Patent Grant
8425589
The present invention claims priority to German Patent Application No. 10-2005-019612.8-43, filed on Apr. 27, 2005 which is incorporated by reference.
The present invention relates to a bodily implant, in particular a stent, for insertion into a living body, having good X-ray visibility, and a method for manufacturing such a bodily implant, and a method for enabling or improving the X-ray visibility of a bodily implant.
Bodily implants or stents of this type protect channels in living bodies such as blood vessels, the esophagus, the urethra, or renal passages, by insertion of the stent and expansion of same inside the bodily channel. In this manner, collapse or occlusion of the particular bodily channel may be prevented. A stent is also used, for example, for intercerebral aneurysms, which are the most common cause of non-traumatic subarachnoid hemorrhages. The incidence of these hemorrhages is approximately 1% in the general population, and, according to autopsy studies, possibly as high as 9%. From a pathomorphological standpoint, intracerebral aneurysms as a rule are genuine saccular aneurysms which are usually localized in vascular arborizations (see, for example, Schumacher, M., “Diagnostic workup in cerebral aneurysms” in Nakstadt PHj (ed.): “Cerebral Aneurysms,” pp. 13-24, Bologna: Centauro (2000)).
Such bodily implants or stents may also be used as carriers for medications to enable local therapy within the bodily channel. Stents are inserted in a collapsed state into a bodily channel, and are expanded after being positioned in the bodily channel. These stents are usually composed of stainless steel or a cobalt-chromium-tantalum alloy. The stents are preferably inserted into the bodily channel by means of an expansion device, such as a balloon catheter, for example, and are expanded there.
The stents may also be composed of other materials, for example polymers, self-degradable materials such as lactic acid materials or derivatives thereof, in addition to nitinol (nickel-titanium alloys) and/or other self-expanding materials such as so-called shape memory materials.
To increase the X-ray visibility of these stents, the stents are often provided with additional elements (known as markers) which are produced from a material having high X-ray visibility. A type of stent is disclosed in U.S. application Ser. No. 11/365,470, filed Feb. 28, 2006, which claims priority from German Application No. 10-2005-013547.1-43, filed Mar. 23, 2005, which are incorporated herein by reference for all purposes.
The present invention is directed to providing a bodily implant having good X-ray visibility which is simple and economical to manufacture, a method for manufacturing such a bodily implant, and a method for enabling or improving the X-ray visibility of a bodily implant.
The bodily implant according to the invention, in particular a stent, for insertion or implantation into a living body has a marker element made of an X-ray visible material which is inserted into a cutout in an implant structure, the cutout having expansions on both of its opening sides so that a conical shape of an exterior side of the implant structure lies adjacent to a conical expansion of an interior side of the implant structure to form a double cone, the marker element being pressed or riveted into the cutout.
As a result of the cutout in the implant structure being outwardly expanded on both opening sides of the cutout, and the marker element being pressed or riveted into the cutout, the marker element makes a positive fit in the implant structure so that the marker element is securely fastened in the implant structure.
In some embodiments, the cutout has an essentially circular shape, and the expansions in each case are essentially conical, the cone angle of the expansions being in the range of approximately 5 degrees to approximately 120 degrees. In some embodiments, the cone angle is approximately 15 degrees to approximately 105 degrees. Because of the acute angle of the cutout, the essentially cylindrical rough marker element is slightly deformed to assume the shape of a double cone.
In addition, both the cutout and the cylindrical marker element may have a relatively large manufacturing tolerance, since these manufacturing tolerances may be compensated for by the riveting or pressing of the marker element into the cutout.
In some embodiments, the marker element is essentially cylindrical before being pressed in, and after pressing or riveting assumes the shape of a double cone, whereby after the pressing or riveting the marker element is essentially flush with the implant structure on the inside and outside.
By virtue of the marker element being essentially flush with the implant structure after being pressed in, it is possible to avoid transitional edges, which otherwise could cause injury to the bodily channel during insertion.
In some embodiments, the marker element comprises a material having good X-ray visibility, i.e., a material with high absorption of X-ray beams, for example gold, platinum, tantalum, platinum alloy, platinum-iridium, or niobium.
The present invention further relates to a method for increasing or enabling the X-ray visibility of a bodily implant, in particular a stent, comprising: forming a cutout in an implant structure by means of a laser so that the cutout assumes a conical shape on an exterior side of an implant structure; providing a conical expansion of an interior side of the implant structure so that the conical shape lies adjacent to the conical expansion to form a double cone; inserting an essentially cylindrical marker element into the cutout; and pressing the marker element. In some embodiments, the conical expansion is preferably applied on the interior side by drilling. The conical expansion is applied in essentially up to half the wall thickness of the bodily implant.
The present invention further relates to a method for manufacturing a bodily implant, in particular a stent, having an X-ray visible marker element, comprising: forming a cutout in an implant structure; expanding the cutout outwardly on both opening sides so that a conical shape on an exterior side of the implant structure lies adjacent to a conical expansion of an interior side of the implant structure to form a double cone; and pressing or riveting in the marker element. In some embodiments, the conical expansion is preferably applied on the interior side by drilling. The conical expansion is applied in essentially up to half the wall thickness of the bodily implant, resulting in high strength, i.e., mechanical locking, of the marker element in the cutout in the implant structure.
The following detailed description together with the accompanying drawings will provide a better understanding of the nature and advantages of the present invention.
As shown in
In the embodiment illustrated, the outer and inner cones 12, 14 lie adjacent to one another so as to form a ridge 13 at the intersection of the outer and inner cones 12, 14. As shown in
A marker element 2 may be inserted into this double cone by pressing or riveting, thereby ensuring a positive fit of the marker element 2. This results in high mechanical strength, i.e., locking, of the marker element 2 in the bodily implant 1. Adhesive bonding, welding, etc. is thus unnecessary, thereby allowing the manufacturing costs for the bodily implant 1 to be kept low.
In some embodiments, the inner cone 14 is applied by drilling in the cutout 10 (so-called eyelet) of the bodily implant 1. However, both the inner cone 14 and the outer cone 12 may also be provided by laser cutting, etching, erosion, etc. It should be appreciated that the invention is not limited to the shape of a cone 12, 14. Instead, any other shape of an expansion 12, 14 may be applied in the cutout 10, provided that a positive fit or barbed hook effect is formed or produced between the marker element 2 and the cutout 10. Thus, the expansion may be applied, for example, only in certain peripheral regions of the cutout 10, such as four expansions, each offset from one another by 90° in the peripheral direction.
A continuous expansion or a convex expansion may also be applied instead of a cone 12, 14, as long as an interior surface of the cutout 10 is configured not radially (as for a cylinder) but instead is inclined at an angle with respect to the center axis of the cutout 10, to form a positive fit or barbed hook effect of a marker element 2 in the cutout 10. However, the double cone may also be used on flat structures, sheets, for example, if the outer cone 12 having the angle a is additionally applied. In some embodiments, the outer cone 12 is produced by laser cutting of the cutout 10 (eyelet) for a cylindrical bodily implant 1, such as a stent.
Because the material of the marker element 2 flows into the annular gap 18, the manufacturing tolerances for both the cutout 10 and the marker element 2 can be relatively high, since the caulking effect of the marker element material can compensate for these manufacturing tolerances.
In some embodiments, the marker 2 comprises an X-ray visible material, for example gold, platinum, tantalum, niobium, or a platinum alloy such as platinum-iridium. The dimensions of the marker element 2 may be matched to the cutout 10 such that, after pressing, the marker element 2 is essentially flush with the implant structure on the inside and outside. However, if there is an increased demand for flatness, the marker element 2 may also be dimensioned slightly larger, and after pressing may undergo surface treatment, for example by a laser, electropolishing, or grinding.
The expansions 12, 14 of the cutout 10 form a positive fit between the marker element 2 and the implant structure 11, thus ensuring a good attachment of the marker element 2 in the implant structure. Adhesive bonding or welding may be omitted to economize on production costs. However, adhesive bonding or welding may also be performed in addition to the positive fit.
In some embodiments, the bodily implant 1 comprises one of the following materials: stainless steel, cobalt-chromium-tantalum alloy, polymers, self-degradable materials such as lactic acid materials or derivatives thereof, in addition to nitinol (nickel-titanium alloys) and/or other self-expanding materials such as so-called shape memory materials.
While the present invention has been described with respect to specific embodiments, those skilled in the art will appreciate that the invention is intended to cover all modifications and equivalents within the scope of the following claims.
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