News Column

Patent Application Titled "Methods for the Manufacture of Intraluminal Endoprosthesis" Published Online

August 28, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors VERSCHUEREN, Peter (Bierbeek, BE); PALLARI, Jari Heikki Petteri (Rovaniemi, FI); ENGELBORGHS, Koen (Vaalbeek, BE); VANCRAEN, Wilfried (Huldenberg, BE), filed on April 4, 2014, was made available online on August 14, 2014.

The assignee for this patent application is Materialise N.v.

Reporters obtained the following quote from the background information supplied by the inventors: "The application provides intraluminal prosthesis, methods for the manufacture of intraluminal endoprostheses and mandrels for the manufacture of such endoprostheses.

"Endoprostheses are a commonly used way of dealing with diseases in interventional medicine and surgery. Mesh-based endoprostheses such as stents, stent grafts, heart valve frames, etc. are of particular importance in cardiovascular applications. Also other fields of medicine make use of such endoprostheses, e.g. pulmonary tract stents, oesophagus stents, etc.

"Intraluminal endoprostheses such as stents are typically designed such that they are deployable by catheter or similar stent delivery system, as it is desirable for stent placement procedures to be minimally invasive. Some stents are self-expandable, whereas other stents are inflated via a balloon inside the stent in order to force the stent to open.

"Currently, the majority of stents have a cylindrical outer shape, regardless of the anatomy of the lumen in which the stents are to be deployed. Although stents typically are flexible, insertion of a stent which is not optimized to fit the exact patient's anatomy often leads to suboptimal intervention results including localized turbulence in the blood, unnatural stresses on the vessel wall, vessel injury, endoprosthesis breaking, endoprosthesis migration, etc.

"U.S. Pat. No. 7,722,663 describes a method for manufacturing a custom, personalized endoprosthesis using a mandrel which is adapted to the actual patient's anatomy. In this method, a V-shape undulated wire, typically in a shape memory or superelastic alloy, is draped around the mandrel, followed by a heat treatment to set the wire onto the mandrel. The wire is then unwrapped from the mandrel in a helical fashion. A problem with this method is that it only allows for the use of shape memory alloy wires or super-elastic wire without links between two adjacent rows of helical wires. Indeed, unwrapping of the wire from the mandrel is only possible when the adjacent rows are not interconnected. Additionally, a heat treatment process on the super-elastic wire is required to restore the desired shape after it has been removed from the mandrel.

"A solution to these problems is presented in US patent application 2005/096729, which discloses a method for the manufacture of a stent, wherein the stent is separated from the mandrel by dissolving the mandrel. However, this method involves the use of hazardous acids, and limits the amount of materials which can be used to manufacture the stents.

"Accordingly, there is a need for improved methods for the production of endoprostheses such as stents, which at least partially mitigate the problems stated above."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "The application provides endoprostheses, molds or mandrels for the manufacture of endoprostheses, and methods for the manufacture thereof. Methods have been developed which enable the production of molds comprising or consisting of two or more pieces, more particularly three or more pieces, which are joined via a weakened seam, such that the molds can be broken into two or more fragments in a controlled way.

"The application provides methods of manufacturing a mold for an endoprosthesis, more particularly a personalized endoprosthesis fitting a patient's lumen anatomy comprising the step of meshing the mold or mandrel (or an image or model thereof), so as to determine the location of the seams forming the pieces within the mold or mold part. In particular embodiments, methods for manufacturing a mold for an endoprosthesis are provided, comprising the steps of:

"a) providing a 3D model of said mold for an endoprosthesis; b) meshing said 3D model, so as to divide said model into two or more solid tile pieces with seams between said tile pieces; c) manufacturing said mold based on the meshed 3D model, thereby providing a mold comprising solid tile pieces with seams between said tile pieces;

"wherein the tile pieces are joined together at the seams with a strength which is reduced compared to the strength of said tile pieces.

"In particular embodiments, the 3D model is or is based on a 3D image of said patient's lumen anatomy or part thereof. This can be of interest in the provision of a personalized endoprosthesis. Thus, in particular embodiments, the methods for manufacturing a mold for a personalized endoprosthesis fitting a patient's lumen anatomy, comprise the steps of: a') providing a 3D image of said patient's lumen anatomy or part thereof; b') optionally designing a 3D model of a mold for a personalized endoprosthesis based on said 3D image of said patient's lumen anatomy or part thereof c') meshing said 3D image or said 3D model, so as to divide said image or model into two or more, preferably three or more solid tile pieces and spacings or seams between said tile pieces; and d') optionally, manufacturing a mold based on said 3D image or said 3D model, thereby providing a mold comprising solid tile pieces interlinked through seams.

"In the methods envisaged herein, the nature and/or width of the spacings or seams between the tiles is such that the tile pieces are joint together at the seams with a strength which is reduced compared to the strength of said tile pieces during manufacturing of said mold.

"In particular embodiments of the methods as described herein, the mold is manufactured by additive manufacturing, more particularly by a technique such as, but not limited to stereolithography, selective laser sintering, selective laser melting and/or fused deposition modeling.

"In particular embodiments, the application provides methods for generating a personalized mold for an endoprosthesis for a patient, characterized in that they comprise the steps of: a) providing a 3D model of a mold for an endoprosthesis based on 3D images of the patient; and b) meshing said 3D model, so as to divide said model into two or more solid tile pieces and spacings between said tile pieces;

"whereby the nature and/or size of said spacings is provided such that, upon executing said model in an additive manufacturing process, the tile pieces are joint together with spacings or seams having a strength which is reduced compared to the strength of said tile pieces.

"In particular embodiments of the methods of generating a mold for a personalized endoprosthesis fitting a patient's lumen anatomy as described herein further comprise the step of providing onto the surface of the mold one of or more structural features not corresponding to the patient's lumen anatomy, which features are of use in the manufacture of said endoprosthesis on said mold. More particularly such features comprise additional grooves in which one or more wires for the endoprosthesis can be positioned.

"The application further provides methods for converting a 3D model into a crushable mold, which methods comprise meshing said 3D model so as to divide said model into three or more solid tile pieces with seams between said tile pieces, whereby the meshing pattern contains information such that during manufacturing of said mold, the strength of the seams is reduced compared to the strength of said tile pieces.

"The application further provides methods for manufacturing a personalized endoprosthesis using the molds as provided herein. More particularly, these methods may comprise the steps of making a mold based on the patient's lumen anatomy, which mold may comprise or consist of tile pieces linked together by seams or spacings of which the strength is reduced compared to the tile pieces such that the mold can be broken in a controlled way, making the endoprosthesis on the mold and removing the mold from the endoprosthesis by breaking the mold. In particular embodiments, the methods for manufacturing a personalized endoprosthesis as described herein comprise the steps of: a) meshing a 3D image of said patient's lumen anatomy or part thereof or a 3D model obtained therefrom, so as to divide said image or model into two or more, more particularly three or more solid tile pieces and spacings between said tile pieces; b) manufacturing a mold based on said 3D image or said 3D model, thereby providing a mold that may comprise solid tile pieces interlinked through seams based on the model or image obtained under (a); and c) manufacturing an endoprosthesis using said mold obtained in step b) as a mandrel; and d) mechanically breaking and removing said mandrel by applying external mechanical force, thereby obtaining a personalized endoprosthesis fitting the patient's lumen anatomy.

"In particular embodiments, the methods as envisaged herein thus start from a 3D image of the patient's lumen anatomy. Thus in particular embodiments, the methods comprise the steps of: a) providing a 3D image of said patient's lumen anatomy or part thereof; b) optionally designing a 3D model of a mold for a personalized endoprosthesis based on said 3D image of said patient's lumen anatomy or part thereof c) meshing said 3D image or said 3D model, so as to divide said image or model into two or more, more particularly three or more solid tile pieces and spacings between said tile pieces; d) manufacturing a mold based on said 3D image or said 3D model, thereby providing a mold that may comprise solid tile pieces interlinked through seams based on the model or image obtained under ; and e) manufacturing an endoprosthesis using said mold obtained in step d) as a mandrel; and f) mechanically breaking and removing said mandrel by applying external mechanical force, thereby obtaining a personalized endoprosthesis fitting the patient's lumen anatomy.

"In particular embodiments of these methods, the mold is made by additive manufacturing.

"In further particular embodiments of the methods of manufacturing a personalized endoprosthesis, the endoprosthesis is formed on the mold using laser cutting.

"In particular embodiments, the step of manufacturing the prosthesis on the mold may comprise providing one or more wires for the endoprosthesis on the mold. In further particular embodiments, a first and a second wire are provided on the mold, which wires are interconnected. More particularly, the steps of providing one or more wires on the mold may comprise i) wrapping a first wire in a helical manner around the mold; ii) wrapping a second wire in a helical manner around the mold, wherein said second wire intersects one or more times with said first wire; and iii) connecting said first and said second wire in at least some of the places where said first and second wire intersect.

"In particular embodiments of the methods as described herein the material of the wires is selected from a shape memory alloy, super elastic alloy, polymer, stainless steel or any other material which is used in endovascular prosthesis.

"In particular embodiments of the methods for manufacturing a personalized endoprosthesis, the step of manufacturing the endoprosthesis on the mold may comprise providing a deploy mechanism for said endoprosthesis.

"Also provided herein are personalized endoprostheses obtainable by the methods described herein. More particularly, the endoprosthesis is an endovascular endoprosthesis, more particularly, a stent or a heart valve frame or a combination thereof.

"Also provided herein are molds for manufacturing a personalized endoprosthesis, which molds are provided with a tiled structure, i.e. tiles interconnected at the seams, whereby the seam strength is lower than the tile strength. In particular embodiments, the molds consist of one and the same material (or combinations of material). In further particular embodiments the molds comprise at least 10 tile pieces, more particularly at least 10 tile pieces of comparable size. In further particular embodiments, the mold may consists of or may comprise a part consisting of more than 10 pieces of comparable size. The molds as envisaged herein may be used as a mandrel and can be broken into small pieces in a controlled and optionally predefined manner, which facilitates separation of the endoprosthesis and the mandrel. Furthermore, the weakened seams of the models can be made such that they do not compromise the rigidity of the mold.

BRIEF DESCRIPTION OF THE DRAWINGS

"The following description of the figures of specific embodiments is merely exemplary in nature and is not intended to limit the present teachings, their application or uses. Throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

"FIG. 1--3D image of the relevant part of the patient's vessel anatomy is provided according to a particular embodiment.

"FIG. 2--A model of a mold for a patient-specific prosthesis of a vessel which has been meshed according to a particular embodiment.

"FIG. 3--Example of a personalized vessel endoprosthesis which can be obtained according to an embodiment.

"FIG. 4--3D image of the relevant part of the patient's heart valve anatomy is provided according to a particular embodiment.

"FIG. 5--A model of a patient-specific mold of a heart valve which has been meshed according to a particular embodiment.

"FIG. 6 A: Schematic drawing of two pieces (8, 9) separated by a planar seam (10) with uniform thickness. B-G: Schematic drawing of two tile pieces (8, 9) separated by a seam (10) with non-uniform thickness.

"In the figures, the following numbering is used: 1--3D image of patient's lumen anatomy; 2--meshed 3D image; 3--tile pieces; 4--seams or spacings; 5--personalized vessel endoprosthesis; 6--3D image of part of a patient's heart valve anatomy; 7--meshed 3D image; 8, 9--tile piece; 10--seam"

For more information, see this patent application: VERSCHUEREN, Peter; PALLARI, Jari Heikki Petteri; ENGELBORGHS, Koen; VANCRAEN, Wilfried. Methods for the Manufacture of Intraluminal Endoprosthesis. Filed April 4, 2014 and posted August 14, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1444&p=29&f=G&l=50&d=PG01&S1=20140807.PD.&OS=PD/20140807&RS=PD/20140807

Keywords for this news article include: Angiology, Prosthetics, Heart Valves, Endoprosthesis, Medical Devices, Materialise N.v..

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