FR2858207A1 - Endoprosthesis for hollow organ in human or animal body has open cavities for controlled release of medication - Google Patents

Abstract

The endoprosthesis or stent has a series of open cavities on its outer surface to contain and release a medication substance. The cavities are more or less cylindrical in shape and have two open ends; they can be made, for example, in the form of twisted spiral connections (7) between filaments (F1, F2) of 0.19 - 0.30 mm diameter in a mesh portion of the prosthesis. In a variant the prosthesis can be in the form of a tube of a supple biocompatible material with cavities in projections on its outer surface. The cavities can be made to contain more than one type of medication, e.g. an antimitotic, anticoagulant, or antiinflammatory substance.

Description

The present invention relates to a

  stent for a human or animal hollow organ, or stent. These stents are intended in particular to bridge aneurysms or to maintain the opening of dilated stenotic arteries.

  When a stent is placed in a hollow organ, it is desirable to provide the region operated certain drug products, including, in the case of arteries, to avoid the formation of stenosis produced by the proliferation of vascular endothelium .

  For this purpose, it is known to coat the outer wall of the stent with the product in question.

  The disadvantage of this solution lies in the difficulty of dosing the product along the stent, and in the brittleness of the coating layer.

  The invention aims to allow better control of the release of the drug product.

  For this purpose, the invention relates to a stent for a human or animal hollow organ, characterized in that it comprises on its outer surface a plurality of open cavities for receiving at least one drug product.

  The endoprosthesis according to the invention may comprise one or more of the following characteristics, taken separately or in all their technically possible combinations: each cavity extends between two open ends.

  each cavity has a substantially cylindrical shape.

  the stent comprises, over at least a portion of its length, a tubular trellis of elastic wire, in particular a metallic wire, this trellis having a plurality of nodes each defined by two wires twisted together over at least one turn, the twist being twisted substantially contiguous and defining internally an open cavity for receiving said drug product.

  the endoprosthesis comprises a flexible biocompatible material tube on the outer surface from which a plurality of protuberances protrude, an open cavity being formed in each protuberance.

  at least some of said cavities are intended to receive at least two medicinal products.

  - Some of said cavities are intended to receive a first drug product and other cavities are intended to receive a second drug product.

  said drug product is an antimitotic, an anticoagulant or an anti-inflammatory.

  each open cavity contains said medicinal product.

  Exemplary embodiments of the invention will now be described with reference to the accompanying drawings, in which: - Figure 1 shows in perspective a stent, in the deployed active state; Figure 2 schematically shows the development of the vicinity of a node of the stent of Figure 1; - Figure 3 is a view similar to Figure 2 corresponding to another node of the stent; - Figure 4 is a view similar to Figure 2, corresponding to yet other nodes of the stent - Figure 5 shows a detail of a variant; - Figure 6 shows a detail of another variant; - Figure 7 shows a detail of yet another variant; - Figure 8 is a sectional view along the line VIII-VIII of Figure 7; and Figure 9 is a partial perspective view of another variation.

  The stent shown in Figure 1 consists of a lattice 1 itself formed by eight elastic wires, such as the son F1, F2 and F3, twisted together in a manner which will be detailed below. These wires define, over the length of the lattice, seven successive regions which are, from top to bottom in FIG. 1: an end region 2 with eight loops 3; a first relatively flexible region 4 which has first twisted nodes 5; a first relatively steep region 6, which has second twisted nodes 7; a second relatively soft region 8 at nodes 5; a second relatively steep region 9 to 20 knots 7; a third relatively flexible region 10 at nodes 5; and - an end region 11 with twisted end 12.

  Considering the F1 wire: - the loop 3 is constituted by the twist of the wire F1 on itself, on at least a half-turn; each node 5 is constituted by the twisting of the wire F1 with an adjacent wire such as F2, F3 on a lathe; each node 7 consists of the twisting of the wire F1 with an adjacent wire such as F2, F3 over a turn and a half; and each end twist 12 is constituted by the twisting of the wire F1 with an adjacent wire such as F2, F3 on more than one turn, on two turns in the example shown.

  Thus, on either side of each node 5, each 5 strand of wire that forms the node extends in two directions parallel to one another and close to each other, as illustrated schematically on These two directions are indicated by D1 and D1 for the F1 wire, by D2 and D2 for the wire F2, which is shown in mixed line.

  On the other hand, with regard to the nodes 7 (FIG. 3), each wire apart along two directions D1, D'1 or D2, D'2 which form between them an angle much smaller than 180, for example a right angle or an acute angle as shown to form two adjacent sides of a lattice mesh. On the other hand, the direction D'1 is substantially parallel to D2 and close to it, and the direction D'2 is substantially parallel to D1 and close to it.

  As shown in bold lines in FIG. 1, in the example shown, the thread F1 starts from a twist 12 and then successively forms a knot 5, a knot 7, a knot 5, another knot 5, a knot 7, a knot node 5, another node 5, a loop 3, a node 5, another node 5, a node 7, a node 5, another node 5, a node 7, a node 5 and another twist 12.

  It is found that regions 4, 8 and 10 containing nodes 5 (a ring of nodes 5 for region 10, two knot crowns 5 for regions 4 and 8) are more flexible than those 6 and 9 which contain nodes 7 (a ring of nodes 7 for each of these regions).

  The arrangement of the two types of nodes makes it possible to obtain either a very flexible stent (with only knots 5), a stent relatively inflexible (with only knots 7), or a stent with more flexible sections than the stent. others, as in the example of Figure 1. A mixed part of such a stent is shown schematically in Figure 4.

  Thus, the stent can be configured, for each surgical operation, to easily adapt to the sinuosities of the arteries considered.

  The endoprosthesis thus described may be plastic expansion. In this case, it initially has a reduced, stable diameter, and its deployed active position is achieved by means of an inflatable balloon.

  The stent may also be self-expanding.

  In this case, its deployed position shown is its stable configuration. For its storage, a wire 13 is threaded through all the loops 3 and then stretched to bring them closer to each other. This allows the stent to be radially compressed into a holding sheath, which is removed to release the stent, for example by longitudinal opening as described in EP 0 584 352 B1. The same wire can be used to perfect the positioning of the stent in the vessel.

  In the example of Figure 1, end twists 12 may be troublesome in some applications as they may injure adjacent tissues. In this case, it is possible to use the variant of FIG. 5. In this case, one of the two wires twisted at the lower end of the stent forms a loop 14 by folding on itself, and the The folded end is twisted back on itself again, for example on one turn, to substantially abut the end of the other wire.

  As illustrated in FIG. 6, each node 5 and / or 7 may also be formed with a loop 103.

  In these variants, the ring crowns 14 and 103 serve to ensure the anchoring of the stent after its introduction. This anchoring can be promoted by arranging in each loop a ring made of a material that promotes the development of fibroblasts, especially polyoxymethylene.

  In a variant also, as illustrated in FIGS. 7 and 8, at least a portion of the nodes of the lattice, in particular the knots twisted over at least one complete turn, may be twisted with substantially contiguous turns on a mandrel of predetermined diameter, for example 0 , 2 mm. These nodes then each form a small or open cylindrical cavity or conduit at both ends, into which a controlled release drug product can be stored. It may be in particular a product avoiding stenosis produced by the proliferation of the vascular endothelium. An example of such a product is an antimitotic marketed under the name TAXOL.

  The multiplicity of conduits 15 and their distribution 20 over the entire surface of the stent makes it possible to release the product in question in an optimal manner. In addition, these conduits are stable over time, can be calibrated at will, and they constitute anchoring protrusions of the stent by invasion of the ducts 15 by the fibroblasts.

  Alternatively, each cavity 15, or some of them, may contain more than one drug product, selected for example from antimitotics, anticoagulants and anti-inflammatories, or different products may be distributed between the different cavities.

  As illustrated in FIG. 8, in a variant, the multiple cavities 15 can be obtained by molding / piercing protuberances 16, for example cylindrical, provided on the outer surface of a stent tube 101 made of biocompatible synthetic material.

  In all variants where the stent comprises a mesh, it may be fully embedded in an elastic film as described in the aforementioned EP-B1, or otherwise associated with a sealed elastic sleeve.

  It should also be noted that: the stent may have a shape other than tubular, in particular Y; the meshes of the lattice 1 may have, according to their position, different shapes and / or dimensions, with the aim of locally adjusting the elasticity of the stent; and that certain wires may be different from the others, in particular by their diameter. For example, wires 0.19 mm in diameter and other wires 0.30 mm in diameter may be used.

Claims (9)

  1. Endoprosthesis for a human or animal hollow organ, characterized in that it comprises on its outer surface a plurality of open cavities (15) intended to receive at least one medicinal product.   2. Endoprosthesis according to claim 1, characterized in that each cavity (15) extends between two open ends.   3.Endoprosthesis according to claim 2, characterized in that each cavity (15) has a substantially cylindrical shape.   4. Endoprosthesis according to any one of claims 1 to 3, characterized in that it comprises, over at least a part of its length, a tubular lattice (1) of elastic wire, in particular metallic, this lattice comprising a plurality nodes (5, 7) each defined by two wires (F1, F2, F1, F3) twisted together over at least one turn, the twist being substantially contiguous turns and internally defining an open cavity (15) for receiving said drug product.   5. Endoprosthesis according to any one of claims 1 to 3, characterized in that it comprises a tube (101) of biocompatible flexible material on the outer surface of which project a plurality of protuberances (16), an open cavity ( 15) being formed in each protuberance.   6. Endoprosthesis according to any one of claims 1 to 5, characterized in that at least some of said cavities (15) are intended to receive at least two medicinal products.   An endoprosthesis according to any of claims 1 to 6, characterized in that some of said cavities (15) are for receiving a first drug product and other cavities (15) are for receiving a second medicinal product.   8. Endoprosthesis according to any one of claims 1 to 7, characterized in that said medicinal product is an antimitotic, an anticoagulant or an anti-inflammatory.   9. Endoprosthesis according to any one of claims 1 to 8, characterized in that each open cavity (15) contains said drug product.