Patent Description:
Medical procedures involving ablation of the heart may be used to cure a variety of cardiac arrhythmia, as well as to manage atrial fibrillation. Such procedures are known in the art. Other medical procedures using ablation of body tissue, such as treating varicose veins, are also known in the art. The ablation energy for these procedures may be in the form of radio-frequency (RF) energy, which is supplied to the tissue via one or more electrodes of a catheter used for the procedures.

The application of the ablation energy to body tissue, if uncontrolled, may lead to an unwanted increase of temperature of the tissue resulting in charring, thrombosis and other complications, especially where a portion of the ablating electrode is buried in tissue. It is consequently important to control the temperature of the tissue during any medical procedure involving ablation. One method for control is to irrigate the tissue being ablated. However, irrigation requires components to deliver fluid from a proximal end of the catheter to its distal end. With catheter distal ends having diameters on the order of millimeters, space is often a primary constraint on the design and configuration of distal ends that provide for fluid delivery components. Moreover, with distal ends having tip and ring electrodes, such fluid delivery components must define fluid pathways that can provide axial flow and radial flow but occupy minimal space and avoid interfering with other functional aspects of the distal end, such as force sensing and temperature sensing. As such, assembling a catheter distal tip on a micro-level with multiple parts and components can be labor intensive and costly.

Flex circuits or flexible electronics involve a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, Liquid Crystal Polymer (LCP), PEEK or transparent conductive polyester film (PET). Circuits or traces can be screen printed onto the substrates, or applied by photolithographic or <NUM>-D printing technology, to offer an assortment of microelectronic features that are carried on the flex circuit.

Applicants recognized that there is a need to provide a catheter with a distal assembly that can be used to ablate with irrigation for temperature control yet be more easily manufactured and assembled, especially incorporating a flex circuit that provides multiple microelectronic features, for example, electrodes and thermocouples for contact with tissue in diagnostic and therapeutic procedures.

The invention provides an electrophysiology catheter according to claim <NUM>.

An electrophysiology catheter has a distal assembly that can ablate with fluid irrigation and temperature sensing while embodying a configuration that supports the use of a flex circuit which enables manufacturing and assembly in a high-volume, low cost manner. An irrigated ablation distal assembly of this configuration can be readily assembled to present a structurally sound construction. The flex circuit with its traces can provide ablation surfaces or temperature sensing surfaces in multiple configurations, as desired or appropriate. Moreover, the flex circuit is supported and carried on a support structure or "bobbin" that allows circulation of irrigation fluid throughout the distal assembly to aid in maintaining a desired thermal energy level within the distal assembly and the supported structure can be made of less-costly material, including plastic, which can be readily constructed with micro-injection molding. Both the flex circuit and the support structure incorporate features that enable irrigation fluid to enter and exit the distal assembly in cooling the distal assembly and surrounding tissue and bodily fluids. One or more flow directors are adjustable in the support member to direct irrigation fluid selectively to different irrigation chambers or in different directions within the distal assembly. Accordingly, the distal assembly leverages the flex circuit and assembly configuration with the ability to provide improved thermal control and cooling with thermally conductive elements and adjustable irrigation fluid delivery providing effective heat transfer and thermal management to facilitate effective ablation while minimizing fluid load on the patient.

In the claimed invention, the electrophysiology catheter includes an elongated catheter shaft, and a distal assembly defining a longitudinal axis. The distal assembly includes a flex circuit and a support member. The flex circuit is configured in a generally cylindrical form on the support member, with its distal and proximal edge portions supported and affixed to the support member in providing the distal assembly with a circumferential contact surface and internal irrigation chambers. The support member includes a post that extends longitudinally through the cylindrical form of the flex circuit which supports the flex circuit and allows irrigation fluid to enter and circulate within the distal assembly.

In some embodiments, the flex circuit includes an outer surface with electrical traces configured for contact with tissue.

In some embodiments, the flex circuit includes a distal portion and a proximal portion, the distal portion including a generally circular portion and the proximal portion including a generally rectangular portion. The generally circular portion may include radiating arm portions.

In some embodiments, the traces include a thermocouple.

In some embodiments, the traces include an electrode.

In some embodiments, the flex circuit includes a substrate with one or more irrigation apertures.

In some embodiments, the flex circuit includes irrigation openings that are fully or partially covered with a conductive, thermally or otherwise, coating, plating, or the like.

In the claimed invention, the post includes a sidewall defining a fluid channel and the sidewall has one or more irrigation apertures in communication with the fluid channel.

In some embodiments, the post includes a raised portion extending in one or more radial direction.

In some embodiments, the post includes one or more raised portion contacting an inner surface of the flex circuit.

In some embodiments, the post includes a raised band extending circumferentially around the post.

In some embodiments, the raised band includes one or more irrigation apertures.

In some embodiments, the distal assembly includes one or more irrigation chambers between the flex circuit and the post.

In some embodiments, a gap space between the flex circuit and the post provides one or more irrigation chambers.

In some embodiments, the post includes a raised band extending circumferentially around the post such that the raised band divides the irrigation chamber into a distal chamber and a proximal chamber.

In the claimed invention, the support member includes a flow director in the fluid channel of the post and is configured to move longitudinally in the fluid channel relative to the support member.

In some embodiments, the flow director includes a tubing with a lumen.

In some embodiments, the tubing of the flow director extends from the catheter shaft into the distal assembly.

In some embodiments, the distal assembly includes a cap distal of the support member.

In some embodiments, the distal assembly includes a tip electrode distal of the support member.

In some embodiments, the tip electrode has a dome configuration.

In some embodiments, the tip electrode has an irrigation aperture.

In some embodiments, an electrophysiology catheter has an elongated catheter shaft and a distal assembly defining a longitudinal axis and having a flex circuit and a support member. The flex circuit is configured in a generally cylindrical form on the support member, and has distal and proximal edge portions and a first plurality of irrigation apertures. The support member has a distal member with a distal circumferential surface, and a proximal member with a proximal circumferential surface, and also a post extending between the distal member and the proximal member. The post extends longitudinally through the cylindrical form, with the distal circumferential surface supporting the distal edge portion of the flex circuit and the proximal circumferential surface supporting the proximal edge portion of the flex circuit. The post also has a longitudinal channel surrounded by a sidewall configured with a second plurality of irrigation apertures. The inner surface of the flex circuit and the sidewall of the post define one or more irrigation chambers in fluid communication with the first and second irrigation apertures.

In some embodiments, the distal assembly includes a first flow director in the longitudinal channel. The flow director is configured to move longitudinally within the channel relative to the support member.

In some embodiments, the distal assembly includes a second flow director nested in the longitudinal channel of the first flow director and is rotationally movable about its axis relative to the first flow director.

In some embodiments, the first flow director has irrigation apertures in multiple radial directions and the second flow director has an irrigation formation that can be aligned with selected irrigation apertures of the first flow director depending on the rotational position of the second flow director.

In some embodiments, the sidewall of the post has one or more raised portion configured to contact the flex circuit.

In some embodiments, a raised portion of the post divides an irrigation chamber into at least two irrigation chambers.

In some embodiments, a raised portion extends circumferentially around the post.

In some embodiments, the distal assembly includes a tip electrode mounted on a distal end of the support member.

In some embodiments, the flex circuit includes a distal portion and a proximal portion, the distal portion including a generally circular portion with radiating arm portions, and the proximal portion including a generally rectangular portion.

In some embodiments, an electrophysiology catheter has an elongated catheter shaft and a distal assembly defining a longitudinal axis and having a flex circuit and a support member. The flex circuit is configured in a generally cylindrical form on the support member, and has distal and proximal edge portions and a first plurality of irrigation apertures. The support member has a distal member with a distal circumferential surface, and a proximal member with a proximal circumferential surface, and means for irrigating the distal assembly.

In some embodiments, a method for controlling cooling of a distal assembly of an electrophysiology catheter, comprises adjusting longitudinal movement of a tubular flow director within the distal assembly along a longitudinal axis of the distal assembly. The distal assembly includes a flex circuit and a support member and the flex circuit is configured in a generally cylindrical form along the longitudinal axis on the support member.

In some embodiments, a method of constructing a distal ablation portion of an electrophysiology catheter, includes providing a flex circuit having an inner surface, and an outer surface with electrical traces, and providing a support member having a distal member with a distal circumferential surface, a proximal member with a proximal circumferential surface, and a longitudinal post extending between the distal member and the proximal member. The method also includes wrapping a flex circuit onto the support member with a distal edge portion of the flex circuit affixed to the distal circumferential surface of the support member and a proximal edge portion of the flex circuit affixed to the proximal circumferential surface of the support member.

In some embodiments, the method includes mounting a tip electrode onto a distal end of the support member.

In some embodiments, the tip electrode has a first coupler and the distal end of the support member has a second coupler, and the first and second coupler are configured to couple with each other.

In some embodiments, the post has a fluid channel.

In some embodiments, the method includes inserting a flow director into the fluid channel of the post, the flow director having longitudinal movement in the fluid channel relative to the support member.

In some embodiments, the post of the support member has one or more raised portions configured to contact the inner surface of the flex circuit.

In some embodiments, at least a portion of the inner surface of the flex circuit and the post is separated by a gap space defining an irrigation chamber.

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 wherein:.

With reference to <FIG> and <FIG>, a catheter <NUM>, which can be used in a minimally invasive procedure such as ablation of cardiac tissue, comprises an elongated catheter shaft <NUM> and a shorter deflection section <NUM> distal of the catheter shaft <NUM>, which can be deflected uni-directionally or bi-directionally. Suitable embodiments of the catheter shaft <NUM> and deflection section <NUM> are described in <CIT>, and titled CATHETER WITH MULTIFUNCTIONAL MICROINJECTION-MOLDED HOUSING. Distal of the deflection section <NUM> is a distal assembly <NUM> which includes at least one electrode and at least one thermocouple. The catheter also includes a control handle <NUM> proximal of the catheter shaft <NUM>.

The distal assembly <NUM> advantageously includes a flex circuit <NUM> and an internal support member <NUM> (see, e.g., <FIG>) on to which the flex circuit is applied to provide the distal assembly <NUM> with a circumferential tissue contact surface and one or more internal chambers for circulating irrigation fluid to cool the flex circuit and the distal assembly. The flex circuit <NUM> is formed with irrigation apertures <NUM> so irrigation fluid can exit the distal assembly <NUM> and also cool surrounding tissue. The distal assembly <NUM>, including the flex circuit <NUM> and support member <NUM>, facilitates assembly in a manner that can be accomplished with relative ease in an assembly-line fashion, either manually or by automated robotics.

Reference is now also made to <FIG>, which is a schematic, pictorial illustration of a catheter ablation system <NUM>. In system <NUM>, the catheter <NUM> is inserted into the vascular system of patient <NUM> and into a chamber of a heart <NUM>. The catheter is used by an operator <NUM> of system <NUM>, during a procedure which typically includes performing ablation of the patient's heart tissue. In some embodiments, including use in intracardiac procedures, the catheter shaft <NUM>, the deflection section <NUM> and distal assembly <NUM> have a very small outer diameter, typically of the order of <NUM>-<NUM>, and all of the internal components of catheter <NUM>, are also made as small and thin as possible and are arranged so as to, as much as possible, avoid damage due to small mechanical strains.

The operations, functions and acts of system <NUM> are managed by a system controller <NUM>, comprising a processing unit <NUM> communicating with a memory <NUM>, wherein is stored software for operation of system <NUM>. In some embodiments, the controller <NUM> is an industry-standard personal computer comprising a general-purpose computer processing unit. However, in some embodiments, at least some of the operations, functions or acts of the controller are performed using custom-designed hardware and software, such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA). In some embodiments, the controller <NUM> is managed by the operator <NUM> using a pointing device <NUM> and a graphic user interface (GUI) <NUM>, which enable the operator to set parameters of system <NUM>. The GUI <NUM> typically also displays results of the procedure to the operator on a display monitor <NUM>.

The software in memory <NUM> may be downloaded to the controller in electronic form, over a network, for example. Alternatively or additionally, the software may be provided on non-transitory tangible media, such as optical, magnetic, or electronic storage media.

Electrical components, including electrodes, thermocouples and position (location or orientation) sensors, of the distal assembly <NUM> are connected to system controller <NUM> by conductors that pass through the catheter shaft <NUM> and the deflection section <NUM>. In addition to being used for ablation, the electrodes may perform other functions, as is known in the art. The system controller <NUM> may differentiate between the currents for the different functions of the electrical components by frequency multiplexing. For example, radio-frequency (RF) ablation power may be provided at frequencies of the order of hundreds of kHz, while position sensing frequencies may be at frequencies of the order of <NUM>. A method of evaluating the position of distal assembly <NUM> using impedances measured with respect to the electrodes is disclosed in <CIT> titled "Current Localization Tracker," to Bar-Tal et al.

As shown in <FIG>, the system controller <NUM> includes a force module <NUM>, an RF ablation module <NUM>, an irrigation module <NUM>, a tracking module <NUM> and a temperature sensing module <NUM>. The system control <NUM> uses the force module <NUM> to generate and measure signals supplied to, and received from, a force sensor <NUM> in the distal assembly <NUM> in order to measure the magnitude and direction of the force on distal assembly <NUM>. The system controller <NUM> uses the ablation module <NUM> to monitor and control ablation parameters such as the level of ablation power applied via the one or more electrodes of the distal assembly <NUM>. The ablation module <NUM> includes an RF generator (not shown) and controls the power/wattage and duration of ablation being applied.

Typically, during ablation, heat is generated in the one or more electrodes energized by the ablation module <NUM>, as well as in the surrounding region. In order to dissipate the heat and to improve the efficiency of the ablation process, the system controller <NUM> monitors temperature of different portions/surfaces of the distal assembly <NUM> and supplies irrigation fluid to distal assembly <NUM>. The system controller <NUM> uses the irrigation module <NUM> to monitor and control irrigation parameters, such as the rate of flow and the temperature of the irrigation fluid. In some embodiments, the system controller <NUM> uses the irrigation module <NUM> in response to the temperature sensing module <NUM> in managing "hot spots" or uneven heating on the surface of the distal assembly <NUM>, by controlling and adjusting movable internal components of the distal assembly <NUM>, as described in detail further below.

The system controller <NUM> uses the tracking module <NUM> to monitor the location and orientation of the distal assembly <NUM> relative to the patient <NUM>. The monitoring may be implemented by any tracking method known in the art, such as one provided in the Carto3® system manufactured by Biosense Webster of Irvine, CA. Such a system uses radio-frequency (RF) magnetic transmitter external to patient <NUM> and responsive elements within distal assembly <NUM>. Alternatively or additionally, the tracking may be implemented by measuring impedances between one or more electrodes, and patch electrodes attached to the skin of patient <NUM>, such as is also provided in the Carto3® system. For simplicity, elements specific to tracking and that are used by module <NUM>, such as the elements and patch electrodes referred to above, are not shown in <FIG>.

With reference to <FIG>, <FIG> and <FIG>, the distal assembly <NUM> includes a cap or a tip electrode <NUM>, an internal support member <NUM>, and a flex circuit <NUM> arranged in a generally cylindrical form on the support member <NUM>. In some embodiments, the support member <NUM> may resemble a spool or a bobbin, with a proximal member or end <NUM>, a distal member or end <NUM>, and a longitudinal member or post <NUM> extending between the ends <NUM> and <NUM>. The ends <NUM> and <NUM> have radial dimensions transverse to a longitudinal axis <NUM> of the distal assembly <NUM>, and the post <NUM> is aligned and coextensive with the longitudinal axis <NUM>. As better seen in <FIG> and <FIG>, a distal face of the distal end <NUM> has a recess 52D and a proximal face of the proximal end has a recess 52P to create a connection and interface between the separate distal cap <NUM>. Each of the ends <NUM> and <NUM> has an inner circumferential surface 46P, 46D located at a smaller diameter D1 and an outer circumferential surface 48P, 48D located at a larger diameter D2, where D1 < D2, so that inner surface <NUM> of the proximal and distal edges <NUM> and <NUM> of the flex circuit <NUM> can rest on the inner circumferential surfaces 46P, 46D, respectively, and the outer tissue contact surface <NUM> of the flex circuit <NUM> can be generally flush or even with the outer diameter of the flex circuit <NUM>. The flex circuit <NUM> at its proximal and distal edges <NUM> and <NUM> is affixed to these circumferential surfaces of the support member <NUM> by a suitable adhesive or the like.

As shown in <FIG> and <FIG>, the post <NUM> extends centrally through the cylindrical form of the flex circuit <NUM>, and the post <NUM> itself is hollow with a longitudinal fluid channel <NUM> that extends through the entire longitudinal length of the member <NUM>, from a distal opening 51D to a proximal opening 51P. Generally surrounded by the flex circuit <NUM>, the post <NUM> has a radius R3 that is less than the radius R2 such than an annular space gap is provided between post <NUM> and the flex circuit <NUM>, defining one or more irrigation fluid chambers <NUM> therebetween. A plurality of irrigation apertures <NUM> are formed throughout generally the entirety of the sidewall of the post <NUM>, in all radial directions about the longitudinal axis <NUM>, so that irrigation fluid entering the proximal opening 51P and passing through the channel <NUM> can exit the post <NUM> in any radial direction through the apertures <NUM> and into the one or more chambers <NUM>. The placement, size or shape of the apertures <NUM> may be varied, as desired or appropriate. It is understood that the drawings do not necessarily illustrate all placement of the apertures <NUM> configured in the post <NUM> - that is, apertures <NUM> may be configured in any surface or portion of the post <NUM> as desired or appropriate. Where the support member <NUM> is constructed of an electrically-conductive material, a lead wire (not shown) from the ablation module <NUM> may be connected to the support member so as to deliver energy conductively to the tip electrode <NUM> at the distal end of the support member for RF ablation at the tip electrode.

The flex circuit <NUM> is rolled, wrapped or otherwise applied to portions of the support member <NUM> so that it forms a cylindrical shape to provide the distal assembly <NUM> with a circumferential tissue contact surface. In some embodiments, the flex circuit <NUM> has a pre-assembly configuration of a generally rectangular shape that is defined by a substrate <NUM> constructed of a sheet of flexible, nonelectrically-conducting, biocompatible material onto which electrically-conducting traces <NUM> are provided on an outer surface <NUM> of the substrate, as shown in <FIG>. (It is understood that that the terms "substrate" and "flex circuit" are used interchangeably herein, as appropriate. ) The substrate <NUM> is configured with a distal edge <NUM>, a proximal edge <NUM>, and opposing side edge portions 33a and 33b that can meet, overlap and be affixed to each other, e.g., with a suitable adhesive, and to form a closed configuration, for example, a hollow cylindrical form with an interior volume <NUM>. The cylindrical form of the flex circuit <NUM> as applied to the support member <NUM> has a center longitudinal axis that is aligned and coextensive with the longitudinal axis <NUM> of the distal assembly <NUM> such that an outer-facing surface <NUM> of the substrate <NUM> forms the circumferential tissue contact surface of the distal assembly <NUM>.

In some embodiments, the substrate <NUM> is constructed of polyimide and the traces <NUM> include one or more trace(s) of two different metals. In the illustrated embodiment of <FIG>, the traces include a trace of constantan 30C and trace(s) of copper or gold 30G1, 30G2, 30G3, 30G4, 30G5 and 30G6 that are electrically isolated from each other, each serving as a distinct conductor that forms a distinct thermocouple junction TC1, TC2, TC3, TC4, TC5, and TC6, respectively, with the constantan 30C serving as the common conductor for all six junctions. The patterns of the traces, as well as the use of distinct and common conductors, may be varied as desired or appropriate. In the illustrated embodiment, each thermocouple occupies a unique position on a grid pattern on the flex circuit outer surface <NUM>, and thus on the circumferential surface of the distal assembly <NUM>, so that temperatures at radial angles of approximately <NUM>, <NUM> and <NUM> degrees, along one of two different longitudinal positions L1 and L2 on the tissue contact surface of the distal assembly <NUM> can be sensed by the thermocouples TC1-TC6.

In some embodiments, one or more additional traces or conducting materials are provided on the substrate <NUM> to form one or more ring electrodes. In the illustrated embodiment of <FIG>, a generally linear elongated trace 30R is positioned along a proximal edge of the substrate such that it forms the ring electrode <NUM> on the distal assembly <NUM>, proximal of the thermocouples TC1-TC6, when the flex circuit <NUM> assumes its generally cylindrical shape on the support member <NUM>. In some embodiments, where the support member <NUM> is not electrically conductive, one or more additional traces 30E are provided for electrical connection to the tip electrode <NUM> so that electrical signals sensed by the tip electrode <NUM> can be passed along the catheter to the system controller <NUM> (<FIG>) or energy, such as RF energy, can be delivered to the tip electrode from the ablation module <NUM> (<FIG>).

The substrate <NUM> of the flex circuit <NUM> is formed generally throughout its planar sheet body with a plurality of irrigation apertures <NUM>. The pattern and plurality may vary as desired or appropriate. The irrigation apertures <NUM> allow irrigation fluid to pass from the interior <NUM> of the generally cylindrical form on the distal assembly <NUM> to the outer tissue contact surface <NUM> of the flex circuit <NUM> and the tissue surrounding the distal assembly <NUM>. The irrigation apertures <NUM> may have different shapes or sizes, as desired or appropriate.

In some embodiments, the flex circuit <NUM> is a multi-layered flexible printed circuit board (PCB) sheet having electrical interconnections, such as the conductive traces, which are configured to electrically connect electrical devices, e.g., microelectrodes, thermocouples, position sensors, and the like, coupled to the PCB to suitable wires that extend along the length of the catheter, or to other suitable circuitry. A suitable flex circuit for a distal end assembly of a catheter is described in <CIT>.

<FIG> illustrates a suitable flex circuit <NUM> suitable for use with a distal assembly in accordance with another embodiment. The flex circuit <NUM> includes a proximal portion <NUM> that is generally rectangular to provide the outer circumferential contact surface of the distal assembly, and a distal portion <NUM> to cover a tip electrode and provide a distal dome contact surface thereon. Both the portions <NUM> and <NUM> have a plurality of fluid apertures <NUM>. The proximal portion <NUM> has a distal edge 201D and a proximal edge 201P, and two opposing side edges 205a and 205b, where side edge 205b has a side portion <NUM> extending laterally therefrom. The proximal portion <NUM> has traces, including a common trace <NUM> of one conductive material, e.g., constantan, and an N plurality of traces of another conductive material, e.g., copper, forming N thermocouple junctions J1 - JN. In the illustrated embodiment of <FIG>, the flex circuit <NUM> has six separate traces <NUM>-<NUM> of the another conductive material, forming six thermocouple junctions J1-J6 with the common trace <NUM>. In some embodiments, the outer exposed elements are the conductive surface for the delivery of RF to heat/treat the tissue, ECG electrode and ring electrode, and the inner exposed elements are a conductive surface primarily intended for thermal transfer and soldering pads to connect to the traces. All other traces such as thermocouples are located within the flex circuit. There are also connections between the various elements through various layers of the flex and terminating at the solder pads exposed on the inner surface. In some embodiments, it is preferable to configure the thermocouple junctions as close as possible to the tissue surface being measured.

The distal portion <NUM> is connected tangentially along a section of its distal edge to a section of the distal edge 201D of the proximal portion <NUM>. The distal portion <NUM> resembles a wheel with a generally circular hub <NUM> and a plurality of arm portions <NUM> radiating outwardly like spokes from the hub.

When mounting the flex circuit <NUM> on the distal assembly, the distal portion <NUM> is positioned over the tip electrode (or a member having a similar dome structure) with a center <NUM> of the distal portion aligned with the longitudinal axis <NUM>, as shown in <FIG>. Depending on the curvature of the dome of the tip electrode, one or more folds or creases <NUM> are formed around the edge of the distal portion <NUM> to conform the distal portion <NUM> to the curvature. The proximal portion <NUM> is then wrapped circumferentially to form a cylindrical form. The arm portions <NUM> of the distal portion <NUM> are tucked under the proximal portion <NUM> so as to secure the distal portion <NUM> onto the dome. The side portion <NUM> is tucked under the side edge 205a. In that regard, the arm portions <NUM> and the side portion <NUM> have fluid apertures <NUM> that align with corresponding fluid apertures <NUM> of the proximal portion <NUM> so that the arm portions <NUM> and the side portion <NUM> do not obstruct the fluid apertures <NUM> of the portions of the proximal portion <NUM> overlapping the arm portions <NUM> and the side portion <NUM>.

With reference to <FIG> and <FIG>, in some embodiments, the sidewall <NUM> of the post <NUM> of the support member <NUM> is configured with one or more raised portions <NUM> extending outwardly in the radial direction, each extending a distance (DR/<NUM>) from the longitudinal axis <NUM>, which is generally equally to the radius (D1/<NUM>) so that each portion <NUM> can contact an inner surface <NUM> of the flex circuit <NUM> and support the flex circuit <NUM> in its cylindrical form around the post <NUM>. The raised portions <NUM> may be localized as a peak or they may span a raised area on the post <NUM>. In the illustrated embodiment of <FIG> and <FIG>, the post <NUM> has a circumferential raised band <NUM> at about a midpoint along the length of the post. As such, the raised band <NUM> divide the chamber <NUM> into a distal chamber 54D and a proximal chamber 54P, generally of equal volume as separated by the band <NUM>. For example, with N plurality of bands <NUM>, N+<NUM> plurality of separate chambers <NUM> can be formed within the distal assembly <NUM> between the post <NUM> and the flex circuit <NUM>. It is understood that the width of the raised band <NUM> may have a different configurations The raised portion or band <NUM> may have a lesser width in the longitudinal direction or have a different cross-sectional shape, e.g., U -shape (<FIG>), V-shape (<FIG>), or a solid shape (<FIG>).

As shown in <FIG> and <FIG>, in some embodiments, the support member <NUM> includes a flow director <NUM> that is movable within the channel <NUM> in the post <NUM>. In some embodiments, the flow director <NUM> may be a tubing with a lumen <NUM> through which irrigation fluid can pass distally from a proximal end and exit via a distal opening 58D. The flow director <NUM> is sized and configured for longitudinal movement within the channel <NUM> relative to the support member <NUM> such that the operator <NUM> can manipulate the flow director <NUM> to position the distal opening 58D at a selected location within the channel <NUM> of post <NUM> and direct irrigation fluid to selected portions and chambers within the distal assembly <NUM>. A O-ring <NUM> may be provided, for example, at or near a distal end of the flow director <NUM> to provide a fluid-tight seal around a distal end of the flow director.

In some embodiments, the system controller <NUM>, the irrigation module <NUM>, and the temperature sensing module <NUM> (<FIG>) can be configured to control and manipulate the flow director <NUM>. For example, the flow director <NUM> can be coupled to an actuator responsive to the system controller <NUM> to adjust movement of the flow director <NUM> along longitudinal axis <NUM> between a more distal position (<FIG>) in the support member <NUM> where sidewall <NUM> of the post <NUM> blocks and seals off those irrigation apertures <NUM> proximal of the distal opening 58D, and a more proximal position (<FIG>) where the sidewall <NUM> of the post <NUM> leaves more irrigation apertures <NUM> unblocked and open allowing additional irrigation fluid volume to be delivered out o fthe body <NUM>. Depending on the position of the flow director <NUM>, the irrigation fluid can be delivered by the flow director <NUM> from its lumen <NUM> to different parts of the channel <NUM> and into one or more chambers <NUM>. For example, where cooling is desired in all regions of flex circuit <NUM>, the flow director <NUM> can be positioned more proximally in the channel <NUM> for larger volume of fluid circulation. For example, where more cooling is desired in a distal region of the flex circuit <NUM>, the flow director <NUM> can be positioned more distally in the channel <NUM>. Moreover, where more cooling is desired in the tip electrode <NUM>, the flow director <NUM> can be positioned in a distal-most position where the post <NUM> blocks off all irrigation apertures <NUM> in the channel <NUM> of the post <NUM> so that all irrigation fluid is directed into the tip electrode <NUM>. The flow director <NUM> can therefore be manipulated by an operator to control the cooling of the distal assembly <NUM>, including the tip electrode <NUM>, by allowing adjustment of its position longitudinally relative to the support member <NUM> and the distal assembly <NUM>, whereby longitudinal movement of the flow director <NUM> proportionally controls the cooling rate of the distal assembly <NUM>.

The tip electrode <NUM> is configured as an atraumatic dome with a thin shell S and is suitable for tissue contact in sensing electrical activity or delivery energy, including RF energy, for ablation with tissue contact. In some embodiments, the tip electrode <NUM> is mounted on a distal end of the support member <NUM>, where the tip electrode <NUM> has a circumferential flange <NUM> that receives and surrounds a distal end of the support member <NUM>. In some embodiments, the tip electrode <NUM> is electrically energized via the flex circuit <NUM>. In some embodiments, the tip electrode <NUM> is electrically energized by energy conducted via the support member <NUM> which is energized via a lead wire (not shown) that passes through the length of the catheter, as known in the art. In some embodiments, the tip electrode <NUM> may be constructed in its entirety of one or more metallic materials. In some embodiments, the tip electrode <NUM> is constructed of a metallized material, for example, with a nonmetallic material as a base and a metallic outer layer, such as an electrically-conductive outer coating or deposit, such as of gold. The tip electrode may also carry a flex circuit on its outer distal surface. In some embodiments, the dome <NUM> is metallic. In some embodiments, the dome <NUM> is plated plastic. In some embodiments, the dome <NUM> includes a formed flex circuit with a metalized outer surface with internal thermocouple junctions.

As shown in illustrated embodiments of <FIG> and <FIG>, the tip electrode <NUM> has a proximal opening <NUM> that leads to an interior volume V configured to receive irrigation fluid. In some embodiments, the opening <NUM> is defined by a radial flange <NUM> within the circumferential flange <NUM>, where the radial flange <NUM> abuts with the distal end of the support member <NUM>. The thin-walled, dome shell S may be formed by stamping and is provided with a plurality of irrigation apertures <NUM> generally throughout the shell so that irrigation fluid entering the interior volume V can exit to outside of all regions of the shell S.

The tip electrode <NUM>, the internal support member <NUM> and the flex circuit <NUM> are configured to allow ease of assembly via manual labor or robotics automation. Additionally, the construction material of the tip electrode <NUM> or the support member <NUM> may be a thermally-conductive metallic material, or a combination of thermally-conductive and thermally-nonconductive material, or the like. In some embodiments, the support member <NUM> can be manufactured out of a biocompatible plastic via micro-injection molding.

The tip electrode <NUM> can be readily mounted on the distal end of the internal support member <NUM> using an interference fit and affixation by a suitable adhesive. To that end, the tip electrode <NUM> in some embodiments, as illustrated in <FIG>, has a male coupler <NUM> that extends along the longitudinal axis <NUM> and is received in the distal opening 51D of the channel <NUM> in the support member <NUM>. The male coupler <NUM> has a lip <NUM> that catches on a rim of the distal opening 51D to secure against detachment. The male coupler <NUM> has a longitudinal lumen <NUM> to allow irrigation fluid to pass from the internal support member <NUM> into the interior volume V. Moreover, the lumen <NUM> is in alignment with and sized comparable to the lumen <NUM> of the flow director <NUM> so that irrigation fluid can flow directly from the lumen <NUM> into the lumen <NUM> when the flow director <NUM> is in its distal-most position. It is understood that in some embodiments, the distal end of the support member <NUM> has a male coupler that is received in a female coupler of the tip electrode <NUM>. It is also understood that the tip electrode <NUM> has a generally solid construction with irrigation pathways that extend through the solid construction and provide fluid communication between the chamber(s) <NUM> and outside the tip electrode.

In some embodiments, the distal assembly <NUM> includes a force sensor <NUM> whose distal end is connected to the proximal end of the internal support member <NUM>. Aspects of a force sensor similar to force sensor <NUM> are described in <CIT>, and in <CIT>. With reference to <FIG>, the force sensor <NUM> comprises a resilient coupling member <NUM>, which forms a spring joint between two ends of the coupling member. In some embodiments, the coupling member <NUM> is understood to be formed in two parts or having a first or distal assembly 81D and a second or proximal portion 81P, the two portions being fixedly joined together. The two portions of coupling member <NUM> are generally tubular, and are joined so that the coupling member also has a tubular form with a central lumen <NUM> therethrough. In the embodiments where the coupling member <NUM> is formed of two portions, the two portions implementation simplifies assembly of elements comprised in the force sensor, as well as of other elements mounted in the distal end, into the member <NUM>.

The coupling member <NUM> typically has one or more helices <NUM> cut or otherwise formed in a section of the length of distal assembly 81D, so that the member behaves as a spring. In an embodiment described herein, and illustrated in <FIG>, helices <NUM> are formed as two intertwined helices, a first cut helix 83A and a second cut helix 83B, which are also referred to herein as a double helix. However, coupling member <NUM> may have any positive integral number of helices, and those having ordinary skill in the art will be able to adapt the present description without undue experimentation to encompass numbers of helices other than two. Alternatively, the coupling member may comprise a coil spring or any other suitable sort of resilient component with similar flexibility and strength characteristics to those generated by the one or more tubular helical cuts, referred to above.

The coupling member <NUM> is mounted within and covered by a nonconducting, biocompatible sheath <NUM>, which is typically formed from flexible plastic material. Coupling member <NUM> typically has an outer diameter that is approximately equal to the inner diameter of sheath <NUM>. Such a configuration, having the outer diameter of the coupling member to be as large as possible, typically increases the sensitivity of force sensor <NUM>. In addition, and as explained below, the relatively large diameter of the tubular coupling member, and its relatively thin walls, provide the relatively spacious central lumen <NUM> enclosed within the coupling member which can be occupied by other elements.

When catheter <NUM> is used, for example, in ablating endocardial tissue by delivering RF electrical energy through electrode <NUM> or electrode <NUM>, considerable heat may be generated in the distal assembly <NUM>. For this reason, it is desirable that sheath <NUM> comprises a heat-resistant plastic material, such as polyurethane, whose shape and elasticity are not substantially affected by exposure to the heat.

Within force sensor <NUM>, typically within the central lumen <NUM> of the coupling member <NUM>, a joint sensing assembly, comprising coils <NUM>, <NUM>, <NUM> and <NUM>, provides accurate reading of any dimensional change in the spring joint of the force sensor <NUM>, including axial displacement and angular deflection of the joint. These coils are one type of magnetic transducer that may be used in embodiments of the present invention. A "magnetic transducer," in the context of the present patent application and in the claims, means a device that generates a magnetic field in response to an applied electrical current or outputs an electrical signal in response to an applied magnetic field. Although the embodiments described herein use coils as magnetic transducers, other types of magnetic transducers may be used in alternative embodiments, as will be apparent to those skilled in the art.

The coils in the sensing assembly are divided between two subassemblies on opposite sides of spring joint: one subassembly in one portion (e.g., distal assembly 81D) of the member <NUM> comprises coil <NUM>, which is driven by a current, via a cable (not shown) from the system controller <NUM> and the force module <NUM>, to generate a magnetic field. This field is received by a second subassembly, comprising coils <NUM>, <NUM> and <NUM>, which are located in another portion (e.g., proximal portion 81P) of the member <NUM>, opposing the coil <NUM> from across the helice(s) <NUM>. Coils <NUM>, <NUM> and <NUM> are fixed in distal end <NUM> at different radial locations about the longitudinal axis <NUM>. Specifically, in this embodiment, coils <NUM><NUM> and <NUM> are all located in the same plane perpendicular to the axis <NUM>, at different azimuthal angles about the longitudinal axis <NUM>, and have respective axes of symmetry generally parallel to axis <NUM>. For example, the three coils may be spaced azimuthally <NUM>° apart at the same radial distance from the longitudinal axis <NUM>.

Coils <NUM>, <NUM> and <NUM> generate electrical signals in response to the magnetic field transmitted by the coil <NUM>. These signals are conveyed by a cable (not shown) to the system controller <NUM>, which uses the force module <NUM> to process the signals in order to measure the displacement of spring joint parallel to axis <NUM>, as well as to measure the angular deflection of the joint from the axis. From the measured displacement and deflection, the system controller <NUM> is able to evaluate, typically using a previously determined calibration table stored in force module <NUM>, a magnitude and a direction of the force on the spring joint of the coupling member <NUM>. In some embodiments, a second ring electrode <NUM> is carried on the proximal portion 81P.

The system controller <NUM> uses the tracking module <NUM> (<FIG>) to measure and detect the location and orientation of distal end <NUM>. The method of detection may be by any convenient process known in the art. In some embodiments, magnetic fields generated external to patient <NUM> (e.g., by generators positioned below patient's bed) generate electric signals in a position sensor <NUM> housed in the proximal portion 81P. As shown in <FIG>, the position sensor <NUM> comprises sensing coil X, coil Y, and coil Z (which in some embodiments is one of the coils <NUM>, <NUM> and <NUM>). The system controller <NUM> processes the electric signal to evaluate the location and orientation of the distal assembly <NUM>. Alternatively, the magnetic fields may be generated in the distal assembly <NUM>, and the electrical signals created by the fields may be measured external to patient <NUM>.

The irrigation fluid is delivered to distal assembly <NUM> by an irrigation tubing <NUM> with lumen <NUM>. The irrigation tubing <NUM> extends through the deflection section <NUM> and the catheter shaft <NUM>. A distal end of the irrigation tubing <NUM> is coupled to a proximal end of the flow director <NUM> such that the lumen <NUM> is in communication with the lumen <NUM> of the flow director <NUM>. In some embodiments, the irrigation tubing <NUM> at its proximal portion extends past the control handle <NUM> such that a proximal end is exposed so that the operator can manipulate the irrigation tubing <NUM> by pulling or pushing the flow director <NUM> in a more proximal position or a more distal position in the support member <NUM> in directing flow of the irrigation fluid. In some embodiments, the system controller <NUM> is configured to actuate movement of the irrigation tubing <NUM> in response to the temperature sensing module <NUM>. In some embodiments, the irrigation tubing <NUM> is integral with and a proximal portion of the flow director <NUM>. In some embodiments, the irrigation fluid is a saline solution, and the rate of flow of the fluid, controlled by the irrigation module <NUM>.

In some embodiments, as shown in <FIG>, a distal portion of the sidewall of the flow director <NUM> that can extend inside the support member <NUM> has irrigation apertures <NUM> in generally all radial directions about the longitudinal axis <NUM>, e.g., 96A, 96B, 96C as shown. A second or inner flow director <NUM>, e.g., a tubing with lumen <NUM>, is nested in the lumen <NUM> of the flow director <NUM>. A sidewall in the distal portion of the second flow director <NUM> that can extend within the support member <NUM> has an irrigation formation <NUM>, e.g., longitudinal slot <NUM> (in broken lines) or longitudinally-arranged irrigation apertures 99A (in solid lines), that can be aligned with a longitudinal group of irrigation apertures <NUM> when the second flow director <NUM> is rotated along its longitudinal axis by the operator <NUM> or the system controller <NUM>. In the illustrated embodiment of <FIG>, the second flow director <NUM> has been rotated so that the irrigation formation <NUM> is aligned with the apertures 96B so that there is fluid communication therebetween and irrigation fluid is directed to exit the post <NUM> via the apertures 96B. However, as shown in <FIG>, the second flow director <NUM> has been rotated so that its irrigation formation <NUM> is aligned with the apertures 96A so that there is fluid communication therebetween and irrigation fluid is directed to exit the post <NUM> via the apertures 96A. The second flow director <NUM> thus enables radial directional control in the flow of irrigation fluid about the longitudinal axis <NUM> within the distal assembly <NUM>. An outer tubing <NUM> is provided to circumferentially surround the exposed proximal portion of first or outer flow director <NUM>.

Means for irrigating the distal assembly <NUM> are shown and described in one of many examples in relation to the post <NUM> of the support member <NUM>, the first flow director <NUM> and the second flow director <NUM>, as shown in <FIG>, <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, including equivalents thereof as well as those provided by later developed technologies.

In use, the catheter <NUM> is introduced into the patient's vascular system and the distal assembly <NUM> is advanced to an area of interest, for example, a heart chamber. The system controller <NUM> accomplishes diagnostic procedures, including mapping. For example, the position sensor <NUM> generates signals processed by the tracking module <NUM> in determining location and orientation of the distal assembly <NUM>. The tip electrode <NUM>, the distal ring electrode <NUM> or the proximal ring electrode <NUM> sense electrical activity of adjacent heart tissue which signals generated are processed by processing unit <NUM>. A <NUM>-D electrophysiology map may be created from these processed signals, and ablation tissue sites are identified and targeted. The system controller <NUM> may then accomplish therapeutic procedures. For example, the operator maneuvers the distal assembly <NUM> so that the tip electrode <NUM> is in contact with the targeted tissue site. Contact between the tip electrode <NUM> and tissue results in the application of a force that displaces the distal assembly 81D relative to the proximal portion 81P of the force sensor <NUM>. Such displacement causes the coils <NUM>, <NUM> or <NUM> to generate signals that are processed by the force module <NUM>, for example, to confirm contact of the distal assembly <NUM> and tissue in preparation for ablation.

Before or during ablation, the irrigation module <NUM> controls delivery and rate of delivery of irrigation fluid to the distal assembly <NUM> by a pump (not shown) that delivers irrigation fluid from a fluid source (not shown) through the lumen <NUM> of the irrigation tubing <NUM> and the lumen <NUM> of the flow director <NUM> (which in some embodiments may include the irrigation tubing <NUM> as its proximal portion). The flow director <NUM> is positioned by an operator or the system controller <NUM> such that its distal opening 58D is, for example, in a more proximal position. The ablation module <NUM> delivers RF energy to the tip electrode <NUM> which heats the target tissue to form a lesion. One or more of the thermocouples TC1-TC6 generate signals representative of temperature of respective surrounding tissue and fluids. Depending on the temperature(s) sensed, the system controller <NUM> may in some embodiments communicate with the ablation module <NUM> to adjust the power delivery or with the irrigation module <NUM> to adjust the rate of fluid delivery or the position of the flow director <NUM> to its distal-most position, a more distal position or a less proximal position, as appropriate to avoid hot-spots, charring or thrombosis. Irrigation fluid can therefore be directed to flow out in various manners, including, e.g., (i) all the irrigation apertures <NUM>, <NUM> and <NUM>, (ii) all of the irrigation apertures <NUM> and a portion of the irrigation apertures <NUM>, or (iii) solely the irrigation apertures. Additionally, where the catheter <NUM> includes a flow director <NUM> with irrigation apertures <NUM>, and a second flow director <NUM> with a radially-directed slot <NUM> or irrigation apertures 99A, the operator or the system controller <NUM> can also manipulate the second flow director <NUM> to control a radial direction of irrigation fluid flow. In that regard, the longitudinal formation <NUM>, e.g., the slot <NUM> and the apertures 99A, may be larger or wider than the apertures <NUM> to facilitate fluid communication between them.

Claim 1:
An electrophysiology catheter (<NUM>), comprising:
an elongated catheter shaft (<NUM>);
a distal assembly (<NUM>) defining a longitudinal axis, having:
a flex circuit (<NUM>) configured in a generally cylindrical form that extends along the longitudinal axis, the flex circuit including a distal edge portion (<NUM>) and a proximal edge portion (<NUM>);
a support member (<NUM>) having a distal member with a distal circumferential surface (46D), a proximal member with a proximal circumferential surface (46P), and a post (<NUM>) extending between the distal member and the proximal member, the post extending longitudinally through the cylindrical form, the distal circumferential surface supporting the distal edge portion of the flex circuit, the proximal circumferential surface supporting the proximal edge portion of the flex circuit, wherein the post includes a sidewall (<NUM>) defining a fluid channel and the sidewall has one or more irrigation apertures (<NUM>) in communication with the fluid channel, and characterized in that the support member includes a flow director (<NUM>) in the fluid channel and configured to move longitudinally in the channel relative to the support member to direct irrigation fluid selectively to different portions of the distal assembly.