Ablation catheter with optically transparent electricity conductive tip

(54) Title: ABLATION CATHETER WITH OPTICALLY TRANSPARENT AND ELECTRICALLY CONDUCTIVE CONDUCTOR TIP (30) Unionist Priority: 06/29/200711S 11 / 824,038 (73) Holder (s): Biosense Webster, Inc.

(72) Inventor (s): Chad Allen Lieber, Christopher Beeckler, Shiva Sharareh (57) Abstract: Ablation catheter with an OTICAM ENTE TRANSPARENT AND ELECTRICALLY CONDUCTIVE tip. The present invention relates to a catheter that allows light measurements in real time, for example, without limitation, diffuse reflectance, fluorescence, etc., from biological materials, such as tissue (including blood), while performing RF ablation . The catheter tip isolates the lighting and collection paths so that light leaves the catheter tip and travels through the tissue of interest (for example, cardiac tissue or blood) before returning to the catheter tip. Said configuration advantageously avoids saturation of the optical detector, and ensures the diffusion of the illumination light within the medium of interest. The catheter is equipped with a catheter body and a tip electrode. The tip electrode has an outer shell, an inner layer of diffuse material and a hollow cavity, where the inner layer is configured to transmit light out of the tip electrode to the fabric through lighting openings in the shell wall and the hollow cavity is configured to receive light from the tissue through a set of collection openings in the wall of the wrapper and inner layer. An inner surface of the inner layer has a reflective coating to isolate the light injected into the inner layer from the light collected in the hollow cavity. There is a first optical waveguide that extends between the catheter body and the tip electrode to inject light into the inner layer and illuminate the tissue, and a second optical waveguide that extends between the catheter body and the electrode to collect recaptured light in the hollow cavity.

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ΡΙ0802232-1

Invention Patent Descriptive Report for ABLATION CATHETER WITH OPTICALLY TRANSPARENT AND ELECTRICALLY CONDUCTIVE CONDUCTOR TIP.

Field of the Invention

The present invention relates to ablation catheters, and in particular ablation catheters with optical tissue monitoring. Background of the Invention

For certain types of minimally invasive medical procedures, real-time information regarding the condition of the treatment field within the body is not available. This lack of information inhibits the physician when using a catheter to perform a procedure. An example of such procedures is the treatment of tumor and disease in the liver and prostate. Yet another example of this procedure is the surgical ablation used to treat atrial fibrillation. This condition in the heart causes abnormal electrical signals, known as cardiac arrhythmias, to be generated in the endocardiac tissue resulting in irregular heartbeats.

The most frequent cause of cardiac arrhythmias is the abnormal routing of electricity through cardiac tissue. In general, most arrhythmias are treated by ablation of the centers suspected of the said electrical failure, thus causing the said centers to become inactive. Successful treatment then depends on the location of the ablation within the heart as well as the injury itself. For example, when treating atrial fibrillation, an ablation catheter is maneuvered into the right or left atrium where it is used to create ablation lesions in the heart. These injuries are intended to interrupt the irregular beating of the heart by creating non-conductive barriers between the regions of the atria that interrupt the passage through the heart of abnormal electrical activity.

The lesion must be created in such a way that the electrical conductivity is interrupted in the localized region (transmürality), but care must be taken to avoid ablation of the adjacent tissues. In addition, the ablation process can also cause undesirable tissue loading and localized coagulation, and can evaporate water in the blood and in the tissue that leads to steam bursts.

Currently, lesions are evaluated after the ablation procedure, by positioning the mapping catheter in the heart where it is used to measure electrical activity within the atria. To allow the doctor to assess newly formed lesions and determine whether they will work to disrupt conductivity. If it is determined that the lesions have not been properly formed, then additional lesions can be created to additionally form a block line against the passage of abnormal currents. Clearly, post ablation assessment is undesirable since correction requires additional medical procedures. Thus, it would be more desirable to assess the lesion as it is being formed in the tissue.

A known method for assessing injuries as they are formed is to measure electrical impedance. Biochemical differences between tissue removed by ablation and normal tissue can result in changes in electrical impedance between tissue types. Although impedance is routinely monitored during electrophysiological therapy, it is not directly related to the formation of the lesion. Impedance measurement merely provides data on the site of tissue injury but does not provide quality data to assess the effectiveness of the injury.

Another approach is to measure the electrical conductivity between two points in the tissue. Said process, known as the injury step, can also determine the effectiveness of injury therapy. The referred technique, however, measures the success or lack of it for each injury, and does not produce information in real time about the formation of the injury.

Thus, there is a need for a catheter capable of measuring the characteristics of the formation of the lesion in real time, and thus with an optical image, whether the catheter is parallel, perpendicular or at an angle to the tissue. It would be desirable for the catheter to be adapted for ablation as well. For this purpose, the catheter tip must be transparent and still electrically conductive so that optical data can be perceived by the catheter tip during, before or after ablation.

Many transparent electrical conductors are available, but each has its limitations. Carbon nanotube film is not one of the transparent electrical conductors. Carbon nanotubes were discovered approximately in 1991, but it was suspected of their existence previously based on mathematical calculations. Carbon nanotubes have a large proportion of length to diameter and thus can be seen almost as one-dimensional forms of fullerenes. They have interesting electrical, mechanical and molecular properties. There are single-walled nanotubes (SWNT) where the ratio of length to diameter is about 1000. There are multiple-walled nanotubes (MWNT) with multiple concentric SWNTs with different diameters. MWNTs have different lengths and diameters than SWNTs and they have different properties.

It is now possible to manufacture ultra-thin, transparent, optically homogeneous and electrically conductive carbon nanotube films, and to transfer said films onto various substrates. The challenge was to deposit the nanotubes in a thin enough layer to be optically transparent and still maintain mechanical electrical contact through the layer. The films exhibit optical transmission in the visible and infrared spectrum. In the near-medium infrared, carbon nanotube films have been shown to have good to high transparency for a given electrical conductivity of most things available.

Even in the visible spectrum, the electrical conductivity of nanotube films for a given transparency is comparable to that of tin indium oxide (ITO), which is another substance that has electrical conductivity and optical transparency.

Thus, it would therefore be desirable to provide a catheter that is adapted for optical imaging and electrical conductivity such as for ablation, provided with a tip that is optically omnidirectional and constructed from carbon nanotube film. Said catheter can also be adapted for ultrasound imaging in conjunction with electrical ablation therapy.

Summary of the Invention

The present invention is oriented to a catheter that removes by ablation and allows omnidirectional light measurements in real time, for example, without limitation, diffuse reflectance, fluorescence, etc., from biological materials, such as tissue (including blood). The tip of the catheter employs a carbon nanotube film which, in a sufficiently thin form, offers electrical conduction and optical transparency. The light recaptured from the tissue through the film-covered electrode tip transports tissue parameters that can be assessed using optical spectroscopy. Said parameters include, without limitation, lesion formation, depth of penetration of the lesion, and cross-sectional area of ​​the lesion, formation of carbonization during ablation, recognition of carbonization during ablation, recognition of carbonization from non-carbonized tissue, formation of clot around the ablation field, differentiation of coagulated blood from uncoagulated blood, differentiation of tissue removed by ablation from healthy, tissue proximity, assessment of healthy tissue, status, and morbid status, and recognition of vapor formation in the tissue to prevent vapor bubbles.

In one embodiment, a catheter is provided with a catheter body and an electrode tip that includes an optically transmitter casing coated with a carbon nanotube film. It is contemplated that the optically transmitter housing is adapted for optical illumination and collection, and the carbon nanotube film is adapted for tissue ablation. Furthermore, it is contemplated that the enclosure is generally shaped like a dome defining a cavity and that the enclosure is optically transparent. The film is still optically transmitting if not optically transparent. The cavity is illuminated by at least one emitting optical fiber and the light that enters the cavity from the tissue is received by at least one receiving optical fiber that communicates with an optical processing system.

In a more detailed embodiment, a catheter is provided with a catheter body and an electrode tip with an optically transparent housing and an electrically conductive and optically transparent film in the housing. The wrapper defines a cavity to receive light from the tissue and the film is adapted to ablate the tissue. A first optical waveguide extends into the cavity to provide light and a second optical waveguide extends into the cavity to collect light. The tip electrode is adapted for RF ablation and the catheter can also include an irrigation tube to send fluid to a cavity and through openings in the housing to reach the outside of the tip 10 electrode. The catheter may include a deviable intermediate section between the catheter body and the tip electrode, and a temperature sensor configured to sense the temperature at the tip electrode. There may also be an electromagnetic location sensor configured to sense the location of the tip electrode.

Advantageously, the light used to monitor and evaluate the tissue (or the lesion formed in the tissue) is generally not affected by the portion of electromagnetic radiation used for ablation. In addition, the bandwidth used for monitoring and evaluation is also transmitted through blood with minimal attenuation. Optical fibers are used and arranged in the catheter in such a way that it avoids contact with the tissue, which can increase the life of the catheter and minimize the damage caused by abrasion to the optical fibers. In addition, the alignment plug on the tip electrode secures fiber optic cables with minimal bending or tension but with greater angular coverage, which can minimize the breakage of optical fibers during assembly and use, as well as reducing the non-linear optical effects caused by the orientation of the optical fibers. Additionally, the use of optical fibers to emit and receive light is, in general, a temperature-neutral process that adds little, if any measurable heat to the blood or surrounding tissue.

Brief Description of Drawings

These and other features of the present invention will be better understood with reference to the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side view of an embodiment of the catheter of the present invention.

FIGURE 2A is a side cross-sectional view of a catheter embodiment in accordance with the present invention, including the junction between a catheter body and an intermediate section, taken along a first diameter.

FIGURE 2B is a side cross-sectional view of a catheter embodiment in accordance with the present invention, including the junction between the catheter body and the intermediate section, taken along a second diameter generally perpendicular to the first diameter of the FIGURE 2A.

FIGURE 3A is a side cross-sectional view of an embodiment of a catheter according to the present invention, including the junction between the intermediate section and a plastic housing, taken along the first diameter.

FIGURE 3B is a side cross-sectional view of an embodiment of a catheter according to the present invention, including the junction between the intermediate section and the plastic housing, taken in general along the second diameter.

FIGURE 4 is a longitudinal cross-sectional view of an embodiment of an intermediate section of Figures 3A and 3B, taken in general along line 4-4.

FIGURE 5A is a side cross-sectional view of an embodiment of a catheter according to the present invention, including a junction between the plastic housing and an electrode tip, taken in general along diameter 5A - 5A as shown in FIGURE 6.

FIGURE 5B is a side cross-sectional view of an embodiment of a catheter body according to the present invention, including the junction between the plastic housing and the tip electrode, taken in general along the long diameter 5B - 5B as shown in FIGURE 6.

FIGURE 6 is a longitudinal cross-sectional view of an embodiment of a plastic housing of Figures 4A and 4B, taken along line 6--6.

FIGURE 7 is a schematic drawing showing components of an embodiment of an optical processing system for use with the catheter of the present invention.

Detailed Description of the Invention

As shown in figures 1-6, a catheter 10 of the present invention comprises an elongated catheter body 12 provided with proximal and distal ends, a deflectable intermediate section (uni- or bidirectionally) 14 at the distal end of the catheter body 12, a se10 point 36 at the distal end of the intermediate section, and a control rod 16 at the proximal end of the catheter body 12.

With further reference to FIGURES 2A and 2B, the catheter body 12 comprises an elongated tubular construction provided with a single axial or central light 18. The catheter body 12 is flexible, that is, foldable, but substantially non-compressible over its length. The catheter body 12 can be of any suitable construction and produced from any suitable material. The construction comprises an outer wall 22 produced from an extruded plastic. The outer wall 22 may comprise an embedded stainless steel braid mesh or similar to increase the torsional rigidity of the catheter body 12 so that when the control rod 16 is rotated, the catheter body 12, the intermediate section 14 and the tip section 36 of the catheter 10 will rotate accordingly.

Extending through the single light 18 of the catheter body 12 are the components, for example, copper wire 40 and thermocouple wires 41, 45 protected by a sheath 53, optical fibers 43, an irrigation tube 48, a compression spring 56 through which a driving wire 42 extends, and an electromagnetic sensor cable 74. The single-lumen catheter body may be preferred over the multiple-lumen body because it has been observed that the single-lumen body allows for better tip control when the catheter is rotated. The single light allows the various components such as the copper wire, thermocouple wires, infusion tube, and the driving wire surrounded by the compression spring to float freely in the catheter body. If these wires, tubes and cables are restricted within multiple lights, they tend to increase energy when the rod is rotated, resulting in the catheter body having a tendency to rotate back, for example, if the rod is released, or if bent in a curve, moves, any of which are undesirable performance characteristics.

The outside diameter of the catheter body 12 is not fundamental, but preferably it is no more than about 8 french, more preferably 10 french. Likewise, the thickness of the outer wall 22 is not essential, but it is sufficiently thin so that the central light 18 can accommodate the above-mentioned components. The inner surface of the outer wall 22 can be lined with a stiffening tube 20, which can be produced from any suitable material, such as polyimide or nylon. The stiffening tube 20, together with the external braided wall 22, provides improved torsional stability and at the same time minimizes the thickness of the catheter wall, thus minimizing the diameter of the central light 18. The outer diameter of the stiffening tube 20 is relatively the same or relatively smaller than the inner diameter of the outer wall 22. Polyimide tube may be preferred for the stiffening tube 20 in that it can be provided with rather thin walls and still provides very good stiffness. This increases the diameter of the central light 18 without sacrificing strength and stiffness.

The catheter may be provided with an outer wall 22 with an outer diameter of about 0.090 inch to about 0.104 inch and an inner diameter of about 0.061 inch to about 0.075 inch and the polyimide stiffening tube 20 provided with a diameter external from about 0.060 inch to about 0.074 inch and a wall thickness of about 0.001 inch - 0.005 inch.

With reference also to FIGURES 3A, 3B and 4, the intermediate section 14 distal from the catheter body 12 comprises a shorter section of tube 19 provided with multiple lights. Tube 19 is produced from a suitable non-toxic material which is preferably more flexible than the catheter body 12. A suitable material for tube 19 is polyurethane braided with low to medium durometer plastic. The outer diameter of the intermediate section 14, such as that of the catheter body 12, is preferably no more than about 8 french, most preferably 7 french. The size and number of the lights are not critical. In one embodiment, the middle section 14 has an outside diameter of about 7 french (0.092 inch). The tube 19 is provided with a first decentralized light 30, a second decentralized light 32 and a third decentralized light 34 which are generally about the same size, each of which has a diameter of about 0.020 inch to about 0.024 inch, preferably 0.022 inch, together with a fourth decentralized light 35, having a larger diameter of about 0.032 inch to about 0.038 inch, preferably 0.036 inch.

Returning with reference to FIGURES 2A and 2B, the catheter body 12 can be attached to the intermediate section 14 formed with an outer circumferential slot 24 configured at a proximal end of the tube 19 that receives the inner surface of the external wall 22 of the catheter body 12 The intermediate section 14 and catheter body 12 are fixed by glue or the like. Before the intermediate section 14 and the catheter body 12 are attached, the stiffening tube 20 is inserted into the catheter body 12. The distal end of the stiffening tube 20 is fixedly attached near the distal end of the catheter body 12 while forming a glue joint 23 with polyurethane glue or similar. Preferably a small distance, for example, about 3 mm, is provided between the distal end of the catheter body 12 and the distal end of the stiffening tube 20 to allow space for the catheter body 12 to receive the slot 24 of the intermediate section 14. If no compression spring is used, a force is applied to the proximal end of the stiffening tube 20, and, en30 when the stiffening tube 20 is under compression, a first glue joint (not shown) is implemented between the stiffening tube 20 and the outer wall 22 by a quick-drying adhesive, for example, cyanoacrylate 10. Then, a second glue joint 26 is formed between the proximal end of the stiffening tube 20 and the outer wall 22 using a less rapid but stronger drying glue, for example, polyurethane.

If desired, a spacer can be located within the catheter body 5 between the distal end of the stiffening tube and the proximal end of the tip section. The spacer provides a transition of flexibility at the junction of the catheter body and the intermediate section, which allows this junction to bend smoothly without bending or wrinkling. A catheter provided with said spacer is described in US Patent Application No. Ser. 08 / 924,616, entitled Steerable Direct Myocardial Revascularization Catheter, the complete description of which is incorporated herein by reference.

Extending from the distal end of the intermediate section 14 is the tip section 36 which includes an electrode tip 37 and a plastic housing 21 as shown in figures 5A and 5B. The plastic housing 21 connects the tip electrode 37 and the tube 19 and provides components that extend through its light with housing and / or transitional space, as further discussed below. The plastic housing 21 is preferably produced from polyetheretherketone (PEEK) and can be about 1 cm long. Its proximal end is received in an external circumferential slot 27 (FIGURES 3A and 3B) formed at a distal end of the tube 19 of the intermediate section 14. The intermediate section 14 and the plastic housing 21 are fixed by glue or the like. Components such as wires, cables and pipe segments that extend between the middle section 14 and the tip electrode 38 can help to hold the tip electrode in place.

The tip electrode dome 37 has an open proximal end that communicates with a generally hollow distal portion or cavity 49. The tip electrode includes an optically 30 transmitter if not optically transparent casing 38 of a generally uniform thickness in which a carbon nanotube film or electrically conductive coating 39 is deposited. The tip electrode further includes a pressure plug or alignment member 44 which is positioned at or near the proximal end of the housing.

The housing 38 is configured with a dome shape or similar at its distal end to facilitate omnidirectional lighting and light collection. Its exterior with film 39 in it is configured in an atraumatic way and is adapted for contact with fabric. The housing is configured with a plurality of perforated holes or openings 87 for the purpose of irrigation / infusion. The enclosure is formed from any suitable material that is optically transparent, including glass or plastic. And because the carbon nanotube film 39 is suitably thin for optical transparency, the tip electrode casing functions as an omnidirectional illuminator and collector. Thus, the dome-shaped tip electrode 37 is configured for ablation and illumination and collection of light from the tissue by optical spectroscopy. For the latter functions, optical fibers are in communication with cavity 49, as explained in more detail below.

Plug 44 has a generally elongated cylindrical configuration with a predetermined length and a generally circular cross section. A distal portion of plug 44 is snapped into the open proximal end of the tip electrode 37 to seal the hollow cavity 49, while a proximal portion of the plug 44 extends proximally from the tip electrode 37 for attachment to the housing

21. As shown in FIGURE 6, several holes and blind passages are provided in the plug to allow components to be anchored to the plug or to pass through the hollow cavity 49. In the illustrated embodiment, there are blind holes 102, 104 and 106 in which the distal ends of the copper wire 40, the thermocouple wires 41 and 45 and the location sensor 72 are anchored, respectively. There are also passages 112, 116 through which the optical fibers 43 extend, and the passage 110 through which the irrigation pipe segment 48 extends. The component portions that extend through the passages in the plug are firmly fixed to the passages by glue, adhesive or the like. The passages help to align, stabilize and secure the various components that extend through the plug 44.

According to a feature of the present invention, catheter 10 is adapted to facilitate real-time assessment based on optics of tissue ablation characteristics, including without limitation, lesion formation, lesion penetration depth, cross-sectional area injury, formation of carbonization during ablation, recognition of carbonization during ablation, differentiation of carbonization from non-carbonized tissue, clot formation around the ablation field 10, differentiation of coagulated blood from non-coagulated blood, differentiation of the tissue removed by ablation in relation to healthy, tissue proximity, and recognition of vapor formation in the tissue to prevent bubbles from steam. These assessments are carried out by measuring the light intensity at one or more wavelengths that are recaptured in the catheter resulting from the light radiated from the tip of the catheter in the tissue removed by ablation. In this regard, the optical fibers 43E extend into the tip electrode 37 to transmit light to the tip electrode and the optical fiber 43R collects light from the tissue for said tissue evaluation in real time based on optics.

Fiber optic cables 43 are housed with protection in the catheter from the control rod 16 to the tip section 36. As shown in figures 2B and 4, it extends through the central light 18 of the catheter 12 and the lights 32 , 34 and 35 of the intermediate section 14. It extends through the plastic housing 21 and into the tip electrode 37 through passages 112 in plug 44. The passages help to minimize the tension in the fibers 43 in their transition between the intermediate section 14 and the tip electrode 37.

In the described embodiment, there are three 43E emitting fibers and one 43R receiving fiber. The 43E fibers act as a light emitter when transmitting light to the tip electrode 37 from a remote light source. The 43R fiber acts as a light receiver when collecting light from the hollow cavity 49 in the tip electrode 37. Each of the 43T and 43R cables can be a single fiber optic cable or fiber bundles. They can be made of simple fibers (also known as mono-modal or unimodal), multi-modal (with step index or graduated index) or plastic optical fiber (POF), depending on a variety of factors, including but not limited to limited to the transmission coefficient, transmission bandwidth, spectral transmission width, transmission distance, cable diameter, cost, optical signal distortion tolerance and signal attenuation, etc. In addition, the sending and collecting of light can be carried out with other devices, such as air core DCE fibers, hollow waveguides, liquid waveguides and the like. It should be understood by those skilled in the art that optical waveguide, optical fibers and fiber optic cables in general serve to transmit optical energy from one end to the other, with minimal loss and are therefore used interchangeably here. Said optical devices are not exclusive and other suitable optical devices can also be used.

As the lesion forms in the tissue from the ablation performed by the tip electrode 37 of the catheter 10, its characteristics are altered as is understood by those skilled in the art. In particular, as the lesion is irradiated by light, the light is scattered and / or reflected back towards the tip electrode 37, where said light having interacted or otherwise having been affected by the quantitative information-bearing lesion and qualitative about the lesion when it re-enters the hollow cavity 49.

With its distal end inserted in the hollow cavity, the optical fiber receiver 43R collects the recaptured light which carries quantitative and qualitative information and is transmitted to an optical processing system, as described in more detail below. According to a feature of the present invention, tip section 36 serves as an optical radiator and omnidirectional collector, as well as an ablation tip.

The present catheter can also be adapted for irrigation or infusion at the tip electrode, such as for cooling the tissue field and to improve electrical conduction for deeper and larger injuries /

Fluid, for example, saline, is fed into the hollow cavity by an irrigation pipe segment 48, as shown in FIGURE 5B. The distal end of the tube segment 48 is anchored in the passage 110 (FIGURE 6) and extends proximally through the plastic housing 21, the fourth light 35 of the intermediate section 14 (FIGURE 2A), the central light 18 of the catheter body 12, and through the control rod 16 where it ends in a Luer cube 90 (FIGURE 1) or similar at a location close to the control rod. In practice, fluid can be injected by a pump (not shown) into the infusion tube 48 through the Luer hub 90, and flows into the hollow cavity 49 in the tip electrode 37, and out of the openings 87. The infusion tube 48 it can be produced from any suitable material, and is preferably produced from polyimide tube. A suitable infusion tube has an outside diameter of about 0.32 inch to about 0.036 inch and an internal diameter of about 0.28 inch to about 0.032 inch.

To energize the tip electrode 37, in particular the carbon nanotube film 39 for RF ablation, a copper wire 40 is provided. The copper wire 40 extends through the third light 34 of intermediate section 14 (FIGURE 4), the central light 18 of the catheter body 12 (FIGU20 RAS 2A and 2B), and the control rod 16, and ends at its end proximal in an entry jacket (not shown) that can be plugged into an appropriate monitor (not shown). The portion of the copper wire 40 that extends through the central light 18 of the catheter body 12, the control rod 16 and the distal end of the intermediate section 14 is enclosed in the protective sheath 52, which can be produced from any suitable material, preferably Teflon RTM. The protective sheath 52 is anchored at its distal end to the distal end of the intermediate section 14 by gluing it to the light 34 with polyurethane glue or the like.

In the described embodiment, the carbon nanotube film 39 is energized by the copper wire 40 by means of a ring electrode 55 that is mounted to overlap a junction between the plastic housing 21 and the carbon nanotube film 39 in the casing 38 of the tip electrode dome 37, as shown in figures 5A and 5B. The ring electrode can be produced from any suitable solid conductive material, such as platinum or gold, preferably a combination of platinum and iridium, and assembled with glue or the like. Alternatively, the ring electrode may be formed by coating the junction with an electrically conductive material, such as platinum, gold and / or iridium. The coating can be applied using sputtering, ion beam deposition or an equivalent technique. In another alternative embodiment, the ring electrode can be formed by repeatedly wrapping one end of the copper wire of the electrode around the junction and removing the coating from the copper wire to expose the conductive surface. Other methods for forming the ring electrode can also be used in accordance with the present invention. In the described embodiment, the ring electrode is mounted when first forming a hole in the wall of the plastic housing 21. The copper wire from electrode 40 is fed through the orifice, and the ring electrode is sealed in place over the copper wire and the carbon nanotube film 37.

A temperature reading means is provided for the tip electrode 37 in the described mode. Any conventional temperature reading medium, for example, a thermocouple or thermistor, can be used. With reference to FIGURES 5B and 6, a temperature reading means suitable for the tip electrode 37 comprises a thermocouple formed by a pair of wires. A wire in the wire pair is a copper wire, for example, a copper wire number 40. The other wire in the wire pair is a constantan 45 wire, which provides support and resistance to the wire pair. The wires 41 and 45 of the wire pair are electrically isolated from each other except at their distal ends where they come into contact and are twisted together, covered with a small piece of plastic tube 63, for example, polyimide, and covered with epoxy . The plastic tube 63 is then fixed to the hole 104 of the plug 44 by epoxy or the like. As shown in figures 2A and 5, wires 41 and 45 extend through the second light 32 in the intermediate section 14. Wires 41 and 45 extend through the central light 18 of the catheter body 12 and the light 32 of the intermediate section 14 inside the protective sheath 53. Wires 41 and 45 then extend outward through the control rod 16 and to a connector (not shown) connectable to the temperature monitor (not shown). Alternatively, the temperature reading medium can be a thermistor. A thermistor suitable for use in the present invention is Model

No. AB6N2-GC14KA143T / 37C marketed by Thermometrics (New Jersey).

With reference to FIGURES 2B and 3B, the booster wire 42 extends through the catheter body 12 and is anchored at its end proximal to the control rod 16. The booster wire is produced from any suitable metal, such as stainless steel or Nitinol, and is preferably coated with Teflon. RTM., Or the like. The coating provides lubricity to the driving wire. The lead wire preferably has a diameter ranging from about 0.006 to about 0.010 inches. A compression spring 56 is located inside the catheter body

12 in an engagement relationship with the driving wire. The compression spring 56 extends from the proximal end of the catheter body 12 to the proximal end of the intermediate section 14. The compression spring is produced from any suitable metal, preferably stainless steel, and is tightly wound over itself to provide flexibility, that is, bending, but to resist compression. The internal diameter of the compression spring is preferably relatively larger than the diameter of the driving wire 42. The Teflon.RTM coating. coating on the driving wire allows it to slide freely within the compression spring. If desired, in particular if the copper wire 40 is not enclosed by the protective sheath 52, the external surface of the compression spring can be covered by a non-conductive and flexible sheath, for example, produced from polyimide tube, to avoid contact between the compression spring and any other wires inside the catheter body 12.

As shown in FIGURE 2B, the compression spring 56 is anchored at its proximal end to the proximal end of the stiffening tube 20 in the catheter body 12 by the glue joint 50 and in its distal end to the intermediate section 14 by the glue joint 51 Both glue joints 50 and 51 preferably comprise polyurethane glue or the like. The glue can be applied by means of a syringe or the like through a hole produced between the outer surface of the catheter body 12 and the central light 18. Said hole can be formed, for example, by a needle or the like that punctures the outer wall 22 of the catheter body 12 and the stiffening tube 20 which is sufficiently heated to form a permanent orifice. The glue is then introduced through the hole to the outer surface of the compression spring 56 and flows around the outer circumference to form a glue joint about the entire circumference of the compression spring.

With reference to FIUGURES 3B and 4, the driving wire 42 extends inwardly a first light 30 of the intermediate section 14. In the described embodiment, the driving wire 42 is anchored at its distal end to a side wall of a plastic tube 21. The distal end of the driving wire 42 comprises a T-bar anchor 61 and is anchored by glue to the slot 63 in the side wall of the plastic housing 21 as shown in FIGURE 3B. Said anchoring is described in the US Patent No. 6,064,908, the complete description of which is incorporated herein by reference. Within a first light 30 of the intermediate section 14, the driving wire 42 extends through a plastic sheath, preferably Teflon.RTM., 81, which prevents the driving wire 42 from cutting inside the wall of the intermediate section 14 when the middle section is deflected. The longitudinal movement of the driving wire 42 with respect to the catheter body 12, which results in the deviation of the tip section 36, is performed by proper handling of the control rod 16. Suitable control rods are described in US Patent No. 6602242, the complete description of which is incorporated herein by reference.

In the illustrated embodiment, the tip section 36 bears an electromagnetic sensor 72, and as mentioned, the electromagnetic sensor can be arranged in the plastic housing 21, with its distal end anchored in the blind hole 106 in plug 44 as shown in figures 5A, 5B and 6. The electromagnetic sensor 72 is connected to an electromagnetic sensor cable 74. As shown in figures 2A and 4, the sensor cable 74 extends through the fourth light 35 of the tip section 36, through the central light 18 of the catheter body 12, and into the control rod 16. The electromagnetic sensor cable 74 then it extends out from the proximal end of the control rod 16 within an umbilical cord 78 (FIGURE 1) to a control sensor module 75 that houses a circuit board (not shown). Alternatively, the circuit board may be housed within the control rod 16, for example, as described in US Patent Application No. 08 / 924,616, entitled Steerable Direct Myocardial Revascularization Catheter, the description of which is incorporated herein by reference. The electromagnetic sensor cable 74 comprises multiple wires embedded in a sheath covered in plastic. In the control sensor module 75, the wires of the electromagnetic sensor cable 74 are connected to the circuit board. The circuit board amplifies the signal received from the electromagnetic sensor 72 and transmits it to a computer in the form capable of being understood by the computer through connector sensor 77 at the proximal end of the control sensor module 75, as shown in FIGURE 1 . Because the catheter can be designed for single use, the circuit board may contain an EPROM chip that closes the circuit board approximately 24 hours after the catheter has been used. This prevents the catheter, or at least the electromagnetic sensor, from being used twice. Electromagnetic sensors suitable for use with the present invention are described, for example, in US Patent Nos. 5,558,091, 5,443,489, 5,480,422, 5,546,951, 5,568,809, and 5,391,199 and International Publication No. WO 95/02995, the descriptions of which are incorporated herein by reference. An electromagnetic mapping sensor 72 can be provided with a length of about 6 mm to about 7 mm and a diameter of about 1.3 mm.

Referring to FIGURE 7, an optical processing system 126 for optically evaluating the ablation tissue using catheter 10 is illustrated. A light source 128 provides a wide band (white; multiple wavelengths) of light and / or radiation of laser light (a single wavelength) to the tip section 36 of catheter 10 via cable 127 which is divided by a beam splitter 131 emitting to the 43E emission cables. The light carrying qualitative information about the lesion from the tip section is transmitted by the receiver cable 43R to the detection component 130. The detection component can comprise, for example, a selective element of wavelength 131 that disperses the collected light at constituent wavelengths, and a quantitation apparatus 140. The at least one selective element of wavelength 131 includes optics 132, as are known in the art, for example, a system of lenses, mirrors and / or prisms, to receive the incident light 34 and divide it into the desired components 136 that are transmitted into the quantizer 140.

The quantizer 140 transforms the measured light intensities into an electrical signal that can be processed with a computer 142 and graphically displayed to a catheter 10 operator. The quantizer 140 may comprise a charged coupled device (CCD) for simultaneous detection and quantification of said light intensities. Alternatively, a number of different light sensors, including photodiodes, photomultipliers or complementary metal oxide semiconductor detectors (CMOS) can be used in place of the CCD converter. The information is transmitted from the quantification device 140 to the computer 142 where a graphic display or other information is generated with respect to the injury parameters. A system suitable for use with catheter 10 is described in US application Serial No. 11/281179 and

No. Seriai 11/281853, the complete description of which is incorporated herein by reference.

The foregoing description has been presented with reference to the currently preferred embodiments of the present invention. Those skilled in the art and technology to which the present invention belongs will note that changes and changes in the described structure can be practiced without departing from the main principles, spirit and scope of the present invention.

Thus, the foregoing description should not be read as belonging only to the precise structures described and illustrated in the accompanying drawings, but should instead be read consistent with and in support of the following claims that must have their broadest and fairest scope.