A radio frequency ablation system based on intraoperative multi-time impedance difference to predict steam pop during catheter radio frequency ablation and automatically adjust ablation energy delivery

Abstract

The utility model relates to a kind of radiofrequency ablation system based on intraoperative multi-time-course impedance difference prediction catheter radiofrequency ablation intraoperative steam burst and automatic adjustment ablation energy delivery, belong to the intervention therapy technical field of arrhythmia, solve the problem of lacking the function of automatic adjustment ablation energy delivery based on impedance dynamic change in prior art.Rapid decline of impedance in ablation process is an independent risk factor for steam burst.The utility model is set by multiple time windows and corresponding impedance change threshold, to reduce the risk of steam burst in catheter radiofrequency ablation.Both reduce the potential risk of intraoperative complication, and not too frequent cut off ablation process affect the operation process, with good clinical application prospect.

Description

Technical Field

[0001] This utility model relates to the field of interventional treatment technology for arrhythmias, and in particular to a radiofrequency ablation system that predicts steam bursts during catheter radiofrequency ablation based on intraoperative multi-time-course impedance differences and automatically adjusts the delivery of ablation energy. Background Technology

[0002] Cardiac arrhythmia is the most common cardiovascular disease, and catheter radiofrequency ablation is an effective treatment for tachyarrhythmias. Radiofrequency is a high-frequency alternating current that generates heat to eliminate arrhythmic lesions. However, if the myocardium overheats, the vapor generated within the myocardium accumulates, and when it reaches a certain pressure, it can cause vapor explosion, damaging the structural integrity of the myocardium and leading to serious complications such as cardiac perforation, cardiac tamponade, and thromboembolism. A popping sound can be heard when vapor explosion occurs during radiofrequency ablation; its occurrence is sudden and unpredictable. Vapor explosion is more likely to occur when the catheter is extensively surrounded by myocardium, where blood flow is less than inside the heart chambers, resulting in slower heat dissipation. As the temperature rises during ablation, the impedance of the heated myocardial tissue to the current decreases; therefore, the decrease in impedance during ablation is a marker of tissue damage, and impedance can serve as a real-time indicator of damage. Previous literature reported that the change in impedance during ablation (impedance difference) can predict the occurrence of vapor explosion, but the optimal cutoff value is difficult to translate into clinical application due to limited sample size. With the development of manufacturing technology, the most advanced radiofrequency ablation devices currently available possess the function of automatically cutting off the ablation process based on peak impedance changes, such as 30-50Ω / 0.5s. However, this function aims to prevent the catheter from getting stuck in areas with large impedance changes, such as pockets or diverticula, and cannot prevent vapor bursting based on impedance changes after ablation begins. Its monitoring time range is defaulted to 0.5s, and it lacks multi-time-segment monitoring capabilities. In summary, based on extensive clinical case data from our center, the applicant has proposed the optimal predictive value for vapor bursting based on impedance differences at different time stages during the ablation process. Combining the cutoff values ​​for different time stages, the applicant has, for the first time, proposed a technology for automatically adjusting ablation energy delivery based on impedance change thresholds corresponding to multiple time stages in catheter radiofrequency ablation. Utility Model Content

[0003] Based on the above analysis, this utility model aims to provide a radiofrequency ablation system that predicts the occurrence of steam bursts during catheter radiofrequency ablation based on intraoperative multi-time-course impedance differences and automatically adjusts the ablation energy delivery, in order to solve the problem that existing radiofrequency ablation systems lack the function of automatically adjusting the ablation energy delivery based on dynamic impedance changes.

[0004] The objective of this utility model is mainly achieved through the following technical solutions: A radiofrequency ablation system that predicts vapor bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery. The procedure involves real-time monitoring of dynamic impedance differences across multiple time periods. Based on comparisons between impedance differences set by the user within different time windows after ablation begins and preset thresholds, the radiofrequency energy delivery is automatically adjusted. These time windows are t1, t2, ..., tn, and the total ablation time is t. total The impedance drop thresholds for each time window are T1, T2, ..., Tn, and the impedance drop threshold for the entire ablation process is T. total .

[0005] Further improvements based on the above scheme: The system includes an impedance detection module; the impedance monitoring module uses dynamic time series analysis technology to calculate the impedance difference in each time window in real time, and combines it with a preset impedance drop threshold to comprehensively judge the risk of steam explosion.

[0006] Further improvements to the above scheme: the system measured the overall impedance of the radiofrequency ablation circuit in all experimental cases.

[0007] Based on further improvements to the above scheme, the system includes a main control module; the main control module is configured to: synchronously record impedance data of multiple time windows during the ablation process; dynamically correct the impedance difference using a time-weighted algorithm to adapt to the ablation characteristics of different tissue sites; and trigger gradient degradation or cutoff of radio frequency energy delivery when the impedance difference of a certain number of time windows exceeds the corresponding threshold.

[0008] Based on the further improvement of the above scheme, the time-weighted algorithm introduces a correction factor and a corresponding algorithm. The correction factor includes the ablation site of the catheter. When the catheter is ablated at a site prone to vapor bursting, it is equivalent to triggering a single time window impedance difference greater than the corresponding preset impedance threshold. Based on the experimental example of this utility model, the sites prone to vapor bursting are the anterior superior margin of the left pulmonary vein and the inferior vena cava side of the tricuspid isthmus.

[0009] Based on the further improvement of the above scheme, the time-weighted algorithm introduces a correction factor and a corresponding algorithm. The correction factor should also include the blood flow velocity at the ablation site, the saline perfusion flow rate of the ablation catheter, and the contact pressure to adjust the impedance drop threshold in real time. Among them, the threshold for a lower risk of impedance rupture can be appropriately increased, and the threshold for a higher risk can be appropriately decreased.

[0010] Based on further improvements to the above scheme, the system includes a human-computer interaction interface; the human-computer interaction interface provides multi-time-term visual feedback and auditory feedback. The visual feedback can display the dynamic relationship between the impedance difference and the threshold in each time window in real time, and the auditory feedback indicates the risk level with different prompt tones; during the ablation process, if the impedance difference exceeds the threshold corresponding to a single time window, it is set to a regular short intermittent sound and a simulated artificial voice indicating "medium risk"; if the impedance difference exceeds the threshold corresponding to two time windows, it is set to a continuous sound without interruption and a simulated artificial voice indicating "high risk"; the operator is allowed to manually adjust the time window length and threshold parameters.

[0011] Based on further improvements to the above scheme, the main control module integrates an adaptive learning engine to optimize multi-time-series thresholds through historical ablation data. Specifically, this includes: dynamically adjusting threshold sensitivity according to the surgeon's operating habits; and automatically updating the threshold database in conjunction with feedback from intraoperative complications.

[0012] Based on further improvements to the above scheme, The radio frequency power amplifier module supports pulsed energy delivery. When the impedance difference is detected to be close to the threshold, it automatically switches to intermittent pulse mode to reduce the risk of tissue vapor explosion.

[0013] Based on the further improvement of the above scheme, the cutoff logic of the system is a phased response: if a single time window threshold is triggered, the auditory feedback is intermittent sound and simulated artificial speech "medium risk", only the ablation power is reduced; if two or more time window thresholds are triggered, the auditory feedback is continuous sound and simulated artificial speech "high risk", then the energy delivery is completely cut off.

[0014] Further improvements to the above scheme: the parameters were validated using large-scale clinical data.

[0015] Based on further improvements to the above scheme, t1 is recommended to be 3s and T1 is recommended to be 9.5Ω.

[0016] Based on further improvements to the above scheme, t2 is recommended to be 5s and T2 is recommended to be 10.5Ω.

[0017] Based on further improvements to the above scheme, t3 is recommended to be 10s and T3 is recommended to be 13.5Ω.

[0018] Based on further improvements to the above scheme, T total The recommended value is 18.5Ω.

[0019] This invention proposes a method for automatically adjusting ablation energy delivery based on impedance change thresholds corresponding to multiple time periods during catheter radiofrequency ablation to avoid vapor explosion and improve surgical safety. Impedance is a fundamental parameter in radiofrequency ablation, and this method is simple and easy to implement, offering valuable insights for subsequent clinical procedures. The automatic adjustment of ablation energy delivery based on impedance changes proposed in this invention has the advantage of avoiding frequent ablation interruptions due to excessively low threshold settings, which could affect the surgical process, while also avoiding the potential risk of surgical complications due to excessively high threshold settings. It balances surgical efficiency with effectively reducing the potential risk of vapor explosion.

[0020] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or be learned by practicing this invention. The objectives and other advantages of this invention can be realized and obtained from the details specifically pointed out in the text and accompanying drawings. Attached Figure Description

[0021] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0022] Figure 1 This is a block diagram of the radiofrequency ablation system according to an embodiment of the present invention. Figure 2 This is a schematic diagram showing the occurrence rate and spatial distribution of steam explosion in this utility model; Figure 3 This is a diagram showing the ablation parameters of an experimental example of steam explosion in this invention. Figure 4 This is a working characteristic curve of the ablation parameter that has statistical significance in predicting steam explosion in this utility model; Figure 5 This is a structural block diagram of the radiofrequency ablation system using a common ablation catheter according to this utility model; Figure 6 This is a flowchart of the algorithm for determining the risk level of steam explosion according to this utility model; Figure 7 This is a schematic diagram illustrating the function of predicting steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusting ablation energy delivery, as an example of implementing this utility model. Detailed Implementation

[0023] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0024] A specific embodiment of this utility model discloses a radiofrequency ablation system that predicts vapor bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts the ablation energy delivery. Figure 1 As shown, the system includes: (1) Radiofrequency ablation module, consisting of a catheter and a negative electrode plate; in this experimental example, a common ablation catheter for measuring the overall impedance of the radiofrequency ablation circuit is used. (2) Power supply module, which provides power to other modules of the ablation system and provides linearly adjustable power to the radio frequency power amplifier module; Radio frequency power amplifier module, which generates high-frequency alternating current to generate radio frequency energy; (3) Temperature monitoring module: The thermocouples arranged at the electrodes at the distal end of the ablation catheter measure the temperature of the tissue at the treatment site in real time and transmit the temperature signal back to the temperature controller in real time to realize the temperature feedback function. (4) Impedance monitoring module, including output voltage / current detection circuit; based on the use of ordinary ablation catheter in this experimental example, radiofrequency current flows from the distal ablation electrode at the contact surface of the tissue electrode to the negative electrode plate. According to Ohm's law, the impedance that can be indirectly measured is the sum of the impedances of the entire circuit; this module adopts dynamic time series analysis technology, which focuses on processing data that changes over time and can adapt to the dynamic changes of data; it ensures that the impedance signal is transmitted back to the impedance controller in real time to realize the impedance feedback function; (5) The main control module is configured to receive the measurement results of the impedance monitoring module; the time window refers to the mechanism for restricting, analyzing or processing events, data or operations within a specific preset time period from the start of ablation. The main control module is configured to: synchronously record impedance data of multiple time windows during the ablation process; dynamically correct the impedance difference using a time-weighted algorithm to adapt to the ablation characteristics of different tissue sites; and trigger gradient degradation or cutoff of radio frequency energy delivery when the impedance difference of a certain number of time windows exceeds the corresponding threshold. (6) The human-computer interaction interface adopts a medical serial port screen that can set the ablation mode, ablation power and main control module. The main control module judges the risk of vapor explosion based on the comparison results of the impedance difference in different time windows set by the user after the start of ablation and the preset threshold, and automatically adjusts the radio frequency energy delivery.

[0025] This prospective study included cases of steam bursting during atrial fibrillation ablation. The incidence and distribution of steam bursting were statistically analyzed. This section confirms that the probability of steam bursting during atrial fibrillation radiofrequency ablation is 2.2%, with the most common sites of steam bursting being the anterior superior margin of the left pulmonary vein and the inferior vena cava side of the tricuspid isthmus.

[0026] This invention analyzes which ablation parameters can effectively predict the occurrence of steam explosion, and confirms that the impedance difference is the only reliable predictor of steam explosion.

[0027] This invention uses the subject working characteristic curve to determine the optimal cutoff value for predicting steam explosion based on the impedance difference corresponding to different time windows. The optimal cutoff values ​​for predicting steam explosion during radiofrequency ablation are 9.5Ω (3 s before ablation), 10.5Ω (5 s before ablation), 13.5Ω (10 s before ablation), and 18.5Ω (during the entire ablation process).

[0028] This invention allows for the setting of multiple time windows (t, time) and corresponding impedance drop thresholds (T, threshold). It is recommended to use the parameters obtained from the experimental examples in the radiofrequency ablation system of this invention.

[0029] A specific embodiment of this utility model discloses a radiofrequency ablation system that predicts vapor explosion during catheter radiofrequency ablation based on intraoperative multi-time-course impedance difference and automatically adjusts ablation energy delivery. The system monitors dynamic impedance differences across multiple time courses in real time during the procedure. Based on the comparison between the impedance difference within different time windows set by the user after ablation begins and a preset threshold, the system automatically adjusts the radiofrequency energy delivery. These time windows are t1, t2, ..., tn, and the total ablation time is t_n. total The impedance drop thresholds for each time window are T1, T2, ..., Tn, and the total impedance drop threshold for the entire ablation process is T. total n represents the number of windows.

[0030] Specifically, the impedance monitoring module uses dynamic time series analysis technology to calculate the impedance difference in each time window in real time, and combines it with the preset impedance drop threshold to comprehensively judge the risk of steam explosion.

[0031] Specifically, the system measured the overall impedance of the radiofrequency ablation circuit in all experimental cases.

[0032] Specifically, the main control module is configured to: synchronously record impedance data for multiple time windows during the ablation process; dynamically correct the impedance difference using a time-weighted algorithm to adapt to the ablation characteristics of different tissue sites; and trigger gradient degradation or cutoff of radio frequency energy delivery when the impedance difference of a certain number of time windows exceeds the corresponding threshold.

[0033] Specifically, the time-weighted algorithm introduces a correction factor and a corresponding algorithm. The correction factor includes the ablation site of the catheter. When the catheter is ablated at a site prone to vapor bursting, it is equivalent to triggering a single time window impedance difference greater than the corresponding preset impedance threshold. Based on the experimental example of this utility model, the sites prone to vapor bursting are the anterior superior margin of the left pulmonary vein and the inferior vena cava side of the tricuspid isthmus.

[0034] Specifically, the time-weighted algorithm introduces a correction factor and a corresponding algorithm. The correction factor should also include the blood flow velocity at the ablation site, the saline perfusion flow rate of the ablation catheter, and the contact pressure. The impedance reduction threshold should be adjusted in real time. The threshold for a lower risk of impedance rupture can be appropriately increased, while the threshold for a higher risk can be appropriately decreased.

[0035] Specifically, the system includes a human-computer interaction interface; the human-computer interaction interface provides multi-time-process visual feedback and auditory feedback. The visual feedback can display the dynamic relationship between the impedance difference and the threshold in each time window in real time, and the auditory feedback indicates the risk level with different prompt tones; during the ablation process, if the impedance difference exceeds the threshold corresponding to a single time window, it is set to a regular short intermittent sound and a simulated artificial voice indicating "medium risk"; if the impedance difference exceeds the threshold corresponding to two time windows, it is set to a continuous sound without interruption and a simulated artificial voice indicating "high risk"; the operator is allowed to manually adjust the time window length and threshold parameters.

[0036] Specifically, the main control module integrates an adaptive learning engine to optimize multi-timescale thresholds through historical ablation data, including: dynamically adjusting threshold sensitivity based on the surgeon's operating habits; and automatically updating the threshold database in conjunction with feedback from intraoperative complications.

[0037] Specifically, the radio frequency power amplifier module supports pulsed energy delivery. When the impedance difference is detected to be close to the threshold, it automatically switches to intermittent pulse mode to reduce the risk of vapor explosion in the tissue.

[0038] Specifically, the system's cutoff logic is a phased response: if a single time window threshold is triggered, the auditory feedback is intermittent sounds and simulated artificial speech "medium risk", only the ablation power is reduced; if two or more time window thresholds are triggered cumulatively, the auditory feedback is continuous sounds and simulated artificial speech "high risk", then energy delivery is completely cut off.

[0039] Specifically, the parameters were validated using large-scale clinical data.

[0040] Specifically, t1 is recommended to be 3s, and T1 is recommended to be 9.5Ω.

[0041] Specifically, t2 is recommended to be 5s, and T2 is recommended to be 10.5Ω.

[0042] Specifically, the recommended voltage for T3 is 10s, and the recommended current rating for T3 is 13.5Ω.

[0043] Specifically, T total The recommended value is 18.5Ω.

[0044] To facilitate understanding of the technical solution of this utility model, taking atrial fibrillation (AF), the most common persistent arrhythmia, catheter radiofrequency ablation as an example, and combining the applicant's experimental case, the application of the method for automatically adjusting ablation energy delivery based on impedance change thresholds corresponding to multiple time periods in AF radiofrequency ablation is further explained. However, the scope of protection of this utility model is not limited to the applicant's experimental case. Those skilled in the art, based on the technical content of this utility model, and using their own clinical experience and practical examples, should all fall within the scope of protection of this utility model by simply replacing and substituting the parameters proposed in this utility model, including different time windows (t) and corresponding change thresholds (T). The scope of protection of this utility model is defined by the claims.

[0045] Research subjects This study retrospectively analyzed 3,263 atrial fibrillation patients who underwent radiofrequency ablation for the first time at Beijing Anzhen Hospital, affiliated with Capital Medical University, between July 2023 and January 2024.

[0046] catheter ablation process Preoperative transesophageal echocardiography or intraoperative intracardiac echocardiography after puncture is performed to rule out atrial thrombosis. Patients already taking warfarin do not need to discontinue the medication before surgery; the international normalized ratio (INR) should be maintained between 2.0 and 3.0. Patients taking newer oral anticoagulants do not need to discontinue the medication before surgery. All antiarrhythmic drugs except amiodarone should be discontinued for at least five half-lives before surgery. All patients undergo surgery in a fasting and sedated state. (If necessary) Intracardiac echocardiography is implanted via the right femoral vein, a coronary sinus electrode is placed via puncture of the left femoral vein, and atrial septal puncture is performed via the right femoral vein. An initial dose of unfractionated heparin 6000 IU is administered, with additional heparin added based on the activated clotting time (ACT) to maintain it at 300-350 seconds.

[0047] Reconstruction of the three-dimensional anatomical model of the left atrium: The three-dimensional anatomical reconstruction of the left atrium was performed by taking points in the left atrium through a star-shaped high-density mapping catheter (PentaRay, Johnson & Johnson).

[0048] For patients with paroxysmal atrial fibrillation, only bilateral pulmonary vein isolation is performed. For patients with persistent atrial fibrillation, some undergo Marshall vein ablation with anhydrous alcohol after three-dimensional anatomical reconstruction of the left atrium to improve the mitral isthmus line block rate. Bilateral pulmonary vein isolation is performed first, followed by linear ablation at the left atrial roof, mitral isthmus, and tricuspid isthmus. Based on the operator's intraoperative judgment, some patients continue ablation of fragmented potentials in the left atrial anterior wall and coronary sinus. If the patient remains in atrial fibrillation rhythm, cardioversion is performed directly, followed by verification of pulmonary vein isolation and the integrity of the ablation path. The ablation power is controlled at 40W-50W during pulmonary vein isolation, 35W-45W for the mitral isthmus line, 30W-40W for the tricuspid isthmus and roof line, and 25W for the coronary sinus. The ablation endpoint is single-catheter verification of bilateral pulmonary vein isolation. The ablation endpoint at each point is guided by the ablation index. The ablation index is 450-550 when ablating at the anterior and top of the pulmonary vein, 350-400 when ablating at the posterior of the pulmonary vein, 400-500 when ablating at the top of the left atrium and the tricuspid isthmus, and 500-600 when ablating at the mitral isthmus.

[0049] Data processing and analysis Statistical analysis was performed using SPSS 26.0 software. Quantitative data were expressed as mean ± standard deviation if they followed a normal distribution, and as median (first quartile, third quartile) if they were skewed. Independent samples t-tests or Mann-Whitney rank-sum tests were performed on the quantitative data according to their distribution. Categorical variables were expressed as frequency and percentage. Multivariate logistic regression analysis was used to explore the risk factors for steam explosion. Receiver operating characteristic (ROC) curve analysis was used to calculate the area under the curve, sensitivity, specificity, and cutoff value for the risk factors. P < 0.05 was considered statistically significant.

[0050] result Of the 3,263 patients, 71 patients experienced a total of 81 steam bursts during the ablation process.

[0051] 1) Occurrence and distribution of steam explosion Steam bursts occurred 47 times during pulmonary vein isolation, with 37 occurring in the left pulmonary vein and 10 in the right. Steam bursts occurred 6 times in the mitral isthmus, 16 times in the tricuspid isthmus, 7 times in the apical line, 3 times in the atrial fragmentation potential, and 2 times in the coronary sinus during ablation. The highest incidence of steam bursts was observed at the anterosuperior margin of the left pulmonary vein and on the inferior vena cava side of the tricuspid isthmus. For details on the incidence and distribution of steam bursts, see [link to relevant documentation]. Figure 2The red dots represent the locations of vapor bursts. LA, left atrium; PA, posteroanterior left atrium; roofline; LSPV, left superior pulmonary vein; LIPV, left inferior pulmonary vein; RSPV, right superior pulmonary vein; RIPV, right inferior pulmonary vein; LAA, left atrial appendage; MAI, mitral isthmus; CFAEs, fragmentation potentials; CS, coronary sinus; TA, tricuspid valve; CTI, tricuspid isthmus; IVC, inferior vena cava.

[0052] 2) Characteristics of steam explosion The 81 steam explosion cases were labeled a0-9, b0-9, c0-9, d0-9, e0-9, f0-9, g0-9, h0-9, and i0-9, respectively. Details of parameter changes during ablation are available in [link to relevant documentation]. Figure 3 Among them, RF Duration, RF Power, AI value, Minimum Temperature, Maximum Temperature, Average Temperature, Minimum Impedance, and Maximum Impedance are the following parameters: RF Duration, RF Power, AI value, Minimum Temperature, Maximum Temperature, Average Temperature, Minimum Impedance, Minimum Impedance, and Maximum Impedance. Impedance, impedance difference; Minimum Contact Force, contact pressure trough; Maximum Contact Force, contact pressure peak; Average Contact Force, contact pressure average.

[0053] 3) Comparison of ablation parameters Two ablation points adjacent to the steam explosion location but in opposite directions were selected as the control group. Five isolated ablation points without surrounding ablation points were also included as the control group. A detailed comparison of ablation parameters between steam explosion and adjacent ablation points is shown in Table 1. There were no statistically significant differences in ablation power, average temperature, peak temperature, impedance valley, impedance peak, average contact pressure, and peak contact pressure between steam explosion and adjacent non-pop sites. The impedance difference was significantly higher in the pop region than in the adjacent non-pop region.

[0054] Table 1. Comparison of ablation parameters between steam explosion and surrounding sites

[0055] 4) Hazardous factors of steam explosion Logistic regression analysis was used to analyze the risk factors for steam explosion (see Table 2). The impedance differences in the first 3 seconds, 5 seconds, and first 10 seconds during radiofrequency ablation, as well as the impedance differences throughout the entire ablation process, were statistically significant. Receiver operating characteristic (ROC) curve analysis showed (see...) Figure 4 The analysis included: a) ROC curve analysis of impedance difference prediction for steam explosion 3 seconds before ablation; b) ROC curve analysis of impedance difference prediction for steam explosion 5 seconds before ablation; c) ROC curve analysis of impedance difference prediction for steam explosion 10 seconds before ablation; and d) ROC curve analysis of impedance difference prediction for steam explosion throughout the entire ablation process. Sensitivity, specificity, and AUC (area under the curve) are also included. The optimal cutoff values ​​for impedance difference in the first 3 seconds, the first 5 seconds, the first 10 seconds, and the entire ablation process were 9.5Ω (sensitivity 73%, specificity 57%; area under the curve = 0.70, 95% confidence interval 0.63–0.78), 10.5Ω (sensitivity 68%, specificity 61%; area under the curve = 0.71, 95% confidence interval 0.64–0.79), 13.5Ω (sensitivity 72%, specificity 60%; area under the curve = 0.71, 95% confidence interval 0.63–0.79), and 18.5Ω (sensitivity 89%, specificity 40%; area under the curve = 0.66, 95% confidence interval 0.59–0.74).

[0056] Table 2. Logistic regression analysis of ablation parameters

[0057] 5) A method for automatically adjusting ablation energy delivery based on impedance change thresholds corresponding to multiple time histories. Based on partial results from clinical studies, an impedance difference exceeding the corresponding optimal cutoff value at different ablation time intervals is an independent risk factor for steam explosion. Unlike existing automated ablation processes, this method allows setting multiple parameters, including different time windows (t) and corresponding change thresholds (T).

[0058] To determine whether steam explosion has occurred, the impedance monitoring module of the system described in this invention employs dynamic time series analysis technology. This technology focuses on processing data that changes over time and can adapt to dynamic changes in the data; it ensures that the impedance signal is transmitted back to the impedance controller in real time to achieve impedance feedback. It calculates the impedance difference within each time window and combines it with a preset impedance drop threshold to comprehensively assess the risk of steam explosion. The main control module receives impedance monitoring information and can be configured to utilize classifiers and / or other machine learning algorithms. In the experimental example, multiple classifiers can be used in parallel, in series, and / or in any number of other ensembles. Classifier algorithms include decision tree algorithms, support vector machines, and can include any number of other machine learning techniques. According to the experimental example, supervised and / or unsupervised learning can be used to increase the accuracy and efficiency of the calculation used to determine the impedance metric over time.

[0059] The system and method described in this paper are implemented as a closed-loop system. The actions taken by the main control module are triggered by the system's judgment of the risk level (low / medium / high) of vapor explosion. In the experimental example, the system is specifically configured as follows: when the impedance difference detected is close to the threshold, it automatically switches to an intermittent pulse mode to reduce the risk of tissue vapor explosion. If a single time window threshold is not triggered during the ablation process (the system's auditory feedback is set to mute), the system judges the risk of vapor explosion as low, and no adjustment is needed for radio frequency energy delivery. If a single time window threshold is triggered or ablation is performed at a location prone to vapor explosion and no time window impedance difference is triggered (the auditory feedback is an intermittent tone and a simulated artificial voice "medium risk"), the system judges the risk of vapor explosion as medium risk and only reduces the ablation power. If two or more time window thresholds are triggered cumulatively or a single time window threshold is triggered during ablation at a location prone to vapor explosion (the auditory feedback is a continuous tone and a simulated artificial voice "high risk"), the system judges the risk of vapor explosion as high risk and completely cuts off energy delivery.

[0060] Various modifications and operations can be made to the discussed example experiments without departing from the scope of this disclosure. For example, the surgeon may simply change and substitute the specific values ​​of parameters t and T based on their own clinical experience and practical considerations. Therefore, the scope of this disclosure is intended to cover all such substitutions, modifications, and variations that fall within the scope of the claims.

[0061] To illustrate the radiofrequency ablation system based on large-scale clinical data from experimental cases, which predicts steam bursting during catheter radiofrequency ablation using intraoperative multi-time-course impedance difference and automatically adjusts ablation energy delivery, please see [link to documentation]. Figure 5 . Figure 5This is a block diagram of the radiofrequency ablation system, including a human-machine interface, power supply module, main control module, radiofrequency power amplifier, radiofrequency ablation module, temperature monitoring module, and impedance monitoring module. The human-machine interface uses a medical serial port screen to set the ablation mode, ablation parameters, t, T, and start-up time. The power supply module mainly provides power to other modules and provides linearly adjustable DC power to the radiofrequency power amplifier module. The radiofrequency power amplifier mainly generates high-frequency alternating current to produce radiofrequency energy. The temperature monitoring module can measure and transmit the temperature of the tissue at the treatment site in real time. The impedance monitoring module can perform impedance measurement in real time, and the impedance signal is transmitted back to the impedance controller in real time to achieve impedance feedback. The main control board receives feedback from each module, performs control outputs, monitors the operating status of each module, and implements corresponding protection mechanisms.

[0062] Figure 6 and Figure 7 This is a schematic diagram of the function proposed in this utility model for predicting steam bursts during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusting ablation energy delivery.

[0063] Those skilled in the art will understand that the programs / software involved in the main control module in the above embodiments are common methods in the prior art. For example, existing methods that output different signals based on different values ​​can be run in the main control module. This utility model does not involve any software improvements. This utility model only requires connecting the various devices with corresponding functions through the connection relationships given in the embodiments of this utility model, which does not involve any program or software improvements. As for the connection methods between the various hardware devices with corresponding functions, they can all be implemented by those skilled in the art using existing technology, and will not be described in detail here.

[0064] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model should be included within the protection scope of the present utility model.

Claims

1. A radiofrequency ablation system that predicts vapor bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, characterized in that, include: The impedance monitoring module, including voltage / current detection circuitry, is configured to monitor multi-time-term dynamic impedance differences in real time. The main control module is configured to receive the measurement results from the impedance monitoring module and automatically adjust the radio frequency energy delivery based on the comparison results of the impedance difference within different time windows set by the user after the ablation begins and the preset threshold. The radio frequency power amplifier module is configured to generate radio frequency energy by producing a high-frequency alternating current based on the comparison result of the main control module. The radiofrequency ablation module consists of a catheter and a negative electrode plate; it uses a common ablation catheter for measuring the overall impedance of the radiofrequency ablation circuit. Power module; It is configured to provide power to other modules of the ablation system and to provide linearly adjustable power to the RF power amplifier module; The temperature monitoring module, including thermocouples and a temperature controller for the electrode arrangement at the distal end of the ablation catheter, is configured to measure the temperature of the tissue at the treatment site in real time and transmit the temperature signal back to the temperature controller in real time to achieve temperature feedback. The human-computer interaction interface uses a medical serial port screen; The time windows are t1, t2, ..., tn, respectively, and the total ablation time is t. total The impedance drop thresholds for each time window are T1, T2, ..., Tn, and the total impedance drop threshold for the entire ablation process is T. total .

2. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that: The impedance monitoring module is configured to use dynamic time series analysis technology to calculate the impedance difference in each time window in real time, and combine it with the preset impedance drop threshold to comprehensively judge the risk of steam explosion.

3. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that: This system measures the overall impedance of the radiofrequency ablation circuit.

4. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The main control module is configured to: synchronously record impedance data of multiple time windows during the ablation process; dynamically correct the impedance difference using a time-weighted algorithm to adapt to the ablation characteristics of different tissue sites; and trigger gradient degradation or cutoff of radio frequency energy delivery when the impedance difference of a certain number of time windows exceeds the corresponding threshold.

5. The radiofrequency ablation system according to claim 4, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The time-weighted algorithm introduces a correction factor and a corresponding algorithm. The correction factor includes the ablation site of the catheter. When the catheter is ablated at a site prone to vapor bursting, it is equivalent to triggering a single time window impedance difference greater than the corresponding preset impedance threshold. The sites prone to vapor bursting are the anterior superior margin of the left pulmonary vein and the inferior vena cava side of the tricuspid isthmus.

6. The radiofrequency ablation system according to claim 4, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The time-weighted algorithm introduces a correction factor and a corresponding algorithm. The correction factor should also include the blood flow velocity at the ablation site, the saline perfusion flow rate of the ablation catheter, and the contact pressure. The impedance reduction threshold should be adjusted in real time. Specifically, the threshold for a lower risk of impedance rupture can be appropriately increased, while the threshold for a higher risk can be appropriately decreased.

7. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The human-computer interface provides multi-time-phase visual feedback and auditory feedback. The visual feedback can display the dynamic relationship between the impedance difference and the threshold in each time window in real time. The auditory feedback indicates the risk level with different prompt tones. During the ablation process, if the impedance difference exceeds the threshold corresponding to a single time window, it is set to a regular short intermittent sound and a simulated artificial voice "medium risk". If the impedance difference exceeds the threshold corresponding to two time windows, it is set to a continuous sound without interruption and a simulated artificial voice "high risk". Operators are allowed to manually adjust the time window length and threshold parameters.

8. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The main control module integrates an adaptive learning engine and is configured to optimize multi-temporal thresholds using historical ablation data. Specifically, this includes: dynamically adjusting threshold sensitivity based on the surgeon's operating habits; and automatically updating the threshold database in conjunction with feedback from intraoperative complications.

9. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The radio frequency power amplifier module is configured to support pulsed energy delivery and automatically switches to intermittent pulse mode when the impedance difference is detected to be close to a threshold in order to reduce the risk of tissue vapor explosion.

10. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... The system's cutoff logic is a phased response: the main control module is configured such that if a single time window threshold is triggered, the auditory feedback is intermittent tone and simulated artificial speech "medium risk", only the ablation power is reduced; if two or more time window thresholds are triggered, the auditory feedback is continuous tone and simulated artificial speech "high risk", then energy delivery is completely cut off.

11. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... t1 is 3s, T1 is 9.5Ω.

12. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... t2 is 5s, T2 is 10.5Ω.

13. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... t3 is 10s, T3 is 13.5Ω.

14. The radiofrequency ablation system according to claim 1, which predicts steam bursting during catheter radiofrequency ablation based on intraoperative multi-time-path impedance difference and automatically adjusts ablation energy delivery, is characterized in that... T total It is 18.5Ω.

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