Medical device with controllably actuated fixation, friction reduction and device motion - Patents.com

Abstract

A catheter system and method utilizes a catheter (100) with strategically configured actuators positioned thereon to provide electronically actuated anchoring, friction reduction, and / or motive force by altering the shape and / or stiffness of the catheter for moving the catheter within a body lumen, such as a blood vessel. The catheter includes an elongated flexible tubular member (12) having one or more actuators (114a, b, c, e, f, g) positioned on the tubular member. The actuators are configured to alter the shape and / or stiffness of the tubular member to provide various control functions including anchoring the catheter, reducing friction during catheter movement, and / or propelling the catheter within the body lumen. The actuators may be electronically actuable electroactive polymer actuators, mechanical actuators actuated by mechanical means such as pull wires, hydraulic or pneumatic actuators actuated by fluid pressure, or combinations thereof.

Description

[Technical field]

[0001] The disclosed invention relates generally to medical devices and methods for performing procedures within a lumen of a patient's vasculature, and more particularly to catheters, sheaths and / or guidewires having actuators, such as mechanical, hydraulic, thermoresistive or electroactive polymer actuators, that modify the stiffness and / or shape of the catheter to provide an actuatable function, such as a force-inducing function or an electronically actuatable function, for use within the vasculature, and methods of using the same. [Background technology]

[0002] Various designs of medical devices have been disclosed to perform various medical procedures, including interventional therapy, drug delivery, diagnosis, perfusion, and the like. Generally, a medical sheath, catheter, or guidewire is used by introducing a distal end of the device into a patient's vascular system, such as a vein or artery, from an entry site of the patient. For example, a catheter is advanced from the entry site by guiding and pushing a proximal portion of the catheter to advance the catheter through the vascular system to a target site to perform a therapeutic and / or diagnostic medical procedure. The vascular pathway to the target site is often tortuous, and the catheter must follow a path that bends and changes direction. A user (typically a physician) must steer the catheter when advancing it by manipulating (e.g., twisting and rotating) the catheter and / or by steering the distal end along the vascular pathway using a pull wire or other steering mechanism coupled to the distal end.

[0003] An example of an intravascular catheter is a guide catheter. Guide catheters are used to guide other instruments to a desired location within the vascular system. Generally, guide catheters include an elongated, flexible tubular member and may have a steering mechanism, such as a pull wire. One common type of guide catheter is a balloon guide catheter, which also includes a balloon member secured to the tubular member. The balloon is attached to a distal portion of the tubular member or other suitable location. The balloon can provide any of a number of useful functions, including fixing the guide catheter in place after it has been advanced to a target site, sealing the vessel lumen at the balloon location (e.g., blocking fluid flow), and / or performing a therapeutic procedure, such as dilating the vessel, compressing an occlusion, etc. The balloon guide catheter also includes an inflation lumen extending from the proximal end of the tubular member to the inflatable balloon for injecting an inflation fluid to inflate the balloon and releasing fluid pressure to deflate the balloon.

[0004] Various designs have been disclosed for steering and reshaping catheters. Some of these designs utilize electroactive polymer actuators located on the catheter and a control unit connected to the actuator that selectively transmits electrical control signals to the actuator that cause the actuator to change the configuration of the catheter. For example, U.S. Pat. No. 7,261,686 describes a guide catheter having electroactive polymer actuators located along its axial length, where the actuators change the shape and / or stiffness of the guide catheter based on control signals received from the control unit. U.S. Pat. No. 7,261,686 explains that the actuators can be used to change the shape of the guide catheter to conform to the patient's anatomy, controllably steer the catheter as it is inserted, and stiffen the catheter. Similarly, U.S. Pat. No. 8,920,870 describes a catheter system that includes a catheter having sections of electroactive polymer at different locations on the catheter that can be actuated by control signals to hinge, bend, rotate, expand or contract the catheter sections, or increase the stiffness of the areas surrounding the sections to improve the pushability of the catheter. Summary of the Invention

[0005] The disclosed invention is directed to devices with strategically configured and positioned actuators to provide actuated fixation, friction reduction and / or motive force to move the device within a body lumen such as a blood vessel. The actuators may be electromechanical actuators actuated by electrical signals, mechanical actuators actuated by mechanical means such as pull wires, hydraulic or pneumatic actuators actuated by fluid pressure, or combinations thereof. Although the description of the disclosed embodiments is directed to guide catheters used for the insertion and positioning of therapeutic devices within a patient's vasculature, it is understood that the disclosed invention is not limited to guide catheters, but may be used with any suitable catheter, sheath or guidewire. For example, the catheters described herein may be any suitable type of device, including guide catheters, balloon guide catheters, diagnostic catheters, therapeutic catheters, access sheaths, guide sheaths, dilators, guidewires, stylets, and the like.

[0006] In one embodiment, a catheter system includes an elongated flexible tubular member with an anchor portion having inherent flexibility and one or more actuators disposed on the tubular member. As used herein, the term "disposed on" means that a first structure is mounted on, integrated with, applied to, or otherwise attached to a second structure. The tubular member has an anchor portion having inherent flexibility. For example, the tubular member is typically highly flexible to navigate tortuous paths within a body lumen. The one or more actuators are disposed along the axial length of the tubular member and may be disposed at different circumferential / circumferential positions. The one or more actuators are configured to change the stiffness of the anchor portion in an anchor shape configured to fix the anchor portion in a fixed position in the body lumen corresponding to the anchor shape when the actuator is actuated. The one or more actuators have an unactuated state that allows the tubular member to have its inherent flexibility, and an actuated state in which the actuators are actuated, in which the one or more actuators stiffen the anchor portion into an anchor shape configured to secure the anchor portion in a fixed position within a body cavity corresponding to the anchor shape.

[0007] The catheter system has an unactuated configuration in which the one or more actuators are unactuated so as not to significantly affect the stiffness and / or shape of the anchor portion of the tubular member. In other words, the anchor portion of the tubular member has its relaxed shape and / or inherent flexibility. The catheter system also has an actuated configuration in which the one or more actuators are actuated, thereby stiffening the anchor portion in an anchor shape configured to fix the anchor portion in a fixed position in a body lumen corresponding to the anchor shape. The anchor shape is configured to fix the anchor portion in a fixed position in a body lumen corresponding to the anchor shape. This fixation resists movement of the tubular member, thereby preventing the tubular member from moving longitudinally within the body lumen. Thus, instruments and other catheters can be moved and manipulated through the tubular member while the tubular member is fixed in position by the anchor shape.

[0008] For example, the body cavity can have a curved shape (e.g., an S-shape corresponding to the petrous carotid artery, or the path across the aortic arch to a branch vessel), and when the anchor portion is hardened to the curved shape of the body cavity, the anchor portion can be fixed in place to resist longitudinal movement of the tubular member.

[0009] In various embodiments of the catheter system, one or more actuators can also be configured to change the shape of the anchor portion. For example, the actuator can also be configured to form the anchor portion into an anchor shape. Thus, the actuator simultaneously forms the anchor portion into the anchor shape and stiffens the anchor portion into the anchor shape. In the above example of an S-shape, the actuator is configured to form the anchor portion of the tubular member into the anatomically corresponding S-shape.

[0010] In various embodiments of the catheter system, the one or more actuators can include a mechanical actuator that is actuated by one or more pull wires coupled thereto. In one embodiment, each mechanical actuator includes an actuator element having an anisotropic region about a central axis of the tubular member, a first area having a first compliance and a second area having a second compliance different from the first compliance, such that compressive loading of the actuator element by the one or more pull wires causes the actuator element to bend and stiffen to a preset shape. The anisotropic region can be formed by a tube, such as a hypotube, having a cut pattern that imparts the first compliance to the first area and the second compliance to the second area.

[0011] In other embodiments of the catheter system, the actuators can comprise other types of mechanical actuators actuated by mechanical means such as pull wires, hydraulic or pneumatic actuators actuated by fluid pressure, or combinations thereof. Representative examples include: actuator elements that are mechanically driven using linear tension or compression elements incorporated within the device, where when a force is applied to them, the force causes asymmetric elastic length contraction or expansion of separate structures within the device at the location of the desired shape change. In another example, the actuators are mechanically driven using rotatable concentric pre-curved elastic tubes that constitute the primary reinforcement of the device, where the rotation and / or stretching of the tubes relative to each other elastically reinforces or offsets their inherent curvature to change the shape of the device along its length.

[0012] In one example of a fluidic actuator, the actuator is fluidically driven via fluid connections incorporated into the device to allow for the expansion or evacuation of fluid cavities incorporated within the device and can impart dimensional changes via one or more of: direct pressure-induced elastic length expansion or contraction of elements and / or cavities asymmetrically positioned within the device at the location of the desired shape change; and / or osmotically driven elastic length expansion or contraction of cavities asymmetrically positioned within the device separated from the fluid cavity by a membrane at the location of the desired shape change.

[0013] In additional embodiments of the catheter system, the actuator may be another type of electrical actuator, for example, the actuator may be electrically driven using electrical conductors embedded in the device to induce bending forces through one or more of applying a potential difference to a resistive material to change its temperature and thereby change its shape, applying a potential difference to an electroactive polymer to change its shape, and / or applying a potential difference to a piezoelectric material to change its shape.

[0014] Another embodiment of the disclosure is directed to a method of using a catheter system. The method includes inserting a distal end of the catheter system and advancing the catheter within a body lumen to a target location with one or more actuators unactuated and the anchor portion having inherent flexibility. Activating the actuator can stiffen the anchor portion into an anchor shape and fix the anchor portion in place within the body lumen. The stiffened anchor portion fixes the catheter in place within the body lumen. This maintains the position of the catheter such that other catheters and / or instruments can be inserted through the catheter without the catheter moving from its fixed position.

[0015] The method may also include actuating the actuator to form the anchor portion into the anchor shape, if the actuator is also configured to form the anchor portion into the anchor shape.

[0016] In yet additional disclosed embodiments, the actuator comprises an electroactive polymer. The use of electronically actuable electroactive polymers allows the catheter to be electronically controlled, which may include computer control. Local electronic actuation of electroactive polymer actuators also minimizes the impact on remote portions of the catheter, such as the proximal shaft, as opposed to pull wire technology. The use of electroactive polymer actuators also allows for multiple actuators to be used and more complex actuator placements. Electronic actuation also allows the catheter to have programmable dynamic shapes and configurations, with the added ability to sense the strain environment at the actuator by measuring the capacitance or induced voltage of the electroactive polymer when in a non-actuated state.

[0017] In these embodiments, the catheter system utilizes strategically configured electroactive polymer actuators located on and / or within the catheter to provide electronically actuated anchoring, friction reduction, and motive force to move the catheter within a body lumen, such as a blood vessel. The use of electronically actuable electroactive polymers allows the catheter to be electronically controlled, which may include computer control. Local electronic actuation of electroactive polymer actuators can also minimize impact on remote portions of the catheter, such as the proximal shaft, as opposed to pull wire technology. The use of electroactive polymer actuators also allows for multiple actuators to be used, and more complex actuator placements. The use of electronic actuation also allows for the catheter to have programmable dynamic shapes and configurations. The use of electronic actuation can also allow for the catheter to have strain sensing and feedback control to induce a catheter shape that matches or mimics the surrounding anatomical lumen shape.

[0018] The electroactive polymer actuators employed in the embodiments described herein utilize electroactive polymers, also known as "conductive polymers." Actuators that utilize electroactive polymers are advantageous in the catheters disclosed herein because they can generate large forces and strains while being very compact. Additionally, electroactive polymers are relatively low cost and relatively easy to incorporate into the catheters disclosed herein.

[0019] Electroactive polymers are a form of polymer that has the ability to change shape in response to an electrical stimulus, i.e., an electrical signal. Dimensional changes in electroactive polymers can occur through mass transfer of ions into and out of the polymer. Thus, the movement of ions into or out of an electroactive polymer results in dimensional changes, such as expansion or contraction due to ion intercalation and / or interchain repulsion between the polymer chains. Thus, based on their properties, electroactive polymers can be used to provide electroactive polymer actuators. Electroactive polymer actuators are activated and deactivated by application and removal of electrical control signals to the actuator. The actuators can then be applied to a structure to apply forces to the structure that can change the physical properties of the structure, such as changing the shape, dimensions, stiffness, and / or position of the structure.

[0020] In an exemplary embodiment utilizing electroactive polymer actuators, a catheter system includes a catheter having an elongated flexible tubular member and one or more electroactive polymer actuators disposed on the tubular member. The tubular member has an anchor portion having inherent flexibility. For example, the tubular member is typically highly flexible to navigate a tortuous path within a body lumen. The one or more electroactive polymer actuators can be disposed along an axial length of the tubular member as well as at different circumferential / circumferential locations. The one or more electroactive polymer actuators are configured to modify the stiffness of the anchor portion in an anchor configuration configured to secure the anchor portion in a fixed position within a body lumen corresponding to the anchor configuration in response to one or more electrical control signals.

[0021] Thus, the catheter system has an unactuated configuration in which the electroactive polymer actuators are not actuated, in other words, the electroactive polymer actuators are not actuated by electrical signals, such as voltage and / or current, and are in a relaxed configuration in which they do not significantly affect the stiffness and / or shape of the anchor portion of the tubular member, i.e., the anchor portion of the tubular member has its inherent flexibility.

[0022] The catheter system also has an actuation configuration in which one or more electroactive polymer actuators are actuated by one or more control signals, such as voltage and / or current. The control signals cause the electroactive polymer actuators to stiffen the anchor portion in an anchor shape, i.e., the actuators increase the stiffness of the anchor portion from the inherent flexibility of the tubular member. The anchor shape is configured to fix the anchor portion in a fixed position within the body lumen corresponding to the anchor shape. This allows instruments and other catheters to be moved and / or manipulated through the tubular member while the tubular member remains stationary due to the anchor shape.

[0023] As an example, the body lumen can have a curved shape (e.g., an S-shape corresponding to the petrous carotid artery) and when the anchor portion is hardened in the curved shape of the body lumen, the anchor portion can be fixed in place to resist longitudinal movement of the tubular member. Other catheters or instruments can then be guided through the tubular member to a target site within the body lumen while the catheter remains fixed in place.

[0024] In various embodiments of the catheter system, one or more electroactive polymer actuators can also be configured to change the shape of the anchor portion. For example, the electroactive polymer actuator can also be configured to form the anchor portion into an anchor shape. In this manner, the electroactive polymer actuator simultaneously forms the anchor portion into the anchor shape and stiffens the anchor portion into the anchor shape. In the above example of an S-shape, the electroactive polymer actuator is configured to form the anchor portion of the tubular member into an S-shape.

[0025] In various other embodiments, the catheter system can further include a controller operably connected to the plurality of electroactive polymer actuators. The controller is configured to selectively transmit electrical control signals to the plurality of electroactive polymer actuators to alter a configuration of the tubular member, such as altering the stiffness and / or shape of the anchor portion. The electrical control signals can be voltages applied to each of the electroactive polymer actuators. The controller can be connected to the one or more electroactive polymer actuators using a plurality of conductors, such as wires, conductive traces, etc., disposed on the tubular member. Each conductor has a first end connected to a respective electroactive polymer actuator and a second end connected to the controller.

[0026] In another embodiment, the controller can sense the strain on the actuator via induced voltage or capacitance change, thereby interpreting the curvature of the device at the sensed actuator location, and thereby the anatomical shape that the unactuated device resides in. The controller can then apply a signal to the sensed actuator to induce a shape change that mimics the shape of the interpreted anatomical lumen, thereby achieving an anchor shape that conforms to the anatomical shape, without prior knowledge of the anatomical shape of the anchor location.

[0027] In various embodiments, the electroactive polymer actuator can include a parylene film, hi other embodiments, the electroactive polymer actuator includes any suitable electroactive polymer, such as parylene, polyaniline, polypyrrole, polysulfone, or polyacetylene.

[0028] Another aspect of the disclosed invention is directed to a method of using the above-described exemplary embodiment of a catheter system. The method includes inserting a distal end of the catheter into a body lumen and advancing the catheter to a target location within the body lumen with one or more electroactive polymer actuators deactivated such that the anchor portion of the tubular member has its inherent flexibility, thereby allowing the catheter to be advanced through the body lumen in a flexible state. Once the catheter is at the target location, the electroactive polymer actuators are activated using a control signal to stiffen the anchor portion into an anchor shape. The stiffened anchor portion anchors the catheter within the body lumen. This maintains the catheter in a fixed position such that other catheters and / or instruments can be inserted through the catheter without the catheter moving from its fixed position.

[0029] The method may also include actuating the electroactive polymer actuator to form the anchor portion into the anchor shape, when the electroactive polymer actuator is also configured to form the anchor portion into the anchor shape.

[0030] The method may further include one or more of the other aspects of the catheter system described above.

[0031] Another embodiment of a catheter system utilizing electroactive polymer actuators is directed to a catheter system configured to utilize electroactive polymer actuators to reduce stiction of a catheter as the catheter moves longitudinally within a body lumen. In this embodiment, the catheter system includes a catheter having an elongated flexible tubular member and a plurality of electroactive polymer actuators disposed on the tubular member. The plurality of electroactive polymer actuators are configured to form the tubular member into a substantially sinusoidal shape and cycle the sinusoidal shape back and forth between a substantially sinusoidal shape with a phase shift of 0° and a substantially sinusoidal shape with a phase shift of 180° (i.e., transition the sinusoidal shape back and forth from a phase shift of 0° to a phase shift of 180°). In other words, the shape of the tubular member cycles such that the peaks of the sinusoidal shape move to valleys and vice versa.

[0032] The catheter system also includes a controller operatively connected to the plurality of electroactive polymer actuators, the controller configured to send control signals to the plurality of electroactive polymer actuators to dynamically cycle the tubular member back and forth between a substantially 0° out-of-phase sinusoidal shape and a substantially 180° out-of-phase sinusoidal shape.

[0033] Thus, as the catheter system is moved longitudinally within the body lumen, the multiple electroactive polymer actuators are actuated to dynamically cycle the tubular member back and forth between a substantially sinusoidal shape that is 0° out of phase and a substantially sinusoidal shape that is 180° out of phase. This cyclical sinusoidal motion of the tubular member breaks down static friction of the tubular member as the catheter is moved longitudinally, thereby requiring less force to move the catheter and making the catheter move more smoothly.

[0034] In various friction reduction embodiments, the controller is configured to dynamically cycle the sinusoidal shape of the tubular member at an amplitude, peak-to-peak wavelength, and cycling frequency that reduces the stiction of the tubular member as it is moved longitudinally within the body lumen. For example, the amplitude and wavelength can be set to be just enough to destroy the stiction, while the frequency can be set so as not to damage the walls of the body lumen or cause other undesirable side effects.

[0035] In various embodiments of the friction reduction, the electroactive polymer actuators are arranged in one particular configuration that provides a sinusoidal shape. The plurality of electroactive polymer actuators includes a first set of electroactive polymer actuators and a second set of electroactive polymer actuators. On a first side of the tubular member, the first set of electroactive polymer actuators are arranged longitudinally along the tubular member and are interleaved with a second set of electroactive polymer actuators arranged longitudinally along the tubular member on the first side. Similarly, on a second side of the tubular member opposite the first side, the first set of electroactive polymer actuators are arranged longitudinally along the tubular member and are interleaved with a second set of electroactive polymer actuators arranged along the tubular member on the second side. Furthermore, the first set of electroactive polymer actuators are arranged such that the electroactive polymer actuators on the first side are offset from the electroactive polymer actuators on the second side. Similarly, the second set of electroactive polymer actuators are arranged such that the electroactive polymer actuators on the first side are offset from the electroactive polymer actuators on the second side. In one aspect, a first set of electroactive polymer actuators on a first side are positioned opposite a second set of electroactive polymer actuators on a second side, and the first set of electroactive polymer actuators on the second side are positioned opposite the second set of electroactive polymer actuators on the first side, or vice versa. The electroactive polymer actuators are configured such that actuation of the first set of electroactive polymer actuators changes the shape of the tubular member to a substantially sinusoidal shape that is 0° out of phase, and actuation of the second set of electroactive polymer actuators changes the shape of the tubular member to a sinusoidal shape that is 180° out of phase.

[0036] In another aspect of the friction reduction embodiment, a first set of electroactive polymer actuators are electrically connected to a controller via a first pair of electrical conductors such that all of the electroactive polymer actuators in the first set are actuated by a single first signal from the controller. Similarly, a second set of electroactive polymer actuators are electrically connected to the controller via a second pair of electrical conductors such that all of the electroactive polymer actuators in the second set are actuated by a single second signal from the controller. The second pair of electrical conductors are electrically isolated / separated from the first pair of electrical conductors. Thus, the multiple electroactive polymer actuators can be actuated to dynamically cycle the tubular member back and forth between a substantially 0° out-of-phase sinusoidal shape and a substantially 180° out-of-phase sinusoidal shape by alternating between the first and second signals.

[0037] Another aspect of the disclosed embodiments is directed to a method of using an embodiment of a friction reduction catheter system within a body lumen. The method includes inserting a catheter into the body lumen. The catheter is moved longitudinally within the body lumen while a controller sends control signals to a plurality of electroactive polymer actuators to dynamically cycle the tubular member back and forth between a substantially 0° out-of-phase sinusoidal shape and a substantially 180° out-of-phase sinusoidal shape. The cycling sinusoidal motion of the tubular member breaks static friction of the tubular member as the catheter is moved longitudinally.

[0038] In various embodiments, the method of using the friction reduction embodiment of the catheter further includes one or more of the other aspects of the second embodiment of the catheter system described above.

[0039] Another embodiment of a catheter system utilizing an electroactive polymer actuator is directed to a catheter system configured to utilize an electroactive polymer actuator to shape a tubular member into substantially continuous circumferential contact with a wall of a body cavity, thereby stabilizing the catheter. The catheter system includes an elongated flexible tubular member and an electroactive polymer actuator disposed on the tubular member in a helical path along the tubular member. Actuating the helically disposed electroactive polymer actuator using an electrical control signal changes the shape of the tubular member to a substantially helical shape, allowing the tubular member to circumferentially contact the wall of the body cavity along a length of the tubular member sufficient to stabilize the tubular member within the body cavity. For example, the circumferential contact can prevent longitudinal movement of the catheter within the body cavity and / or can center or otherwise prevent movement of the catheter within the body cavity, similar to the anchoring function of the first embodiment.

[0040] In various helical embodiments, the catheter is configured such that the substantially helical shaped tubular member circumferentially contacts the wall of the body lumen along a selected discrete length of the catheter or along substantially the entire insertable length of the tubular member. For example, the catheter may be configured to have the electroactive polymer along a length beginning at a first distance from the distal end of the catheter and ending at a second, longer length from the distal end of the catheter, or the catheter may be configured to have the electroactive polymer along substantially the entire length of the tubular member except for the proximal end that remains outside the body.

[0041] In various helical-shaped embodiments, the catheter system can further include a controller operably connected to the electroactive polymer actuator, the controller configured to selectively transmit control signals to the electroactive polymer actuator.

[0042] In various embodiments of the helical shaped device, the one or more actuators can include a mechanical actuator actuated by one or more pull wires coupled to the mechanical actuator. In one embodiment, a series of actuatable mechanical structures are arranged in series along the length of the device, each mechanical structure including an anisotropic actuatable element (hence a preferred bending direction relative to the axis), the actuatable elements being rotatably arranged in series around and along a central axis of the device in a helical path, such that compressive loading of the series of actuatable elements by one or more pull wires causes the device to bend and stiffen into a helical shape. The series of mechanical structures and corresponding anisotropic elements can be formed in a tube, such as a hypotube, with a cut pattern that imparts anisotropic compliance to regions of each individual structure, and each individual structure can be the same or different from adjacent structures, thereby allowing each structure to bend in the same or different directions.

[0043] In another embodiment, a series or series of mechanical structures are disposed along the length of the device, with each mechanical element or series having an isotropic bending about a central axis of the device (and thus a non-preferential bending direction relative to the axis), and a single pull wire is disposed in a helical path along the length of the series or series of mechanical structures, such that compressive loading of the series or series of mechanical structures by the pull wire causes the device to bend and stiffen in a helical shape. The series or series of mechanical structures and corresponding isotropic elements may be formed by coils or, alternatively, may be formed into a tube, such as a hypotube, having a cut pattern that imparts isotropic compliance to regions of each individual structure, allowing each structure to bend non-preferentially in any direction.

[0044] In other embodiments of the helical shaped device, the actuator can comprise other types of mechanical actuators that are actuated by mechanical means, such as pull wires, hydraulic or pneumatic actuators that can be actuated by fluid pressure, or combinations thereof.

[0045] In a preferred embodiment, the helical shaped device has an outer helical diameter and a helical pitch. The outer helical diameter is selected to be at least as large as the target lumen where fixation is to occur, with the more preferred outer helical diameter being 1.25 to 2 times the diameter of the target lumen. The helical pitch is selected to be short enough to provide a degree of friction between the wall of the lumen and the helically shaped device that can fix the device in place, yet the helical pitch should be long enough not to prevent the smooth passage of other catheters and / or instruments through the lumen of the device or to withdraw the outside of the helical device. The preferred helical pitch is 3 to 10 times the outer helical diameter.

[0046] Another aspect of the disclosed invention is directed to a method of using a helical embodiment of the catheter system within a body lumen. The method includes inserting the catheter into the body lumen with the electroactive polymer actuator in an unactuated configuration and with the tubular member having its inherent flexibility and relaxed shape. The electroactive polymer actuator is actuated using a control signal, thereby transitioning the shape of the tubular member to a substantially helical shape such that the tubular member is in circumferential contact with the wall of the body lumen along a length of the tubular member sufficient to stabilize the tubular member within the body lumen. The catheter is thereby stabilized within the body lumen. In various embodiments of the method, the tubular member can be in circumferential contact with the wall of the body lumen along substantially the entire insertable length of the tubular member.

[0047] Another embodiment of the helical shaped device is directed to a device utilizing an actuator to generate a motive force to move a catheter longitudinally within a body lumen. The catheter system includes an elongated flexible member. The flexible member has a plurality of radially arranged straight portions or path segments that coincide longitudinally along a respective length of the device and are radially spaced apart from one another, such as a first segment, a second segment radially offset from the first segment, and a third segment radially offset from the second segment. Each actuator or series of actuators is disposed within each segment in a helical path along the respective length of the device, and each actuation of one or more actuators using a respective control method is adapted to transition the shape of the respective length of the device to a substantially helical shape. Each actuator or series of actuators is configured to generate a frictional force between the flexible member and a wall of the body lumen by modulated actuation of the actuator. Sequential actuation of the actuator or series of actuators within each path segment moves the flexible member longitudinally within the body lumen. For example, modulated actuation of the path segments can cause the flexible member to move in a worm crawler-like or rotary screw motion that creates a motive force to move the flexible member longitudinally.

[0048] In various embodiments, a modulated signal or force is applied to an actuator or set of actuators in each path segment using a respective control method, thereby controlling the amplitude of the geometric response of each path segment. The controller provides a sinusoidal amplitude modulation of the signals or forces, each signal or force being out of phase with the other signals. For example, in the case of three path segments, each signal or applied force may be 120° out of phase with the other two signals or applied forces.

[0049] In various embodiments, a device utilizing electroactive polymer actuation can further include a controller operably connected to the electroactive polymer actuators and configured to send respective control signals to the respective electroactive polymer actuators. Similarly, a device utilizing mechanical or hydraulic actuation can further include a controller operably connected to the mechanical or hydraulic actuators and configured to transmit respective control forces or pressures to the respective actuators. The controller may be electromechanical or purely mechanical and can generate the modulated forces and / or pressures required for modulated actuation of the respective actuators.

[0050] Another aspect of the disclosed embodiments is directed to a method of using embodiments of a helical shaped device within a body lumen. The method includes inserting a catheter system into the body lumen. A respective actuator or series of actuators in each path segment is actuated using a respective modulation control method for each path segment. The modulated actuation creates a motive force between the flexible member and a wall of the body lumen that moves the flexible member longitudinally within the body lumen.

[0051] In various embodiments, each modulated control signal or force is a sinusoidal amplitude modulated signal or applied force, with each signal or applied force being out of phase with the other signals or applied forces, e.g., for three path segments, each signal or applied force is 120° out of phase with the other signals or applied forces.

[0052] Thus, the embodiments described herein provide innovative devices that utilize actuators, such as mechanical actuators and / or electroactive polymer actuators, and methods of using such devices to provide fixation, friction reduction, and / or motive force that is actuated to move the device within a body lumen. Electroactive polymer actuation embodiments provide electronically controllable devices that allow for computer control, local electronic actuation of electroactive polymer actuators with minimal impact on remote parts, use of multiple actuators, more complex placement of actuators, and programmable and / or dynamic shape and configuration of the device. [Brief description of the drawings]

[0053] The foregoing, together with other and further embodiments and aspects of the disclosed invention, will now be described in more detail in the following detailed description to be read in light of the accompanying drawings, in which like reference numbers indicate like elements and in which the description of like elements shall apply to all relevant described embodiments.

[0054] [Figure 1] FIG. 1 is a schematic diagram of a catheter system according to an embodiment of the disclosed invention. [Diagram 2] 2A-2C are perspective views of some of various configurations of actuators on a catheter for use in the catheter system of FIG. 1 according to embodiments of the disclosed invention. [Diagram 3] 3A and 3B are partial side views of one configuration of an electroactive polymer actuator on a catheter for use in the catheter system of FIG. 1 according to an embodiment of the disclosed invention. [Figure 4] 4A and 4B are side views illustrating an anchoring feature of a catheter for use in the catheter system of FIG. 1 according to an embodiment of the disclosed invention. [Diagram 5] 5A and 5B are side views illustrating another fixation feature of a catheter for use in the catheter system of FIG. 1 according to an embodiment of the disclosed invention. [Figure 6] FIG. 6 shows a flow chart of a method of using a catheter having an anchoring feature as shown in FIGS. 4A, 4B, 5A and 5B according to an embodiment of the disclosed invention. [Figure 7] 7A and 7B are side views of another catheter for use in the catheter system of FIG. 1 according to an embodiment of the disclosed invention. [Figure 8] 8A-8C show dynamic cycling motion of the catheter of FIGS. 7A and 7B according to an embodiment of the disclosed invention. [Figure 9] FIG. 9 shows a flow chart of a method of using the catheter of FIGS. 7A and 7B according to an embodiment of the disclosed invention. [Figure 10] Figure 10A is a side view of another catheter for use with the catheter system of Figure 1 according to an embodiment of the disclosed invention. Figure 10B is a side view of the catheter of Figure 10A in an actuated configuration according to an embodiment of the disclosed invention. Figure 10C is a side perspective view of the catheter of Figure 10A in a non-actuated configuration. Figure 10D is a side perspective view of the catheter of Figure 10A in an actuated configuration. [Figure 11] FIG. 11 is a side view of the catheter of FIG. 10A in an operative configuration within a body lumen according to an embodiment of the disclosed invention. [Figure 12] FIG. 12 shows a flow chart of a method of using the catheter of FIGS. 10A-10D according to an embodiment of the disclosed invention. [Figure 13] FIG. 13 is a side view of yet another catheter for use with the catheter system of FIG. 1 in accordance with an embodiment of the disclosed invention. [Figure 14] Figures 14A-14D are side views of the catheter of Figure 13 at various states of a modulated actuation sequence for generating a motive force according to an embodiment of the disclosed invention, and Figure 14E is a graph of a modulated actuation sequence of the catheter of Figure 13 for generating the modulated actuation sequence shown in Figures 14A-14D according to an embodiment of the disclosed invention. [Figure 15]FIG. 15 is a side view of yet another catheter for use with the catheter system of FIG. 1 according to an embodiment of the disclosed invention. [Figure 16] Figures 16A-16C are side views of the catheter of Figure 15 at various states of a modulated actuation sequence for generating a motive force according to an embodiment of the disclosed invention, and Figure 16D is a graph of a modulated actuation sequence of the catheter of Figure 15 for generating the modulated actuation sequence shown in Figures 16A-16C according to an embodiment of the disclosed invention. [Figure 17] FIG. 17 shows a flow chart of a method of using the catheters of FIGS. 13 and 15 according to an embodiment of the disclosed invention. [Figure 18] FIG. 18 is a side view of a portion of a catheter reinforcement having multiple mechanical actuators for use in a catheter system according to an embodiment of the disclosed invention. [Figure 19] FIG. 19 shows the catheter reinforcement of FIG. 16 in an unloaded state, illustrating the various areas of compliance provided by the mechanical actuators, according to an embodiment of the disclosed invention. [Figure 20] FIG. 20 shows the catheter reinforcement of FIG. 16 under compressive load, illustrating the bending curvature / stiffness of the areas of various compliance provided by the mechanical actuators, according to an embodiment of the disclosed invention. [Figure 21] FIG. 21 is an enlarged cross-sectional view of one embodiment of the catheter reinforcement of FIG. 18 showing one embodiment of a pull wire actuator for the mechanical actuator according to an embodiment of the disclosed invention. [Figure 22] FIG. 22 is an enlarged cross-sectional view of another embodiment of the catheter reinforcement of FIG. 18 showing another embodiment of a multiple pull wire actuator for the mechanical actuator in accordance with an embodiment of the disclosed invention. [Figure 23] FIG. 23 is an enlarged side view of one of the mechanical actuators of the catheter reinforcement without compressive load, according to an embodiment of the disclosed invention. [Figure 24]FIG. 24 is an enlarged side view of the mechanical actuator of FIG. 21 illustrating bending of the actuator under a compressive load, according to an embodiment of the disclosed invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] 1-4 show a catheter system 100 configured in accordance with an exemplary embodiment of the disclosed invention. The catheter system 100 is generally configured to perform a procedure, such as a medical or diagnostic procedure, in a body cavity, such as a lumen in the vasculature. The catheter system 100 includes a catheter 102 and a controller 104. The catheter 102 includes a flexible, elongated tubular member 106 having a proximal portion 108, a distal portion 110, and a working lumen 112 extending therebetween. The tubular member 106 has an inherent flexibility (or inherent stiffness) that depends on the physical properties and dimensions of the material or materials forming the tubular member 106. The inherent flexibility is typically highly elastically deformable so that the catheter 102 can navigate relatively tortuous paths in the body cavity of the vasculature. The catheter 102 also includes one or more actuators 114 disposed on the tubular member 106.

[0056] The actuators 114 may include steering actuators 114a, 114b, 114c, 114d (not shown but positioned on the opposite side of the tubular member 106 from the steering actuator 114b) located at a distal portion of the tubular member 106, and anchor actuators 114e, 114g, 114f. As described herein, any suitable number of actuators 114 may be positioned on the tubular member 106, depending on the desired actuation configuration of the catheter 102, and thus more or fewer actuators 114 may be utilized. The actuators 114 may include an electroactive polymer material. As described herein, an electroactive polymer has the ability to change shape in response to an electrical stimulus, i.e., an electrical signal. The electroactive polymer may be an electroactive polymer film, or other suitable form of electroactive polymer. The electroactive polymer may be any suitable electroactive polymer, such as parylene, polyaniline, polypyrrole, polysulfone, or polyacetylene. The electroactive polymer actuator 114 is actuated by applying an electrical control signal to the actuator and is deactuated by removing the electrical control signal.

[0057] The actuator 114 is applied to the tubular member 106 to exert a force on the structure of the tubular member in order to apply a force to the tubular member 106 that changes the physical properties of the tubular member 106, such as changing the shape, dimension, stiffness and / or position of the tubular member 106.

[0058] The actuator 114 may be disposed on the tubular member 106 by any suitable method. As some examples, the actuator 114 may be attached onto a surface (e.g., on an outer surface, on an inner surface) of the tubular member 106 using an adhesive or other fastening means. The actuator 114 may be deposited onto the tubular member 106, such as by spray deposition, electrodeposition, or other suitable deposition means. The actuator 114 may be integral with the tubular member 106, such as molded into the wall of the tubular member 106, or may be incorporated within the tubular member.

[0059] The catheter 102 has an unactuated configuration in which the actuators 114 are not actuated by a control signal. In the unactuated configuration, each of the actuators 114 and each segment of the tubular member 106 in which the respective actuator 114 is disposed are in a relaxed configuration (i.e., an unactuated configuration). In the relaxed configuration, the actuators 114 do not significantly affect the configuration (e.g., stiffness and / or shape) of the tubular member 106. Thus, in the relaxed configuration, the tubular member 106 has its inherent shape and flexibility. The catheter 102 has an actuated configuration in which the one or more electroactive polymer actuators are actuated by one or more electrical control signals. The control signals cause the electroactive polymer actuators to change shape, thereby exerting a force on the tubular member 106 to which the electroactive polymer actuator is applied, altering the properties of the tubular member 106. As described below, an actuated actuator 114 can change the stiffness and / or shape of the tubular member 106. When the electrical control signal is removed, the actuator 114 returns to its relaxed configuration and the tubular member 106 also returns to its relaxed configuration, including its inherent flexibility.

[0060] 2A-2C show various configurations of electroactive polymer actuators 114 arranged to effect various changes in the configuration of the tubular member 106 on which the electroactive polymer actuator 114 is disposed. FIG. 2A shows a close-up side view of the tubular member 106 and one of the electroactive polymer actuators 114 disposed on the tubular member 106. FIG. 2A shows the electroactive polymer actuator 114 and tubular member 106 in an unactuated configuration (i.e., with no electrical control signal applied). FIG. 2B shows an actuated configuration of the electroactive polymer actuator 114 of FIG. 2A, in which the actuator 114 expands upon actuation by an electrical control signal and contracts from the expanded state back to the unactuated configuration upon removal of the electrical control signal. As shown in FIG. 2B, upon actuation, the electroactive polymer actuator 114 expands, causing the segment of the tubular member 106 attached to the electroactive polymer actuator 114 to bend in a convex curve (relative to the side of the tubular member 106 to which the actuator 114 is attached). In addition to bending the tubular member 106, actuation of the electroactive polymer actuator 114 causes the tubular member 106 to stiffen into the curved shape.

[0061] 2C illustrates an actuated configuration of the electroactive polymer actuator 114 of FIG. 2A, where the actuator 114 contracts upon actuation by an electrical control signal and expands from the contracted state back to an unactuated configuration upon removal of the electrical control signal. As shown in FIG. 2C, upon actuation, the electroactive polymer actuator 114 contracts, causing the segment of the tubular member 106 attached to the electroactive polymer actuator 114 to bend in a concave curve (relative to the side of the tubular member 106 to which the actuator 114 is attached). Again, in addition to bending the tubular member 106, actuation of the electroactive polymer actuator 114 stiffens the tubular member 106 into a curved shape.

[0062] FIG. 3A illustrates an enlarged side view of another embodiment of a tubular member 106 and an electroactive polymer actuator 114 disposed thereon. In FIG. 3A, the electroactive polymer actuator 114 is configured to stiffen the tubular member 106 into a generally straight shape. The electroactive polymer actuator 114 is circumferentially disposed on the tubular member 106. Alternatively, a pair of electroactive polymer actuators 114 can be disposed on either side of the tubular member 106 in tension with respect to one another. FIG. 3A illustrates the electroactive polymer actuator 114 and tubular member 106 in an unactuated configuration (i.e., no electrical control signal is applied). FIG. 3B illustrates an actuated configuration of the electroactive polymer actuator 114 of FIG. 3A, where the actuator 114 expands upon actuation by an electrical control signal and returns from the expanded state to the unactuated configuration upon removal of the electrical control signal. As shown in Figure 3B, upon actuation, the electroactive polymer actuator 114 expands, causing the segment of the tubular member 106 attached to the electroactive polymer actuator 114 to expand linearly and stiffen. Alternatively, the electroactive polymer actuator 114 of Figure 3A may be configured to contract upon actuation. Upon actuation, the electroactive polymer actuator 114 contracts to provide a similar stiffening effect.

[0063] The controller 104 is configured to selectively send one or more electrical control signals to the electroactive polymer actuators 114. The controller 104 is operatively connected to the electroactive polymer actuators 114 using one or more conductors 118, each having a first end electrically connected to the controller 104 and a second end electrically connected to one or more of the electroactive polymer actuators 114. In one embodiment, there may be a pair of conductors 118 for each electroactive polymer actuator 114. In an alternative embodiment, a set of two or more electroactive polymer actuators 114 may be connected to the same pair of conductors 118 such that the set of two or more electroactive polymer actuators 114 are actuated by the same electrical control signal from the controller 104. Similarly, the catheter system 100 may be configured with one or more sets each having multiple electroactive polymer actuators 114 connected to the same pair of conductors 118.

[0064] Returning to FIG. 1 , the catheter system 100 includes a catheter 102 that utilizes electroactive polymer actuators 114 to selectively alter a configuration of the catheter 102, such as the shape and / or stiffness of the tubular member 106, via one or more electrical control signals. For example, the steering actuators 114a, 114b, 114c, 114d can be configured to steer the catheter 102 as it moves through a body lumen. In one embodiment, each of the steering actuators 114a, 114b, 114c, 114d can be configured the same as or similar to the electroactive polymer actuator 114 of FIG. 2B. In this manner, the steering actuators 114a, 114b, 114c, 114d can be selectively actuated using one or more control signals to bend the distal portion 110 of the tubular member 106 in a direction that a user desires to advance the catheter 102 through a body lumen. Each of the steering actuators 114a, 114b, 114c, 114d is independently connected to the controller 104 and is controllable by a respective individual control signal from the controller 104. This allows each of the steering actuators 114a, 114b, 114c, 114d to be controlled independently from the other steering actuators 114a, 114b, 114c, 114d. Although the exemplary embodiment of FIG. 1 shows four steering actuators 114, any suitable number can be used to provide the desired steering effect. For example, a single steering actuator 114a can be used, and a user can manually manipulate the catheter 102 from the proximal end to rotate the tubular member 106 such that the distal portion 110 of the tubular member 106 is bent in the desired direction of travel by actuating the steering catheter 114a.

[0065] The anchor actuators 114e, 114f, 114g are disposed on the anchor portion 120 of the tubular member 106. The anchor actuators 114e, 114f, 114g are configured to be actuated to change the stiffness and / or shape of the tubular member 106 to the anchor shape, thereby fixing the anchor portion in place in the body lumen having a shape corresponding to the anchor shape. In the exemplary embodiment of FIG. 1, the anchor actuators 114e, 114g are configured to stiffen and / or change the shape of the tubular member 106 and bias the tubular member 106 to a curved shape, while the anchor actuator 114f is configured to stiffen the tubular member 106 and bias the tubular member 106 to a substantially straight shape. Thus, the anchor actuators 114e, 114g are the same as or similar to the electroactive polymer actuator 114 of FIG. 2B. The anchor actuator 114f is the same as or similar to the electroactive polymer actuator 114 shown in FIG. 3A and FIG. 3B. The anchor actuators 114e, 114f, 114g may be separately connected to the controller 104 so that they can be independently actuated by separate control signals from the controller 104, or may be connected to the controller 104 as a set so that they can be actuated by a single control signal from the controller 104.

[0066] In a non-activated configuration of the anchoring function of the catheter system 100, the anchor actuators 114e, 114f, 114g are not activated such that the anchor portion 120 of the tubular member 106 has its inherent flexibility. In other words, the anchor portion 120 is relatively flexible so that the catheter 102 can navigate a relatively tortuous path within the body lumen as it advances therethrough. In an activated configuration of the anchoring function of the catheter system 100, the anchor actuators 114e, 114f, 114g are activated by one or more control signals (depending on the connection configuration to the controller, as described above). Activation of the anchor actuators 114e, 114f, 114g causes the anchor actuators 114e, 114f, 114g to stiffen and / or mold the anchor portion 120 of the tubular member 106 into an anchor shape.

[0067] 4A and 4B illustrate an anchoring feature of the catheter 102 that is used to anchor or stabilize the catheter 102 within an exemplary body lumen 122. In the illustrated example, the body lumen 122 is an arcuate cross section 122 within a vasculature 124 that includes multiple interconnecting blood vessels. FIG. 4A illustrates the catheter 102 being advanced into the body lumen 122 of the vasculature 124. In FIG. 4A, the catheter 102 is in an unactuated configuration in which the anchor actuators 114e, 114f, 114g are unactuated, and the anchor portion 120 of the tubular member 106 is essentially flexible. Once the catheter 102 is positioned with the anchor portion 120 disposed at a desired location within the body lumen 122, the anchor actuators 114e, 114f, 114g are actuated using one or more control signals from the controller 104, as shown in FIG. 4B. 4B, actuation of anchor actuators 114e, 114f, 114g causes anchor portion 120 to harden and form into a shape corresponding to body cavity 122 so as to force anchor portion 120 into body cavity 122. This stabilizes and / or fixes anchor portion 120 within body cavity 122, thereby stabilizing and / or fixing catheter 102 in place. Fixing catheter 102 prevents catheter 102 from moving when other instruments, such as other catheters or devices, are inserted and advanced through catheter 102.

[0068] 5A and 5B show another exemplary embodiment of the anchoring feature of the catheter system 100. The anchoring feature shown in FIG. 5A and 5B is similar to the anchoring feature shown in FIG. 4A and 4B, except that it is configured for use in a particular curved body lumen 124 having an S-shaped curve (similar to the shape of a typical carotid artery). The catheter 140 of FIG. 5A and 5B does not require a straight shaped anchor actuator 114f like the catheter 102 of FIG. 4A and 4B. Instead, the catheter 140 has an anchor actuator 114h and an anchor actuator 114i configured to curve in opposite directions to form an anchor shape corresponding to the S-shaped curve shape of the body lumen 142. FIG. 5A shows the catheter 140 being advanced into the body lumen 142 of the vasculature 144. In FIG. 5A, the catheter 140 is in an unactuated configuration in which the anchor actuators 114h, 114i are unactuated, and the anchor portion 120 of the tubular member 106 is essentially flexible. Once the catheter 140 is positioned with the anchor portion 120 disposed at a desired location within the body cavity 142, the anchor actuators 114h, 114i are actuated using one or more control signals from the controller 104, as shown in FIG. 5B. As shown in FIG. 5B, actuation of the anchor actuators 114h, 114i hardens and forms the anchor portion 120 into an S-shape, thereby securing the anchor portion 120 in a shape corresponding to the body cavity 142. This stabilizes and / or secures the anchor portion 120 within the body cavity 142, thereby stabilizing and / or securing the catheter 140 in place. Securing the catheter 102 prevents the catheter 140 from moving when other instruments, such as other catheters or devices, are inserted and advanced through the catheter 102.

[0069] 6, a flow chart showing a method 150 of using the catheter system 100 having either the catheter 102 or 140 is shown. The method of using the catheter system 100 having either the catheter 102 or 140 is substantially the same, so the method 150 will be described for the catheter system having the catheter 102. In step 152, the distal end 110 of the catheter 102 is inserted into the body cavity with the anchor actuators 114e, 114f, 114g deactivated so that the anchor portion 120 of the tubular member 106 has its inherent flexibility. In step 154, the catheter 102 is advanced in the body cavity with the anchor actuators 114e, 114f, 114g deactivated to position the catheter 102 at the desired location such that the anchor portion is located within the body cavity 122. In step 156, controller 104 sends one or more control signals to anchor actuators 114e, 114f, 114g, thereby actuating anchor actuators 114e, 114f, 114g. In step 158, actuation of anchor actuators 114e, 114f, 114g hardens and / or forms anchor portion 120 into an anchor shape to secure anchor portion 120 in place in body cavity 122.

[0070] 7A and 7B and 8A-8C, another exemplary embodiment of a catheter 160 having an actuator 114 that can be used in the catheter system 100 of FIG. 1 is shown. Additionally, the catheter 160 can include one or more of the features and aspects of the catheter 102 described in the drawings and herein. The catheter 160 is configured to utilize the actuator 114 to dynamically cycle the shape of the catheter 160 during longitudinal movement within a body lumen, thereby reducing static friction of the catheter 160. As shown in FIGS. 7A and 7B, the catheter 160 includes an elongated flexible tubular member 106 and a plurality of actuators 114 disposed on the tubular member 106. The actuators 114 are configured and arranged to change the shape of the tubular member 106 to a generally sinusoidal shape and dynamically cycle the sinusoidal shape between a 0° out-of-phase state (as shown in FIG. 8B) and a 180° out-of-phase state (as shown in FIG. 8C). 7A and 7B and 8A-8C show representative segments of catheter 160, it should be understood that actuators 114j, 114k may be positioned along any suitable length of tubular member 106 (including along substantially the entire length of tubular member 106 extending from proximal end 108 to distal end 110 of tubular member 106), or along substantially the entire insertable length of tubular member 106.

[0071] 7A and 7B show an example arrangement of actuators 114 configured to shape the tubular member 106 into 0° out-of-phase and 180° out-of-phase sinusoidal waveforms. The plurality of actuators 114 includes a first set 162 of actuators 114j and a second set 164 of actuators 114k. On a first (radial) side 166 of the tubular member 106, the actuators 114j of the first set 162 are arranged longitudinally along the tubular member 106 and are interleaved with actuators 114k of the second set 164 arranged longitudinally along the tubular member 106 on the first side 166. Similarly, on a second side 168 of the tubular member 106 radially opposite the first side 166, the actuators 114j of the first set 162 are arranged longitudinally along the tubular member 106 and are alternated with actuators 114k of the second set 164 arranged longitudinally along the tubular member 106 on the second side 168.

[0072] As shown in Figures 7A and 7B, the actuators 114j of the first set 162 are arranged such that the actuators 114j of the first side 166 are longitudinally offset from the actuators 114j of the second side 168. Similarly, the actuators 114k of the second set 164 are arranged such that the actuators 114k of the first side 166 are longitudinally offset from the actuators 114k of the second side 168. As also shown in Figures 7A and 7B, this arrangement results in the actuators 114j of the first set 162 of the first side 166 being opposite the actuators 114k of the second set 168 of the second side 168, and the actuators 114j of the first set 162 of the second side 168 being opposite the actuators 114k of the second set 164 of the first side 166, and vice versa. This configuration of actuators 114 is such that actuation of a first set 162 of actuators 114j changes the shape of tubular member 106 to a substantially sinusoidal shape with a 0° phase shift, as shown in FIG. 8B, and actuation of a second set 164 of actuators 114k changes the shape of tubular member 106 to a sinusoidal shape with a 180° phase shift, as shown in FIG. 8C.

[0073] 7A, when the actuators include an electroactive polymer, the first set 162 of the electroactive polymer actuators 114j are electrically connected to the controller 104 via a first pair of electrical connections 118a, 118b such that all of the electroactive polymer actuators 114j in the first set 162 are actuated by a single first electrical control signal from the controller 104. One connection 118a of the pair of electrical connections is connected to a first end of each of the electroactive polymer actuators 114j, and the other connection 118b is connected to a second end of each of the electroactive polymer actuators 114j. Each of the electrical connections 118a, 118b can include a wire, with each wire disposed on the tubular member 106 and extending from the distal end 110 of the catheter 160 to the proximal end 108 and to a connection on the controller 104. Instead of wires, the electrical connections 118a, 118b may be constructed from any other suitable electrical conductor, such as a conductive material coated or printed on the tubular member 106.

[0074] Similarly, as shown in FIG. 7B, the second set 164 of electroactive polymer actuators 114k are connected to the controller 104 via a second pair of electrical connections 118c, 118d such that all of the electroactive polymer actuators 114k in the second set 164 are actuated by a single second electrical control signal from the controller 104. The second pair of electrical connections 118c, 118d are electrically isolated / separated from the first pair of electrical connections 118a, 118b. One of the pair of electrical connections, connection 118c, is connected to a first end of each of the electroactive polymer actuators 114k, and the other connection, connection 118d, is connected to a second end of each of the electroactive polymer actuators 114k. Each of the electrical connections 118c, 118d can include a wire that is disposed on the tubular member 106 and extends from the distal end 110 of the catheter 160 to the proximal end 108 to a connection at the controller 104. Instead of wires, the electrical connections 118c, 118d can be constructed from any other suitable electrical conductor, such as a conductive material coated or printed on the tubular member 106.

[0075] As shown in Figures 8A-8C, multiple actuators 114 on the catheter 160 can be dynamically actuated to cycle the tubular member 106 back and forth between a substantially sinusoidal shape with 0° out of phase and a substantially sinusoidal shape with 180° out of phase by alternately actuating the first set 162 and the second set 164 using a first signal and a second signal. Figure 8A shows the catheter 160 in a state where both the first set 162 and the second set 164 are unactuated, thereby allowing the tubular member 106 to have its inherent flexibility and a relaxed shape that is typically the shape of the passage of the body cavity into which the catheter 160 is inserted. As shown in Figure 8B, when the first set 162 of actuators 114j is actuated by a first control signal from the controller 104 (with the second set 164 unactuated), the actuators 114j form the tubular member 106 into a substantially sinusoidal shape with 0° out of phase. 8C, when the second set 164 of actuators 114k is activated by a second control signal from the controller 104 (and the first set 162 is deactivated by turning off the first control signal), the actuators 114k form the tubular member 106 into a substantially sinusoidal shape that is 180° out of phase. The controller 104 is configured to modulate the first and second control signals in an alternating pattern to dynamically cycle the activation of the first set 162 of actuators 114j and the second set 164 of actuators 114k, thereby dynamically cycling the tubular member 106 back and forth between a substantially 0° out of phase sinusoidal shape and a substantially 180° out of phase sinusoidal shape.

[0076] The catheter system 100 with the catheter 160 is configured to dynamically cycle the sinusoidal shape of the tubular member 106 at an amplitude and frequency that reduces the static friction of the tubular member 106 as it is moved longitudinally within the body lumen. The amplitude and frequency can be set to a minimum value necessary to reduce static friction and that does not irritate or cause spasms in the walls of the body lumen (such as blood vessels). For example, an exemplary frequency is in the range of 1 Hz to 10 Hz (cycles / sec) and an exemplary amplitude is in the range of 0.1 mm to 1.0 mm (this is compared to the exemplary amplitude of the movement of the steering actuators 114a-114d, which is in the range of 2.0 mm to 10.0 mm).

[0077] Referring to FIG. 9, a flow chart illustrating a method 170 of using the catheter system 100 implementing the catheter 160 is shown. The method 170 includes step 172 of inserting the distal end 110 of the catheter 160 into a body cavity. The catheter 160 can be inserted into the body cavity without actuating the actuator 114 or with the actuator 114 dynamically actuated to reduce static friction as the catheter 160 is inserted. It is envisioned that the catheter 160 is initially inserted at least a short length into the body cavity to provide more stability when the catheter 160 is initially inserted. In step 174, the controller alternately applies first and second electrical control signals as the catheter 102 is moved longitudinally within the body cavity, thereby dynamically cycling the tubular member 106 back and forth between a substantially 0° out-of-phase sinusoidal shape and a substantially 180° out-of-phase sinusoidal shape. The circular sinusoidal motion of the tubular member 106 breaks the static friction of the tubular member 106, making longitudinal movement easier (ie, requiring less force on the catheter 160) and smoother.

[0078] 10A-10D and 11 show another exemplary embodiment of a catheter 180 having an actuator 114 that can be used in the catheter system 100 of FIG. 1. Additionally, the catheter 180 can include one or more of the features and aspects of the catheter 102 shown in the drawings and described herein. The catheter 180 utilizes a single helically-disposed actuator 114m configured to stabilize the catheter 180 within the body cavity 122 by forming the tubular member 106 into a helical shape and circumferentially contacting the wall 182 of the body cavity 122. As shown in FIG. 10A, the catheter 180 includes a tubular member 106. The actuator 114m is disposed on the tubular member 106 in a helical path longitudinally along the tubular member 106. 10A-10D and 11 show a representative segment of the catheter 180, it should be understood that the actuator 114m may be disposed over any suitable length of the tubular member 106, including over substantially the entire length of the tubular member 106 extending from the proximal end 108 to the distal end 110 of the tubular member 106, or over substantially the entire length of the insertable tubular member 106. As shown in FIGS. 10A and 10C, when the actuator 114 is in an unactuated state, the tubular member 106 has its inherent flexibility and its relaxed shape (typically taking the shape of the passage of the body cavity 122 through which the catheter is inserted). In FIGS. 10A and 10C, the unactuated catheter 180 is substantially straight. As shown in FIGS. 10B and 10D, when the actuator 114m is actuated, the actuator 114m transitions the shape of the tubular member 106 to a substantially helical shape. The actuator 114m contracts (i.e., is placed under tension), causing the tubular member 106 to form into a generally helical shape such that the actuator 114m is located on the inner radius of the helical shaped tubular member 106 (as best shown in FIG. 10D).

[0079] 1, 2A-3B, 7A and 7B, when the actuator comprises an electroactive polymer, the catheter 180 also has a pair of electrical connections 118, each connected at one end to an electroactive polymer actuator 114m and at the other end to the controller 104. When the electroactive polymer actuator 114m is unactuated, the tubular member 106 has its inherent flexibility and its relaxed shape (typically the shape of the passageway of the body lumen 122 through which the catheter 180 is inserted), as shown in FIGS.

[0080] 10B and 10D, upon actuation of the electroactive polymer actuator 114m by an electrical control signal from the controller 104, the electroactive polymer actuator 114m transitions the shape of the tubular member 106 into a substantially helical shape. The actuator 114m contracts (i.e., is placed under tension), causing the tubular member 106 to form into a substantially helical shape such that the actuator 114m is located on the inner radius of the helical shaped tubular member 106.

[0081] The single actuator 114m may include any type of elongated linearly acting contraction or expansion actuator. If the actuator 114m is a contraction actuator, upon contraction the actuator forces the helically disposed side of the tubular member 106 to shorten, thereby causing the catheter 180 to assume a helical shape with the actuator 114m biased inwardly of the helical shape. If the actuator is an expansion actuator, upon expansion the actuator forces the helically disposed side of the tubular member 106 to lengthen, thereby causing the catheter 180 to assume a helical shape with the actuator 114m biased outwardly of the helical shape.

[0082] 11, the catheter 180 is configured such that the substantially helically shaped tubular member 106 circumferentially contacts a wall 182 of the body cavity 122. The circumferential contact of the tubular member 106 with the wall 182 stabilizes the catheter 180 within the body cavity 122. For example, the catheter 106 is prevented from moving radially while instruments and other catheters are moved and / or manipulated through the tubular member 106, and also prevents longitudinal movement of the catheter 180 relative to the body cavity 122.

[0083] 12, a flow chart is shown illustrating a method 190 of using the catheter system 100 implementing the catheter 180. The method 190 includes step 192 of inserting the catheter 180 into the body cavity 122 with the electroactive polymer actuator 114m deactivated such that the tubular member 106 has its inherent flexibility and relaxed shape. At step 194, the catheter 180 is advanced through the body cavity 122 to a desired location within the body cavity. At step 196, the controller 104 applies an electrical control signal to the electroactive polymer actuator 114m. At step 198, the controller 104 activates the electroactive polymer actuator 114m to transition the shape of the tubular member 106 to a substantially helical shape such that the tubular member 106 is in circumferential contact with the wall 182 of the body cavity 122. This circumferential contact stabilizes and / or anchors the catheter 180 within the body cavity 122.

[0084] 13 and 14A-14E illustrate another exemplary embodiment of a catheter 200 having an actuator 114 that can be used in the catheter system 100 of FIG. 1. Additionally, the catheter 200 can include one or more of the features and aspects of the catheter 102 illustrated in the drawings and described herein. The catheter 200 utilizes a motive force actuator 202 including a plurality of helically arranged actuators 114n, 114o, 114p, etc. to generate a motive force for longitudinally moving or assisting in the movement of the catheter 200 within the body cavity 122. The illustrated embodiment of the catheter 200 includes a motive force actuator 202 having three helical actuators 114n, 114o, 114p, although any suitable number of helical actuators 114 can be utilized.

[0085] Similar to other catheters described herein, the catheter 200 includes an elongated flexible tubular member 106. The tubular member 106 has a number of longitudinal segments or portions 204, one segment 200 for each helical actuator 114. In the illustrated embodiment, the tubular member 106 has three segments 204a, 204b, 204c. The segments 204a, 204b, 204c are spaced apart longitudinally, e.g., a first segment 204a, distal to the first segment 204a, a second segment 204b, distal to the second segment 204b, and a third segment 204c. The three segments 204a, 204b, 204c may also be located at the distal portion 110 of the tubular member 106. In this manner, the prime mover actuator 202 is typically inserted into the body cavity 122 first along with the distal portion 110 of the catheter 200, and the prime mover actuator 202 can then push or pull the catheter 200 into the body cavity 122 to advance the catheter 200 to a desired position within the body cavity 122.

[0086] Each helical actuator 114n, 114o, 114p is disposed on each of the segments 204a, 204b, 204c in a helical path along the respective segments 204a, 204b, 204c such that actuation of each of the actuators 114n, 114o, 114p using respective control signals transitions the shape of each of the segments 204a, 204b, 204c to a substantially helical shape, as shown in Figures 14A-14D. Figure 14A illustrates actuator 114n in an unactuated state and actuators 114o, 114p actuated to form segments 204b, 204c into their respective helical shapes. Figure 14B illustrates actuator 114o in an unactuated state and actuators 114n, 114p actuated to form segments 204a, 204c into their respective helical shapes. FIG. 14C shows actuator 114p in an unactuated state, while actuators 114n and 114o are actuated to form segments 204a and 204b into their respective helical shapes.

[0087] Each actuator 114n, 114o, 114p is configured such that modulated actuation of the actuators 114n, 114o, 114p generates a motive force between the tubular member 106 and the wall 182 of the body cavity 122 that moves the tubular member 106 longitudinally within the body cavity 122.

[0088] The outer surface of each of the segments 204a, 204b, 204c may have helical undulations, ribs, or other structures to facilitate movement of the tubular member 106 in response to modulated actuation. The undulations, ribs, or other structures may increase friction between the tubular member 106 and the wall 182 of the body cavity 122.

[0089] In one aspect, modulated actuation of the polymer actuators 114n, 114o, 114p causes the tubular member 106 to move in a worm-crawler-like motion, as shown in FIGS. 14A-14E. To produce the worm-crawler-like motion, each of the actuators 114n, 114o, 114p is actuated in an out-of-phase modulation manner from the other two actuators. In the exemplary embodiment shown in FIGS. 14A-14E, the modulated actuation of each actuator 114 is 120° out-of-phase with the other actuators 114. FIG. 14E illustrates an example of the modulated actuation states / signals of the actuators 114n, 114o, 114p over time to generate a crawler-like motive force to move the tubular member 106. In the graph of Figure 14E, actuation line 220a corresponds to the actuation state of actuator 114n, actuation line 220b corresponds to the actuation state of actuator 114o, and actuation line 220c corresponds to the actuation state of actuator 114p. Times A1, B1, C1, and A2 in Figure 14E correspond to like reference numbers in Figures 14A-14D.

[0090] 14A-14E, the operation of catheter 200 moving within body cavity 122 having wall 182 will now be described. As shown in FIG. 14E, at time A1, actuator 114n is unactuated, actuator 114o is fully actuated, and actuator 114p is fully actuated. FIG. 14A illustrates a configuration of catheter 200 corresponding to the actuated state at time A1, in which unactuated actuator 114 forms segment 204a in a substantially straight shape, fully actuated actuator 114o forms segment 204b in a helical shape that contacts wall 182, and fully actuated actuator 114o forms segment 204b in a helical shape that contacts wall 182. As shown in FIG. 14E, as the modulated actuation progresses from time A1 to time B1 ("time interval 1"), actuator 114n is gradually actuated, actuator 114o is gradually deactuated, and actuator 114p remains fully actuated. During time interval 1, actuator 114n forms segment 204a into a spiral shape, actuator 114o transitions segment 204b from the spiral shape to a substantially straight shape, and actuator 114p maintains segment 204c in a spiral shape. During time interval 1, segment 204c anchors the rear end of motive actuator 202 to wall 182, and the expansion of segment 204b pushes segment 204a to the left.

[0091] As shown in FIGURE 14E, as the modulated actuation progresses from time B1 to time C1 ("time interval 2"), actuator 114n remains actuated, actuator 114o gradually activates, and actuator 114p gradually deactivates. During time interval 2, actuator 114n maintains segment 204a in a spiral shape, actuator 114o transitions segment 204b from a substantially straight shape to a spiral shape, and actuator 114p transitions segment 204c from a spiral shape to a substantially straight shape. During time interval 2, segment 204a secures the tip of motive force actuator 202 to wall 182, segment 204c disengages from wall 182, and the contraction of segment 204b as it forms a spiral shape pulls segment 204c to the left.

[0092] As shown in FIG. 14E, as modulated actuation progresses from time C1 to time A2 ("time interval 3"), actuator 114n is gradually deactivated, actuator 114o remains fully activated, and actuator 114p is gradually activated. During time interval 3, actuator 114n transitions segment 204a from a helical shape to a substantially straight shape, actuator 114o maintains segment 204b in a helical shape, and actuator 114p transitions segment 204c from a substantially straight shape to a helical shape. During time interval 3, segment 204b secures the middle portion of motive actuator 202 to wall 182, segment 204a extends leftward disengaging the leading end of motive actuator 202 from wall 182, and segment 204c contracts as it forms into a helical shape, re-securing the trailing end of motive actuator 202 to wall 182. At time A2, motive force actuator 202 is in the same configuration as at time A1 and can repeat the modulated actuation to continue moving catheter 200. Of course, the modulated actuation can be reversed, thereby producing a motive force in the opposite direction to move catheter 200 to the right.

[0093] The degree of phase shift between the actuators 114 may vary depending on the number of actuators 114 and other considerations such as designing the motion to generate a desired motive force. Additionally, the actuators 114 in the catheter 200 may be any suitable actuator, including electroactive polymer actuators or other types of actuators disclosed herein. In the case of electroactive polymer actuators 114, the catheter 200 has a pair of electrical connections 118 for each of the electroactive polymer actuators 114, allowing for independent actuation of each actuator 114. The controller 104 is configured to provide modulated electrical actuation signals to each of the actuators 114n, 114o, 114p according to a modulation pattern to generate a motive force.

[0094] 15 and 16A-16D show another exemplary embodiment of a catheter 250 having a motive force actuator 252 for generating a motive force for longitudinally moving or assisting the catheter within the body cavity 122. Similar to the catheter 200, the catheter 250 has an actuator 114 and can be used in the catheter system 100 of FIG. 1. Additionally, the catheter 250 can include one or more of the features and aspects of the catheter 102 shown in the drawings and described herein. The motive force actuator 250 includes a plurality of helically arranged actuators 114q, 114r, 114s, etc., for generating a motive force for longitudinally moving the catheter 250 within the body cavity 122. The illustrated embodiment of the catheter 250 includes a motive force actuator 252 having three helical actuators 114q, 114r, 114s, although any suitable number of helical actuators 114 can be utilized.

[0095] Similar to the other catheters described herein, the catheter 250 includes an elongated, flexible tubular member 106 .

[0096] Each helical actuator 114q, 114r, 114s is disposed on the tubular member 106 in a helical path along the longitudinal length of the tubular member 106, with each helical path of actuator 114 being longitudinally spaced or offset from the helical paths of the other actuators 114. As shown in Figures 15 and 16A-16C, the ordering of actuators 114 proceeds from left to right in the order 114q, 114r, 114s, with actuators 114q, 114r, 114s being disposed in parallel along the tubular member. The motive force actuator 252, which is comprised of the helical actuators 114q, 114r, 114s, may extend along a portion 254 of the tubular member 106, may extend along the entire length of the tubular member 106, may extend along at least a percentage (e.g., 90%, or 80%, or 70%, or 60%, or 50%) of the length of the tubular member 106, or may extend along any other suitable length of the tubular member. For example, the motive force actuator 252 may be disposed on a portion 254 of a distal portion of the catheter 250. In this manner, the motive force actuator 252 may first be inserted into the body cavity 122 along with the distal portion 110 of the catheter 250, and then the motive force actuator 252 may be used to push or pull the catheter 250 into the body cavity 122 to advance or retract the catheter 200 to a desired position within the body cavity 122.

[0097] Each helical actuator 114q, 114r, 114s is disposed on the tubular member 106 and configured such that, upon actuation of each actuator 114q, 114r, 114s using a respective control signal, the tubular member 106 is formed into a substantially helical shape, as shown in Figures 16A-16C. The offset position of each actuator 114q, 114r, 114s also offsets the helical shape of the tubular member 106 formed by each actuator 114q, 114r, 114s. Thus, modulated actuation of the actuators 114q, 114r, 114s can form the tubular member 106 into a helical shape that propagates in a wave-like manner along the longitudinal length of the tubular member 106. The helical wave-like propagation in a first direction (e.g., to the right) along the longitudinal length of the tubular member 106 creates a motive force in the opposite direction (e.g., to the left) of the tubular member 106 against the wall 182 of the body cavity 122, thereby moving the catheter 250 in the direction of the motive force.

[0098] The outer surface of the tubular member 106 of the catheter 250 may have helical undulations, ribs, or other structures to facilitate movement of the tubular member 106 in response to modulated actuation. The undulations, ribs, or other structures may increase friction between the tubular member 106 and the wall 182 of the body cavity 122.

[0099] 16A-16D show an example of modulated actuation of motive actuator 250 to generate a motive force to move catheter 250. FIG. 16D shows the actuation states / signals of each of actuators 114q, 114r, 114s over time to generate a helical shape that propagates in a wave-like manner from left to right. Actuation line 256a corresponds to the actuation state of actuator 114q, actuation line 256b corresponds to the actuation state of actuator 114r, and actuation line 256c corresponds to the actuation state of actuator 114s. Time points A, B, and C in FIG. 16D correspond to like reference numbers in FIGS. 16A-16C. Actuation states / signals 256 are modulated in a sinusoidal fashion, with the sinusoidal actuation states / signals of each actuator 114 being 120° out of phase with the other actuators 114. In other words, the sinusoidal operating state / signal 256b for actuator 114r is 120° out of phase with the operating state / signal 256a for actuator 114q, the sinusoidal operating state / signal 256c for actuator 114s is 120° out of phase with the operating state / signal 256b for actuator 114r, and the sinusoidal operating state / signal 256a for actuator 114q is 120° out of phase with the operating state / signal 256c for actuator 114s.

[0100] As shown in FIG. 16A, at time A in FIG. 16D, the actuators 114q and 114s are actuated and the actuator 114r is not actuated. This causes the tubular member 106 to form a helical shape, with the actuator 114r and the portion of the tubular member 106 attached to the actuator 114r located on the outer radius of the helical shape, while the actuators 114q, 114s and the respective portions of the tubular member 106 located on the inner radius of the helical shape. As shown in FIG. 16B, at time B in FIG. 16D, the actuators 114q and 114r are actuated and the actuator 114s is not actuated. This causes the tubular member 106 to form a helical shape, with the actuator 114s and the portion of the tubular member 106 attached to the actuator 114s located on the outer radius of the helical shape, while the actuators 114q, 114r and the respective portions of the tubular member 106 located on the inner radius of the helical shape. As shown in Figure 16C, at time C in Figure 16D, actuators 114r, 114s are actuated and actuator 114q is not actuated, which causes tubular member 106 to be formed into a helical shape, with actuator 114q and the portion of tubular member 106 attached to actuator 114q located on the outer radius of the helical shape, while actuators 114r, 114s and the respective portions of tubular member 106 located on the inner radius of the helical shape.

[0101] 16D, by modulating the respective actuation signals 256a, 256b, 256, the helical shape of the tubular member 106 can be caused to wave-like propagate in a first direction (e.g., to the right) along the longitudinal length of the tubular member 106, thereby creating a motive force in an opposite direction (e.g., to the left) of the tubular member 106 against the wall 182 of the body cavity 122 to move the catheter 250 in the direction of the motive force. The modulated actuation pattern can be reversed, thereby creating a motive force in the opposite direction to move the catheter 250 in the right direction. For example, modulated actuation of the actuators 114q, 114r, 114s can move the tubular member 106 in a rotational screw motion, thereby generating a motive force to move the catheter 250 longitudinally.

[0102] The degree of phase shift between the actuators 114 in the motive force actuator 252 may vary depending on the number of actuators 114 and other considerations, such as the design of the motion, to produce a desired motive force. Additionally, the actuators 114 in the catheter 250 may be any suitable actuator, including electroactive polymer actuators or other types of actuators disclosed herein. In the case of electroactive polymer actuators 114, the catheter 250 also has a pair of electrical connections 118 for each of the electroactive polymer actuators 114, allowing for independent actuation of each actuator 114. The controller 104 is configured to provide modulated electrical actuation signals to each of the actuators 114q, 114r, 114s according to a modulation pattern to generate a motive force.

[0103] 17, a flow chart is shown illustrating a method 210 of using the catheter system 100 implementing any of the catheters 200, 250. The method 210 includes step 212 of inserting the catheter 200 into the body cavity 122 with the actuators 114n, 114o, 114p deactivated such that the tubular member 106 has its inherent flexibility and relaxed shape. In step 214, the actuators 114n, 114o, 114p are actuated using a first pattern of respective modulated control signals to each actuator 114n, 114o, 114p. The controller 104 provides the control signals, which may include various forms of energy, including electrical, mechanical, hydraulic, or other means by which an energy signal may be transmitted. The respective modulated control signals are out of phase with each other (e.g., 120° out of phase). The modulated actuation causes each of the segments 204a, 204b, 204c to transition into a helical shape in a first modulated pattern, thereby creating a motive force between the tubular member 106 and the wall 182 of the body cavity 122. In step 216, the actuators 114n, 114o, 114p are actuated with a second pattern of modulated control signals (e.g., the second pattern may be the inverse of the first pattern) that withdraws the tubular member 106 (i.e., moves the tubular member 106 in the opposite direction of advancement).

[0104] Referring to FIG. 18, a mechanical actuation system 300 for providing anchoring functionality to a catheter system is shown. The catheter system may be similar to the catheter system 100 described herein, except that the actuator 114 is replaced with the mechanical actuation system 300. The mechanical actuation system 300 includes a tube 304 having one or more mechanical actuator elements 302. The tube 304 may be a hypotube or other suitable tube for use in a catheter. The illustrated embodiment includes two actuator elements 302a, 302b. The mechanical actuation system 300 may include any suitable number of mechanical actuators 302 to provide a desired anchor shape for anchoring within a body lumen having a corresponding shape.

[0105] In the illustrated embodiment, the actuator element 302 is integrally formed within a tube 304 having distinct longitudinal regions including a region containing the actuator element 302 and non-actuated regions 306a, 306b, 306c adjacent the actuator element 302. The non-actuated regions 306a, 306b, 306c are regions of the tube 304 that have low axial compressive compliance and are isotropic about the central axis of the tube 304, forming straight, non-actuated segments of the tube 304.

[0106] The actuator element 302 is a region of the tube 304 whose compliance is anisotropic around the central axis and may include areas of various compliances. The actuator element 302a has a first anisotropic area 308a with a downward bias and moderate compliance (i.e., bends more than a low compliance and bends less than a high compliance for a given compressive force) and a second anisotropic area 308b with a downward bias and high compliance (i.e., bends more than a moderate compliance for a given compressive force). The direction of the "bias" is based on the orientation shown in Figures 18-20. In other words, the first anisotropic area 308a and the second anisotropic area 308b are configured to bend clockwise in response to a compressive force, as shown in Figure 20. As shown in Figure 20, for a given compressive force, the first anisotropic area 308a bends less (i.e., bends with a larger bending radius or bending curvature) than the second anisotropic area 308b. Similarly, the actuator element 302b has a first anisotropic area 310a with an upward bias and a moderate compliance (i.e., bends more than a low compliance and bends less than a high compliance for a given compressive force) and a second anisotropic area 310b with an upward bias and a high compliance (i.e., bends more than a moderate compliance for a given compressive force). In the orientation as shown in Figs. 16-18, the first anisotropic area 310a and the second anisotropic area 3108b are configured to bend counterclockwise in response to a compressive force, as shown in Fig. 18. As shown in Fig. 18, for a given compressive force, the first anisotropic area 310a will bend less (i.e., bend with a larger bending radius or bending curvature) than the second anisotropic area 310b.

[0107] FIG. 19 illustrates the relative axial compression compliance of each region of the mechanical actuation system 300. As shown in FIG. 20, actuation of the actuation system 300 by applying an axial compressive force to the tube 303 will cause the actuator elements 302 to bend based on the configuration of each actuator element 302. With reference to FIGS. 19 and 20, two alternative actuation mechanisms 312a, 312b are shown. The actuation mechanism 312a of FIG. 21 includes a single pull wire 314 disposed within a lumen of the catheter. The pull wire 314 has a distal end attached to the distal end of the actuation system 300 and extends proximally along the length of the catheter to the proximal end of the catheter where it can be manipulated to apply or remove a compressive force to the actuation system 300. The actuation mechanism 312b of FIG. 22 includes multiple pull wires 314a, 314b, 314c disposed within passages or lumens in the wall of the tube 304. Pull wires 314a, 314b, 314c are attached and operated similarly to pull wire 314 of Figure 19. The pull wires 14a, 314b, 314c may all be actuated simultaneously or each may be actuated sequentially, and similarly, the actuation forces on the individual wires may all be the same or may vary.

[0108] 24 and 25, an exemplary embodiment of an actuator element 302a is shown. The anisotropic areas 308a, 308b of the actuator element 302a are formed by a number of cuts in the tube 304, such as laser or machine cuts in the hypotube 304. The width, spacing and location of the cuts establish different compressive compliances and bending curvatures of each anisotropic area 308. As shown in FIG. 22, when a compressive force is applied, the anisotropic area 308a bends to a larger radius than the anisotropic area 308b.

[0109] The anisotropic areas 308 can impart a bending bias in a given direction to each area of ​​the actuator element 302, and this bending bias can be varied from area to area to cause bending in different planes in each area, or can be varied continuously within the bending region to create complex bends, including forming helical shapes along some or all of the actuation system 300.

[0110] The method of using the catheter system 100 with the actuation system 300 is similar to the method of using the catheter 120 or 140 described above, except that the actuation system 300 is actuated by actuating one or more pull wires 314 to apply and remove an axial compressive force to the actuator element 302. First, the distal end 110 of the catheter 102 is inserted into the body cavity with the actuation element 302 unactuated and with no compressive load applied to the actuation system 300 such that the anchor portion 120 of the tubular member 106 has its relaxed shape and / or inherent flexibility. The catheter 102 is then advanced into the body cavity to position the catheter 102 at a desired location with the anchor portion located within the body cavity 122. The actuation system 300 is then actuated by applying a compressive force to the actuation element 302, thereby bending and stiffening the actuation element 302 into an anchor shape that secures the anchor portion 120 in place within the body cavity 122.

[0111] Similarly, another method of using the catheter system 100 is directed to a catheter system having an actuation system 300 configured to form the catheter 102 into a helical shape such that the tubular member 106 can circumferentially contact the walls of the body cavity along the length of the tubular member 106 sufficient to stabilize the tubular member within the body cavity. The method includes inserting the catheter 102 into the body cavity 122 with the actuation system 300 deactivated such that the tubular member 106 has its relaxed shape and / or inherent flexibility. The catheter 100 is then advanced within the body cavity to a desired location within the body cavity. The actuation system 300 is then actuated by applying a compressive force to the actuation element 302, thereby bending and stiffening the actuation element 302 into a helical shape such that the catheter 100 circumferentially contacts the walls of the body cavity. The circumferential contact stabilizes and / or anchors the catheter 100 within the body cavity.

[0112] Although specific embodiments have been disclosed and described, it should be understood that the above description is not intended to limit the scope of those embodiments. Although embodiments and variations of many aspects of the present invention have been disclosed and described herein, such disclosures are provided for the purpose of illustration and example only. Thus, various changes and modifications can be made without departing from the scope of the claims. For example, not all of the components described in the embodiments are necessary, and the present invention can include any suitable combination of the components described, and the overall shape and relative size of the components of the present invention can be changed. Thus, the embodiments are intended to illustrate alternatives, modifications, and equivalents that may be included in the scope of the claims. Thus, the present invention should not be limited, except to the following claims and their equivalents.

Claims

1. A catheter system comprising: an elongated flexible tubular member having an anchor portion having inherent flexibility; one or more actuators disposed on the tubular member, the one or more actuators having an unactuated state that allows the tubular member to have its relaxed shape and an actuated state in response to being actuated, the one or more actuators change a shape of the anchor portion to an anchor shape and further stiffen the anchor portion to the anchor shape, the anchor shape being configured to secure the anchor portion in a fixed position within a body lumen corresponding to the anchor shape; The catheter system is characterized in that it has: (a) an unactuated configuration in which the one or more actuators are unactuated so that the anchor portion of the tubular member has its inherent flexibility; and (b) an actuated configuration in which the one or more actuators are actuated such that the actuators stiffen the anchor portion into an anchor shape configured to fix the anchor portion in a fixed position within a body lumen corresponding to the anchor shape.

2. 2. The catheter system of claim 1, The catheter system, wherein the one or more actuators include an electroactive polymer actuator actuated by one or more electrical control signals.

3. The catheter system according to claim 2, 11. The catheter system of claim 1, further comprising a controller operably connected to the plurality of electroactive polymer actuators, the controller configured to selectively communicate electrical control signals to the plurality of electroactive polymer actuators.

4. The catheter system according to claim 3, 11. A catheter system comprising: a catheter controller coupled to the one or more electroactive polymer actuators by a plurality of conductors, each conductor having a first end connected to a respective electroactive polymer actuator and a second end connected to the controller.

5. The catheter system according to claim 4, The catheter system, wherein the electrical control signals include respective voltages applied to the one or more electroactive polymer actuators.

6. 2. The catheter system of claim 1, The catheter system, wherein the one or more actuators include a pressure actuator actuated by one or more pressure lumens coupled to the pressure actuator.

7. A catheter system. an elongated flexible tubular member having an anchor portion having inherent flexibility; one or more mechanical actuators disposed on the tubular member, the mechanical actuators configured to be actuated by one or more pull wires coupled to the mechanical actuators, the one or more actuators having an unactuated state that allows the tubular member to have its relaxed shape, and an actuated state in response to being actuated, the one or more mechanical actuators stiffen the anchor portions into an anchor shape, the anchor shapes securing the anchor portions in a fixed position within a body lumen corresponding to the anchor shapes; The catheter system is characterized in that it has: (a) an unactuated configuration in which the one or more actuators are unactuated so that the anchor portion of the tubular member has its inherent flexibility; and (b) an actuated configuration in which the one or more actuators are actuated such that the actuators stiffen the anchor portion into an anchor shape configured to fix the anchor portion in a fixed position within a body lumen corresponding to the anchor shape.

8. The catheter system according to claim 7, a catheter system comprising: an actuator element having an anisotropic region about a central axis of the tubular member, a first area having a first compliance and a second area having a second compliance different from the first compliance, wherein compressive loading of the actuator element by the one or more pull wires causes the actuator element to bend and stiffen into a preset shape.

9. 9. The catheter system of claim 8, A catheter system, wherein each actuator element includes a region of hypotube having a cut pattern that imparts a first compliance to the first area and a second compliance to the second area.

10. The catheter system according to claim 7, The catheter system, wherein the one or more mechanical actuators are also configured to change the shape of the anchor portion, the one or more mechanical actuators forming the anchor portion to the anchor shape in an actuated configuration.

11. A catheter system comprising: an elongated flexible tubular member; a plurality of electroactive polymer actuators disposed on the tubular member, the plurality of electroactive polymer actuators configured to form the tubular member into a substantially sinusoidal shape and to transition the shape of the tubular member back and forth between a substantially sinusoidal shape that is 0 degrees out of phase and a substantially sinusoidal shape that is 180 degrees out of phase; and a controller operably coupled to the plurality of electroactive polymer actuators, the controller configured to send control signals to the plurality of electroactive polymer actuators to dynamically cycle the tubular member back and forth between a substantially sinusoidal shape that is 0 degrees out of phase and a substantially sinusoidal shape that is 180 degrees out of phase.

12. The catheter system of claim 11, wherein the controller dynamically cycles a sinusoidal shape of the tubular member at an amplitude and frequency that reduces static friction of the tubular member as it is moved longitudinally within a body lumen.

13. The catheter system of claim 12, and wherein on a first side of the tubular member, the electroactive polymer actuators of the first set are disposed longitudinally along the tubular member and are interleaved with electroactive polymer actuators of a second set disposed longitudinally along the tubular member on the first side, and on a second side of the tubular member opposite the first side, the electroactive polymer actuators of the first set are disposed longitudinally along the tubular member and are interleaved with electroactive polymer actuators of a second set disposed along the tubular member on the second side, such that actuation of the first set of electroactive polymer actuators changes the shape of the tubular member to a substantially sinusoidal shape that is 0° out of phase and actuation of the second set of electroactive polymer actuators changes the shape of the tubular member to a sinusoidal shape that is 180° out of phase.

14. The catheter system of claim 13, a first set of electroactive polymer actuators electrically connected to the controller via a first pair of electrical connections, whereby all of the electroactive polymer actuators in the first set are actuated by a single first signal from the controller; a second set of electroactive polymer actuators connected to the controller via a second pair of electrical connections, whereby all of the electroactive polymer actuators in the first set are actuated by a single second signal from the controller; and the second pair of electrical connections being electrically isolated / separated from the first pair of electrical connections.

15. 1. A catheter system comprising: an elongated flexible tubular member; and an actuator disposed on the tubular member in a helical path along the tubular member, wherein actuation of the actuator causes the shape of the tubular member to change to a substantially helical shape thereby enabling the tubular member to circumferentially contact a wall of a body lumen along a length of the tubular member sufficient to stabilize the tubular member within the body lumen.

16. 16. The catheter system of claim 15, 1. A catheter system, comprising: a catheter configured such that a substantially helically shaped tubular member is in circumferential contact with a wall of a body lumen along substantially the entire insertable length of the tubular member.

17. 16. The catheter system of claim 15, The catheter system, wherein the actuator comprises an electroactive polymer actuator actuated by one or more electrical control signals.

18. 18. The catheter system of claim 17, 11. The catheter system of claim 10, further comprising a controller operably connected to the electroactive polymer actuator, the controller configured to selectively transmit electrical control signals to the electroactive polymer actuator.

19. 20. The catheter system of claim 18, 11. A catheter system comprising: a catheter body having an electroactive polymer actuator and a controller connected to the electroactive polymer actuator by a pair of conductors, each conductor having a first end connected to the electroactive polymer actuator and a second end connected to the controller.

20. 20. The catheter system of claim 18, The catheter system, wherein the electrical control signals include respective voltages applied to the electroactive polymer actuators.

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