Catheter contact force estimation during ablation

Abstract

In one example, a device includes: an ablation energy generator for transmitting ablation energy to electrodes of a catheter; a processor configured to: calculate a first force signal acting on tissue by the distal end assembly based on a first magnetic signal received from a magnetic emitter coil at the distal end of the catheter by a first magnetic field sensor of the distal end assembly during tissue ablation by the electrodes; calculate a second force signal acting on tissue by the distal end assembly based on a second magnetic signal received from a magnetic emitter coil disposed in a positioning pad by a second magnetic field sensor of the distal end assembly; calculate a third force signal based on the first and second force signals; and render the force value or ablation index value calculated based on the third force signal to a display.

Description

Technical Field

[0001] This disclosure relates to medical systems including catheters, and specifically, but not exclusively, to catheter contact force estimation. Background Technology

[0002] Many medical procedures involve inserting probes, such as catheters, into a patient's body. One medical procedure in which these types of probes or catheters have proven to be very useful is the treatment of cardiac arrhythmias. Cardiac arrhythmias, especially atrial fibrillation, have been a common and dangerous medical condition, particularly among the elderly.

[0003] The diagnosis and treatment of cardiac arrhythmias involve mapping the electrical properties of cardiac tissue, particularly the endocardium and cardiac volume, and selectively ablating cardiac tissue by applying energy. In such procedures, catheters are inserted into and optionally around the heart chambers. In most procedures, multiple catheters are inserted into the patient. Catheters may include mapping catheters, ablation catheters, temperature-sensing catheters, and image-sensing catheters. Some catheters are specifically designed for placement in particular anatomical structures, such as the coronary sinus, esophagus, atria, and ventricles. Catheters have multiple electrical channels; some catheters have more channels than others, depending on the number of sensors and electrodes included in each catheter. The number and type of catheters depend on the procedure and the physician's preferred workflow. Attached Figure Description

[0004] This disclosure will be understood in conjunction with the following detailed description and the accompanying drawings, in which: Figure 1 This is a simplified illustration of a catheter-based electrophysiological mapping and ablation system constructed and operated according to examples of this disclosure; Figure 2 It shows the sensing from the source used for Figure 1 A schematic diagram of magnetic signals from axis-based magnetic coils in the system; Figure 3 It shows the sensing from the source used for Figure 1 A schematic diagram of the magnetic signal of the positioning pad magnetic coil in the system; Figure 4 It includes Figure 1 A flowchart of the steps in the system's operation method; Figure 5 This is a schematic diagram of a Kalman filter combining the first and second force signals into a third force signal; and Figure 6 This is a schematic diagram of a display showing electroanatomical mapping and various related values. Detailed Implementation

[0005] Overview During electroanatomical mapping and ablation, it is important that the physician positions the catheter to ensure adequate contact between the relevant electrodes and the cardiac tissue, applying sufficient pressure to the tissue. This is especially important during ablation, as the force applied to the tissue by the electrodes should exceed a given limit to achieve successful ablation.

[0006] Force can be measured using one or more force sensors embedded in the catheter. When the catheter is a lesion catheter, force sensors provide an acceptable solution, but when the catheter includes multiple electrodes on a deformable distal end assembly (e.g., basket or balloon shape), force sensors may not provide an optimal solution and / or may be difficult to implement.

[0007] One method for determining the force applied by the electrodes is based on estimating the magnetic field generated by a magnetic coil in the distal end of the catheter's shaft. The magnetic field is sensed by a magnetic sensor positioned on the distal end assembly. During calibration, different measuring forces are applied to the catheter, and the magnetic field sensed at each magnetic sensor is measured, thereby creating a mapping between the sensed magnetic field and the force. The mapping can then be used to locate the force applied by the electrodes based on the magnetic field sensed by the magnetic sensor.

[0008] However, during ablation, especially with short pulses of very high ablation energy (e.g., pulsed field ablation (PFA)), the ablation signal generates a lot of noise at the magnetic transmission coil because the wires used for ablation extend through or near the magnetic transmission coil and interfere with it, causing the magnetic transmission coil to generate frequencies that it was not designed to generate.

[0009] Therefore, using a magnetic transmission coil to provide a magnetic signal during ablation may lead to inaccuracies in calculating the position of the sensor (or other element) and / or the shape of the distal end assembly, as well as the force applied to the tissue by the electrodes of the distal end assembly.

[0010] Because the distal end assembly possesses elastic properties, another method for determining the force applied by the electrodes can be estimated based on the deformation shape of the distal end assembly using a predefined linear or nonlinear elastic model, since the deformation of the distal end assembly is caused by the forces exerted on it by the surrounding tissue. Different deformation shapes of the distal end assembly can be calibrated based on the measured forces. The distal end assembly can deform in various ways, and the resulting forces can be measured, thus providing a calibration between different deformation shapes of the distal end assembly and the resulting forces. Alternatively, the forces for different deformation shapes of the distal end assembly can be calculated based on a model of the distal end assembly and the structural properties of the materials used to form the distal end assembly.

[0011] During in vivo use of the catheter, deformation of the distal end assembly can be tracked based on the location of one or more magnetic field sensors (e.g., on the distal end assembly (such as on a spline of a basket catheter) and in the distal end of the catheter's axis). The associated forces can be determined as deformation of the distal end assembly using any suitable method (such as the mapping described above).

[0012] The position of a magnetic field sensor can be calculated based on magnetic signals emitted from a magnetic transmitter coil disposed externally in a positioning pad around the patient's body (e.g., around the chest). Because of the large distance from the positioning pad to the distal end of the catheter, the positioning pad method is unaffected by noise caused by ablation. However, due to the relatively large distance between the positioning pad and the magnetic field sensor, the force calculated based on the deformation of the distal end assembly is generally determined with lower accuracy compared to the aforementioned method based on sensing the magnetic field from an transmitter in the catheter's axis.

[0013] Therefore, the exemplary mode of this disclosure addresses the aforementioned drawbacks by calculating force signals based on the two methods described above, particularly when ablation is being performed. Magnetic signals sensed from a magnetic emitter coil disposed in the distal end of the catheter are used to calculate a time-varying force signal (referred to as the first force signal). Magnetic signals from a magnetic emitter coil disposed in a positioning pad are used to calculate the position of a magnetic field sensor (or other element), the deformation of the distal end assembly over time is calculated based on the calculated position of the magnetic field sensor, and the time-varying force signal (referred to as the second force signal) is calculated based on this deformation. For example, by combining information from the first and second force signals, a third force signal is calculated based on the first and second force signals to better estimate the force applied to the cardiac tissue by one or more electrodes in the electrodes.

[0014] When ablation energy is not delivered, for example during idle mode, the system typically uses a first force signal instead of a second force signal, for example to calculate the ablation index or force to be displayed for physician viewing.

[0015] In some examples, the Kalman filter receives a first force signal and a second force signal as input, and combines the information from the first and second force signals to generate a third force signal. The Kalman filter provides a mathematically optimal estimate of the force signal by selecting between an accurate but unreliable value and a reliable but inaccurate value.

[0016] In some examples, a trainable neural network can be trained to find a third force signal from a first force signal and a second force signal based on training the network using the force value when ablation is not performed.

[0017] In some examples, the force value from the third force signal can be displayed for physicians to view during ablation. The third force signal can also be used with other suitable values ​​(e.g., ablation power and, optionally, the number of ablation pulses) to calculate one or more ablation index values ​​based on real-time force sensing during ablation at different corresponding ablation sites in, for example, cardiac tissue. In some examples, the calculated ablation index values ​​can be recorded and associated with corresponding ablation sites in an electroanatomical mapping for selective display.

[0018] System Description See now Figure 1 This is a schematic illustration of a catheter-based electroanatomical (EA) mapping and ablation system 10 according to an example of this disclosure. System 10 includes one or more catheters inserted by a physician 24 through the skin into a patient's vascular system or into a chamber or vascular structure of the heart 12. Typically, a delivery sheath catheter is inserted into the left or right atrium near a desired location in the heart 12. One or more catheters may then be sequentially inserted into the delivery sheath catheter to reach the desired location. The one or more catheters may include catheters dedicated to sensing intracardiac electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters dedicated to both sensing and ablation. An exemplary basket catheter 14 configured for sensing IEGM is shown herein. As shown in illustration 45, the physician 24 contacts a basket-type expandable distal end assembly 28 (hereinafter also referred to as "expandable distal end assembly 28") mounted on the axis 44 of catheter 14 against 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.

[0019] As shown in Figure 65, the conduit 14 is an exemplary conduit including one, and preferably multiple, electrodes 26 optionally distributed on multiple splines 22 at the scalable distal end assembly 28 and configured to sense IEGM signals. The conduit 14 further includes (i) a proximal magnetic field sensor 29 (e.g., a biaxial sensor (DAS) including two electromagnetic coils (ECMs) or a triaxial sensor (TAS) 29 including three ECMs) embedded in the distal end 46 of the shaft 44 near the scalable distal end assembly 28, and (ii) two distal magnetic field sensors 39 (e.g., a single-axis sensor (SAS) 39 including a single ECM) for tracking the position of the distal end of the scalable distal end assembly 28. Optionally and preferably, the magnetic field sensors 29 and 39 are magnetic field sensors including magnetic coils for sensing three-dimensional (3D) position.

[0020] 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 electrode 26.

[0021] 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.

[0022] 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.

[0023] The patient interface unit (PIU) 30 is a controller with processing capabilities configured to establish electrical communication between the catheters, 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 has processing capabilities for real-time calculation of catheter position and for performing ECG calculations.

[0024] 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 position and orientation of multiple catheters within the cardiac chambers; and (iv) displaying on display device 27 the site of interest (such as where ablation energy has been applied). An example of an element embodying system 10 could be CARTO. ™ The system was purchased from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

[0025] Two alternative methods for calculating forces on duct scalable components See now Figure 2 It shows the sensing from the source used for Figure 1 A schematic diagram of the magnetic signal 71 of the magnetic transmitter coil 69 in system 10. In some examples, the axis-based magnetic coil 29 (e.g., TAS) can transmit the magnetic signal 71. A more accurate method for estimating the force applied by the distal end extendable component 28 includes the magnetic transmitter coil 69 emitting the magnetic signal 71 for detection by the magnetic field sensor 39. Figure 2 Three magnetic field sensors 39 are shown, such as single-axis sensors (SAS), including SAS1 39-1, SAS2 39-2, and SAS3 39-3. SAS1 39-1 receives signal S1, SAS2 39-2 receives signal S2, and SAS3 39-3 receives signal S3. The signals 71 sensed by the magnetic field sensors 39 (e.g., S1 sensed by SAS1 39-1, S2 sensed by SAS2, and S3 sensed by SAS3 39-3) are received by PIU 30, as shown. Figure 2 As shown. Magnetic signals 71 (S1-S3) are processed by PIU 30 and analyzed by processor unit 56 to determine the amount applied to tissue 47 by the distal end extendable component 28. Figure 1 ) force.

[0026] See now Figure 3 It shows the sensing from the source used for Figure 1 A schematic diagram of the magnetic signal 73 of the positioning pad magnetic coil 32 in the system. A less accurate method for estimating the force applied to tissue 47 by the distal end extendable component 28 but less affected by noise during ablation involves determining the force from the deformation (i.e., shape) of the distal end extendable component 28 based on the position of the magnetic field sensor 39 and the electromagnetic coil 29, which transmits the magnetic signal 73 for detection by the magnetic field sensor 39 and the electromagnetic coil 29, according to the magnetic field generated by the magnetic coil 32 of the positioning pad 25. The signal 73 sensed by the magnetic field sensor 39 and the electromagnetic coil 29 is received by the PIU 30, as... Figure 3 As shown. SAS1 39-1 receives signal S4, SAS2 39-2 receives signal S5, SAS3 39-3 receives signal S6, and TAS receives signal S7 from magnetic coil 32. Magnetic signals 73 (S4-S7) are processed by PIU 30 and analyzed by processor unit 56 to calculate the positions of magnetic field sensor 39 and electromagnetic coil 29, and determine the deformation (i.e., shape) of distal end extendable component 28 based on the calculated positions. Processor unit 56 then derives the force applied to tissue 47 by distal end extendable component 28 based on the determined deformation or shape.

[0027] 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.

[0028] The shrinkage amount D of the expandable distal end assembly can be calculated based on the positions of sensors 29 and 30. L And based on the known (e.g., measured) spring constant K of the scalable distal end assembly 28 L According to F C =K L ·D L Estimate contact force F C .

[0029] The expandable distal end assembly 28 can tilt or bend by an angle β from its zero-angle orientation. This is based on a known (e.g., measured) spring constant K of the expandable distal end assembly 28. A The measured or predicted distance L between sensors 29 and 30 can be determined based on F. A =K A ·L· β estimates the contact force F A .

[0030] When the simple spring model used for shrinking and tilting of scalable distal end-components is limited (e.g., for some types of scalable distal end-components), the processor can use a more complex elastic model (e.g., based on a set of springs) for deformation of the scalable distal end-component.

[0031] Additionally or alternatively, the processor can use empirical data to estimate the contact force, which includes calibrations for forces acting on tilting and / or deformation of the scalable distal end assembly. The processor can use weights to interpolate between the calibration values. In this case, the system's memory is configured to store the relationship between the EMC output and the contact force based on the empirical data. The processor is configured to use the stored empirical data to correlate the EMC output with the contact force.

[0032] Combining force values ​​from different methods used to calculate the forces of the catheter expansion components Now for reference Figure 4 It includes Figure 1 The flowchart 400 shows the steps in the operation method of system 10. The ablation energy generator 50 is configured to conduct ablation energy to a given electrode in electrode 26 of catheter 14 (box 402). The processor unit 56 is configured to detect when the ablation energy generator 50 delivers ablation energy.

[0033] Magnetic field sensor 39 is configured to receive a first magnetic signal 71 from magnetic emitter coil 69 and a second magnetic signal 73 from magnetic emitter coil 32 disposed in positioning pad 25 (box 404). Magnetic field sensor 29 is configured to receive the second magnetic signal 73 from magnetic emitter coil 32 disposed in positioning pad 25. In some examples, the first magnetic signal 71 and the second magnetic signal 73 are simultaneously received by the same magnetic field sensor 39 during tissue ablation by a given electrode in electrode 26. The term "simultaneously" may include a gap of up to 300 milliseconds between the pulses receiving the first and second magnetic signals, such as in the range of 10 to 100 milliseconds or 50 to 150 milliseconds. In some examples, different magnetic-based position sensors 39 may be configured to receive the first magnetic signal 71 and the second magnetic signal 73.

[0034] The received magnetic signal 71 can be processed by the PIU 30 and provided to the processor unit 56 to calculate the first force signal 502. Figure 5 ), as described in more detail below.

[0035] The received magnetic signal 73 can be processed by PIU 30 and provided to processor unit 56 to calculate the position of magnetic field sensors 29, 39 of the received signal 73, and to calculate the corresponding shape (e.g., distorted shape or distortion) of the distal end assembly 28 over time based on the calculated position of the magnetic field sensors 29, 39. The calculated distortion (i.e., shape) of the distal end assembly 28 can be used to calculate the second force signal 504 ( Figure 5 ), as described in more detail below.

[0036] The processor unit 56 is configured to calculate a first force signal 502 (box 406) acting on the tissue 47 by the distal end assembly of the catheter 14 based on a first magnetic signal 71 received by the first magnetic field sensor 39 of the distal end assembly 28 of the catheter 14 from the magnetic transmitter coil 69 of the distal end assembly 28 of the catheter 14 during the ablation of tissue 47 by the given electrode 26.

[0037] The processor unit 56 is configured to calculate a second force signal 504 (box 408) acting on the tissue 47 by the distal end assembly of the catheter 14 based on a second magnetic signal 73 received by the second magnetic field sensors 29, 39 of the distal end assembly 28 from the magnetic emitter coil 32 disposed in the positioning pad 25. The positioning pad 25 is configured to be disposed outside the body during ablation of the tissue 47 by the given electrode 26.

[0038] See now Figure 5 This is a schematic diagram showing how the Kalman filter 500 combines the first force signal 502 and the second force signal 504 into a third force signal 506. See also... Figure 1Processor unit 56 is configured to calculate a third force signal 506 based on a first force signal 502 and a second force signal 504 (box 410). In some examples, processor unit 56 is configured to use a Kalman filter 500 to combine the first force signal 502 and the second force signal 504 to generate the third force signal (box 412). In some examples, processor unit 56 is configured to use a Kalman filter 500 to combine the first force signal 502 and the second force signal 504 to generate the third force signal 506 as the best state estimate of the force value over time (which is mathematically optimal, as defined by the Kalman filter).

[0039] See now Figure 6 This is a schematic diagram of a display device 27 showing an electroanatomical mapping map 600 and various related values. See also: Figure 1 In some examples, processor unit 56 is configured to calculate an ablation index value 602 based on a third force signal 506, which estimates the force sensed in real time during ablation at the corresponding ablation site 604 (box 414). The calculated ablation index value provides an indication of the ablation quality at the corresponding ablation site 604. In some examples, processor unit 56 is configured to calculate the ablation index value 602 based on: the third force signal 506 calculated for the corresponding ablation site 604; and the ablation power used at the corresponding ablation site 604, and optionally the number of pulses, the duration of the pulses, etc. In some examples, processor unit 56 is configured to calculate the ablation index value based on the third force signal during ablation and to calculate other ablation index values ​​based on a first force signal during non-ablation periods.

[0040] In some examples, processor unit 56 is configured to record a calculated ablation index value 602 associated with a corresponding ablation site 604 (box 416). In some examples, processor unit 56 is configured to render to display device 27 one or more force values ​​606 (only one shown) or ablation index values ​​602 calculated based on a third force signal 506. In some examples, processor unit 56 is configured to render to display device 27 an electroanatomical mapping 600 including an indication of the calculated ablation index value 602 associated with a corresponding ablation site 604 (box 418).

[0041] In some examples, processor unit 56 is configured to render to a display: a force value 606 or an ablation index value 602 calculated based on a third force signal 506 during the period when ablation energy is being conducted to catheter 14; and another force value 606 or another ablation index value 602 calculated based on a first force signal 502 during the period when ablation energy is not being conducted to catheter 14.

[0042] In practice, some or all of the functions of processor 56 may be combined in a single physical component, or alternatively, implemented using multiple physical components. These physical components may include hardwired or programmable devices, or a combination of both. In some examples, at least some of the functions of processor unit 56 may be implemented by a programmable processor under the control of suitable software. This software may be downloaded to the device electronically via, for example, a network. Alternatively or additionally, the software may be stored in a tangible, non-transitory computer-readable storage medium, such as optical, magnetic, or electronic memory.

[0043] As used herein, the term “about” or “approximately” for any numerical value or range indicates appropriate dimensional tolerances that allow a collection of parts or components to achieve the intended purpose as described herein. More specifically, “about” or “approximately” may refer to a range of ±20% of the enumerated value; for example, “about 90%” may refer to a range of values ​​from 72% to 108%. Example

[0044] Example 1: An apparatus comprising: an ablation energy generator configured to conduct ablation energy to an electrode of a catheter; a processor configured to: calculate a first force signal acting on the tissue by the distal end assembly of the catheter based on a first magnetic signal received by a first magnetic field sensor of the distal end assembly of the catheter from a magnetic emitter coil at the distal end of the catheter during tissue ablation by the electrode; calculate a second force signal acting on the tissue by the distal end assembly of the catheter based on a second magnetic signal received by a second magnetic field sensor of the distal end assembly from a magnetic emitter coil disposed in a positioning pad, the positioning pad being configured to be disposed outside the body during tissue ablation by the electrode; calculate a third force signal based on the first force signal and the second force signal; and render to a display the force value or ablation index value calculated based on the third force signal; and a memory configured to store data used by the processor.

[0045] Example 2: According to the device of Example 1, wherein the processor is configured to render to the display: the force value or the ablation index value calculated based on the third force signal during the time period when the ablation energy is being conducted to the catheter; and another force value or another ablation index value calculated based on the first force signal during the time period when the ablation energy is not being conducted to the catheter.

[0046] Example 3: The device according to Example 1 or 2, wherein the first magnetic field sensor and the second magnetic field sensor are the same magnetic field sensor, wherein the first magnetic signal and the second magnetic signal are simultaneously received by the same magnetic field sensor during the ablation of the tissue by the electrode.

[0047] Example 4: The device according to any one of Examples 1 to 3, wherein the processor is configured to calculate the ablation index value based on the third force signal.

[0048] Example 5: The device according to any one of Examples 1 to 4, wherein the processor is configured to calculate the ablation index value based on the third force signal during ablation and to calculate an additional ablation index value based on the first force signal during non-ablation.

[0049] Example 6: The device according to any one of Examples 1 to 5, wherein the processor is configured to use a Kalman filter to combine the first force signal and the second force signal to generate the third force signal.

[0050] Example 7: The device according to Example 6, wherein the processor is configured to use the Kalman filter to combine the first force signal and the second force signal to generate the third force signal as the best state estimate of the force value.

[0051] Example 8: The device according to any one of Examples 1 to 6 further includes the conduit and the positioning pad.

[0052] Example 9: The device according to any one of Examples 1 to 6, wherein the processor is configured to calculate an ablation index value based on the third force signal, the third force signal being an estimate of the force sensed in real time during ablation at the corresponding ablation site, and the calculated ablation index value providing an indication of the quality of the ablation at the corresponding ablation site.

[0053] Example 10: The device according to Example 9, wherein the processor is configured to calculate the ablation index value based on the following: the third force signal calculated for the corresponding ablation site, and the ablation power used at the corresponding ablation site.

[0054] Example 11: The device according to Example 9, wherein the processor is configured to record the calculated ablation index value and render an electroanatomical mapping to a display, the electroanatomical mapping including an indication of the calculated ablation index value associated with the corresponding ablation site.

[0055] Example 12: A method comprising: conducting ablation energy to an electrode of a catheter; calculating a first force signal acting on the tissue by the distal end assembly of the catheter based on a first magnetic signal received from a magnetic emitter coil at the distal end of the catheter by a first magnetic field sensor of the distal end assembly during tissue ablation by the electrode; calculating a second force signal acting on the tissue by the distal end assembly of the catheter based on a second magnetic signal received from a magnetic emitter coil disposed in a positioning pad by a second magnetic field sensor of the distal end assembly, the positioning pad being configured to be disposed outside the body during tissue ablation by the electrode; calculating a third force signal based on the first force signal and the second force signal; and rendering to a display the force value calculated based on the third force signal or an ablation index value calculated based on the third force signal.

[0056] Example 13: The method according to Example 12 further includes rendering to the display: the force value or the ablation index value calculated based on the third force signal during the time period when the ablation energy is being conducted to the catheter; and another force value or another ablation index value calculated based on the first force signal during the time period when the ablation energy is not being conducted to the catheter.

[0057] Example 14: The method according to Example 12 or 13, wherein the first magnetic field sensor and the second magnetic field sensor are the same magnetic field sensor, and the method further includes receiving the first magnetic signal and the second position simultaneously by the same magnetic field sensor during the ablation of the tissue by the electrode.

[0058] Example 15: The method according to any one of Examples 12 to 14 further includes calculating the ablation index value based on the third force signal.

[0059] Example 16: The method according to any one of Examples 12 to 15 further includes calculating the ablation index value based on the third force signal during ablation, and calculating an additional ablation index value based on the first force signal during non-ablation.

[0060] Example 17: The method according to any one of Examples 12 to 16 further includes using a Kalman filter to combine the first force signal and the second force signal to generate the third force signal.

[0061] Example 18: According to the method of Example 17, the combination includes using the Kalman filter to combine the first force signal and the second force signal to generate the third force signal as the best state estimate of the force value.

[0062] Example 19: The method according to any one of Examples 12 to 17 further includes calculating an ablation index value based on the third force signal, the third force signal being an estimate of the force sensed in real time during ablation at the corresponding ablation site, the calculated ablation index value providing an indication of the quality of the ablation at the corresponding ablation site.

[0063] Example 20: According to the method of Example 19, the calculation of the ablation index value includes calculating the ablation index value based on the following: the third force signal calculated for the corresponding ablation site, and the ablation power used at the corresponding ablation site.

[0064] Example 21: The method according to Example 19 further includes: recording the calculated ablation index value, and rendering an electroanatomical mapping to a display, the electroanatomical mapping including an indication of the calculated ablation index value associated with the corresponding ablation site.

[0065] For clarity, the various features of this disclosure described in the context of individual embodiments may also be provided in combination in a single embodiment. Conversely, for simplicity, the various features of this disclosure described in the context of individual embodiments may also be provided individually or in any suitable sub-combination.

[0066] The above embodiments are cited by way of example, and this disclosure is not limited to the content specifically shown and described above. Rather, the scope of this disclosure 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.

Claims

1. An apparatus comprising: An ablation energy generator configured to conduct ablation energy to electrodes of a catheter; Processor, the processor being configured to: A first force signal acting on the tissue by the distal end assembly of the catheter is calculated based on a first magnetic signal received from a magnetic transmitter coil at the distal end of the catheter by a first magnetic field sensor of the distal end assembly of the catheter during tissue ablation by the electrode. A second force signal acting on the tissue by the distal end assembly of the catheter is calculated based on a second magnetic signal received from a magnetic transmitter coil disposed in the positioning pad by a second magnetic field sensor of the distal end assembly, the positioning pad being configured to be disposed outside the body during ablation of the tissue by the electrode; Calculate the third force signal based on the first force signal and the second force signal; as well as Render the force value or ablation index value calculated based on the third force signal to the display; and A memory configured to store data used by the processor.

2. The device according to claim 1, wherein, The processor is configured to render to the display: The force value or ablation index value calculated based on the third force signal during the time period during which the ablation energy is being conducted to the catheter; as well as During the period when the ablation energy is not conducted to the catheter, another force value or another ablation index value is calculated based on the first force signal.

3. The device according to claim 1, wherein, The first magnetic field sensor and the second magnetic field sensor are the same magnetic field sensor, wherein the first magnetic signal and the second magnetic signal are simultaneously received by the same magnetic field sensor during the ablation of the tissue by the electrode.

4. The device according to claim 1, wherein, The processor is configured to calculate the ablation index value based on the third force signal.

5. The device according to claim 1, wherein, The processor is configured to calculate the ablation index value based on the third force signal during ablation, and to calculate an additional ablation index value based on the first force signal during non-ablation.

6. The device according to claim 1, wherein, The processor is configured to use a Kalman filter to combine the first force signal and the second force signal to generate the third force signal.

7. The device according to claim 6, wherein, The processor is configured to use the Kalman filter to combine the first force signal and the second force signal to generate the third force signal as the best state estimate of the force value.

8. The device according to claim 1, further comprising the conduit and the positioning pad.

9. The device according to claim 1, wherein, The processor is configured to calculate an ablation index value based on the third force signal, which estimates the force sensed in real time during ablation at the corresponding ablation site, and the calculated ablation index value provides an indication of the quality of the ablation at the corresponding ablation site.

10. The device according to claim 9, wherein, The processor is configured to calculate the ablation index value based on: the third force signal calculated for the corresponding ablation site; and the ablation power used at the corresponding ablation site.

11. The device according to claim 9, wherein, The processor is configured to: Record the calculated ablation index value; and An electroanatomical mapping is rendered to the display, the electroanatomical mapping including an indication of a calculated ablation index value associated with the corresponding ablation site.

12. A method comprising: The ablation energy is conducted to the electrodes of the catheter; A first force signal acting on the tissue by the distal end assembly of the catheter is calculated based on a first magnetic signal received by a first magnetic field sensor from a magnetic transmitter coil at the distal end of the catheter during tissue ablation by the electrode. A second force signal acting on the tissue by the distal end assembly of the catheter is calculated based on a second magnetic signal received from a magnetic transmitter coil disposed in the positioning pad by a second magnetic field sensor of the distal end assembly, the positioning pad being configured to be disposed outside the body during ablation of the tissue by the electrode; Calculate the third force signal based on the first force signal and the second force signal; as well as The force value calculated based on the third force signal or the ablation index value calculated based on the third force signal is rendered to the display.

13. The method of claim 12, further comprising rendering to the display: The force value or ablation index value calculated based on the third force signal during the time period during which the ablation energy is being conducted to the catheter; and During the period when the ablation energy is not conducted to the catheter, another force value or another ablation index value is calculated based on the first force signal.

14. The method according to claim 12, wherein, The first magnetic field sensor and the second magnetic field sensor are the same magnetic field sensor, and the method further includes receiving the first magnetic signal and the second position simultaneously by the same magnetic field sensor during the ablation of the tissue by the electrode.

15. The method of claim 12, further comprising calculating the ablation index value based on the third force signal.

16. The method of claim 12, further comprising calculating the ablation index value based on the third force signal during ablation, and calculating an additional ablation index value based on the first force signal during non-ablation.

17. The method of claim 12, further comprising using a Kalman filter to combine the first force signal and the second force signal to generate the third force signal.

18. The method according to claim 17, wherein, The combination includes using the Kalman filter to combine the first force signal and the second force signal to generate the third force signal as the best state estimate of the force value.

19. The method of claim 12, further comprising calculating an ablation index value based on the third force signal, the third force signal being an estimate of the force sensed in real time during ablation at the corresponding ablation site, the calculated ablation index value providing an indication of the quality of the ablation at the corresponding ablation site.

20. The method according to claim 19, wherein, Calculating the ablation index value includes calculating the ablation index value based on the following: the third force signal calculated for the corresponding ablation site; and the ablation power used at the corresponding ablation site.

21. The method of claim 19, further comprising: Record the calculated ablation index value; as well as An electroanatomical mapping is rendered to the display, the electroanatomical mapping including an indication of a calculated ablation index value associated with the corresponding ablation site.

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