CATHETER HAVING TAPERED SUPPORT MEMBER FOR A VARIABLE ARC DISTAL ASSEMBLY - Patent application

Abstract

To provide a catheter having a variable arc distal section that has improved retraction and bend radius characteristics as well as greater durability. A catheter having a variable circular loop according to a contraction wire for coiling is supported by a member having a tapered distal section that transitions from a circular cross section to a generally rectangular cross section while maintaining a uniform cross-sectional area along its entire tapered length for improved coiling characteristics. A radially contractible sleeve prevents the contraction wire from separating from the support member, thereby minimizing distortion of the loop during contraction.

Description

[Technical field]

[0001] The present invention relates generally to methods and devices for invasive medical procedures, and more particularly to catheters, especially catheters having a distal section adapted for mapping and ablation of selected anatomical structures. [Background technology]

[0002] Ablation of myocardial tissue is a well-known treatment for cardiac arrhythmias. In radiofrequency (RF) ablation, for example, a catheter is inserted into the heart and brought into contact with tissue at a target location. RF energy is then applied via electrodes on the catheter to create lesions with the goal of destroying the pathways of arrhythmogenic currents in the tissue.

[0003] Circumferential ablation of the ostium of a pulmonary vein is now accepted as a treatment for atrial arrhythmias, and in particular for atrial fibrillation. For example, U.S. Patent No. 6,064,902, the disclosure of which is incorporated herein by reference, describes a catheter for ablating tissue on the inner wall of a blood vessel, such as a pulmonary vein. The tip portion of the catheter is deflectable from a first generally straight configuration, in which the proximal and distal sections are substantially collinear, to a second J-shaped configuration, in which the proximal and distal sections are generally parallel with a separation distance therebetween that corresponds substantially to the inner diameter of the blood vessel. The distal end portion of the catheter is rotated about the longitudinal axis of the catheter to cause circumferential displacement of the proximal and distal ablation electrodes on the catheter along the inner wall of the pulmonary vein. In this manner, the electrode catheter can be used to ablate multiple circumferentially spaced sites on the inner wall of a pulmonary vein by ablating one or two sites at each circumferential location.

[0004] No. 6,973,339, the disclosure of which is incorporated herein by reference, describes a lasso for pulmonary vein mapping and ablation. A catheter for circumferentially mapping pulmonary veins (PV) includes a curved section shaped to generally closely match the shape of the inner surface of the PV. The curved section is connected to the catheter by a generally straight axial base section in an "on edge" configuration, where the base axial section connects to the curved section on the periphery of the curved section. The curved section includes one or more sensing electrodes, the proximal end of which is joined at a constant or generally known angle to the base section of the catheter. A position sensor is fixed to the distal end of the curved section and base section of the catheter. The catheter is inserted into the heart and the curved section is positioned in contact with the wall of the PV, while the base section is left in the left atrium, typically with the curved section and its junction positioned at the venous ostium. The information generated by the three position sensors is used to calculate the location and orientation of the sensing electrodes, which can additionally perform ablation of selected sites, and the catheter can further comprise an ablation element.

[0005] U.S. Patent No. 7,008,401, the disclosure of which is incorporated herein by reference, describes compound steering assemblies that can be used in both diagnostic and therapeutic applications to steer the distal section of a catheter in multiple planes or complex curves. These assemblies are said to enable a physician to quickly and accurately position and maintain ablation and / or mapping electrodes in intimate contact with an internal body surface. U.S. Patent No. 5,820,591, the disclosure of which is incorporated herein by reference, similarly describes compound steering assemblies of this type.

[0006] U.S. Patent No. 8,608,735, the disclosure of which is incorporated herein by reference, describes a medical device including an insertion shaft having a longitudinal axis and a distal end adapted for insertion into a patient's body. A resilient end section is secured to the distal end of the insertion shaft and is shaped to define an arc having a center of curvature on the axis when unconstrained and oriented obliquely relative to the axis. One or more electrodes are disposed at respective locations along the end section.

[0007] However, because human anatomy varies between individuals, the shape and size of the ostium varies, and the arcuate distal section may not always be able to fit a particular target ostium. Furthermore, it may be desirable to use the same catheter for a target ostium of a certain diameter and for the PV at that ostium, which may also have a significantly smaller diameter. In addition, when a lasso catheter has a variable arcuate distal assembly, contraction of the arcuate distal assembly may distort the generally circular configuration of the arcuate distal assembly because one or more of its components are too stiff to coil relatively closely in the desired manner.

[0008] Current circular loop catheters are constructed utilizing support members such as nitinol spines having a constant uniform cross-section that cannot consistently maintain a circular configuration during loop retraction. Such current circular loop catheters are also limited in their retraction and deflection characteristics in that they require smaller retraction wire pull forces for smaller loop retractions. Additionally, current circular loop catheters may lack a reliable attachment between the contraction wire and the support member that would eliminate the possibility of the contraction wire breaking or becoming dislodged from the support member. Current circular loop catheters have nitinol spines that have the same uniform moment of area along their entire length, and the nitinol spines have the same cross-sectional area. Summary of the Invention [Means for solving the problem]

[0009] The present invention is directed to a catheter having a variable arcuate distal section with improved contraction and bend radius characteristics in addition to greater durability. The variable arcuate distal section includes a variable tapered support member for greatly increasing the degree of contraction of a generally circular catheter loop while reducing forces on the contraction wire and all other structural support portions of the loop, providing the catheter operator with a repeatable and more true circular contraction for circular diagnostic and therapeutic catheters. The variable tapered support member also provides increased and more uniform contact forces between an annular electrode carried by the loop and cardiac tissue by increasing the stiffness of the catheter loop along the axis of contraction.

[0010] In some embodiments, a catheter having a variable circular loop is supported by a member having a tapered distal section that transitions from a circular cross-section to a generally rectangular cross-section while maintaining a uniform cross-sectional area along its tapered length, the tapered distal section providing a decreasing moment of area along a first centroid axis and an increasing moment of area along a second centroid axis generally perpendicular to the first centroid axis. Thus, the tapered section is biased to deflect less along the second centroid axis with an increased moment of area and to deflect more along the first centroid axis with a decreased moment of area.

[0011] In some embodiments, an electrophysiology catheter includes an elongate catheter body, a contraction wire, and a distal assembly configured to contract upon actuation of the contraction wire. The distal assembly has a shape memory support member having a 3D configuration with a distal portion defined by a distal radius. The shape memory support member has a generally rectangular cross-section defined by a width and a height. The generally rectangular cross-section is tapered at the distal portion such that a distal location of the distal portion has a greater height and a smaller width, and a proximal location of the distal portion has a smaller height and a greater width.

[0012] In a more detailed embodiment, the support member has an inner surface facing the inner circumference of the 3D configuration, with a coextensive portion of the contraction wire extending through the distal assembly aligned with the inner surface.

[0013] In some detailed embodiments, the distal assembly includes a radially shrinkable sleeve that surrounds the support member and a portion of the contraction wire coextensive with the support member.

[0014] In some detailed embodiments, the distal assembly includes a laser welded connection of a distal end of a support member and a contraction wire, the distal end of the support member having a cross-section that is different from a generally rectangular cross-section.

[0015] In another embodiment, an electrophysiology catheter includes an elongate catheter body, a contraction wire, and a 3D arcuate distal assembly configured to be contracted by the contraction wire, the distal assembly including a first tube defining an inner circumference and having a lumen at or near the inner circumference, and an elongate support member extending through the lumen, the support member having a longitudinal flat surface. The contraction wire extends through the lumen and has a coextensive section along one or more flat surfaces of the support member. The distal assembly also includes a sleeve circumferentially surrounding the support member and the coextensive section of the contraction wire.

[0016] In some detailed embodiments, the support member and the coextensive section of the contraction wire collectively define a cross-sectional profile, and the sleeve surrounds the support member and the coextensive section in general conformance with the cross-sectional profile.

[0017] In some detailed embodiments, the coextensive portion of the contraction wire is aligned with the flat surface of the support member during contraction of the distal assembly and is configured to maintain the coextensive section of the contraction wire in substantial alignment with the flat surface.

[0018] In some detailed embodiments, the support member has a distal tail portion, the support member having a generally rectangular cross-section defined by a width and a height, the generally rectangular cross-section being tapered at the distal tail portion.

[0019] In some detailed embodiments, a distal location of the distal tail portion has a greater height and a smaller width, and a proximal location of the distal tail portion has a smaller height and a greater width.

[0020] In some embodiments, an electrophysiology catheter includes an elongate catheter body defining a longitudinal axis, a contraction wire, and a 3D distal assembly movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction wire. The 3D distal assembly includes an elbow junction and a distal portion. The elbow junction is defined by at least a proximal diameter, and the distal portion is defined by a distal diameter. In the neutral configuration, the proximal diameter is smaller than the distal diameter. In the contracted configuration, the distal diameter is approximately equal to or smaller than the proximal diameter.

[0021] In some detailed embodiments, the elbow joint has a torsion portion configured to support the distal portion generally transverse to the longitudinal axis, such that the longitudinal axis extends through the center of the distal portion.

[0022] In some detailed embodiments, the distal assembly has an elongate support member having an inner planar surface and an opposing planar surface, and the contraction wire has a distal section coextensive with the inner planar surface along its entire length.

[0023] In some detailed embodiments, the inner surface of the support member is on or near the inner circumference of the distal portion of the 3D distal assembly.

[0024] In some embodiments, the distal assembly further includes a radially shrinkable sleeve circumferentially surrounding both the elongate support member and the friction reduction tube surrounding the contraction wire.

[0025] In some embodiments, the radially shrinkable sleeve is circumferentially shrinkable around the support member and the friction reduction tube in minimizing lateral movement of the contraction wire relative to the support member.

[0026] In another embodiment, an electrophysiology catheter includes an elongate catheter body defining a longitudinal axis, a contraction wire, and a distal assembly having a 3D arcuate configuration, the distal assembly being movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction wire. The distal assembly includes a support member providing the 3D arcuate configuration, the 3D arcuate configuration having an elbow junction and a distal portion, the elbow junction being defined by at least a proximal diameter, the distal portion being defined by a distal diameter, and a radially contractible sleeve surrounding coextensive portions of the support member and the contraction wire. In the neutral configuration, the proximal diameter is smaller than the distal diameter. In the contracted configuration, the distal diameter is reduced to a diameter approximately smaller than the distal diameter.

[0027] In some detailed embodiments, the 3D arcuate form defines an inner circumference, the distal assembly includes a tube having multiple lumens including a lumen closest to the inner circumference, and the support member and coextensive portions of the contraction wire are within the lumen closest to the inner circumference.

[0028] In some detailed embodiments, the support member has a generally rectangular cross-section, the support member having a distal portion, and the width and height dimensions of the generally rectangular cross-section vary along the length of the distal portion. [Brief description of the drawings]

[0029] These and other features and advantages of the present invention will be more fully understood by considering the following detailed description in conjunction with the accompanying drawings, in which: It is understood that selected structures and features have not been shown in certain drawings in order to improve visibility of the remaining structures and features. [Figure 1] FIG. 1 is a plan view of a catheter of the present invention, according to one embodiment. [Figure 2A]FIG. 2 is a detailed view of the 3D arcuate distal assembly of the catheter of FIG. 1 in a neutral, unconstrained configuration. [Figure 2B] FIG. 3 is a detailed view of the 3D arcuate distal assembly of FIG. 2 in a contracted configuration. [Diagram 3] 2 is a cross-sectional end view of the catheter body of the catheter of FIG. 1 taken along line AA. [Figure 4] 2 is a cross-sectional end view of the deflectable intermediate section of the catheter of FIG. 1 taken along line BB. [Figure 5A] 2 is a cross-sectional end view of the connector section of the catheter of FIG. 1 taken along line CC. [Figure 5B] 2 is a side cross-sectional view of the connector section of FIG. 1 taken along region DD. [Figure 6A] FIG. 13 is a perspective view of a support member and coextensive contraction wires along with a radially shrinkable tube. [Figure 6B] FIG. 6B is a detailed plan view of the assembled structure of the support member and distal end of the contraction wire of FIG. 6A. [Figure 7] FIG. 2 is an end view of the distal assembly of FIG. 1. [Figure 8] FIG. 2B is a cross-sectional end view of the distal assembly of FIG. 2A taken along line EE. [Figure 9] FIG. 2B is a side cross-sectional view of the distal assembly of FIG. 2A taken along line FF. [Figure 10] FIG. 1 is a perspective view of an irrigated ablation electrode having lead attachment, according to one embodiment. [Figure 11] FIG. 2 is a side cross-sectional view of a control handle, according to one embodiment. [Figure 12] FIG. 12 is a partial cross-sectional plan view of the control handle of FIG. [Figure 13A] 7 is a cross-sectional end view of the support member of FIG. 6 before it is reconfigured; FIG. [Figure 13B] 7 is a cross-sectional end view of the support member of FIG. 6 taken along line GG. [Figure 13C] 7 is a cross-sectional end view of the support member of FIG. 6 taken along line JJ. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The embodiments of the invention described below provide probes, such as catheters, having arcuate distal electrode carrying structures that are improved for ease of steering and positioning in the heart, and in particular in tubular regions of various sizes and various peripheral locations within a tubular region within a patient's body. Such catheters can be used to create generally circular or spiral ablation paths as well as to sense electrical activity along generally curvilinear or spiral patterns for electrical potential and anatomical mapping.

[0031] 1, a catheter 10 according to a disclosed embodiment comprises a body that may include a flexible insertion shaft or catheter body 12 having a longitudinal axis 13, and an intermediate section 14 distal to the catheter body that may be deflected in one or two directions off-axis from the longitudinal axis 13. As shown in FIG 2A, extending from the intermediate section 14 is a resilient three-dimensional (3D) arcuate distal assembly 17 that is advantageously configured for significantly greater and more uniform loop contraction. As described in more detail below, the distal assembly 17 responds to operator manipulation of a control handle 16 in decreasing its radius and increasing coiling, as shown in FIG 2B.

[0032] In the embodiment depicted in Figures 1 and 3, the catheter body 12 comprises an elongated tubular structure having a single, axial or central lumen 18. The catheter body 12 is flexible, i.e., bendable, but substantially incompressible along its length. The catheter body 12 may have any suitable construction and may be made of any suitable material. In some embodiments, the construction comprises an outer wall 20 made of polyurethane or PEBAX. The outer wall 20 includes an embedded braided mesh, such as stainless steel, as is commonly known in the art, to increase the torsional stiffness of the catheter body 12 such that rotation of the control handle 16 causes the intermediate section 14 to rotate in a corresponding manner.

[0033] The outer diameter of the catheter body 12 is not critical, but in some embodiments is about 8 French or less, more preferably 7 French. Similarly, the thickness of the outer wall 20 is not critical, but is thin enough to allow the central lumen 18 to accommodate any desired wires, cables, and / or tubing. The inner surface of the outer wall 20 is lined with a stiffening tube 22 to improve torsional stability. The outer diameter of the stiffening tube 22 is about the same as or slightly smaller than the inner diameter of the outer wall 20. The stiffening tube 22 can be made of any suitable material, such as polyimide, that provides very high stiffness and does not soften at body temperature.

[0034] The deflectable intermediate section 14 comprises a shorter section of tubing 23 having multiple lumens, each of which is occupied by various components from the catheter 12 into the intermediate section 14. In the embodiment shown in FIG. 4, there are six lumens. A respective lead wire / thermocouple 40, 41 passes through the first lumen 31 when coupled to the ring electrode 19. A non-conductive protective sheath 39 may be provided surrounding the wire pairs 40 / 41. An irrigation tube 43 for delivering irrigation fluid to the distal assembly 17 passes through the second lumen 32. A deflection puller wire 44 passes through the third lumen 33 to enable deflection of the intermediate section 14. A position sensor cable assembly 48 including one or more single-axis sensors (SAS) carried by the distal assembly 17 passes through the fourth lumen 34. A contraction wire 24 passes through the sixth lumen 36 to vary the shape and size, e.g., radius of curvature, of the arcuate distal portion 15 of the distal assembly 17 in response to manipulation of the control handle by a user. As described below, the contraction wire 24 acts on a shape memory support member 50 which provides the 3D shape of the distal assembly 17.

[0035] The multi-lumen tube 23 of the intermediate section 14 is preferably made of a suitable non-toxic material that is more flexible than the catheter body 12. A suitable material is braided polyurethane or PEBAX, i.e., polyurethane or PEBAX with an embedded mesh, such as braided stainless steel. The number and size of the lumens is not critical, provided there is sufficient space to accommodate the associated components. In the illustrated embodiment, the third lumen 33 and sixth lumen 36 for the deflection puller wire 44 and contraction wire 24 are off-axis and diametrically opposed to one another, and the fifth lumen 35 for the support member 50 is on-axis.

[0036] The useful length of the catheter, i.e., the portion that can be inserted into the body excluding the distal assembly 17, can be varied as needed. Preferably, the useful length is in the range of about 110 cm to about 120 cm. The length of the intermediate section 14 is a relatively small portion of the useful length, preferably in the range of about 3.5 cm to about 10 cm, more preferably about 5 cm to about 6.5 cm.

[0037] Distal to the intermediate section 14 is the distal assembly 17. As shown in Figures 2A and 5A, a generally straight connector section 30 having a tube of suitable material such as PEEK extends between the intermediate section 14 and the distal assembly 17 with a central lumen 37 that allows the various components extending between the intermediate section 14 and the distal assembly 17 to turn and reposition as necessary to transition therebetween, as shown in Figure 5B. The components are packed within the lumen 37 of the section 30 by a suitable adhesive 112. A shape memory support member 50 extends into the distal portion of the connector section 30 a relatively short distance proximally from the distal assembly 17 in supporting and providing the 3D shape of the distal assembly 17.

[0038] As shown in Figures 2A and 6, the 3D distal assembly 17 includes a preformed arcuate distal portion 15, an elbow portion 21, and a proximal linear stem 26. The arcuate distal portion 15 carries a plurality of irrigated ring electrodes 19. The elbow portion 21 orients the distal portion 15 obliquely relative to the longitudinal axis 13 such that the longitudinal axis extends generally through the center of the distal portion 15 as shown in Figure 7. Thus, an oblique angle θ (Figure 2A) is defined between the longitudinal axis 13 and a plane P generally defined by the distal assembly 17, the oblique angle θ ranging from about 45 degrees to 135 degrees, preferably about 75 degrees to 100 degrees, and preferably about 90 degrees.

[0039] 2A, 6 and 7, elbow portion 21 has a proximal curved section 21P, an elbow junction or "kink" 42, and a distal curved section 21D. Proximal curved section 21P traces a first arc defined by a first (or proximal) radius R1 relative to longitudinal axis 13. Distal curved section 21D traces a second arc defined by a second (or intermediate) radius R2 relative to an axis 27 oblique to longitudinal axis 13. First radius R1 is smaller than second radius R2. However, both radii R1 and R2 are smaller than a third (or distal) radius R3 that defines a third arc traced by distal portion 15. In some embodiments, radius R1 ranges from about 0.1 inch to 0.25 inch, radius R2 ranges from about 0.15 inch to 0.38 inch, and radius R3 ranges from about 0.4 inch to 0.6 inch. Thus, the 3D configuration of distal assembly 17, when unconstrained, has a helical characteristic with radius R3 greater than radius R2. For example, when oblique angle θ is about 90 degrees and longitudinal axis 13 defines the Z-axis, as shown in FIG. 6, a first arc defined by radius R1 may lie in the Y / Z plane, and second and third arcs defined by radii R2 and R3, respectively, may both lie in the X / Y plane. It should be understood that the distal assembly 17 is not limited to the radii R1, R2, and R3 discussed above, but may include larger or smaller radii as needed or desired.

[0040] The 3D configuration of the distal assembly 17, when unconstrained, also has a helical characteristic in which the distal assembly 17 extends distally in a spiral manner such that the distal end 25 of the distal assembly 17 is the most distal portion of the distal assembly 17, as best shown in FIG. 2A.

[0041] Thus, the distal assembly 17 has a spiral helix configuration (or helical spiral configuration) such that a first separation gap is between the distal end 25 and the distal curved section 21D along the longitudinal axis 13, and a second separation gap is between the distal end 25 and the distal curved section 21D along the oblique axis 27. The spiral helix configuration of the distal assembly 17 can be described as an expanding helix tracing on the axis of the longitudinal axis from its proximal end to its distal end, as shown in FIG. 2A.

[0042] Based on the length of the distal portion 15, the distal assembly 17, in its neutral, unconstrained 3D configuration, can define a radius angle α of about 360 degrees between the torsion portion 42 and the distal end 25. In another embodiment, the distal assembly 17 defines a radius angle α (FIG. 6) that is greater than 360 degrees, for example, about 380 degrees. As shown in FIG. 2B, when the distal assembly 17 is contracted, the spiral helix tightens forming a "roll-up" and, concomitantly, one or more of the radii R1, R2, R3 traced by the distal assembly 17 decreases and the radius angle α corresponding to the arc by the distal assembly 17 increases between the torsion portion 42 and the distal end 25 from, for example, about 360 degrees or 380 degrees to about 540 degrees or more. Thus, the distal assembly 17 in a neutral unconstrained configuration can be used to provide circumferential contact with an ostium having a larger radius, and then adjusted to a contracted configuration to provide circumferential contact within the PV of an ostium having a significantly smaller radius.

[0043] 8, the distal assembly 17 includes a multi-lumen tube 56. In the disclosed embodiment, the tube 56 has four off-axis lumens: a first lumen 51 for the SAS cable assembly 48 (circumferentially surrounded by a friction-reducing coating 38, e.g., of TEFLON®), a second lumen 52 for the annular electrode pair wires 40, 41, a third lumen 53 for irrigation fluid delivered through irrigation tube 43, and a fourth lumen 54 for the support member 50 and contraction wire 24, a section of which is coextensive with the support member 50 within lumen 54. Again, the location and size of the lumens is not critical, except as follows: it is desirable for the location of the fourth lumen 54 for the contraction wire 24 to be on or near the inner circumference of the spiral helix of the distal assembly 17 so that proximal movement of the contraction wire 24 can act more effectively in tightening the spiral helix and increasing its coiling. The multi-lumen tube 56 may be made of any suitable material, and is preferably made of a biocompatible plastic such as polyurethane or PEBAX.

[0044] In the depicted embodiment, the preformed support member 50 of the distal assembly 17 extends through the fourth lumen 54 of the tube 56 to provide and define the 3D spiral helical form of the distal assembly 17, including the twists 42 and arcs of the proximal and distal sections 21P and 21D, and the distal portion 15 defined by radii R1, R2, and R3. The support member 50 is made of a material that has shape memory, i.e., a material that can be straightened or bent away from its original shape when a force is exerted, and can return to substantially its original shape when the force is removed. In some embodiments, a suitable material for the support member 50 is a nickel / titanium alloy. Such an alloy typically includes about 55% nickel and about 45% titanium, but can include about 54% to about 57% nickel, with the balance being titanium. The nickel / titanium alloy is Nitinol, which has excellent shape memory along with ductility, strength, corrosion resistance, electrical resistance, and temperature stability.

[0045] 5A[ ], the support member 50 has a proximal end that is received and secured in the connector section 30. In some embodiments, the proximal end extends to a proximal depth of about 2-3 mm from the distal end of the connector section 30. Alternatively, the support member 50 may extend further proximally through the entire length of the intermediate section 14, into the lumen 35 of the intermediate section 14, and even into the catheter body 12 via the central lumen 18, as desired or required.

[0046] Advantageously, the support member 50 has a generally rectangular cross-sectional shape, with the height and width dimensions of the cross-sectional shape varying in a predetermined manner along the length of the member 50. As shown in Figures 13B and 13C, the generally rectangular cross-sectional area at any location along the length remains constant, although its width dimension W and height dimensions vary at different locations. There is no increase or decrease in cross-sectional area at any location along the length, since any gain or loss in one dimension is proportionally gained or lost in the other dimension between more proximal and more distal locations along the length of the support member 50. The tapered portion or "tail" of the support member 50 is such that as one dimension of cross-sectional area narrows from the proximal end to the distal end of the member, the other dimension of cross-sectional area widens from the proximal end to the distal end. Decreasing a dimension (e.g., the width dimension W along the X-axis in FIGS. 13B and 13C) decreases the resistance to bending in that dimension from the proximal end to the distal end, while increasing a dimension (e.g., the height dimension H along the Y-axis in FIGS. 13B and 13C) increases the resistance to bending in the dimension from the proximal end to the distal end of the tapered portion.

[0047] As shown in FIG. 6, the generally rectangular cross-section at the proximal end of the support member 50 has a maximum width W1 and a minimum height H1. In order to minimize changes or deformations in the radii R1 and R2 during contraction of the distal assembly 17, the width and height dimensions of the cross-sectional area of the support member 50 begin to change (or taper) at a predetermined location distal of the radius R2 (e.g., at or near location L2). Distal of that predetermined location in the tapered tail of the distal assembly 17, the width begins to decrease to W2 (<W1), while the height begins to increase to H2 (>H1). The width further decreases to W3 (<W2<W1) at the distal location L3, while the height further increases to H3 (>H2>H1). These decreases and increases are smooth and continuous. This tapered configuration increases a relatively small resistance to coiling towards the distal end 25 when, for example, the support member 50 is biased and is being contracted by the contraction wire 24, while providing a gradually greater resistance to an axial force applied when the distal assembly 17 contacts the tissue surface head first. Thus, this change in cross-sectional shape enables improved contraction characteristics, including that the distal assembly 17 can easily contract and coil with minimal deformation of the elbow joint 21 at the distal portion 15, and that the elbow joint 21 is more able to withstand the load from the axial force applied when the distal assembly 17 contacts the target tissue. By this change in the cross-sectional shape applied to the support member 50, the distal assembly 17 can be adjusted to exhibit a smaller loop size (see FIG. 2B), for example, where the distal portion 15 exhibits a curvature approximately equal to or even smaller than the curvature of the distal region 21D, when the contraction wire 24 is actuated.

[0048] 6, with its generally rectangular cross-section, the support member 50 resembles a "coiled ribbon" having faces / surfaces 62 and 63 that define a height dimension of the generally rectangular cross-section, and an edge 75 that defines a width dimension of the generally rectangular cross-section. Advantageously, the inner flat face / surface 62 faces continuously along its length toward the inner circumference of the spiral helical configuration of the distal assembly, and the outer flat face / surface 63 opposite the inner flat face 62 faces continuously outwardly away from the inner circumference of the spiral helical configuration. The tapering of the support member 50 creates a "tapered tail" of the distal assembly 17 that resembles a ribbon that becomes gradually wider and thinner.

[0049] Moreover, the generally rectangular cross-section of the proximal end of the support member 50 helps to anchor the proximal end within the lumen 35 of the tube 23 of the deflectable section 14 and reduces the risk of the support member rotating about its axis if the proximal end is packed down with an adhesive such as epoxy (see FIG. 4).

[0050] In some embodiments, the support member 50 begins with a circular cross-sectional shape, as shown in FIG. 13A. The support member 50, e.g., a round wire, is gradually flattened to a tapered tail with a generally rectangular cross-section. Thus, the two opposing ends in the width dimension between the parallel flattened surfaces in the height dimension carry what remains of the original circular cross-sectional shape. It should be understood that the support member may begin with a square / rectangular cross-sectional shape that then results in flat opposing ends rather than circular opposing ends. In some embodiments, the use of a round wire makes manufacturing more economical, and the circular opposing ends facilitate assembly of the distal assembly 17, including the insertion of the support member into the radially shrinkable flexible tube or sleeve 60, as discussed further below. The circular opposing ends may also reduce the insertion force used to insert the support member 50 into the tube 60 and the risk that the support member 50 will tear and damage the tube 60.

[0051] In some embodiments, the support member 50, such as a round wire, has an initial (pre-flattened) diameter of about 0.019 inches and a length of about 4.25 inches. When flattened, the support member 50 has generally rectangular cross-sectional dimensions of about 0.021 inches by 0.015 inches from its proximal end to location L2. The tapered tail of the support member 50 (distal to location L2 in FIG. 6) is about 2.9 inches in length and has generally rectangular cross-sectional dimensions of about 0.035 inches by 0.008 inches at or near its distal end 25. In some embodiments, as described in more detail below, the distal end of the support member 50 has a non-flattened region 50D that retains its circular cross-section.

[0052] The area moment of inertia of a 0.019 inch diameter support member 50 (before flattening) is the same regardless of the centroid axis orientation, but the area moment of inertia about a first centroid axis at or near its distal end is 2.5 times stiffer than the moment of inertia at the proximal end. The area moment of inertia about a second centroid axis at the distal end is 4.5 times stiffer than the moment of inertia at the proximal end. Comparing the area moments about the two centroid axes at the distal end to each other, the first centroid axis is 18.5 times stiffer than the second centroid axis. Since the contraction wire 24 exerts a constant inward force line (neglecting friction) on the support member 50 to achieve a small, generally circular contraction, the area moment of inertia of the support member 50 should continually decrease toward the distal end when it is attached to the contraction wire 24.

[0053] The contraction wire 24 has a proximal end anchored within the control handle 16, which provides a rotatable control knob 59 (see FIG. 1) for actuating the contraction wire 24 via manipulation by an operator. The contraction wire 24 extends through the central lumen 18 (FIG. 3) of the catheter body 12, the sixth lumen 36 (FIG. 4) of the intermediate section 14, the central lumen 37 (FIG. 5A) of the connector section 30, along the support member 50, through the fourth lumen 54 (FIG. 8) of the tube 56 of the distal assembly 17 to the distal end 25 (FIG. 9).

[0054] The contraction wire 24 may be covered by friction-reducing tubing 61 (FIG. 8), such as a polyimide or PEEK tubing with a TEFLON® inner diameter coating, to physically isolate and insulate the contraction wire 24 from the sides 62 of the support member 50 and the inner surface of the shrinkable tubing 60 surrounding the contraction wire 24 and support member 50, as described in more detail below. The friction-reducing tubing 61 may have a proximal end at the connector section 30 and a distal end at or near location L2, at least distal to radius R2, provided that it is not relatively close to the distal end of the support member 50.

[0055] Advantageously, the coextensive sections of the support member 50 and the contraction wire 24 (and its tube 61) passing through the lumen 54 of the distal assembly 17 are surrounded and joined together by an interference fit flexible tube 60, as shown in FIG. 6. In some embodiments, the interference fit tube 60 has an inner diameter 91 constructed of a friction reducing material such as TEFLON® (formed as a first extruded film or layer), which is covered by a stainless steel flat braid 92, which is covered by an outer diameter 93 of nylon or the like (formed as a second extruded film or layer). The shrinkable tube 60 is slid over the support member 50 and the contraction wire 24 (with the friction reducing tube 61) after their distal ends are attached together, as described further below. The tube 60 has a distal end at or near the junction of radii R2 and R3, and a proximal end at or near the elbow junction 21. The tube 60 is fitted to provide a circumferential contraction around the support member 50 and the contraction wire 24 with the friction reducing tube 61 (see FIG. 8 ), thereby securing the tube 61 against the inner surface 62 of the support member 50 while maintaining the contraction wire 24 in alignment with (or against) the inner surface 62, resulting in improved contraction characteristics of the distal assembly 17, including improved circular shape retention and significantly tighter contraction and coiling, as well as improved resistance to the contraction wire 24 cutting into the tube 56 of the distal assembly 17. Such improved contraction characteristics, particularly for the tapered tail of the distal assembly, are possible by maintaining the contraction 24 against the inner surface 62 over the entire length of the support member 50. For example, if the radius R3 of the arc of the distal portion 15 is approximately 17 mm when the distal assembly 17 is unconstrained, then as the distal assembly 17 is contracted into a tighter coil, the distal curved portion 21D and the arc of the distal portion 15 are both defined by a radius of approximately 10 mm, whereas the radius R3 of the arc of the distal portion 15 is reduced by approximately 60% or more.

[0056] 6, the contraction wire 24 within the tube 61 runs along the entire length of the inwardly facing side 62 of the support member 50 that extends between the distal end 25 of the distal assembly 17 and the connector section 30. This predetermined pattern advantageously minimizes any tendency of the contraction wire 24 to lift away from the support member 50 as the contraction wire 24 is pulled proximally. In some embodiments, the contraction wire 24 may also have a rectangular cross-section along its length, or along one or more sections thereof.

[0057] 8 and 9, the assembled structure of support member 50, contraction wire 24, and the distal end of shrinkable tubing 60 is oriented within fourth lumen 54 of tube 56 of distal assembly 17 so that contraction wire 24 is oriented closest to the inner circumference of distal assembly 17 with contraction wire 24 pointing toward the center of distal assembly 17. With fourth lumen 54 located closer to the inner circumference than the other lumens of tube 56, and contraction wire 24 within lumen 54 also located closer to the inner circumference than support member 50, contraction wire 24 can effectively contract distal assembly 17.

[0058] Prior to insertion into lumen 54, the assembled structure of support member 50, contraction wire 24, and distal end of shrinkable tubing 60 is adjusted. In some embodiments, the connection of the distal end of contraction wire 24 to support member 50 includes a laser weld connection with a stainless steel ferrule 65 (e.g., 304 or 316 series) that is placed on distal end 25D of support member 50 that is not flattened and retains its original circular cross-sectional shape. Ferrule 65 is flattened after it is placed on distal end 25D. The flattened portion of support member 50 acts as a stop that prevents any proximal movement or displacement of ferrule 65 when contraction wire tension is applied to support member 50. Ferrule 65 is secured to circular distal end 50D of support member 50 by a crimping die that has a flat portion that is clocked parallel to surface 62 of support member 50. The distal end of the contraction wire 24 has a crimped ferrule 80 having a flat portion that is also secured to the flat portion of ferrule 65. A laser seam weld 101 is made on the common (bottom) surface of one of the ferrules 65 and 80 that joins the distal ends of the contraction wire 24 and the support member 50.

[0059] In contrast to prior art bonds for joining support members and contraction wires, in which lead-free solder is used to join the Nitinol support member to the contraction wire, the laser weld bond described herein includes the use of a strong acid flux to remove oxides from the Nitinol and stainless steel prior to soldering. Additionally, the laser weld bond provides a much stronger bond compared to prior art lead-free solders that have low shear and tensile strengths (approximately 4000 psi) that can cause the puller wire to break away from the Nitinol support member when the lead-free solder contains unexposed voids or is formed as a cold solder connection.

[0060] The shrinkable tube 60 is then slid with its proximal end over the contraction wire 24, advanced with its proximal end over the support member 50, and advanced further until the distal end of the tube 60 reaches and covers the assembled structure.

[0061] Once the shrinkable tubing 60 is properly installed over the contraction wire 24 and support member 50, the shrinkable tubing 60 has a proximal end proximate the junction of radii R2 and R3 and a distal end that is trimmed or otherwise includes a finished distal end that terminates just proximal to the stainless steel ferrule 65. The finished distal end of the shrinkable tubing 60 is then attached to the friction reducing tubing 61 and support member 50 by a circumferential application of an adhesive 111, such as LOCTITE®. In particular, the friction reducing tubing 61 surrounding the contraction wire 24 has a distal end that is sufficiently proximal to the soldered stainless steel ferrule 65 that the adhesive 101 can directly bond the distal end of the shrinkable tubing 60 to the contraction wire 24 and support member 50.

[0062] The assembled structure of contraction wire 24, support member 50, and shrinkable tube 60 is then inserted into lumen 54 where stainless steel ferrule 65 and the components it contains are secured and anchored to the distal end of multi-lumen tube 56 by adhesive 64, such as polyurethane, which covers the entire distal surface of distal end 25 to form a tip dome, as shown in FIG. 9. With this arrangement, the relative positions of contraction wire 24 and support member 50 can be controlled such that contraction wire 24 is located on or near the inner circumference of distal assembly 17, closer to the center of the spiral helix configuration, as described above. Shrinkable tube 60 protects multi-lumen tube 56 from contraction of contraction wire 24 into the sidewall of multi-lumen tube 56 during contraction of distal assembly 17.

[0063] 3 and 4, a compression coil 68 surrounding the contraction wire 24 extends from the proximal end of the catheter body 12 through the entire length of the sixth lumen 36 of the intermediate section 14. The compression coil thus has a distal end at or near the middle of the connector section 30. The compression coil 68 is made of any suitable metal, preferably stainless steel, and is tightly wound on itself to provide flexibility, i.e., bending, but resist compression. The inner diameter of the compression coil is preferably slightly larger than the diameter of the contraction wire 24. The outer surface of the compression coil is covered by a flexible, non-conductive sheath 67 made, for example, of polyimide tubing. The compression coil is preferably made of wire having a square or rectangular cross section, making it less compressible than a compression coil made from a wire having a circular cross section. As a result, the compression coil 68 keeps the catheter body 12, and especially the intermediate section 14, from deflecting as the compression coil 68 absorbs more compression when the contraction wire 24 is pulled proximally to contract the distal assembly 17.

[0064] A ring electrode 19 is mounted in place on the distal portion 15 as shown in Figures 2A and 2B. The electrode may be made of any suitable solid conductive material, such as platinum or gold, preferably a combination of platinum and iridium, or a combination of gold and platinum, and may be mounted on the tube with adhesive or the like. A preferred embodiment of an electrode suitable for ablation and irrigation is shown in Figure 10. The ablation reservoir ("AR") electrode is generally cylindrical with a length greater than its diameter. In one embodiment, it is about 3.0 mm long, has an outer diameter of about 2.8 mm, and an inner diameter of about 2.33 mm.

[0065] In some embodiments, the number of AR ring electrodes 19 on the distal assembly 17 may range from about 6 to about 20, preferably about 8 to about 12. In some embodiments, the distal assembly 17 carries 10 AR electrodes. The electrodes may be approximately evenly spaced along the distal portion 15.

[0066] The proximal end of each wire of the wire pair 40, 41 is electrically connected to a suitable connector (not shown) distal to the control handle 16. In the disclosed embodiment, the wire 40 of the pair is a same wire, such as a number "40" copper wire, and the other wire 41 of the pair is a constantan wire. The wire pair extends from the control handle 16 through the central lumen 18 of the catheter body 12 (FIG. 3), the first lumen 31 of the intermediate section 14 (FIG. 4), the central lumen 37 of the connector section 30 (FIG. 5A), and the second lumen 52 of the distal assembly 17 (FIG. 8). The distal ends of the wire pair pass through a through hole 74 (FIG. 9) formed in the side wall of the tube 56 to reach the AR electrode 19. The wires of each pair are electrically insulated from each other except at their exposed distal ends. The exposed distal end of each wire pair 40, 41 is sandblasted and then wrapped in and welded to a folded metal foil 72 (e.g., copper foil) as shown in FIG. 10, and then welded to the inner surface 70 adjacent the proximal end 71 of the AR electrode 19 of the wire pair.

[0067] Ablation energy, such as RF energy, is delivered to the AR electrodes 19 via the wire pairs 40. However, the wire pairs, including their respective constantan wires 41, may also function as temperature sensors or thermocouples to sense the temperature of the respective AR electrodes 19.

[0068] All of the wire pairs pass through a surrounding non-conductive protective sheath 39 (FIGS. 3 and 4), which may be made of any suitable material, such as polyimide. The sheath 39 extends, together with the wire pairs, from the control handle 16, through the catheter body 12, the intermediate section 14, the connector section 30, and into the second lumen 52 of the distal assembly 17, for example, about 5 mm into the second lumen 52, terminating just distal to the junction between the connector section 30 and the distal assembly 17. The distal end is anchored in the second lumen 52 by an adhesive, for example, a polyurethane adhesive.

[0069] Irrigation fluid is supplied to the distal assembly by irrigation tube 43, the proximal end of which is attached to a luer hub 73 (FIG. 1) proximal to the control handle 16 and receives fluid supplied by a pump (not shown). Irrigation tube 43 extends through the control handle 16, the central lumen 18 (FIG. 3) of the catheter body 12, the second lumen 32 (FIG. 4) of the intermediate section 14, the central lumen 37 (FIG. 5A) of the connector section 30, and a short distance, such as about 5 mm, distally into the third lumen 53 of the multi-lumen tube 56 of the assembly 17. Fluid enters the third lumen 53 and exits it through an opening (not shown) formed in the side wall of the tube 56 to the AR ring electrode 19 and out an exit opening 78 formed in the electrode side wall (FIG. 10). It should be understood that the distal portion 15 may carry any type of electrode, including the AR ring electrodes, impedance ring electrodes, and / or combinations thereof, as described above, as desired or required.

[0070] A deflection puller wire 44 is provided for deflection of the midshaft 14. The deflection wire 44 extends through the central lumen 18 (FIG. 3) of the catheter body 12 and through the third lumen 33 (FIG. 4) of the midsection 14. The deflection wire is anchored at its proximal end to the control handle 16 and at its distal end to or near the distal end of the midsection 14 by a T-bar 76 (FIG. 4) secured to the sidewall of the tube 15 by a suitable material such as polyurethane 69. The puller wire 54 is made of any suitable metal such as stainless steel or nitinol and is preferably coated, such as with TEFLON®. The coating provides lubricity to the puller wire. The puller wire 44 may have a diameter ranging from about 0.015 to about 0.025 centimeters (0.006 to about 0.010 inches).

[0071] The second compression coil 47 is within the central lumen 18 of the catheter body 12 in surrounding relationship to the puller wire 44 (FIG. 3). The second compression coil 47 extends from the proximal end of the catheter body 12 to or near the proximal end of the intermediate section 14. The second compression coil 47 is made of any suitable metal, preferably stainless steel, and is tightly wound on itself to provide flexibility, i.e., bending, but resist compression. The inner diameter of the second compression coil 47 is preferably slightly larger than the diameter of the puller wire 44. A TEFLON® coating (not shown) on the puller wire allows the puller wire to slide freely within the second compression coil. Within the catheter body 12, the outer surface of the second compression coil 47 is covered by a flexible, non-conductive sheath 49 made, for example, of polyimide tubing. A second compression coil 47 has its proximal end secured to the outer wall 20 of the catheter body 12 by a proximal bond and is secured to the intermediate section 14 by a distal bond.

[0072] Within the third lumen 33 of the intermediate section 14, the puller wire 44 extends through a plastic sheath (not shown), preferably TEFLON®, which prevents the puller wire 44 from cutting into the wall of the tube 23 of the intermediate section 14 when the intermediate section 14 is deflected.

[0073] Longitudinal movement of the contraction wire 24 relative to the catheter body 12, which effects contraction of the spiral helix configuration of the distal assembly 17, is accomplished by suitable manipulation of the control handle 16. Similarly, longitudinal movement of the deflection wire 44 relative to the catheter body 12, which effects deflection of the intermediate section 14, is accomplished by suitable manipulation of the control handle 16. Suitable control handles for manipulating two or more wires are described, for example, in U.S. Patent Nos. 6,468,260, 6,500,167, and 6,522,933, the entire disclosures of which are incorporated herein by reference.

[0074] In one embodiment, the catheter includes a control handle 16, as shown in Figures 11 and 12. The control handle 16 includes a deflection control assembly having a handle body 84 in which a core 86 is fixedly mounted, and a piston 87 slidably mounted to a distal region of the core 86. The piston 87 has a distal portion that extends outside the handle body. A thumb knob 58 is mounted to the distal portion to allow a user to more easily move the piston 87 longitudinally relative to the core 86 and the handle body 84. The proximal end of the catheter body 12 is fixedly attached to the distal end of the piston 87. An axial passage 88 is provided in the distal end of the piston 87 to allow various components extending through the catheter body 12 to enter the control handle, including the leads 40, 41, the contraction wire 24, the deflection wire 44, the position sensing cable assembly 48, and the irrigation tube 43. The leads 40, 41 may extend out of the proximal end of the control handle 16 or may be connected to connectors built into the control handle, as is generally known in the art. Irrigation tubing 43 may also extend out of the proximal end of the control 16 for connection to an irrigation source (not shown) via a luer hub.

[0075] The proximal end of the deflection wire 44 enters the control handle 16 and is wrapped around a pulley 83 and anchored to the core 86. The thumb knob 58 and piston 87 move distally longitudinally relative to the handle body 84 and core 86, thereby pulling the proximal end of the deflection wire 44 distally. As a result, the deflection wire 44 pulls on the side of the intermediate section 14 to which it is anchored, thereby deflecting the intermediate section in that direction. To release and straighten the intermediate section 14, the thumb knob 58 is moved proximally, causing the piston 87 to move proximally back to its original position relative to the handle body 84 and core 86.

[0076] The control handle 16 is also used to longitudinally move the contraction wire 24 via a rotary control assembly. In the illustrated embodiment, the rotary control assembly includes a cam handle 81 and a cam receiver 82. By rotating the cam handle in one direction, the cam receiver is pulled proximally to retract the contraction wire 24. By rotating the cam handle in the other direction, the cam receiver is advanced distally to release the contraction wire 24. The contraction wire 24 extends from the catheter body 12 through the control handle 16, through an axial passage in a piston 88, and through a core 86 that is anchored to an adjustment device 85 that can adjust the tension in the contraction wire.

[0077] In one embodiment, a position sensor cable assembly 48 including multiple single-axis sensors ("SAS") extends through a first lumen 51 (FIG. 8) of the distal assembly 17, where each SAS occupies a known or predetermined position in the spiral helix of the distal assembly 17. The cable assembly 48 extends proximally from the distal assembly 17 through a central lumen 37 of the connector section 30, a fourth lumen 34 of the intermediate section 14 (FIG. 4), a central lumen 18 of the catheter body 12 (FIG. 3), and into the control handle 16. Each SAS may be placed with a known equal spacing separating adjacent SAS. In the disclosed embodiment, the cable carries three SAS placed under the most distal AR electrode, the most proximal AR electrode, and the middle AR electrode to sense the location and / or position of the distal assembly 17. The SAS allows the spiral morphology to be viewed under mapping systems manufactured and sold by Biosense Webster, Inc., including the CARTO, CARTO XP, and NOGA mapping systems. A suitable SAS is described in U.S. Patent No. 8,792,962, the entire disclosure of which is incorporated herein by reference.

[0078] The above description is provided in relation to the presently preferred embodiment of the present invention. Those skilled in the art and technology to which the present invention pertains will recognize that modifications and variations may be made to the described configurations without significantly departing from the principles, spirit, and scope of the present invention. Any feature or configuration disclosed in one embodiment may be incorporated in place of or in addition to other features of any other embodiment, as necessary or appropriate. As will be appreciated by those skilled in the art, the drawings are not necessarily to scale. Thus, the above description should not be read in relation to the exact configurations described and illustrated in the accompanying drawings, but rather in accordance with and in support of the following claims, which are to have their fullest and fairest scope.

[0079] [Embodiment] (1) An electrophysiology catheter, comprising: An elongated catheter body; A contraction wire; a distal assembly configured to contract by actuation of the contraction wire, the distal assembly having a shape memory support member having a 3D configuration with a distal portion defined by a distal radius, the shape memory support member having a generally rectangular cross-section defined by a width and a height, the generally rectangular cross-section tapered at the distal portion such that a distal location of the distal portion has a greater height and a smaller width and a proximal location of the distal portion has a smaller height and a greater width; An electrophysiology catheter comprising: (2) An electrophysiology catheter as described in embodiment 1, wherein the support member has an inner surface facing the inner circumference of the 3D configuration, and a coextensive portion of the contraction wire extending through the distal assembly is aligned with the inner surface. (3) An electrophysiology catheter as described in embodiment 1, wherein the distal assembly includes a radially contractible sleeve surrounding the support member and a portion of the contraction wire coextensive with the support member. (4) An electrophysiology catheter as described in embodiment 1, wherein the distal assembly includes a laser welded connection of the distal end of the support member and the contraction wire, and the distal end of the support member has a cross-section different from the approximately rectangular cross-section. (5) An electrophysiological catheter as described in embodiment 1, wherein the distal assembly carries a plurality of ring electrodes.

[0080] (6) An electrophysiological catheter, comprising: An elongated catheter body; A contraction wire; a 3D arcuate distal assembly configured to be contracted by the contraction wire, the distal assembly defining an inner circumference, the distal assembly comprising: a first tube having a lumen on or near the inner circumference; an elongate support member extending through the lumen, the support member having a longitudinal planar surface; the contraction wire extends through the lumen and has a coextensive section along the planar surface of the support member; and a second tube extending through the lumen, the second tube circumferentially surrounding the support member and the coextensive section of the contraction wire; An electrophysiology catheter comprising: (7) An electrophysiology catheter as described in embodiment 6, wherein the support member and the coextensive section of the contraction wire collectively define a cross-sectional profile, and the second tube surrounds the support member and the coextensive section in a manner that generally conforms to the cross-sectional profile. (8) The electrophysiology catheter of embodiment 6, wherein the coextensive portion of the contraction wire is aligned with a flat surface of the support member, and the second tube is configured to maintain the coextensive section of the contraction wire in approximate alignment with the flat surface of the support member during contraction of the distal assembly. (9) An electrophysiological catheter as described in embodiment 6, wherein the second tube is configured to maintain the coextensive section of the contraction wire along the flat surface of the support member. (10) The electrophysiology catheter of embodiment 6, wherein the support member has a distal tail portion, the support member having a generally rectangular cross-section defined by a width and a height, the generally rectangular cross-section being tapered at the distal tail portion.

[0081] (11) The electrophysiology catheter of embodiment 10, wherein a distal location of the distal tail portion has a greater height and a smaller width, and a proximal location of the distal tail portion has a smaller height and a greater width. (12) An electrophysiological catheter, comprising: an elongate catheter body defining a longitudinal axis; A contraction wire; a 3D distal assembly movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction wire, the 3D distal assembly having an elbow junction and a distal portion, the elbow junction defined by at least a proximal diameter and the distal portion defined by a distal diameter; a 3D distal assembly, in the neutral configuration, the proximal diameter is smaller than the distal diameter, and in the contracted configuration, the distal diameter is approximately equal to or smaller than the proximal diameter; 1. An electrophysiological catheter comprising: (13) The electrophysiology catheter of claim 12, wherein the elbow junction has a torsion portion configured to support the distal portion generally transverse to the longitudinal axis, such that the longitudinal axis extends through a center of the distal portion. (14) The electrophysiology catheter of claim 12, wherein the distal assembly has an elongate support member having an inner planar surface and an opposing planar surface, and the contraction wire has a distal section coextensive with the inner planar surface along its entire length. (15) The electrophysiology catheter of embodiment 14, wherein the inner surface of the support member is on or near the inner circumference of the distal portion of the 3D distal assembly.

[0082] (16) The electrophysiology catheter of embodiment 14, wherein the distal assembly further comprises a radially contractible tube circumferentially surrounding the elongate support member and a friction reducing tube surrounding the contraction wire. (17) The electrophysiology catheter of embodiment 16, wherein the radially contractible tube is circumferentially contractible around the support member and the friction reduction tube while minimizing movement of the friction reduction tube relative to the support member. (18) An electrophysiological catheter, comprising: an elongate catheter body defining a longitudinal axis; A contraction wire; a distal assembly having a 3D arcuate configuration, the distal assembly movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction wire, the distal assembly comprising: a support member providing the 3D arcuate configuration, the 3D arcuate configuration having an elbow junction and a distal portion, the elbow junction being defined by at least a proximal diameter and the distal portion being defined by a distal diameter; a radially shrinkable tube circumferentially surrounding the support member and the coextensive portion of the contraction wire; a distal assembly, in the neutral configuration, the proximal diameter is less than the distal diameter, and in the contracted configuration, the distal diameter is reduced to a diameter approximately less than the distal diameter; 1. An electrophysiological catheter comprising: (19) The electrophysiology catheter of embodiment 18, wherein the 3D arcuate configuration defines an inner circumference, the distal assembly includes a tube having multiple lumens including a lumen closest to the inner circumference, and the support member and the contraction wire are coextensive within the lumen closest to the inner circumference. (20) The electrophysiology catheter of embodiment 19, wherein the support member has a generally rectangular cross-section, the support member has a distal portion, and the width and height dimensions of the generally rectangular cross-section vary along the length of the distal portion.

Claims

[Claim 1] 1. An electrophysiology catheter comprising: An elongated catheter body; A contraction wire; a 3D arcuate distal assembly configured to be contracted by the contraction wire, the 3D arcuate distal assembly defining an inner circumference, the 3D arcuate distal assembly having a spiral helix configuration when unconstrained; a first tube having a lumen; an elongate support member extending through the lumen, the elongate support member comprising: having a longitudinal flat surface, having a circular distal end, a distal tail portion having a generally rectangular cross-sectional shape in which height and width dimensions vary such that one dimension of a cross-sectional area of ​​the generally rectangular cross-sectional shape narrows from its proximal end to its distal end prior to the circular distal end as the other dimension of the cross-sectional area of ​​the generally rectangular cross-sectional shape widens from the proximal end to the distal end, the cross-sectional area of ​​the generally rectangular cross-sectional shape of the distal tail portion remaining constant along a length of the distal tail portion; an elongate support member, the circular distal end having a non-flattened area that maintains a circular cross-section; a second tube extending through the lumen; and Equipped with the contraction wire has a friction-reducing tube extending through the lumen and aligned with the flat surface of the elongate support member, the contraction wire having a coextensive section that defines a cross-sectional profile in cooperation with the elongate support member, and the second tube is fitted to provide a circumferential contraction around the elongate support member and the contraction wire having the friction-reducing tube, circumferentially surrounding the elongate support member and the coextensive section in substantial conformance with the cross-sectional profile, thereby maintaining the coextensive section of the contraction wire aligned with the flat surface of the elongate support member.

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