Estimation of catheter proximity to tissue using contact force sensing

Abstract

To estimate proximity of catheters to tissue.SOLUTION: A method to find tissue proximity indications includes inserting a shaft of catheter into body part of living subject, the catheter including an expandable distal-end assembly coupled to a distal end of the shaft that has multiple electrodes disposed thereon. Impedances are measured between each of the electrodes and a reference electrode. Based on measured impedances, subset of the electrodes is identified, that physically contact tissue of the body part. Signals are received from assembly of coils coupled at least one of the distal-end assembly and the distal end of the shaft. Based on signals, estimated is a total contact force exerted on the tissue by the assembly. Based on the identified subset of the electrodes and the estimated total contact force, one or more qualities are inferred, of physical contact between respective electrodes and the tissue. One or more of the inferred qualities of physical contact are output.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to invasive medical probes, and more particularly to estimating catheter proximity to tissue.

Background Art

[0002] Techniques for estimating the proximity of a catheter's electrodes to tissue have been previously proposed in the patent literature. For example, U.S. Patent Application Publication No. 2022 / 0183748 describes a method for detecting a tissue proximity metric that includes inserting a catheter into a body part of a living being such that the electrodes of the catheter contact the tissue at respective positions within the body part. Signals provided by the electrodes are received. The method further includes selectively providing rewards and penalties to a reinforcement learning agent over a reinforcement learning exploration phase to learn at least one tissue proximity policy in response to at least one of the received signals. The method additionally includes applying the reinforcement learning agent in a reinforcement learning exploitation phase to detect respective tissue proximity actions to be taken that maximize respective expected rewards in response to at least one tissue proximity policy. The method further includes providing respective derived tissue proximity metrics of the proximity of a given one of the electrodes to the tissue in response to each detected tissue proximity action.

[0003] A more complete understanding of the present disclosure will be obtained by reading the following detailed description of embodiments of the disclosure in conjunction with the drawings.

Brief Description of the Drawings

[0004]

Figure 1

Figure 2

Figure 3

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Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0005] Overview A catheter having a plurality of electrodes attached to an expandable distal end assembly of the catheter can be used to map and / or ablate the wall tissue of a cavity of a patient's organ, such as a ventricle. In a ventricular mapping and / or ablation procedure, the physician expands the assembly and manipulates the expanded distal end assembly such that the electrodes contact the ventricular wall and electrode signals are acquired or applied.

[0006] The quality of electrical mapping and / or ablation depends on the quality of the physical contact between the electrode and the wall tissue (also referred to as "touch quality (TQ)" in the present disclosure). The quality scale may use any unit (e.g., a number from 0 to 10), or may be given in physical units of contact force (e.g., steps of 1 dyne (=1 gram·cm·sec -2 ^-2) from 0 to 10 dynes).

[0007] One way to estimate the contact force of the entire assembly (e.g., not a specific electrode) with tissue is to use the local transmitter-receiver mode of a proximal electromagnetic coil and a distal electromagnetic coil (EMC), where the distal EMC is placed on the distal portion of the expandable assembly and the proximal EMC is placed on the distal end of the catheter shaft. This local transmitter-receiver mode provides an accurate estimate of the deflection Δl of the assembly shown in 3D with respect to the distal end of the catheter shaft. In one embodiment, the technique employs three coils distributed on the distal end of the assembly in three different XYZ orientations (e.g., on three different splines in the case of an expandable basket assembly) to enable sensing of the 3D position and orientation of the assembly (e.g., of the catheter basket assembly) with respect to the distal end of the catheter shaft. Using the deflection Δl (e.g., change in 3D orientation) and the known spring constant of the distal end assembly (elastic cage), the processor can calculate the contact force using the spring equation (F = K·Δl). The spring constant is known from the elastic model of the cage or based on laboratory calibration between a known force applied to the cage and the measured cage deflections respectively (e.g., to measure the spring constant). A detailed description of the contact force estimation method for a multi-electrode catheter using a position sensor in local transceiver mode is given in U.S. Patent Application No. 18 / 373,308, filed September 27, 2023, entitled "Estimation of Contact Force of Catheter Expandable Assembly", assigned to the assignee of this patent application.

[0008] The electrical impedance of a catheter electrode is considered a specific measure of how close the electrode is to the wall tissue. Since the range of impedance encountered by the electrode is specific to the patient and the procedure, the disclosed algorithm is used to continuously monitor each electrode impedance and look for changes. The impedance measurements may be normalized by detecting the lowest and highest values recorded over time. Lower impedance is typically well measured for an electrode within a ventricular blood pool, and higher impedance occurs when the electrode is close to or in physical contact with tissue (e.g., greater than 1 dyne).

[0009] For example, touch proximity (TP) can be estimated in this way by measuring the electrical impedance between an electrode disposed on the distal assembly and body tissue and the patch electrode. Examples of such electrical techniques are further described in U.S. Patent Application Publication No. 2022 / 0401032. TPI can also be measured more locally between an electrode disposed on the distal assembly and a reference electrode on the distal end of the shaft or on the distal assembly.

[0010] The embodiments of the present disclosure described herein provide a technique in which a processor infers the real-time quality of physical contact between an electrode and tissue based on the measured impedance related to the contact force applied to the distal assembly. This technique achieves an improved estimation of touch quality by determining the relationship between the contact force applied to the tissue throughout the distal assembly and the impedance measured by the electrode. This relationship is applicable to any electrode, despite only measuring the contact force of the entire assembly.

[0011] To achieve this relationship, a processor executing the disclosed technique identifies a subset of electrodes of an assembly that are shown to be in physical contact with a tissue wall by identifying an area on the assembly surface that contacts the tissue (e.g., on an approximate sphere in the case of a basket assembly) that is primarily centered in a direction orthogonal to the deflection direction of the assembly (as seen in FIG. 2), and (ii) in that area, only considers electrodes that have an impedance sufficient to indicate that they are in sufficiently firm contact with the tissue (e.g., electrodes having an impedance above a given threshold).

[0012] The processor applies the analysis model described in FIG. 2 to the identified subset of electrodes to obtain, for any electrode, the relationship between its measured impedance and the contact force with the underlying tissue.

[0013] Thus, during a clinical process such as ablation, the processor can estimate in real time the contact force of individual electrodes of an expandable distal assembly from the measured impedance and the detected force applied to the distal assembly, and for example, determine whether electrode TQ is sufficient to apply ablation energy.

[0014] In another example, the processor can use Bayesian estimation (described in FIG. 3) to statistically infer the TQ of individual electrodes and evaluate the most likely touch quality value on a given electrode. The shown contact force is the input and the most likely touch quality (e.g., with respect to contact force) is the inferred output. Bayesian estimation can modify the initial (electric-only) estimate of the most likely contact force, as described in FIG. 3.

[0015] Yet another way to statistically infer the quality of physical contact is to use a neural network trained with electrical signals and the respective estimated contact forces, or to directly use magnetic position data acquired for training.

[0016] Description of the System FIG. 1 is a schematic depiction of a catheter-based electroanatomical (EA) mapping and ablation system 10 according to an embodiment of the present disclosure.

[0017] System 10 includes one or more catheters that are percutaneously inserted by physician 24 into a cardiac chamber or vascular structure of heart 12 through a patient's vasculature. Typically, a delivery sheath catheter is inserted into the left atrium or right atrium near a desired location of heart 12. Thereafter, one or more catheters can be sequentially inserted into the delivery sheath catheter to reach a desired location. The one or more catheters can include a catheter dedicated to sensing intracardiac electrogram (IEGM) signals, a catheter dedicated to ablation, and / or a catheter dedicated to both sensing and ablation. A basket catheter 14 of an embodiment configured for ablation while sensing IEGM is shown herein. As another example, catheter 14 can be a tip catheter for ablation and sensing with a contact force mechanism as described in U.S. Patent No. 8,535,308, which is assigned to the assignee of the present application.

[0018] As seen in insertion view 45, physician 24 contacts a basket assembly 28 (hereinafter also referred to as "expandable distal end assembly 28") attached to the shaft 44 of catheter 14 with the heart wall to sense a target site within heart 12. For ablation, physician 24 similarly moves the distal end of the ablation catheter to a target site for ablation.

[0019] As seen in Inserted Figure 65, the basket catheter 14 is an exemplary catheter that is distributed over a plurality of splines 22 in a distally expandable distal end assembly 28 and includes one, preferably a plurality of electrodes 26 configured to ablate and / or sense IEGM signals. The catheter 14 additionally includes (i) a proximal position sensor 29 (e.g., a biaxial sensor (DAS) 29 having two orthogonal EMCs or a triaxial sensor (TAS) including three orthogonal EMCs) embedded at the distal end 46 of the shaft 44 near the basket assembly 28, and (ii) three distal position sensors 39 (e.g., single-axis sensors (SAS) 39 including a single EMC) for tracking the position of the distal end of the basket assembly 28. Optionally and preferably, the position sensors 29 and 39 are magnetic-based position sensors including magnetic coils for sensing three-dimensional (3D) position. A reference electrode 31 of an embodiment disposed at the base of the assembly 28 is also shown.

[0020] Figure 2 below shows how the EMCs of the distal sensor 39 and the proximal sensor 29 are used in a transmitter-receiver mode to estimate the contact force of the elastic basket cage with tissue. At the same time, the impedance signal (bipolar signal) between the electrodes 26 and / or the impedance signal (unipolar signal) between the electrode 26 and the electrode patch 38 are used to electrically estimate tissue proximity.

[0021] As described in FIGS. 2 and 3, the disclosed technique quantifies the quality of contact (i.e., TP) between each of the plurality of electrodes 26 and the tissue wall based on impedance detection associated with contact force detection by the model described in FIG. 2.

[0022] Magnetic position sensors (29, 39) (i.e., coil assemblies) can further operate with an external position pad 25 that includes a plurality of magnetic coils 32 configured to generate a magnetic field within a predetermined working volume. To prevent signal interference, the frequencies of these fields are different from any given frequency used in the local transmitter-receiver mode for contact force detection. The real-time orientation of the basket assembly 28 of the catheter 14 is thus calculated from the tracked locations of sensors 29 and 39 (the locations are generated using the position pad 25 and tracked using the magnetic fields sensed by the magnetic-based position sensors 29 and 39). This relative orientation is revealed by the angle formed between the distal end 46 and the longitudinal axis 42 of the expandable assembly 28 (extending to the distal edge 16 of the assembly).

[0023] Details of magnetic-based position sensing techniques are described in U.S. Pat. Nos. 5,539,199; 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; 6,892,091.

[0024] System 10 includes one or more electrode patches 38 disposed for skin contact on patient 23 to establish a position reference for the position pad 25 and impedance-based tracking of the electrodes 26. For impedance-based tracking, current is directed to the electrodes 26 and sensed at the electrode-skin patches 38, whereby the position of each electrode can be triangulated via the electrode patches 38. Details of impedance-based position tracking techniques are described in U.S. Pat. Nos. 7,536,218; 7,756,576; 7,848,787; 7,869,865; and 8,456,182.

[0025] Recorder 11 displays the electrocardiogram 21 captured by the body surface ECG electrodes 18 and the intracardiac electrogram (IEGM) captured by the electrodes 26 of the catheter 14. Recorder 11 may include pacing capabilities for pacing the rhythm of the heart and / or may be electrically connected to an independent pacemaker.

[0026] System 10 may include an ablation energy generator 50 adapted to deliver ablation energy to one or more electrodes at the distal tip of a catheter configured to ablate. The energy generated by ablation energy generator 50 may include high-frequency (RF) energy or pulsed-field ablation (PFA) energy, or a combination thereof, including unipolar or bipolar high-voltage DC pulses that can be used to effect irreversible electroporation (IRE), but is not limited thereto.

[0027] The patient interface unit (PIU) 30 is configured to establish electrical communication between the catheter, the electrophysiology equipment, the power supply, and the workstation 55 that controls the operation of system 10. The electrophysiology equipment of system 10 may include, for example, a plurality of catheters, position pads 25, body surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally and preferably, PIU 30 additionally includes processing capabilities for performing real-time calculations of catheter location and executing ECG calculations.

[0028] The workstation 55 includes a memory 57, a processor unit 56 having a memory or storage device loaded with appropriate operating software, and a user interface function. The workstation 55 may optionally provide a plurality of functions including: (i) rendering to model the endocardial anatomical structure in three-dimensions (3D) and display a model or anatomical map 20 on a display device 27; (ii) displaying on the display device 27 a representative visual display or image of an activation sequence (or other data) compiled from a recorded electrogram 21 superimposed on the rendered anatomical map 20; (iii) displaying the real-time position and orientation of a plurality of catheters within the heart chamber; and (iv) displaying on the display device 27 a site of interest such as a location where ablation energy has been applied. One commercially available product that implements each element of the system 10 is available as the CARTO (trademark) 3 system, commercially available from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA, 92618.

[0029] FIG. 1 illustrates a basket assembly, and the figures and disclosed methods are applicable to multi-ray assemblies and balloon assemblies with necessary modifications.

[0030] Estimation of Touch Quality (TQ) of Electrodes of an Expandable Assembly FIG. 2 is a schematic depiction of a catheter expandable distal end assembly 28 when in contact with tissue 47, according to an embodiment of the present disclosure.

[0031] As shown, the expandable distal assembly 28 forms an angle θ308 with the distal end 46 of the shaft 44. Angle 308 is defined between the longitudinal axis 307 of the expandable distal assembly and the longitudinal axis 305 of the distal end 46. Using the EMC 39, the EMC of the TAS 29, and the known relationship between the distal edge 309 of the assembly and the distal end 46, the processor can easily calculate the angle θ308. The processor can calculate the amount of deflection Δl of the distal edge 309 based on the tilt angle and length of the expandable distal assembly (e.g., length 241). Using the use of the deflection Δl (e.g., change in 3D orientation) and the known spring constant of the distal assembly (elastic cage), the processor can calculate the contact force using the spring equation (F = K·Δl).

[0032] The processor calculates a direction 312 in a space pointing away from the tissue contact area (orthogonal to the direction of the longitudinal axis 307). Each impedance reading value z1, z2,...z that exceeds a threshold (e.g., 200 ohms). k giving the electrodes 314, e1, e2,...e within this region k is identified. Based on the known magnitude and direction of the contact force and the identified electrodes having respective impedance reading values that exceed the threshold, a force distribution across the identified electrodes can be determined.

[0033] The impedance reading value can be between any electrode 314 and the electrode patch 38 (monopolar signal), where the patch is used as a reference, or between any electrode 314 and the reference electrode 31 on the distal assembly. Typically, the threshold impedance is determined for each patient during the procedure (e.g., by detecting the lowest and highest impedance values recorded over time).

[0034] The processor calculates the total impedance,

[0035]

Number

[0036]

Number

[0037] Method for estimating the touch quality (TQ) of electrodes of an expandable assembly FIG. 3 is a flowchart schematically showing a method for inferring the electrode touch quality for the basket cage 28 of FIG. 2 according to an embodiment of the present disclosure. The method includes two steps. The impedance-force association step 300 at the start of the clinical procedure for identifying the threshold impedance to be used provides a touch indicator and a subsequent TQ estimation step 320. The impedance-force association step can be repeated during the clinical procedure.

[0038] The algorithm according to the presented embodiment implements a process that begins with the physician 24 inserting an expandable distal assembly into the cavity (e.g., ventricle) in the basket assembly insertion step 302.

[0039] Next, impedance values are sampled and the range of impedance detected for the patient is determined.

[0040] In impedance thresholding step 306, the processor 56 defines a threshold impedance for the touch metric based on impedance.

[0041] In step 320, in assembly contact step 317, the physician contacts the basket assembly with the patient's cavity wall tissue (e.g., tissue 47) to, for example, ablate the tissue.

[0042] In impedance measurement step 319, the processor measures the impedance of the electrodes of the basket assembly.

[0043] In electrical estimation of touch quality step 321, the processor 56 estimates the touch quality (e.g., contact force) of the electrode (e.g., electrode 26) based on the electrical impedance signal.

[0044] Finally, the processor outputs the estimated electrode touch quality in output step 323. The information may be displayed to the physician and / or used by another algorithm such as an EA mapping algorithm or an ablation algorithm.

[0045] The flowchart shown in FIG. 3 is selected merely for the purpose of clarity of concept. Other possible steps (such as graphical encoding of TQ as done in FIG. 5) are intentionally omitted from the disclosure herein to provide a more simplified flowchart.

[0046] Statistical Inference of Electrode Touch Quality The inference method described with reference to FIG. 2 is mainly analytical. The statistical method of inferring the touch quality of an electrode from impedance is to use a prior estimate of the contact force in a Bayesian estimation method. Bayesian estimation evaluates the most likely value of the contact force on a given electrode. The estimated contact force is the input, the touch quality is the inferred output, and is in the form of a statistical distribution with the most likely value.

[0047] Figure 4 is a schematic graph 400 of the touch quality levels of electrodes statistically inferred using the estimated contact forces, according to an embodiment of the present disclosure. Figure 4 shows the probability distributions of touch quality for two different electrodes e1 and e2, such as two of the 26 electrodes. As shown, the disclosed technique detects the probability of touch quality when a measured touch force is given. In the case of electrode e1, the most likely touch quality is a value 403 that exceeds a given threshold 405 (e.g., exceeds 1 dyne). In the case of electrode e2, the most likely touch quality is a value 407 that is below the threshold 405.

[0048] In Figure 4, the estimation of the most likely previous touch qualities 413 and 417 for electrodes e1 and e2 is based only on electrical impedance. As shown, the electrical impedance results in very similar values 413 and 417, and both electrodes are considered to have sufficient touch quality. As shown, a processor using the disclosed technique updates the touch quality of electrode e2 as being at an insufficient level 407. In contrast, the prior electrical estimation-derived level 417 was shown to be greater than the threshold 405.

[0049] Method for estimating the contact force of the spline of a catheter-expandable assembly Figure 5 is a flowchart schematically showing a method for inferring the touch quality of an assembly electrode with tissue, according to an embodiment of the present disclosure. The algorithm according to the presented embodiment starts with a basket assembly insertion step 502 where the physician 24 inserts an expandable distal end assembly into a cavity (e.g., a ventricle).

[0050] Next, in an assembly contact step 504, the physician contacts the basket assembly with the cavity wall tissue (e.g., tissue 47), which leads to a change in the shape or orientation of the basket assembly relative to the distal end of the shaft.

[0051] In the electrical estimation step 506 of touch quality, the processor 56 estimates the touch quality of the electrode (for example, electrode 26) based on the electrical impedance signal.

[0052] In the magnetic estimation step 508 of contact force, the processor 56 uses the signal from the contact force sensor assembly to estimate the contact force on the basket.

[0053] Using the contact force estimated in step 508 and the impedance determined in step 506, the processor 56 infers the electrode touch quality in the electrode touch quality inference step 510.

[0054] Finally, in the output step 512, the processor outputs the inferred electrode touch quality. The information may be used by another algorithm such as an EA mapping algorithm or an ablation algorithm.

[0055] Finally, in the graphics step 514, the processor graphically shows the electrode 26 having a touch quality above a given threshold. The information may be displayed to the physician.

[0056] The flowchart shown in FIG. 5 is selected merely for the purpose of clarifying the concept. Other possible steps (such as imaging of the catheter) are intentionally omitted from the disclosure herein to provide a more simplified flowchart.

Example

[0057] (Example 1) A method for detecting tissue proximity indicators includes inserting the shaft (44) of a catheter (14) into a body part of a living body (23), the catheter (14) including an expandable distal end assembly (28) coupled to the distal end (46) of the shaft (44), the assembly (28) having a plurality of electrodes (26) disposed thereon. Impedance is measured between each of the electrodes (26) and a reference electrode (31). Based on the measured impedance, a subset of the electrodes (26) that physically contact the tissue of the body part is identified. A signal is received from an assembly of coils (29, 39) coupled to at least one of the distal end assembly (28) and the distal end (46) of the shaft. Based on the signal, the total contact force exerted on the tissue by the assembly (28) is estimated. Based on the identified subset of electrodes (26) and the estimated total contact force, one or more qualities of the physical contact between each electrode (26) and the tissue are inferred. One or more of the inferred qualities of the physical contact are output (323).

[0058] (Example 2) Inferring the quality of physical contact includes associating impedance with the contact force for each electrode (26) of the assembly (28) using a subset of the electrodes (26), the method described in Example 1.

[0059] (Example 3) Outputting the quality of physical contact includes providing the quality of physical contact as a number on a scale, the method described in Example 1 or 2.

[0060] (Example 4) Outputting a number when the corresponding estimated electrode contact force exceeds a given threshold and the impedance of the electrode (26) is within an estimated range of impedance, the method described in any of Examples 1 to 3.

[0061] (Example 5) Estimating the quality among the physical contact qualities of the electrode (26) includes inferring the probability (403, 407) that the physical contact force exceeds a given threshold (405) contact force using Bayesian statistics, according to the method described in any of Examples 1 to 4.

[0062] (Example 6) Estimating the quality among the physical contact qualities of the electrode (26) includes inferring the probability of quality based on the estimated contact force using a neural network (NN) model, according to the method described in any of Examples 1 to 4.

[0063] (Example 7) The expandable distal end assembly (28) includes one of a plurality of spines (22) and a plurality of layers on which the electrode (26) is disposed. Estimating the contact force includes estimating the contact force exerted by one or more of the spines (22) and one or more of the layers, according to the method described in any of Examples 1 to 6.

[0064] (Example 8) The expandable distal end assembly includes a plurality of spines (22) disposed in one of a basket assembly (28) and a multi-layer assembly, according to the method described in any of Examples 1 to 7.

[0065] (Example 9) Receiving a signal from an assembly of coils (29, 39) includes using an electromagnetic coil (EMC) in the local transmitter-receiver layout of the assembly (28), according to the method described in any of Examples 1 to 8.

[0066] (Example 10) Measuring the impedance includes receiving at least one of a bipolar signal and a monopolar signal acquired by the catheter (14), according to the method described in any of Examples 1 to 9.

[0067] (Example 11) A system (10) for detecting a tissue proximity indicator, the system including a catheter (14) and a processor (56). The catheter (14) includes a shaft (44) configured to be inserted into a body part of a living body (23), the catheter further including an expandable distal end assembly (28) coupled to the distal end (46) of the shaft, the distal end assembly (28) having a plurality of electrodes (26) disposed thereon. The processor is configured to (i) measure the impedance between each of the electrodes (26) and a reference electrode (31), (ii) identify a subset of the electrodes (26) that physically contact the tissue of the body part based on the measured impedance, (iii) receive a signal from an assembly of coils (29, 39) coupled to at least one of the distal end assembly (28) and the distal end (46) of the shaft, (iv) estimate the total contact force exerted on the tissue by the assembly (28) based on the signal, (v) infer one or more qualities of the physical contact between each of the identified electrodes (26) and the tissue based on the identified subset of electrodes (26) and the estimated total contact force, and (vi) output one or more of the inferred qualities of the physical contact.

[0068] The embodiments described herein mainly address cardiac diagnostic applications, but the methods and systems described herein can also be used for other medical applications.

[0069] It will be understood that the embodiments described above are given by way of example, and that the present disclosure is not limited to what is particularly illustrated and described above in this specification. Rather, the scope of the present disclosure includes both combinations and sub - combinations of the various features described above, as well as those variations and modifications thereof that would occur to those skilled in the art upon reading the foregoing description and that are not disclosed in the prior art.

[0070] 〔Embodiments〕 (1) A method for detecting a tissue proximity indicator, the method comprising: Inserting a catheter shaft into a body part of a living body, the catheter including an expandable distal end assembly coupled to a distal end of the shaft, the distal end assembly having a plurality of electrodes disposed thereon, Measuring an impedance between each of the electrodes and a reference electrode, Identifying a subset of the electrodes that physically contact the tissue of the body part based on the measured impedance, Receiving a signal from an assembly of coils coupled to at least one of the distal end assembly and the distal end of the shaft, Estimating a total contact force exerted on the tissue by the assembly based on the signal, Speculating on one or more qualities of physical contact between each electrode and the tissue based on the identified subset of the electrodes and the estimated total contact force, Outputting one or more of the speculated qualities of physical contact, a method comprising. (2) Speculating on the quality of physical contact includes associating the impedance with a contact force for each electrode of the assembly using the subset of electrodes, the method according to embodiment 1. (3) Outputting the quality of physical contact includes providing the quality of physical contact as a number on a scale, the method according to embodiment 1. (4) Outputting a number when a corresponding estimated electrode contact force exceeds a given threshold and the impedance of the electrode is within an estimated range of impedance, the method according to embodiment 3. (5) Speculating on a quality from among the qualities of physical contact of the electrodes includes inferring a probability that the physical contact force exceeds a given threshold contact force using Bayesian statistics, the method according to embodiment 1.

[0071] (6) Inferring quality from among the quality of the physical contact of the electrodes includes inferring the probability of the quality based on the estimated contact force using a neural network (NN) model, according to the method of embodiment 1. (7) The expandable distal end assembly includes one of a plurality of spines and a plurality of layers on which the electrodes are disposed, and estimating the contact force includes estimating the contact force exerted by one of one or more of the spines and one or more of the layers, according to the method of embodiment 1. (8) The expandable distal end assembly includes a plurality of spines disposed in one of a basket assembly and a multi-layer assembly, according to the method of embodiment 1. (9) Receiving the signal from the assembly of the coil includes using an electromagnetic coil (EMC) in the local transmitter-receiver layout of the assembly, according to the method of embodiment 1. (10) Measuring impedance includes receiving at least one of a bipolar signal and a monopolar signal acquired by the catheter, according to the method of embodiment 1.

[0072] (11) A system for detecting a tissue proximity indicator, the system comprising A catheter including a shaft configured to be inserted into a body part of a living body, the catheter further including an expandable distal end assembly coupled to a distal end of the shaft, the distal end assembly having a plurality of electrodes disposed thereon, A processor, and the processor Measures the impedance between each of the electrodes and a reference electrode, Identifies a subset of the electrodes that physically contact the tissue of the body part based on the measured impedance, Receives a signal from an assembly of coils coupled to at least one of the distal end assembly and the distal end of the shaft, Based on the signal, estimate the total contact force exerted on the tissue by the assembly, Based on the identified subset of the electrodes and the estimated total contact force, infer one or more qualities of the physical contact between each electrode and the tissue, A system configured to output one or more of the inferred qualities of the physical contact. (12) The system according to embodiment 11, wherein the processor is configured to infer the quality of the physical contact by associating the impedance with the contact force for each electrode of the assembly using the subset of the electrodes. (13) The system according to embodiment 11, wherein the processor is configured to output the quality of the physical contact by providing the quality of the physical contact as a number on a scale. (14) The system according to embodiment 13, wherein the processor is further configured to output a number when the corresponding estimated contact force of the electrode exceeds a given threshold and the impedance of the electrode is within an estimated range of impedances. (15) The system according to embodiment 11, wherein the processor is configured to infer a quality from among the qualities of the physical contact of the electrodes by inferring the probability that the physical contact force exceeds a given threshold contact force using Bayesian statistics.

[0073] (16) The system according to embodiment 11, wherein the processor is configured to infer a quality from among the qualities of the physical contact of the electrodes by inferring the probability of the quality based on the estimated contact force using a neural network (NN) model. (17) The expandable distal end assembly includes one of a plurality of spines and a plurality of rays on which the electrodes are disposed, and the processor is configured to estimate the contact force by estimating the contact force exerted by one or more of the spines and one or more of the rays. The system according to embodiment 11. (18) The expandable distal end assembly of claim 11, comprising a plurality of splines disposed in one of a basket assembly and a multi-layer assembly. (19) The system of claim 11, wherein the processor is configured to receive the signal from the assembly of coils by using an electromagnetic coil (EMC) in the local transmitter-receiver layout of the assembly. (20) The system of claim 11, wherein the processor is configured to measure impedance by receiving at least one of a bipolar signal and a monopolar signal acquired by the catheter.

Claims

1. 1. A system for detecting a tissue proximity indicator, the system comprising: a catheter including a shaft configured to be inserted into a body portion of a living subject, the catheter further including an expandable distal tip assembly coupled to a distal end of the shaft, the distal tip assembly having a plurality of electrodes disposed thereon; a processor, the processor comprising: measuring an impedance between each of said electrodes and a reference electrode; identifying a subset of the electrodes that are in physical contact with tissue of the body part based on the measured impedance; receiving a signal from an assembly of coils coupled at at least one of the distal tip assembly and the distal end of the shaft; estimating a total contact force exerted by the assembly on the tissue based on the signals; inferring one or more qualities of physical contact between each electrode and the tissue based on the identified subset of electrodes and the estimated total contact force; and outputting one or more of the inferred qualities of the physical contact.

2. 2. The system of claim 1, wherein the processor is configured to infer the quality of physical contact using the subset of electrodes by relating the impedance to a contact force for any electrode of the assembly.

3. The system of claim 1 , wherein the processor is configured to output the quality of physical contact by providing the quality of physical contact as a number on a scale.

4. 4. The system of claim 3, wherein the processor is further configured to output a number when a corresponding estimated electrode contact force is above a given threshold and the electrode impedance is within an estimated range of impedance.

5. 2. The system of claim 1, wherein the processor is configured to infer quality among the qualities of electrode physical contact by using Bayesian statistics to infer a probability that the physical contact force exceeds a given threshold contact force.

6. 2. The system of claim 1, wherein the processor is configured to infer a quality from among the qualities of electrode physical contact by inferring a probability of the quality based on the estimated contact force using a neural network (NN) model.

7. 2. The system of claim 1, wherein the expandable distal tip assembly includes one of a plurality of spines and a plurality of rays on which the electrodes are disposed, and the processor is configured to estimate the contact force by estimating the contact force exerted by one of one or more of the splines and one or more of the rays.

8. The system of claim 1 , wherein the expandable distal end assembly includes a plurality of splines disposed on one of a basket assembly and a multi-lay assembly.

9. The system of claim 1 , wherein the processor is configured to receive the signal from the assembly of coils by using an electromagnetic coil (EMC) in a local transmitter-receiver layout of the assembly.

10. The system of claim 1 , wherein the processor is configured to measure impedance by receiving at least one of a bipolar signal and a unipolar signal acquired by the catheter.

11. 1. A method for detecting a tissue proximity indicator, the method comprising: inserting a catheter shaft into a body portion of a living subject, the catheter including an expandable distal tip assembly coupled to a distal end of the shaft, the distal tip assembly having a plurality of electrodes disposed thereon; measuring an impedance between each of said electrodes and a reference electrode; identifying a subset of the electrodes that are in physical contact with tissue of the body part based on the measured impedance; receiving a signal from an assembly of coils coupled at least one of the distal tip assembly and the distal end of the shaft; estimating a total contact force exerted by the assembly on the tissue based on the signals; and inferring one or more qualities of physical contact between each electrode and the tissue based on the identified subset of electrodes and the estimated total contact force; and outputting one or more of the inferred qualities of physical contact.

12. The method of claim 11 , wherein inferring the quality of physical contact includes relating the impedance to a contact force for any electrode of the assembly using the subset of electrodes.

13. The method of claim 11 , wherein outputting the quality of the physical contact includes providing the quality of physical contact as a number on a scale.

14. 14. The method of claim 13, comprising outputting a number when a corresponding estimated electrode contact force is above a given threshold and the electrode impedance is within an estimated range of impedance.

15. 12. The method of claim 11, wherein inferring quality from among the qualities of electrode physical contact comprises using Bayesian statistics to infer a probability that the physical contact force exceeds a given threshold contact force.

16. 12. The method of claim 11, wherein inferring a quality from among the qualities of electrode physical contact comprises inferring a probability of the quality based on the estimated contact force using a neural network (NN) model.

17. 12. The method of claim 11, wherein the expandable distal tip assembly includes one of a plurality of spines and a plurality of rays on which the electrodes are disposed, and estimating the contact force includes estimating the contact force exerted by one of one or more of the splines and one or more of the rays.

18. The method of claim 11 , wherein the expandable distal end assembly includes a plurality of splines disposed on one of a basket assembly and a multi-lay assembly.

19. The method of claim 11 , wherein receiving the signal from the assembly of coils includes using an electromagnetic coil (EMC) in a local transmitter-receiver layout of the assembly.

20. The method of claim 11 , wherein measuring impedance includes receiving at least one of a bipolar signal and a unipolar signal acquired by the catheter.

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