongues 21 which, as can be seen in FIG. 5, are supported on the sides 22 of the transverse legs 17 of the webs 5a facing the abutment 3a. Due to the resilient elastic restoring force of the spring tongues 21, the pressure pieces 9a are consequently loaded in the direction of the abutment 3a.

Adjacent to the reinforced areas 18 of the pressure pieces 9a, these have concave contact surfaces 14a which are adapted to the concavely curved counter surfaces 8a. As in the embodiment of the device according to FIGS. 1 to 4, the contact surfaces 14a and the counter surfaces 8a form receiving areas for flexible clamping bodies 15, for example in the form of hoses which can be pressurized with a pressure fluid.

If the clamping body 15 is pressurized with a pressurized fluid (compressed air or pressurized liquid), the pressure pieces 9a are displaced radially inwards, supported on the webs 5a of the abutment 3a, and in this way reduce the diameter of a stent 2 inserted into the middle receiving area on the end face of the pressure pieces 9a , if necessary by pressing on a catheter, not shown.

After the pressure in the clamping bodies 15 ceases to exist, the spring tongues 21 on the pressure pieces 9a ensure that the pressure pieces 9a are again displaced radially outward into the standby position.

The device 1a can also have pressure pieces 9a in several planes E, E1, etc., as is explained with reference to FIG. 1.

The device 1 shown in FIG. 8 represents a further embodiment. FIG. 8 differs from FIG. 2 in that it has a higher number of segments and in that the elongated holes 12 from FIG. 2 are realized as triangular cutouts 23 in this figure , The remaining reference numerals have been used identically, so that no further explanation is necessary.

REFERENCE NUMBERS

1 - device 1a- device 2- stent 3- abutment 3a- abutment 4- inner surface v.3 5- webs 5a- webs 6- inner end v.5 6a- ends v.5a 7- central axis 7a- central axis 8- counter surfaces on 5 8a- mating surfaces on 6a 9- thrust pieces 9a- thrust pieces 10- spring band 11 - leg v.9 11a- leg v.9a 12- elongated holes 13- trapezoidal areas 14- contact surfaces 14a- contact surfaces 15- clamping body 16- end faces v.9 17- cross legs on 5a 18- ends v.9a 19- ends v.11a 20- projections on 19 21 - spring tongues 22 pages v.17

23- recesses

E level

E1 - level

Claims

claims

1. Device for reducing the diameter of a stent (2), which has at least indirectly radially acting pressure pieces (9, 9a) on the outer surface of the stent (2), which are supported on a circumferential abutment (3, 3a), characterized That between the radially inward displaceable, segment-like pressure pieces (9, 9a) and the abutment (3, 3a) against a resilient restoring force (13, 21) with a pressurized fluid flexible clamping body (15) are provided.

2. Device according to claim 1, characterized in that the clamping body (15) are formed by balloons or expandable hoses.

3. Device according to claim 1 or 2, characterized in that the pressure pieces (9, 9a) towards the circumferential abutment (3, 3a) facing concave contact surfaces (14, 14a) and the abutment (3, 3a) to its central axis (7 , 7a) have open, concavely curved counter surfaces (8, 8a) for the clamping bodies (15).

4. Device according to one of claims 1 to 3, characterized in that the pressure pieces (9, 9a) are arranged in at least two mutually parallel planes (E, E1) and in each plane (E, E1) independently of the pressure pieces ( 9, 9a) of an adjacent plane (E, E1) are radially displaceable.

5. The device according to claim 4, characterized in that the abutment (3, 3a) extends over all levels (E, E1).

6. Device according to one of claims 1 to 5, characterized in that the pressure pieces (9, 9a) each encompass a radially inwardly directed web (5, 5a) of the cylindrical abutment (3, 3a) and engage on the web ( 5, 5a) support resiliently.

7. The device according to claim 6, characterized in that the pressure pieces (9a) are designed as hollow circular sections, with their radially directed, mutually diverging legs (11a) and towards each other Support projections (20) adjacent to the abutment (3a) directly on the webs (5a) and with inwardly directed spring tongues (21) on cross legs (17) of the webs (5a).

8. Device according to one of claims 1 to 7, characterized in that the pressure pieces (9a) consist of plastic and the abutment (3a) is formed from a metal.

9. Device according to one of claims 1 to 6, characterized in that the pressure pieces (9) form components of a meandering metallic spring band (10) extending in the circumferential direction, which trapezoidal areas (13) on two adjacent webs (5 ) supports the abutment (3) made of a metal.