Patent Description:
<CIT> teaches a flexibility/rigidity adjustable device which can change its state between a flexible state and a rigid state and has a flexible cover <NUM> which can expand/shrink over a flexible tube <NUM>, and a latching member <NUM> movable with the closing cover <NUM> into and out of engagement with a latching member receiving part <NUM>. The latching member <NUM> can be separate structures or can be part of the closing cover <NUM>.

From the United States patent application publication <CIT> a manipulator for minimally invasive surgery procedures is known including a flexible pipe that may be inserted into one or more cavities of a body. The pipe may be stiffened by applying pressure to a plurality of overlapping flap members stiffening the tube by frictional forces between at least some of the plurality of overlapping flap members resulting from the applied pressure.

It is an object to create a flexible lumenal assembly. This and other objects are achieved by the features as claimed in claim <NUM>. Advantageous further embodiments are claimed in the dependent claims. As used herein, "outer" in the context of outer tubular member, outer member, outer element, outer cover, outer envelope or outer wall refers to a position relative to the structural support member, and "outer" in this context does not mean outer-most.

These and other examples are set forth more fully below in conjunction with drawings, a brief description of which follows.

This specification taken in conjunction with the drawings sets forth examples of apparatus incorporating one or more aspects of the present inventions in such a manner that any person skilled in the art can make and use the inventions. The examples provide the best modes contemplated for carrying out the inventions, although it should be understood that various modifications can be accomplished within the parameters of the present inventions.

Examples of lumenal or tubular structures and of methods of making and using the lumenal or tubular structures are described. Depending on what feature or features are incorporated in a given structure or a given method, benefits can be achieved in the structure or the method. For example, tubular structures using inner and outer tubular elements, which may but need not be concentric, may be configured to have one stiffness in a first state and another stiffness in another state, for example may be configured to be relatively rigid when in a relaxed state, and less rigid when one or more elements in the tubular structures are activated. Inner and outer tubular elements can also be configured with an intermediate structural framework that can provide a more reliable support assembly when in a support configuration, for example when the inner and outer tubular elements and the structural framework are pressed together. Configurations of inner and outer tubular elements may also be used to more securely releasably fix the tubular elements in a desired geometry, for example to support passage of another element, for example an interventional device or other device, during a procedure.

Examples of inner and outer lumenal element or tubular elements and medial member forming intermediate structural frameworks can also be used to provide a more reliable support structure per unit length of an assembly of the tubular elements and structural framework. Elements of one or more of the inner and outer tubular elements and structural framework can be configured to incorporate a desired flexibility or stiffness per unit length. In one example, a structural framework can be used intermediate the inner and outer tubular elements that provides a given flexibility or stiffness per unit length, and a different structural framework can be used to manufacture or assemble another combination having a different flexibility or stiffness per unit length. In another example, a structural framework can be used to provide a given flexibility or stiffness as a function of inflation or deflation of a component adjacent the structural framework. In one configuration, the structural framework can provide an increased stiffness when an adjacent component presses against it, for example when deflation brings the component into contact with the structural framework, and can provide a decreased stiffness when the adjacent component has a reduced amount of contact with the structural framework.

In some configurations of lumenal or tubular structures, improvements can be achieved also in assembly, and in some configurations, assemblies can be produced having an assembled or final configuration with a desired stiffness or flexibility, and wherein such stiffness or flexibility can be selectively or intermittently reduced through one or more actions. For example, an assembly can be produced where a component in a relaxed or natural state presses against a structural framework, in one example where a resilient tubular structure presses against a structural framework. In another example, a user can reduce a stiffness or flexibility in an assembly by releasably inflating or enlarging at least one of the tubular structures, which can reduce a stiffness or flexibility in at least part of the assembly.

These and other benefits will become more apparent with consideration of the description of the examples herein. However, it should be understood that not all of the benefits or features discussed with respect to a particular example must be incorporated into a tubular structure, component or method in order to achieve one or more benefits contemplated by these examples. Additionally, it should be understood that features of the examples can be incorporated into a tubular structure, component or method to achieve some measure of a given benefit even though the benefit may not be optimal compared to other possible configurations. For example, one or more benefits may not be optimized for a given configuration in order to achieve cost reductions, efficiencies or for other reasons known to the person settling on a particular product configuration or method.

Examples of a number of tubular structure configurations and of methods of making and using the tubular structures are described herein, and some have particular benefits in being used together. However, even though these apparatus and methods are considered together at this point, there is no requirement that they be combined exactly as described, used together in the exact combinations, or that one component or method be used only with the other components or methods, or combinations as described. Additionally, it will be understood that a given component or method could be combined with other structures or methods not expressly discussed herein while still achieving desirable results.

Catheters are used as examples of a tubular structure that can incorporate one or more of the features and derive some of the benefits described herein, and in particular vascular catheters. Catheters used for navigation and for support for other components in vessels have a number of configurations, and such catheters can benefit from one or more of the present inventions. Tubular structures other than catheters can benefit from one or more of the present inventions.

As used herein, "substantially" and "approximately" shall mean the designated parameter or configuration, plus or minus <NUM>%.

A lumenal or tubular structure can be incorporated into a number of devices, which may include apparatus and methods for varying the stiffness or flexibility of, or support provided by, such lumenal or tubular structure. The present examples described herein relate to lumenal or tubular structures for catheters, for example catheters for traversing vasculature, including human vasculature. However, it is understood that the components and assemblies described herein can be used in a variety of structures and applications, including catheters for other applications, and other lumenal or tubular structures. The present examples will include vascular catheters, but other structures are applicable as well.

In one example of a lumenal or tubular structure (<FIG>), a catheter assembly <NUM> includes a catheter having a shaft <NUM>. The catheter assembly <NUM> is configured to be sufficiently flexible to transit human vasculature. The catheter assembly further includes a catheter hub <NUM>. The catheter hub can take a number of configurations, and may be used to receive and provide a number of structures and components and/or fluids in the use and application of the catheter, and may be used with a number of other instruments and/or components as would be understood to one of ordinary skill in the art. In the present example, the catheter hub includes an inflation or injection port <NUM> for receiving an injection or inflation device, in the present example denominated as syringe <NUM> having a syringe body or barrel <NUM> and plunger <NUM>, for example for injecting and withdrawing fluid from or into the barrel <NUM>. The syringe will be used to hold and inject or withdraw saline into or from the catheter hub <NUM> or lumen (in the example of <FIG> described more fully below). The syringe is mounted or secured in the inflation port <NUM> in a conventional way.

The catheter hub <NUM> includes a main body <NUM> extending longitudinally and defining in part a main axis of the catheter hub, at the proximal portion of the catheter. The catheter hub body <NUM> includes an internal wall defining a bore <NUM> extending from a proximal end <NUM> of the catheter hub to a distal end <NUM> of the catheter hub, and is configured in a conventional manner for receiving devices and materials, and may receive in the present example a dilator <NUM> as illustrated. The dilator can be omitted, or replaced by a cover or by other components. In the present example, the dilator <NUM> includes a dilator hub <NUM> mounted on or secured to the proximal end <NUM> of the catheter hub, and a dilator shaft <NUM> extending longitudinally of the catheter hub inside the wall <NUM> and within the catheter shaft <NUM>. In the present example, the dilator shaft <NUM> extends through a distal end portion <NUM> of the catheter shaft and includes a dilator tip <NUM>. In the present example, the dilator tip extends beyond a distal end surface <NUM> of the catheter shaft, for example a distance typical for catheter and dilator assemblies. The dilator <NUM> is a conventional dilator, configured for use with a catheter such as any of those described herein. In one example, the dilator is configured for receiving a guidewire or other guide device (not shown) through the central lumen of the dilator.

The inflation port <NUM> includes an internal wall <NUM> defining a bore extending to the central bore <NUM> of the catheter hub. The inflation bore <NUM> is in fluid communication with the central bore <NUM>, and fluid from the inflation port <NUM> can flow into and out of the central bore <NUM> around the dilator shaft with the operation of the syringe <NUM>, as well as under the influence of any other forces or influences in the design of the catheter. An interference fit between the dilator distal end and the catheter shaft distal end keeps fluid in the central bore <NUM>.

The catheter shaft <NUM> includes a lumenal member, in the present example a tubular member <NUM>. A proximal portion <NUM> of the tubular member <NUM> is mounted, secured and sealed in the distal portion <NUM> of the catheter hub in a conventional manner. The tubular member extends longitudinally from the catheter hub to the distal end portion <NUM> of the catheter shaft, and specifically terminates in the present example at the distal end surface <NUM>. The tubular member is formed so as to be sufficiently flexible for transiting human vasculature and body lumens, including cardiac, peripheral, and cerebral vasculature, which can be tortuous. The tubular member <NUM> in the present example has a substantially circular cross-section, but can have other cross-sectional profiles. The tubular member is substantially coaxial with the central axis of the catheter hub <NUM> when in the shape as illustrated in <FIG> and <FIG>.

The tubular member <NUM> is substantially cylindrical over substantially its entire length. The tubular member also has a substantially uniform wall thickness over substantially its entire length, for example <NUM>" - <NUM>" (<NUM> inch = <NUM>,<NUM>), and it also has a substantially uniform inner diameter, for example <NUM>" - <NUM>", over its entire length from inside the catheter hub up to just proximal of the distal end portion <NUM>, which is described more fully below. However, it is understood that other tubular geometries can be used, and the catheter shaft can be formed with other cross-sectional profiles. Alternatively, the catheter shaft <NUM> can have other constructions and geometries than those described herein, and such other constructions and/or geometries may include lumens, as desired, for example for passage of apparatus or fluids, such as guide wires, tubular devices, instruments, saline, contrast, and other devices and materials.

The tubular member <NUM> is formed from a suitable material, which may be determined by the intended application. In the present examples, the tubular member <NUM> is formed from an elastomeric material conventional for vascular catheters, for example PEBA, polyurethane, or similar. The internal and external surfaces of the tubular member are configured to have the desired finishes for their intended purposes. In the present example, the outside surface <NUM> (<FIG>) permits easy movement through other devices and through vasculature, as necessary. The inside surface <NUM> permits fluid flow within the tubular member and easy movement of the dilator shaft <NUM> and any other devices or materials as desired, such as interventional devices/instruments.

In the illustrated example, the tubular member <NUM> includes strengthening elements. In the present example, the strengthening elements include one or more helical coil structures <NUM> (<FIG>). In the present example, the helical coil <NUM> is a single continuous helical coil extending from inside the catheter hub <NUM> to a point adjacent the distal end portion <NUM> of the tubular structure. The helical coil can take the form of conventional reinforcement for conventional catheter tubes, and may be stainless steel, for example <NUM> or <NUM> stainless steel, with a diameter of <NUM>" - <NUM>" (<NUM> inch = <NUM>), and a pitch of <NUM>" - <NUM>". Furthermore, the coil may be formed from a wire with a non-circular shape in cross section, such as a rectangle or oval cross section. The coil can be formed from other materials, with other coil and strand diameters and/or with other pitches, to provide the desired strength, reinforcement and/or stiffness. Other strengthening devices can be used, either alternatively or additionally. For example, braid structures can be used. In the present example, the strengthening elements are embedded in or coextruded with the tubular member <NUM>, for example as would be conventional.

The tubular member <NUM> extends distally to the distal end portion <NUM>, where the coil <NUM> terminates. The elastomeric tubular member continues distally at a converging portion <NUM>, which then terminates at a cylindrical or annular wall portion <NUM>. The distal end portion <NUM> is formed with a diameter so as to provide an interference fit with the dilator tip <NUM>, both of which are configured to provide the desired interference fit.

The tubular member <NUM> geometry and structure in the present example extends uninterrupted from the proximal to the distal end portions except for one or more apertures or fluid openings <NUM> (<FIG>). The apertures <NUM> extend completely through the tubular wall between strands of the coil and provide a fluid path between the inside and the outside of the tubular member at a location of the openings, which in the present example are within an outer tubular member described more fully below. The fluid openings allow fluid to pass from the lumen within the tubular member <NUM>, for example fluid from the inflation port <NUM>, to a cavity or recess or balloon outside the tubular member <NUM>. In the present example, there are two fluid openings through the wall of the tubular catheter member.

Use of fluid to expand and/or contract the volume of a cavity containing a structural support element allows changing conditions of the tubular structure. For example, inflation and deflation or reduction in pressure or application of vacuum can change a stiffness or flexibility of a structure. In one example, inflating a cavity containing a structural support element can increase the flexibility of the catheter in the area of the structural support element, and reducing the pressure, applying vacuum or allowing deflation of the cavity can decrease the flexibility of the catheter. In this way, the catheter can have a selective adjustability of its stiffness or flexibility.

The configuration of the tubular member <NUM>, as the inner layer or inner tubular element, can be configured in a number of ways. Flexibility can be enhanced along the length, including in the distal portion of the tubular element, by changing the durometer of the material as a function of its length, and/or adjusting the wall thickness of the tubular member as a function of length or distance from the catheter hub. Alternatively and/or additionally, the reinforcement can be modified as a function of distance from the catheter hub, for example by changing the geometry or the spacing of the material. In the example of a helical coil, the pitch of the coil can be changed, or the diameter of the coil or strand element embedded in the tubular member. The reinforcement material can be metal or non-metal, and may be stainless steel, nitinol, polymeric fiber, metallic wire with a radio opacity property, tantalum, tungsten, or alloys of these materials or other materials.

The catheter <NUM> further includes an adjustable member outside of the catheter tubular member <NUM>, extending over at least a portion of the outer surface of the tubular member <NUM>. In the area of the adjustable member, the catheter tubular member <NUM> is an inner tubular member relative to the outer adjustable member. In some configurations, the adjustable member is used to selectively establish or change a flexibility or stiffness of a portion of the catheter, for example the portion of the catheter around which the adjustable member is positioned. The adjustable member can be used to sandwich one or more underlying components within an envelope, cavity or area over or around which the adjustable member extends. The adjustable member can be used to increase surface areas of contact between adjacent elements, and to establish or increase internal forces that must be overcome to move or change a geometry of a portion of the catheter. The adjustable member can also be used to effectively separate itself from a portion or all of an underlying component, which may allow separation of additional components from each other, and which may also allow position adjustments or other adjustments of one or more underlying components. The adjustable member can be configured to be normally in a first condition or normally in a second condition (for example having a memory characteristic), for example normally producing contact with underlying components or normally separating from underlying components, or normally applying pressure or normally released from applying pressure. Alternatively, the adjustable member can be configured to remain in a given state until acted upon, for example without any memory characteristic. In the examples described herein, the adjustable member is configured to be normally in a collapsed, reduced or application mode where pressure or force is applied by the adjustable member to one or more underlying components. The adjustable member is adjusted by positive action to change the adjustable member from its collapsed, reduced or application mode at least in part, for example to reduce a surface area of contact between the adjustable member and an underlying component. In the present examples, the adjustable member is movable radially. Also in the present examples, the adjustable member applies pressure to an underlying component along the entire length of the underlying component substantially simultaneously.

An example of an adjustable member (<FIG> and <FIG>) is tubular member <NUM>. In the present example, the tubular member <NUM> extends over a portion of the catheter shaft <NUM>. The tubular member <NUM> forms an outer tubular member (outer tube) to the extent that it is outward of the adjacent portion of the catheter shaft <NUM>. However, it is understood that one or more other components can be outward of the outer tubular member <NUM>. A proximal end <NUM> of the outer tube is secured to an adjacent portion of the catheter tubular member <NUM>, circumferentially around the entire portion of the proximal end <NUM> of the outer tube. The proximal end can be sealed, welded, bonded, for example thermally or adhesively, or otherwise secured to the outer surface of the catheter tubular member <NUM>, for example in a manner similar to concentric catheter tubes may be secured to each other in conventional catheters. With the present outer tube, the outer tube is secured to the catheter tubular member <NUM> at both ends of the outer tubular element in such a way that the junction can withstand expected internal fluid pressures developed between the outer tubular member and the catheter tubular member <NUM>.

The outer tube <NUM> extends distally from the proximal end portion <NUM> over the catheter tubular member <NUM> to a distal end portion <NUM> of the outer tubular member, surrounding the distal end portion <NUM> of the catheter tubular member <NUM>. The distal end portion <NUM> is sealed, welded, bonded or otherwise secured to the adjacent distal end portion of the catheter tubular member in the same manner as for the proximal end portion <NUM>. The outer tube <NUM> forms between the proximal and distal end portions a cavity, envelope or annular space <NUM> between the inside surface <NUM> of the outer tube <NUM> and the opposite or facing outer surface <NUM> of the inner tubular member <NUM>. The cavity <NUM> forms in the present examples a balloon which can be enlarged or inflated as a function of the flexibility and strength of the outer tubular member <NUM>. In some configurations, the adjacent portion of the inner tubular member may also be sufficiently flexible to provide a measure of additional inflation or enlargement, inwardly toward the central axis of the catheter, but the present configurations have the inner tubular member <NUM> with the embedded coil <NUM> such that the wall of the inner tubular member does not change diameter significantly under the presently contemplated pressures within the cavity <NUM>, and remains a constant diameter before, during and after inflation or enlargement of the outer tubular element and an before during and after deflation or full collapse of the outer tubular element.

In the present example, the outer tube <NUM> is a monolithic structure, and is formed from a material that is flexible and can increase in diameter (i.e., increase in diameter where the outer tube is substantially cylindrical or circular) upon application of an internal pressure (for example between approximately <NUM>-<NUM> psi or <NUM>-<NUM> kPa) between the outer tube <NUM> and the inner tube <NUM>. The outer tubular element serves as a balloon that can expand outwardly upon application of an internal pressure, for example pressure developed by a fluid, in one example a relatively incompressible fluid. The outer tubular element <NUM> is configured to have a maximum expandable diameter under normal operating conditions for example by selecting a material that can inherently expand or stretch to a selected or preferred diameter and maintain that diameter even with possible expected higher pressures.

The outer tubular element <NUM> in the present examples is formed from polyurethane, and has a wall thickness of approximately <NUM> inches (<NUM>). In the present examples, the outer tubular element <NUM> has a relaxed internal diameter when originally formed and before assembly on the catheter of approximately <NUM> inch (<NUM>). when the other components inside the outer tubular element are dimensioned as described herein. It has an expected inflated internal diameter of <NUM> inches (<NUM>).

The material is preferably abrasion resistant, and highly resistant to puncture. The outer tubular element <NUM> in the present examples has a structure similar to balloon catheters but without any folds or creases, and can be produced in a manner similar to balloon blow molding processes. In the present example, the outer tubular element <NUM> is formed prior to assembly to be configured to be normally collapsed when assembled in the catheter. Once installed and if the outer tubular member is enlarged or inflated, the material of the outer tubular member is configured to produce an elastic recoil when the pressure is reduced or removed. The outer tubular member can be modified in a number of ways, but in the present examples is configured to be uniform throughout its length. In other examples, the outer tubular member can be configured to have different characteristics at different places along its length, for example based on durometer, thickness, the original or relaxed or recovered shape and/or diameter, material and thickness, and circumferential configuration. However, in the present examples, the response of the outer tubular member to inflation or enlargement pressure from an internal fluid is relatively uniform throughout the outer tubular member, and reaches a predetermined outer diameter, which is maintained even with higher pressures until pressure is removed and the outer tubular member deflate, retracts or returns to the structural support element. In this way, inflation or expansion of the outer tubular element allows disengagement of layers without overstretching the outer tubular element. The outer tubular element can be configured to have a non-linear pressure versus diameter relationship such that the diameter of the outer tubular element can increase with pressure up to a predetermined diameter, after which no further expansion occurs.

In the present examples, the catheter tubular member <NUM> and the outer tubular element <NUM> form nested tubular structures which are concentric, and together they define a cavity. Alternatively, they can be other than concentric, and they can have geometries other than cylindrical or circular cross-sections.

Lumenal structures and tubular structures, including the tubular catheter <NUM> can include support structures, for example medial or intermediate support structures, that can provide stiffness to the lumenal and tubular structures, and in the present examples, can provide selectable or variable adjustable stiffness or flexibility to the lumenal and tubular structures. The support structure can be placed the entire length or at a number of locations along the length of the lumenal and tubular structures, and in the present examples, the support structure is positioned adjacent the distal end of the catheter. In the present example, the support structure is a medial member that is placed between the lumenal and tubular structures. In one configuration of the support structure and the lumenal or tubular structure, the support structure can have an adjustable stiffness or modifiable stiffness configuration, which configuration can be affected by its geometry and how it is combined with the lumenal or tubular structure. In one configuration, the support structure is sandwiched or interposed between two structures, one or both of which may be adjustable relative to the support structure to change the stiffness of the assembly. In that or another configuration, the support structure has surfaces contacting one or more adjacent surfaces in the lumenal or tubular structure, which contact results in frictional forces if the support structure bends or otherwise changes its configuration. The frictional forces resist the configuration change, contributing at least in part to increased stiffness or decreased flexibility of the assembly, for example in the area of the support structure.

The support structure can take a number of configurations, and when placed over a lumenal or tubular structure, the support structure can also be a tubular support structure. The support structure takes the form of a tubular mesh, including a non-random mesh configuration. Such a configuration can be a tubular skeletal structure, a tubular framework, a tubular braid, a stent, for example such structures as medically implantable stents, and other structures. "Non-random" as used herein in the context of a structural support element is one that includes elements between the ends of the structural support element that were configured in a selected or controlled way. Elements making up the support structure can have a relatively high degree of interconnectedness, while still providing some degree of freedom of movement. In contrast to stents, however, the present support structure does not expand radially or extend longitudinally substantially once the catheter is assembled, other than what might occur on bending of the catheter and therefore the support structure. In the art of stents, a relatively low degree of interconnectedness would be termed an open cell configuration, and a relatively high degree of interconnectedness would be termed a closed cell configuration, or one tending more toward a closed cell configuration than an open cell configuration. Higher levels of interconnectedness in a tubular mesh, skeletal structure or framework may have more interconnections between elements than fewer interconnections. Interconnectedness contributes to an ability or inability of the support structure to move or change its geometry, with movement being easier with fewer interconnections, and more difficult with more interconnections.

In addition to the inherent characteristics of the support structure to allow or resist movement or changing geometry, interactions of the support structure with adjacent surfaces also affects resistance to movement or changing geometry. For example, larger surface areas of contact between the support structure and adjacent surfaces give rise to frictional forces to a greater extent resisting movement or geometry changes than smaller surface areas of contact. Support structures having larger numbers of components with surface areas that can contact the adjacent surfaces will exhibit higher resistance to geometry changes or movement than ones having smaller numbers of components, all other things being equal. Similarly, the surface characteristics of the components of support structures may also affect the resistance to geometry changes or movement. For example, surface textures or surface edges may contribute to higher frictional forces when in contact with adjacent surfaces that may resist geometry changes or movement. In one configuration, described more fully herein, a surface of the support structure facing an adjacent surface may be configured to include raised structures, for example protrusions or raised areas or outwardly extending structures (outwardly of the surface), or a combination of raised and recessed areas, which may contribute to higher frictional forces when in contact with the adjacent surface to help resist geometry changes or movement. For example, one or more facing surfaces of the support structure may include one or more raised structures extending outward from the facing surface a distance and having an element or surface area that may come into contact with the adjacent surface, and a raised structure may have a number of configurations such as pointed, extended or distributed, or other surface configurations that can contact the adjacent surface.

The catheter <NUM> includes an intermediate or medial member in the form of support structure <NUM> (<FIG>). In the present invention, the structural support member is monolithic. In the present example, the medial member is solely the support structure <NUM> in the form of at least one monolithic structure having a tubular shape made up of component elements such as spars, struts, or linear or curving limbs <NUM> interconnected with each other with open space <NUM> in between to form the support structure <NUM>, and the cross sections of <FIG> show cross sections of elements of the support structure <NUM> not to scale with the pitch of the coil <NUM>, with the understanding that the example of the support structure <NUM> is shown in and described in more detail with respect to <FIG>. The support structure is a three-dimensional configuration of spars, struts, or linear or curving limbs and intermediate cavities or openings whose configuration can be selectively adjusted or changed and releasably fixed in place as desired. The adjacent structures can be selectively coupled and decoupled to provide support or tracking as desired. In the present examples, three components are mechanically or frictionally decoupled to a greater or lesser extent to allow selective changing or adjustment of the configuration of the support structure, after which the three components can be re-coupled, for example mechanically and with increased surface areas of contact for frictional engagement.

In the present example, the support structure <NUM> is positioned intermediate the tubular member <NUM> and the outer tubular member <NUM>, in the cavity or annular void <NUM> formed between the inner tubular member and the outer tubular member <NUM>. Also in the present example, the support structure <NUM> extends substantially from the proximal end portion <NUM> of the outer tubular element <NUM> to the distal end portion <NUM>, and the configuration of the support structure is substantially consistent over the length thereof. However, the support structure can be configured to have different configurations as a function of axial position and/or circumferential position. The support structure <NUM> can be secured to the outer surface <NUM> of the inner tubular member <NUM>, for example by tacking, adhesive, or other means, such as at one or several endpoints at the proximal and distal ends of the support structure. Such securement may assist in assembly, and such securement can be eliminated prior to final assembly if desired. Conversely, flexibility of the distal portion of the catheter can be reduced as a function of securement of the structural support <NUM> to the inner tubular member <NUM>, axially and/or circumferentially. However, such reduction generally would not be reversible, and would decrease the baseline flexibility or increase the stiffness of the distal portion of the catheter and it could be difficult to increase the flexibility above the baseline or reduce the stiffness.

The components of the structural support <NUM>, such as the limbs <NUM>, can have a number of geometries. In the present example, each limb <NUM> has a substantially rectangular cross-section with a long axis parallel to the main axis of the catheter, and short axis perpendicular thereto. Having the long axis parallel increases the surface area of each limb that can contact an adjacent surface <NUM> of the inner tubular member and the inner surface <NUM> of the outer tubular member <NUM>. However, other geometries can be used. In the present example, each limb <NUM> of the support structure <NUM> is illustrated in <FIG> as being slightly spaced outward from the outer surface <NUM> of the inner tubular element <NUM>. The support structure can be configured to have a larger inside diameter in a relaxed state than an outside diameter of the outer surface <NUM>, which may then produce limited surface contact between the structural support <NUM> and the inner tubular member <NUM> when first assembled. Alternatively, the support structure can be configured to have an inside diameter in the relaxed state comparable or approximately the same as the outside diameter of the outer surface <NUM>, so that greater surface contact occurs between the structural support and the inner tubular member. In another alternative, the structural support <NUM> can be configured to have a smaller inside diameter in the relaxed state, for example through an inherent bias in the support structure, to have a higher surface area of contact with the inner tubular element in the relaxed state. Higher surface area of contact promotes stiffness, relative to lower surface area of contact between the support structure <NUM> and the inner tubular element <NUM>.

As illustrated in <FIG>, each limb <NUM> of the structural support <NUM> has a relatively defined set of corners or angular transitions <NUM> from one side to an adjacent side. The corners <NUM> are exaggerated in their sharpness, but the curvature of the transition between surfaces around a perimeter of a limb can affect frictional forces arising through contact between a limb and an adjacent surface, either with the outer surface <NUM> of the inner tubular element or with the inner surface <NUM> of the outer tubular element. The quantity or extent and the quality of the edge contact between limbs and their adjacent surfaces will contribute more or less to the stiffness or flexibility of the combination. All other things being equal, sharper or more angular transitions between surfaces produce higher frictional forces and increased stiffness or decreased flexibility. Therefore, a non-round limb profile on the structural support <NUM> can enhance the stiffness or reduce the flexibility of the distal portion of the catheter when the structural support contact the adjacent surfaces. Similarly, textures on surfaces of the support structure contacting adjacent surfaces of the tubular elements can also increase friction and stiffness or decreased flexibility. For example, a nitinol structural support <NUM> that is not electro-polished may enhance the stiffness or reduce the flexibility of the distal portion of the catheter as a result of surface contact with the adjacent surfaces of the inner and/or outer tubular elements.

The structural support element can be formed from a number of materials, including stainless steel, nitinol, polymeric materials, and other suitable materials. The structures can have cross sectional geometries that are angular, and may be finished or unfinished, etched or not, abraded or not (e.g., grit blasting), and for example with nitinol, electropolished or not. A structural support element such as a stent will be configured to have a structure, material, and characteristics of such a stent, such as stents used for medical implantation.

The illustrations of catheters in <FIG> show the catheter shaft extending straight, in what is considered a neutral configuration. In such a configuration, and as can be seen in <FIG>, the outer surface <NUM> extends axially substantially straight, and the adjacent surfaces of the limbs <NUM> of the support structure <NUM> extend substantially parallel to the outer surface. Relatively little frictional engagement occurs in such a configuration between the corners <NUM> and the outer surface <NUM> until such time as the catheter bends. When the catheter bends, the concave portion of the bend may have relatively higher contact and frictional engagement with the corners <NUM> of the adjacent limbs, for example at both corners of a limb, whereas in the convex portion of the bend, fewer of the corners <NUM> might contact the adjacent outer surface <NUM>.

The outer tubular element <NUM> is relatively more flexible than the inner tubular element <NUM>. In a configuration where the outer tubular element <NUM> is constricted, deflated, or otherwise pressed against the support structure <NUM>, the flexibility of the outer tubular element <NUM> allows the inner surface <NUM> to somewhat conform to the adjacent surface of the support structure. Specifically, the inner surface <NUM> extends over a limb <NUM> and curves or bends around adjacent corners <NUM> it contacts. Additionally, the outer tubular element <NUM> extends into the gaps or spaces <NUM> between adjacent limbs of the support structure. Consequently, possible movement of the limb <NUM> to the left as viewed in <FIG> (or outward toward the outer tubular element <NUM>) will tend to increase the frictional engagement between the corner <NUM> and the adjacent surface 208A, increasing the resistance to movement of the limb. Similar actions occur with other limbs and their adjacent surfaces of the outer tubular element, thereby accumulating forces resisting movement, and also increasing the stiffness or decreasing the flexibility of that portion of the catheter. Any increase in frictional engagement between limbs of the structural support <NUM> and adjacent surfaces of the outer tubular element <NUM> and/or inner tubular element <NUM> as a result of bending of the catheter will depend on the location and direction of the bending.

Resistance to bending or stiffness in the distal portion of the catheter can be reduced by reducing the amount of surface area of contact between one or more limbs <NUM> of the support structure <NUM> and one or more adjacent surfaces. The extent to which such contact can be reduced may depend on which surface or surfaces release or move out of contact with the support structure, and how many surfaces release or move out of contact. In one configuration, contact between the support structure and one or more adjacent surfaces may occur simply by moving the catheter, so that the adjacent surface <NUM> of the inner tubular structure <NUM> and/or the adjacent surface <NUM> of the outer tubular structure <NUM> slide or slip over the respective limb surface. In another configuration, including those illustrated herein, one or both of the adjacent surfaces of the inner tubular structure and the outer tubular structure become separated from the respective surface or surfaces of the support structure, thereby reducing or eliminating surface contact therebetween, and thereby reducing or eliminating the contributions of those surfaces resisting movement of the catheter.

In one example (<FIG>), the outer tubular element <NUM> can be released, moved away or separated from one or more adjacent surfaces of the support structure <NUM>. For example, fluid in the syringe <NUM> can be injected into the lumen <NUM> of the inflation port, and into the interior lumen of the catheter hub and the catheter. As the pressure in the interior of the catheter increases, fluid flows through the apertures <NUM> into the annular cavity <NUM> between the inner and outer tubular members. With the increase in pressure in the annular cavity, the outer tubular element expands or enlarges, and the interior walls <NUM> begin to move radially outward, and out of contact with, or mechanically and frictionally disengage from, the adjacent surfaces of the structural support <NUM>. The amount or extent of disengagement will be a function of the pressure, and the location or locations of the apertures <NUM>. In the example of an incompressible fluid and sufficient apertures <NUM> distributed along the cavity <NUM>, substantially all of the outer tubular element will release from the structural support <NUM>, both circumferentially and longitudinally. When all or any portion of the outer tubular element releases from adjacent surfaces of the limbs <NUM>, the flexibility of the catheter in the area of the outer tubular element commensurately increases and the stiffness commensurately decreases. Conversely, as more of the outer tubular element comes into contact with adjacent surfaces of the limbs <NUM>, the flexibility of the catheter in that area commensurately decreases and the stiffness commensurately increases.

In the example illustrated in <FIG> and other examples herein, variable stiffness is incorporated in a portion of a catheter. For example, when the outer tubular element is in a relaxed state, such as when excess fluid is removed from the annular cavity <NUM> and the catheter lumen, such as by withdrawing the plunger <NUM> on the syringe <NUM>, or by applying vacuum, that portion of the catheter has increased stiffness. Conversely, when the outer tubular element is expanded or inflated, such as by injection of fluid into the catheter lumen and the cavity <NUM>, the portion of the catheter has decreased stiffness. Therefore, in the examples herein using inflation and deflation, inflation and deflation can be used to affect stiffness or flexibility of the tubular element. In the present example, inflation increases flexibility. Similarly, a relaxed or natural state of the outer tubular element decreases flexibility and provides a stiffer construction. Additionally, the ability to increase or decrease stiffness or flexibility depends in part on the encapsulated or encased structural member <NUM>, which is independent of structures outside the outer tubular element or structures inside the dilator. The intermediate or medial structural support <NUM> is sandwiched between opposing continuous surfaces, one or both of which are movable, for example radially, such as where the outer tubular element <NUM> can expand radially outward relative to the structural support <NUM>.

In the present examples, the outer tubular element wall is movable with fluid pressure, outward with increasing fluid pressure, and inward with decreasing fluid pressure. Increasing the fluid pressure separates or widens the spacing between the facing walls of the outer tubular element and the inner tubular element, <NUM> and <NUM>, respectively. Decreasing the fluid pressure decreases the spacing between the facing walls of the outer tubular element and the inner tubular element, and eventually brings the outer tubular wall into contact with one or more limbs of the structural support <NUM>. As pressure is removed, the outer tubular element applies pressure to the structural support <NUM> squeezing the structural support between the outer and inner tubular elements, thereby changing the mechanical properties, stiffness and flexibility of that portion of the catheter. Where fluid is used to inflate the outer tubular element, it can be seen that the structural support <NUM> is in a closed fluid system, and in a cavity that is closed except for fluid communication with a source of fluid for fluid pressure. Having the support structure in an enclosed cavity in the catheter provides more predictability in the adjustability of the stiffness or flexibility of the catheter. Additionally, when the outer tubular element is formed from a material and configured on assembly to be resiliently biased in the direction of the structural support member, the resiliency of the outer tubular element helps to maintain the sandwich or application of pressure on the support structure when pressure is reduced or removed. Flexibility of the catheter can be adjusted by changing how the structural support element <NUM> is captured between the layers or concentric tubular elements of the outer tubular element <NUM> and inner tubular element <NUM>. Flexibility can be adjusted by manipulating fluid in the fluid system of the catheter lumen and the cavity <NUM>, and the fluid can be used to separate or increase the spacing between the concentric tubular elements. Similar effects can be achieved by reducing fluid pressure in the cavity, for example where the outer tubular element has a relaxed or unbiased configuration, making little or no contact with the support structure. By reducing pressure in the cavity <NUM>, the outer tubular element can be drawn into further contact with more surface area of the structural support, thereby increasing the surface area of contact and the rigidity or stiffness of that portion of the catheter. Alternatively in the examples illustrated herein where the outer tubular element is configured in its natural or relaxed state to be pressing against the structural support element, for example where in the relaxed state the outer tubular element has an inside diameter less than an outside diameter of the structural support element, the natural configuration of the assembly is to have the outer tubular element pressing against the structural support element absent increased fluid pressure in the cavity <NUM>. Additionally, the assembly can be configured so that fluid pressure reduces naturally if no active pressure is being applied to the syringe <NUM> by a user.

The catheter assembly is used so that the catheter <NUM> can be positioned in a desired position, for example within the vasculature, for example by using a guide device to guide the catheter into a desired location and position. For example, a guidewire (not shown) extends into the central lumen of the dilator and is guided into the appropriate vasculature, and the dilator and catheter with the outer tubular element inflated or enlarged is passed along the guidewire until positioned as desired. Once in position, the outer tubular element is deflated or reduced to fix the catheter geometry in position. The dilator <NUM> is then removed, and the remaining catheter with the adjustable flexibility element fixed remains in place for subsequent procedure. As shown in <FIG>, the dilator has been removed and the syringe <NUM> has been removed from the injection port <NUM>. The catheter is then ready to receive an intervention device, material or other component through the catheter hub <NUM>. When the procedure is complete, fluid is reintroduced into the lumen either with the intervention device in place or a dilator, a syringe attached to the injection port <NUM> and the outer tubular element <NUM> inflated to allow removal of the catheter <NUM>.

In an alternative embodiment of a catheter (<FIG>), a catheter 100A has an outer tubular element <NUM> enclosing a structural support <NUM>, and has the structures and functions described above with respect to the example of <FIG> except as discussed herein. In the present example, the catheter 100A includes a catheter shaft 102A identical to the catheter shaft <NUM> but for omitting the apertures <NUM>, but for the proximal portion of the catheter shaft extending further into the catheter hub 104A beyond the opening of the injection port <NUM>, and except for one or more inflation lumens <NUM>. The construction, geometry and dimensions of the exemplary catheter shaft 102A is substantially identical to that for catheter shaft <NUM> except that the catheter shaft includes the inflation lumen <NUM> defined by an interior wall <NUM> extending from the inflation lumen <NUM> in the catheter hub 104A to the proximal portion 202A of the outer tubular element <NUM>. The inflation lumen <NUM> has an interior lumen configured to permit the desired inflation of the outer tubular element, which allows the catheter to be used without a dilator for inflating or enlarging the outer tubular element <NUM>. The proximal portion 202A is sealed around the catheter shaft and the distal portion of the inflation lumen <NUM>, and withstands any fluid pressure expected within the lumen and the cavity <NUM> of the outer tubular element. The proximal portion of the catheter is supported by and sealed in the catheter hub 104A as would be done in a conventional catheter. The catheter is shown in <FIG> having the outer tubular element <NUM> deflated or in its collapsed configuration, pressing against the structural support <NUM>, sandwiching or pressing the structural support <NUM> between the outer and inner tubular elements. Injecting fluid into the lumen <NUM> and increasing the pressure in the fluid system from the injection port <NUM> through the lumen <NUM> and into the cavity <NUM> within the outer tubular element <NUM> enlarges or inflates the outer tubular element <NUM>, so that pressure is no longer applied to part or, in the illustrated example, all of the structural support element <NUM>, and to reduce the stiffness and increase the flexibility of that portion of the catheter (<FIG>).

The structural support element <NUM> in the present example includes a repeating pattern (<FIG>). <FIG> shows the structural support element <NUM> extending along and around the adjacent portion of the inner tubular element <NUM> from a first end <NUM> to a second end <NUM>. Because the structural support element is formed from a tubular mesh design, the first and second end portions are terminations of the pattern in between, and are not terminated with extra structures added to the end portions that are not present in the interior pattern.

The structural support element which has a repeating pattern can have the repeating pattern isolated into repeating groups or cells, while it is understood that a structural support element that does not have a recognizable repeating pattern will have a more complex structure that may not be amenable to identification of repeating groups or cells. The present support structure <NUM> (<FIG>) includes a cell <NUM>, which in the present example repeats circumferentially to provide six cells, and in the example illustrated in <FIG> repeats longitudinally to provide <NUM> cells plus a terminal boundary structure, which equates to approximately a half cell, depending on how the support structure is produced. Because the support structure is to be used in a catheter in the present example, it is desirable to exclude any free-ended limbs <NUM>. In the illustrated examples, each limb terminates at both ends at respective ones or more other limbs.

In the structural support element <NUM>, each cell <NUM> includes a first strut <NUM>, which in the present configuration is a longitudinally-extending strut that extends longitudinally of the tubular support structure, and parallel to the axis of the inner tubular member <NUM>. As shown in <FIG>, the support structure and the tubular inner element <NUM> are concentric and coaxial over the length of the structural support element <NUM>. The cell <NUM> also includes parts of adjacent longitudinal struts 312A and 312B. The longitudinal struts <NUM> extend parallel to each other, and are distributed circumferentially about the tubular support structure. In the present configuration, the longitudinal strut <NUM> is offset both circumferentially and axially relative to the adjacent longitudinal struts 312A and 312B.

Each longitudinal strut includes a first end <NUM> and a second end <NUM>. Each of the first and second ends are joined or coupled to a pair of serpentine struts extending from opposite sides of the longitudinal strut. The first end <NUM> is joined or coupled to a first serpentine strut <NUM> on one side of the longitudinal strut, and to a second serpentine strut <NUM> on an opposite side of the longitudinal strut from the first serpentine strut <NUM>. The first end <NUM> of the longitudinal strut forms a node at which three struts join or converge. Similarly, the second end <NUM> of the longitudinal strut <NUM> is joined or coupled to a third serpentine strut <NUM> on one side of the longitudinal strut, the same side as the first serpentine strut <NUM>, and a fourth serpentine strut <NUM> on an opposite side of the longitudinal strut from the first and third serpentine struts <NUM> and <NUM>. The first and second serpentine struts extend away from the longitudinal strut <NUM> and toward the third and fourth serpentine struts, which also extend away from the longitudinal strut <NUM> and toward the first and second serpentine struts, respectively.

The opposite ends of the second and fourth serpentine struts are joined or coupled at their respective ends to respective longitudinal struts 312B and 312A, the ends of which form their respective nodes. The second serpentine strut <NUM> is joined or coupled to a second end <NUM> of the adjacent longitudinal strut 312B, and the fourth serpentine strut <NUM> is joined or coupled to a first end <NUM> of the adjacent longitudinal strut 312A. A fifth serpentine strut <NUM> is coupled to the second end of the longitudinal strut 312B, and to the first end of a longitudinal strut <NUM>'. A sixth serpentine strut <NUM> is coupled to the first end <NUM> of the longitudinal strut 312A, and to the second end of the longitudinal strut <NUM>'. Therefore, in the present configuration, a cell <NUM> includes two longitudinal struts, as the outline is drawn formed from a full longitudinal strut and two halves, and the cell includes four serpentine struts formed from two complete serpentine struts and the sums of four partial serpentine struts. Each cell includes four nodes, and each node is the junction of three struts. As can be seen in the illustrated example, all struts are coupled or joined to at least two other struts, and the longitudinal struts are coupled to four serpentine struts, and each serpentine strut is coupled to two longitudinal struts. This arrangement provides a moderate degree of interconnectivity, allows free-form radial expansion and contraction (before the support structure is combined with any other structure), and allows free-form longitudinal expansion and contraction. The amount of expansion and contraction is determined in part by the starting angle of an angle <NUM> when the support structure is first formed. For example, when the support structure is first formed with a relatively small angle <NUM>, greater radial expansion is permitted than radial contraction because the starting angle is small. Conversely, when the first support structure is first formed with a relatively large angle, the remaining radial expansion is less, and the available radial contraction is greater than for a smaller starting angle <NUM>.

The structural support member <NUM> at any given transverse cross-section is configured to have at least two struts in the cross-section, and in many designs will have at least three struts, as three points define a plane. In the exemplary structural support member <NUM>, a transverse cross-section will intersect at least six struts <NUM> (<FIG>). The six longitudinal struts <NUM> are distributed substantially uniformly about the circular support member <NUM>. Such a transverse cross-section can be visualized in <FIG> at either of the lateral sides (as visualized in <FIG>) of the cell <NUM>. However, at other transverse cross-sections axially along the structural support member, additional struts will be visible, for example <NUM> when the transverse cross-section intersects a node such as <NUM>, and for example <NUM> when the transverse cross-section intersects intermediate portions of the serpentine struts. Additionally as would be seen in a transverse cross-section, the longitudinal struts are different size from the serpentine struts, and have a larger cross-sectional area. There are more of the smaller struts than there are larger struts, and in the present example twice as many smaller struts than larger struts in a given cell. As can also be seen in <FIG>, all of the struts are connected, and in the present example interlinked or interconnected so that each strut is connected to at least two other struts. Also as can be seen in <FIG> and <FIG>, no single longitudinal strut extends the entire length of the structural support member without a bend or transition to another longitudinal strut. Additionally, in the illustrated example, no single element of the structural support member, in the present example no single strut, extend the entire length of the structural support member without a bend or transition to another element/strut.

In the present examples of support structures, the support structures are formed from solid tubular elements having a constant wall thickness (thereby providing a substantially constant thickness for all of the struts) and laser cut in a manner similar to the formation of stents to form the tubular mesh illustrated in <FIG> or in <FIG>. In the example of the support structure <NUM>, the angle <NUM> formed during formation of the support structure may be a small acute angle, for example as small as several degrees (<NUM>-<NUM>°), or a large acute angle, for example as large as <NUM>-<NUM>°. Larger angles (obtuse) are possible as well and provide structural support, but do not provide the same structural support once incorporated into a catheter assembly as does the configuration of the support structure <NUM> having an acute angle <NUM> when initially formed.

In the configuration of the structural support produced using the pattern shown in <FIG>, the angle <NUM> is selected to be approximately <NUM>°. In the final assembled configuration of the structural support shown in <FIG>, the angle represented by <NUM> is approximately <NUM>° after expanding the support structure.

The support structure <NUM> in the present examples is formed from a solid tubular element having a wall thickness of <NUM> inch (<NUM>). The structural support <NUM> is then formed by laser cutting, in a manner similar to that used for forming stents, so that all of the struts have a thickness <NUM> equal to the starting wall thickness of the solid tubular element. In the present example, the width <NUM> of the longitudinal strut is approximately <NUM> inch (<NUM>), which is approximately twice as much as the width <NUM> of the serpentine strut, which is approximately <NUM> inch (<NUM>), in the present example, and greater than the thickness, while the thickness is approximately <NUM> inch (<NUM>), which is greater than the width <NUM> of the serpentine struts. Consequently, the longitudinal struts resist bending more than the serpentine struts. The geometry of the cells, the wall thickness of the struts, the width of the struts, and the angle <NUM> contribute to determining the stiffness, flexibility or resistance to bending of the support structure, in free-form separated or apart from the catheter assembly. Such stiffness, flexibility or resistance to bending of the support structure is carried into the assembly in the catheter, and will exhibit similar characteristics in the catheter assembly. The thicknesses and widths of the struts can be selected to be between approximately <NUM> inch and <NUM> inch (<NUM> and <NUM>). Additionally, the stiffness, flexibility or resistance to bending of the catheter assembly in the area of the support structure <NUM> is determined in part by the stiffness, flexibility or resistance to bending of the support structure per se, as well as the engagement and interaction of the components of the assembly with each other, including surface areas of contact between the structural support and adjacent surfaces. When such surface areas of contact are reduced or removed, such as by inflation or enlargement of the outer tubular element, the various contributions to stiffness, flexibility or resistance to bending are reduced but the inherent stiffness, flexibility or resistance to bending of the support structure per se remains. Therefore, the design or pattern of the support structure determines not only the stiffness, flexibility or resistance to bending of the support structure per se, but also the contribution to the stiffness, flexibility or resistance to bending of the catheter based on the interaction of the support structure with adjacent components. In the configuration described and illustrated in <FIG>, the structural support member has cells with the surfaces facing the outer tubular member wherein each cell has a facing surface area of about <NUM>. 00075824in. , (<NUM> inch = <NUM>,<NUM>) and likewise with the surface of each cell facing the inner tubular member. Alternatively, as described herein, the outer and/or inner surface of at least one limb may include discontinuities or other configurations that form structures extending outward from a respective surface for engaging a respective adjacent structure to change the relative contribution to the stiffness, flexibility or resistance to bending of the assembly at least in the area of the outward extending structures.

The effect of interaction between the support structure <NUM> and any adjacent components is affected in part by the radial position of the support structure. With a flexible inner tubular member <NUM> having an inside radius from the center R1 and an outside radius from the center of R2, the support structure <NUM> will be on or closely adjacent the outside surface <NUM> of the inner tubular element. In the present examples, the inside diameter of the support structure <NUM> is represented by radius from the center R3 which is substantially equal to the radius R2, so that the support structure contacts the outside surface <NUM> of the inner tubular member. The outside radius R4 of the support structure <NUM> is then determined by the wall thickness of the support structure. Additionally, the inside diameter of the outer tubular member <NUM> is represented by the radius from the center R5, and the outside diameter is represented by the radius R6, both of which are given while the outside tubular element is enlarged or expanded or inflated. The maximum inside diameter of the outer tubular element in a relaxed or collapsed state corresponds to substantially R4, namely the outside diameter of the support structure, and the maximum outside diameter of the outer tubular element in the relaxed or collapsed state is substantially R4 plus the wall thickness of the outer tubular element. The minimum inside diameter of the outer tubular element when in the collapsed or uninflated state will depend on the flexibility of the material of the outer tubular element, and the relative surface area of the open areas between struts that will allow the material of the outer tubular element to extend between the struts. The radius values of the structural support <NUM> are set forth in the Table I below (<NUM> inch = <NUM>,<NUM>):.

Resistance to bending in tubular structures such as catheters generally occurs on an outer surface of the tubular structure. As illustrated in <FIG>, the support structure and the outer tubular element are positioned at the outer reaches of the assembly, and the mechanism in the form of the structural support that is used in the present examples to provide variable stiffness is located in the area of or on an outside surface of the inner tubular member, for example where the mechanical properties of the structural support can have a strong effect. As illustrated in <FIG>, the structural support is in the area of approximately <NUM>% of the maximum outer diameter of the catheter. Therefore, the effect of the structural support on the flexibility or stiffness of the portion of the catheter at which it is placed by having it applied at outer areas of the catheter relative to the center axis, for example between <NUM>% and <NUM>% of the overall outside diameter of that portion of the catheter. Additionally, the function of surface area of contact, such as between the structural support and the outer surface <NUM> of the inner tubular member <NUM>, and/or between the structural support <NUM> and the outer tubular element <NUM>, is improved by positioning the structural support element at a higher radial position than a lower radial position, because the surface area available increases with the square of the radius. Therefore, placing the structural support element outside the inner tubular element <NUM> enhances the contribution of the surface area of contact and frictional resistance developed between the structural support and any adjacent surfaces.

<FIG> illustrates a portion of the structural support <NUM> in an approximately neutral state, for example after assembly onto an inner tubular element and formed into a catheter assembly, ready for use though after some residual movement as not all of the longitudinal struts <NUM> are precisely parallel and the serpentine struts, labeled generically as <NUM>, have adjusted accordingly. The longitudinal struts are not in compression or tension and are substantially regularly spaced from each other, and the serpentine struts <NUM> also are not in tension or compression, but such condition will depend on the initial magnitude of the angle <NUM> (<FIG>) when the support structure was initially produced and its condition when positioned on the inner tubular element.

The struts are free to bend relative to each other with minimal applied force when in an unconstrained state, such as when the outer tubular element <NUM> is enlarged or inflated, because of their relatively small thicknesses and widths. When the structural member <NUM> is bent in its unconstrained state based on an applied bending load, the struts rearrange themselves to accommodate the changed mechanical condition, as schematically represented in <FIG>. In <FIG>, the longitudinal and serpentine struts have rearranged themselves to the lowest energy configuration available with the imposed curvature, preserving the length and interconnection of the struts. In the concave portion of the support structure, the longitudinal struts are brought closer together, which approach is limited by the serpentine struts which are put in tension, and the angle <NUM> becomes more acute. The acute angle between adjacent longitudinal and serpentine struts helps in the force transfer between longitudinal struts as they rearrange themselves. On the convex side of the bend, the longitudinal struts tend to separate in some areas, subject to the restrictions of the attached serpentine struts and nearby longitudinal struts.

When the support structure is incorporated into catheters as described herein, rearrangement of the struts occurs with relatively low force required when the structural support element is unconstrained, or in a tracking mode, such as when the outer tubular element is enlarged, expanded or separated from the structural support element. When the structural support is constrained, such as when the catheter is in a support mode, such as when the outer tubular element is collapsed or pressing against the structural support element, rearrangement of the struts either does not occur or occurs at a much higher applied force compared to that in the unconstrained condition. The relatively high degree of interconnectedness between the struts allows for flexibility of the support structure to bend, but the points of interconnection between struts limit the degrees of freedom in which the struts may rearrange themselves. These factors can be changed by increasing or decreasing the number of nodes per unit length, increasing or decreasing the number of struts at a node, separate the struts into groups of struts and have one group of struts connected at more nodes and another group of struts connected at fewer nodes, and similar variations.

In one exemplary catheter configuration, the length of the catheter distally from the catheter hub is approximately <NUM> inches or approximately <NUM>, and the length of the variable flexible portion with the support structure <NUM> and the outer tubular element <NUM> is approximately <NUM> inches or <NUM>. The portion of the catheter shaft that can include a variable flexible portion can be greater or lesser than this example.

The structural support element can take a number of configurations, especially considering the number of stent configurations that have been developed. As one example of an alternative structural support element (<FIG>), a support element <NUM> includes a cell <NUM> forming the basis of a repeating pattern, extending longitudinally and circumferentially. The cell <NUM> forms part of a helical pattern where the cell includes a rectangular frame <NUM> having four sides and defining an opening <NUM>. Each cell is separated from a longitudinally adjacent cell by a laser cut separation, forming the helically wound ribbon. The openings <NUM> receive flexible portions of the outer tubular element when collapsed or pressing against the structural support element, thereby helping to limit or restrict movement by mechanical engagement or frictional resistance. In an alternative configuration, the cells <NUM> can take a non-helical configuration, for example with two or more circumferentially adjacent cells connected together as shown in <FIG>, or connected at one or more nodes (not shown) providing greater flexibility between circumferentially adjacent cells. Longitudinally adjacent cells can also be connected at one or more nodes (not shown) as a function of the desired flexibility in the constrained and unconstrained states.

In another example of a structural support element (<FIG>), structural support element <NUM> is formed from a helically cut tube or helically wound ribbon. The structural support element includes a longitudinally extending projection <NUM> in one part of the winding extending into a complementary longitudinally extending cavity for <NUM> in an adjacent winding. Windows or apertures (not shown) may be provided interior to edge surfaces of windings of the helix to provide frictional engagement surfaces with the outer tubular element.

Adjustment of the flexibility or stiffness of a portion of the catheter <NUM>/100A/100B is used to allow the catheter to track a path in a vessel, for example over a guidewire or other guide device, and alternately to provide structural support within the vessel when desired, for example to support passage of an intervention device or the like. In a tracking mode, the inner tubular member is flexible for easy track ability, and kink resistant to minimize damage during use and to provide suitable force transmission along the long axis of the catheter for pushing and advancing through the vessel. In the tracking mode when the structural support element is flexible and not constrained, the struts of the structural support element are free to bend, adjust and realign and move freely, subject to the positioning of adjacent struts. The struts align to the lowest energy configuration possible. When the catheter is positioned as desired, the structural support element is pressed between the outer tubular element and the inner tubular element, thereby becoming constrained and the struts are no longer free to move relative to each other or relative to the adjacent surfaces without a significant amount of force. In the constrained or supportive configuration, the structural support resists bending of the catheter, reducing its flexibility and increasing its stiffness. The configuration is analogous to a clutch, whereby disengaging the outer tubular element from the structural support element and further away from the inner tubular element allows free motion of the structural support element and the struts therein, as may be limited by the bending limitations in the structural support element per se. Applying a vacuum or negative pressure or removing inflation fluid from inside the outer tubular element engages the clutch structure, mechanically linking the outer tubular element, the structural support element, and the inner tubular element, rendering the catheter structure in the area of the structural support element less flexible, and better able to support devices to be passed through the catheter lumen.

In operation, a fully assembled catheter assembly <NUM>/100A/100B is placed in a tracking configuration by injecting fluid into the cavity <NUM> within the outer tubular element <NUM>, or otherwise increasing the pressure in the cavity. The tubular element is expanded or enlarged so that the outer tubular element releases or mechanically disengages from the structural support element <NUM>, thereby reducing or eliminating the frictional resistance to bending with the structural support element <NUM>. The pressure is maintained within the cavity <NUM> or the outer tubular element is otherwise maintained in the inflated or enlarged configuration. The catheter assembly is introduced into a body lumen, for example through a trocar, introducer, or other structure and moved through vasculature <NUM> (<FIG>), for example with the assistance of a guidewire <NUM>. As the guidewire <NUM> is moved to a new position, as illustrated in <FIG>, the catheter <NUM>/100A/100B is advanced over the guidewire in the catheter tracking mode. When the catheter has reached the desired location, such as illustrated in <FIG>, the catheter assembly can be placed in the support mode by withdrawing fluid or applying negative pressure to the lumen in fluid communication with the cavity <NUM>, or by allowing the recoil or memory of the inflated outer tubular element <NUM> to return toward its relaxed state, contracting into mechanical engagement or contact with the structural support element, and applying pressure to the structural support element and clamping the structural support element between the outer and inner tubular elements. The flexible wall of the outer tubular element can also bulge into the openings <NUM> between struts of the structural support element <NUM> (and possibly contacting the outer surface <NUM> of the inner tubular element), thereby increasing the mechanical engagement or frictional force resisting movement of the structural member relative to adjacent surfaces, and thereby increasing the stiffness and support of the catheter assembly. The reinforcement, for example the coil <NUM> in the inner tubular element, resists deformation of the inner tubular member, for example due to any compressive loading from the outer tubular member, either alone or in combination with any bending load. In the examples herein, the inner tubular element is substantially incompressible for the pressure loads that would be experienced under normal operating conditions. The guidewire can then be withdrawn and replaced by an interventional or other device <NUM> (<FIG>) to carry out the desired procedure, which may also have its own structural support element and flexible outer tubular element for adjustable support. The catheter assembly can then be withdrawn after returning the catheter assembly to a tracking mode, which may include reinserting a dilator, and then withdrawn in accordance with conventional methods.

Before the catheter is introduced into a lumen, and as the catheter is transiting a body lumen such as depicted in <FIG>, the catheter can be in the tracking or flexible mode in the area of the structural support member. In that configuration, the catheter takes a number of shapes configurations, for example after manufacture the catheter can be straight, including the variable stiffness region in the area of the structural support member, and while the catheter is transiting the body lumen, the catheter including the variable stiffness region will take shape configurations conforming to the body lumen. In those shape configurations, while the structural support member is released or free to adjust its shape, the structural support member can have a number of configurations. One configuration is illustrated in <FIG>, in which the struts have rearranged themselves to the lowest-energy configuration imposed on it by the wall of the inner tubular member. However, when part or all of the structural support member takes on a fixed shape configuration, for example by being sandwiched, pressed or squeezed between the inner and outer tubular elements, the structural support member and the surrounding catheter structure maintains the fixed shape configuration, which is also the configuration of the surrounding lumen wall. As a result, the variable shape portion of the catheter adopts the shape of the surrounding lumen and does not substantially change that shape until released. For example, once the catheter has been positioned as desired while in the tracking, flexible or released mode, such as in <FIG>, the variable shaped portion of the catheter takes on a second shape configuration different than previous shape configurations while the catheter was transiting the lumen. When the structural support element is sandwiched, laminated or fixed in the second shape configuration, the variable shaped portion of the catheter applies little if any force <NUM> or pressure on the lumen wall as a result of the transition from tracking or flexible mode to the support or fixed mode in the second shape configuration. If the catheter were theoretically able to be lifted from the body lumen without having to transit the lumen passageway again, it would be seen that the catheter maintains the shape of the lumen it has adopted as though it has shape memory. In other words, the variable shaped portion of the catheter in going from the tracking or flexible mode to the support or fixed mode applies little if any force on the adjacent lumen wall. Such results can be illustrated with a three-point bending flexural test with the variable shaped portion of the catheter arranged in a second shape configuration, and the force measured before and after fixing or pressing the structural support member would not be very different. For example, the force difference could be approximately <NUM>%-<NUM>%, and could be in the range of <NUM>-<NUM>%, and with the configuration of the structural support member <NUM> illustrated in <FIG>, can be less than <NUM>% (force after fixing or pressing the structural support member minus the force before fixing or pressing the structural support member divided by the force before).

A difference between the tracking mode and the support mode can be illustrated by comparing forces used to deflect a straight catheter assembly at the area of the variable stiffness. With a substantially straight catheter, a middle portion or other selected portion of the variable stiffness area can be bent for an inch or other selected distance by having a normal force applied and measuring the force required to move the selected distance. The force is measured when the catheter is in the tracking mode or a more flexible state, and when the catheter is in the support mode or a more rigid or stiff and less flexible state. In one example where the outer tubular element is completely spaced apart from the underlying structural support member and the catheter bent <NUM> inch, the measured force is about <NUM> pounds force (<NUM> inch = <NUM>,<NUM> and <NUM> pounds force = <NUM>. The catheter is then returned to a straight configuration, and placed in the support mode or with the outer tubular member pressing against the structural support member and bent <NUM> inch. The measured force is about <NUM> pounds force (<NUM>,<NUM> N). A Bend Force Ratio of the Support Mode Force divided by the Tracking Mode Force in this example is approximately <NUM>. Ratios greater than one provide a desirable catheter configuration, and ratios of approximately <NUM> and above are more desirable.

The catheter assembly can be assembled in a number of ways, including in part conventional methods for assembling a catheter. In one method (<FIG>) a mandrel assembly <NUM> is used, similar to conventional assembly apparatus. The mandrel assembly is selected to have a mandrel <NUM> to provide the desired size catheter with the selected internal diameter. In one process, the inner tubular member <NUM> is assembled by sliding a polytetrafluoroethylene liner over the mandrel <NUM> and applying a braid or coil reinforcement over the liner. An extrusion is applied over the braid or coil reinforcement, after which the layers are securely laminated inside a removable heat shrink tube to merge all of the components together into the inner tubular member <NUM>. One or more holes or apertures <NUM> are formed in the laminate, extending completely through, in the area where the structural support element will be positioned. The structural support element is formed for example by focused laser cutting a monolithic metal tube according to the desired pattern. The structural support element <NUM> is placed over the tubular member <NUM> and positioned as desired. It may be tack bonded at its distal and proximal ends to secure it to the inner tubular member for assembly.

The mandrel with the inner tubular member assembly is then inserted into a tubular loading tool <NUM> (<FIG>) with the structural support element within a barrel <NUM> of the loading tool. The barrel <NUM> can include multiple parts, for example to be separated for inserting the mandrel and inner tubular member. The loading tool includes an O-ring seal <NUM> at a distal portion for providing an airtight seal around the inner tubular member and mandrel. The loading tool <NUM> also includes a pressurization port <NUM> proximal of the seal <NUM> for providing pressurized air or other pressurized fluid around the outside of the inner tubular element extending toward the distal end of the tubular element. The barrel <NUM> includes an annular lip or ridge <NUM> at a distal end for receiving one end of an inflatable tubular element <NUM> to be sealed around the barrel with an O-ring seal or other seal element <NUM>. The parts of the barrel can be separated and the proximal portion placed over the proximal portion of the mandrel and inner tubular element, and the distal portion placed over the structural support element and the two parts brought together and sealed. The inflatable tubular element <NUM> is applied to the distal portion of the barrel and sealed with the seal <NUM>. As illustrated in <FIG>, the relaxed state of the inflatable tubular element <NUM> is less than the outer diameter of the structural support element <NUM>, and <FIG> shows the relationship schematically and greater spacing between the inflatable tubular element and the mandrel <NUM> for ease of illustration. The opposite end of the inflatable tubular element is closed, for example with a closure knot, clip, ligation or the like. Inflation pressure is then applied at the inflation port <NUM> to inflate the inflatable member <NUM>, as illustrated in <FIG>, for example approximately <NUM> psi (<NUM> kPa) and possibly as much as <NUM>-<NUM> psi (<NUM>-<NUM> kPa). The applied pressure inflates or expands the inflatable member diametrically. When the inflatable member is stabilized, the mandrel and inner tubular member assembly are slid inside the outer tubular element <NUM> (<FIG>) so that the inflatable member is suitably positioned over the structural support member and an underlying assembly. Pressure is then removed from the inflatable member, for example through the pressurization port, and the inflatable member collapses around the structural support member and the adjacent portion of the inner tubular member (<FIG>). The assembly is then removed from the loading tool <NUM> (<FIG>) and the inflatable member trimmed to the desired length around the structural support member. The outer tubular element <NUM> is then bonded at <NUM> and <NUM> the inner tubular element, and further trimmed if necessary (<FIG>). The mandrel <NUM> is then replaced by a smaller mandrel <NUM>, and the tip of the catheter is re-flowed to reduce its diameter to that of the smaller mandrel, to provide the desired interference fit with an appropriate dilator tip. The mandrel <NUM> is then removed, and the tubular assembly bonded or otherwise secured at its proximal end to a proximal hub, for example catheter hub <NUM> (<FIG>).

With selection of suitable material for the outer tubular element <NUM>, resilience or pressure memory can be incorporated into the outer tubular member on assembly, for example by using a relaxed tubular member having an inside diameter in the relaxed condition less than the structural support member and possibly even less than the inner tubular element. Inflation of the inflatable material allows easy assembly of the outer tubular element onto the catheter assembly to provide the desired resilience so that the outer tubular member can apply an appropriate pressure to the structural support element.

Other structures and assemblies can be used in addition to or as alternatives to those described herein for controllably changing the support provided in a lumenal assembly, for example a catheter assembly such as those described herein. In the examples shown in <FIG>, structures with the same reference numbers have the same or similar structures and functions as described herein. In one exemplary alternative, described in conjunction with <FIG>, an assembly for controllably varying a stiffness of a catheter assembly 100A includes a medial member that is an assembly having a structural support assembly 300A. The structural support assembly 300A includes an inner structural support member <NUM> extending about an adjacent portion of the catheter wall <NUM> in a manner similar to the structural support <NUM> described herein. The inner structural support member <NUM> can be configured to have the structure and function of any of the structural support members described herein, and in the present invention extends circumferentially completely around the adjacent portion of the catheter lumen.

In the illustrated configuration in <FIG>, the structural support assembly 300A includes an outer structural support member <NUM> laterally outward of the inner structural support member <NUM>. In the present example, the outer structural support member <NUM> extends circumferentially around the adjacent portion of the catheter lumen, outboard of the inner structural support member, and interior to the adjacent surface <NUM> of the inflation lumen <NUM>. The outer structural support member <NUM> can have a structure and function identical to that of the inner structural support member <NUM>, or it can have a structure and/or function different than that of the inner structural member. The outer structural support member <NUM> can be configured to have the structure and function of any of the structural support members described herein.

The structural support assembly 300A may also include, but need not include, a secondary material such as a sleeve <NUM>. The sleeve in the exemplary configuration extends and is positioned between the inner and outer structural support members, coaxial therewith, but may be inside or outside both structural support members. In the present example, the sleeve material is a flexible material, and may include surface characteristics allowing free sliding movement of the adjacent structural support members, or providing frictional engagement to reduce free sliding movement of the adjacent structural support members relative to the sleeve material. The sleeve may be a continuous tubular element, may be formed with a porous configuration, may be a random or non-random mesh material, or may have other configurations as desired.

The configurations illustrated in <FIG> show the inflation lumen in an expanded or inflated configuration, providing a reduced measure of structural support to the assembly. When inflation fluid is removed or allowed to escape or evacuate the interior of the inflation lumen <NUM>, spacing between the inner and outer structural support elements and the sleeve and the adjacent surfaces of the inflation lumen and the catheter lumen decreases. With sufficient removal or outflow of inflation fluid, the inflation lumen <NUM> may contact the adjacent surfaces of the outer structural support member <NUM>. Additionally, interior surfaces of the outer structural support member <NUM> may contact the outer surface of the sleeve <NUM>, and the inner surface of the sleeve <NUM> may contact the adjacent outer surfaces of the inner structural support member <NUM>. Interior surfaces of the inner structural support member may contact the adjacent surface <NUM> of the catheter lumen, and the assembly may provide additional stiffening, rigidity or structural support for the catheter assembly when in the configuration illustrated in <FIG>.

In another configuration of a catheter assembly having controllably variable stiffness or rigidity in at least a portion of the catheter assembly, a portion of a catheter lumen 102A (<FIG>) may be enclosed in or surrounded by an inflation lumen or inflation balloon <NUM>. The inflation lumen <NUM> may enclose only the adjacent portion of the catheter lumen, or may enclose the portion of the catheter lumen along with other structures and/or materials, including possible structures and/or materials between the inflation lumen <NUM> and the catheter lumen 102A. In the present illustrated example, the inflation lumen <NUM> surrounds the catheter lumen 102A without any intermediate structural material between the inflation lumen <NUM> and the catheter lumen 102A. in the present example, the inflation lumen <NUM> is formed from a relatively non-compliant material. When the inflation lumen <NUM> deflates or contracts inwardly around the catheter lumen 102A, for example to contact the catheter lumen, and for example with removal of inflation fluid or otherwise similar to methods described herein, one or more portions of the inflation lumen <NUM> form one or more pleats <NUM> (<FIG>). One or more pleats on the inflation lumen <NUM> provides structural support to the assembly. In the illustrated example, a pleat forms on the interior of a curved surface of the assembly, or on a concave surface of the assembly. In the configuration illustrated in <FIG>, the inflation lumen <NUM> has a deflated configuration where the lumen makes substantial contact with adjacent surfaces of the catheter lumen.

In another exemplary alternative illustrated in <FIG>, the assembly is identical to or substantially identical to that described with respect to <FIG> but the medial member is omitting one or the other of the outer or inner structural support <NUM> (as illustrated) or <NUM>, respectively. In an alternative configuration not illustrated, the structural support assembly can omit the inner structural support <NUM> and instead include the sleeve <NUM> and the outer structural support <NUM>. Other configurations of a medial member of an assembly having a structural support member and a secondary material can be used.

In a further exemplary alternative illustrated in <FIG>, an assembly 100A includes an inflation lumen or balloon 200A incorporating with it a structural support material 300C. As illustrated, the structural support material 300C is embedded in or formed in part of the interior of the material of the inflation lumen 200A. In other configurations, the structural support material 300C may be formed on either or both of the interior or exterior surfaces of the inflation lumen 200A. In this example, the structural support material 300C may be any of the structural support elements described herein.

In any of the assemblies of the type described herein, and for any of the support members/structural supports or support structures described herein, the support structure can be made more or less amenable to easy movement within the assembly for example when an outer tubular element is in a relaxed state or otherwise pressing the support structure against the outer surface of the inner tubular structure <NUM>, or otherwise when the support structure is contacting an outer surface of the inner tubular structure. To provide for easier movement, for example, steps can be taken to change the structural configuration of the support structure, for example by decreasing the density of the limbs and/or their interconnection. In one example, easier movement can be accomplished by electro-polishing of a nytinol support structure.

In addition to other ways described herein, configurations of a support structure can also be used to contribute to higher frictional forces when in contact with one or more adjacent surfaces, including configurations described previously. In one example, a support structure may be configured so that one or more surfaces on the support structure facing respective adjacent structures on another part of the lumenal assembly have surface geometries that are other than smooth, or that are discontinuous, nonuniform or otherwise changed to be other than smooth. For example, the support structure has surfaces facing one or more of the adjacent structures, for example facing the tubular member <NUM> outer surface or facing the tubular element <NUM> inner surface, and such facing surfaces will have surface geometries.

One or more of the surface geometries are other than smooth, have discontinuities or non-uniformities. For example, a support structure may have an element such as a limb, or a plurality of limbs, that may be configured with a facing surface geometry that is non-smooth, for example to include one or more raised structures extending outwardly from one or more facing surfaces a desired distance so that the raised structure can contact a respective surface adjacent the facing surface for generating higher frictional force when they contact. In examples of the present assemblies, the adjacent surfaces can be adjacent surfaces on either or both of the outer tubular element or the inner tubular structure, or on intermediate or associated structures such as those described with respect to <FIG>.

An example of a support structure configuration that can contribute to higher frictional forces in the assembly for resisting movement or geometry changes with raised structures is a support structure <NUM> (<FIG>). In the present example, the support structure <NUM> is described as having raised structures on an interior facing surface to face an adjacent outside surface on the inner tubular structure <NUM>, but it should be understood that raised structures can instead or additionally be placed on a facing surface facing an adjacent inside surface of the outer tubular element in the configuration shown in <FIG>. The present description has the raised structures for the support structure <NUM> on the inside surface of the support structure, but identical raised structures or different raised structures can be on the outside surface of the support structure.

The support structure <NUM> is similar to the support structure <NUM> in that it includes cells of limbs in the form of primary longitudinal struts <NUM> and secondary longitudinal struts <NUM> interconnected by serpentine struts <NUM>, and the cells generally repeat. Other configurations are possible, and non-smooth surface geometries can be incorporated in any of the support structures as described herein or similar thereto. In the present configuration of the support structure <NUM>, the primary longitudinal strut is less than twice the length of the secondary longitudinal strut but greater than <NUM>½ times the length, as can be seen by the relative number of, substantially equally spaced in the illustrated example, raised structures on each of the longitudinal struts. Each primary longitudinal strut at each end is coupled to respective pairs of oppositely arranged serpentine struts <NUM>. Each serpentine strut in the present example includes an enlarged portion <NUM> for providing a support for a raised structure. However, it is understood that fewer than all or that any number of struts can include raised structures, in any desired distribution, density, geometry and configuration, as desired, while the illustration shows all struts with raised structures, equally spaced, uniformly distributed, and with identical geometries.

In the example of the support structure <NUM> illustrated in <FIG>, each strut includes a raised structure <NUM>. In the present example, each of the raised structures <NUM> are identical to the others, and are relatively evenly distributed across the longitudinal struts and across the enlarged portions <NUM> of the serpentine struts <NUM>. In alternative configurations, the raised structures can be different from each other, and can be distributed unevenly or randomly, omitted from one or more limbs, or otherwise. One or more of the raised structures can be created according to a defined process at defined locations, according to a defined process at random locations, or according to a random process at random locations. In the present example, each of the raised structures <NUM> are identical to the extent that manufacturing or formation processes allow any predictable precision in the formation of the raised structures <NUM> or the support structure <NUM> having such raised structures. However, it is understood that conventional manufacturing processes may produce raised structures with variations in location on a strut, geometry and orientation, and the visual appearance of the geometry may be different from a drawing characterizing the structure or from which the structure was created by currently available forming techniques.

The raised structures can take a number of configurations. In the present example, they are illustrated as being substantially round having a relatively constant and consistent heights relative to each other and relative to the underlying strut. However, it should be understood that the actual resulting raised structures may not be identical in height or in cross-sectional configuration as between one another, or from one manufacturing lot to another. The raised structures are illustrated in the present example as being consistent in cross-section and also in height for simplicity. The geometries of the actual raised structures may vary. In one example of a configuration for the raised structures, the raised structure can have a height <NUM> less than a height or thickness <NUM> of the strut. If the raised structure <NUM> were configured to be round, the raised structure could have a diameter or equivalent dimension <NUM>, which may be less than a width <NUM> of the strut from which the raised structure <NUM> extends. As illustrated, the ratio of the height of the raised structure is less than <NUM>%, and the ratio of the diameter is also less than <NUM>% of the width of the strut. These ratios may vary from about <NUM>% to about <NUM>%, respectively, with resulting variations in the frictional forces developed in the assembly for resisting movement or geometry changes in the assembly.

For a given assembly of a support structure and adjacent surfaces, the raised structures can decrease the surface area of contact between the struts and the adjacent surfaces, such as between the struts and the outer surface of the inner tubular element, relative to such an assembly without the raised structures. Decreasing the surface area of contact, such as by adding the raised structures, increases the force per unit area for a given configuration of the assembly in the area of the support structure, which produces an increase in the traction or frictional engagement between the support structure and the adjacent outer surface of the inner tubular element. For example, relative to comparable structures with the support structure <NUM> as illustrated in <FIG> and <FIG>, a support structure <NUM> having raised structures <NUM> will apply a higher force per unit area for each raised structure for a given outer tubular element <NUM>. The higher force per unit area can occur when the outer tubular element is in its relaxed state or when the outer tubular element is contracted, such as when fluid is removed or pressure within the outer tubular element is reduced, for example so that the outer tubular element applies pressure to the structural support <NUM> squeezing it between the outer and inner tubular elements, and thereby changing the mechanical properties, stiffness and flexibility of that portion of the assembly. In the present example, the raised structures engage an outer surface on the inner tubular element <NUM>. During the engagement, for example as illustrated in <FIG>, the pressure applied to the struts <NUM> forces the raised structures <NUM> into the plastic surface of the inner tubular element <NUM>. The raised structures engage the material creating frictional engagement, thereby changing the mechanical properties, stiffness or flexibility of that portion of the assembly. For a given pressure applied by the outer tubular element <NUM>, the raised structures <NUM> produce a higher force per unit area against the outer surface of the inner tubular element <NUM>.

Raised structures can be created on surfaces of the support structure according to a pattern, or randomly. They can be created as raised structures per se, or they can be produced by removing adjacent material, or they can be generated as a combination of raised and depressed areas or cavities. Raised structures can be formed in a number of ways. In one process, raised structures can be photochemically milled during the formation of a stent or stent-like structure, such as any of the support structures of the type described herein, and the support structure formed accordingly. For example, raised structures can be formed on a planar stent pattern and then rolled to form the final support structure, with the raised structures on the interior surface, exterior surface, or possibly both depending on the desired method of formation. In another process of forming raised structures on a support structure, the support structure can be created as desired, and then covered with a photomask or photoresist, which can then be used to create a random or non-keyed pattern of raised structures.

In another example of lumenal or tubular structures, including any of those described herein, a surface of an inner tubular structure facing an adjacent surface of a support structure such as any of those described herein can be formed other than entirely smooth, for example with surface roughness different than the surface configuration of other parts of the inner tubular structure, surface dimples, surface cavities or other surface discontinuities. The facing surface of the inner tubular structure can be other than entirely smooth to increase the frictional engagement between the surface and the adjacent support structure.

In any of the lumenal members described herein, including for example the catheter assembly <NUM>, and 100A, the lumenal members may include one or more medical devices associated with the assembly, for example adjacent the distal portion of the assembly. In one example (<FIG>), a catheter assembly 100B is identical to the catheter assembly 100A, and has the same structures and functions as described with respect to catheter 100A, for example as described in conjunction with <FIG>, with the addition of one or more medical devices. In the illustrated example, medical device <NUM> is positioned on an external surface of the catheter shaft 102A, for example as illustrated over and contacting the seam or seal between the catheter shaft and the inflation lumen. Alternatively, the medical device <NUM> can be mounted on or supported by a portion of the catheter shaft (not shown) extending distally of the seam or seal. The medical device can be configured to extend around the catheter shaft, or may be configured to extend over an arcuate portion of the shaft. The medical device can extend longitudinally and radially as desired for the intended purpose of the device.

In a further configuration of the assembly 100B is illustrated in <FIG>, the medical device <NUM> alternatively or additionally can be supported adjacent a distal portion of the catheter shaft 102A, as illustrated at <NUM>'. The characteristics and configuration of the medical device <NUM>' can be the same as or different from the medical device located distally of the inflation lumen.

The medical device <NUM>/<NUM>' can be any number of devices. The medical device can be any one or more of a diagnostic or therapy device, including but not limited a device for angioplasty, ablation, angiography, occlusion, radiation, visualization, or a stent.

Claim 1:
A flexible lumenal assembly (<NUM>, 100A) configured for transiting a body lumen comprising a flexible lumenal member (<NUM>, 102A, <NUM>) extending longitudinally and a medial member having a structural support member (<NUM>, <NUM>, <NUM>, <NUM>) that has a facing surface facing at least one surface on either of the flexible lumenal member (<NUM>, 102A, <NUM>) or an outer member (<NUM>), wherein
the facing surface has a non-smooth surface geometry;
the medial member extends outside a portion of the flexible lumenal member (<NUM>, 102A, <NUM>) and inside the outer member (<NUM>) extending over the medial member wherein the outer member (<NUM>) is configured to selectively apply pressure to the medial member;
the structural support member (<NUM>, <NUM>, <NUM>, <NUM>) is monolithic; and
the structural support member (<NUM>, <NUM>, <NUM>, <NUM>) extends along and circumferentially completely around an adjacent portion of the flexible lumenal member (<NUM>, 102A, <NUM>);
characterized in that
the structural support member (<NUM>, <NUM>, <NUM>, <NUM>) is a tubular mesh that includes a non-random tubular mesh.