MXPA97002199A - Fixed and fixed gravers that have improved ring resistance and methods to make myself - Google Patents

Abstract

The present invention relates to a prosthesis, characterized in that it comprises: a) a substantially cylindrical, radially and axially flexible body, formed of a plurality of wire filaments having crossing points that define an interweave of interstices between the wire filaments, said wire filaments being coated with a polycarbonate urethane polymer having a melting point of about 240 ° C, continuously substantially alone and substantially all their lengths and at said crossing points, such that said wire filaments are attached one to the other by said polymer at said crossing points, and said interstices of said interwoven are not substantially obstructed by the polymer, and b) a porous vascular graft affixed to said body, said porous vascular graft comprising a spun polycarbonate urethane liner having a melting point of about 160

Description

FIXING AND FIXED FIXINGS THAT HAVE A RING RESISTANCE tlE OROPO AND METHODS TO MAKE THEMSELVES BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The invention relates to self-expanding fixed fixators and grafts. More particularly, the invention relates to fixed fasteners and grafts in which the fixator has a polymeric coating that provides improved ring strength, as well as other benefits.

BACKGROUND ART Translumenal prostheses are well known in medical techniques for implantation in blood vessels, bile ducts or similar organs of the living body.

These prostheses are commonly known as fixators and are used to maintain, open or dilate tubular structures or to support tubular structures that are being stretched. When biocornpatible materials are used as a cover or liner for the fixative, the prosthesis is called a fixed or fixed. If used specifically in blood vessels, the fixed graft is known as an endovascular graft. A fixed fixator or graft can be introduced into the body by stretching it longitudinally or by compressing it radially, until its diameter is sufficiently reduced so that it can be fed into a catheter. The fixed graft is released through the catheter to the deployment site and then released from the catheter, after which the catheter self-expands. Fixed grafts introduced in this way are known as fixed endolummal grafts. A fixative of the typical technique, such as that described in the US patent. No. 4,655,771 to Uallsten or in British Patent No. 1,205,743 to Didcott, is shown herein in the prior art figures 1, 2, and 2a. Didcott and Ulallsten describe a tubular body fixer 10 composed of wire elements, e.g., 12, 13, each of which extends in a elicoid configuration with the centerline 14 of the fixator 10 as a common axis. Half of the elements, v.gr. 12, are wound in one direction, while the other half, v.gr. 13, they are wound in an opposite direction. With this configuration, the diameter of the fixator is changeable by axial movement of the ends 9, 11 of the fixator. Typically, the crossing elements form a braided-type configuration and are arranged such that the diameter of the fastener 10 is normally expanded as shown in Figures 1 and 1. The diameter can be contracted by pulling the ends 9, 11 of the fixer 10 away from one another as shown by the arrows 16, 18 in Figure 2. When the ends of the body are released, the diameter of the fixer 10 self-expanding leads to the ends 9, 11 of the fastener to be closer together. The shrink-to-stretch ratio and the radial pressure of the fixators can usually be determined by means of basic braiding equations. A scrupulously technical description of braiding equations and the mechanical properties of fixators is found in Jedweb, M.R. and Olere, C.O. , "A Study of the Geornetrical and Mechanical Properties of a Self-Expanding Metallic Stent - Theory and Expeprnent", Journal of Applied B ornateri ls; Vol. 4, pp. 77-85 (1993). However, in general, the shrink-to-stretch ratio is related to the axially directed angle or between the crossing elements 12, 13 in the expanded state as shown in Figure 1. As explained in Didcott, the larger the magnitude of the angle op greater will be the amount of axial extension required to contract the diameter of the fixator. The ability of a fixator to withstand radial forces is known in the art as "ring resistance". The ring strength of both Uallsten and Didcott fixators is relatively low. The Uallsten fixer provides an improvement in ring strength over Didcott by virtue of the higher pitch angle (a >; 90 °). However, the higher pitch angle of the Uallsten fixator makes the fixator more difficult to position since substantial elongation is required to pull the fastener down into a catheter introducer. Several designs have been made in efforts to increase the ring strength of the fixer. These designs include the use of thinner wires, the use of more wires and the use of wires in pairs. However, there are limitations for each of these designs. For example, if many wires are used or if the diameter of the wire is very long, the fixative will tend to show a tilt at one end and a widening at the other end. This is harmful to the performance of the fastener, yet the use of numerous wires or thin wires commonly results in clogging of the wires when the fastener is driven down. This requires a longer introducer catheter that is more difficult to place in distal and tortuous vessels. Apart from ring strength, another problem with conventional fasteners is that the ends fray or unravel when cut. When this happens, it becomes difficult to load the fixative into a introducer and it is possible for one end of the laminar wire to penetrate the wall of the introducer. Similarly, an untwisted wire can pierce the human vessel during or after placement. In addition another problem with fixers of the technique above, is that during normal use, even without cutting the fastener, the ends of the fastener tend to tilt inward due to the slippage of the wires and the loss of the braid structure. The inclined ends of a fixator can affect the flow through the lumen of the fixator : > ? and cause thrombosis. In addition, since the ends of an installed fixer are tilted inward, the fixer can be discharged and can even be conducted downstream through the vessel in which it was installed. In addition, another problem with the conventional fixators of Didcott or Wallsten is illustrated in Figure 3 of the prior art. When a fixator 10 of this type is deployed in a vessel 20 having a fold 22, the angle of passage of the wire increases in proportion to the fixer 10 passing through the bend 22. Therefore, the diameter of the fixer 10 at the center of the fold 22 is greater than the diameter of the fastener 10 at its ends 9, 11 since the center of the fastener makes the glass narrower in the fold. This tends to alter the hernodynamics of the vessel. Another problem associated with these aforementioned fixators is that the fixator will flex continuously with each bolus of blood passing through it. The flexion continues until the fixative is completely covered with biological tissue. During flexion, the wires support a scissor-like activity at crossing points that can irritate the tissue and adversely affect the patient, especially in small diameter vessels such as the coronary arteries. Moreover, the points at which the wires intersect are subject to abrasion when the fixer is flexed in the vaeculature. Severe abrasion is manifested as wear on the wires which can eventually lead to premature breaking of the wire components.

Another type of fixator (not braided) is described in European Patent Publication No. 0312852 to Ui tor. A Wiktor type fixer 30 is shown in Figure 4 of the prior art in conjunction with a balloon catheter 31. The fixator 30 is made of a single strand of zigzag filament 32 which is helically wrapped around a mandrel. Although the strand 32 does not necessarily cross over itself, the adjacent zig zags, e.g., 34, 36 touch each other or approach each other to touch each other. One of the disadvantages of the Uiktor ipo fixator is that the zigzag wire tends to expand non-uniformly when expanded into an artery by means of a balloon catheter. In addition, the non-braided fixator can be dislodged during manipulation of the balloon catheter in the vasculature, which can cause positioning problems, as well as damage to the endothelium. In addition, the ring resistance of the Uiktor type fixer is relatively low. Other disadvantages of conventional wire fasteners are that they are intrinsically thrombogenic and do not bind well to surface coatings due to the inert nature of the metal oxide layers on the wires.

BRIEF DESCRIPTION OF THE INVENTION It is therefore an object of the invention to provide a fixator and a fixed graft with an improved ring strength. It is also another object of the invention to provide a fixative and a fixed graft that will resist the inclination and maintain the widening at the ends. It is another object of the invention to provide a fixator and a fixed implant that exhibit little or no abrasion of the wires in the vacuum. It is also another object of the invention to provide a fastener and a fixed graft that maintain a substantially constant diameter when installed in the fold of a vessel. In accordance with these objects, which will be described in detail below, the fixed fixators and implantable grafts of the present invention include a conventional fixator which is coated by a polymer so that the polymer coating overlaps the crossing points of the wires, or in the case of a Uiktor type fixator, one the adjacent zig zags of wires without occluding the interstices of the interweaving of the fixator. Suitable coating polymers include polyurethane, polycarbonate polyurethane, polyurethane urea, silicone rubber, polybutylene copolymer (with styrene, etc.), polyolefin, polyester, glycerol polyester, polia ida, polia ida amorphous, combinations of the above and the like . Biodegradable polymers such as polusobutyrate, po birateate, polylactic acid, polyglycolic acid and combinations of these are also suitable.

The main requirement for the polymer is that it may deform during the loading of the fixative into a catheter and have sufficient impact or memory to substantially return to its original shape after the fixative is deployed. The presently preferred polymer is an aromatic polycarbonate urethane of a Shore hardness of BOA at 100D; preferably a Shore hardness of 55D to 75D. The polymer can be reacted in the fixative without a solvent, such as a two-component polyurethane, or silicone rubbers, or the reacted polymer can be dissolved in a suitable solvent, for example dimethylacetamide for the polyurethanes, toluene for the polyolefins or heptane for silicone rubbers. The concentration of solids to solvent is chosen for the specific procedure used to apply the polymer on the fixative. For example, for spray coating, 5 to 10% solids by weight is preferred, although 7% to 13% solids are preferred for surging by surnesion. Binary agents such as dimethylacetamide and tetrahydroturan can be used to accelerate the drying times or the dew accumulation for polyurethanes. To improve the bonding of the polymer to the strand wires, it may be desirable to prime the metallic fixative before coating with polymer. Suitable primers include silane primers such as arninoethylammopropyl-propacytosilane. In addition to spraying and submersion, the polymer can be filled or spun onto the fixative (or primed fixative) and cured or dried to form the polymer adhesive, taking care to avoid occlusion of the interstices of the interlock of the fixative. Alternatively, the polymeric coating can be extruded onto the wire before shaping the fixer and once complete, the polymer can be adhered by fusion to adjacent components. The ring resistance of a polymer coated fastener according to the invention is improved due to the securing of crossing points (or zig zag points) and the prevention of free movement of the relative fastener wires relative to each other. This also prevents the sliding of the wires and therefore the abrasion of the same at the crossing points, as well as the scissor-like movement of the wires, which causes irritation to the tissue and adversely affects the patient, especially in the blood vessels. small diameter as the coronary arteries. The polymer coating adds only a slight increase in the wall thickness of the fastener wires while significantly increasing the ring strength. The introduction profiles of the polymer-coated fasteners according to the invention are not appreciable and increased. The polimeric coating also prevents the ends from fraying or unraveling when the fastener is cut before deployment. In addition, the polyethylene coating helps keep the ends of the fixative widened to prevent the fixator from migrating after deployment. This also provides a dynamically favored flow inlet for blood flow. Moreover, the polimeric coating holds the fixator in a cylindrical configuration throughout its length, thus preventing the phenomenon of ballooning and tilting when deployed in the fold of an artery. The presence of a polymer on the surface of the fixative also allows the release of drugs through the polymer which may take the form of a surface modification or a drug eluting receptacle. For example, an anticoagulant such as hepapn or the like can be attached to the polymer surface and automatically released from the fixative after deployment to prevent thrombosis. Alternatively, drugs such as anti-inflammatory agents, steroids or antimitotic drugs such as radioactive compounds or radioactive drugs may be eluted from the fixative after their deployment. These drugs can prevent intimal hyperplasia. Still alternatively, radioactive materials containing beta or gamma emitters can be stratified in the polymer with their actinic radiation interfering with DNA replication thus increasing the incidence of hyperplasia. Genetically engineered drugs such as growth factors and the like can also be eluted from the coating material.

The objects and further advantages of the invention will be apparent to those skilled in the art with reference to the detailed description taken in conjunction with the figures provided.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a sectional side elevational view of a braided prior art fastener expanded into a non-tensioned possession; Figure la is a cross-sectional view along line 1A-1A of figure 1; Figure 2 is a side elevational view in section of a prior art fastener of Figures 1 and A stretched and contracted; Figure 2a is a tranevereal view along line 2A-2A of Figure 2; Figure 3 is a side elevational view in section of a prior art fixator placed in the fold of an artery; Figure 4 shows a view similar to Figure 1 of a non-deployed zigzag fixer of the prior art in a balloon catheter; Figure 5 is an elongated side elevation view of a portion of a braided fastener of the prior art; Figure 6 is a view similar to Figure 5 of a braided polymer-coated fastener according to the invention; Figure 7 is a view similar to Figure 4 of a zig zag fixative coated with polymer according to the invention; Figure 8 is a perspective view of a fixed and recessed graft coated with polymer according to the invention; and Figure 9 is a schematic sectional view of a polymer coated fastener according to the invention with conical inserts widening the ends of the fixator.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The invention will now be described with reference to several examples in which a prior art fixative is coated with a polymer to attach to the wires of the fixative at crossing points (or zigzag points) without occluding the interwoven texture of the fastener. fixative.

EXAMPLE 1 Referring to Figures 5 and 6, a fastener 50 is made of a Didcott design as shown in Figure 5 of the prior art. Each of the wires, i.e. 52, 53, is approximately 8 millimeters in diameter and the wires are braided at a pitch angle of approximately 85 °. The fastener 50 has an outward ring force for 50% compression of 0.04 kg, ie, a radial load of 0.04 U g is required to radially compress the fastener by 50%. In accordance with a first method of the invention, a Shore 55D polycarbonate urethane is dissolved in dimethylacetamide at a concentration of 5% solids by weight. The mixture is sprayed onto the binder 50 and dried at 7p ° C for 10 minutes to create a coated binder 150 as shown in Figure 6. Preferably, the spraying and drying is repeated several times to accumulate to the surface coating urethane polycarbonate, v.gr. 156, in each of the wires, v.gr. 152, of the fastener 150. The load required to compress the fastener 150 by 50% is tabulated below in table 1 in accordance with the reference number.

The coated fixer 150 can be cut to a size and loaded into a catheter without the ends fraying. The fixative can then be released at the site of the injury to the vascular system and deployed in the normal way.

EXAMPLE 2 An expandable balloon-shaped fixator 30 of the Uiktor design (Figure 4) is placed on a mandrel with adjacent zig zags, e.g. 34, 36, touching each other. The fixative 30 is sprayed with polycarbonate urethane of a Shore 75D hardness dissolved in di-ethylacetamide at a concentration of 10% solids content by weight. The fixative is dried and is sprayed and dried another five times. The resultant fastener 130, shown in Figure 7, is removed from the mandrel and demonstrates a uniform cylindrical outer line with a higher ring force than the uncoated fastener. The zig zag wire comprising the fixer is maintained in a uniform cylindrical outer line. The fixator is deployed with a balloon catheter 31 which expands beyond the relaxation point of the polycarbonate urethane. When the fixator is deployed in this way, it remains open in a uniform cylindrical outer line.

EXAMPLE 3 The Didcott type fixative of Figure 5 is spray-coated (once or several times) with a biodegradable polymer consisting of a mixture of 50% polybuterate and 50% polyvalerate dissolved in chloroform. The resulting fixator is made stiffer than the fixative of Example 1, but it is appreciably softened after its implantation in the body.

EXAMPLE 4 The coated fixative 150 described in Example 1 and shown in Figure 6 is attached to a vascular graft as described in Belgian patent Dereune No. 112,774 and shown in Figure 8 to form an endolute 200 graft. The graft Vascular 202 can be applied to the interior of the fixator or to the exterior of the fixator as shown in Figure 8. The endoluminal graft 200 is implanted in a tortuous artery where it assumes the shape of the artery without the ends tipping or the center inflate.

EXAMPLE 5 The coated fixative 150 described in Example 1, with ten polyurethane coatings is immersed in a solution containing 5% phospholipid in water. A thin layer of phospholipid is subsequently bonded to the surface of the polymer coating. A fixative made in accordance with this example was placed in the coronary artery of a dog and showed a very small truncated accumulation owing to the patchy hernocoid nature of the phospholipid surface.

EXAMPLE 6 In a solution of dimethylacetamide and 5% polycarbonate urethane with a Shore 50D hardness, the drug 5-fluorouracil is added (10% by weight of the drug to the weight of the polycarbonate urethane). The varnish containing the drug is coated by immersion on a fixative and allowed to dry. The drug-eluting polymer-coated fixator according to this example was implanted in the coronary artery of a dog where the drug was slowly released. The drug eluted interfered with the reproduction of DNA in the coronary artery thus preventing intimal hyperplasia of the vessel.

EXAMPLE 7 A Didcott-type fixator like that used in Example 1 is placed on a mandrel having two conical inserts as shown schematically in Figure 9. The tapered inserts 302, 304 are forced into the ends of the fixer 50 so that the ends be widened. The fixative is subsequently coated by spraying with 15 layers of polycarbonate urethane (5% solids) and dried and removed from the mandrel. The fixative shows enlargements in each ext rowing.

EXAMPLE 8 A coated fixator 150 (Figure 6) made in accordance with Example 1 with ten layers of polycarbonate urethane is placed on a mandrel having two conical inserts. The tapered inserts are forced into the ends of the fixer so that the ends are widened. The fixative and the mandrel are then placed in an oven at 170 ° ~ 2Q0 ° C where the polycarbonate urethane is partially fused. The fixator * and the mandrel are subsequently cooled to ambient temperature, at which point the tapered inserts are removed from the fixator. The fixator now shows enlarged ends with a high ring strength at the ends.

EXAMPLE 9 A self-expanding ElgiloyTM wire fixer is primed by immersing it in a 2% solution of ammopropylaminoethyltrirnetoxysilane dissolved in a mixture of 95% / 5% ethanol-water. The primed fixative is subsequently dried overnight at room temperature and placed on a rotating mandrel. The fixative is spray coated and dried three times with a solution containing 9 grams of durometer polyurethane urethane 75D, one gram of 55D durometer polycarbonate urethane, 75 grams of diketiacetamide and 75 grams of tetrahydrofur. The dried fastener has a ring strength four times greater than the initial ring strength of the uncoated fastener. In replacement of an ElgiloyTM wire, the wire can be PhynoxTM 0 316 LV stainless steel.

EXAMPLE 10 A porous, spunbond polycarbonate liner of 160 ° C melting point is made by spinning 500 steps from a 30-hole polymer spinner onto a stainless steel mandrel at 1,000 RPM with a wrapping angle of 50 °. The lining is cured in an oven at 110 ° C during the night. A fixative is coated by immersion with 5% urethane polycarbonate of? 5D hardness and with a melting point of 240 ° C in tetrahydrofuran and drying. The 75D coated fixer is submerged again in another polycarbonate urethane solution but with a hardness of 80A and a melting point of 160 ° C and drying. Ten additional fiber steps are spun onto the liner and while wet, the 75D and 80A coated fixer is placed on the liner and the assembly placed in an oven at 120 ° C where the outer layers on the liner are fused and bind the fixer with the liner. The fixed graft formed in this way has a higher ring strength than without the 75D coating.

EXAMPLE 11 The fixed graft assembly of Example 10 is further reinforced by placing it back on the spinning machine where one additional fiber steps are spun on the fixer. Even if the fibers are wet, a soft silicone roller is passed over the fixative, thus pressing the fibers through the fixative threads and attaching them to the inner lining. The graft fixed in this formed manner demonstrates a much better fixation of the liner with the fixator.

EXAMPLE 12 Tantalum wire of 0.10 m is pulled through a die extruder where a thin layer (0.025 mm) of fluorinated ethylene-polypropylene polymer (EFP) with a melting point of 420 ° C is extruded on the wire. The wires are formed in a zig zag pattern in accordance with Uiktor and subsequently woven into a helical geometry with adjacent zig zags touching each other. The fixative is then heated to 420 ° C where the FEP fuses and when it cools it adheres to the adjacent zig zags. The cooled assembly is removed from the mandrel and shows a uniform design with a ring strength higher than the uncoated fixator. The zigzag wire comprising the fixator remains uniform. The fixative is then expanded in the form of a balloon beyond the resistance to relaxation of the FEP where it is kept open in a uniform manner. Many embodiments of implantable fixators and grafts with wires have been described and illustrated herein, which are coated with a polymer and its crossing points or zigzag vertices. Although there have been various hypotheses and particular examples of the invention, the invention is not intended to be limited thereto, since it is intended that the invention be as broad in scope as the technique allows and that the specification be read from. same way. Therefore, although particular conventional fixators have been described in conjunction with the method of the invention, it will be appreciated that other fixatives may be subjected to the inventive methods described herein. Also, although specific examples of polymetic coatings have been described, it will be recognized that other polymers having similar properties can be used to obtain the same results. Moreover, although specific methods have been shown to apply to the coating, co-or dipping and spraying, other methods can be used. For example, the polymer can be applied using electro-spray, where a potential difference is applied between the spray nozzle and the fixer. In addition, although particular examples have been described in reference to the release of drugs by means of the polyrnery coating, it will be appreciated that other types of drugs can likewise be used. Therefore, it will be appreciated by those skilled in the art that other modifications to the provided invention may still be made without deviating from its spirit and scope as claimed.

Claims (1)

1. 70 NOVELTY OF THE INVENTION CLAIMS 1. - A prosthesis consisting of: a substantial radial and axially flexible cylindrical body of wire filaments with crossing points that define an interweave of interstices between the wire filaments, said wire filaments being coated with a polymer at said crossing points whereby said wire filaments are joined together by said polymer at said crossing points and said interstices of said interwoven are not substantially occluded by said polymer. 2.- A prosthesis in accordance with the claim 1, further characterized in that said polymer is an aromatic polycarbonate urethane with a Shore hardness of 80A to 100D. 3.- A prosthesis in accordance with the reiviication 2, further characterized in that said polymer has a Shore hardness of 55DA to 75D. 4. A prosthesis according to claim 1, further characterized in that said filaments are coated with said polymer along substantially their entire lengths. 5. A prosthesis according to claim 1, further characterized in that said filaments and said polymer are chosen so that a ring strength of said body with said polymer is increased by at least 25% on a second ring strength of a body. similar without said polymer. 6.- A prosthesis in accordance with the claim 1, further characterized in that said filaments are coated with several layers of said polymer. 7. A prosthesis according to claim 1, further characterized in that said polymer elutes drug. B. ~ A prosthesis in accordance with the claim 1, which also consists of: a porous vascular graft attached to said body. 9. A prosthesis according to claim 8, further characterized in that said porous vascular graft is a spun polycarbonate urethane liner with a melting point of approximately 160 ° C, and said polymer is a polycarbonate urethane having a point. of fusion of approximately 240 ° C. 10. A prosthesis according to claim 8, further characterized in that said porous vascular graft are two polycarbonate urethane spun liners, one being placed inside said body and the other being placed on said body, said liners being attached to each other. through said interstices of said interwoven. 11. A method for making a prosthesis, consisting of: a) obtaining a substantially radial and axially flexible cylindrical body formed of a plurality of filaments having crossing points that define an interweave of interstices between the filaments; b) apply a polymer solution to the crossing points; and c) allowing the polymer solution to cure so that the cross filaments are joined together by the polymer and the interstices of the interwoven are not substantially occluded by the polymer. 12. A method according to claim 11, further characterized in that the polyar- neric solution contains a polycarbonate urethane of approximately 55D of .Shore dissolved in dir- ethylacetamide at a concentration of about 5% solids content by weight. 13. A method according to claim 12, further characterized in that the polymer solution is sprayed onto the filaments and cured by drying. 14. A method according to claim 13, further characterized in that steps b) and c) are repeated between five and fifteen times. 15.- A method in accordance with the claim 11, further characterized in that the polymer solution contains a biodegradable mixture of polybuterate and polyvalerate dissolved in chloroform. 16. A method according to claim 11, further comprising: d) fixing a porous graft to the filaments to form a fixed graft. 17. - A method in accordance with the claim 16, further characterized in that the porous graft is formed by spinning a polycarbonate urethane with a melting point of about 160 ° C on a rotating mandrel, curing the graft, spinning a further polycarbonate urethane over the cured graft, placing the fixative on the graft, and cure the fixed graft assembly. 18.- A method according to the claim 17, further characterized in that the graft is further formed by spinning a second additional polycarbonate urethane over the fixed graft assembly, and pressing the second additional polycarbonate urethane through the interstices to join the second additional polycarbonate urethane with the first urethane of additional polycarbonate. 19. A method in accordance with the claim 14, which further consists of: d) coating the cured polymer with a solution containing phospholipid, so that a thin layer of phospholipid is bound to the surface of the polymer. 20. A method according to claim 11, further characterized in that the polyarran solution contains about 10% by weight of the 5-fluorouracil drug and about 5% by weight of polycarbonate urethane with a Shore hardness of about 50D dissolved in dimethyacetamide to form a varnish. 21. A method according to the claim 11, which further consists of: d) before applying the polinepca solution, pressing conical inserts into at least one first end of the substantially cylindrical body so that the first end is widened. 22. A method according to claim 11, further comprising: d) after the polimeric solution has cured, forcing conical inserts into at least one first end of the substantially cylindrical body so that the first end is widened 23. A method according to claim 22, further comprising: e) heating the substantially cylindrical body with said first widened end at about 170 ° -200 ° C until the polymer is partially fused; and f) cooling the substantially cylindrical body and the mandrel to ambient temperature. 24.- A method in accordance with the claim 11, which further consists of: d) before applying the polymer solution, submerging the substantial cylindrical body in a 2% solution of inopropylammoetiitrimethoxysilane dissolved in a mixture of substantially 95% / 5% ethanol and water; and e) drying the substantial cylindrical body before applying the polymer solution. 25. A method according to claim 24, further characterized in that the polymer solution contains about 6% by weight of polycarbonate urethane of about 73D durometer, about 47% by weight of dimethylacetamide and about 47% by weight of tetrahydrofuran. 26.- A prosthesis consisting of: a radially and axially flexible substantially cylindrical body formed by a helically wound zig zag filament, adjacent zig zags defining a interstitial interstice, said filament is coated with a polymer in said pgs. that the zig zags are joined together by means of said polymer and said interstices of said interweave are not substantially occluded by said polymer. 27. A prosthesis according to claim 26, further characterized in that said polymer is an aromatic polycarbonate urethane with a Shore hardness of 80A to 100D. 28.- A prosthesis according to claim 26, further characterized in that said filament is coated with said polymer along substantially its entire length. 29. A prosthesis according to claim 26, further characterized in that said filaments and said polymer are chosen so that a ring strength of said body with said polymer is increased by at least 25% on a second ring strength of a body. similar without said polymer. 30. A prosthesis according to claim 26, further characterized in that said filament is coated with several layers of said polymer. 31. A prosthesis according to claim 26, further characterized in that said polymer elutes drug. 32. A prosthesis according to claim 26, further comprising: a porous vascular graft attached to said body. 33.- A prosthesis according to claim 32, further characterized in that said porous vascular graft is a spun polycarbonate urethane liner with a melting point of approximately 160 ° C. A prosthesis according to claim 32, characterized in addition because said porous vascular graft are two polycarbonate urethane spun liners, one being placed inside said body and the other placed on said body, said liners being joined together through said interstices. 35.- A prosthesis according to claim 26, further characterized in that said filament is tantalum wire and said polymer is an FEP polymer having a melting point of about 420 ° C, which is extruded on said filament as length of substantially the entire length of said filament. 36.- A method for making a prosthesis, consisting of: a) obtaining a substantially radial and axially flexible cylindrical body formed of a spirally wound helical zigzag filament, with adjacent portions of the zig zags defining an interweaving of interstices; b) apply a polymer solution to the adjacent portions of the zig zags; c) allowing the polymer solution to cure so that the adjacent portions of the zig zags are joined together by the polymer and the interstices of the interweave are not substantially occluded by the polymer. 37. A method according to claim 36, further characterized in that the polymer solution is polycarbonate urethane dissolved in dimethylaceta-ida. 38.- A method according to claim 36, further comprising: d) before applying the polymer solution, the body is placed on mandrel with said adjacent portions of said substantially zig zags touching each other. 39.- A method to make a prosthesis, consisting of: a) applying a poly epca solution to wire filaments pulling the wire filaments through a die extruder to form coated wire filaments; b) forming the coated wire filaments in a substantial cylindrical body with the coated wire filaments adjacent to each other in certain locations; c) curing the polymer solution so that the coated wire filaments adhere to each other in said certain locations, thus defining an interweaving of non-occluded interstices. 40. - A method in accordance with the claim 39, further characterized in that the polymer solution is an FEP polymer having a melting point of about 420 ° C, and said curing step includes heating to about 420 ° C with subsequent cooling. 41.- A method in accordance with the claim 40, which further contemplates: d) expanding the substantially cylindrical body beyond the relaxivity resistance of the FEP polymer.