FR2694688A1 - Expandable tubular prosthesis. - Google Patents

Abstract

The present invention relates to an expansible tubular prosthesis capable of being introduced in an anatomical conduit of a human or animal body and to a device for introducing such prosthesis. A radially expansible tubular prosthesis (1) is comprised of a plurality of transversal elastic filiform braces (2) which are substantially parallel to each other, substantially similar, and a longitudinal brace (31) arranged between at least two thin sheets (3) of plastic material; the prosthesis is wound and its edges overlap. The technical field of the invention is the fabrication of anatomical prostheses.

Description

EXPANDABLE TUBULAR PROSTHESIS
DESCRIPTION
The present invention relates to an expandable tubular prosthesis capable of being inserted into an anatomical conduit of the human body or of an animal, and its introduction device.

 The technical field of the invention is that of the manufacture of anatomical prostheses.

 The present invention relates in particular to tubular prostheses capable of expanding radially after having been introduced into an anatomical canal of the human body, for example such as a bronchus, the trachea, a blood vessel, the esophagus, etc.

 Already known from patent application FR2627982 (ARTEMIS) a tubular endoprosthesis for anatomical conduit whose outer surface is provided with protuberances which may be constituted by rounded nipples, arranged in spaced alignment and oriented along generatrices of the tubular body; according to the embodiment described in this document, the prosthesis is made of silicone elastomer; the establishment of this prosthesis necessarily poses difficulties in introducing the prosthesis into the conduit intended to receive it due in particular to the presence of the nipples on its external surface as well as to its thickness which is made necessary in particular in the case of use silicone as a constituent material, in order to ensure sufficient mechanical characteristics for the prosthesis.

 Also known from patent application FR2617721 is a shape memory alloy prosthesis capable of expanding after being introduced into the body under the effect of the heating caused by the supply of hot body fluid, on the location of the prosthesis; according to the embodiments described in this document, this prosthesis can be constituted by a leaf spring or a wire winding with an oval section, or else be constituted by a woven tube or a woven mesh, or else a laminated and wound sheet.

 Patent application EP481365 (ANGIOMED) also describes a radially expandable prosthesis made of an alloy having a transition temperature above room temperature and below the temperature of the body into which it is to be introduced, and the diameter of which, at a temperature below the transition temperature, is less than the diameter of the vessel in which it is to be placed.

 The object of the present invention is to remedy the drawbacks of known radially expandable tubular prostheses; indeed prostheses of the type described in patent FR2627982, with relatively thick walls, are very difficult to implant, and, in particular in the case of use as a prosthesis, bronchial, because of their thickness limit the useful passage diameter in the prosthesis for the respiratory flow; moreover, this type of prosthesis is difficult to deposit once the fitting has been carried out, which may be made necessary in particular in the case of fitting a prosthesis intended to stem the development of tumor and as well as in a general case due to the development and tissue growth near this prosthesis.

 In addition, prostheses in general essentially metallic formed by a winding of wires or by a tubular mesh are quickly invaded and encompassed by the development of the tissues against which the prostheses are pressed during installation, which also prevents their subsequent removal. .

In addition, prostheses using shape memory alloys such as those described in documents FR2617721 and
EP481365 are expensive and require complex positioning devices which are difficult to handle in certain operating cases.

 The problem posed therefore consists in providing a radially expandable tubular prosthesis whose walls are not too thick, easy to implant in particular using the operating channel of a fibroscope, which may be subsequently removable (or withdrawable from the body), and to provide a device for introducing such a prosthesis.

The solution to the problem posed consists in providing a prosthesis (or stent of generally substantially cylindrical shape) tubular (intended to be introduced into a canal such as a bronchus, a trachea, a blood vessel or the esophagus of the human body or an animal) radially expandable (so as to be able to be shaped according to at least two states, a folded state where said prosthesis has a small diameter D1 and an expanded state where said prosthesis has a diameter
D3 greater than said diameter D1), which comprises several elastic filiform elements (reinforcements), substantially parallel to each other, substantially identical, arranged between at least two thin sheets (of plastic material, assembled by gluing), each of said sheets comprising fibers, of preferably woven fibers, and synthetic plastic, impregnated with silicone.

 According to a preferred embodiment of the invention, said elements or frames are regularly spaced, are preferably metallic and of small thickness.

 Advantageously, each of said sheets has a thickness close to l.î-4 meter (0.1 mm) to 1.10-3 meter (1 mm), preferably close to 2 to 3 10-4 meter and is cut into a substantially rectangular shape , and the total thickness of the prosthesis being less than 2.10-3 meters (2 mm), for example close to 4.10-4 meters to 5.10-4 meters.

 Advantageously, the ratio of said diameter D3 in the expanded state to said diameter D1 in the folded or rolled up state is at least equal to 1.2 and less than 2, and said diameter D3 in the expanded state is slightly greater than the diameter D2 internal of the channel into which said prosthesis is intended to be inserted.

 Advantageously, said fibers and / or said fabric mainly consist of dacron.

 Advantageously, said sheets are assembled by a translucent silicone adhesive.

 Advantageously, said frames are arranged substantially along planes perpendicular to the axis of said substantially cylindrical prosthesis, and said center-line of said frames is between 3.10-3 meters and 1.10-2 meters and preferably said center-line is between 5.10 -3 meter and 8.10-3 meter.

 Advantageously, said reinforcements have a substantially rectangular or circular section close to 1 to 3 10-7 mZ and are mainly made of stainless steel.

 Advantageously, said fibers are arranged on the internal part of an internal sheet forming part of said sheets and are arranged on the external, respectively internal part of an external sheet, so that the internal face of said prosthesis is smooth, and so that the outer face of said prosthesis is slightly rough, respectively smooth.

 The solution to the problem also consists in providing a device for introducing, into the human or animal body, a radially expandable tubular prosthesis essentially constituted by several elastic filiform elements disposed between at least two thin sheets, which device the introduction comprises a cannula, or "candle", preferably for single use, substantially cylindrical, flexible, for example made of PVC or polyethylene, tapered, or profiled, substantially frustoconical, at one end and comprising at least one substantially circumferential groove, of substantially rectangular section, preferably located in a cylindrical part of said cannula, near said tapered frustoconical end, the depth of which is close, for example little greater, to the total thickness of said prosthesis and whose length is little greater than the length of said prosthesis, which cannula has a diameter outer D4 neighbor, for example slightly greater, of said diameter D1 of said prosthesis in the wound state, which insertion device preferably further comprises a flexible tubular jacket or sheath, for example made of teflon / tetrafluoroethylene, of internal diameter D5 neighboring of said external diameter D4 of said cannula, of small thickness, of length at least equal to the length of the cylindrical part of said cannula, which sleeve is capable of intimately surrounding said cannula and said prosthesis in the wound state in said groove said cannula and to maintain said prosthesis inside said groove, until said prosthesis is positioned in the channel of the human or animal body in which it is to be implanted.

 Among the many advantages provided by the invention, it should be noted that thanks to the solid or sealed walls of the prosthesis according to the invention, the invasion or growth of the tissues is intimately avoided in contact with this prosthesis and thus the possible subsequent removal of the prosthesis.

 Furthermore, when a prosthesis with a smooth internal wall is available according to a particular embodiment of the invention, this smooth internal surface makes it possible to avoid the deposition of secretions inside this prosthesis; the invention also makes it possible to obtain a prosthesis having a reduced wall thickness as well as easier positioning, not requiring a sophisticated and / or bulky tool or introduction device.

Furthermore, thanks to the presence of said elastic reinforcements, despite the small thickness of the prosthesis, good resistance to crushing is provided,
In addition, according to an important characteristic of the invention, it is possible to implant prostheses of which said large diameter D3 has been chosen very slightly greater than the internal diameter D2 of the conduit in which the prosthesis is implanted, so, on the one hand, that it does not not reduce the free passage in the canal and on the other hand, not to cause significant mechanical effort which would lead to significant local deformation of this canal (the mechanical reaction exerted by the tissues in which this prosthesis is implanted generally ending by s cancel) ;; therefore, one of the characteristics of the invention is to introduce said prosthesis into the conduit, placing it against the wall of the tissues, therefore substantially at a diameter D2 corresponding to the diameter of said conduit, in a slightly prestressed state, which prosthesis will tend, after implantation, to open until reaching said diameter D3, very little greater than said diameter D2, in which the mechanical stresses internal to the prosthesis will be canceled and consequently the progression or the deformation of this- this will be stopped.

 It should also be noted that thanks to an essential characteristic of the invention, said radially expandable tubular prosthesis is such that in its unfolded or unrolled state where it takes a substantially cylindrical tubular shape of circular section having for diameter said diameter D3, state in which said wall of said prosthesis, in particular said elastic reinforcements are in a state of substantially zero mechanical stress, and in which the longitudinal edges of said prosthesis are not placed edge to edge, but overlap (overlap) so as to constitute a cylindrical channel; a fortiori, when said prosthesis is implanted in a tubular channel of the human or animal body, when it expands radially and takes as initial diameter (after its introduction into said channel) a diameter substantially equal to the diameter D2 of said channel, said edges longitudinal of said prosthesis also overlap, and still overlap when said prosthesis has reached its state of zero stress by residual radial expansion inside said channel where it was implanted, so that any penetration or proliferation is thus avoided living tissue inside the cylindrical duct of said prosthesis.

 The numerous advantages provided by the invention will be better understood through the following description which refers to the appended drawings which illustrate without any limiting character particular embodiments of prostheses according to the invention.

 Figure 1 illustrates in plan view a prosthesis in a manufacturing stage prior to winding (to deformation) thereof.

 Figure 2 is a section along II. Figure 1.

 FIG. 3 schematically illustrates a prosthesis according to the invention in its folded (pre-stressed) state in which it can be stored and introduced into a human or animal body, for example via the operating channel of a fibroscope.

 FIG. 4 schematically illustrates a prosthesis according to the invention in its free state, of zero mechanical stress.

 FIG. 5 schematically illustrates a prosthesis according to the invention implanted in a tubular channel.

 FIG. 6 schematically illustrates a device for introducing a prosthesis according to the invention.

 With reference to FIG. 1, it can be seen that, according to the invention, said prosthesis shown in this figure in an intermediate stage of manufacture before it is wound along an axis XX1 which will constitute the substantially symmetrical longitudinal axis of said tubular prosthesis, said prosthesis represented in plan view and generally extending along a plane, comprises said sheets 3 cut in a substantially rectangular shape limited by 2 longitudinal edges 31 and 2 transverse edges 3t. It can be seen in this figure that each of said sheets 3 which is preferably made made of translucent medical grade silicone elastomer, for example of hardness of the order of 50 to 70 Shore A, is reinforced with a dacron fiber fabric and is cut to said rectangular shape so as to see a sheet width 8 (which will correspond to the length of the tubular prosthesis marked 8 in Figure 3 after winding it the latter), and a length (transverse) 7 which is substantially greater than the circumference corresponding to said diameter D3 of the prosthesis wound in the free state (in the state of zero stress) so as to allow said overlapping of the longitudinal edges of the wound prosthesis (marked 31 in FIG. 4) corresponding to the marked edges 31 of said rectangular sheet.

 This overlap zone can for example be constituted by the longitudinal end of a first of said sheets whose length is greater than the length of the second sheet of said prosthesis, itself greater than said length 6 of said frames.

 By way of example, said width 8 of said sheet 3 corresponding to the length of the wound prosthesis may be of the order of 20 to 70 mm and the length 7 may be slightly greater than the circumference corresponding to diameters D3 ranging from 8 to 18 mm for example for bronchial prosthesis applications, said length 7 being greater than said circumference by 2 to 6 mm for example.

 It can also be seen in this figure that said prosthesis comprises reinforcements 2 regularly spaced apart by a pitch 4, parallel to each other, of small width 5 for example close to one mm, and whose length 6 is less than the length 7 of said sheet 3 so as to leave at each longitudinal end of said sheet 3 a zone of width 9 devoid of said frames; said frames preferably extend perpendicular to the axis XX1 which will constitute the axis of the cylindrical shape of the wound prosthesis and are arranged at a distance 10 from the transverse edges 3t for example of the order of at least 1 mm, said distance 4 separating 2 of said adjacent reinforcements 2 which can be of the order of approximately 5 mm to 10 mm depending on the applications; thanks to this structure, once said prosthesis is wound (as shown in FIGS. 3 and 4 in particular), it is possible to obtain a substantially cylindrical prosthesis which is radially expandable and which is capable of being bent, that is to say that said tubular prosthesis can be deformed along its longitudinal axis so as to be installed in curved cylindrical conduits such as bent or curved channels.

 With reference to FIG. 2, it can be seen that said cylindrical prosthesis advantageously comprises said two sheets 31 and 32 of silicone impregnating fibers 11 which can be woven, for example, said reinforcements 2 being provided between said sheets 31 and 32 which can be assembled together and with said reinforcements by an adhesive, preferably a translucent silicone adhesive, for example sterile.

 Advantageously, each of said sheets 31 and 32 has a small thickness 14, for example close to 2/10 \ mm and each of the frames also has a relatively small thickness of the same order of magnitude so as to produce a prosthesis whose wall constituted by l 'assembly of said sheets and said reinforcements has a thickness of about 0.5 mm.

 In the preferred embodiment illustrated in FIG. 2, it can be seen that said internal sheet 31 arranged in the lower part of the figure which is intended to constitute the internal face 12 of said prosthesis once it has been wound up, is provided with said fibers. 11 which are located in the upper part of said sheet 31 so as not to be flush with the underside of said sheet 31 and thus ensure a surface or a soft, (smooth) face devoid of roughness; said second sheet 32 (external) on the other hand has, in this exemplary embodiment, said fibers 11 disposed flush with the external face 13 which will constitute the external face of the prosthesis once wound and which may be rough; it can also be seen that said armatures 2 can advantageously be of substantially rectangular section, and the angles of which can be possibly broken or rounded, which armatures are preferably made of stainless steel for medical use, for example a cobalt steel alloy ( possibly containing molybdenum, nickel, chromium and manganese in particular) allowing it to provide high mechanical strength (for example of the order of 170 to 200 kg per mm2).

 We see as illustrated in Figures 3 and 4 that said prosthesis once wound, can constitute a tubular conduit of length 8 and can pass from a wound state where it is registered in a cylinder of diameter D1 advantageously less than 10 mm, to a unrolled state where it is substantially inscribed in a cylinder of diameter D3 which can for example vary from 12 to 16 mm in the case of bronchial prosthesis and this thanks to the elasticity of said frames which have been preloaded beforehand, which prosthesis passes from the state shown in Figure 3 to that shown in Figure 4, by deformation of said frames until they return to a substantially zero stress state, in which state the longitudinal edges 31 of said prosthesis overlap for example by 2 mm at less.

 With reference to FIG. 5, it can be seen that after implantation of a prosthesis according to the invention in a substantially cylindrical anatomical tubular conduit 16 of "natural" internal diameter D2, said prosthesis which has been introduced for example via of the working channel of a fibroscope, in the folded state, that is to say in a state where it occupies a diameter Di, was then released at the end of the channel of the fibroscope, in said anatomical tubular conduit 16, where it has expanded radially to come to press against the internal walls of said anatomical duct 16 at a diameter D2; after this positioning of the prosthesis in the anatomical conduit, due to the residual stresses existing in said elastic frameworks, said prosthesis continues to expand radially until it reaches said diameter D3 in which said frameworks find zero stresses.

 With reference to FIG. 6, in a preferred mode of use of a prosthesis according to the invention, said prosthesis 1 is previously wound up so as to occupy a substantially cylindrical volume having for diameter said diameter D1, this inside d 'A groove 19 provided in a cannula or candle 17 forming part of a device for introducing said prosthesis.

 Said groove 19 is preferably arranged in the cylindrical part of said cannula 17, near the tapered end 18 thereof, which may have a substantially frustoconical shape said groove 19 has a depth 20 close to the thickness (mark 15 of FIG. 2) of said prosthesis and has a length 21 preferably close to the length (reference 8 of FIG. 3) of said prosthesis 1.

 Said candle or cannula 17 is preferably hollow, crossed by a central channel 22 opening out, which allows the sliding inside said channel of a wire guide 24.

 The introduction device also preferably comprises a flexible jacket 23, of small thickness, the internal diameter D5 of which is very close to the external diameter D4 of the cylindrical part of said cannula 17, so as to maintain said prosthesis during its introduction into the human or animal body via said cannula, inside said groove provided in said cannula.

 The introduction process is as follows: first of all said filiform guide 24 is introduced into the sanatomical conduit 16 which is shown in FIG. 6 substantially cylindrical with an axis ZZ1; then introducing said cannula 17 carrying said prosthesis 1 in the wound state and coated externally with said jacket 23 holding said prosthesis, by sliding said cannula around said guide 24 through said channel 22 provided in said cannula; the sliding of said cannula relative to said guide 24 which takes place in the direction of the arrow Fi is stopped when a predetermined depth which could, for example, have been located on said cannula, has been reached, corresponding to the zone said anatomical canal 16 in which said prosthesis 1 is to be disposed; it is then possible, by pulling along arrow F2, keeping said cannula 17 substantially immobile, to remove said jacket 23, which causes the release of said prosthesis which unwinds and is pressed against the walls of said anatomical canal 16; said cannula and said metal guide can then be removed from the human or animal body.

Claims (10)

 1. Radially expandable tubular prosthesis (1), which comprises several elastic filiform elements (2), substantially parallel to each other, substantially identical, arranged between at least two thin sheets (3), each of said sheets comprising fibers (11) impregnated with silicone.  2. Prosthesis according to claim 1 characterized in that said elements or frames are regularly spaced apart by a pitch (4), and are preferably metallic and thin.  3. Prosthesis according to any one of claims 1 and 2 characterized in that each of said sheets has a thickness (14) close to 1.10-4 meters to 1.10-3 meters and is cut into a substantially rectangular shape, and in that the total thickness (15) of said prosthesis is less than 2.10-3 meters.  4. Prosthesis according to any one of claims 1 to 3 characterized in that the ratio of said diameter D3 in the expanded state to said diameter D1 in the folded state is at least equal to 1.2 and less than 2, and in that said diameter D3 in the expanded state is slightly greater than the internal diameter D2 of the channel into which said prosthesis is intended to be introduced.  5. Prosthesis according to any one of claims 1 to 4 characterized in that said fibers and / or said tissue consist mainly of dacron,  6. Prosthesis according to any one of claims 1 to 5 characterized in that said sheets are assembled by a silicone adhesive.  7. Prosthesis according to any one of claims 1 to 6 characterized in that said frames are arranged substantially perpendicular to the axis (XX1) of said substantially cylindrical prosthesis, and in that said inter-axis (4) of said frames is between 3.10-3 meters and 1.10-2 meters.  8. Prosthesis according to any one of claims 1 to 7 characterized in that said frames have a rectangular section and are mainly made of stainless steel.  9. Prosthesis according to any one of claims 1 to 8 characterized in that said fibers are arranged on the internal part of a sheet (31), so that the internal face (12) of said prosthesis is smooth.  10. Device for introducing a prosthesis according to any one of claims 1 to 9, characterized in that it comprises  a substantially cylindrical, flexible cannula (17) tapered to a  end (18) and comprising at least one groove (19) substantially  circumferential whose depth (20) is close to the thickness  total (15) of said prosthesis and the length (21) of which is short  greater than the length (8) of said prosthesis.