Monitoring torsion on distal end assembly

Abstract

The invention discloses a device for measuring torque. The device is composed of a probe having a shaft with a shaft distal end. The probe has a distal end assembly configured to be inserted into an organ of a human subject and having a distal terminal and a proximal terminal connected to the shaft distal end. A position sensor assembly is attached to the distal end assembly proximate the distal terminal, the position sensor assembly configured to provide a signal indicative of a three-dimensional position and orientation of the distal terminal relative to the shaft distal end. A processor is configured to calculate a torsion of the distal terminal relative to the proximal terminal in response to the signal from the position sensor assembly, and to calculate the torque on the distal end assembly in response to the torsion and a predetermined correspondence between the torsion and the torque.

Description

Technical Field

[0001] The present disclosure relates generally to catheters, and particularly to measuring forces on catheters. Background Art

[0002] In a catheter configured to ablate tissue, the distal tip assembly of the catheter can be manipulated to a target area of ​​tissue. The electrodes on the distal tip assembly can then be used to ablate the target area tissue. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The present disclosure will be understood from the following detailed description in conjunction with the accompanying drawings, in which:

[0004] Figure 1 A catheter-based electrophysiology mapping and ablation system for medical procedures according to an example of the present disclosure is shown;

[0005] Figure 2A is a schematic diagram of a distal tip assembly in an unconstrained form for use in a system according to an example of the present invention;

[0006] Figure 2B is a schematic diagram of an unconstrained assembly along an assembly axis according to an example of the present invention;

[0007] Figure 3 is a schematic diagram of an alternative distal tip assembly according to an example of the present disclosure;

[0008] Figure 4 is a schematic diagram of another alternative distal tip assembly according to an example of the present disclosure;

[0009] Figure 5A is a flow chart describing a calibration algorithm executed by a processor of a system according to an example of the present disclosure; and

[0010] Figure 5B is a flow chart describing an operational algorithm executed by a processor during an ablation procedure according to examples of the present disclosure. DETAILED DESCRIPTION

[0011] Overview

[0012] A catheter with a distal tip assembly in the form of a basket or balloon can be advantageously used for ablation in, for example, the ostium of a pulmonary vein. Once the distal tip assembly has been correctly positioned, a circular ablation line can be generated by stimulating the multiple electrodes of the assembly simultaneously. This simultaneity reduces the overall time of the ablation procedure.

[0013] In the case of a basket distal tip assembly, the splines of the assembly are flexible so that the assembly can be manipulated into a desired position in the heart and so that the electrodes on the splines better conform to the shape of the tissue being ablated. However, the flexibility of the splines means that when the distal tip assembly is manipulated into position, the assembly as a whole can twist relative to the axis of the catheter when the electrodes come into contact with the tissue. In the case of a balloon, the assembly can also twist relative to the axis. In addition to twisting, the distal tip assembly can also press against the tissue.

[0014] When the physician manipulates and / or positions the catheter at the selected ablation site, a torque may be established between the twisted distal tip assembly and the contacted tissue. The quality and extent of ablation performed by the electrodes depends on the force applied to the tissue by the electrodes. It is important to consider the torque when obtaining the force applied to each electrode.

[0015] Examples of the present disclosure provide a method for determining the torque generated by a distal tip assembly by sensing the torsion (i.e., angular rotation) of the distal tip of the assembly relative to a shaft. A plurality of position sensors are attached proximate the distal tip of the distal tip assembly. During a procedure, such as an ablation procedure, the position and orientation of the sensors relative to the shaft are measured, and the torsion of the distal tip about an axis defined by the shaft of the catheter is calculated based on the measurements.

[0016] A calibration procedure performed prior to the ablation procedure finds a correspondence between the angular rotation (i.e., twist) produced and the torque that generates the rotation. In one example, the correspondence is based on a model and assumes that the distal tip assembly behaves as elastic. The correspondence is then used in the ablation procedure to find the total torque on the assembly based on the measured angular rotation. During the ablation procedure, the electrodes of the distal assembly that are in contact with the tissue are identified. Since the positions of the contact electrodes of the distal tip assembly are known, the force on each of the electrodes can be calculated based on the total torque.

[0017] System Description

[0018] In the following description, similar elements are identified by the same reference numerals and are distinguished by adding letters as suffixes after the numerals where necessary.

[0019] Reference now Figure 1, which shows a catheter-based electrophysiology mapping and ablation system 10 for medical procedures according to an example of the present disclosure. The system 10 includes a plurality of catheters that are inserted percutaneously through the patient's vascular system into a chamber or vascular structure of a heart 12 of a patient 23 by a physician 24. Typically, a delivery sheath catheter is inserted into the left atrium or right atrium near a desired location in the heart 12. Multiple catheters may then be inserted into the delivery sheath catheter in order to reach the desired location. The multiple catheters may 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.

[0020] An example catheter 14 (also referred to herein as a probe 14) configured for an ablation procedure is shown herein and includes an insertion shaft 37 and a distal tip assembly 28 secured to the distal end of the shaft. During the ablation procedure, once the distal tip assembly 28 leaves the delivery sheath, the physician 24 manipulates the proximal end of the shaft 37 so as to bring the assembly into contact with the heart wall 31 of a chamber 36 of the heart 12 for the purpose of ablating a target site in the wall.

[0021] Figure 2A is a schematic diagram of the distal tip assembly 28 in a fully deployed, unconstrained form (ie, with no contact forces applied to the distal tip assembly), and Figure 2B is a schematic diagram of an unconstrained assembly along an assembly axis according to an example of the present invention. In the description herein, unless otherwise specified, it is assumed that the catheter 14 comprises a basket catheter, so that the distal end assembly 28 is a basket constructed as a plurality of similar elastic splines 13A, 13B, ... (generally referred to as splines 13). The splines 13 form the assembly 28 to have a generally spherical shape and act as a support structure for the attached electrode 26, and therefore may also be referred to herein as a support structure 13.

[0022] Each of the splines of the structure 13 has at least one attached electrode 26 that can be used for ablation. Each spline has a known length, and each attached electrode 26 is located in a known position on its respective spline. The respective proximal terminals 16 of the splines are fixedly located at the distal end 19 of the shaft 37, and together serve as the proximal terminal of the distal tip assembly 28. The distal terminals 15 of the splines are bifurcated, and the bifurcations are connected together by a generally rigid ring 17 connecting adjacent splines. Other structures for connecting the distal terminals 15 are contemplated herein. The distal structure 34, which optionally includes an assembly of the ring 17 formed by connecting the distal terminals 15 by way of example herein, is generally generally rigid. The distal structure 34 serves as the distal terminal of the distal tip assembly 28.

[0023] exist Figure 2A and Figure 2BIn the example of the distal tip assembly 28 shown in FIG, there are ten splines 13 distributed about an assembly axis, referred to herein as the z-axis, which is colinear with the central symmetry axis of the distal end 19 of the shaft 37. However, it should be understood that the assembly 28 may have more or less than ten distributed splines.

[0024] like Figure 2A As shown in FIG. 3 , the terminal ends 15 of the splines 13 are close to a distal point 33 centered on the structure 34, and the z-axis includes a line from the distal point to the center of the shaft 37. The terminal ends 15 are symmetrically distributed around the distal point 33.

[0025] Position sensor 35 is located at the distal end 19 of shaft 37. In addition, a plurality of substantially similar position sensors 29A, 29B, ... are attached to respective different splines 13A, 13B, ... near the distal terminal end 15 of the splines. Sensors 29A, 29B, ... operate as a position sensor assembly 29 and are attached to their respective splines such that they are in a three-dimensional (3D) configuration. It should be understood that because the splines are angled relative to each other, the axes of the attached sensors of the splines are also angled relative to each other in the 3D configuration. By angling the sensors in this manner, even if the sensors are single axis sensors based on magnetics, the signals from the multiple sensors provide complete 3D information of the attached splines. In the disclosed example, as shown, there are three position sensors 29A, 29B, and 29C on splines 13A, 13B, and 13C, respectively, but other examples may have more or less than three sensors.

[0026] The splines to which the sensor assembly 29 is attached are selected so that the sensors are at least approximately symmetrically distributed about the z-axis. Thus, in the disclosed example using splines 13A, 13B, and 13C, where ten splines 13 are 36° apart, the angles between splines 13A, 13B, and 13C are 108°, 108°, and 144°. Selecting splines that are approximately symmetrically distributed ensures that adjacent sensors of a spline are as separated as possible.

[0027] The position sensor 35 and the position sensor assembly 29 are typically magnetic-based position sensors having at least one coil. In the disclosed example, the position sensor 35 is a two-axis or three-axis coil, and the sensor assembly 29 is a single-axis coil. The sensor 35 and the sensor assembly 29 can operate using a positioning pad 25 including a plurality of magnetic coils 32, which are configured to generate a magnetic field in a predetermined workspace. The real-time position of the multi-axis sensor 35 (i.e., the three-dimensional (3D) position and 3D orientation of the sensor) can be tracked based on the magnetic field generated using the positioning pad 25 and sensed by the sensor. Similarly, the real-time position of the single-axis sensor assembly 29 (i.e., their 3D position and 2D orientation) can be tracked based on the magnetic field from the positioning pad 25. Details of magnetic-based position sensing techniques are described 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, 6,892,091.

[0028] In some examples, one or more coils 41 are located at distal end 19, and the coils are configured to generate magnetic fields in a manner generally similar to the coils of positioning pad 25. The magnetic field from coils 41 enables tracking of the position of sensor assembly 29 relative to coils 41. U.S. Patent Publication 2020 / 0206461 provides details of a magnetic tracking system similar to that using coils 41, where a magnetic field generator on the basket catheter shaft is used to find the position of the sensor on the basket.

[0029] In some examples, sensor 35 is configured to operate sequentially or simultaneously as a position sensor and a magnetic field generator. When operating in this mode, the position of sensor 35 relative to positioning pad 25 is determined using the field from the positioning pad, and the position of sensor assembly 29 is determined relative to coil 41 (from its magnetic field) and relative to positioning pad 25.

[0030] It should be understood that Figure 2A The unconstrained form of the distal tip assembly 28 shown in the figure exists before the assembly enters the delivery sheath mentioned above. As described above, during the ablation procedure, the physician 24 manipulates the proximal end of the catheter shaft 37 to bring the distal tip assembly 28 into contact with the heart wall 31. Manipulation generally involves the physician 24 pushing, pulling, bending and / or turning the proximal end of the shaft 37 to bring the assembly 28 into the desired position for contacting the wall 31.

[0031] When at least some of the electrodes 26 of the distal end assembly are in contact with the wall 31, the assembly may be twisted from its unconstrained form relative to the shaft 37. In the constrained, twisted form of the assembly, the tissue in contact with the electrodes exerts a corresponding force on the electrodes, thereby generating a torque on the assembly, and the electrodes exert a corresponding counteracting force on the tissue. The following description of FIG. 5 describes how examples of the present disclosure detect torque on the assembly and the forces on the assembly electrodes caused by the torque.

[0032] Figure 3 1 is a schematic diagram of an alternative distal tip assembly 128 according to an example of the present disclosure. The operation of assembly 128 is similar to assembly 28 ( Figure 2A and Figure 2B ) are substantially similar in operation, and elements indicated by the same reference numerals in both assembly 28 and assembly 128 are substantially similar in construction and operation. In contrast to assembly 28 in which electrodes 26 are attached as single electrodes, in assembly 128, electrodes 26 are attached in groups. By way of example, in the illustrated example of assembly 128, electrodes 26 are in groups of three. As for assembly 28, in assembly 128, sensor assembly 29 is located at a distal section of assembly 128 in a 3D configuration.

[0033] Figure 4 28 and 128 ( Figure 2A , Figure 2B and Figure 3 ) are substantially similar in operation, and elements indicated by the same reference numerals in assemblies 28, 128, and 228 are substantially similar in construction and operation.

[0034] In contrast to assemblies 28 and 128, distal tip assembly 228 is formed as a balloon assembly having a balloon 232 that has a generally spherical shape when inflated. Balloon 232 acts as a support structure for ablation electrode 236 (which is attached to the balloon via electrode substrate 238), and therefore may also be referred to herein as support structure 232. Figure 4 , assembly 228 is shown with balloon 232 attached to shaft 37 in its inflated state.

[0035] Balloon terminal 240 is located at the distal end of the balloon and, together with the center of shaft 37, defines a z-axis as the axis of assembly 228. (A lasso catheter 244 is shown extending from balloon terminal 240 and may be used to position balloon assembly 228 in a desired position.) As for assemblies 28 and 128, position sensor assembly 29 (in the illustrated example, there are three sensors 29A, 29B, 29C) is attached to balloon 232 proximate terminal 240 in the 3D configuration described above.

[0036] For simplicity and clarity, the following description refers to distal tip assembly 28, and one of ordinary skill in the art will be able to adapt the description, mutatis mutandis, to other distal tip assemblies such as assembly 128 and assembly 228. Thus, the scope of the present disclosure includes other basket catheters having distal tip assemblies including a plurality of elastic splines, each of the splines having at least one electrode that can be used for ablation. The scope of the present disclosure also includes other balloon catheters having a balloon with an attached electrode suitable for ablation.

[0037] return Figure 1 , the system 10 includes one or more electrode patches 38 positioned for contact with the skin on the patient 23. Measurement of the impedance between the patch 38 and a given electrode 26 can be used to identify whether the electrode is contacting tissue of the wall 31. U.S. Patent 11,596,324 describes how to use the impedance between the electrodes on the basket catheter and the patch on the patient's skin to identify whether the electrode is contacting tissue in a chamber of the patient's organ. Optionally, the impedance between the intracardiac electrodes can be sensed to assess contact with the chamber wall. The intracardiac electrodes can include electrodes on the distal tip assembly and / or electrodes on the distal end of the catheter shaft.

[0038] Recorder 11 displays electrograms 21 captured using body surface ECG electrodes 18 and intracardiac electrograms (IEGMs) that may be captured using electrodes 26 of catheter 14. Recorder 11 may include pacing capabilities for pacing the cardiac rhythm and / or may be electrically connected to a separate pacemaker.

[0039] The system 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more of the electrodes 26. 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, such as may be used to achieve irreversible electroporation (IRE)), or a combination thereof.

[0040] The patient interface unit (PIU) 30 is an interface configured to establish electrical communication between catheters, electrophysiology equipment, a power source, and a workstation 55 for controlling the operation of the system 10. The electrophysiology equipment of the system 10 may include, for example, multiple catheters, a positioning pad 25, surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally and preferably, the PIU 30 additionally includes processing capabilities for enabling real-time calculation of the position of the catheter and for performing ECG calculations.

[0041] The workstation 55 includes a memory, a processor 22 with a memory or storage device loaded with appropriate operating software, and user interface capabilities. The processor 22 operates the system 10. The workstation 55 can provide multiple functions, optionally including: (1) three-dimensional (3D) modeling of endocardial anatomy and rendering a model or anatomical map 20 of the heart 12 or a portion thereof for display on the display device 27, (2) displaying an activation sequence (or other data) compiled from a recorded electrogram 21 on the display device 27 as representative visual markers or images superimposed on the rendered anatomical map 20, (3) displaying a representation 39 of the combined real-time position and orientation values ​​of the distal tip assembly 28 within the heart chamber 36, and (4) displaying a site of interest, such as a site to which ablation energy has been applied, on the display device 27. A commercial product embodying elements of the system 10 can be CARTO TM The 3 system was purchased from Biosense Webster, Inc., 31 Technology Drive, Suite 200, Irvine, CA 92618.

[0042] Reference now Figure 5A , which is a flowchart 300 describing a calibration algorithm executed by the processor 22 according to an example of the present disclosure.

[0043] It is assumed that the algorithm of flowchart 300 is executed by processor 22 .

[0044] The distal tip assembly is calibrated in an initial calibration step 304 of the flowchart, which is performed prior to an ablation procedure using the distal tip assembly 28. The calibration process applies known torques to the assembly 28, and for each torque applied, registers and measures the average angular deflection, i.e., twist, of the sensor assembly 29 relative to the distal end 19 of the shaft 37. As explained above, the position sensor 35 on the distal end 19 of the shaft 37 (to which the assembly 28 is attached) measures the orientation of the distal end 19 in 3D.

[0045] As described above, the deflection of each sensor from its unconstrained position is measured from sensor signals generated in response to magnetic fields emitted from positioning pad 25 and / or coil 41. Torque may be applied by any convenient method, such as by twisting the distal end of assembly 26 and monitoring the torque required for twisting.

[0046] In a storage step 306, processor 22 stores the correspondence between the torque applied to assembly 28 and the average angular deflection of position sensor assembly 29 and / or the angular deflection of distal structure 34 as a result of the calibration process. The correspondence may be in any convenient form, such as a lookup table or a model-based relationship.

[0047] In the disclosed example, the correspondence is based on a model and assumes that the component 28 behaves elastically, with a positive proportional relationship according to equation (1):

[0048] T=k·θ (1)

[0049] Where T is the torque applied to the component, measured in N·m,

[0050] θ is the average angular deflection of the sensor assembly 29, measured in degrees, and

[0051] k is the proportionality constant of equation (1) and corresponds to the spring constant of the assembly.

[0052] In step 306 , processor 22 calculates the spring constant k of the assembly.

[0053] Figure 5B 310 is a flow chart describing an operational algorithm executed by processor 22 during an ablation procedure according to an example of the present disclosure. In the procedure, physician 24 inserts catheter 14 into heart 12 until distal assembly 28 is in a desired target position contacting wall 31. Processor 22 uses the algorithm to ascertain the torque on distal tip assembly 28 and the corresponding force on electrodes 26 of the assembly as a result of the applied torque.

[0054] The following description of the flow chart 310 assumes that the correspondence between torque and average angular deflection given by equation (1) applies, and a person skilled in the art will be able to adapt the description mutatis mutandis to other types of correspondences.

[0055] In a measuring step 308, the processor 22 records the measured position of the sensor assembly 29. Based on the measured position relative to the shaft distal end 19, the processor calculates the average angular deflection of the sensor, i.e., the twist of the distal end assembly 28. It should be understood that the sensor assembly 29 does not have to deflect symmetrically about the z-axis. For example, in the case where the distal end assembly 28 as a whole deflects relative to the shaft distal end 19, the angular deflection may be asymmetrical.

[0056] The average angular deflection of the sensor assembly 29 is assumed to be θ m .

[0057] The processor 22 calculates the total torque T on the assembly according to equation (2) using the calculated value of the average angular deflection and the spring constant k of the assembly determined in the calibration step 304 of the flowchart 300. m :

[0058] T m = k·θ m (2)

[0059] Torque on assembly 28 is generated by electrodes 26 contacting wall 31, and processor 22 determines the number of electrodes contacting the wall in counting step 312. As described above, processor 22 can use impedance-based measurements to identify which of electrodes 26 contact tissue of wall 31.

[0060] For each electrode 26 identified as contacting the wall 31, the processor 22 also records the position of the electrode. The position may be calculated based on the measured twist of the electrode, or alternatively or in addition, using impedance-based measurements, such as reference Figure 1 Further alternatively or in addition, the known positions of the electrodes on the splines 13 and the dimensions of the splines may be used to record the positions.

[0061] From the recorded position of each electrode, processor 22 calculates a vector from the electrode to the axis of assembly 28 (ie, the z-axis), which vector includes distance and direction.

[0062] It will be appreciated that each electrode that contacts the tissue of wall 31 contributes to the total torque on assembly 28, such that the calculated vector corresponds to the lever arm vector of the torque generated by the electrode.

[0063] In an electrode-force step 316 , processor 22 uses the results calculated in steps 308 and 312 to estimate the torsional force on each electrode.

[0064] In the disclosed example, it is assumed that the measured total torque T m is evenly distributed among all contacting electrodes. In this case, the magnitude of the torsional force on each electrode is given by equation (3):

[0065]

[0066] where F E is the torsional force on electrode E in electrode 26,

[0067] T m is the total torque on the assembly 28 calculated in equation (2),

[0068] n is the number of electrodes 26 in contact with the tissue of wall 31 determined in step 312, and

[0069] d E is the distance of electrode E from the axis of assembly 28 , also determined in step 312 .

[0070] Equation (3) gives the magnitude of the torsional force on electrode E. The direction of the torsional force on electrode E is orthogonal to the axis of symmetry of assembly 28 and also orthogonal to the lever arm vector of electrode E.

[0071] The above results, i.e., the values ​​generated from equations (2) and (3), and the direction of the force on the electrodes of the distal tip assembly can be provided to the physician 24, for example, using the display device 27. For a given electrode, the results can be combined with the force generated by the electrode pressing against the tissue in a non-torsional manner, and the total resultant force on the given electrode can be provided to the physician 24.

[0072] Example

[0073] Embodiment 1. A device for measuring torque, comprising:

[0074] A probe (14), comprising:

[0075] a shaft (37) having a shaft distal end (19);

[0076] a distal tip assembly (28) configured to be inserted into an organ of a human subject, the distal tip assembly having a distal terminal end (34) and a proximal terminal end (16) connected to the distal end of the shaft; and

[0077] a position sensor assembly (29) attached to the distal end assembly proximate the distal terminal end of the distal end assembly, the position sensor assembly being configured to provide a signal indicative of a three-dimensional (3D) position and orientation of the distal terminal end relative to the shaft distal end; and

[0078] A processor (22) configured to calculate the torsion of the distal terminal relative to the proximal terminal in response to the signal from the position sensor assembly, and to calculate the torque on the distal end assembly in response to the torsion and a predetermined correspondence between the torsion and the torque.

[0079] Example 2. A device according to Example 1, and comprising an axis position sensor (35) attached to the distal end of the axis, the axis position sensor being configured to provide a signal indicative of the orientation of the axis, and wherein the processor is configured to calculate the torsion associated with the orientation of the axis.

[0080] Example 3. An apparatus according to Example 1, and comprising a magnetic field generator (41) attached to the distal end of the shaft, and wherein the signal from the position sensor assembly is generated in response to a magnetic field from the generator, and wherein the processor is configured to calculate the torsion associated with the orientation of the shaft.

[0081] Embodiment 4. The apparatus of embodiment 1, wherein the predetermined correspondence is based on modeling the distal end component as an elastic component.

[0082] Example 5. A device according to Example 1, and comprising a plurality of electrodes (26) attached to the distal end assembly, wherein the processor is configured to identify electrodes contacting tissue of the organ, and to evaluate the number of contacting electrodes, and to calculate an electrode torque on a given electrode among the contacting electrodes in response to the number and the torque.

[0083] Example 6. A device according to Example 5, wherein the processor is configured to determine the distance of the given electrode to a torsional axis connecting the proximal terminal to the distal terminal, and to calculate the magnitude of the force on the given electrode in response to the electrode torque and the distance.

[0084] Embodiment 7. A device according to embodiment 5, wherein the processor is configured to determine a vector from the given electrode to a torsional axis connecting the proximal terminal with the distal terminal, and to calculate the direction of the force on the given electrode in response to the orientation of the vector and the torsional axis.

[0085] Example 8. The apparatus of Example 5, wherein the processor is configured to determine the force on the given electrode in response to the given electrode pressing on the tissue in a non-torsional manner.

[0086] Example 9. The device of Example 1, wherein the distal end assembly comprises a balloon.

[0087] Example 10. The device of Example 1, wherein the distal end assembly comprises a plurality of splines.

[0088] Embodiment 11. A method for measuring torque, comprising:

[0089] A probe (14) is provided, the probe comprising:

[0090] a shaft (37) having a shaft distal end (19);

[0091] a distal tip assembly (28) configured to be inserted into an organ of a human subject, the distal tip assembly having a distal terminal end (34) and a proximal terminal end (16) connected to the distal end of the shaft; and

[0092] a position sensor assembly (29) attached to the distal end assembly proximate the distal terminal end of the distal end assembly, the position sensor assembly being configured to provide a signal indicative of a three-dimensional (3D) position and orientation of the distal terminal end relative to the shaft distal end;

[0093] calculating a twist of the distal terminal relative to the proximal terminal in response to the signal from the position sensor assembly; and

[0094] The torque on the distal tip assembly is calculated in response to the twisting and a predetermined correspondence between the twisting and the torque.

[0095] Embodiment 12. A method according to embodiment 11, and comprising: attaching a shaft position sensor (35), the shaft position sensor being configured to provide a signal indicative of the orientation of the shaft; and calculating the torsion associated with the orientation of the shaft.

[0096] Embodiment 13. A method according to embodiment 11, and comprising: attaching a magnetic field generator (41) to the distal end of the shaft, wherein the signal from the position sensor assembly is generated in response to a magnetic field from the generator; and calculating the torsion associated with the orientation of the shaft.

[0097] Embodiment 14. The method according to embodiment 11, wherein the predetermined correspondence is based on modeling the distal end component as an elastic component.

[0098] Example 15. A method according to Example 11, and comprising: attaching a plurality of electrodes (26) attached to the distal end assembly; identifying electrodes contacting tissue of the organ; evaluating the number of contacting electrodes; and calculating an electrode torque on a given electrode among the contacting electrodes in response to the number and the torque.

[0099] Embodiment 16. A method according to embodiment 15, and comprising: determining the distance of the given electrode to the torsional axis connecting the proximal terminal with the distal terminal, and calculating the magnitude of the force on the given electrode in response to the electrode torque and the distance.

[0100] Embodiment 17. A method according to embodiment 15, and the method includes: determining a vector from the given electrode to a torsional axis connecting the proximal terminal with the distal terminal; and calculating the direction of the force on the given electrode in response to the orientation of the vector and the torsional axis.

[0101] Embodiment 18. The method of Embodiment 15, and comprising: determining the force on the given electrode in response to the given electrode pressing on the tissue in a non-torsional manner.

[0102] Example 19. A method according to Example 11, wherein the distal end assembly includes a balloon.

[0103] Example 20. A method according to Example 11, wherein the distal end assembly includes a plurality of splines.

[0104] The above embodiments are cited by way of example, and the present disclosure is not limited by what is specifically shown and described above. On the contrary, the scope of the present 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. A device for measuring torque, comprising: A probe, the probe comprising: a shaft having a shaft distal end; a distal tip assembly configured to be inserted into an organ of a human subject, the distal tip assembly having a distal terminal end and a proximal terminal end connected to the shaft distal end; and a position sensor assembly attached to the distal end assembly proximate the distal terminal end of the distal end assembly, the position sensor assembly being configured to provide a signal indicative of a three-dimensional (3D) position and orientation of the distal terminal relative to the shaft distal end; and A processor configured to calculate a torsion of the distal terminal relative to the proximal terminal in response to the signal from the position sensor assembly, and to calculate the torque on the distal end assembly in response to the torsion and a predetermined correspondence between the torsion and the torque.

2. The apparatus of claim 1 and comprising a shaft position sensor attached to the distal end of the shaft, the shaft position sensor being configured to provide a signal indicative of the orientation of the shaft, and wherein, The processor is configured to calculate the twist associated with the orientation of the shaft.

3. The apparatus of claim 1, and comprising a magnetic field generator attached to the distal end of the shaft, and wherein: The signal from the position sensor assembly is generated in response to a magnetic field from the generator, and wherein the processor is configured to calculate the twist associated with the orientation of the shaft.

4. The device according to claim 1, wherein: The predetermined correspondence is based on modeling the distal tip component as an elastic component.

5. The apparatus of claim 1 and comprising a plurality of electrodes attached to the distal tip assembly, wherein: The processor is configured to identify electrodes contacting tissue of the organ, and to assess a number of contacting electrodes, and to calculate an electrode torque on a given one of the contacting electrodes in response to the number and the torque.

6. The device according to claim 5, wherein: The processor is configured to determine a distance of the given electrode from a torsion axis connecting the proximal terminal with the distal terminal and to calculate a magnitude of a force on the given electrode in response to the electrode torque and the distance.

7. The device according to claim 5, wherein: The processor is configured to determine a vector from the given electrode to a torsion axis connecting the proximal terminal with the distal terminal, and to calculate a direction of a force on the given electrode in response to the vector and an orientation of the torsion axis.

8. The device according to claim 5, wherein: The processor is configured to determine a force on the given electrode in response to the given electrode pressing on the tissue in a non-torsional manner.

9. The system according to claim 1, wherein: The distal tip assembly includes a balloon.

10. The device according to claim 1, wherein: The distal tip assembly includes a plurality of splines.

11. A method for measuring torque, comprising: A probe is provided, the probe comprising: a shaft having a shaft distal end; a distal tip assembly configured to be inserted into an organ of a human subject, the distal tip assembly having a distal terminal end and a proximal terminal end connected to the shaft distal end; and a position sensor assembly attached to the distal end assembly proximate the distal terminal end of the distal end assembly, the position sensor assembly configured to provide a signal indicative of a three-dimensional (3D) position and orientation of the distal terminal end relative to the shaft distal end; calculating a twist of the distal terminal relative to the proximal terminal in response to the signal from the position sensor assembly; and The torque on the distal tip assembly is calculated in response to the twisting and a predetermined correspondence between the twisting and the torque.

12. A method according to claim 11, and comprising: attaching a shaft position sensor configured to provide a signal indicative of an orientation of the shaft; and calculating the twist associated with the orientation of the axis.

13. The method according to claim 11, and comprising: attaching a magnetic field generator to the shaft distal end, wherein the signal from the position sensor assembly is generated in response to a magnetic field from the generator; and calculating the twist associated with the orientation of the shaft.

14. The method according to claim 11, wherein: The predetermined correspondence is based on modeling the distal tip component as an elastic component.

15. The method according to claim 11, and comprising: attaching a plurality of electrodes attached to the distal tip assembly; identifying electrodes contacting tissue of the organ; evaluating the number of contact electrodes; and calculating an electrode torque on a given one of the contacting electrodes in response to the quantity and the torque.

16. A method according to claim 15, and comprising: A distance of the given electrode from a torsion axis connecting the proximal terminal to the distal terminal is determined, and a magnitude of a force on the given electrode is calculated in response to the electrode torque and the distance.

17. The method according to claim 15, and comprising: determining a vector from the given electrode to a torsion axis connecting the proximal terminal with the distal terminal; and calculating a direction of the force on the given electrode in response to the vector and the orientation of the torsion axis.

18. The method according to claim 15, and comprising: A force on the given electrode is determined in response to the given electrode pressing against the tissue in a non-torsional manner.

19. The method according to claim 11, wherein: The distal tip assembly includes a balloon.

20. The method according to claim 11, wherein: The distal tip assembly includes a plurality of splines.

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