Ablation catheter and distal tip structure thereof

Abstract

The application discloses an ablation catheter and a distal round head structure thereof, the distal round head structure comprising a distal head, an extensible section and an expansion section, the expansion section being provided with at least two variable-diameter portions arranged at intervals in the axial direction, the variable-diameter portions being at least partially made of elastic material to shrink or expand in response to pressure changes in the air cavity, the extensible section being axially extensible to drive the variable-diameter portions to expand in sequence through the extension and contraction of the extensible section in the axial direction, so as to achieve the purpose of adaptively adjusting the distance between the treatment center and the distal head, and improve the safety and operation convenience of the operation.

Description

Technical Field

[0001] This invention belongs to the field of ablation therapy technology, specifically relating to a distal rounded head structure of a catheter with ranging and protection functions, and an ablation catheter having the distal rounded head structure. Background Technology

[0002] Peripheral lung lesions are generally located in the distal segmental bronchi of the lungs, surrounded by lung parenchyma and not visible under routine bronchoscopy. They are without intraluminal neoplasms, external pressure, mucosal lesions, stenosis, inflammation, hemorrhage, etc. A lesion with a long diameter >3cm is called a mass, and a lesion with a long diameter ≤3cm is called a nodule.

[0003] Local ablation therapy, as a minimally invasive treatment technique, has been applied in the treatment of early-stage lung cancer. It boasts advantages such as minimal trauma, definite efficacy, accurate localization, and good selectivity, and has been recommended by multiple guidelines as one of the radical or palliative treatment methods for both primary and metastatic lung cancer. Transbronchial treatment of peripheral lung tumors requires placing the ablation site of the treatment catheter through the bronchus to the center of the lesion. Because the lesion is located distal to the segmental bronchus, the treatment site cannot be exposed in the field of vision. Therefore, it is crucial to accurately and safely place the treatment site in the center of the lesion.

[0004] Current placement methods typically involve estimating the distance from the lesion using graduated markings on the catheter. The physician uses a preoperative CT scan to determine how far the lesion is from the bronchoscopic field of view. The distance the catheter is moved beyond the field of view is then used to determine the length of the treatment area beyond the lesion's visual field. After confirming the placement position, a second CT scan is performed to verify that the treatment area is centered on the lesion.

[0005] Because the placement location is outside the field of vision, it has the following drawbacks: First, the depth of the catheter is difficult to determine, and the accuracy of placement depends heavily on the doctor's experience; Second, during placement without a field of vision, the tip of the catheter at the treatment site is prone to puncture or scratch the tracheal wall, causing bleeding or even pneumothorax; Third, pushing without a field of vision can easily lead to the treatment site being too close to the chest wall, and if the treatment area and intensity are too large, it can easily damage the chest wall and cause problems such as pneumothorax. Summary of the Invention

[0006] In existing technologies, because the area to be treated is outside the field of vision, it is difficult to safely, accurately, and conveniently deliver the instruments used for treatment to the center of the lesion, resulting in insufficient convenience and safety of the surgery.

[0007] To achieve the above objectives, the solution adopted by the present invention is as follows:

[0008] The distal rounded head structure for an ablation catheter extends axially, with the ablation catheter positioned proximally at the distal rounded head structure. The distal rounded head structure comprises a distal tip, a telescopic section, and an expansion section from its distal to its proximal end. An air cavity is formed within at least a portion of the telescopic and expansion sections, allowing the telescopic section to deform and induce pressure changes within the air cavity, and the expansion section to deform in response to these pressure changes. The distal tip is connected to the outer end of the telescopic section. The expansion section has at least two axially spaced variable diameter sections, the inner cavities of which communicate with the air cavity. At least a portion of each variable diameter section is made of an elastic material to contract or expand in response to pressure changes within the air cavity. The telescopic section is axially extensible, allowing its axial expansion and contraction to act on the air cavity, thereby driving the variable diameter sections to expand sequentially from the distal to the proximal end.

[0009] The air cavity is formed within at least a portion of the telescopic and expansion sections, meaning it can be located either along the entire length of the telescopic or expansion section or within a small segment. The variable-diameter section is at least partially made of an elastic material, with an internal variable-diameter cavity connected to the air cavity, allowing pressure changes within the air cavity to cause deformation of the variable-diameter section. For example, as the air pressure within the air cavity increases, the outer diameter of the variable-diameter section increases linearly, or its outer diameter suddenly increases when the air pressure exceeds a preset value. The air pressure required for the linear increase to the preset value or the sudden increase is the expansion threshold of the variable-diameter section. When the air pressure is less than the expansion threshold of a certain variable-diameter section, the section does not deform significantly; conversely, when the air pressure is greater than or equal to the expansion threshold, the section expands, thereby adjusting the treatment area of ​​the device.

[0010] This technical solution allows for two main advantages. First, the distal end of the catheter can be compressed by the bronchial or chest wall, enabling the catheter to be adjusted to the desired treatment position. This ensures the ablation treatment area is located at the lesion while maintaining a sufficient safe distance from the chest wall, preventing chest wall damage due to excessive treatment area. Second, it allows for monitoring the expansion of each diameter-changing section through methods such as air pressure measurement, thus obtaining the distance between the ablation component and the distal end, achieving the purpose of distance measurement.

[0011] According to the aforementioned distal rounded head structure for the ablation catheter, the telescopic section is composed of an axial telescopic tube with several telescopic joints to achieve axial telescopic flexibility. With this design, the telescopic section has a variable diameter structure, meaning its diameter differs between the extended and compressed states. Compared to a cylindrical shape, it is easier to fold, and both the folding method and the folded structure are axial, making it less prone to bending.

[0012] According to the aforementioned distal rounded head structure for an ablation catheter, the telescopic section is composed of an elastic element and an elastic membrane. The elastic membrane is connected between the distal head and the expansion section to form an elastic cavity. The elastic element is sleeved on the inner or outer side of the elastic membrane outside the tubing to provide telescopic tension, so as to keep the distal head extended when there is no external force. In this case, the elastic element is preferably a helical spring, which is sleeved on the inner or outer wall of the tubing and acts between the two ends of the tubing to give the telescopic section axial telescopic characteristics. Alternatively, the helical spring can be integrated into the tubing wall, which can also achieve the purpose of providing axial telescopic characteristics to the telescopic section.

[0013] According to the above-mentioned distal round head structure for ablation catheter, the telescopic section is composed of two telescopic sub-tubes that are nested together and can move axially, including an inner telescopic sub-tube and an outer telescopic sub-tube. A lumen is formed inside the outer telescopic sub-tube, and an elastic element is provided inside the lumen. The elastic element abuts against the inner telescopic sub-tube and the outer telescopic sub-tube. An elastic element is provided between the two telescopic sub-tubes so that both remain in an extended state when there is no external force. This also achieves the purpose of the telescopic section having telescopic characteristics.

[0014] According to the above-described distal round head structure for the ablation catheter, the capacity of the air cavity within the telescopic section increases or decreases linearly as the telescopic section extends or retracts axially, thereby achieving linear control of the variable diameter section.

[0015] According to the above-mentioned distal round head structure of the ablation catheter, the capacity of the air cavity in the telescopic section increases or decreases nonlinearly with the axial expansion and contraction of the telescopic section. For example, the change in air cavity capacity changes with the axial expansion and contraction increment of the telescopic section in a relationship of first decreasing and then decreasing or first decreasing and then increasing. This nonlinear relationship is also feasible.

[0016] According to the aforementioned distal rounded head structure for an ablation catheter, the distal rounded head structure further includes a distal body, with both ends of the distal body connected to a telescopic section and an expansion section, respectively. An air cavity is internally connected to the telescopic section, the distal body, and the expansion section. The distal body and the telescopic section or expansion section can be fabricated separately and then sealed together, or they can be integrally formed simultaneously.

[0017] According to the above-mentioned distal round head structure for ablation catheter, the expansion section includes a variable diameter body and a variable diameter part disposed on the variable diameter body. Several variable diameter parts are spaced apart on the variable diameter body along the axial direction. As the expansion section is compressed, the air pressure in the air chamber increases accordingly, and each variable diameter part expands in sequence, thereby achieving the purpose of adjusting the treatment range of the distal round head structure.

[0018] According to the above-described distal round head structure for ablation catheter, a sealing ring end is formed at the connection between the distal body and the variable diameter body, so that the distal round head structure can be easily connected to and work together with the ablation catheter.

[0019] According to the above-mentioned distal round head structure for the ablation catheter, the outer wall of the distal head is curved to prevent scratching during the pushing process and when it comes into contact with the distal bronchus or chest wall.

[0020] According to the above-described distal round head structure for ablation catheter, both the variable diameter body and the distal body are tubular components, and the diameter of the variable diameter body is smaller than that of the distal body, so as to form the sealing ring end on the end face of the distal body, thereby facilitating the connection of the distal round head structure.

[0021] According to the aforementioned distal rounded head structure of the ablation catheter, the expansion threshold of each diameter-changing section increases sequentially from the distal end to the proximal end, so that each diameter-changing section can expand sequentially.

[0022] As a second aspect of the present invention, an ablation catheter is provided, comprising a medium tube and a plurality of medium nozzle groups spaced axially on the medium tube, each medium nozzle group comprising at least one nozzle; characterized in that the ablation catheter further comprises any of the above-mentioned distal rounded head structures, the variable diameter portion of the distal rounded head structure being disposed within the medium tube, the distal end of the distal rounded head structure being formed as the front end of the ablation catheter, so that the pressure change of the air cavity induced by the telescopic section of the distal rounded head structure under the action of the distal end causes the variable diameter portion to expand sequentially, thereby regulating the working state of the medium nozzle group.

[0023] Based on the aforementioned advantages of its distal rounded head structure, the resulting instrument, when mounted on an ablation catheter, possesses the necessary surgical functions and features of the distal rounded head structure, thereby enhancing the safety and convenience of the surgical procedure.

[0024] According to the above-mentioned ablation catheter, the ablation catheter includes at least a spray-type cryoablation catheter, a balloon-type cryoablation catheter, or a hot steam ablation catheter.

[0025] The ablation catheter and its distal rounded head structure of the present invention have at least the following advantages:

[0026] 1. It can be operated as needed to adjust the distance between the ablation treatment area and the bronchial wall or chest wall, and achieve the purpose of simple and quick positioning to the lesion location.

[0027] 2. Distance measurement can be achieved by monitoring air pressure.

[0028] 3. The distal end is preferably shaped with a round or blunt outer end, so that the distal end round head structure is less likely to cause scratches or damage during use.

[0029] 4. By measuring the air pressure, an alarm function can also be provided. That is, if the telescopic section is not compressed or is compressed but not to the expected extent, it indicates that the distal round head structure is still a certain distance from the end of the bronchus or the chest wall, and the surgical instrument has not been placed in the intended position. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of the distal round head structure of a certain embodiment of the present invention when its telescopic section is at its maximum length. It is a schematic diagram of the structure when its telescopic section is composed of an axial telescopic tube.

[0031] Figure 2 yes Figure 1 A schematic diagram of the cross-sectional structure;

[0032] Figure 3 yes Figure 1 A schematic diagram of the structure when the telescopic section is at its minimum length;

[0033] Figure 4 yes Figure 1 A schematic diagram of the structure of the distal rounded head structure of the embodiment when applied to a balloon-type cryoablation catheter;

[0034] Figure 5 This is a schematic diagram of the distal round head structure of another embodiment of the present invention when its telescopic section is at its maximum length. It is a schematic diagram of the structure when the telescopic section is composed of elastic elements and spring films.

[0035] Figure 6 yes Figure 5 A schematic diagram of the structure of the distal round head structure in the embodiment when it is partially compressed;

[0036] Figure 7 yes Figure 5 A schematic diagram of the structure of the embodiment when it is fully compressed;

[0037] Figure 8 This is a schematic diagram of the distal round head structure of another embodiment of the present invention when its telescopic section is at its maximum length. It is a schematic diagram of the structure when the telescopic section is composed of a telescopic sub-tube.

[0038] Figure 9 yes Figure 8 A schematic diagram of the structure under partial compression in the embodiment;

[0039] Figure 10 yes Figure 8 A schematic diagram of the structure when fully compressed in the embodiment.

[0040] The components include: telescopic section 11, expansion section 12, distal head 13, distal body 14, air chamber 110, telescopic section outer end 111, telescopic section inner end 112, telescopic joint 113, variable diameter body 121, variable diameter part 122, sealing ring end 141, elastic element 151, elastic membrane 152, elastic membrane cavity 153, inner telescopic sub-tube 161, outer telescopic sub-tube 162, lumen 163, air inlet pipe 21, air return pipe 22, balloon 23, air inlet pipeline 211, nozzle 212, air return pipeline 221, and balloon cavity 231. Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention and to more clearly define the scope of protection of the present invention, the present invention will be described in detail below with reference to certain specific embodiments. It should be noted that the following are only some specific embodiments of the present invention, and are merely a part of the embodiments of the present invention. The specific and direct descriptions of related structures are only for the convenience of understanding the present invention, and the specific features do not necessarily or directly limit the scope of the present invention. Conventional choices and substitutions made by those skilled in the art under the guidance of the present invention should be considered within the scope of protection of the present invention.

[0042] Example 1

[0043] The distal rounded head structure can be used in ablation catheters. It is used to assemble onto or integrally form with the ablation catheter to provide protection at the distal end of the ablation catheter, preventing scratches to the patient, and also to achieve distance measurement.

[0044] like Figure 1 As shown, the distal rounded head structure extends axially, with its proximal end connected to the ablation catheter and its distal end positioned away from the ablation catheter to protrude from its distal end. Figure 1 In the diagram, the left side is the distal end (or outer end / outer side), the right side is the proximal end (or inner end / inner side), and the left and right extension directions are the axial direction.

[0045] In this embodiment, the distal rounded head structure has a distal head 13, a telescopic section 11, and an expansion section 12 formed from its distal end to its proximal end. An air cavity 110 is formed inside the distal rounded head structure, located within the telescopic section 11 and the expansion section 12. This allows the telescopic section 11 to expand and deform, inducing a pressure change within the air cavity 110. The expansion section 12 can deform in response to the pressure change within the air cavity 110. Alternatively, in other embodiments, the air cavity 110 may be located only within a portion of the telescopic section 11 or the expansion section 12, i.e., a portion of the telescopic section 11 or the expansion section 12 may be a solid structure without the air cavity 110.

[0046] The telescopic section 11 is axially expandable to change the distance between its two ends (i.e., the outer end 111 and the inner end 112) and the capacity of its internal air chamber 110. When the telescopic section 11 is in such a state... Figure 1 and Figure 2 In the telescopic state shown, the axial distance between the two ends of the telescopic section 11 is the greatest, and the internal air chamber volume is also at its maximum. When the telescopic section 11 is compressed to contract substantially axially (as shown in the diagram), Figure 3 As shown), the axial distance between its two ends decreases, and at the same time, the volume of its internal air chamber is at its minimum. In actual use, the telescopic section 11 can vary between these two values.

[0047] In this embodiment, the capacity of the air cavity 110 inside the telescopic section 11 decreases as the telescopic section 11 is compressed axially. The reduction can be linear or non-linear, depending on the specific construction of the telescopic section 11. For example, when the telescopic section 11 is as follows... Figure 1-3 When the expansion joints are uniformly arranged along the axial direction, the internal air chamber capacity decreases linearly when compressed. When the expansion joints are non-uniformly arranged with smaller ends and a larger middle section along the axial direction, the decrease in air chamber capacity when the expansion joints are compressed along the axial direction first increases and then decreases.

[0048] In this embodiment, the distal end 13 is disposed at the outer end 111 of the telescopic section, and the two are fixedly connected or integrally formed. The distal end 13 has a blunt structure to avoid scratches that may be caused by sharp parts. For example, the outer surface of the distal end 13 is a smooth curved surface, such as a hemisphere.

[0049] The inner end 112 of the telescopic section and the outer end of the expansion section 12 can be directly or indirectly connected. Direct connection means that the two are directly connected or integrally formed, while indirect connection means that the two are connected via a third component or integrally formed. The connection between the two should be airtight to avoid air leakage.

[0050] The expansion section 12 includes at least two variable diameter sections 122 arranged along the axial direction. Each variable diameter section 122 is made wholly or partially of an elastic material. It is in a constricted state when the internal air pressure is below a preset value and in an expanded state when the internal air pressure is greater than or equal to the preset value. Furthermore, the preset air pressure required for the expansion of each variable diameter section 122 along the axial direction from the distal end to the proximal end increases sequentially, thereby allowing them to expand one by one as the internal pressure of the air chamber 110 increases.

[0051] In this embodiment, since the internal air chamber of the telescopic section 11 and the internal air chamber of the expansion section 12 are interconnected, the air pressure in all parts of the overall air chamber 110 is equal. When the telescopic section 11 is subjected to force and is compressed and deformed to shrink generally along the axial direction, the air pressure in the air chamber 110 increases, thereby expanding each variable diameter part 122 of the expansion section 12 from far to near in sequence.

[0052] Therefore, when the telescopic section 11 is at its maximum length, only the variable diameter section 122 at the farthest end is in an expanded state while the other variable diameter sections 122 are in a non-expanded state or all variable diameter sections 122 are in a non-expanded state. As the telescopic section 11 is compressed and deformed, the internal air pressure of the air chamber 110 increases, and each variable diameter section 122 from far to near sequentially turns into an expanded state.

[0053] In this embodiment, the axial distance between the catheter ablation component and the lesion can be adjusted by the retraction distance of the telescopic section 11, thereby changing the range of ablation.

[0054] In this embodiment, by adjusting the number of variable diameter sections 122 in the expansion section 12 that are in the expansion state, the flow rate of the medium entering the ablation component can be changed, thereby changing the intensity of the ablation effect.

[0055] In this embodiment, the ablation range and intensity can be changed by altering the retraction distance of the telescopic section 11 and the number of variable diameter sections 122 in the expanded state.

[0056] In this embodiment, by adjusting the material or structural characteristics of the telescopic section 11 and the variable diameter section 122, their respective elastic properties can be changed. For example, the change of a single telescopic section 11 from an expanded state to a compressed state can correspond to the change of two variable diameter sections 122 from a reduced state to an expanded state, thereby achieving the adjustment of the axial distance between the distal end 13 and the innermost variable diameter section 122 in the expanded state, and achieving the purpose of controlling the ablation range and ablation intensity.

[0057] In this embodiment, the air chamber 110 is connected to the outside through an air chamber tube (not shown in the figure), and the pressure inside the air chamber 110 is detected in real time by an air pressure measuring mechanism to ensure that the air pressure meets the preset during operation, and can also be used to trigger an alarm based on the air pressure.

[0058] In this embodiment, the distal rounded head structure further includes a distal body 14, which is generally a hollow columnar structure. Its two ends are connected to the telescopic section 11 and the expansion section 12, respectively. An air cavity 110 is disposed internally within the telescopic section 11, the distal body 14, and the expansion section 12. Furthermore, the diameter of the distal body 14 is larger than that of the expansion section 12 to facilitate the installation of the distal rounded head structure at the distal end of the ablation catheter.

[0059] The expansion section 12 includes a variable-diameter body 121 and variable-diameter portions 122 disposed on the variable-diameter body 121. The variable-diameter body 121 is a tubular component with a diameter smaller than that of the distal body 14, so that a sealing ring end 141 is formed at the connection between the distal body 14 and the variable-diameter body 121 for installation and engagement with the ablation catheter. In this embodiment, four variable-diameter portions 122 are evenly spaced along the axial direction on the variable-diameter body 122. When the expansion section 11 is compressed, the air pressure in the air chamber 110 increases accordingly, and each variable-diameter portion 122 expands sequentially, thereby achieving the purpose of adjusting the treatment range and / or intensity.

[0060] like Figure 1-4 As shown, in some embodiments, the telescopic section 11 is composed of an axial telescopic tube having a plurality of telescopic joints 113, each of which can extend and retract axially to change its axial length.

[0061] like Figure 5-7 As shown, in some embodiments, the telescopic section 11 is composed of an elastic element 151 and an elastic membrane 152. The elastic element 151 (e.g., a spring) is disposed inside the elastic membrane 152. The two ends of the elastic element are respectively connected to the distal end 13 and the distal end of the expansion section 12. The elastic membrane 152 is sealed between the distal end 13 and the expansion section 12 to form an axially expandable elastic cavity 153, which constitutes part of the air cavity 110. Therefore, in this embodiment, when pressure is applied to the distal end 13, the elastic element 151 is driven to deform axially, causing the elastic cavity 153 to be compressed and the elastic membrane 152 to contract accordingly. The internal pressure of the air cavity 110 increases, allowing each variable diameter section 122 from the distal end to the proximal end to sequentially expand. The specific number of variable diameter sections 122 that expand depends on the axial compression of the telescopic section 11. Of course, in other embodiments, the elastic element 151 can also be sleeved on the outside of the elastic film 152, which can also achieve the purpose of inducing air pressure changes and driving the variable diameter part 122 to expand sequentially.

[0062] like Figure 8-10As shown, in some other embodiments, the telescopic section 11 is composed of two telescopic sub-tubes that are nested together and movable axially, including an inner telescopic sub-tube 161 and an outer telescopic sub-tube 162, which are nested together. The outer telescopic sub-tube 162 has a cavity 163 formed within it, which forms part of the air chamber 110. An elastic element 151 is provided within the cavity 163, with both ends of the elastic element 151 abutting between the inner telescopic sub-tube 161 and the outer telescopic sub-tube 162, for example, abutting the outer end face of the inner telescopic sub-tube 161 and the end face of the cavity 163 of the outer telescopic sub-tube 162, thereby keeping the inner telescopic sub-tube 161 extended when no external force is applied. The distal end 13 is formed at the distal end of the inner telescopic sub-tube 161, and a piston is formed at the proximal end of the inner telescopic sub-tube 161 for sliding movement within the cavity 163, thereby ensuring that the maximum extension stroke of the inner telescopic sub-tube 161 is limited and the cavity 163 is well sealed.

[0063] As an application, the aforementioned distal rounded head structure is installed into a balloon-type cryoablation catheter, thereby forming an ablation catheter with measurement and protection functions.

[0064] like Figure 4 As shown, in this specific embodiment, the balloon-type cryoablation catheter has a conventional structure based on existing technology. It includes an inlet tube 21, a return tube 22, and a balloon 23 located at its distal end. The inlet tube 21 is fitted inside the return tube 22. An inlet channel 211 is formed inside the inlet tube 21, and a return channel 221 is formed in the gap between the return tube 22 and the inlet tube 21. The balloon 23 is located at the distal end of the inlet tube 21 and connected to the distal end of the return tube 22. A balloon cavity 231 is formed within the balloon 23, allowing the medium to flow sequentially through the inlet channel 211, the nozzle 212, the balloon cavity 231, and the return channel 221. The inlet tube 21 can be an integral component or a separate component. For an inlet tube with a separate component, the portion at its distal end where the nozzle 212 is located can be a separate component.

[0065] In this specific embodiment, the distal body 14 and the expansion section 12 of the distal round head structure are connected to the air intake pipe 21. The distal end of the balloon 23 is sealed to the distal body 14. Each variable diameter section 122 of the expansion section 12 corresponds to the nozzle 212 of the air intake pipe 21. When the corresponding variable diameter section 122 expands, it blocks each nozzle 212 to prevent the medium from flowing out of the nozzle 212.

[0066] Therefore, with all the variable diameter sections 122 in a non-expanded state, the medium flows through all the nozzles 212 for ablation treatment. At this time, the ablation treatment site is furthest away. As each variable diameter section 122 is sequentially expanded and blocks its corresponding nozzle 212, the nozzles 212 through which the medium flows are sequentially blocked from distal to proximal, causing the ablation treatment site to shift inward, thereby achieving the purpose of controlling the treatment area and / or the intensity of the effect. When the telescopic section 11 is in an extended state, the ablation treatment area is closer to the distal end; when the telescopic section 11 is partially or completely compressed, the ablation treatment area also moves proximally accordingly. Furthermore, this process is based on the pushing stroke control of the ablation catheter at the surgical site. When the distal tip 13 contacts the human organ, a larger pushing amount will result in more compression of the telescopic section 11.

[0067] In a further embodiment, the expansion state of each variable diameter section 122 can be determined by measuring the absolute or relative value of the pressure within the return air line 221, thereby reflecting the distance and intensity of its actual treatment area. This is because, when the pressure in the inlet air line 211 is stable, the pressure in the return air line 221 depends on the number of nozzles 212 that are open. The pressure in the return air line 221 is at its maximum when all variable diameter sections 122 are not blocking the nozzles 212. As each variable diameter section 122 expands sequentially from the distal end to the proximal end, blocking its corresponding nozzle 212, the pressure in the return air line 221 decreases accordingly. Of course, in other embodiments, the expansion state of each variable diameter section 122 can also be measured by measuring the pressure change in the air cavity 110 within the distal rounded head structure, but this is less convenient than the former and the overall stability of the equipment may decrease as a result.

[0068] In this embodiment, in order to seal the corresponding nozzle 212, the variable diameter part 122 of the distal round head structure expands and can abut against the inner wall of the medium tube or the nozzle, thereby achieving the effect of sealing each nozzle of the medium tube from the outside to the inside. This allows for adjustment of the axial distance between the cryoablation treatment area and the distal head, preventing the treatment area from being too close to the chest wall.

[0069] Of course, in other embodiments, the aforementioned distal round head structure can also be applied to spray-type cryoablation devices or hot steam ablation catheters.

Claims

1. A distal rounded head structure for an ablation catheter, characterized in that: The distal round head structure extends along its axial direction, and the ablation catheter is disposed at the proximal end of the distal round head structure. The distal round head structure is provided with a distal head (13), a telescopic section (11), and an expansion section (12) from its distal end to its proximal end. An air cavity (110) is formed in at least a portion of the telescopic section (11) and the expansion section (12) so that the telescopic section (11) and the expansion section (12) induce or respond to pressure changes in the air cavity (110). The distal head (13) is connected to the distal end of the telescopic section (11). The expansion section (12) is provided with at least two variable diameter sections (122) spaced apart along the axial direction. The inner cavity of the variable diameter section (122) is connected to the air cavity (110). At least a portion of the variable diameter section (122) is made of elastic material to contract or expand in response to pressure changes in the air cavity (110). The telescopic section (11) is axially extensible so that the telescopic section (11) acts on the air cavity (110) through its telescopic movement in the axial direction, thereby driving each variable diameter section (122) to expand sequentially from the distal end to the proximal end.

2. The distal rounded head structure for the ablation catheter according to claim 1, characterized in that: The telescopic section (11) is composed of an axial telescopic tube, which has several telescopic joints (113); or, The telescopic section (11) is composed of an elastic element (151) and an elastic film (152). The elastic film (152) is connected between the distal end (13) and the expansion section (12) to form an elastic cavity (153). The elastic element (151) is sleeved on the inner or outer side of the elastic film (152); or, The telescopic section (11) is composed of two telescopic sub-tubes that are nested together and move along the axial direction, including an inner telescopic sub-tube (161) and an outer telescopic sub-tube (162). A cavity (163) is formed inside the outer telescopic sub-tube (162), and an elastic element (151) is provided inside the cavity (163). The elastic element (151) abuts against the inner telescopic sub-tube (161) and the outer telescopic sub-tube (162).

3. The distal rounded head structure for an ablation catheter according to claim 1 or 2, characterized in that: The capacity of the air cavity (110) within the telescopic section (11) increases or decreases linearly as the telescopic section (11) expands or contracts axially; or, The capacity of the air chamber (110) in the telescopic section (11) increases or decreases nonlinearly as the telescopic section (11) expands or contracts along the axial direction.

4. The distal rounded head structure for the ablation catheter according to claim 3, characterized in that: The distal round head structure also includes a distal body (14), whose two ends are respectively connected to the telescopic section (11) and the expansion section (12), and the air cavity (110) is connected inside the telescopic section (11), the distal body (14) and the expansion section (12).

5. The distal rounded head structure for the ablation catheter according to claim 3, characterized in that: The air chamber (110) is connected to the outside through the air chamber tube, and the air pressure measuring mechanism detects the pressure inside the air chamber (110).

6. The distal rounded head structure for an ablation catheter according to claim 4, characterized in that: The expansion section (12) includes a variable diameter body (121) and a variable diameter part (122) disposed on the variable diameter body (121), and a sealing ring end (141) is formed at the connection between the distal body (14) and the variable diameter body (121).

7. The distal rounded head structure for an ablation catheter according to claim 6, characterized in that: The outer wall of the distal end (13) has a curved structure. Both the variable diameter body (121) and the distal body (14) are tubular components, and the diameter of the variable diameter body (121) is smaller than that of the distal body (14) so ​​that the sealing ring end (141) is formed on the end face of the distal body (14).

8. The distal rounded head structure for an ablation catheter according to claim 1, characterized in that: The expansion threshold of each variable diameter section (122) increases sequentially from the distal end to the proximal end.

9. An ablation catheter, comprising a medium tube and a plurality of medium nozzle groups spaced axially on the medium tube, each medium nozzle group comprising at least one nozzle; characterized in that, The ablation catheter further includes a distal round head structure as described in any one of claims 1-8, wherein the variable diameter section (122) of the distal round head structure is disposed inside the medium tube, and the distal head (13) of the distal round head structure is formed as the front end of the ablation catheter, so that the pressure change of the air chamber (110) is induced by the telescopic section (11) of the distal round head structure under the action of the distal head (13), thereby driving the variable diameter section (122) to expand sequentially and regulating the working state of the medium nozzle group.

10. The ablation catheter according to claim 9, characterized in that, The ablation catheter is a spray-type cryoablation catheter, a balloon-type cryoablation catheter, or a hot steam ablation catheter.

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