Zero force calibration for basket catheter

Abstract

This disclosure provides a system including a catheter with an expandable distal end assembly (EDEA) and a processor having multiple electrodes. The processor is configured to: receive input from a user command to perform force zeroing measurements on the EDEA while in the patient's heart; estimate the actual positions of at least some electrodes; determine reference positions of the electrodes; calculate the deviation between the actual positions and the corresponding reference positions; and enable or prevent force zeroing measurements based on the calculated deviations. This system improves the accuracy of force measurements by automatically determining when conditions are suitable for force zeroing, thereby enhancing the reliability of subsequent force measurements during medical procedures.

Description

Technical Field

[0001] The present invention relates generally to medical devices, and more particularly to methods and systems for estimating mechanical / deformational forces applied between a catheter and tissue. Background Technology

[0002] Various techniques for measuring and / or estimating contact forces exerted by medical devices within tissue are known in the art. Effective techniques for obtaining such force measurements are constantly being improved. Specifically, catheters with expandable distal end-effector assemblies (EDEAs) equipped with multiple electrodes are used in mapping and ablation procedures in the heart. These catheters typically incorporate force-sensing capabilities to measure the contact forces between the catheter and cardiac tissue.

[0003] Catheters with EDEA, such as basket catheters, expand within the heart chambers to contact the chamber walls. Electrodes on these catheters can be used for a variety of purposes, including sensing electrical activity in the heart, delivering ablation energy, and providing location information. The ability to accurately determine the location of these electrodes within the heart is crucial for many cardiac procedures.

[0004] Over the years, position sensing technologies for medical devices have advanced significantly. These technologies utilize various physical principles, such as electromagnetic fields, electrical impedance measurements, or mechanical sensors, to determine the location and orientation of catheter electrodes within the body. Advanced signal processing techniques are typically employed to improve the accuracy and reliability of these position measurements.

[0005] The mechanical properties of catheters, especially those with expandable components, can be complex. Catheters are typically designed to be flexible enough to navigate through blood vessels while still maintaining sufficient rigidity to apply controlled forces when necessary. The materials used in the catheter construction, such as nitinol, contribute to these mechanical properties.

[0006] As medical protocols become increasingly complex, research and development are underway aimed at improving the accuracy and reliability of medical devices and related measurement technologies. This includes efforts to enhance force sensing capabilities, position tracking accuracy, and the overall performance of catheter-based systems used in cardiac protocols. Summary of the Invention

[0007] Technical Solution 1. A system comprising: A catheter, the catheter including an expandable distal end assembly (EDEA), the expandable distal end assembly (EDEA) including a plurality of electrodes disposed thereon; and Processor, the processor being configured as follows: The reference positions of the plurality of electrodes of the catheter relative to a reference point are stored in the memory; The actual location of the plurality of electrodes is monitored when the EDEA is in vivo; Zero-point force calibration is enabled or disabled by comparing the deviation between the actual position and the reference position with a deviation threshold. If the zero-point force calibration is enabled, the zero-point force calibration is actuated based on the received command; The force is calculated based on the deviation from the actual position and the output from the zero-point force calibration; and An electronic display configured to display the calculated force.

[0008] Technical Solution 2. The system according to Technical Solution 1, wherein the processor is configured to disable the zero-point force calibration measurement based on the deviation exceeding the deviation threshold, and to restart another zero-point force calibration measurement based on the deviation decreasing below the deviation threshold.

[0009] Technical Solution 3. The system according to Technical Solution 1, wherein the processor is configured to monitor one or both of impedance and intracardiac electrogram (ICEG) at each of the plurality of electrodes, and to enable or disable the zero-point force calibration measurement based on a predefined standard defined for one or both of impedance and ICEG and based on the comparison of the deviation with the deviation threshold.

[0010] Technical Solution 4. The system according to any one of Technical Solutions 1-3, wherein the deviation threshold is dynamically updated based on the deviation calculated within a limited time period.

[0011] Technical Solution 5. The system according to any one of Technical Solutions 1-3, wherein the deviation threshold is user-defined.

[0012] Technical Solution 6. The system according to any one of technical solutions 1-3, wherein the command is based on user input requesting the zero-point force calibration.

[0013] Technical Solution 7. The system according to any one of Technical Solutions 1-3, wherein the command is automatically performed based on the processor recognizing predefined events.

[0014] Technical Solution 8. The system according to any one of technical solutions 1-3, wherein the processor is configured to render a virtual representation of the EDEA and update the shape of the virtual representation based on the actual positions of the monitored plurality of electrodes.

[0015] Technical Solution 9. The system according to any one of Technical Solutions 1-3, wherein the EDEA is in the form of a basket comprising a plurality of deformable splines, and wherein the actual positions of the plurality of electrodes are determined based on a mechanical model of the EDEA and outputs from a plurality of magnetically based position sensors mounted on the deformable splines.

[0016] Technical Solution 10. The system according to any one of technical solutions 1-3, wherein the reference configuration of the EDEA is predetermined in vitro during the calibration procedure.

[0017] Technical Solution 11. A method comprising: The reference positions of multiple electrodes relative to a reference point are stored in the memory; the multiple electrodes are disposed on the expandable distal end assembly (EDEA) of the catheter. The actual location of the plurality of electrodes is monitored when the EDEA is in vivo; Zero-point force calibration is enabled or disabled by comparing the deviation between the actual position and the reference position with a deviation threshold. If the zero-point force calibration is enabled, the zero-point force calibration is actuated based on the received command; The force is calculated based on the deviation from the actual position and the output from the zero-point force calibration; and Displays the calculated force.

[0018] Technical Solution 12. The method according to Technical Solution 11, wherein enabling or disabling the zero-point force calibration includes: disabling the zero-point force calibration measurement based on the deviation exceeding the deviation threshold, and restarting another zero-point force calibration measurement based on the deviation decreasing below the deviation threshold.

[0019] Technical Solution 13. The method according to Technical Solution 11, wherein enabling or disabling the zero-point force calibration comprises: monitoring one or both of impedance and intracardiac electrogram (ICEG) at each of the plurality of electrodes, and enabling or disabling the zero-point force calibration measurement based on a predefined standard defined for one or both of impedance and ICEG and based on the comparison of the deviation with the deviation threshold.

[0020] Technical Solution 14. The method according to any one of technical solutions 11-13, and including dynamically updating the deviation threshold based on the deviation calculated within a defined time period.

[0021] Technical Solution 15. The method according to any one of technical solutions 11-13, wherein the deviation threshold is user-defined.

[0022] Technical Solution 16. The method according to any one of technical solutions 11-13, wherein the command is based on user input requesting the zero-point force calibration.

[0023] Technical Solution 17. The method according to any one of technical solutions 11-13, wherein the command is performed automatically based on the identification of predefined events.

[0024] Technical Solution 18. The method according to any one of Technical Solutions 11-13, and including rendering a virtual representation of the EDEA, and updating the shape of the virtual representation based on the actual positions of the monitored plurality of electrodes.

[0025] Technical Solution 19. The method according to any one of technical solutions 11-13, wherein the EDEA is in the form of a basket comprising a plurality of deformable splines, and wherein the actual position of the plurality of electrodes is determined based on a mechanical model of the EDEA and outputs from a plurality of magnetically based position sensors mounted on the deformable splines.

[0026] Technical Solution 20. The method according to any one of technical solutions 11-13, wherein the reference configuration of the EDEA is predetermined in vitro during the calibration procedure. Attached Figure Description

[0027] The invention will be more fully understood from the following detailed description of examples of the invention, taken in conjunction with the accompanying drawings, wherein: Figure 1 This is a schematic diagram of a catheter-based location-tracking and ablation system according to an example of the present invention; Figure 2 For example according to the present invention Figure 1 The schematic diagram of the distal end assembly of the catheter in the system depicted illustrates different locations of the distal end assembly within the patient's heart; and Figure 3 A flowchart illustrating an example of a method for estimating zero-point force calibration according to an invention is provided. Detailed Implementation

[0028] Overview Calibration procedures play a crucial role in ensuring the accuracy of force measurements obtained from medical devices. These procedures may involve establishing baseline measurements or determining reference locations under controlled conditions. Specific calibration requirements can vary depending on the device type and intended application.

[0029] Some medical procedures, such as pulsed field ablation (PFA) and radiofrequency (RF) ablation of tissue in a patient's heart, benefit from sensing the contact force applied to the tissue during ablation. The distal end assembly may include, for example, a basket assembly that includes an ablation electrode coupled to a flexible spline.

[0030] One challenge in using such catheters, especially larger ones that may occupy a significant volume within the heart chambers, is accurately determining the zero-force state—the fully relaxed state of the distal end assembly when it is not in contact with tissue. This is used to calibrate force measurements and ensure accurate force application during the procedure. Conventional methods for zero-force calibration (also referred to herein as zero-force calibration measurements) typically rely on visual confirmation that the catheter appears to be centered within the heart chamber, assuming no contact with tissue. However, with larger catheters, even if the catheter appears to be centered within the heart chamber, it can be difficult to confirm that it is not in contact with the walls in 3D space. Even small deformations can lead to accidental contact, making it difficult to ensure that there is truly no contact force. The relatively large size of nitinol baskets, coupled with the complex geometry of the heart chambers, presents a significant challenge in ensuring the absence of contact during zero-force calibration.

[0031] Furthermore, the force-deformation relationship in these catheters is often highly nonlinear, with the catheter exhibiting the greatest sensitivity to small forces when in its near-canonical state. This sensitivity to small forces increases the complexity of accurately determining the zero-force state based on visual inspection. For example, the zero state may be incorrectly determined during accidental contact associated with small deformations that are not visually apparent.

[0032] The automated method described in this article helps address this complexity in some examples by identifying when the electrodes on the EDEA are in their reference position and activating, enabling, or preventing zero-point force calibration based on the calculated deviation from the reference position. In some examples, this automated assessment capability can help improve the accuracy of zero-point force calibration. Improved zeroing techniques can potentially enhance the overall accuracy of force measurements during procedures, leading to better patient outcomes and more efficient workflows.

[0033] For example, consider basket catheters. Basket catheters are typically made of nitinol strips or any other material with elastomeric properties. Because nitinol is sensitive to temperature and in vivo conditions, the neutral, fully relaxed shape of a nitinol basket may differ from its shape outside the patient's body when positioned within the space of a cardiac chamber.

[0034] Therefore, before estimating the mechanical forces applied to the nitinol basket during the procedure, it is necessary to predetermine the shape of the nitinol basket when no mechanical forces are applied to it by the cardiac tissue. This shape is referred to herein as “zero-point force calibration”.

[0035] Additionally, the system can utilize impedance-based touch proximity index (TPI) and electrocardiogram (ECG) signals to determine when the electrode is in contact with or near the tissue. TPI provides an indication of the electrode's proximity to the tissue, while an ECG signal is detected when the electrode is close to or in contact with the tissue, but may not be detected when the electrode is far from the tissue. By integrating this information, the system can optimally assess when to perform zero-point force calibration, thereby ensuring accurate force measurements during medical procedures.

[0036] In view of the above, it is desirable to provide a catheter-based diagnostic and / or therapeutic system that can automatically obtain zero-point force calibration of the distal end assembly of the catheter and / or guide the user when to initiate zeroing.

[0037] The examples of the invention described below provide techniques for obtaining zero-point force calibration applied between the tissue in question (e.g., tissue of a patient's heart) and the expandable distal end assembly (EDEA) of the catheter prior to ablation or sensing procedures. The disclosed techniques rely on quantifying and utilizing the elastic properties of the deformable components of the distal end assembly.

[0038] In some examples, the system may include a catheter comprising an expandable distal end assembly (EDEA) and a processor having multiple electrodes disposed thereon. The processor may be configured to receive input from a user command to perform zero-point force calibration on the EDEA when it is located in the patient's heart.

[0039] The processor can determine the reference positions of at least some of the electrodes, for example, relative to a reference point. When the EDEA is in vivo, the processor can estimate the actual positions of at least some of the electrodes. The processor can then calculate the deviation between the actual positions and the corresponding reference positions. Based on the calculated deviation, the processor can enable or disable (in other words, allow or revoke) zero-point force calibration commanded by the user.

[0040] The prerequisite is that zero-point force calibration is enabled, and the processor actuates the zero-point force calibration based on a command received from the user. The processor can then calculate the force based on the deviation of the actual position and the output from the zero-point force calibration, and display the calculated force on the electronic display.

[0041] The process of enabling and disabling zero-point force calibration can be repeated within the body. For example, the processor can disable a zero-point force calibration measurement based on a deviation exceeding a deviation threshold, and restart another zero-point force calibration measurement based on a deviation decreasing below the deviation threshold.

[0042] This automated decision-making process can be important because, in some cases, the system may be able to assess the suitability of zero-point force calibration conditions more accurately than a physician.

[0043] In some examples, the processor can disable the use of zero-point force calibration if the calculated deviation exceeds a predetermined threshold. Conversely, the processor can enable the use of zero-point force calibration if the calculated deviation is below the threshold. The threshold can be adjusted based on factors such as the specific procedure being performed or the patient's anatomy.

[0044] Alternatively, the system can find the minimum deviation within a sensing time period. During this period, the processor continuously monitors the deviation between the actual position and the reference position and identifies where the deviation is at its minimum. The measurement with this minimum deviation can then be used for zero-point force calibration.

[0045] The system can provide users with feedback on deviations and, in some cases, allow users to continue zero-point force calibration. This feedback may include visual or auditory cues to guide the user to reposition the EDEA to achieve conditions more suitable for zeroing the force.

[0046] By automating the decision-making process for zero-point force calibration, this system can help ensure more accurate and reliable force measurements in medical procedures. In some cases, this can lead to improved patient outcomes and more efficient workflows.

[0047] In some examples, the catheter includes an EDEA with multiple electrodes disposed thereon. The EDEA is constructed as a basket comprising one or more splines that can deform in response to mechanical forces and return to their original shape when no force is applied. The splines are typically made of shape memory alloys such as nitinol, which have both elastic and ductile properties and are biocompatible.

[0048] In some examples, the electrodes on the EDEA serve multiple purposes. One electrode can be used as a transmitter, while others act as receivers. The transmitter is preferably a single-axis position sensor (TAS). The receiving electrodes are typically single-axis sensors (SAS) oriented with different 3D positioning and orientations, designed to detect signals from the transmitter.

[0049] In some examples, the system includes position sensing capabilities for the electrodes on the EDEA. Position sensing allows determining the actual location of the electrodes within the patient's heart.

[0050] In some examples, the transmitter is positioned on the distal end of the shaft, and the receiver is positioned on the distal end of the EDEA. This configuration allows the transmitter to emit a signal detected by the receiver, enabling the system to accurately determine the position of the electrode and assess the deformation of the EDEA.

[0051] Alternatively, the system can use a Bézier curve-based method. This method may involve sensing the position and location of the uniaxial sensor (SAS) at the distal end of the basket. The system can then use the Bézier curve to determine the shape of each spline, which can then be used to determine the location of each electrode on the spline.

[0052] In some examples, the sensor can be an actual coil or a printed coil.

[0053] In some examples, position sensing can utilize a variety of methods. For instance, the system can employ advanced current positioning (ACL) technology to determine the location of each electrode. This method may involve applying a current and measuring the resulting voltage to calculate the electrode position.

[0054] The system can combine data from both ACL and Bézier curve-based methods to enhance the accuracy of electrode location estimation.

[0055] In some examples, the system can further improve electrode position estimation by using a model of conduit mechanics based on both methods. This approach must consider the constraints imposed by the mechanical properties of the conduit. These constraints may include the elastic and deformation properties of the conduit material, the expected response to applied forces, and the geometry of the spline. By integrating these mechanical constraints, the system can enhance the accuracy of the Bézier curve representation and improve the accuracy of electrode position estimation.

[0056] Position sensing capability enables the system to track the deformation of the EDEA in real time as it interacts with cardiac tissue. This information can be used to calculate the deviation between the actual electrode position and its reference position, which in turn can be used to determine when conditions are suitable for force-zeroing measurements.

[0057] In some examples, the conduit includes a transmitter and an EDEA with one or more receivers, typically implemented using an electrical coil. The transmitter is coupled to the shaft of the conduit or a flushing device. One or more receivers are coupled to corresponding deformable parts of the EDEA. For example, (i) in an EDEA comprising a basket, one or more receivers may be coupled to each spline of the basket.

[0058] One or more receivers are electrically connected to the processor, and a transmitter is electrically connected to the processor or a signal generator controlled by the processor. In some examples, the electrical connection may be implemented (i) using wires or traces running between the proximal and distal ends of the catheter (e.g., between the EDEA and the operating console of the system including the processor), or (ii) wirelessly using wireless devices coupled to the proximal and distal ends of the catheter.

[0059] In some examples, the processor is configured to apply a transmit signal to the transmitter, referred to herein as a first signal, and at least one of the receivers is configured to generate a receive signal in response to receiving the first signal, referred herein as a second signal.

[0060] In some examples, during and prior to zero-point force calibration, the physician inserts the EDEA into the patient's heart, inflates it to the inflated position, positions it in contact with the tissue, and moves the EDEA between several different locations within the heart. For each location of the EDEA in the heart, the processor is configured to estimate, based on input from user commands to perform zero-point force calibration of the EDEA, as it is located within the patient's heart.

[0061] Alternatively, the system can automatically perform zero-point force calibration without user intervention. In this method, as the EDEA moves within the heart, the processor continuously monitors the deviation between the actual position and the reference position. The processor identifies where the deviation is at its minimum and automatically performs zero-point force calibration based on that minimum deviation.

[0062] The processor can estimate the actual positions of at least some of the electrodes and compare them with reference positions of at least some of the electrodes. The processor can then calculate the deviation between the actual positions and the corresponding reference positions. Based on the calculated deviation, the processor can enable or disable zero-point force calibration commanded by the user.

[0063] In some examples, the processor is configured to record the output from the SAS sensor or other deformation sensing sensor throughout the zero-point force calibration process.

[0064] In some examples, if the calculated deviation exceeds a predetermined threshold, the processor may prevent the recording of zero-point force calibration and then enable another zero-point force calibration. Conversely, if the calculated deviation is below the threshold, the processor may enable the recording of zero-point force calibration.

[0065] In some examples, the system / processor can use a display to provide visual or auditory feedback to guide the user to reposition the EDEA to conditions suitable for zero-point force calibration. This feedback may include a real-time indication of the current deviation and suggestions for catheter movement that can reduce that deviation.

[0066] The threshold can be adjusted based on factors such as the specific procedure being performed or the patient's anatomy. In some examples, the processor may provide feedback to the user regarding the deviation and allow the user to decide whether to continue zero-point force calibration. In some examples, the threshold deviation will be predetermined. The user can also manually adjust the threshold. More likely, the system will use the deviation from the reference position, along with the Touch Proximity Index (TPI) and electrocardiogram (ECG) recordings, to find the optimal moment to capture the zero state. In this case, the threshold can serve as a hard stop, meaning that if the deviation exceeds the threshold, it clearly indicates that zero-point force calibration cannot be performed.

[0067] The disclosed technology improves force sensing capabilities. Force sensing can be used to improve the quality of cardiac procedures (e.g., PFA and / or RF ablation and electrophysiological mapping) by increasing the accuracy of sensing the mechanical forces applied between the ablation electrode and the tissue to be ablated during RF ablation procedures and reducing their complexity. The disclosed technology is also applicable, with necessary modifications, to any other medical procedures that require accurate sensing of the mechanical forces between the medical device and the tissue.

[0068] System Description Figure 1 This is a schematic diagram of a catheter-based position-tracking and ablation system 10 according to an example of the present invention.

[0069] System 10 includes one or more catheters that are inserted by a physician 24 through the skin into the chambers or vascular structures of the heart 12 within the patient's vascular system. Typically, a delivery sheath catheter is inserted into the left or right atrium near the desired location within the heart 12. One or more catheters can then be sequentially inserted into the delivery sheath catheter to reach the desired location. The one or more catheters may include catheters specifically for sensing intracardiac electrogram (IEGM) signals, catheters specifically for ablation, and / or catheters specifically for both sensing and ablation. An example basket catheter 14 configured for ablation sensing of IEMM is illustrated herein. As another example, catheter 14 may be a tip catheter for both ablation and sensing, the tip catheter being fitted with a contact force mechanism described in U.S. Patent 8,535,308, which is assigned to the assignee of this application.

[0070] As shown in Illustration 45, the physician 24 brings a basket-shaped catheter 28 (hereinafter also referred to as "expandable distal end assembly 28") mounted on the shaft 44 of catheter 14 into contact with the heart wall to sense a target site in the heart 12. For ablation, the physician 24 similarly brings the distal end of the ablation catheter to the target site for ablation.

[0071] As shown in Figure 65, the basket catheter 14 is an exemplary catheter comprising one, and preferably multiple, electrodes 26 optionally distributed on multiple splines 22 at the expandable distal end assembly 28 and configured to ablate and / or sense IEGM signals. The catheter 14 further includes (i) a proximal position sensor 29 (e.g., a biaxial sensor (DAS) 29 with two orthogonal ECMs or a triaxial sensor (TAS) including three orthogonal ECMs) embedded in the distal end 46 of the axis 44 near the basket catheter 28, and (ii) three distal end position sensors 39 (e.g., a single-axis sensor (SAS) 39 including a single ECM) for tracking the position of the distal end of the basket catheter 28. Optionally and preferably, position sensors 29 and 39 are magnetically based position sensors comprising magnetic coils for sensing three-dimensional (3D) position. An example reference electrode 31 located at the base of assembly 28 is also shown.

[0072] Now return to the reference. Figure 1 A full view. In some examples, during navigation of the distal end assembly 28 within the heart 12, the processor 56 receives signals from magnetic position sensors 29 and 39.

[0073] Position sensing methods using external magnetic fields have been implemented in various medical applications, such as in CARTO, manufactured by Biosense Webster Inc. (Irvine, California). TM The system is implemented and described in detail in U.S. Patents 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, PCT Patent Publication WO 96 / 05768, and U.S. Patent Application Publications 2002 / 0065455 A1, 2003 / 0120150 A1 and 2004 / 0068178 A1, the disclosures of which are all incorporated herein by reference.

[0074] The magnetic position sensors (29, 39) (i.e., coil assemblies) also operate in conjunction with an external positioning pad 25, which includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predetermined workspace. To prevent interference between signals, the frequencies of these fields differ from any given frequency used in the local transmitter-receiver mode for contact force detection. The real-time orientation of the basket conduit 28 of the conduit 14 can be calculated in this way from the tracking position of the sensors 29 and 39 (positioning is tracked using the magnetic field generated by the positioning pad 25 and sensed by the magnetic-based position sensors 29 and 39). This relative orientation is represented by the angle formed between the distal end 46 and the longitudinal axis 42 of the expandable assembly 28 (to the distal edge 16 of the assembly).

[0075] Detailed descriptions of magnetic position sensing technology are found in U.S. Patents 5,5391,199, 5,443,489, 5,558,091, 6,172,499, 6,239,724, 6,332,089, 6,484,118, 6,618,612, 6,690,963, 6,788,967, and 6,892,091.

[0076] System 10 includes one or more electrode patches 38 positioned to contact the skin of patient 23 to establish a position reference for impedance-based tracking of positioning pad 25 and electrodes 26. For impedance-based tracking, current is directed toward electrodes 26 and sensed at the electrode skin patch 38, allowing triangulation of the position of each electrode via the electrode patch 38. Details of the impedance-based positioning tracking technique are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0077] Recorder 11 displays an electrogram 21 captured using surface ECG electrodes 18 and an intracardiac electrogram (IEGM) captured using electrodes 26 using catheter 14. Recorder 11 may include pacing capability for pacing rhythms and / or may be electrically connected to a separate pacemaker.

[0078] System 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes at the distal end of a catheter configured for ablation. The energy generated by the ablation energy generator 50 may include, but is not limited to, radio frequency (RF) energy or pulsed field ablation (PFA) energy (including monopolar or bipolar high-voltage DC pulses that can be used to achieve irreversible electroporation (IRE), or combinations thereof.

[0079] The patient interface unit (PIU) 30 is configured to establish electrical communication between the catheter, electrophysiological equipment, power supply, and workstation 55 for operating the system 10. The electrophysiological equipment of the system 10 may include, for example, multiple catheters, positioning pads 25, surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally and preferably, the PIU 30 further includes real-time calculations for catheter positioning and processing capabilities for performing ECG calculations.

[0080] Workstation 55 includes memory 57, a processor unit 56 with a memory or storage device loaded with appropriate operating software, and user interface capabilities. Workstation 55 may provide multiple functions, optionally including: (i) three-dimensional (3D) modeling of endocardial anatomy and rendering the model or anatomical mapping 20 for display on display device 27; (ii) displaying on display device 27, with representative visual markers or images superimposed on the rendered anatomical mapping 20, activation sequences (or other data) compiled from recorded electrograms 21; (iii) displaying the real-time location and orientation of multiple catheters within the cardiac chambers; and (iv) displaying on display device 27 sites of interest (such as areas where ablation energy has been applied). An item embodying elements of system 10 is also available, capable of using CARTO... TM The system was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0081] Although Figure 1 The basket assembly is described, but the figures and methods disclosed are adapted with the necessary changes to the multi-ray assembly and the balloon assembly.

[0082] This particular configuration of system 10 is illustrated by way of example to illustrate certain problems solved by examples of the invention and to demonstrate the application of these examples in enhancing the performance of such systems. However, the examples of the invention are by no means limited to this particular category of example systems, and the principles described herein can be similarly applied to other categories of medical systems and procedures.

[0083] Distal end assembly and force zeroing measurement Figure 2 A schematic illustration of an expandable distal end assembly (EDEA) 28 in an expanded position in one of three exemplary locations 60A, 60B and 60C inside the heart 12 according to an example of the present invention.

[0084] When the distal end assembly 28 is located within the center 60A of the heart 12, the tissue 47 of the heart 12 does not exert mechanical force on the distal end assembly 28 and thus maintains a neutral shape, making it suitable for zero-point force calibration.

[0085] When the distal end assembly 28 is located near and in contact with the tissue at location 60B of the heart 12, the tissue 47 applies a small mechanical force to the distal end assembly 28. However, the mechanical force is below a specific threshold of about 1 gram required to deform the distal end assembly 28 into a neutral shape.

[0086] Finally, when the distal end assembly 28 is positioned to contact the tissue 47 at location 60C of the heart 12, a non-negligible mechanical force is applied to the distal end assembly 28. The mechanical force exceeds a specific threshold required to deform the neutral shape of the distal end assembly 28.

[0087] As can be understood, of the three locations 60A, 60B, and 60C, the measurement performed at location 60A is the most suitable for use as a zero-point force calibration measurement. In some examples, the processor 56 identifies this measurement and saves it for later use.

[0088] Figure 2 The illustration on the right shows the structure of the distal end assembly 28 in more detail. In this example, the distal end assembly 28 is a basket-shaped assembly comprising a plurality of splines 22.

[0089] In some examples, one or more ablation electrodes 26 are coupled to each spline 22 and configured to apply an ablation pulse to the tissue of the heart 12. The ablation pulse is designed to kill the cells of the tissue in question and create a lesion rather than tissue that prevents or reduces the propagation of electrophysiological (EP) waves through the ablated tissue.

[0090] In some examples, one or more ablation electrodes 26 are also used to sense the impedance of the TPI and sense the ECG signal for mapping purposes. This dual function of the electrodes enhances the system's ability to accurately determine the proximity and contact state of the electrodes to the tissue, thereby improving the accuracy of both the ablation and mapping procedures.

[0091] In some examples, the distal end assembly 28 includes a plurality of electrodes (26) comprising a transmitter 88 and one or more receivers 99. The transmitter 88 is coupled to a rigid component of the distal end assembly 28. In other examples, the transmitter 88 may be coupled to any other suitable rigid component of the distal end assembly 28, such as the shaft 44. In the context of this disclosure and the claims, the term “rigid” refers to a component of the conduit 14 that moves with the conduit and whose positioning is unaffected by any forces (such as contact forces) applied to the distal end assembly 28, as will be described in detail below. In other words, the transmitter 88 has the same angular velocity and the same angular acceleration as the distal end of the shaft 44.

[0092] In some examples, one or more receivers 99 are coupled to corresponding resilient members of the distal end assembly 28. In this example, one receiver 99 is coupled to each spline 22 of the basket. Note that in Figure 2 In the example, only three receivers 99 are shown, but the receivers 99 are coupled to each spline 22, even though some of the receivers 99 are hidden by the isometric perspective view of the distal end assembly 28 and therefore not shown in the image. Figure 2 The example configuration is shown in the example configuration.

[0093] In some examples, transmitter 88 and receiver 99 can be implemented using electrical coils respectively connected to spline 22. The coils of transmitter 88 and receiver 99 are electrically connected to processor 56 using any suitable connection technology.

[0094] In some examples, receiver 99 is electrically connected (e.g., via traces on the aforementioned flexible PCB and via conduit 14) to processor 56. Additionally, transmitter 88 is electrically connected to processor 56 (e.g., via a wire extending between the distal end of (i) shaft 44 or the proximal end of flusher 60 and (ii) conduit 14). Alternatively or additionally, transmitter 88 may be electrically connected to a pulse generator (not shown), controlled by processor 56 and configured to apply one or more pulses using transmitter 88, as described below.

[0095] In other examples, wireless devices (not shown) coupled to the proximal and distal ends of the conduit 14 may be used to implement the electrical connection between (i) the transmitter 88 and / or the receiver 99 and (ii) the processor 56.

[0096] In some examples, processor 56 is configured to control transmitter 88 to apply a transmit signal, also referred to herein as a first signal. In response to receiving the first signal, at least one, and typically all, receivers 99 are configured to generate a receive signal, also referred to herein as a second signal.

[0097] In some examples, a second signal generated by a given receiver 99 indicates the distance between the transmitter 88 and the given receiver 99, as will be described below.

[0098] In some examples, during the zero-force calibration procedure and prior to the ablation procedure, physician 24 inserts the distal end assembly 28 into the cavity of heart 12. Subsequently, physician 24 inflates the distal end assembly 28 to the inflated position (e.g., Figure 2 As shown in the example, press the zeroing button and manipulate the distal end assembly 28 within the heart 12 to perform the zero-point force calibration procedure.

[0099] In some examples, during the zero-point force calibration procedure, the physician 24 moves the EDEA 28 to multiple locations within the heart 12, such as locations 60A, 60B, and 60C. As stated above, the zero-point force calibration measurement performed at location 60A is the most suitable measurement for use as a zero-point force calibration measurement.

[0100] In some examples, at the end of the zero-point force calibration procedure, the physician 24 presses the zero button to mark the end of the zero-point force calibration procedure.

[0101] In some examples, during the zero-point force calibration procedure, processor 56 is configured to control transmitter 88 to apply a transmission signal until physician 24 ends the zeroing procedure.

[0102] In some examples, processor 56 is configured to estimate the mechanical force applied to the spline with a typical sensitivity of about 5 grams (also referred to herein as gram force (GF)), while typical values ​​of mechanical forces applied in such procedures range from about 0 grams to 100 grams.

[0103] Therefore, the disclosed technique improves the quality of the ablation procedure by increasing the accuracy of the estimated mechanical force applied between the ablation electrode 26 and the heart 12, which is intended to be ablated during the aforementioned RF ablation procedure. The disclosed technique, with necessary modifications, is also applicable to any other medical procedure requiring accurate and stable sensing of the mechanical force between the medical device and the tissue.

[0104] By giving examples Figure 2 The present invention provides a configuration of the distal end assembly 28 to illustrate certain problems addressed by examples of the invention and to demonstrate the application of these examples in enhancing the performance of such distal ends for treating cardiac arrhythmias in patients. However, the examples of the invention are by no means limited to this particular category of exemplary distal end assemblies, and the principles described herein can be similarly applied to other classes of catheters used in any suitable class of medical systems and procedures that require measuring or estimating the mechanical forces applied between any suitable type of medical device and any suitable tissue of the patient.

[0105] Figure 3 The flowchart illustrates, according to an example of the present invention, a method for estimating zero-point force calibration measurements of the distal end assembly 28 within the tissue of the heart 12.

[0106] The method begins with catheter pre-insertion step 100, where the position of each electrode in the reference configuration is uploaded to processor 56 during calibration before the catheter is inserted into the body.

[0107] At the sensing position step 102, the processor 56 calculates the actual position of each electrode inside the heart.

[0108] Subsequently, at the position error calculation step 104, the processor 56 calculates the root mean square error (RMSE) between the preloaded reference position and the corresponding actual position of the electrode.

[0109] In the optimization step (not shown in the flowchart), the system is configured to optimize the zero-point force calibration measurement by identifying the optimal zeroing time within a threshold. This optimization is based on a cost function that considers multiple factors, including minimum RMSE, minimum TPI, and minimum ECG gain.

[0110] At decision point step 106, processor 56 compares the calculated RMSE with a predetermined threshold.

[0111] If the RMSE is greater than the threshold ("Yes" branch), the process moves to step 108 where the zero-point force calibration option is disabled.

[0112] In step 108, any zero-point force calibration measurements commanded by the user are disabled. The method loops back to repeat steps 102-106.

[0113] If the RMSE is not greater than the threshold ("No" branch), the process moves to step 110, where the zero-point force calibration option is enabled.

[0114] In step 110, the zero-point force calibration measurement is recorded and used in the subsequent deformation measurement step 112 to estimate the mechanical forces exerted on the deformable component by the heart wall tissue in subsequent deformation measurements (e.g., during an ablation procedure).

[0115] Figure 3 The procedure described here is an example and is for clarity only. Any other suitable procedure may be used in alternative examples. For example, in some examples, the processor monitors impedance and / or intracardiac electrogram (ICEG) at each of multiple electrodes and enables or disables zero-point force calibration measurements based on predefined criteria defined for impedance and / or ICEG and based on a comparison of deviation with a deviation threshold.

[0116] In some examples, the deviation threshold is dynamically updated based on the deviation calculated over a defined time period. In other examples, the deviation threshold is user-defined.

[0117] In one example, the command to initiate zero-point force calibration is based on user input requesting zero-point force calibration. In another example, the command is executed automatically based on the processor recognizing predefined events.

[0118] In one example, the processor renders a virtual representation of EDEA and updates the shape of the virtual representation based on the monitored actual positions of multiple electrodes.

[0119] In another example, the EDEA takes the form of a basket comprising multiple deformable splines, and the actual positions of the multiple electrodes are determined based on a mechanical model of the EDEA and outputs from multiple magnetically based position sensors mounted on the deformable splines. Typically, the reference configuration of the EDEA is predetermined in vitro during the calibration procedure.

[0120] While the examples described herein primarily address the estimation of force-zeroing measurements of the expandable distal end assembly of the RF ablation catheter and the tissue to be ablated, the methods and systems described herein can also be used in other applications, such as those requiring accurate measurement of the contact forces applied between any suitable medical device and any suitable tissue of a patient's organ. For example, in organs of a patient's ear, nose, and throat (ENT) system. Example

[0121] Example 1 : A system includes a catheter, a processor, and an electronic display. The catheter includes an expandable distal end assembly (EDEA) comprising a plurality of electrodes disposed thereon. The processor is configured to store reference positions of the plurality of electrodes of the catheter relative to the reference point in memory, monitor the actual positions of the plurality of electrodes while the EDEA is in vivo, and enable or disable zero-point force calibration based on a comparison of the deviation of the actual positions from the reference positions with a deviation threshold. The processor is further configured to: actuate the zero-point force calibration upon receiving a command, provided that the zero-point force calibration is enabled; and calculate a force based on the deviation of the actual positions and the output from the zero-point force calibration. The electronic display is configured to display the calculated force.

[0122] Example 2 : According to the system of Embodiment 1, the processor is configured to disable the zero-point force calibration measurement based on the deviation exceeding the deviation threshold, and to restart another zero-point force calibration measurement based on the deviation decreasing below the deviation threshold.

[0123] Example 3 : According to the system of Embodiment 1, the processor is configured to monitor one or both of impedance and intracardiac electrogram (ICEG) at each of the plurality of electrodes, and to enable or disable the zero-point force calibration measurement based on a predefined criterion defined for one or both of impedance and ICEG and based on the comparison of the deviation with the deviation threshold.

[0124] Example 4 : According to the system of Embodiment 1, the deviation threshold is dynamically updated based on the deviation calculated within a defined time period.

[0125] Example 5 : According to the system described in Embodiment 1, the deviation threshold is user-defined.

[0126] Example 6 : According to the system described in Embodiment 1, the command is based on user input requesting the zero-point force calibration.

[0127] Example 7 : According to the system described in Embodiment 1, the command is performed automatically based on the processor recognizing predefined events.

[0128] Example 8 : According to the system of Embodiment 1, the processor is configured to render a virtual representation of the EDEA and update the shape of the virtual representation based on the actual positions of the monitored plurality of electrodes.

[0129] Example 9 : According to the system of Embodiment 1, the EDEA is in the form of a basket comprising a plurality of deformable splines, and the actual positions of the plurality of electrodes are determined based on a mechanical model of the EDEA and outputs from a plurality of magnetically based position sensors mounted on the deformable splines.

[0130] Example 10 : According to the system described in Example 1, the reference configuration of the EDEA is predetermined in vitro during the calibration procedure.

[0131] Example 11 : A method includes storing in memory the reference positions of a plurality of electrodes relative to a reference point, the electrodes being disposed on an expandable distal end assembly (EDEA) of a catheter. The actual positions of the plurality of electrodes are monitored while the EDEA is in vivo. Zero-point force calibration is enabled or disabled based on a comparison of the deviation of the actual positions from the reference positions to a deviation threshold. This is predicated on the zero-point force calibration being enabled, actuated based on a received command. A force is calculated based on the deviation of the actual positions and the output from the zero-point force calibration. The calculated force is displayed.

[0132] Therefore, it should be understood that the above embodiments are cited by way of example, and the invention is not limited to what has been specifically shown and described above. Rather, the scope of the invention includes combinations and sub-combinations of the various features described above, as well as variations and modifications thereof, which will occur to those skilled in the art upon reading the above description, and which are not disclosed in the prior art. Documents incorporated herein by reference are considered an integral part of this application, and unless any terminology defined in such incorporated documents conflicts with the definitions expressly or implicitly given in this specification, only the definitions in this specification shall be considered.

Claims

1. A system comprising: The catheter includes an expandable distal end assembly (EDEA) comprising a plurality of electrodes disposed thereon; as well as The processor is configured as follows: The reference positions of the plurality of electrodes of the catheter relative to a reference point are stored in the memory; The actual location of the plurality of electrodes is monitored when the EDEA is in vivo; Zero-point force calibration is enabled or disabled by comparing the deviation between the actual position and the reference position with a deviation threshold. If the zero-point force calibration is enabled, the zero-point force calibration is actuated based on the received command; The force is calculated based on the deviation of the actual position and the output from the zero-point force calibration; as well as An electronic display configured to display the calculated force.

2. The system according to claim 1, wherein, The processor is configured to disable the zero-point force calibration measurement based on the deviation exceeding the deviation threshold, and to restart another zero-point force calibration measurement based on the deviation decreasing below the deviation threshold.

3. The system according to claim 1, wherein, The processor is configured to monitor one or both of impedance and intracardiac electrogram (ICEG) at each of the plurality of electrodes, and to enable or disable the zero-point force calibration measurement based on a predefined criterion defined for one or both of impedance and ICEG and based on the comparison of the deviation with the deviation threshold.

4. The system according to any one of claims 1-3, wherein, The deviation threshold is dynamically updated based on the deviation calculated within a defined time period.

5. The system according to any one of claims 1-3, wherein, The deviation threshold is user-defined.

6. The system according to any one of claims 1-3, wherein, The command is based on user input requesting the zero-point force calibration.

7. The system according to any one of claims 1-3, wherein, The command is executed automatically based on the processor recognizing predefined events.

8. The system according to any one of claims 1-3, wherein, The processor is configured to render a virtual representation of the EDEA and update the shape of the virtual representation based on the actual positions of the monitored plurality of electrodes.

9. The system according to any one of claims 1-3, wherein, The EDEA is in the form of a basket comprising multiple deformable splines, and the actual positions of the multiple electrodes are determined based on a mechanical model of the EDEA and outputs from multiple magnetically based position sensors mounted on the deformable splines.

10. The system according to any one of claims 1-3, wherein, The baseline configuration of the EDEA is predetermined in vitro during the calibration procedure.

11. A method comprising: The reference positions of multiple electrodes relative to a reference point are stored in the memory; the multiple electrodes are disposed on the expandable distal end assembly (EDEA) of the catheter. The actual location of the plurality of electrodes is monitored when the EDEA is in vivo; Zero-point force calibration is enabled or disabled by comparing the deviation between the actual position and the reference position with a deviation threshold. If the zero-point force calibration is enabled, the zero-point force calibration is actuated based on the received command; The force is calculated based on the deviation of the actual position and the output from the zero-point force calibration; as well as Displays the calculated force.

12. The method according to claim 11, wherein, Enabling or disabling the zero-point force calibration includes: disabling the zero-point force calibration measurement based on the deviation exceeding the deviation threshold, and restarting another zero-point force calibration measurement based on the deviation decreasing below the deviation threshold.

13. The method according to claim 11, wherein, Enabling or disabling the zero-point force calibration includes: monitoring one or both of impedance and intracardiac electrogram (ICEG) at each of the plurality of electrodes, and enabling or disabling the zero-point force calibration measurement based on a predefined criterion defined for one or both of impedance and ICEG and based on the comparison of the deviation with the deviation threshold.

14. The method according to any one of claims 11-13, further comprising dynamically updating the deviation threshold based on the deviation calculated over a defined time period.

15. The method according to any one of claims 11-13, wherein, The deviation threshold is user-defined.

16. The method according to any one of claims 11-13, wherein, The command is based on user input requesting the zero-point force calibration.

17. The method according to any one of claims 11-13, wherein, The command is executed automatically based on the recognition of predefined events.

18. The method of any one of claims 11-13, further comprising rendering a virtual representation of the EDEA and updating the shape of the virtual representation based on the actual positions of the monitored plurality of electrodes.

19. The method according to any one of claims 11-13, wherein, The EDEA is in the form of a basket comprising multiple deformable splines, and the actual positions of the multiple electrodes are determined based on a mechanical model of the EDEA and outputs from multiple magnetically based position sensors mounted on the deformable splines.

20. The method according to any one of claims 11-13, wherein, The baseline configuration of the EDEA is predetermined in vitro during the calibration procedure.

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