Patent Description:
In general, there are numerous circumstances where a thin, elongate device must be inserted into a lengthy, narrow and often curved or branched tubular member in order to effect navigation and related repair, insertion or other complex activities associated with the device. With particular regard to minimally-invasive medical procedures, there is a need for flexible and steerable guide wires (also referred to herein as guide wire assemblies), stylets, catheters and related devices that generally have to be maneuvered through tortuous body lumens through one or more of pushing, pulling and tangential rotation, and more particularly do so by transferring such movements initiated at the proximal end of the device as accurately as possible to the distal end. While conventional guide wire assemblies with a steerable tip are known in the art as a way to achieve some degree of maneuverability, all have some form of drawback.

For example, some steerable devices have a shapeable tip at the distal end that can be bent to a desired angle before insertion. While the angle enables the operator to maneuver the device into side arteries or related branches in a body lumen, its relatively fixed nature means that once inserted, the tip angle cannot be changed, thereby limiting its subsequent mobility. To overcome the problems associated with such a fixed configuration, other devices have been developed to provide for a measure of remotely controlled steerability, such as by hand manipulation and related user actuation at the proximal end of the device. In one such example as shown by <CIT>, the operator pulls a tension wire relative to the guide wire, so that the tip will bend in an amount that varies with the pulling force. In another example, <CIT> uses a hollow guide wire with a series of slots made in the tubular member wall at the place where more flexibility is desired. Relatedly, <CIT> shows that numerous pairs of slots are cut into the body to make it more flexible in bending while maintaining adequate torsional stiffness, while <CIT> shows numerous radial slots-all with the same cut depth-formed near the tip distal end, with the distance between the slits increasing farther away from the distal tip. In yet another example, <CIT> varies the depth of the slots over the length, with the deepest slots near the distal end, while keeping the axial distance between the slots identical, possibly in an attempt to vary the rigidity of the remaining tubular member material with slot depth. In still another example, <CIT> shows a device with an alternating pattern of opposing slots defined by a small linear offset; while such a configuration provides enhanced flexibility upon bending, the steerability is compromised, while manufacturing costs tend to be high. More significantly, fracture of the fragile wall near any slot causes complete failure of the device.

Helical slots have been proposed in an attempt to promote flexibility; however, it is difficult to achieve a reliable, repeatable one-to-one correspondence between the initiated rotation at the proximal end and the responsive rotation at the distal end. By way of example, <CIT> shows a single helical cut formed in the tubular member. The helix has an invariable pitch, and upon pulling the control wire, the gaps in the outer sheath all close at the same time, which in turn requires the device to remain straight regardless of whether the gaps are opened or closed. Such construction means that the only thing be varied is the rigidity of the device, so while a conventional helical cut can provide the selective flexibility needed to provide ample degrees of steerability, it has proven to be a vexing problem to use such cuts to keep a good reliable one to one rotational movement between proximal and distal ends.

In addition to steerability concerns, manufacturability issues must be addressed, especially where the device is meant for endoluminal use. In particular, as can be seen from the foregoing examples, normally laser cutting or similar techniques are used to form a pattern of slots into the wall of a tubular member. Such techniques (which often result in localized heating during the cutting process) tend to weaken the remaining material around the slot. This problem manifests itself during bending operations where elevated stress tends to be concentrated in a very localized region, leading to an increased risk of breakage in such region. The present Applicant believes that there is not enough remaining unharmed base material to absorb these stresses while the device is introduced and maneuvered into a tortuous path such as a body lumen. To overcome this elevated local stress problem, other approaches, such as that of <CIT> have been developed, where the member is produced by forming a strip of material into an elongate helical coil. Additional locks are used to improve the torsional stability, and while such an approach helps avoid or reduce the stress problems associated with traditional slot formation, the high costs render such approaches prohibitive, as does the inability to simultaneously control bending along with the increased torsional stability.

According to one aspect of the present disclosure, a steerable device is disclosed.

The device includes a tubular sheath and an elongate control element disposed within and attached to the tubular sheath. The sheath has a proximal end, a distal end and one or more reconfigurable sections disposed between these two ends. Within at least the reconfigurable section, one or more helical slots may be formed through the sheath wall. In addition, the one or more slots may include a variable slot width, a constant or variable slot pitch or both. By having variations in one or both of the slot width and pitch, an operator-induced axial force applied to the elongate control element can be used to cause the variation in the slot to produce at least one of a change of the flexibility, rotatability or pushability, rotation of the distal section and a distal end bending within the tubular sheath.

According to another aspect of the present disclosure, a medical device for use in a body lumen is disclosed. The medical device includes an elastic bias section disposed proximal relative to a tubular sheath and elongate control element that cooperate with one another to provide a steerable section where device bending and rotation may be implemented. The elastic bias section can be used by a physician or related operator to vary the shape of the tubular sheath through changes in length that result from an axial force imparted to the elongate control element. In one form, the medical device is a guide wire assembly such that the elongate control element is a wire such that the elastic bias section forms a tool through which the operator may manipulate the wire. Additional portions of the device may include an intermediate section and an anchoring section to selectively provide secure contact between the device and a body lumen interior wall.

According to another aspect of the present disclosure, a method of using a steerable device is disclosed. The method includes positioning the device within a tubular path and moving the device within the tubular path such that when a distal end (such as the tip of a reconfigurable section that has at least one of bendability and rotatability attributes) of the device reaches a bend, bifurcation or other change in direction within the tubular path, the distal end may be reconfigured in order to be steerably moved through the bent, bifurcated or changed region. The device includes a tubular sheath defining a proximal end, a distal end and at least one reconfigurable section disposed between the proximal and distal ends. The tubular sheath also includes one or more helical slots formed through the sheath wall. The one or more slots are constructed so that they possess either or both of variable slot width and a constant or variable slot pitch along the length of the reconfigurable section at least while the tubular sheath is in a substantially undeformed shape. An elongate control element is cooperative with the tubular sheath such that upon application of an axial force to the elongate control element, one or both of the variable slot width and the constant or variable slot pitch to produce at least one of a change of the flexibility, rotatability or pushability, rotation of the distal section and a distal end bending within the tubular sheath.

The following detailed description of the present disclosure can be best understood when read in conjunction with the following drawings:.

Embodiments disclosed herein include a device that can be inserted into and navigated through complex tortuous hollow bodies for various applications, such as body lumens for medical procedures. Such devices may be used in conjunction with other endoluminal devices, including those disclosed in <CIT> and <CIT>, as well as <CIT> and <CIT>.

The device disclosed herein may also be used for non-medical procedures, such as those associated with exploration, completion and maintenance of oil, gas and water wells, fluid and gas transport systems. Devices according to the present disclosure exhibit greater reliability in part because their construction avoids many of the fracture and related breakage problems associated with traditional devices, while also improving on ease of manufacture.

As will be discussed in more detail herein, the device of the present disclosure provides increases in both flexibility and steerability while preserving the structural rigidity necessary to ensure the reliable, repeatable correlation between controlling movement at one elongate end of the device and rotational movement at the opposing end of such device. Several main features as discussed in more detail below may be used singly or in conjunction with one another to contribute to simultaneously meeting these competing objectives. These features include the fact that (<NUM>) axially-induced tension causes bending in a slotted helical tube that has a variable slot width, (<NUM>) locking members and hinges may be used to prevent undesirable torque loss in slotted helical tube situations where a rotation initiated at one end is meant to be transferred one-to-one to the other end, and (<NUM>) axially-induced tension causes torque in a slotted helical tube in what is referred to as self-torque-tip (STT) so that a device section rotates tangentially around its own length axis in response to an applied length change in a helical wall due to such tension. Within the present context, this last feature pertains to a helical section that rotates tangentially around its own length axis by applying a length change in the helical wall. STT depends on various structural considerations of the helix, including pitch angle of the helix and sheath wall thickness.

Embodiments disclosed herein can take advantage of these features to meet the long-felt needs mentioned above. As will be discussed in more detail below, in one form, a device made up of at least a tubular sheath and a control element centrally disposed along the axial dimension of the sheath cooperate with one another such that the control element can impart a preload onto the sheath in such a way to close tangential gaps in locking members that are formed between adjacent wall sections of the sheath. By closing these gaps, a controllable reduction in sheath floppiness can be realized, which in turn results in an improved tangential stiffness and a higher degree pushability during device insertion into a body lumen or other tubular member. In another form, interrupted helical slots create hinges in the wall of the sheath. As with the locking members mentioned above, such hinges can improve the tangential one-to-one movement that is needed to achieve repeatable rotational stability. In yet another form, the helical slots may have a variable width along their length. Because the width is not everywhere the same, an axial deviation of adjacent sections will form upon application of a force on the sheath through the control element as gaps within the slot will close at different times commensurate with the degree of width variability. In a related form, this bending effect experienced by the variable-width slots also works for helical slot forms with hinged interruptions; for example, where the hinges are situated on the convex side of a tubular sheath, an applied force tends to close the gap on the circumferentially opposing side. With such a configuration, bending may take place in one plane but also in several planes, depending of the position and shape of the slots and their corresponding hinges, interlocking members or the like.

In yet another form, the tangential self-rotation effect-where minor tangential rotation relative to a neighbor coil (also referred to herein as wall section) upon closure or opening of the slot occurs when tension is applied to a helical sheath-may be used advantageously to eliminate the need to have an operator apply tangential rotation at the device proximal end. In this way, mere axial movement of an elongate control element can cause the distal section to start rotating even while the majority of the sheath has yet to start rotating. The fact that only a short section of the wall is rotating reduces the total friction with the inner wall of the lumen in which the device is placed. This in comparison with a conventional device, which has to be rotated over its entire length. Both the accuracy and reduced friction associated with rotational movement thereby improves, especially for endoluminal and other very thin devices that are designed to navigate tortuous paths. As will become apparent from the present disclosure, this latter self-rotation effect can be combined with the locking members or other rotation-inhibition devices as discussed above in order to limit excessive deformation, as well as to control the bending effect caused by variable slot width.

Lastly, in yet another form, the spacing or pitch between axially adjacent portions of the slot at common circumferential positions on the sheath may be varied in order to create a gradual change in stiffness of the device. With such construction, smaller pitch (i.e., more closely-spaced slot portion) sections tend to exhibit more bendability than larger pitch (i.e., farther-spaced slot portion) sections.

Referring first to <FIG>, a reconfigurable section of a tubular sheath <NUM> with a slot (also referred to herein as a kerf) <NUM> formed in a wall <NUM> thereof is shown, where the helical nature of the slot <NUM> resembles the familiar "barber-pole" pattern. As shown with particularity in <FIG>, the sheath <NUM> is in an axially stretched or elongated form, or in its as-cut state with a large slot width where in this latter form the sheath <NUM> can be used as a compression spring a the proximal end of a guide wire assembly. <FIG> shows the sheath <NUM> in its as-cut dimension, and <FIG> shows the sheath <NUM> bent to define an arcuate path that deviates from the linear shape of <FIG>. Both the pitch P (i.e., the axial dimension spacing between adjacent slot sections at the same circumferential wall position) and the width W of the slot <NUM> remain constant over the length of the slot <NUM> while the sheath <NUM> is in its nominal (i.e., undeformed) axially-aligned configuration of <FIG>. Likewise, upon bending as shown in <FIG>, relative closures <NUM>C and gaps <NUM>G form between adjacent wall <NUM> sections; these closures <NUM>C and gaps <NUM>G correspond to reductions and increases in the width W of the slot <NUM> that are present on the respective concave and convex sides of the sheath <NUM>. As shown, the closures <NUM>C become smaller upon increased bending and finally become zero when the walls <NUM> of adjacent sections between adjacent slots <NUM> touch each other. Contrarily, on the convex side, the gaps <NUM>G will increase to be wider than the nominal width W.

Referring next to <FIG>, a reconfigurable section of a tubular sheath <NUM> according to an embodiment of the present disclosure also has a continuous slot <NUM> arranged in a helical shape between equally continuous wall <NUM> where adjacent sections of the wall <NUM> define the corresponding section of the slot <NUM>. Within the present context, these adjacent wall sections <NUM> that define the slot <NUM> between them are also referred to as coil sections commensurate with the helical nature of the tubular sheath <NUM> construction. In one preferred embodiment, the sheath <NUM> makes up a portion of an endoluminal device <NUM> (such as a guide wire assembly), and is shown presently in an axially stretched or elongated form (<FIG>) that allows the sheath <NUM> to be used as a compression spring when loaded in its axial direction A. When used as such a device, a notional slot <NUM> width of about <NUM> microns or even smaller can be achieved when using nitinol tubing with an outer diameter of <NUM> microns and wall thickness of about <NUM> microns where such dimensions are often useful in endoluminal procedures). As is shown with particularity in <FIG>, and as will be discussed in more detail below, by the present disclosure, the as-cut slot <NUM> width W (of which the aforementioned <NUM> microns is an exemplary, rather than limiting, value) can be varied between a minimal width W<NUM> to a maximum width W<NUM>. Sheaths <NUM> according to the present disclosure may be made of metal, polymer, ceramics, metal alloys, alloys with shape memory, linear elastic and/or superelastic behavior (such as nitinol, NiTiNb or related ternary alloys) and all combinations thereof. It is within the scope of the present disclosure that any material or any combination of materials can be used in any of the embodiments discussed herein.

<FIG> shows with particularity the sheath <NUM> in its bent state such as that associated with an axial contraction of the sheath <NUM> by an internal actuating tension wire (not presently shown). Significantly, upon such bending, there is no substantial variation in the width W of the various slot <NUM> sections along the length of the sheath <NUM>. As such, the closures <NUM>C and gaps <NUM>G that were present in the bent sheath <NUM> of the prior art of <FIG> are replaced by converging adjacent wall <NUM> sections such that no open slots remain. In this shape of sheath <NUM>, the borders of the adjacent wall <NUM> sections are in contact with one another, which in turn causes the sheath <NUM> to possess a relatively rigid state compared to that of <FIG>.

Referring next to <FIG>, the tailoring of the width W of the slots <NUM> of the sheath <NUM> of <FIG> can be achieved by using the cutting pattern or template where a generally two-dimensional simulation of the width variations along the length of the helical slot <NUM> that is formed in wall <NUM> of sheath <NUM> can be better visualized. Within the present context, the width W of the slot <NUM> that is cut into the wall <NUM> of the sheath <NUM> is made to vary in a tangential direction around the circumference of the sheath <NUM>. In one form, there is only a single cut formed throughout the entirety of the steerable, flexible section of the sheath <NUM>. When an operator pulls at the proximal end of a central actuation wire (such as that depicted in <FIG> below) while he holds the outer tube in place, the slots in the distal section will tend to close. As the slot width varies along the circumference of the slotted cross section, the edges of the smallest slot width in the tube will close earlier than the opposing edges, where the slot is wider. At that moment the device is still straight, but if the central actuation wire is pulled out further, the remaining asymmetrical gap will tend to close and the tube will start bending.

Referring with particularity to <FIG>, slot <NUM> is shown with one edge defining the width W in vertical direction and the repeating cutting length L in horizontal direction. Slot <NUM> width W varies alternating between W<NUM> and W<NUM>. When both the rotation speed of the sheath <NUM> and the axial feed are constant, the length of the cut going in one loop from top to top corresponds to the repeating length L. Within the present context, a loop corresponds to the helical length or section of a slot <NUM> from one circumferential location on a sheath <NUM> to the next portion of the sheath <NUM> at the same circumferential location upon traversal along the slot <NUM>. The value of length L depends on pitch P and diameter D, as explained in conjunction with <FIG> below in conjunction with <FIG>. If length L is exactly enough to reach bottom point B for every loop, all points corresponding to the maximum width W<NUM> will be in a straight line that is parallel to the center axis of the sheath <NUM>. In this case all loops have equal lengths L. The resulting sheath <NUM> resembles that depicted in <FIG>.

Referring with particularity to <FIG>, where the amplitude of the width W of slot <NUM> varies again between W<NUM> and W<NUM> but the feed of the sheath <NUM> is variable, the length L of the cut varies over the length of the sheath <NUM>, thus creating different lengths L<NUM>, L<NUM>, L<NUM> and so on. This results in different respective pitch values P<NUM>, P<NUM>, P<NUM> and so on. The resulting sheath <NUM> resembles that depicted in <FIG>. By varying the feed of the sheath <NUM> and the rotation speed, it is also possible to not only vary the pitch P over the length, but also varying the locations of the points where the maximum width W<NUM> is located in a manner similar to that associated with the discussion of <FIG> for locations Y, Y<NUM> and Y<NUM>. Further additional sheath <NUM> parameters may be varied in order to optimize a design. For example, the variations in slot <NUM> width need not only be restricted to an alternating pattern of two values for W<NUM> and W<NUM>; there may be more widths W used to provide even more flexibility and steering behaviors. Moreover, additional cuts can be tailored to improve only the flexibility, while leaving the steerability the same.

In providing the slot <NUM> with a variable width, such as by various known techniques including laser cutting, mechanical cutting with fine blades, electrostatic discharge machining (EDM), chemical milling, photo-etching, ablation or the like. Likewise, variations in shapes of the slot <NUM> may also be formed, such as through using several cuts, using a zigzag cut with variable amplitude, using another offset cut, using a variable cutting energy, using a variable spot size, or winding the helical shape from a strip with variable width. In one form, one end of the sheath <NUM> may be held in a chuck (not shown) that rotates, while the laser (not shown) is positioned close to and above the rotating sheath <NUM> surface. Either the sheath <NUM> moves in axial direction under the laser or the laser moves in axial direction relative to the sheath <NUM> end In either variant, it is that the cutting pattern varies over the length of the helical slot <NUM> being formed. In one variation, the spot size of the laser varies, dependant on the angle of rotation of the sheath <NUM> around its central length axis. The spot size-and thus the amount of removed material-can be varied in order to create a slot <NUM> that alternates in widths between W<NUM> and W<NUM> for every full rotation of the sheath <NUM>. If the spot size cannot be enlarged fast enough or big enough, the alternative would be to cut a second time over the same slot <NUM>, with some offset at all places where slot <NUM> enlargement is needed. Alternatively, the slotting speed may be alternately lowered in order to remove more material locally, while a zigzag movement be used to enlarge the slot <NUM> as well.

Referring again to <FIG>, the sheath <NUM> with a cutting pattern as shown in <FIG> is axially compressed by the tension in the control element <NUM>, which causes bending of the sheath <NUM>. On the concave side of the bent sheath <NUM>, the width W<NUM> of slot <NUM> becomes smaller upon increased bending and finally becomes zero when the wall <NUM> sections on opposing lateral sides of the slot <NUM> touch each other. Simultaneously on the convex side, the width W<NUM> of slot <NUM> will also become smaller and decreases further after contact between adjacent wall <NUM> sections is attained by the reductions in width W<NUM> on the concave side. In fact, a calculation of the total bending angle of sheath <NUM> can be made as follows. By way of example, a given sheath <NUM> diameter of D that is bent over an imaginary mandrel with diameter D<NUM> until the sheath <NUM> is bent over a total angle of <NUM> degrees. In that final position, all gaps in the concave side are closed, so the length of the convex side is larger than the concave side with a difference of nΔW where n is the number of slots. Then the following equations can be used to calculate n. Total length of convex side over <NUM> degrees is L<NUM> = (π(D<NUM>+D))/<NUM>. Total length of concave side is L<NUM> = (πD<NUM>)/<NUM>. L<NUM> = L<NUM> + nΔW. This gives n = πD/(2ΔW). For example if ΔW=<NUM> microns and D = <NUM> microns, it follows that n = <NUM> slots <NUM> for <NUM> degrees of bending. If the mandrel has a diameter D<NUM> = <NUM>, the pitch P is then calculated as follows. P = L<NUM>/n = (πD<NUM>)/2n = 5π/<NUM> = <NUM>. Other sizes can be calculated easily from these formulas. For example, if D = <NUM> microns and ΔW = <NUM> microns, then D<NUM> = 2nP/π = <NUM> P. Thus, if P is assumed to be <NUM> and n is <NUM>, then D<NUM> = <NUM>. The bending angle is <NUM> degrees for <NUM> slots, so in this case the bending angle with all slots closed is then (<NUM>/<NUM>)<NUM> = <NUM> degrees. It is clear that if ΔW =W<NUM> - W<NUM> = <NUM> microns and if the pitch P = <NUM>, a sheath <NUM> as shown in <FIG> with D = <NUM> micron and n = <NUM> can bend over <NUM> degrees when all gaps are closed. The diameter D<NUM> will then be <NUM>, while the slots <NUM> and sheath <NUM> will resemble <FIG>.

Referring next to <FIG>, an endoluminal device <NUM> according to another embodiment of the present disclosure is shown. In this configuration, a length of sheath <NUM> surrounds a control wire (also referred to herein as elongate control element) <NUM> that is attached to the distal tip or end <NUM>D and that extends through the hollow core of the sheath to the proximal end <NUM>P, where it can be actuated by some external tool or by a bias spring, such as that of aforementioned <CIT> and <CIT>. Materials making up the control wire <NUM> may include polymers (including polymers that exhibit one or both of high strength and high modulus of elasticity), as well as metal and metal with enhanced radio-opacity (including magnetic resonance imaging) features. It will be appreciated by those skilled in the art that the control wire <NUM> may be made from a different material than the sheath <NUM>, and that movement of the control wire <NUM> may be achieved through a remotely controlled actuator taking advantage of one or more of a shape memory effect, hydraulic pressure, electric or magnetic signal, electromotor, direct, with the assistance of a mechanical gear box, as well as combinations thereof.

The sheath <NUM> and control element <NUM> are fixedly attached to one another such that there is equilibrium between a tensile force in the control element <NUM> and an axial compression force in the wall <NUM> of the sheath <NUM>. The tensile force is sufficient to bias the endoluminal device <NUM> in a deformed first shape that can be changed by variation of the tensile force. In changing the tensile force, the endoluminal device <NUM> assumes a second shape different from the deformed first shape. In the present context, the endoluminal device <NUM> is considered to exist in a deformed shape when the inherent bias force causes the sheath <NUM> to assume a shape different than would exhibit in a state of rest if no such force were imposed. For example, with a tension force existing between the control element or wire <NUM> and the sheath <NUM>, a bend in one or both ends of the device <NUM> produced by this tension would cause a (preferably elastic) deviation from a normally straight or linear shape along the sheath <NUM> axial dimension. In such case, the bent shape is considered deformed. Similarly, radial or related outward expansion of the sheath <NUM> caused by an axial compression of the portion intermediate the connected ends would amount to a deformed shape. Contrarily, a device <NUM> is considered to exist in an undeformed shape when any inherent bias forces have been overcome such that the device <NUM> assumes a shape commensurate with no net forces acting upon it, such as that associated with the linear (i.e., straight) sheath <NUM> of <FIG>.

In another form (not shown) the control element <NUM> may be configured to have a tubular shape similar to sheath <NUM> in order to allow internal access through its lumen for additional component use. In either its solid (i.e., control wire <NUM>) or hollow construction, such a control element <NUM> is sized to allow its longitudinal (or axial) placement within the sheath <NUM>. In the case of where the control element <NUM> is itself of hollow construction, an operator may use additional devices that can be moved through or around the inner lumen of such control element <NUM>.

As with the embodiment of <FIG>, a single helical line is shown in <FIG>, extending from a starting cut or hole that is closer to the proximal end <NUM>P of the sheath <NUM> all the way until an end hole or cut near the distal end <NUM>D that culminates in tip <NUM>. The pitch P may be made to vary over the axial dimension A such that farther away from the tip <NUM> the pitch P<NUM> is larger than the pitch P<NUM> that is closer to the tip <NUM>. With such construction, the flexibility increases closer to the tip <NUM>, while closer to the proximal end <NUM>P the bending properties of the sheath <NUM> are relatively similar to that of a non-slotted portion of the sheath <NUM>. This variation in pitch P permits a gradual transition in flexibility in order to avoid undesired stress concentrations that otherwise may lead to failures. As the sheath <NUM> becomes compressed when a tension force is applied to the control wire <NUM>, the sections of the wall <NUM> with smallest pitch P<NUM> will start bending first, and upon increasing axial force from the control wire <NUM>, the amount of the sheath <NUM> that assumes a bent (rather than linear or straight) profile will increase until the most proximal section of slot <NUM> is finally closed that coincides with the maximum bending angle of sheath <NUM> being reached.

In yet another embodiment, the variable slot width features of <FIG> may be combined with the variable pitch feature of <FIG>. In that way, the slot <NUM> is in the shape of a helix with variable pitch P along the length of the sheath <NUM> and a variable slot width W along both (a) the helix defined by the slot <NUM> and (b) the sheath <NUM> that contains the helix. In both of the embodiments of <FIG> and <FIG>, the control element <NUM> may also be used with a preload in order to minimize the free tangential movement between adjacent sections of the helix that is formed in the sheath <NUM>. As will be discussed in more detail below, there is another way to minimize the free tangential movement between adjacent helix sections through the use of locking members.

Referring next to <FIG>, details of the sheath <NUM> of the separate embodiments of <FIG> and <FIG> are shown. Referring with particularity to <FIG>, the shape of the slot <NUM> is enlarged in order to better see how the width W of slot <NUM> varies from one side (as shown, the top) to the other side (as shown, the bottom) of the sheath <NUM>, changing from narrower width W<NUM> to wider width W<NUM>. The length of a slot, starting at point B and running over <NUM> degrees until it reaches point Y, is determined by the diameter D and the pitch P of sheath <NUM>. If both the pitch P and diameter D are constant, all locations where the wider width W<NUM> is present can be made to extend on a straight line along a common circumferential location of sheath <NUM>. Referring with particularity to <FIG>, a cross section of the sheath <NUM> with the top points T and bottom points B, as well as overlap points Y, Y<NUM> and Y<NUM>. If all points Y correspond with B, the curvature of the sheath <NUM> upon actuation by the control wire <NUM> will be in one plane, with the concave side below. However, it is also possible to form the cuts in slot <NUM> in such a way that the widest portion of the loop of the slot starting at B does not end in Y, but in Y<NUM>, and the widest portion of the next loop thereafter ends in Y<NUM>, and so on. In such case, the actuated sheath <NUM> can obtain bending or curvature in more than one plane, such as that associated with a pig-tail shape. This helps promote a self-anchoring effect by providing a more complete contact between the sheath <NUM> and the wall of the lumen into which it is placed.

Referring next to <FIG>, a two-dimensional representation of an unraveled tubular sheath <NUM> that can be used as part of a steerable device, medical device or guide wire assembly according to one or more of the embodiments of the present disclosure is shown with three distinct regions the last two of which (regions <NUM> and <NUM>) show how the reconfigurable section of the sheath <NUM> may be made up of two or more reconfigurable sections. The unraveled view is used to better show how the diameter D and entire circumference πD of the sheath <NUM> cooperate to provide one or more slot <NUM> patterns. Region <NUM> defines a proximal zone with a helical cut that is wide enough to make this section work as a compression spring; this zone generally corresponds to the proximal end <NUM>P of sheath <NUM>. Region <NUM> is an example of slots <NUM> configured as a double helix, in this case a continuous helical slot <NUM>C and an interrupted helical slot <NUM>I in-between; this region may be used to increase the flexibility of device <NUM>, as well as to create bending upon tension. In particular, the discontinuous nature of the interrupted helical slot <NUM>I acts to provide hinges <NUM> bridges or related landed areas (as will be discussed in more detail with <FIG> below) that are created where the cuts that make up the slots <NUM> are interrupted. This has the effect of creating an asymmetrical rigidity when the hinges <NUM> are located on a common circumferential spot along the length of the sheath <NUM>, such as when aligned in a row. Although only two helices are shown in the figure, more than two may be used as well, depending on the desired device <NUM> behavior. Region <NUM> shows the steerable distal end <NUM>D that may exhibit bending behavior upon applied tensile force such as that of a guide wire or related elongate control element (not presently shown). In a manner similar to that depicted in <FIG>, the variable slot width W<NUM> and W<NUM> around the circumference contribute to such steerability, although it will be appreciated that the variable slot pitch of <FIG>, <FIG> may be used as well.

Referring next to <FIG>, device <NUM> is shown in the form of a guide wire assembly as it exists in five different states of actuation from fully straight or linear at 13A to bent at a <NUM> degree angle at 13E. The guide wire assembly includes an elastic bias section <NUM> where an operator (not shown) may manipulate the relative position between the control wire <NUM> and the sheath <NUM>, an intermediate section <NUM> (shown with an indeterminant length), an anchoring section <NUM> that can be selectively expanded in order to establish secure contact between the device <NUM> and an interior lumen wall and a steerable section <NUM>. Additional details associated with the construction of the guide wire assembly may be found in the aforementioned <CIT> and <CIT>. In particular, the steerable section <NUM> may be made of one sheath <NUM> plus one control wire <NUM>, connected to their respective two ends such as that shown for sheath proximal and distal ends <NUM>P and <NUM>D. In the embodiment shown, the anchoring section <NUM> may be formed such that it is situated within the steerable section <NUM> to be a part thereof such that it is near the distal end <NUM>D of sheath <NUM>. The elastic bias section <NUM> may be used as a tool such that when coupled to at least one of the control element <NUM> or the sheath <NUM>, can be used to regulate relative axial positions between them to effect transitions in sheath <NUM> shape or rotation. Details associated with the elastic bias section <NUM> may be found in the aforementioned <CIT> and <CIT>, and may further include a display configured to inform an operator about an operational status of the reconfigurable section that resides within the sheath <NUM>. Although not shown, other features may be included at the distal end <NUM>D of sheath <NUM>, including a steerable antenna or steerable drilling tool.

In both of the embodiments depicted in <FIG> and <FIG>, the reconfigurable section of sheath <NUM> may include a plurality of steerable sections (<FIG>), as well as an expandable anchoring section <NUM> (<FIG>) responsive to changes in force between the elongate control element <NUM> and the sheath <NUM>. In particular, each of the steerable sections may be configured to be responsive to different levels in such force. Furthermore, these steerable sections may preferentially deform into similar shapes and directions, or do so independently of one another.

Referring next to <FIG>, while the foregoing description pertains to a continuous slot <NUM> defining a single cut with variable width W that alternates between a smallest value W<NUM> and maximum value W<NUM>, it is also possible to make W<NUM> zero. In particular, another embodiment of the device is shown as <NUM>. Thus, rather than having one long continuous helical slot (such as that of <FIG> and portions of <FIG>), a series of discontinuous slots 212A, 212B, 212C, 212D and 212E may be formed in the sheath <NUM>, while the control element <NUM> is substantially similar to that of the control element <NUM> discussed earlier. This would have the effect of providing a continuity in the wall <NUM> that forms a bridge, link or related hinge <NUM> between axially-adjacent wall sections. These hinges <NUM> act as short uncut sections that provide additional rigidity elements between adjacent wall <NUM> sections to prevent the full gap closure of the slot <NUM> between two wall <NUM> sections, while on the opposing side the gap can still be closed upon raising the tension in the actuating wire. Such a construction would provide improved torque resistance to help promote the one-to-one correspondence between each rotation at the proximal end <NUM>P and the distal end <NUM>D, which in turn enhances the reliability of a particular steering movement. The upper portion of <FIG> shows an example of such an embodiment of the disclosure with a flat projection of the slot <NUM> cutting pattern via two-dimensional representation of the unraveled tubular sheath <NUM>. The unraveled view is used to better show the relationship between the pitch P along the x-direction projection and the number of y-direction travels πD, 2πD, 3πD. around the sheath <NUM> circumference, as well as how the helical slot angles relative to the axial dimension of the sheath <NUM> vary with the pitch P. In the lower portion of <FIG>, opposing circumferential sides of a few helical slots <NUM> near the distal end are shown. As can be seen, the pitch P varies in a manner generally similar to that of the embodiment of <FIG>. The length of a helical cut section will then also vary between a maximum length L<NUM> and a minimum length L<NUM>.

The additional structural rigidity associated with devices <NUM> with such hinges <NUM> helps promote improved pushability, as well as prevent an undesirable torsional deviation of the sheath <NUM> between the proximal and distal ends <NUM>P, <NUM>D. As mentioned above, it is helpful to promote good and reliable steerability by ensuring that any rotation angle imparted to the proximal end produce an equal (i.e., one-to-one) rotation angle on the distal end. The hinges <NUM> further this one-to-one relationship by having the hinges <NUM> be aligned on the convex side (such as that depicted in <FIG>) to prevent the axial shortening of the sheath <NUM> upon activation of the control wire <NUM>, while the gap associated with the slots 212A, 212B, 212C, 212D and 212E on the opposing side enables such shortening. It will be appreciated that although presently shown as having the bending only taking place in one plane, the number and position of such hinges <NUM> can be chosen such that the bending can follow in either one plane or in several planes, and that all such variants are within the scope of the present disclosure.

As with the embodiments disclosed in <FIG> and <FIG>, the width W of the slots 212A, 212B, 212C, 212D and 212E may be variable or constant, depending on the application of the device <NUM>. Similarly, the dimensions of the slots 212A, 212B, 212C, 212D and 212E close to their respective hinge <NUM> also defines the amount of hinge <NUM> deformation while the device <NUM> is being activated. As such, a very small slot width W close to the hinge <NUM> will prevent strong bending of the hinge <NUM> over an axis perpendicular to the longitudinal or axial dimension of the control element <NUM>. Further, the ratio between diameter D and the slot width W on the concave side will determine the maximum amount of bending deformation of the hinge <NUM> around its longitudinal axis. As soon as the gaps between adjacent wall <NUM> sections on the concave side are entirely closed, additional sheath bending stops. In this position the device <NUM> not only reaches its maximum bending angle, but also become less floppy because of the full axial dimension contact of the slot <NUM> edges. This means that the rigidity of such devices <NUM> is controllable. Without tension in the control wire <NUM>, the floppiness of the sheath <NUM> is optimal, while for increasing tension it gradually becomes stiffer. This stiffening starts in the sections where the pitch P is smallest, because these sections will elastically deform easier than sections with a larger pitch P. Increasing tension will thus cause a stiffening of the sheath <NUM> over an increasing length, combined with the increasing bending.

Referring next to <FIG> and <FIG>, a variation of the embodiment of <FIG> is shown where rather than the hinges <NUM> of <FIG>, a series of interlocking members <NUM> made up of complementary-shaped male and female sections with nesting capability are provided. In a preferred form, the width of the cut is made as small as possible in order to get a proper shape fit, while the remainder of the width W of the helical slot <NUM> is larger in order to prevent gap closure of the gap on the circumferentially opposing surface that would in turn cause inadvertent sheath <NUM> bending. In particular, a shortening of the section of the sheath <NUM> that includes the interlocking members causes a closure of the gap around the locking members, resulting in an increased tangential torsional rigidity of the section. As can be seen, the shape of the interlocking members <NUM> produces a corresponding variable shape within the portion of the slot <NUM> that is occupied by the interlocking members <NUM>.

Reductions in tangential free movement or play may also be achieved through the use of locking members <NUM> such as those attached or integrally-formed between adjacent walls <NUM> that define a given slot <NUM>; such locking improves the steerability and such locking members may also be used for devices without a helical cut. Another feature is the fact that applying tension to the central control element <NUM> automatically causes a minor tangential rotation between adjacent helical coils. This effect can eliminate the use of proximal rotation for steering the distal end. In the embodiments depicted in <FIG>, the control elements <NUM>, <NUM> may-in addition to being used in a tension mode-be used in a pushing mode as a way to achieve one or both of a desired bending and STT effect.

The interlocking members <NUM> of <FIG> give more sheath <NUM> flexibility compared to those in <FIG>, while the interlocking turns still enable a good rotational torqueability, although not as much as that of <FIG>, because each interlocking member <NUM> still permits minor tangential direction rotation upon torsion. This rotation may be small for one loop of slot <NUM>, but having as many as twenty or more loops within a sheath <NUM> will add up rapidly and leads to a relatively reduced degree of torqueability. Minimizing the gap around the interlocking member <NUM> is important in order to reduce the relative axial rotation between adjacent loops.

Referring next to <FIG>, minimizing the gap discussed in conjunction with the interlocking members <NUM> of <FIG> is shown. When a specific tension force is applied to the control wire, the small V-shaped gap in slot <NUM> between the top of a male section and the bottom of the surrounding female section will close entirely. Thus, this application of a tension preload on the control element <NUM> of <FIG> can be used to control the tangential gap between the adjacent wall components. With a proper load there is full contact in the interlocking member <NUM> to promote torsional actuation at the proximal side into comparable one-to-one movement into the sheath <NUM> distal end.

Examples of the function of the V-shaped gap <NUM> are shown. <FIG> shows with particularity a section of a sheath <NUM> with the gap of slot <NUM> around an interlocking member <NUM>. The two borders of the gap are shown as <NUM><NUM> and <NUM><NUM>. <FIG> show enlargement details of <FIG>. In <FIG>, the angle between the gap of slot <NUM> with width ΔX and the length axis of the sheath <NUM> is given as β. As such, cosβ = ΔX/Xt. Likewise, the tangential gap Xt can be described by the following formula: <MAT>.

<FIG> shows the same section after a moment of torque Mt is applied to the proximal side of the sheath <NUM> and if the distal end cannot freely rotate, the width of the gap first has to become zero before the full torque can be transferred from proximal to the distal side. Seen in the tangential direction this means that between each pair of adjacent slot <NUM> coils the rotation over a gap with a value of Xt is needed before real contact is made between surfaces <NUM><NUM> and <NUM><NUM> at which time a one-to-one torque can be applied. Each pair of coils causes an angular deviation φ in a sheath <NUM> with diameter D, which can be calculated as follows: <MAT>.

For example if β = <NUM> degrees and D = <NUM> microns and ΔX = <NUM> microns, the deviation per coil φ = <NUM>/(π350) =<NUM> degrees. This deviation will double if the torque direction is reversed, because the opposing gap between surfaces <NUM><NUM> and <NUM><NUM> has then reached a double width, as can be seen in <FIG>. It will be appreciated the otherwise desirable one-to-one steerability in response to applied torque is not desired in such cases, especially those involving when the direction of the applied torque has to be changed during device <NUM> steering. Nevertheless, by choosing a proper design of the interlocking member <NUM> and if a preload is applied which closes the tangential gap, the torsional steerability suddenly improves significantly, as can be seen in <FIG>. Here the gap between surfaces <NUM><NUM> and <NUM><NUM> is fully closed after applying the axial preload, where surface <NUM><NUM> has now moved until its position depicted as <NUM><NUM>' where full contact is established. Of course this preload causes a decrease in the axial length with an amount of shortening of ΔX, which in this example is slightly over <NUM> microns, but the influence is a lot less important than the gain in torsional steerability. For a sheath <NUM> made up of thirty coils, the total length would change only just over <NUM> microns, while the tangential deviation by torsional load is reduced significantly. For example, if the angular deviation φ in sheath <NUM> is <NUM> degrees per coil, then thirty coils would produce <NUM> degrees, while after applying the preload the deviation becomes zero. If the preload is chosen well, it has no influence on the straightness of the sheath <NUM>. For clarity, it must be stated that the application of the preload for improving the torsional steerability is different than the final application for steering of the bendable distal end. Upon further increasing the axial preload the device will start bending because the opposing larger gaps on the convex side will start closing. Full release of the entire preload will result in an optimized floppiness of the slotted distal sheath <NUM> section, so the device has many features integrated into a single cutting design.

Although in the figures only a single row of interlocking members <NUM> is shown, it may be clear that more locking members, eventually in different planes may be used in order to improve certain aspects of devices according to the disclosure. For example, suppose that only tangential torquability is an issue and steerability is not important. In such cases the feature of closing the tangential gap of interlocking members <NUM> by axial preload is already a major issue and is an important claimed embodiment of the disclosure.

Of course the concept of closing the tangential gap not only works upon axial shortening. It may be clear that if the central control element <NUM> is used in a pushing mode, the interlocking members <NUM> can also be closed in a similar way as described above, but now upon lengthening. Further pushing enlarges the opposing gap in devices like the one of <FIG> and will also cause bending. It will be dependent on the type of application which choice is made, either pulling or pushing.

Instead of leaving small bridges or interlocking members in the sheath <NUM> material itself, as mentioned above, additional small rigidity elements (not shown) may be used to connect adjacent loops in a similar way, thus causing bending upon tension and preventing the relative torsional displacement between adjacent loops. In one form, the rigidity element is a polymer, glue or related material that fills the gaps and resists change of lengths and tangential shear between adjacent coils. Consistent with the discussion associated with <FIG> above, this resistance against compression has to be higher at the convex side than on the concave side. In another example, a polymer cover (not shown) may be applied on the outer surface of the sheath <NUM>. The polymer cover preferably has a wall thickness that is larger on the convex side than on the concave side. As such, the polymer cover would enable the bending of the sheath <NUM> while preventing tangential deviations between adjacent slot <NUM> loops caused by torque. There is no difference between the angle of rotation on the proximal end relative to the distal end, so the polymer cover has a similar function as the locking elements as described in <FIG> and <FIG>.

Another possibility is the use of an eccentric reinforcement sheath (not shown), acting as a flexible spine, which is embedded in a layer around the sheath <NUM>. This connection between this flexible section and the sheath <NUM> of the steerable device <NUM> may be achieved by any known technique, including the use of dipping, extrusion, welding, crimping, brazing, gluing or embedding in a surrounding cover material.

If additional flexibility is needed there may be extra slots besides the main helical slot. One example is that there are two or more continuous helical main slots. This would reduce the risk of failure, because if one section would break, the remainder of the helices would still keep the device intact, at least for a safe retrieval. In another embodiment of the disclosure there is one continuous main helical slot, while additional slots are each only located at the concave side and only run over an angle of less than <NUM> degrees. They can run with the same pitch angle as the continuous main slot or eventually with a different pitch angle. The advantage of such a series of interrupted extra slots is that they will also contribute to the steerability by bending, even if the main helix and additional have a constant slot width around the circumference. This is because there would be more slots on the concave side than on the convex side.

Besides the method of cutting slots in a sheath <NUM>, <NUM>, <NUM>, there is also the possibility to form a strip of material into an elongate helical coil. By giving the strip an alternating width before it is formed into a helical coil. The distance between the widest parts of the strip determines the diameter of the final product. If the widest parts are exactly located on one side of the final coil, it will become a bending behavior in one plane, with the concave side being the opposing side. Of course other relative locations of the widest parts give different bending characteristics, like in more than one plane.

As mentioned throughout this disclosure, the need for a good one-to-one relationship between applied torque and sheath rotation is a significant limitation with devices employing conventional helical slots. While the various embodiments disclosed herein are made in such a way that any tangential deviation between adjacent coils is avoided as much as possible, another feature of the helical devices disclosed herein is the fact that applying tension to the central control element automatically causes a minor tangential rotation between adjacent helical coils or wall sections. As discussed above, a helical section that rotates tangentially around its own length axis by applying a length change in the helical wall corresponds to the STT; this effect can eliminate the need to apply proximal end rotation in order to produce sheath distal end steering, and in fact the prototypes discussed below take advantage of the STT effect. When there are enough coils available in the distal end the application of a tension force can cause a full tangential rotation of <NUM> degrees at the distal tip, while the major length of the guide wire is kept still. As will be understood by reference to the present disclosure, it is not required that STT be located at the very distal end of the device. For example, it may be also arranged either closer to the proximal end or somewhere in between the proximal and distal ends. In one embodiment a steerable bending tip may be combined with the STT. Another embodiment is with the STT section located more distally than the bending section, so that the torque effect appears under an angle with the proximal main length axis. Any combination between existing devices with the features of this disclosure, including one or more of the STT effect and the steerable sections, is deemed to be within the scope of the present disclosure.

This STT feature is particularly beneficial for very small diameter devices (such as devices used to navigate a body lumen) where the floppiness of extremely thin guide wires would otherwise inhibit the desirable one-to-one remote torque steering by rotating the proximal end around its length axis. Another advantage is that the operator does not have to rotate the entire wire together with its proximal manipulation tool, so it becomes easier to handle. The only need is a small knob for related tool (such as an elastic bias device) or applying some tension or the use of a proximal bias spring as described in <CIT> and <CIT>.

Still another advantage of the STT principle is that the issue of friction becomes less critical as compared to devices using one-to-one torque. While the remainder of the device is kept still, the tip can be bent and rotated on its own, so the friction is significantly minimized. The operator only has to use the knob on the control element by pulling or pushing. Thus, once the tip is brought in the right position in front of a target lumen, it can just be pushed longitudinally farther into that lumen so that the procedure can be repeated as desired. This also means, if proximal torque is not needed anymore for steering, that the major length of the device may be made stiffer without losing the STT and steerability at the distal end.

Upon applying tension on the control element, the extreme floppiness of the helical distal end is reduced and it becomes more robust in order to enable the operator to push it forward into side branches of the lumen. After this branch is reached the distal end can be made floppy again, just by reducing the tension of the control element. Therefore the floppiness and shape of the distal end can be remote controlled.

While in this description the device is discussed in conjunction with a guide wire assembly, it should be clear that any device using one or more of the described features is meant to be part of the disclosure. The guide wire assembly is just one example out of many embodiments. The author of the present disclosure made some prototypes from a superelastic nitinol sheath with outer diameter of <NUM> and a wall thickness of <NUM>. A laser was used to cut a helical slot with a width of <NUM> into the wall with a pitch of <NUM> and with forty coils. Application of a tension force on a central steel wire with a diameter of <NUM> caused a tangential rotation at the distal end of <NUM> degrees, and the total shortening was <NUM>. So the tangential rotation was <NUM> degrees per coil. This prototype did not have a variable slot width.

Another sample was made in a superelastic nitinol tube with outer diameter of <NUM> and a wall thickness of <NUM>, and generally resembles according to <FIG>, with the slot around the lock only <NUM> microns wide and <NUM> microns on the opposing side. The pitch of the coil was <NUM> for the twenty most distal coils and went over into a pitch of <NUM> for another twelve coils and finally into ten coils with a pitch of <NUM>. All locking members were located in one line parallel to the axial dimension of the sheath. Upon tension of a steel wire with diameter <NUM> a combined movement of the tip occurred. Initially, the tip starts bending, after which upon increasing tension the bent tip also rotates around the main length axis of the remainder of the uncut section. Moreover, the locking members all become engaged and the floppiness of the distal section disappears. Also the minor tangential rotation per coil, combined with the different slot width on opposing sides, makes that the device does not exactly bend in one plane, but in more planes, for example into a pigtail-like shape. If this is not desirable, the width of the slots may be modified and/or the slots may be placed with a small longitudinal offset per coil, which eventually be used to compensate the tangential rotation. Unlike the previously-described prototype, the presence of interlocking members evidences one form of the variable-width slot was included in this prototype.

The locking members ensure that during the STT-effect the wall of the helix is not deformed too strong and the outer surface remains in a smooth state. The locking members also ensure that the maximum tangential rotation upon tension is known and limited, so this information can be used in exact position control.

Another possibility to ensure that only pure tangential rotation appears is the use of an internal or external straight guiding member, which has a size that allows the free tangential rotation but prevents bending. In one prototype a stainless steel tube with outer diameter surrounds the control element with outer diameter <NUM> and they are both located in the nitinol tube that was mentioned above. Only the twenty most distal coils were not internally supported by stainless steel tube. Upon applying tension to the control element the distal twenty coils start bending first, because they have the smallest pitch. When the tension is further increased the coils with larger pitch will try to start bending, but also start to show the STT effect. As the internal supporting tube prevents bending for these coils, only the STT effect is apparent. The total result is that the most distal tip bends and then the STT causes this bent tip to rotate, enabling the operator to search the right position for reaching any branching side lumen with only the help of variable tension, without using proximal torque.

It may be clear that the same pure STT-effect can also be achieved by supporting the slotted helical section with a surrounding tube in which the device can freely rotate, while bending is prevented. The supporting tube does not have to be straight in all cases. In specific embodiments the supporting element may be curved in order to use the STT effect under an angle with the main proximal length axis, for example any angle between <NUM> and <NUM> degrees.

The supporting tube may be integrated with the most distal tension wire that functions as control element for the bending tip. Such an integrated element does not have to be made of separate tube and wire, but can for example be centre-less grinded into one piece of wire. Near the distal end flexibility upon bending is crucial, while prevention of bending in the STT section asks for a larger size of this element. Also closer to the proximal end the control element may be made thinner in order to make the proximal section more flexible. Only where the STT section is active, more support may be needed.

While the present disclosure emphasizes a device for guide wire applications, it will be appreciated by those skilled in the art that but the same principle can be used for a range of different exoluminal or endoluminal applications, including catheters, steerable tips, endoscopes, laser systems, ablation systems, stents, filters, angioplasty balloons, drains, dilators, filters, baskets, filterbaskets, anchors, floating anchors, occlusion devices, guide wires, stylets, electrodes, leads, drains, catheter sheaths for use with catheter introducers or a drug infusion catheter, or related medical devices. Likewise, the device <NUM> may further include one or more endoluminal devices that can slidably fit over the sheath, at least when the sheath is in the substantially undeformed second shape. The endoluminal device can be at least any of a catheter, steerable tip, endoscope, stent, filter, angioplasty balloon, drain, dilator, filter, basket, filterbasket, anchor, floating anchor, occlusion device, guide wire, stylet, electrode, lead, drain, catheter sheath for use with catheter introducers or a drug infusion catheter, as well as combinations of the above. Similarly, the device itself may be a catheter, steerable tip, stent, filter, angioplasty balloon, drain, dilator, basket, filterbasket, anchor, floating anchor, occlusion device, guide wire, stylet, electrode, lead, drain, catheter sheath for use with catheter introducers or a drug infusion catheter, or combination of the above. Furthermore, materials making up the control element and sheath can be made from polymers, metals or similar structural constituents, or combinations thereof. In a particular form, the metal can be a shape-memory metal. These materials are especially valuable for applications requiring reconfigurable or related components.

As mentioned above, the devices disclosed herein may be used in non-medical applications as well as medical applications. For devices using the principles according to the disclosure that are used in other fields than medical, different sizes and different techniques for providing the slots may be used. Examples are water jet cutting, etching, abrasive cutting and others. In another embodiment, there is no cutting of slots, for example if a technique such as <NUM>-dimensional printing is used to form the device with an integrated pattern of slots. In another form of the device, steerable pipes may be used in oil wells, water wells, gas wells or the like, as well as for space applications or transportation systems. In yet another form, the devices may be configured as an endoscope for medical and non-medical use.

In general, it is advantageous if the distal end of a guide wire assembly is relatively compliant or floppy, while the majority of the length should be kink resistant, pushable, bendable and able to transmit torsional forces from the proximal to distal end in order to maneuver the assembly accurately. The tubular sheath can be chosen from any wire or hypotube material suitable for guide wire or catheter applications. One specifically suitable material is superelastic nitinol, a nickel-titanium alloy with shape-memory properties that is well-known for its flexibility, pushability, biocompatibility and kink resistance. In one configuration, the majority of the length of the tubular sheath may made of metal while the distal section may be made from a relatively soft and flexible material that easily deforms when the control wire being moved causes an axial compression in the tubular sheath. The control wire can be made of a high strength yet flexible polymer. If improved visibility for MRI or related radio-opacity is needed, additional markers of materials like gold, platinum, silver, tungsten, iridium or the like may be used at specific locations on either the control wire or the tubular sheath. Other material choices include metals and related materials for improved strength, stiffness or visibility for MRI or radio-opacity. Nitinol does not have to be in its superelasic mode, but can also be used in its linear elastic state, caused by a different thermomechanical production process.

The elastic bias section is disposed proximal relative to the reconfigurable section, and is configured to vary the axial length of the sheath's reconfigurable section, which in turn may be used to produce the variation in one or both of bending and rotation as discussed herein. The elastic bias section assists in compensating the relative movement between the control element and the sheath in the reconfigurable section by allowing relative movement of the sheath and the control element in the vicinity of the proximal end of the device. To achieve this, the elastic bias section acts as a bias spring to create an axial force necessary to keep the reconfigurable section in its deformed state. Actuation (such as by a user or operator) of the bias spring will cause a release of the axial force on the control element and so allow the spontaneous return of one or both of the anchoring and steerable sections from a deformed shape to an undeformed or lesser deformed shape.

For a proper functioning of all devices <NUM>, <NUM>, <NUM> described above it may be necessary to take precautions that the control elements <NUM>, <NUM>, <NUM> and respective steerable sheaths <NUM>, <NUM>, <NUM> always remain substantially concentric. This can be achieved by placing a flexible liner (not shown) in between the control elements <NUM>, <NUM>, <NUM> and their respective sheaths <NUM>, <NUM>, <NUM>. In other cases, such a liner may be eccentric for achieving a different predictable behavior of the devices <NUM>, <NUM>, <NUM>.

It is within the scope of the invention that any material or any combination of materials can be used in any configuration. For example, materials making up the elongate control elements <NUM>, <NUM>, <NUM> may include polymers (including high-strength polymers), metal and metal with enhanced radio-opacity (including magnetic resonance imaging) features. It will be appreciated by those skilled in the art that the control elements <NUM>, <NUM>, <NUM> may be made from a different material than the elongate tubular sheaths <NUM>, <NUM>, <NUM>.

There are several options to making steerable devices according to the invention. Moreover, it is an object of the present disclosure that devices <NUM>, <NUM>, <NUM> discussed herein may be used in medical procedures, comprising minimal invasive devices, surgical tools, steerable drilling tools, instruments, rotating instruments, placement of pacemaker leads and implants. Of course it is also an object of the present disclosure that such devices <NUM>, <NUM>, <NUM> may be used in non-medical procedures, including but not limited to exploration, completion and maintenance of oil, gas and water wells, fluid and gas transport systems, manipulators in robotics, vacuum environments, laboratory equipment and other fields. Even for the use outside of a lumen the steerable devices <NUM>, <NUM>, <NUM> according to the present disclosure may be used, for example in a robot arm or in a manipulator in outer space or under water, like a manipulator arm on a submarine. One example would be a steerable antenna for outer space applications. Other applications are the fine adjustment of parts in drones and related unmanned aerial vehicles, like for example fine adjustment of wing flaps, rudders or propeller blades.

The STT effect mentioned above can also be used in devices without using a proximal mechanical actuation. For example, in space, vacuum, water, gas or oilfield applications, there may be enough room in the device to put an actuator closer to the distal section where steering is needed. This actuator can apply the necessary force on the control element by using an electrical or hydraulic lead, running to the proximal end. The remote electric, magnetic or hydraulic actuator only needs a steering signal, which is converted into the necessary force to move the control element in order to change the shape of the reconfigurable section. If needed, a gear or lever may be used to enlarge the needed force.

It is noted that terms like "preferably", "generally" and "typically" are not utilized herein to limit the scope of the claimed disclosure or to imply that certain features are critical, essential, or even important to the structure or function of the claimed disclosure. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure. Likewise, for the purposes of describing and defining the present disclosure, it is noted that the terms "substantially" and "approximately" and their variants are utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement or other representation, as well as to represent the degree by which a quantitative representation may vary without resulting in a change in the basic function of the subject matter at issue.

Claim 1:
A steerable device comprising:
a tubular sheath (<NUM>, <NUM>, <NUM>, <NUM>) comprising:
a proximal end (<NUM>P, <NUM>P, <NUM>P);
a distal end (<NUM>D, <NUM>D, <NUM>D) opposite the proximal end (110p, 210p, 310p); and
at least one reconfigurable section disposed intermediate the proximal (<NUM>P, <NUM>P, 310p) and distal (<NUM>D, <NUM>D, <NUM>D) ends and possessive of an increased flexibility, the at least one reconfigurable section comprising at least one helical slot (<NUM>, <NUM>, <NUM>, <NUM>) formed through the wall (<NUM>, <NUM>, <NUM>, <NUM>) of the sheath (<NUM>, <NUM>, <NUM>, <NUM>), the at least one helical slot (<NUM>, <NUM>, <NUM>, <NUM>) defining a pitch (P) along the axial dimension of the tubular sheath (<NUM>, <NUM>, <NUM>, <NUM>); and
an elongate control element (<NUM>, <NUM>, <NUM>) defining a proximal end and a distal end, the elongate control element (<NUM>, <NUM>, <NUM>) centrally disposed along the axial dimension of the tubular sheath (<NUM>, <NUM>, <NUM>, <NUM>) and attached to at least one part of the tubular sheath (<NUM>, <NUM>, <NUM>, <NUM>) in order to enable an operator to impose an axial force to the elongate control element (<NUM>, <NUM>, <NUM>) that causes a relative tangential rotation between adjacent wall sections that define the helical slot (<NUM>, <NUM>, <NUM>, <NUM>), resulting in a known, limited, controllable torsional rotation of the distal end (<NUM>D, <NUM>D, <NUM>D) of the tubular sheath (<NUM>, <NUM>, <NUM>, <NUM>) without torsional rotation of the proximal end (<NUM>P, <NUM>P, <NUM>P) of the tubular sheath (<NUM>, <NUM>, <NUM>, <NUM>).