Steam ablation system with simplified control of steam delivery

Abstract

Ablation systems and methods include improved methods of generating heated vapor. A vapor ablation system preferably has a controller having a user interface that receives data indicative of a treatment session time, a pump in data communication with the controller, and a catheter having an electrode and in fluid flow communication with the pump. The controller is configured to control the pump to provide fluid to a lumen of the catheter, to cause an electrical current to be delivered to the electrode to heat the fluid in the lumen and convert the fluid to heated vapor, to control the delivery of the fluid and generation of the heated vapor based on the data indicative of the time and without modifying a flow rate of the fluid or a voltage and / or current level of the electrical current based on data from a sensor located in or on the catheter.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Provisional Application No. 62 / 961473, filed January 15, 2020, entitled “Steam Ablation System with Improved Control of Steam Quality and Delivery,” which is incorporated herein by reference. Technical Field

[0003] This specification relates to systems and methods configured to simplify the generation and delivery of steam for ablation-based treatments. More specifically, this specification relates to systems and methods that use time as a single data input driving all subsequent operational variables to generate and deliver a continuous and reliable flow of ablation steam for focused and consistent tissue ablation. Background Technology

[0004] Ablation, as described in this specification, involves the removal, destruction, or modification (e.g., shrinkage, tightening, remodeling, denaturation, etc.) of body tissue by introducing a disruptive agent such as radiofrequency energy, laser energy, ultrasonic energy, a coolant, or vapor such as steam or evaporated saline solution. Ablation is commonly used to remove diseased or unwanted tissue, such as, but not limited to, cysts, polyps, tumors, hemorrhoids, and other similar lesions.

[0005] Steam-based ablation systems, such as those disclosed in U.S. Patent Nos. 9,615,875, 9,433,457, 9,376,497, 9,561,068, 9,561,067, and 9,561,066, disclose ablation systems that controllably deliver steam toward a tissue target through one or more luminal cavities, which are incorporated herein by reference. A problem with all such steam-based ablation systems is the complex interaction of multiple variables that, if not handled properly, can lead to inconsistent or unreliable steam delivery through the catheter port and / or potential overheating or burns to healthy tissue.

[0006] Furthermore, the effective use of steam typically requires the controlled exposure of a certain volume of tissue to the steam. However, existing steam ablation methods either fail to adequately seal the treated volume, thus failing to adequately expose the tissue, or over-seal the treated volume, thereby dangerously increasing pressure and / or temperature within the patient's organ. Pressure sensors located on the catheter can help regulate energy delivery, but they are not always reliable and represent a critical point for potential malfunctions in the system.

[0007] Furthermore, existing systems are often too expensive or complex because they require the use of one or more sensors in a disposable catheter to monitor the vapor quality, temperature, or pressure of the ablated body tissue or area. Including such sensors increases the cost and complexity of the ablation system and requires the user to monitor any changes in temperature and / or pressure.

[0008] Therefore, it is desirable to have a steam-based ablation device that integrates simple safety and / or steam control mechanisms into the device itself, resulting in reliable steam delivery and preventing unwanted combustion during use. It is also desirable to provide a way to better control the amount of steam exposed to the target tissue without relying on sensors located within the conduit. Furthermore, it is desirable to provide automatic control of steam quality without requiring feedback from sensors. Such a system could eliminate the need for sensors, such as those used to sense pressure, temperature, steam quality, humidity, or any other parameters to ensure proper heat transfer.

[0009] In the event of a technical malfunction and cessation of operation in a conventional steam-based ablation system, the steam stored in the catheter can potentially burn the patient. Therefore, there is also a need for a heat delivery system that delivers heat in a manner that avoids storing large amounts of heat that could potentially burn the patient.

[0010] Finally, current ablation systems have inflexible port structures, making it difficult to deliver steam directly from the catheter to tissue substantially parallel or inclined to the port without significant steam loss. Furthermore, ablation using circular coverage areas is challenging because gaps of untreated areas may remain after ablation at adjacent sites, or overlap may occur during ablation—both inefficient and potentially dangerous situations. Therefore, there is a need for focused and effective ablation that can be easily stacked without missing any target space. It is also desirable to provide steam-based ablation systems and methods for treating a variety of conditions, including precancerous or cancerous tissue in the esophagus, duodenum, bile duct, pancreas, or other tissues within the gastrointestinal system. Summary of the Invention

[0011] This specification discloses a steam ablation system comprising: a controller having user input configured to receive data indicating treatment duration; a pump communicating with the controller; and a conduit in fluid communication with the pump and having an elongated shaft, a proximal end, and a distal end, the conduit including: at least one lumen; and at least one electrode within the lumen, wherein the controller is configured to control the pump to supply fluid to the lumen of the conduit, wherein the controller is configured to deliver an electrical current to the at least one electrode to heat the fluid in the lumen and convert the fluid into heated steam, and wherein the controller is configured to control the delivery of fluid and the generation of heated steam by controlling the flow rate and power, voltage, and / or current levels of the fluid solely based on the data indicating treatment duration.

[0012] Optionally, the controller is also configured to control the delivery of fluid and the generation of heating steam by controlling the flow rate and power, voltage and / or current levels of the fluid without modifying the fluid flow rate or voltage and / or current levels based on data from sensors located in or above the conduit.

[0013] Optionally, the vapor ablation system further includes a cap in fluid communication with the distal end of the catheter, the cap being configured to guide ablative from at least one lumen into body tissue, wherein the cap is defined by an enclosed shell of a certain volume, and wherein a single opening in the shell is located on one side of the cap parallel to or at an angle of 5 degrees or greater relative to the longitudinal axis of the catheter. Optionally, the cap includes a rounded or curved outer edge or surface and is detachably attached to the distal end of the catheter. Optionally, the single opening has a polygonal coverage area. Optionally, the polygon includes one of a square, rectangle, pentagon, or hexagon. Optionally, this side of the cap forms an angle ranging from 5 degrees to 45 degrees relative to the longitudinal axis of the catheter.

[0014] Optionally, the controller is also configured to detect the actual start of heating steam generation by monitoring changes in output power, output voltage, or output current, which is independent and separate from the initiation of fluid flow to at least one electrode.

[0015] Optionally, the controller is also configured to automatically apply a predefined on / off duty cycle during the treatment period.

[0016] Alternatively, the fluid is salt water.

[0017] Optionally, the controller is configured to deliver power ranging from 5 watts to 300 watts to at least one electrode.

[0018] Optionally, the controller is configured to deliver fluid into the lumen at a flow rate of 2 ml / min.

[0019] Optionally, at least one electrode includes a bipolar electrode.

[0020] Optionally, the controller is configured to automatically apply a fixed power / flow relationship during the treatment period, which cannot be changed based on sensed data indicating the steam quality, temperature, humidity level, or pressure of the heating steam.

[0021] Optionally, the conduit does not include sensors configured to sense steam quality, temperature, humidity level, or pressure of the heating steam.

[0022] Optionally, the catheter includes a programmable element, and the controller is configured to program the programmable element based on at least one of treatment type, power level, voltage level, current level, fluid flow rate, or treatment time. Optionally, the programmable element is a resistor.

[0023] This specification also discloses a steam ablation system comprising: a controller having a user interface configured to receive data indicating treatment duration; an infusion pump communicating with the controller; and a catheter in fluid communication with the infusion pump and having an elongated shaft, a proximal end, and a distal end, the catheter comprising: at least one lumen; and at least one electrode within the lumen, wherein the controller is configured to control the pump to supply fluid to the lumen of the catheter, wherein the controller is configured to deliver an electrical current to the at least one electrode to heat the fluid in the lumen and convert the fluid into heated steam, and wherein the controller is configured to control the fluid flow rate and the electrical current based on the data indicating the time. The controller controls the delivery of fluid and the generation of heating steam by controlling the power, voltage, and / or current level of the current, and wherein the controller is further configured to control the delivery of fluid and the generation of heating steam without modifying the flow rate of the fluid or the voltage and / or current level of the electrical current based on data from sensors located in or above the catheter; and a cap in fluid communication with the distal end of the catheter, the cap being configured to guide the ablative from at least one lumen to body tissue, wherein the cap is defined by a shell that encloses a certain volume, and wherein the only opening in the shell is located on the side of the cap that is parallel to or at an angle of 5 degrees or greater relative to the longitudinal axis of the catheter.

[0024] Optionally, the controller is configured to use data to determine the duration for at least one electrode to receive current to heat the fluid in the chamber and convert the fluid into heated steam.

[0025] Alternatively, the steam ablation system is adapted to operate at a constant fluid flow rate from the pump to the conduit lumen.

[0026] Optionally, the controller is configured to maintain the power delivered to at least one electrode in a stable state by keeping the voltage level and impedance in a stable state.

[0027] Optionally, the controller is configured to maintain the impedance in a steady state by keeping the fluid flow rate and salinity in a steady state.

[0028] This specification also discloses a steam ablation system comprising: a controller; a pump communicating with the controller; a catheter in fluid communication with the pump and electrically connected to the controller, having an elongated shaft, a proximal end, and a distal end; the catheter comprising: at least one lumen; at least one electrode within the lumen, wherein the pump is configured to supply fluid to the lumen of the catheter, wherein the at least one electrode is configured to receive an electrical current from the controller to heat the fluid in the lumen and convert the fluid into heated steam, and wherein the controller is configured to control the quality of the heated steam by controlling the voltage and / or current level of a time-based input control current, and independent of any temperature, pressure, humidity, or steam quality sensors located on or within the catheter inserted into the patient; and optionally, a cap in fluid communication with the distal end of the catheter, the cap being configured to guide an ablation agent from at least one lumen to body tissue.

[0029] Alternatively, the fluid is a physiologically compatible fluid containing free ions, such as, but not limited to, NaCl and Ca.

[0030] Alternatively, the fluid may be an aqueous solution of sodium chloride, such as brine.

[0031] Alternatively, the fluid may be physiological saline.

[0032] Optionally, the controller is configured to deliver power ranging from 1 watt to 300 watts to at least one electrode.

[0033] Optionally, the controller is configured to deliver fluid flow to the lumen of the catheter in the range of 0.1-25 ml / min.

[0034] Optionally, at least one electrode includes a bipolar electrode.

[0035] Optionally, the fluid is brine, and the brine has a sodium chloride concentration of 0.01% to 10%.

[0036] Optionally, the cap may include a rounded or curved outer edge or surface.

[0037] Optionally, the cap includes a polygonal exit coverage area. The polygon may include one of the following geometric shapes: square, rectangular, pentagonal, hexagonal, or otherwise.

[0038] The above and other embodiments of the present invention will be described in more detail in the accompanying drawings and detailed description provided below. Attached Figure Description

[0039] These and other features and advantages of the invention will be better understood when considered in conjunction with the accompanying drawings and with reference to the detailed description, in which:

[0040] Figure 1A An ablation system according to an embodiment of this specification is shown;

[0041] Figure 1B An ablation catheter according to an embodiment of this specification is shown;

[0042] Figure 2A An ablation catheter for annular ablation is shown according to some embodiments of this specification;

[0043] Figure 2B A graph showing inconsistent temperature increases measured at the steam delivery port of the annular ablation catheter is presented.

[0044] Figure 2C A graph showing a consistent temperature increase measured at the steam delivery port of the annular ablation catheter is shown.

[0045] Figure 3A An ablation catheter including a distal cap or focused ablation is shown according to an embodiment of this specification;

[0046] Figure 3B An ablation catheter including a distal cap for focused ablation is shown according to other embodiments of this specification;

[0047] Figure 3C A cross-sectional side view of a distal cap attached to the distal end of an ablation catheter according to an embodiment of this specification is shown.

[0048] Figure 3D A front view of the polygonal outlet of the distal cap according to an embodiment of this specification is shown;

[0049] Figure 3E A front view of the polygonal outlet of the distal cap according to another embodiment of this specification is shown;

[0050] Figure 3F A front view of a polygonal outlet of a distal cap attached to the distal end of an ablation catheter, according to an embodiment of this specification, is shown.

[0051] Figure 3G A side view of a polygonal outlet of a distal cap attached to the distal end of an ablation catheter, according to an embodiment of this specification, is shown.

[0052] Figure 4 This is a flowchart illustrating the steps of a method using an ablation system with a distal cap on an ablation catheter, according to some embodiments of this specification;

[0053] Figure 5 This is a flowchart illustrating an exemplary process for controlling steam generation in an ablation apparatus according to some embodiments of this specification;

[0054] Figure 6 An exemplary controller interface is shown;

[0055] Figure 7A Exemplary twisted-pair or braided electrodes according to some embodiments of this specification are shown; and

[0056] Figure 7B Exemplary stranded multiwire or braided electrodes according to some embodiments of this specification are shown. Detailed Implementation

[0057] The embodiments of this specification provide systems and methods for ablation therapy to treat a variety of conditions. The embodiments of this specification describe ablation systems and methods that achieve a high degree of safety without requiring sensors embedded in the catheter to monitor parameters such as temperature, humidity, pressure, and vapor quality, and minimize the chance of burns or injury to the patient.

[0058] Embodiments of the present invention are intended for deployment in known ablation systems. Exemplary known ablation systems include a controller and a catheter, the controller having a pump (e.g., an injection pump) attached thereto, the catheter including an elongated shaft having a proximal end, a distal end, and at least one lumen therein, the elongated shaft being attached to the controller via a conduit and in fluid communication with the pump. The catheter and / or conduit are disposable and together form a disposable kit. The catheter includes at least one electrode located within the catheter lumen to provide an energy source and convert fluid (e.g., saline) within the lumen into vapor (e.g., steam). At least one electrode is located at or near the distal end or tip of the catheter. The electrode is positioned near an output port on the catheter such that any vapor generated travels only a short distance (e.g., a few centimeters) before leaving the catheter. The catheter is also electrically connected to the controller for supplying power to the catheter in the form of an electrical current flowing to the at least one electrode. The catheter includes a first electrical connection port, the controller includes a second electrical connection port, and at least one wire connects the first electrical connection port to the second electrical connection port.

[0059] "Treatment" and its variations refer to any reduction in the degree, frequency, or severity of one or more symptoms or signs associated with a condition.

[0060] "Duration" and its variations refer to the prescribed time period from the start to the end of treatment, regardless of whether treatment ends due to remission or is discontinued for any other reason. Multiple treatment cycles can be prescribed during the treatment period, during which the subject is given one or more prescribed stimuli.

[0061] A “cycle” refers to the duration of a “dose” of stimulation administered to a subject as part of a prescribed treatment plan.

[0062] The term "and / or" refers to one or all of the listed elements or any combination of two or more listed elements.

[0063] In the specification and claims of this application, each of the words “comprising,” “including,” and “having,” and their forms, is not necessarily limited to members of the list that the word may be associated with. The term “comprising” and its variations are not intended to be limiting when they appear in the specification and claims.

[0064] Unless otherwise stated, “a,” “one,” “the,” “one or more,” and “at least one” are used interchangeably to mean one or more.

[0065] The term "controller" refers to an integrated hardware and software system defined by multiple processing elements (such as integrated circuits, microcontrollers, microprocessors, application-specific integrated circuits, and / or field-programmable gate arrays) that communicates data with memory elements (such as random access memory or read-only memory), wherein one or more processing elements are configured to execute program instructions stored in one or more memory elements.

[0066] The term "steam generating system" refers to any or all methods described in this application for generating steam from water.

[0067] The terms “steam,” “water vapor,” “fluid vapor,” and “vapor” are used interchangeably to refer to the gaseous phase of the fluid used for ablation according to various embodiments of this specification.

[0068] The term "steam mass" or "vapor mass" refers to the ratio of steam mass to liquid mass, expressed as a percentage of the total steam mass.

[0069] The terms “flow rate” or “volume flow rate” are used interchangeably and refer to the volume of fluid passing through the conduit embodiments described in this specification.

[0070] For any method disclosed herein that includes discrete steps, these steps can be performed in any feasible order. And, if appropriate, any combination of two or more steps can be performed simultaneously.

[0071] Furthermore, numerical ranges described herein by way of endpoints include all values ​​contained within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.). Unless otherwise stated, all figures used in the specification and claims to indicate the quantity of components, molecular weight, etc., should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise indicated, the numerical parameters listed in the specification and claims are approximate values ​​that may vary depending on the desired properties sought to be obtained in this specification. At least, and without attempting to limit the doctrine of equivalence to the scope of the claims, each numerical parameter should be interpreted at least according to the number of significant figures reported and by applying ordinary rounding techniques.

[0072] Although the numerical ranges and parameters described in this specification are approximate, the values ​​presented in the specific examples are reported as precisely as possible. However, all values ​​inherently include a range, which necessarily derives from the standard deviation found in their respective test measurements.

[0073] It should be understood that the devices and embodiments described herein are implemented in conjunction with a controller, which includes a microprocessor that executes control instructions. The controller can take the form of any computing device, including desktop computers, laptops and mobile devices, custom consoles, and can transmit control signals to the ablation device in a wired or wireless manner.

[0074] This invention relates to several embodiments. The following disclosure is provided to enable those skilled in the art to practice the invention. The language used in this specification should not be construed as a general denial of any particular embodiment, nor should it be used to limit the claims to meanings other than those of the terms used herein. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Furthermore, the terminology and wording used are for the purpose of describing exemplary embodiments and should not be considered restrictive. Therefore, the invention is to be accorded the widest scope, including many substitutions, modifications, and equivalents consistent with the disclosed principles and features. For clarity, details related to technical materials known in the art related to this invention have not been described in detail so as not to unnecessarily obscure the invention.

[0075] It should be noted here that, unless explicitly stated otherwise, any feature or component described in connection with a particular embodiment may be used and implemented with any other embodiment.

[0076] Figure 1A An ablation system 100 according to an embodiment of this specification is shown. Figure 1B It shows the use of Figure 1A The ablation system 100 includes the catheter 110. (See also...) Figure 1A and 1BThe ablation system 100 includes a controller 150, a pump 140 attached to the controller 150, and a catheter 110. The catheter 110 includes an elongated shaft 111 having a proximal end 112, a distal end 113, and at least one lumen 114 therein. The catheter 110 is attached to the controller 150 via a conduit 120 and is in fluid communication with the pump 140. The controller 150 includes a microprocessor 155 for controlling the flow rate of the ablation agent. In some embodiments, the system 100 includes an input device 125 that communicates data with the controller 150 and is configured to allow a user to adjust the treatment duration. In some embodiments, the input device includes a foot pedal and / or a graphical user interface (GUI). In some embodiments, a switch 127 on the catheter 110 or a switch 157 on the controller 150 is provided and configured to allow a user to control the flow of the ablation agent.

[0077] In one embodiment, the GUI is configured to allow users to define devices, organs, and conditions, which in turn creates default settings for key variables such as temperature, circulation, volume, volumetric flow rate, power, time, and standard energy or radio frequency (RF) settings, such as RF voltage, RF current, RF power, and RF impedance. In one embodiment, the user can further modify these default values. The user interface also includes a standard display of all key variables, as well as warnings when values ​​exceed or fall below certain levels. In one embodiment, system 100 also includes safety mechanisms to prevent user burns while operating the catheter, including markings on the catheter shaft indicating areas of heat or steam generation, insulation, and optional cold air flushing, cold water flushing, and alarms / audible signals indicating the start and stop of treatment.

[0078] Reference Figure 6 In one embodiment, the controller includes a graphical user interface 600 that displays only input 610, configured to receive a selected treatment period 605 based on the ablated tissue and / or the treatment provided. In one embodiment, the input of the time, which can be determined based on the ablated tissue and / or the treatment provided, automatically and necessarily determines all further operational variables, including flow rate, voltage level, and / or power level, as further described below.

[0079] In some embodiments, pump 140 is an injection pump. In various embodiments, heated steam generated by heating a conductive solution, such as brine, supplied by pump 140 within a conduit is used as an ablative. Brine is more suitable than water as the fluid for generating heated steam because brine is a conductive fluid, while water is not. A salt solution with specific conductivity and resistivity is required because the solution needs resistivity to heat up and evaporate, while excessively high conductivity will prevent heating. Furthermore, the surface area of ​​the electrodes is defined to optimize the amount of steam generated within a specific time period. A larger electrode surface area increases the amount of power that can be delivered, resulting in a greater amount of steam being generated with electrodes of relatively smaller surface areas within a similar time period. In embodiments, brine with a sodium chloride concentration in the range of 0.01% to 10% is used to optimize conductivity. In one embodiment, brine with a sodium chloride concentration of 0.9% is used.

[0080] The conduit 110 includes at least one electrode 118 located within a lumen 114 of the conduit 110 to deliver energy to generate heat and convert fluid within the lumen 114 into steam. Energy in the form of an electric current (i) delivered by the at least one electrode 118 heats the fluid via resistance heating (R), which converts the fluid into steam. In an embodiment, the generated heat can be represented by the following equation:

[0081] i 2 *R

[0082] Where i = current (amperes) and R = fluid resistance (ohms).

[0083] At least one electrode 118 is located at or near the distal end 113 or distal tip of the conduit 110. The at least one electrode 118 is positioned near at least one output port 116 on the conduit 110 such that any vapor generated travels only a short distance before leaving the conduit 110. The conduit 110 is also electrically connected to a controller 150 for supplying power to the conduit 110 in the form of an electrical current to the at least one electrode 118. In an embodiment, the conduit 110 includes a first electrical connection port 119, the controller 150 includes a second electrical connection port 159, and a metal wire 129 connects the first electrical connection port 119 to the second electrical connection port 159. In some embodiments, the at least one electrode 118 includes at least a pair of electrodes 118a, 118b, or includes at least one elongated bipolar electrode. In some embodiments, multiple independently controlled channels exist for the bipolar electrode pair. In an embodiment, the electrodes in the at least one pair of electrodes 118a, 118b are cylindrical and spaced apart from each other. The electrical current supplied to at least one electrode 118 causes heat to be generated, heating a fluid, such as brine, flowing within the lumen 114 and converting the fluid into heated steam. In some embodiments, multiple electrodes are positioned in series along the length of the conduit lumen 114. In some embodiments, multiple electrodes are placed concentrically. In one embodiment, and as... Figure 1A and 1B As shown, electrode 118 has conductors on the top and bottom sides, and fluid flows through both sides of the flat electrode assembly.

[0084] In one embodiment, reference Figure 7A and 7B Electrodes 700a and 700b each comprise a single twisted pair or braid (comprising two helically twisted or interlaced segments 715a) or multiple twisted pairs or braids (comprising more than two helically twisted or interlaced segments 715b, preferably 3, 4, 5, 6, or more interlaced segments). Each segment in the twisted pair or braid 715a and 715b comprises a conductive material covered by an insulating material, resulting in twisted pairs or braids 715a and 715b with individually insulated segments interlaced helically. At selected locations along the length of the individual segments, the insulation is removed, exposing the underlying conductive material 710a and 710b. The exposed portions 710a and 710b of the individual segments of the twisted pairs or braids 715a and 715b are aligned such that, when evaluated along the longitudinal length of the electrode, the exposed portions of each individual segment may not overlap, or may overlap within a range of 1% to 100% (or any increment therein).

[0085] In some embodiments, the electrode configuration is defined by their respective surface areas and / or peripheral edges. In some embodiments, a vaporization electric field is generated by using a range of 1 to 25 bipolar electrode pairs, thereby providing a range of 4 to 100 edges, wherein four edges comprise bipolar pairs. In some embodiments, the power supplied to at least one electrode is in the range of 2 watts to 300 watts. In some embodiments, a saline flow is supplied to the catheter in the range of 0.1 to 10 ml / min. In one embodiment, the ablation system operates at a saline flow rate of 2 ml / min and a power level of 50 watts.

[0086] The ablation system described in this specification uses a power / flow rate relationship to control the amount and / or quality of steam, without further relying on sensing data from the conduit, particularly temperature, pressure, humidity, steam quality, or steam mass data. More preferably, as described above, the power / flow rate and time are automatically triggered or set based on the desired ablation effect. Specifically, by positioning at least one electrode 118 near at least one output port 116 on the conduit 110, the amount of steam is tightly controlled because the steam is output almost immediately after generation, and the steam quality can be controlled. Furthermore, since the electrode 118 is located near the output port 116, a shorter section of the conduit near the port 116 is heated. Moreover, the less heat loss, the better the steam quality. High steam quality is defined as steam with a high amount of steam relative to the amount of condensate. In one embodiment, the heating steam has a quality level of at least 0.10, preferably higher than 0.50, as a measure of the proportion of saturated steam in the saturated condensate mixture. The high steam quality can be maintained by controlling the amount of power in the form of electrical current supplied to at least one electrode 118, and by controlling the fluid flow rate from the pump 140 to the conduit 110. As the inventors uniquely determined, following a specific relationship between flow rate and supplied power ensures the generation of high-quality steam without requiring further control or modification via data input or received from one or more sensors positioned on or within the catheter. This eliminates the need for any sensors, such as temperature, pressure, humidity, or fluid flow sensors, positioned within, embedded in, or along the length of the catheter to monitor steam quality and ensure it is sufficient for ablation without exceeding limits that could lead to injury or undertreatment. Steam quality is controlled by fine-tuning two variables: the range of voltage or current supplied to at least one electrode and the range of saline flow rate. For example, a voltage setting of 35 volts and a flow rate of 2.2 ml / min can produce approximately 40%–60% steam quality. In the most preferred embodiment, the supplied voltage range (based solely on the desired tissue effect input) is 25 volts (V) to 35 V, the supplied current range (based solely on the desired tissue effect input) is 1 ampere (A) to 5 A, the supplied power range (based solely on the desired tissue effect input) is 40 watts (W) to 60 W, and the supplied flow rate range (based solely on the desired tissue effect input) is 1.8 ml / min to 2.5 ml / min. In a preferred embodiment, the supplied voltage range (based solely on the desired time tissue effect input) is 10 volts (V) to 55 V, the supplied current range (based solely on the desired time tissue effect input) is 0.5 amperes (A) to 10 A, the supplied power range (based solely on the desired time tissue effect input) is 20 watts (W) to 100 W, and the supplied flow rate range (based solely on the desired time tissue effect input) is 0.9 ml / min to 4.0 ml / min.

[0087] Heating steam is generated and delivered almost immediately upon generation, a process known as "timely steam generation and delivery," ensuring a rapid and continuous flow of steam. This results in very little heat being stored within the conduit or controller, making it a safer system. In various embodiments, the ablation system stores less than 500 J of heat, preferably less than 100 J, defined by the amount of steam or water equal to or less than 0.5 ml of brine and preferably less than 0.1 ml of brine. Therefore, embodiments of this specification provide a safety mechanism in the event of system malfunction or failure, as there is no steam to discard. Consequently, various embodiments prevent or significantly reduce the risk of damage due to burns caused by stored heat.

[0088] In some embodiments, the patient is treated in a two-step process to ensure complete or near-complete ablation of the target tissue. In some embodiments, the patient is first treated with a catheter having two positioning elements—an initially deployed distal positioning element, followed by a subsequently deployed proximal positioning element, and a tube length having a port located between the two positioning elements, thereby enabling large-area circumferential ablation.

[0089] Figure 2A An ablation catheter 200 for annular ablation is illustrated according to some embodiments of this specification. The ablation catheter 210 includes an elongated shaft 211, a proximal end 212, a distal end 213, and at least one lumen 214. A proximal positioning element 201 is positioned proximal to the distal end 213, and a distal positioning element 203 is positioned distal to the proximal positioning element 201. A plurality of ports 216 are located on the catheter shaft 211 between the proximal and distal positioning elements 201 and 203. At least one electrode 218 is located in at least one lumen 214 for converting fluid into vapor. A first contact (but preferably without a seal or meaningful vapor barrier) is created through contact between the periphery of the positioning elements 201, 203 and the patient tissue at the distal and proximal positioning elements 201, 203. Less preferably, a seal may be formed. Then, ablation energy in the form of vapor is delivered from catheter 210 via port 216 into a first treatment volume, in which the ablation energy contacts the patient’s tissue and condenses for circumferential ablation, and because the ablation energy is blocked (less preferred) by positioning elements 201, 203, the ablation energy cannot escape from the distal or proximal end, or preferably, based on the construction of positioning elements 201, 203 or the presence of orifices or channels 209 in positioning elements 201, 203, the ablation energy escapes from the distal or proximal end.

[0090] The port 216 extending between the two positioning elements is configured such that the surrounding chamber receives an equal distribution of vapor. In embodiments, the size, shape, orientation / angle, and position of the port can vary based on location to help optimize the equal distribution of vapor. For example, the rate of temperature rise measured at different points on the lining of the patient's gastrointestinal (GI) tract is substantially equal at all points. This prevents some surfaces from receiving too much heat while others receive too little, thereby ensuring equal ablation.

[0091] Figure 2B Graph 222 shows inconsistent temperature increases measured at the vapor delivery port of a conventional ablation catheter. The x-axis 222a represents time, and the y-axis 222b represents temperature (°C). Some points depicted by curves 223 and 224 lag behind others depicted by a roughly similar distribution in curve 226 in terms of temperature increase. In reality, these points do not receive sufficient energy. Figure 2C Graph 228 is shown, illustrating a consistent temperature increase measured at the vapor delivery port of the annular ablation conduit according to an embodiment of this specification. The x-axis 228a represents time, and the y-axis 228b represents temperature (°C). The points depicted by the generally similar distribution of curve 229 show a relatively consistent growth rate across all points, implying consistent energy deposition across all surfaces.

[0092] In one embodiment, the annular ablation catheter 210 of this specification is configured to establish a point array defined by a specific distance from a portion of the catheter axis 211, such that each point will experience a temperature rise at approximately the same rate. In other embodiments, the annular ablation catheter 210 of this specification is configured to establish a point array defined by a specific distance from a portion of the catheter axis 211, such that each point on the tissue to be ablated will experience the same temperature, from 60°C to 90°C to the same depth, from 0.5 mm to 5 mm within 5 seconds of each other.

[0093] In an embodiment, the port 216 of the annular ablation catheter 210 of this specification is configured such that the ratio of the surface area of ​​the port 216 opening to the surface area of ​​the length of the catheter 210 between the two positioning elements 201, 203 is less than 0.25, and preferably less than 0.10. The catheter 210 is configured to have a large number of holes, from 16 to 100, but not exceeding a percentage of the surface area of ​​the catheter shaft 211. In an embodiment, the diameter of each port 216 ranges from 0.05 mm to 2 mm.

[0094] In some embodiments, the loop catheter 210 includes one or more features to prevent water pooling in the patient's organ (GI tract). "Pooling" occurs when hot water (not just steam) drips from the port and accumulates in areas of tissue that may not be ablated. Because the loop ablation catheter is essentially horizontal during use, and because the patient is supine, a pool of hot water may form below the catheter and in the adjacent surfaces or bottom of the GI tract. The configuration of the catheter 210 provides for monitoring of pooling formation. In one embodiment, the outer surface of the catheter is connected to a second electrical connection port of the controller (… Figure 1A 159) is electrically connected to create a heated surface. The configuration of the two electrical ports ensures that the steam exiting port 216 remains in a steam state. Furthermore, in some embodiments, port 216 is a slit rather than a circular port. The slit is created using laser cutting. In some embodiments, the slit increases the flexibility of the length between positioning elements 201 and 203. In another embodiment, ports 216 are concentrated at locations where convergence is expected. For example, in one embodiment, more ports 216 are positioned toward the distal end 213 of the conduit. In a less preferred embodiment, the steam at the distal end 213 of the conduit is pressurized by using a flared nozzle at port 206 to reduce the size of the conduit lumen 214 or by superheating the steam as it exits the conduit 210. In yet another embodiment, the ports are covered with a semi-permeable or hydrophobic material that allows gas to pass through but not liquid. In some embodiments, the material is polytetrafluoroethylene (PTFE). In various embodiments, any one or a combination of the above mechanisms are used to avoid all forms of convergence. In some embodiments, the brine delivery conduit and the entire fluid path are constructed of a non-expanding (i.e., pressure-rated) material to ensure the path is completely free of air. The absence of air in the system or piping helps prevent the system / pipeline from expanding under pressure during steam transport. This, in turn, prevents fluid from dripping and pooling from the conduit when the expanded pipe resumes operation after steam transport has stopped.

[0095] After the circumferential ablation in the first step, the ablation area is examined by the physician. While observing the patient, the physician can identify tissue blocks that require focused ablation. In embodiments, circular or polygonal ablation coverage areas can be created, but polygonal ablation coverage areas are used to make focused ablation more effective than circular ablation coverage areas. Circular coverage areas may result in gaps or overlaps when ablating adjacent areas, which can be inefficient. In embodiments of this specification, polygonal ablation coverage areas are used, which are easy to stack and less likely to leave gaps. After the physician examines the circumferential ablation area, a second step is performed to provide focused ablation. During focused ablation, a second catheter with a needle or cap, shield, or disc accessory is passed through the endoscope and used for focused ablation. In embodiments, the cap has a circular or polygonal exit surface area. The polygonal exit surface area can be square, pentagonal, hexagonal, or any other type of polygon.

[0096] Figure 3A and 3B Ablation catheters 310 and 360 according to embodiments of this specification are shown, including distal caps 326 and 366 for focused ablation. In some embodiments, caps 326 and 366 are made of a foldable, expandable material that can be inserted through an endoscope. In some embodiments, caps 326 and 366 may be separate components attached to an endoscope or other surgical instrument. Similar to Figure 1B Catheter 110, Figure 3A and 3B The ablation catheters 310, 360 include an elongated shaft 311 having a proximal end 312 and a distal end 313, at least one internal cavity 314 having at least one electrode 318 internally, and a switch 327 for controlling vapor flow. The catheters 310, 360 are in fluid communication with a pump via a conduit 320 and are electrically connected to a controller via a wire 329 connected to an electrical connection port 319 at the proximal end 312. In some embodiments, the catheters 310, 360 and the conduit 320 together form a disposable kit 322. Distal caps 326, 366 are attached to the distal end 313 of the catheters 310, 360. The distal caps 326, 366 include circular or polygonal outlet ports 328, 368 for focused vapor delivery. Figure 3A and 3B In the illustrated embodiment, the outlet ports 328 and 368 are rectangular or square.

[0097] Reference Figure 3A Exit 328 is located at the far end of the far cap 328. (Refer to...) Figure 3B The outlet 368 is located on one side of the distal cap 366. It should be understood that the cap comprises a shell that completely encloses a certain volume except for a window, which is a gap or opening in the shell, located on one side of the cap such that it is parallel to the longitudinal axis of the catheter. The outer edges or outer surfaces 327, 367 of the distal caps 326, 366 are rounded or curved to provide a damage-resistant tip and prevent injury, avoiding edges that are too sharp to potentially cut into the patient's anatomical structures, such as the gastrointestinal tract (GI). In embodiments, the distal caps 326, 366 are closed except for the outlets 328, 368, which define an ablation coverage area for capturing and concentrating vapor. The coverage areas of the outlets 328, 368 are shaped in a circular or polygonal form to allow for easy stacking without overlap.

[0098] Figure 3C An attachment according to an embodiment of this specification is shown. Figure 3BA cross-sectional side view of the distal cap 366 of the distal end 313 of the ablation catheter 360. A portion of the distal cap 366 slides over and covers the distal portion of the catheter shaft 311. The distal cap 366 includes a connector 369 having an inner lumen 364 configured to be inserted into the outlet port 316 of the catheter. The distal cap 366 includes a circular or polygonal side outlet port 368. Vapor 335 is guided from the lumen 314 of the catheter 360, through the outlet 316 and the lumen 364 of the connector 369, and flows out from the side outlet port 368 for focused ablation. The location of at least one electrode 318 near the distal end 313 of the catheter 360 ensures that the vapor has a very short travel distance after generation to reach the target tissue. The outer edge or surface 367 of the distal cap 366 is rounded or curved to provide a damage-resistant tip and prevent injury.

[0099] Figure 3D A front view of the polygonal outlet 372 of the distal cap 371 according to an embodiment of this specification is shown. The polygonal outlet 372 is square, and the distal cap 371 includes a rounded or curved outer edge or surface 377 to provide a damage-resistant tip and prevent injury. Figure 3E A front view of the polygonal outlet 374 of the distal cap 373 according to another embodiment of this specification is shown. The polygonal outlet 374 is hexagonal, and the distal cap 373 includes a rounded or curved outer edge or surface 379 to provide a damage-resistant tip and prevent injury.

[0100] Figure 3F A front view of a polygonal outlet 382 of a distal cap 381 attached to the distal end 313 of an ablation catheter 360 according to an embodiment of this specification is shown. The polygonal outlet 382 is square, and the distal cap 381 includes a rounded or curved outer edge or surface 387 to provide a damage-resistant tip and prevent injury. Vapor flows from the lumen of the catheter 360 through the outlet port 316 of the catheter 360, through the distal cap 381, and out of the round or polygonal outlet 382. Figure 3G A side view of a polygonal outlet 392 of a distal cap 391 attached to the distal end 313 of an ablation catheter 360 according to an embodiment of this specification is shown. The polygonal outlet 392 is rectangular, and the distal cap 391 includes a rounded or curved outer edge or surface 397 to provide a damage-resistant tip and prevent injury. Vapor flows from the lumen of the catheter 360 through the outlet 316 of the catheter 360, through the distal cap 391, and out of the rounded or polygonal outlet 392.

[0101] Reference Figure 3GThe distal cap is tilted or offset to one side such that it forms an angle of at least 1 degree relative to the longitudinal axis of the catheter, preferably at least 5 degrees but less than 90 degrees, more preferably at least 10 degrees, and more preferably in the range of 5 to 45 degrees, thereby allowing even more focused ablation of the target tissue. In some embodiments, the catheter 360 includes a mechanism 399 for tilting the distal cap 391 at a larger or smaller angle and for changing the direction of tilt. The tilted distal cap 391 with a polygonal outlet 392 makes positioning of the catheter 360 easier because the physician does not have to figure out how to bend or move the outlet surface to hit the desired target surface (assuming that the outlet points downward and parallel to the GI channel when first inserted). The physician only needs to gently push the polygonal outlet 392 against the GI channel for proper positioning. In some embodiments, the polygonal outlet 392 has a 0.5 cm... 2 up to 5cm 2 Surface area within the range.

[0102] Figure 3A-3G The distal cap shown is configured to attach to the distal end or tip of the catheter. In some embodiments, the distal cap includes a groove and / or O-ring that attaches or snaps into the distal tip of the catheter. In some embodiments, the distal cap further includes an additional channel that guides vapor from the catheter lumen into the cap and toward the distal cap outlet port. In some embodiments, the catheter lumen is positioned off-center from the catheter axis, and the distal cap further includes a connecting member configured to insert into the catheter lumen and guide vapor to the distal cap outlet port. In some embodiments, the distal cap channel has a length within a predetermined range and a maximum thickness within a predetermined range to fit and remain within the catheter lumen.

[0103] Figure 4 This is a flowchart illustrating the steps of a method using an ablation system with a distal cap on an ablation catheter, according to some embodiments of this specification. In step 402, the physician places a circular or polygonal outlet surface onto the target tissue, such as a portion of the patient's GI tract. In step 404, the physician presses a button (e.g., Figure 3B The ablation system pulses a standard amount of steam via a switch 327 or foot pedal (e.g., input device 125). In step 406, the ablation system pulses steam for a predetermined time period ranging from 0.01 to 10 seconds. In step 408, the physician moves the circular or polygonal outlet surface to the next position. The physician then continues with step 402 until all focal ablation is complete. In this embodiment, the ablation system is configured to output a standard amount of steam for a predetermined time period of 0.01 to 10 seconds whenever the physician presses a button (e.g., foot pedal). The steam pulse continues until either 1) the predetermined time period (0.01-10 seconds) ends or 2) the physician stops pressing the button (lifts their foot off the foot pedal).

[0104] The cap provides directional focal ablation and closes the focal ablation area, optionally (but not preferably) creating a sealed and enclosed treatment volume for tissue ablation. Preferably, contact between the cap and the tissue area directs vapor to the treatment area, such that a portion of the patient tissue lies within the area defined by the attachment, but without sealing the cap onto the surface of the patient tissue, such as the esophagus or duodenum. In embodiments of this specification, the outer surface 367 of the circular or polygonal cap has a damage-resistant shape. In one embodiment, the outer periphery 367 of the circular or polygonal cap is rounded or curved to avoid sharp surfaces that could potentially damage the patient's GI tract.

[0105] In one embodiment, the flow rate of steam exiting the closed or partially closed volume is a predetermined percentage of the flow rate of steam entering the closed or partially closed volume from the catheter port, wherein the predetermined percentage is in the range of 1% to 80%, preferably less than 50%, more preferably less than 30%. At least one port is located at the distal end of the catheter such that the port enters the treatment volume when the accessory is positioned.

[0106] The apparatus and methods described in this specification can be used to induce controlled focal or circumferential ablation of target tissue to varying depths in a manner that allows for complete healing through epithelial regeneration. Furthermore, steam can be used to treat / ablate benign and malignant tissue growths, leading to destruction, necrosis, and absorption of the ablated tissue. The dosage and manner of treatment can be adjusted according to the type of tissue and the desired ablation depth. The ablation device can be used not only to treat arrhythmias, Barrett's esophagus and esophageal dysplasia, flat colon polyps, gastrointestinal bleeding lesions, endometrial ablation, and lung ablation, but also to treat any mucosal, submucosal, or peripheral lesions, such as inflammatory lesions, tumors, polyps, cysts, and vascular lesions. The ablation device can also be used to treat local or surrounding mucosal or submucosal lesions of any hollow organ or hollow body passage in the body. Hollow organs can be the gastrointestinal tract, pancreatic ducts, urogenital tract, respiratory tract, heart, parts of the cardiovascular system, bladder, uterus, or vascular structures such as blood vessels. The ablation device can be placed endoscopically, radiographically, surgically, or by direct observation. In various embodiments, a wireless endoscope or a single-fiber endoscope may be incorporated as part of the device. In another embodiment, magnetic navigation or stereotactic navigation may be used to navigate the catheter to a desired location. Radiopaque or acoustically transparent materials may be incorporated into the body of the catheter for radiographic positioning. Ferromagnetic materials may be incorporated into the catheter to aid in magnetic navigation.

[0107] Ablation agents, such as vapor, heated gases, or cryogenic agents like, but not limited to, liquid nitrogen, are inexpensive and readily available, and are directed onto the tissue through an infusion port, maintained at a fixed and consistent distance from the target tissue. This allows the ablation agent to be uniformly distributed across the target tissue. The flow rate of the ablation agent is controlled by a microprocessor according to a predetermined method based on the characteristics of the tissue to be ablated, the desired ablation depth, and the distance between the port and the tissue. Additionally, one or more aspiration ports are provided to aspirate the ablation agent from the vicinity of the target tissue. The target segment can be treated by continuous injection of the ablation agent or by a cycle of injection and removal of the ablation agent determined and controlled by the microprocessor.

[0108] The ablation system described in this specification is configured to have reduced start-up time and perfusion process. In some embodiments, impedance is measured during start-up to check for saline contact with the electrodes. The controller is configured to automatically perform impedance checks and generate an error indicating high impedance, suggesting that the saline is not in contact with the electrodes or that the wires are broken. A rapid change in impedance level from high to low at the electrodes is also detected as an indication of saline contact with the electrodes. Furthermore, in embodiments, the controller is configured to check the power level delivered to the electrodes during start-up. In embodiments, the controller is configured to check the radio frequency (RF) power relative to the direct current (DC) power level. Preferably, the controller checks to determine whether the RF power matches the DC power within a range of at least 50%, preferably about 75%. If not, the controller does not continue the treatment period and indicates an error, such as an electrical short circuit, fluid blockage, or some other error, on the graphical user interface, preferably with instructions on how to resolve the error. Preferably, the controller checks to determine whether the motor current experiences an increase of more than 10% or about 25%, indicating stall current torque on the motor. If such an increase is determined, the controller does not continue the treatment period and indicates fluid blockage on the graphical user interface, preferably with instructions on how to resolve the fluid blockage. The embodiments described in this specification also eliminate the need for a pressure sensor. Any fluid blockage or flow problem is detected by measuring the fluid flow resistance at the pump. A relatively high current required to push the syringe may indicate a blockage. Therefore, the detection is performed by the controller, eliminating the need to include a pressure sensor in the conduit.

[0109] In one embodiment, the controller is configured to automatically flush the catheter during startup before insertion into the patient. This automatic flushing by the controller bypasses the need for the user to initiate flushing and manually stop it once water flows out of the catheter. In another embodiment, startup time is reduced by delivering steam at a high power level of approximately 2 to 4 times the normal therapeutic power level (which can range from 150 W to 300 W), and then reducing the power delivered to the electrode to a steady-state level (which can be approximately 60 W or otherwise defined as a power level that does not change by more than 10%, preferably more than 5%, over a period of time, such as 5 seconds, 10 seconds, or more). The delivered power is also automatically controlled by the controller.

[0110] The embodiments of the ablation system described in this specification provide methods and systems for the controlled generation of ablation vapor. See again... Figure 1A In some embodiments, the ablation system 100 is responsible for generating an electrical current and applying force to a pump 140, which provides a flow of ablation agent, such as saline, into the lumen 118 of the conduit 110. Using an electrical port 127 directly connected to an electrical port 157 on a controller 150, current is delivered to electrodes 118a / 118b within the lumen 118. Figure 5 This is a flowchart illustrating an exemplary process for controlling steam generation in an ablation apparatus 100 according to some embodiments of this specification. In step 502, a user interface (UI) is available as an input device for the controller 150. A user, such as a clinician, interacts with the UI to set the maximum treatment time for the steam ablation process. In this embodiment, the treatment time is set before treatment is initiated. Figure 6 As shown, the UI can provide a touchscreen, buttons, or a combination of both, as well as a display, allowing the user to input and view the time period set for treatment. In step 504, the controller uses the treatment time input by the user to determine the energy required to ablate the target tissue. Treatment is initiated when the controller starts supplying power to operate electrode 118, which in turn generates steam by heating the ablation fluid supplied by pump 140. The power supplied to the ablation device 100 and the flow rate of the ablation fluid from pump 140 are constant, therefore the amount of energy delivered to the target site during ablation is determined by the amount of time set by the user (which is a function of the tissue being ablated). The impedance / resistance of the ablation fluid is consistent because the flow rate is stable and the salinity (conductivity) of the ablation fluid is consistent. The following equation is used to represent the total energy delivered:

[0111] The total energy delivered = power × time, where power is a function of the current and voltage supplied to the device from the power source.

[0112] In step 506, when the set time period ends, the controller 150 stops steam generation, thus interrupting energy delivery. Steam generation ceases as the controller 150 stops supplying power to the electrode 118 in the conduit 110 when the predetermined time has elapsed. Optionally, the user can manually intervene to stop the process before the set time period. In one embodiment, an input device provided as an option or button on the UI or a foot pedal is used to intervene and stop the ablation process. Embodiments of this specification can limit the maximum ablation dose based on the maximum therapeutic dose by automatically cutting off steam generation. In step 502, the maximum dose is input to the device 100 as a function of time. As an additional safety measure, the device 100 allows the user to interrupt energy delivery at any time during treatment, even before the maximum dose is reached, by disabling power via the UI or by releasing the foot pedal. In some embodiments, the controller 150 is programmed to repeatedly deliver therapeutic ablation treatments for a predetermined duration, wherein each treatment lasts for a set time period and is interleaved with another predetermined time interval when steam delivery stops.

[0113] While the catheter preferably does not include sensors for sensing flow rate, temperature, pressure, steam quality, or humidity levels, in one embodiment, the catheter may include programmable elements or components with measurable characteristics, such as resistors. Preferably, the values ​​stored in the programmable elements or the measured component values, such as resistor values, can be automatically set by a controller. In one embodiment, the controller is configured to program values ​​such as resistance values, as discussed throughout this application, based on the type of treatment or set treatment variables, such as power, voltage, current, fluid flow rate, and / or treatment time.

[0114] Steam generation control algorithm

[0115] In one embodiment, the controller is programmed to automatically generate steam for pre-filling and treatment. In one embodiment, the control algorithm originates from control signals and measurements related to the RF energy delivered to the ablation fluid and the resulting transformation of the ablation fluid (water or saline) into steam. The controller controls voltage, current, and / or power to heat the ablation fluid and generate fluid steam, and measures the results of these control signals. The measured signals are used to further control or optimize the characteristics of the steam. Therefore, the steam generation process includes a series of steps performed before the ablation device is used. The user sets the control or output voltage and measures the generated current. The controller then calculates the impedance and the resulting power delivered to the ablation fluid. Similarly, the control or output current is set, the generated voltage is measured, and the power delivered to the ablation fluid and the resulting impedance are calculated. Furthermore, the control or output power is set, the voltage or current level is adjusted to achieve the desired power delivered to the ablation fluid, and the resulting impedance is calculated. Additionally, the control or output voltage is set, the resulting current is measured, and the power delivered to the fluid to generate steam and the resulting impedance are calculated. In this embodiment, the control voltage and / or control current can be adjusted to change the power supplied to the fluid and the amount or quality of steam generated.

[0116] As mentioned here, the controller can use one or a combination of the steps described to measure and control steam generation. Impedance is calculated when the controller a) sets the control voltage and measures the current, and when b) sets the control current and measures the voltage, impedance is calculated, and the change in impedance is calculated as steam generation begins to cause a relevant change in impedance. The change in impedance can be reflected as a sharp increase in impedance, for example, in the form of a “step change.” The amount of impedance change may depend on the inherent impedance of the fluid. For example, for brine, the inherent impedance of a steam chamber geometry at an RF output frequency of 460 kHz is approximately 2 ohms. When steam is generated, the impedance change at 460 kHz is large, for example, approximately 10–60 ohms or greater, depending on the steam quality and steam power.

[0117] The onset of steam or steam generation can be detected based on one or more characteristics derived from impedance measurements. In one embodiment, a step change in impedance from a minimum average value of about 2 ohms to about 15 ohms can indicate steam generation. In another embodiment, a change in impedance calculated characteristics from a semi-constant or slowly varying value of about 1-3 ohms to a highly variable value of about 10 ohms to 60 ohms or greater indicates steam generation. The change in impedance is caused by the conversion of fluid to steam, as a random boiling process occurs, resulting in steam in contact with the electrode surface being less conductive than the fluid in contact with the electrode surface. Because boiling is random, the resulting impedance varies randomly from low to high values ​​and between high and low values.

[0118] The controller performs the following actions:

[0119] a. Set the control voltage and measure the current.

[0120] b. Set the control current and measure the voltage.

[0121] Calculate the RF output power. A change in output power is detected when steam generation begins. This change is reflected as a sharp drop or a "step" drop in output power. The amount of change may depend on the inherent impedance of the ablative fluid. For example, for brine, at an RF output frequency of 460 kHz, the inherent impedance is approximately 2 ohms for a specific model of the steam chamber geometry. When delivering steam, the impedance at 460 kHz is variable, for example, approximately 10–60 ohms or greater, depending on the steam quality and steam power.

[0122] The controller can detect the actual start of steam or steam generation based on one or more characteristics derived from power measurements. In one embodiment, a decrease or step change in output power from a minimum average value of about 100-200 watts to about 40-50 watts indicates steam generation. In another embodiment, a change in the calculated power characteristic from a semi-constant or minimum variation value of about 100-200 watts to a variable value of about 10 watts to 60 watts is an indication of steam generation. Although the change in calculated power depends on the voltage setting, the form of the change is similar. For example, if the voltage is about 30 volts, the calculated average power is about 50 watts. If the voltage is about 15 volts, the average power is calculated to be about 20 watts. Therefore, in one embodiment, the controller is configured to detect the actual start of steam generation by monitoring changes in output power, such as a first output power decreasing from a range of 100-200 watts to a second output power within a range of 60 watts or less, which is independent and separate from the initiation of fluid flow to the heating chamber.

[0123] When the controller sets the power and adjusts the current and / or voltage to achieve the set power, a change in the output voltage and / or current is detected when steam generation begins. This change in output voltage and / or current or resistance is reflected as a sharp increase or "step change" in voltage, or a sharp decrease or "step change" in current. The amount of change may depend on the inherent impedance of the ablative fluid. For example, for brine, at an RF output frequency of 460 kHz, the inherent impedance is approximately 2 ohms for a specific model of steam chamber geometry. When steam is delivered, the impedance at 460 kHz is variable, for example, approximately 10-60 ohms or greater, depending on the steam quality and steam power. Therefore, in one embodiment, the controller is configured to detect the actual start of steam generation by monitoring changes in output voltage or current, such as an increase in output voltage or a decrease in current, which is independent and separate from the initiation of fluid flow to the heating chamber.

[0124] The controller can detect the onset of actual steam or steam generation based on one or more characteristics obtained from power measurements. In one case, if the output power drops or steps from approximately 100-200 watts to a minimum average of approximately 40-50 watts, a change in the calculated power characteristic from a semi-constant or minimally variable value of approximately 100-200 watts to a highly variable value of approximately 10 watts to 60 watts is an indication of steam generation. Although the change in calculated power depends on the voltage setting, the directionality of the change is similar. For example, if the voltage is approximately 30 volts, the calculated average power is approximately 50 watts. If the voltage is approximately 15 volts, the calculated average power is approximately 20 watts.

[0125] In another scenario, if the resistance increases or steps from approximately 2-3 ohms to a minimum average value of approximately 8-20 ohms, a change in the resistance value from a semi-constant or minimum variation value of approximately 2-3 ohms to a highly variable value of approximately 8 to 20 ohms indicates steam generation. In yet another embodiment, if the voltage increases or steps from approximately 7 volts to a minimum average value of approximately 30 volts, a change in the output voltage characteristic from a semi-constant or minimum variation value of approximately 7 volts to a highly variable value of approximately 30 to 34 volts indicates steam generation. Therefore, in one embodiment, the controller is configured to detect the actual onset of steam generation by monitoring changes in resistance variability, current variability, voltage variability, or power variability, such as an increase in variability, which is independent and separate from the initiation of fluid flow to the heating chamber.

[0126] For each of the control modes described above involving voltage, current, and power, voltage source control can be replaced by current source control and associated voltage measurement to achieve the same control response. Alternatively, for each control mode, current source control can be replaced by voltage source control and associated current measurement to achieve the same control response. Furthermore, voltage or current control can be replaced by power control, and related changes in control voltage or control current can be implemented.

[0127] In the embodiments described in this specification, the RF voltage, current, and / or power delivery is interrupted during the treatment time and is therefore not constant. This has the effect of reducing the delivered energy and can alter or reduce the final temperature of the fluid or vapor, and / or reduce the rate of temperature rise of the fluid or vapor during the treatment time. The interruption of RF energy delivery can occur periodically or non-periodically to produce a desired energy delivery profile and / or temperature rise rate. Furthermore, the fluid flow rate can be changed periodically or non-periodically to regulate the energy delivery rate and / or temperature rise rate.

[0128] The embodiments described in this specification enable the controller to be programmed to control the pulsed delivery and temperature response of ablation energy in the form of vapor during treatment. For this purpose, the user can set the treatment time, which will automatically cause the voltage, current, and / or power to be set at the required levels for ablation of the target tissue according to the set time. In one embodiment, for a specific configuration of the vapor chamber of the ablation device, the control voltage, current, or power is automatically set to a portion of the input time period, where this portion is approximately 250 milliseconds (ms). The controller can then automatically stop the RF delivery for a period of approximately 250 ms. A duty cycle of 250 ms for enabling RF delivery and 250 ms for disabling RF delivery is repeated. In this way, pulsed delivery of RF energy is provided to the ablation device, representing a periodic and symmetrical 50:50 duty cycle. In another embodiment, the control voltage, current, or power, automatically set by the input time, is delivered for a period of approximately 1000 ms, followed by a gap of approximately 300 ms when the RF delivery stops, followed again by 1000 ms of RF delivery. In this embodiment, pulsed ablation energy is also delivered with a repeated 25:75 duty cycle. It should be understood that the duty cycle of the on / off switch can be divided into 5:95 to 95:5 according to the ratio of the input treatment time. In this way, the controller is configured to automatically convert the input treatment time into an on / off duty cycle within the above range.

[0129] In a further embodiment, the duration for enabling and disabling RF delivery can be varied throughout the treatment duration. In one embodiment of the pulse delivery cycle, voltage, current, or power is delivered for 100 ms, stopped for 100 ms, delivered again for 100 ms, and then stopped for 300 ms. Repeating this pulse delivery pattern represents a periodic and asymmetric duty cycle of 50:50:25:75. Therefore, in embodiments, the duty cycle can be adjusted to result in a high rate of energy delivery and / or a rapid increase in fluid and / or vapor temperature.

[0130] While not preferred, according to some embodiments, the output of the ablation device is measured during treatment to provide additional control. In some embodiments, the flow rate of a pump (e.g., an infusion pump) is adjusted during treatment. Adjusting the flow rate can optimize vapor quality, thereby increasing the average impedance. The flow rate is adjusted to increase or decrease based on the desired vapor quality. Increasing the flow rate improves the vapor quality, while decreasing the flow rate decreases the vapor quality. In one case, after the ablation vapor has been delivered to the target tissue, such as during pulsed delivery of treatment, the flow rate is reduced or even stopped to minimize fluid delivery. In embodiments, a controller receives output signals, such as temperature and impedance during vapor generation, and uses them to regulate or control the fluid flow rate from the pump. Output measurements from the ablation device are used to monitor the consistency of vapor generation, and the fluid flow control signal can be adjusted to compensate for output variations.

[0131] In one embodiment, the controller adjusts the fluid flow rate to a first flow rate (R1) before steam generation is detected and to a second flow rate (R2) after steam generation is detected. This change in the infusion pump flow rate minimizes the amount of fluid or low-quality steam delivered to the treatment site. In one example, the fluid flow rate (R1) before steam generation is detected can be from about 0.01 ml / min to 1.0 ml / min, and the fluid flow rate (R2) after steam generation is detected can be from about 2.0 ml / min to 2.2 ml / min. The flow rate can vary for steam chambers with different geometries. Various combinations are possible depending on the desired steam power output, the quality and quantity of fluid delivered to the treatment site.

[0132] Depending on the tissue or organ system being treated, the configuration of the various catheters in the ablation systems described in this specification may differ. The distribution and depth of ablation provided by the systems and methods of this specification depend on the duration of exposure to vapor, the ablation size, the temperature and / or mass of the vapor, the contact time with the vapor, and the tissue type.

[0133] The examples above are merely illustrations of many applications of the system of the present invention. Although only a few embodiments of the invention have been described herein, it should be understood that the invention may be practiced in many other specific forms without departing from the spirit or scope thereof. Therefore, these examples and embodiments are to be considered illustrative rather than restrictive, and the invention may be modified within the scope of the appended claims.

Claims

1. A steam ablation system, comprising: A controller with user input configured to receive data indicating the duration of treatment; A pump that communicates data with the controller; as well as A conduit in fluid communication with a pump and having an elongated shaft, a proximal end, and a distal end, the conduit comprising: At least one lumen; and At least one electrode inside the cavity, The controller is configured to control a pump to supply fluid to the lumen of a catheter, wherein the controller is configured to deliver an electrical current to at least one electrode to heat the fluid in the lumen and convert the fluid into heated steam, and wherein the controller is configured to control the delivery of fluid and the generation of heated steam by controlling the flow rate and the levels of power, voltage and / or current of the fluid solely based on data indicating the treatment period duration, wherein the treatment period duration is determined based on the treatment provided, such that the levels of power, voltage and / or current are automatically set to the levels of treatment provided according to the treatment period duration, and wherein during the treatment period, the ratio of the fluid flow rate to the power, voltage and / or current levels is fixed solely based on data indicating the treatment period duration.

2. The steam ablation system according to claim 1, wherein, The controller is also configured to control the delivery of fluid and the generation of heating steam by controlling the flow rate and power, voltage and / or current levels of the fluid without modifying the fluid flow rate or the voltage and / or current levels of the electrical current based on data from sensors located in or above the conduit.

3. The vapor ablation system of claim 1, further comprising a cap in fluid communication with the distal end of the catheter, the cap being configured to guide the ablation agent from the at least one lumen to body tissue, wherein the cap is defined by an enclosed outer shell, and wherein a single opening in the outer shell is located on a side of the cap parallel to or at an angle of 5 degrees or greater relative to the longitudinal axis of the catheter.

4. The steam ablation system according to claim 3, wherein, The cap includes a rounded or curved outer edge or outer surface and is detachably attached to the distal end of the catheter.

5. The steam ablation system according to claim 3, wherein, The single opening has a polygonal coverage area.

6. The steam ablation system according to claim 5, wherein, The polygon includes one of the following: square, rectangle, pentagon, or hexagon.

7. The steam ablation system according to claim 3, wherein, The cap is at an angle ranging from 5 to 45 degrees relative to the longitudinal axis of the catheter.

8. The steam ablation system according to claim 1, wherein, The controller is also configured to detect the actual start of heating steam generation by monitoring changes in output power, output voltage, or output current, which is independent and separate from the initiation of fluid flow to the at least one electrode.

9. The steam ablation system according to claim 1, wherein, The controller is also configured to automatically apply a predetermined on / off duty cycle during the treatment period.

10. The steam ablation system according to claim 1, wherein, The fluid is salt water.

11. The steam ablation system according to claim 1, wherein, The controller is configured to deliver power ranging from 5 watts to 300 watts to the at least one electrode.

12. The steam ablation system according to claim 1, wherein, The controller is configured to deliver fluid into the cavity at a flow rate of 2 ml / min.

13. The steam ablation system according to claim 1, wherein, The at least one electrode includes a bipolar electrode.

14. The steam ablation system according to claim 1, wherein, The controller is configured to automatically apply a fixed power / flow rate relationship during the treatment period, which cannot be changed based on sensing data indicating the steam quality, temperature, humidity level, or pressure of the heating steam.

15. The steam ablation system according to claim 1, wherein, The conduit does not include sensors configured to sense the steam quality, temperature, humidity level, or pressure of the heated steam.

16. The steam ablation system according to claim 1, wherein, The catheter includes programmable elements, and the controller is configured to program the programmable elements based on at least one of treatment type, power level, voltage level, current level, fluid flow rate, or treatment time.

17. The steam ablation system according to claim 16, wherein, The programmable element is a resistor.

18. A steam ablation system, comprising: A controller with a user interface configured to receive data indicating the duration of treatment; An injection pump that communicates data with the controller; A catheter in fluid communication with an infusion pump and having an elongated shaft, a proximal end, and a distal end, the catheter comprising: At least one lumen; At least one electrode inside the cavity, The controller is configured to control a pump to supply fluid to the lumen of a catheter, wherein the controller is configured to deliver an electrical current to at least one electrode to heat the fluid in the lumen and convert the fluid into heated steam, wherein the controller is configured to control the delivery of fluid and the generation of heated steam by controlling the flow rate of the fluid and the power, voltage, and / or current level of the electrical current based on data indicating the treatment duration, wherein the treatment duration is determined based on the treatment provided, such that the power, voltage, and / or current level is automatically set to the level of the treatment provided according to the treatment duration, and wherein the controller is further configured to control the delivery of fluid and the generation of heated steam without modifying the flow rate of the fluid or the voltage and / or current level of the electrical current based on data from sensors located in or above the catheter, and wherein during the treatment duration, the ratio of the fluid flow rate to the power, voltage, and / or current level is fixed only according to the data indicating the treatment duration; and A cap in fluid communication with the distal end of a catheter, the cap being configured to guide an ablative from at least one lumen into body tissue, wherein the cap is defined by an enclosed shell of a certain volume, and wherein a single opening in the shell is located on the side of the cap that is parallel to or at an angle of 5 degrees or greater relative to the longitudinal axis of the catheter.

19. The steam ablation system according to claim 18, wherein, The controller is configured to use the data to determine the duration for which the at least one electrode receives current to heat the fluid in the cavity and convert the fluid into heated steam.

20. The steam ablation system according to claim 18, wherein, The steam ablation system is adapted to operate at a constant fluid flow rate from the pump to the lumen of the conduit.

21. The steam ablation system according to claim 18, wherein, The controller is configured to maintain the power delivered to the at least one electrode in a stable state by keeping the voltage level and impedance in a stable state.

22. The steam ablation system according to claim 18, wherein, The controller is configured to maintain the impedance in a stable state by keeping the flow rate and salinity of the fluid in a stable state.

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