Judgment system based on local impedance

Abstract

The invention discloses a judgment system based on local impedance. An excitation source of a to-be-measured ablation electrode is obtained, and a voltage difference value between the to-be-measured ablation electrode and an ablation electrode adjacent to the to-be-measured ablation electrode is obtained; according to the excitation source, the voltage difference and a preset formula, the local impedance of the ablation electrode to be measured is obtained; and receiving and judging the local impedance of the ablation electrode to be measured so as to determine the position of the pulse ablation catheter in the heart cavity and deploy the energy output opportunity. The system judges the local impedance to determine the position of the pulse ablation catheter in the heart cavity and deploy the energy output opportunity, can accurately and effectively judge whether the ablation electrode transmitting the local impedance is stably or excessively attached to the tissue or not, and takes corresponding measures according to the judgment result. Therefore, the problem of unstable ablation injury is effectively solved.

Description

[0001] This application is a divisional application of application number "202310347853.1", application date April 3, 2023, and invention name "A judgment method and system based on local impedance". Technical Field

[0002] The present application relates to the field of ablation technology, and in particular to a judgment system based on local impedance. Background Art

[0003] Atrial fibrillation is a rapid arrhythmia, common in the elderly population, with an incidence rate of up to 10% in people over 75 years old. During atrial fibrillation, the atrial excitation frequency reaches 300 to 600 beats per minute, and the ventricular rate is often fast and irregular, sometimes reaching 100 to 160 beats per minute, which is not only much faster than a normal heartbeat, but also absolutely irregular, and the atria lose their effective contraction function. The incidence of atrial fibrillation is also closely related to diseases such as coronary heart disease, hypertension and heart failure.

[0004] Treatments for atrial fibrillation include drug therapy and non-drug therapy. Drug therapy can be divided into sodium channel blockers, beta-receptor antagonists, drugs that prolong action potential duration, and calcium channel blockers based on their mechanism of action. Generally speaking, drug therapy is the preferred treatment option, but it requires long-term use and is accompanied by side effects. Since some patients with arrhythmias cannot control their condition with drugs, in this case, non-drug therapy will help patients control their heart rhythm and improve symptoms, such as catheter ablation, pacemaker implantation, surgical intervention, etc.

[0005] Pulmonary vein electrical isolation is a recognized strategy for catheter ablation treatment of atrial fibrillation and is also one of the surgical procedures for catheter ablation. The operator will insert the ablation catheter into the left atrium and perform circular ablation of the myocardium at the pulmonary vein orifice / vestibule. Point-to-point ablation with a straight catheter with a single ablation electrode is a traditional surgical method. The tip electrode of the ablation catheter can output ablation energy, and the other electrodes on the tube body can only be used to record intracardiac electrical signals. A pressure sensor is placed inside the straight catheter with a single ablation electrode, and the pressure generated when it is in contact is used to detect the degree of coupling between the tissue and the ablation electrode. However, multi-electrode ablation catheters do not have space for placing pressure sensors, so the degree of coupling between the ablation electrode and the tissue cannot be detected by pressure, resulting in the problem of unstable ablation damage.

[0006] In view of this, it is a technical problem that needs to be solved urgently by those skilled in the art to provide a local impedance-based judgment method and system that can accurately evaluate whether the discharge electrode and tissue are stably attached or excessively attached. Summary of the invention

[0007] The purpose of the present invention is to provide a judgment system based on local impedance, which can accurately judge whether the ablation electrode and tissue are in stable contact or excessive contact, and take corresponding measures according to the judgment result, thereby effectively solving the problem of unstable ablation damage;

[0008] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0009] A judgment system based on local impedance, the judgment system performs the following steps:

[0010] Acquire an excitation source for a loop formed by an ablation electrode to be measured and an unrelated electrode; acquire a voltage difference between the ablation electrode to be measured and an ablation electrode adjacent to the ablation electrode to be measured through a pulse ablation catheter; acquire the local impedance of the ablation electrode to be measured based on the excitation source, the voltage difference and a preset formula; receive and judge the local impedance of the ablation electrode to be measured to determine the position of the pulse ablation catheter in the heart cavity and adjust the timing of energy output.

[0011] The present invention also provides a technical solution, a judgment system based on local impedance, characterized in that it includes: a pulse ablation catheter, a pulse electric field ablation device, a connecting pigtail, and an irrelevant electrode; the pulse ablation catheter is connected to the pulse electric field ablation device through the connecting pigtail; the irrelevant electrode is connected to the pulse electric field ablation device through the connecting pigtail; the pulse ablation catheter is used to obtain local impedance based on an excitation source and a voltage difference; the pulse electric field ablation device is used to receive the local impedance and judge the local impedance; wherein the pulse ablation catheter is used to measure the local impedance and release ablation energy, and the ablation electrode close to the myocardial tissue can be obtained according to the local impedance generated by each ablation electrode on the pulse ablation catheter; the timing of the ablation electrode outputting energy can be adjusted.

[0012] The present invention provides a judgment system based on local impedance, which obtains the excitation source of the ablation electrode to be measured and the voltage difference between the ablation electrode to be measured and an ablation electrode adjacent to the ablation electrode to be measured; then, the local impedance of the ablation electrode to be measured is obtained according to the excitation source, the voltage difference and a preset formula; the local impedance of the ablation electrode to be measured is received and judged to determine the position of the pulse ablation catheter in the heart cavity and the timing of adjusting energy output. This system measures the excitation source and the voltage difference of the ablation electrode to be measured, calculates the local impedance of the ablation electrode to be measured according to the excitation source and the voltage difference, and judges the local impedance to determine the position of the pulse ablation catheter in the heart cavity and the timing of adjusting energy output. It can accurately and effectively judge whether the ablation electrode transmitting the local impedance is stably attached to the tissue or over-attached, and take corresponding measures according to the judgment result, thereby effectively solving the problem of unstable ablation damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 is a flow chart of a determination method based on local impedance in an embodiment of the present invention;

[0015] Figure 2 is a flow chart of step S4 in an embodiment of the present invention;

[0016] Figure 3 Schematic diagram of the structure of the judgment system based on local impedance in an embodiment of the present invention;

[0017] Figure 4 Schematic diagram of the structure of a pulse ablation catheter in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] like Figure 1 As shown, an embodiment of the present invention provides a judgment method based on local impedance, comprising the following steps:

[0020] S1. Obtaining the excitation source of the ablation electrode to be measured;

[0021] S2. obtaining a voltage difference between the ablation electrode to be measured and an ablation electrode adjacent to the ablation electrode to be measured;

[0022] S3. Obtaining the local impedance of the ablation electrode to be measured according to the excitation source, the voltage difference and the preset formula;

[0023] S4. Obtain the target baseline according to preset rules;

[0024] S5. Determine the local impedance of the ablation electrode to be measured according to the target baseline.

[0025] In step S1, a loop is formed by the ablation electrode to be measured and the irrelevant electrode (negative plate), thereby generating an excitation source of a certain amplitude, thereby forming a stable electric field, wherein the frequency of the excitation source can be 1kHz~1MHz, with no limit on the range. In this embodiment, 10kHZ~100kHz is preferably selected.

[0026] In step S2, in this embodiment, a plurality of ablation electrodes are used, and each ablation electrode is located at a different position, so the voltage generated by each ablation electrode is also different. Therefore, it is necessary to calculate the voltage difference of the ablation electrodes to be measured.

[0027] In step S3, the local impedance is calculated according to a preset formula using the excitation source obtained in step S1 and the voltage difference obtained in step S2;

[0028] The default formula is:

[0029] Zm=V_0 / V_1

[0030] Among them, Zm is the local impedance; V_0 is the voltage difference; V_1 is the excitation source.

[0031] In step S4, the difference in blood and myocardial conductivity causes local impedance changes, and the algorithm determines whether the catheter has coupled with the myocardium by the amplitude of its rise; the size of the measuring electrode and the spacing between the adjacent electrodes will have a direct impact on the measured local impedance, so the type of pulse ablation catheter is correlated with the value of local impedance, and the blood conductivity of different patients will be different; in a pulse ablation catheter with multiple electrodes, there is no difference in the local impedance measured by each electrode, but there is an error of ±1Ω between the channels connecting each electrode to the device, so the local impedance measured by the system has a difference of ±1Ω; therefore, in order to make the baseline range more robust, the target baseline is obtained through preset rules.

[0032] In step S5, after the target baseline is obtained in step S4, the calculated local impedance of the ablation electrode to be measured at every moment is compared with the target baseline and judged.

[0033] Preferably, the step S1 comprises the following steps:

[0034] A1. Obtaining a first voltage value of the ablation electrode to be measured;

[0035] A2. Obtain a second voltage value of a preset resistor;

[0036] A3. Obtain the excitation source of the ablation electrode to be measured according to the first voltage value, the second voltage value and the preset resistance value.

[0037] In steps A1 to A3, firstly, the first voltage value V_AN1 of the electrode to be ablated is obtained, and then the second voltage value Vs of the preset resistor is obtained. Since the preset resistor is a fixed resistor Zc, there is no need to obtain the resistance value of the preset resistor, and it can be used directly; then the excitation source V1 is calculated by a preset formula; the preset formula is as follows:

[0038] V1 = (Vs - V_AN1) / Zc.

[0039] Preferably, the step S2 comprises the following steps:

[0040] B1. Obtaining a third voltage of the ablation electrode to be measured;

[0041] B2. acquiring a fourth voltage of an ablation electrode adjacent to the ablation electrode to be measured;

[0042] B3. Obtain the voltage difference of the ablation electrode to be measured based on the third voltage and the fourth voltage.

[0043] In step B1, a third voltage of the ablation electrode to be measured is measured by using a device. Those skilled in the art may also select a suitable device to measure the voltage according to actual conditions. In this embodiment, a pulsed electric field ablation device is used.

[0044] In step B2, the fourth voltage of the next ablation electrode adjacent to the ablation electrode to be measured is also measured by using the device. Those skilled in the art can also select a suitable device to measure the voltage according to the actual situation. In this embodiment, a pulsed electric field ablation device is used;

[0045] In step B3, the voltage difference of the ablation electrode to be measured is obtained by subtracting the third voltage obtained in step B1 from the fourth voltage obtained in step B2; the voltage difference of the last ablation electrode on the annular end tube needs to be measured with respect to the adjacent previous ablation electrode.

[0046] like Figure 2 As shown, preferably, the step S4 comprises the following steps:

[0047] C1. Obtain impedance data of the ablation electrode according to a preset time;

[0048] C2. Obtain quartiles and medians based on impedance data;

[0049] C3. Obtain initial baseline;

[0050] C4. Update the initial baseline based on the quartiles and median to obtain the target baseline.

[0051] In step C1, when all ablation electrodes just enter the heart cavity, the impedance data of all ablation electrodes need to be initialized, and then according to the preset time, the impedance data around the electrodes at this moment, which is real-time feedback during the movement of the ablation electrodes in the heart, is collected, and the minimum value of the impedance data obtained in each frame is arranged in ascending order.

[0052] In step C2, the impedance data obtained in step C1 is calculated according to a preset statistical method to obtain quartiles and medians, which can effectively filter out detected specific values, such as metal implants in the heart, and can maximize the impedance around the catheter during initialization. At the same time, the quartile is set as the minimum value of the baseline; the median plus X is set as the maximum value of the baseline, because the local impedance of the blood in the atrium is slightly smaller than the local impedance when the catheter is suspended at the mouth of the pulmonary vein; the baseline range at this time is greater than or equal to the quartile and less than or equal to the median plus X; the reasonable baseline range of the current catheter in this heart cavity can be effectively obtained, which can make the sticking judgment more accurate.

[0053] In step C3, firstly, the impedance data of the electrode to be ablated is obtained, and the impedance data is obtained once every Y seconds, and the minimum value of the obtained impedance data is used as the initial baseline;

[0054] In step C4, after the initialization setting is completed, the catheter can operate normally. During the operation, the initial baseline obtained in step S3 will be updated according to the baseline range composed of the quartiles and the median obtained in step C2. If the initial baseline at this time is within the baseline range, the initial baseline will be updated and output as the target baseline; if the initial baseline at this time is not within the baseline range, the initial baseline will not be updated.

[0055] Preferably, the step S5 comprises the following steps:

[0056] If the local impedance is greater than the target baseline, the ablation electrode transmitting the local impedance is in contact;

[0057] If the local impedance is less than the target baseline, the ablation electrode transmitting the local impedance is not in contact.

[0058] In actual use, the conductivity of blood is higher than that of the heart. When there is only blood around the ablation electrode, the local impedance of the ablation electrode is low, about 70-90Ω; when the ablation electrode contacts the myocardial tissue in the heart cavity, the local impedance measured by the ablation electrode will increase significantly, about 100Ω or more; therefore, it is necessary to judge the local impedance based on the target baseline. If the local impedance is greater than the target baseline, it means that the ablation electrode transmitting this impedance is close to the myocardial tissue; if the local impedance is less than the target baseline, it means that the ablation electrode transmitting this impedance is not close to the myocardial tissue;

[0059] At the same time, as the heart beats at its own rhythm, after the ablation electrode contacts the myocardium, the measured local impedance increases significantly. In addition, periodic and stable fluctuations in impedance can be observed at some locations in the heart. For example, the heart periodically dilates and contracts under the control of its own rhythm, and the volume of the ventricle during diastole is more than twice that during systole. The violent movement of the ventricular free wall may cause the tip of the catheter to contact the myocardium during a part of the cardiac cycle, so it can be observed that the local impedance fluctuates with the same length as the heartbeat cycle.

[0060] like Figure 3 As shown, the embodiment of the present invention further provides a judgment system based on local impedance, based on the judgment method based on local impedance described in any one of claims 1-5, comprising: a pulse ablation catheter 1, a pulse electric field ablation device 2, a connecting pigtail 3, an irrelevant electrode 4 and a three-dimensional positioning navigation system 5;

[0061] The pulse ablation catheter 1 is connected to the pulse electric field ablation device 2 via a connecting pigtail 3;

[0062] The indifferent electrode 4 is connected to the pulse electric field ablation device 2 via the connecting pigtail 3;

[0063] The pulse electric field ablation device 2 is connected to the three-dimensional positioning navigation system 5 via the connecting pigtail 3;

[0064] A pulse ablation catheter 1, used to obtain local impedance according to an excitation source and a voltage difference;

[0065] A pulsed electric field ablation device 2 for processing local impedance according to a target baseline;

[0066] The three-dimensional positioning and navigation system 5 is used to receive an initialization instruction;

[0067] The three-dimensional positioning and navigation system 5 is also used to receive the judgment result of the pulse ablation device 2 .

[0068] During actual use, the pulse ablation catheter sends the local impedance generated by the pulse ablation catheter to the pulse electric field ablation device through the connecting pigtail; the local impedance of the pulse ablation catheter is received and judged through the connecting pigtail; a complete loop is formed with the pulse ablation catheter through the irrelevant electrode; after the three-dimensional positioning and navigation system receives the initialization instruction, the impedance data of the ablation electrode is initialized; the pulse ablation device uploads the local impedance of the electrode to be measured to the three-dimensional positioning and navigation system, and performs color rendering for the doctor to observe and judge; it can also be used to determine the position of the catheter inside the heart cavity, adjust the timing of energy output, and monitor the patient's intracardiac electrophysiological signals.

[0069] like Figure 4 As shown, preferably, the pulse ablation catheter 1 comprises: an ablation electrode 11, a ring-shaped end tube 12, a tube body 13, a positioning electrode 14, a handle 15 and a connector 16;

[0070] The annular end pipe 12 is connected to the pipe body 13;

[0071] The connector 16 is connected to the tube body 13 through the handle 15;

[0072] The ablation electrode 11 is arranged on the annular end tube 12;

[0073] The positioning electrode 14 is arranged on the tube body 13;

[0074] Ablation electrodes, used to measure local impedance and release ablation energy;

[0075] An annular end tube for carrying an ablation electrode;

[0076] Positioning electrodes are used to provide magnetic position information.

[0077] In actual use, the ablation electrode is set on the ring-shaped end tube, and the positioning electrode is set on the tube body, so that the ablation electrode on the ring-shaped end tube and the positioning electrode on the tube body can both measure local impedance; in this embodiment, all electrodes of the ring-shaped end tube can participate in ablation discharge, and the patient's myocardium, ablation electrode, catheter, cable, and ablation equipment form a power-on circuit; all ablation electrodes and irrelevant electrodes (negative plates) can form a communication circuit for local measurement; in this embodiment, the size of the ablation electrode is 2 mm long and 1.5 mm wide; the spacing between the electrode edges is 4 mm.

[0078] In the embodiments provided in the present application, it should be understood that the disclosed methods and systems can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of modules is only a logical function division. There may be other division methods in actual implementation, such as: multiple modules or components can be combined, or can be integrated into another system, or some features can be ignored, or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or modules, which can be electrical, mechanical or other forms.

[0079] In addition, all functional modules in the embodiments of the present invention may be integrated into one processor, or each module may be a separate device, or two or more modules may be integrated into one device; each functional module in the embodiments of the present invention may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0080] A person of ordinary skill in the art can understand that all or part of the steps of implementing the above method embodiment can be completed by program instructions and related hardware. The aforementioned program instructions can be stored in a computer-readable storage medium. When the program instructions are executed, the steps of the above method embodiment are executed; and the aforementioned storage medium includes: a mobile storage device, a read-only memory (ROM), a magnetic disk or an optical disk, and other media that can store program codes.

[0081] It should be understood that if "system", "device", "unit" and / or "module" are used in this application, it is only a method for distinguishing different components, elements, parts, parts or assemblies at different levels. However, if other words can achieve the same purpose, the word can be replaced by other expressions. As shown in this application and the claims, unless the context clearly indicates an exception, the words "one", "an", "a kind" and / or "the" do not specifically refer to the singular, but may also include the plural. Generally speaking, the terms "including" and "comprising" only indicate the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list, and the method or device may also include other steps or elements. The elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, commodity or device that includes the elements.

[0082] In the following, the terms "first", "second", "third", and "fourth" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first", "second", "third", and "fourth" may explicitly or implicitly include one or more of the features.

[0083] If a flow chart is used in the present application, the flow chart is used to illustrate the operations performed by the system according to the embodiment of the present application. It should be understood that the preceding or following operations are not necessarily performed accurately in order. On the contrary, each step can be processed in reverse order or simultaneously. At the same time, other operations can also be added to these processes, or a certain step or several steps of operations can be removed from these processes.

[0084] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A judgment system based on local impedance, It is characterized in that The judgment system performs the following steps: Acquire an excitation source of a loop formed by the ablation electrode to be measured and the irrelevant electrode; Acquiring a voltage difference between the ablation electrode to be measured and an ablation electrode adjacent to the ablation electrode to be measured by a pulse ablation catheter; Acquire the local impedance of the ablation electrode to be measured according to the excitation source, the voltage difference and a preset formula; The local impedance of the ablation electrode to be measured is received and judged to determine the position of the pulse ablation catheter in the heart cavity and adjust the energy output timing.

2. The local impedance-based determination system according to claim 1, It is characterized in that The judgment system further performs the following steps: After the local impedance of the ablation electrode to be measured is uploaded to the three-dimensional positioning navigation system, color rendering is performed.

3. The local impedance-based determination system according to claim 1, It is characterized in that The ablation electrode to be measured is also used to release ablation energy.

4. The local impedance-based determination system according to claim 1, It is characterized in that Receiving and judging the local impedance of the ablation electrode to be measured, including: The local impedance of the pulse ablation catheter is received by connecting the pigtail and judged; wherein the judging of the local impedance includes judging the local impedance according to a target baseline, and the target baseline is obtained according to a preset rule.

5. The local impedance determination system according to any one of claims 1 to 4, It is characterized in that The step of obtaining the excitation source of the loop formed by the ablation electrode to be measured and the irrelevant electrode comprises the following steps: Acquiring a first voltage value of the ablation electrode to be measured; Obtain a second voltage value of a preset resistor; The excitation source of the loop formed by the ablation electrode to be measured and the irrelevant electrode is obtained according to the first voltage value, the second voltage value and the preset resistance value.

6. The local impedance determination system according to any one of claims 1 to 4, It is characterized in that The step of obtaining the voltage difference between the ablation electrode to be measured and an ablation electrode adjacent to the ablation electrode to be measured comprises the following steps: Acquiring a third voltage of the ablation electrode to be measured; Acquiring a fourth voltage of an ablation electrode adjacent to the ablation electrode to be measured; The voltage difference of the ablation electrode to be measured is obtained according to the third voltage and the fourth voltage.

7. The local impedance determination system according to claim 4, It is characterized in that The determining of the local impedance according to the target baseline comprises the following steps: If the local impedance is greater than the target baseline, the ablation electrode transmitting the local impedance is brought into contact; If the local impedance is less than the target baseline, the ablation electrode transmitting the local impedance is not in contact.

8. A judgment system based on local impedance, It is characterized in that include: Pulse ablation catheter, pulse electric field ablation equipment, connecting pigtail, irrelevant electrode; The pulse ablation catheter is connected to the pulse electric field ablation device via the connecting pigtail; The indifferent electrode is connected to the pulsed electric field ablation device via the connecting pigtail; The pulse ablation catheter is used to obtain local impedance according to the excitation source and the voltage difference; The pulsed electric field ablation device is used to receive the local impedance and determine the local impedance; The pulse ablation catheter is used to measure the local impedance and release ablation energy. The ablation electrode close to the myocardial tissue can be obtained according to the local impedance generated by each ablation electrode on the pulse ablation catheter; the timing of the ablation electrode outputting energy can be adjusted.

9. The local impedance determination system according to claim 8, It is characterized in that The judgment system also includes a three-dimensional positioning and navigation system, which is used to receive initialization instructions and receive the judgment result of the pulse ablation device on the local impedance; wherein, after the pulse ablation device uploads the local impedance of the ablation electrode to the three-dimensional positioning and navigation system, it performs color rendering.

10. The local impedance determination system according to claim 8 or 9, It is characterized in that The pulse ablation catheter also includes: a ring-shaped end tube, a tube body, a positioning electrode, a handle and a connector; The annular end pipe is connected to the pipe body; The connector is connected to the tube body via the handle; The ablation electrode is arranged on the annular end tube; The positioning electrode is arranged on the tube body; The annular end tube is used to carry the ablation electrode; The positioning electrode is used to provide magnetic position information.

Images