Patent Description:
Various techniques for measuring and/or estimating contact force between a medical device and tissue and relative positions thereof are known in the art.

For example, <CIT> describes a system that includes an expandable distal-end assembly, a proximal position sensor, a distal position sensor, and a processor. The expandable distal-end assembly is coupled to a distal end of a shaft for insertion into a cavity of an organ of a patient. The proximal and distal position sensors are located at a proximal end and a distal end of the distal-end assembly, respectively. The processor is configured to estimate a position and a longitudinal direction of the proximal sensor, and a position of the distal sensor, all in a coordinate system used by the processor. The processor is further configured to project the estimated position of the distal sensor on an axis defined by the estimated longitudinal direction, and calculate an elongation of the distal-end assembly by calculating a distance between the estimated position of the proximal sensor and the projected position of the distal sensor.

<CIT> describes systems, devices and methods that integrate stretchable or flexible circuitry, including arrays of active devices for enhanced sensing, diagnostic, and therapeutic capabilities. The invention enables conformal sensing contact with tissues of interest, such as the inner wall of a lumen, the brain, or the surface of the heart. Such direct, conformal contact increases accuracy of measurement and delivery of therapy. Further, the invention enables the incorporation of both sensing and therapeutic devices on the same substrate allowing for faster treatment of diseased tissue and fewer devices to perform the same procedure. Other catheter systems are described in <CIT>, <CIT> and <CIT>.

An embodiment of the present invention that is described herein provides a system including a catheter and a processor. The catheter includes an expandable distal-end assembly (EDEA) having: (i) a transmitter, which is coupled to the EDEA and is configured to transmit a first signal, and (ii) one or more receivers, which are coupled to an elastic component of the EDEA, and are configured to produce one or more respective second signals in response to receiving the first signal. The processor is configured to estimate, based on the one or more respective second signals, a force applied to the elastic component.

In some embodiments, the EDEA includes a basket, the elastic component includes one or more splines of the basket, the force includes a contact force applied between the EDEA and tissue of an organ, and in response to applying the contact force, at least one of the splines is configured to deform for conforming with a shape of the tissue. In other embodiments, the transmitter is coupled to a rigid component of the EDEA. In yet other embodiments, the rigid component includes an irrigation apparatus or a shaft of the catheter.

In an embodiment, the processor is configured to: (i) hold a calibration dataset for quantifying a relation between at least one of the respective second signals and a level of deformation of at least one of the splines, and (ii) estimate the contact force based on at least one of the respective second signals and the calibration set. In another embodiment, the processor is configured to produce the calibration set before insertion of the EDEA into the organ, and to estimate the contact force when the EDEA is placed in contact with the tissue. In yet another embodiment, when the EDEA is in an expanded position, the one or more respective second signals include: (i) a first given signal received from a given receiver of the one or more receivers without applying the contact force, and (ii) a second given signal received from the given receiver when the contact force is applied, and the processor is configured to estimate the contact force based on the first and second given signals.

In some embodiments, the EDEA includes a balloon, and the elastic component includes a member of the balloon. In other embodiments, the force includes a contact force applied between the member and tissue of an organ, and in response to applying the contact force, the member is configured to deform for conforming with a shape of the tissue, and the processor is configured to: (i) hold a calibration dataset for quantifying a relation between at least one of the respective second signals and a level of deformation of at least a section of the member, and (ii) estimate the contact force based on at least one of the respective second signals and the calibration set.

There is additionally provided in the disclosure a method which is not part of the claimed invention, the method including inserting into an organ of a patient a catheter including an expandable distal-end assembly (EDEA) having: (i) a transmitter, which is coupled to the EDEA for transmitting a first signal, and (ii) one or more receivers, which are coupled to an elastic component of the EDEA for producing one or more respective second signals in response to receiving the first signal. The first signal is applied to the transmitter and the one or more respective second signals are received. Based on the one or more respective second signals, a force applied to the elastic component is estimated.

There is further provided, in accordance with an embodiment of the present invention, a method for producing a catheter, the method includes coupling, to an expandable distal-end assembly (EDEA) of a catheter, a transmitter for transmitting a first signal. One or more receivers for producing one or more respective second signals in response to receiving the first signal, are coupled to an elastic component of the EDEA. At least the one or more receivers are electrically coupled to a processor for receiving the one or more respective second signals and for estimating, based on the one or more respective second signals, a force applied to the elastic component.

In some embodiments, the EDEA includes a basket, the elastic component includes one or more splines of the basket, the force includes a contact force applied between the EDEA and tissue of an organ, and in response to applying the contact force, at least one of the splines is configured to deform for conforming with a shape of the tissue. In other embodiments, the transmitter is coupled to a rigid component of the EDEA, and the rigid component includes a shaft or an irrigation apparatus of the catheter. In yet other embodiments, coupling the one or more receivers includes coupling a given receiver to a given spline of the basket.

In an embodiment, the EDEA includes a balloon, and the elastic component includes a member of the balloon. In another embodiment, the force includes a contact force applied between the member and tissue of an organ, in response to applying the contact force, the member is configured to deform for conforming with a shape of the tissue.

Some medical procedures, such as radiofrequency (RF) ablation of tissue in a patient heart, require controlled contact force between ablation electrodes of an ablation catheter inserted into a patient heart and the heart tissue intended to be ablated by applying RF signals to the ablation electrodes. The ablation electrodes may be coupled to flexible splines of a basket-shaped expandable distal-end assembly. During the ablation procedure the distal-end assembly is inserted into the heart and expanded to an expanded position for exposing the ablation electrodes to the tissue. Some of the splines are placed in contact with the tissue and are deformed in order to conform with the tissue and for placing the electrodes in contact with the tissue intended to be ablated. The controlled contact force between the respective splines and the tissue is important for properly ablating the tissue and for producing, in the tissue in question, a lesion having specified properties.

In principle, it is possible to couple to the distal-end assembly, a device for measuring the contact force. For example, the device may include one or more piezoelectric crystals that output voltage in response to sensing contact force applied to the splines. However, the piezoelectric crystals may increase the complexity of the catheter and may provide insufficient accuracy of the measured or estimated contact force, inter alia, due to the flexibility of the splines.

Embodiments of the present invention that are described hereinbelow provide improved techniques for estimating the contact force applied, during an ablation procedure, between tissue in question (e.g., of a patient heart) and an expandable distal-end assembly (EDEA) of a catheter. Note that the improved techniques rely on quantifying and using the elastic properties of a flexible component of the distal-end assembly.

In some embodiments, a system for performing RF ablation to tissue in question comprises a catheter and a processor. The catheter comprises an EDEA having a transmitter and one or more receivers, typically implemented in electrical coils. The transmitter is coupled to a rigid component of the EDEA, e.g., a shaft or an irrigation apparatus of the catheter. The one or more receivers are coupled to respective elastic component(s) of the EDEA. For example, (i) in an EDEA comprising a basket, one or more receiver(s) may be coupled to each spline of the basket, and (ii) in an EDEA comprising a balloon, the one or more receivers may be disposed and fitted at several positions on the outer surface of the balloon.

In some embodiments, the one or more receivers are electrically connected to the processor and the transmitter is electrically connected to the processor or to a pulse generator controlled by the processor. In some embodiments, the electrical connection may be carried out using (i) electrical wires or traces running between the proximal and distal ends of the catheter, e.g., between the EDEA and an operating console of the system that comprises the processor, or (ii) wirelessly, using wireless devices coupled to the proximal and distal ends of the catheter.

In some embodiments, the processor is configured to apply to the transmitter a transmission signal, referred to herein as a first signal, and at least one of the receivers is configured to produce a receiving signal, referred to herein as a second signal, in response to receiving the first signal.

In some embodiments, during the ablation procedure, a physician inserts the EDEA into the patient heart, expands the EDEA to an expanded position, places the EDEA in contact with the tissue and applies contact force to the elastic component (e.g., splines) for performing the ablation. The processor is configured to estimate, based on the second signal received from the receiver, the contact force applied to the respective one or more splines. Note that the intensity of the first signal sensed by the receiver is proportional to the distance between the transmitter and the respective receiver. In some embodiments, in response to the contact force applied by the physician, a given spline of the splines deforms, and the deformation is sensed by the altered intensity of the first signal sensed by the respective receiver.

In some embodiments, the processor is configured to hold a calibration dataset (e.g., a calibration table) for quantifying the relation between the one or more second signals and the level of deformation of the one or more respective splines. The calibration process may be carried out as part of the manufacturing process of the EDEA, or before inserting the catheter into the patient heart.

In other embodiments, after expanding the EDEA and before placing the EDEA in contact with the heart tissue, the physician may control the processor to: (i) apply the first signal using the transmitter, and (ii) receive the one or more second signal(s) for obtaining a reference before applying the contact force to the splines. In such embodiments, after placing the EDEA in contact with the tissue and applying the contact force to the splines, the processor is configured to reapply the first signal and to receive an additional second signal. The processor is configured to estimate the contact force applied to the respective splines using the received second signals before and after applying the contact force to the splines.

The disclosed techniques improve the quality of RF ablation procedures by improving the accuracy and reducing the complexity of sensing contact force applied between ablation electrodes and tissue intended to be ablated during the RF ablation procedure. The disclosed techniques are also applicable, mutatis mutandis, to any other medical procedure that requires accurate sensing of contact force between a medical device pressed against tissue.

<FIG> is a schematic, pictorial illustration of a catheter-based position-tracking and ablation system <NUM>, in accordance with an embodiment of the present invention. In some embodiments, system <NUM> comprises a catheter <NUM>, in the present example an expandable cardiac catheter, and a control console <NUM>. In the embodiment described herein, catheter <NUM> may be used for any suitable therapeutic and/or diagnostic purposes, such as ablation of tissue in a heart <NUM> and for mapping cardiac arrhythmias by sensing intra-cardiac electrical signals.

In some embodiments, console <NUM> comprises a processor <NUM>, typically a general-purpose computer, with suitable front end and interface circuits for receiving signals from catheter <NUM> and for controlling other components of system <NUM> described herein. Processor <NUM> may be programmed in software to carry out the functions that are used by the system, and is configured to store data for the software in a memory <NUM>. The software may be downloaded to console <NUM> in electronic form, over a network, for example, or it may be provided on non-transitory tangible media, such as optical, magnetic or electronic memory media. Alternatively, some or all of the functions of processor <NUM> may be carried out using an application-specific integrated circuit (ASIC) or any suitable type of programmable digital hardware components.

Reference is now made to an inset <NUM>. In some embodiments, catheter <NUM> comprises an expandable distal-end assembly <NUM> having multiple splines (shown in detail in <FIG> below), and a shaft <NUM> for inserting distal-end assembly <NUM> to a target location for ablating tissue in heart <NUM>. During an ablation procedure, physician <NUM> inserts catheter <NUM> through the vasculature system of a patient <NUM> lying on a table <NUM>. Physician <NUM> moves distal-end assembly <NUM> to the target location in heart <NUM> using a manipulator <NUM> near a proximal end of catheter <NUM>, which is connected to interface circuitry of processor <NUM>.

In some embodiments, catheter <NUM> comprises a position sensor <NUM> of a position tracking system, which is coupled to the distal end of catheter <NUM>, e.g., in close proximity to distal-end assembly <NUM>. In the present example, position sensor <NUM> comprises a magnetic position sensor, but in other embodiments, any other suitable type of position sensor (e.g., other than magnetic-based) may be used.

Reference is now made back to the general view of <FIG>. In some embodiments, during the navigation of distal-end assembly <NUM> in heart <NUM>, processor <NUM> receives signals from magnetic position sensor <NUM> in response to magnetic fields from external field generators <NUM>, for example, for the purpose of measuring the position of distal-end assembly <NUM> in heart <NUM>. In some embodiments, console <NUM> comprises a driver circuit <NUM>, configured to drive magnetic field generators <NUM>. Magnetic field generators <NUM> are placed at known positions external to patient <NUM>, e.g., below table <NUM>.

In some embodiments, processor <NUM> is configured to display, e.g., on a display <NUM> of console <NUM>, the tracked position of distal-end assembly <NUM> overlaid on an image <NUM> of heart <NUM>.

The method of position sensing using external magnetic fields is implemented in various medical applications, for example, in the CARTO™ system, produced by Biosense Webster Inc. (Irvine, Calif. ) and is described in detail in <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and<CIT>, in <CIT>, and in <CIT>, <CIT> and <CIT>.

This particular configuration of system <NUM> is shown by way of example, in order to illustrate certain problems that are addressed by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such a system. Embodiments of the present invention, however, are by no means limited to this specific sort of example system, and the principles described herein may similarly be applied to other sorts of medical systems and procedures.

<FIG> is a schematic, pictorial illustration of distal-end assembly <NUM> in an expanded position, in accordance with an embodiment of the present invention.

In some embodiments, distal-end assembly <NUM> comprises multiple splines <NUM> of a basket-shaped assembly. Each spline <NUM> comprises a flexible arm <NUM> made from a suitable elastic substance, such as but not limited to a flexible printed circuit board (PCB), or a suitable biocompatible and flexible metal alloy (e.g., nickel-titanium based, such as nitinol) that may be partially coated with one or more electrically insulating layer(s) to prevent electrical shorts between splines <NUM>.

In some embodiments, one or more ablation electrodes <NUM> are coupled to each spline <NUM> and are configured to apply ablation pulse (s) to tissue of heart <NUM>. The ablation pulse(s) are intended to kill cells of the tissue in question and to produce, instead of the tissue, a lesion that prevents or reduces the propagation of electrophysiological (EP) waves through the ablated tissue.

In some embodiments, distal-end assembly <NUM> comprises a transmitter <NUM> and one or more receivers <NUM>. Transmitter <NUM> is coupled to a rigid component of distal-end assembly <NUM>, in the present example, transmitter <NUM> is coupled to an irrigation apparatus, also referred to herein as an irrigator <NUM>, which is configured to apply irrigation fluid when applying the ablation signals to tissue of heart <NUM>, or at any other suitable time interval of the ablation procedure. In other embodiments, transmitter <NUM> may be coupled to any other suitable rigid component of distal-end assembly <NUM>, such as shaft <NUM>. In the context of the present disclosure and in the claims, the term "rigid" refers to a component of catheter <NUM> that moves together with the catheter and whose location is not affected by any force, such as contact force, applied to distal-end assembly <NUM>, as will be described in detail below. In other words, transmitter <NUM> has the same angular velocity and the same angular acceleration of the distal end of shaft <NUM>.

In some embodiments, one or more receivers <NUM> are coupled to respective elastic components of distal-end assembly <NUM>. In the present example, distal-end assembly <NUM> comprises a basket having multiple splines <NUM>, and one receiver <NUM> is coupled to each spline <NUM> of the basket. In alternative embodiments, distal-end assembly <NUM> may comprise a balloon (not shown) having a flexible member, or any other suitable type of expandable distal-end assembly. In case of a balloon, receivers <NUM> may be disposed at several positions on the outer surface of the balloon. Note that in the example of <FIG>, only three receivers <NUM> are shown, but a receiver <NUM> is coupled to each spline <NUM> even though some of receivers <NUM> are hidden by the isometric perspective of distal-end assembly <NUM>, and therefore, are not shown in the example configuration of <FIG>.

In some embodiments, transmitter <NUM> and receivers <NUM> may be implemented using electrical coils that are coupled to irrigator <NUM> and splines <NUM>, respectively. The coils of transmitter <NUM> and receivers <NUM> are electrically connected to console <NUM>, and more particularly, to processor <NUM> using any suitable connection techniques described in detail below.

In some embodiments, receivers <NUM> are electrically connected (e.g., via traces of the aforementioned flexible PCB, and via catheter <NUM>) to processor <NUM>. Moreover, transmitter <NUM> is electrically connected to processor <NUM> (e.g., via wires running between (i) the distal end of shaft <NUM> or irrigator <NUM>, and (ii) the proximal end of catheter <NUM>). Additionally, or alternatively, transmitter <NUM> may be electrically connected to a pulse generator (not shown) controlled by processor <NUM> and configured to apply one or more pulses using transmitter <NUM> as will be described below.

In other embodiments, the electrical connection between (i) transmitter <NUM> and/or receivers <NUM> and (ii) processor <NUM>, may be carried out using wireless devices (not shown) coupled to the proximal and distal ends of catheter <NUM>.

In some embodiments, processor <NUM> is configured to control transmitter <NUM> to apply a transmission signal, also referred to herein as a first signal. In response to receiving the first signal, at least one of and typically all receivers <NUM>, are configured to produce a receiving signal, also referred to herein as a second signal.

In some embodiments, the second signal produced by a given receiver <NUM> is indicative of the distance between transmitter <NUM> and given receiver <NUM>, as will be described below.

In some embodiments, during the ablation procedure, physician <NUM> inserts distal-end assembly <NUM> into a cavity of heart <NUM>. Subsequently, physician <NUM> expands distal-end assembly <NUM> to an expanded position (as shown in the example of <FIG>), places distal-end assembly <NUM> in contact with the tissue intended to be ablated, and applies contact force to splines <NUM> (or any elastic component of another sort of expandable distal-end assembly) for performing the ablation of the tissue in heart <NUM>.

In some embodiments, processor <NUM> is configured to receive the second signals from receivers <NUM> and to estimate, based on the second signals, the contact force applied to the respective one or more splines <NUM>. Note that the intensity of the first signal sensed by a given receiver <NUM> is indicative of (e.g., proportional to) the distance between transmitter <NUM> and given receiver <NUM>, the smaller the distance the larger the intensity of the first signal sensed by given receiver <NUM>. In the present example, the sensitivity of the estimated change in distance between transmitter <NUM> and given receiver <NUM> is about <NUM>, whereas when applying the contact force to distal-end assembly <NUM> the change in distance between transmitter <NUM> and given receiver <NUM> is typically larger than about <NUM>.

In the context of the present disclosure and in the claims, the terms "about" or "approximately" for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein.

In some embodiments, in response to the contact force applied to distal-end assembly <NUM> by physician <NUM>, arm <NUM> of a given spline <NUM> having given receiver <NUM> coupled thereto is deformed, and the deformation is sensed by the altered intensity of the first signal sensed by the given receiver <NUM>.

In some embodiments, processor <NUM> is configured to hold a calibration dataset (e.g., a calibration table) for quantifying the relation between the one or more second signals and the level of deformation of the one or more respective splines <NUM>. The calibration process may be carried out as part of the manufacturing process of distal-end assembly <NUM>, or at any other time interval before inserting distal-end assembly <NUM> into heart <NUM> of patient <NUM>.

In some embodiments, processor <NUM> is configured to translate the change in distance between transmitter <NUM> and given receiver <NUM> to the contact force applied to the spline having the given receiver coupled thereto (e.g., using the calibration dataset. As described above, the sensitivity of estimating the change in distance is higher than the typical deformation of the spline. Therefore, processor <NUM> is configured to estimate the contact force applied to the spline with a typical sensitivity of about <NUM> grams also referred to herein as gram-force (GF), whereas a typical value of contact force applied in such procedures is between about <NUM> grams and <NUM> grams.

In other embodiments, after expanding distal-end assembly <NUM> and before placing distal-end assembly <NUM> in contact with the tissue in question of heart <NUM>, physician <NUM> may control processor <NUM> to: (i) apply the first signal using transmitter <NUM>, and (ii) receive the one or more second signal(s) from one or more respective receivers <NUM> for obtaining a reference before applying the contact force to splines <NUM>. In such embodiments, after placing distal-end assembly <NUM> in contact with the tissue intended to be ablated, and applying the contact force to splines <NUM>, processor <NUM> is configured to control transmitter <NUM> to reapply the first signal. Subsequently, processor <NUM> is configured to receive from one or more receivers <NUM>, additional second signals.

In some embodiments, processor <NUM> is configured to estimate the contact force applied to the respective splines <NUM> using the received second signals before and after applying the contact force to the respective splines <NUM>.

In some embodiments, processor <NUM> holds a threshold indicative of the minimal level of contact force, which is applicable for applying the ablation pulse(s) to the tissue in question of heart <NUM>. In some embodiments, processor <NUM> controls a RF pulse generator (not shown) of system <NUM> to apply the RF ablation signal(s) to a given ablation electrode <NUM>, only when the contact force estimated by processor <NUM> using the techniques described above, is larger than the threshold. Thus, the disclosed techniques improve the quality of RF ablation procedures by improving the accuracy of the estimated contact force applied between ablation electrodes <NUM> and the tissue of heart <NUM>, which is intended to be ablated during the RF ablation procedure described above. The disclosed techniques are also applicable, mutatis mutandis, to any other medical procedure that requires accurate and stable sensing of contact force between a medical device pressed against tissue.

The configuration of distal-end assembly <NUM> is provided in <FIG> by way of example, in order to illustrate certain problems that are addressed by embodiments of the present invention and to demonstrate the application of these embodiments in enhancing the performance of such a distal end for treating arrhythmias in patient heart. Embodiments of the present invention, however, are by no means limited to this specific sort of example distal-end assembly, and the principles described herein may similarly be applied to other sorts of catheters used in any suitable sort of medical systems and procedures that require measurement or estimation of contact force applied to any suitable type of medical device pressed against any suitable tissue of a patient.

<FIG> is a flow chart that schematically illustrates a method for estimating contact force applied between distal-end assembly <NUM> and tissue of heart <NUM>, in accordance with an embodiment of the present invention.

The method begins at a catheter insertion step <NUM>, with physician <NUM> inserting distal-end assembly <NUM> of catheter <NUM> into a cavity of heart <NUM>. In some embodiments, distal-end assembly <NUM> comprises a basket having splines <NUM> and ablation electrodes <NUM> coupled to arms <NUM> of splines <NUM>.

In some embodiments, distal-end assembly <NUM> has transmitter <NUM> coupled to a rigid component of distal-end assembly <NUM>, in the present example, irrigator <NUM> or the distal end of shaft <NUM>. Distal-end assembly <NUM> further comprises one or more receivers <NUM> coupled to at least one of and typically all splines <NUM>, which are elastic components of distal-end assembly <NUM> and are configured to deform in response to applying contact force between the tissue and the respective spline(s) <NUM>, as described in <FIG> above.

In some embodiments, transmitter <NUM> is controlled by processor <NUM> and is configured to apply a transmitted signal, also referred to herein as the first signal, as described in <FIG> above. Receivers <NUM> are configured to produce respective second signals in response to sensing/receiving the first signal applied by transmitter <NUM>, as also described in <FIG> above.

At a signal application step <NUM>, processor <NUM> controls transmitter <NUM> to apply the first signal, and, in response to applying the first signal, processor <NUM> receives one or more second signals from respective receivers <NUM>, as described in <FIG> above.

At a contact force estimation step <NUM> that concludes the method, processor <NUM> estimates the contact force applied to the respective one or more splines <NUM>, based on the one or more second signals received from the one or more respective receivers <NUM> coupled to the one or more respective splines <NUM> of distal-end assembly <NUM>.

In some embodiments, a calibration process is carried out before estimating the contact force. In the calibration process, the applied contact force and resulting deformation of splines <NUM> are quantified relative to the second signal produced by one or more receivers <NUM> coupled to one or more splines <NUM>. In other words, after the calibration, processor <NUM> is configured to receive from a given receiver <NUM> that is coupled to a given spline <NUM>, a given second signal, and based on the given second signal, processor <NUM> is configured to provide physician <NUM> with an estimated change in the contact force applied to given spline <NUM> pressed against tissue of heart <NUM>. The calibration may be carried out in the production of distal-end assembly <NUM>, or at any other suitable time interval before applying the contact force to one or more splines <NUM> of distal-end assembly <NUM>.

<FIG> is a flow chart that schematically illustrates a method for producing distal-end assembly <NUM> depicted in <FIG> above, in accordance with an embodiment of the present invention.

The method begins at a transmitter coupling step <NUM>, with coupling transmitter <NUM> to a rigid component of catheter <NUM> and/or distal-end assembly <NUM>. In the example of <FIG> above, the rigid component comprises an irrigation apparatus, referred to herein as irrigator <NUM>, or the distal end of shaft <NUM>. In other embodiments, transmitter <NUM> may be coupled to any other suitable rigid component of catheter <NUM>.

In some embodiments, transmitter <NUM> is controlled by processor <NUM> and is configured to produce a first signal, as described in <FIG> above.

At a receiver coupling step <NUM>, one or more receivers <NUM> are coupled to one or more respective elastic components (e.g., splines <NUM>) of distal-end assembly <NUM>. In some embodiments, in response to receiving or sensing the first signal applied by transmitter <NUM>, receivers <NUM> are configured to produce a second signal indicative of the distance between transmitter <NUM> and the respective receiver <NUM>.

In some embodiments, any suitable number of receivers <NUM> may be coupled along each spline <NUM>, the number of coupled receivers <NUM> may be similar among all splines <NUM> or may differ between different splines <NUM>. In one example implementation of distal-end assembly <NUM>, one receiver <NUM> may be coupled to each spline <NUM>. In another example implementation of distal-end assembly <NUM>, multiple receivers <NUM> are coupled to a first spline <NUM>, only one receiver <NUM> is coupled to a second spline <NUM>, and a third spline <NUM> may not have any receiver <NUM>.

At a connecting step <NUM> that concludes the method, transmitter <NUM> and receivers <NUM> are electrically connected to processor <NUM> for estimating, based on the first and second signals, the contact force applied to each spline <NUM> of distal-end assembly <NUM>. The electrical connectors may comprise electrical leads or wires coupled between the distal and proximal ends of catheter <NUM>, or electrical traces of the flexible PCB, or wireless devices coupled to the distal and proximal ends of catheter <NUM>, as described in <FIG> above.

In some embodiments, after the production method may comprise additional steps, such as but not limited to: (i) coupling ablation electrodes to arms <NUM> of splines <NUM>, (ii) coating one or more sections of one or more splines <NUM> using one or more electrically insulating layer(s), and (iii) coupling distal-end assembly <NUM> to catheter <NUM>, for example by coupling splines <NUM> to the distal end of shaft <NUM> or to any other suitable component of catheter <NUM>.

Claim 1:
A system (<NUM>), comprising:
a catheter (<NUM>), comprising an expandable distal-end assembly (EDEA) (<NUM>) having: (i) a transmitter (<NUM>), which is coupled to the EDEA (<NUM>) and is configured to transmit a first signal, and (ii) a plurality of receivers (<NUM>), which are coupled to an elastic component of the EDEA (<NUM>), and are configured to produce one or more respective second signals in response to receiving the first signal;
wherein one of the following conditions is satisfied:
(i) the EDEA (<NUM>) comprises a basket and one or more of the plurality of receivers (<NUM>) are coupled to each spline (<NUM>) of the basket; or
(ii) the EDEA (<NUM>) comprises a balloon and the plurality of receivers (<NUM>) are disposed at several positions on the outer surface of the balloon;
and wherein the system further comprises:
a processor (<NUM>), which is configured to: (i) hold a calibration dataset for quantifying a relation between at least one of the respective second signals and a level of deformation of at least one of the splines (<NUM>) or a member of the balloon, and (ii) estimate the contact force based on at least one of the respective second signals and the calibration set.