Radio frequency ablation catheter and flexible electrode thereof, and radio frequency ablation system

Abstract

Provided are a flexible electrode (22) for a radio frequency ablation catheter (100), the radio frequency ablation catheter (100), and a radio frequency ablation system. The flexible electrode (22) comprises: a flexible metal electrode layer (223), a liner layer (224), a first flexible conductor layer (226), a substrate layer (227), and a second flexible conductor layer (229) that are sequentially stacked. The liner layer (224) and the substrate layer (227) are made of a flexible insulating material. A power connection region of the flexible metal electrode layer (223) is configured to be connected to the distal end of a radio frequency cable of the radio frequency ablation catheter (100), and a radio frequency conduction region at the distal end of the flexible metal electrode layer (223) is configured to conduct radio frequency energy to a target tissue. The distal end of the substrate layer (227) is provided with an electrical connection part (2271). The distal end of the second flexible conductor layer (229) is electrically connected to the distal end of the first flexible conductor layer (226) by means of the electrical connection part (2271). In addition, the orthographic projections of junctions between the distal ends of both the first flexible conductor layer (226) and the second flexible conductor layer (229) and the electrical connection part (2271) on a first surface fall within the radio frequency conduction region, and the proximal ends of both the second flexible conductor layer (229) and the first flexible conductor layer (226) are configured to be respectively connected to the distal ends of two wires (40a, 40b) of the radio frequency ablation catheter to form a thermocouple circuit.

Description

Radiofrequency ablation catheters and their flexible electrodes, radiofrequency ablation systems Cross-references

[0001] This disclosure incorporates, in its entirety, Chinese Patent Application No. 202411946821.4, filed on December 26, 2024, entitled “Radiofrequency Ablation Catheter and Flexible Electrode Thereof, Radiofrequency Ablation System”, which is incorporated herein by reference. Technical Field

[0002] This disclosure relates to the field of medical device technology, and in particular to a radiofrequency ablation catheter and its flexible electrode, and a radiofrequency ablation system. Background Technology

[0003] Currently, radiofrequency ablation (RFA) is widely used in the medical field to treat diseases such as arrhythmia and tumors. Its working principle involves applying radiofrequency current through electrodes to the target tissue (such as tumors or heart lesions). As the radiofrequency current flows through the target tissue, it is converted into heat energy, causing the temperature of the target tissue to rise rapidly. This leads to the evaporation of intracellular water and protein denaturation, thereby inducing necrosis of the target tissue. Therefore, the key to radiofrequency ablation technology lies in precise temperature control.

[0004] Radiofrequency ablation catheters, commonly used medical devices employing radiofrequency ablation technology, are equipped with temperature sensing elements located near the electrodes to monitor the temperature of the target tissue for precise temperature control. During treatment, the radiofrequency ablation catheter is typically inserted into the patient's body through a natural cavity (such as a blood vessel). Electrodes made of metallic materials are placed against the target tissue to discharge radiofrequency current, which is then conducted along the electrodes to the target tissue.

[0005] However, in actual use, this radiofrequency ablation catheter encounters significant resistance during its insertion into the patient's body. Summary of the Invention

[0006] This disclosure provides a radiofrequency ablation catheter and its flexible electrode, as well as a radiofrequency ablation system, which can reduce the resistance encountered by the radiofrequency ablation catheter with the flexible electrode during intervention in the patient's body.

[0007] According to a first aspect of this disclosure, a flexible electrode for a radiofrequency ablation catheter is provided, comprising: a flexible metal electrode layer, a liner layer, a first flexible conductor layer, a substrate layer, and a second flexible conductor layer;

[0008] The flexible metal electrode layer has a first surface and a second surface opposite to the first surface along its own thickness direction. The power receiving area of ​​the flexible metal electrode layer is used to connect to the distal end of the radio frequency cable of the radio frequency ablation catheter. The distal end of the flexible metal electrode layer has a radio frequency conducting area, which is configured to conduct radio frequency energy to the target tissue.

[0009] A liner layer is disposed on the second surface, and the liner layer is made of a flexible insulating material;

[0010] The first flexible conductor layer is stacked on the side of the liner layer facing away from the flexible metal electrode layer, and the first flexible conductor layer and the flexible metal electrode layer are insulated and isolated by the liner layer.

[0011] The substrate layer is disposed on the side of the first flexible conductor layer that faces away from the flexible metal electrode layer, and an electrical connection portion is provided at the far end of the substrate layer. The substrate layer is made of a flexible insulating material.

[0012] The second flexible conductor layer is stacked on the side of the substrate layer facing away from the flexible metal electrode layer. The second flexible conductor layer and the first flexible conductor layer are insulated and isolated by the substrate layer. The distal end of the second flexible conductor layer is electrically connected to the distal end of the first flexible conductor layer through an electrical connection portion. The orthographic projection of the connection points between the distal ends of the first flexible conductor layer and the distal ends of the second flexible conductor layer and the electrical connection portion falls within the radio frequency conduction area on the first surface. The proximal ends of the second flexible conductor layer and the proximal ends of the first flexible conductor layer are used to connect with the distal ends of the two wires of the radio frequency ablation catheter to form a thermocouple circuit.

[0013] The flexible electrode of this disclosure can perform radiofrequency ablation and monitor the temperature of the radiofrequency ablation area. Furthermore, by designing each layer of the flexible electrode to be flexible, the flexible electrode as a whole possesses excellent flexibility. Additionally, the flexible metal electrode layer, the first flexible conductor layer, and the second flexible conductor layer are stacked along their respective thickness directions, thereby reducing the resistance encountered by the radiofrequency ablation catheter during intervention in the patient's body when using the flexible electrode of this disclosure.

[0014] In some embodiments, the proximal end of the first flexible conductor layer has a first connection region, which is connected to one of the two wires; the proximal end of the second flexible conductor layer has a second connection region, which is used to connect to the other of the two wires; the orthographic projections of the first connection region and the second connection region on the first surface are offset, and the orthographic projection of the first connection region on the first surface does not fall into the orthographic projection region of the second flexible conductor layer on the first surface.

[0015] In some embodiments, the orthographic projection of the first flexible conductor layer on the first surface falls within the boundary of the orthographic projection area of ​​the substrate layer on the first surface, and the proximal end of the substrate layer extends beyond the proximal end of the second flexible conductor layer in its own extension direction; a first conductive via is formed at the proximal end of the substrate layer, and the first conductive via is formed in the portion of the substrate layer that extends beyond the proximal end of the second flexible conductor layer, and the first connection region is connected to one of the two wires through the first conductive via.

[0016] In some embodiments, the flexible electrode further includes a back film layer stacked on the side of the second flexible conductor layer facing away from the flexible metal electrode layer. The side of the back film layer facing away from the flexible metal electrode layer is used to connect with the support carrier of the radiofrequency ablation catheter. The back film layer is made of a flexible insulating material. The proximal end of the back film layer is provided with a first through hole and a second through hole spaced apart from each other. The first through hole is used to expose the connection point between the first conductive through hole and one of the two wires, and the second through hole is used to expose the connection point between the second connection area and the other of the two wires.

[0017] In some embodiments, the flexible electrode further includes a conductive layer, which is disposed in the same layer as the second flexible conductor layer. The proximal ends of the conductive layer and the second flexible conductor layer are adjacent to each other and spaced apart. A first conductive via is connected to one of the two wires through the conductive layer. And / or, the proximal end of the backing layer is rectangular, and a first through hole and a second through hole are disposed at both ends of the diagonal of the rectangle along its own extension direction.

[0018] In some embodiments, the flexible electrode further includes a coating layer disposed on the side of the flexible metal electrode layer opposite to the substrate layer. The coating layer has a first window and a second window, the first window exposing a contact area and the second window exposing a radio frequency conduction area. The coating layer is made of a flexible insulating material.

[0019] In some embodiments, the electrical connection portion is a second conductive via, which penetrates the thickness of the far end of the substrate layer.

[0020] In some embodiments, the total thickness of the flexible electrode is less than or equal to 0.2 mm.

[0021] According to a second aspect of this disclosure, a radiofrequency ablation catheter is provided, comprising: an expandable support carrier and a flexible electrode assembly, the flexible electrode assembly including one or more flexible electrodes provided in the first aspect of this disclosure, the flexible electrodes being attached to the support carrier.

[0022] In some embodiments, the radiofrequency ablation catheter further includes a tube body, with a balloon as the support carrier, and the proximal end of the balloon disposed on the tube body; the flexible electrode assembly includes a fixing ring and a plurality of flexible electrodes, the fixing ring being sleeved on the outer periphery of the proximal axial segment of the balloon; the plurality of flexible electrodes are all connected to the fixing ring, and the distal and proximal ends of any flexible electrode are respectively located on both sides of the fixing ring along its axial direction, the portions of each flexible electrode located distal to the fixing ring are independent of each other and attached to the balloon, and the portions of each flexible electrode located proximal to the fixing ring have at least two common liner layers and substrate layers and extend into the lumen of the tube body.

[0023] In some embodiments, the support carrier is a balloon, and the flexible electrode assembly includes a plurality of flexible electrodes, the distal ends of which are uniformly and spaced apart around the longitudinal axis of the balloon, and the distal ends of which are distributed sequentially from the proximal end to the distal end of the balloon along the longitudinal axis of the balloon.

[0024] According to a third aspect of this disclosure, a radiofrequency ablation system is provided, comprising: a radiofrequency device and any of the radiofrequency ablation catheters provided in the second aspect of this disclosure, wherein the proximal end of a radiofrequency cable of the radiofrequency ablation catheter is connected to the radiofrequency device.

[0025] These and other aspects of this disclosure will be apparent from the embodiments described below, and will be elucidated with reference to the embodiments described below. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort. In the following description of exemplary embodiments in conjunction with the accompanying drawings, more details, features, and advantages of this disclosure are disclosed, in which:

[0027] Figure 1 is a partial structural schematic diagram of a radiofrequency ablation catheter according to some embodiments of this disclosure;

[0028] Figure 2 is a partial structural schematic diagram of a radiofrequency ablation catheter according to some other embodiments of this disclosure;

[0029] Figure 3 is a schematic diagram of the structure of a flexible electrode according to some embodiments of this disclosure;

[0030] Figure 4 shows enlarged partial schematic diagrams of points A, B, and C in Figure 3, respectively;

[0031] Figure 5 is a simplified schematic diagram of the connection between a flexible electrode and a wire in some embodiments of this disclosure;

[0032] Figure 6 is a simplified schematic diagram of the connection between the flexible electrode and the wire in some other embodiments of this disclosure;

[0033] Figure 7 is a schematic diagram of the back side of a flexible electrode according to some embodiments of this disclosure;

[0034] Figure 8 is a front view of a flexible electrode according to some embodiments of this disclosure;

[0035] Figure 9 is a structural schematic diagram of the flexible electrode assembly in the unfolded state according to some embodiments of this disclosure.

[0036] Explanation of reference numerals in the attached drawings: 100-Radiofrequency ablation catheter; 10-Support carrier; 11-Balloon; 20-Flexible electrode assembly; 21-Fixing ring; 22-Flexible electrode; 221-Coating layer; 2211-First window; 2212-Second window; 222-Fourth adhesive layer; 2221-Fifth opening; 2222-Sixth opening; 223-Flexible metal electrode layer; 224-Backing layer; 225-First adhesive layer; 226-First flexible conductor layer; 227-Substrate layer; 2271-Electrical connection; 2272-Second conductive via. 2273 - First conductive through-hole; 228 - Second adhesive layer; 2281 - First opening; 2282 - Second opening; 229 - Second flexible conductor layer; 2291 - Insulating hole; 230 - Third adhesive layer; 2301 - Third opening; 2302 - Fourth opening; 231 - Back film layer; 2311 - First through-hole; 2312 - Second through-hole; 232 - Conductive layer; 233a, 233b, 233c, 233d - Gold plating layer; 30 - Tube body; 40a, 40b - Conductors. Detailed Implementation

[0037] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure. Therefore, the drawings and description are to be considered exemplary in nature and not restrictive.

[0038] As used herein, the terms “patient,” “host,” and “user” refer to any human or animal subject and are not intended to limit the system or method or use to human use, but for the sake of brevity, human patients will be used as an example below.

[0039] To minimize resistance during the insertion of the radiofrequency ablation catheter into the patient's body, the distal end of the catheter should be as small as possible. Conversely, to ensure good electrode adhesion to the target tissue during treatment, the distal end of the catheter should be larger. Thus, the volume requirements for the radiofrequency ablation catheter are opposite at different stages. To address this, the electrodes are typically mounted on shape-memory metal components. These components can be constricted into a narrow shape to pass through natural cavities, and upon reaching the target tissue, they deform back to their original shape, increasing in volume.

[0040] However, due to the high hardness of the metal electrode itself, and the fact that the electrode and the temperature sensing element located near the electrode are laid flat on the shape memory metal component, the shape memory metal component carrying the electrode and temperature sensing element is difficult to shrink into a small volume even if it is bound and shaped, and the resistance encountered during the intervention in the patient's body is still relatively large.

[0041] Figure 1 is a partial structural schematic diagram of a radiofrequency ablation catheter according to some embodiments of the present disclosure, and Figure 2 is a partial structural schematic diagram of a radiofrequency ablation catheter according to other embodiments of the present disclosure. As shown in Figures 1 and 2, embodiments of the present disclosure provide a flexible electrode applied to a radiofrequency ablation catheter 100, specifically disposed on an expandable support carrier 10 (e.g., a shape memory metal component, a balloon 11, etc.) of the radiofrequency ablation catheter 100. For clarity, a balloon 11 will be used as an example in the following description.

[0042] Figure 3 is a schematic diagram of the structure of the flexible electrode 22 according to some embodiments of the present disclosure. As shown in Figure 3, the flexible electrode 22 includes: a flexible metal electrode layer 223, a liner layer 224, a first flexible conductor layer 226, a substrate layer 227, and a second flexible conductor layer 229. The flexible metal electrode layer 223 has a first surface and a second surface opposite to the first surface along its thickness direction. The liner layer 224 is disposed on the second surface. The first flexible conductor layer 226 is stacked on the side of the liner layer 224 opposite to the flexible metal electrode layer 223. The substrate layer 227 is disposed on the side of the first flexible conductor layer 226 opposite to the flexible metal electrode layer 223. The second flexible conductor layer 229 is stacked on the side of the substrate layer 227 opposite to the flexible metal electrode layer 223. Along the radial direction of the balloon 11, from the outer surface of the balloon 11 to the inner surface of the balloon 11, the flexible metal electrode layer 223, the liner layer 224, the first flexible conductor layer 226, the substrate layer 227, and the second flexible conductor layer 229 are sequentially stacked. That is, the first surface faces away from the outer surface of the balloon 11, the second surface faces the outer surface of the balloon 11, and the second flexible conductor layer 229 is closer to the outer surface of the balloon 11 than the flexible metal electrode layer 223.

[0043] The flexible metal electrode layer 223 can be made of any of the flexible conductors such as copper, gold, silver, and aluminum, giving it high conductivity and a certain degree of bending deformation capability. The distal end of the flexible metal electrode layer 223 is entirely or partially a radiofrequency conduction region. When the radiofrequency ablation catheter 100 is inserted into the patient's body, the distal end of the flexible metal electrode layer 223 is close to the target tissue, and the radiofrequency conduction region is configured to conduct radiofrequency energy to the target tissue. The configuration of the radiofrequency conduction region can be any of the following shapes: circular, rectangular, elliptical, etc.

[0044] In this embodiment of the disclosure, taking the flexible metal electrode layer 223 as an example, the end of the flexible metal electrode layer 223 or its components closer to the operator in the extension direction is defined as the "proximal end," and similarly, the end of the flexible metal electrode layer 223 or its components further away from the operator in the extension direction is defined as the "distal end." The definitions of "proximal end" and "distal end" for other layers or components on the flexible electrode 22 besides the flexible metal electrode layer 223, as well as the definitions of "proximal end" and "distal end" for the balloon 11 or its components, can be referenced to the flexible metal electrode layer 223 and will not be repeated here. As discussed herein, "operator" may include a physician, surgeon, or any other individual or delivery device associated with delivering the radiofrequency ablation catheter 100 to the patient.

[0045] The liner layer 224 is made of a flexible insulating material, giving it the ability to deform flexibly. Exemplarily, the flexible insulating material can be polyimide (PI), polyethylene terephthalate (PET), polyurethane (PU), or a combination thereof. The liner layer 224 can also be used to insulate the flexible metal electrode layer 223 and the first flexible conductor layer 226, thereby preventing a short circuit caused by the connection between the flexible metal electrode layer 223 and the first flexible conductor layer 226.

[0046] Similar to the liner layer 224, the substrate layer 227 is also made of a flexible insulating material, giving it flexible deformation capability and insulating isolation capability for insulating the first flexible conductor layer 226 and the second flexible conductor layer 229. Figure 4 shows a partial enlarged schematic diagram at points A, B, and C in Figure 3. As shown in Figures 3 and 4(A), the far end of the substrate layer 227 is also provided with an electrical connection portion 2271.

[0047] The distal end of the first flexible conductor layer 226 is electrically connected to the distal end of the second flexible conductor layer 229 via an electrical connection portion 2271. One of the first flexible conductor layer 226 and the second flexible conductor layer 229 is made of thermocouple positive conductor material, and the other is made of thermocouple negative conductor material. The proximal ends of the first flexible conductor layer 226 and the proximal ends of the second flexible conductor layer 229 are respectively connected to the distal ends of the two wires 40a and 40b of the radiofrequency ablation catheter 100 to form thermocouple circuits. The orthographic projection of the connection points between the distal ends of the first flexible conductor layer 226 and the distal ends of the second flexible conductor layer 229 and the electrical connection portion 2271 on the first surface falls within the radiofrequency conduction area; that is, the connection points of the distal ends of the first flexible conductor layer 226 and the distal ends of the second flexible conductor layer 229 correspond to the radiofrequency conduction area. In this way, the temperature of the target tissue can be transmitted through the radio frequency conduction region to the connection point at the distal end of the first flexible conductor layer 226 and the distal end of the second flexible conductor layer 229. Therefore, the connection point at the distal end of the first flexible conductor layer 226 and the distal end of the second flexible conductor layer 229 can be affected by the temperature change of the target tissue. Utilizing the thermocouple effect, the temperature of the connection point at the distal ends of the first flexible conductor layer 226 and the second flexible conductor layer 229, i.e., the temperature of the radio frequency conduction region and the target tissue, can be detected. To form a closed loop in the thermocouple circuit, the proximal ends of the two wires 40a and 40b can be connected to a voltage measuring instrument (e.g., a voltmeter). In other words, one of the first flexible conductor layer 226 and the second flexible conductor layer 229 is equivalent to the positive electrode of the thermocouple, and the other is equivalent to the negative electrode. The two wires 40a and 40b are the positive and negative electrode wires, respectively. The one of the first flexible conductor layer 226 and the second flexible conductor layer 229 that is the positive electrode of the thermocouple is connected to the positive electrode wire, and the one that is the negative electrode is connected to the negative electrode wire.

[0048] It is understood that the thermocouples described in this article can be any of the following types that meet the requirement that both the positive and negative electrode materials can withstand a certain degree of bending: Type K thermocouple, with a positive electrode material of nickel-chromium alloy and a negative electrode material of nickel-silicon alloy; Type T thermocouple, with a positive electrode material of copper and a negative electrode material of copper-nickel alloy; Type J thermocouple, with a positive electrode material of pure iron and a negative electrode material of copper-nickel alloy; and Type N thermocouple, with a positive electrode material of nickel-chromium-silicon alloy and a negative electrode material of nickel-silicon-magnesium alloy.

[0049] To transmit radio frequency current to the flexible metal electrode layer 223 for ablation, the energized area of ​​the flexible metal electrode layer 223 is connected to the distal end of the radio frequency cable of the radio frequency ablation conduit 100, and the proximal end of the radio frequency cable is connected to the radio frequency device. The energized area can be located at the proximal end of the flexible metal electrode layer 223, or it can be located in the portion between the proximal and distal ends of the flexible metal electrode layer 223.

[0050] The flexible electrode 22 of this embodiment integrates the functions of an ablation electrode and a thermocouple. It incorporates a radio frequency (RF) conduction region in the flexible metal electrode layer 223 to conduct RF energy to the target tissue. Furthermore, it features a distal connection between the first flexible conductor layer 226 and the second flexible conductor layer 229, with the connection point corresponding to the RF conduction region, to monitor the temperature of that region. In summary, the flexible electrode 22 of this embodiment integrates the functions of an ablation electrode and a thermocouple.

[0051] When the radiofrequency ablation catheter 100 employs the flexible electrode 22 of this embodiment, the resistance encountered during intervention in the patient's body is reduced. This is due, in part, to the flexibility of each layer of the flexible electrode 22 designed in this embodiment, resulting in excellent overall flexibility. The flexible electrode 22 can deform with the expansion and contraction of the support carrier 10, allowing it to adapt to the contracted state, thus reducing the volume of the contracted support carrier 10 and the flexible electrode 22. Furthermore, the flexible metal electrode layer 223, the first flexible conductor layer 226, and the second flexible conductor layer 229 are stacked along their thickness direction, eliminating the need for the temperature monitoring component to occupy additional space on the surface of the support carrier 10, further contributing to the reduction in volume of the contracted support carrier 10 and the flexible electrode 22.

[0052] In some embodiments of this disclosure, a first adhesive layer 225 may be provided between the liner layer 224 and the first flexible conductor layer 226. The first adhesive layer 225 is used to bond the liner layer 224 and the first flexible conductor layer 226 together, which helps to improve the stability of the relative position of the liner layer 224 and the first flexible conductor layer 226.

[0053] Figure 5 is a simplified schematic diagram of the connection between the flexible electrode 22 and the wires in some embodiments of this disclosure. Referring to Figure 5, the proximal end of the first flexible conductor layer 226 has a first connection region, which is connected to one of the two wires (i.e., wire 40a). Similarly, the proximal end of the second flexible conductor layer 229 has a second connection region, which is used to connect to the other of the two wires (i.e., wire 40b). It can be understood that the connection positions of the first connection region and the corresponding wire 40a, and the connection positions of the second connection region and the corresponding wire 40b, are varied.

[0054] In some embodiments of this disclosure, as shown in FIG5, the orthographic projections of the first connection region and the second connection region on the first surface are staggered, and the orthographic projection of the first connection region on the first surface may not fall within the orthographic projection area of ​​the second flexible conductor layer 229 on the first surface. FIG6 is a simplified schematic diagram of the connection between the flexible electrode 22 and the wire in some other embodiments of this disclosure. Compared with the technical solution shown in FIG6 where the orthographic projection of the first connection region on the first surface falls within the orthographic projection area of ​​the second flexible conductor layer 229 on the first surface, this embodiment is designed such that the second flexible conductor layer 229 does not need to be designed with an insulating hole 2291 for the wire 40a to pass through. This not only simplifies the structural design of the flexible electrode 22 and facilitates manufacturing, but also helps to prevent the first flexible conductor layer 226 from short-circuiting with the second flexible conductor layer 229 through the wire 40a.

[0055] As shown in Figure 5(A), the proximal end of the first flexible conductor layer 226 may extend beyond the proximal end of the substrate layer 227 in its extension direction. In this example, the orthographic projection of the first flexible conductor layer 226 on the first surface does not partially coincide with the orthographic projection of the substrate layer 227 on the first surface, while the orthographic projection of the second flexible conductor layer 229 on the first surface falls within the orthographic projection of the substrate layer 227 on the first surface. The first connection region is located at the portion of the first flexible conductor layer 226 that protrudes from the substrate layer 227.

[0056] Referring to Figures 3 and 5(B), the orthographic projection of the first flexible conductor layer 226 on the first surface can also be designed to fall within the boundary of the orthographic projection area of ​​the substrate layer 227 on the first surface, and the proximal end of the substrate layer 227 extends beyond the proximal end of the second flexible conductor layer 229 in its own extension direction, that is, the proximal end of the substrate layer 227 protrudes beyond the proximal end of the second flexible conductor layer 229. To achieve the connection, a first conductive via 2273 is also provided at the proximal end of the substrate layer 227, and the first connection area is connected to the wire 40a through the first conductive via 2273.

[0057] By comparison, it can be seen that in the embodiment shown in Figure 5(A), the conductor 40a can extend directly to connect with the first connection area, and the transmission loop of the thermocouple circuit current between the conductor 40a and the first connection area eliminates the need for the first conductive via 2273 in the substrate layer 227, which helps to reduce resistance and energy loss. In the embodiment shown in Figure 5(B), thanks to the fact that the proximal end of the first flexible conductor layer 226 does not protrude from the substrate layer 227, the risk of short circuits caused by electrical interference sources in the environment to the first flexible conductor layer 226 and the second flexible conductor layer 229 is reduced.

[0058] In some embodiments of this disclosure, referring further to FIG3, the flexible electrode 22 may further include a back film layer 231, which is stacked on the side of the second flexible conductor layer 229 facing away from the flexible metal electrode layer 223. When the flexible electrode 22 is applied to the radiofrequency ablation catheter 100, the side of the back film layer 231 facing away from the flexible metal electrode layer 223 is attached to the outer surface of the support carrier 10. The back film layer 231 is made of a flexible insulating material, which may be polyimide (PI), polyethylene terephthalate (PET), polyurethane (PU), or a combination thereof. By introducing the back film layer 231, this embodiment provides electrical and mechanical insulation protection for the side of the second flexible conductor layer 229 facing away from the flexible metal electrode layer 223, reducing the risk of short circuits by isolating electrical interference sources in the external environment from connecting with the second flexible conductor layer 229. Furthermore, since the back membrane layer 231 is made of flexible insulating material, the flexible electrode 22 still has good overall flexibility after the back membrane layer 231 is introduced, which can still improve the problem of high resistance encountered by the radiofrequency ablation catheter 100 when it is inserted into the human body.

[0059] In this example, as shown in Figures 3 and 4(B), the proximal end of the backsheet layer 231 is further provided with a first through hole 2311 and a second through hole 2312 spaced apart from each other. The first through hole 2311 is configured to expose the connection point between the first conductive via 2273 and the wire 40a, and the second through hole 2312 is configured to expose the connection point between the second connection area and the wire 40b. That is, by using the first through hole 2311 to define the connection position of the wire 40a and using the second through hole 2312 to define the connection position of the wire 40b, the backsheet layer 231 can prevent the connection between the first conductive via 2273 and the wire 40a, and the connection between the second connection area and the wire 40b, from being obstructed. The shapes of the first conductive via 2273, the first through hole 2311, and the second through hole 2312 are not limited and can be any of the following: circular, rectangular, elliptical, etc.

[0060] In some embodiments of this disclosure, the first through hole 2311 may be completely or partially opposite to the first conductive via 2273, and the first through hole 2311 exposes at least a portion of the first conductive via 2273.

[0061] In other embodiments of this disclosure, as shown in Figures 3 and 4(B), the first through hole 2311 and the first conductive via 2273 can be completely offset. In this example, the flexible electrode 22 may also include a conductive layer 232, which is disposed in the same layer as the second flexible conductor layer 229. The conductive layer 232 and the proximal end of the second flexible conductor layer 229 are adjacent and spaced apart. The conductive layer 232 is connected to the first conductive via 2273, and the first through hole 2311 exposes the conductive layer 232. By introducing the conductive layer 232, the positional relationship between the first through hole 2311 and the first conductive via 2273 can be flexibly arranged in this embodiment. Even if they are offset, the first conductive via 2273 can still be connected to the wire 40a through the conductive layer 232. As shown in Figure 3, the size of the first conductive via 2273 can be smaller than that of the first through hole 2311; of course, in other embodiments, the size of the first conductive via 2273 can also be greater than or equal to the size of the first through hole 2311.

[0062] In some embodiments, the distal end of the wire 40a can be directly electrically connected to the portion exposed by the first through-hole 2311. In some embodiments, a conductive metal material (e.g., gold, silver, platinum, copper) can also be deposited in the first through-hole 2311 and the second through-hole 2312 using a deposition process. Exemplarily, the deposition process can be either electroplating or chemical plating (e.g., physical vapor deposition PVD, chemical vapor deposition CVD). Taking gold plating of the first through-hole 2311 and the second through-hole 2312 as an example, a schematic diagram of the back side of the resulting flexible electrode 22 is shown in Figure 7. The gold plating layer 233a corresponding to the first through-hole 2311 and the gold plating layer 233b corresponding to the second through-hole 2312 are exposed on the back side of the flexible electrode 22 for connection with the distal ends of the two wires 40a and 40b by means of welding or other methods. By depositing plating layers in the first through-hole 2311 and the second through-hole 2312, the connection reliability between the plating layer and the wire is stronger, which is beneficial to improving the stability of the electrical connection. As can be seen from the above, as shown in Figure 3, in the embodiment where the first through hole 2311 and the first conductive via 2273 are completely offset, the conductive metal material will not be deposited into the first conductive via 2273 during the subsequent deposition process. Therefore, even if the aperture of the first conductive via 2273 is designed to be small, it will not have a negative impact on the ease of the deposition process, and the aperture of the first conductive via 2273 has little limitation.

[0063] The configuration of the proximal end of the backsheet layer 231 is not limited; for example, it can be any shape such as circular, rectangular, or elliptical. For example, as shown in Figures 3 and 4(B), the proximal end of the backsheet layer 231 can be constructed as a rectangle, with the first through-hole 2311 and the second through-hole 2312 located at opposite ends of the rectangle's diagonal along its extension direction. In other words, the first through-hole 2311 and the second through-hole 2312 are respectively located near the two opposite corners of the proximal end of the rectangular backsheet layer 231. This design in this embodiment allows for a larger distance between the first through-hole 2311 and the second through-hole 2312 without changing other parameters when the proximal end of the backsheet layer 231 is rectangular. This helps reduce the risk of short circuits caused by the connection points of the flexible electrode 22 to the respective wires 40a and 40b.

[0064] It should be noted that the rectangle referred to in this article is not limited to right-angled rectangles, but can also be rounded rectangles or their variations.

[0065] In some embodiments of this disclosure, a second adhesive layer 228 may be provided between the substrate layer 227 and the second flexible conductor layer 229. The second adhesive layer 228 is used to bond the substrate layer 227 and the second flexible conductor layer 229 together, which helps to improve the stability of the relative position of the substrate layer 227 and the second flexible conductor layer 229. The second adhesive layer 228 has a first opening 2281 corresponding to the position of the electrical connection portion 2271, and a second opening 2282 corresponding to the position of the first conductive via 2273. This prevents the second adhesive layer 228 from obstructing the electrical connection portion 2271 and the first conductive via 2273, thus ensuring the smooth construction of the electrical connection path.

[0066] In some embodiments, when the flexible electrode 22 further includes a back film layer 231, a third adhesive layer 230 may be provided between the back film layer 231 and the second flexible conductor layer 229. The third adhesive layer 230 is used to bond the back film layer 231 and the second flexible conductor layer 229 together, which helps to improve the stability of the relative positions of the back film layer 231 and the second flexible conductor layer 229. Specifically, the third adhesive layer 230 has a third opening 2301 corresponding to the position of the first through hole 2311, and a fourth opening 2302 corresponding to the position of the second through hole 2312. This prevents the third adhesive layer 230 from obstructing the connection points between the flexible electrode 22 and the two wires 40a and 40b, thus ensuring the smooth construction of the electrical connection path. In embodiments where the first through hole 2311 and the second through hole 2312 are subsequently covered with metal using a deposition process, this also facilitates the smooth execution of the subsequent deposition process.

[0067] In some embodiments of this disclosure, as shown in FIG3, the flexible electrode 22 may further include a coating layer 221, which is disposed on the side of the flexible metal electrode layer 223 facing away from the liner layer 224. The coating layer 221 is made of a flexible insulating material. Exemplarily, the material of the coating layer 221 may be polyimide (PI), polyethylene terephthalate (PET), polyurethane (PU), or a combination thereof. By introducing the coating layer 221, this embodiment can provide electrical and mechanical insulation protection for the first surface, preventing electrical interference sources in the external environment from connecting with the flexible metal electrode layer 223 to reduce the risk of short circuits. Due to the fact that the coating layer 221 is made of a flexible insulating material, the flexible electrode 22 as a whole still has good flexibility after the introduction of the coating layer 221, so that the problem of high resistance encountered by the radiofrequency ablation catheter 100 using this flexible electrode 22 during human intervention can still be improved.

[0068] The coating layer 221 has a first window 2211 and a second window 2212. The first window 2211 exposes the electrical contact area, and the second window 2212 exposes the radio frequency (RF) conduction area. This ensures that, except for the electrical contact area and the RF conduction area, the other areas of the flexible metal electrode layer 223 are protected by the coating layer 221. On the one hand, this prevents the coating layer 221 from obstructing the connection between the electrical contact area and the RF cable; on the other hand, it limits the output range of RF energy to the RF conduction area, thus defining the area of ​​RF ablation. The second window 2212 can be, for example, 8 mm in length and 4 mm in width, resulting in an RF ablation area of ​​approximately 4 mm × 8 mm for the flexible electrode 22.

[0069] In this embodiment, the distal end of the RF cable can be directly extended to the first window 2211 and connected to the contact area, or a deposition process can be used to deposit conductive metal materials (such as gold, silver, platinum, and copper) into the first window 2211 and the second window 2212. Taking gold plating of the first window 2211 and the second window 2212 as an example, a front view of the resulting flexible electrode 22 is shown in Figure 8. The gold plating layer 233c corresponding to the first window 2211 and the gold plating layer 233d corresponding to the second window 2212 are exposed on the front side of the flexible electrode 22 and in the surrounding environment. By depositing plating layers in the first window 2211 and the second window 2212, it is beneficial to reduce the possibility of the contact area and the RF conduction area being exposed and oxidizing with air to form an oxide layer, thereby reducing contact resistance, improving RF energy conduction efficiency, and enhancing the ablation effect.

[0070] In some embodiments, when the flexible electrode 22 further includes a coating layer 221, a fourth adhesive layer 222 may be provided between the coating layer 221 and the flexible metal electrode layer 223. The fourth adhesive layer 222 is used to bond the coating layer 221 and the flexible metal electrode layer 223 together, which helps to improve the stability of the relative positions of the coating layer 221 and the flexible metal electrode layer 223. Specifically, the fourth adhesive layer 222 has a fifth opening 2221 corresponding to the position of the first window 2211, and a sixth opening 2222 corresponding to the position of the second window 2212. This avoids the fourth adhesive layer 222 obstructing the electrode contact area and the radio frequency conduction area, ensuring that the radio frequency conduction area can output radio frequency current and facilitating the electrical connection between the radio frequency cable and the electrode contact area. In embodiments where the first window 2211 and the second window 2212 are covered with metal using a deposition process, subsequent deposition processes can also proceed smoothly.

[0071] In some embodiments of this disclosure, the total thickness of the flexible electrode 22 can be configured to be less than or equal to 0.2 mm. The total thickness of the flexible electrode 22 can be selected from any value among 0.15 mm, 0.16 mm, 0.17 mm, 0.18 mm, 0.19 mm, and 0.2 mm. This design results in a smaller overall thickness of the flexible electrode 22, which allows for a smaller volume of the radiofrequency ablation catheter 100 when inserted into the human body, thus positively impacting the reduction of interventional resistance. Furthermore, due to the smaller overall thickness of the flexible electrode 22, its adaptability is higher, allowing it to withstand more bends and deform more frequently with the expansion and contraction of the support carrier 10, thereby extending its service life.

[0072] The first conductive via 2273 and the second conductive via 2272 in this embodiment can be formed using a through-silicon via (TSV) process or a copper insertion process; this embodiment does not impose any specific limitations on this. As disclosed herein, each adhesive layer (i.e., the first adhesive layer 225, the second adhesive layer 228, the third adhesive layer 230, and the fourth adhesive layer 222) can be any of epoxy resin, hot melt adhesive, polyurethane adhesive, acrylic adhesive, butyl adhesive, etc.

[0073] Referring to Figures 1 and 2, this disclosure also provides a radiofrequency ablation catheter 100, including an expandable support carrier 10 and a flexible electrode assembly 20. The flexible electrode assembly 20 includes one or more flexible electrodes 22 as described in any of the foregoing embodiments, each of which is attached to the support carrier 10. As described above, the support carrier 10 may be, but is not limited to, a shape memory metal component and a balloon 11. The distal end of the radiofrequency ablation catheter 100 can be deformed to achieve a smaller volume, thereby reducing the resistance encountered during its intervention in the human body.

[0074] In some embodiments of this disclosure, as shown in Figures 1 and 2, the radiofrequency ablation catheter 100 may further include a tube body 30, with the support carrier 10 being a balloon 11, the proximal end of which is disposed within the tube body 30. The tube body 30 not only supports the balloon 11, but its internal lumen also allows for the passage of radiofrequency cables and wires. The flexible electrode assembly 20 may include a fixing ring 21 and multiple flexible electrodes 22. The fixing ring 21 is sleeved around the proximal axial segment of the balloon 11. Each flexible electrode 22 is connected to the fixing ring 21. The distal and proximal ends of each flexible electrode 22 are located on opposite sides of the fixing ring 21 along its own axis. The portions of each flexible electrode 22 located distal to the fixing ring 21 are independent of each other. The portion of each flexible electrode 22 located distal to the fixing ring 21 forms an ablation terminal. At least two shared liner layers 224 and substrate layers 227 are present in the portions of each flexible electrode 22 located proximal to the fixing ring 21, forming a connection terminal. Thus, the flexible electrode assembly 20 has multiple ablation terminals and at least one connection terminal. The number of ablation terminals is the same as the number of flexible electrodes 22. The ablation terminals are attached to the balloon 11 by means of bonding or other methods. The connection terminal can extend into the lumen of the tube body 30 to connect with the wires and radio frequency cables passing through the lumen.

[0075] Figure 9 is a schematic diagram of the structure of a flexible electrode assembly 20 according to some embodiments of the present disclosure. As shown in Figure 9, the flexible electrode assembly 20 includes four flexible electrodes 22. The portions of the four flexible electrodes 22 located distal to the fixing ring 21 each form an ablation terminal. The four ablation terminals are independent of each other. The portions of every two flexible electrodes 22 located proximal to the fixing ring 21 share a liner layer 224 and a substrate layer 227 to form a connection terminal. Of course, in other embodiments of the present disclosure, the number of flexible electrodes 22 included in the flexible electrode assembly 20 can be 2, 3, 5, etc., and can be reasonably designed according to requirements.

[0076] This embodiment utilizes an integrated design to form a flexible electrode assembly 20 from multiple flexible electrodes 22. As an integrated component, the flexible electrode assembly 20 has a compact structure, facilitating standardized manufacturing and production. Compared to individually installing all the flexible electrodes 22 onto the balloon 11, this embodiment reduces the assembly steps between the flexible electrode assembly 20 and the balloon 11, improving assembly efficiency. Furthermore, the connection points between each flexible electrode 22 and the radio frequency cable and the two wires 40a and 40b in the shared liner layer 224 and substrate layer 227 are more concentrated, simplifying wiring.

[0077] In some embodiments of this disclosure, as shown in Figures 1 and 9, the flexible electrode assembly 20 includes a plurality of flexible electrodes 22. The distal ends of all flexible electrodes 22 are uniformly and spaced apart around the longitudinal axis of the balloon 11, and the distal ends of all flexible electrodes 22 are distributed sequentially from the proximal end to the distal end of the balloon 11 along the longitudinal axis of the balloon 11. That is, the distal ends of each flexible electrode 22 are arranged sequentially along a spiral curve on the surface of the balloon 11, and the normal distance between the distal end of each flexible electrode 22 and the distal end of the tube body 30 gradually increases. In this embodiment, by optimizing the layout of the distal ends of the plurality of flexible electrodes 22, the distribution of radio frequency energy can be effectively optimized.

[0078] This disclosure also provides a radiofrequency ablation system, including a radiofrequency device and a radiofrequency ablation catheter 100 of any of the foregoing embodiments, wherein the proximal end of the radiofrequency cable of the radiofrequency ablation catheter 100 is connected to the radiofrequency device. This radiofrequency ablation system can be used not only to treat arrhythmias but also to treat diseases such as tumors. When using this radiofrequency ablation system to ablate target tissue for a patient, the distal end of the radiofrequency ablation catheter 100 can be deformed to achieve a smaller volume, thereby reducing the resistance encountered during its intervention in the human body.

[0079] It should be understood that in this specification, the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship or dimensions based on the orientation or positional relationship or dimensions shown in the accompanying drawings. These terms are used only for ease of description and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this disclosure.

[0080] Furthermore, the terms "first," "second," and "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0081] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0082] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0083] This specification provides many different implementations or examples that can be used to implement this disclosure. It should be understood that these different implementations or examples are entirely exemplary and are not intended to limit the scope of this disclosure in any way. Those skilled in the art will be able to conceive of various variations or substitutions based on the disclosure of this specification, and these should all be covered within the scope of this disclosure. Therefore, the scope of this disclosure should be determined by the scope defined in the appended claims.

Claims

1. A flexible electrode for a radiofrequency ablation catheter, comprising: A flexible metal electrode layer has a first surface and a second surface opposite to the first surface along its own thickness direction. The power receiving area of ​​the flexible metal electrode layer is used to connect to the distal end of the radio frequency cable of the radio frequency ablation catheter. The distal end of the flexible metal electrode layer has a radio frequency conducting area, which is configured to conduct radio frequency energy to the target tissue. A liner layer is disposed on the second surface, the liner layer being made of a flexible insulating material; A first flexible conductor layer is stacked on the side of the liner layer facing away from the flexible metal electrode layer, and the first flexible conductor layer and the flexible metal electrode layer are insulated and isolated from each other by the liner layer. A substrate layer is disposed on the side of the first flexible conductor layer facing away from the flexible metal electrode layer, and an electrical connection portion is provided at the far end of the substrate layer. The substrate layer is made of a flexible insulating material. A second flexible conductor layer is stacked on the side of the substrate layer facing away from the flexible metal electrode layer. The second flexible conductor layer and the first flexible conductor layer are insulated and isolated from each other by the substrate layer. The distal end of the second flexible conductor layer is electrically connected to the distal end of the first flexible conductor layer through the electrical connection portion. The orthographic projection of the connection points of the distal ends of the first flexible conductor layer and the distal ends of the second flexible conductor layer with the electrical connection portion on the first surface falls within the radio frequency conduction area. The proximal ends of the second flexible conductor layer and the proximal ends of the first flexible conductor layer are used to connect with the distal ends of the two wires of the radio frequency ablation catheter to form a thermocouple circuit, respectively.

2. The flexible electrode according to claim 1, wherein, The first flexible conductor layer has a first connection region near its end, and the first connection region is connected to one of the two wires. The proximal end of the second flexible conductor layer has a second connection region for connection with another of the two wires; The orthographic projections of the first connection region and the second connection region onto the first surface are offset, and the orthographic projection of the first connection region onto the first surface does not fall into the orthographic projection area of ​​the second flexible conductor layer onto the first surface.

3. The flexible electrode according to claim 2, wherein, The orthographic projection of the first flexible conductor layer onto the first surface falls within the boundary of the orthographic projection area of ​​the substrate layer onto the first surface, and the proximal end of the substrate layer extends beyond the proximal end of the second flexible conductor layer in its own extension direction. A first conductive via is provided near the end of the substrate layer. The first conductive via is provided in the portion of the substrate layer that extends beyond the near end of the second flexible conductor layer. The first connection area is connected to one of the two wires through the first conductive via.

4. The flexible electrode according to claim 3 further includes a back film layer stacked on the side of the second flexible conductor layer facing away from the flexible metal electrode layer, the side of the back film layer facing away from the flexible metal electrode layer being used to connect with the support carrier of the radiofrequency ablation catheter, the back film layer being made of a flexible insulating material; The proximal end of the back film layer is provided with a first through hole and a second through hole spaced apart from each other. The first through hole is used to expose the connection point between the first conductive through hole and one of the two wires, and the second through hole is used to expose the connection point between the second connection area and the other of the two wires.

5. The flexible electrode according to claim 4 further includes a conductive layer, wherein the conductive layer is disposed in the same layer as the second flexible conductor layer, the conductive layer and the second flexible conductor layer are adjacent to each other at their proximal ends and spaced apart, and the first conductive via is connected to one of the two wires through the conductive layer.

6. The flexible electrode according to claim 4 or 5, wherein, The near end of the backsheet layer has a rectangular configuration, and the first through hole and the second through hole are located at both ends of the diagonal of the rectangle along its own extension direction.

7. The flexible electrode according to any one of claims 1 to 6 further includes a coating layer, the coating layer being disposed on the side of the flexible metal electrode layer opposite to the substrate layer, the coating layer having a first window and a second window, the first window exposing the electrical contact area, and the second window exposing the radio frequency conduction area; the coating layer is made of a flexible insulating material.

8. The flexible electrode according to claim 7, wherein, The electrical connection portion is a second conductive via, which penetrates the thickness of the far end of the substrate layer.

9. The flexible electrode according to any one of claims 1 to 8, wherein, The total thickness of the flexible electrode is less than or equal to 0.2 mm.

10. A radiofrequency ablation catheter, comprising: An expandable support carrier and a flexible electrode assembly, the flexible electrode assembly comprising one or more flexible electrodes as described in any one of claims 1 to 9, the flexible electrodes being attached to the support carrier.

11. The radiofrequency ablation catheter according to claim 10 further includes a tube body, wherein the support carrier is a balloon, and the proximal end of the balloon is disposed in the tube body; The flexible electrode assembly includes: A retaining ring is fitted onto the outer periphery of the proximal axial segment of the balloon; as well as The plurality of flexible electrodes are all connected to the fixed ring, and the distal and proximal ends of any flexible electrode are located on both sides of the fixed ring along its axial direction. The portions of each flexible electrode located on the distal side of the fixed ring are independent of each other and attached to the balloon. The portions of each flexible electrode located on the proximal side of the fixed ring have at least two that share the liner layer and the substrate layer and extend into the lumen of the tube body.

12. The radiofrequency ablation catheter according to claim 11, wherein, The distal ends of all the flexible electrodes are evenly and spaced around the longitudinal axis of the balloon, and the distal ends of all the flexible electrodes are distributed sequentially from the proximal end to the distal end of the balloon along the longitudinal axis of the balloon.

13. A radiofrequency ablation system, comprising: The radio frequency device and the radio frequency ablation catheter according to any one of claims 10 to 12, wherein the proximal end of the radio frequency cable of the radio frequency ablation catheter is connected to the radio frequency device.

Images