Apparatus and method for cryogen measurement and control for cryoablation systems

Abstract

The present disclosure relates to devices and methods for cryogen measurement and control for cryoablation systems. A cryoablation device includes a Dewar defining an interior volume configured to hold a volume of cryogen, a supply tube extending into the interior volume of the Dewar, a heating assembly positioned at a distal end of the supply tube, a pump assembly positioned proximate the heating assembly, and a cap assembly coupled to the Dewar at a proximal end of the supply tube opposite the distal end of the supply tube. The cryoablation device also includes a capacitance-based cryogen level sensor positioned in the Dewar flask.

Description

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application is related to U.S. Patent Application No. TBD entitled “APPARATUSES AND METHODS FOR CRYOABLATION SYSTEMDIAGNOSTICS AND PURGE”, which was filed on the same date as the present application by Varian Medical Systems, Inc. The entire disclosure of the above application is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to apparatus and methods for cryogen measurement and control for cryoablation systems. Background Art

[0004] This section provides background information related to the present disclosure which is not necessarily prior art.

[0005] Systems and methods for providing cryoablation therapy can include a cryoablation probe introduced at or near a target tissue in a patient's body. A cryoablation system can include an extremely cold cryogen (liquid, gas, or mixed phase of nitrogen, argon, helium, etc.), which can be transferred through a probe in thermal contact with the target tissue. Heat from the tissue is transferred from the tissue through the probe and into the cryogen, thereby removing heat from the target tissue. This removal of heat causes the tissue to freeze, thereby causing destruction of the target tissue. When the tissue freezes, ice is typically formed in the form of an ice ball. The ice ball can be a sphere, an ellipsoid, or other round shape. It is desirable to perform cryoablation therapy so that the target tissue is completely frozen and the freezing of surrounding tissues and / or body structures is minimized.

[0006] Conventional or existing systems typically include a cryogen source and delivery system that operates to deliver cryogen to a probe to produce a satisfactory and predictable temperature at the target tissue. However, existing systems may include multiple independent systems, separate controls, independent measurement devices, and separate user interfaces, which may lead to inefficiencies and reduced treatment effectiveness. Therefore, improved devices and systems are needed to increase efficiency, reduce treatment costs, and improve treatment effectiveness. Summary of the invention

[0007] This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] In some embodiments of the present disclosure, a cryoablation device may include a capacitance-based level sensor positioned in a dewar. The capacitance-based level sensor may be coupled to a cryocontrol that may determine the cryogen level based on the capacitance of the level sensor in the dewar. The cryocontrol may continuously determine the cryogen level in the dewar from the capacitance-based level sensor. This real-time and / or continuous indication of the cryogen level may be used to optimize the operation, performance, and effectiveness of the cryoablation device.

[0009] In some embodiments, a cryoablation device may include a dewar defining an internal volume for containing a cryogen, and a capacitance-based cryogen level sensor positioned in the dewar configured to provide a cryogen level of the cryogen in the dewar. The cryoablation device may also include a cryocontrol configured to send a cryogen level warning if the cryogen level is below a predetermined level.

[0010] In one aspect, a capacitance-based cryogen liquid sensor can include a cryogen rod extending within an interior volume of a Dewar.

[0011] In another aspect, the cryogen rod may include a first capacitor surface and a second capacitor surface. The first capacitor surface may be concentrically positioned around the second capacitor surface and define an annular cavity therebetween.

[0012] In another aspect, a cryoablation device can include a control circuit coupled to a capacitance-based cryogen level sensor and a cryocontrol. The cryocontrol and control circuit can be configured to continuously charge and discharge the capacitance-based cryogen level sensor during a cryoablation cycle to continuously determine the cryogen level in the Dewar.

[0013] In another aspect, the cryogen control can be further configured to determine the cryogen level based on a capacitance of the capacitance-based cryogen level sensor and one or more operating conditions of the Dewar.

[0014] In another aspect, the one or more operating conditions of the Dewar can include the temperature and pressure of the cryogen in the Dewar.

[0015] In another aspect, the one or more operating conditions of the Dewar can include the flow of cryogen.

[0016] In another aspect, a capacitance-based liquid level sensor can include a cavity configured to supply cryogen from a Dewar to a cryoprobe.

[0017] In another aspect, the capacitance-based level sensor can be configured to provide the refrigerant level of the refrigerant at any level along the length of the capacitance-based level sensor.

[0018] In another aspect, the cryogen control can be configured to determine the cryogen level based on a mapping of the capacitance of the capacitance-based level sensor to the amount of cryogen liquid in the Dewar.

[0019] In some embodiments of the present disclosure, a method for determining cryogen level is provided. The method may include obtaining a capacitance from a capacitance-based level sensor in a dewar vessel, and determining the cryogen level based on the capacitance.

[0020] In one aspect, the step of obtaining a capacitance may include continuously charging and discharging a capacitance-based fluid level sensor during a cryoablation cycle.

[0021] In another aspect, the step of obtaining a capacitance can be performed while moving liquid cryogen through a capacitance-based liquid level sensor.

[0022] In another aspect, the step of determining the cryogen level can be based on one or more operating conditions in the Dewar.

[0023] In another aspect, the one or more operating conditions in the Dewar can include the temperature and pressure of the cryogen.

[0024] In another aspect, the one or more operating conditions in the Dewar can include the flow of cryogen.

[0025] In another aspect, the method may include sending a refrigerant level warning if the refrigerant level is below a predetermined level.

[0026] In another aspect, a capacitance-based liquid level sensor can be implemented as a cryogen rod extending within the Dewar.

[0027] In another aspect, the step of determining the refrigerant level can be performed using a trained machine learning model.

[0028] In some embodiments, a freezer control is provided. The freezer control may include a processor and a memory, and the freezer control may be configured to perform the method of the present disclosure.

[0029] In some embodiments of the present disclosure, a cryoablation device is provided, which includes a pressure control that can use a closed-loop feedback process to automatically monitor and adjust the pressure in the Dewar flask and in the cryogen supply line to efficiently and effectively deliver the cryogen to one or more cryoprobes. The cryoablation device may include a heating assembly located in the Dewar flask and a low-pressure sensor in the Dewar flask to monitor the pressure of the cryogen in the Dewar flask and activate and control the heating assembly to pressurize the Dewar flask to a desired low-pressure condition. The cryoablation device may also include a high-pressure pump assembly that can be controlled and adjusted to provide a high-pressure cryogen flow to one or more cryoprobes. Low-pressure monitoring and control in the Dewar flask can be performed in parallel with high-pressure monitoring and control to provide cryogen more efficiently and effectively than existing systems.

[0030] In some embodiments of the present disclosure, a cryoablation device may include: a dewar defining an internal volume, the internal volume being configured to hold a volume of cryogen, and a supply tube extending into the internal volume of the dewar. The cryoablation device may also include a heating assembly positioned at a distal end of the supply tube and a pump assembly positioned proximate the heating assembly. The cryoablation device may also include a cap assembly coupled to the dewar at a proximal end of the supply tube opposite the distal end of the supply tube.

[0031] In one aspect, the distal end of the supply tube can be positioned near the bottom of the Dewar.

[0032] In another aspect, a heating assembly can include a bubble barrier including at least one wall defining a heating boundary and a heater positioned within the bubble barrier.

[0033] In another aspect, the distal end of the supply can be positioned at the top of the bubble barrier.

[0034] In another aspect, the device can include at least one pressure sensor positioned within the bubble barrier.

[0035] In another aspect, the heater can be configured to increase the local pressure of the cryogen within the heating boundary to a pressure that is greater than the pressure of the cryogen outside the heating boundary.

[0036] In another aspect, the cryoablation device may include a pressure control operably coupled to the heating assembly, the pump assembly, and the cap assembly. The pressure control may be configured to activate and deactivate the heater to maintain the cryogen supplied to the supply tube at a pressure within a first predetermined operating range.

[0037] In another aspect, the pressure control may be further configured to operate the pump assembly and the cap assembly to pressurize the refrigerant at the outlet of the pump to a pressure within a second predetermined operating range.

[0038] In another aspect, the first predetermined operating range is a low pressure range and the second predetermined operating range is a high pressure range.

[0039] In another aspect, the cryoablation device may include a valve assembly fluidically coupled to the interior volume of the dewar. A pressure control may be operably coupled to the valve assembly and further configured to open a valve of the valve assembly when a pressure of the cryogen in the dewar is greater than an upper pressure level of a first predetermined operating range, and to open a valve of the valve assembly when a pressure of the cryogen at an outlet of the pump is greater than an upper pressure level of a second predetermined operating range.

[0040] In some embodiments of the present disclosure, a method of pressurizing a cryogen includes obtaining Dewar pressure information characterizing the cryogen pressure in the Dewar, and maintaining the cryogen pressure in the Dewar within a first pressure range using a heating assembly in the Dewar. The method may also include obtaining pump pressure information characterizing the cryogen pressure at the outlet of a pump, and maintaining the cryogen pressure at the outlet of the pump within a second pressure range using a pump, wherein the steps of maintaining the cryogen pressure in the Dewar and maintaining the cryogen pressure at the outlet of the pump are performed simultaneously.

[0041] In another aspect, the first pressure range can be a low pressure range and the second pressure range can be a high pressure range.

[0042] In another aspect, the first pressure range can be in the range of about 10 psi to about 15 psi.

[0043] In another aspect, the second pressure range can be in the range of about 400 psi to about 600 psi.

[0044] In another aspect, the step of maintaining the pressure of the cryogen in the Dewar can be performed using a heating assembly that can include a bubble barrier including at least one wall defining a heating boundary and a heater positioned within the bubble barrier.

[0045] In another aspect, the step of maintaining the pressure of the cryogen in the Dewar can include determining when the pressure of the cryogen in the Dewar is outside of a first pressure range and modifying an operating parameter of a heater in the Dewar.

[0046] In another aspect, the step of modifying an operating parameter of the heater may include determining a modification to a duty cycle delivered to the heater, and the modification to the duty cycle may be determined using a trained machine learning model.

[0047] In another aspect, the step of maintaining the pressure of the refrigerant at the outlet of the pump may include determining one or more modifications to an operating parameter of the pump.

[0048] In another aspect, a trained machine learning model can be used to determine one or more modifications to an operating parameter of a pump.

[0049] In some embodiments of the present disclosure, a pressure control is provided. The pressure control may include a processor and a memory, and the pressure control may be configured to perform any method of the present disclosure.

[0050] In some embodiments of the present disclosure, a cryogen gas device is provided. The cryogen gas device may include: a housing configured to hold a volume of liquid cryogen; and a heater positioned in the housing and configured to heat the liquid cryogen to convert the liquid cryogen into cryogen gas. The cryogen gas device may also include a flow conduit including a conduit heater. The flow conduit may be connected to the housing and configured to fluidly connect the housing to a cryogen flow path of a cryoablation system.

[0051] In another aspect, the cryogen gas device can include a connector configured to fluidly connect the housing to a dewar of a cryoablation system.

[0052] In another aspect, the housing can be positioned inside a dewar of a cryoablation system.

[0053] In another aspect, a flow conduit can be positioned at the top of the housing to distribute cryogen gas from the housing to the cryogen flow path.

[0054] In another aspect, the cryogen gas device can include a gas control coupled to the heater and the conduit heater. The gas control can be configured to activate the heater to achieve a predetermined pressure in the housing and activate the conduit heater to achieve a predetermined temperature of the cryogen gas.

[0055] In another aspect, the gas control is further configured to distribute the cryogen gas to the cryogen flow path to perform a purge of the cryogen flow path.

[0056] In some embodiments of the present disclosure, a cryoablation device may include a dewar and a cryogen gas device positioned in the dewar.

[0057] In some embodiments of the present disclosure, a method for purging a cryogen flow path is provided. The method may include moving a portion of a volume of liquid cryogen from a dewar into a housing of a cryogen gas device, heating the portion of a volume of liquid cryogen to form cryogen gas in the housing, and moving the cryogen gas from the housing into the cryogen flow path to purge the cryogen flow path.

[0058] In another aspect, the housing defines an interior cavity within the dewar.

[0059] In another aspect, the housing can be positioned in a Dewar.

[0060] In some embodiments of the present disclosure, a cryoablation device may include a dewar configured to hold a volume of cryogen, and a cryogen flow path, which is fluidically coupled to the dewar to supply cryogen to the cryoprobe. The cryoablation device may also include a first pressure sensor and a second pressure sensor positioned at a first portion of the cryogen flow path and a second portion of the cryogen flow path, respectively, and a first valve and a second valve positioned along the cryogen flow path, respectively, each valve being configured to operate in an open position to allow the flow of cryogen, and to operate in a closed position to prevent the flow of cryogen. The cryoablation device may also include a diagnostic control operably coupled to the first pressure sensor, the second pressure sensor, the first valve, and the second valve. The diagnostic control may be configured to determine whether there is a blockage or leak in the first portion and the second portion of the cryogen flow path.

[0061] In another aspect, the second portion of the refrigerant flow path is positioned downstream of the first portion, and the diagnostic control is configured to determine whether a blockage or leak exists in the first portion before the second portion.

[0062] In another aspect, the first portion and the second portion are positioned along a supply line of the cryogen flow path.

[0063] In another aspect, a cryoablation device can include a return line fluidly coupled to the cryoprobe and the supply line.

[0064] In another aspect, the cryoablation device can further include a first connector valve that fluidly connects the supply line to the return line at a location upstream of the first valve.

[0065] In another aspect, the cryoablation device can include a second connector valve that fluidly connects the supply line to the return line at a location downstream of the first valve and upstream of the second valve.

[0066] In another aspect, the return line can be fluidly coupled to the exhaust port, thereby allowing pressure in the return line to be exhausted from the cryogen flow path.

[0067] In another aspect, the diagnostic control can determine if a blockage or leak exists by comparing the pressure to a target pressure range and comparing the time to reach a maximum pressure to a target time range.

[0068] In another aspect, the diagnostic control can use a trained machine learning model to determine if a blockage or leak exists.

[0069] In another aspect, the diagnostic control can be configured to cause a purge of the refrigerant flow path to be performed when it determines that an obstruction exists.

[0070] In another aspect, the diagnostic control can be configured to operate the first valve in an open position and the second valve in a closed position to determine if there is an obstruction or leak in the first portion, and then the diagnostic control operates the first valve in an open position and the second valve in an open position to determine if there is an obstruction or leak in the second portion.

[0071] In some embodiments of the present disclosure, a method for diagnosing refrigerant flow in a refrigerant flow circuit is provided. The method may include obtaining pressure information of a refrigerant pressure in a first portion of the refrigerant flow circuit, comparing the pressure information with a target pressure range, comparing a time to reach a maximum pressure in the first portion of the refrigerant flow circuit with a target time range, and sending a flow alarm if a flow problem is detected based on the pressure information and the time to reach the maximum pressure.

[0072] In another aspect, the method can include opening a first valve to allow cryogen to flow to a first portion of the cryogen flow path.

[0073] In another aspect, the method may further include opening a second valve to allow refrigerant to flow to a second portion of the refrigerant flow path, wherein the second portion of the refrigerant flow path is positioned downstream of the first portion, obtaining pressure information of the refrigerant pressure in the second portion of the refrigerant flow path, comparing the pressure information with a second target pressure range, comparing a second time to reach a maximum pressure in the second portion of the refrigerant flow path with a second target time range, and sending a flow alarm if a flow problem is detected based on the pressure information in the second portion of the refrigerant flow path and the second time to reach the maximum pressure.

[0074] In another aspect, if a flow problem is detected, the method can include venting pressure from the cryogen flow path.

[0075] In another aspect, the pressure is vented by opening a connector valve fluidly connecting the first portion of the cryogen flow circuit to a return line of the cryogen flow circuit.

[0076] Further areas of applicability will become apparent from the description provided herein.The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0078] Figure 1 is a diagram illustrating an example cryoablation device according to some embodiments of the present disclosure.

[0079] Figure 2 is a diagram illustrating an example refrigerant source with a refrigerant capacitive level sensor according to some embodiments of the present disclosure.

[0080] Figure 3A can be used for Figure 2 Cross-sectional view of an example rod sensor of a cryogen source.

[0081] Figure 3B can be used for Figure 2 A cross-sectional view of another example of a cryogen source rod sensor.

[0082] Figure 4 It is a diagram that can be used for Figure 2 Figures 2 and 3 provide further aspects of example refrigerant sources and refrigerant capacitive level sensors and example control circuits.

[0083] Figure 5 is a diagram illustrating aspects of signals and related processing that may occur during operation of a refrigerant capacitance level sensor of the present disclosure.

[0084] Figure 6 is a diagram illustrating an example cryoablation machine learning model that may be trained and used to operate the cryoablation device of the present disclosure.

[0085] Figure 7 is a flow chart illustrating an example method of determining a cryogen level in a cryoablation device according to some embodiments of the present disclosure.

[0086] Figure 8 is a flow chart illustrating another example method of determining a cryogen level in a cryoablation device according to some embodiments of the present disclosure.

[0087] Fig. 9 is a diagram illustrating an example computing device that may be used in one or more cryoablation systems of the present disclosure.

[0088] Fig.10 is an illustration of an example cryoablation device according to some embodiments of the present disclosure.

[0089] Fig.11 can be used for Fig.10 Illustration of an example heating assembly in a cryoablation device.

[0090] Fig.12 It may include some embodiments according to the present disclosure Fig.10 An example cryoablation system of a cryoablation device.

[0091] Fig.13 is another example cryoablation system according to some embodiments of the present disclosure.

[0092] Fig.14 is a diagram illustrating aspects of an example phantom that may be used in conjunction with some cryoablation systems of the present disclosure.

[0093] Fig.15 is an example method of maintaining pressure conditions according to some embodiments of the present disclosure.

[0094] Fig.16 is another example method of maintaining pressure conditions according to some embodiments of the present disclosure.

[0095] Fig.17 is another example method of maintaining pressure conditions according to some embodiments of the present disclosure.

[0096] Fig.18 is an illustration of an example cryoablation device that may include a refrigerant gas assembly according to some embodiments of the present disclosure.

[0097] Fig.19 is an illustration of an example cryogen gas assembly according to some embodiments of the present disclosure.

[0098] Fig. 20 are example methods of performing a purge process according to some examples of the present disclosure.

[0099] Fig.21 is another example method of performing a purge process according to some examples of the present disclosure.

[0100] Fig. 22 is an illustration of an example cryoablation system according to some embodiments of the present disclosure.

[0101] Fig.23 It is shown that the use Fig. 22 Graph of example pressure outputs that may be observed under various circumstances for a cryoablation system.

[0102] Fig.24 is a diagram illustrating aspects of an example diagnostic model according to some embodiments of the present disclosure.

[0103] Fig.25 is an example diagnostic method according to some embodiments of the present disclosure.

[0104] Fig.26 is another example diagnostic method according to some embodiments of the present disclosure.

[0105] Corresponding reference characters indicate corresponding parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0106] Example embodiments will now be described more fully with reference to the accompanying drawings.

[0107] Example embodiments are provided to make the present disclosure comprehensive and to fully convey the scope to those skilled in the art. Many specific details, such as examples of specific components, devices, and methods, are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. It will be appreciated by those skilled in the art that specific details need not be employed, that example embodiments may be embodied in a variety of different forms, and that they should not be construed as limiting the scope of the present disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.

[0108] The terms used herein are only used to describe specific example embodiments and are not intended to be limiting. As used herein, unless the context clearly states otherwise, the singular forms "one", "an" and "the" may also be intended to include plural forms. The terms "include", "comprise" and "have" are inclusive, and therefore specify the existence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the existence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups. The method steps, processes and operations described herein should not be interpreted as necessarily requiring execution in the specific order discussed or illustrated, unless clearly identified as an execution order. It should also be understood that additional or alternative steps may be adopted.

[0109] When an element or layer is referred to as being "on," "engaged to," "connected to," or "coupled to" another element or layer, it may be directly on, engaged to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on," "directly engaged to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the listed related items.

[0110] Although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts in this article, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms can only be used to distinguish an element, component, region, layer or part from another region, layer or part. Unless the context clearly indicates, the terms such as "first", "second" and other numerical terms used in this article do not imply sequence or order. Therefore, the first element, component, region, layer or part discussed below can be referred to as the second element, component, region, layer or part, without departing from the teaching of the exemplary embodiment.

[0111] For ease of description, spatially relative terms such as "inside", "outside", "below", "below", "lower", "above", "upper", etc. may be used herein to describe the relationship of an element or feature to another (multiple) element or (multiple) feature, as shown in the figure. In addition to the orientations depicted in the figures, spatially relative terms may also be intended to cover different orientations of the device in use or operation. For example, if the device in the figure is turned over, the elements described as "below" or "below" other elements or features will be oriented "above" the other elements or features. Therefore, the example term "below" can cover both above and below orientations. The device can be oriented in other ways (rotated 90 degrees or other orientations), and the spatially relative descriptors used herein can be interpreted accordingly.

[0112] A number of different embodiments are described below that describe various functions, devices, systems and methods of cryoablation systems. Some functionalities and devices are described separately, but it should be understood that the functionalities and related elements can be included in the same device to provide a cryoablation system having all the functionalities and elements described below.

[0113] The embodiments and aspects thereof described further below can be applied to various devices and methods used for cryoablation treatment. Although the following disclosure can be applied to various cryogens, such as liquid nitrogen, liquid argon, liquid helium, liquid hydrogen and liquid oxygen, the present disclosure is particularly applicable to liquid nitrogen. Liquid nitrogen presents challenges because it can be extremely difficult to work with liquid nitrogen in refrigeration systems and environments. Operating temperatures, pressures and other conditions can stress common materials and bring challenges that other cryogens may not have. Traditional and existing methods and devices may not be able to cope with the challenging properties of liquid nitrogen. In addition to low temperatures, liquid nitrogen expands dramatically when it changes from liquid to gas. In this transition, the volume of liquid nitrogen may expand 700 times. Vapor blockage is another challenge faced by liquid nitrogen systems. During such conditions, air pockets may be trapped in the cryogen flow path, thereby hindering the flow of liquid nitrogen. The devices and methods of the present disclosure improve upon existing systems to address and manage the challenges of working with liquid nitrogen.

[0114] Capacitive-based liquid level sensor

[0115] In some embodiments of the present disclosure, a cryoablation device is provided that may include a cryogen capacitance level sensor that can be operated to determine the cryogen level in a cryogen source (such as a dewar or other cryogen container). The cryogen capacitance level sensor can be positioned in the dewar or formed as a part of the dewar to allow the real-time cryogen level to be determined. Existing or traditional cryoablation systems may have sensors for determining discrete cryogen levels, but such systems are not operable to deliver real-time cryogen levels and / or are not able to determine the usage rate of the cryogen well. In addition, existing systems are not able to predict well when the cryogen source may need to be refilled and / or are unable to determine the efficiency that can be obtained by adjusting the operating parameters of the cryoablation device.

[0116] The cryoablation device of the present disclosure and the cryogen capacitance level sensor included can be used to obtain many advantages over the shortcomings of existing systems and devices. The real-time cryogen level that can be determined using the device of the present disclosure enables the actual cryogen level to be determined. The real-time cryogen level can be used to determine, for example, when the Dewar needs to be refilled. In addition, the cryogen level can be used to predict when the Dewar will need to be refilled. The cryogen device of the present disclosure can be used to use cryogen more effectively during cryoablation treatment to improve efficiency, reduce costs and increase the possibility of successful and effective treatment.

[0117] See now Figure 1 , an example cryoablation system 100 is shown. The cryoablation system 100 may include a cryoablation computing device 102, a cryocontrol 104, one or more probe information channels 106, a pump 108, a cryogen source 110, a cryogen valve 112, a cryogen supply 114, and a cryoprobe 128. The pump 108, the cryogen source 110, and the cryogen valve 112 may together form a cryogen device 200. The cryogen device 200, together with the cryogen supply 114 and the cryoprobe 128, may operate to deliver cryogen from the cryogen source 110 to the cryoprobe 128 to perform a cryoablation treatment. The cryogen (e.g., liquid nitrogen, argon, helium, or other) may be stored in a cryogen source 110 (such as a Dewar or other suitable container) and then delivered to the cryoprobe 128 via the cryogen supply 114. The cryogen may exit the cryogen supply 114 at the tip 122 of the cryoprobe 128 and cool the tip 122 of the cryoprobe 128 to a temperature at which target tissue of the patient 120 begins to freeze to form an ice ball.

[0118] The cryoprobe 128 can be positioned at or near a target tissue (e.g., a tumor) in the patient 120. In this way, the target tissue can be frozen, thereby destroying the target tissue. One or more freezing cycles can be performed to destroy the target tissue. During the freezing cycle, an ice ball 118 can be formed at the target tissue in the patient 120. It is desirable to control and form the ice ball 118 in a predetermined manner so that the ice ball 118 forms a desired size, shape, and rate so that the target tissue is frozen in the ice ball 118 for a desired period of time. It is also desirable to form the ice ball 118 at a desired size, shape, and rate so that healthy tissue or body structures near the target tissue are not harmed by the freezing cycle. For example, it may be desirable to limit the size of the ice ball 118 so that it does not form and freeze healthy tissue.

[0119] A treatment plan may be determined before performing cryoablation therapy. The treatment plan may detail and / or describe the various steps of the process and various aspects of the treatment, such as the type of equipment to be used, the positioning of the cryoprobe, the temperature of the cryoprobe, the duration of freezing (and thawing cycles), and the number of cycles. The treatment plan may also include the size, position, shape, growth rate, and duration of the ice ball. The treatment plan may be determined by a medical professional and / or other person. In some examples, after health, patient, and other information is entered into the cryoablation computing device 102 or such information is retrieved or otherwise obtained by the cryoablation computing device 102, the cryoablation computing device 102 may determine or recommend a treatment plan. The cryoablation computing device 102 may be any suitable computing device, such as a workstation, a computer, a laptop, a tablet computer, a server, and the like.

[0120] As further shown, the cryoablation system 100 can include a cryocontrol 104 that can be coupled to the cryoablation computing device 102, the cryoprobe 128, and the cryoablation device 200. The cryocontrol 104 can be any suitable controller, PLC, data acquisition unit, control unit, etc., which can perform the operations described herein. In some examples, various aspects of the cryocontrol 104, the computing device 102, and / or the cryoablation device 200 can be integrated into a cryoablation console. The dimensions of the cryoablation console can be determined to allow it to be easily moved and positioned in a treatment room close to the patient 120.

[0121] The cryocontrol 104 can be operated to obtain information about the operating conditions of the cryoablation device 200 and / or the cryoprobe 128. One type of information that the cryocontrol 104 can obtain is the cryogen level in the cryogen source 110. The cryogen can be evaporated into cryogen gas to pressurize the cryogen source 110. The increased pressure in the cryogen source 110 can allow the liquid cryogen to be pumped to the cryoprobe 128 at a very low temperature so that the cryoprobe 128 can be cooled to form an ice ball 118 at the target tissue. The pressure in the cryogen source 110 can be at or near the critical pressure of the cryogen. As will be further described below, the cryoablation device 200 can include a level sensor that can be operated to determine the level of the cryogen in the cryogen source 110. When the cryogen in the cryogen source 110 has been exhausted and / or when the cryogen has been evaporated to the extent that the cryogen in the cryogen source 110 is mainly in the form of cryogen gas, the cryogen source 110 may need to be refilled with liquid cryogen. The ablation procedure may need to be paused while the cryogen source 110 is refilled. The cryocontrol 104 may be coupled to the inlet valve 112 and the pump 108 to control the flow of cryogen to the cryoprobe 128.

[0122] For example, the cryogen dewar can hold about 25 to 50 liters of liquid nitrogen. This example dewar can be used to perform multiple cryoablation treatments ranging from about 5 treatments to about 8 treatments. When the dewar reaches a predetermined liquid level, the dewar can be refilled. The predetermined liquid level can correspond to an appropriate safety factor to allow at least one cryoablation treatment to be performed. In one example, the predetermined liquid level can be about 10% of the total volume of the dewar. In other examples, the predetermined liquid level can correspond to other amounts of liquid cryogen.

[0123] The freeze control 104 can be coupled to a cryogen liquid sensor in the cryogen source 110. The freeze control 104 can obtain liquid level information from the cryogen liquid sensor. The freeze control 104 can then determine when the cryogen source 110 needs to be refilled and can alert the operator to the status of the liquid level in the cryogen source 110.

[0124] The cryocontrol 104 may also be operable to obtain other operational information of the cryogen device 200 and / or cryoprobe 128. Such operational information may include pump operating characteristics, cryogen flow characteristics, pressure, temperature, and other information. The cryocontrol 104 may provide the information to the cryoablation computing device 102. The cryoablation computing device 102 may then perform various operations to determine the characteristics of ice formed during cryoablation therapy, the performance of the cryoablation device 200, and / or the characteristics of the cryogen source 110.

[0125] The cryoablation computing device 102 can take actions to adjust, change, modify or otherwise control one or more operating parameters of the cryoablation system 100. In some examples, the cryoablation computing device 102 can adjust the flow of the cryogen provided to the cryoprobe 128 from the cryogen source 110. The cryoablation computing device 102 can be coupled to a pump 108. The pump 108 can be an adjustable, programmable or otherwise controllable pump. The pump 108 can allow the flow rate, flow rate, flow velocity, pressure or other characteristics of the flow of the cryogen to be modified, controlled or customized. In some examples, the pump 108 can be operated to deliver the cryogen to the cryoprobe 128 in a pulsed manner using pulse width modulation (PWM). In such an example, the pump 108 can be controlled to deliver the cryogen flow at a desired frequency, pulse width, pulse amplitude or other desired flow characteristics.

[0126] See now Figure 2 , an example cryoablation device 200 is shown. The cryoablation device 200 may be part of the cryoablation system 100 previously described. Other elements of the cryoablation system 100 are not shown. Figure 2 However, it should be understood that Figure 1 Or other elements of a cryoablation system may be included in other examples.

[0127] The cryoablation device 200 may include a dewar 202 and a cryogen rod 208. The dewar 202 may be a suitable housing for enclosing a volume of cryogen, such as liquid nitrogen. As previously described, when the cryoablation device 200 operates to deliver pressurized liquid cryogen to the cryoprobe via the cryogen supply 210, the cryogen may separate into liquid cryogen 204 and cryogen gas 206.

[0128] The cryogen rod 208 can operate as a cryogen level sensor and a conduit for liquid cryogen. Figure 2 202, but the pump 108 can be positioned at or near the end of the cryogen rod 208 and move the liquid cryogen 204 from the bottom of the dewar 202 to the cryogen supply 210. The cryogen rod 208 can form a cryogen level capacitance sensor. The level of the liquid cryogen 204 in the dewar 202 can be determined using the measured or determined capacitance of the cryogen rod 208.

[0129] The cryocontrol 104 can be coupled to the cryogen rod 208 via a first control line 210 and a second control line 212. In other examples, the cryocontrol 104 can be coupled to more than two control lines 210 or 212. The cryogen rod 208 can include a first capacitor surface and a second capacitor surface separated by a dielectric (such as a cryogen in a liquid or gas phase). The cryocontrol 104 can be operated to alternately charge and discharge the first capacitor surface and the second capacitor surface of the cryogen rod 208. The cryocontrol 104 can also measure various aspects of the charging and discharging process, such as measuring current and voltage. The cryocontrol 104 and / or the cryoablation computing device 102 can determine the level of the liquid cryogen 204 in the Dewar flask by determining the capacitance of the cryogen rod 208.

[0130] The cryocontrol 104 and / or cryoablation computing device 102 can determine the level of the liquid cryogen 204 because the total capacitance (C) of the cryogen rod 208 varies according to the capacitance (C1) of the portion of the cryogen rod covered by the liquid cryogen rod and the capacitance (C2) of the portion of the cryogen rod covered by the gaseous cryogen rod. The cryogen rod acts as a dielectric of a capacitor, which is positioned between the first capacitor surface and the second capacitor surface of the cryogen rod 208. Since the cryogen rod is in different phases, the capacitance of the cryogen rod 208 is different between the two different portions. The cryocontrol 104 and / or cryoablation computing device 102 can use this difference to determine the level of the liquid cryogen 204 in the Dewar flask 202.

[0131] The relationship between the total capacitance (C), the gaseous portion capacitance (C1), and the liquid portion capacitance (C2) can be described by Equation 1: C = C1 + C2. In addition, the capacitance (C) can be characterized by Equation 2: C = ε r *ε0*A / D, where ε r, ε0 is the ratio of the contribution of the liquid cryogen material to the capacitance, A is the equivalent area of ​​the capacitance rod surface / plate, and D is the equivalent distance between the capacitance rod surface / plate. The total capacitance that can be measured is the integrated capacitance and combined value of the two partial capacitances C1 and C2, which corresponds to the liquid nitrogen partial capacitance plus the gaseous nitrogen partial capacitance (for systems using nitrogen as a cryogen). By using the total capacitance value, the user, software, and computing equipment can determine the ratio between C1 and C2, which can be directly related to the material ratio between the liquid cryogen and the gaseous nitrogen. Some experimental or clinical data can be used to determine the relationship between the liquid level in the Dewar flask and the capacitance. For example, the total capacitance value can be measured when the Dewar flask is filled with gaseous cryogen and filled with liquid cryogen. The system can be calibrated to determine the relationship between the total capacitance and the liquid level in the Dewar flask by measuring the total capacitance. Then, the computing equipment can be configured to calculate or determine the ratio of C1 to C2 and then determine the level of liquid nitrogen in the Dewar flask. For a fixed size Dewar vessel, a capacitance curve (ie, the relationship between total capacitance and liquid level) can be determined prior to operation of the system to relate the total capacitance to the cryogen level.

[0132] In some examples, for different ratios and / or different levels of liquid cryogen and gaseous cryogen, experimental and / or operational data collected during operation of the cryoablation device 200 can be used to map the capacitance of the cryogen rod 208. Such information can be obtained and stored in a database or other repository accessible to the cryocontrol 104 and / or the cryoablation computing device 102. In other examples, such experimental and / or operational data can be used to determine an algorithm, model, or other suitable relationship to provide an accurate mapping between the level of liquid cryogen and the capacitance of the cryogen rod 208.

[0133] It should be understood that the cryocontrol 104 and / or cryoablation computing device 102 may obtain other information that can be used to determine the capacitance of the cryogen rod 208. Other information may act and / or affect the capacitance of the cryogen rod 208. Information such as the temperature and / or pressure of the cryogen in the dewar can be obtained by the cryocontrol 104 and / or cryoablation computing device 102 from a sensor 220 that can be positioned on the cryogen rod 208. Although not shown, the sensor can be positioned at other locations in the dewar. The sensor 220 may include a temperature sensor such as a thermocouple, a thermistor, etc. The sensor 220 may include a pressure transducer, a thin film pressure sensor, a piezoelectric pressure sensor, etc. The temperature and / or pressure information can be used, for example, to calibrate, adjust, and / or establish a highly accurate mapping between the capacitance of the cryogen rod 208 and the level of the liquid cryogen in the dewar 202. This accuracy can provide an accuracy within ±0.5% for the level of the liquid cryogen in the dewar 202. For capacitance measurement and calculation, there are several factors that may affect the capacitance, such as the material inside the capacitor, the displacement and size of the capacitor, etc. Some other factors may also change the capacitance, such as the temperature and pressure around the capacitor. For example, a higher pressure of the gaseous cryogen will result in a high density of the gas, which may increase the capacitance. Temperature may also cause changes in capacitance. The sensor used in the device can be a variety of suitable mechanical transducers capable of measuring the pressure of the gaseous cryogen, such as a micro-electromechanical (MEM) gas pressure sensor. The temperature sensor can be a thermistor or a thermocouple, such as a T-type, whose temperature sensor can have an accuracy of + / -3°C, or an Omega PR-10E-3-100-1 / 8-6 can be used in the device.

[0134] As described above, the cryogen rod 208 may include a first structure that operates as a first capacitor surface of a capacitor and a second structure that operates as a second capacitor surface. The cryogen rod 208 may have various suitable structures to perform this function. Figure 3A , an example cryogen rod 302 is shown. In this example, the cryogen rod 302 can be formed by an outer tube 304, which is separated from an inner tube 306 by a gap 308. The inner tube 306 and the outer tube 304 can be concentrically aligned along a common axis, wherein the inner tube 306 is positioned at the center of the outer tube 304. In this example, the gap 308 can form an annular volume extending longitudinally along the cryogen rod 302. When liquid cryogen is pumped from the dewar 202 to the cryoprobe 128, the cryogen can move through the gap 308. In this example, the inner tube 306 can form a first capacitor surface, and the outer tube 304 can form a second capacitor surface.

[0135] Now go to Figure 3B, another example cryogen rod 312 is shown. In this example, the cryogen rod 312 includes an outer tube 314 and an inner tube 316 separated by a gap 318. In this example, the outer tube 314 and the inner tube 316 can be axially aligned similar to the previously described cryogen rod 302. In this example, the inner tube 316 can form a first capacitor surface, and the outer tube 314 can form a second capacitor surface.

[0136] In other examples, the dewar 202 may include other structures that can be used as a capacitive liquid level sensor. The dewar 202 may include a pair of elongated plates extending from the top of the dewar to the bottom. In another example, the inner surface or shell of the dewar may be used as a first capacitor surface, and the outer surface of the cryogen rod 208 may be used as a second capacitor surface. In yet other examples, other surfaces of other pipes, insulators, heaters, etc. may be used to form one or more capacitor plates in the dewar 202.

[0137] Now go to Figure 4 , another example cryoablation device 400 is shown. The cryoablation device 400 can operate as previously described using the capacitance of the cryogen rod 208 to determine the level of the liquid cryogen 204 in the Dewar 202. In this example, various aspects of the control circuit 402 and the cryocontrol 104 are shown. The control circuit 402 may include one or more operational amplifiers, switches, resistors, and control lines that couple the cryocontrol 104 to the cryogen rod 208 and allow the cryocontrol to charge and discharge the cryogen rod 208 and determine the capacitance of the cryogen rod 208.

[0138] The control circuit 402 can be coupled to the freezer control 104. In this example, the freezer control 104 can include a capacitance module 404, a central control and communication module 408, a source level indicator module 410, and an operation feedback module 412. Each module can be implemented as a set of executable instructions to perform the functions described below. Each module can also include Fig. 9 , memory or other elements shown in , to achieve functionality. In other examples, the modules may share hardware components (such as Fig. 9 those described in ).

[0139] The capacitance module 404 can be coupled to switches, variable resistors, etc. of the control circuit 402 to allow the cryogen rod 208 to be charged, discharged, and various parameters, such as current and voltage, to be measured. Such charging, discharging, and measurements can be collected at a predetermined frequency or rhythm to allow continuous or semi-continuous measurement of capacitance during operation of the cryoablation device 400. The capacitance module 404 can be coupled to a central control and communication module 408. The central control and communication module 408 can store the information provided by the capacitance module 404 and / or can provide the information to other elements of the cryoablation device 400.

[0140] The central control and communication module 408 may also be coupled to an analog-to-digital (A2D) converter 406. The A2D converter 406 may provide current and / or voltage information in the form of a digital signal to the central control and communication module 408 for further use. The digital signal may also be conditioned, filtered, and / or processed to increase the signal-to-noise ratio.

[0141] The cryocontrol 104 may also include a source level indicator module 410. The source level indicator module 410 may be operable to determine the level of the dewar 202. The source level indicator module 410 may use algorithms, relationships, mappings, machine learning models, etc. to determine the level of the cryogen liquid in the dewar 202. The source level indicator module 410 may include or be coupled to a database, server, or other source that it may access, for example, to determine the level. In some examples, the source level indicator module 410 may use the relationships shown in Equations 1 and 2 to determine the level. In other examples, a machine learning model may be used, such as the one described below with reference to Figure 5 The source level indicator module 410 may compare the liquid level to the predetermined liquid level threshold described above. The source level indicator module 410 may send an indication, message, or other alert to the user to indicate the liquid level. For example, the liquid level may be expressed as a percentage of the total volume of the Dewar 202.

[0142] The cryocontrol 104 may also include an operational feedback module 412. The operational feedback module 412 may obtain liquid level information from the source liquid level indicator module 410. The operational feedback module 412 may also obtain pressure, temperature, flow rate, flow rate, and other operational information from various sensors or other information sources. The operational feedback module 412 may be coupled to the Dewar 202 or other elements in the cryogen source. The operational feedback module 412 may control or cause the operational condition of the cryoablation device 200 to change. For example, the operational feedback module 412 may start, change, or stop the flow of cryogen. For example, the operational feedback module 412 may change the operational condition to improve the efficiency of the cryoablation device.

[0143] See now Figure 5, shows an example operating curve of the cryoablation device 200. The charging signal 502 shows an example signal that can be delivered to the cryogen rod 208. The cryocontrol 104 can deliver the charging signal 502 to the cryogen rod 208 via the control circuit 402. The charging signal 502 can deliver a charging current to the capacitor surface of the cryogen rod 208 to charge the capacitor surface. The charging voltage signal 504 shows an example charging voltage output to the cryogen rod 208. As can be seen, the voltage signal 504 shows an increase in voltage between the capacitor surfaces of the cryogen rod. At a predetermined frequency, the capacitor surface of the cryogen is repeatedly charged and discharged.

[0144] Voltage signal 504 can be converted to digital signal 506. Digital signal 506 can be used to determine capacitance, and thus fluid level, as previously described. Fluid level signal 508 can be determined from digital signal 506. Fluid level signal 508 can correspond to the cryogen level in dewar 202. Fluid level signal 508 can indicate a drop in fluid level in the dewar during operation of cryoablation device 200.

[0145] The machine learning model can be used to determine the relationship between the operating characteristics of the cryoablation device 200 and the performance of the cryoablation device 200. The machine learning model 600 can be used to determine various performance aspects 606 of the cryoablation device 200, for example. In some examples, the machine learning model 600 can be trained using experimental, laboratory or historical data from simulated or actual cryoablation treatments. The machine learning model can include an input 602, which can include various operating characteristics of the cryoablation device 200. The input 602 can include, for example, the capacitance of the cryogen rod 208. In other examples, other capacitances can also or alternatively be used as input 602. The input 602 can also include other operating information, such as temperature, pressure, flow, pump force, pump displacement, etc. The input 602 can also include various characteristics of the cryoablation device 200. Such characteristics can include the number, type, temperature, pattern or mode of ablation probes. The input 602 can also include patient characteristics, such as blood pressure, respiration, heart rate, etc.

[0146] The input 602 may then be processed by one or more layers 604 of a machine learning model. The layers 604 may include algorithms, formulas, objective functions, etc., that process the data in the input 602 to determine relationships, patterns, or other information from the input 602. The layers 604 may process the data from the input 602 using linear regression, decision trees, random forest models, etc. Various proprietary or open source models may be used to process the input 602.

[0147] In the example shown, the machine learning model 600 can use deep learning, which uses one or more hidden layers 604 to determine the relationship between the inputs 602. The machine learning model 600 can be used to determine an output 606, such as the level of a cryogen. The machine learning model can also be used to determine optimized operating settings or parameters that can be used in various situations or for a specific treatment. The output 606 can then be used to determine various operating settings or actions 608. The operating settings or actions 608 may include an early warning indicator for the cryogen level. The operating settings or actions 608 may also include recommended cryogen usage. The operating settings or actions 608 can be used to improve the efficiency and effectiveness of cryoablation treatment.

[0148] Now go to Figure 7 , an example method 700 of operating a cryoablation device is shown. The method 700 can be performed using one of the devices described in the present disclosure. In other examples, the method 700 can be performed by other devices. For illustrative purposes, the method 700 is described below with reference to the cryoablation system 100 and / or the cryoablation device 200. However, it should be understood that the method 700 can be performed using other devices or variations of the system 100 and the device 200.

[0149] The method 700 may begin at step 702. At step 702, the cryocontrol 104 may start or initialize the cryoablation device 200. Such initialization or startup may include starting various modules of the cryocontrol 104 and / or testing various systems of the cryoablation device 200 to ensure that the systems are functioning properly and can be connected to exchange or access information as needed during the method 700.

[0150] At step 704, the cryocontrol 104 may begin obtaining operational information. The operational information may include data or information about the cryogen in the dewar 202, such as temperature, pressure, and flow information. The cryocontrol 104 may obtain information from various sensors that may be included in the cryoablation device 200 and the cryoprobe 128. Such information may be compared to a preferred operational system that may be indicated in a treatment plan or clinical procedure.

[0151] At step 706, the cryocontrol 104 can adjust, tune and / or set various operating parameters of the cryoablation device 200 to the desired settings or parameters. The cryocontrol 104 can start the heater, vacuum pump, cryogen pump, etc. to start the cryoablation cycle. When the cryogen reaches the desired temperature and / or pressure required to achieve the desired cryoablation cycle, the flow of the cryogen can be started. For example, the settings and / or treatment plan can define the desired size of the ice ball based on the size of the target tissue. This information in the treatment plan can correspond to the desired temperature and flow of the cryogen from the dewar 202 to the cryoprobe 128.

[0152] At step 708, the cryocontrol 104 can obtain the Dewar capacitance and cryogen information. The Dewar capacitance can be information obtained from the cryogen rod 208, as described above. The cryocontrol 104 can charge and discharge the cryogen rod 208 using the control circuit 402. During this charging and discharging process, the cryocontrol can obtain the voltage and current of the signal in the control circuit 402. Other operating information of the Dewar can also be obtained, such as the temperature, pressure, and flow rate of the cryogen.

[0153] During the cryoablation cycle, the cryocontrol 104 can continuously or semi-continuously perform a cycle of steps 710, 704, 706, and 708. At step 710, the information obtained at steps 704 and / or 706 can be used to adjust the operating parameters of the cryoablation device 200 to optimize the cryoablation cycle. For example, the cryocontrol 104 can adjust the parameters of the heater, vacuum pump, cryogen pump, etc. to achieve the cryoablation conditions that can be defined in the treatment plan or clinical procedure. This step cycle can be performed until the cryoablation cycle is completed.

[0154] While this cyclic and continuous monitoring and controlled adjustment can be performed, the freezing control 104 can perform step 712. At step 712, the freezing control 104 can determine the frozen liquid level in the Dewar 202. The freezing control 104 can determine the liquid level based on the Dewar capacitance information obtained at step 708. In various implementations of the present disclosure, the freezing control 708 can use equations 1 and / or 2, other algorithms and / or machine learning models. In one example, the freezing control 104 can determine the frozen liquid level based on the capacitance of the cryogen rod 208. Step 712 can be determined continuously during the cryoablation cycle. Since the cryogen rod 208 is an element in the Dewar 202, using the cryogen rod 208 as a liquid level sensor enables any liquid level of the liquid cryogen in the Dewar 202 to be determined. In existing systems, there may be multiple sensors at discrete locations within the Dewar, but such existing systems can only determine discrete liquid levels at each discrete sensor location. The information that can be obtained from such existing systems is limited by the number of sensors placed in the Dewar. The capacitance-based liquid level sensor of the present disclosure (eg, cryogen rod 208 ) allows for continuous measurement at any liquid level in the Dewar 202 .

[0155] At step 714, the cryocontrol 104 may determine whether the Dewar flask liquid level is within a predetermined liquid level range. In other examples, the cryocontrol 104 may determine whether the cryolevel is below a predetermined liquid level threshold. In the example shown, the cryocontrol 104 may determine whether the cryolevel is within a range of 15% to 100% of the volume of the Dewar flask 202. In other examples, other predetermined liquid level ranges may be used. The predetermined liquid level range and / or predetermined liquid level threshold may be determined by a treatment plan, a clinical procedure, and may be input to the cryocontrol 104 by a user or a technician. If the cryolevel is within the predetermined liquid level range, the method 700 may proceed to step 716. If the cryolevel is not within the predetermined liquid level range, the method 700 may move to step 718.

[0156] At step 716, the cryocontrol can adjust the operating parameters to achieve the preferred cryoablation state. In a similar manner to the adjustment at step 710, the cryocontrol can adjust the flow of the cryogen based on the measured cryolevel determined at step 712. For example, such an adjustment can be made to optimize the amount of liquid cryogen remaining in the Dewar 202. The cryocontrol 104 can also adjust or change various pressures, temperatures, or other characteristics of the cryoablation device 200 by causing the setting or operation of the heater, vacuum pump, cryogen pump, or valve to be modified. After step 716, the method can return to step 704 to re-execute steps 704 to 716. Therefore, the cryocontrol 104 can continuously monitor the cryolevel in the Dewar 202 and adjust the various operating parameters of the cryoablation device 200 as needed to achieve the desired clinical results.

[0157] At step 718, the cryocontrol determines that the level of the cryogen is not within a predetermined level range. The cryocontrol 104 can then determine whether the amount of cryogen remaining in the Dewar is sufficient to complete the current cryoablation procedure. For example, if the procedure is about to be completed, the amount of liquid cryogen remaining may be sufficient to complete the procedure. The cryocontrol 104 can determine whether the remaining liquid cryogen is sufficient based on the usage rate recorded by the cryocontrol 104 during the current or historical cryoablation cycle. If the cryocontrol 104 determines that the remaining liquid cryogen is sufficient to complete the cryoablation procedure, the method 700 moves to step 716. The cryocontrol 104 can perform step 716 described above and continue to operate the cryoablation device 200 to perform a cryoablation cycle.

[0158] If the cryocontrol 104 determines that the amount of liquid cryogen remaining in the dewar 202 is insufficient to complete the cryoablation procedure, the method moves to step 720. At step 720, the cryocontrol 104 may indicate that refilling of the dewar 202 is required. The cryocontrol 104 may alert the user of the cryoablation device 200 that refilling is required by sending an alarm (such as an audible signal, a text message, an email, a visible message, a warning light, or other indicator). In some examples, the refill warning may be indicated on a screen or display coupled to the cryocontrol 104. After displaying or otherwise sending a refill indicator, the method 700 may move to step 722.

[0159] At step 722, the cryocontrol 104 may determine whether the dewar 202 has been refilled with liquid cryogen. The cryocontrol 104 may determine whether the dewar 202 has been refilled by measuring the liquid level of the dewar 202, as previously described. In some examples, the cryocontrol 104 may use a cryogen rod 208 or other capacitance-based liquid level sensor. In other examples, the cryocontrol 104 may use a temperature sensor, a pressure sensor, or other liquid level sensor to determine whether the dewar 202 has been refilled. If the cryocontrol 104 determines that the dewar 202 has been refilled, the method 700 may move to step 724. If the cryocontrol determines that the dewar has not been refilled, the method may move to step 726.

[0160] At step 724, the cryocontrol 104 may reinitialize and / or restart the cryoablation device 200. The cryocontrol 104 may need to readjust and / or activate elements of the cryoablation device 200 to allow a new cryoablation cycle to begin. After step 724, the method may return to step 710, and the previously described states may be re-executed to perform a cryoablation cycle.

[0161] At step 726, the method 700 can end. The cryocontrol 104 can determine that the dewar 202 has not been refilled. If the dewar 202 has not been refilled, the cryocontrol 104 can end the method after a certain time. In other examples, the user can indicate or input that the cryocontrol 104 will not perform a refill. In such an example, the cryocontrol 104 can stop further action of the cryoablation device 200, and the method 700 can end.

[0162] refer to Figure 8Another example method 800 for performing a cryoablation cycle is provided. The method 800 can be performed using one of the devices described in the present disclosure. In other examples, the method 800 can be performed by other devices. For illustrative purposes, the method 800 is described below with reference to the cryoablation system 100 and / or the cryoablation device 200. However, it should be understood that the method 800 can be performed using other devices or variations of the system 100 and the device 200.

[0163] Method 800 may begin at step 802. At step 802, cryocontrol 104 may obtain operating parameters of cryoablation device 200. The operating parameters may include pressure, temperature, and flow information of the cryogen in dewar 202. Various sensors that may be positioned in dewar 202 may be used to obtain the operating parameters.

[0164] At step 804, the cryocontrol 104 can obtain the total dewar capacitance. The cryocontrol 104 can use a capacitance-based liquid level sensor (such as a cryogen rod 208) to determine the dewar capacitance. The cryocontrol 104 can obtain the dewar capacitance by charging and discharging the capacitor in the dewar 202. The capacitor can extend continuously from the top of the dewar 202 to the bottom of the dewar 202. The capacitance-based liquid level sensor can be implemented as a cryogen supply tube in the dewar 202, a combination of a cryogen supply tube and an inner surface of the dewar 202, or other capacitor surfaces in the dewar 202. In one example, the capacitance-based liquid level sensor is a cryogen rod 208 extending from the bottom of the dewar 202, which is fluidically connected to the supply tube and the cryoprobe 128.

[0165] At step 806, the cryocontrol 104 can determine the cryogen level in the dewar 202 based on the capacitance of the capacitance-based level sensor in the dewar 202. The cryocontrol 104 can determine the cryogen level based on the cryogen and / or the operating characteristics of the dewar 202 and the capacitance. In addition to capacitance, the temperature, pressure, and flow of the cryogen 204 in the dewar 202 can also be used to determine the cryogen level. In some examples, a machine learning model can be used to determine the cryogen level. The machine learning model can be a trained model that is trained using experimental and / or historical cryoablation data.

[0166] At step 808, if the cryogen level is below a predetermined level, the cryocontrol 104 may send a cryogen level warning. The predetermined level may correspond to a cryogen level that will allow the current cryogen cycle to be executed to completion. The cryocontrol 104 may send a message, an audible warning, a display alarm message, or other warning, as described above. The warning may be sent to the user's portable device and / or the display of the cryoablation device 200 via a communication network.

[0167] See now Fig. 9 , an example computing device 900 is shown. The cryoablation system 100 may include one or more computing devices 900. For example, the cryoablation computing device 102 and / or the cryocontrol 104 may have Fig. 9 The methods of the present disclosure, such as method 700 or 800 , may be performed by computing device 900 , or the steps of such methods may be performed by computing device 900 .

[0168] As shown, computing device 900 may include one or more processors 902, working memory 904, one or more input / output devices 906, instruction memory 908, transceiver 912, one or more communication ports 914, and display 916, all of which are operably coupled to one or more data buses 910. Data bus 910 allows communication between various devices. Data bus 910 may include wired or wireless communication channels.

[0169] The processor 902 may include one or more different processors, each having one or more cores. Each different processor may have the same or different structures. The processor 902 may include one or more central processing units (CPUs), one or more graphics processing units (GPUs), application specific integrated circuits (ASICs), digital signal processors (DSPs), etc.

[0170] The processor 902 may be configured to embody a specific function or operation by executing a code embodying the function or operation stored in the instruction memory 908. For example, the processor 902 may be configured to perform one or more of any functions, steps, methods or operations disclosed herein.

[0171] The instruction memory 908 may store instructions that may be accessed (e.g., read) and executed by the processor 902. For example, the instruction memory 908 may be a non-transitory, computer-readable storage medium such as a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), flash memory, a removable disk, a CD-ROM, any non-volatile memory, or any other suitable memory.

[0172] The processor 902 may store data in the working memory 904 and may also read data from the working memory 904. For example, the processor 902 may store a set of working instructions (such as instructions loaded from the instruction memory 908) in the working memory 904. The processor 902 may also use the working memory 904 to store dynamic data created during operation of the cryoablation computing device 102. The working memory 904 may be a random access memory (RAM), such as a static random access memory (SRAM) or a dynamic random access memory (DRAM), or any other suitable memory.

[0173] The input-output device 906 may include any suitable device that allows data input or output. For example, the input-output device 906 may include one or more of a keyboard, a touchpad, a mouse, a stylus, a touch screen, physical buttons, a speaker, a microphone, or any other suitable input or output device.

[0174] The communication port 914 may include, for example, a serial port, such as a universal asynchronous receiver / transmitter (UART) connection, a universal serial bus (USB) connection, or any other suitable communication port or connection. In some examples, the communication port 914 allows executable instructions to be programmed in the instruction memory 908. In some examples, the communication port 914 allows data to be transferred (e.g., uploaded or downloaded), such as refrigerant level data, etc.

[0175] The display 916 can display a user interface 918. The user interface 918 can enable user interaction with the cryoablation computing device 102. For example, the user interface 818 can be a user interface that allows an operator to interact, communicate, control, and / or modify different messages, settings, or features that may be presented or otherwise displayed to the user. The user interface 918 may include a slider, dialog box, or other input field that allows the user to control, communicate, or modify settings, limitations, or inputs for cryoablation therapy. In addition, the user interface 918 may include one or more input fields or controls that allow the user to modify or control optional features or customizable aspects of the cryoablation computing device 102 and / or operating parameters of the cryoablation system 100. In some examples, the user can interact with the user interface 918 by engaging the input-output device 906. In some examples, the display 916 can be a touch screen, wherein the user interface 918 is displayed on the touch screen. In other examples, the display 916 can be a computer display that can be interacted with using a mouse or keyboard.

[0176] The transceiver 912 allows for communication with a network. In some examples, the transceiver 912 is selected based on the type of communication network in which the cryoablation computing device 102 will operate. The processor(s) 902 are operable to receive data from or send data to a network, such as a wired or wireless network coupling elements of the cryoablation system 100.

[0177] Adaptive pressure control of refrigerant

[0178] In some embodiments of the present disclosure, a cryoablation device is provided that implements adaptive pressure control of cryogen. The adaptive pressure control functionality can be operated to measure and control cryogen pressure in multiple locations of cryogen storage, supply, and flow from a Dewar or other storage container to the cryoprobe. The pressure can be measured and controlled to maintain the desired pressure and / or temperature of the cryogen at various locations in the cryoablation device. The pressure control can be operated to more efficiently and effectively utilize the cryogen during the cryoablation procedure to reduce costs, improve efficiency, and / or improve treatment effectiveness.

[0179] In some examples, the cryoablation device may include an intelligent pressure control, a liquid cryogen heating assembly, a high pressure pump motor assembly, and a dewar cap assembly. The cryoablation device may be operated by an intelligent pressure control to independently control the pressure and / or temperature of the cryogen at various locations in the cryoablation device, such as in the dewar, in the cryogen supply conduit, and / or at the cryoprobe. Independent control may allow cryogen to be used more efficiently than existing systems, which may use gravity or a separate pump to control pressure and move cryogen to the cryoprobe.

[0180] In some examples, the cryoablation devices and methods of the present disclosure can utilize at least two pumps (which may include a low-pressure pump and a high-pressure pump) to operate independently to control the pressure and flow of the cryogen through the system. The pressure control system can utilize a closed-loop system, whereby operational information can be obtained, which is then used to continuously control the cryogen pressure and flow, thereby operating the cryoablation device more efficiently and effectively than existing systems. The cryogen used in the system may include various suitable cryogens, such as nitrogen, helium, argon, and the like. The following disclosure may include a description of liquid nitrogen operating pressures, but it should be understood that other cryogens may be used.

[0181] See now Fig.10 , an example cryoablation device 1000 is shown. The cryoablation device 1000 can be used as a cryoablation system (such as cryoablation system 100 ( Figure 1 The cryoablation device 1000 may be a Figure 1An alternative example of a cryoablation device 116 is shown in FIG. The cryoablation device 1000 can be coupled to a cryoprobe 128 to deliver a cryogen for cryoablation therapy. The cryoablation device 1000 can be coupled to a pressure control ( Fig.10 (not shown), the pressure control can obtain information such as pressure, temperature and / or flow information from the cryoablation device 1000 and adjust, change or modify the operation of the cryoablation device 1000.

[0182] The cryoablation device 1000 may include a dewar 1002, a supply tube 1006, one or more sensors 1008, a heating assembly 1012, a high pressure pump assembly 1014, a valve assembly 1016, a cable 1018 and a cap assembly 1020. The dewar 1002 may be configured as previously described to include a housing that may be insulated, double-walled, vacuum insulated or of similar material. The dewar 1002 may define an internal volume to accommodate a volume of cryogen, such as liquid nitrogen. The cryogen may be deposited into the dewar 1002 as a liquid cryogen 1004. The liquid cryogen may become cryogen vapor 1010 in the internal volume of the dewar 1002. In one example, the liquid cryogen 1004 may be pressurized to a desired pressure and / or temperature before it is pumped or otherwise moved from the dewar 1002 to the cryoprobe 128. The dewar 1002 may be configured with a liquid level sensor as previously described. The liquid level sensor may, for example, be a capacitance-based liquid level sensor.

[0183] The heating assembly 1012 of the cryoablation device 1000 can include a heater, such as a resistive heater that can transfer heat to the liquid cryogen 1004. As the liquid cryogen 1004 is heated, the liquid cryogen 1004 can be converted to cryogen vapor (gas) 1010. The accumulation of cryogen vapor 1010 in the dewar 1002 can cause the pressure of the cryogen in the dewar 1002 to increase. The heating assembly 1012 can be activated to convert the liquid cryogen 1004 to cryogen vapor 1010 until a predetermined or desired pressure is reached in the dewar 1002. In this example and as will be further explained, the heating assembly 1012 can be positioned at the distal end of the supply tube 1006, which is located in the liquid cryogen 1004, near or proximate to the bottom of the dewar 1002. In other examples, the heating assembly 1012 can be located at other locations, but is preferably positioned below the liquid level of the cryogen in the dewar 1002.

[0184] The cryoablation device 1000 may also include a high pressure pump assembly 1014. In this example, the high pressure pump assembly 1014 is positioned at or toward the distal end of the supply tube 1006 at or near the heating assembly 1012. The high pressure pump assembly 1014 may be positioned above the heating assembly 1012. The high pressure pump assembly 1014 may pressurize the liquid cryogen 1004 to a high pressure level to provide the cryoprobe with high pressure liquid cryogen. In one example, the pump assembly 1014 may include an internal pressure cylinder design that is operated by the cap assembly 1020 to move and pressurize the low pressure liquid cryogen to a high pressure liquid cryogen (e.g., about 300 psi to about 600 psi).

[0185] Although not shown, the cap assembly 1020 can be coupled to a cryogen supply conduit and / or cryogen supply manifold, which can be used to connect the cryogen fluid in the dewar 1002 to one or more cryoprobes 128. The cryoprobe 128 can be inserted into or near the target tissue in the patient during cryoablation therapy. The size and capacity of the dewar 1002 and other elements of the cryoablation device 1000 can be configured to allow the appropriate volume and flow of cryogen to be supplied to the desired number of cryoprobes 128.

[0186] Sensor 1008 can be positioned at various positions inside Dewar 1002. In the example shown, multiple sensors 1008 are positioned at various vertical positions along supply tube 1006. Sensor 1008 can be positioned at various positions in liquid cryogen 1004 and cryogen vapor 1010. Sensor 1008 can also be positioned at various positions along the surface of Dewar 1002 and / or positioned on other elements that may be included in cryoablation device 1000. Sensor 1008 can be configured as a suitable sensor to provide information about the conditions in Dewar 1002 and / or the conditions of the cryogen that may be located in Dewar 1002 and / or supply tube 1006. Sensor 1008 can be coupled to a data acquisition module of a pressure control via a wired or wireless connection. In the example shown, sensor 1008 can be coupled to a pressure control via cable 1018. In other examples, other connections can be used.

[0187] Sensor 1008 can be positioned at a plurality of positions to provide information such as pressure, temperature or flow information about the cryogen in the dewar flask and the cryogen supplied to the cryoprobe. Sensor 1008 can be located at a suitable position to provide temperature and / or pressure information of the cryogen in the dewar flask 1002 that can be maintained under low pressure conditions, for example. Sensor 1008 can also be located at a suitable position to provide temperature and / or pressure information of the cryogen supplied to the cryoprobe that can be maintained or operated under high pressure conditions, for example. In some examples, sensor 1008 can be configured as a temperature-pressure sensor transducer. In other examples, other suitable pressure or temperature sensors, such as thermistors, thermocouples, piezoelectric pressure sensors, strain gauge pressure sensor positions.

[0188] The valve assembly 1016 may include one or more controllable valves that can be used to control the pressure of the cryogen in the Dewar 1002. The valve assembly 1016 may include a manual or electronically actuated valve that can be used to discharge the cryogen into the surrounding environment. The valve assembly 1016 may be coupled to a pressure control that can open or close the valve of the valve assembly 1016 in response to a pressure measurement obtained from the sensor 1008.

[0189] The cap assembly 1020 can be positioned at or near the top of the dewar flask and can be connected to the supply tube 1006. The cap assembly 1020 can seal the connection location of the supply tube 1006 with the dewar flask 1002. The cap assembly 1020 can also seal the location where the cable 1018 can enter the dewar flask 1002 and allow the cable 1018 to be coupled to the various elements of the cryoablation device 1000. The cap assembly can also include one or more sensors 1008 to provide information about the conditions in the dewar flask 1002 and / or in the supply tube 1006. The cap assembly 1020 can also include a pump motor and a gear box that operates to move the barrel in the pump assembly 1014. The pump motor can be controlled to rotate at a desired speed, such as 500 revolutions per minute (rpm). The pump motor can be coupled to the high pressure pump assembly 1014 described previously.

[0190] As previously described, the cable 1018 can be coupled to various components of the cryoablation device 1000 to provide control signals that can cause the components to operate to achieve desired operating conditions (e.g., temperature and pressure) in the Dewar 1002. The cable 1018 can include a bundle of wires that can be connected to, for example, the sensor 1008, the heating assembly 1012, the high pressure pump assembly 1014, the valve assembly 1016, etc. The cable 1018 can also be coupled to a pressure control that can obtain operating information and then control the operation of the cryoablation device to achieve desired operating conditions.

[0191] See now Fig.11, an example heating assembly 1012 is shown. The heating assembly 1012 can be positioned at or near the distal end 1112 of the supply tube 1006. The heating assembly 1012 can include a heater 1102, one or more sensors 1104, and a bubble barrier 1106. The heater 1102 can include one or more heating elements that can extend into the liquid cryogen 1004. The heater 1102 can be a resistive heater, a laser heater, an infrared heater, or other heaters. Other heaters can include radiant heaters, wireless transmission heaters, microwave heaters, and RF heaters. The heater 1102 can be positioned within a heating boundary 1114 defined by the bubble barrier 1106. The heating boundary 1114 can be a volume surrounding the heater 1102. The heating boundary 1114 can be separated from the internal volume of the dewar 1002 by the bubble barrier 1106. The bubble barrier 1106 can be a wall that can surround the heater 1102. In the example shown, the bubble barrier 1106 can have a cylindrical shape to define a cylindrically shaped heating boundary 1114. The bubble barrier 1106 may be open at its top and bottom to allow liquid cryogen 1004 to enter the heating boundary 1114 and allow cryogen vapor to leave the heating boundary 1114. The bubble barrier 1106 may be made of, for example, double-walled or insulated stainless steel and formed as a vertically oriented tubular member with its axis aligned with the axis of the supply tube 1006. Alternatively, the bubble barrier 1106 may be made of a non-thermally conductive material. In some examples, the bubble barrier 1106 may be formed of rubber, plastic, polymer, or composite material. In other examples, the bubble barrier 1106 may have other shapes or configurations.

[0192] When the heater 1102 is activated, the liquid cryogen 1004 located inside the bubble barrier 1106 can begin to be converted into cryogen vapor. The cryogen vapor can form into vapor bubbles 1110. The vapor bubbles 1110 can travel upward after formation and then reach the surface of the liquid cryogen 1004. The bubble barrier 1106 keeps the cryogen vapor locally in the heating boundary 1114 within the bubble barrier 1106. In other systems without the heating boundary 1114, the cryogen vapor bubbles 1110 can travel unrestricted and can move in all directions throughout the Dewar 1002. The cryogen vapor bubbles 1110 are confined to the heating boundary 1114, allowing the area of ​​the liquid cryogen 1004 located in the bubble barrier 1116 to reach a different local pressure than the pressure of the liquid cryogen that may be located outside the bubble barrier 1116. This local pressure difference can allow the pressure of the liquid cryogen 1004 to be greater than the pressure of the liquid cryogen 1004 located outside the bubble barrier 1116.

[0193] The heating assembly 1012 with the bubble barrier 1106 can allow the liquid cryogen 1004 to reach the desired pressure condition faster than other systems that do not include this structure. In other systems, the heater can heat the liquid cryogen, but the liquid cryogen may not be moved to the cryoprobe until the entire Dewar 1002 is pressurized to the desired pressure condition. In the system and device of the present disclosure, the liquid cryogen 1004 can be locally pressurized to the desired pressure inside the bubble barrier 1116, rather than pressurizing the entire Dewar 1002 to the desired pressure condition. The system and device of the present disclosure can allow the cryoablation cycle to be performed faster than other systems. In the system where the entire Dewar 1002 needs to be pressurized to the desired pressure condition, this pressure condition can be achieved within a time period that may be within the range of about 45 minutes to about 60 minutes. The system and device of the present disclosure can make the cryogen reach the desired pressure condition in about 10 to about 15 minutes. In other examples, the system and device of the present disclosure can make the cryogen reach the desired pressure condition in less than about 10 minutes.

[0194] As used in the present disclosure, the low pressure condition of the cryoablation device 1000 can refer to the condition of the cryogen in the Dewar flask maintained before the cryogen is moved to the cryoprobe. The low pressure condition can correspond to a pressure in the range of about 10 pounds per square inch (psi) to about 15 psi. It has been determined that the low pressure condition can cause the liquid cryogen to be effectively converted to a high pressure condition. The low pressure condition can be maintained in the Dewar flask 1002, as will be further described below. The heating assembly 1012 can use a closed loop process to maintain the pressure in the Dewar flask 1002 at a low pressure condition. The high pressure condition can refer to a pressure higher than the low pressure condition, and can refer to the pressure of the cryogen moved from the Dewar flask 1002 to the cryoprobe to perform a cryoablation cycle. The high pressure condition can refer to a cryogen pressure sufficient to remove enough heat from the cryoprobe and surrounding tissue to form an ice ball at the distal end of the cryoprobe. The high pressure condition can correspond to a supercritical, critical or near-critical state of the liquid cryogen. The high pressure condition can correspond to a pressure in the range of about 450 psi to about 550 psi or more. The pump assembly 1014 and / or the cap assembly 1020 may be operable to increase the liquid cryogen from a low pressure condition in the dewar 1002 to a high pressure condition for use in the cryoprobe 128 .

[0195] The heating assembly 1012 may also include one or more sensors 1104. The sensors 1104 may be temperature and / or pressure sensors, such as those previously described with respect to the sensors 1008 ( Fig.10) described above. Sensor 1104 can be positioned inside bubble barrier 1106. Sensor 1104 can also be positioned at different vertical locations within heating boundary 1114. Sensor 1104 can provide temperature and / or pressure information to a pressure control, which can activate heater 1102 as needed to achieve a predetermined high pressure condition for liquid cryogen 1004 within heating boundary 1114. When such a suitable or predetermined high pressure condition is achieved, the pressure control can also activate a pump to move liquid cryogen from within bubble barrier 1106 through supply tube 1006 to the cryoprobe.

[0196] See now Fig.12 , an example cryoablation system 1200 is shown. The cryoablation system 1200 may include the cryoablation device 1000 previously described. The cryoablation device 1000 may include a heating assembly 1012, which includes a heating boundary 1114 and a heater 1102. The cryoablation device 1000 may be coupled to one or more control circuits 1204, 1206. The cryoablation device 1000 may also be coupled to a pressure control 1202. The pressure control 1202 may be configured as a computing device, a PLC, a controller, or other suitable device. The pressure control 1202 may have functionality and may be combined with the controller 104 described previously or implemented as a control 104. The pressure control 1202 may have elements of the computing device 900 described above.

[0197] The pressure control 1202 may be operable to obtain information from the cryoablation device 1000 and / or the cryoprobe 128 to determine operating parameters of the cryoablation device 1000. The pressure control 1202 may include a converter 1208, a communication module 1210, a cryogen pressure module 1212, and a heating module 1214. Each module may be implemented in various ways, such as by executable instructions, dedicated circuits, and the like.

[0198] The converter 1208 can be coupled to the control circuit 1204. The control circuit 1204 can include an amplifier or other components to provide signals or data about the operation of the cryoablation device 1000. The sensors 1008 and 1104 can be coupled to the control circuit 1204 and, in turn, to the converter 1208. The converter 1208 can be configured as an analog-to-digital (A2D) converter to provide a digital signal. The converter 1208 can be coupled to a communication module 1210. The communication module 1210 can be a transceiver, a data acquisition unit, or other suitable device or module to obtain data from the cryoablation device 1000. The communication module 1210 can be coupled to other elements of the cryoablation system 1200 using a wired or wireless connection to provide information and / or feedback about the operation of the cryoablation system 1200.

[0199] The communication module 1210 can be coupled to a pressure module 1212. The pressure module 1212 can determine various operating parameters of the cryoablation system 1200. The pressure module 1212 can determine what actions should be taken during a cryoablation procedure or treatment to achieve a desired result or outcome. In some examples, a treatment plan can be generated before a cryoablation treatment. The treatment plan can describe various details of the cryoablation treatment, such as the number or duration of cryoablation cycles, the size of the ice ball, and other aspects. The pressure module 1212 can determine the temperature, pressure, and flow rate of the cryogen, which may be desired to achieve the details described in the treatment plan. The pressure module 1212 can also determine when and how to activate specific elements of the cryoablation system 1200 to achieve the details of the treatment plan. For example, the pressure module 1212 can determine when to activate the heating assembly 1012 and how long to activate it to achieve the desired temperature and pressure of the liquid cryogen. The pressure module 121 can determine when and whether the valve assembly 1016 should be activated to release the pressure from the Dewar 1002. The pressure module 1212 can determine when and how to activate the pump assembly 1014 to achieve the temperature, pressure, and flow of cryogen to the cryoprobe 128. The pressure module 1212 can also determine other operational aspects of the cryoablation system 1000.

[0200] Pressure module 1212 may use algorithms, lookup tables, machine learning models, artificial neural networks (ANNs), regression, and other tools to determine the operation of cryoablation system 1200. If a machine learning model or ANN is used, such a model may be trained using historical or experimental data and then updated with treatment data to improve its performance. Fig.14 Describe an example machine learning model or ANN.

[0201] The pressure module 1212 can be directly or indirectly coupled to other elements of the cryoablation system 1200 to control functions and operations. As shown, the pressure module 1212 can be coupled to the heating module 1214. The heating module 1214 can activate and control the functions of the heating assembly 1012. The heating module 1214 can be coupled to the control circuit 1206. The heating module 1214 may include a suitable power supply, which can be amplified or regulated by the control circuit 1206 to provide a power signal to the heating assembly 1012. The power signal can energize the heater 1102 of the heating assembly 1012 to convert the liquid cryogen into cryogen vapor. The heating module 1214 can provide a power signal to maintain or create a desired operating condition (e.g., pressure, temperature, etc.) in the heating assembly 1012. The heating module 1214 can provide pulse width modulation (PWM), frequency, amplitude or other control.

[0202] The cryoablation system 1000 can operate to maintain a low pressure condition in the dewar 1002. The pressure module 1212 can obtain temperature and / or pressure information from the sensor 1008 in the cryoablation device 1000. The pressure module 1212 can determine that the pressure in the dewar 1002 is below the desired temperature, such as a low pressure operating condition (e.g., 10 to 15 psi). The pressure module 1212 can communicate with the heating module 1214 to activate the heating assembly 1012 to heat the liquid cryogen 1004 in the dewar 1002. The pressure module 1212 can continue to monitor the pressure in the dewar 1002 using a closed-loop feedback process to continue to heat the liquid cryogen 1004 in the dewar 1002 until the desired pressure is reached in the dewar 1002. Then, the pressure module 1212 can deactivate and modify the power signal delivered to the heating assembly 1012 to maintain the desired pressure in the dewar 1002.

[0203] Fig.13 Another example cryoablation system 1300 is provided in . Cryoablation system 1300 is similar in many respects to the previously described cryoablation system 1200. Cryoablation system 1300 may include a pressure control 1302, which includes an A2D converter 1308, a communication module 1310, a pressure module 1312, and a heating module 1314. Cryoablation system 1300 may also include control circuits 1304, 1306. These elements may have similar structures and functions as the same elements of the cryoablation system 1200 described above. For the sake of brevity, the description of these elements will not be repeated.

[0204] In the example shown, the cryoablation system 1300 may include a cryoablation system 1300 that includes at least two components to change or modify the pressure in the system. As shown, the cryoablation system 1300 may include a first component (such as a heating component 1012) and a second component (such as a pump component 1014). The two components can be controlled via a pressure control 1302 to efficiently and effectively deliver high-pressure cryogen to the cryoprobe as needed for cryoablation treatment.

[0205] The two components can be controlled and / or adjusted by pressure control unit 1302 to increase the pressure of the liquid cryogen to a high pressure condition. The high pressure condition can correspond to a critical, supercritical or near-critical pressure of the cryogen. In an example using liquid nitrogen as a cryogen, the high pressure condition can correspond to a pressure in the range of about 400psi to about 600psi. In some examples, heating assembly 1012 can be used to increase the pressure of the liquid cryogen to a first pressure range, and pump assembly 1014 can increase the pressure of the liquid cryogen from the first pressure range to a second high pressure range.

[0206] The cryoablation system 1300 may include a sensor 1320 positioned at or near the outlet of the cap assembly 1322. The sensor 1320 may be a temperature and / or pressure sensor (such as those previously described). The sensor 1320 may be configured to provide information about the pressure of the cryogen supplied to the cryoprobe 128 by the cap assembly 1322. The pressure may preferably be under high pressure conditions for performing a cryoablation cycle at the cryoprobe 128. The sensor 1320 may be configured to measure high pressure (e.g., in the range of about 400 psi to about 600 psi). In other examples, the cryoablation system 1300 may include additional sensors positioned at various locations along the cryogen supply line and / or the cryoprobe 128 to provide information about the temperature, pressure, and / or flow of the cryogen.

[0207] See now Fig.14 , illustrates an example machine learning or ANN model 1400. Model 1400 can use machine learning to determine the relationship between inputs 1402 to determine outputs 1406 and operational actions 1408. Various layers 1404 can be used to process inputs. The term model (such as model 1400) can refer to a data model created using machine learning and / or artificial intelligence. Machine learning can involve training mathematical models under supervised or unsupervised settings. Machine learning models can be trained to learn the relationship between various data groups. These models can be based on a set of algorithms that are designed to model abstractions in data by using several processing layers. The processing layer can be composed of nonlinear transformations. Machine learning models can include, for example, neural networks, convolutional neural networks, and deep neural networks. Such neural networks can be composed of multiple levels of trainable filters, transformations, projections, hashing, and pooling. These models can be used in large-scale relationship identification tasks. Models can be created using various open source and proprietary machine learning tools and / or libraries known to those skilled in the art.

[0208] In the example shown, input 1402 may include data and information, such as information obtained from Dewar sensors (including low pressure sensors and high pressure sensors). Input 1402 may also include temperature data, such as probe temperature data. Input 1402 may also include ice ball information, such as ice ball growth rate, ice ball size, and / or ice ball isotherm position. Input 1402 may also include other information, such as cryogen flow rate, volume, and the like.

[0209] Model 1400 can determine output 1406. Output 1406 can include efficiency or other treatment optimization measures. Output 1406 can also include operating parameters of the cryoablation device, such as desired pressure, and adjustments to operating parameters to improve efficiency and / or effectiveness.

[0210] Output 1406 can be used to determine an operational action 1408. The operational action 1408 can be implemented by, for example, a pressure control. The operational action 1408 can include activation or timing of the heater and / or configuration of a power signal to be delivered to the heater, including PWM, current, voltage, or other power signal characteristics. The operational action 1408 can also include cryogen pump parameters, cryogen flow parameters, and cryoablation cycle timing, duration, etc.

[0211] See now Fig.15 , a method 1500 for maintaining a low pressure condition in a Dewar is provided. The method 1500 can be performed using the cryoablation device of the present disclosure, but it should be understood that other devices can be used. For example, the cryoablation system 1200 can be used to perform the method 1500. The following description of the method 1500 describes the operations performed by the cryoablation system 1200, but it should not be interpreted as limiting the method to this particular device.

[0212] Method 1500 can be used to achieve a low pressure condition in Dewar 1002. As previously described, it has been determined that for a cryoablation device utilizing liquid nitrogen as a cryogen, a low pressure condition of about 10 psi to about 15 psi is desired. For other cryogens or other cryoablation devices, the low pressure condition may have other ranges or desired levels. This low pressure condition is ideal because it allows the other high pressure pumps of the cryoablation device to effectively pressurize the cryogen to a temperature and pressure for use in the cryoprobe 128.

[0213] At step 1502, the method 1500 can be initiated. At step 1502, the cryoablation device 1000 and the pressure control 1202 can be turned on and / or the cryogen can be filled into the dewar 1002 to a desired level. At step 1504, the pressure control 1202 can begin to obtain information from various sensors 1008. The sensors 1008 can provide, for example, temperature and pressure information of the dewar 1002.

[0214] At step 1506, the pressure control 1202 can compare the information from the sensor 1008 with the desired operating parameters. The desired operating parameters can be described in a treatment plan, an operation or a clinical procedure, or can be experimentally or clinically determined. The desired operating parameters can correspond to operating parameters that achieve a treatment outcome and / or achieve an optimized and efficient performance of the cryoablation device 1000. The desired operating parameters can be determined by an algorithm, a model, machine learning, or other methods as described above. The desired operating parameters can include a lower pressure threshold and an upper pressure threshold of the low pressure range of the Dewar 1002. The low pressure range can correspond to the desired low pressure range of the Dewar 1002, which can allow liquid cryogen to be efficiently and effectively converted to a high pressure cryogen. Therefore, it may be desirable to maintain the Dewar 1002 within a low pressure range so that the cryoablation device 1000 operates efficiently and effectively.

[0215] At step 1508, the pressure control 1202 can determine whether the dewar pressure is below the lower operating threshold defined in the desired operating parameters described above. In some examples, for an apparatus using liquid nitrogen as a cryogen, the lower operating threshold can correspond to about 10 psi. In other examples, the lower operating threshold can correspond to other pressure values. If the pressure control 1202 determines that the pressure in the dewar 1002 is below the lower operating threshold, the method can move to step 1510. If the pressure control 1202 determines that the pressure in the dewar 1002 is not below the lower operating threshold, the method 1500 can move to step 1516.

[0216] At step 1510, the pressure control 1202 can activate or turn on the heater of the heating assembly 1012. The pressure control 1202 can cause a power signal with an appropriate power level, PWM, voltage, or current to be delivered to the heater. After the heater is activated, the liquid cryogen 1004 can be converted to cryogen vapor 1010, and the pressure in the Dewar 1002 can increase.

[0217] At step 1512, the pressure control 1202 can determine whether the rate of increase of pressure in the dewar 1002 is sufficient for a cryoablation cycle. For example, if the cryoablation device 1000 has just been started, the user may want to start a cryoablation cycle as soon as possible. The pressure control 1202 may want the rate of increase of pressure to be as fast as possible. If the cryoablation process is in progress and an ice ball is forming, and / or the cryoablation cycle is almost complete, then the pressure increase may be minimal because the cycle is almost complete. These different situations may require that the rate of increase of pressure in the dewar 1002 is sufficient. If the pressure control 1202 determines that the rate of increase is sufficient, the method 1500 can return to step 1504, where it continues to obtain information from the sensor and continues to monitor the pressure in the dewar. If the pressure control 1202 determines that the rate of increase of pressure is not enough, the method 1500 can proceed to step 1514.

[0218] At step 1514, the pressure control 1202 can modify the power delivered to the heating assembly 1012. The pressure control 1202 can increase the power delivered to the heating assembly 1012 to increase the generation of cryogen vapor and increase the pressure increase rate. The pressure control 1202 can modify the power signal to increase the pressure increase rate. For example, the pressure control 1202 can modify the current, voltage, PWM or other variables of the power signal. After making such modifications, the method 1500 can return to step 1504 to continue monitoring and controlling the pressure in the Dewar 1002.

[0219] Returning now to step 1516, the pressure control 1202 can determine whether the pressure in the Dewar 1002 is above the upper operating threshold. The pressure control previously determined that the pressure in the Dewar 1002 was not below the lower operating threshold (at step 1508), and now determines whether the pressure is above the upper operating threshold. For the cryoablation device 1000 using liquid nitrogen as a cryogen, the upper operating threshold may correspond to about 15psi. In other examples and for other cryogens, the upper operating threshold may have other values. If the pressure control 1202 determines that the pressure in the Dewar 1002 is above the upper operating threshold, the method 1500 moves to step 1518. If the pressure control 1202 determines that the pressure in the Dewar is not above the upper operating threshold, the pressure control 1202 has determined that the pressure in the Dewar is within the desired operating range and no changes are required. In this case, the method 1500 returns to step 1504 to continue to obtain information from the sensor 1008 and monitor the pressure in the Dewar 1002.

[0220] If the method 1500 moves to step 1518, the pressure control 1202 can de-energize the heating assembly 1012. Because the pressure in the dewar 1002 is too high, the heater no longer needs to convert the liquid cryogen to cryogen vapor. The heater can be de-energized to stop this conversion. Then, the method 1500 can continue to step 1520.

[0221] At step 1520, the pressure control 1202 can determine whether the pressure in the dewar is still too high (i.e., above the upper pressure threshold) or is increasing. If the pressure is still too high or the pressure is increasing, the method 1500 can move to step 1522. If the pressure is not too high and the pressure is not increasing, the method can continue to step 1504 to continue to obtain information from the sensor 1008 and monitor the pressure in the dewar 1002.

[0222] At step 1522, the pressure control 1202 can reduce the pressure in the Dewar. The pressure control 1202 can actuate or open the valve assembly 1016. The pressure control 1202 can vent pressure from the Dewar to reduce pressure and / or prevent pressure from increasing in the Dewar. After the pressure control 1202 takes action to reduce pressure or reduce pressure increase, the method 1500 can return to step 1504 to continue obtaining information from the sensor 1008 and monitoring the pressure in the Dewar 1002.

[0223] It should be appreciated that method 1500 can be continuously or semi-continuously performed during operation of cryoablation device 1000 to maintain the temperature of the Dewar vessel within a desired operating range. Such a closed-loop feedback process can be used so that cryoablation device 1000 can be effectively used to provide cryogen to cryoprobe 128.

[0224] Now go to Fig.16 , a method 1600 of providing a cryoprobe with a cryoaspirate is provided. The method 1600 may be performed simultaneously or in parallel with the method 1500. The method 1600 may be performed, for example, by the cryoablation device 1000 and / or the cryoablation system 1300. The method 1600 is described below with reference to the cryoablation device 1000 and the cryoablation system 1300, but it should be understood that other devices and systems may be used.

[0225] Method 1600 may begin at step 1602. At step 1602, cryoablation system 1300 may be ready to begin a cryoablation cycle. Cryoablation system 1300 may have been activated or started to operate. For example, pressure control 1302 may have prepared the cryogen in dewar 1002 to maintain the cryogen in dewar 1002 at a low pressure condition. For example, method 1500 may have been executed to pressurize the dewar to a low pressure condition. When dewar 1002 is ready or the system is ready, method 1600 may proceed to step 1604. Pressure control 1302 may verify that dewar 1002 is operating as desired before moving to step 1604.

[0226] At step 1604, the pressure control 1302 can begin obtaining information about the operating conditions of the cryoablation system 1300. The pressure control 1302 can obtain information about the desired puck size, growth rate, cycle duration, or other information. Such information can be obtained from the treatment plan or can be received by the pressure control 1302 from another source (such as user input, a database, a clinical procedure, etc.). The method 1600 can then proceed to step 1606.

[0227] At step 1606, the pressure control may receive pressure information regarding the refrigerant pressure at the outlet of the pump assembly 1014 or at the outlet of the cap assembly 1322. The pressure control 1302 may receive the pressure information from the sensor 1320 positioned at the outlet of the cap assembly 1322. The method 1600 may proceed to step 1608.

[0228] At step 1608, the pressure control 1302 can obtain other information about the performance of the cryoablation system 1300. The information can include the information previously described in step 1604. The information can include temperature and pressure information at the cryoprobe 128, which can indicate the growth of the ice ball at the cryoprobe 128. The information can be compared with optimized or desired operating parameters. The optimized or desired operating parameters can be determined using the previously described algorithms, lookup tables, models, etc. In some examples, the operating information is input into a trained machine learning model, which can output the optimized or desired operating parameters of the cryoablation system 1300. The pressure control 1302 can obtain or determine a lower high pressure threshold and / or an upper high pressure threshold. The lower high pressure threshold and the upper high pressure threshold can define the desired high pressure range desired for the cryogen when the cryogen flows through the cryoprobe to produce an ice ball with a desired size, growth rate, or other characteristics.

[0229] At step 1610, the pressure control 1302 can determine whether the pressure of the refrigerant at the outlet of the pump is less than the lower high pressure threshold. If the pressure at the outlet of the pump, for example, as measured by the sensor 1320, is less than the lower high pressure threshold, the method 1600 can move to step 1612. If the pressure control 1302 determines that the pressure at the outlet of the pump is not less than the lower high pressure threshold, the method 1600 can move to step 1618.

[0230] At step 1612, the pressure control 1302 may activate or turn on the pump. The pressure control 1302 may, for example, turn on a pump in the pump assembly 1014. The pump assembly 1014 may pressurize the cryogen in the supply tube 1006, which is supplying cryogen to the cryoprobe 128. The method 1600 may then move to step 1614.

[0231] At step 1614, the pressure control 1302 can determine whether the pressure of the cryogen is increasing at a rate sufficient to perform cryogen therapy. For example, if the pressure is increasing at a rate sufficient to allow cryoablation therapy to be successfully completed within the desired time, the pressure control 1302 can determine that the pressure increase is sufficient. If the pressure control 1302 determines that the pressure increase is too slow, so that the ice ball cannot reach the desired size within the specified time, the pressure control 1302 can determine that the pressure increase is insufficient. This determination can be made using a treatment plan, an algorithm, a machine learning model, etc. If it is determined that the pressure increase is sufficient, the method 1600 returns to step 1606, whereby the pressure control 1302 continues to monitor the operation of the cryoablation system 1300. If it is determined that the pressure increase is insufficient, the method 1600 can move to step 1616.

[0232] At step 1616, the pressure control 1302 can adjust or modify the operating parameters of the cryoablation system 1300 to change the pressure of the cryoablation agent. For example, the pressure control 1302 can change, increase or adjust the speed or duty cycle of the power signal delivered to the pump. This modification can increase the pressure increase rate of the cryoablation agent. The pressure control 1302 can use an algorithm, a lookup table, a database, a known relationship, a training model, etc. to determine the nature, size, amplitude or details of the change in pump operation. Then, the method 1600 can return to step 1606, where the steps are re-executed, and the pressure control 1302 continues to monitor the operation of the cryoablation system 1300.

[0233] At step 1618, the pressure control 1302 can determine whether the refrigerant pressure at the outlet of the pump is greater than the upper high pressure threshold. The pressure control 1302 can make this determination by comparing the refrigerant pressure received from the sensor 1320 with the upper high pressure threshold. If the pressure is greater than the upper high pressure threshold, the method 1600 can move to step 1620. If the pressure is not greater than the upper high pressure threshold, the method 1600 can move to step 1626.

[0234] At step 1620, the pressure control 1302 may deactivate or reduce the duty cycle delivered to the heater assembly. The pressure control 1302 may have been pressurizing the refrigerant, and now feedback from the system indicates that the pressure is too high. The pressure control 1302 may take action at step 1620 to reduce the pressure or reduce the pressure increase. Then, the method 1600 may move to step 1622.

[0235] At step 1622, the pressure control 1302 may determine whether the pressure at the outlet of the pump is still increasing. For example, the pressure control 1302 may make this determination based on the pressure information received from the sensor 1320. If the pressure at the outlet of the pump is still increasing, the method 1600 may move to step 1624. If the pressure at the outlet of the pump is not increasing, the method 1600 may return to step 1606, where the steps are re-executed and the pressure control 1302 continues to monitor the operation of the cryoablation system 1300.

[0236] At step 1624, the pressure control 1302 can take further action to reduce the pressure of the cryogen. The pressure control 1302 can, for example, open a valve in the valve assembly 1016. The pressure control 1302 can take such an action to exhaust the gas in the dewar 1002 to reduce the pressure of the cryogen. In other examples, the pressure control can take other actions, such as further reducing the duty cycle of the pump and / or opening other valves or exhaust ports that may be included in the cryoablation system 1300. Then, the method 1600 can return to step 1606, where the steps of the method 1600 are re-executed, and the pressure control 1302 continues to monitor the operation of the cryoablation system 1300.

[0237] At step 1626, the pressure control 1302 has determined that the pressure at the outlet of the pump is within the desired operating range (e.g., between a lower high pressure threshold and an upper high pressure threshold). The method 1600 can return to step 1606, where the steps of the method 1600 are re-executed and the pressure control 1302 continues to monitor the operation of the cryoablation system 1300. It can be seen that the method 1600 provides a closed-loop feedback system, whereby the pressure of the cryogen delivered to the cryoprobe can be continuously or semi-continuously monitored and adjusted. Adjustments to the operation of the cryoablation system 1300 can be automatically performed based on experimental data and / or historical data. In some examples, the trained machine learning model can be continuously updated using treatment data obtained during cryoablation treatment. The method 1600 achieves optimization of the efficiency and effectiveness of the cryoablation system 1300 to provide better performance and lower cost than existing systems.

[0238] See now Fig.17 , an example method 1700 of providing a cryogen to a cryoprobe is provided. The example method 1700 can be performed using the devices and systems of the present disclosure. For example, the cryoablation system 1300 can be used to perform the method 1700. The cryoablation system 1300 is used in the following description for illustrative purposes only, and the description should not be interpreted as limiting the performance of the method 1700 with respect to a specific device system.

[0239] Method 1700 can start at step 1702. At step 1702, pressure control unit 1302 can obtain dewar pressure information. Dewar pressure information can characterize the pressure of the cryogen in dewar 1002. Pressure information can be obtained by one or more pressure sensors (such as sensor 1008 that can be positioned on supply pipe 1006 and / or in dewar 1002). Pressure information can be used to determine whether the pressure in the dewar is within a first predetermined operating range. This predetermined operating range in the dewar can correspond to a low pressure range, such as about 10psi to about 15psi for liquid nitrogen.

[0240] At step 1704, the pressure control 1302 can maintain the pressure of the cryogen in the dewar 1002 within a first predetermined operating range. The pressure control 1302 can use the heating assembly 1012 as described above. The pressure control 1302 can activate or deactivate the heater in the heating assembly 1012 to convert the liquid cryogen in the dewar 1002 into cryogen vapor. The pressure control 1302 can use various methods, such as algorithms, predetermined relationships, databases, lookup tables, mathematical relationships, machine learning models, etc., to determine what actions should be taken to maintain the pressure in the dewar within the first predetermined operating range.

[0241] At step 1706, the pressure control 1302 can obtain pump pressure information. The pump pressure information can characterize the pressure of the cryogen at the outlet of the pump. For example, the pump pressure information can be obtained from the sensor 1320. The pump pressure information can be used to determine whether the pressure at the outlet is within a second predetermined operating range. This predetermined operating range at the outlet of the pump can correspond to a high pressure range, such as about 400 psi to about 600 psi for liquid nitrogen.

[0242] At step 1708, the pressure control 1302 can maintain the pressure of the refrigerant at the outlet of the pump within a second predetermined operating range. The pressure control 1302 can activate or deactivate the pump or cover assembly 1322 of the pump assembly 1014 to increase the pressure of the refrigerant at the outlet of the pump. The pressure control 1302 can modify the pump speed, pump pulse frequency, amplitude or other characteristics of the flow to modify the pressure. The pressure control 1302 can use various methods, such as algorithms, predetermined relationships, databases, lookup tables, mathematical relationships, machine learning models, etc., to determine what actions should be taken to maintain the pressure at the outlet at a pressure within a second predetermined operating range.

[0243] It should be appreciated that steps 1702 to 1708 may be performed continuously or semi-continuously so that the pressure control 1302 may monitor and adjust the operating parameters of the cryoablation system 1300. In addition, during the operation of the cryoablation system 1300, the steps of maintaining the pressure in the Dewar flask and maintaining the pressure at the outlet of the pump may be performed simultaneously or in parallel. By maintaining the pressure of the cryogen in the Dewar flask at the desired operating pressure, the cryogen may be pressurized to a high pressure condition more efficiently and effectively than existing systems. Such operation results in better performance than existing systems.

[0244] Automatic gas switching and purge

[0245] In some embodiments of the present disclosure, devices and methods are provided that can be used to automatically control cryogen gas pressure, convert liquid cryogen to cryogen vapor, and use this cryogen vapor for purposes other than producing ice balls at the cryoprobe. These other purposes can include system cleaning, purging, thawing, and pressure pushing.

[0246] Prior to initiating a cryoablation cycle to create an ice ball at the target tissue, it may be desirable to move a heated fluid, such as cryogen vapor, through the cryogen flow path to clean, purge, or otherwise prepare the cryogen flow path for the cryoablation cycle. This movement of cryogen vapor through the flow path may also be used for the thawing process during the cryoablation cycle. The thawing process may raise the temperature of the cryoprobe to allow the cryoprobe to be removed from an ice ball that may have formed during the cryoablation cycle.

[0247] The apparatus and methods of the present disclosure may also be used for a precooling process. During this process, a cryogen vapor may be passed through a cryogen flow path. The cryogen vapor used in the precooling process will not be raised to a temperature that thaws ice, but may be a frozen cryogen vapor. The temperature of the frozen cryogen vapor may be a temperature below ambient temperature, but not below the temperature of the cryogen used during the cryoablation cycle. This precooling process may reduce the temperature of the cryogen supply line and / or cryoprobe prior to the cryoablation cycle. This precooling may allow the temperature of the cryogen to be lower when it reaches the cryoprobe than in other systems that begin a cryoablation cycle when the flow path (e.g., supply line and cryoprobe) is at ambient temperature. By precooling, the cryogen is able to remove heat from the target more quickly during the early stages of the cryoablation cycle, thereby allowing an ice ball to be formed more quickly than with conventional cryoablation systems.

[0248] The precooling process can reduce the temperature of the entire cryogen flow path and the elements of the cryoablation device. The console, cryogen flow path, valves, cryoprobe and other elements can be cooled to reduce the temperature from the initial or ambient conditions. The flow path is cooled so that the cryoablation treatment time is shorter than the time that may otherwise be required and can be operated more efficiently. In existing systems, liquid cryogens (e.g., liquid nitrogen) can be used to cool the cryoablation device, using low-pressure (50psi) or high-pressure (500psi) liquid nitrogen. However, the use of such liquid cryogens can produce the risk of micro-ice balls inside the cryogen flow path, especially if there is moisture in the cryogen flow path and / or the probe. The precooling process of the present disclosure can use a cryogen gas (such as nitrogen at about -20°C to about -80°C) to purge and cool the cryoablation device. The precooling process reduces the risk of micro-ice balls forming in the cryogen flow path, thereby improving over existing systems and methods.

[0249] Now go to Fig.18 , an example cryoablation device 1800 is shown. Cryoablation device 1800 can be included in a cryoablation system, such as cryoablation system 100 described above. Cryoablation device 1800 can be coupled to cryogen supply 114 and cryoprobe 128 to provide cryogen to cryoprobe 128 during cryoablation therapy.

[0250] Cryoablation device 1800 can include a dewar 1802, a supply rod 1804, a cap assembly 1810 and a cryogen gas assembly 1814. Dewar 1802 can be similar to the above-mentioned dewar, and can be a chamber that defines an internal volume to hold a certain volume of cryogen. The cryogen can be various suitable cryogenic fluids, such as nitrogen, helium, argon, etc. Dewar 1802 can include a certain volume of liquid cryogen 1806 and a certain volume of cryogen vapor 1808.

[0251] The supply rod 1804 can extend into the interior volume of the dewar 1802. The distal end of the supply rod 1804 can extend toward the bottom of the dewar 1802 and extend into the liquid cryogen 1806. The supply rod 1804 can be a hollow member or include an inner cavity or a tube to allow the liquid cryogen to be pumped from the dewar 1802 to the cryoprobe 128. The cap assembly 1810 can include a controllable pump motor and / or a pump assembly to pump the liquid cryogen 1806 through the supply rod 1804. When the cryogen is supplied to the cryoprobe 128, the cap assembly 1810 can pressurize the cryogen to form an ice ball at the cryoprobe 128 during a cryoablation cycle. The supply rod 1804 can also be fluidly connected to a cryogen gas assembly 1814. The connector 1816 can be a tube, conduit, or other member to allow the liquid cryogen 1806 to be dispensed into the cryogen gas assembly 1814. A suitable pump may be used to automatically dispense the liquid cryogen 1806 into the cryogen gas assembly 1814. A level sensor may be used to determine when liquid cryogen 1806 needs to be dispensed into the cryogen gas assembly 1814.

[0252] As shown, the cryogen gas assembly 1814 can be positioned within the interior volume of the dewar 1802. The cryogen gas assembly 1814 can be positioned toward the top of the dewar 1802 and / or positioned in a portion of the dewar 1802 that is generally filled with cryogen vapor 1808. In other examples, the cryogen gas assembly 1814 can be positioned outside the dewar 1802. In one example, the cryogen gas assembly 1814 can be positioned in the cryogen flow path, such as downstream of the cap assembly 1810, along or fluidly connected to the cryogen supply 114 ( Figure 1 ).

[0253] As further shown, the cryoablation device 1800 may include a gas control 1820. The gas control 1820 may be coupled to the cap assembly 1810, the cryogen gas assembly 1814, and other aspects of the cryoablation device 1800. The gas control 1820 may be a computing device, a PLC, a controller, or other suitable device. For example, the gas control 1820 may include an element included in the computing device 900. The gas control 1820 may be coupled to an element of the cryoablation device 1800 via a wired or wireless connection to send and receive information and / or signals from the element. The gas control 1820 may operate to control operating parameters of the cryoablation device 1800 and / or obtain data or information about the operation of the cryoablation device 1800. Although not shown, the cryoablation device may include one or more sensors positioned in the dewar 1802, along the supply rod 1804, in the cap assembly 1810, and / or along the flow path of the cryogen. The sensor may obtain information such as temperature, pressure, flow rate, flow rate, and other information.

[0254] Additional aspects of the exemplary cryogen gas assembly 1814 are as follows: Fig.19 . The cryogen gas assembly 1814 may include a housing 1902. The housing 1902 may define a cavity that may be used to hold a liquid cryogen 1906 and a cryogen gas 1904. The housing 1902 may be insulated for heating and pressure temperature. The housing 1902 is preferably insulated to allow the condition of the cryogen in the housing 1902 to be set to a preferred operating range required to perform a specific action (such as cleaning, purging, precooling, thawing, etc.). The housing 1902 may be insulated using a double wall structure, insulating material, a vacuum layer, or the like. By positioning the housing 1902 in the dewar flask 1802, the cryoablation device 1800 may operate more effectively than when positioned at other locations outside the dewar flask 1802.

[0255] The cavity of shell 1902 can be fluidly connected to flow conduit 1912 and valve assembly 1918. Flow conduit 1912 can connect the internal cavity of shell 1902 with cryogen supply 114 fluid. Flow conduit 1912 can include conduit heater 1920. Conduit heater 1920 can be positioned in flow conduit 1912, and allows the cryogen gas that may be assigned to cryogen flow path to be heated to a desired temperature. For example, cryogen gas may be desired to be used for thawing cycle. In this example, conduit heater 1920 can be controlled / activated by gas control 1820 to heat cryogen gas to a desired temperature. Conduit heater 1920 can be a resistance heater, a laser heater, a radio frequency (RF) heater or other suitable heaters.

[0256] Cryogen gas can flow from the housing 1902 through the flow conduit and through the cryogen flow path and the cryoprobe 128. The controllable flow valve 1914 can be opened or closed to variably control the flow of the cryogen gas 1904 leaving the housing 1902. The valve assembly 1918 can include a discharge valve 1916. The discharge valve 1916 can also be a controllable valve that can be opened or closed to variably control the discharge of cryogen gas from the interior cavity of the housing 1902. The flow valve 1914 and the discharge valve 1916 can each be coupled to a gas control 1820. The gas control 1820 can operate and / or regulate the flow of the cryogen gas to supply a desired flow of the cryogen gas or discharge the cryogen gas to control the pressure in the housing 1902.

[0257] The cryogen gas assembly 1814 may also include a heater 1910. The heater 1910 may extend in the housing 1902 and may extend from the top of the housing toward the bottom of the housing 1902 to contact or thermally engage the liquid cryogen 1906. The heater 1910 may include a controllable heating element, such as a resistive heater, a laser heater, a radio frequency (RF) heater, and the like. The heater 1910 may heat the liquid cryogen to convert the liquid cryogen 1906 into a cryogen gas 1904. The heater 1910 may be used in this manner to generate the cryogen gas 1904 and raise the pressure of the housing 1902 to a desired pressure. The heater 1910 may also heat the cryogen gas to a desired temperature. The heater 1910 may be coupled to a gas control 1820. The gas control 1820 may interface with the heater 1910 to activate, deactivate, or otherwise variably deliver a power signal to the heater 1910 to energize the heater. The gas control 1820 may provide various duty cycles to the heater 1910, such as variable frequency, amplitude, pulse width modulation (PWM), and the like.

[0258] See now Fig. 20 , a method 2000 of providing a cryogen gas to a cryoablation flow path is provided. For example, the method 2000 can be performed using the cryoablation device 1800. The following description describes the method 2000 performed by the cryoablation device 1800. Reference can also be made to the cryoablation system 100. However, it should be understood that the method 2000 is not limited to being performed by these devices and systems. Other systems and devices can be used, including other systems and devices of the present disclosure.

[0259] Method 2000 may begin at step 2002. At step 2002, cryoablation device 1800 may be initialized, and gas control 1820 may determine and / or check that all components are functioning as intended. Step 2002 (and method 2000) may be performed, for example, before a cryoablation cycle begins. Step 2002 and method 2000 may also be performed after a cryoablation cycle, when a thawing cycle is required, or when maintenance of cryoablation device 1800 is required.

[0260] The method 2000 may proceed to step 2004. At step 2004, the gas control 1820 may obtain operational information. The operational information may include information or data characterizing operational conditions at various locations of the cryoablation device 1800. The operational conditions may include, for example, pressure, temperature, flow rate, etc. The operational conditions may include the pressure and temperature of the dewar 1802, the pressure and temperature of the cryogen gas assembly 1814, and / or the pressure and temperature in the supply rod 1804 or at the outlet of the cap assembly 1810. The gas control 1820 may also obtain operational information for other locations in the flow path of the cryoablation system.

[0261] Method 2000 may continue to step 2006. At step 2006, the vacuum pump may be energized. Fig.18 1800, but the cryoablation device 1800 may include a vacuum pump, and the vacuum pump may be coupled to the gas control 1820. The vacuum pump may be operated to provide an insulating layer between the housing 1902 of the cryogen gas assembly 1814 and the dewar 1802. The gas control 1820 may activate the vacuum pump to evacuate the insulating layer of the housing 1902.

[0262] The method 2000 may proceed to step 2008. At step 2008, the gas control 1820 may initiate heating in the cryogen gas assembly 1814. The gas control 1820 may cause a power signal having a desired duty cycle to be delivered to the heater 1910 of the cryogen gas assembly 1814. The heater 1910 may begin heating the liquid cryogen 1906 to convert the liquid cryogen 1906 into the cryogen gas 1904.

[0263] The method 2000 may proceed to step 2010. At step 2010, the gas control 1820 may monitor the operating conditions of the cryogen gas assembly 1814 and continue to produce cryogen gas and / or exhaust cryogen gas to achieve the desired operating conditions in the housing 1902 of the cryogen gas assembly 1814. The process for performing this maintenance may be a closed-loop feedback process in which the gas control 1820 receives information about the conditions of the cryogen gas and the cryogen gas assembly 1814, such as temperature, pressure, power signals of the heater 1910, etc. This information may be used to adjust the operation of the heater 1910 and / or the flow valve 1914 and / or the exhaust valve 1916. The gas control 1820 may maintain the conditions of the cryogen gas within a predetermined operating level or range.

[0264] Method 2000 may proceed to step 2012. At step 2012, gas control 1820 may determine whether a cryogen gas purge is required. Gas control 1820 may determine whether a purge, cleaning, thawing, precooling, or other cryogenic gas flow process is required. This information may be obtained by gas control 1820 according to a treatment plan or from a clinical treatment procedure. For example, a flush or purge may be indicated before each cryoablation cycle, or at startup, or after the system is stored. Information about the need or desire for a purge may also be obtained via a user configuration. In other examples, gas control 1820 may obtain information as a result of one or more sensors that may indicate the need for a purge or cleaning. As described in detail below, gas control 1820 or other computing device may perform a diagnostic step so that it may be automatically determined whether a purge process is required. If gas control 1820 determines that a purge process is desired, method 2000 moves to step 2014. If gas control 1820 determines that a purge process is not desired, method 2000 moves to step 2026.

[0265] At step 2014, gas control 1820 can determine whether the purge process requires high pressure cryogen gas. Gas control 1820 can automatically determine whether high pressure gas is needed based on the above information (including treatment plan, clinical procedure, user input or other information). Specific types of purge processes may require high pressure gas, such as those instances where blockage is detected or determined in the cryogen flow path. High pressure gas can be used for cleaning and removing blockage. High pressure gas can be a gas with a pressure in the range of about 100psi to about 1000psi. Low pressure gas can be a gas in the range of about 10psi to about 50psi. Low pressure gas can be used for cleaning during the purge process, and no blockage is detected or determined. If gas control 1820 determines that high pressure gas is needed, the method moves to step 2016. If gas control 1820 determines that high pressure gas is not needed, method 2000 proceeds to step 2018. At step 2016, the gas control 1820 may energize the heater 1910 using a high power mode to increase the conversion of the liquid cryogen to cryogen gas, thereby increasing the pressure in the housing 1902. At step 2018, the gas control may energize the heater 1910 using a lower power mode to convert the liquid cryogen to cryogen gas at a lower rate than the high power mode. The low power mode may use a different duty cycle, voltage, current, or PWM than the high power mode, which may be controlled by the gas control 1820.

[0266] After steps 2016 and 2018, method 2000 may proceed to step 2020. At step 2020, gas control 1820 may determine whether high temperature gas is required. Gas control 1820 may determine whether high temperature gas is required, similar to whether high pressure gas is required. This information may be input by a user, or may be detailed in a treatment plan or clinical procedure. In other instances, gas control 1820 may automatically determine whether high temperature gas is required based on a diagnostic procedure or information obtained from one or more sensors of cryoablation device 1800. If gas control 1820 determines that high temperature gas is required, method 2000 proceeds to step 2022. If gas control 1820 determines that high temperature gas is not required, the method proceeds to step 2024.

[0267] The desired temperature of the gas can be based on the type of procedure being performed. The thawing procedure can use a temperature of about 40°C to about 60°C. The solidification and / or cauterization procedure can use a temperature of about 80°C to about 120°C. The temperature can also vary with the pressure of the cryogen gas. The pressure and temperature used during the procedure can also vary with clinical needs. In some examples, for the thawing procedure, a cryogen gas with a pressure range of about 10psi to about 50psi and a temperature of about 10°C to about 40°C can be used. These conditions can be used to provide a quick time to remove the needle from the ice ball. In some cases, for the solidification or cauterization procedure, a cryogen gas with a pressure range of about 10psi to about 50psi and a temperature greater than about 50°C can be used. Such an operation can shorten the time of the procedure to about 10 to about 15 seconds. This may be particularly useful if the needle needs to be repositioned during treatment. This reduced time can reduce the total treatment time from about 2 hours to about 30 minutes.

[0268] At step 2022, the gas control 1820 can turn on the conduit heater 1920. As described above, the conduit heater 1920 can be located in the flow conduit 1912. The flow conduit 1912 can connect the cryogen gas device 1814 fluid to the cryogen flow path. The gas control 1820 can activate the conduit heater 1920 to heat the cryogen gas when the cryogen gas is transferred to the cryogen flow path during the purge cycle. The gas control 1820 can use various power signals, duty cycles, etc. to activate the heater to heat the cryogen gas to a desired temperature. The gas control 1820 can obtain temperature information from one or more sensors positioned in the flow conduit 1912, and modify or adjust the power supplied to the conduit heater 1920 to adjust the cryogen gas temperature to a desired temperature or a desired temperature range.

[0269] At step 2024, the gas control 1820 may deactivate the conduit heater 1920 and / or deliver a low level power signal to the conduit heater 1920. Similar to the above, the gas control 1820 may obtain temperature information from one or more sensors positioned in the flow conduit 1912 and modify or adjust the power supplied to the conduit heater 1920 to adjust the cryogen gas temperature to a desired temperature or desired temperature range. The temperature of the cryogen gas at step 2024 is lower than the temperature of the high temperature gas provided by step 2022.

[0270] At step 2026, the gas control 1820 may determine whether the purge process is complete. The purge process may be for a certain duration or a certain volume of refrigerant gas. In other examples, the gas control 1820 may determine whether the purge process is complete by obtaining such information from a treatment plan, a clinical procedure, input from a user, or automatically by measuring operational or diagnostic information from one or more sensors. If the gas control 1820 determines that the purge process is complete, the method moves to step 2028. If the gas control determines that the purge process is not complete, the method moves to step 2030.

[0271] At step 2030, the gas control 1820 may determine whether the conditions within the enclosure 1902 of the cryogen gas assembly 1814 meet predetermined cryogen gas conditions. The particular purge process being performed (e.g., cleaning, thawing, precooling, etc.) may indicate a particular set of cryogen gas conditions, such as temperature, pressure, volume, etc. The gas control 1820 may obtain information about these conditions and determine whether the cryogen gas conditions are satisfactory or sufficient based on the particular purge process to be performed.

[0272] At step 2030, the gas control 1820 can also take action to modify or adjust the condition of the cryogen gas. The gas control 1820 can determine, for example, that the pressure in the housing 1902 is too high. The gas control 1820 can use the exhaust valve 1916 to exhaust the pressure from the housing 1902. In another example, the gas control 1820 can determine that the cryogen gas pressure is too low. The gas control 1820 can increase the power delivered to the heater 1910 to increase the production of cryogen gas, thereby increasing the pressure. In other instances, the gas control 1820 can take other actions. In this way, the gas control 1820 can monitor the operation of the cryoablation device 1800 and continuously adjust the parameters of the system as needed to perform an efficient and effective purge process.

[0273] At step 2028, the gas control 1820 can stop heating the gas in the cryogen gas assembly 1814, and the catheter heater 1920 can be deactivated or de-energized. If additional cryoablation cycles are prescribed, cryoablation can continue. If no further cycles are required, the method 2000 can end.

[0274] It should be appreciated that method 2000 can be performed multiple times during cryoablation therapy. For example, method 2000 can be performed before performing a first cycle to purge or clean the system. Method 2000 can be performed again to perform a precooling process. Method 2000 can be performed again at the end of cryoablation therapy to purge the system.

[0275] See now Fig.21, another example method 2100 for performing a purge process is provided. The method 2100 can be performed by the device and / or system of the present disclosure. The method 2100 can also be performed by other devices and / or systems. The method 2100 is described below as being performed by the cryoablation device 1800, but it should be understood that the steps and / or operations can be performed by other devices and / or systems.

[0276] Method 2100 may begin at step 2102. At step 2102, gas control 1820 may move a portion of liquid cryogen from dewar 1802 to housing 1902 of cryogen gas assembly 1814. For example, a pump may be used to move the liquid cryogen into housing 1902. A conduit may fluidly connect the interior volume of dewar 1802 to housing 1902. Supply rod 1804 may be, for example, Fig.18 1902. A connector 1816 can fluidly connect the supply rod 1804 to the cryogen gas assembly 1814. The gas control 1820 can move liquid cryogen from the dewar 1802 into the housing 1902. A level sensor or other measuring device can indicate when liquid cryogen needs to be moved into the housing 1902. For example, the gas control 1820 can automatically maintain a predetermined cryogen level in the housing 1902.

[0277] At step 2104, the liquid cryogen in the housing 1902 may be heated. For example, the gas control 1820 may activate the heater 1910 by delivering a suitable power signal to the heater 1910. The heater 1910 may be in contact with the liquid cryogen or otherwise thermally coupled to the liquid cryogen so that the liquid cryogen is converted to cryogen gas in the housing 1902.

[0278] At step 2106, the gas control 1820 can obtain cryogen gas information. The gas control 1820 can obtain cryogen gas information that characterizes the condition of the gas cryogen in the housing 1902. The cryogen gas information can include the temperature and pressure of the cryogen gas. The gas control 1820 can compare such cryogen gas information with a predetermined threshold, range, or other desired characteristic of the cryogen gas. The desired characteristic of the cryogen gas can be indicated by a treatment plan, a clinical procedure, a user preference, and / or automatically by the gas control 1820. The desired characteristic can be predetermined based on the type of purge process to be provided (such as cleaning, purging, thawing, precooling, or other).

[0279] The gas control 1820 can determine whether the measured cryogen gas information corresponds to a purge process or is sufficient for a purge process. If not, the gas control can take action to increase / decrease pressure or temperature, for example. If the gas control 1820 determines that the cryogen gas is suitable for the desired purge process, the method can continue to step 2108.

[0280] At step 2108, gas control 1820 can move cryogen gas from housing 1902 into cryogen flow path. Cryogen flow path can include cryogen supply 114 and / or cryoprobe 128. Cryogen gas can clean, clean, thaw, precool or otherwise purge the cryogen flow path. Gas control 1820 can open flow valve 1914, for example, to allow cryogen gas to flow to cryogen flow path. In some instances, gas control 1820 can also heat cryogen gas when cryogen gas flows through cryogen flow path. For example, gas control 1820 can use conduit heater 1920 to heat cryogen gas.

[0281] The above-described apparatus and methods can provide a cryogen gas device or assembly that can provide improvements to known or existing devices. For example, the cryogen gas assembly 1814 can be integrated into a cryoablation system and provide an automatic control and closed-loop feedback process to provide a cryogen gas source suitable for a specific purge process. A purge process can be provided to prepare the cryoablation system for cryogen ablation treatment and / or prepare the cryoablation system for storage after cryoablation treatment. In addition, the cryoablation gas assembly 1814 can be used during cryoablation treatment to provide a thawing process or to resolve blockages or other problems that may occur.

[0282] Automated cryoablation system performance testing and diagnosis

[0283] In some embodiments of the present disclosure, the cryoablation system, device and method of the present disclosure can provide automatic real-time performance detection and diagnosis. Such embodiments can include diagnostic controls that can be coupled to the cryoablation system. The cryoablation system can use various valves and cryogen sensors positioned at various positions along the cryogen flow path. The diagnostic control can open and close the valves at various positions along the cryogen flow path, and obtain measurements of operating parameters of the cryogen at different positions. This information (e.g., temperature and pressure) can be used to determine whether the cryoablation system is performing normally and / or whether it is at a desired level for efficient and effective operation. The diagnostic control can be able to determine and / or predict whether operational problems may occur, such as the location of a blockage or leak is detected. The diagnostic control can also be able to determine or predict possible problems (e.g., blockage or leak) by monitoring the rate of change of the operating characteristics of the cryoablation system.

[0284] The devices and methods of the present disclosure are improvements over existing systems because the location of a blockage or leak can be easily determined. Existing systems are problematic because the user or operator may not be able to determine the location of a blockage, leak, or other problem. Existing systems may require the entire system to be taken offline and removed from the treatment environment to determine the location or cause of an operational problem. The systems, devices, and methods of the present disclosure may allow problems such as blockages or leaks to be detected and corrected without expensive, time-consuming, and potentially ineffective repairs.

[0285] Example cryoablation system 2200 Fig. 22 . The cryoablation system 2220 may include a dewar 2202. The dewar 2202 may include previously described structures and features, such as a cryogen level sensor, a cryogen rod 2204, and a cap assembly 2206. The dewar 2202 may be adapted to hold a volume of cryogen and move liquid cryogen to a cryogen flow path to perform cryoablation therapy. For example, liquid cryogen may be pumped from the dewar 2202 to a cryogen supply 2230. The cryogen may flow to a cryoprobe 2216 through the cryogen supply 2230. The cryoprobe 2216 may be positioned at or near a target tissue in a patient 2232.

[0286] The cryoablation system 2200 may also include multiple sensors and valves at various locations along the cryogen flow path. The cryoablation system 2200 may include, for example, an outlet sensor 2208, a vacuum chamber sensor 2212, a probe sensor 2216, and a return sensor 2224. Each of the outlet sensor 2208, the vacuum chamber sensor 2212, the probe sensor 2216, and the return sensor 2224 may be configured to provide information about the cryogen flow in the cryogen flow path. The outlet sensor 2208, the vacuum chamber sensor 2212, the probe sensor 2216, and the return sensor 2224 may provide pressure, temperature, flow, or other information. In one example, the outlet sensor 2208, the vacuum chamber sensor 2212, the probe sensor 2216, and the return sensor 2224 are temperature or pressure transducers. In other examples, the outlet sensor 2208, the vacuum chamber sensor 2212, the probe sensor 2216, and the return sensor 2224 may be other types of sensors. In other examples, the outlet sensor 2208, the vacuum chamber sensor 2212, the probe sensor 2216, and the return sensor 2224 can be thin film pressure sensors, piezoelectric pressure sensors, and the like.

[0287] The outlet sensor 2208 can be positioned at the outlet of the pump. The vacuum chamber sensor 2212 can be positioned at or near the vacuum chamber of the cryoablation system, or can be positioned after the supply valve 2210 used to supply cryogen to the cryogen flow path. The probe sensor 2216 can be positioned at or within the cryoprobe 2216. The return sensor 2224 can be positioned in the return line 2232, which can allow the cryogen to return to the Dewar 2202 or be exhausted to the atmosphere. The return line 2232 can also be connected to the supply 2230. The return line can allow the line fluid to be connected at or between the various elements of the cryoablation system for diagnostic purposes, as will be further described below.

[0288] It should be appreciated that the cryoablation system may include more sensors or other sensors than the outlet sensor 2208, vacuum chamber sensor 2212, probe sensor 2216, and return sensor 2224 shown. In addition, each of the outlet sensor 2208, vacuum chamber sensor 2212, probe sensor 2216, and return sensor 2224 may include multiple sensors. For example, there may be multiple probe sensors 2216 located at various locations along the cryoprobe 2216.

[0289] As further shown, the cryoablation system 2200 may include a supply valve 2210, a probe valve 2214, a first connector valve 2218, a second connector valve 2220, a third connector valve 2222, and a return valve 2226. The supply valve 2210 may be positioned at or near the outlet of the pump. The supply valve 2210 may be used, for example, to allow cryogen to flow from the Dewar 2202 to the cryogen flow path. The probe valve 2214 may be used to allow cryogen to flow to the cryoprobe 2216. The first connector valve 2218 may be positioned at the return of the cryoprobe 2216 and allow cryogen to flow from the cryoprobe 2216 to the return line 2232. The second connector valve 2220 may be positioned at a position between the Dewar 2202 and the cryoprobe 2216 to connect the supply 2230 fluid to the return line 2232. The second connector valve 2220 may allow the cryoprobe 2216 to be excluded from the cryogen flow path for diagnostic purposes. The third connector valve 2222 can be positioned between the Dewar flask and the return line upstream of the second connector valve to connect the supply 2230 and the return line 2232 fluid. The third connector valve 222 can allow other parts (such as a vacuum chamber) to be excluded from the cryogen flow path. The return valve 2226 can be positioned between the return line 2232 and the Dewar flask 2202. In some examples, the return valve 2226 can allow the cryogen to be returned to the Dewar flask 2202. In other examples, the return valve 2226 can allow the cryogen to be discharged to the atmosphere after it returns from the cryoprobe 2216.

[0290] The supply valve 2210, the probe valve 2214, the first connector valve 2218, the second connector valve 2220, the third connector valve 2222, and the return valve 2226 may each be configured as a controllable flow valve, which may be electronically controlled by the diagnostic control 2240. The supply valve 2210, the probe valve 2214, the first connector valve 2218, the second connector valve 2220, the third connector valve 2222, and the return valve 2226 may be respectively coupled to the diagnostic control 2240 via a wired or wireless connection, so that the supply valve 2210, the probe valve 2214, the first connector valve 2218, the second connector valve 2220, the third connector valve 2222, and / or the return valve 2226 may each be independently opened or closed to perform a diagnostic procedure.

[0291] Diagnostic control 2240 can be a suitable computing device, PLC, controller, or other device configured to perform the operations of the present disclosure. In some examples, diagnostic control 2240 can be a device such as computing device 900 described above. Diagnostic control 2240 can be incorporated into the above-mentioned other controls and / or can be the same device as the above-mentioned other controls.

[0292] The diagnostic control 2240 may include a data acquisition module 2242 that may be operable to obtain information regarding the operating conditions of the cryoablation system 2200. The diagnostic control 2240 may obtain data or signals from the outlet sensor 2208, the vacuum chamber sensor 2212, the probe sensor 2216, and / or the return sensor 2224, as well as other sensors of the cryoablation system 2200. The data acquisition module 2242 may process the information and data and may further communicate and / or send such information to other aspects of the diagnostic control.

[0293] The diagnostic control 2240 may also include a diagnostic module 2244. The diagnostic module 2244 may operate to determine whether the cryoablation system 2200 is operating properly and / or as expected. The diagnostics may include algorithms, models, trained machine learning models, artificial neural networks (ANNs), lookup tables, and the like, which may be used to determine where and which elements of the cryoablation system 2200 are operating as expected. The diagnostic module 2244 may obtain information such as clinical procedures, lookup tables, predetermined relationships, models, and the like.

[0294] Diagnostic controls 2240 may also include an operations module 2246. Operations module 2246 may send and / or receive signals from various elements of cryoablation device 2200 to perform functions to adjust, modify, and / or otherwise control the operation of cryoablation system 2200. Operations module 2246 may cause various valves to open or close, may adjust or modify the pressure or temperature of the cryogen, and / or may adjust the flow or flow rate of the cryogen.

[0295] The diagnostic module 2244 can use various suitable methods to determine whether the cryoablation system 2200 is operating as expected. The diagnostic module 2244 can, for example, obtain pressure information from one or more locations in the cryoablation system 2200 and compare pressures and / or rates of change of pressure to determine the performance of the cryoablation system 2200. The diagnostic module 2244 can receive pressure information from the data acquisition module 2242. The operation module 2246 can open and / or close various valves of the cryoablation and then compare the pressures at various locations along the cryogen flow path to determine whether the cryoablation system 2200 is operating as expected.

[0296] See now Fig.23 , illustrates an example pressure output 2300 observed during an example diagnostic procedure. In some examples, the pressure output 2300 can be output on a user interface of a diagnostic control 2240. The diagnostic module 2244 can monitor the pressure shown in the pressure output 2300. In this example, pressure curves 2302, 2304, and 2306 are shown. The pressure curves are shown as time-dependent changes during the diagnostic procedure. The first curve 2302 shows pressure data for a cryogen flow path without any problems in operation. The second curve 2304 shows pressure data for a cryogen flow path with a blockage in the cryogen flow path between the dewar flask 2202 and the supply valve 2210. The third curve 2306 shows pressure data for a cryogen flow path with a partial leak in the cryogen flow path between the dewar flask 2202 and the supply valve 2210.

[0297] In this example, the cryoablation system 2200 may be ready to perform cryoablation therapy. The diagnostic control 2240 may perform a diagnostic procedure to determine if there are any problems with the system, such as leaks, blockages, or other problems that may interfere with the performance of cryoablation therapy. In this example procedure, the diagnostic control 2240 may obtain pressure information from the supply sensor 2208. The cryogen may be activated and flow from the Dewar toward the supply valve 2210. As shown, the pressure in the cryogen flow path between the Dewar 2202 and the supply valve 2210 increases over time and may reach a target pressure 2308. The target pressure 2308 may be defined as a threshold and / or a target pressure range ΔP. The diagnostic control 2240 may monitor the amount of time it takes for the pressure in the cryogen flow path to reach the target temperature. The expected time is shown as a time period ΔT. The time period ΔT may be determined using experimental data or actual data and / or may be determined using a model. The diagnostic control 2240 may determine whether the time period ΔT is within a predetermined control tolerance range R%. If the time period ΔT is within R% of the time period ΔT, the diagnostic control can determine that the cryoablation system 2200 is operating as expected. If there is a blockage, the pressure may reach the target pressure faster than normal. If there is a leak, the pressure may take longer or never reach the target pressure. In either instance, the diagnostic control 2240 can indicate or otherwise communicate the potential problem to the user for correction.

[0298] As shown by curve 2304, the pressure reaches the target pressure faster than expected. In this case, the diagnostic control 2240 will see that the time period ΔT is much shorter than the target time period ΔT and is outside the tolerance range R%. The blockage will be communicated to the user or corrective action will be taken, such as a purge procedure, etc.

[0299] The pressure never reaches the target pressure as shown by curve 2306. After the time period ΔT has elapsed, the diagnostic control 2240 will identify that there is a problem and communicate this to the user.

[0300] If the diagnostic control determines that the cryoablation system 2200 is operating as expected. The diagnostic control 2240 can move to another part of the cryogen flow path and take steps similar to those described above to determine whether the pressure in the next part of the cryogen flow reaches the target pressure within the target time period ΔT. In this way, the diagnostic control 2240 can determine whether each part of the cryogen flow has a leak, blockage or other problem. For example, 2240 can open the supply valve 2210 to determine whether the next downstream part of the cryogen flow path is operating normally. Then, the diagnostic control 2240 can check the next part of the cryogen flow path by opening the detector valve 2214. If the diagnostic control 2240 determines at any time that there is a blockage or leak, the diagnostic control 2240 can open one or more connector valves 2218, 2220, 2222 to discharge the cryogen from the system by opening the return valve 2226.

[0301] See now Fig.24 , illustrating an example diagnostic model 2400. Model 2400 can be a machine learning model and can involve training a mathematical model in a supervised or unsupervised environment. Machine learning models can be trained to learn relationships between various data groups. These models can be based on a set of algorithms designed to model abstractions in the data using several processing layers. The processing layers can be composed of nonlinear transformations. Machine learning models can include, for example, neural networks, convolutional neural networks, and deep neural networks. Such neural networks can be composed of multi-level trainable filters, transformations, projections, hashing, and pooling. The model can be used for large-scale relationship identification tasks. Models can be created using various open source and proprietary machine learning tools and / or libraries known to those skilled in the art.

[0302] Model 2400 may include inputs 2402, layers 2404, outputs 2406, and results 2408. Inputs 2402 of model 2400 may include various data or information about cryoablation system 2200. The inputs may include data about the state or setting of a valve of cryoablation system 2200. Inputs 2402 may include one or more indicators or statistics. The inputs may include various calculations or other numerical indicators, ratios, etc., which may be determined from data about the operation of cryoablation system 2200. Indicators may include pressure indicators and / or ratios, such as the following.

[0303] Pressure indicators and ratios

[0304] Volatility Indicators

[0305] Volatility Ratio

[0306] Fluctuation pressure time ratio

[0307] Pressure singularity index_1

[0308] Pressure singularity index_2

[0309] Pressure Trend Indicator

[0310] Pressure Trend Indicator

[0311] Pressure Trend Indicator

[0312] Where P is the pressure in the refrigerant flow path.

[0313] Statistical indicators may include the following.

[0314] Mean or average value (expected value) of indicator

[0315] Standard deviation of indicators

[0316] Index variation

[0317] Indicator variability

[0318] Where X is the metric and W is the window size used in the calculation.

[0319] Pressure indices and ratios and statistical indices may be used as inputs 2402 in model 2400. Model 2400 may determine relationships between indices and ratios and outputs 2406 in order to accurately determine and / or predict potential problems (e.g., blockages or leaks) that may exist or be expected to occur in cryoablation system 2200.

[0320] Model 2400 can use one or more layers 2404 to determine output 2406. Output 2406 can be used as a predictor to determine the performance of the cryoablation system. Output 2406 can include, for example, the rate of change of pressure, the singularity of the pressure change during the pressurization of the cryoablation flow path, the shape and slope of the pressure, and / or the rate of change of pressure. These outputs can be determined for each part of the cryoablation flow path so that the problem in the cryoablation system 2200 can be determined and predicted. Output 2406 can also determine the extent of the problem. For example, output 2406 can allow model 2400 to determine whether the blockage is completely blocked, partially blocked, a blockage that is increasing, or clearing in the cryoablation flow path. Model 2400 can similarly be able to determine output 2406, which determines the extent of the leak.

[0321] Output 2406 can be used to determine result 2408. Result 2408 can be the action that the model enables diagnostic control 2240 to perform. Result 2408 can allow diagnostic control 2240 to perform expected or allowable pressure change rate in various parts of the cryogen flow path. This can allow diagnostic control 2240 to control the operation of cryoablation system 2200 so as to perform more efficiently and effectively, including reducing the time to perform cryoablation treatment. Result 2408 can also include allowing diagnostic control 2240 to determine whether cryoablation system 2200 performs as expected and the location and extent of problems (such as blockages or leaks). Overall, model 2400 can allow diagnostic control 2240 to perform real-time and automatically controlled pressure diagnosis and control of cryoablation system 2200.

[0322] See now Fig.25 , an example method 2500 for performing a diagnostic procedure is provided. The method 2500 can be performed using the previously described cryoablation system 2200. In other examples, the method 2500 can be performed using other devices or systems. The following description describes the method 2500 performed using the cryoablation system 2200. However, it should be understood that other devices and / or systems can be used.

[0323] Method 2500 may begin at step 2502. Method 2500 may be used to perform diagnostic procedures on a cryoablation system. At step 2504, diagnostic control 2240 may obtain information about the operating conditions of cryoablation system 2200. For example, such information may be obtained from pressure sensors positioned at various locations along the cryogen flow path.

[0324] At step 2506, the diagnostic control 2240 can cause refrigerant to flow to the refrigerant flow path and can begin recording operating information (e.g., pressure information) over time. Step 2506 can be performed sequentially for desired portions of the refrigerant flow path so that each portion is verified to be operating normally before opening the next downstream valve to check the next downstream portion.

[0325] At step 2508, the diagnostic control may calculate one or more indices, ratios, and / or otherwise extract and calculate operating pressures at various times during the pressurization and sequential verification of the refrigerant flow circuit.

[0326] At step 2510, the diagnostic control 2240 may monitor the pressure in the refrigerant flow path in real time. The diagnostic control 2240 may also determine statistical indicators as the pressure in the refrigerant flow path is monitored and verified for each sequential portion of the refrigerant flow path.

[0327] At step 2512, the diagnostic control 2240 can determine whether any blockage is detected at any part of the refrigerant flow path. The diagnostic control 2240 can compare the pressure change and / or pressure level and the time period for achieving the pressure level with the predetermined target pressure, target time period, and tolerance range. If the diagnostic control 2240 determines that there is a blockage, the method 2500 can proceed to step 2514. If the diagnostic control 2240 determines that there is no blockage, the method 2500 can proceed to step 2520.

[0328] At step 2514, the diagnostic control 2240 can initiate a cleaning or purge cycle to attempt to remove the blockage. The blockage may be caused by moisture or ice in the cryogen flow path. The diagnostic control 2240 can cause a heated gas or other fluid to flow through the cryogen flow path in an attempt to clear the blockage. The cryoablation system 2200 may include a gas cryogen assembly 1814, such as previously described, which can be used to purge or clean the cryogen flow path. In other examples, other purge or cleaning processes may be used.

[0329] At step 2516, the diagnostic control 2240 may re-execute the diagnostic procedure to determine if the blockage still exists. If the diagnostic control 2240 determines that there is no blockage, the method 2500 may return to step 2504 to re-execute the steps as previously described to verify and check the cryogen flow path. If the diagnostic control 2240 determines that there is still a blockage in the cryogen flow path, the method 2500 may continue to step 2518, where the cryoablation system may be stopped for further repairs.

[0330] At step 2520, diagnostic control 2240 can determine whether there is a leak in the refrigerant flow path. Diagnostic control 2240 can determine whether there is a leak by comparing the pressure information with the pressure threshold, pressure range and / or time period and tolerance range as described above. In some examples, diagnostic control 2240 can use a machine learning model, such as model 2400. If diagnostic control 2240 determines that there is a leak, method 2500 can proceed to step 2522. If diagnostic control 2240 determines that there is no leak, the method can proceed to step 2528.

[0331] At step 2522, the diagnostic control can determine remedial actions to attempt to correct the leak found at step 2520. The diagnostic control 2240 can suggest checking specific connections, replacing the cryoprobe, and / or reconnecting specific fittings or conduits. Such actions can be suggested using the model 2400, which can be trained to identify potential repairs for leaks at various portions of the cryogen flow path.

[0332] The method 2500 may then proceed to step 2524, where the diagnostic control 2240 may recheck the specific portion of the cryogen flow path where a leak was detected. The diagnostic control 2240 may re-execute one or more steps of the method 2500 to pressurize and test the identified portion of the cryogen flow path. If a leak is still detected, the method 2500 may proceed to step 2526, where the system is stopped for further repair or maintenance. If no leak is detected, the method 2500 may return to step 2504, where the method may be re-executed to check and verify normal operation of the cryoablation system 2200.

[0333] At step 2518, the diagnostic control 2240 may have determined that there are no leaks or blockages. The method 2500 may end and the system may perform the cryoablation treatment as expected. If a problem occurs or the cryoablation system 2200 is not performing, the method 2500 may be performed in advance to diagnose and possibly repair or correct possible problems in the cryoablation flow path.

[0334] See now Fig.26 , another method 2600 of performing a diagnostic procedure is provided. The method 2600 may be performed by one or more of the cryoablation systems and devices of the present disclosure or variations thereof. In one example, the method 2600 may be performed by the cryoablation device 2200. The following description describes the method 2600 performed by the cryoablation system 2200. It should be understood that the method 2600 is not limited to being performed by the cryoablation system 2200, and other systems and devices may be used.

[0335] The method may start at step 2602. At step 2602, the diagnostic control 2240 may obtain pressure information of the refrigerant pressure in the first portion of the refrigerant flow path. The diagnostic control 2240 may obtain pressure information characterizing the pressure in the supply 2230 from the flow sensor 2208. At this point in the method 2600, the flow valve 2210 may be closed so that the diagnostic control 2240 may obtain pressure information in an isolated portion of the refrigerant flow path, such as that portion of the supply 2230 upstream of the flow valve 2210. The diagnostic control 2240 may obtain and record pressure information over time since the supply 2230 is pressurized and / or track or record the rate of change of pressure over time. The information may be stored and / or displayed for later use. The method may proceed to step 2604.

[0336] At step 2604, the diagnostic control 2240 can compare the pressure in the first portion of the refrigerant flow path with the target pressure range. The diagnostic control 2240 can obtain the target pressure range from a database, experimental data, or clinical data, or can obtain the target pressure range when the target pressure can be recommended by a model, algorithm, or other source. Then, the method 2600 can proceed to step 2606.

[0337] At step 2606, diagnostic control 2240 can compare the time to the maximum pressure in the first part of the cryogen flow path with the target time range. As previously discussed, diagnostic control 2240 can record the pressure that varies over time. When the pressure in the first part reaches a maximum value, the time to reach this maximum pressure can be recorded. This time period can be compared with the target time range. The target time range can be obtained from a database, experimental data or clinical data, or the target time range can be obtained when the target pressure can be recommended by a model, algorithm or other sources. Then, method 2600 can proceed to step 2608.

[0338] At step 2608, if the diagnostic control 2240 determines that there is a flow problem, the diagnostic control 2240 can send a flow alarm. If the pressure in the first part of the refrigerant flow circuit exceeds the target pressure range, the diagnostic control 2240 can determine that there is a flow problem. If the time to reach the maximum pressure in the first part of the refrigerant flow circuit is longer or shorter than the time indicated by the target time range, the diagnostic control 2240 can determine that there is a flow problem. For example, if the time is too long, there may be a leak. For example, if the time is too short, there may be a blockage. In order to confirm correct or expected operation, the pressure should be within the target pressure range and the time should be within the target time range.

[0339] If a problem is detected, the diagnostic control 2240 can send a flow alarm. The flow alarm can be a message, an audible signal, a warning light, an email, a text message, an alarm display on a screen of the cryoablation system 2200, or other suitable indicator, or a combination of the above.

[0340] Although Fig.26 2200, but if a flow problem is detected, the diagnostic control 2240 can perform remedial actions to attempt to correct or repair the flow problem. The diagnostic control 2240 can, for example, cause a purge of the cryogen flow system to be performed. In other examples, the diagnostic control 2240 can send a recommended action to the user, such as reconnecting an element or replacing an element of the cryoablation device 2200.

[0341] The method 2600 may proceed to step 2610. At step 2610, the diagnostic control 2240 may determine whether all portions of the refrigerant flow path have been verified. If all portions have been verified, the method 2600 may end. If all portions have not been verified, the method 2600 may return to step 2602 and re-execute the previously described steps 2602 to 2610.

[0342] For example, method 2600 can be re-executed in order to test the second, third, fourth, fifth or other parts of the cryogen flow path.Method 2600 can be executed in order so that the subsequent downstream part of the cryogen flow path can be tested to verify the correct operation and integrity of the cryogen flow path.In order to perform the verification of the subsequent part, diagnostic control 2240 can open the valve of the previously verified part downstream and pressurize the downstream part.This process can be repeated in order to pressurize the adjacent downstream part and test whether these parts have flow problems.

[0343] The description of the foregoing embodiments is provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the present disclosure. The individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but where applicable, they are interchangeable and can be used in the selected embodiment even if not specifically shown or described. It can also be changed in a variety of ways. Such changes should not be considered as departing from the present disclosure, and all such modifications are intended to be included within the scope of the present disclosure.

[0344] The following is a list of non-limiting illustrative embodiments disclosed herein:

[0345] Illustrative embodiment 1: A cryoablation device comprising:

[0346] a dewar defining an interior volume configured to hold a volume of cryogen;

[0347] a supply tube extending into the interior volume of the Dewar;

[0348] a heating assembly positioned within the interior volume proximate the supply tube; and

[0349] A pump assembly is positioned within the interior volume and operably coupled to the supply tube.

[0350] Illustrative Embodiment 2: The cryoablation device of Illustrative Embodiment 1, wherein the heating assembly is positioned proximate to the supply tube.

[0351] Illustrative embodiment 3: The cryoablation device according to any of the preceding illustrative embodiments, wherein the distal end of the supply tube is positioned near the bottom of the Dewar, and the pump is positioned near the distal end of the supply tube.

[0352] Illustrative embodiment 4: The cryoablation device according to any one of the preceding illustrative embodiments, wherein the heating assembly comprises:

[0353] a bubble barrier comprising at least one wall defining a heating boundary; and

[0354] A heater is positioned within the bubble barrier.

[0355] Illustrative Embodiment 5: The cryoablation device of Illustrative Embodiment 4, wherein the distal end of the supply tube is positioned above the bubble barrier.

[0356] Illustrative Embodiment 6: The cryoablation device according to any one of Illustrative Embodiments 4 or 5, further comprising at least one pressure sensor positioned within the bubble barrier.

[0357] Illustrative embodiment 7: The cryoablation device according to any one of the preceding illustrative embodiments, further comprising a pressure controller operably coupled to the heating assembly and the pump assembly, the pressure controller being configured to:

[0358] The heater is activated and deactivated to maintain the refrigerant supplied to the supply pipe at a pressure within a first predetermined operating range.

[0359] Illustrative Embodiment 8: The cryoablation device according to Illustrative Embodiment 7, wherein the pressure controller is further configured to operate the pump assembly to pressurize the cryogen at the outlet of the pump to a pressure within a second predetermined operating range.

[0360] Illustrative Embodiment 9: The cryoablation device according to any one of Illustrative Embodiments 7 or 8, wherein the first predetermined operating range is a low pressure range, and the second predetermined operating range is a high pressure range.

[0361] Illustrative Embodiment 10: The cryoablation device according to any one of the preceding illustrative embodiments, wherein the cryogen is nitrogen.

[0362] Illustrative embodiment 11: According to any of the aforementioned illustrative embodiments, the cryoablation device also includes a capacitance-based cryogen level sensor positioned in the dewar, and the capacitance-based cryogen level sensor is configured to provide a cryogen level of the cryogen in the dewar.

[0363] Illustrative Embodiment 12: The cryoablation device of Illustrative Embodiment 11, wherein the capacitance-based cryogen liquid sensor comprises a cryogen rod extending within the interior volume of the Dewar.

[0364] Illustrative Embodiment 13: The cryoablation device of Illustrative Embodiment 12, wherein the cryogen rod comprises a first capacitor surface and a second capacitor surface, the first capacitor surface being concentrically positioned around the second capacitor surface and defining an annular cavity therebetween.

[0365] Illustrative embodiment 14: According to any one of illustrative embodiments 11 to 13, the cryoablation device also includes a control circuit coupled to the capacitance-based cryogen level sensor, and the control circuit is configured to continuously charge and discharge the capacitance-based cryogen level sensor during the cryoablation cycle to continuously determine the cryogen level in the Dewar flask.

[0366] Illustrative Embodiment 15: The cryoablation device of any one of Illustrative Embodiments 11 to 14, wherein the capacitance-based fluid level sensor is positioned on the supply tube.

[0367] Illustrative Embodiment 16: The cryoablation device of any one of Illustrative Embodiments 11 to 15, wherein the capacitance-based level sensor is configured to provide the cryogen level for any cryogen level along the length of the capacitance-based level sensor.

[0368] Illustrative Example 17: A method of pressurizing a cryogen, comprising:

[0369] obtaining Dewar pressure information indicative of a pressure of a cryogen in the Dewar;

[0370] maintaining the pressure of the cryogen in the Dewar vessel within a first pressure range using a heating assembly in the Dewar vessel;

[0371] obtaining pump pressure information indicative of a pressure of the refrigerant at an outlet of the pump; and

[0372] maintaining the pressure of the refrigerant at the outlet of the pump within a second pressure range using the pump;

[0373] Wherein the step of maintaining the pressure of the cryogen in the Dewar vessel and the step of maintaining the pressure of the cryogen at the outlet of the pump are performed simultaneously.

[0374] Illustrative Embodiment 18: The method of Illustrative Embodiment 17, wherein the first pressure range comprises a low pressure range and the second pressure range comprises a high pressure range.

[0375] Illustrative Embodiment 19: The method of any of Illustrative Embodiments 17 or 18, wherein the first pressure range comprises a range of about 10 psi to about 15 psi.

[0376] Illustrative Embodiment 20: The method of any one of Illustrative Embodiments 17 to 19, wherein the second pressure range comprises a range of about 400 psi to about 600 psi.

[0377] Illustrative Embodiment 21: The method of any one of Illustrative Embodiments 17 to 20, wherein the step of maintaining the pressure of the cryogen in the Dewar vessel is performed using the heating assembly, the heating assembly comprising:

[0378] a bubble barrier comprising at least one wall defining a heating boundary; and

[0379] A heater is positioned within the bubble barrier.

[0380] Illustrative Embodiment 22: The method of any one of Illustrative Embodiments 17 to 20, wherein a trained machine learning model is used to determine the operating parameters of the heater assembly.

[0381] Illustrative Embodiment 23: The method of any one of Illustrative Embodiments 17 to 22, wherein the cryogen is nitrogen.

[0382] Illustrative embodiment 24: The method according to any one of illustrative embodiments 17 to 23, further comprising:

[0383] obtaining capacitance from a capacitance-based level sensor in a Dewar flask; and

[0384] The refrigerant level is determined based on the capacitance.

[0385] Illustrative Embodiment 25: The method of Illustrative Embodiment 24, wherein the step of obtaining the capacitance is performed while moving liquid cryogen through the capacitance-based liquid level sensor.

[0386] Illustrative Embodiment 26: The method of any one of Illustrative Embodiments 24 or 25, wherein the step of determining the refrigerant level is performed using a trained machine learning model.

[0387] Illustrative Embodiment 27: The method of any one of Illustrative Embodiments 24 to 26, further comprising: sending a refrigerant level warning if the refrigerant level is below a predetermined level.

[0388] Illustrative Embodiment 28: The method of any one of Illustrative Embodiments 24 to 27, wherein the step of obtaining the capacitance comprises: continuously charging and discharging the capacitance-based fluid level sensor during a cryoablation cycle.

[0389] Illustrative Embodiment 29: The method of any one of Illustrative Embodiments 24 to 28, wherein the capacitance-based liquid level sensor comprises a cryogen rod extending in the Dewar.

Claims

1. A cryoablation device, comprising: a dewar defining an interior volume configured to hold a volume of cryogen; a supply tube extending into the interior volume of the Dewar; a heating assembly positioned within the interior volume proximate the supply tube; as well as A pump assembly is positioned within the interior volume and operably coupled to the supply tube.

2. The cryoablation device of claim 1, wherein a distal end of the supply tube is positioned near the bottom of the Dewar, and the pump is positioned near the distal end of the supply tube.

3. The cryoablation device according to claim 1, wherein the heating assembly comprises: a bubble barrier comprising at least one wall defining a heating boundary; as well as A heater is positioned within the bubble barrier.

4. The cryoablation device of claim 2, wherein the distal end of the supply tube is positioned above the bubble barrier.

5. The cryoablation device of claim 3, further comprising at least one pressure sensor positioned within the bubble barrier.

6. The cryoablation apparatus of claim 5, further comprising a pressure controller operably coupled to the heating assembly and the pump assembly, the pressure controller being configured to: The heater is activated and deactivated to maintain the refrigerant supplied to the supply pipe at a pressure within a first predetermined operating range.

7. The cryoablation device of claim 6, wherein the pressure controller is further configured to operate the pump assembly to pressurize the refrigerant at an outlet of the pump to a pressure within a second predetermined operating range.

8. The cryoablation device according to claim 7, wherein the first predetermined operating range is a low pressure range, and the second predetermined operating range is a high pressure range.

9. The cryoablation device of claim 7, wherein the cryogen is nitrogen.

10. The cryoablation device of claim 1, further comprising a capacitance-based cryogen level sensor positioned in the dewar, the capacitance-based cryogen level sensor configured to provide a cryogen level of the cryogen in the dewar.

11. The cryoablation device of claim 10, wherein the capacitance-based cryogen liquid sensor comprises a cryogen rod extending within the interior volume of the Dewar.

12. The cryoablation device of claim 11, wherein the cryogen rod comprises a first capacitor surface and a second capacitor surface, the first capacitor surface being concentrically positioned around the second capacitor surface and defining an annular cavity therebetween.

13. The cryoablation device according to claim 12 further includes a control circuit coupled to the capacitance-based cryogen level sensor, and the control circuit is configured to continuously charge and discharge the capacitance-based cryogen level sensor during the cryoablation cycle to continuously determine the cryogen level in the Dewar bottle.

14. The cryoablation device of claim 10, wherein the capacitance-based fluid level sensor is positioned on the supply tube.

15. The cryoablation device of claim 10, wherein the capacitance-based level sensor is configured to provide the cryogen level for any cryogen level along a length of the capacitance-based level sensor.

16. A method of pressurizing a cryogen, comprising: obtaining Dewar pressure information indicative of a pressure of a cryogen in the Dewar; maintaining the pressure of the cryogen in the Dewar vessel within a first pressure range using a heating assembly in the Dewar vessel; obtaining pump pressure information indicative of a pressure of the refrigerant at an outlet of the pump; and maintaining the pressure of the refrigerant at the outlet of the pump within a second pressure range using the pump; Wherein the step of maintaining the pressure of the cryogen in the Dewar vessel and the step of maintaining the pressure of the cryogen at the outlet of the pump are performed simultaneously.

17. The method of claim 16, wherein the first pressure range comprises a low pressure range and the second pressure range comprises a high pressure range.

18. The method of claim 16, wherein the first pressure range comprises a range of about 10 psi to about 15 psi.

19. The method of claim 16, wherein the second pressure range comprises a range of about 400 psi to about 600 psi.

20. The method of claim 16, wherein the step of maintaining the pressure of the cryogen in the Dewar vessel is performed using the heating assembly, the heating assembly comprising: a bubble barrier comprising at least one wall defining a heating boundary; as well as A heater is positioned within the bubble barrier.

21. The method of claim 16, wherein a trained machine learning model is used to determine operating parameters of the heater assembly.

22. The method of claim 16, wherein the cryogen is nitrogen.

23. The method of claim 16, further comprising: Capacitance is obtained from a capacitance-based level sensor in a Dewar flask; as well as The refrigerant level is determined based on the capacitance.

24. The method of claim 23, wherein the step of obtaining the capacitance is performed while moving liquid cryogen through the capacitance-based liquid level sensor.

25. The method of claim 23, wherein the step of determining the refrigerant level is performed using a trained machine learning model.

26. The method according to claim 23, further comprising: If the refrigerant level is below a predetermined level, a refrigerant level warning is sent.

27. The method according to claim 23, wherein the step of obtaining the capacitance comprises: The capacitance-based fluid level sensor is continuously charged and discharged during the cryoablation cycle.

28. The method of claim 23, wherein the capacitance-based liquid level sensor comprises a cryogen rod extending within the Dewar.

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