MXPA97001043A - Implant of alexander tita autoextensible stenosis - Google Patents

Abstract

A self-extending stenosis implant (10) formed by filaments (12) helically wound and braided of titanium or titanium alloys such Ti-13Zr-13

Description

IMPLANT OF SELF-TENSIBLE STIENOSIS OF TITANIUM ALLOY BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to rnplan + ables and radially extensible medical prostheses which are often referred to as stenotic implants ("TENTS"). In particular, the present invention is a titanium alloy stenotic or extensional implant.

Description of the Prior Art Self-expanding medical prostheses often called stenosis implants are well known and commercially available. These are described for example in U.S. Patent 5,061,275 to Wallsten, U.S. Patent 5,061,275 to Uallsten et al., And International Patent Application number U094 / 24961, all of which are hereby incorporated by reference in their whole. Devices of these types are used inside body vessels of humans and other animals for a variety of medical applications. Examples include stenosis implants to treat stenosis, stenosis implants to maintain openings in the urinary, biliary, esophageal and renal tracts and vein filters to control embolism.

Briefly, self-expanding stenotic implants of the type described in the aforementioned patents are formed by a series of elastic filaments that are wound helically and woven together in a braided configuration. Stenosis implants adopt a substantially tubular shape in its free or extended state when they are not subjected to external forces. When subjected to radial forces directed inward, stenosis implants are forced into a charged or compressed state with a reduced radius and a greater-length. To insert the stenosis implant into a treatment site through the bodily vessels an insertion device is used which maintains the stenosis implant in its compressed state. The flexible nature and reduced radius of the compressed stenosis implant allows it to be introduced through relatively small and curved vessels. After the stenosis implant has been placed in the treatment site, the insertion device is actuated to deploy the stenosis implant, allowing the stenosis implant to self-extend into the interior of the body vessel. The insertion device then detaches from the stenosis implant and is removed from the patient. The stenosis implant remains in the vessel at the treatment site. Stenosis implants must have a relatively high degree of biocoatability since they are implanted in the body. The materials commonly used for the filaments of stenosis implants include elastic alloys of Elg? LoyR and PhynoxR. The Elg? LoyR alloy is available from Carpenter Technology Corporation of Reading, Pennsylvania. Phynox alloy "is available from Metal Imphy of I phy, France, both materials are cobalt-based alloys that also include chromium, iron, nickel and olibdene." Other materials used for filaments of self-expanding stenotic implants are 316 stainless steel and alloy. n MP35N that are available from Carpenter Technology Corporation and Latrobe Steel Company of Latrobe, Pensilvama and the nickel-titanium Nitmol euperelastic alloy that is available from Shape Memory Applications of Santa Clara, Calif. The Nitinol alloy contains approximately 45% titanium. Yet another self-extending stenosis implant available from Schneider (USA) Inc. of Nineapolis, Minnesota includes an alloy housing with a core of tantalum or platinum alloy. The tantalum or platinum alloy core is radiopaque and visualizes the stenosis implant by fluoroscopy during implantation. The resistance and the modulus of elasticity of the filaments that form the stenosis implants are also important characteristics. Elgiloy *, Phynox *, I1P35N and stainless steel are all high strength metals and high modulus of elasticity. Nitmol has a relatively low resistance and modulus.

The continuous need for self-expanding stenosis implants with particular characteristics for use in various medical indications remains. Stenosis implants are necessary for the implant in an ever-growing list of vessels in the body. There are physiological environments and it is recognized that there is no universally accepted set of characteristics for a stenosis implant. In particular, there is a need for stenotic implants formed of materials of moderate strength that have lower moduli of elasticity than those of ElgiloyR, PhynoxR, MP35N and stainless steel, materials from which certain stenosis implants are conventionally formed. Stenosis implants formed by materials of moderate strength and relatively low modulus of elasticity will have properties adapted to a wide range of treatment applications. Stenosis implants with smaller moduli of elasticity will be less rigid and more flexible than a stenosis implant made in the same size of thread and is designed using a material with a high modulus of elasticity. Stenosis implants of these types should also show a high degree of biocompatibility. In addition, the filaments of which the stenosis implant is manufactured are preferably radiopaque to facilitate their implantation in patients. Conventional autoextensive stenosis implants performed in ElgiloyR, MP35N, stainless steel and nitinol can be made to have various characteristics by modifying the size of the filament threads and the designs of the stenosis implant. However, a group of materials for threads for implant stenosis with properties between materials with a high resistance and high modulus of elasticity (ElgiloyR, NP35N, stainless steel) and the materials of resistance and low modulus of elasticity (nitinol ) would even allow the production of more variants of stenosis implants. Implantation of an uranal urnal stenosis implant will preferably cause a generally reduced degree of acute and chronic trauma to the lnalnal wall while performing its function. A stenosis implant that applies a slight radial force to the wall and that is elastic and flexible with movements of the lumen for use in diseased, weakened or brittle lumens is preferred. The stenosis implant will preferably be able to withstand the external occlusive pressure of tumors, plaque, and lumbar remodeling and remodeling.

BRIEF DESCRIPTION OF THE INVENTION The present invention is an improved implantable medical device composed of a tubular, radially compressible, axially flexible and radial self-extending structure that includes at least one elongated filament formed by a braided configuration. The filament consists of titanium or a sufficiently strong titanium alloy with a relatively low modulus and includes at least 68 weight percent titanium. The device is radiopaque and has a relatively high degree of biococity. In a preferred embodiment, the device is a stenosis implant consisting substantially of a plurality of elongated filaments of titanium or titanium alloy wound helically and woven together in a braided configuration to form a tube. A preferred alloy is Ti-13Zr-13Nh.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an isometric view of a stenosis implant according to the present invention, illustrating the braided configuration of the filaments. Figure 2 is a partial longitudinal cross-sectional view of the stenosis implant shown in Figure 1. Figure 3 is a cross-sectional view of one of the filaments of the stenosis implant shown in Figure 1. Figure 4 is a side view of an insertion device with the implant of stenosis shown in Figure 1 inside. Figure 5 is a detailed view of the part of the insertion device surrounded at 5 in Figure 4. Figure 6 is a detailed view of the part of the insertion device surrounded at 6 in Figure 4. Figure 7 a 10 are side views of partial cross sections of the distal portion of the insertion device and the stenosis implant shown in Figure 4 in various states during a deployment operation of the stenosis implant in a body vessel. Figure 11 is a graph of the results of the fatigue test for the twisting of the U-bend on ten samples of T? -13Nh-13Zr wire of 0, 18 inrn as it stretched. Figure 12 is a graph of the results of the torsion fatigue test of the U-bend yarn on six samples of thermally treated T-13Nb-13Zr yarn of 0.18 mm. Figure 13 is a table of tangential strength test results for three braided structures and three thermally treated prototype stenotic implants, all formed by T? -13Nb-13Zr thread of 0.18 mrn and formed on a 12-mandrel mandrel. rnm with a braid angle of 110. The results of the trial for stents of similar size of Elgiloyf and ElgiloyR / DFT are also in the table for the purpose of comparison Figure 14 is a side view of a second embodiment of a stenosis implant according to the present invention Figure 15 is an end view of the stenosis implant shown in Figure 14.

Figure 16 is a graph of radial pressures as a function of diameter for a series of stenosis implants according to the present invention. Figure 17 is a graph of radial pressures calculated as a function of internal diameters in the related state for stenosis implants according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In Fig. 1 and 2, an implantable prosthesis or stenosis implant 10 according to the present invention is generically illustrated. The stenosis implant 10 is a tubular device formed of two groups of elongated filaments or filaments 12 wound helically, spaced apart, parallel and of opposite directions. The group of filaments 12 is interwoven in a twisted xencimal configuration and below "intersecting at points such as 14 formed an open mesh or woven construction. As described in more detail below, at least one and, preferably all of the filaments 12, are composed of pure titanium or titanium alloys of commercially available quality including at least about sixty-eight percent by weight of titanium. Methods for manufacturing stents 10 are generally known and described, for example, in U.S. Patent 4,655,771 to Uallsten and U.S. Patent 5,061,275 to Uallsten et al. they add in the present as reference in their entirety. The stenosis implant 10 is shown in its extended or relaxed state in Figures 1 and 2, that is, in the configuration it adopts when it is not subjected to car-gas or external stresses. The filaments 12 are elastic, allowing radial compression of the stenosis implant 10 to a configuration or condition with reduced radius and greater-length suitable for insertion in the desired location of the treatment site through the body vessel (i.e., transluminally). ). The stenosis implant 10 is also self-extending from the compressed and flexible state in the axial direction. As an example, one embodiment of the stenosis implant 10 has a diameter of about 10 m in the relaxed state and can be elastically compressed to a diameter of about 2 nm. The stenosis implant described in this example has an axial length in its compressed state that is approximately twice its axial length in the relaxed state. Stated otherwise, the stenosis implant 10 is an axial, radially flexible tubular body having a predetermined diameter that can vary under axial movement of the ends of the body with respect to each other. The stenosis implant 10 is composed of a plurality of braided or indistinctly flexible but elastic elements or filaments, each of which extends in helical configuration along a longitudinal central line of the body as the common axis. At least one and preferably all of the filaments 12 consist of commercially available grades of pure titanium or titanium alloys including at least sixty-eight percent by weight of titanium. The filaments 12 define a self-extending body in the radial direction. The body is provided by a first series of filaments 12 which have a common winding direction but which are axially offset from each other, and which intersect with a second series of filaments 12 also offset from each other, but having an opposite winding direction. The tubular and self-extending body or structure formed by the interwoven filaments is a structure of the primary stenosis implant 10 of the prosthesis at functional level and for this reason it can be considered that the device consists essentially of this structure, excluding other structures. However, it is known that other structures and characteristics can be included in the stenosis implants and in particular characteristics that improve or cooperate with the tubular and self-extending structure or that facilitate the implanting of the structure. One example is the inclusion of radiopaque markers on the structure that are used to visualize the position of the stenosis implant using fluoroscopy during implantation. Another example is the inclusion of an additional interwoven sheath or filaments, for example, to reduce porosity or open spaces in the structure so that the stenosis implant can be used to prevent tissue penetration or can be used as a graft. Other examples include collapsible fibers or other structures that facilitate the relocation and removal of the stenosis implant. However, stenosis implants of these types are still substantially composed of the tubular and self-extending structure formed by interwoven filaments 12 and are shown in Figures 1 and 2. Furthermore, many of the desirable features and properties of the stenosis implant 10 will be present if any, but not all, of the filaments 12, are composed of titanium or titanium alloy. Figure 3 is a cross-sectional view of one of the filaments 12 of titanium or titanium alloy. As shown, the filaments 12 are substantially homogeneous in cross section. Commercially available alloys may have small fluctuations in the proper concentration remaining still substantially homogeneous. The filaments 12 also have a homogeneous length. The filaments 12 may be formed of titanium and a wide range of titanium alloys containing at least sixty-eight percent by weight of titanium, preferably from about 68 to about <.36 percent by weight, and more preferably from about 73 to about 86 percent by weight. The titanium and the titanium compositions described for the remainder of this description in percentages are given as a percentage by weight. Example 1 A prototype stenosis implant 10 was fabricated with filaments 12 of approximately 0.18 mm in diameter from a titanium alloy containing approximately 74% titanium, 13% niobium and 13% zirconium (Ti-13Nb-13Zr). The yarn with which the filaments are manufactured was stretched by G &S Titanium of Uooeter, Ohio from a Ti-13Nb-13Zr alloy bar supplied by Smith 8c Nephew Richards Inc. of Memphis, Tenessi. The yarn was acid cleaned, cold reduced by about 52% and its diameter varied from about 0.164 mm to about 0.184 m. The Ti-13Nb-.13Zr yarn portions were thermally treated by S ith to Nephew Richards Inc. using a melt hardening treatment. The samples of the yarn as it was stretched and heat treated were tested to determine the tensile strength, torsion fatigue of U-bend yarn, flexural modulus and torsion / shear modulus (rigidity), having a tensile breaking load. average of approximately 1034 riPa, remaining deformation load of 0.2% average of approximately 972 UPa, average elongation of 3.1% and average elastic modulus of approximately 48.255 MPa. The thermally treated yarn samples were measured, having an average tensile breaking load of about 1048 MPa, average 0.2% remaining deformation load of about 1007 MPa, average elongation of 2.4% and average elastic modulus of about 73,087 MPa. In order to compare, it was found that samples of superelastic Nitinol yarn having a diameter of 0.13 nm had an average tensile breaking load of about 1420 MPa. residual strain of 0.2% average of approximately 517 MPa, average elongation of 14.4% and average elastic modulus of approximately 37.233 MPa. The internally stabilized Elgloy h and having a diameter of 0.17 mm had an average tensile breakage load of approximately 2841, a remaining average deformation load of 0.2% of 2627 MPa, average elongation of 1.9% and average elastic modulus of approximately 191,681 MPa. Fatigue tests on both samples, yarn as it was stretched and heat treated provided a series of samples that obtained ten million cyclical runs at lower tension levels of approximately 414 MPa without breaking. A series of samples as they were stretched subjected to voltage levels of approximately 483 MPa to 552 MPa broke between approximately five and ten thousand cycles. Figure 11 shows a graph of the results of the torsion fatigue test bent in U over the wire - which was stretched. Figure 12 shows a graph of the results of the torsion fatigue test bent in U over the heat treated yarn. For the purpose of comparison, the 0.13 mm diameter superelastic Ni t mol yarn had a slightly lower fatigue strength and the Elg? Loy yarn of 0.17 nm had a resistance to fatigue approximately 50% higher than Thread of Ti-13Nb-l3Zr. The bending modulus of the T? -13Nb-13Zr wire was measured and was approximately 38,854 MPa for the samples as they were stretched and approximately 61,366 MPa for the thermally treated samples. In comparison, the flexural modulus was approximately 43,439 MPa for the superelastic Ni mol yarn of 0.13 m and approximately 123,421 MPa for the Elgiloy R yarn of 0.17 nm. The torsion / stiffness modulus of the Ti-13Nb-13Zr wire was measured and was approximately 24,133 MPa for the samples as they were stretched and approximately 33,096 for the thermally treated samples. In comparison, the torsion / stiffness modulus for the superelastic Nitinol yarn of 0.13 mrn is about 24,133 MPa and about 93,083 MPa for the Elg? Loy yarn of 0.17 m. The prototype tubular structures formed of T? -13Nb-13Zr yarn were produced with twenty twisted filaments around a mandrel of 10 nm (12 nm diameter) with a braid angle of 110. A number of structures were thermally treated by Smith 8 Nephew Richards Inc. using a diffusion hardening treatment to produce the prototype stenosis implants.The heat treatment procedure increased the stability of the devices helping to prevent the braiding from collapsing., the use or not of the thermal treatment procedure will depend on the characteristics desired for the implant of stenosis. The braided structures and stenosis implants were tested to determine the tangential force. The heat treated stenotic implants presented the characteristics of a tubular stenosis implant similar to a braided one. The stenosis implant could be compressed radially and extended axially. When the applied radial pressure was eliminated, the stenosis implant returned to its original undeformed state by an elastic recovery. A stenosis implant was successfully placed in a 9 French caliber loading device. The average tangential force required to tighten the structures from their relaxed state to an outer diameter of approximately 5.16 nm was about 14.38 g and ranged from about 11.66 g to about 15.96 g. The average tangential force required to constrict thermally treated prototype stenotic implants from their relaxed state to an outer diameter of about 5.16 nm was about 38.28 g and ranged from about 36.47 g to about 39.96 g. For the purpose of comparison, an Elgiloy stretched filled tube stenosis implant (iloy / DTF) of equal dimensions formed by yarn of approximately 0.29 nm having a tantalum core and an Elgiloy cover requires a force of Approximately 74.84 g to narrow to the ism diameter An Elg? loy stenosis implant of the same dimensions formed by approximately 0.12 mm diameter wire requires a force of approximately 69.85 g to narrow to the same Figure 13 is a table of tangential strength test results for three braided structures and three prototype heat treated stenotic implants, as well as stents Elgiloy and ElgiloyfVDFT stents, The tests described above indicate that implants of stenoses 10 manufactured in T? -13Nb-13Zr yarn have desirable characteristics for certain applications. relatively low elasticity and relatively moderate resistance. The thread of the T? -13-13 stenosis implant had a remaining strain load of 0.2% and U-curved fatigue properties between that of Elgiloy "and nitinol (two commonly used stenotic implant materials). of stenosis had measurable resistance to compression and can be expected to exert a shorter force (less radial force) than the Elgiloy stenosis implant "on the lurnal wall. The stenotic implants 10 are therefore resistant and flexible and are able to move through curved vessels or lumens during insertion. The titanium alloy is highly biocompatible and is resistant to thrombosis and bacterial infection. Although Ti-l3Nb-13Zr is the most preferred titanium alloy containing niobium and zirconium, other compositions may also be used. In particular, advantages similar to the most preferred composition will offer titanium alloys comprising at least about 68% titanium, 1-29% Nb and 1-29% Zr, including alloys such as 10-15% Nb. and 10-15% of Zr. Example 2 to 6 Radial pressures were calculated for each of five 10 T? -6A1-4V stenosis implants of different diameters (example 2 to 6, respectively). Radial pressures are those of stenosis implants 10 to eighty five percent of their diameter (ie diameter of the center of travel). The radial characteristics and pressures of the stenosis implants of Examples 2 to 6 are shown below in Table 1. The diameter / pressure values of the individual stenosis implant are shown graphically in Figure 16 and were generated by computer-using mathematical formulas described in the Jedwab and Clerc paper * 'A Study of the Geometrical and Mechanical Properties of a Self-Expandmg Metallic Stent-Theory and Experirnent' ', ournal of Applied Biomaterials, Vol. 4 pages 77-85 (1993), which is hereby incorporated by reference in its entirety.

Table 1 Diameter Implant in Number of Pressure Diameter Stenosis State of or of the braid Radial Example Relaxed yarns thread (degrees) (mm Hg) (rnm) í mm) 2 5 20 0,09 110 36,7 3 8 24 0.11 110 15.5 4 10 24 0.14 105 13.4 16 30 0.17 110 7.1 6 20 36 0.17 120 5.3 From the information in Figure 16, the mean radial pressure can be characterized as a function of the diameter (D) of the stenosis implants with the diameters of relaxed state from 5 to 16 rnm by the following Equation 1: Pressure C m Hg] = -2D Cmm] + 40 Eq. 1 The range of available radial pressures for stenosis implants of 5 to 16 mm is characterized by the following Equation 2: Pressure Tmm Hg] = -2D fmm] + 40 + _ 20 Ec. 2 A preferred range of radial pressures for stenosis implants of diameters from 5 to 16 nm is characterized by the following Equation 3: Pressure [mm Hg] = -2D Tnim] + 40 + _ 15 Eq. 3 Example 7 Stenosis implants 10 can be fabricated from a titanium alloy composed of at least about 68% titanium and 1-29% each of aluminum (AI), tin (Sn), zirconium (Zr) and molybdenum (Mo). A preferred titanium alloy having these constituents is Ti-6Al-2Sn-4Zr-6Mo. Threads composed of Ti-6AI-2Sn-4Zr-6Mo alloy are available from one source of supply including RMI Titanium of Ni, Ohio. Example 8 Stenosis implants 10 can be fabricated from a titanium alloy composed of at least about 68% titanium and 1-28% each of aluminum (AL), vanadium (V), chromium (Cr), molybdenum (Mo) and zirconium (Zr). A preferred titanium alloy having these constituents is T? -3Al-8V-6Cr-4Mo-4Zr. Threads composed of Ti-3A1-8V-6Cr-4Mo ~ 4Zr alloy are commercially available from a number of suppliers that include RMI Titamum of Niles, Ohio. Example 9 Stenosis implants 10 can be fabricated from a titanium alloy composed of at least about 68% titanium and 1-31% each of aluminum (Al) and vanadium. Preferred alloys having these constituents are Ti-6A1-4V and Ti-6A1-4V ELI. The chemical, mechanical and metallurgical requirements for the Ti-6A1-4V alloy for surgical implants are published in the specification of the ASTM F 1472 standard. The chemical, mechanical and metallurgical requirements for the T1-6A1-4V ELI alloy for surgical implants are published in the specification of the ASTM F 620 standard. Threads composed of Ti-6A1-4V and Ti-6A1-4V ELI alloys are commercially available from a number of suppliers including RMI Titanium of Niles, Ohio. Example 10 Stenosis implants 10 of non-alloy titanium wire can be fabricated. The chemical, mechanical and metallurgical requirements for the unalloyed titanium wire used in surgical implants are published in the specification of ASTM F 1341. The unalloyed titanium wire of these types is commercially available from a number of suppliers including RMI Titanium of Niles, Ohio. Example 11 Stenosis implants 10 can be manufactured from a wide variety of titanium alloys containing at least about 68% titanium and which are substantially free of nickel, cobalt and chromium. In the above examples, a series of alloys having these characteristics are described. Commercially available alloys of these types typically have less than about 0.1% nickel, cobalt and chromium and / or other elements.

Examples 12 Figure 17 is a graph of radial pressures calculated as a function of internal diameters in the relaxed state for stenotic implants formed of Ti-6A1-4V alloy ('^ Ti alloy'), Elgiloy * alloy and Nitinol alloy. The radial pressures were calculated for implants that have internal diameter of five, eight, ten, sixteen and twenty millimeters at 85% of their diameter in a relaxed state. The calculations were performed using the formulas described in the Jedwab and Clerc article described above. From Figure 17 it is evident that the radial pressures of stenosis implants of the Ti alloy are about 0.4-0.5 times the radial pressures of Elgloy alloy stenosis implants designed and dimensioned similarly. The radial pressures of sling alloy Ti implants are approximately 1.8-1.9 times the radial pressures of Nitinol stenosis implants designed and similarly directed. The specifications of the stenosis implants described in Figure 17 are shown below in Table 2: Table 2 Diameter N ° of angle Braided Diameter of the (mm) threads (degrees) thread (rnrn) 20 110 0.09 8 24 110 0.11 10 24 105 0.14 16 30 110 0.17 20 36 120 0.17 Figures 4 to 6 are illustrations of an insertion device 20 for inserting the stenosis implant 10 into a treatment site in a body vessel. As shown, the stenosis implant 10 is transported through the distal portion of the insertion device 20 and is placed in the insertion device in a compressed and radially retracted state. The proximal part of the insertion device 20 generally remains outside the body for manipulation by the operator. The insertion device 20 includes an elongated inner tube 30, which preferably has a lumen extending axially therethrough. The distal portion of the inner tube 30 is flexible and can be made of Nylon or other suitable biocompatible flexible polymeric material. At its distal end, the inner tube 30 is provided with a head 31, through which the lumen is prolonged. The head 31 serves to facilitate the insertion of the insertion device 20 into the trirds of a narrow opening in a body vessel. The next part! of the inner tube 30 is preferably formed of stainless steel or other suitable rigid metal alloy.

The proximal end of the distal part of the inner tube 30 is attached to the distal end of the proximal part of the inner tube in a conventional manner, such as using a conventional adhesive. A proximal tube 50 surrounds the proximal part of the inner tube 30 coaxially. The proximal tube 50 is preferably formed of polyurethane. The proxirnal end of the tube 50 is connected to a valve body 40 having a side hole 41. An extension tube 45 extends from the side hole 41 to an opening 42. This arrangement permits the injection of liquid through the extension tube 45 and between the proximal tube 50 and the inner tube 30. A movable flexible tube 55 it surrounds the distal part of the inner tube 30. The flexible tube 55 is turned on itself forming a double-walled section. The proximal end of the inner wall 56 of the double walled section is directly connected to the inner tube 30. The proximal end of the outer wall 57 of the double walled section is connected to the outer surface of the proximal part of the proximal tube. 50. These connections can be achieved by any conventional means such as by a standard adhesive. This arrangement allows the flexible tube 55 to move out of the stenosis implant 10 and to be located on the distal part of the inner tube 30. By moving the valve body 40 in the proximal direction, the outer wall 57 of the flexible tube 55 slides proximally on the inner wall 56. This causes the inner wall 55 to move backward from the stenosis implant 10. To facilitate the movement of the flexible tube 55 outside the stenosis implant 10, at least this part of the inner wall 56 that comes into contact with the outer wall 57 in the area in which the flexible tube 55 is turned forming the double-walled section should be lubricated. The lubricating characteristic can be achieved by adding a lubricant substance to this surface of the flexible tube 55, by injecting a lubricating liquid between the inner wall 56 and the outer wall 57 or by forming the flexible tube 55 with a material sliding by nature such as a coating of Teflon In a preferred embodiment, at least the surface of the inner wall 56 and that of the outer wall 57 facing each other in the double-walled section are covered by a lubricating hydrophilic coating. In one embodiment, the hydrophilic coating is 2018-M, material available from Hydro Inc. of Uhite ouse, New Jersey. Other materials that can be used are poly (ethylene oxide) and hyaluronic acid. When wet, the hydrophilic coating becomes lubricant and thus reduces the friction between the inner wall 56 and the outer wall 57 of the double-walled section of the flexible tube 55 when the outer wall 57 moves past the inner wall 56. This facilitates removal of the double wall section of the flexible tube 55 from the stenosis implant. In a preferred embodiment, the hydrophilic material is added to the flexible tube 55 during the assembly of the insertion device 20. In order to allow adequate attachment of the hydrophilic material to the flexible tube 55, the material used to manufacture the flexible tube 55 must be adapted to the material hydrophilic used. The polyurethane has been found to work well as a material for the flexible tube 55. In particular, a polyurethane blend 65D and 75D provides sufficient flexibility to allow the flexible tube 55 to turn on itself, although still sufficiently soft and compatible. with the hydrophilic material so that it can adequately coat it. In one embodiment, the mixture is formed of 50% polyurethane 65D and 50% polyurethane 75D. During assembly of the insertion device 20, one face of the flexible tube 55 is coated with the hydrophilic material after the outer wall 57 of the flexible tube has been connected to the proximal tube 50. Isopropyl alcohol is first applied to one side of the tube flexible 55 to clean the surface and remove the wax film resulting from the plasticizers in the polyurethane. The same face of the flexible tube 55 is then coated with the hydrophilic material. The surface of the flexible tube 55 should be washed with alcohol for approximately thirty seconds. Similarly, the surface of the flexible tube 55 should be washed with the hydrophilic coating for about thirty seconds. It has been found that this technique deposits sufficient hydrophilic material on the inner wall 56 and on the outer wall 57 to allow the flexible tube 55 to retract with minimal friction when the hydrophilic material is wet. After the insertion device has been assembled and is ready to use, the hydrophilic material is moistened with physiological saline by injecting the solution through the extension tube 45, past the proximal tube 50 and into the space between the inner wall 56 and the outer wall 57 of the double-walled section of the flexible tube 55. Excess liquid comes out of the orifice 59 formed towards the distal end of the double-walled section of the flexible tube 55. In this same manner, a lubricating liquid such as polyethylene glycol in the space between the inner wall 56 and the outer wall 57 of the double-walled section to provide the lubricating characteristic of the flexible tube 55 instead of adding a hydrophilic lubricant material through the flexible tube 55 as It has been described above. The manner in which the insertion device is operated to insert the stenosis implant 10 into a treatment site in a vessel or body lumen that includes curved sections is illustrated in Figures 7 through 10. As shown, the stenosis implant 10 is placed in a radially compressed state in a surrounding relationship with the outer distal end of the inner tube 30. The stenosis implant is narrowed on the inner tube 30 by the double-walled section of the flexible tube 55. It is It is important that the stenosis implant 10 not be confined too tightly in the tube 30. The flexible tube 55 will apply sufficient force to the stenosis implant 10 to place the stenosis implant 10 in place. The double wall section of the flexible tube 55 can be removed from the vicinity of the stenosis implant 10 by dragging the valve body 40 and the proximal tube 50 in a proximal direction. The double-walled section is moved out of the stenosis implant 10. No sliding movements take place between the stenosis implant 10 and the inner wall 56 which is in contact with the stenosis implant 10. Together with the movement of the stenosis section 10. Double wall proximally, the distal end of the stenosis implant 10 will be exposed in a radial direction to an adjustment against the wall of the body vessel. When the double-walled section of the flexible tube 55 continues to move proximally, the stenosis implant 10 is exposed in a radial direction until the entire length of the stenosis implant 10 is exposed and fits the wall of the body vessel. The lumen 35 is used to allow the insertion device 20 to follow a guide wire (not shown) previously inserted percutaneously into the body vessel. The lumen of the inner tube 30 can also be used to introduce a contrast fluid into the area surrounding the distal end of the insertion device 20 in order to be able to detect the position of the insertion device 20 (eg by of fluoroscopy or X-ray techniques). The stenosis Lmplant.es of the present invention can be inserted by alternative methods or using alternative devices. For example, the device described in U.S. Patent No. . 201..757 of Heyn et al. In Figures 14 and 15 another embodiment of the present invention is shown, the stenosis implant 110. The stenosis implant 110 is similar to the stenosis implant 10 described above because it is a tubular device formed by two groups of elongated strands or filaments 112. of opposite directions, parallel, separated and coiled hello helically. The framing groups 112 are interwoven in a braid configuration above and below which intersect at such points as 14 formed an open mesh or woven construction. One end 116 of the stenosis implant 110 is conical and has a diameter that decreases from the diameter of the other portions of the stenosis implant to a reduced diameter. The stenosis implant 110 may have an identical structure and be fabricated from the same titanium or titanium alloy materials as the stenosis implant 10 described above. The stenosis implant 110 ee can be applied (in the form of the stenosis implant 10 described above) to a desired position within a vessel, for example, the inferior Vena Cava, in order to avoid a pulmonary embolism. When used in this application, the stenosis implant 110 can be inserted into the Ven Cava with a high degree of precision and function as a filter. Stenosis implants 10 and 110 offer considerable advantages. In particular, the alloys of titanium and the non-alloyed titanium of which they are constituted are highly bcompatible and have good resistance to thrombosis and adhesion of bacteria. Stenosis implants have a relatively low elastic modulus and moderately high resistance at given stress levels. These are therefore resistant and sufficiently flexible so that they can be inserted into treatment sites through bent body vessels. The titanium stenosis 10 and 110 implants exert a more moderate radial force against the luernal wall than conventional Elg? Loy stenosis implants do. The radial force can be made larger or smaller using threads of greater or lesser diameter in the construction of the stenosis implant. The stenosis implants are also radiopaque, thus allowing the visualization of the devices during the implant.

Although the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that there may be changes in shape and details without departing from the spirit and scope of the invention.

Claims (31)

NOVELTY OF THE INVENTION CLAIMS

1. An implantable medical device (10) composed of a tubular structure, radially compressible, axially flexible and radial self-extending body that includes at least one elongated filament (12), in which the filament (12) is composed of titanium or titanium alloy and it includes at least about 68 weight percent titanium.

2. The medical device (10) according to the claim 1, wherein the filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent of titanium and at least one element selected from the group consisting of aluminum, tin, zirconium, rnolibdene , chrome, niobium and vanadium.

3. The medical device (10) according to the claim 2, wherein the filament is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent titanium, 1-31 weight percent niobium and 1-31 weight percent zirconium.

4. The medical device (10) according to the claim 3, wherein the titanium alloy includes 10-15 weight percent niobium and 10-15 weight percent zirconium.

The medical device (10) according to claim 4, wherein the titanium alloy includes about 13 weight percent niobium and 13 weight percent zirconium. b.

The medical device (10) according to claim 2, wherein the filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent of titanium, 1-29 weight percent of aluminum, 0.5-29 weight percent tin, 1-29 weight percent zirconium and 1-29 weight percent molybdenum.

7. The medical device (10) according to claim 6, wherein the titanium alloy includes about 6 weight percent aluminum, approximately? percent by weight of tin, approximately 4 percent by weight of zirconium and approximately 4 percent by weight of molybdenum.

The medical device (10) according to claim 2, wherein the filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 percent by weight of titanium, 1-28 percent by weight. aluminum weight, 1-28 weight percent vanadium, 1-28 weight percent chromium, 1-28 weight percent olybdenum and 1-28 weight percent zirconium.

The medical device (10) according to claim 8, wherein the titanium alloy includes about 3 weight percent aluminum, about 8 weight percent vanadium, about 6 weight percent chromium, about 4 weight percent. weight percent molybdenum and approximately 4 weight percent zirconium.

The medical device (10) according to claim 2, wherein the filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 percent by weight of titanium, 1-31 percent in aluminum weight and 1-31 weight percent vanadium.

The medical device (10) according to claim 10, wherein the titanium alloy includes about 6 weight percent aluminum and about 4 weight percent vanadium.

The medical device (10) according to claim 1, wherein the filament is substantially free of nickel.

The medical device (10) according to claim 1, wherein the average radial pressure, P, exerted by the device, in mm Hg, as a function of diameter, D, in nm, varies in the range of approximately P = -2D _ + _ 20.

14. The medical device (110) according to claim 1, wherein the device has at least one end (116) of decreasing diameter in order to function as a filter.

The medical device (10) according to claim 1, wherein the structure includes multiple elongated filaments (12) interwoven to form a tube.

16. The medical device (10) of claim 15, wherein the structure includes a plurality of elongated filaments (12) of titanium or titanium alloy wound helically and woven in a braided configuration to form a tube.

17. The medical device (10) according to claim 16, wherein the structure consists substantially in a plurality of elongated filaments (12) of titanium or titanium alloy coiled helically coiled and interwoven in a braided configuration to form a tube.

The medical device (10) according to claim 17, wherein each filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent of titanium and at least one selected element Among the group consisting of aluminum, tin, zirconium, rnolibdene, chromium, niobium and vanadium.

The medical device (10) according to claim 18, wherein each filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent of titanium, 1-31 percent in weight of niobium and 1-31 weight percent of zirconium.

The medical device (10) according to claim 19, wherein the titanium alloy includes 10-15 weight percent niobium and 10-15 weight percent zirconium.

The medical device (10) according to claim 20, wherein the titanium alloy includes about 13 weight percent niobium and 13 weight percent zirconium.

The medical device (10) according to claim 18, wherein each filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent of titanium, 1-29 per weight percent aluminum, 0.5-29 weight percent tin, 1-29 weight percent zirconium and 1-29 weight percent olybdenum.

The medical device (10) according to claim 22, wherein the titanium alloy includes about 6 weight percent aluminum, about 2 weight percent tin, about 4 weight percent zirconium and about 4 weight percent. percent by weight of rnolibdene.

The medical device (10) according to claim 17, wherein each filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 percent by weight of titanium, 1-28 percent by weight. aluminum weight, 1-28 weight percent vanadium, 1-28 weight percent chromium, 1-28 weight percent olybdenum and 1-28 weight percent zirconium.

The medical device (10) according to claim 23, wherein the titanium alloy includes about 3 weight percent aluminum, about 8 weight percent vanadium, about 6 weight percent chromium, about 4 weight percent of aluminum, about 8 weight percent of vanadium, about 6 weight percent of chromium, about 4 weight percent of aluminum. weight percent molybdenum and about 4 weight percent zirconium.

26. The medical device (10) according to claim 17, wherein each filament (12) is composed of titanium alloy and the titanium alloy comprises at least 68 weight percent of titanium, 1-31 weight percent of aluminum and 1-31 weight percent vanadium.

The medical device (10) according to claim 25, wherein the titanium alloy includes about 6 weight percent aluminum and about 4 weight percent vanadium.

The medical device (10) according to claim 17, wherein the average radial pressure, P, exerted by the device, in m Hg, as a function of diameter, D, in rnm, varies in the range of approximately P = -2D + 40 + _ 20.

29. The medical device (110) according to claim 17, wherein the device has at least one end (116) of decreasing diameter so as to function as a filter.

30. An implantable medical device (10) composed of a tubular, axially flexible and radially self-extending structure that includes at least one elongated filament (12) of titanium or titanium alloy having a substantially homogeneous cross section and length and wherein the The titanium alloy includes at least 68 weight percent of the chaff.

31. A process for treating a site of a patient's vessel that includes: disposing a biocompatible medical device (10) comprised of a tubular and axially flexible braided structure that is radially self-expanding between a compressed state and an extended state and that includes at least one elongated filament (12), wherein the filament (12) is composed of titanium or titanium alloy and includes at least 68 weight percent titanium; arranging an insertion system (20) with the medical device (10) located on a part of the insertion system (20) in the compressed state; inserting the part of the insertion system (20) with the medical device (10) into a patient's vase in a position away from the treatment site and manipulating the. insertion system for advancing the medical device (10) through the vessel to the treatment site; detaching the insertion system (20) from the medical device (10) and allowing the medical device (10) to self-extend into the vessel; and removing the insertion system (20) from the patient, the medical device (10) remaining in an extended state and supporting the vessel.