Devices for shaping therapy in fluid enhanced ablation

Abstract

To provide devices and methods for shaping an ablation treatment volume formed in fluid enhanced ablation therapy.SOLUTION: The devices and methods cause fluids to interact with each other to create ablation treatment volumes having a variety of shapes. In one embodiment, a method for forming an ablation treatment volume having a desired shape includes delivering therapeutic energy to tissue to form an ablation treatment volume and simultaneously delivering a first fluid and a second fluid to the tissue. The first and second fluids convect the therapeutic energy in a desired direction so that the ablation treatment volume has a desired shape.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This application claims priority to U.S. Provisional Application No. 61 / 474,574, filed April 12, 2011, entitled "Improvements to Ablation Catheters." This application is also related to concurrently filed U.S. application Ser. No. 13 / 445,034, entitled "Device and Method for Remote Temperature Monitoring of Fluid-Assisted Ablation Therapy," U.S. application Ser. No. 13 / 445,036, entitled "Method and Device for Heating Fluid in Fluid-Assisted Ablation Therapy," U.S. application Ser. No. 13 / 445,373, entitled "Method and Device for Controlling Ablation Therapy," and U.S. application Ser. No. 13 / 445,040, entitled "Device and Method for Utilizing Degassed Fluid in a Fluid-Assisted Ablation Device," the entire disclosures of each of which are incorporated herein by reference.

[0002] The present invention relates generally to fluid-assisted ablation (e.g., SERF® ablation technology: saline-assisted, radio frequency® ablation). More particularly, the present invention relates to devices and methods for controlling the shape of treatment zones created during fluid-assisted ablation. [Background technology]

[0003] The use of thermal energy to destroy tissue in the body can be used for a variety of treatments, including tumor destruction. Thermal energy can be delivered to tissue using a variety of fluid energies, such as radiofrequency electrical energy, microwave or light wave electromagnetic energy, or ultrasonic vibration energy. For example, radiofrequency (RF) ablation can be performed by passing a radiofrequency electrical current through the tissue by placing one or more electrodes against or within the tissue to be treated. The electrical current can be passed between closely spaced emitter electrodes or between the emitter electrodes and a larger common electrode located away from the tissue to be heated.

[0004] One drawback of these techniques is that the greatest heating occurs at or near the interface between the treatment tool and the tissue. For example, in RF ablation, the tissue immediately adjacent to the emitter electrode heats the most. This reduces the tissue's electrical conductivity and, in some cases, causes the water in the tissue to reach its boiling point and turn into water vapor. As this process continues, the tissue impedance increases, making it more difficult for the current to enter the surrounding tissue. Therefore, traditional RF techniques limit the amount of tissue that can be treated.

[0005] Fluid-assisted ablation treatments, such as SERF® ablation technology (saline-assisted radiofrequency® ablation), can treat larger volumes of tissue than traditional RF ablation. SERF ablation technology is described in U.S. Patent No. 6,328,735, which is incorporated herein by reference. Using SERF ablation technology, saline can be introduced through a needle, heated, and the heated fluid delivered to the tissue immediately surrounding the needle. The saline disperses the heat generated adjacent to the needle, allowing a larger tissue volume to be treated with a therapeutic dose of ablation energy. Treatment is typically complete when the target tissue reaches the desired treatment temperature; if this temperature is not reached, a fixed therapeutic dose of energy is delivered.

[0006] Fluid-assisted ablation therapy typically creates a spherical treatment zone in tissue surrounding the ablation device. However, there are cases where creating a non-spherical treatment zone is desirable. For example, some lesions or tumors suitable for treatment with fluid-assisted ablation are not spherical. Additionally, it may be desirable to protect certain structures, such as delicate nerve cells, that are located in close proximity to the lesion or other target tissue.

[0007] Additionally, directional treatment zones created using ablation therapy may be desirable. For example, a common treatment for arrhythmias such as atrial fibrillation utilizes catheter-based procedures that selectively ablate tissue in the atrial wall to define pathways through which electrical signals that cause the heart to beat pass. However, currently available methods for ablation therapy cannot create treatment zones comparable to these directional pathways in the ventricles. This is because currently available methods cannot heat the ventricular wall and therefore cannot be used to treat ventricular tachycardia. While fluid-assisted ablation can heat the ventricular wall, it cannot create a pathway for electrical signals because the ablation zones created are large and ablate a large portion of the heart.

[0008] Therefore, improved devices and methods for shaping the treatment zone created during fluid-assisted ablation therapy are desired. Summary of the Invention

[0009] The present invention provides devices and methods for improving ablation therapy by controlling the shape of the treatment zone. In one aspect of the present invention, a method for forming an ablation treatment volume in tissue with a desired shape includes delivering therapeutic energy to the tissue to form the ablation treatment volume in the tissue and simultaneously delivering a first fluid and a second fluid to the tissue, the first fluid and the second fluid circulating the therapeutic energy in a desired direction so that the ablation treatment volume has the desired shape.

[0010] In some embodiments, the method may further include delivering additional fluids to the tissue in combination with the first and second fluids. For example, in some embodiments, a third, fourth, fifth, etc. fluid may be introduced. Each of these fluids may be delivered to the tissue such that they interact with each other to form an ablation treatment volume of a desired shape. Any number of fluids may be utilized.

[0011] In some embodiments, the first and second fluids may be provided at different temperatures. A number of different temperatures may be selected for the first and second fluids. In some embodiments, the first fluid may be approximately 50 degrees Celsius. In other embodiments, the second fluid may be approximately 37 degrees Celsius. However, any temperature may be selected for the first or second fluid. Furthermore, the method may be utilized at a variety of locations within a patient's body. In some embodiments, the tissue may be, for example, from the heart. In other embodiments, the tissue may be from the liver. In yet other embodiments, the tissue may be from the prostate, uterus, kidney, lung, breast, or any other organ or tissue within the patient's body.

[0012] In some embodiments, the first and second fluids can be delivered by one or more elongated portions inserted into the tissue. Additionally, the method may include various other steps to facilitate shaping the ablation treatment volume. For example, the method may further include adjusting one of the fluid flow rates and fluid temperatures of either the first or second fluid to further shape the ablation treatment volume. Similarly, the method may further include adjusting a level of therapeutic energy delivered to the tissue to further shape the ablation treatment volume. In some embodiments, delivering therapeutic energy to the tissue may include activating an ablation portion configured to deliver electrical energy to the tissue. In still other embodiments, the method may further include repeatedly delivering therapeutic energy and simultaneously delivering the first and second fluids to multiple locations to form a treatment volume having an elongated planar shape.

[0013] In some embodiments, a first fluid may be supplied from first and second opposing longitudinal portions of the lumen of the elongate portion, and a second fluid may be supplied from third and fourth opposing longitudinal portions of the lumen, and the third and fourth portions may be radially offset from the first and second portions.

[0014] In yet another embodiment, supplying the first fluid includes discharging the first fluid through at least one exit hole formed in a proximal portion of the sidewall of the elongate member, and supplying the second fluid includes discharging the second fluid through at least one exit hole formed in a distal portion of the sidewall of the elongate member adjacent the proximal portion.

[0015] In yet another embodiment, the method can include removing the first and second fluids from the tissue and further shaping the ablation treatment volume. The first and second fluids can be selectively removed, for example, using the elongated portion to draw fluids from the tissue surrounding the elongated portion.

[0016] In another aspect of the invention, a method for shaping therapeutic energy delivered to tissue includes placing a first elongated portion at a first location within a patient, the first elongated portion having a lumen extending therethrough, the first elongated portion including at least one exit hole, at least one ablation portion disposed along the length of the first elongated portion, and at least one heating portion disposed within the lumen. The method further includes placing a second elongated portion at a second location within the patient, the second elongated portion having a lumen extending therethrough, the second elongated portion including at least one exit hole. The method further includes simultaneously delivering a first fluid through the first elongated portion and a second fluid through the second elongated portion, wherein the first and second fluids interact to shape an ablation treatment volume.

[0017] The method may further include various variations within the scope of the present invention. In some embodiments, for example, the first and second fluids may be at different temperatures. In other embodiments, the method further includes delivering therapeutic energy from an ablation region disposed along the first elongate portion. In this embodiment, the fluid interaction may direct energy from the ablation region to shape the tissue volume to receive the therapeutic energy.

[0018] In other embodiments, placing the first elongate portion at the first location and the second elongate portion at the second location can include placing an elongate member within the patient, the elongate member having the first and second elongate portions disposed therein. The elongate member can be, for example, a catheter or other elongate shaft or member, as described below. Additionally, in some embodiments, the second elongate portion can be positioned adjacent to a structure (e.g., a group of neurons) that is to be protected from the treatment energy.

[0019] In another aspect of the present invention, an ablation device includes an elongate portion having proximal and distal ends, a lumen extending therethrough, and at least two exit holes formed therein for supplying fluid to tissue surrounding the elongate portion. The elongate portion further includes at least one ablation portion disposed along a distal portion of the elongate portion for heating tissue surrounding the at least one ablation portion when the elongate portion is inserted into tissue. Furthermore, each of the at least two exit holes supplies fluid at a different temperature.

[0020] The ablation device may have a variety of configurations and additional features. In some embodiments, the ablation device further comprises at least one heating element associated with one or more of the two exit holes and disposed within the lumen to heat fluid flowing through the associated one or more exit holes.

[0021] In other embodiments, the ablation device may further include at least one divider disposed within the lumen and dividing the lumen into two or more sections that are not in fluid communication with one another. Furthermore, each of the two or more sections may be in fluid communication with one or more of the at least two exit holes. In certain embodiments, the at least one divider may divide the lumen into four sections extending longitudinally along the lumen, dividing the lumen into opposing pairs of quadrants. A heating section may be provided in each of a first pair of opposing quadrants to heat fluid flowing therethrough to a first temperature. A heating section may be provided in each of a second pair of opposing quadrants to heat fluid flowing therethrough to a second temperature that is lower than the first temperature. In still other embodiments, the at least one divider may divide the lumen into a proximal section and a distal section, each of which may be associated with a different ablation section. The at least one division may include at least two divisions that further divide the lumen to create a third portion proximal or distal to the distal portion. In certain embodiments, the device may further include two or more temperature sensors, each located in a different portion of the lumen.

[0022] Another aspect of the present invention provides an ablation device having an elongate member with a distal portion for delivery into a patient's body. The device further includes at least two elongate sections disposed on the distal portion of the elongate member. Each of the elongate sections includes a proximal end and a distal end, a lumen extending therethrough, and at least one exit hole disposed in the elongate section for delivering fluid to tissue surrounding the elongate section. At least one of the elongate sections includes at least one ablation section disposed along the distal portion of the elongate section, the ablation section configured to heat tissue surrounding the ablation section. Furthermore, at least one of the elongate sections includes a heating section disposed in the lumen of the elongate section, the heating section configured to heat fluid flowing within the lumen.

[0023] In some embodiments, the at least two elongate segments can include first, second, and third elongate segments disposed about the distal end of the elongate member at a fixed distance from the longitudinal axis of the elongate member. For example, the first, second, and third elongate segments can be angularly offset from one another and disposed at a specific radius from the longitudinal axis of the elongate member. In other embodiments, the first, second, and third elongate segments can be linearly disposed at the distal end of the elongate member. In this embodiment, one or more of the elongate segments can include an ablation segment.

[0024] The above-described aspects and embodiments of the present invention will be more fully understood from the following detailed description read in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0025] [Figure 1] 1 illustrates an embodiment of a fluid-assisted ablation system. [Figure 2] 1 is a perspective view of one embodiment of a medical device having an elongated portion for use in fluid-assisted ablation. FIG. [Figure 3] 1 is a graphical depiction of simulated heating profiles for various forms of ablation. [Figure 4] FIG. 10 is a side view of the distal portion of the elongate section showing the expansion of the treatment zone over time. [Figure 5] 1 is a cross-sectional schematic view of a treatment zone that can be produced with one embodiment of the fluid-assisted ablation system of the present invention. [Figure 6] FIG. 1 is a perspective view of one embodiment of an ablation device having three elongated sections extending longitudinally from a catheter. [Figure 7A] 1 is a perspective view of an embodiment of an ablation device including an elongate portion with a lumen divided into segments extending longitudinally along the lumen. FIG. [Figure 7B] FIG. 7B is a cross-sectional view of the device of FIG. 7A, with arrows indicating fluid flow and showing the treatment zones created. [Figure 8A] FIG. 10 is a side view of one embodiment of a length having multiple ablation regions disposed along the length. [Figure 8B] 8B is a semi-transparent perspective view of the elongated section of FIG. 8A divided into proximal and distal sections, each capable of receiving fluid at a constant temperature. FIG. [Figure 9] FIG. 1 is a cross-sectional view of one embodiment of a surgical site showing a first elongated portion carrying fluid at a first temperature and a second elongated portion carrying fluid at a second temperature, forming a non-spherical treatment zone. [Figure 10] FIG. 1 is a cross-sectional view of one embodiment of a surgical site showing a first elongated portion that supplies fluid and energy for treatment to the treatment zone and a second elongated portion that carries fluid away from the treatment zone. DETAILED DESCRIPTION OF THE INVENTION

[0026] The following provides exemplary embodiments to facilitate a general understanding of the principles of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will appreciate that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting example embodiments, and that the scope of the invention is defined solely by the claims. Features illustrated and described in connection with one embodiment may be combined with features of other embodiments. Modifications and variations are intended to fall within the scope of the present invention.

[0027] The terms "a" and "an" are equivalent to the terms "one or more" as used herein. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e., meaning including, but not limited to), unless expressly stated otherwise. The terms "about" and "approximately" used in connection with numerical values ​​and ranges indicate a suitable numerical tolerance within which a composition, portion, or collection of elements can achieve the intended purpose function described herein. Such terms generally imply a ±10% variation from the center value. Components described herein as "coupled" refer to either direct coupling or indirect coupling via one or more intervening elements. Numerical ranges recited herein, unless expressly stated otherwise, are provided as a shorthand method of individually referring to each separate value within the range, and each separate value within the range is incorporated into the specification as if it were individually recited. Additionally, to the extent that rectilinear or circular embodiments are used in the disclosed devices, systems, and methods, such embodiments are not intended to limit the types of shapes that may be used in connection with the devices, systems, and methods, and one of ordinary skill in the art can readily determine equivalent configurations to such rectilinear and circular embodiments for any geometric shape.

[0028] Unless otherwise specified, all methods described herein can be performed in any order. Any and all examples or example language (e.g., "e.g.", "such as") are intended solely to facilitate understanding of the present invention and do not limit the scope of the present invention unless otherwise recited in the claims. Nothing in this specification should be construed as indicating that any non-claimed element is a necessary element to practice the present invention. Furthermore, the use of the term "saline" in connection with any embodiment herein does not limit the embodiment to "saline" as distinguished from other fluids unless expressly stated otherwise. Other fluids may be used as well.

[0029] Fluid-assisted ablation system The present invention generally relates to devices and methods for shaping a treatment or therapy zone or region created using fluid-assisted ablation. Fluid-assisted ablation, as defined above, is defined as the flow of fluid through tissue while delivering therapeutic energy from an ablation site. The delivery of therapeutic energy into tissue causes hyperthermia in the tissue, ultimately resulting in necrosis. This selective tissue destruction by hyperthermia can be used to treat a variety of conditions, including tumors, fibroids, arrhythmias (e.g., ventricular tachycardia), and other disorders.

[0030] Fluid-assisted ablation treatments, such as the SERF ablation technology (e.g., SERF® Ablation Technology: Saline-Assisted Radiofrequency Ablation) described in U.S. Patent No. 6,328,735, incorporated herein by reference, involve the delivery of fluid heated to a therapeutic temperature into tissue along with ablation energy. The delivery of heated fluid increases the thermal conductivity of the tissue by a factor of 20 or more by flowing the fluid into the extracellular space of the treated tissue. Thus, the flow of heated fluid allows thermal energy from the ablation energy source to be convected deep within the target tissue. Additionally, heating the fluid to a therapeutic temperature increases the amount of energy delivered to the tissue. Finally, the fluid also helps maintain tissue hydration, preventing charring and other associated impedance increases.

[0031] FIG. 1 illustrates one embodiment of a fluid ablation system 100. The system includes an elongated portion 102 for insertion into a target volume of tissue. The elongated portion may be of various shapes and sizes depending on the shape of the target tissue. Furthermore, the specific size of the elongated portion may vary depending on various factors, including the type and location of the tissue to be treated, as well as the size of the tissue to be treated. By way of example only, in one embodiment, the elongated portion may be a thin-walled stainless steel needle measuring between about 16 and about 18 gauge (i.e., an outer diameter of about 1.27 millimeters to about 1.65 millimeters) and having a length L of about 25 cm (shown in FIG. 2). The elongated portion 102 may include a sharpened distal end 104 configured to pierce tissue and aid in the introduction of the device to the target tissue site, although in other embodiments, the distal end 104 may be blunt and have a variety of other configurations. The elongate portion 102 may be formed from an electrically conductive material and capable of conducting electrical energy along its length to one or more ablation sites located along a distal portion of the elongate portion. The emitter electrode 105 is an example of an ablation site to which RF energy can be delivered from the elongate portion.

[0032] In other embodiments, the emitter electrode 105 may be a portion of the elongated portion 102. For example, the elongated portion 102 may be coated with an insulating material along its entire length, except for the portion representing the emitter electrode 105. More specifically, in one embodiment, the elongated portion 102 may be coated with 1.5 mil of the fluoropolymer Xylan® 8840. The electrode 105 may have a variety of lengths and configurations. In one embodiment, the electrode 105 may be a 4 mm portion of the tubular elongated portion that is exposed to the surrounding tissue. Furthermore, the electrode 105 may be located anywhere along the length of the elongated portion 105 (and more than one electrode may be located along the length of the elongated portion). In one embodiment, the electrode may be located adjacent the distal end 104. In other embodiments, the elongated portion may be formed of an insulating material, and the electrodes may be located around the elongated portion or between portions of the elongated portion.

[0033] In other embodiments, the electrodes can be formed from a variety of other materials suitable for conducting electrical current. Any metal or metal salt can be utilized. In addition to stainless steel, examples of metals include platinum, gold, or silver, and examples of metal salts include silver / silver chloride. In one embodiment, the electrodes can be formed from silver / silver chloride. It has been found that metal electrodes can assume a voltage potential different from that of the surrounding tissue and / or fluid. Applying electrical current to this power difference can result in energy dissipation at the electrode / tissue interface, exacerbating overheating of the tissue near the electrode. One advantage of utilizing metal salts such as silver / silver chloride is their high exchange current density. This results in minimal power drop when a large amount of current passes from the electrode to the tissue, thereby minimizing energy dissipation at this interface. Therefore, electrodes formed from metal salts such as silver / silver chloride can reduce excessive energy dissipation at the tissue interface and produce a more desirable therapeutic temperature profile without the need for fluid flow around the electrode.

[0034] The electrode 105 or other ablation portion may include one or more exit holes configured to deliver fluid from a lumen 106 (shown by arrow 109) extending through the elongated portion 102 to surrounding tissue. Alternatively, the electrode 105 may be located adjacent to one or more exit holes 108 formed in the elongated portion 102. In many embodiments, locating the electrode adjacent to one or more exit holes can maximize the therapeutic effect of the delivered fluid. The exit holes 108 may be formed in various sizes, numbers, and pattern configurations. Additionally, the exit holes 108 can direct fluid in various directions relative to the elongated portion. These may include a normal orientation (i.e., perpendicular to the surface of the elongated portion), as shown by arrow 109 in FIG. 1, and proximal and distal directions along the longitudinal axis of the elongated portion 102 (including various directions that create a circular or spiral flow of fluid around the elongated portion). Additionally, in some embodiments, the elongated portion 102 may be formed with an open distal end that functions as an exit hole. By way of further example, in one embodiment, 24 evenly spaced exit holes 108 having a diameter of approximately 0.4 mm may be formed around the periphery of the electrode 105 using an electrical discharge machine (EDM). Those skilled in the art will appreciate that other manufacturing methods may be used to create the exit holes 108. Additionally, in some embodiments, the exit holes may be formed along a portion of the length adjacent the electrode, rather than in the electrode itself.

[0035] The lumen 106, which communicates with the exit hole 108, may house a heating assembly 110 configured to heat the fluid as it passes through the lumen 106 just prior to entering the tissue. A detailed description of various embodiments of the heating assembly 110 suitable for use in the devices and methods of the present invention is detailed in commonly filed and related U.S. application Ser. No. 13 / 445,036, entitled "Method and Device for Heating Fluid in Fluid-Assisted Ablation Treatment," previously incorporated by reference in its entirety.

[0036] The portion of the elongate section distal to the electrode 105 or other ablation section is solid (or filled), with a lumen 106 terminating at the distal end of the electrode 105. In one embodiment, the volume of the portion of the elongate section distal to the electrode can be secured with an epoxy using an interference fit. In another embodiment, the portion of the elongate section distal to the electrode can be formed from solid metal and connected to the proximal portion of the elongate section using welding, staking, or other known techniques.

[0037] Fluid may be supplied to the lumen 106 and the heating assembly 110 from a fluid reservoir 112. The fluid reservoir 112 may be connected to the lumen 106 through a fluid conduit 114. The fluid conduit 114 may be, for example, a long length of flexible plastic tubing. The fluid conduit 114 may also be a rigid tube or a combination of rigid and flexible tubing.

[0038] Fluid may be drawn into lumen 106 from fluid reservoir 112 by pump 116. Pump 116 may be a syringe-type pump that dispenses a fixed volume by advancing a plunger (not shown). An example of such a pump is the Model 74900 sold by Cole-Palmer Corporation of Chicago, Illinois. Other types of pumps, such as diaphragm pumps, may also be used.

[0039] The pump 116 may be controlled by a power supply / controller 118. The power supply / controller 118 provides electrical control signals to the pump 116 to cause the pump to produce fluid at a desired flow rate. The power supply / controller 118 may be connected to the pump 116 by an electrical connection 120. The power supply / controller 118 may also be electrically connected to the elongated portion 102 by connection 122 and to the collector electrode 124 by connection 126. Additionally, the power supply / controller 118 may be connected to the heating assembly 110 by similar electrical connections.

[0040] The collector electrode 124 can take a variety of forms. For example, the collector electrode 124 can be a large electrode located outside the patient's body. In other embodiments, the collector electrode 124 can be a return electrode located somewhere along the elongated portion 102, or it can be located inside the patient on a second elongated portion that is introduced near the treatment site.

[0041] In operation, the power supply / controller 118 may supply fluid to the target tissue at a desired flow rate, heat the fluid to a desired treatment temperature, and deliver therapeutic ablation energy to one or more ablation elements (e.g., electrodes 105). To accomplish this, the power supply / controller 118 itself may include multiple components for generating, regulating, and delivering the necessary power control and therapeutic energy signals. For example, the power supply / controller 118 may include one or more frequency generators for generating one or more RF signals of a certain amplitude and frequency. These signals may be amplified by one or more RF power amplifiers to relatively high voltage, high amperage signals (e.g., 50 volts at 1 ampere). These RF signals may be carried to the ablation element by one or more electrical connections 122 and the elongated element 102, passing RF energy between a collector electrode 124 and an emitter electrode 105 located remotely from the patient's body. In embodiments in which the elongate portion is formed of a non-conductive material, one or more electrical connections 122 may extend into the lumen of the elongate portion or through its outer surface to supply current to the emitter electrode 105. RF energy may be passed between the ablation portion and the collector electrode 124 to heat the tissue surrounding the elongate portion 102 due to the tissue's inherent electrical resistance. The power supply / controller 118 may further include a directional coupler that may supply a portion of one or more RF signals to, for example, a power monitor to adjust the RF signal power to a desired treatment level.

[0042] The elongate portion 102 shown in FIG. 1 may be configured for insertion into a patient's body in a variety of ways. FIG. 2 illustrates an embodiment of a medical device 200 having an elongate portion 202 at its distal end configured for laparoscopic or direct insertion into a target area of ​​tissue. In addition to the elongate portion 202, the device 200 may include a handle 204 that allows an operator to manipulate the device. The handle 204 may include one or more electrical connections 206 that connect various components of the elongate portion (e.g., the heating assembly and the ablation portion 205, etc.) to, for example, the power supply / control 118 described above. The handle 204 may also include at least one fluid conduit 208 for connecting a fluid source to the device 200.

[0043] While device 200 is one example of an embodiment of a medical device that may be adapted for use in fluid-assisted ablation, several other devices may also be utilized. For example, a very small elongated section may be required for the treatment of arrhythmias such as ventricular tachycardia. In this case, for example, an appropriately sized elongated section may be provided at the distal end of a catheter configured for insertion through the circulatory system into the heart. In one embodiment, a stainless steel needle (between about 20 and about 25 gauge, i.e., having an outer diameter of about 0.5 to about 0.9 millimeters) may be provided at the distal end of the catheter. The catheter may be of various sizes, but in some embodiments, may be approximately 120 cm long and approximately 8 French in diameter ("French" is a unit used in the catheter industry to describe catheter size and is equal to three times the diameter of the catheter measured in millimeters).

[0044] <Treatment procedures using fluid-assisted ablation> Ablation typically utilizes high or low temperatures to selectively necrotize and / or remove tissue. The thermal destruction of tissue achieved by ablation has a known time-temperature relationship. The threshold temperature for irreversible thermal damage to tissue is generally accepted to be approximately 41°C. It has also been shown that the time required to achieve a specific level of cell necrosis decreases as treatment temperatures increase above 41°C. While the exact time / temperature relationship is known to vary depending on the cell type, a general relationship exists that can be used to determine the appropriate thermal dose level for many cell types. This relationship is typically expressed as the equivalent time at 43°C, expressed as follows:

number

[0045] FIG. 3 illustrates the performance profiles of several ablation techniques by showing simulated temperatures achieved at certain distances from an ablation site, such as electrode 105. The first profile 302 shows the performance of RF ablation without fluid assistance. It can be seen that tissue temperature drops rapidly with distance from the electrode. This indicates that within 10 millimeters of the ablation site, tissue temperature is still approximately body temperature (37°C), significantly lower than the aforementioned therapeutic temperature of 50°C. Furthermore, immediately adjacent to the ablation site, temperatures are very high, meaning that the tissue dehydrates very quickly, drying out completely and charring. This dramatically increases tissue impedance, making it difficult to deliver energy to tissue far from the ablation site.

[0046] The second tissue temperature profile 304 relates to a second prior art system similar to that described in U.S. Pat. No. 5,431,649. In this second system, electrodes are inserted into the tissue and a 400 kHz RF current of approximately 525 mA is applied to heat the tissue. Simultaneously, a saline solution at body temperature (37°C) is injected into the tissue at a rate of 10 ml / min. The resulting tissue temperature profile 304 is more uniform than profile 302, but still has a maximum temperature of approximately 50°C at any location. Thus, temperature profile 304 exceeds the commonly accepted threshold temperature for tissue damage after one minute of treatment in only a small portion of the tissue. As discussed above, such a small temperature increase requires a long treatment time to achieve a meaningful therapeutic effect.

[0047] A third tissue temperature profile 306 was achieved utilizing the teachings of the present invention. In the illustrated embodiment, a silver / silver chloride electrode is inserted into tissue and 525 mA of 480 kHz RF current is applied to heat the tissue. Simultaneously, a saline solution heated to 50°C is infused at a rate of 10 ml / min. The resulting temperature profile 306 is uniform and significantly exceeds the therapeutic threshold temperature of 50°C at a distance of 15 millimeters from the electrode. Furthermore, because the temperature is uniform throughout this volume, the thermal dose delivered is also uniform throughout this volume.

[0048] The uniform temperature profile of FIG. 3 can be achieved by introducing a heated fluid into the target tissue during the application of ablation energy. The fluid allows heat to circulate deep within the tissue, thereby reducing charring and impedance changes near the ablation site, as shown in profile 302. Furthermore, because the fluid is heated to therapeutic levels, it does not act as a heat sink, lowering the temperature of the surrounding tissue, as shown in profile 304. Therefore, the simultaneous application of RF energy and perfusion of a heated saline solution to the tissue eliminates dehydration and / or vaporization of tissue adjacent to the electrodes, maintains the effective tissue impedance, and enhances thermal transport within the tissue being heated by the RF energy. This also increases the total volume of tissue that can be heated to therapeutic temperatures (e.g., temperatures above 41°C). For example, experimental testing has shown that a volume of tissue approximately 8 centimeters in diameter (i.e., approximately 156 cm) can be heated using the fluid-assisted ablation techniques described herein for 5 minutes. 3 In comparison, conventional RF can treat approximately 3 centimeters (or 14 cm) of tissue in the same 5-minute period. 3 It can only handle volumes of 1000 x 1000 (the spherical volume of 1000 x 1000).

[0049] Additionally, the fluid-assisted ablation devices of the present invention have numerous parameters that can be varied to tailor the shape of the treatment profile depending on the tissue being treated. For example, when utilizing SERF ablation techniques, an operator or control system can adjust the temperature profile 306 by changing parameters such as saline temperature (e.g., from about 40° C. to about 80° C.), saline flow rate (e.g., from about 0 ml / min to about 20 ml / min), RF signal power (e.g., from about 0 W to about 100 W), and treatment duration (e.g., from about 0 minutes to about 10 minutes). Additionally, a variety of different electrode configurations can be utilized to modify the treatment. For example, while the emitter electrode 105 shown in FIG. 1 is configured as a continuous cylinder for unipolar current, the electrode may be configured in other shapes, such as a sphere or a spiral, that provide a continuous surface area, or the electrode may include multiple discrete segments. The electrodes may be configured for bipolar use, with one electrode (or a portion of an electrode) acting as a cathode and another electrode (or another portion) acting as an anode.

[0050] A suitable fluid for use in SERF ablation techniques is sterile normal saline (defined as a saline solution). However, other fluids (such as Ringer's solution or concentrated saline) may also be used. A fluid may be selected that provides the desired therapeutic and physical properties when applied to the target tissue; sterile fluids are recommended to protect the tissue from infection.

[0051] Shaping the fluid in the treatment zone As discussed above, the ablation energy generally spreads from the ablation site (e.g., emitter electrode 105) in a spherical pattern, forming a generally spherical ablation therapy treatment zone, volume, or area (i.e., an area that reaches a therapeutic temperature and receives a therapeutic dose of ablative energy over a period of time, as discussed above). The diameter of the spherical treatment zone may increase as the treatment time increases.

[0052] One embodiment of this behavior is illustrated in FIG. 4, which shows an embodiment of an ablation device 400 including an elongated portion 402 having a distal end 404 and an emitter electrode 405. A plurality of exit holes 408 may be disposed along the outer surface of the emitter electrode 405 to deliver fluid to the tissue surrounding the elongated portion 402. The heated fluid exits the exit holes 408, and ablation energy is delivered to the tissue by the emitter electrode 405, creating a treatment zone, defined by the dashed line labeled T1, at a first time. While shown as a two-dimensional circle, those skilled in the art will understand that the treatment zone is three-dimensional and has an approximately spherical shape. As the treatment time increases, the diameter of the treatment zone increases until it reaches the dashed line labeled T2 at a second time, which is longer than the first time. Similarly, at a third time, which is longer than the second time, the treatment zone reaches the dashed line labeled T3.

[0053] However, in certain situations, it may be desirable to deliver therapeutic amounts of ablation energy to tissue volumes that are not spherical. For example, in some embodiments, ablation may be performed on fibroids, tumors, or other lesions that are not symmetrical or spherical. In other embodiments, the tissue volume to be treated may be in close proximity to other tissue structures (e.g., nerve cells or other healthy tissue) that should not be treated. In some embodiments, it may be desirable to create a treatment region with a well-defined direction (e.g., a plane of tissue to be ablated, with a length and thickness). An example of the use of a directional treatment region is in the ablation treatment of arrhythmias (e.g., ventricular tachycardia). In this treatment, ablation is used to create directional pathways to guide the electrical waves that control the heartbeat and prevent errant signals that may cause the tachycardia. These pathways are often created in vertical planes in the heart wall.

[0054] The present invention provides devices and methods for creating these types of directional or non-spherical treatment regions during fluid-assisted ablation therapy. Generally, the devices and methods of the present invention operate with fluids of varying temperatures to shape the treatment region. In one embodiment, a fluid heated to a treatment temperature may be introduced into tissue at one or more locations along a length, and a cooler fluid may be introduced at one or more additional locations along the same or another length. In certain regions surrounding one or more lengths, the hot fluid mixes with the cooler fluid and is quenched (i.e., the heated fluid cools below the treatment temperature). This quench prevents the delivery of therapeutic amounts of ablation energy to certain locations. Selection of the relative locations of the fluid sources and operating parameters, such as flow rate and temperature, allows for greater control and customization of the treatment region created during fluid-assisted ablation therapy. Those skilled in the art will appreciate that the various methods and devices disclosed herein can be utilized to create treatment regions of any desired shape.

[0055] <Multibody systems> FIG. 5 illustrates one embodiment of a system of the present invention. This figure shows a top cross-sectional view of one embodiment of a fluid-assisted ablation system having multiple elongated sections for delivering fluids at various temperatures (the elongated sections are described later on this page). In particular, a first elongated section 502 may be located approximately in the center of the treatment volume. The first elongated section 502 may be similar to the elongated section 102 described above. As shown, a second elongated section 504a and a third elongated section 504b may be located adjacent to the first elongated section 502. The second and third elongated sections 504a, 504b may, in some embodiments, be similar to the elongated section 102 described above. However, in other embodiments, the second and third elongated sections are not utilized to deliver therapeutically heated fluids or ablation energy, and therefore may not include one or more of the ablation sections and heating assemblies of the elongated section 102. In certain embodiments, the heating assembly may remain in the second and third elongated portions 504a, 504b and heat the fluid flowing through these members to an elevated temperature (e.g., above body temperature but below a therapeutic threshold, although the elevated temperature may be any temperature).

[0056] In use, fluid from a first fluid source is delivered to the tissue surrounding the first elongated portion 502 by passing the fluid through the lumen, heating the fluid, and exiting the fluid through at least one exit hole formed in the sidewall of the elongated portion 502 as described above. The heated fluid may be at a therapeutic temperature, for example, between about 45°C and about 80°C. In one embodiment, the fluid may be heated to about 50°C. Additionally, a second, lower temperature fluid may be delivered to the tissue surrounding the second and third elongated portions 504a, 504b from the same or a different fluid source. The cold fluid may be at any temperature below the temperature of the fluid delivered within the elongated portion 502. In one embodiment, the cold fluid may be between about 25°C and about 41°C, although any temperature fluid capable of quenching a given amount of heat can be utilized. The flow of fluid from each of the first, second, and third elongated sections 502, 504a, 504b is represented by arrows in Figure 5. As described above, the hotter fluid from the first elongated section 502 may mix with the cooler fluid from the second and third elongated sections 504a, 504b to prevent certain areas of tissue from reaching treatment temperatures and causing tissue damage. This fluid interaction, and thus the selective thermal quenching in the tissue, creates an elliptical-shaped treatment volume (dashed line labeled A1 in Figure 5). Those skilled in the art will appreciate that although the treatment region A1 in Figure 5 is shown as elliptical, the treatment volume may extend in three dimensions and resemble an elliptical disk or sphere compressed on opposite sides by the fluid flow from the second and third elongated sections 504a, 504b.

[0057] The configuration of Figure 5 is one of various possible configurations for the fluid-assisted ablation systems disclosed herein. For example, in certain embodiments, more than one elongate section may be configured to deliver therapeutically heated fluid or heated fluid and ablation energy. Similarly, more or less than two elongate sections 504a, 504b may be used to deliver cooled fluid to areas adjacent to one or more elongate sections used to ablate tissue. As a result, any number of elongate sections delivering fluid to tissue may be used to create multiple different three-dimensional treatment zone shapes. Furthermore, one or more elongate sections may be positioned in various locations relative to one another. Variations may include angular adjustments (e.g., positioning the third elongated portion 504b to the left of the first elongated portion 502 rather than below it), distance adjustments (e.g., positioning the third elongated portion 504b further away from the first elongated portion 502), and vertical adjustments (e.g., moving the second elongated portion 504a normal to the plane of the figure). Additionally, various temperatures may be selected for the fluid delivered within any of the elongated portions. In one embodiment, the fluid flowing through the first elongated portion 502 may be heated to a therapeutic temperature. The fluid flowing through the second and third elongated portions 504a and 504b may be heated to any temperature below the therapeutic temperature. For example, the fluid may be delivered at body temperature without being actively heated, or the fluid may be delivered at a temperature below body temperature. Furthermore, the flow rates and temperatures of the fluids delivered through the first, second, and third elongated portions may vary from the configuration shown in FIG. 5 . Additionally, the ablation energy delivered by any of the ablation segments within the elongated section can be varied, and any number of elongated sections can be placed within or around the treatment zone to achieve the desired treatment.

[0058] The elongated portions 502, 504a, 504b shown in FIG. 5 can be introduced and positioned within a target volume of tissue in a variety of ways. For example, three separate devices similar to medical device 200 described above may be utilized. However, in some embodiments, an ablation device may be provided with multiple elongated portions attached, each of which may be coupled to the same or different fluid sources, heating assemblies, and ablation portions, as desired. FIG. 6 illustrates one embodiment of a device 600 that may include an elongated shaft 610, a first elongated portion 602, a second elongated portion 604a, and a third elongated portion 604b. The first elongated portion 602 may be configured to deliver fluid heated to a therapeutic temperature to the surrounding tissue, for example, along with ablation energy from an emitter electrode 605. The second and third elongated portions 604a, 604b may be configured to deliver a cooler fluid than the first elongated portion 602 to the surrounding tissue. Additionally, each of the elongate portions 602, 604a, 604b may have one or more exit holes 606a, 606b, 606c configured to deliver fluid from the lumen of the respective elongate portion 602, 604a, 604b to surrounding tissue.

[0059] The elongate shaft 610 may have a variety of sizes and configurations. For example, in some embodiments, the elongate shaft may be a catheter configured for introduction into a patient's body via a circulatory system. In one embodiment, the catheter may be approximately 12 French. The size of each of the first, second, and third elongate sections 602, 604a, 604b may correspond to the overall diameter of the catheter utilized as the elongate shaft 610. In one embodiment, each elongate section may be a 27-gauge stainless steel needle section (i.e., having an outer diameter of approximately 0.4 mm). In another embodiment, the elongate shaft 610 may be configured as a laparoscopic device similar to the medical device 200 described above.

[0060] The elongated portions 602, 604a, 604b can be arranged in various configurations relative to the elongated shaft 610. In the embodiment shown in FIG. 6, the elongated portions 602, 604a, 604b can be evenly spaced along an axis D that defines a diameter of the elongated shaft 610. More specifically, the first elongated portion 602 can be located in a central portion of the elongated shaft 610, and the first and second elongated portions 604a, 604b can be located along the axis D outside the diameter of the elongated shaft. The elongated portions 602, 604a, 604b can extend in a direction substantially parallel to the longitudinal axis L of the elongated shaft 610. In other embodiments, the elongated portions 602, 604a, 604b, or at least the second and third elongated portions 604a, 604b, may be configured to slide along axis D to adjust the spacing between the elongated portions 602, 604a, 604b. In yet another embodiment, the elongated portions 602, 604a, 604b may be angularly offset from one another at a particular radius from the longitudinal axis L. For example, the elongated portions 602, 604a, 604b may be positioned at a fixed distance from the longitudinal axis L, 120 degrees from each other. In this embodiment, an ablation portion may be positioned on each elongated portion 602, 604a, 604b, and different power levels, fluid flow rates, and fluid temperatures may be used to create desired treatment zones.

[0061] As described above, the first elongated portion 602 may include an ablative portion, such as an emitter electrode 605, configured to deliver RF energy to heat tissue surrounding the elongated portion 602. In certain embodiments, the second and third elongated portions 604a, 604b may also include an ablative portion (e.g., the ablative portion may operate at a very low temperature or may be turned off during treatment), or in some embodiments, may not include an ablative portion at all. Additionally, each of the elongated portions 602, 604a, 604b may include a heating assembly disposed within the lumen and configured to heat the fluid flowing therethrough. The heating assembly utilized may be similar to that described in related U.S. Application No. 13 / 445,036, entitled "Method and Device for Heating Fluid in Fluid-Assisted Ablation Treatment," filed concurrently herewith and incorporated by reference in its entirety as described above. As noted above, in some embodiments, the second and third elongate sections 604a, 604b may or may not include a heating assembly, and the heating assembly included in each of the second and third elongate sections may be kept off when heating is not needed or desired. Furthermore, one skilled in the art will appreciate that an elongate shaft may have any number of elongate sections thereon, and the elongate sections may be oriented at various angular orientations relative to the catheter.

[0062] <Standalone device> Effective shaping of the treatment zone created during fluid-assisted ablation therapy can also be achieved using devices with only a single elongate portion. For example, in one embodiment, an ablation device may include a elongate portion in which a lumen is divided into two or more portions that are not in fluid communication with each other, each of which may be in communication with a common or separate fluid source, and each of which may have one or more separate exit holes located along the elongate portion. In this manner, fluids may be delivered at different temperatures to different regions surrounding the elongate portion. After exiting the one or more exit holes, the fluids mix, selectively quenching the heat in certain regions of the tissue surrounding the elongate portion. This selective quenching prevents tissue damage and allows for shaping of the volume of tissue that receives the therapeutic amount of energy.

[0063] 7A shows one embodiment of a unitary ablation device 700 including a length 702 with a lumen 706 divided into multiple portions in the form of quadrants 706a, 706b, 706c, and 706d by multiple interior walls w1, w2, w3, and w4. Each quadrant 706a, 706b, 706c, and 706d therefore defines a separate lumen extending through the length 702. Those skilled in the art will appreciate that other configurations of lumens may be formed in the length, and that a length may have any number of lumens. The device 700 further includes a sharpened (or shaped) distal end 710, an ablation portion (e.g., an emitter electrode) 705, and multiple exit holes 708.

[0064] The interior walls w1, w2, w3, and w4 extend the entire length of the elongated portion 702, and the quadrants 706a, 706b, 706c, and 706d they define are not in fluid communication with one another. The interfaces between the interior walls w1, w2, w3, and w4 and the interior walls of the elongated portion 702 may include features such as a sealant or adhesive that prevent fluid from leaking between the quadrants 706a, 706b, 706c, and 706d. Additionally, the interior walls w1, w2, w3, and w4 may be formed of or coated with an insulating material (which may be thermally or electrically insulating) to prevent heated fluid in one quadrant from warming the fluid in an adjacent quadrant. For example, the interior walls w1, w2, w3, and w4 may be formed of or coated with the same fluoropolymers described above for the elongated portion 102. In some embodiments, thermal isolation may not be necessary, for example, at high fluid flow rates (e.g., 10 ml / min or greater), the time required for fluid to flow through lumen 706 is reduced, reducing the amount of heat transfer that can occur between adjacent quadrants.

[0065] Each of the quadrants 706a, 706b, 706c, and 706d may be in fluid communication with one or more of the outlet holes 708. For example, in the embodiment shown in FIG. 7A , quadrant 706a of lumen 706 may be in fluid communication with one or more of the outlet holes 708 that direct fluid in the positive y-direction. Conversely, quadrant 706b may be in fluid communication with one or more of the outlet holes 708 that direct fluid in the negative y-direction. Similarly, quadrants 706c and 706d may be in fluid communication with one or more of the outlet holes 708 that direct fluid in the negative x-direction and positive x-direction, respectively. One skilled in the art will understand that each of the quadrants 706a, 706b, 706c, and 706d may be in fluid communication with different outlet holes than those shown in FIG. 7A , and that any number of outlet holes may be provided at various locations along the elongate portion 702.

[0066] FIG. 7B is a cross-sectional view of the device of FIG. 7A. As shown, fluid ejected from quadrants 706c, 706d of lumen 706 may be heated to a therapeutic temperature by a separate heating assembly (not shown) located within each quadrant. Meanwhile, fluid ejected from quadrants 706a and 706b may be at a second temperature that is less than the therapeutic temperature of the fluid delivered from quadrants 706c and 706d. As discussed above, the second temperature may be less than, equal to, or greater than body temperature but less than the selected therapeutic temperature. Furthermore, this second temperature may be achieved by delivering fluid at the second temperature or by utilizing a separate heating assembly (not shown) in quadrants 706c, 706d to heat the fluid flowing therethrough to the second temperature. Upon entering the tissue surrounding elongate portion 702, the fluid from each quadrant mixes, forming a thermal boundary, indicated by the dashed lines. These boundaries can define treatment zones A2 and A3 that reach a therapeutic temperature sufficient to deliver a therapeutic dose of ablation energy over a period of time. Tissue outside of zones A2 and A3 is prevented from receiving a therapeutic dose of ablation energy by the cooler fluid emitted from quadrants 706a and 706b. Those skilled in the art will appreciate that each of quadrants 706a, 706b, 706c, and 706d can emit fluid at different temperatures and flow rates to create treatment zones of various different shapes.

[0067] 8A and 8B illustrate another embodiment of a unitary ablation device 800 configured to deliver fluids at various temperatures to a treatment volume. Compared to the longitudinally extending portion of device 700 shown in FIGS. 7A and 7B , device 800 may be divided into distal and proximal portions 802 a, 802 b. As shown in FIG. 8A , ablation device 800 may include an elongated portion 802 that is divided into distal and proximal portions 802 a, 802 b by a buffer portion 803. The buffer portion 803 may be an interior wall that separates the lumen of the distal portion 802 a of the elongated portion from the lumen of the proximal portion 802 b of the elongated portion.

[0068] Each segment 802a, 802b may include an emitter electrode 805a, 805b, as well as one or more exit holes 808a, 808b disposed along the elongated portion 802 and / or an emitter electrode 805a, 805b in fluid communication with the lumen of the respective segment. The segments 802a, 802b further include one or more temperature sensors 804a, 804b disposed along the elongated portion and configured to sense the temperature of tissue surrounding the elongated portion 802. The temperature sensors can be implemented in a variety of ways, and in some embodiments, the sensors can be chrome-constantan fine-wire thermocouples (CRC thermocouples) embedded in holes formed in the sidewalls of the elongated portion 802. The temperature sensors 804a, 804b can be located anywhere along the elongated portion 802, but in some embodiments, the temperature sensors 804a, 804b can be symmetrical about the ablation segments 805a, 805b. This configuration allows for accurate measurement of the uniformity of expansion of the treatment zone. Further information regarding temperature sensors can be found in related U.S. application Ser. No. 13 / 445,034, entitled "Device and Method for Remote Temperature Monitoring of Fluid-Assisted Ablation Therapy," which was filed concurrently herewith and is incorporated by reference in its entirety as noted above.

[0069] Dividing elongate portion 802 into sections 802a and 802b allows for adjustments to be made to the treatment zone if uneven heating is detected by temperature sensors 804a and 804b. For example, the illustrated device is particularly useful when fluid is delivered from both sections 802a and 802b at a uniform temperature along with ablation energy from electrodes 805a and 805b, but the temperature recorded by temperature sensor 804a is higher than the temperature recorded by sensor 804b. To adjust the treatment zone to achieve more uniform heating, the delivery of ablation energy from electrode 805a can be reduced or stopped. Additionally, the temperature of the fluid exiting one or more exit holes 808a in distal portion 802a can be reduced. Furthermore, the fluid flow rate can be reduced, if appropriate. Each of these actions can reduce heat generated in the tissue surrounding distal portion 802a and aid in expelling heated fluid from the exit holes in proximal portion 802b toward temperature sensor 804b and the tissue surrounding elongate portion 802 in that region. One skilled in the art will appreciate that opposite steps (e.g., increasing the ablation energy or increasing the temperature of the saline solution) can also be applied to portion 802a to increase the amount of heat delivered to that region. Furthermore, if the opposite condition is observed, any of the steps described above can be reversed to create a higher temperature near temperature sensor 804a. Furthermore, the steps listed above can be performed in any order, individually, or simultaneously, depending on the amount of treatment desired or required.

[0070] FIG. 8B is a semi-transparent view of the device of FIG. 8A , illustrating the internal configuration of one embodiment of an elongate portion in which the proximal and distal sections are separated by one or more buffer sections 803. As shown, the lumen of distal section 802a may be separated from proximal section 802b by baffle section 803. Baffle section 803 may be configured similarly to interior walls w1, w2, w3, and w4 described above. For example, baffle section 803 may be an integral part of elongate section 802 or may be a separate member secured to lumen 806 of elongate section 802 by adhesive or other retaining member or material. Baffle 803 may be formed, for example, from plastic or other suitable material.

[0071] Baffle portion 803 may further define one or more lumens therein, each configured to receive a cannula (e.g., cannula 810a). Cannula 810a may be formed of metal, plastic, or plastic with a metal backing and may include a lumen that provides a fluid flow path through any intervening baffles (e.g., baffle 803) and portions (e.g., proximal portion 802b) to the proximal end of device 800. The lumen of cannula 810a is not in fluid communication with the lumen of other portions (e.g., proximal portion 802b). This allows, for example, fluid to be supplied to distal portion 802a from a different fluid source than that used to supply fluid to proximal portion 802b. Alternatively, fluid may be supplied to portions 802a and 802b from a common fluid source. Lumen 806 may further include additional cannulae configured to supply fluid to other portions of device 800. For example, lumen 806 may include a cannula 810b configured to supply fluid from the proximal end of device 800 to a proximal portion 802b of the distal end of device 800.

[0072] Those skilled in the art will appreciate that lumen 806 may include multiple drains due to the device's multiple sections. Furthermore, device 800 may have any number of sections depending on the desired shape of the treatment zone. For example, device 800 may include two sections, as shown in FIGS. 8A and 8B, or may include three or more sections. In one embodiment with three sections, for example, a centrally located ablation section may be flanked on each side by one or more exit holes configured to deliver cryogenic fluid to tissue surrounding elongate section 802. In this embodiment, the flanking exit holes can compress the treatment zone along the longitudinal axis of elongate section 802.

[0073] Additionally, each cannula may be rigidly held in place by a spacer member (e.g., a member similar to baffle 803 but including one or more lumens that allow fluid to flow around the baffle) or may be suspended within lumen 806. In other embodiments, the cannula may include features formed on its outer surface to prevent contact with the inner wall of lumen 806 or other cannulae. Examples of features include fins or ribs formed on the outer surface of the cannula.

[0074] Each cannula 810a, 810b is connected to an independent or common fluid source at its proximal end. Each cannula 810a, 810b may further include an independent heating assembly disposed within the cannula's lumen near its distal end. An example of a heating assembly may include, for example, a single wire 814a, 814b extending through the cannula's lumen, configured to transmit RF energy to the cannula's inner wall via fluid in the cannula. The wire 814a, 814b may include one or more spacers to prevent the wire from directly contacting the conductive portion of the cannula 810a, 810b. For further details of the heating assembly, see U.S. Application No. 13 / 445,036, filed concurrently herewith and entitled "Method and Device for Heating Fluid in Fluid-Assisted Ablation Therapy," which is incorporated by reference in its entirety as previously mentioned.

[0075] In the example heating assembly described above, at least a portion of each of the cannulae 810a, 810b must be made of an electrically conductive material (to receive RF energy from the wires 814a, 814b). In this embodiment, the cannulae 810a, 810b are coated with an insulating material to prevent electrical shorting by contact with each other or the interior wall of the lumen 806 of the device 800. Additionally, thermal insulation may be utilized to coat the cannulae 810a, 810b to prevent the temperature of the fluid in one area from affecting the temperature of the fluid in another area. However, in some embodiments, the fluid flow velocity may be so high that the fluid cannot affect or be affected by the temperature of the fluid in one area. In these embodiments, thermal insulation of the cannulae 810a, 810b is not required.

[0076] The cannulae 810a, 810b also provide feedback regarding the temperature of the fluid being delivered to certain portions of the device 800. For example, the cannula 810a may include a dual-wire thermocouple 812a extending beyond the distal end of the cannula 810a to measure the temperature of the fluid within the distal end 802a after it exits the cannula and mixes within the lumen 806, but before it exits the cannula into the surrounding tissue through the exit hole 808a. Two thermocouple wires 820, 822 may run through the lumen of the cannula 810a and return to the proximal end of the device 810a. The thermocouple wires may be connected to signal processing electronics known in the art to measure the temperature of the fluid within the distal portion 802a. As shown, the second cannula 810b may also include a temperature sensor 812b, such as a dual-wire thermocouple formed from two wires 816, 818. Sensor 812b also extends from the distal end of cannula 810b into proximal portion 802b such that the temperature measured by sensor 812b represents the temperature of the mixed fluid being delivered to the surrounding tissue by outlet hole 808b. Those skilled in the art will appreciate that a variety of temperature sensors can be used in the devices of the present invention, including, for example, a chrome-constantan fine-wire thermocouple.

[0077] <How to use> The teachings of the present invention can be used to create treatment zones having any desired shape. Generally, this is accomplished by introducing fluid along with therapeutic energy from two or more locations (either from an ablation region or by simply heating the fluid). For example, in some embodiments, a method involves delivering ablation energy and heated fluid to one or more locations while simultaneously delivering a lower temperature fluid to one or more different locations to create the desired treatment zone shape. As a further example, in certain situations, it may be preferable to provide a generally spherical treatment volume, but to prevent a specific subset of the volume from receiving the therapeutic dose of ablation energy. For example, when using fluid-assisted ablation in the prostate region, it may be desirable to protect nearby nerve bundles that control incontinence and erectile function. Using the teachings of the present invention, this is achieved by introducing an elongated section into tissue near the structure to be protected and delivering fluid below the selected therapeutic temperature during treatment while simultaneously delivering energy to the tissue to be treated.

[0078] FIG. 9 illustrates a cross-sectional view of one embodiment of a non-spherical treatment zone (similar to FIG. 5, discussed above). As shown, the first elongated portion 902 is located approximately in the center of the treatment volume. However, the treatment volume is located adjacent to a structure 901 (e.g., a nerve bundle, healthy tissue, etc.) that is to be excluded from the ablation treatment. To accomplish this, the second elongated portion 904 can be positioned adjacent to and between the first elongated portion 902 and the structure 901. During a fluid-assisted ablation treatment, in which the first elongated portion introduces a fluid heated to a treatment temperature into the surrounding tissue along with RF energy, the second elongated portion 904 can deliver a fluid to the surrounding tissue at a temperature below the treatment temperature. As discussed above, the fluid mixes with the surrounding tissue, reducing the temperature of the tissue surrounding the structure 901 below the therapeutic level. The resulting therapeutic treatment region is indicated by the dashed line labeled A4. Those skilled in the art will appreciate that this technique and its variations on multiple ablative and non-ablative segments can be used to protect various tissue structures in the body.

[0079] In other embodiments, treatment zones can be shaped using a single elongated section configured to simultaneously deliver fluids at multiple temperatures. This device has been described above, and examples of treatment zones are shown in FIGS. 7A and 7B. Another embodiment of this device is shown in FIGS. 8A and 8B. In use, either of these devices is introduced into a patient's body using a laparoscope or an endoscope and positioned adjacent to the tissue to be treated. Fluid can then be delivered to the tissue to be treated through one or more lumens of the device. The fluid flowing through each lumen can be independently heated to either a therapeutic temperature or a temperature below the therapeutic temperature. Fluids at different temperatures can be delivered from different locations on the device (through its length or around its circumference) to create treatment zones of different shapes.

[0080] In yet other embodiments, it may be desirable to shape the therapeutic treatment zone by introducing an elongated section configured to remove fluid from surrounding tissue rather than supplying fluid to the tissue. Utilizing an elongated section configured to withdraw fluid from surrounding tissue can help create a desired fluid flow pattern within the tissue volume being treated. In some embodiments, withdrawing fluid may also be necessary if the treatment volume cannot absorb and dissipate the amount of fluid introduced during an ablation treatment.

[0081] 10 illustrates one embodiment of a method for introducing fluid-assisted ablation using one elongated section for delivering heated fluid and one elongated section for removing fluid from a treatment volume. As shown in this figure, a first elongated section 1002 is inserted into a treatment volume 1004. However, unlike the previous embodiments in which the elongated section was located approximately in the center of the treatment volume, the elongated section 1002 is positioned so that the ablation section 1006 is located to one side of the treatment volume 1004. A second elongated section 1008 may then be inserted into the treatment volume at a location generally opposite the first elongated section 1002. The second elongated section 1008 may not include an ablation section, or if it does, the ablation section may be deactivated. Additionally, the second elongate portion 1008 may be configured to draw fluid from the surrounding tissue, for example, by connecting the lumen of the second elongate portion 1008 (which is in fluid communication with the surrounding tissue through one or more exit holes 1010) to a vacuum source.

[0082] After both the first and second elongated portions 1002, 1008 are positioned within the treatment volume 1004, the first elongated portion may begin to deliver therapeutic energy from the ablation portion 1006 and may also begin delivering fluid heated to therapeutic levels from one or more exit holes 1012 formed in the sidewall of the elongated portion 1002 or ablation portion 1006. The second elongated portion 1008 may also begin to activate and withdraw fluid from the tissue in the treatment volume 1004. The simultaneous delivery and withdrawal of fluid from the treatment volume creates a directional flow pattern between the first elongated portion 1002 and the second elongated portion 1008 (see arrows in the figure).

[0083] Those skilled in the art will appreciate that techniques for withdrawing fluid from a treatment region can be combined with any of the other techniques described herein to create a variety of complex therapeutic treatment zones with multiple geometries. Furthermore, multiple elongated sections configured to deliver ablation energy and withdraw fluid introduced into the treatment zone can be utilized simultaneously. Furthermore, the first and second elongated sections do not necessarily need to be positioned opposite each other, depending on the desired shape of the treatment region and the ability to access the site. Indeed, in some embodiments, fluid introduction and removal can be achieved using a single elongated section (e.g., device 800 shown in FIGS. 8A and 8B). In this embodiment, one section of the device can be configured to introduce fluid into the treatment volume, and another section of the device can be configured to remove fluid from the volume.

[0084] The method illustrated in FIG. 10 is particularly useful when treating, for example, covered lesions (e.g., uterine fibroids). Covered lesions have an outer shell that is impermeable to fluids (such as those introduced during fluid-assisted ablation). As a result, fluids are not drawn up during treatment, and the introduction of large amounts of incompressible fluid can undue pressure on the lesion. Additionally, the arrangement of the first and second elongated portions 1002 and 1008 as shown in the figure can impose a strong directionality (indicated by the arrows) on the propagation of heat delivered by the first elongated portion 1002. This allows completion of treatment to be determined by measuring the temperature of the tissue surrounding the second elongated portion 1008 using the same types of temperatures described above.

[0085] Various embodiments of the devices and systems disclosed herein can be utilized in a variety of surgical procedures to treat multiple conditions. For example, the medical devices disclosed herein can be configured for direct insertion into a target tissue volume during an open surgical procedure. Alternatively, the medical devices can be passed through one or more tissue layers during laparoscopic or other minimally invasive procedures. Additionally, the devices can be configured for introduction into one or more tissue layers of a patient or through a natural orifice (endoscopically). Following delivery to the treatment site, a portion of the surgical tool (e.g., a distal portion of the elongate portion 102) is inserted into the target treatment volume so that the ablation portion is located in the treatment volume. In some embodiments, the ablation portion can be located near the center of the treatment volume.

[0086] Once the devices are positioned within the treatment volume, fluid heated to a therapeutic temperature and ablation energy can be delivered to the treatment volume through one or more of the devices. In addition, one or more other devices can deliver cooler fluid or withdraw fluid from the treatment volume. The delivery of ablation energy and fluid can be stopped after a period of time or based on one or more feedback information (e.g., measurements from temperature sensors positioned within the treatment volume). The devices can then be removed and / or repositioned if further treatment is required.

[0087] Additionally, a large treatment zone having a first shape can be created by connecting several smaller treatment zones having a second shape. For example, a large linear treatment zone can be created by creating a slice-like shape (e.g., as shown in FIG. 5) and then repositioning the device to overlap the ends of subsequent treatment zones. A variety of other shapes can also be created using similar methods of connecting multiple smaller treatment zones of a certain shape and size.

[0088] <Sterilization and reuse> The devices disclosed herein may be designed to be disposed of after a single use, or may be designed for multiple uses. In either case, once the device has been used at least once, it can be refurbished for reuse. Refurbishment involves disassembly of the device followed by cleaning or replacement of multiple pieces, and subsequent reassembly. Specifically, the device can be disassembled and any number of pieces or parts of the device can be selectively replaced or removed in any combination. Once specific parts have been cleaned and / or replaced, the device can be reassembled at a refurbishment facility or by a surgical team immediately prior to a surgical procedure. Those skilled in the art will appreciate that refurbishment of devices can utilize a variety of techniques for disassembly, cleaning / replacement, and reassembly. The use of these techniques, and the resulting refurbished devices, are all within the scope of the present invention.

[0089] For example, the surgical devices disclosed herein may be partially or fully disassembled. Specifically, the elongate portion 202 of the medical device 200 shown in FIG. 2 may be detachable from the handle 204, or the entire handle and elongate portion assembly may be detachable from the electrical and fluid connections 206, 208. In yet another embodiment, the handle, elongate portion, and connections may be removably coupled to a housing containing the fluid reservoir, pump, and power source and controls, for example, as shown in FIG. 1.

[0090] Preferably, the devices described herein are processed prior to surgery. First, a new or used tool is obtained and, if necessary, cleaned. The tool is then sterilized. One sterilization technique involves placing the tool in a closed, sealed container (e.g., a plastic or TYVEK bag). The container and its contents are then placed in a radiation field (e.g., gamma radiation, x-rays, or high-energy electrons) that can penetrate the container. The radiation sterilizes the tool and the contents of the container. The sterilized tool may then be stored in a sterile container. The sealed container can keep the tool sterile until it is opened in the medical facility.

[0091] In many embodiments, it is preferred to sterilize the device. This can be accomplished by several methods known to those skilled in the art (e.g., beta or gamma radiation, ethylene oxide, water vapor, liquid soap, (e.g., cold soak)). In certain embodiments, the materials selected for forming members such as lengths may not withstand certain forms of sterilization (e.g., gamma radiation). In this case, a suitable alternative form of sterilization may be utilized (e.g., ethylene oxide).

[0092] Those skilled in the art will recognize additional features and advantages of the present invention based on the above-described embodiments. Accordingly, the present invention is not limited to what has been particularly shown and described, except as indicated by the claims. All publications and references cited herein are expressly incorporated herein by reference in their entirety. [Item 1] 1. A method of forming an ablation treatment volume in tissue having a desired shape, comprising: delivering therapeutic energy to the tissue to form an ablation treatment volume in the tissue; simultaneously delivering a first fluid and a second fluid to the tissue, the first fluid and the second fluid circulating the treatment energy in a desired direction so that the ablation treatment volume has a desired shape; A method comprising: [Item 2] Item 10. The method according to item 1, wherein the first fluid and the second fluid are supplied at different temperatures. [Item 3] Item 10. The method of claim 1, wherein the first fluid and the second fluid are supplied by one or more elongated members inserted into the tissue. [Item 4] Item 10. The method of item 1, further comprising adjusting any one of the flow rate and temperature of the first fluid and the second fluid to further shape the ablation treatment volume. [Item 5] 2. The method of claim 1, further comprising adjusting a level of treatment energy delivered to the tissue to shape the ablation treatment volume. [Item 6] The step of delivering therapeutic energy to the tissue comprises: Item 10. The method of item 1, comprising activating an ablation element configured to deliver electrical energy to the tissue. [Item 7] Item 10. The method of item 1, wherein the first fluid is supplied from first and second opposing longitudinal portions of a lumen of the elongate portion, and the second fluid is supplied from third and fourth opposing longitudinal portions of the lumen, the third and fourth portions being radially offset from the first and second portions. [Item 8] supplying the first fluid includes ejecting the first fluid through at least one exit hole formed in a proximal portion of a sidewall of the elongate member; Item 10. The method of item 1, wherein supplying the second fluid comprises releasing the second fluid from at least one exit hole formed in a distal portion of a sidewall of the elongate member adjacent the proximal portion. [Item 9] Item 14. The method of item 1, further comprising repeating the steps of delivering treatment energy and simultaneously delivering the first fluid and the second fluid to multiple locations to form a treatment volume having an elongated planar shape. [Item 10] 1. A method of shaping therapeutic energy delivered to tissue, comprising: positioning a first elongated portion at a first location within a patient, the first elongated portion having a lumen extending therethrough, the first elongated portion including at least one exit hole, at least one ablation portion disposed along its length, and at least one heating portion disposed within the lumen; positioning a second elongated portion at a second location within the patient, the second elongated portion having a lumen extending therethrough and including at least one exit hole; simultaneously supplying a first fluid from the first elongated portion and a second fluid from the second elongated portion, whereby the first fluid and the second fluid interact to shape an ablation treatment volume; A method comprising: [Item 11] Item 11. The method of item 10, wherein the first fluid and the second fluid are at different temperatures. [Item 12] Item 11. The method of item 10, further comprising delivering treatment energy from the at least one ablation portion disposed along the first elongate portion. [Item 13] Item 11. The method of item 10, wherein disposing the first elongated portion at a first position and the second elongated portion at a second position includes disposing an elongated member having the first elongated portion and the second elongated portion disposed therein within a patient's body. [Item 14] Item 11. The method of item 10, wherein the second elongate portion is positioned adjacent to a structure to be protected from the treatment energy. [Item 15] 1. An ablation device comprising: Equipped with a long section, The long portion is a proximal end and a distal end; a lumen extending within the elongate portion; at least two exit holes formed within the elongate portion for supplying fluid to tissue surrounding the elongate portion; at least one ablation region disposed along a distal portion of the elongate region, the at least one ablation region configured to heat tissue surrounding the at least one ablation region when the elongate region is inserted into tissue; and An ablation device wherein the at least two exit holes each supply fluid at a different temperature. [Item 16] Item 16. The ablation device of item 15, further comprising at least one heating section associated with one or more of the two exit holes, disposed within the lumen, and configured to heat fluid flowing through the associated one or more exit holes. [Item 17] and at least one dividing portion disposed within the lumen and dividing the lumen into two or more portions that are not in fluid communication with one another; Item 16. The ablation device of item 15, wherein each of the two or more portions communicates with one or more of the at least two exit holes. [Item 18] the at least one dividing portion divides the lumen into four portions extending longitudinally along the lumen, dividing the lumen into pairs of opposing quadrants; a heating section disposed within each of the first pair of opposing quadrants for heating a fluid flowing therethrough to a first temperature; Item 18. The ablation device of item 17, wherein a heating portion is provided within each portion of the second opposing pair of quadrants to heat fluid flowing therethrough to a second temperature lower than the first temperature. [Item 19] Item 18. The ablation device of item 17, wherein the at least one division portion divides the lumen into a proximal portion and a distal portion, each portion associated with a separate ablation portion. [Item 20] 20. The ablation device of claim 19, wherein the at least one dividing portion further divides the lumen to create a third portion proximal or distal to the distal portion. [Item 21] Item 18. The ablation device of item 17, comprising two or more temperature sensors, each temperature sensor being positioned in a different portion of the lumen. [Item 22] 1. An ablation device comprising: an elongate member having a distal portion adapted to be introduced into a patient's body; at least two elongate sections disposed on the distal portion of the elongate member; Equipped with each of the at least two elongated portions includes a proximal end and a distal end, a lumen extending therethrough, and at least one exit hole in the elongated portion for supplying fluid to tissue surrounding the elongated portion; at least one of the at least two elongate portions includes at least one ablation portion disposed along a distal portion of the elongate portion, the at least one ablation portion configured to heat tissue surrounding the at least one ablation portion; An ablation device, wherein at least one of the at least two elongated portions includes a heating portion disposed in an inner lumen of the elongated portion, the heating portion being configured to heat a fluid flowing within the inner lumen. [Item 23] Item 23. The ablation device of item 22, wherein the at least two elongate portions include first, second, and third elongate members disposed around the distal portion of the elongate member at a fixed distance from the longitudinal axis of the elongate member.

Claims

1. an elongate member having a distal end adapted to be introduced into a patient's body; at least two elongate sections disposed at the distal end of the elongate member; Equipped with Each of the at least two elongated portions is a proximal end and a distal end; a lumen extending therethrough; at least one exit hole in the elongate portion for supplying fluid to tissue surrounding the elongate portion; and at least one of the at least two elongated sections has at least one ablation section disposed along a distal portion of the elongated section; the ablation region heats tissue surrounding the ablation region; At least one of the at least two elongated portions has a heating portion disposed within the lumen of the elongated portion; The heating section heats a fluid flowing through the lumen.

1. An ablation device comprising: the ablation device is configured to simultaneously discharge energy from the ablation portion, supply a first fluid through the at least one exit hole of the first elongated portion, and supply a second fluid through the at least one exit hole of the second elongated portion; the ablation device is configured to deliver the first and second fluids at different temperatures; the first fluid is at a therapeutic temperature capable of causing irreversible damage to tissue; the second fluid is at a temperature below the therapeutic temperature to selectively quench tissue and limit tissue damage; Ablation devices.

2. the at least two elongate portions include the first elongate portion, the second elongate portion, and a third elongate portion disposed about the distal end of the elongate member and spaced apart from a longitudinal axis of the elongate member; The ablation device of claim 1 .

3. At least one of the liquid flow rate and the temperature of the first and second fluids is adjusted. The ablation device of claim 1 .

4. The amount of energy emitted from the ablation portion is adjusted. The ablation device of claim 1 .

5. the heating section heats the fluid to a therapeutic temperature capable of causing irreversible tissue damage; The ablation device of claim 1 .

6. The heating section heats the fluid to a temperature greater than 41°C. The ablation device of claim 1 .

7. The ablation portion delivers RF energy to surrounding tissue. The ablation device of claim 1 .

8. the ablation device supplies the first and second fluids to the first and second elongated portions via a plurality of fluid-exclusive flow paths; An ablation device according to any one of claims 1 to 7.

9. The ablation device comprises: supplying the first fluid to a first outlet hole provided in the first elongated portion; supplying the second fluid to second outlet holes provided in the second and third elongated portions, respectively; The ablation device of claim 2 .

10. the ablation device supplies the first and second fluids to the first and second exit holes, respectively, via a plurality of fluid-exclusive paths; The ablation device of claim 9 .

11. The at least two elongated portions are the first elongate portion centrally disposed at and extending from the distal end of the elongate member; the second elongate portion extending from the distal end of the elongate member and offset from the first elongate portion along an axis defining a diameter of the elongate member; a third elongate section extending from the distal end of the elongate member and offset from the first elongate section along the axis in a direction opposite to the offset of the second elongate section; Equipped with The first elongated portion said lumen extending therethrough; the at least one exit hole; the at least one ablation portion disposed along its length; The heating unit is disposed inside the lumen; and The second elongated portion is said lumen extending therethrough; the at least one exit hole; and The third elongated portion is said lumen extending therethrough; the at least one exit hole; and the ablation device is configured to simultaneously deliver the first fluid from the first elongated portion and the second fluid from the second and third elongated portions; The ablation device of claim 1 .

12. the ablation device delivers treatment energy from the ablation portion disposed along the first elongate portion. The ablation device of claim 11.

13. the heating section heats the first fluid to a therapeutic temperature capable of causing irreversible tissue damage; The ablation device of claim 11.

14. The heating unit heats the first fluid to a temperature greater than 41°C. The ablation device of claim 11.

15. the at least two elongated portions are positioned relative to the elongated member; The ablation device of claim 1 .

16. the at least two elongated portions are positioned relative to one another; The ablation device of claim 1 .

17. further comprising at least one temperature sensor disposed within the lumen of at least one of the at least two elongated portions. The ablation device of claim 1 .

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