Catheter with tapered support member for variable arc distal assembly

Abstract

The invention is entitled "Catheter with tapered support member for variable arc distal assembly". A catheter with a variable circular ring in response to a shrinking wire for coiling, supported by a member with a tapered distal segment that transitions from a circular cross-section to a generally rectangular cross-section while maintaining a uniform cross-sectional area along the entire tapered length for improved coiling characteristics. A radially constricting sleeve prevents the shrinking wire from separating from the support member to minimize deformation of the ring during shrinking.

Description

Technical Field

[0001] The present invention relates generally to methods and apparatus for invasive medical treatments, and more particularly to catheters, especially catheters having distal segments suitable for mapping and / or ablation of selected anatomical structures. Background Technology

[0002] Myocardial tissue ablation is well-known as a treatment for arrhythmias. For example, in radiofrequency (RF) ablation, a catheter is inserted into the heart and brought into contact with the tissue at the target location. RF energy is then applied through electrodes on the catheter to create an ablation focus, the purpose of which is to disrupt the arrhythmogenic electrical pathways in the tissue.

[0003] Peripheral ablation of the pulmonary vein ostium is now accepted as a treatment for atrial arrhythmias, particularly atrial fibrillation. For example, U.S. Patent No. 6,064,902 describes a catheter for ablating tissue on the inner wall of a vessel such as the pulmonary vein, the disclosure of which is incorporated herein by reference. The distal portion of the catheter can be deflected from a generally straight first configuration (where the proximal and distal segments are substantially collinear) to a J-shaped second configuration (where the proximal and distal segments are generally parallel, and the spacing between them substantially corresponds to the inner diameter of the vessel). The distal portion of the catheter is rotated about the longitudinal axis of the catheter to circumferentially displace the proximal and distal ablation electrodes on the catheter along the inner wall of the pulmonary vein. Thus, the electrode catheter can be used to ablate several circumferentially spaced sites on the inner wall of the pulmonary vein by ablating one or two sites at each circumferential location.

[0004] U.S. Patent No. 6,973,339 describes a ring catheter for pulmonary vein mapping and ablation, the disclosure of which is incorporated herein by reference. The catheter for circumferential mapping of the pulmonary vein (PV) includes a curved segment shaped to conform to the shape of the inner surface of the PV. The curved segment is connected to the catheter via a generally straight axial basal segment in an “edge-on” configuration, wherein the basal axial segment is connected to the curved segment circumferentially. The curved segment includes one or more sensing electrodes, and its proximal end engages with the basal segment of the catheter at a fixed or generally known angle. Position sensors are fixed to the curved segment of the catheter and to the distal end of the basal segment. The catheter is inserted into the heart, and the curved segment is positioned to contact the wall of the PV while the basal segment remains within the left atrium, typically positioned such that the connector with the curved segment is located at the venous orifice. Information generated by the three position sensors is used to calculate the position and orientation of the sensing electrodes, enabling mapping of the surface of the PV. The sensing electrode may additionally perform ablation on the selected site, or the catheter may also include an ablation element.

[0005] U.S. Patent No. 7,008,401 describes composite steering components that can be used in both diagnostic and therapeutic applications to steer distal segments of a catheter into multiple planes or complex curves; the disclosure of that patent is incorporated herein by reference. These components reportedly enable physicians to rapidly and accurately position ablation and / or mapping electrodes and maintain close contact with internal body surfaces. Similar composite steering components are described in U.S. Patent No. 5,820,591; the disclosure of that patent is incorporated herein by reference.

[0006] U.S. Patent No. 8,608,735 describes a medical device comprising an insertion shaft having a longitudinal axis and a distal end adapted for insertion into a patient, the disclosure of which is incorporated herein by reference. A resilient distal segment is secured to the distal end of the insertion shaft and is shaped to define an arcuate orientation relative to the axis and having a center of curvature on the axis when unrestrained. One or more electrodes are disposed at corresponding locations along the distal segment.

[0007] However, due to individual variations in human anatomy, the shape and size of the mouth vary, so the arcuate distal segment may not always fit a specific target mouth. Furthermore, the same catheter may be desired for a target mouth of a certain diameter and for a PV of that mouth that may have a significantly smaller diameter. Additionally, in cases where annular catheters may have variable arcuate distal components, contraction of the arcuate distal component can deform the generally circular shape of the arcuate distal component because one or more of its components are too rigid to be wound more tightly in the desired manner.

[0008] Current annular conduits are constructed using support members with a constant, uniform cross-section, such as nitinol ridges, which cannot maintain a circular shape throughout annular contraction. The contraction and deflection characteristics of such current annular conduits are also limited, requiring more pounds of contraction line tension to reduce annular contraction. Furthermore, current annular conduits may lack a reliable attachment between the contraction line and the support member, which would eliminate the possibility of the contraction line breaking or releasing from the support member. Current annular conduits have nitinol ridges that have the same uniform area moment of inertia along their entire length and have a uniform cross-sectional area. Summary of the Invention

[0009] This invention relates to a catheter with a variable-curvature distal segment, which exhibits improved contraction and bending radius characteristics and greater durability. The variable-curvature distal segment includes a variable-tapered support member to significantly increase the degree of contraction of the generally circular catheter ring, while reducing forces on the contraction line and all other structural support portions of the ring, thus providing the catheter operator with repeatable and more realistic full contraction for circulatory diagnostic and therapeutic catheters. The variable-tapered support member also increases the stiffness of the catheter ring along the contraction axis to provide increased and more uniform contact forces between the annular electrode carried on the ring and the cardiac tissue.

[0010] In some embodiments, the conduit with a variable annulus is supported by a member having a tapered distal segment that transitions from a circular cross-section to a generally rectangular cross-section while maintaining a uniform cross-sectional area along the entire tapered length. The tapered distal segment provides a reduced moment of inertia along a first center of mass axis and an increased moment of inertia along a second center of mass axis that is generally orthogonal to the first center of mass axis. Thus, the tapered segment is biased to deflect less along the second center of mass axis with the increased moment of inertia and more along the first center of mass axis with the reduced moment of inertia.

[0011] In some embodiments, the electrophysiological catheter includes an elongated catheter body, a contraction cord, and a distal assembly configured for contraction via actuation of the contraction cord. 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 its width and height. The generally rectangular cross-section tapers in the distal portion, such that a distal position in the distal portion has a greater height and a smaller width, and a proximal position in the distal portion has a smaller height and a larger width.

[0012] In a more detailed implementation, the support member has an inner side of an inner circumference facing the 3D configuration, wherein the common extension portion of the contraction line extending through the distal component is aligned with the inner side.

[0013] In some detailed implementations, the distal component includes a radial tightening sleeve surrounding the support member and a shrinkage line that extends together with the support member.

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

[0015] In other embodiments, the electrophysiological catheter includes an elongated catheter body; a contraction cord; and a 3D arcuate distal assembly configured for contraction by the contraction cord, wherein the distal assembly defines an inner circumference and includes a first conduit having a lumen on or near the inner circumference; and an elongated support member extending through the lumen, the support member having longitudinally flattened sides. The contraction cord extends through the lumen and has a common extension section adjacent to one or more flattened side surfaces of the support member. The distal assembly also includes a sleeve circumferentially surrounding the common extension section of the support member and the contraction cord.

[0016] In some detailed implementations, the common extension section of the support member and the contraction line jointly defines the cross-sectional profile, and the sleeve surrounds the support member and the common extension section in a manner that is generally consistent with the cross-sectional profile.

[0017] In some detailed implementations, the common extension portion of the shrinkage line is aligned with the flat side of the support member and is configured to maintain the common extension section of the shrinkage line substantially aligned with the flat side during the contraction of the distal assembly.

[0018] In some detailed embodiments, the support member has a distal tail portion, wherein the support member has a generally rectangular cross-section defined by its width and height, the generally rectangular cross-section tapering in the distal tail portion.

[0019] In some detailed implementations, the distal portion of the distal tail section has a greater height and a smaller width, while the proximal portion of the distal tail section has a smaller height and a larger width.

[0020] In some embodiments, the electrophysiological catheter has an elongated catheter body defining a longitudinal axis, a contraction line, and a 3D distal assembly movable between a neutral configuration and a contraction configuration in response to longitudinal movement of the contraction line. The 3D distal assembly has a bend joint and a distal portion. The bend joint is defined at least by a proximal diameter, and the distal portion is defined by a distal diameter. For the neutral configuration, the proximal diameter is smaller than the distal diameter. For the contraction configuration, the distal diameter is approximately equal to or smaller than the proximal diameter.

[0021] In some detailed embodiments, the bend joint has a torsion portion configured to support a distal portion that is 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 component has an elongated support member having an inner flat side and an opposing flat side, and wherein the contraction line has a distal segment extending along its entire length coexisting with the inner flat side.

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

[0024] In some implementations, the distal assembly also includes a radially tightening sleeve that circumferentially surrounds both the elongated support member and the friction-reducing conduit surrounding the contraction line.

[0025] In some implementations, the radial tightening sleeve tightens circumferentially around the support member and the friction-reducing pipe to minimize lateral movement of the shrinkage line relative to the support member.

[0026] In other embodiments, the electrophysiological catheter has an elongated catheter body defining a longitudinal axis, a contraction line, and a distal assembly in a 3D arcuate form, which is movable between a neutral configuration and a contraction configuration in response to longitudinal movement of the contraction line. The distal assembly includes: a support member providing a 3D arcuate form with a bend joint and a distal portion, wherein the bend joint is defined at least by a proximal diameter and the distal portion by a distal diameter; and a radially tightening sleeve surrounding the common extension of the support member and the contraction line. For the neutral configuration, the proximal diameter is smaller than the distal diameter. For the contraction 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 the inner circumference, and the distal component includes a conduit with multiple lumens, including the lumen closest to the inner circumference, and the common extension of the support member and the contraction line is in 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, wherein the width and height dimensions of the generally rectangular cross-section vary along the length of the distal portion. Attached Figure Description

[0029] These and other features and advantages of the invention will be better understood when considered in conjunction with the accompanying drawings and by referring to the following detailed description. It should be understood that some selected structures and features are not shown in certain drawings to provide a better view of the remaining structures and features.

[0030] Figure 1 This is a top plan view of the catheter of the present invention according to one embodiment.

[0031] Figure 2A It is in a neutral, unconstrained configuration. Figure 1 Detailed 3D view of the distal component of the catheter.

[0032] Figure 2B This is a detailed view of the 3D arcuate distal component of Figure 2 in a contracted configuration.

[0033] Figure 3 This is a cross-sectional view of the end of the catheter body of Figure 1, taken along line AA.

[0034] Figure 4 It was taken from BB along the line. Figure 1 A cross-sectional view of the end of the deflectable intermediate segment of the catheter.

[0035] Figure 5A It is a cut along the CC line. Figure 1 A cross-sectional view of the end of the connector segment of the conduit.

[0036] Figure 5B It is extracted along region DD. Figure 1 A side sectional view of the connector segment.

[0037] Figure 6A It is a perspective view of the supporting components, the co-extension contraction line, and the radial tightening pipe.

[0038] Figure 6B yes Figure 6A A detailed top view of the assembly structure of the supporting members and the distal end of the contraction line.

[0039] Figure 7 yes Figure 1 The end view of the far-side component.

[0040] Figure 8 It is the section taken from EE along the line. Figure 2A End section view of the distal component.

[0041] Figure 9 It is a cut along line FF. Figure 2A A side sectional view of the distal component.

[0042] Figure 10 This is a perspective view of a flushing ablation electrode with a guide wire attachment according to one embodiment.

[0043] Figure 11 This is a side sectional view of the control handle according to one implementation scheme.

[0044] Figure 12 yes Figure 11 A partial top sectional view of the control handle.

[0045] Figure 13A This is an end sectional view of the support member in Figure 6 before reforming.

[0046] Figure 13B This is a cross-sectional view of the end of the support member in Figure 6, taken along line GG.

[0047] Figure 13C This is a cross-sectional view of the end of the support member in Figure 6, taken along line JJ. Detailed Implementation

[0048] The embodiments of the invention described below provide probes, such as catheters, with an improved arcuate distal electrode-bearing structure to facilitate manipulation and positioning within tubular regions of varying sizes and at different circumferential locations within those regions, particularly in the patient's body. Such catheters can be used to generate generally circular or spiral ablation paths, and to sense electrical activity along generally curved or spiral patterns for potential and anatomical mapping.

[0049] See Figure 1 According to the disclosed embodiment, the catheter 10 includes: an elongated body, which may include a flexible insertion shaft or catheter body 12 having a longitudinal axis 13; and an intermediate segment 14 distal to the catheter body, the intermediate segment 14 being deflectable unidirectionally or bidirectionally from the longitudinal axis 13. Figure 2A As shown, a resilient three-dimensional (3D) arcuate distal assembly 17 extends from the intermediate segment 14. The distal assembly 17 is advantageously configured for significantly larger and more uniform ring contraction. As explained in further detail below, the distal assembly 17 reduces its radius and increases its winding in response to operator manipulation of the control handle 16, such as... Figure 2B As shown.

[0050] exist Figure 1 and Figure 3 In the illustrated embodiment, the catheter body 12 comprises an elongated tubular structure having a single axial or central lumen 18. The catheter body 12 is flexible, bendable, but substantially incompressible along its length. The catheter body 12 can have any suitable construction and can be made of any suitable material. In some embodiments, the construction includes an outer wall 20 made of polyurethane or PEBAX. As is generally known in the art, the outer wall 20 comprises an embedded braided mesh of stainless steel, etc., to increase the torsional stiffness of the catheter body 12 such that when the control handle 16 is rotated, the intermediate segment 14 will rotate accordingly.

[0051] The outer diameter of the catheter body 12 is not a decisive factor, but in some embodiments it is no greater than about 8 Frenchies, more preferably 7 Frenchies. Similarly, the thickness of the outer wall 20 is not a decisive factor, but it is thin enough that the central lumen 18 can accommodate any desired wire, cable, and / or tube. The inner surface of the outer wall 20 is lined with a stiffening tube 22 to provide improved torsional stability. The outer diameter of the stiffening tube 22 is approximately 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, which provides very good stiffness and does not soften at body temperature.

[0052] The deflectable intermediate segment 14 includes a shorter segment of conduit 23 having multiple lumens, each lumen occupied by various components from the conduit 12 and entering the intermediate segment 14. Figure 4 In the illustrated embodiment, six lumens are provided. Coupled to the annular electrode 19, corresponding guide wire / thermocouple pairs 40, 41 pass through the first lumen 31. A non-conductive sheath 39 may be provided to surround the wire pairs 40 / 41. A flushing conduit 43 for delivering flushing fluid to the distal assembly 17 passes through the second lumen 32. A deflection pull wire 44 passes through the third lumen 33 to enable deflection of the intermediate segment 14. A position sensor cable assembly 48, including one or more uniaxial sensors (SAS) carried in the distal assembly 17, passes through the fourth lumen 34. A retractable wire 24 passes through the sixth lumen 36 to allow the shape and dimensions, such as the radius of curvature, of the arcuate distal portion 15 of the distal assembly 17 to be variable in response to user manipulation of the control handle. As described below, the retractable wire 24 acts on a shape memory support member 50 that provides the 3D shape of the distal assembly 17.

[0053] The multi-lumen conduit 23 of the intermediate segment 14 is preferably made of a suitable, non-toxic material that is more flexible than the conduit body 12. Suitable materials are braided polyurethane or PEBAX, i.e., polyurethane or PEBAX with an embedded braided mesh such as stainless steel. The number and size of the lumens are not decisive factors, provided there is sufficient space to accommodate the relevant components. In the illustrated embodiment, the third and sixth lumens 33 and 36 for deflecting the pull wire 44 and the contraction wire 24 are off-axis and diametrically opposed to each other, and the fifth lumen 35 for supporting the member 50 is axial.

[0054] The usable length of the catheter, i.e. the portion that can be inserted into the body excluding the distal component 17, can vary as needed. Preferably, the usable length is in the range of about 110 cm to about 120 cm. The length of the intermediate segment 14 is a relatively small portion of the usable length, and is preferably in the range of about 3.5 cm to about 10 cm, more preferably in the range of about 5 cm to about 6.5 cm.

[0055] The distal component 17 is located distal to the intermediate segment 14. For example... Figure 2A and Figure 5A As shown, a generally straight connector segment 30 extends between the intermediate segment 14 and the distal assembly 17. The connector segment 30 has a conduit made of a suitable material, such as PEEK, with a central lumen 37. The central lumen 37 allows various components extending between the intermediate segment 14 and the distal assembly 17 to be reoriented and repositioned as needed for transition between the intermediate segment 14 and the distal assembly 17, such as... Figure 5B As shown. The component is encapsulated in the lumen 37 of segment 30 by a suitable adhesive 112. Supporting the distal assembly 17 and providing its 3D dimensional shape, shape memory support member 50 extends a relatively short distance from the distal assembly 17 toward the proximal side into the distal portion of connector segment 30.

[0056] like Figure 2A As shown in Figure 6, the 3D distal assembly 17 includes a pre-formed arcuate distal portion 15, a bent portion 21, and a proximal linear rod 26. The arcuate distal portion 15 carries a plurality of flushing annular electrodes 19. The bent portion 21 is configured such that the distal portion 15 is oriented obliquely relative to the longitudinal axis 13, such that the longitudinal axis extends substantially through the center of the distal portion 15, as shown in Figure 6. Figure 7 As shown. Therefore, the tilt angle θ ( Figure 2A The inclination angle θ is defined between the longitudinal axis 13 and the plane P defined generally by the distal component 17, wherein the inclination angle θ ranges between about 45 degrees and 135 degrees, preferably between about 75 degrees and 100 degrees, and preferably about 90 degrees.

[0057] refer to Figure 2A Figure 6 and Figure 7 The bend portion 21 has a proximal bend segment 21P, a bend joint or "torsion" 42, and a distal bend segment 21D. The proximal bend segment 21P depicts a first arc defined by a first (or proximal) radius R1 relative to the longitudinal axis 13. The distal bend segment 21D depicts a second arc defined by a second (or intermediate) radius R2 relative to an axis 27 inclined to the longitudinal axis 13. The first radius R1 is smaller than the second radius R2. However, both radii R1 and R2 are smaller than the third (or distal) radius R3 defining the third arc depicted by the distal portion 15. In some embodiments, the radius R1 ranges between about 0.1″ and 0.25″, the radius R2 ranges between about 0.15″ and 0.38″, and the radius R3 ranges between about 0.4″ and 0.6″. Thus, when unconstrained, the 3D configuration of the distal assembly 17 has helical characteristics, wherein the radius R3 is larger than the radius R2. For example, with an inclination angle θ of approximately 90 degrees and the longitudinal axis 13 defining the Z-axis, the first arc defined by radius R1 may lie in the Y / Z plane, and the second and third arcs defined by radii R2 and R3, respectively, may both lie in the X / Y plane, as shown in Figure 6. It should be understood that the distal component 17 is not limited to the aforementioned radii R1, R2, and R3, and may include more or fewer radii as needed or desired.

[0058] When unconstrained, the 3D configuration of the distal component 17 also exhibits helical characteristics because the distal component 17 extends distally as it forms a helix, making the distal end 25 of the distal component 17 the farthest part of the distal component 17, such as... Figure 2A The best result is shown in the middle.

[0059] Therefore, the distal assembly 17 has a helical-spiral configuration (or a spiral-helical configuration) such that a first separation gap along the longitudinal axis 13 exists between the distal end 25 and the distal curved segment 21D, and a second separation gap along the inclined axis 27 exists between the distal end 25 and the distal curved segment 21D. The helical-spiral configuration of the distal assembly 17 can be described as depicting an enlarged helix from its proximal end to its distal end, the enlarged helix being aligned with the longitudinal axis, such as... Figure 2A As shown.

[0060] Depending on the length of the distal portion 15, the distal assembly 17, in its neutral and unconstrained 3D configuration, can be oriented at a radial angle α of approximately 360 degrees between the torsion portion 42 and the distal end 25. In another embodiment, the distal assembly 17 is oriented at a radial angle α greater than 360 degrees, for example, approximately 380 degrees (Figure 6). Figure 2B As shown, when the distal assembly 17 contracts, the helical form “rolls up” and tightens, wherein one or more radii R1, R2, R3 depicted by the distal assembly 17 decrease, and the radial angle α of the distal assembly 17 facing each other between the torsion portion 42 and the distal end 25 increases from, for example, about 360 or 380 degrees to about 540 degrees or greater. Therefore, the distal assembly 17 in its neutral, unconstrained configuration can be used for circumferential contact with an opening having a larger radius, and is then adjusted to its contracted configuration for circumferential contact within the PV of an opening having a significantly smaller radius.

[0061] like Figure 8 As shown, the distal assembly 17 includes a multi-lumen conduit 56. In the disclosed embodiment, the conduit 56 has four off-axis lumens, namely, a first lumen 51 for the SAS cable assembly 48 (which is coated with a friction-reducing coating 38, for example...). The multi-lumen conduit 56 consists of a second lumen 52 for the annular electrode wire pairs 40 and 41 (circumferentially surrounding the conduit), a third lumen 53 for the flushing fluid delivered via the flushing conduit 43, and a fourth lumen 54 for the support member 50 and the contraction wire 24, a section of the contraction wire 24 extending co-existing with the support member 50 within the lumen 54. Again, the location and size of the lumens are not decisive factors, except that the fourth lumen 54 for the contraction wire 24 is preferably located on or near the inner circumference of the spiral-helix form of the distal assembly 17, so that proximal movement of the wire 24 can be more effectively used to tighten the spiral-helix form and increase its winding. The multi-lumen conduit 56 can be made of any suitable material, and is preferably made of biocompatible plastics such as polyurethane or PEBAX.

[0062] In the illustrated embodiment, the pre-formed support member 50 of the distal assembly 17 extends through the fourth lumen 54 of the conduit 56 to provide and define a 3D helical shape of the distal assembly 17, the 3D helical shape including a twist 42 and an arc between the proximal segment 21P and the distal segment 21D, and a distal portion 15 defined by radii R1, R2, and R3. The support member 50 is made of a material with shape memory (i.e., the ability to straighten or bend from its initial shape when a force is applied and to substantially return to its initial shape after the force is removed). In some embodiments, the material suitable for the support member 50 is a nickel / titanium alloy. Such alloys typically comprise about 55% nickel and 45% titanium, but may also contain about 54% to about 57% nickel, with the remainder being titanium. One nickel / titanium alloy is nitinol, which has excellent shape memory properties as well as ductility, strength, corrosion resistance, resistivity, and temperature stability.

[0063] In some implementation schemes, such as Figure 5A As shown, the support member 50 has a proximal end that receives and attaches to the connector segment 30. In some embodiments, the proximal end extends approximately 2-3 mm proximal to the distal end of the connector segment 30. Alternatively, the support member 50 may extend further proximally into the lumen 35 of the intermediate segment 14, through the entire length of the intermediate segment 14, or even through the central lumen 18 into the catheter body 12, as needed or as appropriate.

[0064] Advantageously, the support member 50 has a generally rectangular cross-sectional shape, the height and width of which vary along the length of the member 50 in a predetermined manner. For example... Figure 13B and Figure 13C As shown, the roughly rectangular cross-sectional area remains constant at any location along the length, but its width dimension W and height dimension vary at different locations. The cross-sectional area at any location along the length does not decrease or increase because any loss or increase in one dimension is proportionally increased or lost by another dimension along the length of the support member 50 between the proximal and distal locations. While the tapering portion or "tail" of the support member 50 narrows in one dimension of the cross-sectional area from the proximal end to the distal end of the member, the other dimension of the cross-sectional area widens from the proximal end to the distal end. The reduced dimension (e.g., Figure 13B and Figure 13C The width dimension W along the X-axis in the middle reduces its resistance to bending from the proximal end to the distal end in that dimension, while the increased dimension (e.g., Figure 13B and Figure 13C The height dimension H along the Y-axis increases its resistance to bending from the proximal end to the distal end of the tapered portion.

[0065] As shown in Figure 6, the support member 50 has a generally rectangular cross-section with a maximum width W1 and a minimum height H1 at its proximal end. To minimize the change or deformation of radii R1 and R2 during the 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 to radius R2 (e.g., at or near location L2). At the distal end of the predetermined location, in the tapering tail of the distal assembly 17, the width begins to decrease to W2 (< W1) as the height begins to increase to H2 (> H1). When the height at the distal location L3 further increases to H3 (> H2 > H1), the width further decreases to W3 (< W2 < W1). These decreases and increases are smooth and continuous. This tapered configuration biases the support member 50 to provide, for example, decreasing resistance to winding toward the distal end 25 as it contracts by the contraction line 24, while providing increasing resistance to tilting forces toward the distal end 25 as the distal assembly 17 comes into contact with the tissue surface. Therefore, this varied cross-sectional shape allows the distal assembly 17 to exhibit improved contraction characteristics, including the ability of the distal portion 15 to easily contract and wind, with minimal deformation of the bend joint 21 and better ability to withstand loads from axial forces applied when the distal assembly 17 contacts the target tissue. Utilizing this varied cross-sectional shape applied to the support member 50, the distal assembly 17 can be adjusted to present a smaller loop size when the contraction line 24 is actuated (see...). Figure 2B For example, the distal portion 15 exhibits a curvature that is approximately equal to or even less than that of the distal segment 21D.

[0066] As shown in Figure 6, in the case of a generally rectangular cross-section, the support member 50 resembles a “wounded strip” having side surfaces 62 and 63 defining the height dimension of the generally rectangular cross-section, and an edge 75 defining the width dimension of the generally rectangular cross-section. Advantageously, the inner flat side surface 62 faces continuously along its length toward the inner circumference of the spiral-helical configuration of the distal assembly, and the outer flat side surface 63, opposite the inner flat surface 62, faces continuously outward, away from the inner circumference of the spiral-helical configuration. The taper of the support member 50 results in the “tapered tail” of the distal assembly 17 resembling a strip that becomes increasingly wider and thinner.

[0067] Furthermore, the generally rectangular cross-section at the proximal end of the support member 50 helps to anchor the proximal end within the lumen 35 of the pipe 23 of the deflectable segment 14 and reduces the risk of the support member rotating about its axis, wherein the proximal end is encapsulated by an adhesive such as epoxy resin (see [link to documentation]). Figure 4 ).

[0068] In some implementations, the support member 50 begins with a circular cross-sectional shape, such as... Figure 13A As shown. The support member 50, for example, is a circular line that gradually flattens to produce a generally rectangular cross-section and a tapering tail. Thus, the two opposite ends, with a width dimension, between the parallel flattened surfaces having a height dimension, carry the residual circular shape of the original circular cross-section shape. It should be understood that the support member can begin with a square / rectangular cross-section shape, which then results in flattened opposite ends rather than circular opposite ends. In some embodiments, the use of a circular line is more economical to manufacture, and the circular opposite ends facilitate assembly of the distal assembly 17, including inserting the support member into a radially tightened flexible conduit or sleeve 60, as discussed further below. The circular opposite ends reduce the insertion force required to insert the support member 50 into the conduit 60 and also reduce the risk of the support member 50 tearing and damaging the conduit 60.

[0069] In some embodiments, the support member 50, which is a circular line, 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 a generally rectangular cross-sectional dimension of about 0.021″ × 0.015″ from its proximal end to location L2. The tapered tail of the support member 50 (far side of location L2 in FIG. 6) is about 2.9 inches long and has a generally rectangular cross-sectional dimension of about 0.035″ × 0.008″ at or near its distal end 25. In some embodiments, the distal end of the support member 50 has an unflattened segment 50D that maintains its circular cross-section, as explained in more detail below.

[0070] Regardless of the orientation of the center of mass axis, the area moment of inertia (pre-flattened) of the 0.019-inch diameter support member 50 is the same. However, for the first center of mass axis, the area moment of inertia at or near the distal end of the support member 50 is 2.5 times less stiff than the moment of inertia at the proximal end. The moment of inertia of the second center of mass axis at the distal end is 4.5 times more stiff than the moment of inertia at the proximal end. Comparing the area moments of inertia of the two center of mass axes at their distal ends, the first center of mass axis is 18.5 times less stiff than the second center of mass axis. Since the contraction line 24 exerts a constant inward force line (ignoring friction) on the support member 50, in order to obtain a small, approximately circular contraction, the area moment of inertia of the support member 50 should continuously decrease toward its distal end attached to the contraction line 24.

[0071] The retractable cable 24 has a proximal end anchored in the control handle 16, the proximal end providing a rotary control knob 59 for actuating the retractable cable 24 via operator manipulation (see...). Figure 1 The contraction line 24 passes through the central lumen 18 of the catheter body 12. Figure 3 ), the sixth lumen 36 of the intermediate segment 14 ( Figure 4 ), connector segment 30 center lumen 37 ( Figure 5A ) and the fourth cavity 54 of the conduit 56 of the distal assembly 17 parallel to the support member 50. Figure 8 ) extends to the distal end 25 ( Figure 9 ).

[0072] The contraction line 24 can be made by friction reduction pipe 61 ( Figure 8 For example, polyimide or PEEK pipes The coated inner diameter cover physically separates and isolates the shrink line 24 from the side 62 of the support member 50 and the inner surface of the tightening conduit 60 surrounding the shrink line 24 and the support member 50, as will be described in more detail below. If not closer to the distal end of the support member 50, the friction-reducing conduit 61 may have a proximal end in the connector segment 30 and at least a distal end at the radius R2 in or near position L2.

[0073] Advantageously, the common extension section of the support member 50 passing through the lumen 54 of the distal assembly 17 and the contraction line 24 (and its conduit 61) is surrounded and bound together by a tightly fitted flexible conduit 60, as shown in FIG6. In some embodiments, the tightly fitted conduit 60 has a friction-reducing material such as An inner diameter 91 (formed as a first extruded coating or layer) is formed, covered by a stainless steel flat braid 92, which is covered by an outer diameter 93 such as nylon (formed as a second extruded coating or layer). As further described below, the tightening conduit 60 slides over the support member 50 and the shrink line 24 (and its friction-reducing conduit 61) after the distal ends of the support member 50 and the shrink line 24 are attached together. The conduit 60 has a distal end at or near the junction of radii R2 and R3, and a proximal end at or near the bend junction 21. The conduit 60 is adapted to provide circumferential tightening around the member 50, the shrink line 24, and its friction-reducing conduit 61 (see...). Figure 8The conduit 61 is secured against the inner side 62 of the support member 50, thereby keeping the shrink line 24 aligned with (or on the side of) the inner side 62. This improves the shrinkage characteristics of the distal assembly 17, including improved roundness maintenance and significantly tighter shrinkage and coiling, as well as improved durability relative to the shrink line 24 cut into the conduit 56 of the distal assembly 17. Such improved shrinkage characteristics, particularly the tapered tail of the distal assembly, are achieved by keeping the shrink line 24 against the inner side 62 throughout the entire length of the support member 50. For example, when the radius R3 of the arc of the distal portion 15 is approximately 17 mm when the distal assembly 17 is unconstrained, the distal assembly 17 can shrink into a tighter coil such that both the distal bend 21D and the arc of the distal portion 15 are defined by a radius of approximately 10 mm, thereby reducing the radius R3 of the arc of the distal portion 15 by approximately 60% or more.

[0074] As shown in Figure 6, the shrink line 24 extends within its conduit 61 along the entire length of the inward-facing side 62 of the support member 50, which extends between the distal end 25 of the distal assembly 17 and the connector segment 30. This predetermined pattern advantageously minimizes any tendency for the shrink line 24 to separate from and lift from the support member 50 when it is pulled proximally. In some embodiments, the shrink line 24 may also have a rectangular cross-section along its length or along one or more segments thereof.

[0075] refer to Figure 8 and Figure 9 The assembly structure of the support member 50, the contraction line 24, and the distal end of the tightening pipe 60 is oriented within the fourth cavity 54 of the pipe 56 of the distal assembly 17, such that the contraction line 24 is closest to the inner circumference of the distal assembly 17 and faces the center of the distal assembly 17. With the fourth cavity 54 positioned closer to the inner circumference than the other cavities of the pipe 56, and the contraction line 24 within the cavity 54 also positioned closer to the inner circumference than the support member 50, the contraction line 24 can effectively contract the distal assembly 17.

[0076] Before insertion into lumen 54, an assembly structure is prepared for the support member 50, the shrink line 24, and the distal end of the tightening tube 60. In some embodiments, the coupling of the shrink line 24 and the distal end of the support member 50 includes a laser-welded coupling with a stainless steel ferrule 65 (e.g., 304 or 316 series) placed on the distal end 25D of the support member 50, which is not flattened but retains its original circular cross-sectional shape. The ferrule 65 is flattened after it is placed on the distal end 25D. The flattened portion of the support member 50 acts as a stop that prevents any proximal migration or misalignment of the ferrule 65 when shrink line tension is applied to the support member 50. The ferrule 65 is secured to the circular distal end 50D of the support member 50 by a crimping die having a flattened portion parallel to the surface 62 of the support member 50. The distal end of the shrink line 24 has a crimping collar 80, which has a flat portion that is also fixed to a flat portion of the collar 65. A laser seam weld 10l is formed on a common (bottom) side of the collars 65 and 80, thereby joining the distal ends of the shrink line 24 and the support member 50.

[0077] In contrast to existing coupling techniques that use lead-free solder to join nitinol support members to shrinkage lines, the laser welding coupling described herein involves using a strongly acidic flux to remove oxides from both the nitinol and stainless steel prior to welding. Furthermore, laser welding coupling provides a much stronger attachment compared to existing lead-free solders with low shear and low tensile strength (approximately 4000 psi), where the low shear and low tensile strength can be attributed to pull wire detachment failures from the nitinol support member when the lead-free solder contains unexposed voids or forms cold solder joints.

[0078] Then, the tightening pipe 60 slides over the contraction line 24 at its proximal end, advances on the support member 50 at its proximal end, and advances further until the distal end of the pipe 60 reaches and covers the assembly structure.

[0079] When the tightening conduit 60 has been properly positioned on the shrink line 24 and the support member 50, the tightening conduit 60 has a proximal end near the junction of radii R2 and R3, and its distal end is trimmed or otherwise provided with a completed distal end that terminates proximal to the stainless steel collar 65. Then, by applying adhesive 111 circumferentially, for example... The completed distal end of the tightening conduit 60 is attached to the friction-reducing conduit 61 and the support member 50. Notably, the friction-reducing conduit 61 surrounding the shrink line 24 has a distal end very close to the welded stainless steel collar 65, allowing the adhesive 101 to directly bond the distal end of the tightening conduit 60 to the shrink line 24 and the support member 50.

[0080] The assembly of the shrink line 24, support member 50, and tightening pipe 60 is then inserted into the lumen 54, wherein the stainless steel collar 65 and its contained components are secured and anchored to the distal end of the multi-lumen pipe 56 by an adhesive 64, such as polyurethane, wherein the adhesive 64 covers the entire distal side of the distal end 25 to form an end dome, as shown. Figure 9 As shown. This arrangement allows control over the relative positions of the contraction line 24 and the support member 50, such that the contraction line 24 is positioned, as described above, on or near the inner circumference of the distal assembly 17, closer to the center of the helical-spiral configuration. The tightening conduit 60 protects the multi-lumen conduit 56 from the effects of the contraction line 24 cutting into its sidewalls during the contraction of the distal assembly 17.

[0081] refer to Figure 3 and Figure 4 A compression coil 68 surrounding the contraction line 24 extends from the proximal end of the catheter body 12 and through the entire length of the sixth lumen 36 of the intermediate segment 14. Thus, the compression coil has a distal end located at or near the intermediate position in the connector segment 30. The compression coil 68 is made of any suitable metal, preferably stainless steel, and is tightly wound around itself to provide flexibility, i.e., bending, but resistance to compression. The inner diameter of the compression coil is preferably slightly larger than the diameter of the contraction line 24. The outer surface of the compression coil is covered by a flexible, non-conductive sheath 67 (e.g., made of polyimide tubing). The compression coil is preferably formed of wire with a square or rectangular cross-sectional area, which makes it less compressible than a compression coil formed of wire with a circular cross-sectional area. Therefore, the compression coil 68 prevents the catheter body 12, especially the intermediate segment 14, from deflecting when the contraction line 24 is pulled proximally to contract the distal assembly 17, because the compression coil 68 absorbs more compression.

[0082] The annular electrode 19 is mounted at a predetermined position on the distal portion 15, such as... Figure 2A and Figure 2B As shown. The electrode can be made of any suitable solid conductive material, such as platinum or gold, preferably a combination of platinum and iridium or gold and platinum, and can be mounted to the pipe using adhesives or the like. Suitable embodiments of electrodes suitable for ablation and flushing are shown in Figure 10 The ablation reservoir (“AR”) electrode is generally cylindrical with a length greater than its diameter. In one embodiment, the length is about 3.0 mm, the outer diameter is about 2.8 mm, and the inner diameter is about 2.33 mm.

[0083] In some embodiments, the plurality of AR ring electrodes 19 on the distal component 17 may range from about six to about twenty, more preferably from about eight to about twelve. In some embodiments, the distal component 17 carries ten AR electrodes. The electrodes may be spaced substantially evenly along the distal portion 15.

[0084] The proximal end of each wire in wire pairs 40 and 41 is electrically connected to a suitable connector (not shown) distal to the control handle 16. In the disclosed embodiment, wire 40 of the wire pair is copper wire, such as the copper wire of the number "40", while the other wire 41 of the wire pair is constantan wire. The wire pairs extend from the control handle 16 through the central lumen 18 of the catheter body 12. Figure 3 ), the first lumen 31 of the intermediate segment 14 ( Figure 4 ), connector segment 30 center lumen 37 ( Figure 5A ) and the second lumen 52 of the distal assembly 17 ( Figure 8 The distal end of the wire pair passes through a hole 74 formed in the sidewall of the conduit 56. Figure 9 To reach AR electrode 19. Each pair of wires is electrically insulated from each other except at the exposed distal ends. The exposed distal ends of the corresponding wire pairs 40, 41 are sandblasted, wrapped in a folded metal foil 72 (e.g., copper foil), and soldered thereto. The folded metal foil 72 is then soldered to the inner surface 70 near the proximal end 71 of its AR electrode 19, as shown. Figure 10 As shown.

[0085] Ablation energy, such as radio frequency energy, is delivered to the AR electrode 19 via the wires 40 of the wire pair. However, the wire pair, including their corresponding constantan wires 41, can also be used as a temperature sensor or thermocouple to sense the temperature of each AR electrode 19.

[0086] All wire pairs pass through a non-conductive protective sleeve 39 ( Figure 3 and Figure 4 The protective sleeve 39 can be made of any suitable material, such as polyimide, that surrounds it. The sleeve 39, together with the wire pair, extends from the control handle 16, the conduit body 12, the intermediate segment 14, the connector segment 30, and into the second lumen 52 of the distal assembly 17, for example, extending approximately 5 mm into the second lumen 52, terminating distal to the junction between the connector segment 30 and the distal assembly 17. The distal end is anchored in the second lumen 52 by an adhesive, such as polyurethane adhesive.

[0087] Flushing fluid is delivered to the distal assembly via flushing conduit 43, the proximal end of which is attached to the Luer hub 73 proximal to the control handle 16. Figure 1 It also receives fluid delivered by a pump (not shown). The flushing conduit 43 extends through the control handle 16 and the central lumen 18 of the conduit body 12. Figure 3 ), the second lumen 32 of the intermediate segment 14 ( Figure 4 ), connector segment 30 center lumen 37 ( Figure 5A ), and a short distance, for example, about 5 mm, in the third lumen 53 of the multi-lumen conduit 56 extending distally into the distal assembly 17. Fluid enters the third lumen 53, where it exits via an opening (not shown) formed in the sidewall of the conduit 56 to enter the AR annular electrode 19 and exit through an opening 78 formed in the electrode sidewall ( Figure 10 It should be understood that the distal portion 15 may carry any form of electrode as needed or suitably, including the aforementioned AR ring electrode, impedance ring electrode, and / or combinations thereof.

[0088] A deflection traction wire 44 is provided for the deflection of the intermediate shaft 14. The deflection wire 44 extends through the central lumen 18 of the catheter body 12. Figure 3 ) and the third lumen 33 of the intermediate segment 14 ( Figure 4 The deflection line is anchored in the control handle 16 at its proximal end and passes through a T-bar 76 at its distal end. Figure 4 Anchored at or near the distal end of intermediate segment 14, the T-shaped rod 76 is attached to the sidewall of pipe 15 by a suitable material such as polyurethane 69. The pull wire 54 is made of any suitable metal such as stainless steel or nitinol, and preferably coated with... The coating imparts lubricity to the pull wire. The pull wire 44 may have a diameter ranging from about 0.006 inches to about 0.010 inches.

[0089] The second compression coil 47 is located within the central lumen 18 of the catheter body 12, which is surrounded by the traction wire 44. Figure 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 segment 14. The second compression coil 47 is made of any suitable metal, preferably stainless steel, and is tightly wound around itself to provide flexibility, i.e., bending, but resistance to compression. The inner diameter of the second compression coil 47 is preferably slightly larger than the diameter of the pull wire 44. A coating (not shown) allows it 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, for example, made of polyimide tubing. The proximal end of the second compression coil 47 is anchored to the outer wall 20 of the catheter body 12 via a proximal adhesive joint and to the intermediate segment 14 via a distal adhesive joint.

[0090] Within the third lumen 33 of the intermediate segment 14, the pull wire 44 extends through, preferably... A plastic sheath (not shown) is provided to prevent the pull wire 44 from cutting into the wall of the pipe 23 of the intermediate section 14 when the intermediate section 14 deflects.

[0091] The longitudinal movement of the contraction line 24, which causes the distal assembly 17 to contract in a helical manner, relative to the catheter body 12 is accomplished by appropriate manipulation of the control handle 16. Similarly, the longitudinal movement of the deflection line 44, which deflects the intermediate segment 14, relative to the catheter body 12, is accomplished by appropriate manipulation of the control handle 16. Suitable control handles for manipulating more than one line are described in the following patents: for example, U.S. Patent Nos. 6,468,260, 6,500,167, and 6,522,933, the entire disclosure of which is incorporated herein by reference.

[0092] In one embodiment, the catheter includes a control handle 16, such as Figure 11 and Figure 12 As shown in the diagram. 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 is slidably mounted on a distal region of the core 86. The piston 87 has a distal portion extending to the outside of the handle body. A thumb knob 58 is mounted on the distal portion, allowing the user to more easily move the piston 87 longitudinally relative to the core 86 and the handle body 84. The proximal end of the conduit body 12 is fixedly mounted to the distal end of the piston 87. An axial channel 88 is provided at the distal end of the piston 87, allowing access to the control handle for multiple components including guide lines 40, 41 extending through the conduit body 12, a retraction line 24, a deflection line 44, a position sensor cable assembly 48, and a flushing conduit 43. The guide lines 40, 41 may extend beyond the proximal end of the control handle 16 or may be connected to a connector incorporated into the control handle, as is well known in the art. The flushing conduit 43 may also extend from the proximal end of the controller 16 to connect to a flushing source (not shown) via a Luer hub.

[0093] The proximal end of the deflection line 44 enters the control handle 16 and is wrapped around the pulley 83 and anchored to the core 86. The longitudinal movement of the thumb knob 58 and piston 87 relative to the handle body 84 and core 86 pulls the proximal end of the deflection line 44 distally. Thus, the deflection line is pulled on one side of the anchored intermediate segment 14 of the deflection line 44, thereby deflecting the intermediate segment in that direction. To release and straighten the intermediate segment 14, the thumb knob 58 moves proximally, causing the piston 87 to move proximally back to its initial position relative to the handle body 84 and core 86.

[0094] The control handle 16 is also used to move the shrink line 24 longitudinally 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 pull the shrink line 24. By rotating the cam handle in another direction, the cam receiver is advanced distally to release the shrink line 24. The shrink line 24 extends from the guide body 12 into the control handle 16 through an axial channel in the piston 88 and through a core 86 to be anchored in an adjuster 85, by which the tension on the shrink line can be adjusted.

[0095] In one embodiment, a position sensor cable assembly 48 including multiple uniaxial sensors (“SAS”) extends through a first lumen 51 of the distal assembly 17. Figure 8 Each SAS occupies a known or predetermined position in the helical form of the distal assembly 17. The cable assembly 48 extends from the distal assembly 17 toward the proximal side through the central lumen 37 of the connector segment 30 and the fourth lumen 34 of the intermediate segment 14. Figure 4 ), the central lumen 18 of the catheter body 12 ( Figure 3 And enters control handle 16. Each SAS can be positioned with a known and equal spacing separating adjacent SAS. In the embodiments disclosed in this invention, the cable carries three SAS positioned below the farthest AR electrode, the nearest AR electrode, and the intermediate AR electrode for sensing the positioning and / or location of the distal component 17. The SAS allows the helical configuration to be viewed under mapping systems manufactured and sold by Biosense Webster, Inc., including CARTO, CARTO XP, and NOGA mapping systems. Suitable SAS are described in U.S. Patent No. 8,792,962, the entire disclosure of which is incorporated herein by reference.

[0096] The foregoing description has been presented with reference to the presently preferred embodiments of the invention. Those skilled in the art will recognize that changes and modifications can be made to the described structures without departing from the principles, spirit, and scope of the invention. Any feature or structure disclosed in one embodiment may be incorporated, as needed or appropriate, to replace or supplement other features of any other embodiment. As will be understood by those skilled in the art, the drawings are not necessarily drawn to scale. Therefore, the foregoing description should not be construed as relating only to the precise structures described and illustrated in the drawings, but should be considered to be consistent with and supported by the following claims, which have the fullest and most reasonable scope.

Claims

1. An electrophysiological catheter, comprising: A slender catheter body defining its longitudinal axis; contraction line; and A 3D distal assembly, which is movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction line. The 3D distal assembly has a bent portion and a distal portion. The bent portion has a proximal bent segment, a bent joint, and a distal bent segment. The proximal bent segment is defined by a proximal diameter, the distal bent segment is defined by an intermediate diameter, and the distal portion is defined by a distal diameter. In the neutral configuration, the proximal diameter is smaller than the intermediate diameter, and both the proximal diameter and the intermediate diameter are smaller than the distal diameter. In the contracted configuration, the proximal diameter, the intermediate diameter, and the distal diameter are all reduced, and the distal diameter is approximately equal to or smaller than the proximal diameter. The 3D distal component includes an elongated support member made of shape memory material. The elongated support member has a tapered distal portion with a generally rectangular cross-section. The width of the generally rectangular cross-section gradually decreases towards the distal end of the tapered distal portion, while the height of the generally rectangular cross-section gradually increases towards the distal end of the tapered distal portion. The cross-sectional area of ​​the elongated support member remains constant along its length. Furthermore, the contraction line acts on the elongated support member to move the 3D distal component from the neutral configuration to the contraction configuration when the contraction line is pulled proximally.

2. The electrophysiological catheter of claim 1, wherein the bend joint has a torsion portion configured to support the distal portion substantially transverse to the longitudinal axis, such that the longitudinal axis extends through the center of the distal portion.

3. The electrophysiological catheter of claim 1, wherein the distal assembly has an elongated support member having an inner flat side and an opposing flat side, and wherein the contraction line has a distal segment extending along its entire length coexisting with the inner flat side.

4. The electrophysiological catheter of claim 3, wherein the inner flat side of the support member is on or near the inner circumference of the distal portion of the 3D distal assembly.

5. The electrophysiological catheter of claim 3, wherein the distal component further comprises a radial tightening conduit circumferentially surrounding the elongated support member and a friction-reducing conduit surrounding the contraction line.

6. The electrophysiological catheter of claim 5, wherein the radial tightening conduit is circumferentially tightened around the support member and the friction-reducing sheath to minimize movement of the friction-reducing conduit relative to the support member.

7. An electrophysiological catheter, comprising: A slender catheter body defining a longitudinal axis; contraction line; and A distal assembly having a 3D arcuate form, the distal assembly being movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction line, the distal assembly having: A support member providing the 3D arcuate form, the 3D arcuate form having a bent portion and a distal portion, the bent portion having a proximal bent segment, a bent joint, and a distal bent segment, the proximal bent segment being defined by a proximal diameter, the distal bent segment being defined by an intermediate diameter, and the distal portion being defined by a distal diameter; and A radially tightening conduit that circumferentially surrounds the common extension portion of the support member and the contraction line; In the neutral configuration, the proximal diameter is smaller than the intermediate diameter, and both the proximal diameter and the intermediate diameter are smaller than the distal diameter. In the contracted configuration, the proximal diameter, the intermediate diameter, and the distal diameter are all reduced, and the distal diameter is reduced to a diameter approximately smaller than the distal diameter. The support member is made of shape memory material and has a tapered distal portion with a generally rectangular cross-section. The width of the roughly rectangular cross-section gradually decreases towards the distal end of the tapered distal portion, while the height of the roughly rectangular cross-section gradually increases towards the distal end of the tapered distal portion. The cross-sectional area of ​​the support member remains constant along its length. Furthermore, the contraction line acts on the support member to move the distal component from the neutral configuration to the contraction configuration when the contraction line is pulled proximally.

8. The electrophysiological catheter of claim 7, wherein the 3D arcuate form defines an inner circumference, wherein the distal component includes a conduit having a plurality of lumens, the plurality of lumens including the lumen closest to the inner circumference, and wherein the support member and the contraction line coexist in the lumen closest to the inner circumference.

9. The electrophysiological catheter of claim 8, wherein the support member has a generally rectangular cross-section, the support member has a distal portion, wherein the width and height dimensions of the generally rectangular cross-section vary along the length of the distal portion.

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