Deformation-based pressure sensing

Abstract

Determining the force exerted by a catheter when it is inserted into tissue. [Solution] A method for performing a medical procedure is provided, which involves providing a probe having a known spring constant for insertion into a patient, wherein the probe has electrodes and position sensors at each location along the probe, and recording the relative position coordinates of the electrodes and position sensors when the probe is in an unrestrained state. While the probe is in the patient and deformed by contact with the patient's tissue, changes in the relative position coordinates of the electrodes and position sensors in contact with the tissue are recorded, and the shape of the deformed probe is calculated in response to the recorded changes. In response to the known spring constant and the calculated probe shape, the respective forces exerted by the tissue on each electrode are calculated, and the electrical signals from the tissue through the electrodes are controlled in response to the calculated forces on the electrodes.

Description

[Technical Field]

[0001] This disclosure generally relates to catheterization techniques, and more specifically to determining the forces exerted by a catheter when it is inserted into tissue. [Background technology]

[0002] Cardiac catheterization procedures typically involve initial mapping of the patient's heart before surgery on the heart, such as cardiac tissue ablation. Both mapping and ablation can be performed by electrodes attached to a catheter inserted into the heart. [Brief explanation of the drawing]

[0003] This disclosure will be understood from the following detailed description in conjunction with the attached drawings. [Figure 1] An example of a catheter-based electrophysiological mapping and ablation system is shown in this disclosure. [Figure 2] This is a flowchart of the steps performed by the processor of the system in Figure 1 when implementing an algorithm for determining the force exerted by a probe, as illustrated in the example of this disclosure. [Figure 3] This is a schematic diagram of a part of a probe, as an example of the disclosure. [Modes for carrying out the invention]

[0004] overview Cardiac catheterization procedures typically involve both mapping regions of cardiac tissue and ablation of selected sections of tissue, using a multi-electrode assembly attached to the distal end of a catheter. Each electrode in the assembly may be used for mapping and / or ablation of the tissue it contacts. For any given electrode, recording the electrode's position during mapping relies on a processor to identify contact with tissue. In the case of ablation, the dimensions of the tissue to be ablated depend on the force applied to the tissue by the electrode (this force is equal to, but opposite to, the force applied by the tissue to a given electrode). One or more force sensors may be present on the assembly, but these sensors are insufficient to provide force values ​​for the individual electrodes of the probe.

[0005] The assembly may have one or more splines, also referred to herein as probes, each of which typically has multiple electrodes. As described below, examples of the present disclosure provide estimates of the force from each electrode, as well as estimates of the pressure (as force per linear length) applied to a given probe.

[0006] An example of the present disclosure records changes in the shape of a given probe assembly when the probe is deformed by one or more electrodes in contact with tissue. Changes in shape may be recorded, for example, from signals provided by a location sensor incorporated into the probe and / or from signals generated by a conductive loop supported on or embedded within the probe. An example of the present disclosure also uses, for example, an impedance-based system to determine which electrodes are in contact with tissue and which are not.

[0007] In the disclosed example, the processor models the probe as several sections connected at a joint, and the probe electrodes are assumed to be at known locations on the sections. The joint acts as a torsion spring with a known torsional spring constant, and the sections exert torsional and compressive forces on each joint. The magnitude and direction of the torsional force, as well as the direction of the compressive force, are known from the change in the probe's shape and from the joint spring constant.

[0008] The model divides the joints into two types: a first type that contacts tissue and a second type that does not contact tissue. Both types may have external forces acting on the joint, separate from the torsional and compressive forces from the section described above. Each external force is decomposed into two orthogonal components: a component parallel to the probe at the joint and a component perpendicular to the probe.

[0009] The model assumes that the first type of joint (a joint in contact with tissue) is "slippery," and as a result, the parallel component of the external force from the tissue in contact with the joint is minimized. In addition, since the second type of joint does not come into contact with tissue, the perpendicular component of the external force of the second type is also minimized.

[0010] The processor uses a minimization function to calculate the values ​​of all components of the external forces at all joints. When determining the minimization function, the processor uses known joint torsional values ​​and also applies the constraint that the sum of all forces at each joint is zero because the probe is in equilibrium.

[0011] From the calculated component values, the processor can calculate the external force acting on each joint and interpolate the forces to calculate the pressure acting on each section of the probe. Using the calculated pressure, the processor can determine the force acting on each electrode of the probe.

[0012] As described above, any given electrode of the probe can be used to map the contacted tissue, and the mapping is performed by a processor that measures the signal received from the electrode and determines the location of the electrode in response to the signal. The processor may be configured to accept the determined location when the determined force from the tissue to the electrode (which is the same as the force from the electrode to the tissue) is greater than a preset minimum force.

[0013] Alternatively or additionally, any given electrode may be used to ablate the tissue. The processor may be configured to adjust the duration and / or value of the ablation current passing through the electrode in response to the required force applied from the electrode to the tissue.

[0014] System Description In the following description, similar elements are identified by the same number and, where necessary, distinguished by adding a letter as a suffix to the number.

[0015] Referring here to Figure 1, this shows a catheter-based electrophysiological mapping and ablation system 10 used for a medical procedure, as illustrated by the present disclosure. The system 10 includes multiple catheters that are percutaneously inserted by a physician 24 through the patient's vascular system into the lumen or vascular structure of the patient's heart 12. Typically, a delivery sheath catheter is inserted into the left or right atrium near the desired location in the heart 12. Multiple catheters can then be inserted into the delivery sheath catheter to reach the desired location. The multiple catheters may include catheters dedicated to sensing intracardiac electrogram (IEGM) signals, catheters dedicated to ablation, and / or catheters dedicated to both sensing and ablation.

[0016] An exemplary catheter 14 configured for sensing and / or ablation procedures is shown herein, comprising an insertion shaft 37 and a distal end assembly 28 fixed to the distal end of the shaft. During the procedure, once the distal end assembly 28 has exited the delivery sheath, the physician 24 manipulates the proximal end of the shaft 37 to bring the assembly into contact with the cardiac wall 31 of the lumen 36 of the heart 12 for the purpose of sensing a signal from a target site in the wall or ablating a target site in the wall.

[0017] In this specification, unless otherwise specified, the distal end assembly 28 is a basket constructed as a plurality of similar elastic splines or probes 13. The probes 13 form the assembly 28, which has a generally spheroidal shape and functions as a support structure 13S for the attached electrode 26.

[0018] Each probe of the structure 13S has at least one attached electrode 26 which can be used for signal sensing and / or ablation. Each probe has a known length, and each attached electrode 26 is at a known location on its respective probe. At least one position sensor 29 is also attached to each probe 13, and the position sensors are substantially similar to one another. The position sensor 29 is typically a magnetic-based position sensor having at least one coil, and is typically a plurality of coils with orthogonal axes. A given sensor generates a signal indicating the location and orientation of the sensor in response to a magnetic field passing across the sensor. The magnetic field is generated by a plurality of magnetic coils 32 positioned within a location-finding pad 25 adjacent to the assembly 28. Figure 3, which is referenced in more detail below, includes an enlarged schematic view of probe 13A, along with its electrodes 26, position sensors 29, and attached linear conductors 33, which are described below.

[0019] Details of magnetic-based position sensing techniques are described in U.S. Patent 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, and 6,892,091.

[0020] In the disclosed example, at least one probe 13 has respective linear conductors 33 attached to the length of the probe, and the conductors function as open loops. In some configurations, two conductors 33 on separate probes may typically be connected together at the distal ends of the conductors, such that the open loop is substantially closed. A magnetic field from coil 32 across conductor 33 generates a signal between the ends of the open loop formed by the conductor, and these signals indicate the shape of the probe to which the conductor is attached.

[0021] System 10 includes one or more electrode patches 38 positioned for skin contact on patient 23. Measurements of the impedance between patch 38 and a given electrode 26 can be used to determine the location of the electrode and to identify whether the electrode is in contact with the tissue of wall 31. U.S. Patent No. 11,596,324 describes a method that can use the impedance between an electrode on a basket catheter and a patch on a patient's skin to identify whether the electrode is in contact with tissue within the lumen of an organ of the subject. Optionally, the impedance between intracardiac electrodes can be sensed to evaluate contact with the chamber wall.

[0022] Recorder 11 displays an electrogram 21 captured by body surface ECG electrodes 18 and an intracardiac electrogram (IEGM) that can be captured by electrodes 26 of catheter 14. Recorder 11 may include pacing capabilities for pacing the rhythm of the heart and / or may be electrically connected to an independent pacer.

[0023] System 10 may include an ablation energy generator 50 adapted to transmit ablation energy to one or more of the electrodes 26. The energy generated by the ablation energy generator 50 may include pulsed-field ablation (PFA) energy, including radiofrequency (RF) energy, or monopolar or bipolar high-voltage DC pulses that may be used to perform irreversible electroporation (IRE), but is not limited thereto.

[0024] The patient interface unit (PIU) 30 is an interface configured to establish electrical communication between a catheter, an electrophysiological device, a power source, and a workstation 55 that controls the operation of the system 10. The electrophysiological devices of the system 10 may include, for example, a plurality of catheters, location-specific pads 25, body surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally, the PIU 30 further includes processing capabilities for performing real-time calculations of the location of the catheter and performing ECG calculations.

[0025] The workstation 55 includes memory, a processor 22 having memory or storage device in which appropriate operating software is stored, and user interface functions. The processor 22 operates the system 10. The workstation 55 may optionally include a number of functions, including (1) modeling the endocardial anatomical structure in three dimensions (3D) and rendering a model or anatomical map 20 of the heart 12 or part thereof on a display device 27; (2) displaying an activation sequence (or other data) compiled from a recorded electrical record 21 on the display device 27 as a representative visual indicator or image superimposed on the rendered anatomical map 20; (3) displaying a presentation 39 incorporating real-time location and orientation values ​​of the distal end assembly 28 within the cardiac chambers 36; and (4) displaying areas of interest on the display device 27, such as the location where ablation energy was applied. One commercially available product that embodies the elements of System 10 is the CARTO(trademark) 3 system, available from Biosense Webster, Inc. 31 Technology Drive, Suite 200, Irvine, CA, 92618.

[0026] As described above, in the procedure shown in Figure 1, at least some electrodes 26 on the probe 13 may come into contact with the tissue of the heart 12. The following is a description of the algorithm by which the processor 22 determines the force exerted on the tissue by the selected electrodes and the corresponding opposing force exerted by the tissue.

[0027] Figure 2 is a flowchart 100 of the steps taken by the processor 22 when implementing an algorithm for determining the force exerted by probe 13A according to an example of the present disclosure, and Figure 3 is a schematic diagram of a portion of the probe. For simplicity and clarity, the following description assumes that probe 13A lies in a two-dimensional (2D) plane corresponding to the plane of paper in Figure 3. Those skilled in the art will be able to adapt this description as necessary for probes in three dimensions.

[0028] The algorithm models the probe as being divided into sections, each having its own termination, and the sections are connected together at their terminations. Each termination is assumed to function as a spring-like joint with a torsional spring constant j, and the termination is also referred to herein as a joint. In the following description, the probe is assumed to have N joints connected by N-1 sections, where N is a positive integer, and the joints are identified by index k, where k = 1, 2, ..., N. In the disclosed example, N = 10, but it will be understood that in other examples, N may be greater than or less than 10.

[0029] Therefore, Figure 3 shows a portion of probe 13A having joints k-2, k-1, k, k+1, k+2, where adjacent joints are connected by generally similar sections 80A, 80B, 80C, and 80D, commonly referred to as section 80. The probe is assumed to have at least one position sensor 29 and at least one electrode 26. As an example, the figure shows one position sensor 29 and two electrodes, namely electrode 26A and electrode 26B. Electrode 26A is shown to coincide with joint k, but generally, the electrodes and joints of a probe may or may not coincide.

[0030] An enlarged portion of probe 13A, including joints k-1, k, and k+1 connected by sections 80B and 80C, is shown at the bottom of the figure. At the bottom, sections 80B and 80C are depicted as linear connections 82B and 82C to more clearly show the forces acting on the joints.

[0031] In the initial step 102 of the flowchart, which may be performed before the procedure shown in Figure 1 is carried out, the processor 22 records the known parameters of the probe 13A. As described above, the algorithm assumes that the probe behaves as a spring and that the known parameters include the torsional spring constant j of the probe. The parameters also include the locations of the electrode 26, position sensor 29, and conductor 33 on the probe 13A.

[0032] The processor 22 also records the relative position coordinates of the electrode 26, position sensor 29, and conductor 33, and uses these coordinates to formulate data describing the shape of the probe 13A when it is in an unconstrained configuration, i.e., when there are no external forces acting on the probe other than forces due to gravity. The data for the unconstrained configuration may be in any convenient form, such as an ordered triple set and / or analytical formulas.

[0033] The processor 22 also divides the probe 13A into sections 80 that connect adjacent joints, as described above with reference to Figure 3, and records the location of the joints.

[0034] In procedure step 106, the physician 24 inserts the probe 13A into the patient 23's heart 12 until the probe is positioned at the desired target location where it makes contact with the heart tissue, and to assist the physician, the processor 22 may display a representation 39 of the probe on the display device 27.

[0035] The processor 22 may use signals from the probe sensor 29 and the conductor 33 to confirm that the probe is in the desired location. The processor 22 also measures the impedance between the electrode 26 and the patch 38, and uses the impedance measurement signal to calculate the location of the electrode 26 and identify the electrode 26 that is in contact with the tissue.

[0036] Contact with the tissue of the heart 12 deforms the shape of the probe 13A from its unconstrained shape recorded in the initial step 102. In step 106, the processor 22 uses the signal from the probe sensor 29, the conductor 33, and the impedance signal to locate the position of the portion of the probe 13A and formulate the deformed shape of the probe.

[0037] In step 106, the processor 22 identifies a first set G1 of joints in contact with tissue of the heart 12 and a second set G2 of joints not in contact with tissue. The first set G1 includes joints adjacent to the electrode 26 which has been determined to be in contact with tissue based on impedance measurements. The second set G2 includes the remaining joints of the probe 13A. A given electrode 26 may be determined to be in contact with tissue depending on the impedance between the electrode and a body surface electrode such as patch 38, as described above. U.S. Patent No. 10,398,348 describes a method for determining electrode contact using impedance.

[0038] A joint may be assumed to be in contact with tissue if it is between two contact electrodes, and not in contact with tissue if it is between two non-contact electrodes. If the joint is between a contact electrode and a non-contact electrode, it is assumed to have the properties (contact or non-contact) of the nearest electrode.

[0039] In analysis step 110, the processor 22 uses the deformed shape of the probe 13A and the known spring constant j of the probe to calculate the external force acting on each of the joints in contact with the tissue, i.e., each of the joints in the first set.

[0040] As shown in FIG. 3, joint k has the probe internal force given by Table I acting on the joint. In Table I, L k-1 and L k are respectively the lengths of the sections connected at joint k, that is, sections 80B and 80C of the probe. Also, in Table I, angle a k-1 , a k , and a k+1 are respectively the changes in the angles at joints k - 1, k, and k + 1 when probe 13A is deformed from its unconstrained state.

[0041]

Table 1

[0042] In addition to the forces listed in Table I, there are forces T k and T k-1 acting on joint k corresponding to the compressive forces in sections 80C and 80B respectively. Compressive forces T k and T k-1 are also described as F5 and F6.

[0043] Forces F1 to F6 are the probe internal forces acting on joint k. In addition to the probe internal forces, the probe has an external force F7 acting on joint k in its deformed state.

[0044] In its deformed state, probe 13A is in an equilibrium state, and thus, Equation (1) is applicable to all joints of the probe.

[0045]

Equation

[0046]

Equation

[0047] Since each force in equation (1) is a three-dimensional force, there are 3N equations corresponding to equation (1) for the N joints of probe 13A. As shown in Table I, all factors influencing the force are known, so the force for all joints

[0048]

number

[0049]

number

[0050]

number

[0051] N external forces corresponding to the number of sections of probe 13A

[0052]

number

[0053]

number

[0054] In the disclosed example, each external force

[0055]

number

[0056]

number

[0057]

number

[0058]

number

[0059] Line 90 indicates the probe direction at joint k, and it will be understood that this direction corresponds to the direction of the tangent line at joint k on the probe.

[0060] In the disclosed example, the joints in contact with the tissue, i.e., those joints within set G1, are assumed to have a minimum, i.e., zero or near-zero, parallel component, because the presence of fluid between a given joint and the tissue in contact with the joint reduces friction between them. In one example, the magnitude of the parallel component is assumed to be less than or equal to 10% of the magnitude of the perpendicular component.

[0061] Furthermore, joints that do not come into contact with tissue, i.e., joints within set G2, are assumed to have minimal, i.e., zero or near-zero orthogonal components, because there is no tissue to exert force on the non-contact joints. In one example, the magnitude of the orthogonal component is assumed to be less than 10% of the magnitude of the parallel component.

[0062] Using these assumptions, processor 22 performs the following:

[0063]

number

[0064]

number

[0065] In other words, processor 22 solves equation (4).

[0066]

number

[0067] Using the solution to equation (4), processor 22 calculates the following for each value of k from k=1, ..., N:

[0068]

number

[0069]

number

[0070] In the final pressure determination step 114, the processor 22 interpolates the forces at all N joints of the probe 13A. For each section between adjacent joints, the processor 22 uses the interpolated forces and the known length of each section to determine the pressure on the section as a force per unit length.

[0071] Since the electrodes 26 are in known locations on the probe 13A, the processor 22 can use the pressure found in step 114 to determine the force acting on each electrode 26.

[0072] A given electrode 26 can be used to ablate the tissue it is in contact with, and it is known that the dimensions of the ablated tissue depend on the force applied by the electrode. Therefore, if the procedure shown in Figure 1 is an ablation procedure, the processor 22 may be configured to adjust the duration and intensity of the ablation current passing through the electrode in accordance with the force from the electrode on the tissue in contact, as determined in step 114, in order to achieve desired dimensions, such as depth and diameter, for the tissue to be ablated.

[0073] Alternatively or additionally, as described above, the location of the tissue in contact with the electrode may be mapped by a processor 22 that determines the impedance between the skin patch 38 and the electrode using a given electrode 26. In the disclosed example, during the mapping procedure, the processor 22 records only the determined locations from the signal used to calculate the impedance if the force applied to the electrode exceeds a preset minimum value, as determined in step 114.

[0074] The above description of probe 13A assumes that each joint joins two sections. A person skilled in the art will be able to adapt the description with necessary modifications to include probes having joints that join more than two sections, such as probes having multiple linear sections connected at a common point, and probes having connected loops, such as assembly 28, and it is assumed that all such probes are included within the scope of this disclosure. [Examples]

[0075] Example 1. A method for performing a medical procedure, wherein the method is: To provide an elastic probe (13A) having a known spring constant for insertion into the body of a patient (23), wherein the probe comprises a plurality of electrodes (26) and at least one position sensor (29) at each location along the probe, When the probe is in an unconstrained state, the relative position coordinates of the electrode and at least one position sensor are recorded, Record changes in the relative position coordinates of one or more electrodes in contact with the tissue and at least one position sensor while the probe is inside the body and being deformed by contact with the patient's tissue. Calculating the shape of the probe in a deformed state in response to recorded changes, Calculating the forces exerted by the tissue on each of one or more electrodes in response to the known spring constant of the probe and the calculated shape of the probe in a deformed state, A method comprising controlling the reception of an electrical signal from tissue through one or more electrodes, or the application of an electrical signal to tissue through one or more electrodes, in response to a calculated force applied to each electrode.

[0076] Example 2. The method according to Example 1, wherein the known spring constant includes the torsional spring constant.

[0077] Example 3. The method according to Example 1, wherein, in an unrestrained state, only forces due to gravity act on the probe.

[0078] Example 4. The method according to Example 1, wherein at least one position sensor comprises at least one coil.

[0079] Example 5. The method according to Example 1, wherein at least one position sensor comprises a linear conductor attached to the length of the probe.

[0080] Example 6. The method according to Example 1, comprising recording a change in the relative spatial coordinates of one or more electrodes that are not in contact with tissue while the probe is in the body and being deformed by contact with tissue.

[0081] Example 7. The method according to Example 1, wherein calculating the respective forces exerted by the tissue on each of one or more electrodes includes identifying multiple locations on a probe acting as a spring-like joint in proximity to one or more electrodes, and calculating the external force on each of the joints, each location being associated with the respective tangent to the probe therein.

[0082] Example 8. The method of Example 7, wherein calculating the external forces acting on each joint includes calculating the internal probe forces acting on each joint in response to the calculated shape of the probe in a deformed state, such that the external forces are equal to the resultant force of the internal probe forces and are in opposite directions.

[0083] Example 9. The method of Example 7, wherein calculating the external force acting on each joint includes identifying a set of joints in contact with the tissue, and for each joint in the set, the first component of the external force parallel to the respective tangent is less than a predetermined value of the second component of the external force perpendicular to the respective tangent.

[0084] Example 10. The method according to Example 9, wherein the preset value is 10%.

[0085] Example 11. The method according to Example 9, wherein calculating the external forces acting on each of the joints includes identifying a further set of joints that are not in contact with the tissue, and for each joint in the further set, the third component of the external force perpendicular to each tangent is smaller than a further preset value of the fourth component of the external force parallel to each tangent.

[0086] Example 12. The method according to Example 11, wherein the preset value is 10%.

[0087] Example 13. The method according to Example 11, wherein calculating the external force acting on each joint includes determining the external force such that a formula containing a first component and a third component is minimized.

[0088] Example 14. A system for performing medical procedures, An elastic probe (13A) having a known spring constant for insertion into the body of a patient (23), wherein the probe comprises a plurality of electrodes (26) and at least one position sensor (29) at each location along the probe, A processor (22) is provided, and the processor is When the probe is in an unconstrained state, the relative position coordinates of the electrode and at least one position sensor are recorded, While the probe is inside the body and being deformed by contact with the patient's tissue, the change in the relative position coordinates between one or more electrodes in contact with the tissue and at least one position sensor is recorded. Calculating the shape of the probe in a deformed state in response to recorded changes, Calculating the forces exerted by the tissue on each of one or more electrodes in response to the known spring constant of the probe and the calculated shape of the probe in a deformed state, A system configured to control the reception of electrical signals from tissue via one or more electrodes, or the application of electrical signals to tissue via one or more electrodes, in response to the calculated force applied to each electrode.

[0089] Example 15. The system according to Example 14, wherein the known spring constant includes a torsional spring constant.

[0090] Example 16. The system according to Example 14, wherein, in an unconstrained state, only forces due to gravity act on the probe.

[0091] Example 17. The system according to Example 14, wherein at least one position sensor comprises at least one coil.

[0092] Example 18. The system according to Example 14, wherein at least one position sensor comprises a linear conductor attached to the length of the probe.

[0093] Example 19. The system according to Example 14, wherein the processor records changes in the relative location coordinates of one or more electrodes that are not in contact with tissue while the probe is in the body and being deformed by contact with tissue.

[0094] Example 20. The system according to Example 14, wherein calculating the respective forces exerted by the tissue on each of one or more electrodes includes identifying multiple locations on a probe acting as a spring-like joint in proximity to one or more electrodes, and calculating the external force on each of the joints, each location being associated with the respective tangent to the probe therein.

[0095] Example 21. The system according to Example 20, wherein calculating the external forces acting on each joint includes calculating the internal probe forces acting on each joint in response to the calculated shape of the probe in a deformed state, such that the external forces are equal to the resultant force of the internal probe forces and are in opposite directions.

[0096] Example 22. The system according to Example 20, wherein calculating the external force acting on each joint includes identifying a set of joints in contact with the tissue, and for each joint in the set, the first component of the external force parallel to the respective tangent is less than a preset value of the second component of the external force perpendicular to the respective tangent.

[0097] Example 23. The system described in Example 22, wherein the preset value is 10%.

[0098] Example 24. The system according to Example 14, wherein calculating the external forces acting on each joint includes identifying a further set of joints that are not in contact with the tissue, and for each joint in the further set, a third component of the external force perpendicular to each tangent is smaller than a further preset value of a fourth component of the external force parallel to each tangent.

[0099] Example 25. The system described in Example 24, wherein the preset value is 10%.

[0100] Example 26. The system according to Example 24, wherein calculating the external force acting on each joint includes determining the external force such that a formula containing a first component and a third component is minimized.

[0101] The embodiments described above are cited as examples, and this disclosure is not limited to those specifically illustrated and described above. Rather, the scope of this disclosure includes both combinations and partial combinations of the various features described above, as well as variations and modifications thereof not disclosed in the prior art, which would be conceivable to those skilled in the art by reading the above description.

[0102] [Implementation Method] (1) A method for performing a medical procedure, wherein the method is To provide an elastic probe having a known spring constant for insertion into a patient's body, wherein the probe comprises a plurality of electrodes and at least one position sensor at each location along the probe, When the probe is in an unconstrained state, the relative position coordinates of the electrode and the at least one position sensor are recorded. While the probe is inside the body and is deformed by contact with the patient's tissue, the change in the relative position coordinates between one or more of the electrodes in contact with the tissue and the at least one position sensor is recorded. In response to the recorded changes, the shape of the probe in the deformed state is calculated, Calculating the forces exerted by the tissue on each of the one or more electrodes in response to the known spring constant of the probe and the calculated shape of the probe in the deformed state, A method comprising controlling the reception of an electrical signal from the tissue through one or more of the electrodes, or the application of an electrical signal to the tissue through one or more of the electrodes, in response to the respective calculated forces applied to each of the electrodes. (2) The method according to Embodiment 1, wherein the known spring constant includes a torsional spring constant. (3) The method according to Embodiment 1, wherein in the unrestrained state, only forces due to gravity act on the probe. (4) The method according to Embodiment 1, wherein the at least one position sensor comprises at least one coil. (5) The method according to Embodiment 1, wherein the at least one position sensor comprises a linear conductor attached to the length of the probe.

[0103] (6) The method according to Embodiment 1, comprising recording a change in the relative location coordinates of one or more electrodes that are not in contact with the tissue while the probe is inside the body and being deformed by contact with the tissue. (7) The method according to Embodiment 1, wherein calculating the respective forces exerted by the tissue on each of the one or more electrodes includes identifying a plurality of locations on the probe acting as a spring-like joint in close proximity to the one or more electrodes, and calculating the external force on each of the joints, each of the locations being associated with a respective tangent to the probe therein. (8) The method according to Embodiment 7, wherein calculating the external force acting on each of the joints includes calculating the internal probe force acting on each of the joints in response to the calculated shape of the probe in the deformed state, such that the external force is equal to the resultant force of the internal probe forces and is in opposite directions. (9) The method according to Embodiment 7, wherein calculating the external force acting on each of the joints includes identifying a set of joints in contact with the tissue, wherein for each joint in the set, a first component of the external force parallel to the respective tangent is smaller than a preset value of a second component of the external force perpendicular to the respective tangent. (10) The method according to embodiment 9, wherein the preset value is 10%.

[0104] (11) The method according to Embodiment 9, wherein calculating the external force acting on each of the joints includes identifying a further set of joints that are not in contact with the tissue, and for each joint in the further set, a third component of the external force perpendicular to the respective tangent is smaller than a further preset value of a fourth component of the external force parallel to the respective tangent. (12) The method according to embodiment 11, wherein the preset value is 10%. (13) The method according to Embodiment 11, wherein calculating the external force acting on each of the joints is performed by determining the external force such that a formula including the first component and the third component is minimized. (14) A system for performing medical procedures, An elastic probe having a known spring constant for insertion into a patient's body, wherein the probe is equipped with a plurality of electrodes and at least one position sensor at each location along the probe, A processor is provided, and the processor is When the probe is in an unconstrained state, the relative position coordinates of the electrode and the at least one position sensor are recorded. While the probe is inside the body and is deformed by contact with the patient's tissue, the change in the relative position coordinates between one or more of the electrodes in contact with the tissue and at least one position sensor is recorded. In response to the recorded changes, the shape of the probe in the deformed state is calculated, In response to the known spring constant of the probe and the calculated shape of the probe in the deformed state, the forces exerted by the tissue on each of the one or more electrodes are calculated. A system configured to control the reception of an electrical signal from the tissue via one or more of the electrodes, or the application of an electrical signal to the tissue via one or more of the electrodes, in response to the calculated force applied to each of the electrodes. (15) The system according to Embodiment 14, wherein the known spring constant includes a torsional spring constant.

[0105] (16) The system according to embodiment 14, wherein in the unconstrained state, only forces due to gravity act on the probe. (17) The system according to embodiment 14, wherein the at least one position sensor comprises at least one coil. (18) The system according to embodiment 14, wherein the at least one position sensor comprises a linear conductor attached to the length of the probe. (19) The system according to Embodiment 14, wherein the processor records changes in the relative location coordinates of one or more electrodes that are not in contact with the tissue while the probe is inside the body and is deformed by contact with the tissue. (20) The system according to Embodiment 14, wherein calculating the respective forces exerted by the tissue on each of the one or more electrodes includes identifying a plurality of locations on the probe acting as a spring-like joint in close proximity to the one or more electrodes, and calculating the external force on each of the joints, each of the locations being associated with a respective tangent to the probe therein.

[0106] (21) The system according to embodiment 20, wherein calculating the external force acting on each of the joints includes calculating the internal probe force acting on each of the joints in response to the calculated shape of the probe in the deformed state, such that the external force is equal to the resultant force of the internal probe forces and is in opposite directions. (22) The system according to Embodiment 20, wherein calculating the external force acting on each of the joints includes identifying a set of joints in contact with the tissue, wherein for each joint in the set, a first component of the external force parallel to the respective tangent is smaller than a preset value of a second component of the external force perpendicular to the respective tangent. (23) The system according to embodiment 22, wherein the preset value is 10%. (24) The system according to Embodiment 14, wherein calculating the external force acting on each of the joints includes identifying a further set of joints that are not in contact with the tissue, and for each joint in the further set, a third component of the external force perpendicular to the respective tangent is smaller than a further preset value of a fourth component of the external force parallel to the respective tangent. (25) The system according to embodiment 24, wherein the preset value is 10%.

[0107] (26) The system according to Embodiment 24, wherein calculating the external force acting on each of the joints includes determining the external force such that a formula including the first component and the third component is minimized.

Claims

1. A system for determining tissue contact force during medical procedures, An elastic probe having a known spring constant for insertion into a patient's body, wherein the probe is equipped with a plurality of electrodes and at least one position sensor at each location along the probe, A processor is provided, and the processor is When the probe is in an unconstrained state, the relative position coordinates of the electrode and the at least one position sensor are recorded. While the probe is inside the body and is deformed by contact with the patient's tissue, the change in the relative position coordinates between one or more of the electrodes in contact with the tissue and at least one position sensor is recorded. In response to the recorded changes, the shape of the probe in the deformed state is calculated, In response to the known spring constant of the probe and the calculated shape of the probe in the deformed state, the forces exerted by the tissue on each of the one or more electrodes are calculated. A system configured to control the reception of an electrical signal from the tissue via one or more of the electrodes, or the application of an electrical signal to the tissue via one or more of the electrodes, in response to the calculated force applied to each of the electrodes.

2. The system according to claim 1, wherein the known spring constant includes a torsional spring constant.

3. The system according to claim 1, wherein in the unconstrained state, only forces due to gravity act on the probe.

4. The system according to claim 1, wherein the at least one position sensor comprises at least one coil.

5. The system according to claim 1, wherein the at least one position sensor comprises a linear conductor attached to the length of the probe.

6. The system according to claim 1, wherein the processor records changes in the relative spatial coordinates of one or more electrodes that are not in contact with the tissue while the probe is located inside the body and is deformed by contact with the tissue.

7. The system according to claim 1, wherein calculating the respective forces exerted by the tissue on each of the one or more electrodes includes identifying a plurality of locations on the probe acting as a spring-like joint in close proximity to the one or more electrodes, and calculating the external force on each of the joints, each of the locations being associated with a respective tangent to the probe therein.

8. The system according to claim 7, wherein calculating the external force acting on each of the joints includes calculating the internal probe force acting on each of the joints in response to the calculated shape of the probe in the deformed state, such that the external force is equal to the resultant force of the internal probe forces and is in opposite directions.

9. The system according to claim 7, wherein calculating the external force acting on each of the joints includes identifying a set of joints in contact with the tissue, wherein for each joint in the set, a first component of the external force parallel to the respective tangent is smaller than a preset value of a second component of the external force perpendicular to the respective tangent.

10. The system according to claim 1, wherein calculating the external force acting on each of the joints includes identifying a further set of joints not in contact with the tissue, and for each joint in the further set, a third component of the external force perpendicular to the respective tangent is smaller than a further preset value of a fourth component of the external force parallel to the respective tangent.

11. A method for calculating tissue contact force using a probe inserted into a patient's body, wherein the probe is an elastic probe having a known spring constant, and the probe comprises a plurality of electrodes and at least one position sensor at each location along the probe, and the method is When the probe is in an unconstrained state, the relative position coordinates of the electrode and the at least one position sensor are recorded. While the probe is inside the body and is deformed by contact with the patient's tissue, the change in the relative position coordinates between one or more of the electrodes in contact with the tissue and at least one position sensor is recorded. In response to the recorded changes, the shape of the probe in the deformed state is calculated, Calculating the forces exerted by the tissue on each of the one or more electrodes in response to the known spring constant of the probe and the calculated shape of the probe in the deformed state, A method comprising controlling the reception of an electrical signal from the tissue via one or more of the electrodes, or the application of an electrical signal to the tissue via one or more of the electrodes, in response to the calculated force applied to each of the electrodes.

12. The method according to claim 11, wherein the known spring constant includes a torsional spring constant.

13. The method according to claim 11, wherein, in the unconstrained state, only forces due to gravity act on the probe.

14. The method according to claim 11, wherein the at least one position sensor comprises at least one coil.

15. The method according to claim 11, wherein the at least one position sensor comprises a linear conductor attached to the length of the probe.

16. The method according to claim 11, comprising recording a change in the relative spatial coordinates of one or more electrodes that are not in contact with the tissue while the probe is located inside the body and is deformed by contact with the tissue.

17. The method of claim 11, wherein calculating the respective forces exerted by the tissue on each of the one or more electrodes includes identifying a plurality of locations on the probe acting as a spring-like joint in close proximity to the one or more electrodes, and calculating the external force on each of the joints, each of the locations being associated with a respective tangent to the probe therein.

18. The method according to claim 17, wherein calculating the external force acting on each of the joints includes calculating the internal probe force acting on each of the joints in response to the calculated shape of the probe in the deformed state, such that the external force is equal to the resultant force of the internal probe forces and is in opposite directions.

19. The method according to claim 17, wherein calculating the external force acting on each of the joints includes identifying a set of joints in contact with the tissue, wherein for each joint in the set, a first component of the external force parallel to the respective tangent is smaller than a preset value of a second component of the external force perpendicular to the respective tangent.

20. The method according to claim 19, wherein calculating the external force acting on each of the joints includes identifying a further set of joints that are not in contact with the tissue, and for each joint in the further set, a third component of the external force perpendicular to the respective tangent is smaller than a further preset value of a fourth component of the external force parallel to the respective tangent.

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