INVENTORS:

Lior BOTZER

Cesar FUENTES-ORTEGA

Stuart WILLIAMS

PRIORITY

[0001] This application claims the benefits under 35USC§120 as a continuation-in-part of previously filed US Patent Application S.N. 15/890318 filed on February 6, 2018, titled as“CATHETER WITH INCREASED ELECTRODE DENSITY SPINE ASSEMBLY

HAVING REINFORCED SPINE COVERS” with Attorney Docket BI05891 USNP, which prior application is hereby incorporated by reference into this application as if set forth in full in this application.

BACKGROUND

[0002] 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.

[0003] In use, the microelectrode 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.

[0004] 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 microelectrodes mounted on its distal extremity. The catheter is maneuvered to place these

microelectrodes in contact with the endocardium. By monitoring the electrical signals at the endocardium, aberrant conductive tissue sites responsible for the arrhythmia can be pinpointed.

[0005] For sensing by ring microelectrodes mounted on a catheter, lead wires transmitting signals from the ring microelectrodes 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 3-D electrophysiology (EP) mapping system, for example, CARTO, CARTO XP or CARTO 3, available from Biosense Webster, Inc. of Irwindale, California.

[0006] Smaller and more closely-spaced microelectrode 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 microelectrodes, 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 microelectrodes allow the physician to determine the exact anatomical location of the ostium/ostia by the electrical signal.

[0007] Increasing microelectrode density (for example, by increasing the plurality of microelectrodes carried on the catheter) also improves detection accuracy. However, the more microelectrodes that are carried on the catheter, especially with higher

microelectrode density, the risk of microelectrodes touching and shorting increases.

Moreover, there is always the desire to improve microelectrode tissue contact with highly- flexible microelectrode assembly structures that can make contact reliably but, in a manner, whereby the microelectrode-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 microelectrodes and their supporting structure during catheter assembly increases. Furthermore, as microelectrode assembly structures become more delicate, the risk of components detaching, kinking and tangling increases.

[0008] Accordingly, a need exists for an electrophysiology catheter with closely-spaced microelectrodes for high microelectrode density. There is also a need for an

electrophysiology catheter having microelectrode-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, and reinforces the spine construction to minimize deformation, including elongation of soft spine covers and of microelectrodes carried thereon.

SUMMARY OF THE DISCLOSURE

[0009] The present invention is directed to an electrophysiology catheter with a distal microelectrode assembly carrying very small and closely-spaced microelectrodes on a plurality of divergent spines that can flexibly spread over tissue surface area for

simultaneously detecting signals at multiple locations with minimized detection of undesirable noise, including far-field signals. The distal microelectrode assembly is configured to conform to different anatomies of tissue in the atrial cavities of the heart.

The spines have curved segments or curved segments with linear segments for a wide range of adaptability to different tissue surfaces while providing mechanical advantages at distinct segments for improved flexibility and rigidity to facilitate better tissue contact.

Each spine has a generally tapering configuration from its proximal end to its distal end for providing a stronger, more rigid proximal base and more flexible distal ends for improved flexibility characteristics while minimizing the risk of spines touching or entangling.

[0010] In some embodiments, an electrophysiology catheter has an elongated body and a distal microelectrode assembly. The distal microelectrode assembly has a proximal stem, a plurality of spines emanating from the stem and a plurality of nonconductive spine covers, each surrounding a respective spine, each spine cover having a plurality of tensile members embedded in a sidewall of the cover.

[0011] In some embodiments, the tensile members extend in the longitudinal direction.

[0012] In some embodiments, the tensile members have a portion extending in the longitudinal direction. [0013] In some embodiments, the tensile members include wires.

[0014] In some embodiments, tensile members include fibers.

[0015] In some embodiments, an electrophysiology catheter has an elongated body and a distal microelectrode assembly. The distal microelectrode assembly has a proximal stem and a plurality of spines, each spine having an enlarged distal portion, the enlarged distal portion having a through-hole. The distal microelectrode assembly also has a plurality of nonconductive spine covers, each surrounding a respective spine. The distal microelectrode assembly further has a cap cover encapsulating the enlarged distal portion, the cap cover having a portion extending through the through-hole.

[0016] In some embodiments, an electrophysiology catheter has an elongated body and a distal microelectrode assembly. The distal microelectrode assembly has a proximal stem and a plurality of at least eight spines, each spine having a first section with a first preformed curvature defined by a first radius, and a linear section. The distal

microelectrode assembly also has a plurality of nonconductive spine covers and a plurality of microelectrodes, with at least one microelectrode on each spine.

[0017] In some embodiments, each spine includes a second section with a second preformed curvature defined by a second radius different from the first radius, the second section with the second preformed curvature being distal of the first section with the first preformed curvature.

[0018] In some embodiments, the first radius is smaller than the second radius.

[0019] In some embodiments, the second preformed curvature is opposite of the first preformed curvature.

[0020] In some embodiments, the second section with the second preformed curvature is distal of the first section with the first preformed curvature. [0021] In some embodiments, the linear section is between the first section with the first preformed curvature and the second section with the second preformed curvature.

[0022] In some embodiments, the second section with the linear section is distal of the second section with the second preformed curvature.

[0023] In some embodiments, each covered spine has an outer circumference less than 3 French.

[0024] In some embodiments, the outer circumference is about 2.6 French.

[0025] In some embodiments, an electrophysiology catheter has an elongated body, and a distal microelectrode assembly. The distal microelectrode assembly has a proximal portion, and a plurality of spines, each spine having a linear taper with a wider proximal end and a narrower distal end. The distal microelectrode assembly also has a plurality of nonconductive spine covers, each nonconductive spine cover surrounding a respective spine.

[0026] In some embodiments, the linear taper is continuous.

[0027] In some embodiments, the linear taper is noncontinuous.

[0028] In some embodiments, the noncontinuous linear taper includes an indented portion with a width lesser than a width of a more proximal stem and a width of a more distal portion.

[0029] In some embodiments, a spine has a hinge along a lateral edge configured for in-plane deflection of the spine.

[0030] In some embodiments, an electrophysiology catheter has an elongated body and a distal microelectrode assembly. The distal microelectrode assembly has a proximal stem, a plurality of at least eight spines, each spine having a linear taper with a wider proximal end and a narrower distal end. The distal microelectrode assembly also has a plurality of nonconductive spine covers, each nonconductive cover surrounding a respective spine. The distal microelectrode assembly further has a plurality of

microelectrodes, the plurality being at least about 48, each microelectrode having a length of about 480 pm.

[0031] In some embodiments, the microelectrodes on each spine are separated by a distance ranging between about 1 mm and 3mm, as measured between leading edges of the microelectrodes.

[0032] In some embodiments, the distance is about 2 mm.

[0033] In some embodiments, the microelectrodes on each spine are arranged as bipole pairs, with leading edges of microelectrodes within a pair separated by a first distance ranging between about 1 mm and 3mm, and with leading edges of leading microelectrodes between pairs separated by a second distance ranging between 1 mm and 6mm.

[0034] In some embodiments, the first distance is about 2 mm and the second distance is about 6 mm.

[0035] In some embodiments, the plurality of microelectrodes equals about 64.

[0036] In some embodiments, the plurality of microelectrodes equals about 72.

[0037] In some embodiments, a first ring microelectrode is carried on the proximal stem of the distal microelectrode assembly, and a second and a third ring microelectrodes carried on a distal portion of the elongated body.

[0038] In some embodiments, an electrophysiology catheter has an elongated body, and a distal microelectrode assembly. The distal microelectrode assembly has a proximal stem defining a circumference around the longitudinal axis. The distal microelectrode assembly also has a plurality of spines emanating from the proximal stem and diverging at their distal ends, the plurality of spines alternating between first spines and second spines around the circumference of the stem. The distal microelectrode assembly further has a plurality of nonconductive spine covers, each spine cover surrounding a respective spine, and a plurality of microelectrodes having a staggered configuration on the first spines and the second spines, wherein a most proximal microelectrode on each first spine is positioned at a greater distance from the proximal stem, and a most proximal

microelectrode on each second spine is positioned at a lesser distance from the proximal stem.

[0039] In some embodiments, the distal microelectrode assembly comprises at least four first spines and four second spines, and each spine carries eight microelectrodes.

[0040] In some embodiments, each microelectrode has a length of about 480 pm.

[0041] In some embodiments, the microelectrodes on each spine are separated by a distance ranging between about 1 mm and 3mm, as measured between leading edges of the microelectrodes.

[0042] In some embodiments, the distance is about 2 mm.

[0043] In some embodiments, the microelectrodes on each spine are arranged as bipole pairs, with leading edges of microelectrodes within a pair separated by a first distance ranging between about 1 mm and 3mm, and with leading edges of leading microelectrodes between pairs separated by a second distance ranging between 1 mm and 6mm.

[0044] In some embodiments, the first distance is about 2 mm and the second distance is about 6 mm.

[0045] In some embodiments, an electrophysiology catheter has an elongated body and a distal microelectrode assembly. The distal microelectrode assembly has a proximal stem having a side wall having an inner surface defining a lumen, the side wall having an opening. The distal microelectrode assembly also has a plurality of spines emanating from the proximal stem and diverging at their distal ends, and a plurality of nonconductive cover, each nonconductive cover surrounding a respective spine. The distal

microelectrode assembly further has a plurality of microelectrodes on each spine, and a housing insert received in the lumen of the stem, the housing insert having an outer surface leaving a void between the outer surface and the inner surface of the stem. An adhesive fills the void between the inner surface of the proximal stem and the outer surface of the housing insert, the adhesive having a portion passing through the opening in the sidewall of the proximal stem.

[0046] In some embodiments, the adhesive has a second layer coating an outer surface of the stem and sealing the opening in the sidewall of the proximal stem.

[0047] In some embodiments, the housing insert has a lumen with a cross-section having an elongated kidney bean-shaped configuration.

[0048] In some embodiments, the housing insert has a lumen with a cross-section having a C-shaped configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] 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. [0050] FIG. 1 is a perspective view of a catheter of the present invention, according to one embodiment.

[0051] FIG. 2 is an end cross-sectional view of a catheter body of the catheter of FIG.

1 .

[0052] FIG. 3 is an end cross-sectional view of a deflection section of the catheter of FIG. 1

[0053] FIG. 4 is a perspective view of a unibody support member, according to one embodiment.

[0054] FIG. 5A is a side view of a unibody support member, according to one embodiment.

[0055] FIG. 5B is a detailed view of the unibody support member of FIG. 5A.

[0056] FIG. 5C is an end cross-sectional view of the unibody support member of FIG. 5A, taken a line C— C.

[0057] FIG. 5D is a detailed view of an enlarged distal portion of a spine of FIG. 5A.

[0058] FIG. 5E is a detailed view of an end cross-sectional view of a spine of FIG. 5A.

[0059] FIG. 6A is a side view of a unibody support member, according to one embodiment.

[0060] FIG. 6B is a detailed view of the unibody support member of FIG. 6A.

[0061] FIG. 6C is a detailed view of a distal portion of the spine of FIG. 6B.

[0062] FIG. 6D is a detailed view of an enlarged distal portion of a spine of FIG. 6A.

[0063] FIG. 6E is an end cross-sectional view of the unibody support member of FIG. 6B, taken along line E— E.

[0064] FIG. 6F is a detailed view of an end cross-sectional view of a proximal portion of the spine of FIG. 6B. [0065] FIG. 6G is a detailed view of an end cross-sectional view of a distal portion of the spine of FIG. 6B.

[0066] FIG. 7 A is a side view of a unibody support member, according to one embodiment.

[0067] FIG. 7B is a side view of the unibody support member of FIG. 7A, in tissue contact.

[0068] FIG. 8A is a side view of a unibody support member, according to another embodiment.

[0069] FIG. 8B is a side view of the unibody support member of FIG. 8A, in tissue contact.

[0070] FIG. 9A is a side view of a unibody support member, according to yet another embodiment.

[0071] FIG. 9B is a side view of the unibody support member of FIG. 9A, in tissue contact.

[0072] FIG. 10 is a side view of a unibody support member, according to one embodiment, illustrated to show different parameters.

[0073] FIG. 11 A is a top plan view of a spine with hinge formations, according to one embodiment.

[0074] FIG. 11 B is a top plan view of a spine with hinge formations, according to another embodiment.

[0075] FIG. 12A is a side view of a covered spine, according to one embodiment,

[0076] FIG. 12B is a side view of a covered spine, according to another embodiment.

[0077] FIG. 13A is a front view of a distal microelectrode assembly, according to one embodiment. [0078] FIG. 13B illustrates the assembly of Fig. 13A in a side view abutting a flat surface.

[0079] FIG. 13C or FIG. 13E illustrates a view of two variations of the assembly of Fig. 13A as viewed along the longitudinal axis orthogonal to the flat surface T of Fig. 13B.

[0080] FIG. 13D illustrates a scenario in which the spines of the assembly of Fig. 13C is compressed into a collinear configuration.

[0081] FIG. 13F illustrates a variation on the assembly of Fig. 13C.

[0082] FIGS. 13G, 13H , and 131 illustrate yet more variations of the assembly of Fig. 13C.

[0083] FIG. 13J illustrates a cross-sectional view of one exemplary electrode with respect to a spine to show the eccentric or transversally offset configuration of each electrode on one spine.

[0084] FIG. 14A is a side cross-sectional view of a junction between a deflection section and a distal microelectrode assembly, according to one embodiment.

[0085] FIG. 14B is an end cross-sectional view of a housing insert of FIG. 14A.

[0086] FIG. 15A is a side cross-sectional view of a junction between a deflection section and a distal microelectrode assembly, according to another embodiment.

[0087] FIG. 15B is an end cross-sectional view of a housing insert of FIG. 15A.

[0088] FIG. 16 is a side perspective view of a covered spine with reinforcing tensile members, according to one embodiment.

[0089] FIG. 17 is a detailed side cross-sectional view of a portion of a junction with reinforcing tensile members, according to one embodiment.

[0090] FIG. 18 is an end cross-sectional view of a housing insert with reinforcing tensile members passing therethrough, according to one embodiment. [0091] FIG. 19. is an end cross-sectional view of a deflection section with reinforcing tensile members passing therethrough, according to one embodiment.

[0092] FIG. 20 is an end cross-sectional view of a catheter body with reinforcing tensile members passing therethrough, according to one embodiment.

[0093] FIG. 21 is a schematic illustration of a heart and placement of the catheter of the present invention for tissue contact, according various embodiments.

[0094] FIG. 22 is a schematic illustration of a distal microelectrode assembly in contact with tissue in a pulmonary vein, according to one embodiment.

[0095] FIG. 23 is a schematic illustration of a distal microelectrode assembly in contact with tissue of a lateral wall of the heart, according to one embodiment.

[0096] FIG. 24 is a schematic illustration of a distal microelectrode assembly in contact with tissue of an inferior wall or apex of the heart, according to one embodiment.

[0097] FIG. 25 is an end cross-sectional view of the distal end of the distal

microelectrode assembly of FIG. 15A, taken along line A— A.

DETAILED DESCRIPTION OF THE INVENTION

[0098] The following detailed description should be read with reference to the drawings, in which like elements in different drawings are identically numbered. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. The detailed description illustrates by way of example, not by way of limitation, the principles of the invention. This description will clearly enable one skilled in the art to make and use the invention, and describes several embodiments, adaptations, variations, alternatives and uses of the invention, including what is presently believed to be the best mode of carrying out the invention. [0099] As used herein, the terms "about" or "approximately" for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, "about" or "approximately" may refer to the range of values ±10% of the recited value, e.g. "about 90%" may refer to the range of values from 81 % to 99%. In addition, as used herein, the terms "patient," "host," "user," and "subject" refer to any human or animal subject and are not intended to limit the systems or methods to human use, although use of the subject invention in a human patient represents a preferred embodiment. As well, the term“proximal” indicates a location closer to the operator whereas“distal” indicates a location further away to the operator or physician.

[00100] Referring to FIG. 1 , in some embodiments of present invention, a catheter 10 includes a catheter body 12, an intermediate deflection section 14, a distal microelectrode assembly 15, and a control handle 16 proximal of the catheter body 12. The distal microelectrode assembly 15 includes a plurality of spines 17, with each spine supporting a plurality of microelectrodes 18.

[00101] In some embodiments, the catheter body 12 comprises an elongated tubular construction, having a single, axial or central lumen 19, as shown in FIG. 2. The catheter body 12 is flexible, i.e. , bendable, but substantially non-compressible along its length. The catheter body 12 can be of any suitable construction and made of any suitable material. A presently preferred construction comprises an outer wall 20 made of a polyurethane, or PEBAX. The outer wall 20 comprises an imbedded braided mesh of high-strength steel, stainless steel or the like to increase torsional stiffness of the catheter body 12 so that, when the control handle 16 is rotated, the deflection section 14 of the catheter 10 rotates in a corresponding manner. [00102] The outer diameter of the catheter body 12 is not critical. Likewise, the thickness of the outer wall 20 is not critical but is thin enough so that the central lumen 19 can accommodate components, including, for example, one or more puller wires, microelectrode lead wires, irrigation tubing, and any other wires and/or cables. In some embodiments, the inner surface of the outer wall 20 is lined with a stiffening tube 21 , which can be made of any suitable material, such as polyimide or nylon. The stiffening tube 21 , along with the braided outer wall 20, provides improved torsional stability while at the same time minimizing the wall thickness of the catheter, thus maximizing the diameter of the central lumen 19. 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.

[00103] In some embodiments, the intermediate deflection section comprises a shorter section of tubing 30, which as shown in FIG. 3, has multiple lumens 31. In some embodiments, the tubing 30 is made of a suitable biocompatible material more flexible than the catheter body 12. A suitable material for the tubing 19 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 14 is similar to that of the catheter body 12. The plurality and size of the lumens are not critical and can vary depending on the specific application.

[00104] Various components extend through the catheter 10. In some embodiments, the components include lead wires 22 for the distal microelectrode assembly 15, one or more puller wires 23A and 23B for deflecting the deflection section 14, a cable 24 for an electromagnetic position sensor 26 (see FIG. 14A and FIG. 15A) housed at or near a distal end of the deflection section 14. In some embodiments, the catheter includes an irrigation tubing 27 for passing fluid to the distal end of the deflection section 14. These components pass through the central lumen 19 of the catheter body 12, as shown in FIG. 2.

[00105] In the deflection section 14, different components pass through different lumens 31 of the tubing 30 as shown in FIG 3. In some embodiments, the lead wires 22 pass through one or more lumens 31 A, the first puller wire 23A passes through lumen 31 B, the cable 24 passes through lumen 31 C, the second puller 23B passes through lumen 31 D, and the irrigation tubing 27 passes through lumen 31 E. The lumens 31 B and 31 D are diametrically opposite of each other to provide bi-directional deflection of the intermediate deflection section 14. Additional components can pass through additional lumens or share a lumen with the other aforementioned components, as needed.

[00106] Distal of the deflection section 14 is the distal microelectrode assembly 15 which includes a unibody support member 40 as shown in FIG. 4. In some embodiments, the unibody support member 40 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 55% nickel and 45% titanium but may comprise from about 54% to about 57% 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.

[00107] In some embodiments, the member 40 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 42 and the elongated bodies of the spines 17 which emanate from the stem longitudinally and span outwardly from the stem. The stem 42 defines a lumen 43 therethrough for receiving a distal end portion 30D of the multi-lumened tubing 30 (see FIG. 14A) of the deflection section 14, and various components, as further discussed below, which are either housed in the stem 42 or extend through the lumen 43.

[00108] Each spine 17 of the member 40 has an enlarged distal portion 46, and each spine has a wider proximal end and a narrower distal end. In some embodiments, as shown in FIG. 5A, FIG. 5B, FIG. 5C, FIG. 5D and FIG. 5E, the spine is linearly tapered for “out-of-plane” flexibility that varies along it length (see arrows A1 in FIG. 5E), including flexibility that increases toward the distal end 48. In some embodiment, one or more spines 17 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. 5B), 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 46 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.

[00109] In some embodiments, one or more spines 17 have a noncontinuous linear taper between the ends 41 and 46, as shown in FIG. 6A, FIG. 6B, FIG. 6C, FIG. 6D, FIG. 6E, FIG. 6F and FIG. 6G. The noncontinuous linear taper includes one or more narrower or indented portions 50 that are strategically positioned along the spine to interrupt an otherwise continuous linear taper, defined by taper T2 between the stem 42 and the enlarged distal portion 46. Each indented portion 50 has a width W (see FIG. 6C) 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 50 thus advantageously allows that region of the spine to have a different flexibility than

immediately adjacent (distal and proximal) portions 51 of the spine, and to provide a degree of independent flexibility between the portions separated by the indented portion 50 (see FIG. 6B). Accordingly, these spines are allowed to exhibit markedly greater flexibility and hence tighter or more acute curvatures in the region of the indented portions 50 relative to the portions 51 of the spines when the distal portions 46 come into contact with tissue.

[00110] In some embodiments, each spine (between the distal end of the stem 42 and the distal end of the spine) has a length ranging between about 1.0 cm to 2.5 cm, or between about 1.50 cm and 2.0 cm, a width ranging between about 0.009 inches and 0.02 inches. In some embodiments, the indented portion 50 has a length ranging between about 10%-20% of the length of the spine, and a width W ranging between about 50%- 80% of immediately adjacent widths, with its leading proximal edge located at about 55%- 65% of the length of the spine, measured from the distal end of stem 42.

[00111] To further facilitate microelectrode contract with tissue along the entire length of the spine, each spine 17 has a preformed configuration or curvature, accomplished by, for example, heat and a molding fixture. One or more spines 17 have at least two different preformed curvatures C1 and C2, as shown in FIG. 7A, 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 40 has a generally forward-facing concavity that resembles an open umbrella. As shown in FIG. 7B (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 40 maintains its generally forward-facing concave configuration without turning inside out upon tissue contact, like an umbrella upturning in strong wind.

[00112] In some embodiments, one or more spines 17 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. 8A, one or more spines 17 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. 8B (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.

[00113] As another example, as shown in FIG. 9A, 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. 9B (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.

[00114] With reference to FIG. 10, in some embodiments, the unibody support member 40 and its spines 17 can be defined by a plurality of parameters, including the following, for example:

a = height of second curvature, ranging between about 0.00” and 0.050”

b = distal length of second curvature, ranging between about 0.302” and 0.694” c = proximal length of second curvature, ranging between about 0.00” and 0.302” d = distance between first and second curvature, ranging between about 0.00” and

0.170”

e = radius of first curvature, ranging between about 0.075” and 0.100”

f = length of uniform width segment, being about 0.100”

g = concavity depth, ranging between about 0.123” and 0.590”

[00115] Notably, in some embodiments of the unibody support member 40, the proximal (or first) preformed curvature is opposite of the distal (or second) preformed curvature so the spines 17 of the distal microelectrode assembly 15 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 microelectrode assembly is pressed toward the tissue surface to ensure tissue contact by each of the spines 17. Moreover, in some embodiments, the indented portion 50 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.

[00116] 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 subtler and less acute.

[00117] In some embodiments, one or more spines 17 are also configured with a hinge 90 for in-plane (side-to-side) deflection. As shown in FIG. 11A and FIG. 11 B, a spine 17 can have a plurality of notches or recesses along opposing lateral edges, including expandable recess 80 (e.g., in the form of slits 81 and circular openings 82) along one edge 85a and compressible recess 83 (e.g., in the form of slots 84 and circular openings 82) along an opposite edge 85b, forming a hinge 90 for more in-plane deflection along those edges. In the embodiments of FIG. 11A and FIG. 11 B, uni-deflection occurs toward the edge 85b of the spine 17. However, it is understood that where compressible recess 83 are formed along both the edges 85a and 85b the spine 17 has bi-directional deflection toward either edge 85a or 85b. Suitable hinges are described in U.S. Patent No.

7276062, the entire content of which is incorporated herein by reference.

[00118] As shown in FIG. 12A and FIG. 12B, each spine 17 of the distal microelectrode assembly 15 is surrounded along its length by a non-conductive spine cover or tubing 28. In some embodiments, the non-conductive spine cover 28 comprises a very soft and highly flexible biocompatible plastic, such as PEBAX or PELLATHANE, and the spine cover 28 is mounted on the spine with a length that is coextensive with the spine as between the stem 42 and the enlarged distal portion 46. A suitable construction material of the spine cover 28 is sufficiently soft and flexible so as generally not to interfere with the flexibility of the spines 17. [00119] In some embodiments, each covered spine 17 along its length has a diameter D of less than 3 French, preferably a diameter of less than 2.7 French, and more preferably a diameter of 2 French, (e.g., between about 0.025” and 0.035” in diameter).

[00120] Each spine 17 at includes an atraumatic distal cover or cap 45 (see FIG. 12A) encapsulating the enlarged distal portion 46. In some embodiments, the cover 45 comprises a 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 45 includes a bridging portion 63 of the adhesive or sealant that passes through the through-hole 47 in the enlarged distal portion 46 and advantageously creates a mechanical lock that secures the cover 45 on the distal portion 46 and minimizes the risk of the cover 45 detaching from the enlarged distal portion 46.

[00121] Each spine 17 carries a plurality of microelectrodes 18. The plurality and arrangement of microelectrodes can vary depending on the intended use. In some embodiments, the plurality ranges between about 48 and 72, although it is understood that the plurality may be greater or lesser. In some embodiments, each microelectrode has a length L of less than 800 pm, for example, ranging between about 600 pm and 300 pm, and, for example, measuring about 480 pm, 460 pm or about 450 pm. In some embodiment, the distal microelectrode assembly 15 has an area coverage greater than about 7.1 /cm ² , for example, ranging between about 7.2/cm ² and 12.6/cm ² . In some embodiments, the distal microelectrode assembly 15 has a microelectrode density greater than about 2.5 microelectrodes/cm ² , for example, ranging between about 4

microelectrodes/cm ² and 7 microelectrodes/cm ² . [00122] In some embodiments, the distal microelectrode assembly 15 has eight spines, each of about 1.5 cm in length and carrying eight microelectrodes for a total of 48 microelectrodes, each with microelectrode having a length of about 460 pm, wherein the assembly 15 has an area coverage of about 7.1 /cm ² , and a microelectrode density of about 7 microelectrodes/cm ² .

[00123] In some embodiments, the distal microelectrode assembly 15 has eight spines, each of about 2.0 cm in length and carrying six microelectrodes for a total of 48

microelectrodes, each with microelectrode having a length of about 460 pm, wherein the assembly 15 has an area coverage of about 12.6/cm ² , and a microelectrode density of about 4 microelectrodes/cm ² .

[00124] The microelectrodes 18 on a spine 17 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 18 can be separated by a distance S1 ranging between about 1 mm and 3mm, with reference to FIG. 12A. As bipoles, adjacent pairs of microelectrodes 18 can be separated by a distance S2 ranging between 1 mm and 6mm, with reference to FIG. 12B.

[00125] In some embodiments, six microelectrodes are arranged as three bipole pairs, with a spacing S1 of 2.0 mm between proximal edges of a bipole pair, and a spacing S2 of 6.0 mm between proximal edges of adjacent bipole pairs, with reference to FIG. 12B, which may be referred to generally as a“2-6-2” configuration. Another configuration, referred to as a“2-5-2-5-2” configuration, has three bipole pairs, with a spacing S1 of 2.0 mm between proximal edges of a bipole pair, and a spacing S2 of 5.0 mm between proximal edges of adjacent bipole pairs. [00126] In some embodiments, six microelectrodes are arranged as monopoles, with a spacing S1 of 2.0 mm between proximal edges of adjacent monopoles, with reference to FIG. 12A. which may be referred to as“2-2 -2 -2 -2” configuration. In some embodiments, the space S1 is about 3.0 mm and thus is referred to as a“3-3-3-3-3” configuration.

[00127] 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. 13A of an end probe 400, whereas the spacing between microelectrodes on any one spine may be uniform throughout the distal microelectrode assembly, the microelectrodes along any one spine is staggered relative to the microelectrodes along adjacent spines. For example, the distance D1 between the most proximal microelectrode 18P and the end of the stem 42 for spines 17A, 17C, 17E and 17G is greater than the distance D2 between the most proximal microelectrodes 18P and the end of the stem 42 for spines 17B, 17D, 17G and 17G. This staggered

configuration minimizes the risk of microelectrodes on adjacent spines from touching and shorting, especially when an operator sweeps the distal microelectrode assembly against tissue.

[00128] Components of construction and assembly of the junction between the distal microelectrode assembly and the distal end portion of the deflection section 14 are described in U.S. Patent Nos. 7089045, 7155270, 7228164, and 7302285, the entire disclosures of which are incorporated herein by reference.

[00129] Fig. 13B shows the end probe assembly 400 of Fig. 13A in a side view in which the spines of the assembly are in contact with a flat surface T. In this configuration where the longitudinal axis L-L (as defined by stem 42) is generally orthogonal to flat surface T, it can be seen that the stem 42 includes a tubular member 27 in which a reference microelectrode 67A can be mounted to a distal portion of tubing member 27 with a gap G to avoid contact with tissues represented by surface T.

[00130] We have recognized that in certain use cases, the microelectrodes of adjacent spines may contact each other. Accordingly, we have devised placement of the microelectrodes on each spine to ensure that the microelectrodes of adjacent spines do not contact each other. In particular, it can be seen in Fig. 13B that there are eight spines 17A, 17B, 17C, 17D, 17E, 17F, 17G, 17H with each spines having its corresponding six microelectrodes 17A1 -17A6; 17B1-17B6; 17C1 -17C6; 17D1 -17D6; 17E1 -17E6; 17F1 - 17F6; 17G1 -17G6; 17H 1 -17H6 mounted on each of respective spines 17A, 17B, 17C,

17D, 17E, 17F, 17G, 17H. Using spine 17A as a referential datum, it can be seen that when the end effector 400 is placed against a flat clear surface (e.g., glass), the microelectrodes on spine 17A can define various virtual circles as referenced from the longitudinal axis L-L (or tubing 27). For example, first microelectrode 17A1 defines first virtual circle VC1 ; second microelectrode 17A2 defines second virtual circle VC2; third microelectrode 17A3 defines third virtual circle VC3; fourth microelectrode 17A4 defines fourth virtual circle VC4; fifth microelectrode 17A5 defines fifth virtual circle VC5; sixth microelectrode 17A6 defines sixth virtual circle VC6 and so on if there are more

microelectrodes on the spine 17A. The virtual circles demonstrate the“staggered” disposition of the microelectrodes on one spine relative to its adjacent neighbors. As used herein, staggered indicates that one microelectrode on a referential spine is not in contact with different microelectrodes on neighboring spines. In Fig. 13C, even if referential spine 17A can be rotated clockwise for 45 degrees about axis L-L toward spine 17B, none of microelectrodes 17A1 , 17A2, 17A3, 17A4, 17A5 or 17A6 can contact microelectrodes 17B1 -17B6 of spine 17B. Similarly, even if spine 17A can be rotated 45 degrees counterclockwise in Fig. 13C about axis L-L, none of microelectrodes 17A1 -17A6 can contact microelectrodes 17H1 -17H6 of spine 17H.

[00131] As well, in circumstances whereby the spines are compressed together by tissues such that the spines are compressed into co-linear fashion with the axis L-L, the microelectrodes of one spine cannot contact the microelectrodes of its adjacent neighbors. This is shown exemplarily in Fig. 13D where spines 17A is compressed to be collinear with spines 17H, 17G, 17F and 17E. A stagger distance Dstaggerl can be seen between the leading edges of respective microelectrodes 17A1 and 17H1. While the stagger distance can be the same between each of the microelectrodes 17A1 -17A6 on spine 17A with its counterpart neighboring microelectrodes 17H1 -17H6 on neighboring spine 17H, other stagger distances can be utilized, such as, for example, stagger distance Dstagger4 for the fourth microelectrodes 17A4 and 17H4 on respective neighboring spines 17A and 17H. The stagger distance can be any distance from about 0.1 mm to about 6mm.

[00132] Referring again to Fig. 13C, it can be seen that the microelectrodes on each of the spines are configured to have the same gap distance D1 =D2=D3=D4=D5 between them on each spine. The gap distance can be measured on the leading edges of each microelectrode or from center to center of each microelectrode. Although the gap distances are the same, the microelectrode sets 1 -6 on each spine (e.g., 17A) are offset to the microelectrode sets 1 -6 of neighboring spines (e.g., 17H and 17B) by the same stagger distance Dstaggerl . Fig. 13E illustrates an embodiment whereby the gap distances are not the same value and may differ. For example, gap distance D1 is smaller than gap distance D2 and can be equal to gap distance D3 and D5 while gap distance D4 can be equal to gap distance D2. The gap distances D1 , D2, D3, D4, and D5 can be unequal as long as the microelectrode set on each spine (e.g., 17A) is offset or staggered (e.g., Dstaggerl ) to its neighboring spines (e.g., 17H and 17B).

[00133] While the configurations shown in embodiments of Fig. 13A-13E are for a ray- like configuration using spines with free ends, the same principles for the ray-like configuration can be applied to closed ended spine configurations that define a basket such as one shown in Fig. 13F. Specifically, in Fig. 13F, there are spines 17A-17L that join to a common center 270 to define a basket-shaped assembly. Each spine may have a plurality of microelectrodes. For example, microelectrodes 17A1 -1710 are disposed such that a virtual circle that intersects one of the microelectrodes 17A1 -17A10 do not intersect the microelectrodes on a neighboring spine (e.g., 17L or 17B).

[00134] Similarly, the same principles for these embodiments can be applied to spines array in planar (instead of a cone-like configuration of Figs. 13A-13E) configurations shown here in Figs. 13G, 13H and 131.

[00135] In Figs. 13G-13H, the embodiments follow the same naming convention as before with stem 42 and spines 170A, 170B, 170C, 170D that are arrayed to be on a single plane (Figs. 13G and 13H) or multi-plane (Fig. 131). Each spine 170A, 170B, 170C and 170D has microelectrodes 170A1 -170A6; 170B1-170B6; 170C1 -170C6; and 170D1- 170D6. microelectrode set 170A1 -170A6 is staggered or offset from its neighbor microelectrode set 170B1 -170B6 on adjacent spine 170B. microelectrode set 170B1 - 170B6 is offset from both of its neighboring microelectrode sets 170A1 -170A6 and 170C1- 170C6. The end probe assembly 400 (which includes, at a minimum the spines and microelectrode sets for each spine) can be configured as in Figs. 13G and 13H so that the spines are contiguous to a single plane of contact. In Fig. 13H, spine 170A can connect with connector 170AD to spine 170D and spine 170B connects with connector 170BC to spine 170C. Contact in more than one plane can be utilized with the configuration of Fig. 131 whereby the spines 170A is connected via connector 17AC to spine 170C to define a first plane of contact for the microelectrode sets of these spines and spines 170B and 170D connects with connector 170BD to define a second plane of contact.

[00136] It should be noted that the embodiments of Figs. 13A-13F, 13H and 131 illustrate that the electrodes of one spine are staggered or offset with respect to electrodes on the neighboring spine(s) along the longitudinal axis L-L (of each spine) and that each electrode’s centerline or center of mass L-I_AI coincides with the longitudinal axis L-L of each spine. We have also devised yet another staggered configuration in which the centerline of each electrode on one spine is eccentrically offset from the longitudinal axis in a first direction T1 of the spine on which it is mounted. This eccentric offset feature can be seen in Fig. 13G and also in Fig. 13J in which the electrode 170A1 has its centerline L- LAI offset by an eccentric distance“e” with respect to the axis L-L of the spine 170A in a generally transversal direction T1. Similarly, electrode 170B1 on spine 170B is

eccentrically offset in generally the opposite transversal direction T2 relative to electrode 170A1 on spine 170A of Fig. 13G. It is intended that the electrodes on one spine can be offset longitudinally relative to its neighboring electrodes on neighboring spine(s) alone (Figs. 13A-13F, 13H and 131); eccentrically staggered alone (Fig. 13J) or both

longitudinally and eccentrically staggered, as in Fig. 13G.

[00137] In summary, we have devised certain common features for the embodiments of Figs. 13A-13J. Specifically, various embodiments of a medical probe includes at least the following features: an elongated member extending 14 along a longitudinal axis with a distal microelectrode assembly 400 coupled to the elongated member 14, a proximal stem 42 extending along the longitudinal axis L-L, a first spine (e.g., 17A or 170A) radiating away from the longitudinal axis L-L, the first spine (e.g. 17A or 170A) has a plurality of first microelectrodes (17A1 -17A6 or 170A1-170A6) disposed on the first spine (17A or 170A), a second spine (17B or 170B) adjacent the first spine (17A or 170A) and radiating away from the longitudinal axis L-L, the second spine (e.g., 17B or 170B) has a plurality of second microelectrodes (17B1 -17B6 or 170B1-170B6) disposed on the second spine, such that a first virtual circle (e.g., VC1 or VC2) intersecting one of the plurality of first microelectrodes do not intersect any of the second microelectrodes. In a further refinement, a third spine can be provided adjacent the first spine and radiating away from the longitudinal axis. The third spine has a plurality of third microelectrodes disposed on the third spine such that a first virtual circle intersecting one of the plurality of first microelectrodes do not intersect any of the second and third microelectrodes. It is noted that the first virtual circle is centered generally on the longitudinal axis and it can be generally orthogonal to the longitudinal axis. For purpose of defining the configuration of the spines, the proximal stem can be disposed generally orthogonal to a flat surface with the first, second and third spines in contact with the flat surface to define a radiating configuration of spines. The plurality of spines may include five to eight or more spines disposed in an equiangular configuration arrayed about the longitudinal axis.

[00138] Other common features of the embodiments include a plurality of spines 17A, 17B, 17C, 17D, 17E ... 17N extending along the longitudinal axis with a plurality of first microelectrodes (e.g., 17A1-17A6) disposed on a first spine 17A, a plurality of second microelectrodes (17H1 -17H6) disposed on a second spine (17H) adjacent the first spine (17A). The plurality of first microelectrodes (17A1-17A6) is spaced along the first spine so that the first microelectrodes are offset with respect to the second microelectrodes (17H1 - 17H2) by a stagger distance Dstaggerl . In a further refinement, a plurality of third microelectrodes is disposed on a third spine adjacent the first spine so that the first microelectrodes are offset with respect to the second and third microelectrodes by a stagger distance Dstagger The stagger distance includes any distance from

approximately 0.1 mm to approximately 5 mm as measured between leading edges of one microelectrode on one spine relative to the nearest microelectrode on adjacent spines.

[00139] As shown in FIG. 14A, the stem 42 of the unibody support member 40 receives a narrowed distal end 30D of the multi-lumened tubing 30 of the deflection section 14. Surrounding the stem 42 circumferentially is a nonconductive sleeve 68 that is

coextensive with the stem between its proximal end and its distal end. Distal end 68D of the sleeve 68 extends over the proximal ends 28P of the nonconductive spine tubings 28 so as to help secure the tubings 28 on the spines 17.

[00140] Proximal of the distal end 30D is a housing insert 60 that is also received and positioned in the lumen 43 of the stem 42 of the unibody support member 40. The housing insert 60 has a length in the longitudinal direction that is shorter than the length of the stem 42 so that it does not protrude past the distal end of the stem 42. The housing insert 60 is configured with one or more lumens. One lumen 71 may have a noncircular cross-section, for example, a cross-section that generally resembles a“C” or an elongated kidney-bean, and another lumen 72 may have a circular cross-section, as shown in FIG. 14B, so that the lumens can nest with each other to maximize the size of the lumens and increase space efficiency within the housing insert 60. Components passing through the more lumen 71 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. [00141] In some embodiments, the electromagnetic position sensor 26 (at the distal end of the cable 24) is received in the lumen 72. Other components including, for example, the irrigation tubing 27, and the lead wires 22 for the microelectrodes 18 on the distal microelectrode assembly 15 (and lead wires 25 for any ring microelectrodes 67, 69, and 70 proximal of the spines 17) pass through the lumen 71. In that regard, the housing insert 60 serves multiple functions, including aligning and positioning the various components within the stem 42 of the unibody support member 40, 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 14 and the distal microelectrode assembly 15. 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 27 to impede flow, or cause breakage of the lead wires 22 and 25. To that end, the junction is advantageously assembled in a configuration with the housing insert 60 to form a mechanical lock, as explained below.

[00142] The housing insert 60 may be selectively configured with an outer diameter that smaller than the inner circumference of the lumen 43 of the stem 42 by a predetermined amount. This creates an appreciable void in the lumen 43 that is filled with a suitable adhesive 61 , such as polyurethane, to securely affix the housing insert 60 inside the lumen 43 and to the distal end of the multi-lumened tubing 30 so as to minimize, if not prevent, relative movement between the insert 60 and the stem 42. The housing insert 60 protects the components it surrounds, including the electromagnetic position sensor 26 (and its attachment to the cable 24), the irrigation tubing 27, and the lead wires 22 and 25, and provides a larger and more rigid structure to which the stem 42 is attached. To that end, the housing insert 60 may even have a noncircular/polygonal outer cross-section and/or a textured surface to improve the affixation between the housing insert 60 and the adhesive 61.

[00143] To facilitate the application of the adhesive into the void, the stem 42 is formed with an opening 65 in its side wall at a location that allows visual and mechanical access to the housing insert 60 after it has been inserted into the lumen 43 of the stem 42. Visual inspection of the lumen 43 and components therein during assembly of the junction is provided through the opening 65. Whereas any adhesive applied to the outer surface of the housing insert 60 before insertion into the lumen 43 may squirt out of the stem 42 during insertion, additional adhesive may be advantageously applied into the lumen 43 through the opening 65 to fill the void and thus securely affix the housing insert 60 to the stem 42 and the distal end portion of the multi-lumened tubing 30. The combination of the housing insert 60 and its spatially-accommodating lumen 71 provides a more integrated and less vulnerable junction between the distal microelectrode assembly 15 and the deflection section 14.

[00144] In some embodiments, the catheter 10 includes the irrigation tubing 27 whose distal end 27D is generally coextensive with the distal end of the stem 42 of the unibody support member 40. As such, irrigation fluid, e.g., saline, is delivered to the distal microelectrode assembly 15 from a remote fluid source that provides irrigation fluid via a luer hub 100 (FIG. 1) via the irrigation tubing 27 that extends through the control handle 16, the center lumen 19 of the catheter body 12 (FIG. 2), and the lumen 31 E of the tubing 30 of the deflection section 14 (FIG. 3), where it exits the distal end of the irrigation tubing 27 at the distal end of the stem 42 of the unibody support member 40, as shown in FIG. 15A and FIG. 25. A suitable adhesive 90, such as polyurethane, plugs and seals the lumen 43 around the distal end of the irrigation tubing 27. In some embodiments, the catheter is without irrigation and the distal end of the stem 42 of the unibody support member 40 is sealed in its entirety by the adhesive or sealant 90, such as polyurethane, as shown in FIG. 14A.

[00145] FIG. 16 illustrates an embodiment wherein the nonconductive spine tubings 28 include reinforcing tensile members 53. As understood by one of ordinary skill in the art, the microelectrodes 18 are mounted on the spine cover or tubing 28 wherein an elongated tubular mandrel (not shown) is positioned in the lumen of the spine cover 28 to support the microelectrodes 18 while they are rotationally swaged onto the spine cover 28. The microelectrodes 18 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 18 and the spine cover 28 during swaging, including elongation in the longitudinal direction, the spine cover 28 on which the microelectrodes are carried and swaged onto includes reinforcing tensile members 53, as shown in FIG. 16. Tensile members 53, for example, wires or fibers (used interchangeably herein), are embedded (for example, during extrusion of the tensile members) in the side wall 54 of the tubing.

The tensile members 53 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 28 and the microelectrodes 18 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 28 includes four tensile members at 0, 90, 180 and 270 degrees about the side wall 54.

[00146] In some embodiments, distal ends of the tensile members 53 are anchored in the bulbous cover 45 encapsulating the enlarged distal portion of the spines 17 and/or rings 99D, as shown in FIG. 16, maybe compressed or clamped on over the spine cover 28 and spine 17. In some embodiments, proximal ends of the tensile members 53 are coextensive with the proximal end of the spine cover 28 and may also be anchored by rings 99P (see FIG. 14A and FIG. 15A).

[00147] In some embodiments, the tensile members 53 have a much greater length. With reference to FIG. 17, FIG. 18, FIG. 19 and FIG. 20, the tensile members 53 extend through openings 44 formed in the stem 42 of the unibody support member 40 and into the lumen 43 of the stem 42. The tensile members 53 then extend through the lumen 71 of the housing insert 60, a lumen 31 F of the tubing 30 of the deflection section 14, and the center lumen 19 of the catheter body 12, and into the control handle 16. Proximal ends of the tensile members 53 are configured for manipulation by an operator to deflect the spines 17 of the distal microelectrode assembly 15 so they can individually function as “fingers.” In that regard, the tensile members may be formed in the side wall of the tubing 28 in a manner that allows longitudinal movement relative to the tubing 28 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 microelectrode assembly is in contact with an uneven tissue surface where one or more spines need adjustment for better tissue contact. [00148] With reference to FIG. 21, FIG. 22, FIG. 23 and FIG. 24, the catheter 10 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 microelectrode assembly 15 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.

[00149] In some embodiments, the catheter 10 has a plurality of ring microelectrodes proximal of the distal microelectrode assembly 15. In addition to the ring microelectrode

67, as shown in FIG. 1 , the catheter carries another ring microelectrode 69 more proximal than the ring microelectrode 67, and another ring microelectrode 70 more proximal than the ring microelectrode 69. Lead wires 25 are provided for these ring microelectrodes. In some embodiments, the ring microelectrode 69 is located near the distal end 30D of the multi-lumened tubing 30 of the deflection section 14, and ring microelectrode 70 is separated from the ring microelectrode 69 by a distance S ranging between about 1 mm and 3mm. A respective lead wire 25 is connected to the ring microelectrode 67 via opening 75 formed in the stem 42 of the unibody support member 40, and in the sleeve

68. Respective lead wires 25 for ring microelectrodes 69 and 70 are connected to via openings (not shown) formed in these side wall of the tubing 30 of the deflection section 14.

[00150] Each portion of the puller wires 23A and 23B extending through the catheter body 12 is circumferentially surrounded by a respective compression coils 101 A and 101 B as understood in the art. Each portion of the puller wires 23A and 23B extending through the multi-lumened tubing 30 of the deflection section is circumferentially surrounded by a sheath that protects the puller wires from cutting into the tubing when the puller wires are deflected. Distal ends of the puller wires may be anchored in the sidewall of the tubing 30 at or near the distal end of the tubing 30, as understood in the art. Proximal ends of the puller wires are anchored in the control handle 16 for actuation by the operator of the catheter, as understood in the art.

[00151] The preceding description has been presented with reference to presently preferred embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. Any feature or structure disclosed in one embodiment may be incorporated in lieu of or in addition to other features of any other embodiments, as needed or appropriate. As understood by one of ordinary skill in the art, the drawings are not necessarily to scale. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope.