Balloon catheter for low-temperature treatment and intravascular heat exchange system

Abstract

The invention provides a balloon catheter for low-temperature treatment and an intravascular heat exchange system. The balloon catheter for low-temperature treatment comprises a catheter body and a balloon. The balloon sleeves the far section of the catheter main body; at least one first circulation opening is formed in the catheter wall of the far section of the catheter body and located in the balloon, and an inner cavity of the catheter body is communicated with an inner cavity of the balloon through the first circulation opening; at least one second circulation opening is formed in the tube wall of the near section of the catheter body, located outside the balloon and communicated with an inner cavity of the catheter body and the outside of the balloon catheter; the guide pipe main body can selectively guide the fluid medium to the first circulation opening or the second circulation opening; heat exchange system deployment and cooling medium injection are achieved through a single pipeline, a common guide sheath can be compatible, and the device has the advantages of being easy to operate, high in cooling efficiency, safe, reliable and the like.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a balloon catheter for cryogenic therapy and an intravascular heat exchange system. Background Technology

[0002] Therapeutic hypothermia (TH) is a proven and effective neuroprotective technique widely used in the treatment of neurological diseases such as stroke and traumatic brain injury. Current main methods of TH include surface cooling and intravascular cooling. Surface cooling, which involves covering the patient with ice blankets or caps, suffers from slow cooling rates and is prone to adverse reactions such as frostbite and shivering. To avoid the drawbacks of surface cooling, researchers have developed various intravascular cooling techniques. Currently, intravascular cooling techniques are mainly divided into three types: autologous blood perfusion, cooling fluid perfusion, and closed heat exchange catheters. Autologous blood perfusion involves drawing blood from the patient's aorta, cooling it externally, and then perfusing the cooled blood into the carotid artery to achieve intravascular cooling. While this method can achieve rapid and deep brain cooling, it requires a complex extracorporeal circulation system, and blood cells are prone to lysis due to temperature and pressure changes during circulation. Cooling fluid perfusion achieves cooling by injecting a cooling medium (such as hypothermic saline) into the patient's body. This method is relatively simple to operate, but injecting excessive saline may worsen cerebral edema, making it difficult to maintain for a long time. Closed-loop heat exchange catheters achieve cooling by circulating a cooling medium through a closed system. This method does not involve substance exchange with the blood, making it safer.

[0003] A Chinese patent with publication number CN115137549B discloses a double-layer heat exchange balloon, which uses the cooling liquid in the inner balloon to maintain the saline in the outer balloon at a low temperature. However, placing the balloon in an artery for a long time carries the risk of obstructing blood flow and inducing thrombosis. Therefore, it can only be placed in a larger vein for systemic cooling.

[0004] A Chinese patent with publication number CN119746240A discloses an endovascular interventional catheter for brain protection. This catheter uses the principle of phase change cooling to achieve selective cooling of brain regions without changing the normal catheter shape. However, its cooling power is low, and the original interventional devices (such as guide sheaths and aspiration catheters) need to be removed before the cooling catheter can be placed, making the operation more complicated and significantly increasing the operation time. In emergency scenarios such as acute ischemic stroke, every minute of delay may lead to irreversible neuronal death.

[0005] Secondly, in pursuit of minimally invasive procedures, catheter designs tend towards smaller diameters, which typically limits the number of lumens in the catheter. Traditional balloon catheters, to perform both "balloon expansion and occlusion" and "proximal fluid infusion," usually require a double-lumen or multi-lumen structure, which inevitably increases the catheter's outer diameter, making it difficult to pass through tortuous cerebral blood vessels. Furthermore, existing single-lumen catheters cannot easily and reliably switch between "balloon inflation" and "coolant release" flow modes through simple manipulation. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the purpose of this invention is to provide a balloon catheter for cryogenic therapy and an intravascular heat exchange system.

[0007] A balloon catheter for cryotherapy according to the present invention is characterized in that it comprises: a catheter body and a balloon; The balloon is fitted over the distal portion of the catheter body; The catheter body has at least one first access port on the distal section of the catheter wall. The first access port is located inside the balloon and connects the inner lumen of the catheter body and the inner lumen of the balloon. The catheter body has at least one second access port on the proximal wall, the second access port being located outside the balloon and communicating with the inner lumen of the catheter body and the outside of the cryotherapy balloon catheter; The catheter body can selectively guide the fluid medium to either the first or second flow port.

[0008] Preferably, the balloon catheter for cryotherapy further includes a first occlusion device and a second occlusion device; The inner diameter of the catheter body at the distal segment is smaller than the inner diameter of the catheter body at the proximal segment; The first sealing device is a hollow conduit with an outer diameter that is the same as the inner diameter of the conduit body at the proximal segment; The second sealing device is a solid guidewire or sealing rod with an outer diameter that matches the inner diameter of the catheter body at the distal end.

[0009] Preferably, the catheter body includes a first cavity and a second cavity, the first cavity being used to accommodate a guidewire for navigating the balloon catheter to a target location, and the second cavity being used to deliver the fluid medium.

[0010] Preferably, the balloon employs a compliant, semi-compliant, or non-compliant thermal conductivity design.

[0011] Preferably, at least one radiopaque mark is provided on the wall surface of the distal segment of the catheter body, and the radiopaque mark is distributed along the axial direction of the catheter body; And / or, the outer wall surface of the catheter body is coated with a hydrophilic coating, the hydrophilic coating being at least one of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polyacetylimide, polyacrylamide, polyacrylic acid, and polysaccharide materials.

[0012] According to the present invention, an intravascular heat exchange system using the cryotherapy balloon catheter described in any one of the above-mentioned methods further includes: a catheter seat and a heat exchange catheter; The cryotherapy balloon catheter is inserted into the lumen of the heat exchange catheter, and the catheter seat is connected to the proximal end of the heat exchange catheter; The conduit seat is provided with a cooling medium outlet; The second access port in the balloon catheter for cryotherapy is located in the lumen of the heat exchange catheter; After the balloon is fully inflated, the outer diameter of the balloon is larger than the inner diameter of the distal opening of the heat exchange conduit. The balloon blocks the distal opening of the heat exchange conduit, and a distally closed cooling medium return channel is formed between the cryotherapy balloon conduit and the inner wall of the heat exchange conduit.

[0013] Preferably, a sealing ring is provided at the proximal end of the catheter seat, and the sealing ring is located between the inner wall of the catheter seat and the outer wall of the catheter body.

[0014] Preferably, the cooling mechanism of the intravascular heat exchange system includes internal circulation cooling of the cooling medium and phase change cooling; When the cooling mechanism is internal circulation cooling of the cooling medium, the cooling medium includes water, saline and liquid nitrogen; the cooling medium flows sequentially through the conduit body, the cooling medium return channel and the conduit seat, and flows out from the cooling medium outlet. During the flow of the cooling medium, heat exchange occurs with the blood outside the heat exchange conduit. When the cooling mechanism is phase change cooling, the outlet of the cooling medium is connected to a negative pressure device, so that the pressure inside the heat exchange conduit can reduce the boiling point of the cooling medium to below the physiological temperature. The cooling medium undergoes a spontaneous phase change in the cooling medium return channel, and the phase change carries away the heat from the blood flow around the heat exchange conduit.

[0015] Preferably, a temperature sensor is provided on the outer wall of the heat exchange conduit, and the temperature sensor is used to detect the blood vessel temperature in real time.

[0016] A pressure sensor is installed at the media inlet of the balloon catheter for cryotherapy. The pressure sensor is used to measure the pressure at the media inlet of the balloon catheter for cryotherapy, and the state of the balloon is determined by the change in the pressure.

[0017] Preferably, the outer wall of the heat exchange conduit is coated with an anticoagulant coating, which is at least one of heparin, citrate, and hydrogel.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention allows the fluid medium to be selectively guided to either the first or second flow port via the catheter body, enabling two directions of the fluid medium. The balloon catheter can be directly inserted into the conventional guide sheath that has already been placed in the neurointerventional surgery to locally cool the blood around the guide sheath without removing the original instrument or requiring a second puncture. This has significant clinical value for the time-sensitive emergency treatment of stroke. The catheter body selects to guide the dilation medium to the first flow port. The dilation medium enters the balloon through the catheter body. After the balloon is inflated, the open guide sheath is immediately converted into a closed heat exchange outer tube. The catheter body then selects to guide the cooling medium to the second flow port. The cooling medium enters the heat exchange outer tube through the catheter body, thereby performing hypothermia treatment. The closed-loop system formed by the balloon occlusion is used for closed cooling, avoiding the risk of cerebral edema caused by excessive fluid load. Both media are delivered using the catheter body, ensuring a small outer diameter of the catheter. The balloon catheter has a simple, reliable, and easy-to-operate structure with no irregular structure, and has little impact on blood flow. This invention is compatible with multiple cooling mechanisms, greatly expanding its applicability. Due to the adoption of an open fluid guiding structure, this system is not only suitable for conventional low-temperature brine circulation (sensible heat cooling), but also particularly suitable for phase change medium cooling (latent heat cooling) such as liquid nitrogen. When using a phase change medium, the balloon sealing structure of this invention can effectively isolate the vaporized medium from the blood. Combined with negative pressure recovery, it can achieve ultra-high efficiency cooling while ensuring absolute safety. Attached Figure Description

[0019] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall axial cross-section of the balloon catheter, which is the main feature of this invention. Figure 2 This is a partial enlarged view illustrating the structure of the distal segment of the balloon catheter, which is the main feature of this invention. Figure 3 This is a schematic diagram of the overall axial cross-section of the intravascular heat exchange catheter, which is the main feature of this invention. Figure 4 The present invention mainly illustrates the axial cross-sectional view of the intravascular heat exchange catheter in its first working state, as well as the cross-sectional view corresponding to the positions of the first and second flow ports. Figure 5 The present invention mainly illustrates the axial cross-sectional view of the intravascular heat exchange catheter in the second working state, as well as the cross-sectional view corresponding to the positions of the first and second flow ports. Figure 6 This invention primarily demonstrates the changes in cooling power and internal pressure of an intravascular heat exchange system as a function of the injection rate of the cooling medium.

[0020] The figure shows: 1. Catheter body; 2. Balloon; 3. Catheter seat; 4. Heat exchange duct; 5. First sealing device; 6. Second sealing device; 101. Proximal section; 102. Distal section; 11. First flow port; 12. Second flow port; 13. Medium injection port; 31. Cooling medium outlet; 32. Sealing ring. Detailed Implementation

[0021] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0022] like Figure 1 As shown, a balloon catheter for cryotherapy provided by the present invention includes: a catheter body 1 and a balloon 2.

[0023] The catheter body 1 includes a proximal segment 101 and a distal segment 102.

[0024] The balloon 2 is fitted onto the wall of the distal segment 102 of the catheter body 1.

[0025] A medium inlet 13 is provided at the proximal end 101 of the conduit body 1, which is away from the distal end 102. The fluid medium enters the conduit body 1 through the medium inlet 13. The fluid medium includes an expansion medium and a cooling medium.

[0026] The catheter body 1 has at least one first flow port 11 on the wall of its distal segment 102. The first flow port 11 is located inside the balloon 2 and connects the inner lumen of the catheter body 1 and the inner lumen of the balloon 2. A space consisting only of the first flow port 11 is formed between the balloon 2 and the catheter body 1.

[0027] The catheter body 1 has at least one second access port 12 on the wall of the proximal segment 101. The second access port 12 is located outside the balloon 2 and connects the inner lumen of the catheter body 1 with the outside of the cryotherapy balloon catheter.

[0028] The catheter body 1 can selectively guide the fluid medium to the first flow port 11 or the second flow port 12.

[0029] Specifically, the first flow port 11 and the second flow port 12 are obtained through laser processing.

[0030] The balloon catheter is placed into the conventional guide sheath that has already been placed during the balloon catheter insertion procedure in the neurointerventional surgery.

[0031] An expansion medium is injected into the catheter body 1 through the medium injection port 13. The catheter body 1 guides the expansion medium to the first flow port 11. The expansion medium enters the inner lumen of the balloon 2 from the inner lumen of the catheter body 1, and the balloon 2 expands. After expansion, the balloon 2 transforms the open guide sheath into a closed heat exchange outer tube.

[0032] Cooling medium is injected into the catheter body 1 through the medium injection port 13. The catheter body 1 selects to guide the cooling medium to the second flow port 11. The cooling medium is transported from the catheter body 1 to the second flow port 12. The cooling medium enters the gap between the balloon catheter and the guide sheath from the inner lumen of the catheter body 1.

[0033] The fluid medium can be selectively guided to either the first flow port 11 or the second flow port 12 through the catheter body 1, achieving two directions for the fluid medium. The balloon catheter can be directly inserted into the conventional guide sheath that has already been placed in the neurointerventional surgery to locally cool the blood around the guide sheath without removing the original instrument or requiring a second puncture. This has significant clinical value for the time-sensitive emergency treatment of stroke.

[0034] The catheter body 1 selects to guide the expansion medium to the first flow port 11. The expansion medium enters the balloon 2 through the catheter body 1. After the balloon 2 expands, it immediately transforms the open guide sheath into a closed heat exchange outer tube. Then, the catheter body 1 selects to guide the cooling medium to the second flow port 11. The cooling medium enters the heat exchange outer tube through the catheter body 1, thereby performing hypothermia treatment. The closed-loop system formed by the balloon 2 provides closed cooling, avoiding the risk of cerebral edema caused by excessive fluid load.

[0035] Both media are transmitted using the catheter body 1, ensuring a small outer diameter of the catheter. The balloon catheter has a simple, reliable, and easy-to-operate structure with no irregular structure, and has little impact on blood flow.

[0036] In some feasible embodiments, the balloon catheter for cryotherapy also includes a first sealing device 5 and a second sealing device 6. The first sealing device 5 is used to seal the second access port 12, at which point the first access port 11 remains open and the second access port is closed. An expansion medium is injected into the catheter body 1 through the medium injection port 13. The expansion medium is transported from the catheter body 1 to the first access port 11 and then from the inner lumen of the catheter body 1 into the inner lumen of the balloon 2, causing the balloon 2 to expand. After expansion, the balloon 2 transforms the open guide sheath into a closed heat exchange outer tube. The second sealing device 6 is then used to seal the first access port 11. After sealing, the second sealing device 5 is removed from the second access port 12, at which point the first access port 11 is closed and the second access port 12 remains open. A cooling medium is injected into the catheter body 1 through the medium injection port 13. The cooling medium is transported from the catheter body 1 to the second access port 12 and then from the inner lumen of the catheter body 1 into the gap between the balloon catheter and the guide sheath.

[0037] like Figure 2 As shown, the inner lumen of the catheter body 1 features a variable diameter design from the proximal segment 101 to the distal segment 102. The inner diameter of the catheter body 1 at the distal segment 102 is smaller than that at the proximal segment 101, forming a stepped or sloping surface between them. This design of different inner diameters facilitates selective occlusion using different direct occlusion devices, thereby achieving balloon dilation and cooling medium injection separately. Specifically, the variable diameter technology can be achieved through co-extrusion gradient method or secondary thermoforming method.

[0038] The first sealing device 5 is a hollow conduit with an outer diameter that is the same as the inner diameter of the conduit body 1 at the proximal section 101. When the hollow conduit is inserted into the conduit body 1, the inserted end of the hollow conduit abuts against the step or slope formed at the connection between the distal section 102 and the proximal section 101 of the conduit body 1. The hollow conduit only makes an interference fit with the conduit body 1 at the proximal section 101, and the hollow conduit blocks the second flow port 12.

[0039] The second sealing device 6 is a solid guidewire or sealing rod with an outer diameter that is the same as the inner diameter of the catheter body 1 at the distal segment 102. When the solid guidewire or sealing rod is inserted into the catheter body 1, the solid guidewire or sealing rod passes through the inner lumen of the catheter body 1 at the proximal segment 101, and the inserted end of the solid guidewire or sealing rod abuts against the port of the catheter body 1 at the distal segment 102 away from the proximal segment 101. The solid guidewire or sealing rod seals the first flow port 11.

[0040] By using the variable inner diameter design of the conduit body 1, and in conjunction with external sealing devices of different diameters, the switching between two mutually exclusive functions was successfully achieved in a single-lumen pipeline. This flow path control logic based on the change of inner diameter achieves complex fluid control functions while maintaining the extremely fine outer diameter of the conduit, avoiding the high cost and failure risk of setting complex micro-valves inside the conduit.

[0041] In some feasible implementations, the catheter body 1 has a dual-lumen structure, including a first lumen and a second lumen. The first lumen is used to accommodate the guidewire to facilitate navigation of the balloon catheter to the target location, and the second lumen is used to deliver the fluid medium.

[0042] In some feasible implementations, balloon 2 employs a compliant, semi-compliant, or non-compliant thermally conductive design to adapt to different clinical needs and vascular anatomy. The balloon material may be polyethylene, polytetrafluoroethylene, polyurethane, silicone rubber, or nylon.

[0043] In some feasible embodiments, at least one radiopaque marker is provided on the wall surface of the distal segment 102 of the catheter body 1. The radiopaque marker is distributed along the axial direction of the catheter body 1, and the radiopaque marker facilitates the determination of the position of the catheter body 1 under imaging equipment such as X-ray. Specifically, the material of the radiopaque marker is a platinum-iridium alloy or a gold-palladium alloy.

[0044] In some feasible embodiments, the outer wall surface of the catheter body 1 is coated with a hydrophilic coating, which is at least one of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polyacetylimide, polyacrylamide, polyacrylic acid, and polysaccharide materials.

[0045] like Figure 3 As shown, the intravascular heat exchange system provided by the present invention, using the above-mentioned low-temperature therapeutic balloon catheter, further includes: catheter seat 3 and heat exchange catheter 4.

[0046] The heat exchange catheter 4 can be a guide sheath that has been placed during the preoperative procedure (such as mechanical thrombectomy). After the surgical instruments (such as aspiration catheter) are removed, the cryogenic balloon catheter provided by this invention can be directly inserted into the guide sheath to form an intravascular heat exchange system, avoiding repeated access construction and simplifying the surgical procedure.

[0047] The balloon catheter for cryotherapy is inserted into the lumen of the heat exchange catheter 4 and extends along the axial direction of the heat exchange catheter 4.

[0048] The conduit seat 3 is connected to the proximal end of the heat exchange conduit 4.

[0049] The second access port 12 in the balloon catheter for cryotherapy is located in the lumen of the heat exchange catheter 4; Once balloon 2 is fully inflated without external constraints, its outer diameter is larger than the inner diameter of the distal opening of heat exchange catheter 4. Balloon 2 blocks the distal opening of heat exchange catheter 4, and a distally closed cooling medium return channel is formed between the balloon catheter for cryotherapy and the inner wall of heat exchange catheter 4.

[0050] The intravascular heat exchange system provided in this embodiment has two core operating states: First working state (balloon dilation state): such as Figure 4 As shown, the expansion medium enters the catheter body 1 through the medium injection port 13 and enters the balloon 2 through the first flow port 11 located at the distal end 102, causing the balloon 2 to expand and block the heat exchange catheter 4, thus isolating the heat exchange catheter 4 from the external fluid.

[0051] Second working state (low-temperature treatment state): such as Figure 5 As shown, the cooling medium produced by the cooling medium production device located outside the body is pumped into the catheter body 1 through the medium injection port 13 and enters the annular space formed by the outer wall of the catheter body 1 and the inner wall of the heat exchange conduit 4 through the second flow port 12 of the proximal section 101. Then it flows back to the catheter seat 3 and flows out of the heat exchange system through the cooling medium outlet 31. During this process, the heat of the blood is absorbed by the cooling medium through the tube wall of the heat exchange conduit 4 and carried outside the body.

[0052] The present invention provides an intravascular heat exchange system that can realize the deployment of the heat exchange system and the injection of cooling medium through a single medium injection port, simplifying the operation process; at the same time, any catheter sheath can be transformed into a heat exchange catheter, avoiding the tediousness and risks of repeatedly building access routes.

[0053] In some feasible implementations, such as Figure 3 As shown, a sealing ring 32 is provided at the proximal end of the conduit seat 3, and the sealing ring 32 is located between the inner wall of the conduit seat 3 and the outer wall of the conduit body 1. The sealing ring 32 ensures the sealing of the cooling medium return path.

[0054] The cooling mechanisms of intravascular heat exchange systems include internal circulation cooling of the cooling medium and phase change cooling.

[0055] When the cooling mechanism is internal circulation cooling of the cooling medium, the cooling medium includes water, salt water and liquid nitrogen; the cooling medium flows sequentially through the main body of the conduit 1, the cooling medium return channel and the conduit seat 3, and flows out from the cooling medium outlet 31. During the flow of the cooling medium, heat exchange occurs with the blood outside the heat exchange conduit 4.

[0056] When the cooling mechanism is phase change cooling, the cooling medium outlet 31 is connected to a negative pressure device, so that the pressure inside the heat exchange conduit 4 can reduce the boiling point of the cooling medium to below the physiological temperature. The cooling medium undergoes a spontaneous phase change in the cooling medium return channel, and the phase change carries away the blood heat around the heat exchange conduit 4.

[0057] Specifically, when the cooling medium is brine or water, the cooling medium outlet 31 needs to be connected to a vacuum source to create a vacuum chamber in the heat exchange conduit 4, so that the boiling point of the cooling medium is lowered below the physiological temperature, thereby causing the cooling medium to vaporize violently and absorb heat from the surrounding environment.

[0058] Depending on the cooling mechanism and cooling medium, the intravascular heat exchange system provided by this invention can be used for both ultra-low temperature therapy and hypothermia therapy, and has a wide range of applications.

[0059] In some feasible implementations, a temperature sensor is provided on the outer wall of the distal end of the heat exchange catheter 4. The temperature sensor is used to detect the blood vessel temperature in real time and provide feedback to the operator or control system. Specifically, the temperature sensor is one or more of a resistance temperature detector (RTD), a thermistor, and a thermocouple.

[0060] In some feasible implementations, a pressure sensor is installed at the media injection port 13. The pressure sensor measures the pressure at the media injection port 13, and the status of the balloon is determined by monitoring changes in pressure, including whether the balloon is leaking. Real-time feedback based on fluid dynamics principles regarding balloon rupture or occlusion failure (such as a sudden pressure drop or inability to increase pressure) greatly improves surgical safety.

[0061] In some feasible embodiments, the outer wall of the heat exchange conduit 4 is coated with an anticoagulant coating, which is at least one of heparin, citrate, and hydrogel.

[0062] In some feasible implementations, the connection between the conduit seat 3 and the heat exchange conduit 4, as well as the cooling medium return port, adopts a standard Luer connector for easy connection.

[0063] In some feasible implementations, the heat exchange catheter 4 is based on the 8F-80cm guide sheath commonly used in neurointerventions, with an inner diameter of 2.9mm; the main body of the balloon 2 catheter is based on the 4F-115cm guide sheath commonly used in neurointerventions, with an outer diameter of 1.42mm. The inner lumen of the catheter body 1 adopts a variable diameter design, with a larger inner diameter of the proximal segment 101 (approximately 1.2mm) and a smaller inner diameter of the distal segment 102 (approximately 0.5mm). This variable diameter design is achieved through a secondary thermoforming method; the balloon 2 is made of a semi-compliant polyurethane film with an axial length of approximately 2cm and a wall thickness of 0.05mm-0.1mm. When inflated in an unconstrained state, its outer diameter is 4mm-5mm. The balloon 2 is fixed to the surface of the distal segment 102 of the catheter body 1 by thermoforming welding or adhesive.

[0064] In some embodiments, 2 to 4 circular first flow ports 11 are formed on the wall of the distal section 102 of the conduit body 1 inside the balloon 2, each with a diameter of 0.3 mm to 0.5 mm and a total flow area of ​​approximately 0.3 mm² to 0.8 mm², and the ports are evenly distributed along the axial direction; 4 to 6 second flow ports 12 with a diameter of 0.5 mm to 1 mm and a total flow area of ​​1 mm² to 5 mm² are formed on the wall of the proximal section 101 of the conduit body 1 near the balloon 2, and the ports are spirally arranged to promote the uniform flow of the cooling medium; both the first flow ports 11 and the second flow ports 12 can be obtained by laser processing.

[0065] In some embodiments, the media injection port 13 integrates a pressure sensor to assess the working status of the balloon 2 by monitoring changes in injection pressure. For example, with a total flow area of ​​0.5 mm² for the first flow port 11, the pressure should be stable between 6 atm and 10 atm when the balloon 2 is inflated. If the sensor shows a sudden drop in pressure (below 2 atm), or if continuous infusion fails to raise the pressure above 6 atm, it indicates that the balloon 2 is leaking. If the pressure is above 16 atm, it indicates that the pressure inside the balloon 2 is too high and there is a risk of rupture, and the infusion of the expansion medium should be stopped immediately.

[0066] In the second operating state of the intravascular heat exchange system, the pressure sensor can also monitor the pressure within the heat exchange catheter 4 in real time, thereby assessing the system's operating status. A specific example is given below. The dimensions of the heat exchange catheter 4 and the balloon catheter 2 are referenced to the aforementioned typical dimensions. It is assumed that the total flow area of ​​the second access port 12 is 2 mm², the cooling medium is 4°C physiological saline, and the cooling mechanism is low-temperature internal circulation cooling. If the circulation rate of the cooling medium is known, it can be calculated using the Poiseuille formula (…). Calculate the pressure at various points within the balloon 2 catheter and the heat exchange catheter 4, where μ is the viscosity of the medium (approximately 1 mPa·s for physiological saline), L is the flow path length, Q is the flow rate, and r is the radius of the flow path; simultaneously, the specific heat capacity can be calculated using the formula (…). Estimate the cooling efficiency of heat exchange conduit 4, where Cp represents the specific heat capacity of the cooling medium (physiological saline has a specific heat capacity of approximately 4.2 kJ / (kg·℃)), ΔT represents the temperature difference between the cooling medium before entering the heat exchange system (4℃) and after leaving the heat exchange system (it can be assumed that the temperature of the cooling medium after flowing out is 30℃), ρ represents the density of the cooling medium (physiological saline is approximately 1000 kg / m³), and the relationship between the circulation rate of the cooling medium and the pressure at the distal end of heat exchange conduit 4, the theoretical reading of the pressure sensor, and the expected cooling power is as follows: Figure 6 As shown, if the pressure sensor reading is significantly lower than the theoretical reading corresponding to the cycle rate, it can be determined that there is a leakage in the heat exchange conduit 4.

[0067] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0068] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A balloon catheter for cryotherapy, characterized in that, include: The catheter body (1) and the balloon (2); The balloon (2) is fitted onto the distal segment (102) of the catheter body (1). The catheter body (1) has at least one first flow port (11) on the wall of the distal segment (102). The first flow port (11) is located inside the balloon (2) and connects the inner lumen of the catheter body (1) and the inner lumen of the balloon (2). The catheter body (1) has at least one second access port (12) on the wall of the proximal segment (101). The second access port (12) is located outside the balloon (2) and connects the inner lumen of the catheter body (1) with the outside of the cryotherapy balloon catheter. The catheter body (1) can selectively guide the fluid medium to a first flow port (11) or a second flow port (12).

2. The balloon catheter for cryotherapy as described in claim 1, characterized in that, The balloon catheter for cryotherapy also includes a first occlusion device (5) and a second occlusion device (6). The inner diameter of the catheter body (1) at the distal segment (102) is smaller than the inner diameter of the catheter body (1) at the proximal segment (101); The first sealing device (5) is a hollow conduit with an outer diameter that is the same as the inner diameter of the conduit body (1) at the proximal section (101); The second sealing device (6) is a solid guide wire or sealing rod with an outer diameter that is the same as the inner diameter of the catheter body (1) at the distal segment (102).

3. The balloon catheter for cryotherapy as described in claim 1, characterized in that, The catheter body (1) includes a first cavity and a second cavity. The first cavity is used to accommodate a guidewire, which is used to navigate the balloon catheter to the target location. The second cavity is used to deliver the fluid medium.

4. The balloon catheter for cryotherapy as described in claim 1, characterized in that, The balloon (2) is designed to be compliant, semi-compliant or non-compliant in terms of thermal conductivity.

5. The balloon catheter for cryotherapy as described in claim 1, characterized in that, At least one radiopaque mark is provided on the wall surface of the distal segment (102) of the catheter body (1), and the radiopaque mark is distributed along the axial direction of the catheter body (1); And / or, the outer wall surface of the catheter body (1) is coated with a hydrophilic coating, the hydrophilic coating being at least one of polyvinylpyrrolidone, polyvinyl alcohol, polyethylene glycol, polyacetylimide, polyacrylamide, polyacrylic acid, and polysaccharide materials.

6. A heat exchange system within blood vessels, characterized in that, The balloon catheter for cryotherapy according to any one of claims 1 to 5 further includes: a catheter seat (3) and a heat exchange catheter (4). The cryotherapy balloon catheter is inserted into the lumen of the heat exchange catheter (4), and the catheter seat (3) is connected to the proximal end of the heat exchange catheter (4); The conduit seat (3) is provided with a cooling medium outlet (31); The second access port (12) in the cryotherapy balloon catheter is located in the lumen of the heat exchange catheter (4); After the balloon (2) is fully inflated, the outer diameter of the balloon (2) is larger than the inner diameter of the distal opening of the heat exchange conduit (4). The balloon (2) blocks the distal opening of the heat exchange conduit (4), and a distally closed cooling medium return channel is formed between the low-temperature treatment balloon conduit and the inner wall of the heat exchange conduit (4).

7. The intravascular heat exchange system as described in claim 6, characterized in that, The proximal end of the catheter seat (3) is provided with a sealing ring (32), which is located between the inner wall of the catheter seat (3) and the outer wall of the catheter body (1).

8. The intravascular heat exchange system as described in claim 6, characterized in that, The cooling mechanism of the intravascular heat exchange system includes internal circulation cooling of the cooling medium and phase change cooling. When the cooling mechanism is internal circulation cooling of the cooling medium, the cooling medium includes water, salt water and liquid nitrogen; the cooling medium flows sequentially through the main body of the conduit (1), the cooling medium return channel and the conduit seat (3), and flows out from the cooling medium outlet (31). During the flow of the cooling medium, heat exchange occurs with the blood outside the heat exchange conduit (4); When the cooling mechanism is phase change cooling, the cooling medium outlet (31) is connected to a negative pressure device so that the pressure inside the heat exchange conduit (4) can reduce the boiling point of the cooling medium to below the physiological temperature. The cooling medium undergoes a spontaneous phase change in the cooling medium return channel, and the phase change carries away the blood heat around the heat exchange conduit (4).

9. The intravascular heat exchange system as described in claim 6, characterized in that, A temperature sensor is provided on the outer wall of the heat exchange conduit (4), and the temperature sensor is used to detect the blood vessel temperature in real time. A pressure sensor is provided at the medium inlet of the balloon catheter for cryotherapy. The pressure sensor is used to measure the pressure at the medium inlet of the balloon catheter for cryotherapy and to determine the state of the balloon (2) by the change in pressure.

10. The intravascular heat exchange system as described in claim 6, characterized in that, The outer wall of the heat exchange conduit (4) is coated with an anticoagulant coating, which is at least one of heparin, citrate, and hydrogel.

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