A cryoablation system

Abstract

The utility model belongs to the technical field of medical apparatus and instruments, disclose a kind of cryoablation system, including gas source, heat exchange capillary and evaporator, wherein, gas source medium is the nitrogen monoxide containing moisture, cryoablation system includes drying filter;The drying filter has air inlet and air outlet, the air inlet is connected with the gas source, and the air outlet is connected with the heat exchange capillary;The heat exchange capillary exchanges heat with the evaporator;The drying filter is filled with drying material that can absorb water molecules in gas source medium and is suitable for nitrogen monoxide molecule free passage, to remove the moisture in gas source medium that passes through drying filter.The utility model is by additionally providing drying filter, effectively reduce the risk that pipeline occurs blockage, improve balloon temperature and air inlet pressure curve smooth, be conducive to the judgment of operator, ensure the stability of operation.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and in particular to a cryoablation system. Background Technology

[0002] Cryoablation is widely used to treat rapid arrhythmias, such as atrial fibrillation (AF). Its working principle involves the endothermic evaporation of a liquid gaseous medium, which removes heat from the tissue, lowering the temperature of the target ablation site and "freezing" the cells, thereby destroying areas of abnormal electrophysiological activity and achieving the goal of treating the arrhythmia. Extensive clinical data show that compared to other ablation methods, cryoablation is easier for doctors to learn and perform, can shorten operation time, has high treatment effectiveness, reduces serious complications such as thrombosis, and lowers patient pain.

[0003] Currently, the gas source medium used in cryoablation systems is generally nitrous oxide (also known as liquid nitrogen) or liquid nitrogen. These gas source media are stored in gas cylinders through high-pressure sealing. Although there are certain requirements for the water content and purity of the gas source medium in the cylinders, there may still be some moisture in the cylinders. This moisture is prone to freezing into ice slag when passing through the heat exchange tubes of the cryoablation equipment's pre-cooling system due to the low temperature. Since both the balloon catheter and the heat exchange capillary tube use thin tubes with a diameter of less than 1 mm, and the porous plug for the Joule-Thomson effect inside the balloon has an even smaller diameter, ice slag may cause blockage of the capillary tubes and the small holes of the liquid spraying orifice. When one or two of the multiple holes are blocked, it will cause an increase in the inlet pressure, resulting in poor cooling effect, temperature fluctuations, and other problems. This will affect the operator's judgment, making it impossible for them to select an effective freezing time. In severe cases, it may block the tubing, making the surgery impossible. Utility Model Content

[0004] The purpose of this application is to provide a cryoablation system that reduces the possibility of clogging in cryoablation equipment and improves the product reliability of cryoablation equipment.

[0005] The technical solution provided in this application is as follows:

[0006] A cryoablation system includes a gas source, a heat exchange capillary tube, and an evaporator, wherein the gas source medium is nitrous oxide containing moisture, and a drying filter is also included.

[0007] The drying filter has an air inlet and an air outlet. The air inlet is connected to the air source, and the air outlet is connected to the heat exchange capillary tube. The heat exchange capillary tube exchanges heat with the evaporator.

[0008] The drying filter is filled with a drying material that can adsorb water molecules in the gas source medium and allows nitrous oxide molecules to pass freely, in order to remove moisture from the gas source medium passing through the drying filter.

[0009] In some embodiments, the drying filter includes a cylindrical body, a first filter element, and a second filter element;

[0010] The cylinder has openings at both ends;

[0011] The first filter element is disposed at the first end opening of the cylinder;

[0012] The second filter element is disposed at the second end opening of the cylinder;

[0013] The cylinder, the first filter, and the second filter form a closed filtration cavity, which is filled with the drying material. The minimum particle size of the drying material is larger than the pore size of the first filter and the second filter.

[0014] The air inlet and the air outlet are respectively connected to the filter chamber.

[0015] In some embodiments, the first filter and the second filter are sintered metal sheets, and the pore size of the first filter and the second filter is in the range of 30μm-100μm, for passing through the medium in the gas source and intercepting the drying material.

[0016] In some embodiments, the drying filter further includes an end cap having a closed end and an open end;

[0017] The open end of the end cap is sealed to the second end opening of the cylinder, and the second filter is fixedly disposed inside the open end of the end cap. The side wall of the end cap is provided with a radial outlet, which is connected to the air outlet.

[0018] In some embodiments, the dryer filter further includes a housing that covers the cylinder and the end cap;

[0019] A first flow channel is formed between the inner wall of the outer shell and the outer wall of the cylinder. The radial outlet connects the filter chamber and the first flow channel, and the first flow channel connects to the air outlet.

[0020] In some embodiments, the dryer filter further includes a base, which is sealed to the housing, and the air inlet and the air outlet are disposed on the base;

[0021] The first end of the cylinder is sealed to the base, and the air inlet is connected to the outside of the first filter.

[0022] In some embodiments, the base includes a base body and a mounting part, and the side wall of the base body is provided with the air inlet and the air outlet;

[0023] The mounting part protrudes from the base body and has an assembly hole that communicates with the air inlet. The first end of the cylinder is inserted into the assembly hole, and a sealed connection is formed between the outer wall of the first end of the cylinder and the inner wall of the mounting part. An axial channel is provided on the mounting part outside the assembly hole, and the air outlet communicates with the first flow channel through the axial channel.

[0024] In some embodiments, the drying filter further includes a first pressure ring, which is fixedly disposed at the first end opening of the cylinder and located on the side of the first filter sheet away from the filter chamber, for axially fixing the first filter sheet.

[0025] In some embodiments, the drying filter further includes a second pressure ring disposed at the open end of the end cap and located on the side of the second filter sheet near the cylinder, for axially fixing the second filter sheet.

[0026] In some embodiments, the drying material is a 4A molecular sieve, and the particle size range of the 4A molecular sieve is 0.5 mm to 1 mm.

[0027] The technical advantages of this application are as follows: by adding a drying filter filled with drying material between the gas source and the heat exchange capillary of the cryoablation system, the drying material can adsorb water molecules and allow nitrous oxide molecules to pass freely, which can effectively reduce the moisture content in the gas source medium, thereby reducing the risk of pipeline blockage. This not only improves the stability of the balloon temperature and inlet pressure curve, which is beneficial for the operator to make judgments and improves the success rate of the operation, but also ensures the stability of the operation. Attached Figure Description

[0028] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] Figure 1 This is a schematic diagram of a cryoablation system provided in one embodiment of this application;

[0030] Figure 2 This is a piping connection diagram of a cryoablation system provided in one embodiment of this application;

[0031] Figure 3 This is a partial structural schematic diagram of a cryoablation system provided in one embodiment of this application;

[0032] Figure 4 This is an enlarged view of the distal end of the balloon inner tube provided in one embodiment of this application;

[0033] Figure 5 This is a cross-sectional view of a drying filter provided in an embodiment of this application;

[0034] Figure 6 This is a schematic diagram of the structure of a drying filter provided in another embodiment of this application;

[0035] Figure 7 yes Figure 6 An exploded view of the drying filter shown in the diagram;

[0036] Figure 8 This is a schematic diagram of the structure of the outer casing provided in one embodiment of this application;

[0037] Figure 9 This is a schematic diagram of the structure of a base provided in one embodiment of this application;

[0038] Figure 10 This is a schematic diagram of the structure of a drying filter provided in another embodiment of this application;

[0039] Figure 11 yes Figure 10 A cross-sectional view of the drying filter shown;

[0040] Figure 12 This is a comparison chart of the water absorption rates of different molecular sieves provided in an embodiment of this application;

[0041] Figure 13 This is a comparison diagram of the balloon temperature curves of the cryoablation system provided in one embodiment of this application during the ablation process;

[0042] Figure 14 This is a comparison diagram of the intake pressure curves of the cryoablation system provided in one embodiment of this application in the ablation state;

[0043] Figure 15 This is a comparison chart of the blockage probability of the cryoablation system provided in an embodiment of this application under different conditions.

[0044] Explanation of icon numbers:

[0045] 10. Gas cylinder; 20. Heat exchange capillary tube; 22. Evaporator; 30. Coaxial tube; 310. Coaxial inner tube; 320. Coaxial outer tube; 40. Balloon conduit; 410. Balloon inner tube; 411. Liquid spray hole; 420. Balloon outer tube; 50. Balloon; 60. Cold liquid output connector; 70. Stainless steel tube;

[0046] 100. Dryer filter; 101. Air inlet; 102. Air outlet; 103. One-way valve; 104. Filter chamber; 110. Cylinder; 120. First filter element; 130. Second filter element; 140. End cap; 141. Radial outlet; 151. First sealing ring; 152. Second sealing ring; 153. Third sealing ring; 160. Outer shell; 161. First flow channel; 170. Base; 171. Base body; 172. Mounting part; 1721. Assembly hole; 1722. Axial channel; 180. Bracket; 191. First pressure ring; 192. Second pressure ring. Detailed Implementation

[0047] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application can also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0048] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the specific implementation methods of this application will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without creative effort.

[0049] To keep the drawings concise, each drawing only schematically shows the parts relevant to this application, and they do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of the components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0050] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0051] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linkage" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; or they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0052] In the embodiments shown in the accompanying drawings, the directional indications (such as up, down, left, right, front, and back) are relative rather than absolute when describing the structure and movement of the various components, and are not intended to limit the direction of the product during actual use.

[0053] Furthermore, in the description of this application, ordinal numbers, such as "first" and "second," are used only to distinguish related objects and should not be construed as indicating or implying the relative importance or order between related objects.

[0054] In this application, the terms "proximal" and "distal" refer to the relative orientation, position, and direction of elements or movements relative to each other from the perspective of a physician using the medical device. Although "proximal" and "distal" are not restrictive, "proximal" generally refers to the end of the medical device that is closer to the physician during normal operation, while "distal" generally refers to the end that first enters the patient's body.

[0055] like Figure 1 and Figure 2 As shown, in one or more embodiments, this disclosure provides a cryoablation system, including a gas source, a heat exchange capillary tube 20, and an evaporator 22, wherein the gas source medium is nitrous oxide containing moisture, and the cryoablation system includes a drying filter 100; the drying filter 100 has an inlet 101 and an outlet 102, the inlet 101 is connected to the gas source, and the outlet 102 is connected to the heat exchange capillary tube 20; the heat exchange capillary tube 20 exchanges heat with the evaporator 22; the drying filter 100 is filled with a drying material that can adsorb water molecules in the gas source medium and is suitable for the free passage of nitrous oxide molecules, so as to remove moisture from the gas source medium passing through the drying filter 100.

[0056] like Figure 1 As shown, the cryoablation system includes a dryer filter 100, a gas source, a heat exchange capillary tube 20, an evaporator 22, a coaxial tube 30, a balloon conduit 40, and a balloon 50. The dryer filter 100 has an inlet 101 and an outlet 102. The gas source includes a gas cylinder 10 and a gas medium disposed within the gas cylinder 10. The inlet 101 is used to connect to the gas cylinder 10. The coaxial tube 30 includes a coaxial inner tube 310 and a coaxial outer tube 320. The balloon conduit... 40 includes a balloon inner tube 410 and a balloon outer tube 420 arranged coaxially; the air outlet 102 of the dryer filter 100, the heat exchange capillary tube 20, the coaxial inner tube 310 and the balloon inner tube 410 are connected in sequence; the distal end of the balloon inner tube 410 extends into the balloon 50 for injecting gas source medium into the balloon 50; the distal end of the balloon outer tube 420 is connected to the balloon 50, and the proximal end of the balloon outer tube 420 is connected to the coaxial outer tube 320 for recovering the gas source medium.

[0057] The cryoablation system in this embodiment employs a dual-cycle composite refrigeration architecture, comprising two subsystems: a closed-loop phase-change refrigeration cycle (i.e., a compressor pre-cooling system) and an open-loop Joule-Thomson refrigeration cycle. The compressor pre-cooling system is a conventional refrigeration system, including an evaporator 22. A heat exchange capillary tube 20 exchanges heat with the evaporator 22 to lower the temperature of the gas source medium within the capillary tube 20. In the open-loop refrigeration subsystem, this embodiment uses nitrous oxide (N2O) as the gas source medium. Due to physical limitations in the manufacturing process of the gas cylinder 10, limitations in the filling process, and cost considerations, the initial gas source medium still contains trace amounts of residual moisture. These trace amounts of moisture may still pose a risk of pipe icing and blockage in the subsequent low-temperature region. Furthermore, the system pipes have a small inner diameter. When the gas source medium containing trace amounts of moisture flows through the evaporator of the refrigeration system, under low-temperature conditions, the trace moisture will undergo phase change crystallization within the heat exchange capillary tube, producing tiny ice crystals that flow in the pipes, potentially causing blockage and affecting the normal progress of the cryoablation procedure.

[0058] In this embodiment, the cryoablation system adds a drying filter 100 after the gas cylinder 10. The gas source medium flows out from the high-pressure gas cylinder 10 and undergoes thorough drying treatment through the drying filter 100, reducing its water content from 20 ppm to 1-5 ppm, thus reducing the risk of pipeline blockage to near zero. Then, the gas source medium passes through the heat exchange capillary tube 20, which is located in the evaporator of the closed-loop refrigeration subsystem. Here, the gas source medium exchanges energy with the low-temperature region of the closed-loop refrigeration subsystem, thereby completing cryogenic liquefaction, and flows into the coaxial inner tube 310 of the coaxial tube 30. The cryogenically liquefied gas source medium then flows into the inner tube 410 of the balloon catheter 40, and is sprayed into the balloon 50 at the end of the balloon 50 to exert the Joule-Thomson effect, causing the temperature of the balloon 50 to drop sharply, freezing the tissue cells adjacent to the balloon 50, and completing the cryotherapy. The distal end of the balloon outer tube 420 of the balloon catheter 40 is connected to the balloon 50, and the proximal end of the balloon outer tube 420 is connected to the coaxial outer tube 320. The gas source medium in the balloon 50 is recovered through the balloon outer tube 420 and the coaxial outer tube 320 and enters the designated waste gas recirculation system.

[0059] Furthermore, in this embodiment, as Figure 3As shown, the front end of the dryer filter 100 is equipped with a one-way valve 103. The gas source medium enters the dryer filter 100 through the one-way valve 103 at the front end, and then flows out into other components such as the heat exchange capillary tube 20. If the gas cylinder 10 needs to be replaced during the operation, the one-way valve 103 can retain the gas inside the dryer filter 100 during the rapid replacement of the gas cylinder 10, preventing excessive gas from being released into the operating room. When the gas cylinder 10 is not connected, the one-way valve 103 can also prevent the desiccant inside the dryer filter 100 from directly contacting the air, thereby preventing the desiccant from absorbing moisture from the air and avoiding the desiccant from becoming ineffective in a short time.

[0060] In this embodiment, by setting a drying filter filled with drying material between the gas cylinder 10 and the heat exchange capillary tube 20, moisture in the gas source medium can be removed, reducing the risk of pipeline blockage. This not only improves the stability of the balloon temperature and inlet pressure curve, which is beneficial for the surgeon to make judgments and improves the success rate of the operation, but also ensures the stability of the operation.

[0061] Preferably, the inner diameters of the heat exchange capillary tube 20, the coaxial inner tube 310, and the balloon inner tube 410 decrease sequentially. That is, the cryoablation system adopts a staged depressurization design; the gas source medium passes through pipes with gradually decreasing inner diameters to achieve depressurization and liquefaction of the gas source medium, while ensuring the cooling capacity of the gas source medium within the balloon 50. Preferably, the inner diameter of the heat exchange capillary tube 20 is less than 1 mm.

[0062] In the cryogenic ablation system, the heat exchange capillary tube 20 and the coaxial tube 30 are connected by a cold liquid outlet connector 60. One end of the heat exchange capillary tube 20 is provided with a female connector of the cold liquid outlet connector 60, and one end of the coaxial tube 30 is provided with a male connector of the cold liquid outlet connector 60. After the male and female connectors are inserted, the heat exchange capillary tube 20 and the coaxial inner tube 310 of the coaxial tube 30 are connected. The cold liquid outlet connector 60 is also provided with an external discharge port, through which the gas source medium recovered from the coaxial outer tube 320 is discharged into a designated waste gas recirculation system.

[0063] Furthermore, such as Figure 2 As shown, a stainless steel pipe 70 is also provided between the dryer filter 100 and the heat exchange capillary tube 20. After the gas source medium comes out of the dryer filter 100, it first enters the stainless steel pipe 70 for gas transportation. The diameter of the stainless steel pipe is greater than 6mm to facilitate the transportation of the gas source medium. Then it enters the heat exchange capillary tube 20.

[0064] like Figure 4As shown, a spray hole 411 is provided at the distal end of the inner tube 410 of the balloon 50. The spray hole 411 is located inside the balloon 50 and is used to spray the gas source medium into the balloon 50. The diameter of the spray hole 411 is smaller than the inner diameter of the inner tube 410 of the balloon, so as to facilitate the Joule-Thomson effect inside the balloon 50, causing the temperature of the balloon 50 to drop sharply, freezing the tissue cells adjacent to the balloon 50, and completing the cryotherapy. The diameter of the spray hole 411 is even smaller, so ice fragments may cause blockage of the spray hole 411. When one or more spray holes 411 are blocked, it will cause an increase in the inlet pressure, resulting in poor cooling effect. It may also cause fluctuations in gas flow, causing changes in cooling temperature and interfering with the operator's judgment. Therefore, after the gas source medium is output from the gas cylinder 10, it needs to be deeply dehumidified by a special drying filter 100 to reduce the possibility of blockage in the cryoablation pipeline and improve the product reliability of the cryoablation equipment.

[0065] In some embodiments, such as Figure 5 As shown, the dryer filter 100 includes a cylindrical body 110, a first filter element 120, and a second filter element 130; the cylindrical body 110 has openings at both ends; the first filter element 120 is disposed at the first end opening of the cylindrical body 110; the second filter element 130 is disposed at the second end opening of the cylindrical body 110; the cylindrical body 110, the first filter element 120, and the second filter element 130 surround to form a closed filter cavity 104, which is filled with a drying material, the minimum particle size of which is larger than the pore size of the first filter element 120 and the second filter element 130; the air inlet 101 and the air outlet 102 are respectively connected to the filter cavity 104.

[0066] In this embodiment, the overall structure of the cylinder 110 is columnar with a hollow core. Its cross-section can be circular, elliptical, or rectangular, etc. The material of the cylinder 110 needs to have good pressure resistance and corrosion resistance to adapt to the operating environment of the gas source medium in the cryogenic ablation equipment. Preferably, in this embodiment, the material of the cylinder 110 is SUS316, which is not only resistant to nitrous oxide corrosion but also has high structural strength and is not prone to rust.

[0067] The cylinder 110 has openings at both ends along the axial direction. A first filter 120 is provided at one end of the opening of the cylinder 110, and a second filter 130 is provided at the other end. The first filter 120 and the second filter 130 are tightly fitted with the cylinder 110 to form a closed filter chamber 104. The first filter 120 and the second filter 130 have the same structure, both being porous metal filter sheets. For example, the first filter 120 and the second filter 130 are made of copper powder sintered and have a microporous structure. The pore size of the first filter 120 and the second filter 130 ranges from 30μm to 100μm, which is smaller than the diameter of the drying material. This allows the gas source medium to pass through and intercept the drying material, so that the gas source medium can enter the filter chamber 104 through the filter sheets and confine the drying material within the filter chamber 104. This prevents the drying material from entering the pipeline with the flow of the gas source medium, which not only prevents the drying material from leaking and causing pipeline blockage, but also blocks larger particles of impurities from entering the filter chamber 104, thereby protecting the drying material from contamination by impurities, extending the service life of the drying material, and further improving the purity of the gas source medium.

[0068] The air inlet 101 and air outlet 102 of the dryer filter 100 are respectively connected to the filter chamber 104. In this embodiment, an air inlet pipe can be connected to the outside of the first filter 120, and an air outlet pipe can be connected to the outside of the second filter 130. The air inlet 101 is set on the air inlet pipe, and the air outlet 102 is set on the air outlet pipe. The air inlet pipe and the air outlet pipe are respectively connected to the filter chamber 104. The gas source medium flows out of the gas cylinder 10 and enters the air inlet pipe, then passes through the first filter 120 and enters the cylinder 110. In the filter chamber 104, the gas source medium is dried and filtered by the drying material, then flows out of the filter chamber 104 from the second filter 130 and enters the air outlet pipe, and finally flows into the heat exchange capillary tube 20 through the air outlet pipe, so as to reduce the moisture content in the gas source medium from 20ppm to 1-5ppm and reduce the possibility of ice blockage in the pipeline.

[0069] In some embodiments, such as Figure 6 , Figure 7 and Figure 8 As shown, the dryer filter 100 also includes an end cap 140, which has a closed end and an open end. The open end of the end cap 140 is sealed to the second end opening of the cylinder 110, and the second filter 130 is fixedly disposed inside the open end of the end cap 140. The side wall of the end cap 140 is provided with a radial outlet 141, which communicates with the air outlet 102.

[0070] In this embodiment, the end cap 140 can be fixed to the second end opening of the cylinder 110 by means of threaded connection, snap-fit, etc. The second filter 130 is disposed inside the open end of the end cap 140, that is, the second filter 130 is installed at the second end opening of the cylinder 110 through the end cap 140. The second filter 130 and the end cap 140 can form an integral unit. When replacing the drying material inside the cylinder 110, it is only necessary to remove the end cap 140 as a whole from the cylinder 110. This method is easier to operate than directly disassembling the filter, so as to facilitate maintenance and replacement of the drying material and improve maintainability. There is a certain distance between the closed end of the end cap 140 and the second filter 130 to form a cavity inside the end cap 140, which can play a role in buffering or rectifying.

[0071] In this embodiment, the end cap 140 is made of SUS316 stainless steel and is cylindrical in shape, closed at one end and open to the outside at the other. A stepped portion is provided on the inner wall of the cylinder 110 to restrict the position of the end cap 140. A groove for installing the first sealing ring 151 is provided on the outer wall of the end cap 140. The first sealing ring 151 is installed in the groove to achieve a sealed connection between the end cap 140 and the cylinder 110. The first sealing ring 151 is made of nitrile rubber, which is resistant to nitrous oxide corrosion, has good elasticity, and good sealing performance, thus serving to seal against nitrous oxide.

[0072] In some embodiments, such as Figure 8 and Figure 11 As shown, the dryer filter 100 also includes a housing 160, which covers the cylinder 110 and the end cap 140. A first flow channel 161 is formed between the inner wall of the housing 160 and the outer wall of the cylinder 110. The radial outlet 141 connects the filter chamber 104 and the first flow channel 161, and the first flow channel 161 connects to the air outlet 102.

[0073] The outer casing 160 covers the cylinder 110 and end cap 140, providing protection for them. A first flow channel 161 is formed between the inner wall of the outer casing 160 and the outer wall of the cylinder 110. The first flow channel 161 provides additional flow space for the gas source medium, allowing it to flow more smoothly during the filtration process. The design of the first flow channel 161 helps reduce the flow resistance of the gas source medium inside the dryer filter 100, reducing pressure loss and thus improving filtration efficiency.

[0074] The end cap 140 has a radial outlet 141 on its side wall, which connects the filter chamber 104 and the first flow channel 161. The radial outlet 141 allows the dried and filtered gas medium to flow from the filter chamber 104 into the first flow channel 161, thus redirecting the gas medium and extending its flow path within the dryer filter 100. This design makes the flow of the gas medium within the dryer filter 100 more uniform, helps improve the adsorption effect of the drying material, and ensures that moisture in the gas medium is removed more thoroughly.

[0075] In this embodiment, the outer shell 160 is made of SUS316 stainless steel, integrally machined, and features high structural strength, corrosion resistance, high dimensional accuracy, and high hardness. The outer shell 160 serves to protect and secure the internal structure. In other embodiments, the outer shell 160 may also be made of other metal materials.

[0076] In some embodiments, such as Figures 9 to 11 As shown, the dryer filter 100 also includes a base 170, which is sealed to the outer shell 160. An air inlet 101 and an air outlet 102 are disposed on the base 170. The first end of the cylinder 110 is sealed to the base 170, and the air inlet 101 is connected to the outside of the first filter 120. The air inlet 101 is connected to the filter chamber 104 to form a second flow channel. The first flow channel 161 and the second flow channel form a U-shaped flow channel.

[0077] The base 170 is fixedly connected to the outer shell 160, forming an integral structure that provides stable support for the cylinder 110. In this embodiment, the base 170 is made of SUS316 stainless steel, integrally machined, and has high structural strength, corrosion resistance, high dimensional accuracy, and high hardness. In other embodiments, the base 170 may also be made of other metal materials.

[0078] The upper end of the outer shell 160 is cylindrical and hollow inside to accommodate the cylinder 110 and the end cap 140. The other end of the outer shell 160 is cuboid. The base 170 has multiple threaded through holes at corresponding positions. Screws pass through the through holes on the outer shell 160 and the base 170 to achieve a fixed connection between the outer shell 160 and the base 170.

[0079] A right-angled bracket 180 is screwed to the outside of the base 170. The right-angled bracket 180 facilitates the fixing of the dryer filter to other structures. In this embodiment, by setting the installation direction of the cylinder 110 and the base 170, the cylinder 110 and the outer shell 160 are perpendicular to the horizontal plate of the bracket 180, which facilitates the subsequent installation and replacement of the molecular sieve inside the dryer filter 100. The bracket 180 is made of sheet metal with a certain thickness, and the material is SUS316, which is not only resistant to nitrous oxide corrosion, but also has high structural strength and is not easy to rust.

[0080] During operation, the high-pressure gas medium, nitrous oxide, first enters the dryer filter 100 through the one-way valve 103. Then, it passes through the first filter element 120 between the base 170 and the cylinder 110, entering the filter chamber 104 of the cylinder 110. After thorough drying by contact with the drying material in the filter chamber 104, it flows out through the second filter element 130 between the end cap 140 and the cylinder 110. Subsequently, it flows from the radial outlet 141 on the end cap 140 into the first flow channel 161 between the cylinder 110 and the outer shell 160, and finally flows out through the outlet 102 on the base 170, entering other components of the system. In other words, the gas medium is first dried and filtered through the second flow channel, and then discharged from the dryer filter 100 through the first flow channel 161. This U-shaped flow path design, with its up-and-down reversal, makes the flow of the gas medium inside the dryer filter 100 more orderly and smooth, avoiding stagnation and short-circuiting within the dryer filter 100, thus improving filtration efficiency and quality. Furthermore, the dryer filter 100 in this embodiment is designed to minimize its volume, thereby reducing the premature vaporization of the gas source medium in the pipeline in a gas-liquid mixed state.

[0081] In this embodiment, the base 170 is provided with an air inlet 101 and an air outlet 102, so that the air inlet channel and the air outlet channel of the dryer filter 100 are integrated on the base 170, which simplifies the connection between the dryer filter 100 and the external pipeline and reduces the risk of air source medium leakage.

[0082] In some embodiments, such as Figure 9 As shown, the base 170 includes a base body 171 and a mounting part 172. The side wall of the base body 171 is provided with an air inlet 101 and an air outlet 102. The mounting part 172 protrudes from the base body 171 and is provided with an assembly hole 1721 communicating with the air inlet 101. The first end of the cylinder 110 is inserted into the assembly hole 1721, and a sealed connection is formed between the outer wall of the first end of the cylinder 110 and the inner wall of the mounting part 172. An axial channel 1722 is provided on the mounting part 172 outside the assembly hole 1721, and the air outlet 102 is connected to the first flow channel 161 through the axial channel 1722.

[0083] The mounting part 172 is cylindrical, with an assembly hole 1721 in the middle, which communicates with the air inlet 101. The mounting part 172 extends into the gap between the cylinder 110 and the outer shell 160 to seal the opening end of the first flow channel 161. An axial channel 1722 is provided on the side wall of the mounting part 172, which communicates with the first flow channel 161 and the air outlet 102 on the base 170. A groove for installing the second sealing ring 152 is provided on the outer side wall of the mounting part 172. The second sealing ring 152 is installed in the groove. The side wall of the mounting part 172 is inserted into the outer shell 160, and the sealing connection between the outer shell 160 and the base 170 is achieved through the second sealing ring 152. The second sealing ring 152 is made of nitrile rubber, which is resistant to nitrous oxide corrosion, has good elasticity, and good sealing performance, thus playing the role of sealing nitrous oxide. The base 170 is rectangular in shape and has multiple through holes with a diameter of millimeters around its perimeter to reduce weight. Meanwhile, threaded through holes for the fixed connection between the base 170 and the outer shell 160 are located on the base body 171.

[0084] A groove for installing a third sealing ring 153 is provided on the outer side wall of the first end of the cylinder 110. After the third sealing ring 153 is installed in the groove, it is located between the outer side wall of the cylinder 110 and the inner side wall of the mounting hole 1721 to achieve a sealed connection between the cylinder 110 and the mounting part 172. The third sealing ring 153 is made of nitrile rubber, which has the characteristics of being resistant to nitrous oxide corrosion, having good elasticity, and having good sealing performance, and plays the role of sealing nitrous oxide.

[0085] In this embodiment, the mounting part 172 protrudes from the base body 171, and an assembly hole 1721 is provided inside the mounting part 172, which facilitates the insertion of the mounting part 172 between the cylinder 110 and the outer shell 160, thereby facilitating the sealing connection between the cylinder 110 and the mounting part 172, as well as the sealing connection between the mounting part 172 and the outer shell 160.

[0086] In some embodiments, such as Figure 11 As shown, the dryer filter 100 also includes a first pressure ring 191, which is fixedly disposed at the first end opening of the cylinder 110 and located on the side of the first filter 120 away from the filter chamber 104, for axially fixing the first filter 120.

[0087] In this embodiment, a stepped portion is provided inside the first end of the cylinder 110, and the inner side of the first filter element 120 is disposed on this stepped portion. A first pressure ring 191 is disposed on the outer side of the first filter element 120. The first pressure ring 191 is threadedly connected to the cylinder 110. After the first pressure ring 191 is fixed inside the cylinder 110, it can press and fix the first filter element 120 without obstructing the passage of the gas source medium. The first pressure ring 191 is a ring screw made of SUS316, which is not only resistant to nitrous oxide corrosion but also has high structural strength and is not easy to rust. In other embodiments, the first filter element 120 can also be directly fixed inside the cylinder 110 by welding, threaded connection, or other methods.

[0088] In some embodiments, such as Figure 11 As shown, the dryer filter 100 also includes a second pressure ring 192. The second pressure ring 192 is disposed at the open end of the end cap 140 and located on the side of the second filter element 130 near the cylinder 110, for axially fixing the second filter element 130. The structure of the second pressure ring 192 is the same as that of the first pressure ring 191. A stepped portion can be provided inside the end cap 140, and the inner side of the second filter element 130 is disposed on the stepped portion. The second pressure ring 192 is disposed on the outer side of the second filter element 130. The second pressure ring 192 can be threadedly connected to the cylinder 110. After the second pressure ring 192 is fixed inside the end cap 140, it can press and fix the second filter element 130. The second pressure ring 192 is a ring screw made of SUS316, which is not only resistant to nitrous oxide corrosion, but also has high structural strength and is not easy to rust. In other embodiments, the second filter element 130 can also be directly fixed inside the cylinder 110 by welding, threaded connection, or other methods.

[0089] In some embodiments, the drying material is 4A molecular sieve, with a particle size range of 0.5mm-1mm. The gas source medium, after being output from the high-pressure gas cylinder 10, undergoes deep dehumidification treatment through a specially designed drying filter 100. In this embodiment, the drying filter 100 innovatively uses 0.5mm-1mm 4A molecular sieves to dry and filter moisture in the gas source medium, significantly reducing the moisture content and preventing pipeline blockage. 4A molecular sieve is an alkali metal aluminosilicate with high adsorption capacity, strong selectivity, high static adsorption, and high temperature resistance. It can adsorb molecules with a critical diameter of no more than 4A, such as water, sulfur dioxide, and carbon dioxide, while not adsorbing molecules with a diameter greater than 4A. This selective adsorption characteristic means that 4A molecular sieves cannot effectively remove moisture from the gas source medium during the drying process, while retaining other small molecule components. During the research and development process, repeated experiments revealed that 0.5mm-1mm 4A molecular sieves have a suitable pore structure, selectively adsorbing H2O molecules while allowing N2O molecules to pass freely. Meanwhile, through experimental verification, the stability of the balloon temperature curve after adding 4A molecular sieves with a size of 0.5mm-1mm was effectively confirmed, reducing the risk of blockage.

[0090] like Figure 12 The image shows a comparison of the water absorption capacity of molecular sieves of different sizes and types. Desiccant 1 is 13X molecular sieve, and desiccant 2 is 4A molecular sieve with a size of 1-2 mm. Figure 12 As can be seen, 4A molecular sieves with a particle size range of 0.5mm-1mm exhibit the best water absorption performance. The smaller size of 4A molecular sieves with a particle size range of 0.5mm-1mm effectively increases the contact area between the gas source medium and the surface of the molecular sieve, reduces the voids in the molecular sieve core, and enhances the filtration effect. Although the water absorption performance of desiccant 1 is not significantly different from that of 4A molecular sieve, 13X molecular sieve is more expensive and has a higher regeneration temperature, which is not conducive to drying and other processes. Therefore, this embodiment uses 4A molecular sieves with a size range of 0.5mm-1mm as the desiccant, which not only has higher selectivity for water molecules but also allows for reuse, reducing operating costs. After high-temperature drying, 4A molecular sieves need to be sealed and stored to ensure they are not affected by moisture in the air. Simultaneously, strict usage period standards and process control procedures need to be set in the process control to ensure the recyclability of the 4A molecular sieves.

[0091] Figure 13 This is a comparison of balloon temperature profiles for cryoablation systems with and without a desiccant filter. Figure 13 In the diagram, the dashed line represents the temperature change curve of the balloon without using a drying filter, and the solid line represents the temperature change curve of the balloon using the drying filter of this embodiment. Figure 13As can be seen, when the drying filter 100 was not used and slight ice blockage occurred in the tubing, the temperature of the balloon 50 fluctuated irregularly, adversely affecting the operator's judgment of the occlusion effect and freezing time. The reason is that the moisture contained in the high-pressure gas cylinder 10, when it reaches the distal end of the balloon inner tube 410 through the heat exchange capillary tube 20, causes micro-blockage in the heat exchange capillary tube 20, the coaxial inner tube 310, or the balloon inner tube 410. This leads to fluctuations in the circulating gas, changes in the flow rate of the gas source medium reaching the balloon 50, and thus causes steady-state changes in the Joule-Thomson effect within the balloon 50, resulting in temperature fluctuations and poor cooling.

[0092] Figure 14 This is a comparison chart of the intake pressure curves for the cryoablation system with and without a filter dryer. Figure 14 In the diagram, the dashed line represents the intake pressure curve without using a dryer filter, and the solid line represents the intake pressure curve with the dryer filter of this embodiment. Figure 14 As can be seen, due to the lack of a drying filter, the pipeline became clogged. The gas inlet pressure required for the cryoablation system to reach the specified flow rate gradually increased from approximately 580 psi to approximately 650 psi. This not only wastes gas but also affects the steady-state circulation in the pipeline. In severe cases, the continuous accumulation of ice or excessive water content in cylinder 10 can directly clog the pipeline, rendering the ablation system unusable. Furthermore, since the blockage usually occurs inside relatively narrow pipelines, it cannot be cleared immediately. Typically, it takes about an hour for the ice in the pipeline to melt naturally and be flushed out before the pipeline can be cleared, significantly prolonging the normal operation time and potentially leading to its cancellation. However, by using the drying filter filled with 0.5mm-1mm 4A molecular sieves in this embodiment, fluctuations in the temperature and pressure curves caused by minor ice blockage are eliminated, making it easier for the surgeon to make judgments and for the operation to proceed smoothly.

[0093] like Figure 15 As shown, experiments were conducted simultaneously under three conditions, with three different desiccant settings. The first condition involved using the desiccant filter 100 described in the previous embodiment, along with 4A molecular sieves with a size of 0.5mm-1mm as the desiccant. The second condition involved using the desiccant filter 100 described in the previous embodiment, along with other desiccants, such as 4A molecular sieves with a size of 1-2mm. The third condition involved not using a desiccant, i.e., the desiccant filter 100 running idle or not connected to the cryoablation system. The number of ablation procedures required for one surgical procedure was ablated daily, and the number of days with ice blockage was recorded and statistically compared. Figure 15It can be seen that after using the dryer filter 100 and adding desiccant, there is a significant improvement in the dissolution and clogging phenomenon within three months. The dryer filter 100 with 4A molecular sieve desiccant with a size of 0.5mm-1mm performed the best among all types, and no clogging occurred within three months.

[0094] The cryoablation system of the above embodiment has at least the following technical effects:

[0095] (1) The drying filter effectively reduces the moisture in the gas source medium, further improving the stability of the balloon temperature and inlet pressure curve, which is beneficial for the surgeon to make judgments and improves the success rate of the operation.

[0096] (2) The dryer filter effectively improves the stability of the cryoablation equipment and reduces the risk of pipeline blockage. At the same time, the self-designed desiccant is more in line with the actual situation of the cryoablation system, making it easier to repair, maintain and replace, while reducing costs.

[0097] (3) By optimizing the pipeline flow channel design and desiccant selection, the desiccant can fully filter the gas source medium passing through, improve the utilization efficiency of the desiccant, and reduce the cost by independently designing the drying filter.

[0098] (4) Through reasonable structural design, the desiccant replacement method is perpendicular to the side plate of the equipment, and the previous cumbersome installation steps are optimized, which facilitates the maintenance of the equipment in the later stage.

[0099] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0100] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of this application. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the protection scope of this application.

Claims

1. A cryoablation system, comprising a gas source, a heat exchange capillary tube, and an evaporator, wherein, The gas source medium is nitrous oxide containing moisture, and the feature is that it also includes a drying filter; The drying filter has an air inlet and an air outlet. The air inlet is connected to the air source, and the air outlet is connected to the heat exchange capillary tube. The heat exchange capillary tube exchanges heat with the evaporator. The drying filter is filled with a drying material that can adsorb water molecules in the gas source medium and allows nitrous oxide molecules to pass freely, in order to remove moisture from the gas source medium passing through the drying filter.

2. The cryoablation system according to claim 1, characterized in that, The drying filter includes a cylindrical body, a first filter element, and a second filter element; The cylinder has openings at both ends; The first filter element is disposed at the first end opening of the cylinder; The second filter element is disposed at the second end opening of the cylinder; The cylinder, the first filter, and the second filter form a closed filtration cavity, which is filled with the drying material. The minimum particle size of the drying material is larger than the pore size of the first filter and the second filter. The air inlet and the air outlet are respectively connected to the filter chamber.

3. The cryoablation system according to claim 2, characterized in that, The first filter and the second filter are both sintered metal sheets, and the pore size of the first filter and the second filter is in the range of 30μm-100μm, which are used to allow the medium in the gas source to pass through and to intercept the drying material.

4. The cryoablation system according to claim 2, characterized in that, The drying filter also includes an end cap having a closed end and an open end; The open end of the end cap is sealed to the second end opening of the cylinder, and the second filter is fixedly disposed inside the open end of the end cap. The side wall of the end cap is provided with a radial outlet, which is connected to the air outlet.

5. The cryoablation system according to claim 4, characterized in that, The drying filter also includes a housing, which covers the cylinder and the end cap; A first flow channel is formed between the inner wall of the outer shell and the outer wall of the cylinder. The radial outlet connects the filter chamber and the first flow channel, and the first flow channel connects to the air outlet.

6. The cryoablation system according to claim 5, characterized in that, The dryer filter also includes a base, which is sealed to the housing, and the air inlet and air outlet are disposed on the base; The first end of the cylinder is sealed to the base, and the air inlet is connected to the outside of the first filter.

7. A cryoablation system according to claim 6, characterized in that, The base includes a base body and a mounting part, and the side wall of the base body is provided with the air inlet and the air outlet; The mounting part protrudes from the base body and has an assembly hole that communicates with the air inlet. The first end of the cylinder is inserted into the assembly hole, and a sealed connection is formed between the outer wall of the first end of the cylinder and the inner wall of the mounting part. An axial channel is provided on the mounting part outside the assembly hole, and the air outlet communicates with the first flow channel through the axial channel.

8. A cryoablation system according to claim 2, characterized in that, The drying filter further includes a first pressure ring, which is fixedly disposed at the first end opening of the cylinder and located on the side of the first filter sheet away from the filter chamber, for axially fixing the first filter sheet.

9. A cryoablation system according to claim 4, characterized in that, The drying filter further includes a second pressure ring, which is disposed at the open end of the end cap and located on the side of the second filter sheet near the cylinder, for axially fixing the second filter sheet.

10. A cryoablation system according to claim 1, characterized in that, The drying material is 4A molecular sieve, and the particle size range of the 4A molecular sieve is 0.5mm-1mm.

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