Apparatus for reducing the diameter of a stent

Abstract

The apparatus (1a) for reducing the diameter of a stent (2) includes compressors (9a) which are supported on a circumferential abutment (3a) and act, at least indirectly, radially on the outer surface of the stent (2). Resiliently elastic tensioning members (15) are provided between the radially inwardly displaceable segmental compressors (9a) and the abutment (3a) and can be acted upon by a pressure fluid in opposition to a resiliently elastic rebound force (21).

Description

BACKGROUND OF THE INVENTION [0001] The invention relates to an apparatus for reducing the diameter of a stent. [0002] Such an apparatus belongs to the state of the art in view of the DE 297 14 857 U1. It includes a clamping tongs with arms movable relative to one another and configured with conical openings. The openings expand towards the central transverse plane of the clamping tongs. [0003] The apparatus further includes a shaping body for a stent which can be received in the openings of the clamping tongs, i.e. the stent includes a short central portion, which is continued by two conically descending portions in a direction of the end surfaces, and two cylindrical end portions. The shaping body has a central passageway for receiving a stent. [0004] The shaping body is subdivided in radial direction by several longitudinally extending slots to define interconnected compressors. The cross section of the compressors is wedge-shaped, with the compressors narrowing in a direction of ...

AI Technical Summary

Benefits of technology

[0010] The basic idea of the invention is the use of a pressure fluid (compressed air or pressure liquid) which can be adjusted precisely and reproducibly to the respectively desired and required pressure level. The pressure fluid is received in flexible tensioning members which are arranged between radially inwardly movable segmental compressors and an abutment disposed circumferentially about the compressors. When the tensioning members are acted upon by the pressure fluid, the compressors shift radially inwards while being supported on the abutment and reduce the diameter of a stent precisely to the extent, as desired.

[0011] In this context, the invention also allows to subject the circumference of a stent, at least indirectly, to different pressures. In other words, a stent is subjected for example to a certain pressure on opposite circumferential sections by tensioning members provided there, while a different pressure is applied on the other circumferential sections. In this way, certain ovality may be imparted upon the stent.

[0012] The invention provides the conditions for a stent as such to be reduced (crimped) in diameter and to be placed subsequently upon a catheter. The invention allows however in addition to press a stent directly upon a catheter. The invention is especially advantageous when used for stents coated with medicaments. As in such a case, the medicament-coated stent is surrounded by a tube as protective envelope, the apparatus according to the invention is prevented from damaging the medicament coating. When properly securing the stent upon a catheter, the tube can then easily be removed.

[0021] This embodiment thus involves a stent to be deformed having circumferentially several, for example eight or twelve, compressors with a configuration in the form of a pie slice which are as such radially displaceable by the tensioning members between the compressors and the struts on the abutment. The portions, which form the resistance surfaces on the struts and are thickened by material, directly contact the diverging legs of the compressors. The legs of the compressors are provided at the radially outer end with projections, optionally arranged in pairs, which point to one another. This ensures the exact radial displacement capability. The inwardly directed spring tongues at the legs of the compressors have, preferably, a slightly arched contour and rest against the crossbars of the struts at their sides facing the circumferential abutment. These spring tongues thus provide that the compressors are in effect biased continuously in the direction of the abutment. Their spring force can be overcome by the pressure fluid in the tensioning embers.

Problems solved by technology

Errors as a result of human inadequacy cannot be avoided hereby.

As stents are typically placed upon catheters and the stents as well as the catheters have tolerances, it becomes difficult to attain a consistent result, each time the diameter of a stent is to be reduced (crimped).

It is not possible to tailor individual sections of length portions for a reduction in diameter.

A drawback of this apparatus is the fact that stents of only up to a defined length can be placed in it and that the compression of the stent can be evenly compressed only along the entire length.

Images