Patent Description:
Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity.

In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Once the catheter is positioned within the heart, the location of aberrant electrical activity within the heart is then located.

One location technique involves an electrophysiological mapping procedure whereby the electrical signals emanating from the conductive endocardial tissues are systematically monitored and a map is created of those signals. By analyzing that map, the physician can identify the interfering electrical pathway. A conventional method for mapping the electrical signals from conductive heart tissue is to percutaneously introduce an electrophysiology catheter (electrode catheter) having mapping electrodes mounted on its distal extremity. The catheter is maneuvered to place these electrodes in contact with the endocardium. By monitoring the electrical signals at the endocardium, aberrant conductive tissue sites responsible for the arrhythmia can be pinpointed.

For sensing by ring electrodes mounted on a catheter, lead wires transmitting signals from the ring electrodes are electrically connected to a suitable connector in the distal end of the catheter control handle, which is electrically connected to an ECG monitoring system and/or a suitable <NUM>-D electrophysiology (EP) mapping system, for example, CARTO, CARTO XP or CARTO <NUM>, available from Biosense Webster, Inc. of Irwindale, California.

Smaller and more closely-spaced electrode pairs allow for more accurate detection of near-field potentials versus far-field signals, which can be very important when trying to treat specific areas of the heart. For example, near-field pulmonary vein potentials are very small signals whereas the atria, located very close to the pulmonary vein, provide much larger signals. Accordingly, even when the catheter is placed in the region of a pulmonary vein, it can be difficult for the electrophysiologist to determine whether the signal is a small, close potential (from the pulmonary vein) or a larger, farther potential (from the atria). Smaller and closely-spaced bipoles permit the physician to more accurately remove far field signals and obtain a more accurate reading of electrical activity in the local tissue. Accordingly, by having smaller and closely-spaced electrodes, one is able to target exactly the locations of myocardial tissue that have pulmonary vein potentials and therefore allows the clinician to deliver therapy to the specific tissue. Moreover, the smaller and closely-spaced electrodes allow the physician to determine the exact anatomical location of the ostium/ostia by the electrical signal.

Increasing electrode density (for example, by increasing the plurality of electrodes carried on the catheter) also improves detection accuracy. However, the more electrodes that are carried on the catheter, especially with higher electrode density, the risk of electrodes touching and shorting increases. Moreover, there is always the desire to improve electrode tissue contact with highly-flexible electrode assembly structures that can make contact reliably but in a manner whereby the electrode-carrying structures behave in a controllable and predictable manner without perforating or injuring tissue. As the materials used to construct these structures become more flexible and delicate, the risk of deformation and, in particular, elongation of the smaller ring electrodes and their supporting structure during catheter assembly increases. Furthermore, as electrode assembly structures become more delicate, the risk of components detaching, kinking andtangling increases.

Accordingly, a need exists for an electrophysiology catheter with closely-spaced microelectrodes for high electrode density. There is also a need for an electrophysiology catheter having electrode-carrying structures that are delicate in construction to provide desired flexible yet be predictable in their movement upon tissue contact. There is a further need for an electrophysiology catheter that is constructed in a manner that minimizes the risk of components detaching, kinking and tangling.

<CIT> discusses a unibody support member that has a proximal mounting portion from which a support arm extends longitudinally from a distal edge of the mounting portion, the mounting portion having an open cylindrical body defining a lumen therethrough and each spine having an elongated tapered stem and an enlarged distal portion, the stem having a wider proximal end and a narrower distal end.

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.

Referring to <FIG>, in some embodiments a catheter <NUM> includes a catheter body <NUM>, an intermediate deflection section <NUM>, a distal electrode assembly <NUM>, and a control handle <NUM> proximal of the catheter body <NUM>. The distal electrode assembly <NUM> includes a plurality of spines <NUM>, with each spine supporting a plurality of microelectrodes <NUM>.

In some embodiments, the catheter body <NUM> comprises an elongated tubular construction, having a single, axial or central lumen <NUM>, as shown in <FIG>. 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. A presently preferred construction comprises an outer wall <NUM> made of a polyurethane, or PEBAX. The outer wall <NUM> comprises an imbedded braided mesh of high-strength steel, stainless steel or the like to increase torsional stiffness of the catheter body <NUM> so that, when the control handle <NUM> is rotated, the deflection section <NUM> of the catheter <NUM> rotates in a corresponding manner.

The outer diameter of the catheter body <NUM> is not critical. Likewise the thickness of the outer wall <NUM> is not critical, but is thin enough so that the central lumen <NUM> can accommodate components, including, for example, one or more puller wires, electrode lead wires, irrigation tubing, and any other wires and/or cables. In some embodiments, the inner surface of the outer wall <NUM> is lined with a stiffening tube <NUM>, which can be made of any suitable material, such as polyimide or nylon. The stiffening tube <NUM>, along with the braided outer wall <NUM>, provides improved torsional stability while at the same time minimizing the wall thickness of the catheter, thus maximizing the diameter of the central lumen <NUM>. As would be recognized by one skilled in the art, the catheter body construction can be modified as desired. For example, the stiffening tube can be eliminated.

In some embodiments, the intermediate deflection section comprises a shorter section of tubing <NUM>, which as shown in <FIG>, has multiple lumens <NUM>. In some embodiments, the tubing <NUM> is made of a suitable biocompatible material more flexible than the catheter body <NUM>. A suitable material for the tubing <NUM> is braided polyurethane, i.e., polyurethane with an embedded mesh of braided high-strength steel, stainless steel or the like. The outer diameter of the deflection section <NUM> is similar to that of the catheter body <NUM>. The plurality and size of the lumens are not critical and can vary depending on the specific application.

Various components extend through the catheter <NUM>. In some embodiments, the components include lead wires <NUM> for the distal electrode assembly <NUM>, one or more puller wires 23A and 23B for deflecting the deflection section <NUM>, a cable <NUM> for an electromagnetic position sensor <NUM> (see <FIG> and <FIG>) housed at or near a distal end of the deflection section <NUM>. In some embodiments, the catheter includes an irrigation tubing <NUM> for passing fluid to the distal end of the deflection section <NUM>. These components pass through the central lumen <NUM> of the catheter body <NUM>, as shown in <FIG>.

In the deflection section <NUM>, different components pass through different lumens <NUM> of the tubing <NUM> as shown in <FIG>. In some embodiments, the lead wires <NUM> pass through one or more lumens 31A, the first puller wire 23A passes through lumen 31B, the cable <NUM> passes through lumen 31C, the second puller 23B passes through lumen 31D, and the irrigation tubing <NUM> passes through lumen 31E. The lumens 31B and 31D are diametrically opposite of each other to provide bi-directional deflection of the intermediate deflection section <NUM>. Additional components can pass through additional lumens or share a lumen with the other aforementioned components, as needed.

Distal of the deflection section <NUM> is the distal electrode assembly <NUM> which includes a unibody support member <NUM> as shown in <FIG>. In some embodiments, the unibody support member <NUM> comprises a superelastic material having shape-memory, i.e., that can be temporarily straightened or bent out of its original shape upon exertion of a force and is capable of substantially returning to its original shape in the absence or removal of the force. One suitable material for the support member 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. A nickel/titanium alloy is nitinol, which has excellent shape memory, together with ductility, strength, corrosion resistance, electrical resistivity and temperature stability.

In some embodiments, the member <NUM> is constructed and shaped from an elongated hollow cylindrical member, for example, with portions cut (e.g., by laser cutting) or otherwise removed, to form a proximal portion or stem <NUM> and the elongated bodies of the spines <NUM> which emanate from the stem longitudinally and span outwardly from the stem. The stem <NUM> defines a lumen <NUM> therethrough for receiving a distal end portion 30D of the multi-lumened tubing <NUM> (see <FIG>) of the deflection section <NUM>, and various components, as further discussed below, which are either housed in the stem <NUM> or extend through the lumen <NUM>.

Each spine <NUM> of the member <NUM> has an enlarged distal portion <NUM>, and each spine has a wider proximal end and a narrower distal end. In some embodiments, as shown in <FIG>, <FIG>, <FIG>, the spine is linearly tapered for "out-of-plane" flexibility that varies along it length (see arrows A1 in <FIG>), including flexibility that increases toward the distal end <NUM>. In some embodiment, one or more spines <NUM> have a proximal portion 17P with a uniform width W1, a distal portion 17D1 with continuous linear taper defined by taper lines T1 (see <FIG>), and a more distal portion 17D2 with a uniform width W2 < W1. The distal portions 17D1 had a continuously gradual increase in flexibility so that the spines can adopt a predetermined form or curvature when the distal portions <NUM> come into contact with tissue. The resulting spines with a relatively more rigid proximal portion and a relatively more flexible distal portion help prevent the spines from crossing and overlapping each other during use.

In some embodiments, one or more spines <NUM> have a noncontinuous linear taper between the ends <NUM> and <NUM>, as shown in <FIG>, <FIG>, <FIG>. The noncontinuous linear taper includes one or more narrower or indented portions <NUM> that are strategically positioned along the spine to interrupt an otherwise continuous linear taper, defined by taper T2 between the stem <NUM> and the enlarged distal portion <NUM>. Each indented portion <NUM> has a width W (see <FIG>) that is lesser than the width WD of a more distal portion and also lesser than the width WP of a more proximal portion where width WD < width WP. Each indented portion <NUM> thus advantageously allows that region of the spine to have a different flexibility than immediately adjacent (distal and proximal) portions <NUM> of the spine, and to provide a degree of independent flexibility between the portions separated by the indented portion <NUM> (see <FIG>). Accordingly, these spines are allowed to exhibit markedly greater flexibility and hence tighter or more acute curvatures in the region of the indented portions <NUM> relative to the portions <NUM> of the spines when the distal portions <NUM> come into contact with tissue.

In some embodiments, each spine (between the distal end of the stem <NUM> and the distal end of the spine) has a length ranging between about <NUM> to <NUM>, or between about <NUM> and <NUM>, a width ranging between about <NUM> inches and <NUM> inches. In some embodiments, the indented portion <NUM> has a length ranging between about <NUM>%-<NUM>% of the length of the spine, and a width W ranging between about <NUM>%-<NUM>% of immediately adjacent widths, with its leading proximal edge located at about <NUM>%-<NUM>% of the length of the spine, measured from the distal end of stem <NUM>.

To further facilitate microelectrode contract with tissue along the entire length of the spine, each spine <NUM> has a preformed configuration or curvature, accomplished by, for example, heat and a molding fixture. One or more spines <NUM> have at least two different preformed curvatures C1 and C2, as shown in <FIG>, with segment S1 with preformed curvature C1 defined by radius R1 and segment S2 with preformed curvature C2 defined by radius R2, wherein radius R1 < R2 and the curvatures C1 and C2 are generally in opposition direction of each other so that the spines of the unibody support member <NUM> has a generally forward-facing concavity that resembles an open umbrella. As shown in <FIG> (with only two spines shown for purposes of clarity), when the spine distal ends come in contact with an illustrative surface SF, the preformed spines transition from their neutral configuration N (shown in broken lines) into their adaptive or temporarily "deformed" configuration A which may include a "crouched" profile (compared to their neutral configuration) that may be better suited for a region of heart tissue with undulations. Advantageously, the unibody support member <NUM> maintains its generally forward-facing concave configuration without turning inside out upon tissue contact, like an umbrella upturning in strong wind.

In some embodiments, one or more spines <NUM> have at least a curved segment and a linear segment. In some embodiments, one or more spines have at least two different preformed curvatures along its length. For example, as shown in <FIG>, one or more spines <NUM> have a first segment SA with preformed curvature CA defined by radius RA, a second segment SB with preformed curvature CB defined by radius RB, and a third segment SC that is linear, wherein radius RA < radius RB. As shown in <FIG> (with only two spines shown for purposes of clarity), when the spine distal ends come in contact with an illustrative surface SF, the preformed spines transition from their neutral configuration N into their adaptive or temporarily "deformed" configuration A which may include a deeper concavity (compared to their neutral configuration) that may be better suited for a region of heart tissue with a convexity.

As another example, as shown in <FIG>, one or spines 17D have a first segment SJ with preformed curvature CJ defined by radius RJ, a second segment SK that is linear, and a third segment SL with preformed curvature CL defined by radius RL, wherein radius RJ < radius RL. As shown in <FIG> (with only two spines shown for purposes of clarity), when the spine distal ends come in contact with an illustrative surface SF, the preformed spines transition from their neutral configuration N into their adaptive or temporarily "deformed" configuration A which may include a lower profile (compared to their neutral configuration) that may be better suited for a flatter region of heart tissue.

With reference to <FIG>, in some embodiments, the unibody support member <NUM> and its spines <NUM> can be defined by a plurality of parameters, including the following, for example:.

Notably, in some embodiments of the unibody support member <NUM>, the proximal (or first) preformed curvature is opposite of the distal (or second) preformed curvature so the spines <NUM> of the distal electrode assembly <NUM> can maintain its general concavity and remain forward-facing upon tissue contact, without inverting, while the highly-flexible spines allow the assembly to have a pliability or "give" that prevents the distal tips of the spines from perforating or otherwise causing damage to tissue upon contact and when the distal electrode assembly is pressed toward the tissue surface to ensure tissue contact by each of the spines <NUM>. Moreover, in some embodiments, the indented portion <NUM> may span between the proximal and distal preformed curvatures so that each of three portions (proximal, indented and distal) of the spines can behave differently and have a degree of independence in flexibility of each other in response to tissue contact and the associated pressures applied by the operator user of the catheter.

It is understood that the foregoing figures illustrate exaggerated deformities and curvatures of the spines for ease of discussion and explanation, whereas actual deformities and curvatures may be much more subtle and less acute.

In some embodiments, one or more spines <NUM> are also configured with a hinge <NUM> for in-plane (side-to-side) deflection. As shown in <FIG>, a spine <NUM> can have a plurality of notches or recesses along opposing lateral edges, including expandable recess <NUM> (e.g., in the form of slits <NUM> and circular openings <NUM>) along one edge 85a and compressible recess <NUM> (e.g., in the form of slots <NUM> and circular openings <NUM>) along an opposite edge 85b, forming a hinge <NUM> for more in-plane deflection along those edges. In the embodiments of <FIG>, uni-deflection occurs toward the edge 85b of the spine <NUM>. However, it is understood that where compressible recess <NUM> are formed along both the edges 85a and 85b the spine <NUM> has bi-directional deflection toward either edge 85a or 85b. Suitable hinges are described in <CIT>.

As shown in <FIG>, each spine <NUM> of the distal electrode assembly <NUM> is surrounded along its length by a non-conductive spine cover or tubing <NUM>. In some embodiments, the non-conductive spine cover <NUM> comprises a very soft and highly flexible biocompatible plastic, such as PEBAX or PELLATHANE, and the spine cover <NUM> is mounted on the spine with a length that is coextensive with the spine as between the stem <NUM> and the the enlarged distal portion <NUM>. A suitable construction material of the spine cover <NUM> is sufficiently soft and flexible so as generally not to interfere with the flexibility of the spines <NUM>.

In some embodiments, each covered spine <NUM> along its length has a diameter D of less than <NUM> french, preferably a diameter of less than <NUM> french, and more preferably a diameter of <NUM> french, (e.g., between about <NUM>" and <NUM>" in diameter).

Each spine <NUM> includes an atraumatic distal cover or cap <NUM> (see <FIG>) encapsulating the enlarged distal portion <NUM>. In some embodiments, the cover <NUM> comprises an biocompatible adhesive or sealant, such as polyurethane, which has a bulbous configuration to minimize injury to tissue upon contact or the application of pressure against tissue. The formation of the cover <NUM> includes a bridging portion <NUM> of the adhesive or sealant that passes through the through-hole <NUM> in the enlarged distal portion <NUM> and advantageously creates a mechanical lock that secures the cover <NUM> on the distal portion <NUM> and minimizes the risk of the cover <NUM> detaching from the enlarged distal portion <NUM>.

Each spine <NUM> carries a plurality of microelectrodes <NUM>. The plurality and arrangement of microelectrodes can vary depending on the intended use. In some embodiments, the plurality ranges between about <NUM> and <NUM>, although it is understood that the plurality may be greater or lesser. In some embodiments, each microelectrode has a length L of less than <NUM>, for example, ranging between about <NUM> and <NUM>, and, for example, measuring about <NUM>, <NUM> or about <NUM>. In some embodiment, the distal electrode assembly <NUM> has an area coverage greater than about <NUM>/cm<NUM>, for example, ranging between about <NUM>/cm<NUM> and <NUM>/cm<NUM>. In some embodiments, the distal electrode assembly <NUM> has a microelectrode density greater than about <NUM> microelectrodes/cm<NUM>, for example, ranging between about <NUM> microelectrodes/cm<NUM> and <NUM> microelectrodes/cm<NUM>.

In some embodiments, the distal electrode assembly <NUM> has eight spines, each of about <NUM> in length and carrying eight microelectrodes for a total of <NUM> microelectrodes, each with microelectrode having a length of about <NUM>, wherein the assembly <NUM> has an area coverage of about <NUM>/cm<NUM>, and a microelectrode density of about <NUM> microelectrodes/cm<NUM>.

In some embodiments, the distal electrode assembly <NUM> has eight spines, each of about <NUM> in length and carrying six microelectrodes for a total of <NUM> microelectrodes, each with microelectrode having a length of about <NUM>, wherein the assembly <NUM> has an area coverage of about <NUM>/cm<NUM>, and a microelectrode density of about <NUM> microelectrodes/cm<NUM>.

The microelectrodes <NUM> on a spine <NUM> may be arranged with a variety of spacing between them as either monopoles or bipoles, with the spacing measured as the separation between respective leading edges of adjacent microelectrodes or microelectrode pairs. As monopoles, the microelectrodes <NUM> can be separated by a distance S1 ranging between about <NUM> and <NUM>, with reference to <FIG>. As bipoles, adjacent pairs of microelectrodes <NUM> can be separated by a distance S2 ranging between <NUM> and <NUM>, with reference to <FIG>.

In some embodiments, six microelectrodes are arranged as three bipole pairs, with a spacing S1 of <NUM> between proximal edges of a bipole pair, and a spacing S2 of <NUM> between proximal edges of adjacent bipole pairs, with reference to <FIG>, which may be referred to generally as a "<NUM>-<NUM>-<NUM>" configuration. Another configuration, referred to as a "<NUM>-<NUM>-<NUM>-<NUM>-<NUM>" configuration, has three bipole pairs, with a spacing S1 of <NUM> between proximal edges of a bipole pair, and a spacing S2 of <NUM> between proximal edges of adjacent bipole pairs.

In some embodiments, six microelectrodes are arranged as monopoles, with a spacing S1 of <NUM> between proximal edges of adjacent monopoles, with reference to <FIG>. which may be referred to as "<NUM>-<NUM>-<NUM>-<NUM>-<NUM>" configuration. In some embodiments, the space S1 is about <NUM> and thus is refered to as a "<NUM>-<NUM>-<NUM>-<NUM>-<NUM>" configuration.

In some embodiments, the most proximal microelectrode 18P of each spine is carried on the spine at a different location from the most proximal microelectrode 18P of adjacent spines. As illustrated in <FIG>, whereas the spacing between microelectrodes on any one spine may be uniform throughout the distal electrode assembly, the microelectrodes along any one spine is staggered (or offset)relative to the microelectrodes along adjacent spines. For example, the distance D1 between the most proximal microelectrode 18P and the end of the stem <NUM> for spines 17A, 17C, 17E and <NUM> is greater than the distance D2 between the most proximal electrodes 18P and the end of the stem <NUM> for spines 17B, 17D, <NUM> and <NUM>. This staggered configuration minimizes the risk of microelectrodes on adjacent spines from touching and shorting, especially when an operator sweeps the distal electrode assembly against tissue.

Components of construction and assembly of the junction between the distal electrode assembly and the distal end portion of the deflection section <NUM> are described in <CIT>, <CIT>, <CIT>, and <CIT>. As shown in <FIG>, the stem <NUM> of the unibody support member <NUM> receives a narrowed distal end 30D of the multi-lumened tubing <NUM> of the deflection section <NUM>. Surrounding the stem <NUM> circumferentially is a nonconductive sleeve <NUM> that is coextensive with the stem between its proximal end and its distal end. Distal end 68D of the sleeve <NUM> extends over the proximal ends 28P of the nonconductive spine tubings <NUM> so as to help secure the tubings <NUM> on the spines <NUM>.

Proximal of the distal end 30D is a housing insert <NUM> that is also received and positioned in the lumen <NUM> of the stem <NUM> of the unibody support member <NUM>. The housing insert <NUM> has a length in the longitudinal direction that is shorter than the length of the stem <NUM> so that it does not protrude past the distal end of the stem <NUM>. The housing insert <NUM> is configured with one or more lumens. One lumen <NUM> may have a noncircular cross-section, for example, a cross-section that generally resembles a "C" or an elongated kidney-bean, and another lumen <NUM> may have a circular cross-section, as shown in <FIG>, so that the lumens can nest with each other to maximize the size of the lumens and increase space efficiency within the housing insert <NUM>. Components passing through the more lumen <NUM> are not trapped in any one location or position and thus have more freedom to move and less risk of breakage, especially when segments of the catheter are torqued and components are twisted.

In some embodiments, the electromagnetic position sensor <NUM> (at the distal end of the cable <NUM>) is received in the lumen <NUM>. Other components including, for example, the irrigation tubing <NUM>, and the lead wires <NUM> for the microelectrodes <NUM> on the distal electrode assembly <NUM> (and lead wires <NUM> for any ring electrodes <NUM>, <NUM>, and <NUM> proximal of the spines <NUM>) pass through the lumen <NUM>. In that regard, the housing insert <NUM> serves multiple functions, including aligning and positioning the various components within the stem <NUM> of the unibody support member <NUM>, provides spacing for and separation between these various components, and serves as a mechanical lock that reinforces the junction between the distal end of the deflection section <NUM> and the distal electrode assembly <NUM>. In the latter regard, the junction, during the assembly and use of the catheter, can be subject to a variety of forces that can torque or pull on the junction. Torque forces, for example, can pinch the irrigation tubing <NUM> to impede flow, or cause breakage of the lead wires <NUM> and <NUM>. To that end, the junction is advantageously assembled in a configuration with the housing insert <NUM> to form a mechanical lock, as explained below.

The housing insert <NUM> may be selectively configured with an outer diameter that smaller than the inner circumference of the lumen <NUM> of the stem <NUM> by a predetermined amount. This creates an appreciable void in the lumen <NUM> that is filled with a suitable adhesive <NUM>, such as polyurethane, to securely affix the housing insert <NUM> inside the lumen <NUM> and to the distal end of the multi-lumened tubing <NUM> so as to minimize, if not prevent, relative movement between the insert <NUM> and the stem <NUM>. The housing insert <NUM> protects the components it surrounds, including the electromagnetic position sensor <NUM> (and its attachment to the cable <NUM>), the irrigation tubing <NUM>, and the lead wires <NUM> and <NUM>, and provides a larger and more rigid structure to which the stem <NUM> is attached. To that end, the housing insert <NUM> may even have a noncircular/polygonal outer cross-section and/or a textured surface to improve the affixation between the housing insert <NUM> and the adhesive <NUM>.

To facilitate the application of the adhesive into the void, the stem <NUM> is formed with an opening <NUM> in its side wall at a location that allows visual and mechanical access to the housing insert <NUM> after it has been inserted into the lumen <NUM> of the stem <NUM>. Visual inspection of the lumen <NUM> and components therein during assembly of the junction is provided through the opening <NUM>. Whereas any adhesive applied to the outer surface of the housing insert <NUM> before insertion into the lumen <NUM> may squirt out of the stem <NUM> during insertion, additional adhesive may be advantageously applied into the lumen <NUM> through the opening <NUM> to fill the void and thus securely affix the housing insert <NUM> to the stem <NUM> and the distal end portion of the multi-lumened tubing <NUM>. The combination of the housing insert <NUM> and its spatially-accommodating lumen <NUM> provides a more integrated and less vulnerable junction between the distal electrode assembly <NUM> and the deflection section <NUM>.

In some embodiments, the catheter <NUM> includes the irrigation tubing <NUM> whose distal end 27D is generally coextensive with the distal end of the stem <NUM> of the unibody support member <NUM>. As such, irrigation fluid, e.g., saline, is delivered to the distal electrode assembly <NUM> from a remote fluid source that provides irrigation fluid via a luer hub <NUM> (<FIG>) via the irrigation tubing <NUM> that extends through the control handle <NUM>, the center lumen <NUM> of the catheter body <NUM> (<FIG>), and the lumen 31E of the tubing <NUM> of the deflection section <NUM> (<FIG>), where it exits the distal end of the irrigation tubing <NUM> at the distal end of the stem <NUM> of the unibody support member <NUM>, as shown in <FIG> and <FIG>. A suitable adhesive <NUM>, such as polyurethane, plugs and seals the lumen <NUM> around the distal end of the irrigation tubing <NUM>. In some embodiments, the catheter is without irrigation and the distal end of the stem <NUM> of the unibody support member <NUM> is sealed in its entirety by the adhesive or sealant <NUM>, such as polyurethane, as shown in <FIG>.

<FIG> illustrates an embodiment wherein the nonconductive spine tubings <NUM> include reinforcing tensile members <NUM>. As understood by one of ordinary skill in the art, the microelectrodes <NUM> are mounted on the spine cover or tubing <NUM> wherein an elongated tubular mandrel (not shown) is positioned in the lumen of the spine cover <NUM> to support the microelectrodes <NUM> while they are rotationally swaged onto the spine cover <NUM>. The microelectrodes <NUM> may have a circular cross-section, including the configuration of a circle or an oval. To prevent or at least minimize undesirable deformation of the microelectrodes <NUM> and the spine cover <NUM> during swaging, including elongation in the longitudinal direction, the spine cover <NUM> on which the microelectrodes are carried and swaged onto includes reinforcing tensile members <NUM>, as shown in <FIG>. Tensile members <NUM>, for example, wires or fibers (used interchangeably herein), are embedded (for example, during extrusion of the tensile members) in the side wall <NUM> of the tubing. The tensile members <NUM> may be embedded in the nonconductive cover extrusion in a uniaxial or braided pattern, extending in the longitudinal direction or at least having portions extending in the longitudinal direction. As such, the tensile members serve to resist undesirable elongation of particularly soft and flexible spine cover <NUM> and the microelecrodes <NUM> in the longitudinal direction. Examples of suitable tensile members include VECTRAN, DACRON, KEVLAR or other materials with low elongation properties. The plurality of the reinforcing tensile members is not critical. In some embodiments, the plurality may range between two and six that are arranged in an equi-radial configuration. In the illustrated embodiment, the spine cover <NUM> includes four tensile members at <NUM>, <NUM>, <NUM> and <NUM> degrees about the side wall <NUM>.

In some embodiments, distal ends of the tensile members <NUM> are anchored in the bulbous cover <NUM> encapsulating the enlarged distal portion of the spines <NUM> and/or rings 99D, as shown in <FIG>, maybe compressed or clamped on over the spine cover <NUM> and spine <NUM>. In some embodiments, proximal ends of the tensile members <NUM> are coextensive with the proximal end of the spine cover <NUM>, and may also be anchored by rings 99P (see <FIG> and <FIG>).

In some embodiments, the tensile members <NUM> have a much greater length. With reference to <FIG>, <FIG>, <FIG> and <FIG>, the tensile members <NUM> extend through openings <NUM> formed in the stem <NUM> of the unibody support member <NUM> and into the lumen <NUM> of the stem <NUM>. The tensile members <NUM> then extend through the lumen <NUM> of the housing insert <NUM>, a lumen 31F of the tubing <NUM> of the deflection section <NUM>, and the center lumen <NUM> of the catheter body <NUM>, and into the control handle <NUM>. Proximal ends of the tensile members <NUM> are configured for manipulation by an operator to deflect the spines <NUM> of the distal electrode assembly <NUM> so they can individually function as "fingers. " In that regard, the tensile members may be formed in the side wall of the tubing <NUM> in a manner that allows longitudinal movement relative to the tubing <NUM> so that any one or more tensile members can be drawn proximally to bend or deflect the respective spine toward the side along which those tensile members extend. As such, an operator is able to manipulate one or more spines for individual deflection as needed or desired, including when the distal electrode assembly is in contact with an uneven tissue surface where one or more spines need adjustment for better tissue contact.

With reference to <FIG>, <FIG>, the catheter <NUM> of the present invention is shown in use in all four chambers of the heart, namely, the left and right atria and the left and right ventricles, with the spines of the distal electrode assembly <NUM> readily adapting and conforming to various contours and surfaces of the heart tissue anatomy, including, for example, inside a pulmonary vein, and on the posterior wall of the right atrium, and the anterior, inferior and/or lateral walls of the left and right ventricles, and the apex. The preformed configurations of the spines advantageously facilitate contact between the microelectrodes carried on the spines and tissue regardless of the anatomy of the surface.

In some embodiments, the catheter <NUM> has a plurality of ring electrodes proximal of the distal electrode assembly <NUM>. In addition to the ring electrode <NUM>, as shown in <FIG>, the catheter carries another ring electrode <NUM> more proximal than the ring electrode <NUM>, and another ring electrode <NUM> more proximal than the ring electrode <NUM>. Lead wires <NUM> are provided for these ring electrodes. In some embodiments, the ring electrode <NUM> is located near the distal end 30D of the multi-lumened tubing <NUM> of the deflection section <NUM>, and ring electrode <NUM> is separated from the ring electrode <NUM> by a distance S ranging between about <NUM> and <NUM>. A respective lead wire <NUM> is connected to the ring electrode <NUM> via opening <NUM> formed in the stem <NUM> of the unibody support member <NUM>, and in the sleeve <NUM>. Respective lead wires <NUM> for ring electrodes <NUM> and <NUM> are connected to via openings (not shown) formed in these side wall of the tubing <NUM> of the deflection section <NUM>.

Claim 1:
An electrophysiology catheter comprising:
an elongated body (<NUM>);
a distal electrode assembly (<NUM>) comprising:
a proximal portion (<NUM>);
a plurality of spines (<NUM>), each spine having a linear taper with a wider proximal end and a narrower distal end, and an enlarged distal portion (<NUM>) having a through-hole (<NUM>);
a plurality of spine covers (<NUM>), each spine cover surrounding a respective spine; and
a plurality of atraumatic distal covers (<NUM>), each atraumatic distal cover encapsulating a respective enlarged distal portion and including a bridging portion (<NUM>) of adhesive or sealant that passes through the through-hole (<NUM>) of the respective enlarged distal portion (<NUM>).