US20070066972A1 - Ablation catheter apparatus with one or more electrodes - Google Patents

Abstract

A radio frequency (RF) ablation catheter has a flexible distal end portion so that it can be deflected to position an antenna disposed in the distal end portion adjacent a tissue site to be treated. At least one electrical conductor is coupled to the antenna and extends through the catheter to the proximal end of the catheter to a connector at the proximal end of the catheter for connection to a power supply for the RF antenna. At least one electrode is disposed at the distal end portion of the catheter and electrically coupled to the proximal end connector for connection to a monitor. The electrode is of a flexible, electrically conductive material such as conductive polymer material. The electrode may be an electrocardiogram (ECG) electrode.

Description

RELATED APPLICATIONS
• The present application is a continuation-in-part of co-pending U.S. patent application Ser. No. 11/359,808 of concurrent ownership, filed on Feb. 22, 2006, which is a divisional of U.S. patent application Ser. No. 10/306,757, filed Nov. 27, 2002, now U.S. Pat. No. 7,004,938, which claims the benefit of Provisional Application No. 60/334,199, filed Nov. 29, 2001 and the contents of each of these documents are incorporated herein by reference in their entirety.
BACKGROUND
• 1. Field of the Invention
• The present invention generally relates to medical devices used for ablation of biological tissues, and more particularly to an ablation catheter apparatus incorporating one or more electrodes such as electrocardiogram (ECG) electrodes.
• 2. Related Art
• Ablation catheters apply energy to a biological tissue site which requires ablation. Such catheters may use various energy modes, such as radiofrequency, ultrasound, laser, cryogenic, and the like. Radio frequency (“RF”) ablation catheters generally operate in the microwave frequency range and are used to destroy or ablate biological tissues for therapeutic purposes. In one application, microwave ablation catheters are used to ablate cardiac tissues that cause irregular heartbeats or arrhythmia, avoiding the need for more risky and invasive open heart surgery. In a microwave ablation procedure, the catheter-antenna is passed through the vein for access to the atrium. Within the atrium, the antenna is positioned at the desired location where ablation is required. An intracardiac electrogram is used to identify conductive pathways at the cardiac tissue site that needs to be ablated.
• Prior art ablation catheters have been equipped with two or more electrocardiogram (“ECG”) electrode rings or buttons made of electrically conductive material to provide the necessary output signal for identification of the desired ablation site. Traditionally, all catheters used for this purpose are installed with metallic electrodes, regardless of energy mode (RF, ultrasound, laser, cryogenic, or the like). Installing metallic electrodes over a microwave antenna has special challenges. Naked metallic electrodes installed wrongly can absorb ablation energy and become hot. Hot electrodes can have adverse effects on the heart or other biological tissues or organs, such as blood clot formation, adherence to tissue, and tissue charring. Naked metallic electrodes can also impede efficient delivery of energy and hinder ablation efficiency. Additionally, metallic electrodes can separate from the catheter when it is bent, resulting in inaccurate or lost signals.
• Accordingly, what is needed is an efficient system and method for providing an ECG output signal from an ablation catheter device.
SUMMARY
• The ablation catheter system of this invention comprises an elongate catheter adapted for insertion into a body vessel of a patient, the catheter having a distal end portion adapted for positioning adjacent a biological tissue site requiring treatment and a proximal end portion having a connector for connection to a control unit for controlling the ablation procedure, an antenna disposed at the distal end portion of the catheter for providing output energy for tissue ablation purposes, a pair of conductors extending through the catheter from the proximal end portion and connected to the antenna for providing power to the antenna from a power supply in the control unit, and at least one electrode formed of a flexible conductive material disposed at the distal end portion of the antenna and connected to the connector at the proximal end portion of the catheter for providing an output signal to the control unit. The flexible conductive material is at least substantially non-metallic.
• One or more electrodes may be disposed at the distal end portion of the catheter. In one embodiment, the electrode or electrodes are of conductive polymer material with hydrophilic characteristics for improved wetability. Two spaced electrode rings are mounted on or embedded in the outer surface of the cathode. Alternatively, one electrode ring may be provided and the other electrode may be a tip of conductive polymer material at the distal end of the catheter. In alternative embodiments, layers of conductive and nonconductive polymer material may be provided at specific positions at the distal end portion of the catheter to produce multiple working electrodes. In each case, the electrode output signal can be connected to a suitable electrode recording system inputs in the control unit or a separate electrocardiogram unit to provide intracardiac signal mapping.
• This arrangement avoids the problems of metallic electrodes and also provides electrodes which are of a flexible polymer material which can bend readily with the distal end portion of the catheter as it is shaped or bent to negotiate a path through a body vessel.
• Other features and advantages of the present invention will become more readily apparent to those of ordinary skill in the art after reviewing the following detailed description and accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
• The details of the present invention, both as to its structure and operation, may be gleaned in part by study of the accompanying drawings, in which like reference numerals refer to like parts, and in which:
• FIGS. 1A and 1B are side elevation views of a shapeable RF ablation catheter according to one embodiment in a straight and bent configuration, respectively;
• FIGS. 2A and 2B are side elevation views of a shapeable RF ablation catheter according to another embodiment with a different steering mechanism fromFIG. 1;
• FIGS. 3A and 3B are cross sectional views of the distal end portion of the tip of the catheter ofFIG. 1 or2 in a straight configuration and a bent configuration, respectively;
• FIG. 4 is a cross-sectional view of the tip or distal end portion of one embodiment of a shapeable or bendable RF ablation catheter incorporating electrodes;
• FIG. 5 is a cross-sectional view of the tip or distal end portion of a shapeable or bendable RF ablation catheter having a modified electrode arrangement according to another embodiment;
• FIG. 6 is a cross-sectional view of the tip or distal end portion of a shapeable or bendable RF ablation catheter with another electrode arrangement;
• FIG. 7 is a cross-sectional view of the tip or distal end portion of a shapeable or bendable RF ablation catheter with a modified electrode arrangement according to another embodiment; and
• FIG. 8 is a cross-sectional view of the tip or distal end portion of a shapeable or bendable RF ablation catheter with modified electrodes according to another embodiment.
DETAILED DESCRIPTION
• Certain embodiments as disclosed herein provide for systems and methods for ablation of biological tissues in body areas such as the heart, liver, and the like using a bendable radio-frequency (RF) catheter. The catheter is provided with electrodes of a flexible conductive material such as a conductive polymer at its distal end for providing an output signal such as an intracardiac electrocardiogram (“ECG”) signal to a control unit to allow physicians to obtain tissue proximity and electrical conductivity information both before and after tissue ablation, as well as to provide other feedback during the ablation procedure.
• After reading this description, it will become apparent to one skilled in the art how to implement the invention in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments are presented by way of example only and not limitation. As such, this detailed description of various alternative embodiments should not be construed to limit the scope or breadth of the present invention as set forth in the appended claims.
• FIGS. 1A and 1B illustrate a radio-frequency (“RF”)ablation catheter system100 of one embodiment including ashapeable catheter device100 adapted for insertion into a body vessel of a patient and incorporating an RF antenna for delivering electromagnetic energy to a treatment site, as described in more detail below.
• Thecatheter device100 has a flexible, elongatedtubular body120 having aproximal portion130 and a distal ortip portion140. Located at the proximal portion of the body is ahandle chassis160 containing steering and positioning controls (not illustrated) for the body, activated byactuator200. In the embodiment ofFIGS. 1A and 1B, the tip portion of the catheter body is activated to bend between the straight configuration ofFIG. 1A and the bent configuration ofFIG. 1B by sliding the actuator back and forth in an axial direction. In the modified embodiment ofFIGS. 2A and 2B, the tip portion is bent between the straight and bent configurations by rotating the actuator orcollar220. Suitable mechanisms for controlling bending of the tip portion ofcatheter body120 are described in detail in U.S. Pat. No. 7,004,938 of Ormsby et al., the contents of which are incorporated herein by reference. However, it will be understood that any suitable mechanism may be incorporated in the catheter device in order to control the bending or steering of the tip portion as it moves through a body vessel, organ, or cavity.
• A coupling orelectrical connector170 is provided at the proximal end of the catheter device for connecting the catheter to a control unit or the like containing one or more electronic devices such as an RF generator and controller (not shown) for providing power to the antenna during an ablation procedure. Suitable signal control units are known in the ablation catheter field and are therefore not described in detail here.
• The dimensions of the catheter body are adapted as required to suit the particular medical procedure, as is well known in the medical art. In one embodiment, the catheter is used to ablate cardiac tissue. However, the catheter may be used to ablate other types of body tissue in different organs, both internal and external to the body. Thetubular body120 of the catheter device may be generally constructed of a polymer material which is bio-compatible with the body vessel environment. Examples of such materials include thermoplastic elastomer material such as Pebaxg available from Autochem Germany, polyethylene, polyurethane, polyester, polyimide, polyamide, and the like, with varying degrees of radiopacity, hardness, and elasticity.
• The tubular body of the catheter may be formed with a plurality of segments using one or more of the aforementioned materials or equivalents, such that thecatheter body120 is progressively more flexible towards its distal end. The segments may be joined together by thermal bonding, butt joints, or adhesive bonding. Braiding reinforcement may be provided to the surface of the tubular body to attain a desirable level of stiffness and torsional strength for the catheter to advance and negotiate through the body vessel of the patient, while still allowing the distal end portion to be bent when needed. Thedistal end portion140 may be of a softer polymer compound than the remainder of the body, with little or no braiding or reinforcement, to provide the desired flexibility for distal deflection and shaping of the apparatus.
• The structure of the catheter in one embodiment will now be described in more detail with reference toFIGS. 3A and 3B. As noted above, the catheter has a tubular body with acentral bore150 and a closed distal end or tip. The tip may be open in alternative embodiments. In the illustrated embodiment, deflection of the distal end portion of the catheter is accomplished by use of apre-shaped deflection member180 which is constrained in a straight orientation in the configuration ofFIG. 3A and which adopts a bent shape when extended into the bent configuration ofFIG. 3B. However, it will be understood that other bending or shaping mechanisms may be used in alternative embodiments, as described, for example, in U.S. Pat. No. 7,004,938 referenced above. Thedistal end portion140 of the tubular body includes anRF antenna250 comprising a flexible, helically coiledradiating antenna device255 embedded in the flexible wall of the tubular body, as best illustrated inFIGS. 3A and 3B. The antenna device can therefore bend as the distal end portion is shaped to conform to a body vessel or the like, as illustrated inFIG. 3B. Opposite ends of the antenna device are connected to electrical conductors or leads for connection to theproximal end connector170 and thereby to a source of RF energy in the catheter control unit (not illustrated), as will be described in more detail below in connection withFIG. 4. Other antenna devices may be provided in alternative embodiments, and the diameter, pitch and length of thecoiled device255, and the conductive material used for thedevice255, may vary according to the particular procedure and flexibility requirements.
• The electrical conductors which connect the RF antenna to theconnector170 may be of a flexible mesh orbraided wire construction260 or of a thin-film electrically conductive material. In the embodiment illustrated inFIGS. 3A and 3B, the conductors are shown schematically as a mesh construction embedded in the walls of thetubular body120 of the catheter. In alternative arrangements, separate conductors may be used to provide power to theantenna250.FIG. 4 illustrates thedistal end portion310 of a first embodiment of a modified catheter having integratedelectrodes312,314. In one embodiment, the electrodes are ECG electrodes, although they may be other types of electrodes in other embodiments. Although two electrodes are illustrated inFIG. 4, in other embodiments one electrode or more than two such electrodes may be provided. Some parts of the catheter ofFIG. 4 are identical to those in FIGS.1 to3 and like reference numerals have been used for like parts, as appropriate. In the embodiment ofFIG. 4, a pair of coaxial inner and outertubular conductors315,316 extend along the length of thetubular body318, with theouter conductor316 connected to the proximal end ofRF antenna250 and theinner conductor315 connected to the distal end of the RF antenna adjacent the tip of the catheter. The structure of the remainder of thetubular body318 which is not shown inFIG. 4 may be identical to that oftubular body120 described above, and a similar connector170 (not illustrated) may be provided at the proximal end of the catheter for connecting the conductors to a suitable RF source. The distal end portion illustrated inFIG. 4 will be shapeable or bendable in a similar manner and using the same or similar control devices as were described above in connection with FIGS.1 to3.
• In the embodiment ofFIG. 4, thetubular body318 is of dielectric material such as a non-conductive polymer and has aportion320 of reduced outer diameter at its forward end. Thefirst electrode312 comprises a sleeve of flexible conductive material mounted over the reduceddiameter end portion320 of the tubular body and having an end portion ortip322 extending over the open end ofportion320. The RF ormicrowave antenna250 is embedded in the sleeve orelectrode312. The inner andouter conductors315,316 extend through thetubular body318 as illustrated for connection to the opposite ends of theantenna coil250. Thesecond electrode314 comprises a ring of flexible conductive material mounted over thetubular body318 at a location spaced rearwardly from the rear end of conductive sleeve orelectrode312. The two electrodes may be secured over the innertubular body318 by adhesive, bonding, mechanical force, heat sealing or the like. The flexible conductive material forming the electrodes is at least substantially non-metallic material and may be a conductive polymer material which is sufficiently bendable to allow bending of thedistal end portion310 between the positions illustrated inFIGS. 1A and 1B.
• In an alternative embodiment, theelectrode ring314 may be mounted flush in an annular recess or gap in the outer surface of the tubular body, or may be molded integrally with the tubular body, so that it does not project outwardly from the outer surface of thebody318. A conductor orconnector324 extends fromelectrode ring314 to theconnector170 at the proximal end of the catheter, for suitable connection to an ECG monitor or the like in a control unit (not illustrated) for the catheter.Conductor324 is shown spaced from the outer surface ofbody318 inFIG. 4 for clarity, but may be a line of conductive ink or adhesive over the outer surface of the tubular body, or may alternatively be embedded in thebody318outside conductor316, One of theconductors315 or316 will also be connected to the ECG or other monitor for suitable monitoring of the signal detected between the twoelectrodes312,314. In one embodiment, both electrodes are of a flexible, conductive polymer material, i.e. a polymer material loaded with conductive materials.
• FIG. 5 illustrates thedistal end portion325 of a catheter with a modified electrode arrangement in which theelectrode ring314 ofFIG. 4 is replaced by anelectrode end cap330.Electrodes312,330 are of flexible conductive material such as a conductive polymer material as inFIG. 4. In this embodiment, theconductive sleeve312 in which the antenna is mounted has anouter cover layer332 of non-conductive polymer material extending along at least part of its length and over its distal end, providing a non-conductive shield layer between the first andsecond electrodes312,330. A conductor orconnector wire334 extends from the connector at the proximal end of the catheter through thecentral lumen150 of thetubular body318 and into theelectrode end cap330 to provide a signal path between the electrode and the ECG monitor. The catheter ofFIG. 5 is otherwise identical to that of the previous embodiment and like reference numerals have been used as appropriate.Conductive sleeve312,non-conductive layer332, andend cap330 may be laminated together over thetubular body318 by any suitable means such as bonding, heat sealing, adhesive, or the like.
• FIG. 6 illustrates thedistal end portion340 of a catheter having another modified electrode arrangement. Parts of the cathode of this embodiment are identical to those ofFIGS. 4 and 5 and like reference numerals have been used for like parts as appropriate. Unlike the previous embodiments, thesleeve335 in which theantenna coil250 is embedded does not comprise one of the two electrodes. As in the previous embodiment,sleeve335 is mounted over the reduceddiameter end portion320 of thetubular body318, which is of dielectric or non-conductive material, and theantenna coil250 is connected at its opposite ends to the distal ends of the inner andouter conductors315,316.
• In the embodiment ofFIG. 6, anouter layer336 of non-conductive material, such as a non-conductive polymer material, extends over theconductive sleeve335 and has anend cap portion338 extending over the tip of thetubular body318. The electrodes in this embodiment comprise a pair ofconductive rings339,341 mounted at spaced intervals on the outer,non-conductive layer336. The ring electrodes may be of conductive polymer material. Thefirst ring339 is positioned adjacent the non-conductiveend cap portion338 and thesecond ring341 is positioned adjacent the rear end of theconductive layer336. A central conductor orconnector wire342 extends through the hollow central bore or lumen of thetubular body318, through the non-conductiveend cap portion338, and bends back to terminate in the firstconductive ring electrode339. In one embodiment, the part ofconnector wire342 shown extending throughlumen150 may be a line of conductive ink or adhesive on the inner surface oftubular body318. A second conductor orconnector wire343 extends along the outside of thetubular body318 and is connected to the secondconductive ring electrode341. It will be understood that theconnector wire343 may comprise a line of conductive ink or adhesive ontubular body318, or may alternatively be embedded in thetubular body318 at location spaced outside the outertubular conductor316. The various conductive and non-conductive polymer layers of thedistal end portion340, including the electrode rings, are suitably laminated together by heat sealing, adhesive bonding, or the like.
• Also shown inFIG. 6 is apull wire355 which extends through thelumen150 to thetip338 and is attached to suitable steering and positioning controls (not illustrated) at the proximal end of the catheter, for controlling bending of the distal end portion. Such a pull wire mechanism is described in U.S. Pat. No. 7,004,938 referenced above, the contents of which are incorporated herein by reference. It may be understood that a similar position control mechanism will be provided in the embodiments of FIGS.4 to6, or themechanism180 ofFIG. 3 may be provided in any of these embodiments.
• FIG. 7 illustrates thedistal end portion400 of a catheter according to another embodiment. Again, some parts of the catheter illustrated inFIG. 7 are identical to those of FIGS.4 to6 and like reference numerals have been used as appropriate. As in the previous embodiment, atubular body318 of flexible dielectric material extends the length of the catheter and has a central through bore orlumen150 and anend portion320 of reduced outer diameter over which thesleeve312 containing embeddedRF antenna250 is mounted. As in the previous embodiments,sleeve312 is of conductive polymer material and the ends of the antenna are connected to the distal end connector170 (FIG. 1) of the catheter by means of inner and outercylindrical conductors315,316 extending through thetubular body318, in the manner described above in connection withFIG. 1. Unlike the previous embodiments, anouter cover layer345 of non-conductive polymer material extends along the entire length of the catheter, over thetubular body318 andsleeve312, and has a forward end or tip344 covering the forward end of the sleeve and tubular body. A pair of contact rings346,348 are mounted in theouter cover layer345 in the distal end portion of the catheter, with theforward contact ring346 located over thesleeve312 and in electrical contact with the sleeve, and therear contact ring348 located slightly rearwardly fromsleeve312. Each ring is of a flexible conductive material such as conductive polymer material.Rings346,348 andouter cover layer345 are suitably bonded together and laminated over thetubular body318 andconductive polymer sleeve312.
• Theforward contact ring346 is connected to theproximal end connector170 via theconductive sleeve312 and theouter conductor316 which also provides power to theantenna250. Therear contact ring348 is connected to aconductive wire350 which extends through thetubular body318 to theproximal end connector170 of the catheter. Theconductors316,350 therefore provide the output for the ECG monitor in the control unit in this embodiment.
• The embodiment ofFIG. 7 also includes atemperature sensor352 in thelumen150 adjacent the tip of the catheter. In the illustrated embodiment, thetemperature sensor352 may be a thermistor, thermocouple, or the like and has a thermocouple junction orsensor end352 and a pair of braided wires orconductors354 extending from thesensor352 through the tubular body to theconnector170 at the proximal end of the catheter, where they are connected to control circuitry for monitoring the temperature at the distal end of the catheter and controlling the antenna operation. Apull wire355 is attached to thetip344 of the catheter and extends through thecentral lumen150 through the length of the catheter for attachment to a suitable steering and control mechanism (not illustrated), as in the previous embodiment.
• A system for monitoring and controlling operation of an RF ablation catheter incorporating a temperature sensor is described in co-pending application Ser. No. 11/479,259 filed on Jun. 30, 2006, the contents of which are incorporated herein by reference. It will be understood that a similar control system may be provided for controlling operation of the microwave antenna in this embodiment or other embodiments described above, with suitable inclusion of a temperature sensor.
• FIG. 8 illustrates a modification of the embodiment ofFIG. 5, and like reference numerals are used for like parts as appropriate. In this embodiment, as in the previous embodiments, atubular body318 of dielectric material having acentral lumen150 extends the entire length of the catheter, and has a reducedouter diameter portion320 at thedistal end portion500 of the catheter.Conductive sleeve312 is mounted over theportion320 and theRF antenna250 is embedded insleeve312. As in the embodiment ofFIG. 5, the electrodes comprise theconductive sleeve312 and aconductive tip330 mounted over the end of the catheter, with alayer332 of non-conductive material such as non-conductive polymer between theelectrodes312 and330. The various layers of conductive and non-conductive materials in the embodiment ofFIG. 8 will also be laminated together by any suitable means such as heat, adhesives and mechanical force.
• InFIG. 8, theconductive wire334 which is connected to theconductive tip electrode330 ofFIG. 5 is eliminated, and is replaced withdouble thermocouple wires510 which extend throughlumen150 from theproximal end connector170 of the catheter and into theconductive tip electrode330, with athermocouple junction512 at the end of the double wires providing a temperature sensor. The thermocouple wires therefore have the dual function of providing a temperature sensor output as well as providing an ECG monitor output in combination withouter antenna conductor316. The ECG output may be measured betweenconductor316 and either one of thethermocouple wires510. The temperature output may be used in monitoring and controlling operation of the RF antenna, as described above in connection withFIG. 7.
• In each of the embodiments of FIGS.4 to8, electrodes are mounted at the distal end portion of a shapeable or bendable catheter to allow physicians to locate a tissue region causing problems and to obtain both optimum tissue proximity and electrical conductive activities before and after ablation, as well as to obtain feedback of their actions. Although two electrodes are provided in these embodiments, only one electrode or more than two electrodes may be provided in other embodiments. The electrode or electrodes in these embodiments may be ECG or other types of electrodes. Radio-opaque markers (not illustrated) at the distal end portion of the catheter may also be used to aid in positioning the tip of the catheter, as is known in the field. Where the electrodes are ECG electrodes, it will be understood that the conductor wires connected to the electrodes and to theproximal end connector170 of the catheter will communicate with an external ECG system and monitor (not illustrated) via a suitable connection cable which will transmit ECG signals between the electrodes and ECG system. The antenna conductors and thermocouple wires (if a temperature sensor is present) will be similarly connected to an appropriate antenna output control system.
• In each of the above embodiments, theRF antenna250 is adapted to receive and radiate electromagnetic energy in order to treat a selected biological tissue site. An example of a suitable spectrum of radio frequency energy for use in the ablation catheter is that of the microwave frequency range above 300 MHz. The RF antenna is capable of applying substantially uniformly distributed electromagnetic field energy along the RF antenna in a direction substantially normal to the longitudinal axis ofantenna250.
• The electrodes in the embodiments of FIGS.4 to8 are made of a suitable flexible conductive material, so that they can bend with the remainder of the distal end portion during steering. Such electrodes avoid or reduce the problems encountered with metallic electrodes, since they do not absorb microwave energy to any great extent and do not become excessively hot. The electrodes may be of an at least substantially non-metallic material, and in one embodiment they are made from a conductive polymer material such as nylon, polyethylene, polyolefin, polypropylene, polycarbonate, Pebax®, TPE (thermoplastic elastomers) and blends, loaded with a selective conductive material. Other non-conductive parts of the catheter may be of the same polymer material or different polymer materials. The conductive material may be micro-carbon spheres, carbon particles, carbon nanotubes, nickel dust, or the like. The electrodes may be made entirely of conductive polymer material or may be a mixture of conductive and non-conductive polymer material, or a mixture of conductive and non-conductive materials with metal substrates. The composite polymer material is selected to have a relatively low resistance for reduced interference with the microwave radiation pattern, and to be hydrophilic for improved wetability on the outer surface of the catheter.
• Communication between the electrodes and theconnector170 at the proximal end of the catheter may be provided in some embodiments by means of conductive ink or adhesive applied over the polymer surface. For example,conductor324 ofFIG. 4 orconductor342 ofFIG. 6 may be a line of conductive ink or adhesive over the outer surface of thetubular body318 extending fromelectrode ring314 to the proximal end of the catheter.Conductor350 ofFIG. 7 may be a line of conductive ink or adhesive over the outer surface of non-conductivetubular body318, with theouter layer345 of non-conductive polymer laminated over the tubular body andconductor line350.
• Heat energy, adhesives, and/or mechanical force may be used to laminate the conductive and non-conductive polymer layers in the embodiments of FIGS.4 to8. Metallic substrates may also be laminated between the polymer layers, such as the inner and outer tubular conductors which provide power for operatingRF antenna250.
• The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent a presently preferred embodiment of the invention and are, therefore, representative of the subject matter which is broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly limited by nothing other than the appended claims.

Claims (34)

1. An RF ablation catheter apparatus, comprising:

an elongate catheter adapted for insertion into a body vessel of a patient, the catheter having a proximal end and a distal end portion, at least the distal end portion of the catheter being flexible for allowing the distal end portion of the catheter to be deflected;

a radio-frequency (“RF”) antenna disposed at the distal end portion of the catheter and adapted to receive input RF energy for the ablation of biological tissue;

an electrical connector at the proximal end of the catheter for connection to a power supply for the RF antenna; and

at least one electrode disposed at the distal end portion of the catheter and electrically coupled to the connector at the proximal end of the catheter for connection to a monitor;

the electrode being of a flexible, electrically conductive material.

2. The apparatus ofclaim 1, wherein the electrode is an electrocardiogram (“ECG”) electrode.

3. The apparatus ofclaim 1, wherein the electrode material is an at least substantially non-metallic material.

4. The apparatus ofclaim 3, wherein the electrode material is a flexible conductive polymer material.

5. The apparatus ofclaim 1, wherein the electrically conductive material comprises a flexible polymer material loaded with a conductive material.

6. The apparatus ofclaim 5, wherein the polymer is selected from the group consisting of polyethylene, polyolefin, polypropylene, polycarbonate, nylon and thermoplastic elastomer material.

7. The apparatus ofclaim 5, wherein the conductive material is selected from the group consisting of micro-carbon spheres, carbon particles, carbon nanotubes, and nickel dust.

8. The apparatus ofclaim 1, further comprising at least one electrical conductor extending through the catheter and coupled at a first end to the antenna and to the proximal end connector at a second end.

9. The apparatus ofclaim 1, wherein the catheter comprises a tubular body and the electrode comprises a ring mounted on said tubular body.

10. The apparatus ofclaim 1, wherein at least two spaced electrodes are disposed at the distal end portion of the catheter.

11. The apparatus ofclaim 10, wherein at least a portion of the tubular body at the distal end of the catheter is of non-conductive material and said electrodes comprise spaced rings on the non-conductive portion of said tubular body.

12. The apparatus ofclaim 1, wherein the electrode comprises an elongate sleeve at the distal end portion of said catheter.

13. The apparatus ofclaim 11, wherein the antenna comprises a helical coil embedded in said electrode sleeve, and at least one electrical conductor for connecting the antenna to an RF power source to provide an electrical connection from said electrode sleeve to said proximal end connector.

14. The apparatus as claimed inclaim 13, wherein the electrical conductor is coupled to a first end of the helical coil and a second electrical conductor is coupled to a second end of the helical coil and extends through the catheter to the proximal end connector.

15. The apparatus as claimed inclaim 11, further comprising a second electrode of flexible, electrically conductive material spaced from said conductive electrode sleeve.

16. The apparatus as claimed inclaim 11, further comprising an outer layer of non-conductive material extending over at least part of the electrode sleeve, and a second electrode of flexible, electrically conductive material mounted on said outer layer.

17. The apparatus as claimed inclaim 16, wherein the second electrode comprises an end cap extending over the distal end of the catheter and at least part of the said outer layer.

18. The apparatus as claimed inclaim 17, further comprising an electrical conductor extending through said catheter and coupled to said end cap for electrically connecting the end cap to the proximal end connector of the catheter.

19. The apparatus as claimed inclaim 1, further comprising a temperature sensor mounted in the distal end portion of the catheter and a pair of thermocouple wires connected to said temperature sensor and extending through the catheter to said proximal end connector.

20. The apparatus as claimed inclaim 19, wherein said temperature sensor is coupled to the electrode and one of said thermocouple wires further comprises the electrical coupling from the second electrode to the proximal end connector.

21. The apparatus as claimed inclaim 20, wherein the electrode comprises an end cap at the distal end of the catheter, and the temperature sensor is embedded in the end cap.

22. The apparatus as claimed inclaim 1, wherein the catheter comprises a tubular body extending from the proximal end to the distal end of the catheter, the tubular body being of non-conductive material, and an outer sleeve of conductive material mounted over the distal end portion of the tubular body and containing the RF antenna, the electrode comprising a ring electrically isolated from the outer sleeve.

23. The apparatus as claimed inclaim 22, wherein the electrode ring is mounted over the tubular body at a location spaced from the outer sleeve.

24. The apparatus as claimed inclaim 23, wherein the outer sleeve comprises a second electrode electrically coupled to the proximal end connector.

25. The apparatus as claimed inclaim 23, further comprising a layer of non-conductive material extending along at least part of the length of the outer sleeve, and a second electrode mounted on said layer of non-conductive material.

26. The apparatus as claimed inclaim 1, further comprising a deflection member adapted to control deflection of the distal end portion of the catheter.

27. An RF ablation catheter apparatus, comprising:

an elongate catheter adapted for insertion into a body vessel of a patient, the catheter having a proximal end and a distal end portion, at least the distal end portion of the catheter being flexible for allowing the distal end portion of the catheter to be deflected;

a radio-frequency antenna disposed at the distal end portion of the catheter and adapted to receive input RF energy for ablation of biological tissue;

an electrical connector at the proximal end of the catheter for connection to a power supply for the RF antenna;

a pair of inner and outer coaxial electrical conductors extending through the cathode from said antenna to said electrical connector; and

at least one electrode disposed at the distal end portion of the catheter and electrically coupled to the connector at the proximal end of the catheter for connection to a monitor, the electrode being of a flexible, electrically conductive material.

28. The apparatus ofclaim 27, wherein the antenna comprises a helical coil embedded in the distal end portion of the catheter, the coil having first and second ends, and the coaxial electrical conductors being coupled to the first and second ends of the coil, respectively.

29. The apparatus ofclaim 27, wherein the electrode comprises an elongate sleeve at the distal end portion of the catheter.

30. The apparatus ofclaim 29, further comprising a second electrode of flexible, electrically conductive material spaced from the conductive electrode sleeve.

31. The apparatus ofclaim 29, wherein the antenna is embedded in said electrode sleeve.

32. The apparatus ofclaim 27, wherein at least two spaced electrodes of flexible, electrically conductive material are disposed at the distal end portion of the catheter and coupled to the electrical connector for connection to a monitor.

33. The apparatus ofclaim 32, wherein the electrode material is a flexible conductive polymer material.

34. The apparatus ofclaim 32, wherein the electrodes comprise spaced electrode rings.

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