US20140148673A1 - Method of anchoring pullwire directly articulatable region in catheter - Google Patents

Abstract

A catheter comprises a flexible polymer catheter body including a proximal shaft section and a distal working section, a wire support structure embedded within the distal working section of the catheter body, a proximal adapter mounted to the proximal shaft section of the catheter body, and a wire disposed within the catheter body. The wire has a proximal end and a distal end. The proximal end of the wire being operably connected to the proximal adapter, and the distal end of the wire is anchored to the wire support structure.

Description

FIELD OF INVENTION
• The invention relates generally to minimally-invasive instruments and systems, such as manually or robotically steerable catheter systems, and more particularly to steerable catheter systems for performing minimally invasive diagnostic and therapeutic procedures.
BACKGROUND
• Minimally invasive procedures are preferred over conventional techniques wherein the patient's body cavity is open to permit the surgeon's hands access to internal organs. Thus, there is a need for a highly controllable yet minimally sized system to facilitate imaging, diagnosis, and treatment of tissues which may lie deep within a patient, and which may be accessed via naturally-occurring pathways, such as blood vessels, other lumens, via surgically-created wounds of minimized size, or combinations thereof.
• Currently known minimally invasive procedures for the treatment of cardiac, vascular, and other disease conditions use manually or robotically actuated instruments, which may be inserted transcutaneously into body spaces such as the thorax or peritoneum, transcutaneously or percutaneously into lumens such as the blood vessels, through natural orifices and/or lumens such as the mouth and/or upper gastrointestinal tract, etc. Manually and robotically-navigated interventional systems and devices, such as steerable catheters, are well suited for performing a variety of minimally invasive procedures. Manually-navigated catheters generally have one or more handles extending from their proximal end with which the operator may steer the pertinent instrument. Robotically-navigated catheters may have a proximal interface configured to interface with a catheter driver comprising, for example, one or more motors configured to induce navigation of the catheter in response to computer-based automation commands input by the operator at a master input device in the form of a work station.
• In the field of electrophysiology, robotic catheter navigation systems, such as the Sensei® Robotic Catheter System (manufactured by Hansen Medical, Inc.), have helped clinicians gain more catheter control that accurately translates the clinician's hand motions at the workstation to the catheter inside the patient's heart, reduce overall procedures (which can last up to four hours), and reduce radiation exposure due to fluoroscopic imaging necessary to observe the catheter relative to the patient anatomy, and in the case of electrophysiology, within the relevant chamber in the heart. The Sensei® Robotic Catheter System employs a steerable outer catheter and a steerable inner electrophysiology (EP) catheter, which can be manually introduced into the patient's heart in a conventional manner. The outer and inner catheters are arranged in an “over the wire” telescoping arrangement that work together to advance through the tortuous anatomy of the patient. The outer catheter, often referred to as a guiding sheath, provides a steerable pathway for the inner catheter. Proximal adapters on the outer guide sheath and inner EP catheter can then be connected to the catheter driver, after which the distal ends of the outer sheath and inner EP catheter can be robotically manipulated in the heart chamber within six degrees of freedom (axial, roll, and pitch for each) via operation of the Sensei® Robotic Catheter System.
• While the Sensei® Robotic Catheter System is quite useful in performing robotic manipulations at the operational site of the patient, it is desirable to employ robotic catheter systems capable of allowing a physician to access various target sites within the human vascular system. In contrast to the Sensei® Robotic Catheter System, which is designed to perform robotic manipulations within open space (i.e., within a chamber of the heart) after the outer guide sheath and inner catheter are manually delivered into the heart via a relatively non-tortuous anatomical route (e.g., via the vena cava), and therefore may be used in conjunction with sheaths and catheters that are both axially and laterally rigid, robotic catheter systems designed to facilitate access to the desired target sites in the human vascular system require simultaneous articulation of the distal tip with continued insertion or retraction of an outer guide sheath and an inner catheter. As such, the outer guide sheath and inner catheter should be laterally flexible, but axially rigid to resist the high axial loads being applied to articulate the outer guide sheath or inner catheter, in order to track through the tortuous anatomy of the patient. In this scenario, the inner catheter, sometimes called the leader catheter extends beyond the outer sheath and is used to control and bend a guide wire that runs all the way through the leader catheter in an over-the-wire configuration. The inner catheter also works in conjunction with the outer guide sheath and guide wire in a telescoping motion to inchworm the catheter system through the tortuous anatomy. Once the guide wire has been positioned beyond the target anatomical location, the leader catheter is usually removed so that a therapeutic device can be passed through the steerable sheath and manually operated.
• Increasing the lateral flexibility of the sheath and catheter, however, introduces catheter navigation problems that may not otherwise occur when the sheath and catheter are laterally stiff. For example, many steerable catheters available today rely on the capability of the user to articulate the distal end of the catheter to a desired anatomical target. The predominant method for articulating the distal end of a catheter is to circumferentially space a multitude of free floating pullwires (e.g., four pullwires) into the wall of the catheter and attach them to a control ring embedded in the distal end of the catheter. The anchoring of each pullwire to the control ring is usually performed by soldering, welding, brazing, or gluing the pullwire to the control ring. If four pullwires are provided, the pullwires may be orthogonally spaced from each other. Each of these pullwires are offset from the center line of the catheter, and so when the wires are tensioned to steer the catheter tip, the resulting compressive forces cause the distal tip of the catheter to articulate in the direction of the pullwire that is tensioned. However, the compressive forces on the relatively flexible catheter shaft also cause undesired effects.
• For example, the axial compression on the catheter shaft during a steering maneuver that bends the distal end of the catheter may cause undesired lateral deflection in the catheter shaft, thereby rendering the catheter mechanically unstable.
• As another example, the curvature of the catheter shaft may make the articulation performance of the catheter unrepeatable and inconsistent. In particular, because the pullwires are offset from the neutral axis of the catheter shaft, bending the catheter shaft will tighten the pullwires on the outside of the curve, while slackening the pullwires on the inside of the curve. As a result, the amount of tension that should be applied to the pullwires in order to effect the desired articulation of the catheter distal end will vary in accordance with the amount of curvature that is already applied to the catheter.
• As still another example, when bent, the articulate catheter distal end will tend to curve align with the catheter shaft. In particular, as shown inFIGS. 1A and 1B, operating or tensioning a pullwire on the outside edge of a bend may cause the catheter to rotate or twist as the pullwire may tend to rotate the distal articulating section of the catheter until the pullwire is at the inside edge of the bend. This rotation or twist phenomenon or occurrence is known as curve alignment.
• That is, when the proximal shaft section of the catheter is curved (as it tracked through curved anatomy), and the distal section is required to be articulated in a direction that is not aligned with the curvature in the shaft, a wire on the outside of the bend is pulled, as shown inFIG. 1A. A torsional load (T) is applied to shaft as tension increases on the pull-wire on the outside of the bend. This torsional load rotates the shaft until the wire being pulled is on the inside of the bend, as shown inFIG. 1B. In effect, the tensioned wire on the outside of the bend will take the path of least resistance, which may often be to rotate the shaft to the inside of the bend rather than articulate the tip of the catheter adequately.
• This un-intentional rotation of the shaft causes instability of the catheter tip and prevents the physician from being able to articulate the catheter tip in the direction shown inFIG. 1A. That is, no matter which direction the catheter tip is intended to be bent, it will ultimately bend in the direction of the proximal curve. The phenomenon is known as curve alignment because the wire that is under tension is putting a compressive force on both the proximal and distal sections and so both the proximal and distal curvature will attempt to align in order to achieve lowest energy state. The operator may attempt to roll the entire catheter from the proximal end in order to place the articulated distal tip in the desired direction. However, this will placed the tensioned inside pullwire to the outside of the proximal bend causing further tensioning of the pullwire, and possibly causing the distal end of the catheter to whip around.
• All of these mechanical challenges contribute to the instability and poor control of the catheter tip, as well as increased catheter tracking forces. Some steerable catheters overcome these problems by increasing the axial stiffness of the entire catheter shaft (e.g., by varying wall thickness, material durometer, or changing braid configuration) or alternatively by incorporating axially stiff members within the catheter shaft to take the axial load. But these changes will also laterally stiffen the catheter shaft, thereby causing further difficulties in tracking the catheter through the vasculature of the patient. Therefore, the catheter designer is faced with having to make a compromise between articulation performance and shaft tracking performance. Other steerable catheters overcome this problem by using free floating coil pipes in the wall of the catheter to respectively housing the pullwires (as described in U.S. patent application Ser. No. 13/173,994, entitled “Steerable Catheter”, which is expressly incorporated herein by reference), thereby isolating the articulation loads from the catheter shaft. However, the use of coil pipes adds to the cost of the catheter and takes up more space in the result, resulting in a thicker catheter wall. Furthermore, because the relatively stiff coil pipes are spaced away from the neutral axis of the catheter, its lateral stiffness may be unduly increased.
• There, thus remains a need to provide a different means for minimizing the above-described mechanical challenges in a laterally flexible, but axially rigid, catheter.
• Furthermore, although a single region of articulation is typically sufficient to allow a user to track and steer the catheter though the vasculature, it is sometimes inadequate for tortuous anatomies, navigation of larger vessels, or for providing stability during therapy deployment.
• For example, it may be desirable to access either the right coronary artery or the left coronary artery from the aorta of the patient in order to remove a stenosis in the artery by, e.g., atherectomy, angioplasty, or drug delivery. The proximal curve of a catheter may be pre-shaped in a manner that locates the distal end of the catheter in an optimal orientation to access the ostium of the right coronary artery via the aorta, as shown inFIG. 2A. However, in the case where it is desirable to access the ostium of the left coronary artery, the proximal curve of the catheter locates the distal end of the catheter too far from the left coronary artery, which therefore cannot be easily accessed via manipulation of the distal end of the catheter, as shown inFIG. 2B. Alternatively, the proximal curve of a catheter may be pre-shaped in a manner that locates the distal end of the catheter in an optimal orientation to access the ostium of the left coronary artery via the aorta, as shown inFIG. 2C. However, in the case where it is desirable to access the ostium of the left coronary artery, the proximal curve of the catheter locates the distal end of the catheter too close to the right coronary artery, such that the distal end would be seated too deeply within the ostium of the right coronary artery, as shown inFIG. 2D. Thus, it can be appreciated that multiple catheters may have to be used to treat both the left coronary artery and right coronary artery, thereby increasing the cost and time for the procedure.
• To complicate matters even further, the articulating distal end of the catheter needs to be long enough to cross the aorta from the patient right side to the left coronary artery. However, there are varying anatomies in the population with respect to the positioning of the left coronary artery in the aorta. For example,FIG. 3A illustrates the proximal curve required for a catheter to place the distal end within the ostium of the left coronary artery in a “normal” anatomy;FIG. 3B illustrates the proximal curve required for a catheter to place the distal end within the ostium of the left coronary artery in a “wide” anatomy; andFIG. 3C illustrates the proximal curve required for a catheter to place the distal end within the ostium of the left coronary artery in an “unfolded” anatomy. It can be appreciated that, even if is desired to only treat the left coronary artery, the clinician may have to be supplied with multiple catheters, one of which can only be used for the particular anatomy of the patient.
• One way to address this problem in conventional catheters is to have multiple unique or independent regions of articulation in the catheter shaft by, e.g., adding a control ring and a set of pullwires for each articulation region. Thus, both a proximal region and a distal region of the catheter can be articulated. When manufacturing a catheter within only a single region of articulation, this task is not overly complex, typically requiring a single lamination of a polymer extrusion to form an outer jacket over an inner polymer tube (or liner) and the installation of the control ring with associated pullwires onto the assembly. A braided material can be installed between the inner polymer tube and outer polymer jacket to provide select region of the catheter with increased rigidity.
• However, when manufacturing a catheter that has two regions of articulation, this task can be difficult and usually requires the lamination of an outer polymer jacket extrusion up to the proximal articulation region, then the installation of the most proximal control ring with attached pullwires, and then the lamination of an outer polymer jacket for the remaining portion of the catheter. For catheters with more than two regions of articulation, this process would have to be repeated for each and every additional region of articulation. Another issue with respect to the use of control rings is that the laminated polymer extrusion or extrusions need to be carefully sized at the control ring, since the ring itself consumes volume in the wall that not only requires thinner extrusions so as to not have a bulge in the catheter at the control ring, but also creates a significantly stiffer region the length of the control ring, which causes a “knuckle” where there should be a gradual stiffness change required to achieve good catheter performance during tracking through the vasculature.
• There, thus, remains a need to provide a more efficient means for anchoring the distal ends of the pullwires at the articulating region or regions of a catheter.
• As briefly mentioned above, the inner catheter and guide wire may be arranged in an “over-the-wire” configuration. However, such a configuration requires the guide wire to be at least twice as long as the inner catheter in order to allow the user to continuously hold the guide wire in place as the inner catheter is removed from the outer guide sheath. For example, the inner catheter can have a length up to 160 cm, with 140 cm of the catheter being inside the patient. Therefore, to ensure that the position of the guide wire is maintained, the physician will typically require a guide wire to be over 300 cm long. However, guide wires longer than 300 cm are not readily available in sterile catheter laboratories. Additionally, long guide wires require an extra assistant at the bedside to manage the guide wire and ensure it remains in a fixed position and always remains sterile. Furthermore, such a configuration disadvantageously increases the length of the robot required to axially displace the guide wire within the inner catheter to the fullest extent. The increased size of the robot may be impractical and too big and heavy to be mounted on a table in a catheter lab environment. Additionally, because the inner catheter passes entirely “over-the-wire,” the inner catheter cannot be robotically removed while holding the guide wire in place. Instead, the physician needs to remove the guide wire from the robot, and then slide the inner catheter proximally while holding the position of the guide wire fixed. The procedure time for removing the inner catheter from the outer guide sheath is increased for an over-the wire configuration (typically greater than one minute), thereby increasing fluoroscopic time and radiation exposure to the physician and staff.
• A “rapid exchange” leader catheter would alleviate these concerns. Rapid exchange catheter designs have been described and documented in balloon angioplasty catheters, filters, and stent delivery system applications. These designs provide a rapid exchange port on the distal portion of the catheter shaft, which allows the guide wire to exit and run parallel to the proximal portion of the catheter shaft. However, no known designs exist for rapid exchange steerable catheters due to the challenge of navigating the pullwires proximal of the exit port. In addition, no known designs exist for the robotic interface for rapid exchange catheters.
• There, thus, remains a need to provide the inner steerable catheter of a telescoping catheter assembly with a rapid exchange architecture.
SUMMARY OF THEINVENTION 2
• In accordance with one aspect of the present inventions, a catheter comprises a flexible polymer catheter body including a proximal shaft section and a distal working section. The cross-sectional shape of the catheter body may be any suitable shape, such as circular or rectangular. The catheter may optionally comprise a lumen extending through the catheter body. The catheter further comprises a wire support structure (e.g., a braided tubular structure or a coiled structure) embedded within the distal working section of the catheter body, and a proximal adapter mounted to the proximal shaft section of the catheter body. The catheter further comprises a wire disposed within the catheter body. The wire has a proximal end operably connected to the proximal adapter, and a distal end anchored to the wire support structure. The wire support structure comprises a plurality of tubular layers, in which case, the distal end of the wire may be anchored between the tubular layers of the wire support structure.
• In one embodiment, the catheter further comprises a lumen disposed within the catheter body, in which case, the wire is a pullwire extending through the lumen, the distal working section of the catheter body is a distal articulatable section, and the proximal adapter is a proximal steerable interface that is manipulatable to selectively tension the pullwire to bend the distal articulating section. In another embodiment, the catheter further comprises an electrode mounted to the distal working section of the catheter body, in which case, the wire is an electrical wire, the distal end of which is electrically coupled to the electrode.
• In accordance with another aspect of the present inventions, a method of constructing a catheter comprises disposing a wire support structure over an inner polymer tube (e.g., one having a lumen extending therethrough). The wire support structure may be disposed on the inner polymer tube by braiding filament onto the inner polymer tube. The method further comprises disposing at least one outer polymer tube over the wire support structure and wire, applying heat to the melt the outer polymer tube(s), thereby flowing the melted outer polymer tube(s) into the wire support structure. The method further comprises allowing the melted outer polymer tube(s) to solidify, thereby integrating the wire support structure, inner polymer tube, and solidified outer polymer tube(s) together into a catheter body, disposing a wire through the catheter body, and anchoring (e.g., soldering, welding, brazing, or gluing) a distal end of the wire to the wire support structure at a distal end of the catheter body. In one method, the wire support structure comprises a plurality of tubular layers, in which case, the distal end of the wire may be anchored between the tubular layers of the wire support structure. The method may further comprise mounting a proximal adapter to a proximal end of the catheter body, and operatively coupling a proximal end of the wire to the proximal adapter.
• An optional method may comprise disposing a barrier over the wire support structure prior to melting the outer tube(s), with the melting temperature of the barrier being greater than the temperature of the heat applied to the outer polymer tube(s). This method may further comprise removing the barrier from the catheter body subsequent to allowing the melted outer tube(s) to solidify, thereby exposing a portion of the wire support structure. In this case, the distal end of the wire is anchored to the exposed portion of the wire support structure. The barrier may be a tubular barrier, in which case, the exposed portion of the wire support structure may be cylindrical. The optional method may further comprise disposing another outer polymer tube over the exposed cylindrical portion of the wire support structure, melting the other polymer tube, thereby flowing the other outer polymer tube into the exposed cylindrical portion of the wire support structure, and allowing the other melted outer polymer tube to solidify.
• Another method further comprises forming a lumen within the catheter body, the wire is a pullwire extending through the lumen, and the proximal adapter is a proximal steerable interface. In this case, forming the lumen in the catheter body may comprise disposing a process mandrel over the inner polymer tube prior to melting the at least one outer tube, and removing the process mandrel from the catheter body subsequent to allowing the melted outer tube(s) to solidify, and disposing the wire through the catheter body may comprise threading the wire through the lumen.
• In still another method, the wire is an electrical wire, and the method further comprises forming an electrode to the catheter body in electrical communication with the wire. In this case, forming the electrode on the catheter body may comprise disposing a barrier over the wire support structure prior to melting the outer tube(s), removing the barrier from the catheter body subsequent to allowing the melted outer tube(s) to solidify, thereby exposing a portion of the wire support structure, and disposing the electrode on the exposed portion of the wire support structure.
• Other and further aspects and features of the invention will be evident from reading the following detailed description of the preferred embodiments, which are intended to illustrate, not limit, the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
• The drawings illustrate the design and utility of various embodiments of the present invention, in which similar elements are referred to by common reference numerals. In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the present inventions briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
• FIGS. 1A and 1B are plan views showing a curve alignment phenomenon that may occur when articulating a prior art steerable catheter;
• FIGS. 2A-2D are plan views showing possible issues related to using a prior art catheter having a single region of articulation for accessing both the left coronary artery and a right coronary artery of a patient's anatomy;
• FIGS. 3A-3C are plan views showing possible issues related to using a prior art catheter having a single region of articulation for accessing different left coronary artery anatomies;
• FIG. 4 is a perspective view of a medical robotic system constructed in accordance with one embodiment of the present inventions;
• FIG. 5 is a perspective view of a robotic catheter assembly used in the medical robotic system ofFIG. 4;
• FIG. 6 is a perspective view of the catheter assembly used in the robotic catheter assembly ofFIG. 5;
• FIG. 7 is a plan view of one catheter having a single region of articulation with four pullwires for use in the catheter assembly ofFIG. 6;
• FIGS. 7A-7C are cross-sectional views of the catheter ofFIG. 7, respectively taken along thelines7A-7A,7B-7B, and7C-7C;
• FIG. 8 is a perspective view of an adapter used to transition pullwires from one circumferential orientation to another circumferential orientation in the catheter ofFIG. 7;
• FIG. 9 is another perspective view of the adapter ofFIG. 8;
• FIG. 10 is a diagram showing the neutral axis of the bend in a distal articulating section of the catheter ofFIG. 7;
• FIG. 11 is a cross-sectional view of the proximal shaft of the catheter of claim7, particularly showing the location of a neural bending axis relative to the pullwires;
• FIG. 12 is a cross-sectional view of the proximal shaft of a prior art catheter of claim7, particularly showing the location of a neural bending axis relative to the pullwires;
• FIG. 13 is a plan view of one catheter having a single region of articulation with three pullwires for use in the catheter assembly ofFIG. 6;
• FIGS. 13A-13C are cross-sectional views of the catheter ofFIG. 13, respectively taken along thelines13A-13A,13B-13B, and13C-13C;
• FIG. 14 is a perspective view of an adapter used to transition pullwires from one circumferential orientation to another circumferential orientation in the catheter ofFIG. 13;
• FIG. 15 is a top view of the adapter ofFIG. 14;
• FIG. 16 is another perspective view of the adapter ofFIG. 14;
• FIG. 17 is a plan view of a rapid exchange catheter having a single region of articulation with four pullwires for use in the catheter assembly ofFIG. 18;
• FIGS. 17A-17C are cross-sectional views of the catheter ofFIG. 17, respectively taken along thelines17A-17A,17B-17B, and17C-17C;
• FIG. 18 is a side view of a rapid exchange catheter assembly that can alternatively be used in the robotic catheter assembly ofFIG. 5;
• FIG. 19 is a plan view of one catheter having two regions of articulation with four pullwires for use in the catheter assembly ofFIG. 6;
• FIGS. 19A-19C are cross-sectional views of the catheter ofFIG. 19, respectively taken along thelines19A-19A,19B-19B, and19C-19C;
• FIGS. 20 and 21 are plan views showing one method of accessing the left coronary artery of an anatomy using the catheter ofFIG. 19;
• FIG. 20A is a cross-sectional view of the distal articulating region of the catheter shown inFIG. 20, respectively taken along theline20A-20A;
• FIG. 21A is a cross-sectional view of the proximal articulating region of the catheter shown inFIG. 21, respectively taken along theline21A-21A;
• FIGS. 22 and 23 are plan views showing one method of accessing the right coronary artery of an anatomy using the catheter ofFIG. 19;
• FIG. 22A is a cross-sectional view of the distal articulating region of the catheter shown inFIG. 20, respectively taken along theline22A-22A;
• FIG. 23A is a cross-sectional view of the proximal articulating region of the catheter shown inFIG. 23, respectively taken along theline23A-23A;
• FIGS. 24A-24C are plan views showing methods of accessing the left coronary arteries of different anatomies using the catheter ofFIG. 19;
• FIG. 25 is a plan view of another catheter having two regions of articulation with four pullwires for use in the catheter assembly ofFIG. 6;
• FIGS. 25A-25D are cross-sectional views of the catheter ofFIG. 25, respectively taken along thelines25A-25A,25B-25B,25C-25C, and25D-25D;
• FIG. 26 is a plan view of a multi-bend segment of the catheter ofFIG. 25, particularly showing a distal articulation angle and a proximal articulation angle;
• FIG. 27 is a plan view showing a method of accessing a renal artery using the catheter ofFIG. 25;
• FIG. 28 is a control diagram illustrating a multi-bend algorithm that control the distal articulating section and proximal articulating section of the catheter ofFIG. 25;
• FIG. 29 is a diagram illustrating the moment applied to the transition section of the catheter ofFIG. 25 caused by the pullwires extending through the transition section;
• FIGS. 30A and 30B are plan views showing one method of accessing the right coronary artery of an anatomy using the catheter ofFIG. 25;
• FIGS. 31A-31I are plan views illustrating one method of directly anchoring a pullwire to the braid of a steerable catheter;
• FIG. 32 is a plan view illustrating one embodiment of a braiding machine that can be used to braid a catheter for use in the catheter assembly ofFIG. 6;
• FIGS. 33A and 33B are front views of interchangeable nose cones that can be used in the braiding machine ofFIG. 32;
• FIG. 34 is a plan view illustrating another embodiment of a braiding machine that can be used to braid a catheter for use in the catheter assembly ofFIG. 6;
• FIG. 35 is a front view of a nose cone that can be used in the braiding machine ofFIG. 34;
• FIG. 36 is a perspective view of an iris assembly that can be used in the nose cone ofFIG. 35;
• FIG. 37 is a side view of the iris assembly ofFIG. 36;
• FIG. 38 is an axial view of the iris assembly ofFIG. 36, particularly showing the iris assembly in a first position that groups three wire mandrels circumferentially adjacent each other;
• FIG. 39 is an axial view of the iris assembly ofFIG. 36, particularly showing the iris assembly in a second position that spaces three wire mandrels equidistant from each other;
• FIG. 40 is an axial view of a first iris plate for use in the iris assembly ofFIG. 36;
• FIG. 41 is an axial view of a second iris plate for use in the iris assembly ofFIG. 36; and
• FIG. 42 is an axial view of a third iris plate for use in the iris assembly ofFIG. 36.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
• Referring toFIG. 4, one embodiment of arobotic catheter system10 constructed in accordance with the present invention will now be described. Thesystem10 generally comprises an operating table12 having a movable support-arm assembly14, anoperator control station16 located remotely from the operating table12, and arobotic catheter assembly18 mounted to the support-arm assembly14 above the operating table12. Exemplary robotic catheter systems that may be modified for constructing and using embodiments of the present invention are disclosed in detail in the following U.S. patent applications, which are all expressly incorporated herein by reference in their entirety: U.S. patent application Ser. No. 11/678,001, filed Feb. 22, 2007; U.S. patent application Ser. No. 11/073,363, filed Mar. 4, 2005; U.S. patent application Ser. No. 11/179,007, filed Jul. 6, 2005; U.S. patent application Ser. No. 11/418,398, filed May 3, 2006; U.S. patent application Ser. No. 11/481,433, filed Jul. 3, 2006; U.S. patent application Ser. No. 11/637,951, filed Dec. 11, 2006; U.S. patent application Ser. No. 11/640,099, filed Dec. 14, 2006; U.S. Patent Application Ser. No. 60/833,624, filed Jul. 26, 2006; and U.S. Patent Application Ser. No. 60/835,592, filed Aug. 3, 2006.
• Thecontrol station16 comprises amaster input device20 that is operatively connected to therobotic catheter assembly18. A physician orother user22 may interact with themaster input device20 to operate therobotic catheter assembly18 in a master-slave arrangement. Themaster input device20 is connected to therobotic catheter assembly18 via acable24 or the like, thereby providing one or more communication links capable of transferring signals between thecontrol station16 and therobotic catheter assembly18. Alternatively, themaster input device20 may be located in a geographically remote location and communication is accomplished, at least in part, over a wide area network such as the Internet. Themaster input device20 may also be connected to therobotic catheter assembly18 via a local area network or even wireless network that is not located at a geographically remote location.
• Thecontrol station16 also comprises one ormore monitors26 used to display various aspects of therobotic instrument system10. For example, an image of the sheath and leader catheter (described in further detail below) may be displayed in real time on themonitors26 to provide thephysician22 with the current orientation of the various devices as they are positioned, for example, within a body lumen or region of interest. Thecontrol station16 further comprises a processor in the form of acomputer28, which may comprise a personal computer or other type of computer work station for accurately coordinating and controlling actuations of various motors withinrobotic catheter assembly18.
• The support-arm assembly14 is configured for movably supporting therobotic catheter assembly18 above the operating table12 to provide convenient access to the desired portions of the patient (not shown) and provide a means to lock thecatheter assembly18 into position subsequent to the preferred placement. In this embodiment, the support-arm assembly14 comprises a series ofrigid links30 coupled by electronically brakedjoints32, which prevent joint motion when unpowered, and allow joint motion when energized by thecontrol station16. In an alternative embodiment, therigid links30 may be coupled by more conventional mechanically lockable joints, which may be locked and unlocked manually using, for example, locking pins, screws, or clamps. Therigid links30 preferably comprise a light but strong material, such as high-gage aluminum, shaped to withstand the stresses and strains associated with precisely maintaining three-dimensional position of the weight of thecatheter assembly18.
• Referring further toFIGS. 5 and 6, therobotic catheter assembly18 will now be described in detail. Therobotic catheter assembly18 comprises arobotic instrument driver34, arobotic guide sheath36, arobotic leader catheter38, and aguide wire40 mounted to theinstrument driver34 in a coaxial relationship. Therobotic catheter assembly18 may also include a drape (not shown) that covers theinstrument driver34. As will be described in further detail below, theinstrument driver34 provides robotic steering actuation, as well as robotic insertion and retraction actuation, to theguide sheath36, workingcatheter38, and guidewire40 in accordance with control signals transmitted from the control station16 (shown inFIG. 4). Theguide sheath36 generally includes asheath body42 having aproximal end44 and adistal end46, as well as a proximal interface in the form of a guide sheath steering adapter48 (“splayer”) operably coupled to theproximal end44 of thesheath body42. Theleader catheter38 generally includes acatheter body50 having aproximal end52 and adistal end54, as well as a proximal interface in the form of a leadercatheter steering adapter56 operably mounted to theproximal end52 of thecatheter body50. Theguide wire40 generally includes aguide wire body58 having aproximal end60 and adistal end62.
• Theinstrument driver34 comprises ahousing64 that contains motors (not shown). Therespective adapters48,56 and theproximal end60 of theguide wire body58 are mechanically interfaced to thehousing64 in such a manner that they may be axially displaced relative to each other via operation of the motors, thereby effecting insertion or retraction movements of therespective guide sheath36,leader catheter38, and guidewire40 relative to each other, and thus, relative to the operating table12 (shown inFIG. 4).
• To this end, theguide sheath36 comprises a working lumen (not shown inFIGS. 5 and 6) that extends all the way through thesheath body42. The geometry and size of the working lumen will be selected in accordance with the cross-sectional geometry and size of thelead catheter38. Thesheath body42 may be composed of a low-friction inner layer (e.g., a coating of silicone or polytetrafluoroethylene) to provide a low-friction surface to accommodate movement of theleader catheter38 within the working lumen. Thelead catheter38 passes through the lumen of theguide sheath36, and is thus, moveable relative thereto. As shown inFIGS. 5 and 6, theleader catheter38 projects distally with respect to thedistal end46 of thesheath body42. Of course, theleader catheter38 may be withdrawn proximally such that itsdistal end54 is substantially flush with thedistal end46 of thesheath body42, or withdrawn proximally even further such that itsdistal end54 is disposed within thedistal end46 of thesheath body42. Theleader catheter38 may be movably positioned within the working lumen of theguide sheath36 to enable relative insertion of the two devices, relative rotation, or “roll” of the two devices, and relative steering or bending of the two devices relative to each other, particularly when thedistal end54 of theleader catheter38 is inserted beyond the distal tip of theguide sheath36.
• Similarly, theleader catheter38 comprises a working lumen (not shown inFIGS. 5 and 6) that extends at least partially through thecatheter body50. The geometry and size of the working lumen will be selected in accordance with the cross-sectional geometry and size of theguide wire40. Thecatheter body50 may be composed of a low-friction inner layer (e.g., a coating of silicone or polytetrafluoroethylene) to provide a low-friction surface to accommodate movement of theguide wire40 within the working lumen. Theguide wire40 passes through the lumen of theleader catheter38, and is thus, moveable relative thereto. As shown inFIGS. 5 and 6, theguide wire40 projects distally with respect to thedistal end54 of thecatheter body50. Of course, theguide wire40 may be withdrawn proximally such that itsdistal end62 is substantially flush with thedistal end54 of thecatheter body50, or withdrawn proximally even further such that itsdistal end62 is disposed within thedistal end62 of thecatheter body50. Theguide wire40 may be movably positioned within the working lumen of theleader catheter38 to enable relative insertion of the two devices, relative rotation, or “roll” of the two devices, and relative steering or bending of the two devices relative to each other, particularly when thedistal end62 of theguide wire40 is inserted beyond the distal tip of theleader catheter38. Notably, by movably positioning theguide wire40 relative to theleader catheter38, and movably positioning theleader catheter38 relative to theguide sheath36, the bending stiffness of the assembly may be varied as needed to optimize the tracking ability of theleader catheter38.
• Each of theadapters48,56 also comprises one or more rotating spools ordrums66 that can selectively tension or release pullwires (not shown inFIG. 6) disposed within therespective sheath body42 andcatheter body50, thereby effecting a single articulation (and optionally, multiple articulations) of the distal ends46,54 of the sheath andcatheter bodies42,50. In the illustrated embodiment, each of theadapters48,56 comprises four rotating spools or drums66 (only one shown for theproximal adapter48, and only three shown for the proximal adapter56) for four corresponding pullwires. Theinstrument driver34 further comprises aguide wire driver68 to which the proximal end of theguide wire body58 is affixed. Thedistal end62 of theguide wire body58 may have a J-shape as is conventional for guide wires. Each of theadapters48,56 andguide wire driver68 may optionally be capable of rotating or rolling thesheath body42,catheter body50, and guidewire body58 relative to each other.
• With reference now toFIG. 7, an embodiment of a flexible and steerableelongate catheter100 will be described. Thecatheter100 can be used as either of theguide sheath36 orleader catheter38 illustrated inFIGS. 5 and 6, and can be operably coupled to theinstrument driver34 via a proximal adapter101 (e.g., either ofproximal adapters48,56). Thecatheter100 is substantially pliable or flexible, such that when it is advanced into a patient, an operator or surgeon may easily manipulate thecatheter100 to conform, adopt, or match the shape or curvatures of the internal pathways (e.g., gastrointestinal tract, blood vessels, etc.) of the patient.
• Thecatheter100 generally includes anelongate catheter body102, which in the illustrated embodiments, has a circular cross-section, although other cross-sectional geometries, such as rectangular, can be used. As will be described in further detail below, thecatheter body102 may be comprised of multiple layers of materials and/or multiple tube structures that exhibit a low bending stiffness, while providing a high axial stiffness along the neutral axis. Typical designs include a nitinol spine encapsulated in braid and any flexible, pliable, or suitable polymer material or bio-compatible polymer material or a braided plastic composite structure composed of low durometer plastics (e.g., nylon-12, Pebax®, polyurethanes, polyethylenes, etc.).
• Thecatheter100 further includes a workinglumen104 disposed through the entire length of thecatheter body102 for delivering one or more instruments or tools from the proximal end of thecatheter body102 to the distal end of thecatheter body102. The nature of the workinglumen104 will depend on the intended use of thecatheter100. For example, if thecatheter100 is to be used as the guide sheath36 (shown inFIG. 6), the workinglumen104 will serve to accommodate the leader catheter or working catheter38 (shown inFIG. 6). If thecatheter100 is to be used as a leader catheter or working catheter, the workinglumen104 will serve to accommodate a guide wire40 (shown inFIG. 6).
• To enable steering, thecatheter100 further includes a control ring106 (shown in phantom) secured around the workinglumen104 at any location, section, portion, or region along the length of thecatheter body102, a plurality ofpullwires108 housed within one ormore lumens110 extending through thecatheter body102, and a proximal adapter (not shown). Each ofpullwires108 may be a metallic wire, cable or filament, or it may be a polymeric wire, cable or filament. Thepullwire108 may also be made of natural or organic materials or fibers. Thepullwire108 may be any type of suitable wire, cable or filament capable of supporting various kinds of loads without deformation, significant deformation, or breakage.
• The distal ends of thepullwires108 are anchored or mounted to thecontrol ring106, such that operation of thepullwires108 may apply force or tension to thecontrol ring106, which may steer or articulate (e.g., up, down, pitch, yaw, or any direction in-between) the pertinent location, section, portion, or region of thecatheter100, which may in effect provide or define various bend radii for the articulated portion of thecatheter100. In the illustrated embodiment, thecontrol ring106 is secured to the distal end of thecatheter100, and therefore, the distal end of thecatheter100 will articulate when any of thepullwires108 are tensioned. The proximal ends of thepullwires108 terminate in theproximal adapter101, and in particular, spools ordrums103 located within theproximal adapter101. Thus, robotic or manual actuation of the proximal interface will cause the pertinent location, section, portion, or region of thecatheter100 to articulate in the direction of the pullwire orpullwires108 that are tensioned. Thecatheter100 may alternatively be manually controlled, in which case, it may include a conventional manually controlled steerable interface (not shown).
• In other embodiments, no control ring may be used. Instead, the distal ends of thepullwires108 may be attached directly to a section or portion of thecatheter body102 where it may be steered, articulated, or bent, as described in an alternative embodiment below. The wires may be crimped, soldered, welded or interlocked in any suitable manner to a specific location on a bending section or portion of thecatheter body102. In some embodiments there may be more than onecontrol ring106 secured to thecatheter body102 or more than one control wire attachment control locations, sections, or portions for controlling, steering, or articulating more than one section or portion of thecatheter body102, e.g., into various complex shapes or curvatures (e.g., “S” curved shapes or “J” curved shapes, etc.). For example, thecatheter100 may be steered, articulated, or deflected into various complex shapes or curvatures that may conform to various complex shapes or curvatures of internal pathways of a patient to reach a target tissue structure of an organ inside the patient.
• In this embodiment, thecatheter100 is functionally divided into four sections: adistal tip112, a distal articulatingsection114, atransition section116, and aproximal shaft section120.
• Thedistal tip112 includes an atraumaticrounded tip portion122 and acontrol portion124 in which thecontrol ring106 is mounted. Thedistal tip112 also includes an exit port (not shown) in communication with the workinglumen104 and from which a working catheter or guidewire may extend distally therefrom. In one embodiment, the atraumaticrounded tip portion122 is 2 mm in length and is composed of a suitable polymer material (e.g., Pebax® 55D/35D); and thecontrol portion124 is 1 mm in length and is composed of a suitable polymer material (e.g., Pebax® 35D).
• In the distal articulatingsection114, there are fourpullwire lumens110 that are equally spaced in an arcuate manner (i.e., ninety degrees apart), and thus, the fourcorresponding pullwires108 are equally spaced as well. In an alternative embodiment, a different number ofpullwires lumens110, and thus, pullwires108, can be used. For example, threepullwire lumens110, and thus threepullwires108, can be equally spaced in an arcuate manner (i.e., one hundred twenty degrees apart) in the distal articulatingsection114. Thus, thepullwires108 are mounted to thecontrol ring106 in orthogonal positions (i.e., ninety degrees apart), such that tensioning one of thepullwires108 will selectively articulate the distal articulatingsection114 in one of four orthogonal directions. Tensioning two of thepullwires108 will allow the pertinent section to be articulated in an infinite number of directions (effectively, providing two degrees of freedom: pitch and roll).
• The distal articulatingsection114 preferably allows for a moderate degree of axial compression and optimal lateral flexibility. In one embodiment, the distal articulatingsection114 is 30 mm in length. Thepullwire lumens110 extend through the distal articulatingsection114 and may be constructed of a low friction material or may simply be unsupported tubular cavities in which thepullwires108 respectively float. Theentire working lumen104 within the distal articulatingsection114 is formed by an inner polymer tube (e.g., 0.001″ thick PTFE). The distal articulatingsection114 has a several portions of differing rigidities formed by having different polymer outer tubes. For example, the distal articulatingsection114 may include a 5 mmrigid portion126 having a moderately rigid outer polymer tube (e.g., Pebax® 55D) and a 25mm articulatable portion128 having an outer tube composed of a relatively flexible outer polymer tube (e.g., Pebax® 35D). The length of thearticulatable portion128 can vary depending on the performance requirements for thecatheter100. Alonger articulatable portion128 may be beneficial to increase the area of reach, while ashorter articulatable portion128 may be beneficial for cannulating tight side branches in the anatomical vasculature. To increase its axial rigidity and elastic properties, thearticulatable portion128 comprises a double braided layer (e.g., sixteen 0.0005″×0.003″ spring temper 304V stainless steel wires braided at 68 picks per inch (ppi) in a 2 over 2 pattern) embedded within the outer polymer tube. As will be described in further detail below, the distal ends of thepullwires108 may be directly anchored between the two layers of the braid.
• Thetransition section116 resists axial compression to clearly define the proximal end of the distal articulatingsection114 and transfer the motion of thepullwires110 to the distal articulatingsection114, while maintaining lateral flexibility to allow thecatheter100 to track over tortuous anatomies. Thetransition section136 may be 28 mm in length and be composed of an outer polymer tube (e.g., Pebax® 55D). Significantly, thetransition section116 transitions the fourlumens110 in the distal articulatingsection114 to a singlehollow stiffening tube130 in theproximal shaft section120. With further reference toFIGS. 8 and 9, the illustrated embodiment accomplishes this by using a moldedadapter138, which may be mounted within the outer polymer tube of thetransition body section120.
• Theadapter138 includes anadapter body140 having aproximal end142 that interfaces with stiffeningtube130 in theproximal shaft section120, and adistal end144 that interfaces with the fourpullwire lumens110 in the distal articulatingsection114. Theadapter body140 may be composed of a suitable rigid material, such as stainless steel or a glass-filled or high durometer plastic. Theadapter138 further includes a plurality ofchannels146 formed in the external surface of theadapter body140, a square-shapedboss148 formed at thedistal end144 of theadapter body140, a plurality oflumens150 extending throughboss148, and asingle port152 formed in theproximal end142 of theadapter body140. Thelumens150 within theboss148 are equally spaced from each other in coincidence with the equally spacedlumens110 in the distal articulatingsection114 of thecatheter100. In particular, the fourlumens150 are respectively disposed through the four corners of theboss148. Thelumens150 within theboss148 are also respectively coincident with the distal ends of thechannels146, and thesingle port152 is coincident with the proximal ends of thechannels146. One of thechannels146 linearly extends along the length of theadapter body140, while the remaining threechannels146 spiral around the length of theadapter body140, so that the proximal ends of all fourchannels146 converge into thesingle port152. Thus, the fourpullwires108 extend proximally from the distal articulatingsection114, into thelumens150 formed in theboss148 of theadapter body140, along thechannels146, into thesingle port152, and then into the stiffeningtube130.
• Theadapter138 further includes a workinglumen154 extending through theboss148 and a distal portion of theadapter body140. The distal end of the workinglumen154 is in coincidence with the portion of the workinglumen104 extending through the distal articulatingsection114. The proximal end of the workinglumen130 exits theadapter body140 just proximal to thesingle port152, such that it is in coincidence with the lumen of thetransition section136, which, in turn, is in coincidence with the workinglumen104 extending through theproximal shaft section120. In the same manner that the workinglumen104 and stiffeningtube130 are offset from the axis of the proximal shaft section120 (as described below), the workinglumen154 andsingle port152 are offset from the axis of theadapter body140. It should be appreciated that the use of theadapter138 allows the fourpullwires108 to be transitioned from therespective lumens110 of the distal articulatingsection114 into thesingle stiffening tube130 without having to spiral thepullwires108 and corresponding lumens through the wall of thecatheter tube102, thereby allowing the thickness of the wall to be uniform and minimizing the possibility of weakened regions in thecatheter tube102 and possible inadvertent kinking. Therefore, it is particularly suitable for thin walled catheters.
• As will be described below in further embodiments, where wall thicknesses are not as thin, instead of using theadapter140, the equally spacedpullwire lumens110 from the distal articulatingsection114 may be gradually converged via thetransition section116 onto one side of theproximal shaft section120 and into the stiffeningtube130.
• Referring back toFIG. 7, theproximal shaft section120 combines lateral flexibility (which is needed for optimal tracking) with axial stiffness (which is needed for optical articulation performance). Theproximal shaft section120 represents the majority of the length of thecatheter100. Theentire working lumen104 within theproximal shaft section120 is formed by an inner polymer tube (e.g., 0.001″ thick PTFE).
• Theproximal shaft section120 gradually transitions thecatheter100 from the transition section118 to the more rigid remaining portion of thecatheter100 by having several portions of differing rigidities formed by having different polymer outer tubes. For example, theproximal shaft section120 may include a first 6 mmproximal portion132 including outer polymer tube (e.g., Pebax® 55D); a second 7.5 mmproximal portion134 including an outer polymer tube (e.g., Pebax® 72D) that is more laterally rigid than the outer polymer tube in the firstproximal portion128; and a third lengthy (e.g., 1 meter long)proximal shaft section136 including an outer polymer tube (e.g., Nylon-12) that is resistant to rotational forces to reduce the effect of curve alignment when thecatheter100 is contorted to the tortuous anatomy. To increase its axial rigidity, theproximal shaft section120 comprises a double braided layer (e.g., sixteen 0.0005″×0.003″ spring temper 304V stainless steel wires braided at 68 picks per inch (ppi) in a 2 over 2 pattern) embedded within the outer polymer tube.
• Significantly, unlike with the distal articulatingsection114 in which thepullwires108 are disposed in equally spaced apart lumens, thepullwires108 in theproximal shaft section120 are disposed in one or more lumens on one arcuate side of theproximal shaft section120. In the illustrated embodiment, the one or more lumens takes the form of the previously mentionedstiffening tube130 disposed along thecatheter body102 along theproximal shaft section120, and through which thepullwires108 are housed and passed back to theproximal adapter101. As will be described in further embodiments below, the one or more lumens may take the form of a plurality of tubes that respectively house thepullwires108.
• The inner diameter of the stiffeningtube130 is preferably large enough to allow thepullwires108 to slide freely without pinching each other. The stiffeningtube130 is composed of a material that is more axially rigid than the surrounding material in which thecatheter body102 is composed. For example, the stiffeningtube130 may take the form of a stainless steel hypotube or coil pipe, while thecatheter body102 along theproximal shaft section120 may be composed of a more flexible polymer or polymer composite, as will be described in further detail below. The stiffeningtube130 must be laminated into thecatheter body102, thereby allowing the stiffeningtube130 to support the axial loads on thecatheter100 from the tensioning of thepullwires108. Due to the non uniform stiffness in the catheter cross section, the neutral axis will no longer be in the geometric center of thecatheter body102 along theproximal shaft section120, but rather be shifted closer to the axis of the stiffeningtube130, thereby minimizing the impact on bending stiffness. Thus, by locating thepullwires108 in one lumen (i.e., the stiffening tube130) in thecatheter body102, and designing thecatheter body102 to be relatively flexible, thereby controlling the location of the neutral axis, an axially stiff, but laterally flexible,proximal shaft section120 can be achieved.
• The effects of bending stiffness relative to the neutral axis will now be described. The neutral axis can be considered the axis in the cross-section of a beam or shaft along which there are no longitudinal stresses or strains when the beam or shaft is bent. If the cross-section of the beam or shaft is symmetrical, isotropic, and is not curved before a bend occurs, then the neutral axis is at the geometric centroid of the cross-section. When the bend occurs, all fibers on one side of the neutral axis are in a state of tension, while all fibers on the other side of the neutral axis are in a state of compression. As shown inFIG. 10, the axial strain E is given by the ratio y/R, where y is the distance from the neutral axis, and R is the radius of curvature of the neutral axis. It follows that the axial stress σ at any point is given by EKy, where E is the modulus of elasticity andKis the curvature of the beam or shaft. Thus, the axial stress σ is also proportional to the distance from the neutral axis y. Therefore, when high stiffness members are further from the neutral axis, the bending stress and hence bending stiffness is higher.
• It follows that when the pullwires108 (and any axially stiff compressive members that provide the reaction force) are located closer to the neutral axis, the bending stiffness of theproximal shaft section120 is decreased. That is, as shown inFIG. 11, there is only one stiff member (i.e., the stiffening tube130) that supports the axial load of thepullwires108, and therefore, the neutral axis (represented by the asterisk) of theproximal shaft section120 will be close to the location of the stiffeningtube130. Ultimately, the exact location of the neutral axis will depend on the relative stiffness of the stiffeningtube130 relative to the remainder of the material in theproximal shaft section120. Therefore, each of thepullwires108 will be relatively close to the neutral axis. Notably, the workinglumen104 is offset from the geometric center of theproximal shaft section120 in order to accommodate thestiffening tube130. In contrast, as shown inFIG. 12, a conventional symmetrical arrangement may distribute four stiffeningmembers130aabout the geometric center of theproximal shaft section130a, and therefore, the neutral axis of theproximal shaft section130awill essentially be at its geometric center. As a result, thepullwires108awill be relatively far from this neutral axis. Thus, it can be appreciated from a comparison betweenFIGS. 11 and 12 that the maximum distance from any of thepullwires108 to the neutral axis in the preferred embodiment is far shorter than thepullwires108ato the neutral axis in the conventional design.
• Therefore, by having thepullwires108 close to or on the neutral axis, thepullwires108 will have a minimum change in length during an externally applied shaft curvature. This achieves consistent articulation of the distal articulatingsection114 independent of the curvature of theproximal shaft section120. In other words, theproximal shaft section120 does not need to be maintained substantially straight in contrast to the conventional pullwire arrangement, which requires the operator to maintain the proximal shaft section relatively straight. Thus, locating thepullwires108 close to the neutral axis of theproximal shaft section120 allows the operator to traverse anatomical features, such as the iliac bifurcation or the aortic arch—not just with the flexible distal articulatingsection108, but with theentire catheter100 as required, while at the same time having full control of the distal tip of thecatheter100.
• Furthermore, because theproximal shaft section120 is relatively axially stiff, articulation of the distal articulatingsection114 by tensioning one or more of thepullwires108 will not cause significant lateral deflection of theproximal shaft section120, thereby improving instrument stability. Furthermore, because thepullwires108 are close to the neutral axis in theproximal shaft section120, there is only a small radial distance between thepullwires108 and the neutral axis. This radial distance is what causes the bending moment that leads to articulation of the distal articulating section114 (or any other articulating section). With small bending moments generated by tensioning thepullwires108, there will be minimal articulation of theproximal shaft section120. Therefore, varying the position of the neutral axis with respect to the position of thepullwires108 in any section of thecatheter100 can influence how much the distal articulatingsection114 will bend when a given load is applied to apullwire108. For example, thedistal articulation section114 has the neutral axis in the geometric center and when any tension is applied to one or more pullwires108, a moment will be generated and thedistal tip112 will articulate. On the other hand, theproximal shaft section120 will not tend to bend and hence twist during tensioning of thosesame pullwires108 of the distal articulatingsection114 because of the smaller moment arm, thereby minimizing the tendency for thecatheter100 to curve align. Notably, even if atensioned pullwire108 initially causes curve alignment by moving to the inside of the curvedproximal shaft section120, thecatheter100 will be stable thereafter, since all thepullwires108 are located on one arcuate side of thecatheter body102. That is, once the stiffeningtube130, and thus thepullwires108, move to the inside of the curvedproximal shaft section120, any of thepullwires108 can be tensioned without causing further rotation of the curvedproximal shaft section120, thereby allowing the distal articulatingsection114 to be articulated in the desired direction. Furthermore, because only onestiffening tube130 is utilized, as opposed to four separate stiffening tubes or coil pipes, for the respective fourpullwires108, there is a significant reduction in cost and a consistent low bending stiffness irrespective of the articulation loads applied to thepullwires108.
• Having described the construction of thecatheter100, one method of manufacturing thecatheter100 will now be described. In this method, the distal articulatingsection114 andproximal shaft section120 are fabricated separately, and then mounted to each other when thetransition section136 is fabricated. Thedistal tip112 can then be formed onto the assembly to complete thecatheter300.
• The distal articulatingsection114 can be fabricated by first inserting a copper wire process mandrel through a lumen of an inner polymer tube (e.g., a PTFE extrusion) having the intended length of the distal articulatingsection114. Then, using a braiding machine (embodiments of which will be described in further detail below), a first layer of braiding is laid down over the length of the inner polymer tube. Next, four PTFE-coated stainless steel wire process mandrels are respectively disposed over the length of the braided inner polymer tube in four equally spaced circumferential positions (i.e., clocked ninety degrees from each other), and a second layer of braiding is laid down over the four wire process mandrels. Next, outer polymer tubes having different durometers and lengths corresponding to the lengths of the different portions of the distal articulating section114 (e.g., a Pebax® 55D extrusion for therigid section120 and a Pebax® 35D extrusion for the articulatable section122) are slid over the fully braided inner polymer tube, and then heat shrink tubing is slid over the outer polymer tubes. The assembly is then heated to a temperature above the melting temperature of the outer polymer tubes, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tubes are laminated to the assembly. In particular, the outer polymer tubes melt and flow, while the heat shrink tubing shrinks and compresses the melted polymer tubes into the braid and around the four stainless steel process mandrels. The assembly then cools and solidifies to integrate the inner polymer tube, braid, and outer polymer tubes together. Then, the center copper wire can be pulled from the assembly to create the workinglumen104, and the four stainless steel wires can be pulled from the assembly to respectively create the fourpullwire lumens110.
• In a similar manner, theproximal shaft section120 can be fabricated by first inserting a copper wire process mandrel and thestiffening tube130 through respective offset lumens of an inner polymer tube (e.g., a PTFE extrusion) having the intended length of theproximal shaft section120. Then, using a conventional braiding machine, two layers of braiding are laid down over the length of the inner polymer tube. Next, outer polymer tubes having different durometers and lengths corresponding to the lengths of the different portions of the first proximal shaft section120 (e.g., a Pebax® 55D extrusion for theproximal portion130, a Pebax® 72D extrusion for the secondproximal portion132, and a Nylon-12 extrusion for the third proximal portion134) are slid over the fully braided inner polymer tube, and then heat shrink tubing is slid over the outer polymer tubes. The assembly is then heated to a temperature above the melting temperature of the outer polymer tubes, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tubes are laminated to the assembly. In particular, the outer polymer tubes melt and flow, while the heat shrink tubing shrinks and compresses the melted polymer tubes into the braid and around the four stainless steel process mandrels. The assembly then cools and solidifies to integrate the inner polymer tube, braid, stiffeningtube130, and outer polymer tubes together. Then, the center copper wire can be pulled from the assembly to create the workinglumen104.
• Next, the distal articulatingsection114 andproximal shaft section120 are coupled to each other by fabricating thetransition section136 between the distal articulatingsection114 andproximal shaft section120. In particular, a center wire process mandrel is inserted through the workinglumen154 of theadapter138 and four wire process mandrels are inserted through thesingle port152, fourchannels146, and fourlumens150 of theadapter138. The proximal end of the center wire process mandrel is then inserted through the workinglumen104 in theproximal shaft section120, and the distal end of the center wire process mandrel is then inserted through the workinglumen104 in the distal articulatingsection114. The proximal ends of the four wire process mandrels are inserted through the stiffeningtube130 in theproximal shaft section120, and the distal ends of the four wire process mandrels are inserted through thepullwire lumens110 in the distal articulatingsection114. Theproximal shaft section120 anddistal section116 are then moved towards each other until they abut the opposite ends of theadapter138.
• Next, an outer polymer tube having a durometer and length corresponding to the length of the transition catheter136 (e.g., Pebax® 55D) is slid over theadapter138, and then heat shrink tubing is slid over the outer polymer tube. The assembly is then heated to a temperature above the melting temperature of the outer polymer tube, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tube is laminated to the assembly. In particular, the outer polymer tube melts and flows, while the heat shrink tubing shrinks and compresses the melted polymer tube into the desired cylindrical shape. The assembly then cools and solidifies to integrate the inner polymer tube,adapter138, and outer polymer tube together. Then, the center copper wire can be pulled from the assembly to create the workinglumen104.
• Then, the proximal ends of thepullwires108, which may be pre-fastened (e.g., soldered, welded, brazed, or glued) to thecontrol ring106, are inserted into thepullwire lumens110 at the distal end of thecatheter body102, and advanced through thelumens110 until they exit the proximal end of thecatheter body102. Thecontrol ring106 is then slid over the distal end of the central wire process mandrel extending from the distal articulatingsection114 until it abuts therigid portion120 of the distal articulatingsection114. Then, outer polymer tubes having different durometers and lengths corresponding to the lengths of the different portions at the distal tip112 (e.g., a Pebax® 55D/35D extrusion for thetip portion122, and a Pebax® 35D extrusion for the control portion124) are slid over the center wire process mandrel andcontrol ring106, and then heat shrink tubing is slid over the outer polymer tubes. The assembly is then heated to a temperature above the melting temperature of the outer polymer tube, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tube melts and flows, while the heat shrink tubing shrinks and compresses the melted polymer tube into the desired cylindrical shape. The assembly then cools and solidifies to integrate the inner polymer tube,adapter138, and outer polymer tube together. Then, thedistal tip122 can be cut to a rounded shape, and the center wire process mandrel can be pulled from thecatheter100. The proximal end of thecatheter tube102 can then be mounted to theproximal adapter100, and the proximal ends of thepullwires108 can be installed on the spools ordrums103 of theproximal adapter101.
• As briefly discussed above, instead of utilizing acontrol ring106, the distal ends of thepullwires108 may be attached directly to a section or portion of thecatheter body102 where it may be steered, articulated, or bent. In particular, the workinglumen104 andpullwire lumens110 are formed and the braid and outer polymer tubes are applied to the inner polymer tube in the same manner described above, with the exception that the distal ends of thepullwires108 are anchored between the braid layers (or alternatively, layers of a different type of wire support structures, such as a coil or mesh), as illustrated inFIGS. 31A-31J. The wire support structure may be made of metal, plastic, fabric, thread, or any other suitable material.
• The distal articulatingsection114 is fabricated by disposing a first layer of braiding over the length of the inner polymer tube (FIG. 31A), four PTFE-coated stainless steel wire process mandrels (only one shown for purposes of clarity) are respectively disposed over the length of the braided inner polymer tube in four equally spaced circumferential positions (i.e., clocked ninety degrees from each other) (FIG. 31B), and a second layer of braiding is laid down over the four wire process mandrels the length of the inner polymer tube (FIG. 31C).
• Next, the outer polymer tubes are slid over the fully braided inner polymer tube in the same manner as discussed above, with the exception that a barrier is disposed over a region of the braided inner polymer tube to which thepullwires108 will eventually be anchored (FIG. 31D). In the illustrated embodiment, the barrier is a cylindrical, and in particular, takes the form of a short section of heat shrink tubing that is disposed over a corresponding short cylindrical region of the braided inner polymer tube. Additional heat shrinking (not shown) is then disposed over the outer polymer tubes and barrier, and the assembly is then heated to a temperature above the melting temperature of the outer tube tubes, but below the melting temperature of the heat shrink tubing and barrier.
• As a result, the outer polymer tubes are laminated to the assembly. In particular, the outer polymer tubes melt and flow, while the heat shrink tubing shrinks and compresses the melted polymer tubes into the braid and around the four stainless steel process mandrels. Because the barrier has a melting temperature above the temperature of the applied heat, the barrier does not melt and prevents the melted outer polymer tubes from being compressed into the circumferential region of the braid. The assembly then cools and solidifies to integrate the inner polymer tube, braid, and outer polymer tubes together. The barrier is then removed from thecatheter body102, thereby exposing the circumferential region of the braid (FIG. 31E). The center copper wire (not shown) can then be pulled from the assembly to create the workinglumen104, and the four stainless steel wires can be pulled from the assembly to respectively create the fourpullwire lumens110 in the same manner discussed above (FIG. 31F). Theproximal shaft section120 andtransition section136 are then fabricated with the distal articulatingsection114 in the same manner described above.
• Then, the proximal ends of thepullwires108 are inserted into thepullwire lumens110 at the distal end of thecatheter body102, and advanced through thelumens110 until they exit the proximal end of thecatheter body102 and the distal ends of thepullwires108 are disposed within the exposed circumferential region of the braid (FIG. 31G). The distal ends of thepullwires108 are then anchored to the exposed circumferential region of the braid via, e.g., soldering, welding, brazing, or gluing (FIG. 31H). In the case where the distal ends of thepullwires108 are anchored via soldering, 80/20 Au/Sn, which has a melting temperature below the temperature required to damage adjacent components, namely the inner PTFE polymer tube and the stainless steel braid, can be used. Because the distal ends of thepullwires108 are anchored between the two layers of braid by virtue of the disposition of thepullwire lumens110 between the two layers of braid, the distal ends of thepullwires108 are more firmly anchored to the braid, since the bonding material anchored thepullwires108 above and below thepullwires108. In contrast, if thepullwires108 are anchored only to one side of the braid, thepullwires108 would tend to pull away from the braid by either pushing toward the inner polymer tube or being forced outwardly from the inner polymer tube.
• Once the distal ends of thepullwires108 are anchored to the braid, an outer polymer tube (e.g., a Pebax® 35D extrusion) can then be slid over the exposed circumferential region of the braid, and then heat shrink tubing (not shown) is slid over the outer polymer tube (FIG. 31I). The assembly is then heated to a temperature above the melting temperature of the outer polymer tube, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tube melts and flows, while the heat shrink tubing shrinks and compresses the melted polymer tube into the circumferential portion of the braid. The assembly then cools and solidifies. The proximal end of thecatheter tube102 can then be mounted to theproximal adapter100, and the proximal ends of thepullwires108 can be installed on the spools ordrums103 of theproximal adapter101.
• It should be appreciated the technique of directly anchoring the distal ends of the wires to the braid eliminates the need for the control ring, thereby reducing the cost and fabrication process time for thecatheter100. Furthermore, the resulting catheter has a less abrupt stiffness characteristic. Although, the technique of directly anchoring the distal ends of wires to the braid has been disclosed in the context of pullwires, it should be appreciated that this technique can be performed in the context of other types of wires. For example, the wires can be electrical signal wires and/or radio frequency (RF) ablation wires in an electrophysiology catheter. In this case, an electrode, rather than an outer polymer tube, can be disposed over the exposed portion of the braid in electrical communication with the wire or wires. The electrode can be used as a conductive surface that either measures a localized electrical potential or delivers RF ablation energy. In the case where the distal end of the wire or wires are soldered to the braid, the electrode can, e.g., be formed by flowing solder into and over the exposed portion of the braid during the same procedure used to solder the distal end of the wire or wires to the braid.
• With reference now toFIG. 13, an embodiment of another flexible and steerableelongate catheter200 will be described. Thecatheter200 is similar to the previously describedcatheter100, with the exception that thecatheter200 is designed with three, instead of four pullwires. Thecatheter200 may be used in therobotic catheter assembly18 illustrated inFIGS. 5 and 6.
• Thecatheter200 generally includes anelongate catheter body202, a workinglumen204 disposed through the entire length of thecatheter body202 for delivering one or more instruments or tools from the proximal end of thecatheter body202 to the distal end of thecatheter body202, acontrol ring206 secured the distal end of thecatheter body202, a plurality ofpullwires208 housed within one ormore lumens210 extending through thecatheter body202, and a proximal adapter201 (with associated spools or drums203 to which the proximal ends of thepullwires208 are coupled). The workinglumen204,control ring206,pullwires208, andpullwire lumens210 may be constructed and function in a similar manner as the workinglumen104,control ring106,pullwires108, andpullwire lumens110 described above.
• Like thecatheter100, thecatheter200 is functionally divided into four sections: adistal tip212, a distal articulatingsection214, atransition section216, and aproximal shaft section220.
• Thedistal tip212, distal articulatingsection214,proximal shaft section220, and proximal adapter201 may be respectively identical to thedistal tip112, distal articulatingsection114,proximal shaft section120, andproximal adapter103 of thecatheter100, with the exception that threepullwires208, instead of three, are accommodated. Thus, threepullwire lumens210, and thus threepullwires208, are equally spaced in an arcuate manner (i.e., one hundred twenty degrees apart) within the distal articulatingsection214, and thestiffening tube230 within theproximal shaft section220 houses the threepullwires208. The proximal adapter201 includes three spools or drums203 to which the proximal ends of thepullwires208 terminate.
• Like thetransition section116, thetransition section216 transitions the equal spacing of thelumens210 in the distal articulatingsection214 to asingle stiffening tube230 within theproximal shaft section214. With further reference toFIGS. 14-16, the illustrated embodiment accomplishes this by using anadapter238, which may be mounted within the outer polymer tube of thetransition body section220. Theadapter238 is similar to theadapter138 of thecatheter100, with the exception that it is designed to transition three, instead of four,pullwires208.
• In particular, theadapter238 includes anadapter body240 having aproximal end242 that interfaces with the stiffeningtube230 in theproximal shaft section220, and adistal end244 that interfaces with the threepullwire lumens210 in the distal articulatingsection214. Theadapter body240 may be composed of a suitable rigid material, such as stainless steel. Theadapter238 further includes a plurality ofchannels246 formed in the external surface of theadapter body240, and asingle channel248 formed in the external surface of theadapter body240 in communication with the plurality ofchannels246. The distal ends of thechannels246 are equally spaced from each other in coincidence with the equally spacedlumens210 in the distal articulatingsection214, and the proximal end of thesingle channel248 is in coincidence with the stiffeningtube230 in theproximal shaft section220. One of thechannels246 linearly extends along the length of theadapter body140, while the remaining twochannels246 spirals around the length of theadapter body240, so that the proximal ends of all threechannels246 converge into thesingle channel248. Thus, the threepullwires208 extend proximally from the distal articulatingsection214, along the threechannels246, converge into thesingle channel248, and then into the stiffeningtube230.
• Theadapter238 further includes a workinglumen254 extending entirely through theadapter body240. The distal end of the workinglumen254 is in coincidence with the portion of the workinglumen204 extending through the distal articulatingsection214, and the proximal end of the workinglumen254 is in coincident with the portion of the workinglumen204 extending through theproximal shaft section220. In the same manner that the workinglumen204 and stiffeningtube230 are offset from the axis of theproximal shaft section120, the workinglumen254 andsingle channel248 are offset from the axis of theadapter body240. Like with theadapter138 of thecatheter100, theadapter238 allows the threepullwires208 to be transitioned from therespective lumens210 of the distal articulatingsection214 into thesingle stiffening tube230 of theproximal shaft section220 without having to spiral thepullwires208 and corresponding lumens through the wall of thecatheter tube202, thereby allowing the thickness of the wall to be uniform and minimizing the possibility of weakened regions in thecatheter tube202 and possible inadvertent kinking.
• With reference now toFIG. 17, an embodiment of another flexible and steerableelongate catheter300 will be described. Thecatheter300 is similar to the previously describedcatheter100, with the exception that thecatheter300 is designed as a rapid exchange catheter, which is facilitated by the placement of the pullwires on one arcuate side of the proximal shaft section, and in particular, within the stiffening tube. Thecatheter300 may be used in arobotic catheter assembly358, which is similar to therobotic catheter assembly18 illustrated inFIGS. 5 and 6, with the exception that therobotic catheter assembly358 includes aguidewire manipulator360 that is in a side-by-side arrangement with aleader catheter manipulator362, as shown inFIG. 18, which is facilitated by the rapid exchange architecture of thecatheter300.
• The design of thecatheter300 applies to a leader catheter of a telescoping catheter pair; e.g., aleader catheter300 andouter guide sheath36. With a pair of telescoping catheters, the therapy will usually be delivered through the outer catheter after the inner catheter has been removed. Therefore, the inner catheter does not need to have a lumen extending through its center the entire length of its shaft. The purpose of the outer catheter is to facilitate access to the site of interest and then to provide a stable, controllable (steerable) lumen to deliver a therapeutic device. Therefore, the outer catheter needs to have a lumen through the center the entire length of its shaft. The purpose of the inner catheter is to work in conjunction with the outer catheter and guide wire in a telescoping motion to inchworm the catheter system through the anatomy. This can be achieved by just having a short section at the distal end of the leader catheter supporting the guide wire, and allowing the remainder of the wire to run parallel to the leader catheter.
• Thecatheter300 generally includes anelongate catheter body302, a workinglumen304 disposed through the entire length of thecatheter body302 for delivering one or more instruments or tools from the proximal end of thecatheter body302 to the distal end of thecatheter body302, acontrol ring306 secured the distal end of thecatheter body302, a plurality ofpullwires308 housed within one ormore lumens310 extending through thecatheter body302, and a proximal adapter301 (with associated spools ordrums302 to which the proximal ends of thepullwires308 are coupled). The workinglumen304,control ring306,pullwires308, andpullwire lumens310, andproximal adapter301 may be constructed and function in a similar manner as the workinglumen104,control ring106,pullwires108,pullwire lumens110, andproximal adapter101 described above.
• Like thecatheter100, thecatheter300 is functionally divided into four sections: adistal tip312, a distal articulatingsection314, aproximal shaft section320, and a transition section318. Thedistal tip312 and distal articulatingsection314 of thecatheter300 may be identical to thedistal tip112 and distal articulatingsection114 of thecatheter100. The transition section318 of thecatheter300 is identical to the transition section118 of thecatheter100 with the exception that the transition section318 includes arapid exchange port322 that is in communication with aguidewire lumen304. The exact location of therapid exchange port322 relative to the distal tip of thecatheter300 can vary by varying the length of the distal articulatingsection314 and transition section318. Ultimately, the location of therapid exchange port322 will depend on the required distance that thecatheter300 needs to extend beyond the distal tip of theouter guide sheath36. However, therapid exchange port322 should never exit the distal tip of theouter guide sheath36—else it would be difficult to retract the distal end of thecatheter300 back into theouter guide sheath36. Thus, the length of the over-the-wire segment of the catheter300 (i.e., the total length of thedistal tip312, distal articulatingsection314, and transition section318) should always be greater than the maximum extension of thecatheter300 from theouter guide sheath36. A shorter the over-the-wire segment length, however, will be easier and faster to use, because the robot may control more of the insertion and withdrawal of thecatheter300.
• The proximal end of transition section318 is tapered to provide a smoothrapid exchange port322. This allows theguide wire40 to be front-loaded through the proximal end of theouter guide sheath36 and then exit out through the exit port (not shown) at thedistal tip312 of thecatheter300. Theproximal shaft section320 of thecatheter300 is composed of astiffening tube330, which is in communication with thepullwire lumens310 via the transition section316 (e.g., via use of theadapter138 illustrated inFIGS. 8 and 9).
• Thus, when thecatheter300 is used with theouter guide sheath36, theguide wire40 will travel outside thecatheter300 within theouter guide sheath36, until it enters therapid exchange port322, and then through theguide wire lumen304, and then out through the guide wire exit port. Thus, thecatheter300 and theguide wire40 will travel parallel to each other through theouter guide sheath36 until theguide wire40 enters therapid exchange port322, after which they travel concentrically relative to each other. In addition, contrast agents can also be injected through a flush port (not shown) at the proximal end of theouter guide sheath36, which may enter therapid exchange port322, and exit out the guide wire exit port.
• The design of the rapidexchange leader catheter300 allows for significantly greater robotic control of position. In particular, because thecatheter300 and guidewire40 are not concentrically arranged relative to each other, but instead are two independent devices, at the proximal end of the assembly, greater independent robotic control is enabled without the need for an excessively long instrument driver. That is, the guidewire manipulator260 can now be placed in a side-by-side arrangement with the leader catheter manipulator262. The instrument driver has separate drive trains for thecatheter300 and guidewire40, allowing the user to have full independent insertion and withdrawal control of both thecatheter300 and theguide wire40 at all times. This results in less fluoroscopic time and radiation exposure, faster procedure time, greater length of robotic insertion and retraction of thecatheter300 and guidewire40, less risk of losing guide wire position, less risk of breaching the sterile field, and allows for use of shorter guide wires and therefore one less person in the sterile field.
• It should be appreciated that this rapid exchange design is applicable to other non-steerable catheters (e.g., atherectomy devices or graspers) that require the routing of wires from the proximal end to an operative element at the distal end of the catheter. The method of manufacturing thecatheter100 may be similar to the method of manufacturing thecatheter300 described above, with the exception that the proximal end of the transition section318 is tapered, and thestiffening tube330 forms the entirety of the catheterproximal shaft section320 and is suitably bonded within the proximal end of the transition section318.
• One method of using therobotic catheter assembly358 illustrated inFIG. 18 to access a diseased site within the vasculature of a patient will now be described. First, an incision in a blood vessel of the patient (e.g., a femoral artery) is made using a conventional techniques, and a starter wire is advanced into the artery. Next, theleader catheter300 is preloaded into theouter guide sheath36, ensuring that therapid exchange port322 remains inside theouter guide sheath36. Then, theguide wire40 is backloaded into the tip of theleader catheter300. When theguide wire40 exists therapid exchange port322, theguide wire40 is advanced through theouter guide sheath36 next to theleader catheter300 until it exits at the back of theproximal adapter48 of theouter guide sheath36. Next, theguide wire40 is held in a fixed position, while theleader catheter300 is advanced several centimeters into the femoral artery over theguide wire40. Then, theproximal adapter301 of theleader catheter300 and guidewire40 are loaded onto therobotic instrument driver34.
• Then, theguide wire40 andleader catheter300 can be robotically driven remotely to the site of interest using theoperator control station16. If a selective angiogram is required when driving theguide wire40 andleader catheter300, a contrast agent may be injected through an injection port on theouter guide sheath36. If theguide wire40 is 0.035″ in diameter and occupies most of the available space through the leader catheter, almost all of the contrast agent will exit the distal tip of theouter guide sheath36. In contrast, ifguide wire40 is 0.018″ in diameter, some of the contrast agent will exit out the distal tip of theleader catheter300, and some of the contrast agent will exit out the distal tip of theouter guide sheath36. Either way, the physician will be capable of obtaining a selective angiogram for the vessel of interest.
• Once theguide wire40 is at the site of interest, the physician may then robotically withdraw theleader catheter300 until the “over-the-wire” section exits at the back of theproximal adapter48 of theouter guide sheath36. This can be accomplished without the use of fluoroscopy, since therobotic catheter system358 will ensure that the position of theguide wire40 relative to the patient is maintained. Depending on the robotic configuration used (i.e., the travel distance of the leader catheter carriage), thisleader catheter300 removal step may be accomplished entirely remotely or part manually and part robotically.
• The physician may then manually remove theguide wire40 from theguide wire manipulator360, slide out the last few inches of theleader catheter300 under fluoroscopy, and removeleader catheter300 from the patient. A therapeutic device may then be manually delivered through theouter guide sheath36. If the therapeutic device is itself a rapid exchange catheter, after the “over-the-wire” section has been manually passed into theouter guide sheath36, theguide wire40 may then be positioned back onto theguide wire manipulator30, and the robot can be used to hold the position of theguide wire40 while the therapeutic device is manually advanced. If theleader catheter300 needs to be reinstalled to access another site of interest within the patient, it may be backloaded over theguide wire40 until theguide wire40 exits therapid exchange port322. Theguide wire40 may then be loaded onto theguide wire manipulator360 and theleader catheter300 is reinstalled on theinstrument driver34. Theguide wire40 andleader catheter300 can then be robotically driven remotely to the new site of interest using theoperator control station16.
• With reference now toFIG. 19, an embodiment of yet another flexible and steerableelongate catheter400 will be described. Thecatheter400 is similar to the previously describedcatheter100, with the exception that thecatheter400 has multiple regions of articulation, and in particular, a distal region of articulation and a proximal region of articulation. Thecatheter400 enables two regions of articulation by altering the axial stiffness, flexural stiffness, and torsional stiffness of the catheter body in very specific locations. Thecatheter400 may be used in therobotic catheter assembly18 illustrated inFIGS. 5 and 6.
• Thecatheter400 generally includes anelongate catheter body402, which like thecatheter body102, may be comprised of multiple layers of materials and/or multiple tube structures that exhibit a low bending stiffness, while providing a high axial stiffness along the neutral axis. Also like thecatheter100, thecatheter400 further includes a workinglumen404 disposed through the entire length of thecatheter body402 for delivering one or more instruments or tools from the proximal end of thecatheter body402 to the distal end of thecatheter body402, acontrol ring406 secured the distal end of thecatheter body402, a plurality ofpullwires408 housed within one ormore lumens410 extending through thecatheter body402, and a proximal adapter401 (with associated spools ordrums403 to which the proximal ends of thepullwires408 are coupled). The workinglumen404,control ring406,pullwires408,pullwire lumens410, andproximal adapter401 may be constructed and function in a similar manner as the workinglumen104,control ring106,pullwires108,pullwire lumens110, andproximal adapter101 described above.
• Thecatheter400 is functionally divided into five sections: adistal tip412, a distal articulatingsection414, atransition section416, a proximal articulatingsection418, and aproximal shaft section420.
• Thedistal tip412 includes an atraumaticrounded tip portion422, acontrol portion424 in which thecontrol ring406 is mounted, and an exit port (not shown) in communication with the workinglumen404 and from which a working catheter or guidewire may extend distally therefrom. Thedistal tip412 may be constructed and function in a similar manner as thedistal tip112 described above.
• Like the distal articulatingsection114, fourpullwire lumens410 are equally spaced in an arcuate manner (i.e., ninety degrees apart) within the distal articulatingsection414 to allow the distal articulatingsection414 to be articulated in an infinite number of directions within the same plane (effectively, providing two degrees of freedom: pitch and roll). In an alternative embodiment, another number ofpullwires lumens410, and thus, pullwires408, can be used. For example, threepullwire lumens410 can be equally spaced in an arcuate manner (i.e., one hundred twenty degrees apart). The distal articulatingsection414 preferably allows for a moderate degree of axial compression and optimal lateral flexibility. The distal articulatingsection414 includes arigid portion426 and anarticulatable portion428. The distal articulatingsection414 may be constructed and function in a similar manner as the distal articulatingsection114 described above, with thepullwire lumens410 extending through therigid portion426 andarticulatable portion428 as unsupported cavities in which the fourpullwires408 are respectively disposed.
• Thetransition section416 transitions the equal spacing of thelumens410 in the distal articulatingsection414 too close spacing of thelumens410 in the proximal articulatingsection418. Instead of using anadapter138, as illustrated inFIGS. 8 and 9, thelumens410 in thetransition section416 are gradually displaced about the axis of thecatheter body402 within the wall of thetransition section416. In particular, the onelumen410 that is on the same side as the closely spacedlumens410 in the proximal articulatingsection418 may extend linearly along the length of thetransition section416, while the remaining three lumens spiral around the length of thetransition section416 until they converge onto the same side of the proximal articulatingsection418. Thetransition section416 is more rigid than the distal articulatingsection414 to allow the distal articulatingsection414 to bend about thetransition section416.
• Thetransition section416 resists axial compression to clearly define the proximal end of the distal articulatingsection414 and transfer the motion of thepullwires408 to the distal articulatingsection414, while maintaining lateral flexibility to allow thecatheter400 to track over tortuous anatomies. In one embodiment, thetransition section416 is 33 mm in length. Thepullwire lumens410 extending through thetransition section416 take the form of 0.007″×0.009″ polyimide tubes circumferentially oriented relative to each other by ninety degrees, and thus, can be considered stiffening members in which thepullwires408 are respectively disposed. Theentire working lumen404 within thetransition section416 is formed by an inner polymer tube (e.g., 0.001″ thick PTFE). Thetransition section416 has a several portions of differing rigidities formed by having different polymer outer tubes. In one embodiment, thetransition section416 includes a 1 mm pullwirelumen anchoring portion430 having a relatively rigid outer polymer tube (e.g., Nylon-12) that increases the support for holding the distal ends of thepolyimide pullwire lumens410. Thetransition section416 further includes a 4 mmflexible portion432 having a relatively flexible outer polymer tube (e.g., Pebax® 40D) that transitions from the relatively flexibledistal section314 to a 28 mmstiff portion434 having a relatively stiff outer polymer tube (e.g., Pebax® 55D).
• To increase its axial rigidity, thetransition section416 comprises a double braided layer (e.g., sixteen 0.0005″×0.003″ spring temper 304V stainless steel wires braided at 140 ppi in a 2 over 2 pattern) embedded within the outer polymer tubes of all three of the anchoringportion430,flexible portion432, andrigid portion434. Three of thepolyimide pullwire lumens410 spiral around thestiff portion434 of thetransition section416, which along with the remainingpolyimide pullwire lumen410, converge to the same side of thecatheter body402.
• The proximal articulatingsection418 significantly allows for a moderate degree of axial compression and optimal lateral flexibility. Thepullwire lumens410 are grouped on one arcuate side of the proximal articulatingsection418 to allow it to be articulated in one direction. Preferably, thepullwire lumens410 are grouped in a manner that locates their centers within an arcuate angle relative to the geometric cross-sectional center of the proximal shaft section of less than one hundred eighty degrees, and more preferably, less than ninety degrees, and most preferably, less than forty-five degrees.
• In one embodiment, the proximal articulatingsection418 is 16 mm in length. Preferably, the proximal articulatingsection418 is more rigid than the distal articulatingsection414, such that independent control of the distal articulatingsection414 and the proximal articulatingsection418 can be achieved, as discussed in further detail below. Like in thetransition section416, thepullwire lumens410 extending through the proximal articulatingsection418 take the form of 0.007″×0.009″ polyimide tubes, and thus, can be considered stiffening members in which thepullwires408 are respectively disposed. Theentire working lumen404 within the proximal articulatingsection418 comprises an inner polymer tube (e.g., 0.001″ thick PTFE). The proximal articulatingsection418 has two portions of differing rigidities formed by having different polymer outer tubes. In one embodiment, the proximal articulatingsection418 includes a 15mm articulatable portion436 having a relatively flexible outer polymer tube (e.g., Pebax® 40D) and a 1 mm pullwirelumen anchoring portion438 having a relatively rigid polymer tube (e.g., Nylon) that increases the support for holding thepolyimide pullwire lumens410. To increase its axial rigidity and elastic properties, the proximal articulatingsection418 comprises a double braided layer (e.g., sixteen 0.0005″×0.003″ spring temper 304V stainless steel wires braided at 140 ppi in a 2 over 2 pattern) embedded within the outer polymer tubes.
• Theproximal shaft section420 resists axial compression to clearly define the proximal end of the proximal articulatingsection418 and transfer the motion of thepullwires408 to the proximal articulatingsection314, while maintaining lateral flexibility to allow thecatheter400 to track over tortuous anatomies. Like with the proximal articulatingsection314, thepullwire lumens410 are grouped on one arcuate side of theproximal shaft section420. Because thepullwire lumens410 are more rigid than the remaining material of the proximal articulating section418 (i.e., thepullwire lumens410 are composed of a polyimide, whereas the remaining portion of the proximal articulatingsection418 is composed of a low durometer polymer composite), the neutral axis will be shifted closer to the axis of the grouping ofpullwire lumens410, thereby providing the aforementioned advantages discussed above with respect to thecatheter100.
• Theproximal shaft section420 represents the majority of the length of thecatheter400, and gradually transitions thecatheter400 from the more flexibleproximal articulating section418 to the more rigid remaining portion of thecatheter400. For example, theproximal shaft section420 may include threeproximal portions440,442,444 that increase in rigidity in the proximal direction. Theproximal shaft section420 may be constructed and function in a similar manner as theproximal shaft section120 described above.
• Having described its function and construction, one method of manufacturing thecatheter400 will now be described. Like the method of manufacturing thecatheter100, in this method, the distal articulatingsection414 and the combined proximal articulatingsection418/proximal shaft section420 are fabricated separately, and then mounted to each other when thetransition section416 is fabricated. Thedistal tip412 can then be formed onto the assembly to complete thecatheter400.
• The distal articulatingsection414 can be fabricated in the same manner as the distal articulatingsection114 described above. The proximal articulatingsection418 andproximal shaft section420 are fabricated together by first inserting a copper wire process mandrel through a lumen of an inner polymer tube (e.g., a PTFE extrusion) having the intended length of the combined proximal articulatingsection418/proximal shaft section420. Then, using a conventional braiding machine, a first layer of braiding is laid down over the length of the inner polymer tube. Next, four PTFE-coated stainless steel wire process mandrels with polyimide tubing are respectively disposed over the length of the braided inner polymer tube in a group on one side of the inner polymer tube, and a second layer of braiding is laid down over the four wire process mandrels the length of the inner polymer tube. Next, outer polymer tubes having different durometers and lengths corresponding to the lengths of the different portions of the proximal articulatingsection418 and the proximal shaft section420 (e.g., a Pebax® 40D extrusion for thearticulatable portion436 and a Nylon-12 extrusion for the anchoringportion438 of the proximal articulatingsection418, and Pebax® 55D, Pebax® 72D, and Nylon-12 extrusions for the respectiveproximal portions440,442,444 of the proximal shaft section420) are slid over the fully braided inner polymer tube, and then heat shrink tubing is slid over the outer polymer tubes.
• The assembly is then heated to a temperature above the melting temperature of the outer polymer tubes, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tubes melt and flows, while the heat shrink tubing shrinks and compresses the melted outer polymer tubes into the braid and around the four stainless steel process mandrels. The assembly then cools and solidifies to integrate the inner polymer tube, braid, and outer polymer tubes together. Then, the center copper wire can be pulled from the assembly to create the workinglumen404, and the four stainless steel wires can be pulled from the assembly, thereby leaving the polyimide tubing with the assembly to respectively create the fourpullwire lumens410.
• Next, the distal articulatingsection414 and the combined proximal articulatingsection418/proximal shaft section420 are coupled to each other by fabricating thetransition section416 between the distal articulatingsection414 and the combined proximal articulatingsection418/proximal shaft section420. In particular, thetransition section416 is partially fabricated by first inserting a PTFE-coated copper wire process mandrel through a lumen of an inner polymer tube (e.g., a PTFE extrusion) having the intended length of thetransition section416. Then, using a conventional braiding machine, a first layer of braiding is laid down over the length of the inner polymer tube. Then, each of four PTFE-coated stainless steel wire process mandrels is inserted through a lumen of a polyimide tube having the intended length of thetransition section416. The linear length of one of these wire process mandrels will equal the length of thetransition section416, while the linear lengths of the remaining three wire process mandrels will be slightly greater than the length of thetransition section416 to compensate for the additional length required to spiral these wire process mandrels around thetransition section416.
• Next, the opposing ends of the center wire process mandrel are respectively inserted through the workinglumens404 of the distal articulatingsection414 and the combined proximal articulatingsection418/proximal shaft section420, and the opposing ends of four wire process mandrels are inserted through thepullwire lumens410 of the distal articulatingsection414 and thepullwire lumens410 of the combined proximal articulatingsection418/proximal shaft section420. The distal articulatingsection414 and the combined proximal articulatingsection418/proximal shaft section420 are then slid together until the inner polymer tube of thetransition section416 abuts the inner polymer tubes of the distal articulatingsection414 and the proximal articulatingsection418, and the polyimide tubing on the four wire process mandrels abuts thepullwire lumens410 of the distal articulatingsection414 and thepullwire lumens410 of the proximal articulatingsection418. Three of the wire process mandrels are then spiraled around and bonded to the inner polymer tube, and a second layer of braiding is laid down over the four wire process mandrels the length of the inner polymer tube.
• Next, outer polymer tubes having different durometers and lengths corresponding to the lengths of the different portions of the transition section416 (e.g., a Nylon-12 extrusion for the anchoringportion430, a Pebax® 40D extrusion for theflexible portion432, and a Pebax® 55D extrusion for the rigid portion434) are slid over the fully braided inner polymer tube, and then heat shrink tubing is slid over the outer polymer tubes. The assembly is then heated to a temperature above the melting temperature of the outer polymer tubes, but below the melting temperature of the heat shrink tubing. As a result, the outer polymer tubes melt and flows, while the heat shrink tubing shrinks and compresses the melted outer polymer tubes into the braid and around the four stainless steel process mandrels. The assembly then cools and solidifies to integrate the inner polymer tube, braid, and outer polymer tubes together. Then, the center copper wire can be pulled from the assembly to create the workinglumen404 within thetransition section416, and the four stainless steel wires can be pulled from the assembly, thereby leaving the polyimide tubing within the assembly to respectively create the fourpullwire lumens410 within thetransition section416.
• Thecontrol ring406,pullwires408, anddistal tip412 may be installed on the assembly in the same manner as thecontrol ring106,pullwires108, anddistal tip112 described above. Alternatively, in a similar manner discussed above, instead of utilizing acontrol ring106, the distal ends of thepullwires108 may be attached directly to a section or portion of thecatheter body102 where it may be steered, articulated, or bent, and in this case, to the distal end of the distal articulatingsection414.
• Significantly, thecatheter400 may be operated in a manner that independently controls the articulation of the distal articulatingsection414 and proximal articulatingsection418. The theory behind the design of thecatheter400 is that if only onepullwire408 is tensioned, only the distal articulatingsection414 will bend. If all fourpullwires408 are uniformly tensioned (common mode), then only the proximal articulatingsection418 will bend. Any variation in wire tension from these two scenarios will result in the bending of both the distal articulatingsection414 and proximal articulatingsection418 assuming at least two of thepullwires408 are tensioned. Effectively, the distal articulatingsection414 provides thecatheter400 with two degrees of freedom (bend and roll), and the proximal articulatingsection418 provides thecatheter400 with one degree of freedom (bend).
• In particular, when two or less of thepullwires408 are tensioned at relatively small amount, the distal articulatingsection414 articulates in the direction of the tensioned pullwire(s)310. Because the proximal articulatingsection418 is designed to be more laterally rigid than the distal articulatingsection414, the net moment created at thedistal tip412 nominally articulates only the distal articulatingsection414, but is not sufficient to overcome the lateral stiffness of the proximal articulatingsection418 in a manner that would cause a significant bend in the proximal articulatingsection418. This feature therefore facilitates independent articulation of the distal articulatingsection414 relative to the proximal articulatingsection418 even through the pullwires used to articulate the distal articulatingsection414 extend through the proximal articulatingsection418.
• When all four of thepullwires408 are uniformly tensioned, there will be no net moment created at thedistal tip412 due to the equal arcuate distribution of thepullwires408 at thedistal tip412. As such, the distal articulatingsection414 will not articulate. However, because all four of thepullwires408 are grouped together on one side of the proximal articulatingsection418, a net moment is created at the distal end of the proximal articulatingsection418. As such, the proximal articulatingsection418 will articulate in the direction of the groupedpullwires408. This feature therefore facilitates independent articulation of the proximal articulatingsection418 relative to the distal articulatingsection414 even through the pullwires used to articulate the proximal articulatingsection418 extend through the distal articulatingsection414.
• When two or less than thepullwires408 are tensioned a relatively large amount, and the remainingpullwires408 are also tensioned but not as much as the initially tensioned pullwires408 are tensioned, then the net moment is created at thedistal tip412 greatly articulates the distal articulatingsection414 in the direction of the initially tensioned pullwire(s)410, while the combined moment created at the distal end of the proximal articulatingsection418 moderately articulates the proximal articulatingsection418 in the direction of the grouped pullwires408, thereby causing a large bend in the distal articulatingsection414 while causing a small bend in the proximal articulatingsection418.
• When two or less of thepullwires408 are tensioned a relatively small amount, then all of thepullwires408 are uniformly tensioned an additional amount, a net moment is created at thedistal tip412 to moderately articulate the distal articulatingsection414 in the direction of the tensioned pullwire(s)410, while the additional tensioning of all of thepullwires408 greatly articulates the proximal articulatingsection418, thereby causing a small bend in the distal articulatingsection414 while causing a large bend in the proximal articulatingsection418.
• Thecomputer28 within thecontrol station16 may be programmed with algorithms that take into account the elastic behavior of the distal articulatingsection414 and proximal articulatingsection418 and catheter stiffness when computing the displacements of thepullwires408 required to enable complete and independent control of both the distal articulatingsection414 and proximal articulatingsection418.
• By achieving independent articulation control over the distal articulatingsection414 and the proximal articulatingsection418, anatomical sites of interest can be more easily accessed. Thecatheter400 can be used to access either the left coronary artery or the right coronary artery from the aorta of the patient.
• To access the left coronary artery, the pullwire orpullwires408 in the direction of the left coronary artery (in this case, pullwire 1) can be tensioned to bend the distal articulatingsection414 ninety degrees towards the left coronary artery, as illustrated inFIG. 20. Then, all four of thepullwires408 can be tensioned an additional amount to bend the proximal articulatingsection418 to seat thedistal tip412 of thecatheter400 within the ostium of the left coronary artery, as shown inFIG. 21. For example, if thepullwire 1 is initially tensioned at a force of 7 units to bend the distal articulatingsection414, an additional force of 3 units can be used to tension all four pullwires 1-4 (resulting in a 10 unit tension inpullwire 1, and a 3 unit tension in pullwires 2-4). There is now 19 units of force on the proximal articulatingsection418, which is adequate to bend the proximal articulatingsection418. But there remains a delta of 7 units of tension more onpullwire 1 than on all other wires, and therefore there is no further bending of the distal articulatingsection414.
• To access the right coronary artery, the pullwire orpullwires408 in the direction of the right coronary artery (in this case, pullwire 4) can be tensioned to bend the distal articulatingsection414 ninety degrees to seat thedistal tip412 within the ostium of the right coronary artery, as illustrated inFIG. 22. If thedistal tip412 is seated too deeply within the ostium of the right coronary artery, then all four of thepullwires408 can be tensioned an additional amount to bend the proximal articulatingsection418 to properly seat thedistal tip412 within the ostium of the right coronary artery, as shown inFIG. 23. For example, if thepullwire 4 is initially tensioned at a force of 7 units to bend the distal articulatingsection414, an additional force of 1 unit can be used to tension all four pullwires 1-4 (resulting in an 8 unit tension inpullwire 1, and a 1 unit tension in pullwires 2-4) to slightly bend the proximal articulatingsection418.
• As another example, by independently articulating thecatheter400, the left coronary artery of a patient can be accessed regardless of the type of anatomy. In particular,FIG. 24A illustrates independent articulation of the proximal articulatingsection418 and distal articulatingsection414 of thecatheter400 to access the left coronary artery in a “normal” anatomy;FIG. 24B illustrates independent articulation of the proximal articulatingsection314 and distal articulatingsection418 of thecatheter400 to access the left coronary artery in a “wide” anatomy; andFIG. 24C illustrates independent articulation of the proximal articulatingsection418 and distal articulatingsection414 of thecatheter400 to access the left coronary artery in an “unfolded” anatomy.
• Significantly, by taking advantage of the geometric construction and variation in catheter flexibility to achieve independent control over multiple articulation segments, several advantages are achieved using thecatheter400. First, repeatable and consistent articulation performance at two unique locations in thecatheter400 can be achieved. Second, while other dual articulating catheters achieve independent control over multiple articulation segments by employing multiple control rings and having dedicated pullwire or articulation mechanisms, thecatheter400 does not require a second control ring or dedicated control mechanism to effect a second articulation within the catheter, but rather only utilizes the distal-most control ring and the pullwires that are already installed for the distal articulation of the catheter. Thus, by eliminating the need for a second control ring and a separate set of pullwires, few components are needed. Third, the need for a procedure to fasten a second set of wires to a second control ring is eliminated, thereby decreasing the cost of manufacturing the catheter. Fourth, an existing driver instrument initially designed for a catheter having a single region of articulation (e.g., thecatheter100 or catheter400) can be utilized for a catheter having dual regions of articulation (e.g., the catheter400), since no additional pullwires are needed, and thus the proximal adapter of the catheter remains the same. It should also be noted that robotic control of thecatheter400 efficiently and quickly manages the tensioning of the pullwires to effect the articulation of thecatheter400, and therefore, there is no need for the physician to think about which of the pullwires to tension and the magnitude of the tension to be placed on the pullwires.
• With reference now toFIG. 25, an embodiment of yet another flexible and steerableelongate catheter500 will be described. Thecatheter500 is similar to the previously describedcatheter400, with the exception that thecatheter400 has a proximal region of articulation that bi-directionally bends in a plane. Thecatheter500 may be used in therobotic catheter assembly18 illustrated inFIGS. 5 and 6.
• Thecatheter500 generally includes an elongate catheter body502 (which may have any suitable cross-section, such as circular or rectangular), which like thecatheter body502, may be comprised of multiple layers of materials and/or multiple tube structures that exhibit a low bending stiffness, while providing a high axial stiffness along the neutral axis. Also, like thecatheter400, thecatheter500 further includes a workinglumen504 disposed through the entire length of thecatheter body502 for delivering one or more instruments or tools from the proximal end of thecatheter body502 to the distal end of thecatheter body502, acontrol ring506 secured the distal end of thecatheter body502, a plurality ofpullwires508 housed within one ormore lumens410 extending through thecatheter body502, and a proximal adapter501 (with associated spools ordrums503 to which the proximal ends of thepullwires508 are coupled). The workinglumen504,control ring506,pullwires508,pullwire lumens510, andproximal adapter501 may be constructed and function in a similar manner as the workinglumen404,control ring406,pullwires408,pullwire lumens410, andproximal adapter401.
• The workinglumen504,control ring506,pullwires508, andpullwire lumens510 may be constructed and function in a similar manner as the workinglumen404,control ring406,pullwires408, andpullwire lumens410 described above, except that one of thepullwires508 is used to provide proximal bi-directional articulation.
• In particular, as previously stated, tensioning one or more of thepullwires408 in thecatheter400 may cause the proximal articulatingsection418 to bend somewhat. Such proximal bend can be increased by uniformly increasing the tension in thepullwires408, but cannot be decreased. Thus, the proximal articulatingsection418 can only bend in a single direction (i.e., in the direction of the grouped pullwires408).
• In contrast, thecatheter500 utilizes a counteractingpullwire508′ that circumferentially opposes the group ofpullwires508 in the proximal articulating section, such that tensioning the counteractingpullwire508 bends the proximal articulating section in one direction, while uniformly tensioning the three remainingpullwires508 bends the proximal articulating section in an opposite direction. Notably, an existing driver instrument initially designed for a catheter having four pullwires for a single region of articulation (e.g., thecatheters100,200, and300) or a distal region of articulation and a proximal region of uni-directional articulation (e.g., the catheter400) can be utilized for a catheter having a distal region of articulation (using 3 of the pullwires) and a proximal region of bi-directional articulation with the remaining wire (e.g., the catheter500), since no additional pullwires are needed, and thus the proximal adapter of the catheter remains the same.
• Thecatheter500 is functionally divided into five sections: adistal tip512, a distal articulatingsection514, atransition section416, a proximal articulatingsection418, and aproximal shaft section420.
• Thedistal tip512 is identical to thedistal tip412, and the distal articulatingsection514 is identical to the distal articulatingsection414 of thecatheter400, with the exception that three pullwire lumens510 (rather than four), and thus, threepullwires508, are equally spaced in an arcuate manner (i.e., one hundred twenty degrees apart) within the distal articulatingsection514 to allow it to be articulated in an infinite number of directions within the same plane (effectively, providing two degrees of freedom: bend and roll).
• Thetransition section516 is identical to thetransition section416 of thecatheter400, with the exception that the distal end of the counteractingpullwire508′ is anchored within the proximal end of thetransition section516, and the three remainingpullwire lumens510 and associatedpullwires508 are equally spaced in an arcuate manner (i.e., one hundred twenty degrees apart).
• The proximal articulatingsection518 is identical to the proximal articulatingsection418 of thecatheter500, with the exception that the counteractingpullwire508′ is oriented one hundred eighty degrees from the group of the remaining threepullwires508, and the counteractingpullwire lumen510′ in which the counteracting pullwire508′ is disposed takes the form of an unsupported cavity. Theproximal shaft section520 is identical to theproximal shaft section420 of thecatheter400, which has the feature of shifting the neutral axis closer to the axis of the grouping ofpullwire lumens510, thereby providing the aforementioned advantages discussed above with respect to thecatheter100.
• The method of manufacturing thecatheter500 is the same as the method of manufacturing thecatheter500 described above, with the exception that the distal end of the counteractingpullwire508′ is anchored within thepullwire lumen510′ in the proximal end of thetransition section516, and thepullwire lumen510′ is unsupported through thetransition section516 and the proximal articulatingsection518 until it reaches the distal end of theproximal shaft section520, at which point it is composed of a polyimide tube that is grouped with the remaining threepolyimide lumens510. The counteractingpullwire508′ may be anchored in the proximal end of thetransition section516 by using another control ring or anchoring it directly to braid.
• Like with thecatheter500, thecomputer28 within the control station16 (shown inFIG. 4) may be programmed with algorithms that take into account the elastic behavior of the distal articulatingsection514 and proximal articulatingsection518 and catheter stiffness when computing the displacements of thepullwires508 required to enable complete and independent control of both the distal articulatingsection514 and proximal articulatingsection518. To fully utilize the multi-bend architecture of thecatheter500, it is important for the physician to independently control the distal articulatingsection514 and proximal articulatingsection518. However, because the any distal moment created at thedistal tip512 of thecatheter500 will cause bending of the proximal articulatingsection518 as small as it may be, thecomputer28 employs a multi-bend control algorithm that takes into account the inadvertent bending of the proximal articulatingsection518 in order to ensure full independent articulation of the distal articulatingsection514 and the proximal articulatingsection518. Ideally, when only bending of the distal articulatingsection514 is desired, the proximal articulatingsection518 should not bend, and when only bending of the proximal articulatingsection518 is desired, the distal articulatingsection514 should not bend.
• With reference toFIG. 26, a multi-bend segment of thecatheter500 is shown having a distal articulation angle α_dand a proximal articulation angle α_p. The multi-bend segment of the catheter also has a distal articulation roll θ. Thus, thecatheter500 has two articulation Degrees of Freedom (DOFs) in the distal bend and a single articulation DOF in the proximal bend. From a controls perspective, thetransition section516 of thecatheter500 couples the distal articulatingsection514 and the proximal articulatingsection518 in such a way that the coupling can be counteracted by the counteractingpullwire508′. The multi-bend control algorithm employed by thecomputer28 utilizes this configuration to independently control the bends in the distal articulatingsection514 and the proximal articulatingsection518.
• The following relation can be used to calculate the number of independently controllable DOFs (m) in a catheter based on the number of pullwires (n):
• 
  m≦n−1  [1]
• Thus, the fourpullwires508 of thecatheter500 can be used to independently control three DOFs, in particular, the distal articulation angle α_d, proximal articulation angle α_p, and distal articulation roll θ. These DOFs allow the orientation and position of thedistal tip512 of thecatheter500 to be controlled by the distal articulatingsection514, then fine-tuned via theproximal articulating section518. One example of the catheter's utility is the procedure for cannulating the renal artery when an occlusion is located at the ostium, as shown inFIG. 27. In this case, the physician would bend the distal articulatingsection514 to orient thedistal tip512 towards the ostium, while bending the proximal articulatingsection518 to ensure that thedistal tip512 does not contact the occlusion.
• The multi-bend algorithm leverages the counteractingpullwire508′ and the common mode (uniformly tensioning the remaining three pullwires508) to independently control the distal articulatingsection514 and proximal articulatingsection518. In particular, with reference toFIG. 28, the multi-bend algorithm that maps articulation commands (α_d, θ, and α_p) to pullwire distances {right arrow over (w)} will be described.
• The commanded distal articulations α_dand θ are mapped to distal pullwire distances {right arrow over (w)}_dthrough a distal articulating section solid mechanics model. The threepullwires508 fastened to thecontrol ring506 are used to produce the desired bend at the distal articulatingsection514. Based on the commanded distal articulations α_dand θ, a bending force is computed using a constant moment assumption, as disclosed in D. B. Camarillo, C. F. Milne, C. R. Carlson, M. R. Zinn, and J. K. Salisbury; Mechanics Modeling of Tendon-Driven Continuum Manipulators; IEEE Transaction on Robotics, 24(6): 1262-1273 (2008). A series spring model of the catheter is then used to compute the distal pullwire distances {right arrow over (w)}_dthat will produce the desired moment. However, the computed distal pullwire distances {right arrow over (w)}_dmay be negative, which is not physically feasible, since this indicates that thepullwires508 must be pushed. Thus, a null space of control is added to the distal pullwire distances {right arrow over (w)}_duntil all distal pullwire distances {right arrow over (w)}_dare positive. For the distal articulatingsection514, the null space involves adding the same pullwire distance to all threepullwires508, which does not modify the distal articulations α_dand θ.
• These pullwire distances {right arrow over (w)}_dare input to a proximal motion predictor that produces an expected proximal articulation angle {tilde over (α)}_p. There are two effects: a distal moment effect and a common mode effect, that contribute to the expected proximal articulation angle {tilde over (α)}_pbased on the pullwire distances {right arrow over (w)}_d. With respect to the distal moment effect, when a distal pullwire is tensioned, a moment is applied at thecontrol ring506. Based on the constant moment assumption disclosed in D. B. Camarillo, this moment is transferred to the proximal articulatingsection518. With respect to the common mode effect, when one of the non-straight pullwires508 (i.e., spiraled around the transition section516) is tensioned, the path of thepullwire508 through thetransition section516 causes a moment M to be applied to thetransition section516 in the direction of the side of the catheter on which thepullwires508 are grouped, as best illustrated inFIG. 29. This moment M causes the proximal articulatingsection518 to bend in the direction of the groupedpullwires508. To decouple the proximal and distal bend motions from each other, both of these effects must be taken into account.
• The expected proximal articulation angle {tilde over (α)}p due to the distal moment effect can be computed by applying the material properties of the proximal articulatingsection518 to the basic moment-bending relation:
• $\begin{array}{cc}{\tilde{\alpha }}_p=\frac{M_d·L_p}{K_p},& \left[2\right]\end{array}$
• where M_dis the moment applied to thecontrol ring506, L_pis the length of the proximal articulatingsection518, and K_pis the bending stiffness of the proximal articulatingsection518.
• The magnitude of the common mode effect depends upon the path of thenon-straight pullwires508 through thetransition section516. To understand this effect, it should be noted that the lowest energy configuration for a pullwire of a given unloaded length under tension between two points is a straight path. However, the non-straight pullwires have non-zero curvature, and will exert forces on thecatheter500 based on the magnitude of the curvature. These forces can be integrated to calculate an equivalent force and moment that a non-straight pullwire applied to thetransition section516 based on wire tension. Integrating the forces along the wire paths in thetransition section516 shows that the wire curvatures exert no net force and a moment proportional to the wire tension. As a result, a pure moment is transferred from thestiff transition section516 to the flexibleproximal articulating section518, causing a constant-curvature proximal bend.
• The magnitude of this moment M_tcan be modeled by a gain K_ton the wire tension F_win a non-straight pullwire, as follows:
• 
  M_t=K_tF_w  [3]
• The gain K_tcan either be derived from a path integral over the geometry of a given pullwire, or tuned empirically to experimentally dial in a stiffness or gain. Since thetransition section516 is relatively rigid, the pullwire geometry in this section does not change and the gain K_tremains constant.
• The estimated proximal articulation angle {tilde over (α)}_pdue to the common mode effect can be computed by applying the material properties of the proximal articulatingsection518 to the basic moment-bending relation:
• $\begin{array}{cc}{\tilde{\alpha }}_p=\frac{M_t·L_p}{K_p},& \left[4\right]\end{array}$
• The total proximal articulation angle due to the pullwire distances {right arrow over (w)}_dcan be obtained by combining equations [2]-[4], as follows:
• $\begin{array}{cc}{\tilde{\alpha }}_p=\frac{\left(M_d+\sum _i^{}K_t^{\left(i\right)}F_w^{\left(i\right)}\right)L_p}{K_p}& \left[5\right]\end{array}$
• The summation in the numerator of equation [5] operates over all transition section gains K_t⁽ⁱ⁾and F_w⁽ⁱ⁾corresponding to the bent pullwires I=1, 2, . . . . The estimated proximal articulation angle {tilde over (α)}_pis then subtracted from the commanded proximal articulation α_pto produce the amount of additional proximal articulation angle α_p⁺ required to achieve the command using the relation:
• 
  α_p⁺=α_p−{tilde over (α)}_p.  [6]
• The pullwire distance {right arrow over (w)}_prequired to achieve the additional proximal articulation angle α_p⁺ is computed by using a proximal articulating section solid mechanics model. The pullwire distance {right arrow over (w)}_pis different based on the direction of the articulation.
• That is, if the additional proximal articulation angle α_p⁺ is positive (toward the pullwire grouping), then an additional common mode is commanded by tensioning each of thedistal pullwires508 by the same distance:
• 
  w_p=K_cmα_p⁺,  [7]
• where K_cmis a gain that can be set empirically, or can be derived from the transition section gain K_tand proximal articulating section material properties.
• If the additional proximal articulation angle α_p⁺ is negative (away from the pullwire grouping), then the counteractingpullwire108′ is tensioned to achieve the articulation.
• The distal pullwire distances {right arrow over (w)}_dand proximal pullwire distances {right arrow over (w)}_pare summed to produce the final set of pullwire distances {right arrow over (w)}.
• By achieving independent articulation control over the distal articulatingsection514 and the proximal articulatingsection518 using theproximal pullwire108′, greater control when accessing anatomical sites of interest. For example, the distal pullwire orpullwires508 in the direction of the right coronary artery (in this case, pullwire 3) can be tensioned to bend the distal articulatingsection514 ninety degrees to attempt to seat thedistal tip512 within the ostium of the right coronary artery, as illustrated inFIG. 30A. However, the tension on the distal pullwire(s)408 will create a moment at the proximal articulatingsection518, and without proper compensation, may cause the proximal articulatingsection518 to inadvertently bend in a manner that pulls thedistal tip512 away from the right coronary artery ostium. By tensioning theproximal pullwire508′, the proximal articulatingsection518 may be bent back towards the right coronary artery ostium to properly seat thedistal tip512 within the ostium, as illustrated inFIG. 30B. For example, ifpullwire 3 is initially tensioned at a force of 7 units to bend the distal articulatingsection514 to create the 90 degree bend in the distal articulatingsection514,pullwire 4 may be tensioned at a force of 9 units to seat thedistal tip512 into the right coronary artery ostium.
• Although thecatheter500 has been described as having only one counteracting pullwire508′ oriented 180 degrees from thecommon mode pullwires508 to effect bending of the proximal articulatingsection518 in only one plane, it should be appreciated that thecatheter500 may optionally have two counteractingpullwires508′. For example, two counteracting pullwires can be respectively oriented 120 degrees and 240 degrees from the common mode pullwires, thereby allowing bending of the proximal articulatingsection518 in all planes.
• Furthermore, although thecatheter500 has been described as having only proximal articulatingsection518, thecatheter500 may have multiple proximal articulating sections that have increasing lateral flexibility from the most distal articulating section to the most proximal articulating section. For example, in the case where a catheter has two proximal articulating sections, a second transition section similar to thetransition section516 of thecatheter500 can be incorporated between the two proximal articulating sections. This second transition section would transition the counteractingpullwire508′ to an orientation that is adjacent thecommon mode pullwires508, so that counteractingpullwire508′ and remaining threepullwires508 would be in a common mode within the added proximal articulating section. The distal articulatingsection514 and firstproximal articulating section518 can be independently bent relative to each other in the same manner as described above. However, in this case, applying the same tension on the counteractingpullwire508′ as the combined tension on the three remainingpullwires508 will bend the additional proximal articulating section without bending the first articulatingsection518, thereby decoupling the two articulatingsections518 from each other. Another counteracting pullwire can be circumferentially disposed 180 degrees from the threepullwires508 and counteractingpullwire508′ (which are adjacent to each other in the additional proximal articulating section) to bi-directionally bend the additional proximal articulating section in one plane.
• As previously discussed above, distal and proximal regions of thecatheters100,200,400, and500 may be fabricated separately, and then mounted to each other when the transition section is fabricated. The reason for fabricating the distal and proximal regions separately is due, in large part, because the circumferential orientations of the pullwire lumens differ between these proximal and distal regions (i.e., equally circumferentially spaced from each other in the distal region, and adjacent to each other in the proximal region). To accommodate the different circumferential orientations of the pullwire lumens, the braid may be incorporated into the catheters using specially designed braiding machines.
• Referring toFIG. 32, one embodiment of abraiding machine600 capable of braiding three wires602 (only two shown) having one of two selectable circumferential orientations to atube604 will be described. Thebraiding machine600 generally comprises twointerchangeable nose cones606a,606b, afeeder assembly608, and abraiding assembly610.
• As further shown inFIGS. 33A and 33B, each of thenose cones606a,606bincludes adistal tip614, an externalconical surface616, and acircular tube aperture618. Thenose cone606aincludes anoblong wire orifice620 radially outward from coincident with the top of the circular tube aperture618 (or alternatively, three circular wire orifices (not shown) separate from thecircular tube aperture618 and spaced closely to each other), and thenose cone606 includes threecircular wire orifices622 radially outward and separate from thecircular tube aperture618 that are equally spaced in an arcuate manner (i.e., one hundred twenty degrees apart) about thecircular tube aperture618. As will be described in further detail below, thenose cone606acan be used to apply braid over atube604 with the threewires602 positioned adjacent to each other, and thenose cone606bcan be used to apply braid over atube604 with the threewires602 positioned circumferentially equidistant from each other (i.e. 120 degrees from each other). The size of thetube aperture618 is preferably large enough to just accommodate thetube604 and any layers that it may carry, the size of theoblong wire orifice620 is preferably large enough to just accommodate thewires604 and any layers that they may carry in a side-by-side relationship, and the sizes of thecircular wire orifices622 are preferably large enough to just accommodate therespective wires604 and any layers that they may carry.
• Thefeeder assembly608 is configured for advancing thetube604 through thecircular tube aperture618 and the threewires602 through theoblong wire orifice620 or thecircular wire orifices622 at the top of thecircular tube aperture618. Thefeeder assembly608 may be conventional and include a set ofdrive rollers624 distal to thenose cone606 that pull thetube604 andwires602, and a set of tensioning rollers (not shown) proximal to thenose cone606 that maintain tension on thetube604 andwires602 as they are fed through thenose cone606. Thefeeder assembly608 can be programmed to change the speed at which thetube604 andwires602 are advanced through thenose cone606, such that the pic count of the braid may be varied.
• Thebraiding assembly610 is configured for braiding a plurality offilaments628 around thetube604 andwires602 as they are advanced throughnose cone606. To this end, thebraiding assembly610 includes a plurality ofspindles630, each of which wraps arespective filament628 around thetube604 andwires602. Thespindles630 rotate around each other and move in and out in a coordinated manner, such that thefilaments628 form a braid on thetube604 andwires602. Thebraiding assembly610 and either of thenose cones606a,606bare arranged relative to each other, such that theexternal surface616 of therespective nose cone606a,606bserves as a bearing surface for thefilaments628 as they are braided around thetube604 and thewires602 at thedistal tip614 of thenose cone606a,606b. In the illustrated embodiment, sixteenspindles630 and corresponding filaments628 (only two shown) are provided to create the braid, although any number ofspindles630 andfilaments628 can be used.
• As briefly discussed above, thenose cones606a,606bcan be interchanged with one another to apply braid overtubes604 and threewires602 of two different orientations. In particular, thefirst nose cone606awill be installed on thebraiding machine600 when fabricating a braidedassembly having wires602 that are adjacent to each other. That is, theoblong wire orifice620 of thefirst nose cone606awill maintain a set of threewires602 in a closely grouped fashion, such that they remain circumferentially adjacent to each other as thefilaments628 are braided over atube604 and thewires602. In contrast, thesecond nose cone606awill be installed on thebraiding machine600 when fabricating a braidedassembly having wires602 that circumferentially equidistant from each other. That is, the threeseparate wire orifices622 of thesecond nose cone606bwill maintain another set of threewires602 circumferentially equidistant from each other (in this case, 120 degrees from each other), such that they remain equidistant from each other as thefilaments628 are braided over anothertube604 and thewires602. It should be appreciated that additional or alternative nose cones with different numbers of wire orifices or wire orifices of different orientations can be used to fabricate different braided assemblies.
• Having described the structure and function of thebraiding machine600, one method of using thebraiding machine600 to fabricate a catheter will now be described. In this embodiment, the fabricated catheter can be similar to thecatheter400 described above, with the exception that this catheter has three, instead of four, pullwires.
• A distal articulating section can be fabricated by first inserting a copper wire process mandrel through a lumen of an inner polymer tube (e.g., a PTFE extrusion)604 having the intended length of the distal articulating section. Then, using thebraiding machine600 with thesecond nose cone606b, a first layer of braiding is laid down over the length of theinner polymer tube604. Notably, this step only requires the inner polymer tube to be advanced through thetube aperture618 without advancing any of the threewires602 through thewire orifices622 of thesecond nose cone606b. Next, the three wires602 (which take the form of PTFE-coated stainless steel wire process mandrels) are respectively disposed over the length of the braidedinner polymer tube604 in three equally spaced circumferential positions (i.e., clocked 120 degrees from each other), and a second layer of braiding is laid down over the threewires602. This step requires both the braidedinner polymer tube604 to be advanced through thetube aperture618 and thewires602 to be advanced through thewire orifices622 of thesecond nose cone606bduring the braiding process. Next, one or more outer tubular polymer tubes are laminated over the fully braided inner polymer tube. Then, the center copper wire can be pulled from the assembly to create a working lumen, and the threestainless steel wires602 can be pulled from the assembly to respectively create three pullwire lumens.
• In a similar manner, a proximal shaft section can be fabricated by first inserting a copper wire process mandrel the lumen of an inner polymer tube (e.g., a PTFE extrusion)604 having the intended length of the proximal shaft section. Then, using thebraiding machine600 with thefirst nose cone606a, a first layer of braiding is laid down over the length of theinner polymer tube604. Notably, this step only requires theinner polymer tube604 to be advanced through thetube aperture618 without advancing any of the threewires602 through theoblong aperture12 of thefirst nose cone606a. Next, the three wires602 (which take the form of PTFE-coated stainless steel wire process mandrels with polyimide tubing) are respectively disposed over the length of the braidedinner polymer tube604 in adjacent positions, and a second layer of braiding is laid down over the threewires602. This step requires both the braidedinner polymer tube604 to be advanced through thetube aperture618 and thewires602 to be advanced through the oblong aperture of thefirst nose cone606aduring the braiding process. Next, one or more outer tubular polymer tubes are laminated over the fully braided inner polymer tube. Then, the center copper wire can be pulled from the assembly to create a working lumen, and the threestainless steel wires602 can be pulled from the assembly to respectively create three pullwire lumens.
• Next, the distal articulating section and the proximal shaft section are coupled to each other by fabricating a transition section between the distal articulating section and proximal shaft section and pullwires with the control ring are installed in the same manner described above with respect to fabricating thetransition section416 to couple the distal articulatingsection414 and the combined proximal articulatingsection418/proximal shaft section420 together, with the exception that three pullwire lumens and corresponding pullwires, instead of four pullwire lumens and corresponding pullwires, are incorporated into the catheter.
• Referring toFIGS. 34 and 35, another embodiment of abraiding machine700 capable of braiding threewires602 having two different circumferential orientations to asingle tube604 will be described. Thebraiding machine700 is similar to the previously describedbraiding machine600, with the exception that it is capable of applying the braid to a single tube with different circumferential orientations of thewires602. In this manner, thewires602, and thus the pullwire lumens, need not be bonded to any portion of the inner polymer tube. That is, one continuous braid and threecontinuous wires602 with varying circumferential orientations can be applied over asingle tube604. In this manner, not only does this eliminate the processing time required to independently fabricate and subsequently join the separate sections of the catheter together, it eliminates the inherent variation that may result in manually positioning the lumens of the separate catheter sections together. Furthermore, the step of bonding wires to the transition section that would otherwise be needed to join the distal articulating section and proximal shaft section together is eliminated. Since the wires must be otherwise weakly bonded to the inner polymer tube as a stronger bond would negatively affect the performance of the completed catheter, this may be significant, since the braiding process is not gentle and could break or shift the bonds between the wires and the inner polymer tube.
• Thebraiding machine700 generally comprises thefeeder assembly608 and abraiding assembly610, the details of which have been described above. Thebraiding machine700 differs from thebraiding machine600 in that it comprises asingle nose cone706 and an iris assembly712 (shown in phantom), which in the illustrated embodiment, is installed within thenose cone706.
• Like the previously describednose cones606a,606b, thenose cone706 includes adistal tip714, an externalconical surface716, and acircular tube aperture718. In the illustrated embodiment, thenose cone706 does not include a wire aperture per se. Rather, the size of thetube aperture718 is preferably large enough to accommodate both thetube604 and any layers that it may carry, as well as thewires602 and any layers that they may carry (i.e., the diameter of thetube aperture718 is equal to or slightly greater than the combined diameters of thetube604 and one of the wires602). Theiris assembly712 is operable to adjust the relative circumferential positions of the wires704 as the exit from thetube aperture718 around the tube702, and in the illustrated embodiment, between a relative circumferential position where the wires704 are adjacent to each other in a side-by-side relationship and a relative circumferential position where the wires704 are positioned circumferentially equidistant from each other (i.e. 120 degrees from each other).
• To this end, and with reference toFIGS. 36-41, theiris assembly712 comprises threestacked iris plates720a,720b, and720c, each of which includes acenter aperture722, awire orifice724 disposed radially outward from thecenter aperture722, and at least onearcuate channel726 in circumferential alignment with therespective wire orifice724. Thefeeder assembly608 is configured for advancing thetube604 through thecenter apertures722 of theiris assembly712, as well as through thetube aperture718 of thenose cone706, and the for advancing thewires602 through therespective wire orifices724 of theiris assembly712, as well as through the periphery of thetube aperture718 of thenose cone706.
• The iris plates720 are rotatable relative to each other to adjust the circumferential orientation of thewire orifices724 relative to each other, while the arcuate channel(s)726 of each respective iris plate720 is coincident with thewire orifices724 of the remaining two iris plates720. In this manner, anywire orifice724 may be adjusted via rotation of the respective iris plate720 without blocking the path of thewire orifices724 of the other iris plates720. Thebraiding assembly610 is configured for braiding thefilaments628 around thetube604 and thewires602 as they are fed through theiris assembly712 and as the respective iris plates720 are rotated relative to each other to create the braided tube assembly. Thus, theiris assembly712 may be operated to circumferentially orient thewires602 relative to each other differently along the braided tube assembly.
• In the illustrated embodiment, theiris plate720ais rotationally fixed relative to thenose cone706, while the remaining twoiris plates720b,720care capable of being rotated relative to thenose cone706. To facilitate their rotation, each of the twoiris plates720b,720cincludes alever728 that can be manipulated to rotate therespective iris plate720b,720c. Thelevers728 may be manipulated, such that rotation of therespective iris plates720b,720ccan be synchronously automated with thefeeder assembly608. To accommodate thelevers728, thenose cone706 may include aslot730 through which thelevers728 for connection to the motor and linkage assembly. To facilitate rotation of the iris plates720 relative to each other, theiris assembly712 further comprises thrust bearings730 (shown in phantom inFIG. 36) mounted between the iris plates720, and in particular, a first thrust bearing730amounted between therespective iris plates720a,720b, a second thrust bearing730bmounted between therespective iris plates720b,720c, and a third thrust bearing730cmounted between theiris plate720cand thedistal tip714 of thenose cone706. Each of thebearings730 includes a center aperture732 that accommodates thetube604 andwires602 as they pass through theiris assembly712.
• Referring back toFIG. 34, thebraiding machine700 further comprises a mechanical driver734 (which may include a motor and appropriate linkage) connected to thelevers728 for rotating the iris plates720 relative to each other, and acontroller736 configured, while thebraiding assembly610 is braiding thefilaments628 around thetube604 and thewires602 over a period of time, instructing themechanical driver734 to maintain an initial relative rotational orientation of the iris plates720, such that spacings between therespective wire orifices724 are equal over a first portion of the time period, instructing themechanical driver734 to gradually change the rotational orientation of the iris plates720, such that spacings between therespective wire orifices724 decrease over a second portion of the time period until therespective wire orifices724 are adjacent to each other, and instructing themechanical driver734 to maintain the changed relative rotational orientation of the iris plates720, such that therespective wire orifices724 are adjacent to each other over a third portion of the time period.
• As briefly discussed above, thewire orifices724 and arcuate channel(s)726 of the respective iris plates720 are arranged in a manner that allows the threewire orifices724 to be placed between an adjacent circumferential orientation and an equally spaced circumferential orientation without blocking the paths of thewire orifices724.
• To this end, thefirst iris plate720ahas two arcuate channels726athat straddle the respective wire orifice724a(FIG. 40) The furthest extent of each of these arcuate channels726ais at least 120 degrees from the wire orifice724a. Thesecond iris plate720bhas a singlearcuate channel720bwith a furthest extent of at least 240 degrees counterclockwise from the wire orifice724bof thesecond iris plate720b(FIG. 41). Thethird iris plate720chas a singlearcuate channel720cwith a furthest extent of at least 120 degrees clockwise from the wire orifice724cof thethird iris plate720c(FIG. 42). It can be appreciated that, when thelevers728 of therespective iris plates720b,720care moved to their downward position, thewire orifices724a-724care located circumferentially adjacent to each other, as shown inFIG. 38. In contrast, when thelevers728 of therespective iris plates720b,720care moved to their upward position, thewire orifices724a-724care circumferentially spaced equidistant from each other, as shown inFIG. 39.
• The right arcuate channel726aof thefirst iris plate720aremains coincident with the wire orifice724bof thesecond iris plate720bas thelever728 of thesecond iris plate720bis moved between the upward and downward positions. Thus, the right arcuate channel726aprevents thefirst iris plate720afrom blocking the path of the wire orifice724bof thesecond iris plate720b. Similarly, the left arcuate channel726aof thefirst iris plate720aremains coincident with the wire orifice724cof thethird iris plate720cas thelever728 of thethird iris plate720cis moved between the upward and downward positions. Thus, the left arcuate channel726aprevents thefirst iris plate720afrom blocking the path of the wire orifice724cof thethird iris plate720c.
• The arcuate channel726bof thesecond iris plate720bremains coincident with the wire orifice724aof thefirst iris plate720aand the wire orifice724cof thethird iris plate720cas thelever728 of thesecond iris plate720bis moved between the upward and downward positions. Thus, the arcuate channel726bprevents thesecond iris plate720bfrom blocking the paths of the wire orifice724aof thefirst iris plate720aand the wire orifice724cof thethird iris plate720c. The arcuate channel726cof thethird iris plate720cremains coincident with the wire orifice724aof thefirst iris plate720aand the wire orifice724bof thesecond iris plate720bas thelever728 of thethird iris plate720cis moved between the upward and downward positions. Thus, the arcuate channel726cprevents thethird iris plate720cfrom blocking the paths of the wire orifice724aof thefirst iris plate720aand the wire orifice724bof thesecond iris plate720b.
• Having described the structure and function of thebraiding machine700, one method of using thebraiding machine700 to fabricate a catheter will now be described. The catheter can be fabricated by first inserting a copper wire process mandrel through a lumen of an inner polymer tube (e.g., a PTFE extrusion) having the intended length of the catheter. Then, a first layer of braiding is laid down over the length of the inner polymer tube. Notably, this step only requires the inner polymer tube to be advanced through thecenter aperture722 of theiris assembly712 and thetube aperture718 of thenose cone706 without advancing any of the threewires602 through thewire orifices724 of theiris assembly712 or thetube aperture718 of thenose cone706. Next, the three wires602 (which take the form of PTFE-coated stainless steel wire process mandrels) are respectively disposed over the length of the braided inner polymer tube in varying circumferential positions, and a second layer of braiding is laid down over the threewires602.
• This step requires both the braided inner polymer tube to be advanced through thecenter aperture722 of theiris assembly712 and thetube aperture618 of thenose cone706, and thewires602 to be advanced through thewire orifices724 of theiris assembly712 and thetube aperture718 of thenose cone706 during the braiding process. Furthermore, during this step, thelevers728 of theiris plates720b,720care manipulated to change the relative circumferential positions of thewire orifices724 of theiris assembly712, and thus, thewires602 on which the braid is laid. In particular, during the length of the distal articulating section of the catheter, thelevers728 of therespective iris plates720b,720care moved to their downward position, such that thewire orifices724a-724c, and thus, thewires602, are located circumferentially adjacent to each other. During the length of the transition section of the catheter, thelevers728 of therespective iris plates720b,720care gradually moved to their upward position, such that thewire orifices724a-724c, and thus, thewires602, are gradually moved from a position where they are circumferentially adjacent to each other at the distal-most extent of the transition section to a position where they are circumferentially spaced equidistant from each other at the proximal-most extent of the transition section. During the length of the proximal shaft section of the catheter, thelevers728 of therespective iris plates720b,720care maintained in their upward position, such that the spacings of thewire orifices724a-724c, and thus, thewires602, is maintained circumferentially equidistant from each other. Next, one or more outer tubular polymer tubes are laminated over the fully braided inner polymer tube. Then, the center copper wire can be pulled from the assembly to create a working lumen, and the threestainless steel wires602 can be pulled from the assembly to respectively create three pullwire lumens.
• Although the iris assembly has been described as comprising three iris plates for respectively accommodating threewires602, it should be appreciated that the number of iris plates can be less or more than three, depending on the number ofwires602 that are to be incorporated into the catheter.
• For example, in the case where twowires602 are to be accommodated, the iris assembly may comprise only two iris plates. In this case, one of the iris plates will have a single arcuate channel with a furthest extent at least 180 degrees clockwise from the wire orifice, and the other iris plate will have a single arcuate channel with a furthest extent at least 180 degrees counterclockwise from the wire orifice. Thus, the wire orifices in this iris assembly may be selectively located circumferentially adjacent to each other or circumferentially spaced equidistant from each other by 180 degrees.
• In the case where fourwires602 are to be accommodated, the iris assembly may comprise four iris plates. In this case, the first iris plate has a single arcuate channel that extends virtually all the way around the respective iris plate from one side of the wire orifice to the other side of the wire orifice. The second iris plate has a single arcuate channel with a furthest extent of at least 270 degrees counterclockwise from the wire orifice of the second iris plate. The third iris plate has a single arcuate channel with a furthest extent of at least 270 degrees clockwise from the wire orifice of the third iris plate. The fourth iris plate has a single arcuate channel that extends virtually all the way around the respective iris plate from one side of the wire orifice to the other side of the wire orifice. Thus, the wire orifices in this iris assembly may be selectively located circumferentially adjacent to each other or circumferentially spaced equidistant from each other by 90 degrees.
• Although particular embodiments of the present inventions have been shown and described, it will be understood that it is not intended to limit the present inventions to the preferred embodiments, and it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present inventions. Thus, the present inventions are intended to cover alternatives, modifications, and equivalents, which may be included within the spirit and scope of the present inventions as defined by the claims.

Claims (21)

What is claimed is:

1. A catheter, comprising:

a flexible polymer catheter body including a proximal shaft section and a distal working section;

a wire support structure embedded within the distal working section of the catheter body;

a proximal adapter mounted to the proximal shaft section of the catheter body; and

a wire disposed within the catheter body, the wire having a proximal end operably connected to the proximal adapter, and a distal end anchored to the wire support structure.

2. The catheter ofclaim 1, wherein the wire support structure is a braided tubular structure.

3. The catheter ofclaim 1, wherein the wire support structure is a coiled structure.

4. The catheter ofclaim 1, wherein the wire support structure comprises a plurality of tubular layers, wherein the distal end of the wire is anchored between the tubular layers of the wire support structure.

5. The catheter ofclaim 1, further comprising a lumen disposed within the catheter body, wherein the wire is a pullwire extending through the lumen, the distal working section of the catheter body is a distal articulatable section, and the proximal adapter is a proximal steerable interface that is manipulatable to selectively tension the pullwire to bend the distal articulating section.

6. The catheter ofclaim 1, further comprising an electrode mounted to the distal working section of the catheter body, wherein the wire is an electrical wire, the distal end of which is electrically coupled to the electrode.

7. The catheter ofclaim 1, wherein the cross-sectional shape of the catheter body is either circular or rectangular.

8. The catheter ofclaim 1, further comprising a lumen extending through the catheter body.

9. A method of constructing a catheter, comprising:

disposing a wire support structure over an inner polymer tube;

disposing at least one outer polymer tube over the wire support structure and wire;

applying heat to the melt the at least one outer polymer tube, thereby flowing the at least one melted outer polymer tube into the wire support structure;

allowing the at least one melted outer polymer tube to solidify, thereby integrating the wire support structure, inner polymer tube, and at least one solidified outer polymer tube together into a catheter body;

disposing a wire through the catheter body; and

anchoring a distal end of the wire to the wire support structure at a distal end of the catheter body.

10. The method ofclaim 9, wherein the wire support structure is disposed on the inner polymer tube by braiding filament onto the inner polymer tube.

11. The method ofclaim 9, wherein the wire support structure comprises a plurality of tubular layers, wherein the distal end of the wire is anchored between the tubular layers of the wire support structure.

12. The method ofclaim 9, further comprising:

mounting a proximal adapter to a proximal end of the catheter body; and

operatively coupling a proximal end of the wire to the proximal adapter.

13. The method ofclaim 9, further comprising disposing a barrier over the wire support structure prior to melting the at least one outer tube, wherein the melting temperature of the barrier is greater than the temperature of the heat applied to the at least one outer polymer tube, and removing the barrier from the catheter body subsequent to allowing the at least one melted outer tube to solidify, thereby exposing a portion of the wire support structure, wherein the distal end of the wire is anchored to the exposed portion of the wire support structure.

14. The method ofclaim 13, wherein the barrier is a tubular barrier, and the exposed portion of the wire support structure is cylindrical.

15. The method ofclaim 13, further comprising:

disposing another outer polymer tube over the exposed cylindrical portion of the wire support structure;

melting the other polymer tube, thereby flowing the other outer polymer tube into the exposed cylindrical portion of the wire support structure; and

allowing the other melted outer polymer tube to solidify.

16. The method ofclaim 9, further comprising forming a lumen within the catheter body, wherein the wire is a pullwire extending through the lumen, and the proximal adapter is a proximal steerable interface.

17. The method ofclaim 16,

wherein forming a lumen within the catheter body comprises disposing a process mandrel over the inner polymer tube prior to melting the at least one outer tube, and removing the process mandrel from the catheter body subsequent to allowing the at least one melted outer tube to solidify; and

wherein disposing the wire through the catheter body comprises threading the wire through the lumen.

18. The method ofclaim 9, wherein the wire is an electrical wire, and the method further comprises forming an electrode to the catheter body in electrical communication with the wire.

19. The method ofclaim 18, wherein forming the electrode on the catheter body comprises disposing a barrier over the wire support structure prior to melting the at least one outer tube, removing the barrier from the catheter body subsequent to allowing the at least one melted outer tube to solidify, thereby exposing a portion of the wire support structure, and disposing the electrode on the exposed portion of the wire support structure.

20. The method ofclaim 9, wherein anchoring the distal end of the wire to the wire support structure comprising soldering, welding, brazing, or gluing the distal end of the wire to the wire support structure.

21. The method ofclaim 9, wherein the inner polymer tube has a lumen extending therethrough.

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