WO1993008986A1

WO1993008986A1 - Coated wire reinforced tubing

Info

Publication number: WO1993008986A1
Application number: PCT/US1992/009256
Authority: WO
Inventors: Csaba Truckai
Original assignee: Csaba Truckai
Priority date: 1991-11-08
Filing date: 1992-10-29
Publication date: 1993-05-13

Abstract

A flexible reinforced tubing (7) of the type having a wire braided reinforcing layer disposed adjacent one or more coating layers (4; 5) of plastic material. The individual wire filaments (1) of the reinforcement layer are plastic encapsulated (2) to promote better adhesion between the wire braided reinforcement layer and plastic coating layers (4; 5). The wires (1) may be electrically conductive to permit the connection of electrically operated devices at selectively stripped portions of the wire coating. In one embodiment, the base coat layer is omitted and the wires are coated with highly lubricous material (18), preferably a polyhalogenated polyolefin such as PTFE or KEL-F plastic. Radially inward facing surface portions of the PTFE coated wires (1) are left exposed to the lumen to increase lubricity. The unexposed surface portions of the PTFE coated wires are selectively etched to promote better adhesion to the top coat layer (14) extruded thereover.

Description

COATED WIRE REINFORCED TUBING SPECIFICATION

FIELD:

This invention relates to a flexible wire-reinforced tubing and fabrication method having improved adhesion characteristics between the wire reinforcement layer and the encasing plastic layer(s). Particular uses of the invention include: medical tubing for catheters, especially guiding catheters adapted for insertion into vascular vessels; and high pressure industrial tubing.

BACKGROUND:

Reinforcement of a tubing structure is necessary when the tubing is required to withstand a variety of different mechanical stresses, such as torque, pushing, pulling, pressure and shearing forces. A typical construction configuration of reinforced tubing is the three layer sandwich comprising a reinforcement layer encased by a base coat and top coat layer. This three layer sandwich is made by forming or extruding a first plastic layer ("base coat") into a tube over a mandrel. A braided or spirally wound metal wire or oriented plastic filament is then tightly woven over the base coat. A second plastic layer or top coat is then applied as an outer coating and is extruded, heat shrunk or otherwise formed to encase the reinforcement layer.

For medical application, such as catheters, a Luer hub is attached to the proximal end of the tubing for the connection of different accessories. A soft, preferably radiopaque, tubular material is fused to the distal (intra corporeal) end of the reinforced tubing for a less traumatic insertion into the vasculature. Guiding catheters, in particular, must be able to transmit high torque for engagement and directional control and have a high inner lumen lubricity for the insertion of secondary devices such as angioplasty and antherectomy devices. Additionally, it is desirable that the outer diameter of the guiding catheter be as small as possible so as to minimize trauma to the patient. The outer diameter dimension is a function of base and top coat width and the type of reinforcement material and braid configuration used. All of these factors must be combined in a way to achieve low kinking characteristics for the tube.

The reinforced tubing can also be modified for use in general industrial applications, such as, for example, a high pressure flexible hose, by connectorising one or both ends for easier attachment into the high pressure system. In order to create a high performance reinforced tubing for use as a catheter or as an industrial high pressure flexible hose, it is desirable that the reinforcement layer and the encapsulating plastic (top/base coat layers) have the strongest adhesion to each other as possible. A strong adhesion improves the torque transmission of the reinforcing material. A strong adhesion between the encapsulating plastic layers and the reinforcement structure is particularly required, when the wall thickness of the tube is extremely thin.

The presently used reinforcing materials, such as oriented plastic or flexible metal filaments, are not suitable for such high performance requirements. While it is true that some oriented plastic filaments, such as Kevlar, Si-Carbide or Nylon fibers, have high tensile strength and relatively good adhesion to the surrounding plastic material (top/base coat) , they are prone to kinking since these types of materials have a very low modulus of elasticity. Metal filaments, such as stainless steel, have a high tensile strength and a high elastic modulus, but they too are inadequate since they suffer from poor adhesion to the extruded thermoplastic materials used for encapsulation. Because of their poor adhesion characteristics, the reinforcing metal filaments tend to slip within the plastic encapsulation (top/base coat) and this slippage decreases their torque transmissivity and lowers their capability to withstand increased internal pressures.

An example of an industrial-type reinforced tubing is found in U.S. Patent No. 2,962,050 issued to Ramburg βt al_/ where it is disclosed to provide a flexible inner plastic hose with an overlapping woven braid reinforcement made of metal strands. The wire mesh has a braid angle of approximately 34' and has a sufficiently tight weave to limit motion of the braid due to internal pressure variations. However, the problems associated with inadequate adhesion between the metal strands and the inner plastic hose were not addressed. Also, Ramburg teaches to further limit motion of the braided reinforcement layer by providing additional layers, which directs away from constructing a thin walled tube.

U.S. Patent No. 4,516,972 issued to Samson discloses a helically wound ribbon of flexible material that is imbedded in the wall of a guiding catheter tube to provide torsional rigidity for facilitating steering and turning of the reinforced tubing. The proposed Kevlar filament is an example of the above described material which has a high tensile strength material and which has relatively good adhesion to the encapsulating plastic materials (top/base coat) , but does not have a high elastic modulus and therefore is prone to kinking.

For some catheters, particularly electrode and ultrasound catheters, it is desirable to provide a means for electrical conduction to permit the hook up of certain desired electrically operated medical diagnostic or treatment devices. U.S. Patent No. 4,027,659 issued to Slingluff teaches to provide an extruded thermoplastic medical tube with a plastic encapsulated strip of powdered conducting metal formed integral with an exterior wall portion of the tube. Other methods teach to place insulated conducting elements directly into the central lumen or into individual lumens which are created with a multi-lumen extrusion process. The above described techniques are very labor intensive, because the conduits have to be placed individually into the lumens. A major disadvantage with these techniques is that their placement within the tubing uses up valuable space.

The prior art industrial and medical spirally wound or braid reinforced tubing requires a relatively thick wall dimension to work adequately. There is an ever increasing need for thinner walled high performance reinforced tubing, especially in the medical and aerospace industries wherein it is necessary that the reinforcement layer have excellent anti-kinking characteristics, a high tensile strength and a high elastic modulus, such as afforded by use of a metal wire reinforcement, and also the reinforced tubing must have an excellent adhesion between its reinforcement layer and its encapsulating plastic tubing layers (top and/or base coat) , such as afforded by a non-metal filament.

There is also a need in the art for an improved reinforced tubing which includes means for electrical conduction without decreasing valuable lumen volume or increasing the outer diameter size of the tubing.

THE INVENTION

DRAWINGS:

The invention is more clearly understood by reference to the drawings in which:

Fig. 1 is an isometric diagrammatic view displaying a section of an individually coated wire;

Fig. 1A is an isometric diagrammatic view, displaying an alternate embodiment for an individual coated wire;

Fig. 2 is a sectioned cut-away isometric view of one embodiment of a coated wire reinforced tubing illustrating the top coat layer, reinforced layer and base coat layer configuration of a three layer sandwich construction;

Fig. 3 is a sectioned cut-away isometric view of a second embodiment for the coated wire reinforced tubing of the present invention illustrating the topcoat layer and the reinforcement layer configuration of a two layer sandwich construction;

Fig. 4 is a cross-sectional view of a PTFE coated wire reinforced tubing taken along the line and in the direction of the arrows 4-4 of Fig. 3; and Fig. 5 is a cut-away isometric view of another embodiment of the invention showing a coated wire reinforced tubing, wherein the insulated wires are used as electrical conduits.

SUMMARY:

I have found that the adhesion properties between a wire braided reinforcement layer and an outer or inner coating of a convention reinforced plastic tubing member may be dramatically improved by first coating individual strand or filaments of the wire braid material with a plastic coating material of the type compatible with the typical coating materials used for the inner and outer layers (base and top coat) of conventional three layer reinforced tubing members. I have also found that commercially available coated wire of the type intended for use in the electronics industry is ideally suited for use in the practice of the present invention. The coated wire is braided or spirally wound to form the conventional annular braid configuration for the reinforcement material in the tubing.

Presently, the coating materials used for commercially available coated wire comprise a variety of plastics, including, but not limited to polyurethane, polyester, polyamide, polyimide and polytetroflouroethylene (PTFE, otherwise known by the Dupont trademark, TEFL0N_TM) or a combination of the above. A known "liquid coating" technology is used to deposit these materials on the wire in extremely thin layers on the order of .00005". Another characteristic of these coatings is that when properly selected, they provide an extremely good adhesion to the metal wire and to an extruded thermal plastic encapsulation layer which may be placed thereover in forming the tubing structure. This adhesion characteristic creates a unique opportunity to build a more positive and cohesive composite tubular structure.

In view of the improved adhesion offered by the individual coated wire strands, the conventional three layer composite reinforced tubing structure, typically comprising a reinforcement layer sandwiched between a top coat layer and a base coat layer, can now be modified to an improved thinner and more cohesive two layer construction comprising only a top coat layer and a coated wire reinforcement layer.

Current extrusion technology does not permit the extrusion of tubing having a wall thickness thinner than .002". Thus, in prior art tubing devices, the base coat or inner tubing wall layer reduces the inner lumen diameter by at least .004". In the improved tubing of the present invention, for the case where the base coat is removed, the total wire coating thickness is no greater than .0004" when the wire coating thickness is .00005" or less. Thus, for any given outside tube diameter, the inside tube diameter can be enlarged by at least .0036". The enlarged inside diameter permits a larger flow rate and increased internal tubing pressures which is desirable for industrial tubing applications.

For the case where the improved reinforced tubing is to be used as a catheter, a larger diameter inner lumen permits faster fluid exchange or, in the case of a guiding catheter, a larger diameter inner lumen permits the insertion of larger medical devices such as angioplasty and antherecto y devices.

In accordance with the method aspects of the present invention, a first embodiment of the coated wire reinforced tubing is constructed by extruding a first plastic tubular member (base coat layer) over a mandrel.

The individual coated wires are then formed through a known spiral weaving process into a braided annular configuration which is tightly overlayed onto the base coat layer. A plastic top coat layer is then extruded and is bonded to the braided reinforcing material by a known hot metal adhesive process to complete the composite tube construction.

In an alternate embodiment wherein the tube comprises only a reinforcing layer and a plastic top coat layer, the method steps include forming the individual coated wires directly over a mandrel into a spiral weave or braided reinforcement configuration after which a plastic top coat is extruded thereover as before. In both methods, the mandrels are removed after the formation of the top coat. In accordance with another embodiment, the individually coated braiding wires are also used as electrical conduits. This feature is particularly useful for some special catheter uses, such as, for example, for electrode and/or ultrasound catheters, since the electrical conduits are built into the reinforcement layer of the tubing structure, thus obviating the need for additional wiring and insulation. Thus, a major space savings can be accomplished by using the individually insulated/coated wires for both tubing reinforcement and electrical conduction. Another advantage offered by this embodiment is the greater number of possible electrical conduits which may be utilized than was heretofore possible with prior art devices. Preferably, the conventional number of 16 wire filaments are used in the reinforcing braid to insure the adequate mechanical properties of the tube. Thus, as many as 16 or more (in the case where up to 32 wire filaments are used) sensors, probes or other electrically operated medical devices can be hooked up to the 16 or more electrically conductive and insulated wires of the reinforcing material. The wire coatings can also be color coded to aid in the identification of the individual conduits.

The manufacturing method for the construction of the electrically conductive coated wire embodiment is the same as described above, except that the braided material is selectively stripped of its plastic coating to permit the electrical connections to a desired wire at the desired location adjacent the distal and proximal ends of the tube.

For the tubing applications where inner lumen lubricity is of the utmost importance, such as in guiding catheters or in the biopsy forceps channels of a flexible scope, it is preferred to use the above described two layer tubing configuration (i.e., where the plastic base coat has been omitted) so that the plastic coated wire reinforcement layer forms the inner lumen. Also, it is preferred to coat the individual wires with a PTFE coating. It should be noted that the PTFE coated reinforcement layer of the present invention has improved lubricity characteristics over a conventional PTFE inner liners of the same inner lumen diameter since the bumps and ridges created in the inner lumen from the PTFE braiding reinforcement layer reduce the total contact surface area so that the inserted medical devices encounter less drag resistance.

This method of construction for the tubing embodiment using the PTFE coated braid material involved the formation of a soft, preferably silastic or polyethylene material into a tube structure over a stretchable mandrel. A PTFE coated wire braid configuration is then formed over this soft material in such a way that, during the braiding operation, the tension on the individual filaments is set sufficiently high to embed the PTFE coated wire into the soft material to a predetermined depth. the exposed portions of the braided material are then etched with a known TETRA-ETCH_TM solution. In other words, the PTFE coated braid is not etched on those surface areas where it is embedded into the soft material since it is shielded from the etching solution at these surface areas. A plastic topcoat layer is then extruded over this uniquely etched braid reinforcement. The mandrel and the soft inner coating are then removed so that the unetched inner diameter facing surfaces of the PTFE coated wire are exposed. With this technique, the unetched portion of the braid reinforcement will stand out from the topcoat plastic encapsulation to form a bump or ridge and any object which is pushed through the lumen, such as, for example, an angioplasty balloon catheter, will only have contact with this smaller unetched PTFE surface area. This results in a reduction of the insertion force necessary to overcome inner lumen surface drag. DETAILED DESCRIPTION OF THE BEST MODE:

The following detailed description illustrates the invention by way of example, not by way of limitation of the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what I presently believe is the best mode of carrying out the invention.

Fig. 1 is an isometric diagrammatic view of a section of the coated wire filament reinforcement material 1 of the present invention.

The coated wire filament 1 comprises a core 3 which is encapsulated by a plastic coat or layer 2. The core material 3 is preferably metal, such as commercially available grades of stainless steel wire or nickel alloy, but it is understood that any other ferrous or non-ferrous metal or alloy composition may be used. As is seen in Fig. 1, the cross-sectional configuration of metal core 3 is preferably circular or round, but it is understood that conventional flat wires may also be used in combination with the present invention and thus the cross sectional configuration for the metal core may be square or rectangular (see for example, element la of Fig. 1A) . Moreover, the metal core 3 may also comprise a braided wire which is plastic encapsulated.

The composition of the plastic coat 2 is selected to yield the best possible adhesion to the type of metal core 3 used. Preferred plastic materials include polyurethane, polyester, polyamide, polyimide, polytetroflouroethylene (PTFE or otherwise more commonly known as "TEFLON_TM" brand plastic) or any like flouropolymer of any useful combination thereof. Fig. 2 is an isometric view illustrating the application of coated wire 1 of Fig. 1 in combination with one embodiment of the reinforced tubing 7 of the present invention.

The reinforced tubing 7 comprises a first inner plastic tubular member or "base coat" layer 5 having an inner lumen 6, a reinforcing layer formed of braided coated wires 1 and an outer plastic tubular member or "top coat" layer 4. The reinforcement layer is disposed almost entirely within the top coat layer 4.

To fabricate the reinforced tubing 7, the base coat layer 5 is extruded into an elongated tubular member on a conventional fusing mandrel. The outer perimeter surface of the base coat layer 5 may be "roughened" by known chemical treatment means, such as, for example, application of TETRA-ETCH solution, to promote better adhesion to overlaying plastic layers. This roughening step is preferred when the wire coating is PTFE.

A braid reinforced plastic tube is then formed by braiding the individual coated wires 1 into a desired braiding configuration over a ductile wire mandrel and then applying the elastomeric plastic top coat layer 4 by a conventional wire coating extrusion apparatus. During the braiding and extrusion operation, the wire mandrel serves to support the inside of the tube and prevent it from collapsing, the extruded tube stock is then cut to length and the mandrel is removed.

Following this, the fusing mandrel along with the prepared inner tubular member (i.e., base coat layer 5) is inserted within the extruded tube (top coat layer 4 and wires 1) and bonded together by a heat shrinkable tubular sheet in accordance with hot melt techniques well known by those skilled in the art. Alternatively, the base coat layer 5 may be directly extruded over the fusing mandrel having the prepared inner tubular member thereon.

It is evident from Fig. 2 and from the above described manuf cturing process that the coated wire 3 is almost totally embedded within the top coat layer 4. Accordingly, the plastic coating 2 of the coated wire 1 should be selected so as to provide the adhesion possible with both the metal core 3 and to the top coat layer 4. It should be noted that commercially available plastic coated wire intended for use in the electronics industry is ideal for this purpose. By creating a good adhesion between the top coat layer 4 and the coated wire reinforcement layer 1, the base coat layer can be eliminated without sacrificing the mechanical characteristics of the reinforced tubing. This is described below in greater detail with reference to Figs. 3 and 4.

The coated wire reinforced tubing of the present invention is particularly well suited for medical tubing applications. For example, the tubing may be incorporated into the tubular body portion of a catheter. For this application, the preferred thickness dimension of the metal core 3 of the coated wire should be sufficiently large to provide adequate strength and prevent kinking when formed into the braided reinforcement layer 15. Generally, a core diameter in the range of about .001" -

.010" is sufficient for this purpose. the thickness of the plastic coating 2 is sufficient to completely cover the core and is preferably in the range of about .00005" -

.001". The braided coated wire reinforcement layer preferably consists of 16 to 32 strands of stainless steel wires woven in a one-over-one, one-over-two, two-over-one or two-over-two configuration. In the embodiments shown in Figs. 2-4, the braided reinforcement layer consists of 16 stainless steel wires woven in a two-over-two configuration. Each strand may consist of either one wire or a plurality if wires (wire bundle) , but preferably two round cross sectional monofilaments of braided wires. The monofilaments are also of preferably high tensile strength braided wires, woven in a side-by-side fashion. However, it is understood that annealed wires may also be used with equally good results.

Fig. 3 is an isometric view illustrating the coated wire 1 of Fig. 1 used in combination with a second embodiment of the reinforced tubing 17 of the present invention.

In this embodiment, the reinforced tubing 17 comprises only a top coat layer 14 having an inner lumen 16 and a reinforcement layer formed of braided coated wires 1. The radially inward facing surfaces of the coated wires 1 are exposed as certain areas 18 inside the lumen 16. Since the individually plastic coated wires 1 of the reinforcement layer provide excellent adhesion to the top coat layer 14, a base coat layer is unnecessary. The result is a very thin walled reinforced tube 17 which, because of the braided coated wire reinforcement, has superior mechanical characteristics. Also, the improved adhesion permits a thinner extrusion of the top coat layer 14, since the torque transmissivity characteristics of the reinforced tubing 17 are no longer solely dependent upon the thickness of the top coat layer 14. Improved inner lumen lubricity is also a desirable result of the reinforced tubing embodiment of Figs. 3 and 4. As is best seen in Fig. 4, the exposed portions 18 of the coated wires 1 form bumps and ridges within the inner lumen. This embodiment is ideally suited for use as a guiding catheter since the presence of the exposed portions 18 reduce the total contact surface area (hence drag) that an inserted medical device would encounter as it is guided through the lumen 16. Moreover, since the base coat layer has been omitted, a larger lumen 16 is now possible.

To further improve lubricity, it is preferred to use PTFE as a coating material for the coated wires 1. As will be appreciated by those skilled in the art, the PTFE coated wire reinforced tubing of the present invention offers a significant advance in lubricity (and enlarged lumen size) over conventional guiding catheters which use a separate PTFE inner liner to promote lumen lubricity.

As is evident from Figs. 3 and 4, the PTFE coated wires 1 of the reinforcement layer are only partially embedded into the top coat 14. To promote better adhesion between the PTFE coated wire 1, and the encapsulating top coat 4, the PTFE coated wires 1 are preferably etched along the embedded surfaces 19.

To construct the PTFE coated wire reinforced tube 17 a soft, preferably silastic or polyethylene material is first extruded over a stretσhable mandrel. Then the PTFE coated wire 1 is formed into a braid over this soft material in such a way that during the braiding operation the tension on the individual filaments is set high enough to partially embed the coated wire 1 into the soft material to a predetermined depth. This embedded area corresponds to the exposed surfaces 18 of Figs. 3 and 4.

Next, an etching solution, such as TETRA-ETCH_TM solution, is applied to treat surface areas 19 of the coated wires 1. After this, the plastic top coat layer 14 is extruded over the etched braid reinforcement. The mandrel and the soft coating on it are then removed, exposing the unetched surfaces 18 of the PTFE coated wires 1. with this technique, the unetched portions 18 of the braid reinforcement will stand out from the top coat plastic encapsulation 14 and any object such as, for example, an angioplasty balloon catheter, may be pushed through the lumen 16 with a reduced insertion force.

Fig. 5 shows the cut-away side view of a reinforced tubing 27, where the coated wires 1 serve both as the tubing reinforcement and as individually insulated electrical conduits. The coated wire 1 can be stripped at preselected areas 22 to permit an electrical connection or hook up.

For some special devices, such as electrode and ultrasound catheters, different sensors or electrical connections are required at different locations of the reinforced tubing. For this purpose, separate insulated conductors are attached to the reinforced tubing wall or are placed within the lumen. With the coated wire reinforcement of the present invention, when a ferrous or other electrically conductive core material is used, the reinforcement can also serve as an electrical conduit. Individual wires can be color coded to further assist in the identification of the desired electrical connection at both ends of the tubing.

It should be understood that various modifications within the scope of this invention can be made by one of ordinary skill in the art without departing from the spirit thereof. For example, while the invention has been described in great detail with particular reference to the close and exacting thickness tolerances associated with catheter applications, it is understood that the reinforced tubing of the present invention may also be adapted for use in industrial tubing applications which, in general, do not require the degree of tolerances associated with medical tubing applications. In this regard, it should be noted that the 3 layer reinforced tubing embodiment 7 disclosed in Fig. 2 is preferred when laminar flow is of primary concern. I therefore wish my invention to defined by the scope of the appended claims in view of the specification as broadly as the prior art will permit.

Claims

CLAIMSI CLAIM:

1. An improved flexible reinforced tubing comprising in operative combination: a) a first tubular member formed of a flexible plastic material; b) a braided reinforcement layer overlying the outer surface of said first tubular member; c) said braided reinforcement layer further includes: i) a plurality of wire filaments; ii) each of said wire filaments is individually encapsulated with an adherent plastic coating; and d) a second extruded flexible plastic tubular layer disposed around and encapsulating said first tubular member and said reinforcement layer, said extruded layer is adhered strongly to the plastic coating of said wire filaments of said reinforcement layer to increase torque transmissivity and enhance the mechanical properties of said flexible reinforced tubing.

2. An improved flexible reinforced tubing as in claim 1 wherein: a) said plastic coated wire filament of said reinforcement layer are substantially embedded within a wall portion of said second tubular layer; and b) said plastic coated wire filaments include a metal core having an elastic modulus sufficiently high and a core dimension sufficiently thick to resist kinking.

3. An improved flexible reinforced tubing as in claim 2 wherein: a) at least one of said wire filaments is electrically conductive; b) said wire filament plastic coating is electrically insulating; and c) at least one of said wire filament plastic coatings is stripped at selected locations along said filament to permit the connection of electrically operated devices thereto.

4. An improved flexible reinforced tubing as in claim 3 wherein: a) said flexible reinforced tubing is used as the main tubular portion of a catheter wherein: i) said metal cores of said wire filaments have an outer diameter in the range of from about 0.001" to about 0.010"; and ii) said plastic coating for said wire filaments has a thickness on the order of at least 0.00005"; and b) said first tubular member is formed of a PTFE plastic material to promote lumen lubricity.

5. An improved flexible reinforced tubing as in claim 2 wherein: a) said flexible reinforced tubing is used as the main tubular portion of a catheter wherein: i) said metal cores of said wire filaments have an outer diameter dimension in the range of from about

0.001" to about 0.010"; and ii) said plastic coating for said wire filaments has a thickness on the order of at least 0.00005"; and b) said first tubular member is formed of a polyhalogenated polyolefin plastic material to promote lumen lubricity.

6. An improved flexible reinforced tubing comprising in operative combination: a) a braided reinforcement layer formed as a first inner tubular member which includes: i) a plurality of wire filaments; ii) each of said wire filaments is individually encapsulated with an adherent plastic coating; and b) a flexible plastic outer tubular member having an inner diameter sufficient to encapsulate at least said outer perimeter surface of said tubular reinforcement layer; c) said second flexible tubular member substantially embedding the exterior surface of said braided reinforcement layer to provide a strong adhesion between the plastic coated wire filaments of said reinforcement layer and said second flexible tubular member to increase torque transmissivity of the reinforced tubing; and d) at least a portion of an inner surface of said braided reinforcement layer projecting into a central lumen of said outer tubular member.

7. An improved flexible reinforced tubing as in claim 6 wherein: a) each of said plastic coated wire filaments includes a metal core portion having an elastic modulus sufficiently high and a core dimension sufficiently thick to resist kinking and to maintain the mechanical properties of the reinforced tubing.

8. An improved flexible reinforced tubing as in claim 7 wherein: a) at least one of said wire filaments is electrically conductive; b) said wire filament plastic coating is electrically insulating; and c) at least one of said wire filament plastic coatings is stripped at selected locations along said filament to permit the connection of electrically operated devices thereto.

9. An improved flexible reinforced tubing as in claim 8 whereby the tubing comprises the main tubular portion of a catheter wherein: a) said metal cores of said wire filaments have an outer diameter in the range of from about 0.001" to about 0.010"; b) said plastic coating for said wire filaments comprises a polyhalogenated polyolefin plastic material to promote lumen lubricity and said PTFE plastic coating having a thickness on the order of at least 0.00005".

10. An improved flexible reinforced tubing as in claim 9 wherein those portions of said polyhalogenated polyolefin plastic coated wire filaments disposed to contact said plastic outer tubular member are etched to improve adhesion.

11. An improved flexible reinforced tubing as in claim 7 whereby the tubing comprises the main tubular portion of a catheter wherein: a) said metal cores of said wire filaments have an outer diameter dimension in the range of from about 0.001" to about 0.010"; b) said plastic coating for said wire filaments comprises a polyhalogenated polyolefin plastic material to promote lumen lubricity and said polyhalogenated polyolefin plastic coating having a thickness on the order of at least 0.00005".

12. An improved flexible reinforced tubing as in claim 11 wherein those portions of said polyhalogenated polyolefin plastic coated wire filaments disposed to contact said plastic outer tubular member are treated to improve adhesion.