Steerable Delivery Sheaths

[0001] This application claims the benefit of U.S. Provisional Application No. 61/482,018, filed May 3, 2011, U.S. Provisional Application No. 61/555,687, filed Nov. 4, 2011, and U.S. Provisional Application No. 61/555,706, filed Nov. 4, 2011. The disclosure of each of the aforementioned applications is incorporated by reference herein.

[0002] All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference.

[0003] Delivery devices are used to deliver, or guide, medical devices or instruments to a target location within a subject. The delivery devices provide access to target locations within the body where, for example, diagnostic, therapeutic, and interventional procedures are required. Access via these devices is generally minimally invasive, and can be either percutaneous, or through natural body orifices. The access can require providing a guiding path through a body lumen, such as, for example without limitation, a blood vessel, an esophagus, a trachea and adjoining bronchia, ducts, any portion of the gastro intestinal tract, and the lymphatics. Once the delivery device has provided access to the target location, the delivery device is then used to guide the medical device or instrument to perform the diagnostic, therapeutic, or interventional procedure. An example of such a delivery device is a guide catheter, which may be delivered by steering it to its required destination, tracking it along a previously delivered guide wire, or both. The list of components being delivered for use percutaneously is large and rapidly growing.

[0004] Minimal outer dimensions of these delivery devices are important for minimizing the injury associated with delivery. Minimizing the wall thickness of the delivery device provides additional space for the medical device to be guided, while minimizing the injury associated with entry into the subject and the closure needed. Flexibility of the delivery device is important in allowing the guiding device to track or be steered to its target destination along tortuous paths while minimizing injury to the intervening tissues. The delivery device also needs to have compressive and tensile properties sufficient to support its delivery to the target site. When tracking around bends in the body, any kinks created in the guiding device can create an obstruction to the delivery of the medical device. When used as a steerable device, the distal end of the delivery device is preferably deflectable over a range of bend radii and responsive to the steering controls. The delivery device also should support torque transmitted from the handle to the distal region.

[0005] Once the delivery device is in place the delivery device preferably also supports torque around a distal bend such that the medical device may be rotated into position while sustaining some contact loads. Additionally, once in place the guiding device preferably is sufficiently stiff to support and guide the medical device to its target destination. The guiding device should also remain stable and not shift from one state of equilibrium to another either spontaneously or under the influence of forces being imparted to it from the delivery of the medical device or its own control mechanisms. As the delivery device often travels down fluid-filled lumens such as, for example without limitation, blood vessels, it should additionally incorporate a seal against fluids impinging upon its periphery and another at its distal end which interfaces with the medical device to maintain a seal around the delivery device.

[0006] There exists a need for improved steerable delivery devices and guiding medical devices.

[0007] One aspect of the disclosure is a steerable delivery device comprising: a steerable portion adapted to be steered; and an outer sheath and an inner sheath disposed within the outer sheath along a first portion of the delivery device, the outer sheath comprising a first material and the second sheath comprising a second material, wherein the first and second materials are merged together at a merged location distal to the steerable portion, forming a unitary section of material at the merged location, wherein the inner and outer tubular members are adapted to be axially moved relative to one another along the steerable portion to steer the steerable portion.

[0008] In some embodiment the first material is different than the second material.

[0009] In some embodiments the inner sheath comprises a braided material extending along the steerable portion.

[0010] In some embodiments the outer sheath comprises a tubular element in the steerable portion that includes a plurality of slots formed therein. The tubular element in the steerable element can include a first interlocking element and a second interlocking element each adapted to allow relative movement therebetween when in a first configuration and to prevent relative movement therebetween along at least one of a radial axis and an axial axis when in a second configuration. The outer sheath can also comprise a second tubular element in the steerable portion secured to the tubular element, wherein the second tubular element has a plurality of second slots formed therein in a pattern different than the plurality of slots formed in the tubular element. The outer sheath can comprise a braided material proximal to the steerable portion, wherein a distal end of the braided material and a proximal end of the tubular element are secured to one another.

[0011] In some embodiments the device further comprises a tensioning element disposed radially between the inner and outer sheaths in the steerable portion. The tensioning element can be secured to the inner sheath proximal to the steerable portion and can be secured to the unitary material in the merged location. A proximal end of the tensioning element can be secured to the inner sheath such that the proximal end is closer to the steerable portion than it is to a proximal end of the inner sheath.

[0012] One aspect of the disclosure is a steerable delivery device comprising: a steerable portion adapted to be steered; and an outer sheath and an inner sheath disposed within the outer sheath, wherein the outer sheath and the inner sheath are permanently axially fixed relative to one another at a location distal to the steerable portion, and wherein, in the steerable portion, the outer sheath comprises a tubular member with a first portion with a plurality of slots formed therein in a first pattern and a second portion with a plurality of slots formed therein in a second pattern different than the first pattern.

[0013] In some embodiments the first pattern includes a first interlocking element and a second interlocking element each adapted to allow relative movement therebetween when in a first configuration and to prevent relative movement therebetween along at least one of a radial axis and an axial axis when in a second configuration.

[0014] In some embodiments the inner sheath comprises a braided material extending along the steerable portion. The outer sheath can comprise a braided material proximal to the steerable portion, wherein a distal end of the braided material and a proximal end of the first portion of the tubular element are secured to one another.

[0015] In some embodiments the device also comprises a tensioning element disposed radially between the inner and outer sheaths in the steerable portion. The tensioning element can be secured to the inner sheath proximal to the steerable portion and can be secured to a location on the device wherein the two tubular sheaths are permanently axially fixed relative to one another.

[0016] In some embodiments the tubular member is a single tubular element such that the first portion and the second portion are unitary.

[0017] One aspect is a steerable delivery device comprising: a steerable portion adapted to be steered; an outer sheath and an inner sheath disposed within the outer sheath and axially fixed to the outer sheath at a first location distal to the steerable portion, wherein the inner and outer tubular members are adapted to be axially moved relative to one another along the steerable portion to steer the steerable portion; and a tensioning element secured to the inner sheath at a first location proximal to the steerable portion and secured at a second location where the inner and outer sheaths are axially fixed relative to one another, the tensioning element disposed radially between the outer and inner sheaths in the steerable portion, wherein the tensioning element is adapted to add axial stiffness to the steerable portion when the inner and outer sheaths are moved relative to one another when steering the steerable portion.

[0018] In some embodiments the tensioning element is free floating between the first and second locations.

[0019] In some embodiments the first location is closer to the steerable portion than to a proximal end of the inner sheath.

[0020] In some embodiments the tensioning element is adapted to be disposed on an inner curve of the steerable portion when the steerable portion is actuated.

[0021] In some embodiments the tensioning element is made of Kevlar.

[0022] In some embodiments the outer sheath includes a tube section with a plurality of slots formed therein in a first pattern. The first pattern can include a first interlocking element and a second interlocking element each adapted to allow relative movement therebetween when in a first configuration and to prevent relative movement therebetween along at least one of a radial axis and an axial axis when in a second configuration.

[0023] One aspect is a steerable delivery device comprising: an outer sheath and an inner sheath disposed within the outer sheath, wherein the inner sheath includes a first tubular element; a steerable portion adapted to be steered; wherein along the steerable portion the first tubular element includes a first section of a first material with a first durometer and a second section of a second material with a second durometer different than the first durometer, wherein the first and second sections are disposed at different radial portions of the first tubular element.

[0024] In some embodiments the first durometer is greater than the second durometer. The first section and the steerable portion can be adapted such that the first section is disposed on an inner curve of the steerable portion when the steerable portion is steered. The device can further comprise a tensioning element disposed radially between the inner and outer sheaths along the steerable portion and adapted to be disposed on the inner curve of the steerable portion when the steerable portion is steered, and wherein the tensioning element is disposed directly adjacent to the first section. The first section can extend about a quarter of the way around the circumference of the first tubular member. The first section can be adapted to be disposed about 90 degrees away from an inner curve of the steerable portion when steered. The first section can be two discrete sections around the circumference of the tubular member, and wherein each of the two sections is about 90 degrees away from the inner curve of the steerable portion when steered. The device can further include a tensioning element disposed radially between the inner and outer sheaths along the steerable portion, and wherein the tensioning element is disposed directly adjacent to the second section.

[0025] In some embodiments the first tubular member consists of polymeric material.

[0026] In some embodiments the outer and inner sheaths are axially fixed relative to one another at a first location distal to the steerable portion.

[0027] In some embodiments the outer sheath includes a tube portion with a plurality of slots formed therein in a first pattern, and wherein the first pattern includes a first interlocking element and a second interlocking element each adapted to allow relative movement therebetween when in a first configuration and to prevent relative movement therebetween along at least one of a radial axis and an axial axis when in a second configuration.

[0028] One aspect is a steerable delivery device comprising: a steerable portion adapted to be steered; an outer sheath and an inner sheath disposed within the outer sheath, the sheaths are axially fixed relative to one another distal to the steerable portion, and are adapted to be axially moved relative to one another along the steerable portion to steer the steerable portion; a wire element secured to the inner sheath and to the outer sheath; and a pulley secured to an external actuator, wherein the wire element extends around the pulley and is adapted to be actuated to steer the steerable section.

[0029] In some embodiments a distal end of the wire element is secured to a distal tip of the inner sheath. A proximal end of the wire element can be secured to an outer surface of the outer sheath.

[0030] In some embodiments a distal end of the wire element is secured to the proximal end of the inner sheath. A proximal end of the wire element can be secured to a proximal end of the inner sheath.

[0031] In some embodiments the outer sheath includes a tube portion with a plurality of slots formed therein in a first pattern, and wherein the first pattern includes a first interlocking element and a second interlocking element each adapted to allow relative movement therebetween when in a first configuration and to prevent relative movement therebetween along at least one of a radial axis and an axial axis when in a second configuration.

[0078] The disclosure relates generally to steerable delivery devices, which may be considered steerable guide devices, and their methods of use. The steerable delivery devices can be used to deliver, or guide, any type of suitable medical device or instrument therethrough to a target location within a patient's body. For example, the steerable delivery devices can be used to deliver, or guide, a medical device into bodily lumens or cavities such as, for example without limitation, a blood vessel, an esophagus, a trachea and possibly adjoining bronchia, any portion of the gastrointestinal tract, an abdominal cavity, a thoracic cavity, various other ducts within the body, the lymphatics, one or more chambers of the heart, etc. Once the steerable delivery device has gained access to a target location within the subject, one or more medical devices or instruments is delivered, or guided, to the target location to carry out one or more medical interventions. In some methods of use the steerable delivery devices described herein are tracked along a previously positioned guide wire, the positioning of which is known in the art.

[0079] FIG. 1 is a perspective view of a distal portion of an exemplary steerable delivery device. Steerable device 10 includes steerable portion 12 and has distal end 15. Steerable portion 12 includes an outer tubular member 14 and inner tubular member 16. Outer tubular member 14 has an inner surface defining a lumen therein, and inner tubular member 14 is sized to be disposed within the inner lumen of outer tubular member 14. Outer tubular member 14 and inner tubular member 16 are permanently axially fixed relative to one another at fixation location 18 along the length of steerable device 10. That is, at fixation location 18, the inner and outer tubular members are not adapted to move distally or proximally relative to one another and are permanently axially fixed to one another. “Permanent” fixation as used herein generally refers to fixation that occurs during manufacture of the device such that one or more components are not adapted or intended to be disengaged from one another during use of the device. As used herein, when the tubular members or components are described as being axially fixed relative to one another at a certain location, the fixation can be permanent fixation or temporary fixation unless specifically indicated to be one or the other. Fixation location 18 is located distal to steerable portion 12. At locations proximal to fixation location 18, inner tubular member 16 and outer tubular member 14 are axially movable relative to one another. That is, along steerable portion 12, inner tubular member 16 and outer tubular member 14 are adapted to move axially relative to another, which provides for the steering of the device, described below. Outer tubular member 14 has slots 22 formed therein, which define spine 20. Spine 20 extends along a length of steerable portion 12. Slots 22 are shown substantially perpendicular to the longitudinal axis “L” of steerable portion 12, when steerable portion 12 is in a straightened configuration as shown in FIG. 1. Inner tubular member 16 also has slots formed therein (not shown) in the steerable portion, which define a spine (not shown).

[0080] FIGS. 2A and 2B illustrate an exemplary embodiment of a steerable delivery device. Steerable device 30 has a distal end 37 and includes outer tubular element 34 and inner tubular element 36 which are axially immovable relative to one another at fixation location 38, but are axially movable proximal to fixation location 38. Outer tubular element 34 includes a plurality of slots 42 formed therein to define spine 40. Inner tubular element 36 also includes a plurality of slots formed therein (not shown) to define a spine (not shown). In FIGS. 2A and 2B, the spines are disposed substantially 180 degrees apart from one another. FIG. 2A illustrates steerable portion 32 deflected, or steered, into a first bent configuration, while FIG. 2B illustrates steerable portion 32 steered into a second bent configuration different than the first bent configuration. To steer the steerable portion into the configuration shown in FIG. 2A, a proximal portion of outer tubular member 34 is moved axially, and specifically proximally, relative to inner tubular member 36, while the tubular elements 34 and 36 are axially fixed relative to one another at fixation location 38. This can be accomplished by pulling outer tubular member 23 in a proximal “P” direction while maintaining the position of inner tubular member 36, by pushing inner tubular member 36 in a distal “D” direction while maintaining the position of outer tubular member, or by a combination thereof. The relative axial movement of the inner and outer tubular members as shown in FIG. 2A applies substantially opposing compressive and tensile forces to the spines of the tubular members, thus deflecting, or steering, the device in the direction of spine 40 of outer tubular member 34, as is shown in FIG. 2A. FIG. 2B illustrates a step of steering device 30 in the substantially opposite direction from that shown in FIG. 2A. To steer device 30 into the configuration shown in FIG. 2B, inner tubular member is moved proximally relative to outer tubular member 34. This can be performed by moving the outer tubular member distally, moving the inner tubular member proximally, or a combination thereof. This relative axial movement applies substantially opposing compressive and tensile forces to the spines in steerable portion 32 of device 30, thereby deflecting the device in a direction substantially opposite that of spine 40 of outer tubular member 34.

[0081] FIG. 2C shows a sectional view of the steerable portion from FIG. 2B, including optional floating tubular member 505 disposed within inner tubular member 504. Steerable portion 500 includes inner tubular member 504 and outer tubular member 502. Inner tubular member 504 has interrupted slots 512 formed therein to define spine 506. Outer tubular member 502 has interrupted slots 510 formed therein to define spine 508. The steerable portion is bent along the axis of spine 506. Spine 508 and spine 506 are substantially 180 degrees apart from one another (i.e., they are on substantially opposite sides of steerable portion 500).

[0082] To steer steerable portion 500 into the configuration shown in FIG. 2C (also shown in FIG. 2B), inner tubular member 504 is pulled in the proximal direction relative to outer tubular member 502, as is illustrated in FIG. 2B. Pulling on the inner member 504 applies a tensile force to inner spine 506. Because inner and outer tubular members 504 and 502 are axially fixed relative to one another at a location distal to the steerable portion, pulling on inner member 504 relative to outer tubular member 502 results in a compressive force applied to the distal end of the steerable portion of outer tubular member 502. The compressive force begins to compress slots 510 on outer tubular member 502. Compression of outer slots 510 causes outer tubular member to bend in the direction shown in FIG. 2C, and the bending stops when inner slots 510 are closed. Thus, outer slots 510 limit the degree of the bend of steerable portion 500. The same type of bending that is shown in FIGS. 2B and 2C would occur if outer tubular element 502 were pushed distally relative to inner tubular member 504.

[0083] If outer tubular member 502 were pulled proximally relative to inner tubular member 504 (or if inner tubular member 504 were pushed distally relative to outer tubular member 502), steerable portion 500 would bend in the manner shown in FIG. 2A. The degree of the bend would be limited by inner slots 512.

[0084] FIG. 2C illustrates an embodiment of a medical device including a floating tubular member, which may be referred to herein as a floating liner. In general, a floating liner is disposed within an outer structure. In the exemplary embodiment in FIG. 2C, the outer structure includes the inner and outer tubular members. The outer structure generally provides structural and mechanical properties for the delivery device, and the floating liner provides lubricity for a medical device or instrument to be advanced therethrough. A floating liner is generally impermeable as well. A floating liner “floats” with a portion of the outer structure. That is, the floating liner is not fixed to a portion of the outer structure in which it floats. In the exemplary embodiment in FIG. 2C, the floating liner floats within the steerable portion (i.e., is not attached to the steerable portion). In general, a floating liner is attached to the outer structure at a location proximal to the steerable or bendable portion of the device. For example, in the embodiment in FIG. 2C, the floating liner is attached to the outer structure at a location proximal to the steerable portion. A floating liner doesn't impede the ability of the outer structure to move as it is steered, bent, actuated, receives forces applied thereto, etc.

[0085] In some embodiments the floating liner is a lubricious polymer tube. In some embodiments the floating liner includes wire windings and/or axially laid wires.

[0086] The outer structure in which the floating liner floats can be any suitable tubular member. For example, the outer structure can be a catheter, guiding device, a steerable device, etc. In some embodiments the outer structure has a neutral bending preference but is not intended to be steered. In this embodiment the outer structure provides axial and radial stiffness thereby limiting the likelihood of kinks while the floating liner provides lubricity and is additionally restrained from kinking by the outer structure.

[0087] FIGS. 2A and 2B also show proximal portion 35 of device 30, which is proximal to steerable portion 32, having a substantially neutral portion designed to have no preferential bending axis while at the same time transmitting axial force and torque applied at a proximal end of the device (not shown).

[0088] In some embodiments, the inner and outer tubular members are adapted to have opposing compressive and tensile loads applied thereto to steer the steerable portion. In some embodiments at least one of the tubular members has a neutral bending axis. A neutral bending axis, as used herein, generally refers to an axis of the tubular member along which there is substantially no axial displacement in response to a compressive and/or tensile force applied thereto. Axial displacement along the neutral bending axis, in response to a compressive and/or tensile force applied thereto, is less than axial displacement of structures elsewhere in the tubular member. In particular, axial displacement along the neutral bending axis is minimal relative to axial displacement of structures elsewhere in the tubular member. Examples of a neutral bending axis include spine 382 in FIG. 21 and spines 412 and 414 in FIG. 23.

[0089] In some embodiments at least one of the tubular members is adapted to offset the neutral bending axis relative to the opposite tubular member. The neutral bending axes of the tubular members can be offset to be approximately tangent to opposite sides of the opposing members, making the neutral bending axis offset equal to the diameter of the device, thus providing the highest possible bending leverage ratio for a given device diameter.

[0090] The tubular members described herein may exhibit preferential or neutral bending behavior. Neutral bending behavior implies that the displacement for a given radially applied load (from the edge of the tubular member through the longitudinal axis of the tubular member) will be independent of the radial angle from which the load was applied. In contrast, in a non-neutral structure the displacement associated with a radial load will change as a function of the radial angle. An exemplary tubular member tending towards neutral bending behavior is shown in FIG. 25 or the uninterrupted spiral pattern of FIG. 25 which is essentially a spring.

[0091] In some embodiments the inner and outer tubular elements are adapted to be rotated relative to one another to enhance the steerability of the steerable portion. The tubular elements can rotate relative to one another yet remain axially fixed relative to one another at a location distal to the steerable portion. In these embodiments, in addition to axial forces being applied to one or more tubes, one or more tubular members are also rotated with respect to each other to steer the steerable portion.

[0092] In some embodiments only one of the inner and outer tubular members has at least one slot defining a spine along the steerable portion, while the other does not have any slots along the steerable portion. For example, in FIGS. 2A and 2B, outer tubular member 34 can have a slot and a spine while inner tubular member 36 does not have a slot formed therein. Alternatively, inner tubular member 36 can have at least one slot and a spine while outer tubular member 34 does not have a slot formed therein. The steerable portion can be steered as described herein if at least one of the inner and outer tubular members is adapted to preferentially bend in a first direction.

[0093] In the embodiment in FIGS. 1 and 2 the slots in both tubular members are substantially perpendicular to the longitudinal axis of the steerable portion. The slots in one or both of the tubular members can be, however, at an angle relative to the longitudinal axis that is other than substantially 90 degrees.

[0094] In some embodiments the steerable device also includes a tubular element disposed between the inner and outer tubular members. The intermediate member can be, for example without limitation, a flexible polymeric material. The intermediate member can be encasing one or both of the tubular members, or comprising one or both of the members. The intermediate member can be adapted to provide a fluid barrier and/or a low friction surface.

[0095] Slots as described herein can be formed in a tubular member by laser machining or other machining processes. Forming the slots creates at least one spine in a tubular member. A spine as used herein can be considered a region of the steerable portion that imparts axial stiffness in compression or tension, or both, and may additionally include features that provide torsional stiffness. When a single spine is created in a tubular member, the neutral bending axis of the tubular member is moved to the spine of the tubular member.

[0096] In some embodiments, a tubular member includes at least two spines, the combination of which moves the neutral bending axis of the tubular member to an axis parallel to, or tangent to when bent, the longitudinal axis of the tubular device and passing through the spines.

[0097] In some embodiments a liner, such as a flexible polymer liner, is bonded on the inner surface of the inner tubular member. In some embodiments a flexible polymer is bonded or otherwise disposed over the outer surface of the outer tubular member. A liner can also be disposed such that it is encasing the inner tubular member.

[0098] In some embodiments the steerable portion is comprised of a first tubular member that is adapted to bend preferentially in a first direction and a second tubular member that is not adapted to bend preferentially in one direction. In some instances of these embodiments, the second tubular member is a flexible polymer material with or without a braided or wire support. In some instances, a wire or other structural support is included in the first tubular member in the deflectable area to increase compressive and tensile stiffness along one side of the tubular member, thus moving the neutral bending axis from the longitudinal axis of the tubular member to the side of the tubular member that includes the structural support. In some instances wires are laid longitudinally and distributed evenly to increase axial stiffness in tension without creating a preferential bending.

[0099] In some embodiments the device includes three tubular members, having three offset neutral bending axes approximately 120 degrees radially spaced apart, thus providing the steerable device with universal steering in any direction.

[0100] FIG. 3 illustrates, for ease of description, a flattened, or unrolled, portion of exemplary tubular member 50, which can be an inner or an outer tubular member. Tubular member 50 includes fixation region 52, steerable portion 54, and a proximal neutral portion 58. Steerable portion 54 includes a plurality of slots 56 formed therein to define spine 55 extending along the steerable portion. Slots 56 are sinuous-shaped slots, and spine 55 has a generally straight configuration along the length of steerable portion 54. That is, spine 55 is substantially parallel with the longitudinal axis of the tubular member. Fixation region 52 includes a plurality of holes 57 to facilitate bonding to provide for axial fixation relative to a second tubular member (not shown). Proximal portion 58 includes a plurality of multiple overlapping slots 60 to provide the desired flexibility, axial force transmission, and torque transmission characteristics.

[0101] FIG. 4 illustrates a flattened, or unrolled, portion of exemplary tubular member 61, which can be an inner or an outer tubular member of a steerable portion. Tubular member 61 includes fixation region 62, steerable portion 64, and proximal neutral bending portion 68. Neutral bending portion 68 will exhibit minimal bending preference upon a compressive or tensile force applied thereto. Tubular member 61 is similar to tubular member 50 shown in FIG. 3, but includes linking elements 72, which can be flexible. Each linking element extends from one side of a slot to the other side. Each linking element includes two arm portions extending from one side of the slot to the other side of the slot. The two arms meet at the point at which they are connected to one side of the slot. The linking elements extend along steerable portion 64 on substantially the opposite side as spine 65. Linking elements 72 enhance and/or control torque response and bending of steerable portion 64. As steerable portion 64 is bent about spine 65, linking elements 72 bend and stretch under tension. As steerable portion 64 is twisted, or put in torque, linking elements 72 are put in compression. In torque, the gap between a given linking element and the section of the tubular member proximally adjacent to the given linking element collapses, effectively increasing the torsional stiffness of steerable portion 64.

[0102] FIG. 5 illustrates a flattened portion of exemplary tubular member 80, including fixation portion 82, steerable portion 84, and proximal neutral portion 86. The embodiment in FIG. 5 is similar to the outer tubular member as shown in FIGS. 2A and 2B. Steerable portion 84 includes substantially straight slots 90 that are substantially perpendicular to the longitudinal axis of tubular member 80. Spine 88 is substantially straight in configuration, extending along the length of steerable portion 84 substantially parallel to the longitudinal axis of the tubular member 80. Fixation portion 82 includes holes 92 therethrough (four shown) to facilitate bonding. Proximal portion 86 has multiple overlapping slots 94 to give the desired flexibility, axial force and torque transmission.

[0103] FIG. 6 illustrates a flattened portion of exemplary tubular member 96, including fixation portion 98, steerable portion 100, and proximal neutral portion 102. Steerable portion 100 includes substantially straight slots 108 that are substantially perpendicular to the longitudinal axis of tubular member 96, but each is offset relative to the adjacent slot so that spine 106 has a sinuous shape extending along the length of steerable portion 100. Fixation portion 98 includes holes 104 therethrough (four shown) to facilitate bonding. Proximal portion 102 includes multiple overlapping slots 110 to give the desired flexibility, axial force and torque transmission characteristics.

[0104] FIGS. 7A and 7B illustrate exemplary portions of flattened first and second tubular members 112 and 128. First tubular member 112 can be an inner tubular member and second tubular member 128 can be an outer tubular member, or first tubular member 112 can be an outer tubular member and second tubular member 128 can be an inner tubular member. Tubular members 112 and 128 can be assembled as part of a steerable delivery device. That is, one of the first and second tubular members can be disposed within the other. First tubular member 112 includes fixation portion 114, steerable portion 116, and proximal neutral portion 118. Fixation portion 114 includes holes 120. Steerable portion 116 has slots 124 formed therein to define spine 122. Spine 122 has a generally sinuous shape. Proximal portion 118 includes a plurality of overlapping slots 126. Second tubular member 128 includes fixation portion 130, steerable portion 132, and proximal neutral portion 134. Fixation portion 130 includes holes 136. Steerable portion 132 has slots 140 formed therein to define spine 138. Spine 138 has a generally sinuous shape. Proximal portion 134 includes a plurality of overlapping slots 142.

[0105] In FIGS. 7A and 7B, the slots in each of tubular members 112 and 128 are offset relative to the adjacent slot, interrupted, and have a general helical configuration. Spines 122 and 138 have generally sinuous configurations. The slots in the tubular members are at the same angle relative to the longitudinal axis of the tubular member, but are formed in opposite helical patterns. A advantage of having inner and outer tubular members with slots that are not in alignment (as opposed to inner and outer tubular members that have slots perpendicular to the longitudinal axis of the tubular member) is that the slots are less likely to get caught up on one another as the steerable portion is steered. The angled slots shown in FIGS. 7A and 7B also provide for an increased torque response based on a torque applied at the proximal end of the device.

[0106] FIG. 8 illustrates a portion of an exemplary steerable delivery device. Steerable device 150 includes outer tubular member 152, inner tubular member 154, and intermediate tubular member 156. A portion of outer tubular member 152 and intermediate member 156 are cut away to show inner tubular member 154. Intermediate tubular member 156 can be a flexible polymeric tube. Inner and outer tubes 152 and 154 have slots 160, 164 formed therein to define spines 158 and 162. The spines are substantially 180 degrees apart, as shown. The slots formed in the respective tubular members are at an angle relative to the longitudinal axis of the steerable portion and are formed in opposite helical patterns.

[0107] FIG. 9 illustrates a portion of an exemplary steerable delivery device. Steerable device 166 includes outer tubular member 168 and inner tubular member 170. Inner tubular member 170 can be a flexible polymeric tubular element. Outer tubular member 168 has a plurality of slots 174 formed therein to define spine 172. Inner tubular member 170 has no preferential bending axis. Inner tubular member 170 could alternatively have a modified bending axis offset by having, for example, a stiffening element incorporated into the wall of inner tubular member 170 approximately 180 degrees from spine 172. In some embodiments inner tubular member 170 may incorporate wire braids and or axially-laid wires which reduce kinkability and increase axial stiffness as is common in braided catheters or other similar known tubular medical devices.

[0108] FIG. 10 illustrates a portion of an exemplary steerable delivery device. Steerable delivery device 178 includes outer tubular member 180 and inner tubular member 182. Outer tubular member 180 can be, for example, a flexible polymeric tubular member. Inner tubular member 182 has a plurality of slots 186 formed therein to define spine 184, which is substantially parallel to the longitudinal axis of the steerable portion. Outer tubular member 180 has no preferential bending axis. Alternatively, outer tubular member 180 can have a preferential bending axis. For example, a structural support element can be incorporated into the wall of outer tubular member 180 approximately 180 degrees from spine 184. Outer tubular member 180 can be substantially the same as inner tubular element 170 in FIG. 9, but for any lubricity enhancing feature. In some embodiments inner tubular member 170 may incorporate wire braids and or axially laid wires which reduce kinkability and increase axial stiffness as is common in braided catheter or other similar known tubular medical device.

[0109] In an alternative embodiment, the device includes inner and outer slotted tubes, and additionally includes an outermost tubular member similar to 180 shown in FIG. 10. The outermost tubular member can be, for example without limitation, a polymeric tubular member.

[0110] FIG. 11A illustrates a portion of an exemplary embodiment of a first tubular member that can be included in a steerable delivery device. Tubular member 190 is a tubular member formed from a ribbon wire. Tubular member 190 has spine 192 formed by coiling a ribbon shaped with interlocking elements 194 and 196, which together form an interlocking feature along spine 192. Interlocking elements 194 and 196 may be press-fit to interlock the two. The interlocking elements can be encased with a tubular member, such as a polymer tubular member, to secure them in place. The interlocking elements can also, or alternatively, have a polymer tubular member disposed therein to help secure them in place. In addition to the interlocking features, the ribbon wire has sections of decreased width 198 which once wound into a tubular structure create the steerable portion for flexibility. A second tubular member of the steerable delivery device can be created in a similar manner to the tubular member in FIG. 11A. FIG. 11B illustrates an embodiment of the ribbon with interlocking elements 196 and decreased width regions 200 between elements 196. The angle of interlocking elements 196 relative to the longitudinal axis of the tubular element can be varied based on the pitch of the coil. Such a pattern can additionally be fabricated by laser machining.

[0111] FIGS. 12A and 12B illustrate an exemplary embodiment of a tubular member. Tubular member 210 comprises a tube 214 with grooves 212 formed therein on the outer surface of tube 214. Grooves 212 do not extend all the way through tube 214. Tubular member can be, for example, a stiff polymeric tubular member. FIG. 12A shows a sectional view of a portion of tubular 210 showing the depth of grooves 212 in the steerable portion. FIG. 12B illustrates a flattened view of tubular member 210 showing grooves 212 formed in tube 214. Grooves 212 define a single substantially straight spine 216. Grooves 212 cut into tube 214 increase flexibility of the steerable portion to allow the steerable portion to be steered. Spine 216 provides for the application of compressive and tensile forces to steer the device. Because the cut does not go all the way through the wall of the tube, it inherently creates a fluid tight barrier and a lubricious liner. In some embodiments tubular member 210 can an inner or outer tubular member of a steerable device, and the other of the inner and outer tubular elements can also includes a tubular element with grooves formed thereon. In some embodiments the steerable device can also have a polymeric sleeve to encapsulate the outer tube to create a smooth outer surface.

[0112] FIG. 13A illustrates a portion of an exemplary introducer sheath reinforcement member 220. Member 220 is formed by laser cutting a tubular member to slots or gaps therein. A helical slot 222 defines interlocking T-shaped patterns 224 formed in reinforcement member 220. The helical path is shown generally in helical path 226. Flexibility slots 228 are formed in member 220 to provide flexibility to member 220. Member 220 also includes bonding slots 230 formed therein to allow for bonding to one or more components of the device. FIG. 13B illustrates member 220 from FIG. 13A in a flattened pattern showing the interlocking T-shaped pattern along helical path 226, flexibility slots 228, and bonding slots 230. FIG. 13C shows a close-up of the section shown in FIG. 13B.

[0113] In some embodiments a guide catheter includes a relatively rigid metal or polymer reinforcement member (an example of which is shown in FIGS. 13A-13C layered between an inner and an outer flexible polymer tube. The rigid reinforcement member can be laser machined or otherwise cut in a pattern in order to enhance flexibility along the longitudinal axis of the tube, to allow some limited radial compliance, and to allow bonding of the inner and outer flexible polymers. The slot pattern can include an interlocking T-shaped pattern arranged helically around the tube for flexibility and radial compliance, a slot pattern where the slots are substantially perpendicular to the tube longitudinal axis, and are patterned along the tube longitudinal axis to further enhance flexibility and bonding of said layers.

[0114] FIG. 14 illustrates an exemplary embodiment of a guide system adapted to guide and deliver a therapeutic, diagnostic, interventional, or any other type of medical device 260 intraluminally to a target location within a body. Guide system 250 includes outer guide member 252 and steerable delivery device 256, a portion of which is disposed within outer guide member 250. Steerable delivery device 256 can be, for example, any of the steerable delivery devices described herein. Outer guide member 252 has a preset bend 254 that can be formed by, for example, heat setting. Steerable delivery device 256 includes steerable portion 258, which can be formed as, for example, any of the steerable portions described herein. For example, steerable delivery device can include outer and inner tubular members, wherein at least one of the tubular members is adapted to preferentially bend in a first direction. In the embodiment shown in FIG. 14, steerable portion 258 is comprised of a single steerable tubular member steered into the configuration shown in FIG. 14 by actuating pull wire 264. Alternatively, steerable delivery device 256 can be comprised of the embodiment described in FIG. 2, and steered by relative axial movement of inner and outer tubular members, as described herein.

[0115] Alternatively, outer guide member 252 can be adapted to be bent using optional pull wire 262, shown in FIG. 14. In such an embodiment bend 254 may or may not preset. Guide member 250 comprises a tubular member incorporating a pattern of slots as described for steering portions herein. When located in position pull wire 262 is tensioned and the axial and torsional stiffness of bend 254 is thereby increased. A steerable outer guide member 252 in its delivery configuration (non-bent) is generally loose and compliant, but is tensioned or compressed to reconfigure it into a pre-set shape. Its stiffness in the bent configuration is a function of the amount of tension or compression applied and the particular slot pattern chosen.

[0116] Bend 254 in outer guide member 252 is compliant enough to be straightened for delivery, for example advanced on a guide wire, but rigid enough to be able to guide steerable delivery device 256 around bend 254. Steerable delivery device 256 is steerable and transmits torque.

[0117] The structural properties of the inner and outer tubular members of the steerable delivery device will determine the manner in which they respond to force applied thereon. The structural properties of the inner and/or outer tubes will depend on the tubing material and the design, or characteristics, of the slots created in the tubular members (unless one of the inner and outer tubular members does not have any slots therein). The design of the slot pattern is therefore a function of the required structural properties of the tubular member. For example, structural properties of the tubular member that can be modified by changing the design of the slots or slot patterns include flexural stiffness, torque transmission, steerability, radius of curvature, and allowable wall thickness of the steerable assembly.

[0118] FIG. 15 is a flattened view and illustrates a portion of an exemplary steerable portion of a tubular member. Tubular member 290 can be an inner or an outer tubular member as described herein. Steerable portion 290 is typically a laser-cut tubular member, but may in fact be fabricated by any technique capable of creating the appropriate widths of cuts required (e.g., water jet, wire EDM, etc.) wherein first cut, or slot, 292 is made, defined by first surface 294 and second surface 296. Slot 292 extends almost all the way around tubular member 290, and defines spine 308. Slots 282 are thickest, along the tubular longitudinal axis, along compression axis C which allows tubular member to be compressed along compression axis C, which changes the configuration of tubular member 290. Tubular member 290 also includes interlocking features 298 (only one of which is labeled), which include first interlocking element 300 and second interlocking element 302. Slot 292 includes slot portion 304, which is defined by the first and second interlocking elements 300 and 302 and allows for movement between the two interlocking elements 300 and 302 in the axial direction. Tubular member 290 also includes stress relief slots 306, which extend across spine 308 and provide stress relief for spine 308. Stress relief slots 306 can be considered to be axially in-between slots 292. Slots 292 are not connected with slots 306. Slots 306 are substantially thinner than slots 292. As will be described in detail below, tubular member 290 is adapted to be compressed along compression axis C, which is substantially 180 degree from spine 308.

[0119] FIGS. 16A and 16B illustrate a portion of tubular member 290 shown in FIG. 15. FIG. 16B illustrates tubular member 290 with slot 292, with a greatest thickness along compression axis C. Slot 292 includes slot 304, which is defined by interlocking elements 300 and 303. Slot 292 and slot 304 allow for compression of tubular member 290, shown in FIG. 16A. When a compressive force A is applied along compressive axis C surfaces 294 and 296 are brought closer towards another, as are surfaces 300 and 302. Slots 292 and 304 therefore allow for axial compression of tubular member 290, until surfaces 294 and 296 engage one another, or until surfaces 300 and 302 engage one another, whichever happens first. Slots 292 and 304 can be designed such that the slots close at the same time. Once the surfaces engage, they behave substantially like a solid tube and can no longer be compressed along the engagement points. In this configuration, the first and second interlocking elements are adapted to prevent movement therebetween at least along a first axis, in this embodiment along compression axis C. Upon a compressive force to tubular member 290, tubular member will therefore be steered into the configuration shown in FIG. 16A. Similarly, when a tensile force is applied to tubular member 290 shown in FIG. 16A, tubular member 290 will straighten to the configuration shown in FIG. 16B. Particularly, tubular member 290 will straighten until the interlocking features engage one another and prevent further movement. FIG. 16C illustrates the tubular member from FIGS. 16A and 16B and indicates points of load application including those illustrated in FIGS. 16B and 16C. Torsional force T indicates a torsional force acting on tubular member 290 upon the application of torque at a proximal end of the device. Tensile and compressive forces are listed as “a” or “b” depending on the behavior exhibited by the tubular member as described below.

[0120] FIG. 17 is a graph illustrating Force v. Displacement behavior associated with the application of loads or displacements at various points around tubular member 290 shown in FIGS. 15-16C. The Force/Displacement behavior of tubular member 290 for loads applied in planes passing through the longitudinal axis of the tubular member, ranges between the lines A and B in FIG. 17. Curve A illustrates the behavior along a compliant axis on the surface of the tubular member and parallel to the longitudinal axis of the tubular member where the slots are widest, while curve B illustrates the behavior where the slots are very narrow. As the tubular member is bent about spine 308 in a fashion which closes slots 292, the forces required to bend the tubular member are low and the Force/Displacement curve has a small slope. The tubular member is compliant in this region. When the width of the slots decreases to zero the structure becomes much stiffer as indicated by the second much higher slope region of curve A. The amount of displacement associated with closing the slots is essentially indicated by point D where the slope of the Force/Displacement curve changes. Curve A indicates the behavior expected from forces applied at a point along compressive axis C, illustrating that a large amount of axial displacement follows from minimal compressive force on tubular member 290. Upon closing slots, the compressive axis becomes stiff (indicated by the large increase in Force at point D in the curve). Curve B in the graph indicates compression along the axis running through spine 308. Due to stress relief slots 306, a small amount of compressive displacement occurs before spine 308 stiffens and begins to act substantially like a solid tube, as indicated by point E in the graph. The structure will exhibit the behavior of curve B for tensional loads applied to the top of the structure on the compressive axis C as the gaps closed under this loading are very narrow. Curve B also represents the behavior of the structure to torsional loads, as the gaps impacted most by these loads are narrow.

[0121] FIG. 18 illustrates a flattened view of exemplary tubular member 320. Slot 330, or cut, formed therein has a spiral (also referred to herein as helical) pattern and is un-interrupted. Tubular member 320 is shown in an as-cut compressed configuration, and is adapted to be expanded the greatest amount along expansion axis EA upon the application of a tensile force thereto. Tubular member 320 includes interlocking features 332, which include surfaces 322 and 324, and surfaces 326 and 328. Slot 330 includes the slot defined by surfaces 326 and 328, and by surfaces 322 and 324. In this embodiment the slot, or gap, defined by surfaces 326 and 328 is larger than the gap defined by surfaces 322 and 324. That is, the gap that is closer to expansion axis EA is larger than the gap that is further from expansion axis EA. Tubular member 334 also includes spine 334, which is interrupted by small slots 336. As illustrated in FIG. 16C, tubular member 320, upon the application of axial loads applied thereto, will exhibit Force/Displacement curves as follows: a compressive force (downwards) applied at EA will exhibit curve B, while a tensile load at EA (upwards) will exhibit curve A. A torsional load will exhibit curve B.

[0122] FIG. 19 is a flattened view and illustrates a portion of a tubular member. Tubular member 270 can be an inner or an outer tubular member as described herein. Steerable portion 270 is a laser-cut tubular member wherein first cut, or slot, 274 is made to define spine 276. Cut 274 is made almost all the way around tubular member 270. Cut 274 also defines interlocking features 278 (only one of them is labeled), which are comprised of a first interlocking element 280 and a second interlocking element 282. Cut 274 includes cut 284, which creates the interlocking features and allows for movement between the two interlocking elements. Tubular member 270 also includes stress relief 272, which extend across spine 276 and provide stress relief for spine 276. Stress relief slots 272 can be considered to be axially in-between slots 274. Slots 274 are not connected with slots 272. Tubular member 270 is adapted to be expanded along expansion axis EA, and is adapted to be minimally compressible upon the application of compressive forces thereto. Spine 276 is substantially static. Upon the application of tensile forces to tubular member 270 along expansion axis EA, tubular member 270 will deflect from a straightened configuration into a bent configuration.

[0123] FIG. 20 illustrates an embodiment similar to that shown in FIG. 18 and only differences in the structure between the two will be described. All other features can be considered the same. Tubular member 350 includes interlocking features including interlocking elements 354 and 356. Slot 360 created in tubular member 350 includes the gap defined by surfaces of interlocking elements 354 and 356.

[0124] FIG. 21 illustrates a flattened portion of an exemplary tubular member 380 including interrupted cuts 390 that define spine 382. Tubular member 380 includes interlocking features 384, which include interlocking elements 386 and 388. Interlocking features 384 allow for expansion along expansion axis EA upon the application of a tensile force thereto. Tubular member 380, like all tubular members described herein unless specifically stated otherwise, can be incorporated into a steerable portion as an inner or an outer tubular member.

[0125] FIG. 22 illustrates a flattened portion of an exemplary tubular member 400. Interrupted slots 404 define spine 402, which has a spiral shape. Tubular member 400 does not have static axis.

[0126] FIG. 23 illustrates a flattened portion of an exemplary tubular member 410. Tubular member 410 includes interrupted helical slots 418, which define spines 412 and 414. Tubular member 410 has two spines, 180 degrees around the periphery of the device from one other. The helical cut pattern repeats itself every 180 degrees to define substantially straight spines. Tubular member 410 also includes a plurality of interlocking features 420 which provide torsional stiffness. The maximal expansion/compression is at axis 416.

[0127] FIG. 24 illustrates a flattened portion of an exemplary tubular member 430, which is similar to the embodiment in FIG. 23 but rather than repeating every 180 degrees, the cut pattern repeats every 360 degrees. Slots 434 have an interrupted helical design, and tubular member 430 has a single spine 432. Feature 436 provides additional torsional stiffness. Tubular member 430 exhibits maximal expansion/compression along axis 438.

[0128] FIG. 25 illustrates a flattened portion of an exemplary tubular member 440. Tubular member 440 includes slots 448, which repeat every 190 degrees to define spines 442 and 446. The slots have an interrupted helical pattern, and create a relatively neutral pattern.

[0129] FIG. 26 illustrates a flattened portion of an exemplary tubular member 450. Tubular member 450 has uninterrupted slot 456 formed therein, which repeats every 360 degrees. Tubular member 450 also includes interlocking features 454 comprised of at least two interlocking elements as described herein. In this embodiment, the interlocking elements have complimentary curved surfaces and are adapted to support rotation. Slot 456 defines spines 452, while slot 456 allows compression and/or expansion along axes A.

[0130] FIG. 27 illustrates an exemplary steerable delivery device including steerable portion 520. Steerable delivery device includes outer tubular member 522, inner tubular member 524, and floating inner member 534. Inner tubular member 524 is disposed within and coaxial to outer tubular member 522, and floating inner member 534 is disposed within and coaxial with inner tubular member 524. Floating inner member 534 is axially fixed relative to inner tubular member 524 at a location proximal to steerable portion 520. The device shown in FIG. 27 can also include a liner member disposed between the outer and inner tubular members.

[0131] FIG. 28 illustrates an exemplary steerable delivery system 600. System 600 includes control device 602 that is adapted to steer steerable portion 610 of a steerable delivery device. The steerable delivery device includes outer tubular member 606 and inner tubular member 608 disposed within outer tubular member 606. Control device 602 includes housing 612 with a slot therein adapted to allow for movement of actuator 604. Actuator 604 is coupled to inner tubular member 608, and is adapted to be moved axially, either distally D or proximally P to control the axial movement of inner tubular member 608. Any other suitable type of actuator can also be used including actuators incorporating mechanical advantage. Actuation of actuator 604 causes inner tubular member 608 to move axially relative to outer tubular member, which causes steerable portion 610 to bend. The control device is therefore adapted to steer steerable portion 610 inside of a subject. System 600 also includes a floating liner member 616 and hemostatic valve 614.

[0132] One aspect of the disclosure is a guide device that is adapted to be maintained, or locked, in a specific configuration to provide access for a medical device or instrument to be passed therethrough, but may or may not be steerable. In FIGS. 2A-2C, steerable portion 32 is adapted to be steered or deflected into any configuration between those shown in FIGS. 2A and 2B. Steerable portion is adapted to be steered to, for example, navigate bends or turns within a bodily lumen. In that specific embodiment, compressive and/or tensile forces are applied to the inner and/or outer tubular members to steer the steerable portion. In some embodiments, once steerable portion 32 is steered into a curved configuration, the forces applied thereto (e.g., compressive, tensile, torsional) can be released, and yet a medical device or instrument can be passed through the tubular members. In some embodiments, however, the bent configuration of the steerable portion can be maintained by maintaining the application of the forces thereto. For example, in FIGS. 2A-2C, steerable portion 32 can be maintained, or locked, in the bent configurations shown by maintaining the application of the compressive and/or tensile forces. By maintaining the application of the forces to the steerable portion or locking the relative displacements of the inner and outer tubes, the inner and outer tubes are substantially axially fixed relative to one another along the length of the steerable portion.

[0133] In an exemplary method of use, multiple bend portions may be incorporated and adapted to have a locked configuration that closely mimics, or resembles, a portion of the subject's anatomy. The bend portion can be advanced through the subject (e.g., over a guide wire) to a desired location, and can then be actuated into a curved configuration, such as by the application of compressive and/or tensile forces thereto. The curved configuration can be adapted to resemble the path of the anatomical lumen in which the device is positioned. Application of the actuation force maintains, or stiffens, the bend portions in the desired curved configuration. A medical device or instrument can then be advanced through the curved portion to a target location within the subject.

[0134] The device shown in FIG. 14 can alternatively be configured to be operated in this manner. For example, steerable delivery device 256 in FIG. 14 can be actuated to have a first bend or curved region 254 and a second bend or curved region 258. The curves, or bends, form a general S-shaped portion of the device. The delivery device 256 can be maintained, or locked, in the general S-shape to guide a medical device or instrument therethrough. The S-shape of the delivery device 256 can be used if it resembles a portion of the anatomy into which it is placed, but any other type of preformed configuration can be used, depending on the anatomical requirements. In the alternative to FIG. 14, the delivery device can be actuated into the configuration shown by the application of compressive and/or tensile forces to inner and outer tubular members, as is described herein.

[0135] FIGS. 29A and 29B illustrate an exemplary embodiment of a portion of a lockable device adapted to be locked, or maintained, in a specific configuration that mimics that of a portion of the subject's anatomy. In the unlocked form the structure is compliant and easily guidable whereas in the locked form the device is rigid in its predetermined form. The device can then be used to provide access for a medical device or instrument to be passed therethrough to a target location within the subject. Bend portion 700 of the device includes a plurality of beads, 702, 704, and 706. Bead 702 is the distal-most bead, bead 706 is the proximal-most bead and beads 704 are disposed between the two end beads 702 and 706. The beads are separate and distinct structural features, not mechanically coupled to one another. Each bead has two bores 715 therethrough, each adapted to receive one of the two control wires 708. Control wires 708 are secured only to distal bead 702, using any suitable technique (e.g., adhesive). Wires 708 therefore are adapted to be axially moveable relative to beads 704 and 706. Proximal bead 706 has a substantially constant height H around the periphery of the bead, while beads 702 and 704 do not have a constant height. Specifically, the height of the beads 702 and 704 decreases around a portion of each of the beads. The gap between adjacent beads is therefore relatively large between bead 702 and 704, and between beads 704, while the gap between bead 706 and the adjacent bead 704 is relatively small compared to the other gaps.

[0136] To adjust the lockable portion into its predetermined form, an axially directed (i.e., distally directed) compressive force C is applied to proximal bead 706 while maintaining wires 208 is position. Maintaining wires 208 in position can occur based on a proximally directed tensile force applied to wires 208, or wires 208 may be secured to a portion of the delivery system that is not actuated. This causes the distance between surfaces 711 and 713 to decrease, until they engage one another as shown in FIG. 29B. The actuation force is continued until all of the beads' adjacent surfaces are engaged, as shown in the configuration in FIG. 29B. In FIG. 29B, lockable portion 700 is in a bent configuration adapted to mimic a portion of the patient's anatomy in which it is to be positioned. FIG. 29B also shows a section portion of one side of the beads through which one of wires 708 passes. Lockable portion is maintained in the locked configuration in FIG. 29B by maintaining the distally directed compressive force to proximal bead 706 or the relative displacements between distal bead 702 and proximal bead 706. Lockable portion 208 can also be bent into the configuration shown in FIG. 29B upon the application of a proximally directed tensile force applied to wires 708, while applying a distally directed compressive force to proximal bead 706. While six beads are shown in FIGS. 29A and 29B, the lockable portion can have two or more beads.

[0137] FIGS. 30A-30H show exemplary beads that can be incorporated into a lockable portion as described herein. FIG. 30A illustrates bead 716 with wire bores 717 therethrough. The height H of bead 716 is substantially constant. When the height is substantially constant, the planes through the proximal and distal ends of the beads are substantially parallel. When the height is not constant, the planes are not parallel. Bead 716 is the same as proximal bead 706 in FIG. 29A. In an embodiment with a lockable portion comprised entirely of beads that have a constant height, the lockable portion would have a straight configuration under compression. FIG. 30B shows bead 718 with bores therethrough, wherein the height at portion 720 is less than at portion 721. Bead 718 has the same general shape as beads 702 and 704 in FIG. 29A. The height of portion 720 can be adjusted to modify the curvature of the lockable portion. Generally, as height 720 decreases, the degree of the bend increases (i.e., the radius of curvature decreases). Similarly, the height of portion 721 can be modified to modify the curvature. FIG. 30C illustrates bead 722 that can be injection molded. Bead 722 includes two outer wire features 724 and two inner wire features 726 formed in bead 722. Each outer wire feature has a portion that overlaps with a portion the corresponding inner wire feature to define an opening through which a control wire can pass. Molding the bead with the wire features to create the wire bore can be easier than forming a hole the entire way through the bead. Bead 722 is formed to have 2 control wires pass therethrough. FIG. 30D illustrates bead 730 that can be injection molded. Bead 730 includes two indentations 732 and two indentations 734. The indentations in bead 730 allow for the height of wire bore 736 to be less than it would be without the indentations. The indentations can make the wire bores easier to mold. FIG. 30E illustrates bead 740 including tabs 742 stamped therein. The tabs are stamped in the body of bead 740 to form wire openings 744, through which a control wire is passed. Bead 740 can be, for example, a hypotube, sheet metal rolled into an annular shape, etc. FIG. 30F is similar to FIG. 30E and includes interlocking features including interlocking elements 754 (male) and 756 (female). The interlocking features generally enhance torque transmission. The interlocking feature could be comprised of any interlocking elements described herein or any other suitable interlocking elements. FIG. 30G illustrates bead 760 including an inner corrugated member 764 and outer member 762. The spaces between inner member 764 and outer member 762 define control wire bores 768, which are adapted to receive control wires therethrough. In FIG. 30G, twelve control wires can be passed through bead 760. FIG. 30H shows a plurality of beads 760 (from FIG. 30G) and 770, each with inner member 764 and outer member 762. In adjacent beads 760 and 770, the control wire bores are defined by peaks and valleys formed in the inner members on adjacent beads.

[0138] While the embodiments have been shown with control wires being secured relative to a single bead, all of the control wires in a lockable portion need not be secured to the same bead. For example, a control wire can be secured to any bead in the lockable portion.

[0139] The locked configuration of the lockable portion can be modified by modifying characteristics of the beads. For example, the number of beads in the lockable portion can be modified to change the radius of curvature. The height of portion of the beads can be modified, as shown in the comparison between FIGS. 30A and 30B. The lockable portion additionally need not include beads of the same type. For example, a lockable portion could alternate the beads shown in FIGS. 30A and 30B, creating a curve with a degree of bend less than that shown in FIG. 29A. Beads of similar design can be rotationally offset from one another along the length of the lockable portion. For example, in the embodiment in FIG. 29A, every other bead could be rotated 90 degrees in the same direction relative to the adjacent beads. Additionally, the relative angle between the control wire bore axis and the plane of a bead end can be adjusted. For example, in FIG. 30B, the axes of control wire bores 719 can be substantially 90 degrees relative to the plane of the distal end of bead 718. The axes of bores 719, can, however, be offset such that they are not substantially 90 degrees relative to the plane of the distal end of bead 718.

[0140] The beads as described herein can have almost any length. In some embodiments a bead is a section of straight tubing. Any bead can also incorporate any of the slotted cut patterns described herein

[0141] While the lockable portions have been shown to include curved, or bent sections, the lockable device can have a locked configuration in which the device is substantially straight. For example, if the lockable device included 2 or more beads as shown in FIG. 30A, the lockable device would have a substantially straight locked configuration.

[0142] In some embodiments the lockable device could have a floating liner (as described herein) disposed therein. The floating liner could, in some embodiments, secured to the distal-most bead. The lockable device could alternatively or additionally have an outer liner disposed on the outside of the lockable device. The outer liner could also be secured to the distal-most bead or the outer liner could be affixed to the inner liner and the beads left to float inside.

[0143] In some embodiments the lockable device (e.g., the device shown in FIGS. 29A and 29B) is adapted to be advanced over a steerable device within the subject. For example, a traditional guidewire or the steerable device shown in FIGS. 2A-2C can be steered to a desired location within the subject. A lockable device, such as a beaded lockable device described herein, can then be tracked over the steered device. The lockable device comprising at least two beads is flexible to allow it to follow the curvature of the steered device. Once the lockable device has been advanced over the steered device to the desired position, the beads of the lockable device are locked in place as described herein, and the lockable device assumes its preset configuration.

[0144] In alternative embodiments, the lockable portion (e.g., the beaded structure in FIGS. 29A and 29B) includes a floating liner therein. In an exemplary embodiment of use, a guiding element (e.g., a guidewire) is advanced to a desired location within the subject. The device comprising the lockable portion is then tracked over the guiding element until it reaches a desired position. The lockable portion is then actuated to change the configuration of the lockable portion to the desired configuration. The lockable portion is then maintained, or locked, in the desired configuration. A medical device, medical instrument, or other device is then advanced therethrough to a target location within the subject.

[0145] FIGS. 31-34 depict an alternative embodiment of a steerable delivery device. FIGS. 31-34 illustrate steerable delivery sheath 810 adapted to bend in two directions within a pre-defined and controlled plane and having an improved torqueability and bend retention. Sheath 810 is comprised of outer tubular member 820, inner tubular member 830, and two tensioning members 841. Three cross-sections of catheter 810 in sections A-A, B-B, and C-C as indicated in FIG. 31 are shown in FIGS. 32-34. Sheath 810 has a distal steerable portion 814 including a distal section, a cross section of which is depicted in section A-A in FIG. 32. Distal portion 814 also includes a proximal section, a cross section of which is depicted in section B-B in FIG. 33. A cross-section of a proximal portion 813 (relative to the distal portion 814) of sheath 810 is shown in section C-C in FIG. 34.

[0146] Inner tubular member 830 has three discrete components along its length except in the distal section of distal portion 814. Inner tubular member 830 comprises an innermost layer 831, which in this embodiment is a lubricious liner, and can include PTFE. Innermost layer 831 is wrapped with braided material 832, which in turn is covered and impregnated by outer layer 833. The outer surface of inner liner 831 and/or the braided layer 832 can be surface treated to enhance the bonding between these structures and inner liner 831. In some embodiments the material used for outer layer 833 can be a free flowing thermoplastic polymer such as, for example without limitation, PEBAX. The mechanical properties of inner tubular member 830 can be modified by adjusting the particulars of the braid, including but not limited to, size and shape of the fiber, the composition of the fiber, the weave pattern, overlay structure, and any other suitable property. In some embodiments inner layer 831 is a PTFE tube, braided material 832 has a herring bone pattern, and outer layer 833 is PEBAX. In these embodiments the structure is relatively stiff in tension and compression.

[0147] Outer tubular member 820 also has three discrete components along its length except in the distal section of distal portion 814. Outer tubular member 820 includes inner layer 821, which in this embodiment is a lubricious liner, braided layer 822 surrounding inner layer 821, and an encapsulating and impregnating outer layer 823. In some embodiments used in conjunction with the specific embodiment of inner tubular member 830 described above, inner layer 821 is a PTFE tube, braided layer 822 has a diamond pattern, and outer layer 823 is PEBAX. In this specific embodiment, the outer tubular member is less stiff in tension but better resists kinking during bending. This construction also provides for a lubricious interface between the inner and outer tubular members 830 and 820. In other embodiments the braided material in the outer member can also be in a herring bone configuration.

[0148] The length of distal portion 814 corresponds to the arc length of the desired maximum bend for steerable sheath 810. Distal portion 814 of sheath 810 is comprised of materials that are more compliant than those in proximal portion 813 of sheath 810. The diamond pattern of braided layer 822 in the specific embodiment described above is a one-over/one-under pattern wherein the weave structure can include one or more wires.

[0149] In some embodiments both the inner and outer tubular members include braided components with the same general pattern (e.g., both herring, both diamond). In some embodiments the two tubular members include braided components with different general pattern (e.g., one herring, one diamond). In some embodiments only one tubular member includes a braided component. In some embodiments neither tubular element includes a braided element. The braided material in one tubular member can have different characteristics than the braided material in the other tubular member, such as a different number of wires, different sized wire, etc. Additionally, the braided material within a single tubular element can have different characteristics along the length of the braided material.

[0150] In some embodiments in which one or more tubular members include a braided material with a herring bone pattern, the pattern is a 2-over/2-under pattern, wherein the weave structure is either single or multiple wires. In some embodiments both inner and outer tubular members may use the same pattern and in others the patterns may be different as may be required by the design constraints.

[0151] Tables 1 and 2 below describe component properties based on axial location for two exemplary embodiments of a 2-way steerable sheath. The embodiment of Table 2 describes a device in which the outer tubular member has a braided material in the proximal and central portions of the tubular member, but does not have a braided material in the distal section. The braided material transitions into a cut metal tube structure in the distal section, which essentially replaces the braid in the distal section, as is described in more detail below. Tables 1 and 2 also indicate exemplary ranges for the polymer hardness for PEBAX tubing in the exemplary inner and outer tubular members, indicated as Shore D durometer.

TABLE 1
2-way steerable sheath	Proximal	Central/Middle	Distal
Inner sheath
Liner	1 to 2 mil PTFE	1 to 2 mil PTFE	1 to 2 mil PTFE
Braided Material	Herring	Herring	Herring
PEBAX (Durometer)	70 to 80	50 to 70	20 to 40
Outer Sheath
Liner	1 to 2 mil PTFE	1 to 2 mil PTFE	1 to 2 mil PTFE
Braided Material	Herring	Herring	Herring
PEBAX (Durometer)	70 to 80	50 to 70	20 to 40

TABLE 2
2-way steerable sheath	Proximal	Central/Middle	Distal
Inner sheath
Liner	1 to 2 mil PTFE	1 to 2 mil PTFE	1 to 2 mil PTFE
Braided Material	Herring	Herring	Herring
PEBAX (Durometer)	70 to 80	50 to 70	20 to 40
Outer Sheath
Liner	1 to 2 mil PTFE	1 to 2 mil PTFE	1 to 2 mil PTFE
Braided Material	Herring	Herring	None
Cut Tube	None	None	Patterned
PEBAX (Durometer)	70 to 80	50 to 70	20 to 40

[0152] As indicated in Tables 1 and 2, the durometer of the PEBAX tubing decreases from the proximal region towards the distal region. This provides for enhanced bending in the steerable section. The proximal portion of the steerable sheath will typically not be required to overly bend to accommodate the natural contours of the vasculature, and as such a relatively stiff structure comprised of higher durometer polymers will generally be preferred. The central portion of the sheath will often be required to follow a somewhat more tortuous anatomical path but is stiff enough to transmit the forces required to facilitate the steering of the distal end. The distal section is configured to minimize trauma and maximize steerability.

[0153] In the distal section of distal portion 814 (shown in section A-A in FIG. 33), the two tubular members 820 and 830 are merged together, which causes them to be permanently axially fixed in the distal section. Along the remainder of the length of sheath 810 proximal to where they are axially fixed, the two tubular members are separated by space 843 and as such are free to move longitudinally relative to one another. Tensioning members 841 are constrained differently along the length of sheath 810. In the distal section of the sheath (section A-A shown in FIG. 32), tensioning elements 41 are completely constrained by being embedded in polymer layer 823 (which is where inner and outer tubular members are merged together), as shown in FIG. 32. Through the remainder of the sheath proximal to this location, tensioning elements 841 are disposed between inner and outer tubular member 830 and 820 in annular space 843, and hence are free-floating longitudinally but are constrained radially. In the proximal section of distal steerable portion 814 (section B-B in FIG. 33), however, tensioning members 841 are additionally constrained circumferentially in channels 842 formed in outer layer 833 of inner tubular member 830. The channels extend along the inner tubular member along a plane which includes the longitudinal axis of the inner tubular member in its unbent, or unsteered, configuration. These channels may be open to space 843, as shown in FIG. 33, or may incorporate a section of tubing completely or partially encapsulated by the outer layer 833. Along the remainder of the sheath, tensioning members 841 are not constrained circumferentially.

[0154] In this embodiment distal portion 814 of sheath 810 is the steerable portion, and can be bent or steered in one of two directions by pulling one of tensioning members 841 while maintaining nominal tension on the other. Sheath 810 will bend towards the pulled tension member. In this manner distal portion 814 of sheath 810 can be bent or steered in one of two directions about the longitudinal axis in the plane described by the embedding locations of the tensioning members 841 and parallel to the longitudinal axis of the catheter. In alternative designs (not shown), tensioning members 841 are constrained circumferentially along the entire length of sheath. For example, tensioning members 841 could be constrained circumferentially along the entire length of sheath by constraining them in channels shown in FIG. 33, wherein the channels extend along the entire length of the device. In this alternative design, however, the sheath would suffer from a phenomenon known in the art as “whipping.” This phenomenon occurs when the sheath is rotated around its longitudinal axis while the sheath is not in a straight configuration, as is typically the case when the sheath is in use and is disposed in a contoured configuration that follows a path defined by some anatomical structure. As the sheath is rotated around the longitudinal axis, the path length of the different pull wires will vary due to the one or more bends in the sheath. The variation in path lengths will causes the sheath to become unstable, and it can quickly change rotational position, which is disconcerting to the physicians. Additionally, the variation in path lengths will cause the angle of bend at the distal tip to vary as a function of the longitudinal rotation for a fixed tension member setting. Thus, when in use, as the physician is rotating the device, the degree of bend undesirably will change. This can also be very disconcerting to the physician who needs to readjust the bend to compensate for the change associated with the rotation. If, on the other hand, the tensioning members are left unconstrained as indicated in FIG. 34, both whipping and the change in bend radius are minimized. These are two exemplary advantages of this and other applicable embodiments described herein. However, in this configuration the plane in which the distal portion 814 bends will vary as a function of the rotation and tortuosity of the path. This results since the tensioning member will seek the shortest path to their distal termination point, as they are unconstrained circumferentially. This in turn allows them to lay in or pass through different planes than those described by the longitudinal axis of the sheath and the plane within which the sheath bends as that described by the tensioning member. The distal portion 814 will also tend to corkscrew in this situation for similar reasons.

[0155] By circumferentially constraining the tensioning members 841 only along the steerable portion of the sheath, as in the embodiment shown in FIGS. 31-34, the issues described above are obviated. When two tensioning members 841 are used as described in this embodiment, they may alternatively be terminated and constrained along planes which do not include the longitudinal axis. In such situations the bending will be bi-directional, but the bending action will not fall in a single plane. Additionally, although not shown in the embodiments presented herein, more than two tensioning members can be included, thereby allowing the sheath to bend in more than one plane.

[0156] FIGS. 35-40 show an alternative embodiment of a steerable delivery device. FIGS. 35-40 illustrate steerable delivery sheath 900 capable of bending in one direction with torqueability and bend retention enhancements better than those of the embodiment in FIGS. 31-34. FIG. 40 is an enlarged view of a distal-most portion of sheath 900. Sheath 900 includes inner tubular member 930 and outer tubular member 920, respectively. Cross sections of sheath 900 are represented in FIGS. 36-39. Locations of cross sections are indicated as sections A-A, B-B, C-C, and D-D as indicated in FIG. 35. Construction of sheath 900 in proximal portion 913, shown in cross section D-D shown in FIG. 39, is similar to the proximal portion for sheath 810. Table 3 describes component properties for an exemplary embodiment of the sheath shown in FIGS. 35-40. As in sheath 810, the distal-most portions of the inner and outer tubular members 930 and 920 are merged together, as is shown in section A-A in FIG. 36. In section A-A they are thus permanently axially fixed. Inner tubular member 930 includes three discrete components—inner layer 931, braided layer 932, and outer layer 933. In this embodiment inner layer 931 is a lubricious liner, layer 932 is a braided material embedded in PEBAX outer layer 933. Outer tubular member 920 includes inner layer 921, intermediate layer 922, and outer layer 923. In this embodiment, inner layer 921 is a lubricious liner, intermediate layer 922 is a braided material embedded in outer PEXAX layer 923.

[0157] In contrast to sheath 810, however, inner sheath 930 incorporates an additional stiffening element 945 that provides stiffness, only in tension, along the axis falling on the plane within which the distal end of the sheath bends. The proximal end of stiffening element 945 is embedded in the outer polymer layer 933 of the inner tubular member 930 at a location in a distal portion of the proximal portion 913 of the inner tubular member 930, as shown in FIG. 39. Stiffening element 945 is free floating in the annular space 943 between inner tubular member 930 and outer tubular member 920 throughout the remaining portion of proximal portion 913, as well as in distal bendable portion 914 of sheath 900 up to a point at the distal end of distal portion 914 where the distal portion of stiffening element 945 is embedded in outer polymer layer 923, which is shown in section A-A in FIG. 36. Stiffening element 945 is located in the plane through which the distal end of sheath 900 bends and is located on the inside radius of the bend. In some embodiments stiffening element 945 is a multi-stranded Kevlar line. In some embodiments the proximal end of stiffening element is secured to the outer layer of the inner tubular member at a location that is closer to the steerable portion of the device than a proximal end of the inner tubular member.

[0158] Distal portion 914 is the steerable portion of sheath 900 and is constructed as follows. In the proximal region of distal portion 914 (section C-C), the braid in layer 922 is replaced by a tubular structure with cutouts, and can be a metal tubular structure. The cutouts allow for the controlled variation in the bending stiffness of the outer tubular member in different planes which extend through the longitudinal axis. The cutout pattern may additionally incorporate features to enhance torsional stiffness.

[0159] In this embodiment element 925 is a part of the spine of pattern cut tube 922 and 927 is an aperture passing through all layers of the device.

TABLE 3
1-way steerable sheath	Proximal	Central/Middle	Distal
Inner sheath
Liner	1 to 2 mil PTFE	1 to 2 mil PTFE	1 to 2 mil PTFE
Braided Material	Diamond	Diamond	Diamond
PEBAX (Durometer)	70 to 80	50 to 70	20 to 40
Outer Sheath
Liner	1 to 2 mil PTFE	1 to 2 mil PTFE	1 to 2 mil PTFE
Braided Material	Herring	Herring	None
Cut Tube	None	None	Patterned
PEBAX (Durometer)	70 to 80	50 to 70	20 to 40

[0160] A representation of the performance of such a tube with cutouts is depicted in FIG. 41 where curve 951 represents the stiffness in compression along axis on the periphery of the tube parallel to the longitudinal axis of the cut tube. The stiffness is represented on a polar plot where r represents the stiffness and theta the angle around the longitudinal axis pointing at the measurement axis. One embodiment of a cut-out pattern incorporating both controlled variation in bending stiffness and features which enhance torsional stiffness is represented as a flat pattern in FIG. 42.

[0161] Bending in the steerable portion 914 of steerable sheath 900 occurs by axially translating the inner and outer tubular members relative to each other along the longitudinal axis. In some embodiments this is accomplished by fixing the outer sheath 920 to a handle or external controller incorporating an internal mechanism that is adapted to translate inner tubular member 930. As inner tubular member 930 is translated distally relative to outer sheath 920, compressive forces are applied to outer sheath 920. These compressive forces cause distal portion 914 of sheath 900 to bend in the direction of its most compliant axis, indicated by 929 in FIGS. 40, 41 and 42. As illustrated stiffening element 945 is adjacent to axis 929 and provides additional tensional stiffness to inner sheath 930 on this axis while allowing the opposed axis 928 to stretch. Sheath 900 in FIG. 40 additionally incorporates a radio opaque marker 927 at its distal end. One or more of these markers may also be incorporated in sheath 810 shown in FIGS. 31-34. 926 is a cut out in layer 922 through which polymer can pass, as shown in FIG. 37. The section with the square cutouts is completely embedded in polymer, hence all of the material is secured together at the distal end in FIG. 40 allows for the delivery of fluid from within the sheath to outside the sheath when the distal end of the sheath is plugged as might occur when the device is used to deliver a balloon which is inflated after delivery through the sheath and pulled back against the distal end.

[0162] In the embodiments shown in FIGS. 31-34 and 35-40, the inner and outer tubular members may be rotated relatively to one another, thereby causing the bent distal end of the sheath to rotate in a generally circular arc as shown in FIG. 43. This allows for more control of the distal tip by very finely torquing just the distal end. This type of control minimizes whipping to an even greater degree.

[0163] FIG. 44 illustrates an exemplary steerable device that can be controlled as described herein. The device includes an exemplary external actuatable component incorporated into a handle at its proximal end. The handle includes a first actuator at its distal end that is adapted to be actuated (e.g., rotation) to deflect, or steer, the tip as described herein. The handle also includes a second actuator at its proximal end that is adapted to be actuated (e.g., rotation) for fine tune torque adjustment as described in FIG. 43.

[0164] FIGS. 45-47 illustrate an exemplary external controller, in the form of a handle, that is adapted to deploy and actuate the steerable devices described herein. The external controller is adapted, or can be adapted to control other steerable devices not specifically described herein. FIGS. 45 and 46 illustrate the proximal portion of an exemplary steerable sheath system 1000 that includes steerable sheath 1100, such as those described above, and handle portion 1200 for actuating steerable sheath 1100. Handle portion 1200 includes sheath flexure adjustment knob 1210, grip 1220, guide wire port 1230, inner lumen purge port 1240 leading into central lumen 1150. Flexure, or steering, of the steerable sheath is facilitated by twisting control knob 1210 relative to handle grip 1220. The amount of flexure of the sheath is related to the amount of rotation of adjustment knob 1210. In some embodiments there will be a relatively linear correspondence between the degrees of rotation of control knob 1210 and the angle of flexure for the sheath steerable section. In such an embodiment each unit of incremental rotation of the control knob 1210 substantially equals or “maps” into a corresponding and constant unit of incremental flexure for the sheath steerable portion, independent of the starting flexure of the steerable sheath. In alternate embodiments there can be a nonlinear correspondence. For example, in an exemplary configuration when the steerable section is at minimal flexure, control knob 1210 can impart twice as much flexure as when it is at about 50% of its allowable flexure.

[0165] Other mappings are considered here although not described in detail. FIG. 46 illustrates a cross-sectional view of handle portion 1200 of FIG. 45 at a midline plane. Situated at the proximal end is guide wire pass-through 1230 which sits proximal to guide wire seal 1250 leading into central lumen 1150.

[0166] Additional features comprising the control mechanism 1330 are also shown. Control knob 1210 sits over drive nut 1330 and is constrained against rotation relative to the drive nut by drive nut feature 1380. Control knob 1210 and drive nut 1330 in turn are positioned concentrically around drive screw 1310. Outer sheath interface tube 1340 sits concentrically within the drive nut 1330.

[0167] Outer shaft 1110 is anchored to the outer sheath interface tube at 1140. Anchoring may be accomplished with adhesives, ultrasonic welding, heat staking or other suitable means. Inner shaft 1120 is anchored at 1130 to inner sheath interface tube 1370 via any of the mechanisms described for the outer sheath.

[0168] Handle housing 1220 feature 1320 passes through a proximal end of outer sheath interface tube 1340 constraining it from both rotation and axial displacement. Pins 1320 additionally ride in the drive screw stabilizing slot feature 1350 of drive screw 1310 pictures in FIG. 47. FIG. 47 depicts a portion of control mechanism 1300 with housing features removed. As control knob 1210 is rotated, drive nut 1330 is constrained to rotate with it via features 1380 and corresponding feature within the control knob, not shown. Since drive screw 1310 is constrained against rotation by the drive screw stabilizing pin 1320 riding in slot 1350, rotation of drive nut 1330 is translated into a linear motion for drive screw 1310. Drive screw thread 1360 may comprise a constant pitch or a variable pitch. Since the inner shaft is anchored to the inner sheath interface tube which in turn is constrained from moving axially relative to screw 1310, this in turn will be translated into axial motion of the inner sheath relative to the outer sheath and result in flexure, or steering, of the steerable portion of the device.

[0169] An exemplary aspect of the disclosure includes embodiments that facilitate the visualization of portions of the steerable sheath when used in a navigation system, such as the St. Jude NavX Navigation & Visualization Technology, or other impedance-based methods associated with identifying relative positions of system components within a living or deceased body.

[0170] FIG. 48 illustrates the distal end of an exemplary steerable sheath. Steerable sheath 1400 comprises features of catheter 1100 and is adapted for use with a handle as described herein, such as handle 1000. Indicated on sheath 1400 are straight non-steerable section 1417 and steerable section 1418. Steerable section 1418 is shown in a curved configuration. Sheath 1400 as illustrated additionally comprises a plurality of electrodes 1401 separated by spaces 1402. Spaces 1402 of uniform length are indicated in section 1405 and spaces of non-uniform length are illustrated in section 1404. As illustrated the steerable section 1418 comprises section 1405 and the non-steerable section 1417 comprises section 1404. Sheath 1400 comprises any combination of the usage of sections 1405 and/or sections 1402. Such embodiments include multiple or alternatively no sections of one or the other of sections 1405 and 1404. Sections 1405 and 1404 may have different electrode spacing. The non-uniform spacing of electrodes section 1404 may be monotonically varying or may vary in non-monotonic fashion. The use of different electrode spacing can be used to identify different sections of the sheath during the visualization. Often impedance measurements will be obtained between individual electrodes and pads located at specific points on the surface of the body thereby providing information regarding the position of the sheath electrodes relative to the pads. In some instances the impedance between electrodes will be measured to indicate whether one portion of the sheath is on one side of a body structure while another portion of the sheath is on another side of a body structure. Such a system would have utility in uses where devices are being passed through the septum of the heart.

[0171] Any of the methods of depositing conductive and insulative material described in U.S. Provisional Application No. 61/541,765, filed Sep. 30, 2011, which is incorporated by reference herein, may be used to manufacture any of the devices described herein.

[0172] The electrodes may be comprised of elastomeric inks and elastomeric insulators, examples of which can be found in U.S. Provisional Application No. 61/541,765. An exemplary configuration of electrodes on a sheath is shown in FIGS. 49 and 50. In FIG. 49 a sheath such as sheath 1100 is illustrated as a flat pattern, i.e. where the width is equal to the circumference of the sheath, and additional layers of elastomeric conductive ink and elastomeric insulation material have been applied in such a fashion as to comprise electrodes such as those described above. FIG. 50 depicts a cross-section of one of the electrodes illustrated in FIG. 49. In the illustration of FIG. 49 all of the layers are illustrated as if they were transparent. In an exemplary method of manufacturing, individual traces 1507 are first applied to the outer surface of the sheath such that each terminates at a location near an electrode. Next, an insulation layer is applied wherein the insulation layer is masked at points 1506 near the distal ends of the traces 1507. Electrodes 1501 comprised of a conductive elastomer are then applied such that the electrode 1501 is in electrical contact via the masked area 1506 in the elastomeric insulator 1508 with conductive trace 1507.

[0173] As depicted in these illustrations the electrodes have annular configurations circumscribing the sheath. In alternate embodiments the shape of the electrodes may comprise other forms such as squares circles or other shapes where the electrode does not transcribe the circumference of the catheter. In any of these configurations the surface area of the electrodes can be designed to advantage relative to the impedance characteristics without impacting the flexibility and performance of the steerability features of the system. In such embodiments the electrodes may be arranged such that they are all on one side of the sheath such as on the outer edge of the curve of a steerable section. Such electrodes may also be arranged such that they are distributed uniformly or non-uniformly around the circumference. Alternatively, multiple electrodes may be placed on the same circumference, in this fashion it is possible to characterize how a catheter section is interfacing with local tissues. In some configurations the most distal portion of the sheath is an electrode comprising an atraumatic tip feature. Such an electrode can provide information on the type of tissue in contact with the tip, for instance connective versus cardiac tissue. The composition of the electrodes may be modified to enhance their visibility under x-ray by the addition of more radio opaque materials such as PtIr, Tungston, or other commonly used materials.

[0174] The elastomeric nature of electrodes and other electrical and insulative components has minimal impact on the steering and delivery performance of the steerable device. Apart from positional mapping and tissue identification, the electrodes herein may also be placed near appropriate target tissue within the heart and used for pacing the heart.

[0175] FIGS. 51A and 51B illustrate alternative conductor patterns for interfacing with electrodes on the outer surface of exemplary steerable sheaths. In FIG. 51A, delivery device 1600 includes steerable and non-steerable portions. Device 1600 includes electrode 1602, conductor 1606 and insulation material 1604. Conductor 1606 extends generally parallel to the longitudinal axis of the steerable portion. In FIG. 51B, the steerable portion of device 1610 (and the non-steerable portion(s)) includes conductor material 1616 in a spiral, or helical, configuration, and insulation material 1614.

[0176] FIG. 52 illustrates an exemplary steerable portion 1620 of a steerable device. The dimensions shown are intended to be merely exemplary and are not limiting in any way. The device includes a proximal portion 1630 and a distal portion 1632. Steerable portion 1620 includes four generally annular electrodes 1626 individually electrically coupled to individual traces 1624, which are each electrically coupled to individual connectors 1622. Connectors 1622 are adapted to be inserted into any suitable navigation system such that electrodes 1626 can be used to determine the position of the steerable portion 1620 within a patient. The proximal-most electrode includes a break, or discontinuity, in the annular configuration through which the other three traces extend. Similarly, the central two electrodes have a discontinuity in their annular configuration, allowing one or more traces to extend therethrough. The distal-most electrode does not have a discontinuity as there are no electrodes located distal to that electrode. More or less than four electrodes can be used, and the electrodes need not have generally annular configurations.

[0177] When a steerable device includes one or more tubular members, as in the embodiments described above, the distal section of one or more of the tubular member can sometimes compress, or shorten, when it is actuated to straighten the tip of the steerable device. For example, in the embodiments above which include an inner tubular member disposed within an outer tubular member, the distal section of the inner tubular member may sometime compress, or shorten, when it is pushed in relative to the outer tubular member to straighten the steerable portion from a bent configuration towards a straighter configuration. In some of these embodiments, the proximal section of the inner tubular member has a greater durometer (e.g., 72 D) than the steerable portion (e.g., 35 D). The lower durometer allows the steerable portion to bend. The shortening, when it occurs, is an inefficient use of the displacement of the inner tubular member that is necessary to deflect the steerable device.

[0178] FIGS. 53A-53G illustrate an exemplary embodiment that reduces or eliminates the shortening. In this embodiment, the region of the inner tubular member disposed on the inside of the curve in the steerable portion and the distal tip has a higher durometer than the rest of the inner tubular member in the steerable portion and distal tip. FIGS. 53B-53D show cross-sections through sections A-A, B-B, and C-C as indicated in FIG. 53A. Device 1650 includes inner tubular member 1652, outer tubular member 1654, and tensioning element 1660. Outer tubular member 1654 has the same durometer along the length of the outer tubular members. In section C-C, the inner tubular member includes a first portion 1658 with a first durometer. In sections B-B and A-A, the inner tubular member includes first portion 1658 with the first durometer and a second portion 1656 with a second durometer lower than the first durometer. First portion 1658 makes up about ¼ of the inner tubular member in cross section. First portion 1658 is radially within tensioning member 1660 that is used to transfer tension from the proximal section of the tubular member to the tip of the device. The higher durometer in the portion on the inside of the curve prevents the shortening of the inner tubular member when actuated. FIG. 53G shows section G-G of the distal section indicated in FIG. 53E. First portion 1658 can be seen on the inside of the curve radially within tensioning element 1660. In one specific embodiment first portion 1658 is 72 D PEBAX, and second portion 1656 is 35 D PEBAX. These numbers are exemplary and are not intended to be limiting.

[0179] FIGS. 54A-54D illustrate an alternative embodiment in which device 1700 includes inner tubular member 1702 and outer tubular member 1704. Inner tubular member 1702 has first section 1708 with a first durometer and a plurality of second sections 1706 with a second durometer lower than the first durometer. In this embodiment, the steerable portion (section B-B) and distal tip (section A-A) of the inner tubular member include two higher durometer sections 1708. In this embodiment neither of the higher durometer sections 1708 is radially within tensioning member 1710, and as such neither of sections 1708 is on the inside of the curve. The two higher durometer sections 1708 are substantially opposite each other around the circumference of the inner tubular member, and are each about 90 degrees apart from tensioning element 1710.

[0180] In some of the embodiments set forth above, the deflection of the steerable portion is limited by the travel of the inner tubular member or the pull wire, if one is used. FIG. 55A illustrates an exemplary embodiment in which the displacement of the inner tubular member can be increased. In FIG. 55A inner tubular member 1804 is actuated to steer the device. Device 1800 includes wire element 1806. The distal end of wire 1806 is secured to the distal end of inner tubular member 1804. The proximal portion of wire element 1806 is wrapped around pulley 1808 and is secured to the outer shaft at location 1810. Pulling on pulley 1808 tensions wire element 1806 and pulls on inner tubular member 1804. The displacement of inner tubular member is two times the displacement of pulley 1808.

[0181] In FIG. 55B, device 1850 includes outer tubular member 1852, inner tubular member 1854, wire element 1856, and pulley 1858. The proximal end of wire element 1856 is attached to the outer tubular member 1852. The distal end of wire element 1856 is attached to inner tubular member 1854. Pulling on the pulley tensions wire element 1856. The displacement of wire element 1856 is two times the displacement of pulley 1808.

[0182] While preferred embodiments of the present disclosure have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the disclosure. It should be understood that various alternatives to the embodiments of the disclosure described herein may be employed in practicing the disclosure. The following claims define the scope of the disclosure and that methods and structures within the scope of these claims and their equivalents are covered thereby.