Balloon catheter

Abstract

The application relates to the technical field of cardiovascular interventional medical instruments, in particular to a balloon catheter, which comprises a catheter and a balloon, the balloon is arranged on the catheter and can be collapsed and filled; the catheter is defined with a balloon injection channel, the balloon injection channel is communicated with the internal cavity of the balloon and is used for injecting liquid contrast agent into the balloon; at least one pressure relief hole is arranged on the balloon wall of the balloon, the pressure relief hole is configured to release the contrast agent outwards when the filling pressure in the balloon reaches a preset pressure value, and the contrast agent outflow can be detected by a medical imaging device. When the pressure in the balloon reaches a preset safe critical pressure, the contrast agent outflow at the pressure relief hole is clearly visible under X-ray perspective, which serves as an intuitive visual alarm to prompt an operator to immediately stop the injection of the contrast agent, so that the risk of tearing of the atrial septum and other tissues caused by excessive filling of the balloon is fundamentally eliminated while the diameter of the defect "waist" is accurately measured.

Description

Technical Field

[0001] This application relates to the field of cardiovascular interventional medical devices, specifically to a balloon catheter. Background Technology

[0002] The key to procedures such as interventional closure of atrial septal defects (ASD) and patent foramen ovale (PFO) closure lies in the accurate preoperative measurement of the dimensions of the defects, such as ASD and PFO. Taking ASD as an example, the balloon measurement method is widely used clinically to measure the size of ASD. This involves injecting contrast agent into a balloon that spans the defect under real-time ultrasound monitoring (such as transesophageal or transthoracic ultrasound). The "waist sign" formed by the balloon being compressed by the defect edge is observed under DSA (digital subtraction angiography) imaging, and the blood flow signals between the left and right atria flowing through the defect are observed to be completely blocked by the balloon (i.e., a "blood flow cutoff" phenomenon) as the core basis for judging whether the balloon is completely attached to the defect edge and whether the measurement is accurate.

[0003] However, this method has the following shortcomings: First, it is complex and highly dependent on other methods. Determining the measurement endpoint requires simultaneous use of transesophageal or transthoracic ultrasound and DSA equipment, which is cumbersome and requires high levels of medical resources and operator cooperation. Second, the interpretation of "blood flow cutoff" in ultrasound images is subject to observer variability, affecting measurement consistency. Third, "blood flow cutoff" is a functional endpoint and cannot directly reflect the actual mechanical pressure of the balloon on the fragile atrial septum tissue. To ensure measurement accuracy, the operator may inject additional blood after blood flow cutoff, leading to excessively high pressure inside the balloon, which may cause serious complications such as iatrogenic atrial septal tear and cardiac tamponade. Summary of the Invention

[0004] This application provides a new balloon catheter to address the problem of difficulty in intuitively judging balloon pressure during use.

[0005] To achieve one of the above objectives, one embodiment of this application provides a balloon catheter, comprising:

[0006] catheter;

[0007] And a balloon, disposed in the catheter, the balloon being collapsible and inflatable;

[0008] The catheter defines a balloon injection channel that communicates with the internal cavity of the balloon for injecting a liquid contrast agent into the balloon.

[0009] The balloon has at least one pressure relief hole on its wall. The pressure relief hole is configured such that when the inflation pressure inside the balloon reaches a preset pressure value, the pressure relief hole can release contrast agent that can be detected by medical imaging equipment.

[0010] In one embodiment, there are multiple pressure relief holes, at least two of which have different initial hole diameters, and the pressure relief holes with different initial hole diameters correspond to different preset pressure values.

[0011] In one embodiment, the balloon body is made of an elastic polymer material, and the initial pore diameter of the pressure relief orifice, the wall thickness of the balloon body, and the elastic modulus of the balloon body material satisfy the following relationship:

[0012] When the wall thickness and elastic modulus of the bladder are the same, the preset pressure value corresponding to the pressure relief hole with the smaller initial orifice diameter is higher than the preset pressure value corresponding to the pressure relief hole with the larger initial orifice diameter;

[0013] When the initial diameter of the pressure relief hole and the wall thickness of the bladder are the same, the preset pressure value corresponding to the pressure relief hole is higher when the elastic modulus of the bladder material is higher than the preset pressure value when the elastic modulus is lower.

[0014] When the initial diameter of the pressure relief hole and the elastic modulus of the bladder material are the same, the preset pressure value corresponding to the pressure relief hole when the wall thickness is thicker is higher than the preset pressure value when the wall thickness is thinner.

[0015] In one embodiment, the elastic modulus of the capsule material is from 30 MPa to 150 MPa;

[0016] And / or, the wall thickness of the capsule is 0.01 mm to 0.10 mm;

[0017] And / or, the initial diameter of the pressure relief hole is 0.02 mm to 0.20 mm;

[0018] And / or, the capsule material is thermoplastic polyurethane.

[0019] In one embodiment, the preset pressure value ranges from 10 mmHg to 40 mmHg, and the preset pressure value corresponding to the pressure relief hole with a larger initial orifice diameter is lower.

[0020] And / or, the plurality of pressure relief holes are distributed along the circumference and / or axial direction of the balloon, and there is a physical spacing between adjacent pressure relief holes so that they can be distinguished when different pressure relief holes begin to release the contrast agent.

[0021] In one embodiment, the plurality of pressure relief holes include a first pressure relief hole and a second pressure relief hole, wherein the first pressure relief hole and the second pressure relief hole are distributed at intervals along the axial direction of the balloon, and the interval distance is not less than 1.5 mm;

[0022] The initial diameter of the first pressure relief hole is 0.08 mm to 0.12 mm, and the corresponding preset pressure value is 8 mmHg to 12 mmHg; the initial diameter of the second pressure relief hole is 0.03 mm to 0.05 mm, and the corresponding preset pressure value is 18 mmHg to 22 mmHg.

[0023] In one embodiment, the total flow area of ​​the pressure relief orifice is not greater than the cross-sectional area of ​​the balloon injection channel.

[0024] In one embodiment, the balloon includes a contact segment and a first conical transition segment, the contact segment being for contacting tissue structures at the defect site, the first conical transition segment being connected to the proximal side of the contact segment, and the at least one pressure relief hole being distributed in the first conical transition segment or at the junction of the first conical transition segment and the contact segment.

[0025] In one embodiment, the pressure relief hole is a through hole or formed by a slit, the shape of the through hole includes at least one of circular and polygonal shapes, and the shape of the slit includes at least one of straight, cross, and star-shaped shapes.

[0026] In one embodiment, the catheter is further provided with a wire-threading channel, which is independent of the balloon injection channel;

[0027] The balloon catheter further includes an interface component connected to the catheter, the interface component comprising:

[0028] A balloon injection port, connected to the balloon injection channel, is used to connect to a contrast agent input device;

[0029] And a threading interface, which is connected to the threading channel, for inserting the guide wire.

[0030] To achieve one of the above objectives, another embodiment of this application provides a method for measuring hole size, including:

[0031] The balloon catheter is delivered to the hole to be measured, wherein the balloon catheter includes the balloon catheter described in any of the above embodiments;

[0032] Liquid contrast agent is continuously injected into the balloon through the balloon injection channel, so that the balloon is inflated and fits the edge of the hole to be measured.

[0033] Under the monitoring of medical imaging equipment, observe the waist morphology of the balloon and observe whether contrast agent leaks out from the pressure relief port;

[0034] When at least one of the pressure relief holes is observed to release contrast agent leakage, the injection of the liquid contrast agent is stopped, and the size of the hole to be measured is measured based on the image at this time.

[0035] In one embodiment, the balloon catheter includes a plurality of pressure relief holes as described in any of the above embodiments, wherein at least two of the plurality of pressure relief holes have different initial diameters and the pressure relief holes with different initial diameters correspond to different preset pressure values;

[0036] In this hole size measurement method, when observing whether the contrast agent is leaking and released, the maximum value of the preset pressure value corresponding to each pressure relief hole that causes the contrast agent leakage is used to determine whether to stop the injection.

[0037] According to the balloon catheter described in the above embodiment, a dynamic pressure relief valve mechanism is formed by pre-setting at least one pressure relief hole in the balloon wall and using liquid contrast agent as the filling medium. When the inflation pressure inside the balloon reaches a preset threshold, the pressure relief hole automatically opens, releasing the contrast agent and thus converting the invisible pressure into a visible imaging signal under medical imaging equipment. On the one hand, it achieves real-time visual monitoring and safety warning of balloon pressure; on the other hand, the leakage process itself actively reduces the pressure inside the balloon, stabilizing the balloon pressure within a safe upper limit and forming a physical self-balance. This design fundamentally avoids the risk of atrial septum tissue tearing due to over-inflation, and significantly improves surgical safety, especially for high-risk cases such as soft-edge defects, effectively overcoming the hidden danger of balloon pressure runaway in related technologies.

[0038] Furthermore, the leaked liquid contrast agent can be clearly visualized under DSA X-ray fluoroscopy. Operators can accurately determine whether the balloon completely seals the defect by observing the flow of the leaking contrast agent, providing objective and intuitive imaging evidence for determining the measurement endpoint. This reduces measurement deviations caused by inconsistent interpretations of ultrasound blood flow cutoff images by different operators, making the measurement results more objective, accurate, and repeatable. The appearance of the contrast agent leak signal directly corresponds to the balloon pressure reaching a preset safety threshold. Operators can make judgments without relying on complex interpretations of ultrasound images, simplifying the surgical procedure and significantly improving overall operational efficiency. This application transforms the pressure management challenge in interventional surgery into a design problem of fluid mechanics and materials mechanics, achieving a unity of precise measurement and active safety protection. Moreover, it requires no additional sensors, is simple to operate, and has significant clinical application value. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of a balloon catheter according to one embodiment;

[0040] Figure 2 This is a schematic diagram of the balloon portion of a balloon catheter according to one embodiment;

[0041] Figure 3 This is a schematic diagram of the proximal side of the balloon in a balloon catheter according to one embodiment.

[0042] In the diagram, 10 is the catheter; 11 is the balloon injection channel; 111 is the balloon injection port; 1111 is the first injection port; 1112 is the second injection port; and 12 is the wire threading channel.

[0043] 20. Balloon; 21. Pressure relief port; 211. First pressure relief port; 212. Second pressure relief port; 22. First conical transition section; 23. Contact section; 24. Second conical transition section;

[0044] 30. Interface component; 31. Balloon injection interface; 32. Threading interface. Detailed Implementation

[0045] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by related similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0046] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0047] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0048] The terms "proximal" and "distal" used in this article are conventional medical terms. For the instrument to be operated on, the proximal end is the end closer to the operator, and the distal end is the end furthest from the operator; it is usually the end that enters the patient's body first. For more information on proximal and distal ends, please refer to [link to relevant documentation]. Figure 1 The displayed location.

[0049] In interventional closure of cardiac structural abnormalities such as atrial septal defects or patent foramen ovale, accurate preoperative measurement of the defect or opening size is a crucial step in selecting the appropriate occluder model. The widely used balloon 20 measurement method involves delivering an ultra-thin thermoplastic polyurethane balloon catheter to the opening to be measured, injecting diluted contrast agent into the balloon 20 to inflate it, and then measuring the extension diameter using the waist-like shape formed by the compression of the balloon 20 by the opening edge under digital subtraction angiography. However, this method has the following inherent drawbacks: First, it is complex and highly dependent on other methods. Determining the measurement endpoint requires simultaneous use of transesophageal or transthoracic ultrasound and digital subtraction angiography, making the process cumbersome and demanding on medical resources and operator cooperation. Second, it poses safety risks. The "blood flow cutoff" determined by ultrasound is a functional endpoint and cannot directly reflect the actual mechanical pressure of the balloon 20 on the fragile atrial septum. To ensure accurate measurement, the operator may inject additional blood after the blood flow cutoff, leading to excessively high pressure within the balloon 20, which carries the risk of serious complications such as iatrogenic atrial septal tearing and cardiac tamponade. Currently, there is no direct and intuitive method for monitoring the pressure within the balloon 20 during the procedure. Third, the interpretation is highly subjective. The interpretation of the ultrasound image of blood flow cutoff is subject to observer differences, affecting measurement consistency.

[0050] This application provides a balloon catheter that, by providing at least one pressure relief hole 21 on the balloon wall of the balloon 20, utilizes the characteristic of the pressure relief hole 21 to release contrast agent that can be detected by medical imaging equipment when the inflation pressure inside the balloon 20 reaches a preset pressure value. This converts the invisible intra-balloon pressure into a visible leakage signal, allowing the operator to directly observe the pressure status under digital subtraction angiography equipment, thereby completing accurate measurements within a safe pressure range.

[0051] The technical solutions of this application will be described in detail below with reference to specific embodiments. It should be noted that the technical features in each embodiment can be freely combined without conflict, and the resulting technical solutions all fall within the protection scope of this application.

[0052] One embodiment of this application provides a balloon catheter; please refer to [reference needed]. Figures 1 to 3 The balloon catheter includes a catheter 10 and a balloon 20 disposed within the catheter 10. The balloon 20 is collapsible and inflatable; in its collapsed state, it can smoothly pass through the vascular lumen to reach the site of the hole to be measured; in its inflated state, it can contact the tissue structure at the edge of the hole to complete the dimensional measurement. The catheter 10 defines a balloon injection channel 11, which communicates with the internal cavity of the balloon 20 for injecting a liquid contrast agent into the balloon 20. The balloon 20 has at least one pressure relief hole 21 on its wall, configured such that when the inflation pressure inside the balloon 20 reaches a preset pressure value, the pressure relief hole 21 can release contrast agent that can be detected by medical imaging equipment.

[0053] The aforementioned medical imaging equipment can be a digital subtraction angiography (DSA) system or other imaging equipment capable of detecting liquid contrast agents. The liquid contrast agent can be iohexol solution, iopamidol solution, or other iodine-containing non-ionic X-ray contrast agents. When injecting the liquid contrast agent, a hand-operated syringe or a high-pressure injection pump can be used as the contrast agent infusion device.

[0054] When the internal pressure of balloon 20 does not reach the preset pressure value, the capillary resistance at the pressure relief port 21 and the elastic restoring force of the balloon wall together prevent the contrast agent from passing through the pressure relief port 21. When the internal pressure of balloon 20 reaches or exceeds the preset pressure value, the pressure overcomes the capillary resistance and the external blood environment pressure, and the contrast agent begins to leak out from the pressure relief port 21, forming a visible contrast agent leakage signal under the monitoring of medical imaging equipment. Once the operator observes the contrast agent leakage signal, they can know that the internal pressure of balloon 20 has reached the preset safety limit. At this time, the injection is stopped and the hole size is measured according to the current image. This can effectively avoid the risk of tissue tearing caused by over-inflation of balloon 20. At the same time, the contrast agent leakage itself also provides an objective basis for judging whether balloon 20 is fully attached to the edge of the hole, overcoming the problem of inconsistent measurement results caused by subjective differences in the interpretation of ultrasound images by different operators, and improving the objectivity and repeatability of the measurement.

[0055] In some embodiments, please refer to Figure 2 There are multiple pressure relief holes 21, at least two of which have different initial diameters. Each pressure relief hole 21 with a different initial diameter corresponds to a different preset pressure value. By setting multiple pressure relief holes 21 with different initial diameters on the balloon 20, and each pressure relief hole 21 with a different initial diameter corresponding to a different preset pressure value, a graded pressure warning mechanism can be formed. The surgeon can determine the current intra-balloon pressure level by observing which pressure relief hole 21 begins to release contrast agent, achieving more precise safety control.

[0056] For example, the balloon 20 is provided with three pressure relief holes 21. The initial diameter of the first pressure relief hole is about 0.10 mm, and the corresponding preset pressure value is about 10 mmHg; the initial diameter of the second pressure relief hole is about 0.06 mm, and the corresponding preset pressure value is about 15 mmHg; the initial diameter of the third pressure relief hole is about 0.04 mm, and the corresponding preset pressure value is about 20 mmHg. During the continuous injection of liquid contrast agent into the balloon 20, the intra-balloon pressure gradually increases. The first pressure relief orifice with the largest initial orifice diameter reaches its corresponding lower preset pressure value first and begins to release contrast agent. When the operator observes contrast agent leakage at one pressure relief orifice under medical imaging equipment, it indicates that the intra-balloon pressure has reached the first-level safety threshold. If injection continues, the intra-balloon pressure continues to rise, and the second pressure relief orifice with the second largest initial orifice diameter subsequently begins to release contrast agent, indicating that the intra-balloon pressure has reached the second-level safety threshold. This process continues, with pressure relief orifices 21 of different initial orifice diameters releasing contrast agent sequentially from largest to smallest, forming a stepped pressure warning system. The number of pressure relief orifices 21 is not limited to three; it can also be two, four, or more, and can be flexibly set according to the pressure warning levels required clinically.

[0057] In one embodiment, the balloon 20 is made of an elastic polymer material, which can be thermoplastic polyurethane, nylon elastomer, polyether block amide, etc. The initial pore size of the pressure relief hole 21, the wall thickness of the balloon, and the elastic modulus of the balloon material satisfy the following relationship:

[0058] When the wall thickness and elastic modulus of the bladder are the same, the preset pressure value corresponding to the pressure relief hole 21 with the smaller initial orifice diameter is higher than the preset pressure value corresponding to the pressure relief hole 21 with the larger initial orifice diameter.

[0059] When the initial aperture of the pressure relief hole 21 and the wall thickness of the bladder are the same, the preset pressure value corresponding to the pressure relief hole 21 is higher when the elastic modulus of the bladder material is higher than the preset pressure value when the elastic modulus is lower.

[0060] When the initial aperture of the pressure relief hole 21 and the elastic modulus of the bladder material are the same, the preset pressure value corresponding to the pressure relief hole 21 is higher when the wall thickness is thicker than when the wall thickness is thinner.

[0061] The physical basis of the above three sets of relationships lies in the fact that the critical condition for the release of contrast agent through the pressure relief orifice 21 depends on whether the intracapsular pressure is sufficient to overcome the capillary resistance at the pressure relief orifice 21 and the pore size after expansion. The capillary resistance is inversely proportional to the pore size, while the pore expansion is related to the elastic modulus and wall thickness of the material. By selecting the three structural parameters—the elastic modulus of the capsule material, the capsule wall thickness, and the initial pore size of the pressure relief orifice 21—the intracapsular pressure value at which the release of contrast agent through each pressure relief orifice 21 begins can be precisely controlled, ensuring that it falls within the preset safe physiological pressure range.

[0062] In one embodiment, the elastic modulus of the balloon material is between 30 MPa and 150 MPa. If the elastic modulus is too low, such as with silicone materials below 30 MPa, the pressure relief orifice 21 easily expands during contrast agent injection, making it difficult for the contrast agent to form a clearly detectable concentrated flow at the orifice, resulting in poor detectability. If the elastic modulus is too high, such as with nylon or polyester materials above 150 MPa, the balloon's compliance is insufficient, and the pressure in the balloon 20 increases rapidly with the contrast agent injection volume exceeding the balloon 20's rated volume, making it unsuitable for fitting measurements of flexible tissues such as atrial septal defects. Materials with an elastic modulus in the range of 30 MPa to 150 MPa, especially thermoplastic polyurethane, possess both appropriate compliance and sufficient elastic recovery. This allows the balloon 20 to expand gently with increasing pressure during contrast agent injection, conforming to the natural shape of the orifice edge, while also allowing the pressure relief orifice 21 to undergo controllable elastic expansion under pressure, reliably releasing the contrast agent at a preset pressure value.

[0063] In one embodiment, the wall thickness of the cyst is between 0.01 mm and 0.10 mm. When the wall thickness is less than 0.01 mm, the cyst is not strong enough and there is a risk of rupture in clinical use; when the wall thickness is greater than 0.10 mm, the cyst is too rigid and its volume is too large when collapsed, which is not conducive to delivery through the vascular cavity.

[0064] In one embodiment, the initial aperture of the pressure relief orifice 21 is between 0.02 mm and 0.20 mm. An initial aperture smaller than 0.02 mm significantly increases processing difficulty and poses a risk of blockage by particles in the contrast agent or blood components. An initial aperture larger than 0.20 mm corresponds to a preset pressure value that is too low, potentially causing contrast agent leakage before the balloon 20 fully adheres to the orifice edge, affecting measurement accuracy. The aforementioned wall thickness range and initial aperture range can be freely combined according to actual needs. For example, a wall thickness of 0.03 mm can be paired with an initial aperture of 0.08 mm, a wall thickness of 0.05 mm with an initial aperture of 0.10 mm, a wall thickness of 0.08 mm with an initial aperture of 0.15 mm, etc. Different combinations correspond to different preset pressure values ​​to meet the measurement needs of different patient groups or different orifice types.

[0065] In one embodiment, the preset pressure value ranges from 10 mmHg to 40 mmHg, with lower preset pressure values ​​corresponding to pressure relief orifices 21 with larger initial diameters. The preset pressure value is set within this range based on the fact that the average normal right atrial blood pressure is approximately 2 mmHg to 6 mmHg, and the average left atrial blood pressure is approximately 4 mmHg to 8 mmHg. The preset pressure value needs to be higher than the intracardiac blood environment pressure to overcome external resistance, while simultaneously being lower than the risk threshold for tearing of the atrial septum. The pressure range of 10 mmHg to 40 mmHg ensures sufficient contact between the balloon 20 and the tissue for accurate measurement while minimizing the risk of tissue tearing. A specific preset pressure value can be set for a single pressure relief port 21, such as setting the preset pressure value to 15 mmHg. When the pressure inside the bladder reaches 15 mmHg, the pressure relief port 21 releases contrast agent. Alternatively, multiple preset pressure values ​​can be set for multiple pressure relief ports 21 with different initial diameters, such as setting the preset pressure values ​​of the three pressure relief ports 21 to 10 mmHg, 20 mmHg, and 30 mmHg, respectively.

[0066] Regarding the distribution of pressure relief holes 21, please refer to... Figure 2 In one embodiment, multiple pressure relief holes 21 are distributed circumferentially along the balloon 20. For example, three or four pressure relief holes 21 are evenly arranged on the circumference at the same axial position near the proximal end of the balloon 20, with equal circumferential angles between each pressure relief hole 21. This prevents the pressure relief hole 21 in one direction from being blocked by tissue due to patient position or hole shape, thus preventing the contrast agent from being released normally. In another embodiment, multiple pressure relief holes 21 are distributed axially along the balloon 20. For example, several pressure relief holes 21 are spaced apart along the generatrix of the tapered transition section near the proximal end of the balloon 20, with an axial distance of not less than 1.5 mm between each pressure relief hole 21. This allows for clear differentiation of the timing of contrast agent release from pressure relief holes 21 at different axial positions under medical imaging equipment. In yet another embodiment, multiple pressure relief holes 21 are simultaneously distributed circumferentially and axially along the balloon 20, forming an array-like layout in both the circumferential and axial directions.

[0067] Regardless of the distribution method, there is a physical gap between adjacent pressure relief holes 21. The size of this physical gap is sufficient to allow the image signals of different pressure relief holes 21 at the start of contrast agent release to be clearly distinguished under medical imaging equipment. The specific value of the physical gap depends on the resolution of the medical imaging equipment. For conventional digital subtraction angiography equipment, a gap distance of not less than 1.5 mm between adjacent pressure relief holes 21 is sufficient to meet the distinction requirements.

[0068] In one or more embodiments, please refer to Figure 2 and Figure 3The plurality of pressure relief holes 21 may include a first pressure relief hole 211 and a second pressure relief hole 212. The first pressure relief hole 211 and the second pressure relief hole 212 are distributed at intervals along the axial direction of the balloon 20, and the interval distance is not less than 1.5 mm. The initial diameter of the first pressure relief hole 211 is 0.08 mm to 0.12 mm, and the corresponding preset pressure value is 8 mmHg to 12 mmHg. The initial diameter of the second pressure relief hole 212 is 0.03 mm to 0.05 mm, and the corresponding preset pressure value is 18 mmHg to 22 mmHg. For example, the first pressure relief port 211 is located proximal to the second pressure relief port 212, and the first pressure relief port 211 and the second pressure relief port 212 are spaced 2 mm apart along the axial direction of the balloon 20 or along the surface of the balloon 20. The initial diameter of the first pressure relief port 211 is 0.1 mm, corresponding to a preset pressure value of 10 mmHg; the initial diameter of the second pressure relief port 212 is 0.04 mm, corresponding to a preset pressure value of 20 mmHg. During the continuous injection of liquid contrast agent into the balloon 20, the pressure inside the balloon gradually increases. The first pressure relief port 211, with its larger initial diameter, reaches its corresponding lower preset pressure value first and begins to release contrast agent. When the operator observes contrast agent leakage at the first pressure relief port 211 under medical imaging equipment, it indicates that the pressure inside the balloon has reached the first safety threshold. If injection continues, the pressure inside the balloon continues to increase. When the second pressure relief port 212, with its smaller initial diameter, also begins to release contrast agent, it indicates that the pressure inside the balloon has reached the second safety threshold. The first pressure relief port 211 and the second pressure relief port 212 are spaced apart along the axial direction, so that the starting time of the contrast agent release from the two ports can be clearly distinguished under medical imaging equipment. The operator can accurately determine the safety level of the intracapsular pressure based on which pressure relief port is releasing the contrast agent, and thus decide whether to continue or stop the injection.

[0069] Regarding the position of the pressure relief hole 21 in the axial direction of the balloon 20, in one embodiment, please refer to... Figure 1 and Figure 2The balloon 20 includes a contact section 23 and a first conical transition section 22. The contact section 23 is a roughly cylindrical or waist-shaped area where the balloon 20 contacts the tissue structure at the defect site after inflation. The first conical transition section 22 is connected to the proximal side of the contact section 23, and at least one pressure relief hole 21 is distributed in the first conical transition section 22. Since the first conical transition section 22 is located in the atrium proximal to the hole after the balloon 20 is inflated, the released contrast agent is concentrated in this area, making it easier for medical imaging equipment to capture. In another embodiment, the pressure relief hole 21 is distributed in the junction area between the first conical transition section 22 and the contact section 23. This junction area is close to the actual contact surface between the balloon 20 and the tissue, and the pressure relief hole 21 is closer to the core measurement area. The occurrence of contrast agent leakage and the full contact of the balloon 20 with the edge of the hole are more synchronized in time and space, allowing the operator to judge the timing of stopping the injection more accurately. Another advantage of the pressure relief holes 21 being distributed in the conical transition section is that the curvature change of the conical transition section makes it less likely for the pressure relief holes 21 to be completely adhered and blocked by the tissue at the edge of the hole, which is conducive to the smooth leakage of the contrast agent.

[0070] In a further embodiment, please refer to Figure 1 and Figure 2 The distal end of balloon 20 may also include a second conical transition section 24. The balloon injection channel 11 connects to the internal cavity of balloon 20 through a balloon injection port 111 located on the wall of catheter 10. The balloon injection port 111 includes at least a first injection port 1111 and a second injection port 1112. The first injection port 1111 corresponds to the first conical transition section 22 near the proximal end of balloon 20, and the second injection port 1112 corresponds to the second conical transition section 24 near the distal end of balloon 20. This dual-end injection port layout allows balloon 20 to be completely emptied of internal air before use via a fluid-filled emptying method. For example, by holding balloon 20 vertically, residual air inside balloon 20 is concentrated at the proximal or distal end and fully expelled by liquid contrast agent through the corresponding injection port, ensuring that balloon 20 can be smoothly delivered through the vascular cavity in its collapsed state, while avoiding interference from residual air on measurement accuracy. In addition, the dual-ended injection port allows liquid contrast agent to be injected into or discharged from both ends of the balloon 20 into the internal cavity simultaneously, enabling rapid and uniform inflation and deflation of the balloon 20 and improving surgical efficiency.

[0071] Regarding the shape of the pressure relief hole 21, in one embodiment, the pressure relief hole 21 is a through hole. The shape of the through hole includes at least one of circular and polygonal shapes. Circular through holes are easy to process and have uniform stress distribution; polygonal through holes, such as triangular through holes, quadrilateral through holes, hexagonal through holes, etc., have a longer perimeter under the same cross-sectional area, which is beneficial for the contrast agent to form a more easily detectable leakage pattern at the orifice.

[0072] In another embodiment, the pressure relief orifice 21 is formed by a slit. The shape of the slit includes at least one of a straight slit, a cross slit, and a star-shaped slit; other shapes are also possible. The slit is closed or nearly closed when the pressure inside the balloon 20 is low. When the pressure rises to a preset pressure value, the slit opens under the circumferential tensile stress of the balloon wall, forming a leakage channel. This characteristic gives the slit-type pressure relief orifice 21 a steeper opening characteristic; there is almost no leakage when the pressure does not reach the threshold, and it opens rapidly when the pressure reaches the threshold, resulting in a more sudden and obvious leakage of contrast agent, and better detectability under medical imaging equipment. The pressure relief orifice 21 can be processed by mechanical punching, laser drilling, mold forming, etc., depending on the characteristics of the balloon material and the design shape of the pressure relief orifice 21.

[0073] In one embodiment, the total flow area of ​​the pressure relief holes 21 is not greater than the cross-sectional area of ​​the balloon injection channel 11. The total flow area of ​​the pressure relief holes 21 refers to the sum of the orifice areas of all pressure relief holes 21 in their unexpanded state. When the total flow area of ​​the pressure relief holes 21 is greater than the cross-sectional area of ​​the balloon injection channel 11, the contrast agent may leak in large quantities even at low pressure, making it difficult for the balloon 20 to establish effective inflation pressure. This results in the balloon 20 not being able to fully expand and fit the edge of the orifice, affecting measurement accuracy. When the total flow area of ​​the pressure relief holes 21 is not greater than the cross-sectional area of ​​the balloon injection channel 11, the leakage rate of the contrast agent is reasonably limited. The balloon 20 can establish and maintain sufficient working pressure during the measurement process, and only begins to leak moderately when the pressure reaches a preset pressure value, thus balancing pressure relief safety and measurement effectiveness.

[0074] Regarding the overall structure of the catheter 10, in one embodiment, the catheter 10 also includes a guidewire channel 12, which is independent of the balloon injection channel 11. The guidewire channel 12 is used to pass through the guidewire, enabling the balloon catheter to be accurately delivered to the measurement site along the guidewire. The guidewire channel 12 extends axially along the catheter 10 and is arranged parallel to the balloon injection channel 11. The two are separated by the catheter wall within the cross-section of the catheter 10 to avoid interference between guidewire passage and contrast agent injection.

[0075] In some embodiments, the balloon catheter further includes an interface 30 connected to the proximal end of the catheter 10. The interface 30 includes a balloon injection interface 31 and a guidewire insertion interface 32. The balloon injection interface 31 communicates with the balloon injection channel 11 and is used to connect a contrast agent inlet device for liquid contrast agent inlet. The guidewire insertion interface 32 communicates with the guidewire insertion channel 12 and is used for guidewire insertion. The guidewire insertion interface 32 is axially aligned with the guidewire insertion channel 12 to reduce bending resistance during guidewire insertion. The interface 30 integrates the contrast agent inlet and guidewire insertion functions, simplifying the intraoperative procedure and improving surgical efficiency.

[0076] One embodiment of this application also provides a method for measuring the size of an incision, using the balloon catheter described in any of the above embodiments. The incision may be an atrial septal defect, a patent foramen ovale, a ventricular septal defect, or other in vivo orifices requiring size measurement via balloon 20. The measurement method includes the following operations:

[0077] The balloon catheter is delivered to the hole to be measured. During delivery, the balloon catheter can be guided to the target position by the guide wire inserted in the wire channel 12.

[0078] Liquid contrast agent is continuously injected into the balloon 20 through the balloon injection channel 11, so that the balloon 20 gradually inflates and fits the edge of the hole to be measured. During the injection process, the balloon 20 is compressed by the edge of the hole to form a waist shape.

[0079] While injecting the contrast agent, the waist shape of the balloon 20 is monitored using medical imaging equipment in preparation for measurement, and it is observed whether the contrast agent leaks from the pressure relief hole 21. When at least one pressure relief hole 21 is observed to release contrast agent, it indicates that the internal pressure of the balloon 20 has reached the preset pressure value. At this time, the injection of liquid contrast agent is stopped, and the size of the hole to be measured is measured based on the image at this time.

[0080] Compared with related technologies that rely on ultrasound to determine when to stop injection, this method uses the appearance of contrast agent leakage as an objective imaging indicator for stopping injection. Operators can simultaneously perform pressure monitoring and size measurement on the same digital subtraction angiography device interface, avoiding measurement deviations caused by inconsistent interpretation of ultrasound blood flow cutoff images by different operators, reducing differences in judgment between operators, and improving the objectivity and repeatability of measurement results.

[0081] In some embodiments, when the balloon catheter used is a balloon catheter with multiple pressure relief holes 21 of different initial diameters, during the operation of observing whether contrast agent leakage occurs, the maximum value of the preset pressure corresponding to each pressure relief hole 21 that causes contrast agent leakage is used to determine whether to stop the injection. For example, the balloon 20 is provided with three pressure relief holes 21, with preset pressure values ​​of 10 mmHg, 15 mmHg and 20 mmHg, respectively. The three pressure relief holes 21 are distributed along the axial direction of the balloon 20 at intervals on the proximal side of the balloon 20, with a spacing of not less than 1.5 mm. Under medical imaging, the operator first observes the contrast agent leaking from the pressure relief orifice with a preset pressure value of 10 mmHg. At this point, the intra-balloon pressure is at least 10 mmHg, but has not yet reached the subsequent higher-level threshold. The operator can choose to continue injection to observe whether the balloon 20 further adheres to the edge of the orifice. When injection continues until the third pressure relief orifice with a preset pressure value of 20 mmHg also leaks contrast agent, the maximum preset pressure value corresponding to the pressure relief orifice 21 that leaked the contrast agent has reached 20 mmHg, indicating that the intra-balloon pressure has reached the highest safe threshold allowed for this measurement. At this point, injection must be stopped. Under digital subtraction angiography imaging, the operator can clearly determine whether the contrast agent has crossed the orifice and entered the contralateral atrium (e.g., the left atrium) by observing the distribution range and flow direction of the leaked contrast agent in the proximal atrium (e.g., the right atrium), thereby assisting in assessing the degree of occlusion of the orifice by the balloon 20. This graded judgment method allows the operator to flexibly choose the timing of stopping according to actual clinical needs, ensuring that the balloon 20 adheres fully and the measurement results are accurate. The graded pressure early warning mechanism provides operators with multiple decision points ranging from conservative to proactive, balancing safety and measurement accuracy.

[0082] It should be noted that the technical features described in the above embodiments are not isolated from each other. Provided they do not contradict each other, the technical features in different embodiments can be arbitrarily combined according to actual needs, and the new technical solutions formed by such combinations also fall within the protection scope of this application. For example, an embodiment where the pressure relief hole 21 is a cross-shaped slit can be combined with an embodiment where the capsule material is thermoplastic polyurethane with an elastic modulus of 30MPa to 150MPa; an embodiment where multiple pressure relief holes 21 are distributed circumferentially along the balloon 20 and adjacent holes are physically spaced can be combined with an embodiment where the preset pressure value range is 10mmHg to 40mmHg; an embodiment where the pressure relief holes 21 are distributed in the area at the junction of the first conical transition section 22 and the contact section 23 can be combined with an embodiment where the total flow area of ​​the pressure relief holes 21 is not greater than the cross-sectional area of ​​the balloon injection channel 11. Any technical solution formed by a reasonable combination based on the technical features disclosed in this application should be considered as being covered by this application.

[0083] It is important to emphasize that this application does not simply involve creating a hole in the balloon 20. Instead, based on a coupled model of materials mechanics, capillary action, and fluid mechanics, the pressure relief hole 21 is designed to reliably release contrast agent at preset safe physiological pressure thresholds (e.g., 10 mmHg, 20 mmHg, 30 mmHg) through the coordinated design of the balloon's elastic modulus, thickness, and pore diameter. The working principle and calculation method are as follows:

[0084] The average blood pressure in the right atrium of a normal human body is 2 mmHg-6 mmHg, and the average blood pressure in the left atrium is 4 mmHg-8 mmHg. This blood pressure value represents the pressure of the external blood environment of the balloon 20 that the contrast agent needs to overcome to be ejected from the pressure relief port 21 of the balloon 20. Contrast agent leakage depends on intracapsular pressure. Whether it is possible to overcome the critical conditions jointly determined by the capillary resistance of the pressure relief orifice 21, the elastic deformation of the capsule material, the hydrodynamic properties of contrast agent diffusion, and the clinical tissue environment:

[0085] When the pressure inside the cyst At lower levels, the capillary resistance threshold of the pressure relief orifice 21 can prevent the contrast agent from flowing out;

[0086] When the pressure inside the cyst Increase to critical pressure At that time, the diameter of the pressure relief hole 21 was changed from the initial diameter. elastic expansion to ;at this time Higher than capillary resistance Under pressure difference Under the action of the pressure relief hole 21, the gas inside is completely pushed out, the channel is filled with contrast agent and continues to leak outward; the contrast agent gathers into a cluster near the orifice and then slowly diffuses to the surroundings, the fluid inside the orifice is in a peristaltic flow state, and the outlet Reynolds number is... .

[0087] The elastic deformation of the pressure relief hole 21 on the balloon 20 can be calculated using an elastic mechanics model, under balloon pressure. At that time, the diameter of the pressure relief hole 21 in the bladder body The computational model can be simplified to a sphere model, with the area near the hole appearing to be an infinitely large plane.

[0088] The basic assumptions and parameter definitions of the model are as follows:

[0089] (1) Initial diameter of the sphere initial thickness initial aperture And satisfy much smaller ;

[0090] (2) The balloon body of balloon 20 is made of TPU material, and the TPU film is a linear elastic material with an elastic modulus of The value ranges from 30MPa to 100MPa, and the Poisson's ratio is... (Incompressible);

[0091] (3) Pressure on the inner side of balloon 20 External blood environment pressure The cyst is subjected to a uniform pressure difference Due to the symmetrical deformation of the sphere, the area near the hole can be approximated as a plane.

[0092] Let the radius of the sphere after expansion be... ( ; (where is the radial expansion ratio), and based on the assumption of constant volume, the wall thickness of the expanded cyst is:

[0093] (Equation 1).

[0094] The circumferential strain of the balloon at 20° is:

[0095] (Equation 2)

[0096] According to Hooke's Law, the circumferential stress of the thin film is:

[0097] (Equation 3)

[0098] According to the theory of spherical shell thin films, the equilibrium relationship between pressure difference, stress, and wall thickness is as follows:

[0099] (Equation 4)

[0100] Substituting equations 1 and 3 into equation 4, we derive the relationship between pressure difference and expansion ratio:

[0101] (Equation 5)

[0102] Biaxial equal tensile stress Under the action of the force, the radial displacement of the circular hole in the plane is given by the solution of the plane problem of elasticity:

[0103] (Equation 6)

[0104] In the formula, The initial radius of the pressure relief hole 21 is given.

[0105] The radius of the expanded circular hole is:

[0106] (Equation 7)

[0107] In equation 3 Substituting into Equation 7, we obtain the relationship between the expanded diameter of the pressure relief hole 21 and its initial diameter:

[0108] (Equation 8)

[0109] As shown in Equation 8, the diameter of the pressure relief orifice 21 increases with the expansion ratio. Linear growth. Under small deformation conditions ( ), using approximation relationships From this, an approximate relationship between orifice diameter and pressure difference can be derived:

[0110] (Equation 9)

[0111] According to the Young-Laplace equation, the formula for calculating the capillary resistance at pressure relief orifice 21 is as follows:

[0112] (Equation 10)

[0113] The parameters in the formula are defined as follows:

[0114] Surface tension at the interface between the contrast agent solution and air. Iohexol is a nonionic, strongly hydrophilic triiodamide contrast agent. When dissolved in water, the system is mainly dispersed by highly polar polyhydroxy molecules and does not possess surfactant properties. Its liquid-gas interfacial surface tension is close to that of water. When performing fluid dynamics, capillary action, and wettability calculations, values ​​are taken based on the aqueous solution. ;

[0115] The contact angle between the contrast agent solution and air;

[0116] : The actual diameter of the pressure relief hole 21 after expansion.

[0117] Substituting Equation 8 into Equation 10, and combining it with the thin-shell equilibrium relationship in Equation 5, the coupling equation between the pressure difference inside and outside the bladder and the capillary resistance can be derived:

[0118] (Equation 11)

[0119] From the above coupling formula, it can be seen that the initial diameter of the pressure relief hole 21 is... For the critical pressure of discharge The effect is most significant, and it can directly determine the pressure threshold when contrast agent leakage occurs in the capsule.

[0120] The following are calculation examples under some parameters: setting external environmental pressure Surface tension Contact angle Initial radius of balloon 20 The critical pressure for discharge and capillary resistance corresponding to different parameters are shown in the table below:

[0121] Table 1. Comparison of critical pressure and capillary resistance for discharge under different parameters.

[0122]

[0123] The calculation results from the formula and examples show that, for The value has the most significant impact and can directly determine the pressure when contrast agent leakage occurs in the capsule.

[0124] When the contrast agent pressure inside balloon 20 At a pressure of 15 mmHg, the expansion pressure of the balloon 20 on the defect tissue in contact with the balloon body is approximately 12 mmHg, and the balloon body and the tissue to be measured are in pressure contact. Under this condition, the cylindrical surface of the balloon 20 fits perfectly with the defect tissue, resulting in accurate dimensional measurements. Based on the atrial septal defect dimensions measured under this condition, the surgeon can accurately select the occluder model, avoiding measurement errors caused by non-contact measurement methods such as ultrasound, which are affected by deviations in measurement direction and angle, as well as the soft edges and irregular shapes of the defect tissue.

[0125] When the operator observes contrast agent leaking from the capsule to the outside in the pre-set micropore area of ​​the capsule, the injection of contrast agent can be stopped to avoid excessive pressure in the capsule due to continuous injection, which could cause damage such as tearing of the contact tissue, while ensuring measurement accuracy.

[0126] Based on the above aperture-pressure correspondence, the pressure relief holes 21 with different apertures on the balloon 20 can be equivalent to a visual pressure scale.

[0127] Multiple sets of different initial diameters can be arranged at different positions of the balloon 20. , , ...) pressure relief orifice 21; the larger the orifice diameter, the higher the corresponding critical pressure for venting. The lower the pressure, the better. Multiple sets of pressure relief holes 21 are arranged in descending order of diameter, which will sequentially cause contrast agent leakage under progressively increasing pressure thresholds, forming a stepped pressure alarm system under DSA imaging.

[0128] When leakage is detected around the pressure relief hole 21 with the largest diameter in the first row, it indicates that the pressure inside the bladder has reached the first level of safety threshold (e.g., 10 mmHg).

[0129] If contrast agent injection continues, leakage and contrast imaging around the smaller-diameter pressure relief holes 21 in the second row indicate that the intracapsular pressure has risen to a higher safety threshold (e.g., 15 mmHg).

[0130] The balloon catheter design of this application provides operators with intuitive, graded pressure feedback, ensuring operational safety and measurement accuracy.

[0131] Finally, it should be noted that the above embodiments, which describe the balloon catheter in conjunction with atrial septal defect detection, are only intended to clearly illustrate the inventive concept of the balloon catheter in this application and do not constitute a limitation on the balloon catheter. In other words, the application scenarios of the balloon catheter in this application are not limited to atrial septal defect detection; it can also be applied to the detection or interventional closure treatment of other in vivo defects such as patent ovale. Specific scenarios will not be elaborated here.

[0132] The above examples illustrate this application only to aid understanding and are not intended to limit its scope. Those skilled in the art to which this application pertains can make various simple deductions, modifications, or substitutions based on the ideas presented.

Claims

1. A balloon catheter, characterized by, include: catheter; And a balloon, disposed in the catheter, the balloon being collapsible and inflatable; The catheter defines a balloon injection channel that communicates with the internal cavity of the balloon for injecting a liquid contrast agent into the balloon. The balloon has at least one pressure relief hole on its wall. The pressure relief hole is configured such that when the inflation pressure inside the balloon reaches a preset pressure value, the pressure relief hole can release contrast agent that can be detected by medical imaging equipment.

2. The balloon catheter of claim 1, wherein, The number of pressure relief holes is multiple, and at least two of the multiple pressure relief holes have different initial hole diameters. The pressure relief holes with different initial hole diameters correspond to different preset pressure values.

3. The balloon catheter as described in claim 2, characterized in that, The balloon body is made of an elastic polymer material, and the initial pore diameter of the pressure relief orifice, the wall thickness of the balloon body, and the elastic modulus of the balloon body material satisfy the following relationship: When the wall thickness and elastic modulus of the bladder are the same, the preset pressure value corresponding to the pressure relief hole with the smaller initial orifice diameter is higher than the preset pressure value corresponding to the pressure relief hole with the larger initial orifice diameter; When the initial diameter of the pressure relief hole and the wall thickness of the bladder are the same, the preset pressure value corresponding to the pressure relief hole is higher when the elastic modulus of the bladder material is higher than the preset pressure value when the elastic modulus is lower. When the initial diameter of the pressure relief hole and the elastic modulus of the bladder material are the same, the preset pressure value corresponding to the pressure relief hole when the wall thickness is thicker is higher than the preset pressure value when the wall thickness is thinner.

4. The balloon catheter as described in claim 3, characterized in that, The elastic modulus of the capsule material is 30 MPa to 150 MPa; And / or, the wall thickness of the capsule is 0.01 mm to 0.10 mm; And / or, the initial diameter of the pressure relief hole is 0.02 mm to 0.20 mm; And / or, the capsule material is thermoplastic polyurethane.

5. The balloon catheter as described in claim 2, characterized in that, The preset pressure value ranges from 10 mmHg to 40 mmHg, and the preset pressure value corresponding to the pressure relief hole with a larger initial orifice diameter is lower; And / or, the plurality of pressure relief holes are distributed along the circumference and / or axial direction of the balloon, and there is a physical spacing between adjacent pressure relief holes so that they can be distinguished when different pressure relief holes begin to release the contrast agent.

6. The balloon catheter as described in claim 5, characterized in that, The plurality of pressure relief holes include a first pressure relief hole and a second pressure relief hole, wherein the first pressure relief hole and the second pressure relief hole are distributed at intervals along the axial direction of the balloon, and the interval distance is not less than 1.5 mm; The initial diameter of the first pressure relief hole is 0.08 mm to 0.12 mm, and the corresponding preset pressure value is 8 mmHg to 12 mmHg; the initial diameter of the second pressure relief hole is 0.03 mm to 0.05 mm, and the corresponding preset pressure value is 18 mmHg to 22 mmHg.

7. The balloon catheter according to any one of claims 1 to 6, characterized in that, The total flow area of ​​the pressure relief orifice is not greater than the cross-sectional area of ​​the balloon injection channel.

8. The balloon catheter according to any one of claims 1 to 6, characterized in that, The balloon includes a contact section and a first conical transition section. The contact section is used to contact the tissue structure at the defect site. The first conical transition section is connected to the proximal side of the contact section. The at least one pressure relief hole is distributed in the first conical transition section or in the boundary area between the first conical transition section and the contact section.

9. The balloon catheter according to any one of claims 1 to 6, characterized in that, The pressure relief hole is a through hole or formed by a slit. The shape of the through hole includes at least one of circular and polygonal shapes, and the shape of the slit includes at least one of straight, cross, and star-shaped shapes.

10. The balloon catheter according to any one of claims 1 to 6, characterized in that, The catheter also has a wire-passing channel inside, which is independent of the balloon injection channel. The balloon catheter further includes an interface component connected to the catheter, the interface component comprising: A balloon injection port, connected to the balloon injection channel, is used to connect to a contrast agent input device; And a threading interface, which is connected to the threading channel, for inserting the guide wire.

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