Patent Description:
Ablation of myocardial tissue is well known as a treatment for cardiac arrhythmias. In radio-frequency (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 through an electrode on the catheter in order to create a lesion for the purpose of breaking arrhythmogenic current paths in the tissue.

Circumferential ablation of the ostia of the pulmonary vein is now accepted as a treatment for atrial arrhythmias, and particularly for atrial fibrillation. For example, <CIT>
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 co-linear, to a second, J-shaped, configuration in which the proximal and distal sections are generally parallel with a separation therebetween substantially corresponding to the inside diameter of the blood vessel. The distal end portion of the catheter is rotated about the longitudinal axis of the catheter to cause a circumferential displacement of proximal and distal ablation electrodes on the catheter along the inner wall of the pulmonary vein. In this way, the electrode catheter may be used to ablate a number of circumferentially-spaced sites on the inner wall of the pulmonary vein by ablating one or two sites at each circumferential position.

<CIT> describes a lasso for pulmonary vein mapping and ablation. A catheter for circumferentially mapping a pulmonary vein (PV) includes a curved section shaped to generally conform to the shape of the interior surface of the PV. The curved section is connected to catheter by a generally straight axial base section that is in an "on edge" configuration where the base axial section connects to the curved section on the circumference of the curved section. The curved section comprises one or more sensing electrodes, and its proximal end is joined at a fixed or generally known angle to a base section of the catheter. Position sensors are fixed to the curved section of the catheter and to the distal end of the base section. 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 remains within the left atrium, typically positioned such that the joint with the curved section is at the ostium of the vein. The information generated by the three position sensors is used to calculate the locations and orientations of the sensing electrodes, which enables mapping of the surface of the PV. The sensing electrodes may additionally perform ablation of selected sites, or the catheter may further comprise ablation elements.

<CIT> describes compound steering assemblies, usable in both diagnostic and therapeutic applications, for steering the distal section of a catheter in multiple planes or complex curves. These assemblies are said to enable a physician to swiftly and accurately position and maintain ablation and/or mapping electrodes in intimate contact with an interior body surface. <CIT> similarly describes compound steering assemblies of this sort.

<CIT> describes a medical device, including an insertion shaft, having a longitudinal axis and having a distal end adapted for insertion into a body of a patient. A resilient end section is fixed to the distal end of the insertion shaft and is formed so as to define, when unconstrained, an arc oriented obliquely relative to the axis and having a center of curvature on the axis. One or more electrodes are disposed at respective locations along the end section.

However, because human anatomy varies between individuals, the shape and size of an ostium vary, and the arcuate distal section may not always fit the particular target ostium. Moreover, it may be desirable to use the same catheter for a target ostium of a certain diameter and also the PV of that ostium which may have a significantly lesser diameter. Additionally, where a lasso catheter may have a variable arcuate distal assembly, contraction of the arcuate distal assembly may misshapen the generally circular form of the arcuate distal assembly because one or more of the components thereof are too stiff for tighter coiling in a desirable manner.

Current circular loop catheters are constructed utilizing a support member, e.g., a nitinol spine, with a constant uniform cross-section that fails to consistently maintain a circular configuration during loop contraction. Such current circular loop catheters also are limited in its contraction and deflection characteristics in requiring more pound contraction wire tensile force for less loop contraction. Moreover, current circular loop catheters may lack reliable attachment between the contraction wire and the support member that would eliminate possible breakage or release of the contraction wire from the support member. Current circular loop catheters have nitinol spines with the same uniform area moments of inertia along their entire length and the nitinol spines have the same cross-sectional area. <CIT> describes a medical device control handle with multiple puller wires. <CIT> describes a catheter adapted for deflection in a narrow tubular region and/or a sharp turn. The catheter has an elongated body, a deflection section having a support member adapted for heat activation to assume a trained configuration and a lead wire configured to deliver a current to the support member for heat activation. The support member is constructed of a shape memory alloy, for example nitinol, and the lead wire is adapted to directly heat the support member. Moreover, the catheter may include a thermally insulating layer covering at least a portion of the support member. The trained configuration of the support member extends in a single dimension, in two dimensions or in three dimensions. <CIT> describes a catheter with single axial sensors. <CIT> describes a catheter including an elongated body, a distal assembly with a shape-memory member defining a generally circular form, and a control handle adapted to actuate a deflection puller wire for deflecting a portion of the elongated body, and a contraction wire for contracting the generally circular form. <CIT>, cited under Article <NUM>(<NUM>) EPC, describes a catheter with a variable circular loop responsive 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 the entire tapered length for improved coiling characteristics. A radially constrictive sleeve prevents separation of the contraction wire from the support member to minimize misshaping of the loop during contraction.

The present invention is directed to a catheter having a variable arcuate distal with improved contraction and bending radius characteristics, along with greater durability. The variable arcuate distal section includes a shape-memory support member, a contraction wire, and a radially-constrictive tubing or sleeve to greatly increase the degree of contraction of a generally circular catheter loop while decreasing the forces on the contraction wire and all other structural support portions of the loop and providing operators of the catheter with a repeatable and more truthful round contraction for circular diagnostic and therapeutic catheters.

In some embodiments, the radially-constrictive tubing is transparent or at least translucent so that the contraction wire under the tubing is visible, especially during assembly of the variable arcuate distal section.

In some embodiments, the radially-constrictive tubing has a braided construction so that its radial constriction is increased when tension is applied to the tubing in a longitudinal direction.

The radially-constrictive tubing is constructed of a manufactured fiber, spun from a liquid crystal polymer (LCP), for example, manufactured fiber sold under the trademark VECTRAN®, created by Celanese Acetate LLC and now manufactured by Kuraray Co.

In some embodiments, an electrophysiology catheter includes an elongated catheter body, a contraction wire, and a distal assembly configured for contraction by actuation of the contraction wire. The distal assembly has a shape-memory support member having a <NUM>-D configuration with a distal portion defined by a distal radius.

In more detailed embodiments, the support member has an inner side facing an inner circumference of the <NUM>-D configuration, wherein a coextensive portion of the contraction wire extending through the distal assembly is aligned with the inner side.

In some detailed embodiments, the distal assembly includes a radially constrictive tubing surrounding the support member and a coextensive portion of the contraction wire with the support member.

In some detailed embodiments, the support member and the coextensive segment of the contraction wire jointly define a cross-sectional profile, and the radially constrictive tubing surrounds the support member and the coextensive segment generally in conformity to the cross-sectional profile.

In some detailed embodiments, the coextensive portion of the contraction wire is aligned with a flat side of the support member and configured to maintain the coextensive segment of the contraction wire generally in align the flat side during contraction of the distal assembly.

In some embodiments, an electrophysiology catheter has an elongated catheter body defining a longitudinal axis, a contraction wire, and a <NUM>-D distal assembly movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction wire. The <NUM>-D distal assembly has at least an elbow defined by a proximal diameter and a distal portion defined by a distal diameter, and a radially constrictive tubing that extends generally between the elbow junction and the distal portion. For the neutral configuration, the proximal diameter is less than the distal diameter. For the contracted configuration, the distal diameter is about equal to or less than the proximal diameter.

In some detailed embodiments, the elbow junction has a twist configured to support the distal portion generally transversal to the longitudinal axis such that the longitudinal axis extends through a center of the distal portion.

In some detailed embodiments, the distal assembly has an elongated support member having an inner flat side and an opposing flat side, and wherein the contraction wire has a distal segment coextensive with the inner flat side along its entire length.

In some detailed embodiments, the inner side of the support member is on or near an inner circumference of the distal portion of the <NUM>-D distal assembly.

In some embodiments, the distal assembly further includes a radially-constrictive tubing circumferentially surrounding at least a portion of the elongated support member and a friction-reducing tubing surrounding a portion of the contraction wire.

In some embodiments, the radially-constrictive tubing is circumferentially constrictive around the support member and the friction-reducing tubing in minimizing lateral movement of the contraction wire relative to the support member.

In other embodiments, an electrophysiology catheter has an elongated catheter body defining a longitudinal axis, a contraction wire, and a distal assembly with a <NUM>-D arcuate form, the distal assembly movable between a neutral configuration and a contracted configuration in response to longitudinal movement of the contraction wire. The distal assembly has a support member providing the <NUM>-D arcuate form, the <NUM>-D arcuate form 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, and a radially constrictive tubing surrounding the support member and a coextensive portion of the contraction wire. For the neutral configuration, the proximal diameter is less than the distal diameter. For the contracted configuration, the distal diameter is decreased to a diameter about less than the distal diameter.

In some detailed embodiments, the <NUM>-D arcuate form defines an inner circumference, the distal assembly includes a tubing with multiple lumens including a lumen closest to the inner circumference, and the support member and the coextensive portion of contraction wire are in the lumen closest to the inner circumference.

In some detailed embodiments, the support member has a generally-rectangular cross-section, the support member having a distal portion wherein a width dimension and a height dimension of the generally rectangular cross-section varies along the length of the distal portion.

These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings. It is understood that selected structures and features have not been shown in certain drawings so as to provide better viewing of the remaining structures and features.

Embodiments of the present invention that are described hereinbelow provide probes, such as catheters, with improved arcuate distal electrode-carrying structures, to facilitate maneuvering and positioning in the heart and especially tubular regions of different sizes in a patient's body and different circumferential locations within the tubular regions. Such catheters can be used to produce generally circular or helical ablation paths, as well as sensing electrical activity along a generally curve or helical pattern for electrical potential and anatomical mapping.

Referring to <FIG>, a catheter <NUM> according to the disclosed embodiments comprises an elongated body that may include a flexible insertion shaft or catheter body <NUM> having a longitudinal axis <NUM>, and an intermediate section <NUM> distal of the catheter body that can be uni- or bi-directionally deflected off-axis from the longitudinal axis <NUM>. As shown in <FIG>, extending from the intermediate section <NUM> is a resilient three-dimensional (<NUM>-D) arcuate distal assembly <NUM> which is advantageously constructed for significantly greater and more uniform loop contraction. As explained below in further detail, the distal assembly <NUM> is responsive to operator manipulation of a control handle <NUM> in decreasing its radius and increasing its coiling, as shown in <FIG>.

In the depicted embodiment of <FIG> and <FIG>, the catheter body <NUM> comprises an elongated tubular construction having a single, axial or central lumen <NUM>. The catheter body <NUM> is flexible, i.e., bendable, but substantially non-compressible along its length. The catheter body <NUM> can be of any suitable construction and made of any suitable material. In some embodiments, the construction comprises an outer wall <NUM> made of polyurethane or PEBAX. The outer wall <NUM> comprises an imbedded braided mesh of stainless steel or the like, as is generally known in the art, to increase torsional stiffness of the catheter body <NUM> so that, when the control handle <NUM> is rotated, the intermediate section <NUM> will rotate in a corresponding manner.

The outer diameter of the catheter body <NUM> is not critical, but in some embodiments is no more than about <NUM> french, more preferably <NUM> french. Likewise the thickness of the outer wall <NUM> is not critical, but is thin enough so that the central lumen <NUM> can accommodate any desired wires, cables and/or tubes. The inner surface of the outer wall <NUM> is lined with a stiffening tube <NUM> to provide improved torsional stability. The outer diameter of the stiffening tube <NUM> is about the same as or slightly smaller than the inner diameter of the outer wall <NUM>. The stiffening tube <NUM> can be made of any suitable material, such as polyimide, which provides very good stiffness and does not soften at body temperature.

The deflectable intermediate section <NUM> comprises a shorter section of tubing <NUM> having multiple lumens, most of which are occupied by the various components passing from the catheter <NUM> and into the intermediate section <NUM>. In the illustrated embodiment of <FIG>, there are six lumens. Coupled to the ring electrodes <NUM>, respective lead wire/thermocouple pairs <NUM>, <NUM> pass through a first lumen <NUM>. A nonconductive protective sheath <NUM> may be provided to surround the wire pairs <NUM>/<NUM>. An irrigation tubing <NUM> for delivering irrigation fluid to the distal assembly <NUM> passes through a second lumen <NUM>. For enabling deflection of the intermediate section <NUM>, a deflection puller wire <NUM> passes through a third lumen <NUM>. A position sensor cable assembly <NUM>, including one or more single axis sensors (SAS) carried in the distal assembly <NUM>, passes through a fourth lumen <NUM>. To render an arcuate distal portion <NUM> of the distal assembly <NUM> variable in shape and size, e.g., curvature radii, in response to manipulation of the control handle by a user, a contraction wire <NUM> passes through a sixth lumen <NUM>. As described below, the contraction wire <NUM> acts on an elongated shape-memory support member <NUM> that provides the <NUM>-D shape of the distal assembly <NUM>.

The multi-lumened tubing <NUM> of the intermediate section <NUM> is made of a suitable non-toxic material that is preferably more flexible than the catheter body <NUM>. A suitable material is braided polyurethane or PEBAX, i.e., polyurethane or PEBAX with an embedded mesh of braided stainless steel or the like. The plurality and size of the lumens are not critical, provided there is sufficient room to house the relevant components. In the illustrated embodiment, the third and sixth lumens <NUM> and <NUM> for the deflection puller wire <NUM> and contraction wire <NUM> are off-axis and diametrically opposed to each other, and the fifth lumen <NUM> for the support member <NUM> is on-axis.

The useful length of the catheter, i.e., that portion that can be inserted into the body excluding the distal assembly <NUM>, can vary as desired. Preferably the useful length ranges from about <NUM> to about <NUM>. The length of the intermediate section <NUM> is a relatively small portion of the useful length, and preferably ranges from about <NUM> to about <NUM>, more preferably from about <NUM> to about <NUM>.

Distal the intermediate section <NUM> is the distal assembly <NUM>. Extending between the intermediate section <NUM> and the distal assembly <NUM> is a generally straight connector section <NUM>, as shown in <FIG> and <FIG>, having a tubing of suitable material, e.g., PEEK, with a central lumen <NUM> that allows the various components extending between the intermediate section <NUM> and the distal assembly <NUM> to reorient and reposition as needed for transitioning therebetween, as shown in <FIG>. The components are potted in the lumen <NUM> of the connector section <NUM> by a suitable materials, for example, adhesive <NUM>. Supporting the distal assembly <NUM> and providing its <NUM>-D shape, the shape-memory support member <NUM> extends proximally from the distal assembly <NUM> for a relatively short distance into a distal portion of the connector section <NUM>.

As shown in <FIG> and <FIG>, the <NUM>-D distal assembly <NUM> includes a preformed, arcuate distal portion <NUM>, an elbow portion <NUM>, and a proximal linear stem <NUM>. The arcuate distal portion <NUM> carries a plurality of irrigated ring electrodes <NUM>. The elbow portion <NUM> is configured to orient the distal portion <NUM> obliquely to the longitudinal axis <NUM> such that the longitudinal axis extends generally through a center of the distal portion <NUM>, as shown in <FIG>. As such, an oblique angle Θ (<FIG>) is defined between the longitudinal axis <NUM> and a plane P generally defined by the distal assembly <NUM>, wherein the oblique angle Θ ranges between about <NUM> degrees and <NUM>, preferably about <NUM> and <NUM> degrees, and preferably about <NUM> degrees.

With reference to <FIG>, <FIG> and <FIG>, the elbow portion <NUM> has a proximal curved section 21P, an elbow junction or "twist" <NUM>, and a distal curved section 21D. The proximal curved section 21P traces a first arc defined by a first (or proximal) radius R1 relative to the longitudinal axis <NUM>. The distal curved section 21D traces a second arc defined by a second (or mid) radius R2 relative to an axis <NUM> oblique to the longitudinal axis <NUM>. The first radius R1 is lesser than the second radius R2. However, both radii R1 and R2 are lesser than a third (or distal) radius R3 defining a third arc traced by the distal portion <NUM>. In some embodiments, the radius R1 ranges between about <NUM>" and <NUM>", the radius R2 ranges between about <NUM>" and <NUM>", and the radius R3 ranges between about <NUM>" and <NUM>". As such, the <NUM>-D configuration of the distal assembly <NUM>, when unconstrained, has a spiral characteristic, with radius R3 being greater than the radius R2. For example, where the oblique angle Θ is about <NUM> degrees and the longitudinal axis <NUM> defines a Z axis, the first arc defined by radius R1 may lie in the Y/Z plane, and the second and third arcs defined respectively by radii R2 and R3 may both lie in the X/Y plane, as shown in <FIG>. It is understood that the distal assembly <NUM> is not limited to the radii R1, R2 and R3 described above, and may contain more or less radii, as needed or desired.

The <NUM>-D configuration of the distal assembly <NUM>, when unconstrained, also has a helical characteristic in that the distal assembly <NUM> extends distally as it spirals such that the distal end <NUM> of the distal assembly <NUM> is the distal-most portion of the distal assembly <NUM>, as best shown in <FIG>.

Accordingly, the distal assembly <NUM> has a spiral-helical configuration (or helical-spiral configuration) such that there are a first separation gap between the distal end <NUM> and the distal curved section 21D along the longitudinal axis <NUM>, and a second separation gap between the distal end <NUM> and the distal curved section 21D along the oblique axis <NUM>. The spiral-helical configuration of the distal assembly <NUM> can be described as tracing from its proximal end to its distal end an enlarging helix that is on-axis with the longitudinal axis, as shown in <FIG>.

Depending on the length of the distal portion <NUM>, the distal assembly <NUM>, in its neutral, unconstrained <NUM>-D configuration, may subtend a radial angle α of about <NUM> degrees between the twist <NUM> and the distal end <NUM>. In another embodiment, the distal assembly <NUM> subtends a radial angle α (<FIG>) greater than <NUM> degrees, e.g., about <NUM> degrees. When the distal assembly <NUM> is contracted, as shown in <FIG>, the spiral-helical form "coils up" and tightens, with the one or more of radii R1, R2, R3 traced by the distal assembly <NUM> decreasing, and the radial angle α subtended by the distal assembly <NUM> increasing, for example, from about <NUM> or <NUM> degrees to about <NUM> degrees or more between the twist <NUM> and the distal end <NUM>. Accordingly, the distal assembly <NUM> in its neutral, unconstrained configuration may be used for circumferential contact with an ostium having a larger radius, and then be adjusted into its contracted configuration for circumferential contact within the PV of the ostium with a significantly smaller radius.

As shown in <FIG>, the distal assembly <NUM> includes a multi-lumened tubing <NUM>. In the disclosed embodiment, the tubing <NUM> has four off-axis lumens, namely, a first lumen <NUM> for the SAS cable assembly <NUM> (circumferentially surrounded by a friction-reducing coating <NUM>, e.g., of TEFLON®), a second lumen <NUM> for the ring electrode wire pairs <NUM>, <NUM>, a third lumen <NUM> for irrigation fluid delivered through the irrigation tubing <NUM>, and a fourth lumen <NUM> for the support member <NUM> and the contraction wire <NUM>, a segment of which is coextensive with the support member <NUM> in the lumen <NUM>. Again, position and sizing of the lumens are not critical, except the position of the fourth lumen <NUM> for the contraction wire <NUM> is preferably on or near an inner circumference of the spiral-helical form of the distal assembly <NUM> so that proximal movement of the wire <NUM> can act more effectively in tightening the spiral-helical form and increasing its coiling. The multi-lumened tubing <NUM> can be made of any suitable material, and is preferably made of a biocompatible plastic such as polyurethane or PEBAX.

In the depicted embodiment, the pre-formed support member <NUM> of the distal assembly <NUM> extends through the fourth lumen <NUM> of the tubing <NUM> to provide and define the <NUM>-D spiral-helical shape of the distal assembly <NUM>, which includes the twist <NUM> and arcs of the proximal section 21P and the distal section 21D, and the distal portion <NUM> defined by radii R1, R2 and R3. The support member <NUM> is made of a material having shape-memory, i.e., that can be straightened or bent out of its original shape upon exertion of a force and is capable of substantially returning to its original shape upon removal of the force. In some embodiments, a suitable material for the support member <NUM> is a nickel/titanium alloy. Such alloys typically comprise about <NUM>% nickel and <NUM>% titanium, but may comprise from about <NUM>% to about <NUM>% nickel with the balance being titanium. One nickel/titanium alloy is Nitinol, which has excellent shape memory, together with ductility, strength, corrosion resistance, electrical resistivity and temperature stability.

In some embodiments, as shown in <FIG>, the support member <NUM> has a proximal end received and affixed in the connector section <NUM> In some embodiments, the proximal end of the support member <NUM> extends at a depth of about <NUM>-<NUM> proximal of the distal end of the connector section <NUM>. Alternatively, the support member <NUM> can extend further proximally into the lumen <NUM> of the intermediate section <NUM>, through the entire length of the intermediate section <NUM>, and even into the catheter body <NUM> via the central lumen <NUM>, as desired or appropriate.

Advantageously, the support member <NUM> has a generally rectangular cross-sectional shape whose height and width dimensions vary in a predetermined manner along the length of the member <NUM>. As shown in <FIG>, the generally rectangular cross-sectional area at any location along the length remains constant although its width dimension W and height dimension vary at different locations. There is no reduction or increase in the cross-sectional area at any location along the length in that any loss or gain in one dimension is proportionally gained or lost by the other dimension between a more proximal location and a more distal location along the length of the support member <NUM>. As a tapered portion or "tail" of the support member <NUM> 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 dimension that decreases (for example, the width dimension W along the X axis in <FIG>) decreases its resistance to bending in that dimension from the proximal end to the distal end, while the dimension that increases (for example, the height dimension H along the Y axis in <FIG>) increases its resistance to bending in that dimension from a proximal end to a distal end of the tapered portion.

As shown in <FIG>, the generally rectangular cross-section of the support member <NUM> at its proximal end has a maximum width W1 and a minimum height H1. For minimizing change or deformation in radii R1 and R2 during contraction of the distal assembly <NUM>, the width and height dimensions of the cross-sectional area of the support member <NUM> begin to change (or taper) starting at a predetermined location distal of radius R2 (e.g., at or around location L2) Distal of the predetermined location, in the tapered tail of distal assembly <NUM>, 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) while the height further increases to H3 (>H2 >H1) at distal location L3. These decreases and increases are smooth and continuous. This tapered configuration biases the support member <NUM> to have increasing less resistance to coiling toward the distal end <NUM> such as when contracted by the contraction wire <NUM>, while providing increasingly more resistance to oblique forces toward the distal end <NUM> such as when the distal assembly <NUM> contacts tissue surface head on. Thus, this varied cross-sectional shape allows the distal assembly <NUM> to exhibit improved contraction characteristics, including the distal portion <NUM> being able to contract and coil readily with minimal deformation of the elbow junction <NUM> and the elbow junction <NUM> being better able to withstand the load from an axial force that is applied when the distal assembly <NUM> comes into contact with target tissue. With this varied cross-sectional shape applied to the support member <NUM>, the distal assembly <NUM> can be adjusted, upon actuation of the contraction wire <NUM>, to assume a smaller loop size (see <FIG>), for example, where the distal portion <NUM> assumes a curvature that is generally equal to or even be lesser than the curvature of the distal section 21D.

As shown in <FIG>, with a generally rectangular cross-section, the support member <NUM> resembles a "coiled ribbon" having sides/surfaces <NUM> and <NUM> defining a height dimension of the generally rectangular cross-section, and edges <NUM> defining a width dimension of the generally rectangular cross-section. Advantageously, the inner flat side/surface <NUM>, along its length, continually faces the inner circumference of the spiral-helical configuration of the distal assembly, and an outer flat side/surface <NUM> that is opposite of the inner flat surface <NUM> continually faces outwardly, away from the inner circumference of the spiral-helical configuration. The tapering of the support member <NUM> results in the "tapered tail" of the distal assembly <NUM> resembling an increasing wider and thinner ribbon.

Moreover, the generally rectangular cross-section at the proximal end of the support member <NUM> helps anchor the proximal end in the lumen <NUM> of the tubing <NUM> of the deflectable section <NUM> and reduces the risk of the support member rotating about its axis where the proximal end is potted by an adhesive, e.g., epoxy (see <FIG>).

In some embodiments, the support member <NUM> begins with a round cross-sectional shape, as shown in <FIG>. The support member <NUM>, for example, a round wire, is progressively flattened to produce the generally rectangular cross-section and tapered tail. Thus, the two opposed ends of the width dimension between the parallel fattened surfaces of the height dimension carry the residual round shape of the original round cross-sectional shape. It is understood that the support member may begin with a square/rectangular cross-sectional shape which would then result in flat opposed ends instead of round opposed ends. In some embodiments, using a round wire may be more economical to manufacture, and rounded opposed ends may ease the assembly of the distal assembly <NUM>, including insertion of the support member into a radially-constrictive flexible tubing or sleeve <NUM>, as discussed further below. The rounded opposed ends may reduce the insertion force used to insert the support member <NUM> into the tubing <NUM> and also the risk of the support member <NUM> tearing and damaging the tubing <NUM>.

In some embodiments, the support member <NUM>, as a round wire, has an initial (pre-flattening) diameter of about <NUM> inches and a length of about <NUM> inches. When flattened, the support member <NUM> has a generally rectangular cross-sectional dimensions of about <NUM>" x <NUM>" from its proximal end to the location L2. The tapered tail of the support member <NUM> (distal of location L2 in <FIG>) is about <NUM> inches long and has a generally rectangular cross-sectional dimensions of about <NUM>" x <NUM>" at or near its distal end <NUM>. In some embodiments, a distal end of the support member <NUM> has an unflattened section 50D which retains its round cross-section, as explained below in further detail.

The area moment of inertia for the <NUM> inch diameter support member <NUM> (pre-flattening) is the same regardless of centroidal axis orientation, whereas the area moment of inertia at or near its distal end for the first centroidal axis is <NUM> times less stiff than the moment of inertia at the proximal end. The moment of inertia for the second centroidal axis at the distal end is <NUM> times stiffer than the moment of inertia at the proximal end. Comparing the two centroidal axis area moments of inertia at the distal end with respect to each other, the first centroidal axis is <NUM> times less stiff than the second centroidal axis. Since the contraction wire <NUM> exerts a constant inwardly line of force (neglecting friction) on the support member <NUM>, to obtain a small, generally circular contraction, the area moment of inertia of the support member <NUM> should constantly decrease towards the distal end where it is attached to the contraction wire <NUM>.

The contraction wire <NUM> has a proximal end anchored in the control handle <NUM> which provides a rotational control knob <NUM> (see <FIG>) for actuating the contraction wire <NUM> via manipulation by an operator. The contraction wire <NUM> extends through the central lumen <NUM> of the catheter body <NUM> (<FIG>), the sixth lumen <NUM> of the intermediate section <NUM> (<FIG>), the central lumen <NUM> of the connector section <NUM> (<FIG>) and the fourth lumen <NUM> of the tubing <NUM> of the distal assembly <NUM> (<FIG>) alongside the support member <NUM>, to the distal end <NUM> (<FIG>).

The contraction wire <NUM> may be covered by a friction-reducing tubing <NUM> (<FIG>), e.g., a TEFLON® coated inner diameter of a polyimide or PEEK tubing, so that the contraction wire <NUM> is physically separated and isolated from the side <NUM> of the support member <NUM> and the inside surface of the constrictive tubing <NUM> that surrounds the contraction wire <NUM> and the support member <NUM>, which is described below in further detail. The friction-reducing tubing <NUM> may have a proximal end in the connector section <NUM> and a distal end at least distal of the radius R2, at or near the location L2, if not closer to the distal end of the support member <NUM>.

Advantageously, the support member <NUM> and the coextensive segment of the contraction wire <NUM> (and its tubing <NUM>) through the lumen <NUM> of the distal assembly <NUM> are surrounded and bound together by the tight-fitting flexible tubing <NUM>.

As shown in <FIG>, the tubing <NUM> to provide radial constriction includes a woven or braided tubing of a manufactured fiber, spun from a liquid crystal polymer (LCP), for example, manufactured fiber sold under the trademark VECTRAN®. Chemically, it is an aromatic polyester produced by the polycondensation of <NUM>-hydroxybenzoic acid and <NUM>-hydroxynaphthalene-<NUM>-carboxylic acid. These fibers exhibit thermal stability at high temperatures, high strength and modulus, low creep and good chemical stability.

The resulting tubing has a high modulus of elasticity which allows for improved contraction of the distal assembly <NUM>. In some embodiments, the manufactured fiber is braided at high pix per inch (PPI) of about <NUM> and is free of resin so that there is little restriction on the bending radius of the tubing. A tubing of such manufacture satisfies the strength required to constrain the contraction wire <NUM> from tearing the sidewall of the tubing <NUM>. Moreover, the tubing is sufficiently flexible to allow contraction of the distal assembly <NUM>, and sufficiently strong to withstand frictional fatigue of the contraction wire <NUM> and other moving components imposed on the tubing fibers.

In some embodiments, after the tubing <NUM> has been slipped onto the support member <NUM> and the contraction wire <NUM>, tension force T is applied to its ends to lengthen longitudinally and shorten radially to provide a radially constrictive tight fit around the support member <NUM> and the contraction wire <NUM> in ensuring that the contraction wire <NUM> remains in the proper location relative to the support member <NUM>, thus ensuring that the pulling force vector is in alignment with the support member <NUM> for a more efficient loop contraction and improved loop contraction geometry. The tubing <NUM> may also be fused to the lumen <NUM>.

In other embodiments, as shown in <FIG>, the tubing <NUM> for radial constriction has an inner diameter <NUM> composed of a friction-reducing material, such as, TEFLON®, (formed as a first extrusion coat or layer), which is covered by a stainless steel flat braid <NUM>, which is covered by an outer diameter <NUM>, such as nylon (formed as a second extrusion coat or layer). The constrictive tubing <NUM> is slipped over the support member <NUM> and the contraction wire <NUM> (with its friction-reducing tubing <NUM>) after their distal ends are affixed together, as described further below.

In some embodiments, the constrictive tubing <NUM> has a distal end at or near a junction of the radii R2 and R3, and a proximal end at or near the elbow junction <NUM>. The constrictive tubing <NUM> is fitted to provide circumferential/radial constriction around the member <NUM>, the contraction wire <NUM> with its friction-reducing tubing <NUM> (see <FIG>) so as to secure the tubing <NUM> against the inner side <NUM> of the support member <NUM> in keeping the contraction wire <NUM> aligned with (or on the side of) the inner side <NUM> for improving contraction characteristics of the distal assembly <NUM>, including improved circular shape maintenance and significantly tighter contraction and coiling, as well as improved durability against the contraction wire <NUM> cutting into the tubing <NUM> of the distal assembly <NUM>.

Such improved contraction characteristics, particularly of the tapered tail of the distal assembly, is enabled by keeping the contraction <NUM> against the inner side <NUM> throughout the length of the support member <NUM>. For example, where a radius R3 of the arc of distal portion <NUM> is about <NUM> when the distal assembly <NUM> is unconstrained, the distal assembly <NUM> can be contracted into a tighter coil such that the arcs of the distal curve portion 21D and the distal portion <NUM> are both defined by a radius of about <NUM>, for a reduction in the radius R3 of the arc of the distal portion <NUM> by about <NUM>% or more.

As illustrated in <FIG>, the contraction wire <NUM> within its tubing <NUM> runs along the entire length of the inner-facing side <NUM> of the support member <NUM> extending between the distal end <NUM> of the distal assembly <NUM> and the connector section <NUM>. This predetermined pattern advantageously minimizes any tendency for the contraction wire <NUM> to separate and lift from the support member <NUM> when the contraction wire <NUM> is drawn proximally. In some embodiments, the contraction wire <NUM> may also have a rectangular cross-section along its length or along one or more segments thereof.

With reference to <FIG>, an assembled structure of the distal ends of the support member <NUM>, contraction wire <NUM> and constrictive tubing <NUM> is oriented within the fourth lumen <NUM> of the tubing <NUM> of the distal assembly <NUM> such that the contraction wire <NUM> is most adjacent to the inner circumference of the distal assembly <NUM> to face the center of the distal assembly <NUM>. With the fourth lumen <NUM> positioned closer to the inner circumference than the other lumens of the tubing <NUM>, and the contraction wire <NUM> within the lumen <NUM> also positioned closer to the inner circumference than the support member <NUM>, the contraction wire <NUM> can effectively contract the distal assembly <NUM>.

Prior to insertion into the lumen <NUM>, the assembled structure of the distal ends of the support member <NUM>, the contraction wire <NUM> and the constrictive tubing <NUM> is prepared. In some embodiments, a coupling of the distal ends of the contraction wire <NUM> and support member <NUM> includes a laser welded coupling having a stainless steel ferrule <NUM> (e.g., <NUM> or <NUM> series) that is placed over the distal end 25D of the support member <NUM> which is not flattened but retains its original round cross-sectional shape. The ferrule <NUM> is flattened after it is placed over the distal end 25D. The flattened portion of the support member <NUM> acts as a stop preventing any proximal migration or dislocation of the ferrule <NUM> when contraction wire tension is applied to the support member <NUM>. The ferrule <NUM> is secured to the round distal end 50D of the support member <NUM> by a crimp die which has a flat portion that is clocked parallel to the surface <NUM> of the support member <NUM>. The distal end of the contraction wire <NUM> has a crimped ferrule <NUM> which has a flat portion that is also fixed to the flat portion of the ferrule <NUM>. A laser seam weld <NUM> is made on one common (bottom) side of the ferrules <NUM> and <NUM> joining the distal ends of the contraction wire <NUM> and the support member <NUM>.

In contrast to prior art coupling of the support member and the contraction wire which used lead-free solder to join a nitinol support member to the contraction wire, the laser welded coupling described herein includes the use of strong acid flux to remove oxides from the nitinol and stainless steel before soldering. Moreover, the laser welded coupling provides a much stronger attachment compared to the prior art the lead-free solder with a low shear and tensile strength (about <NUM> psi) which can attribute to puller wire detachment failures from the nitinol support member when the lead-free solder contained unexposed voids or was formed as a cold solder joint.

The constrictive tubing <NUM> is then slid over the contraction wire <NUM> at its proximal end, advanced over the support member <NUM> at its proximal end, and further advanced until the distal end of the tubing <NUM> reaches and covers the assembled structure.

When the constrictive tubing <NUM> has been properly positioned over the contraction wire <NUM> and the support member <NUM>, the constrictive tubing <NUM> has a proximal end near a junction of radii R2 and R3, and it distal end is trimmed or otherwise provided with a finished distal end terminating immediately proximal of the stainless steel ferrule <NUM>. The finished distal end of the constrictive tubing <NUM> is then affixed to the friction-reducing tubing <NUM> and the support member <NUM> by a circumferential application of an adhesive <NUM>, e.g., LOCTITE®. Notably, the friction-reducing tubing <NUM> surrounding the contraction wire <NUM> has a distal end that is well proximal of the soldered stainless steel ferrule <NUM> so that the adhesive <NUM> can bond the distal end of the constrictive tubing <NUM> directly on to the contraction wire <NUM> and the support member <NUM>.

The assembled structure of the contraction wire <NUM>, the support member <NUM> and the constrictive tubing <NUM> is then inserted into the lumen <NUM>, where the stainless steel ferrule <NUM> and its contained components are fixed and anchored at the distal end of the multi-lumened tubing <NUM> by an adhesive <NUM>, e.g., polyurethane, which covers the entire distal face of the distal end <NUM> to form a tip dome, as shown in <FIG>. With this arrangement, the relative positions of the contraction wire <NUM> and the support member <NUM> can be controlled so that the contraction wire <NUM> is positioned on or near the inner circumference of the distal assembly <NUM>, closer to the center of the spiral-helical form, as described above. The constrictive tubing <NUM> protects the multi-lumened tubing <NUM> from the contraction wire <NUM> cutting into its side wall during contraction of the distal assembly <NUM>.

With reference to <FIG>, a compression coil <NUM> surrounding the contraction wire <NUM> extends from the proximal end of the catheter body <NUM> and through the entire length of the sixth lumen <NUM> of the intermediate section <NUM>. Thus, the compression coil has a distal end at or near a mid-location in the connector section <NUM>. The compression coil <NUM> is made of any suitable metal, preferably stainless steel, and is tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of the compression coil is preferably slightly larger than the diameter of the contraction wire <NUM>. The outer surface of the compression coil is covered by a flexible, non-conductive sheath <NUM>, e.g., made of polyimide tubing. The compression coil preferably is formed of a wire having a square or rectangular cross-sectional area, which makes it less compressible than a compression coil formed from a wire having a circular cross-sectional area. As a result, the compression coil <NUM> keeps the catheter body <NUM>, and particularly the intermediate section <NUM>, from deflecting when the contraction wire <NUM> is drawn proximally to contract the distal assembly <NUM>, as the compression coil <NUM> absorbs more of the compression.

The ring electrodes <NUM> are mounted on predetermined locations on the distal portion <NUM>, as shown in <FIG>. The electrodes 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 mounted onto the tubing with glue or the like. A suitable embodiment of an electrode adapted for ablation and irrigation is illustrated in <FIG>. An ablation reservoir ("AR") electrode is generally cylindrical with a length greater than its diameter. In one embodiment, the length is about <NUM>, the outer diameter is about <NUM>, and the inner diameter is about <NUM>.

In some embodiments, the plurality of AR ring electrodes <NUM> on the distal assembly <NUM> can ranges from about six to about twenty, more preferably from about eight to about twelve. In some embodiments, the distal assembly <NUM> carries ten AR electrodes. The electrodes can be approximately evenly spaced along the distal portion <NUM>.

The proximal end of each wire of the wire pairs <NUM>, <NUM> is electrically connected to a suitable connector (not shown) distal of the control handle <NUM>. In the disclosed embodiment, wire <NUM> of a wire pair is a copper wire, e.g. a number "<NUM>" copper wire, and the other wire <NUM> of the wire pair is a constantan wire. The wire pairs extend from the control handle <NUM>, through the central lumen <NUM> of the catheter body <NUM> (<FIG>), the first lumen <NUM> of the intermediate section <NUM> (<FIG>), the central lumen <NUM> of the connector section <NUM> (<FIG>), and the second lumen <NUM> of the distal assembly <NUM> (<FIG>). The distal ends of the wire pairs pass through holes <NUM> (<FIG>) formed in the side wall of the tubing <NUM> to reach the AR electrodes <NUM>. The wires of each pair are electrically isolated from each other except at their distal ends where they are exposed. Exposed distal ends of a respective wire pair <NUM>, <NUM> are sandblasted, and wrapped in and welded to a folded metal foil <NUM> (e.g., copper foil) which is then welded to an inner surface <NUM> near a proximal end <NUM> of its AR electrode <NUM>, as shown in <FIG>.

Ablation energy, e.g., RF energy, is delivered to the AR electrodes <NUM> via the wire <NUM> of the wire pairs. However, the wire pairs inclusive of their respective constantan wire <NUM> can also function as temperature sensors or thermocouples sensing temperature of each AR electrode <NUM>.

All of the wire pairs pass through one nonconductive protective sheath <NUM> (<FIG>), which can be made of any suitable material, e.g., polyimide, in surrounding relationship therewith. The sheath <NUM> extends with the wire pairs from the control handle <NUM>, the catheter body <NUM>, the intermediate section <NUM>, the connector section <NUM> and into the second lumen <NUM> of the distal assembly <NUM>, terminating just distal of the junction between the connector section <NUM> and the distal assembly <NUM>, for example, about <NUM> into the second lumen <NUM>. The distal end is anchored in the second lumen <NUM> by glue, for example, polyurethane glue or the like.

Irrigation fluid is delivered to the distal assembly by the irrigation tubing <NUM> whose proximal end is attached to a luer hub <NUM> (<FIG>) proximal of the control handle <NUM> and receives fluid delivered by a pump (not shown). The irrigation tubing <NUM> extends through the control handle <NUM>, the central lumen <NUM> of the catheter body <NUM> (<FIG>), the second lumen <NUM> of the intermediate section <NUM> (<FIG>), the central lumen <NUM> of the connector section <NUM> (<FIG>) and a short distance, e.g., about <NUM>, distally into the third lumen <NUM> of the multi-lumened tubing <NUM> of the distal assembly <NUM>. The fluid enters the third lumen <NUM> where it exits via openings (not shown) formed in the sidewall of the tubing <NUM> to enter the AR ring electrodes <NUM> and exits apertures <NUM> formed in the electrode side wall (<FIG>). It is understood that the distal portion <NUM> may carry any form of electrodes, including the aforementioned AR ring electrodes, impedance ring electrodes, and/or combinations thereof, as desired or appropriate.

The deflection puller wire <NUM> is provided for deflection of the intermediate shaft <NUM>. The deflection wire <NUM> extends through the central lumen <NUM> of the catheter body <NUM> (<FIG>) and the third lumen <NUM> of the intermediate section <NUM> (<FIG>). It is anchored at its proximal end in the control handle <NUM>, and at its distal end to a location at or near the distal end of the intermediate section <NUM> by a T-bar <NUM> (<FIG>) that is affixed to the sidewall of the tubing <NUM> by suitable material, e.g., polyurethane <NUM>. The puller wire <NUM> is made of any suitable metal, such as stainless steel or Nitinol, and is preferably coated with TEFLON® or the like. The coating imparts lubricity to the puller wire. The puller wire <NUM> may have a diameter ranging from about <NUM> to about <NUM> inch.

A second compression coil <NUM> is situated within the central lumen <NUM> of the catheter body <NUM> in surrounding relation to the puller wire <NUM> (<FIG>). The second compression coil <NUM> extends from the proximal end of the catheter body <NUM> to at or near the proximal end of the intermediate section <NUM>. The second compression coil <NUM> is made of any suitable metal, preferably stainless steel, and is tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of the second compression coil <NUM> is preferably slightly larger than the diameter of the puller wire <NUM>. A TEFLON® coating (not shown) on the puller wire allows it to slide freely within the second compression coil. Within the catheter body <NUM>, the outer surface of the second compression coil <NUM> is covered by a flexible, non-conductive sheath <NUM>, e.g., made of polyimide tubing. The second compression coil <NUM> is anchored at its proximal end to the outer wall <NUM> of the catheter body <NUM> by a proximal glue joint and to the intermediate section <NUM> by a distal glue joint.

Within the third lumen <NUM> of the intermediate section <NUM>, the puller wire <NUM> extends through a plastic sheath (not shown) , preferably of TEFLON®, which prevents the puller wire <NUM> from cutting into the wall of the tubing <NUM> of the intermediate section <NUM> when the intermediate section <NUM> is deflected.

Longitudinal movement of the contraction wire <NUM> relative to the catheter body <NUM>, which results in contraction of the spiral-helical form of the distal assembly <NUM>, is accomplished by suitable manipulation of the control handle <NUM>. Similarly, longitudinal movement of the deflection wire <NUM> relative to the catheter body <NUM>, which results in deflection of the intermediate section <NUM>, is accomplished by suitable manipulation of the control handle <NUM>. Suitable control handles for manipulating more than one wire are described, for example, in <CIT>, <CIT>, and <CIT>.

In one embodiment, the catheter includes a control handle <NUM> as shown in <FIG> and <FIG>. The control handle <NUM> includes a deflection control assembly that has a handle body <NUM> in which a core <NUM> is fixedly mounted and a piston <NUM> is slidably mounted over a distal region of the core <NUM>. The piston <NUM> has a distal portion that extends outside the handle body. A thumb knob <NUM> is mounted on the distal portion so that the user can more easily move the piston <NUM> longitudinally relative to the core <NUM> and handle body <NUM>. The proximal end of the catheter body <NUM> is fixedly mounted to the distal end of the piston <NUM>. An axial passage <NUM> is provided at the distal end of the piston <NUM>, so that various components, including lead wires <NUM>, <NUM>, contraction wire <NUM>, deflection wire <NUM>, position sensing cable assembly <NUM> and irrigation tubing <NUM> that extend through the catheter body <NUM> can pass into the control handle. The lead wires <NUM>, <NUM> can extend out the proximal end of the control handle <NUM> or can be connected to a connector that is incorporated into the control handle, as is generally known in the art. The irrigation tubing <NUM> can also extend out the proximal end of the control <NUM> for connection with an irrigation source (not shown) via a luer hub.

The proximal end of the deflection wire <NUM> enters the control handle <NUM>, and is wrapped around a pulley <NUM> and anchored to the core <NUM>. Longitudinal movement of the thumb knob <NUM> and piston <NUM> distally relative to the handle body <NUM> and core <NUM> draws the proximal end of the deflection wire <NUM> distally. As a result, the deflection wire <NUM> pulls on the side of the intermediate section <NUM> to which it is anchored, thereby deflecting the intermediate section in that direction. To release and straighten the intermediate section <NUM>, the thumb knob <NUM> is moved proximally which results in the piston <NUM> being moved proximally back to its original position relative to the handle body <NUM> and core <NUM>.

The control handle <NUM> is also used for longitudinal movement of the contraction wire <NUM> via a rotational control assembly. In the illustrated embodiment, the rotational control assembly includes a cam handle <NUM> and a cam receiver <NUM>. By rotating the cam handle in one direction, the cam receiver is drawn proximally to draw on the contraction wire <NUM>. By rotating the cam handle in the other direction, the cam receiver is advanced distally to release the contraction wire <NUM>. The contraction wire <NUM> extends from the catheter body <NUM> into the control handle <NUM>, through the axial passage in the piston <NUM> and through the core <NUM> to be anchored in an adjuster <NUM> by which tension on the contraction wire can be adjusted.

In one embodiment, the position sensor cable assembly <NUM> including a plurality of single axis sensors ("SAS") extends through the first lumen <NUM> of the distal assembly <NUM> (<FIG>), where each SAS occupies a known or predetermined position on the spiral-helical form of the distal assembly <NUM>. The cable assembly <NUM> extends proximally from the distal assembly <NUM> through the central lumen <NUM> of the connector section <NUM>, the fourth lumen <NUM> of the intermediate section <NUM> (<FIG>), the central lumen <NUM> of the catheter body <NUM> (<FIG>), and into the control handle <NUM>. Each SAS can be positioned with a known and equal spacing separating adjacent SASs. In the disclosed embodiment, the cable carries three SASs that are positioned under the distal-most AR electrode, the proximal-most AR electrode, and a mid AR electrode, for sensing location and/or position of the distal assembly <NUM>. The SASs enable the spiral-helical form to be viewed under mapping systems manufactured and sold by Biosense Webster, Inc. , including the CARTO, CARTO XP and NOGA mapping systems. Suitable SASs are described in <CIT>.

Claim 1:
An electrophysiology catheter comprising:
an elongated catheter body (<NUM>);
a contraction wire (<NUM>);
a distal assembly (<NUM>) configured for contraction by actuation of the contraction wire, the distal assembly having a shape-memory support member (<NUM>) having a <NUM>-D configuration, the distal assembly including a radially-constrictive tubing (<NUM>) surrounding the shape-memory support member and a coextensive portion of the contraction wire,
characterised in that the radially-constrictive tubing includes manufactured fibers formed from a liquid crystal polymer.