METHOD AND DEVICE FOR DETERMINING A SUFFICIENT STENT REMOVAL FORCE

Abstract

A method for determining a sufficient stent removal force includes providing a balloon fastened to a shaft with a stent securely clamped to the balloon. In order to move or remove the balloon from the stent, a stent removal force has to act on the balloon in the axial direction. The stent, which surrounds the balloon, is clamped between first and second holding jaws with a predefined contact pressure perpendicularly to the axial direction. A predefined, desired stent removal force is then exerted on the balloon via the shaft in the axial direction, at which the balloon should not be removed from the stent. If the balloon moves axially relative to the stent, the force is considered to be too low and the shaft-balloon-stent assembly is discarded as a reject. If the stent position remains constant, the stent removal force is considered to be sufficient.

Claims

1-31 (canceled)

32. A method for determining the sufficiency of a removal force, the method comprising the following steps: providing an implant securely clamped to a catheter part, wherein the catheter part and the implant extend along an axial direction, and wherein a force acting on the catheter part in the axial direction must exceed a nominal removal force in order to move the catheter part relative to the implant in the axial direction; clamping the implant, which is securely clamped on the catheter part, between two holding jaws with a predefined contact pressure acting perpendicularly to the axial direction; exerting a predefined force on the catheter part in the axial direction, the predefined force being a force that does not exceed the nominal removal force and which should not cause the catheter part to move relative to the implant in the axial direction; and: if the catheter part moves relative to the implant in the axial direction in reaction to the exertion of the predefined force, concluding that the removal force of the implant is too low; and if the catheter part does not move relative to the implant in reaction to the exertion of the predefined force, concluding that the removal force of the implant is sufficient.

33. The method according to claim 32, wherein the catheter part consists of a shaft and a balloon fastened to the shaft, the implant is a stent, and the removal force is a stent removal force.

34. The method according to claim 33, wherein the clamping step comprises causing the holding jaws to merely contact the stent.

35. The method according to claim 33, wherein the clamping step comprises merely contacting an outer side of the stent with the holding jaws, the stent running around the balloon in a peripheral direction perpendicular to the axial direction.

36. The method according to claim 32, wherein the clamping step comprises causing the holding jaws to merely contact the implant.

37. The method according to claim 32, wherein the clamping step comprises merely contacting an outer side of the implant with the holding jaws, the implant enclosing the catheter part in a peripheral direction perpendicular to the axial direction

38. The method according to claim 32, which comprises pressing each of the holding jaws with a surface against the implant, wherein the surface is formed from a material selected from the group consisting of silicone and PUR.

39. The method according to claim 32, wherein, in order to exert the contact pressure, pressing a first holding jaw against the implant by way of a pretensioned spring, such that the first holding jaw presses the stent against a second holding jaw and the implant surrounding the catheter part is thus clamped between the two holding jaws by the contact pressure.

40. The method according to claim 32, wherein the axial direction is a vertical direction, and the stent removal force exerted on the catheter part points downwardly in the vertical direction.

41. A device for determining a sufficient removal force, the device comprising: a clamping device having first and second holding jaws disposed opposite one another and configured to hold an implant surrounding a catheter part with a predefinable contact pressure; and an actuator for exerting a predefinable tensile force on the catheter part, said actuator including a fastening device for fastening the catheter part relative to said actuator, to enable said actuator to exert the tensile force on the catheter part via the fastening device.

42. The device according to claim 41, wherein the catheter part is a balloon and the implant is a stent surrounding said balloon, and wherein said actuator is configured for exerting the tensile force on a shaft that is fastened to the balloon.

43. The device according to claim 41, wherein said holding jaws include a first holding jaw with a first material region and a second holding jaw with a second material region, each of the first and second material regions comprises a surface for contacting and holding the implant, and the first and second surfaces extend parallel to one another and perpendicularly to the contact pressure.

44. The device according to claim 43, wherein the first and second material regions are formed of a material selected from the group consisting of silicone and PUR.

45. The device according to claim 43, wherein said holding jaws comprise a first holding jaw with a first carrier and a second holding jaw with a second carrier opposite said first carrier, and wherein said first material region is fastened to said first carrier and said second material region is fastened to said second carrier.

46. The device according to claim 45, wherein said first carrier is fastened to a first arm of said clamping device, and said second carrier is fastened to a second arm of said clamping device.

47. The device according to claim 46, which comprises a spring disposed to pretension said first carrier in a direction towards said second carrier in order to generate the contact pressure.

48. The device according to claim 47, wherein said spring for adjustment of the contact pressure is supported on a screw that meshes via an external thread in an internal thread of said first arm.

Description

[0037] Further features and embodiments of the invention will be explained hereinafter with reference to the drawings, in which:

[0038] FIG. 1 shows a sectional illustration of a clamping device of a device according to the invention for holding the stent surrounding the balloon; and

[0039] FIG. 2 shows a sectional illustration of a fastening device for introducing a tensile force into the shaft connected to the balloon.

[0040] FIG. 1 in conjunction with FIG. 2 shows a device 1 according to the invention for testing the stent removal force of a balloon-stent combination 101, 100. Here, the stent 100 is securely clamped on a balloon 101, such that the stent 100 surrounds the balloon 101 in a peripheral direction U (that is to say transversely to the axial direction z of the stent 100 or of the balloon 101). A shaft 102 extends from the balloon 101 in the axial direction z and can be used to inflate the balloon 101. FIG. 1 in the present case shows an upper part of the device 1, specifically a clamping device 2 for the stent 100. A lower part of the device 1, which is configured to exert a tensile force F.sub.A on the balloon 101, which force points downwardly in the axial or vertical direction z, is shown in FIG. 2.

[0041] In order to remove the stent 100 from the balloon 101 or conversely the balloon 101 from the stent 100, or in order to move the two components 100, 101 axially relative to one another, what is known as the stent removal force F.sub.A has to be applied in the axial direction z, which force must be great enough to ensure the functionality of the balloon catheter (stent-balloon combination 100, 101).

[0042] Whether a sufficiently great stent removal force F.sub.A is present can be tested in accordance with the invention as follows: Firstly, the stent 100 surrounding the balloon 101 is clamped between a first and a second holding jaw 10, 20 with a predefined contact pressure F.sub.B (for example between 1 and 10 N) perpendicularly to the axial direction z. Here, it is preferably provided that the two holding jaws 10, 20 in each case by merely a surface 12a, 22a contact or hold merely an outer side 100a of the stent 100, which surrounds the balloon 101 in the peripheral direction U running perpendicularly to the axial direction z and faces away from the balloon 101. The surfaces 12a, 22a are preferably formed from silicone or PUR or a comparable material.

[0043] A free end 102a of the shaft 102 is clamped in accordance with FIG. 2 preferably in a fastening device 30 of an actuator 3. A predefined, desired stent removal force F.sub.A (for example between 1 and 15 N, in particular between 10 and 15 N) is then applied to the balloon 101 via the shaft 102 in the axial direction z via the fastening device 30 by means of the actuator 3. If the balloon 101 then moves relative to the stent 100 in the axial direction z, the stent removal force F.sub.A of the stent 100 is considered to be too low. Otherwise, the test is deemed to be passed.

[0044] According to FIG. 1, it is preferably provided in respect of the clamping device 2 that the first holding jaw 10 comprises a first material region 12 and the second holding jaw 20 comprises a second material region 22, wherein the two material regions 12, 22 are preferably formed as pads and said surfaces 12a, 22a are designed to hold the stent 100. The two surfaces 12a, 22a run parallel to one another and perpendicularly to the contact pressure F.sub.B. Said material regions/pads 12, 22 are preferably manufactured from a silicone or from PUR, as already mentioned above.

[0045] In order to hold the two material regions 12, 22, the two holding jaws 10, 20 preferably each comprise a carrier 13, 23, wherein the two carriers 13, 23 are opposite one another, and wherein the first material region 12 is fastened to the first carrier 13 and the second material region 22 is fastened to the second carrier 23. Here, the first carrier 13 is fastened to a first arm 2a of the clamping device, wherein in particular the first carrier 13 engages by means of a protrusion 13a in a recess 13b in the first arm 2a. It is also provided that the first carrier 13 in order to generate the contact pressure F.sub.B can be pretensioned by means of a spring 11 in the direction of the second carrier 23, wherein the spring 11 in order to adjust the contact pressure F.sub.B is supported on a screw 14 which engages by means of an external thread 14a in an internal thread 14b of the first arm 2a. The spring 11 is arranged here between the first carrier 13 and the screw 14. Furthermore, the second carrier 23 can also be fastened to the second arm 2b of the clamping device 2 in that the second carrier 23 engages by means of a protrusion 23a in a recess 23b in the second arm 2b.

[0046] According to FIG. 2, the fastening device 30 already mentioned above can also comprise two clamping jaws 30a, 30b for securely clamping a free end 102a of the shaft 2, such that said tensile force or predefined, desired stent removal force F.sub.A can be exerted onto the balloon 101 via the fastening device 30. The tensile force F.sub.A can be exerted for example by means of an actuator 3 onto the shaft 102 in the axial direction z via the fastening device 30.

[0047] FIG. 2 also shows a measurement standard device 5, which can be used to exert a precisely predefinable tensile force on the balloon 101, in particular for the case in which the tensile force F.sub.A is not precisely controllable/measurable, for example in the case of a manual exertion of the tensile force F.sub.A.

[0048] The measurement standard device 5 in accordance with FIG. 2 can be inserted optionally between a free end 102a of the shaft 102a and the fastening device 30, wherein it is possible to exert a tensile force on the measurement standard device 5 in the axial direction via the fastening device 30. This tensile force F.sub.A is also introduced into the free end 102a of the shaft 102 and thus into the balloon 101 via the measurement standard device 5.

[0049] The measurement standard device 5 can comprise for example a first portion 51 and a second portion 52 connected thereto, wherein the two portions 51, 52 detach from one another when they are pulled apart from one another at a predefined force. In this way, a predefined tensile force F.sub.A can be exerted onto the shaft 102 and balloon 101 in the axial direction z, since the two portions 51, 52 separate from one another when this force F.sub.A is reached and precisely delimit the exerted force F.sub.A. The two portions 51, 52 can be formed for example in each case by a magnet 51, 52, wherein the two magnets 51, 52 are attracted by a predefinable force F.sub.A, which is adjustable for example by the choice of the magnets.