WO2025243077A1

WO2025243077A1 - Jig and method to calibrate contact force of basket catheter assembly

Info

Publication number: WO2025243077A1
Application number: PCT/IB2024/061827
Authority: WO
Inventors: Vadim Gliner; Ilya Sitnitsky; Assaf Govari
Original assignee: Biosense Webster Israel Ltd
Current assignee: Biosense Webster Israel Ltd
Priority date: 2024-05-20
Filing date: 2024-11-26
Publication date: 2025-11-27
Anticipated expiration: 2026-11-20

Abstract

Apparatus for calibrating a catheter, the apparatus including (i) a catheter mounting device configured to fixedly mount a distal end of a shaft of the catheter, (ii) a grasper configured to couple an expandable distal-end assembly of the catheter to a gauge, the gauge configured to measure a force on the grasper by the expandable distal-end assembly in response to translation of the gauge along one or more mutually orthogonal axes, (iii) a mechanical stage configured to translate the gauge along three mutually orthogonal axes, and (iv) a processor, configured to generate calibration data for the catheter, the calibration data associating multiple translations of the mechanical stage with corresponding force measurements measured by the gauge.

Description

JIG AND METHOD TO CALIBRATE CONTACT FORCE OF BASKET

CATHETER ASSEMBLY

FIELD OF THE DISCLOSURE

The present disclosure relates generally to invasive medical probes , and particularly to the calibration of contact force of cardiac catheters .

BACKGROUND OF THE DISCLOSURE

A wall tissue of a cavity of an organ of a patient , such as a cardiac chamber , can be electroanatomically ( EA) mapped and/or electrically ablated using a catheter having multiple electrodes fitted at an expandable distal end assembly of the catheter . In a mapping and/or ablation procedure in a cardiac chamber , the physician expands the assembly and manipulates the expanded distal end assembly for the electrodes to contact chamber walls to acquire and/or apply electrical signals . The quality of electrical mapping and/or ablation depends on the contact force of the distal end assembly with wall tissue . The expandable assembly is flexible and typically deforms when pressed against the chamber wall , which yields complicated behavior of contact force .

The present disclosure will be more fully understood from the following detailed description of the examples thereof , taken together with the drawings , in which :

BRIEF DESCRIPTION OF THE DRAWINGS

Fig . 1 is a schematic , pictorial illustration of a catheter-based electroanatomical ( EA) mapping and ablation system, according to an example of the present disclosure ;

Figs . 2A-2D are schematic , pictorial illustrations of a catheter expandable distal end assembly ( i ) in free space, (ii) compressed against tissue, (iii) elongated, and (iv) warped by contacting tissue, respectively, according to examples of the present disclosure;

Fig. 3 is a schematic block diagram of a calibration apparatus of the contact force of the catheter assembly of Fig. 2, according to an example of the present disclosure;

Fig. 4 is a schematic figure of a calibration jig used by the calibration apparatus of Fig. 3, according to an example of the present disclosure;

Fig. 5 is a schematic, pictorial illustration of the catheter expandable distal end assembly of Fig. 2 being wrapped by the calibration jig of Fig. 4, according to an example of the present disclosure; and

Fig. 6 is a flow chart that schematically illustrates a method to calibrate the contact force of the catheter assembly of Fig. 2 using the calibration apparatus of Fig. 3, according to an example of the present disclosure.

DETAILED DESCRIPTION OF EXAMPLES

OVERVIEW

EA mapping and ablation are, respectively, diagnostic and treatment cardiac procedures that may be used to restore a heart's sinus rhythm by applying a catheter. During the diagnostic and/or treatment procedure, a physician manipulates the catheter so that electrodes on the catheter' s distal end contact selected sites within the heart, so that, when contact is achieved, electrical signals may be acquired or applied.

To both accelerate and simplify the procedure, it is advantageous to use a catheter having a distal end assembly with multiple electrodes, such as a catheter with a basket distal end assembly, or a balloon distal end assembly, so that multiple sites may be contacted simultaneously.

The distal end assembly, e.g., of a basket-type catheter, may be inserted into the heart by a minimally invasive method, such as insertion through a femoral artery. The physician manipulates the proximal end of the catheter shaft to position the assembly at a desired location inside the heart and to engage the electrodes against the tissue with a desired force.

While inside a cardiac chamber blood pool, the basket (or balloon) assembly has a generally spherical shape and is aligned with the distal end of the shaft. The assembly may change shape and/or orientation due to the contact force exerted by the tissue. For example, the spheroid shape may change into (i) an oblate shape by an axial compression force against wall tissue, (ii) a prolate shape due to a radial compression force by wall tissue (e.g., inside a pulmonary vein) , or may (iii) a combination of tilt relative to the distal end of the shaft and a distortion of the basket shape, when the applied contact force is asymmetrical. One example is shear due to friction when dragging the catheter along the chamber wall . Non- axial or other asymmetrical forces applied to the basket shape will lead to asymmetrical bending of the basket shape, e.g., warping of the basket shape.

The changed assembly shape and/or orientation (e.g., warping) , due to the contact force, can be sensed using position sensors disposed over the distal end assembly. However, it may be difficult to relate signals from position sensors to an estimation of the size and direction of the force exerted by the distal end assembly, which includes the forces described above and a combination thereof . As a result , it may be difficult for a physician to ensure the quality of diagnostic and/or treatment signals acquired from and/or applied to , respectively, the cardiac tissue .

Examples of the present disclosure that are described herein provide a calibration apparatus and method to calibrate the detection of the contact force of an expandable distal end assembly . The disclosed j ig enables the simulation of asymmetrical and/or non-axial forces applied to the basket . The calibration apparatus includes a j ig and a processor associated with the j ig . The j ig enables controllably deforming a distal end assembly in a plurality of different 3D directions while measuring the force exerted on the distal end assembly due to the deformation . The relationship established between the controlled deformations and measured force may later be used to determine force based on a detected deformation . The deformation is known based on position sensors on the spline and the known mechanical model of the splines . Based on your identified shape and the information that you established during calibration, a processor can determine the direction and magnitude of the force applied on the distal end assembly . The j ig enables the reconstruction of relations between shape and/or orientation, including warp, and force to calibrate the various forces experienced by the assembly inside a cardiac chamber to the signals received from the multiple position sensors disposed over the assembly .

In an example , a calibration apparatus of the contact force of a catheter assembly is provided . The apparatus comprises a j ig comprising a 3D force gauge coupled to an XYZ mechanical stage configured to translate the force gauge along three mutually orthogonal directions . A grasper is used to couple the distal end assembly, at its distal edge , to the 3D force gauge .

The j ig includes , an XYZ stage , a 3D force gauge , a catheter shaft mounting device , and a grasper that is configured to couple a distal end of a distal end assembly to the 3D force gauge . The catheter shaft mounting device holds the shaft over the XYZ stage . The 3D force gauge is mounted on the XYZ stage on one end and coupled to the distal end of the distal end assembly . As the 3D force sensor is shifted based on movement of the XYZ stage , the distal end assembly is pulled and/or pushed in different directions leading to deformation of the distal end assembly as compared to its neutral shape . In another example , the XYZ mechanical stage is coupled to the catheter shaft mounting device and the XYZ mechanical stage is configured to translate the shaft along three mutually orthogonal directions while the force gauge is fixed in place to the ig . In yet another embodiment , each of the force gauge and shaft is translated in at least one XYZ direction .

Using the XYZ stage , the processor can operate the j ig to selectively push, pull , and/or deflect the distal end assembly in a defined manner . During the calibration apparatus ' s operation, the 3D force gauge senses the applied force due to the selective maneuvering of the distal end assembly .

Position sensors on the distal end assembly, along with a mechanical model of the distal end assembly, enable tracking of the spline ' s deformation and deflection and the distal end assembly ' s deflection . The processor receives the force-related data from the 3D force gauge in the j ig and the shape and orientation data based on output from the plurality of position sensors located over the distal end assembly, from which the processor forms a correspondence between the two sets of data , i . e . , between the force and resulting shape and orientation of distal end assembly, based on sensed location and orientation data . Changes in shape and orientation may be in the form of compression, elongation and/or deflection of the distal end assembly . The correspondence may be used to find the 3D force on the distal end assembly of a basket-type catheter based on a change in shape of the distal end assembly as compared to its shape when no forces are applied on the catheter .

CLINICAL SYSTEM DESCRIPTION

Fig . 1 is a schematic , pictorial illustration of a catheter-based electroanatomical ( EA) mapping and ablation system 10 , according to an example of the present disclosure .

System 10 includes one or more catheters that are percutaneously inserted by physician 24 through the patient ' s vascular system into a chamber of a heart 12 . Typically, a delivery sheath catheter is inserted into the chamber near a desired location in heart 12 . Thereafter, one or more catheters , in turn, can be inserted into the delivery sheath catheter to arrive at the desired location .

The one or more catheters may include catheters dedicated for sensing intracardiac electrogram signals , catheters dedicated for ablating and/or catheters dedicated for both sensing and ablating . An example basket catheter 14 that is configured for sensing the electrograms is illustrated herein. As seen in inset 45, physician 24 brings a basket type of expandable distal end assembly 28 fitted on a shaft 44 of catheter 14 into contact with the heart wall for sensing a target site in heart 12. For ablation, physician 24 similarly brings a distal end of an ablation catheter to a target site for ablating.

As seen in inset 65, catheter 14 includes multiple electrodes 26 distributed over a plurality of splines 22 at expandable distal end assembly 28 and configured to sense electrograms. Catheter 14 additionally includes (i) a proximal position sensor 29 (e.g., a magnetic position sensor in the form of a single axis sensor (SAS) 29) embedded in a distal end 46 of shaft 44 near expandable distal end assembly 28, and (ii) three distal position sensors 39 (e.g., SAS 39 comprising a single EMC) to track the position of the distal end of expandable distal end assembly 28. Optionally, and preferably, position sensors 29 and 39 are magnetic-based position sensors that include magnetic coils for sensing three-dimensional (3D) position.

Figs. 2B, 2C and 2D below show two scenarios where expandable distal end assembly 28 applies a contact force on tissue. In Fig. 2B the force results in distal end assembly contraction into an oblate shape. In Fig. 2C the force results in elongation into a prolate shape. In Fig. 2D the force is estimated from the expandable distal end assembly's warp relative to the distal end of the shaft.

In the disclosed contact force estimation technique, the EMCs of distal and proximal sensors 39 and 29 are operated in a transmitter-receiver mode to obtain signals indicative of the above changes in shape and/or orientation of the distal end assembly due to the experienced contact forces. The relative orientation is manifested by an angle formed between distal end 46 and a longitudinal axis 42 of expandable assembly 28 (to a distal edge 16 of the assembly) .

In the transmitter-receiver mode, one EMC (e.g., sensor 29) emits magnetic fields, and the other EMC (e.g., sensor 39) outputs position indicative electrical signals in response to receiving the magnetic fields . This transmitter-receiver mode, used by a processor, yields more accurate location and/or orientation data of assembly 28 relative to distal end 46 of shaft 44 than data yielded by using EMCs with a magnetic field source that is external to the patient's body.

Magnetic position sensors (29, 39) may also be operated together with an external location pad 25 that includes a plurality of magnetic coils 32 configured to generate magnetic fields in a predefined working volume. The frequencies of these fields are different from any given frequency used in the local transmitter-receiver mode for contact force detection, thus eliminating confusion between signals. Using the operation with external location pad 25 (at a unique frequency for each EMC) , the processor can determine the position of EMCs 39 on a coordinate system of the position tracking system.

Details of the magnetic-based position sensing technology are described in U.S. Patent Nos. 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.

System 10 includes one or more electrode patches 38 positioned for skin contact on patient 23 to establish a location reference for location pad 25 as well as impedance-based tracking of electrodes 26. For impedancebased tracking, electrical current is directed toward electrodes 26 and sensed at electrode skin patches 38, such that the location of each electrode can be triangulated via electrode patches 38. Details of the impedance-based location tracking technology are described in US Patent Nos. 7,536,218; 7,756,576; 7,848,787; 7,869,865; and 8,456, 182.

A recorder 11 displays electrograms 21 captured with body surface ECG electrodes 18 and intracardiac electrograms captured with electrodes 26 of catheter 14. Recorder 11 may include pacing capability for pacing the heart rhythm and/or may be electrically connected to a standalone pacer.

System 10 may include an ablation energy generator 50 that is adapted to conduct ablative energy to one or more electrodes at a distal tip of a catheter configured for ablating. Energy produced by ablation energy generator 50 may include, but is not limited to, radiofrequency (RE) energy or pulsed-field ablation (PEA) energy, including monopolar or bipolar high-voltage DC pulses that may be used to effect irreversible electroporation (IRE) , or combinations thereof.

Patient interface unit (PIU) 30 is configured to establish electrical communication between catheters, electrophysiological equipment, power supply and a workstation 55 for controlling the operation of system 10. Electrophysiological equipment of system 10 may include, for example, multiple catheters, location pad 25, body surface ECG electrodes 18, electrode patches 38, ablation energy generator 50, and recorder 11. Optionally, and preferably, PIU 30 additionally includes processing capability for implementing real-time computations of catheter locations and for performing ECG calculations. Workstation 55 includes memory 57, processor unit 56 with memory or storage with appropriate operating software loaded therein, and user interface capability. Workstation 55 may provide multiple functions, optionally including (i) modeling endocardial anatomy in three-dimensions (3D) and rendering the model or anatomical map 20 for display on a display device 27, (ii) displaying on display device 27 activation sequences (or other data) compiled from recorded electrograms 21 in representative visual indicia or imagery superimposed on the rendered anatomical map 20, (iii) displaying real-time location and/or orientation of multiple catheters within the heart chamber, and (iv) displaying on display device 27 sites of interest such as places where ablation energy has been applied. One commercial product embodying elements of the system 10 is available as the CARTO™ 3 System, available from Biosense Webster, Inc., 31A Technology Drive, Irvine, CA 92618.

ESTIMATION OF CONTACT FORCE OF CATHETER EXPANDABLE

ASSEMBLY

Figs. 2A-2D are schematic, pictorial illustrations of a catheter expandable distal end assembly 281 (i) in free space, (ii) compressed against tissue 47, (iii) elongated, and (iv) warped by contacting tissue 47, respectively, according to examples of the present disclosure. Position sensors on the splines of the expandable distal end assembly 281 output, along with a mechanical model of splines, enable tracking deformation of the splines and deflection of the distal end assembly 281.

Expandable distal end assembly 281 is formed by splines 222 and comprises three distal EMCs 239, and a proximal EMC 229. In the figures, an annular element 206 is coupled or integral to the distal ends of the splines, as shown in the inset of Fig. 2A. In the example shown in the inset, the splines, and the annular element are typically formed from a single Nitinol tube.

In Fig. 2A, expandable distal end assembly 281 is in free space and has a given first length 241. In this example, the calibration technique employs the three EMCs 239 distributed on the assembly's distal ends in three different XYZ orientations (e.g. , on three different splines in the case of an expandable basket assembly) , which enables sensing the assembly's 3D shape and/or orientation (e.g., of the basket assembly of the catheter) relative to the distal end of the catheter's shaft.

In the disclosed method, the processor uses the local transmitter-receiver mode by using proximal EMC 229 to transmit signals and distal electromagnetic coils (EMCs) 239, disposed on the expandable assembly, to generate position indicative signals responsively. Using the signals, the processor calculates the relative position of EMCs 239 relative to EMC 229.

The processor operates the multiple position sensors located over the distal end assembly to receive signals indicative of the resulting shape and/or orientations of the expandable distal end assembly. The sensors generate the location-indicative signals in response to transmission from at least one electromagnetic coil (EMC) disposed over the distal end of the catheter shaft. This transmitterreceiver local mode yields accurate estimations (e.g., submillimeter) .

In Fig. 2B, the elastic expandable distal end assembly 281, once pressed head-on against tissue 47 (e.g. , with some of electrodes 226 brought into firm contact with wall tissue) , contracts into a second, shorter, length 242.

The transmitter-receiver mode of the EMCs 239 and 229 enables accurate determination of the amount of expandable distal end assembly contraction (e.g., length 241 minus length 242 ) .

In Fig. 2C, the elastic expandable distal end assembly 281 may be elongated, e.g. , when pulled, into a longer length 243. Such a scenario is typical in cases of pulmonary vein isolation (PVI) procedures, where the basket in the ostium of the vein is radially compressed by the cylindrical wall of the vein. Some distal electrodes 226 are used in this way to electrically ablate an ostium of a PV in a left atrium to eliminate an arrhythmia.

The transmitter-receiver mode of EMCs 239 and 229 enables accurate determination of the amount of expandable distal end assembly elongation (e.g. , length 243 minus length 241 ) .

In Fig. 2D, expandable distal end assembly 281 is brought into side contact with tissue 47. As a result, expandable distal end assembly 281 is tilted, or bent, from its zero-angle orientation (as seen in Fig. 2A) into an angle 250 (an angle between a longitudinal axis 204 of the distal end of shaft 244 and an axis 256 of the expandable distal end assembly) . In addition to being tilted, the flexible cage of assembly 281 (e.g. , the arrangement of splines 222) is deformed. Such a scenario where the assembly is warped may be typical in cases when only a portion of the distal end assembly 281 is pressing against the wall or is being dragged along the wall..

Using the location data from EMCs 239, a processor can estimate the contact force using empirical data comprising calibration of the forces against expandable distal end assembly warp, as described in Figs . 4 to 6 . The processor may use weights to interpolate between calibration values . In such a case , a memory of the system is configured to store a relationship between EMC output and contact force based on the empirical data . The processor of system 10 is configured to use the stored empirical data to relate EMC output to contact force during a clinical procedure .

CALIBRATION APPARATUS DESCRIPTION

Fig . 3 is a schematic block diagram of a calibration appartus 300 of the contact force of a catheter assembly 281 of Fig . 2 , according to examples of the present disclosure .

Apparatus 300 comprises a j ig 400 , a detailed view of which is shown in Fig . 4 . As seen in Fig . 3 , ig 400 comprises a 3D force gauge 436 coupled to an XYZ mechanical stage 414 configured to translate the base along three mutually orthogonal directions . As further seen, distal end assembly 281 is coupled to force gauge 436 at the annular element 206 of assembly 281 using a grasping set-up 444 .

Using XYZ stage 414 , j ig 400 is operable by a processor 436 to selectively push, pull and/or deflect distal end assembly 281 in a defined manner . During operation of the calibration apparatus , 3D force gauge 436 senses the applied force due to the selective maneuvering of the distal end assembly 281 .

In the shown exmaple , the three SASs 239 on distal end assembly 281 generate signals indicative of their locations and/or orientations relative to SAS 229 that is statically held by the shaft . A processor 334 transmits data for operating j ig 400 , as well as driving signals for SAS 229 . In general , other types of position sensors can be used instead of SASs 229 and 239 .

The processor receives force-related data from the 3D force gauge 436 in the j ig . The processor also receives the location and/or orientation data from each sensor 239 relative to the distal end, and the processor forms a correspondence ( e . g . , a relation) between the two sets of data , i . e . , between the force and the compression, elongation and/or deflection of distal end assembly 281 based on sensed location and/or orientation data . The correspondence may be used to find the 3D force on the distal end assembly of a bas ket-type catheter for differently shaped deflections and bending of the distal end assembly, for the same type of catheters used in a medical procedure .

CALIBRATION JIG

Fig . 4 is a schematic figure of calibration ig 400 used by calibration apparatus 300 of Fig . 3 , according to an example of the present disclosure . Calibration j ig 400 is used to move assembly 281 and measure resulting force on the assembly, to calibrate the forces that assembly 281 experiences inside a heart .

Jig 400 comprises a base 420 coupled to XYZ stage 414 . Stage 414 can move base 420 along each direction independently of the other two directions . Stage 414 is fixed to a frame 415 of j ig 400 . On its distal end, assembly 281 is coupled to the 3D force sensor 436 with a grasper 447 , as seen in inset 425 . Shaft 244 is held in place by a mounting device 417 .

Force gauge 436 is fixedly held inside a case 437 that is rigidly coupled to base 420 of XYZ stage . As further seen in inset 425, force gauge 436 is coupled to annular element 206 of expandable distal end assembly 281 via grasping element 444 comprising the grasper 447. The grasper includes a pin 445 and a cable 448 attached to the pin, a tube 446, e.g., silicon tube, a pusher element 449, and a seat 440. Cable 448, pin 445, and pusher element 449 together provide a collapsing assembly for collapsing tube 446 along its longitudinal axis. The seat is mounted on the force gauge 436 and couples grasper 447 to the force gauge 436 inside case 437. Cable 448 extends through tube 446 and pusher element 449. The pin 445 and tube 446 are inserted through the annular element 206 of the distal end assembly 281. Pusher element 449 compresses then the tube 446. A locking element also locks the pusher element 449 in place. The tube 446 compresses and sandwiches the annular element 206. The cable 448 and pusher element 449 are coupled to the seat 440. This gives the jig a good grip while avoiding mechanically damaging the annular element 206.

Using the above coupling scheme, force gauge 436 is configured to indicate a 3D force on the expandable distal end assembly 281 in response to the translation of base 420 along one or more directions .

Fig. 4 is brought by way of example. Other implementations may be possible, such as a different way to hold the catheter and a different way to couple the catheter to the force gauge.

Fig. 5 is a schematic, pictorial illustration of the catheter expandable distal end assembly 281 of Fig. 2 being deformed, e.g., warped by the calibration jig 400 of Fig. 4, according to an example of the present disclosure.

Jig 400 has catheter mounting device 417 configured to fixedly mount the distal end of a catheter's shaft 244. The expandable assembly 281 is flexible and therefore deforms when pulled aside by the jig (via grasper 447 that holds the assembly's annular element 206 using a tube made of a flexible material, e,g. a silicon tube 446 and pusher 449) . The deformation imitates the complicated behavior of the assembly under variable contact force applied by wall tissue, as seen, for example, in Fig. 2D above. The force applied by the jig is conveyed to the force gauge 426 using wire 448.

A METHOD FOR ESTIMATING CONTACT FORCE OF CATHETER EXPANDABLE ASSEMBLY

Fig. 6 is a flow chart that schematically illustrates a method to calibrate the contact force of catheter assembly 281 of Fig. 2 using the calibration apparatus 300 of Fig. 3, according to an example of the present disclosure. The algorithm, according to the presented example, carries out a process that begins with mechanically coupling expandable distal end assembly 281 to jig 400, and electrically connecting distal end assembly 281 of the catheter to calibration apparatus 300 (e.g. , to drive EMC 229 and receive position signals from EMCs 239) at a calibration preparation step 502.

Next, processor 334 runs the below-described calibration procedure using calibration apparatus 300.

At jig translation step 504, processor 334 has jig 400 translating base 420 according to a preplanned calibration scheme .

At signal acquisition step 506, processor 334 receives location and/or orientation indicative signals acquired by EMCs 239 implemented in a local transmitter-receiver mode as described above. At 3D force reading acquisition step 508, processor 334 acquires (e.g., receives) a 3D force reading from gauge 436.

Processor 334 relates the 3D translation of base 420 to the location and/or orientation indicative signals at a first output relating step 510. Optionally, a shape of the distal end assembly is determined based on the 3D translation of base 420 and/or the location and/or orientation indicative signals.

Processor 334 relates the measured 3D force on assembly 28 to the 3D translation of base 420, at a second output relating step 512.

Based on steps 510 and 512, processor 334 relates the measured 3D force on assembly 28 to the respective location and/or orientation indicative signals at a third output relating step 514.

Finally, at calibration data storing step 516, processor 334 stores the relation of step 514 in the memory of the calibration apparatus.

The flow chart shown in Fig. 6 is applied to a basket catheter for the sake of conceptual clarity. The present example may be applied, mutatis mutandis , to a balloon catheter or other types of multi-electrode distal end assemblies that carry position sensors.

EXAMPLES

Example 1

Apparatus (300) for calibrating a catheter (214) , the apparatus (300) including (i) a catheter mounting device (417) configured to fixedly mount a distal end of a shaft (244) of the catheter (214) , (ii) a grasper (447) configured to couple an expandable distal-end assembly (281) to a gauge (436) wherein the coupling is configured to enable applying a pulling force on the distal end, the gauge (436) configured to measure a force on the grasper (447) by the expandable distal-end assembly (281) in response to translation between the shaft and the gauge (436) along one or more mutually orthogonal axes, (iii) a mechanical stage (414) configured to translate one or more of the gauge (436) and the shaft (244) along three mutually orthogonal axes, and (iv) a processor (334) , configured to generate calibration data for the catheter (214) , the calibration data associating multiple translations of the mechanical stage (414) with corresponding force measurements measured by the gauge (436) .

Example 2

The apparatus (300) according to example 1, wherein the mechanical stage (414) is configured to independently translate the gauge (436) along each of the three mutually orthogonal axes .

Example 3

The apparatus (300) according to any of examples 1 and 2, wherein the mechanical stage (414) is configured to pull the distal end assembly.

Example 4 The apparatus (300) according to any of examples 1 and 2, wherein the mechanical stage (414) is configured to warp the distal end assembly.

Example 5

The apparatus (300) according to any of examples 1 through 4, wherein, in generating the calibration data, the processor (334) is further configured to associate the translations and the force measurements with corresponding signals received from position sensors (239) disposed on the expandable distal-end assembly (281) , the signals indicative of respective positions of the position sensors (239) .

Example 6

The apparatus (300) according to any of examples 1 through 5, wherein the processor (334) is configured to associate the signals to the force measurements by generating (i) a first look-up table associating between the signals and the respective translations and (ii) a second look-up table associating between the translations and the force measurements .

Example 7

The apparatus (300) according to example 6, wherein the processor (334) is configured to combine the first and second look-up tables into a third look-up table that associates between the signals and the force measurements. Example 8

The apparatus (300) according to any of examples 1 through 7, wherein the position sensors (239) are configured to generate the signals in response to receiving a signal transmitted by one or more coils (229) disposed on a shaft (244) of the catheter (214) .

Example 9

The apparatus (300) according to any of examples 1 through 8, wherein the force measurements comprise vectors in 3D space.

Example 10

The apparatus (300) according to any of examples 1 through 9, wherein the gauge (436) comprises a 3D load cell .

Example 11

The apparatus (300) according to any of examples 1 through 10, wherein the expandable distal-end assembly (281) is one of a basket assembly and a balloon assembly.

Example 12

The apparatus (300) according to any of examples 1 through 11, wherein the grasper (447) is configured to couple the expandable distal-end assembly (281) using a tube (446) made of a flexible material, the tube configured to be inserted to the assembly (281) via an annular element (206) of the assembely (281) .

Example 13

The apparatus (300) according to any of examples 1 through 12, wherein the the gauge (436) is configured to measure the force on the grasper (447) by the gauge being coupled to the graspr (447) using a cable (448) extending through the tube (446) .

Example 14

A calibrating method includes fixedly mounting a distal end of a shaft (244) of a catheter (214) . An expandable distal-end assembly (281) of the catheter (214) is coupled to a gauge (436) , the gauge configured to measure a force on the expandable distal-end assembly (281) in response to translation of the gauge (436) along one or more mutually orthogonal axes. The gauge (436) is trnanslated along three mutually orthogonal axes. Calibration data is generated for the catheter (214) , the calibration data associating multiple translations with corresponding force measurements measured by the gauge (436) .

Although the examples described herein mainly address cardiac diagnostic applications, the methods and systems described herein can also be used in other medical applications .

It will be appreciated that the examples described above are cited by way of example, and that the present disclosure is not limited to what has been particularly shown and described hereinabove . Rather, the scope of the present disclosure includes both combinations and subcombinations of the various features described hereinabove , as well as variations and modifications thereof which would occur to persons s killed in the art upon reading the foregoing description and which are not disclosed in the prior art .

Claims

1 . Apparatus for calibrating a catheter , the apparatus comprisin : a catheter mounting device configured to fixedly mount a distal end of a shaft of the catheter ; a grasper configured to couple a distal end of an expandable distal-end assembly of the catheter to a gauge , wherein the coupling is configured to enable applying a pulling force on the distal end; the gauge configured to measure a force on the grasper by the expandable distal-end assembly in response to translation between the shaft and the gauge along one or more mutually orthogonal axes ; a mechanical stage configured to translate one or more of the gauge and the shaft along three mutually orthogonal axes ; and a processor, configured to generate calibration data for the catheter, the calibration data associating multiple translations of the mechanical stage with corresponding force measurements measured by the gauge .

2 . The apparatus according to claim 1 , wherein the mechanical stage is configured to independently translate the gauge along each of the three mutually orthogonal axes .

3 . The apparatus according to claim 2 , wherein the mechanical stage is configured to pull the distal end assembly .

4 . The apparatus according to claim 2 , wherein the mechanical stage is configured to warp the distal end assembly .

5 . The apparatus according to claim 1 , wherein, in generating the calibration data, the processor is further configured to associate the translations and the force measurements with corresponding signals received from position sensors disposed on the expandable distal-end assembly, the signals indicative of respective positions of the position sensors .

6 . The apparatus according to claim 5 , wherein the processor is configured to associate the signals to the force measurements by generating ( i ) a first look-up table associating between the signals and the respective translations and ( ii ) a second look-up table associating between the translations and the force measurements .

7 . The apparatus according to claim 6 , wherein the processor is configured to combine the first and second look-up tables into a third look-up table that associates between the signals and the force measurements .

8 . The apparatus according to claim 6 , wherein the position sensors are configured to generate the signals in response to receiving a signal transmitted by one or more coils disposed on a shaft of the catheter .

9 . The apparatus according to claim 1 , wherein the force measurements comprise vectors in 3D space .

10 . The apparatus according to claim 1 , wherein the gauge comprises a 3D load cell .

11 . The apparatus according to claim 1 , wherein the expandable distal-end assembly is one of a bas ket assembly and a balloon assembly .

12 . The apparatus according to claim 1 , wherein the grasper is configured to couple the expandable distal-end assembly using a tube made of a flexible material , a collapsing assembly configured to collapse the flexible tube , the tube configured to be inserted through an annular element at a distal end of the assembly and to collapse on either side of the annular element .

13 . The apparatus according to claim 12 , wherein the the gauge is configured to measure the force on the grasper by the gauge being coupled to the graspr using a cable extending through the tube .

14 . A calibrating method, comprising : fixedly mounting a distal end of a shaft of a catheter ; coupling an expandable distal-end assembly of the catheter to a gauge , wherein the coupling is configured to enable applying a pulling force on the expandable distal end assembly, the gauge configured to measure a force on the expandable distal-end assembly in response to translation of the gauge along one or more mutually orthogonal axes ; translating one or more of the gauge and the shaft along three mutually orthogonal axes ; and generating calibration data for the catheter , the calibration data associating multiple translations with corresponding force measurements measured by the gauge .

15 . The method according to claim 14 , and comprising independently translating the gauge along each of the three mutually orthogonal axes .

16 . The method according to claim 15 , and comprising pulling the distal end assembly .

17 . The method according to claim 15 , and comprising warping the distal end assembly .

18 . The method according to claim 14 , and comprising, in generating the calibration data , associating the translations and the force measurements with corresponding signals received from position sensors disposed on the expandable distal-end assembly, the signals indicative of respective positions of the position sensors .

19 . The method according to claim 18 , wherein associating the signals to the force measurements comprises generating ( i ) a first look-up table associating between the signals and the respective translations and ( ii ) a second look-up table associating between the translations and the force measurements .

20 . The method according to claim 19 , and comprising combining the first and second look-up tables into a third look-up table that associates between the signals and the force measurements .

21 . The method according to claim 14 , wherein the force measurements comprise vectors in 3D space .

22 . The method according to claim 14 , wherein the expandable distal-end assembly is one of a basket assembly and a balloon assembly .