Patent Description:
Cardiac arrhythmias, such as atrial fibrillation, occur when regions of cardiac tissue abnormally conduct electric signals to adjacent tissue, thereby disrupting the normal cardiac cycle and causing asynchronous rhythm.

Procedures for treating arrhythmia include surgically disrupting the origin of the signals causing the arrhythmia, as well as disrupting the conducting pathway for such signals. By selectively ablating cardiac tissue by application of energy via a catheter, it is sometimes possible to block or modify the propagation of unwanted electrical signals from one portion of the heart to another. The ablation process destroys the unwanted electrical pathways by formation of non-conducting lesions.

Verification of physical electrode contact with the target tissue is important for controlling the delivery of ablation energy. Attempts in the art to verify electrode contact with the tissue have been extensive, and various techniques have been suggested. For example, <CIT> describes apparatus for treating a selected patient tissue or organ region. A probe has a contact surface that may be urged against the region, thereby creating contact pressure. A pressure transducer measures the contact pressure. This arrangement is said to meet the needs of procedures in which a medical instrument must be placed in firm but not excessive contact with an anatomical surface, by providing information to the user of the instrument that is indicative of the existence and magnitude of the contact force.

As another example, U. <CIT> describes methods for creating lesions in body tissue using segmented electrode assemblies. In one embodiment, an electrode assembly on a catheter carries pressure transducers, which sense contact with tissue and convey signals to a pressure contact module. The module identifies the electrode elements that are associated with the pressure transducer signals and directs an energy generator to convey RF energy to these elements, and not to other elements that are in contact only with blood.

A further example is presented in <CIT>. This patent describes a method for mapping a heart using a catheter having a tip electrode for measuring local electrical activity. In order to avoid artifacts that may arise from poor tip contact with the tissue, the contact pressure between the tip and the tissue is measured using a pressure sensor to ensure stable contact.

<CIT> describes systems and methods for assessing electrode-tissue contact for tissue ablation. An electromechanical sensor within the catheter shaft generates electrical signals corresponding to the amount of movement of the electrode within a distal portion of the catheter shaft. An output device receives the electrical signals for assessing a level of contact between the electrode and a tissue.

<CIT>et al. , describes another application of contact pressure measurement, in which deformation in response to pressure on a resilient member located at the distal end of a catheter is measured using a sensor.

A number of references have reported methods to determine electrode-tissue contact, including <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; <CIT>; and <CIT>. A number of these references, e.g., <CIT>, <CIT>, and <CIT> determine electrode-tissue contact by measuring the impedance between the tip electrode and a return electrode. As disclosed in the '<NUM> patent, it is generally known than impedance through blood is generally lower that impedance through tissue. Accordingly, tissue contact has been detected by comparing the impedance values across a set of electrodes to premeasured impedance values when an electrode is known to be in contact with tissue and when it is known to be in contact only with blood.

<CIT>, at al. , describes using machine learning to determine catheter electrode contact. The '<NUM> Patent describes cardiac catheterization being carried out by memorizing a designation of a contact state between an electrode of the probe and the heart wall as an in-contact state or an out-of-contact state, and making a series of determinations of an impedance phase angle of an electrical current passing through the electrode and another electrode, identifying maximum and minimum phase angles in the series, and defining a binary classifier adaptively as midway between the extremes. A test value is compared to the classifier as adjusted by a hysteresis factor, and a change in the contact state is reported when the test value exceeds or falls below the adjusted classifier.

<CIT>, describes a device for ablating target tissue of a patient with electrical energy is provided. An elongate shaft includes a proximal portion and a distal portion, and a radially expandable element is attached to the distal portion. An ablation element for delivering electrical energy to target tissue is mounted to the radially expandable element. The device can be constructed and arranged to ablate the duodenal mucosa of a patient while avoiding damage to the duodenal adventitial tissue. Systems and methods of treating target tissue are also provided.

<CIT> describes catheter apparatuses, systems, and methods for achieving renal neuromodulation by intravascular access are disclosed herein. One aspect is directed to apparatuses, systems, and methods that incorporate a catheter treatment device comprising an elongated shaft. The elongated shaft is sized and configured to deliver an energy delivery element to a renal artery via an intravascular path. Thermal or electrical renal neuromodulation may be achieved via direct and/or via indirect application of thermal and/or electrical energy to heat or cool, or otherwise electrically modulate, neural fibers that contribute to renal function, or of vascular structures that feed or perfuse the neural fibers.

<CIT>, describes a catheter for treating arrhythmia comprises a catheter shaft of a double-cylinder structure where an inner shaft is slidably inserted in an outer shaft, a balloon installed so as to straddle between the tip portion of the inner shaft and the tip portion of the outer shaft, a pair of high frequency current-carrying electrodes of which at least one electrode is provided inside the balloon, and a temperature sensor for monitoring the temperature in the balloon. The front edge portion of the balloon at least in a deflated state protrude from the tip portion of the inner shaft. Alternatively, a tube that is more flexible than the inner shaft is provided on the tip portion of the inner shaft.

<CIT>describes a catheter for performing balloon angioplasty comprising concentric, independently inflatable/deflatable balloons, each balloon having a different diameter.

<CIT>, describes a medical apparatus, including a probe having a distal end configured for insertion into a body cavity and containing a lumen that opens through the distal end, and an inflatable balloon deployable through the lumen into the body cavity such that when the balloon is deployed through the lumen and inflated, a distal pole on a distal side of the balloon is located opposite the lumen. The medical apparatus also includes an electrode attached to the distal side of the inflatable balloon and extending over at least <NUM>% of an area of the distal side of the balloon that is within <NUM>° of arc from the distal pole.

The invention is defined in appended independent claim <NUM>. Further embodiments are defined in appended dependent claims.

There is provided in accordance with an embodiment of the present disclosure, a system including a balloon catheter configured to be inserted into a body-part of a living subject, the balloon catheter including an insertion tube having a distal tip, a force sensor connected to the distal tip, and an inflatable balloon including a proximal portion connected to the force sensor so that the force sensor is disposed between the distal tip of the insertion tube and the inflatable balloon, and multiple electrodes disposed around an outer surface of the balloon, and configured, when the balloon is inflated, to contact tissue at respective locations in the body-part, wherein the force sensor is configured to output at least one force signal indicative of a magnitude and a direction of a force applied by the balloon on the tissue when the balloon is inflated.

Further in accordance with an embodiment of the present disclosure, the system includes a display, and processing circuitry configured to compute the magnitude and direction of the force responsively to the at least one force signal, and render to the display a representation of a force vector and a representation of the inflatable balloon, responsively to the at least one force signal.

Still further in accordance with an embodiment of the present disclosure the balloon catheter further includes at least one position sensor configured to output at least one position signal indicative of a position of the distal tip, the processing circuitry is configured to compute the position of the distal tip responsively to the at least one position signal, and render to the display the representation of the force vector responsively to the computed magnitude and direction, and the representation of the inflatable balloon responsively to the computed position and the at least one force signal.

Additionally in accordance with an embodiment of the present disclosure the processing circuitry is configured to receive contact signals from the electrodes, in response to the contact signals, assess a respective quality of contact of each of the electrodes with the tissue, and render to the display the representation of the inflatable balloon, while modifying a visual feature of ones of the electrodes responsively to the respective quality of contact of the electrodes with the tissue at the respective locations.

Moreover, in accordance with an embodiment of the present disclosure each of the electrodes is a flexible electrode formed from a polyamide substrate with a gold covering thereon.

There is provided in accordance with another embodiment of the present disclosure, a electrophysiology catheter device, including a tubular member extending along a longitudinal axis from a proximal portion to a distal portion, a first coupler member connected to the distal portion of the tubular member, a beam coupling member coupled to the first coupler member with at least one first protrusion on one of the beam coupling member and first coupler member with the one first protrusion mated to at least one first notch on one of the other of the beam coupling member and first coupler member, and a second coupler member coupled to the beam coupling member with at least one second protrusion on one of the beam coupling member and second coupler member with the at least one second protrusion mated to at least one second notch on one of the other of the beam coupling member and second coupler member.

Further in accordance with an embodiment of the present disclosure, the device includes a balloon connected to the second coupler member.

Still further in accordance with an embodiment of the present disclosure the beam coupling member defines a generally cylindrical surface that extends from a first end to a second end, each of the first and second ends having at least one arm extending along the longitudinal axis, the at least one arm defining a protrusion that extends along a circumferential direction about the longitudinal axis.

Additionally, in accordance with an embodiment of the present disclosure the at least one arm at the first end includes three arms that extend towards the first coupler member and the at least one arm at the second end includes three arms that extend toward the second coupler member, each arm having a protrusion that extends along a circumferential direction about the longitudinal axis.

Moreover, in accordance with an embodiment of the present disclosure a protrusion proximate the first end is configured to be divided into two ramps that extend in a spiral direction along the longitudinal axis towards another protrusion proximate the second end.

Further in accordance with an embodiment of the present disclosure the first coupler includes a notch configured to mate to the protrusion of the at least one arm at the first end and the second coupler member includes a notch configured to mate to the protrusion of the at least one arm at the second end.

Still further in accordance with an embodiment of the present disclosure, the device includes a flex circuit having at least one location sensing coil mounted to one of the first and second coupler members.

Additionally, in accordance with an embodiment of the present disclosure the at least one location sensing coil includes two location sensing coils.

Moreover, in accordance with an embodiment of the present disclosure, the device includes at least one ablation electrode coupled to the second coupler member and at least one temperature sensor coupled to the second coupler member.

Further in accordance with an embodiment of the present disclosure, the device includes at least one ablation electrode mounted on the balloon and at least one temperature sensor mounted to the balloon.

Still further in accordance with an embodiment of the present disclosure the at least one ablation electrode includes eight ablation electrodes and the at least one temperature sensor includes eight temperature sensors.

Balloon catheters may inflate to diameters that are approximately <NUM> or more and are generally used to simultaneously perform ablations over a relatively large area, such as a pulmonary vein ostium. Focal catheters, on the other hand, generally having a diameter of around <NUM>, are more suited to performing relatively "pin-point" ablations in the heart chamber. To enlarge the ablation region, the focal catheter may be used for multiple consecutive ablations. Performing point-by-point ablation using a focal catheter is time consuming, which may be a critical factor when performing heart procedures.

Embodiments of the present invention overcome the above problems by providing a system including a balloon catheter having a diameter of around <NUM>, or less, when fully inflated. Due to the small size of the balloon, after deflation, the balloon shrinks to a diameter of around <NUM> without the need for a central extension tube, used in many balloon structures, to straighten out the deflated balloon for reinsertion into a sheath.

The inflatable balloon may be maneuvered easily around the chambers of the heart, allowing ablation of large regions of heart tissue to be performed quickly, thus shortening the ablation time compared to a focal catheter.

The inflatable balloon includes flexible electrodes disposed thereon for sensing electrical signals and/or applying radio frequency energy to perform ablation. Wires extending from the rear of the electrodes may also function as temperature sensors for use in sensing the temperature of the electrodes and/or tissue during ablation.

The maneuverability of the inflated balloon within the chambers of the heart highlights a new problem: A large balloon, which performs ablation in a pulmonary vein, occludes the vein due to its large size, and all the electrodes around the surface of the balloon contact the vein tissue sufficiently to provide a good lesion. With a small balloon, however, sufficient electrode contact with the tissue is not guaranteed.

Embodiments of the present invention overcome the above problem by providing the balloon catheter with a force sensor, which is disposed between the distal tip of the deflectable segment of the catheter and the proximal end of the inflatable balloon. The force sensor senses the magnitude and direction of the force applied by the inflatable balloon. In some embodiments, a force vector representing the magnitude and direction of the force may be rendered to a display with a representation of the balloon catheter. The force vector may be used by an operator of the system to estimate the magnitude and direction of the force applied on the heart tissue by the balloon and thereby to configure which electrodes should be used to perform an ablation, with which power, and for which duration. In some embodiments, the force vector may be indicative of the force applied on the balloon by the heart tissue.

In some embodiments of the present invention, sufficiency of tissue contact between individual electrodes and tissue is used to decide whether or not to highlight the electrodes on the representation of the inflatable balloon rendered to the display. The quality of contact may be assessed based on different methods including using impedance values and/or change of phase of impedances, or based on amplitudes of intracardiac electrogram (IEGM) signals, for example only, as will be described below in more detail. Although the quality of contact based on impedance or other electrical methods may provide an indication of whether the electrode is in contact with (or at least close to) the tissue, the impedance does not generally provide an accurate picture as to the extent of the contact. Using the quality of contact in combination with the force vector provides the operator of the system with a more accurate picture of the extent of the contact. The operator of the system may then consider both the force vector and the highlighted electrodes to configure which electrodes should be used to perform an ablation, with which power, and for which duration. For example, the highlighted electrodes may be confirmed by an operator as being in sufficient contact with tissue based on the direction of the force vector. By way of another example, if the force vector indicates that the applied force is low, and the direction of the force is consistent with the highlighted electrodes, and the highlighted electrodes indicate that many of the electrodes are in contact with tissue, the operator may assume that the catheter is in a region of soft tissue as the catheter has likely sunk into the tissue and is partially, or fully, surrounded by the tissue. The operator may then use this information to set the power and duration of ablation according to the assumption that the tissue is soft tissue, by using a lower power for less time. By way of yet another example, if the force vector indicates that the applied force is high, and the direction of the force is consistent with the highlighted electrode(s), and the highlighted electrode(s) indicate that one or two electrodes are in contact with the tissue, the operator may assume that the catheter is in a region of hard tissue (e.g., scarred tissue). The operator may then use this information to set the power and duration of ablation according to the assumption that the tissue is hard tissue, by using a higher power for more time.

In response to signals provided by the catheter electrodes (and optionally body surface electrodes), processing circuitry may assess the respective quality of contact of each of the catheter electrodes with the tissue in the heart. Any one of the catheter electrodes may be in full or partial contact with the tissue of the heart. In some cases, any one of the catheter electrodes may be in contact with the tissue via another fluid such as blood of various thicknesses. The quality of contact (full or partial contact, or contact via another liquid) of any one of the catheter electrodes with the tissue may be assessed based on the signals provided by the catheter.

The term "quality of contact" as used in the specification and claims is defined herein as a quantitative indicator of the degree of electrical contact between one of the catheter electrodes and the tissue. The "quality of contact" may be expressed directly, for example in terms a measured electrical impedance, or indirectly, for example in terms of IEGM amplitude.

In some embodiments, the catheter may provide signals which provide an indication of impedance between the catheter electrodes and body surface electrodes. The indication of the impedance provides an indication of a quality of contact. Since myocardium has a lower conductivity than blood, a higher value of impedance between one catheter electrode and the body surface electrodes indicates a higher quality of contact between that catheter electrode and the tissue. A value of impedance may be selected to define a minimum quality of contact considered to represent sufficient contact between any one of the catheter electrodes and the tissue.

In some embodiments, the impedance between one of the catheter electrodes and another one of the electrodes on the catheter may be used as a measure of quality of contact. As disclosed in the '<NUM> patent mentioned in the background section above, impedance through blood is generally lower than impedance through tissue. Accordingly, tissue contact may be assessed by comparing impedance values across a set of electrodes to premeasured impedance values when an electrode is known to be in sufficient contact with tissue and when it is known to be in contact only with blood.

Reference is now made to <FIG>, which is a pictorial illustration of a system <NUM> for evaluating electrical activity in a heart <NUM> of a living subject and providing treatment thereto using a catheter <NUM> constructed and operative in accordance with an embodiment of the present invention. The catheter <NUM> is percutaneously inserted by an operator <NUM> through the patient's vascular system into a chamber or vascular structure of the heart <NUM>. The operator <NUM>, who is typically a physician, brings the catheter's distal tip <NUM> into contact with the heart wall, for example, at an ablation target site. Electrical activation maps may be prepared, according to the methods disclosed in <CIT>, and <CIT>, and in commonly assigned <CIT>, whose disclosures are herein incorporated by reference in their entirety. One commercial product embodying elements of system <NUM> is available as the CARTO® <NUM> System, available from Biosense Webster, Inc. , <NUM> Technology Drive, Irvine, CA, <NUM>.

Areas determined to be abnormal, for example by evaluation of the electrical activation maps, can be ablated by application of thermal energy, e.g., by passage of radiofrequency electrical current through wires in the catheter to one or more electrodes at the distal tip <NUM>, which apply the radiofrequency energy to target tissue. The energy is absorbed in the tissue, heating it to a point (typically above <NUM>) at which point it permanently loses its electrical excitability. This procedure creates non-conducting lesions in the cardiac tissue, which disrupt the abnormal electrical pathway causing the arrhythmia. Such principles can be applied to different heart chambers to diagnose and treat many different types of cardiac arrhythmias.

The catheter <NUM> typically includes a handle <NUM>, having suitable controls on the handle to enable the operator <NUM> to steer, position and orient the distal end of the catheter as desired for the ablation. To aid the operator <NUM>, distal portion <NUM> of catheter <NUM>, or portions proximate thereto, contains position sensors, e.g., traces or coils (discussed below), that provide signals to a processor <NUM>, located in a console <NUM>.

Ablation energy and electrical signals can be conveyed to and from the heart <NUM> through one or more ablation electrodes <NUM> located at or near the distal tip <NUM> via cable <NUM> to the console <NUM>. Pacing signals and other control signals may be conveyed from the console <NUM> through the cable <NUM> and the electrodes <NUM> to the heart <NUM>.

Wire connections <NUM> link the console <NUM> with body surface electrodes <NUM> and other components of a positioning sub-system for measuring location and orientation coordinates of the catheter <NUM>. The processor <NUM> or another processor may be an element of the positioning subsystem. The electrodes <NUM> and the body surface electrodes <NUM> may be used to measure tissue impedance at the ablation site as taught in <CIT>et al. A temperature sensor typically a thermocouple or thermistor, may be mounted on or near each of the electrodes <NUM>. An example of the temperature sensor as used in conjunction with the ablation electrode is shown and described in <CIT>, with a copy provided in the Appendix in the priority patent application.

The console <NUM> typically contains one or more ablation power generators <NUM>. The catheter <NUM> may be adapted to conduct ablative energy to the heart using any known ablation technique, e.g., radiofrequency energy, ultrasound energy, cryogenic energy, and laser-produced light energy. Such methods are disclosed in commonly assigned <CIT><CIT>, and <CIT>.

The positioning subsystem may also include a magnetic position tracking arrangement that determines the position and orientation of the catheter <NUM> by generating magnetic fields, using magnetic field generators <NUM>, in a predefined working volume and sensing these fields at the catheter, using coils or traces disposed within the catheter, typically proximate to the tip. A positioning subsystem is described in <CIT>, and in the above-noted <CIT>.

Operator <NUM> may observe and regulate the functions of the catheter <NUM> via console <NUM>. Console <NUM> includes the processor <NUM> implementing processing circuitry including appropriate signal processing circuits. The processor <NUM> is coupled to drive a display <NUM>. The signal processing circuits typically receive, amplify, filter and digitize signals from the catheter <NUM>, including signals generated by sensors such as electrical, temperature and contact force sensors, and a plurality of location sensing coils or traces located distally in the catheter <NUM>. The digitized signals are received and used by the console <NUM> and the positioning subsystem to compute the position and orientation of the catheter <NUM>, and to analyze the electrical signals from the electrodes and the contact force sensors.

In order to generate electroanatomic maps, the processor <NUM> typically comprises an electroanatomic map generator, an image registration program, an image or data analysis program and a graphical user interface configured to present graphical information on the display <NUM>.

Typically, the system <NUM> includes other elements, which are not shown in the figures for the sake of simplicity. For example, the system <NUM> may include an electrocardiogram (ECG) monitor, coupled to receive signals from one or more body surface electrodes, in order to provide an ECG synchronization signal to the console <NUM>. The system <NUM> typically also includes a reference position sensor, either on an externally applied reference patch attached to the exterior of the subject's body, or on an internally placed catheter, which is inserted into the heart <NUM> maintained in a fixed position relative to the heart <NUM>. Conventional pumps and lines for circulating liquids through the catheter <NUM> for cooling the ablation site may be provided. The system <NUM> may receive image data from an external imaging modality, such as an MRI unit, CT, or the like and includes image processors that can be incorporated in or invoked by the processor <NUM> for generating and displaying images.

<FIG> describe force and position sensors for use in the distal tip of the catheter <NUM>. The sensors generally need to fit within the small inner diameter of the catheter (e.g., often equal to or less than about <NUM>) yet overcome various design constraints related thereto to provide feedback reliably. For example, metal coils may be used to detect location within a magnetic field. Generally, larger and thicker coils may provide better detection than smaller and thinner coils, however, due to the small space within the catheter, the coils need to be small and thin enough to fit therein. Further, when such coils are fabricated as traces on a circuit board or flexible circuit via a lithographic process, the process limits the trace pitch. Although the thickness of the traces may be increased using additional layers lithographically, this option may be expensive and the coils may be compromised insofar as the yield decreases non-linearly with the number of layers. These design challenges are compounded by inclusion of additional structures proximate to the location traces, such as force sensors to provide sub-gram force measurements and reducing cross-talk interference that may arise from packing the structures in a tight space, as well as ease of assembly and safe wiring.

Reference is now made to <FIG>, which is a schematic view of a flexible-circuit <NUM> of the catheter <NUM> of <FIG>. The flexible circuit <NUM> may be employed within a catheter, such as catheter <NUM>, to provide signals indicative of location and force to the processor <NUM> in console <NUM>. Flexible circuit <NUM> includes a substantially planar substrate <NUM> having a first portion <NUM> having a first shape (e.g., a circular or trefoiled shape as shown) formed from three segments <NUM>, <NUM>, and <NUM>. Flexible circuit <NUM> also includes a second portion <NUM> having a second shape (e.g., substantially rectangular as shown) formed from two substantially rectangular segments connected by connector segment <NUM> and optionally connector segment <NUM>. First portion <NUM> and second portion <NUM> are typically different shapes because, as will be explained below, portion <NUM> is elongated and is assembled with its long axis parallel to the longitudinal axis of the catheter <NUM>, whereas portion <NUM> is assembled transversely to the longitudinal axis of the catheter <NUM>, such that it should fit in the inner diameter of the catheter <NUM> (i.e., have a maximum width or diameter that is less than the inner diameter of the catheter <NUM>). Substrate may be formed of any suitable material that is non-conductive and is capable of resisting high temperatures, for example, but not limited to, polyimide, polyamide, or liquid crystal polymer (LCP).

Substrate <NUM> may also include additional portions, such as third portion <NUM> and fourth portion <NUM>. Each of these portions may further include various segments. Third portion <NUM> may have a similar structure to second portion <NUM>, and may include substantially rectangular segments <NUM>, <NUM>, which are connected via at least one connector segment, such as <NUM> and/or <NUM>. Fourth portion <NUM> may include at least three connector segments <NUM>, <NUM> and <NUM>, which connect fourth portion <NUM> to first, second, and third portions <NUM>, <NUM>, and <NUM>, respectively.

Electrical components may be incorporated into substrate <NUM> and its various portions and segments. For example, substantially planar coils or traces used to measure signals relating to force (i.e., force-sensing coils or traces) may be disposed on first portion <NUM>. Specifically, a coil <NUM> may be disposed on segment <NUM>, a coil <NUM> may be disposed on segment <NUM>, and a coil <NUM> may be disposed on segment <NUM>. Coils <NUM>, <NUM>, and <NUM> may be discrete from each other, as shown, or they may each be connected to one or both of the others. Portions of each coil, or extensions thereof, may extend from the coil to solder joints <NUM> (only some labeled for the sake of simplicity) located on fourth portion <NUM> and be soldered thereto. Where the three coils are discrete from each other, each should include at least one respective line (e.g., <NUM>, <NUM>, and <NUM>) connecting to the solder joints <NUM>. Where the coils are discrete from each other, the signals generated in each of the coils may be used to provide additional details of force, such as an indication of an off-center force or an off-axis direction of the force. As shown, each coil on first portion <NUM> includes approximately five turns. However, because signal strength is a function of the number of turns, the number of turns may be maximized based on the size of each segment and the pitch that the lithographic process can accomplish.

Planar coils or traces used to measure signals relating to location (i.e., location coils or traces) may also be incorporated into second portion <NUM> and third portion <NUM>. Coil <NUM> may be disposed on segment <NUM>, coil <NUM> may be disposed on segment <NUM>, coil <NUM> may be disposed on segment <NUM>, and coil <NUM> may be disposed on segment <NUM>. Each of the coils <NUM>, <NUM>, <NUM>, <NUM> may extend to solder joints <NUM> on fourth portion <NUM>. For example, coil <NUM> may include an extension <NUM> that connects to a solder joint <NUM> via connector segment <NUM> and coil <NUM> may include an extension <NUM> that connects to a solder joint <NUM> via connector segment <NUM>, segment <NUM> and connector segment <NUM>. As shown, each coil on portions <NUM> and <NUM> includes approximately five turns. However, because signal strength is a function of the number of turns, the number of turns may be maximized based on the size of segments <NUM>, <NUM>, <NUM>, and <NUM>, and the pitch that the lithographic process can accomplish.

Second portion <NUM> is laterally disposed to one side of first portion <NUM> and fourth portion <NUM>, and such that third portion <NUM> is laterally disposed to the other side of first portion <NUM> and fourth portion <NUM>. Thus, fourth portion <NUM> is disposed between first portion <NUM>, second portion <NUM> and third portion <NUM>. Further, segments <NUM> and <NUM> have traces wound in opposite orientations.

Substrate <NUM> may be a single layer. Alternatively, it may include more layers, for example, but not limited to, between two and ten layers, such as, four layers. In this manner the coils may be thickened by adding layers. However, as described above, thickening by layers results in non-linearly decreased yield in manufacturing of the component. The flexibility of flexible circuit <NUM> provides a solution to this tradeoff, as will be described below.

Reference is now made to <FIG>, which is a schematic view of the flexible-circuit <NUM> of <FIG> in a folded configuration. By deforming or bending connector <NUM> and connector <NUM>, segment <NUM> may be folded on top of segment <NUM> so that coil <NUM> aligns with coil <NUM>. Similarly, by deforming or bending connector <NUM> and connector <NUM>, segment <NUM> may be folded on top of segment <NUM> so that coil <NUM> aligns with coil <NUM>. Although connectors <NUM> and <NUM> are optional, they may assist aligning the coils with each other by reducing relative rotation between the segments. If substrate <NUM> is formed from multiple layers, such as four layers, for example, then after segment <NUM> is folded onto segment <NUM>, coils <NUM> and <NUM> form a combined coil having more than two layers, such as eight layers. Folding different segments on to each other to yield a combined coil allows for the creation of a coil with more layers without negatively affecting manufacturing yields.

An advantage that a thinner substrate (e.g., four layers) has over a thicker substrate (e.g., eight layers) is that it is easier to deform or bend, which is helpful for assembling flexible circuit <NUM> to other catheter components and ultimately for fitting it within the inner-diameter of the catheter, as will be described.

Reference is now made to <FIG>, which is a schematic view of another flexible-circuit <NUM> of the catheter <NUM> of <FIG>. The flexible circuit <NUM> includes substrate <NUM> and coil or coils <NUM>. The structure of flexible circuit <NUM> is similar to the structure of first portion <NUM> of flexible circuit <NUM>. However, in various embodiments, the number or pitch of the coils may vary, and the various coils on the three segments may be discrete from each other or integrated with each other.

Reference is now made to <FIG>, which is a schematic view of a beam coupling member <NUM> of the catheter <NUM> of <FIG>. The helical beam coupling member <NUM> includes a top face <NUM>, a bottom face <NUM>, and various arms <NUM> that may be used to connect the beam coupling member <NUM> to other components of catheter <NUM>. Beam coupling member <NUM> has a known or predetermined spring constant providing a relationship between distance and force in accordance with Hooke's law. Together flexible circuit <NUM>, first portion <NUM> of flexible circuit <NUM>, and helical beam coupling member <NUM> form a force sensor sub-assembly that receives electrical signals from, and provides electrical signals to, console <NUM>, which may process received signals to determine forces, e.g., sub-gram forces, exerted on tip <NUM> of catheter <NUM>.

The first portion <NUM> (including coils <NUM>, <NUM>, <NUM>) of flexible circuit <NUM> is disposed on bottom face <NUM>, and coils <NUM> on flexible circuit <NUM> are disposed on the top face <NUM>. In some embodiments, the first portion <NUM> (including coils <NUM>, <NUM>, <NUM>) of flexible circuit <NUM> is disposed on top face <NUM>, and coils <NUM> on flexible circuit <NUM> are disposed on the bottom face <NUM>.

Wires (within a cable-bundle <NUM> of <FIG> and <FIG>), running between the console <NUM> and solder joints <NUM> of fourth portion <NUM> of flexible circuit <NUM>, connect the console <NUM> via coil extensions <NUM>, <NUM>, and <NUM> to coils <NUM>, <NUM>, and <NUM> on segments <NUM>, <NUM>, and <NUM> of first portion <NUM>, respectively. Wires (also within cable-bundle <NUM>) running from the console <NUM> connect with coil or coils <NUM> on flexible circuit <NUM>. Electrical signals from console <NUM>, e.g., having RF frequencies, may be used to power either the coils <NUM>, <NUM>, <NUM> on the first portion <NUM> of flexible circuit <NUM> or the coils <NUM> on flexible circuit <NUM>. Whichever set of coils receives power from console <NUM> may be considered a transmitter (i.e., one of flex circuit <NUM> or <NUM>) because it emits an electromagnetic field that varies in accordance with the frequency of the signals received from console <NUM>. The set of coils that is not powered by console <NUM> may be considered a receiver in as much as it functions like an antenna in response to the electromagnetic field from the transmitter. Thus, the receiver (i.e., the other of flex circuit <NUM> or <NUM>) generates electrical signals that may be conveyed to console <NUM> for analysis. The electrical signals generated by the receiver depend on the distance between the receiver and the transmitter, such that the electrical signals generated by the receiver may be correlated to the distance between the receiver and the transmitter, which is correlated to a compression displacement of the beam coupling member (e.g., in the order of <NUM> nanometers) and thus correlates to forces against tip <NUM> of catheter <NUM> that cause spring <NUM> to compress.

The beam coupling member <NUM> may be deflected to one side more than another. This off-center deflection is representative of a sideways component of a force being applied by the tip <NUM>. The sideways force may be detected by the different distances between the coils <NUM>, <NUM>, <NUM> and the coil(s) <NUM> which may be computed for example, from the signals provided by the coils <NUM>, <NUM>, <NUM>.

In use, console <NUM> may process these signals and use them to regulate the amount of ablation energy supplied to electrodes. For example, when the signals indicate that the beam coupling member <NUM> is in a relaxed state (i.e., no compression) this may be perceived as an indication that tip <NUM> of catheter <NUM> is not in contact with tissue, and therefore, no ablation energy should be supplied to the electrodes. Indicators of the information (e.g., in units of force, such as gram-force) may further be provided to operator <NUM> on display <NUM> so that the operator <NUM> may adjust the ablation settings manually.

Top distal face <NUM> and bottom proximal face <NUM> of beam coupling member <NUM> may be parallel to each other and oriented transversely to the longitudinal axis of the beam coupling member <NUM> (e.g., at an angle of greater than about sixty degrees and less than or equal to ninety degrees, e.g., about eighty degrees). Accordingly, in some embodiments, the receiver and the transmitter, affixed thereto, are similarly oriented. The inventors have determined that a transverse but non-perpendicular orientation of the receiver and transceiver increases the sensitivity of the receiver because the distance between the transmitter and receiver is minimized as compared to when the receiver and transceiver are disposed perpendicular to the beam coupling member <NUM>'s longitudinal axis, and the catheter's longitudinal axis.

Reference is now made to <FIG>. <FIG> is a first cutaway view of a distal portion of the catheter <NUM> of <FIG>. <FIG> is a second cutaway view of a distal portion of the catheter <NUM> of <FIG>. <FIG> is a transverse cross-sectional view taken through line A-A of <FIG> shows flexible circuit <NUM> as assembled to beam coupling member <NUM> and a coupler or coupling sleeve <NUM>. Although not seen, first portion <NUM> of flexible circuit <NUM> is adhered to proximal face <NUM> (<FIG>) of beam coupling member <NUM> and flexible circuit <NUM> is adhered to distal face <NUM> (<FIG>) of beam coupling member <NUM>. In <FIG>, tip <NUM>, which includes ablation electrode(s) <NUM>, and various irrigation apertures <NUM>, is attached to beam coupling member <NUM>. Also shown in <FIG> and <FIG> is cable bundle <NUM>. Cable bundle <NUM> includes a set of wires which, although not shown, are connected to solder joints <NUM> on fourth portion <NUM> of flexible circuit <NUM>, and thus to the various coils or traces on flexible circuit <NUM>, and to coils or traces <NUM> on flexible circuit <NUM>. As seen in <FIG> flexible circuit <NUM> is no longer planar. Rather, it has been deformed to have a shape that has a traverse cross section that is generally circular. Segment <NUM> of second portion <NUM> is the most readily visible segment of flexible circuit <NUM> in <FIG> and <FIG>. Various sides of segment <NUM>, segment <NUM>, and segment <NUM>, as well as connectors <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are also visible in these figures. As seen these connectors have been deformed into bent or curved configurations for attachment to coupler <NUM>. Specifically, segment <NUM> is adhered to a substantially planar surface <NUM> of coupler <NUM>, and segment <NUM> is adhered to a substantially planar surface <NUM> of coupler <NUM> (<FIG>). So assembled, these portions of flexible circuit <NUM> may be viewed as having a triangular cross section. Further, connector <NUM> is adhered to a circular (or arcuate) surface <NUM> of coupler <NUM> and connector <NUM> is adhered to a circular (or arcuate) surface <NUM> of coupler <NUM>. So assembled, these portions of flexible circuit <NUM> may be viewed as having a circular (or arcuate) cross section. Fourth portion <NUM> may further be adhered to substantially planar surface <NUM> of coupler <NUM>.

The diameter or width of the circular portion of the cross section of flexible circuit <NUM> as assembled to coupler <NUM> is equal or approximately equal to the diameter or maximum width of first portion <NUM>, which is also equal or approximately equal to the maximum width (or base) of the triangular portion of the cross-section of flexible circuit <NUM> as assembled to sleeve <NUM>. Accordingly, as assembled, flexible circuit <NUM>, may be readily inserted into an outer tube or sleeve <NUM> (<FIG>) that provides an outer surface of catheter <NUM> and that defines the inner diameter within which components (e.g., flexible circuit <NUM>, beam coupling member <NUM>, coupler <NUM>) of catheter <NUM> fit. To help prevent soft spots under sleeve <NUM> that result from gaps between the substantially planar outer surfaces of segments <NUM> and <NUM>, and portion <NUM> on the one hand, and the curvature of sleeve <NUM> on the other hand, these gaps may be filled by including additional material, e.g., adhesives <NUM> and polyimide layers <NUM>, on segments <NUM> and <NUM> (of second portion <NUM> (<FIG>) and third portion <NUM> (<FIG>), respectively) and portion <NUM>. The polyimide layers <NUM> may be fabricated separately from flexible circuit <NUM> and adhered thereto, or they may be an integral portion of flexible circuit <NUM>, formed during the same lithographic process as the remainder of flexible circuit <NUM>. Polyimide layers <NUM> may interpolate the curve of sleeve <NUM> with a series of substantially planar steps or layers.

Flexible circuit <NUM> may be assembled into catheter <NUM> as follows. First, flexible circuit <NUM> may be provided. Segment <NUM> of second portion <NUM> may be folded over segment <NUM> of second portion <NUM> to overlap it and contact it by deforming connector <NUM> and, if included, connector <NUM>. Segment <NUM> of third portion <NUM> may be folded over segment <NUM> of third portion <NUM> to overlap it and contact it by deforming connector <NUM> and, if included, connector <NUM>. First portion <NUM> of flexible circuit <NUM> may be oriented to be parallel to bottom face <NUM> of beam coupling member <NUM>, which is oriented transversely (e.g., less than thirty degrees from a perpendicular plane) to a longitudinal axis of beam coupling member <NUM>. First portion <NUM> may then be adhered to bottom face <NUM> of beam coupling member <NUM>. Coupler <NUM> having substantially planar surface portions may be provided and oriented to align its longitudinal axis with the longitudinal axis of the beam coupling member <NUM>. Second portion <NUM> and third portion <NUM> may be oriented to be parallel to respective substantially planar surface portions of coupler <NUM>. Then, second portion <NUM> and third portion <NUM> may be adhered to the respective substantially planar surface portions of coupler <NUM>. Coupler <NUM>, adhered to flexible circuit <NUM>, may then be coupled or inserted into outer sleeve <NUM>. Finally, tip <NUM> may be affixed to beam coupling member <NUM>. Flexible circuit <NUM> may be adhered to top face <NUM> of beam coupling member <NUM> at nearly any step of the process so long as tip <NUM> has not been attached to beam coupling member <NUM>.

Reference is now made to <FIG>, which is a schematic view of a balloon catheter <NUM> constructed and operative in accordance with an embodiment of the present invention. Reference is also made to <FIG>, which are semi-transparent views of the balloon catheter <NUM> of <FIG>. In all subsequent figures herein, it should be understood that beam member <NUM> of <FIG> could be utilized with a particular variation shown and described in <FIG>.

The balloon catheter <NUM> is configured to be inserted into a body-part (such as a heart chamber, or any other suitable body-part) of a living subject. The balloon catheter <NUM> includes an insertion tube <NUM> having a distal tip <NUM>. The insertion tube <NUM> may have any suitable outer diameter according to the body-part in which the balloon catheter <NUM> is to be inserted. In some embodiments, the outer diameter of the insertion tube <NUM> is about <NUM>.

The balloon catheter <NUM> includes an inflatable balloon <NUM> including: a proximal portion <NUM> connected to the distal tip <NUM> of the insertion tube <NUM> via a force sensor <NUM>; and multiple electrodes <NUM> disposed thereon. The inflatable balloon <NUM> also includes various irrigation apertures <NUM> (only one is labeled for the sake of simplicity). The inflatable balloon <NUM> may have any suitable diameter when fully inflated. In some embodiments, the inflatable balloon <NUM> has an outer diameter of less than <NUM>. The electrodes <NUM> are configured to contact tissue at respective locations in the body-part. Each electrode <NUM> is a flexible electrode formed, for example, from a polyamide substrate with a gold covering thereon, or any other suitable combination of materials. Each electrode <NUM> is connected to a proximal end of the insertion tube <NUM> via wires (not shown) which may also function as a temperature sensor to provide a signal indicative of temperature of the electrode <NUM> for use during ablation.

The balloon catheter <NUM> includes a force sensor <NUM> disposed proximate the distal tip <NUM> of the insertion tube <NUM> and configured to output at least one force signal indicative of a magnitude and a direction of a force applied by the inflatable balloon <NUM> when inflated on the tissue. The force sensor <NUM> is disposed between the distal tip <NUM> of the insertion tube <NUM> and the proximal portion <NUM> of the inflatable balloon <NUM>.

The force sensor <NUM> is connected to the insertion tube <NUM> and the inflatable balloon <NUM> using a lower coupler <NUM> and an upper coupler <NUM>, respectively. The lower coupler <NUM> and the upper coupler <NUM> may use any suitable coupling mechanism, for example, but not limited, a screw fitting, a bayonet fitting, or a pressure fit coupling.

The balloon catheter <NUM> includes at least one position sensor <NUM> configured to output at least one position signal indicative of a position of the inflatable balloon <NUM> and/or the distal tip <NUM>. The position sensor <NUM> is described in more detail with reference to <FIG> and may comprise one or more magnetic coils. In some embodiments, the electrodes <NUM> may be used as position sensors in conjunction with the body-surface electrodes <NUM> (<FIG>) using a current-based, or impedance-based location tracking method, or a combined magnetic and current/impedance-based location tracking method described above in more detail with reference to <FIG>.

Due to the small size of the balloon, after deflation, the balloon shrinks to a diameter of around <NUM> without the need of a central extension tube, used in many balloon structures, to straighten out the deflated balloon for reinsertion into a sheath. The inflatable balloon may be easily maneuvered around the chambers of the heart, allowing ablation of large regions of heart tissue to be performed quickly, thus shortening the ablation time compared to a focal catheter.

During ablation, RF power may be applied to all the electrodes <NUM> equally or a multichannel RF generator may be used to selectively apply power to each of the electrodes <NUM>. The power levels may be controlled according to temperature feedback or by manually controlling the power. The electrodes <NUM> may also be used to sense electrical activity in the body part, for example IEGMs.

<FIG> and <FIG> show a coupler/flow diverter <NUM> connected to the distal portion of the force sensor <NUM>. The coupler/flow diverter <NUM> is an elongated element which extends distally and is coaxial with the insertion tube <NUM> (<FIG> and <FIG>). An irrigation line <NUM> is disposed in the insertion tube <NUM> and extends into a central portion of the coupler/flow diverter <NUM> and is bonded to a proximal section of the coupler/flow diverter <NUM>. The coupler/flow diverter <NUM> includes irrigation ports <NUM> therein through which irrigation fluid enters the inflatable balloon <NUM> from an opening at the end of the irrigation line <NUM>. Wires <NUM> (also functioning as temperature sensors) connecting to the electrodes <NUM> are fed through the insertion tube <NUM> and exist out of proximal elongated openings <NUM> in the coupler/flow diverter <NUM>. These openings are then sealed to prevent irrigation fluid from entering the insertion tube <NUM>.

The inflatable balloon <NUM> is bonded to the proximal section and the distal section of the coupler/flow diverter <NUM>. At the distal section of the inflatable balloon <NUM>, a polymer ring <NUM> secures the inflatable balloon <NUM> and/or distal portions of the electrodes <NUM> to the coupler/flow diverter <NUM> in order to prevent the electrodes <NUM> from delaminating. A partial balloon <NUM> covers the inflatable balloon <NUM> and the proximal section of the inflatable balloon <NUM> to protect the wires <NUM> and non-ablation surfaces of electrodes <NUM>. The partial balloon <NUM> may be configured to take on a portion of a hemisphere to ensure that certain components such as wirings and circuit trace are protected between the main balloon <NUM> and the partial balloon <NUM>.

<FIG> and <FIG> show a protector sleeve <NUM> covering the force sensor <NUM>, the x-axis coil <NUM>, the y-axis coil <NUM> and the solder pad area <NUM>. The protector sleeve <NUM> is typically formed from any suitable plastic. A deflectable element <NUM> (in the form of a pull cable) may be disposed in the distal portion of the insertion tube <NUM> to facilitate deflection of the balloon catheter <NUM> as shown in <FIG>.

<FIG> illustrates a sectional view of the exemplary end effector of catheter <NUM>. Starting from distal tip <NUM> of tubular member <NUM>, a first (or lower) coupler <NUM> is provided that extends along longitudinal axis L-L of the tubular member <NUM> through a central opening defined by the location sensor coils <NUM>, <NUM> and beam coupling member <NUM> and the contact-force coil circuits <NUM> and <NUM>. The first coupler <NUM> terminates just at 314a and 314b before physical contact with the coil <NUM> (leaving a small gap between the coupler <NUM> and the coil <NUM>). Coupler <NUM> is coupled to the beam coupling member <NUM>, shown here in <FIG> with other components hidden for clarity. Irrigation fluid (arrow) is delivered along an irrigation tube <NUM> that extends through coupler <NUM>, beam coupling <NUM>, coupler <NUM> such that the irrigation fluid impinges against flat surface 332a to redirect fluid flow approximately <NUM> degrees or more out of ports <NUM>.

Referring to <FIG>, which is an exploded view for components discussed in <FIG>, coupler <NUM> is provided with a plurality of notches 314a, 314b, 314c on the periphery of cylindrical member <NUM> for corresponding engagement with protrusions 194a, 194b, 194c of beam coupling member <NUM>.

A second coupler <NUM> is provided with notches 316a, 316b, 316c that mates with protrusions 192a, 192b, 192c of beam coupling member <NUM>. Flat surfaces 316d (three shown for coupler <NUM>) are formed whereby each flat surface 316d is angulated with respect to the axis L-L so that each flat surface is complementary to the angulation <NUM> defined by the helicoid path of ramp 193a, 193b, 193c (i.e., helix angle). Three flat surfaces (not shown due to the perspective view) 314d are also provided for coupler <NUM> in a configuration similar to flat surface 316d of coupler <NUM> in that the three flat surfaces 314d are also angulated with respect to the axis L-L so that each flat surface 314d of coupler <NUM> are generally parallel to the angulation path <NUM> defined by the helicoid ramp 193a, 193b, 193c as well as flat surface 316d.

The location sensor coils <NUM> and <NUM> are mounted to the first coupler <NUM> in a generally equiangular configuration about the axis L-L. It is noted that while two coils (for XY axes) are used in an exemplary embodiment to determine the location of these coils (as mounted to the coupler and thereby the location of the balloon as the distance between balloon and the location sensor is known), in certain circumstances, only one location sensing coil may be utilized if the other two axes are known via other visualization techniques. As well, three location sensing coils may also be used depending on the packaging constraints of the catheter.

<FIG> illustrates the beam coupling member <NUM> (with other components hidden to better show the structural details). Beam coupling member <NUM> defines generally a cylindrical form factor about the axis L-L so that beam coupling member <NUM> can be mounted inside the catheter outer tube <NUM>. Extending along axis L-L to a first (or distal) end in <FIG> are three arms <NUM>, each with protrusions 192a, 192b, 192c whereby each protrusion (192a, 192b, or 192c) further extends along a circumferential direction with respect to longitudinal axis L-L. At the other end, extending along axis L-L to a second (or proximal) end in <FIG> are three arms <NUM>, each with protrusions 194a, 194b, 194c whereby each protrusion (194a, 194b, or 194c) further extends along a circumferential direction with respect to the longitudinal axis L-L. It is noted that when beam coupling member <NUM> is viewed with the observer located at the proximal side on axis L-L, protrusions 192a, 192b and 192c extend away from each arm <NUM> in a counter-clockwise circumferential direction. Contrast this with protrusion 194a, 194b, and 194c (at the other end) which extend away from each arm <NUM> in a clock-wise circumferential direction. This opposite orientation feature of the protrusions ensures that the couplers <NUM> and <NUM> stay connected (via respective notches 314a and 316a) in the catheter once the proximal protrusions (194a, 194b, 194c) of the beam coupling member <NUM> engages notches (314a, 314b, 314c) of first coupler <NUM> and the distal protrusions (192a, 192b, 192c) engage with notches (316a, 316b, 316c) of the second coupler <NUM>.

Each protrusion 192a, 192b, 192c is configured to divide into two members so that elements of a biasing or spring member can be formed. For example, protrusion 192a is divided into helicoid ramps 191a and 193a that extend in a circumferential direction with respect to axis L-L and along L-L. Helicoid 191a and 193a defines a spiral-like path around axis L-L and along axis L-L to rejoin at protrusion 194b. As well, protrusion 192b at one end (e.g., distal end) is divided into two helicoid ramps 191b and 193b separated by a through-gap between the two helicoid ramps 191b and 193b and whereby the two ramps 191b and 193b are rejoined at protrusion 194c at the other end (e.g., proximal). Finally, protrusion 192c is divided into ramps 191c and 193c (with a through-gap between them) that spiral around the axis L-L and rejoin at protrusion 194a.

By forming these spiral ramps (with a gap in between each ramp), applicant is able to transform what is essentially a beam-like structure into a hybrid beam-spring coupling with three spiral spring windings. Beyond achieving the function of a coil spring, this design enables applicant to: (a) retain flex circuit <NUM> between protrusions 192a, 192b, 192c via notches <NUM>; (b) retain flex circuit <NUM> between protrusions 194a, 194b, 194c via circumferential notches <NUM>; and (c) retain couplers <NUM> and <NUM> from separation; and (d) transmit forces to protrusions 192a, 192b, 192c from coupler <NUM> and transmit forces to protrusions 194a, 194b, 194c from coupler <NUM> for measurement of the displacement between each of the pie-shaped pair of flex circuits <NUM> and <NUM>. These features are heretofore not available in this field but for applicant's design described herein.

With this configuration of the couplers <NUM> and <NUM> to the beam coupling member <NUM>, forces applied from the balloon <NUM> to the coupler <NUM> are transmitted to the beam coupling member <NUM> such that displacement of discrete portions of beam coupling member <NUM> can be determined (given that spring constant k of beam coupling member <NUM> is known prior to installation) by measuring the displacement in the distance "d" between each pair of trefoil force sensor segment in respective flex circuits <NUM> and <NUM>. Alternatively, after final assembly balloon catheter <NUM> may be tested to determine constant k, taking into account effects of protector sleeve <NUM>, irrigation line <NUM>, wires <NUM>, and any other components that are functionally in parallel with beam coupling member <NUM>. The results of the testing can be used to calibrate the force sensor to eliminate inaccuracies caused by variations in assembly or manufacturing of components.

As can be seen in <FIG>, each of the trefoil force sensor segment <NUM>, <NUM>, <NUM> for flex circuit <NUM> is mounted in the beam coupling member <NUM> such that each segment <NUM>, <NUM>, <NUM> has a counterpart segment with flex circuit <NUM>. For example, segment <NUM> of flex circuit <NUM> is mounted to be parallel to segment <NUM> of flex circuit <NUM> at a specified distance "d" (which distance "d" can change when forces are applied to coupler <NUM> or <NUM>). The remainder of the force sensor coil segments <NUM> and <NUM> of flex circuit <NUM> are mounted in a similar manner with the respective trefoil force sensor segment of flex circuit <NUM>. Displacement for each pair of trefoil force sensor segment will allow console <NUM> to determine the angle and direction of forces being applied to which one of the pie-shaped force sensor coil segment pairs. For example, when distance "d" (opposite facing arrows in <FIG>) between force sensor coil segments <NUM> and <NUM> is changed without the distance on the other two pair of force sensor coil segments being changed, then the processor of the system is able to determine that a force is being applied along one of the directions designated by the dual-facing arrow (<FIG>).

Reference is now made to <FIG> and <FIG>, which are semi-transparent views of sensors of the balloon catheter <NUM> of <FIG>. The force sensor <NUM> is comprised of the beam coupling member <NUM> with the first portion <NUM> of flexible circuit <NUM> (<FIG>) disposed on bottom face of the beam coupling member <NUM>, and the flexible circuit <NUM> disposed on the top face of the beam coupling member <NUM>. In some embodiments, the first portion <NUM> is disposed on top face, and the flexible circuit <NUM> is disposed on the bottom face. The various components of the beam coupling member <NUM>, and the flexible circuits <NUM>, <NUM> have been described in detail with reference to <FIG>.

<FIG> shows a solder pad area <NUM> which includes a plurality of solder pads (e.g., about eleven), which may include the solder joints <NUM> of portion <NUM> (<FIG>) for connecting the coils of the flexible circuit <NUM> (<FIG>) and optionally the coil(s) of the flexible circuit <NUM> to the console <NUM> (<FIG>). <FIG> shows an x-axis coil <NUM> and a y-axis coil <NUM> forming part of the position sensor <NUM>. The x-axis coil <NUM> and the y-axis coil <NUM> may be formed from the segments <NUM>, <NUM>, <NUM>, and <NUM>, described above with reference to <FIG> and <FIG> in more detail.

Reference is now made to <FIG>, which is a flowchart <NUM> including steps in a method of operation of the system <NUM> of <FIG> using the balloon catheter <NUM> of <FIG>. The steps described below do not need to be performed in the order described. The steps may be performed in any suitable order. Some of the steps may be performed in parallel to each other.

The processor <NUM> (<FIG>) is configured to receive (block <NUM>) force signal(s) from the force sensor <NUM> (<FIG>). The processor <NUM> (<FIG>) is configured to compute (block <NUM>) a magnitude and direction of a force measured by the force sensor <NUM> responsively to the force signal(s).

The force sensor <NUM> may be calibrated using any suitable method. In accordance with some embodiments, the distal tip <NUM> is held in a clamp or other apparatus, while the inflatable balloon <NUM> is deflected using a robot. The robot measures the lateral and angular displacement of the inflatable balloon <NUM> with respect to the distal tip <NUM>, and the corresponding force applied on the inflatable balloon <NUM> by the robot using a strain gauge, as well as the corresponding force signal(s) provided by the force sensor <NUM>. The robot may also perform the above measurements while applying the force from different directions around the axis of the inflatable balloon <NUM>. The calibration measurements may then be stored in a table, or the like, for future lookup. Therefore, in use of the system <NUM>, the magnitude and direction of the force applied by the inflatable balloon <NUM> may be computed from force signal(s) output by the force sensor <NUM> by looking up corresponding values in the table and by performing appropriate interpolation or extrapolation of the values found in the table. The force signal(s) are also indicative of a lateral and angular displacement of the inflatable balloon <NUM> with respect to the distal tip <NUM> and may therefore be used to determine the lateral and angular displacement of the inflatable balloon <NUM> with respect to the distal tip <NUM> and therefore the position (location and orientation) of the inflatable balloon <NUM> (described in more detail below).

The processor <NUM> (<FIG>) is configured to receive (block <NUM>) position signal(s) from the position sensor <NUM> (<FIG>, <FIG>, <FIG>) and/or the electrodes <NUM> (<FIG> and <FIG>). The processor <NUM> (<FIG>) is configured to compute (block <NUM>) the position of the distal tip <NUM> responsively to the position signal(s). The processor <NUM> is configured to compute (block <NUM>) a position (location and orientation) of the inflatable balloon responsively to the computed position of the distal tip <NUM> and the force signal(s) (which yields the lateral and angular displacement of the inflatable balloon <NUM> with respect to the distal tip <NUM>).

The processor <NUM> (<FIG>) is configured to receive (block <NUM>) contact signals from the electrodes <NUM> (<FIG> and <FIG>). The processor <NUM> (<FIG>) is configured in response to the contact signals, to assess (block <NUM>) a respective quality of contact of each of the electrodes <NUM> with the tissue.

Reference is now made to <FIG>, which is a schematic view of rendering a representation <NUM> of the balloon catheter <NUM> of <FIG> and a representation <NUM> of a force vector. Reference is also made to <FIG>.

The processor <NUM> (<FIG>) is configured to render (block <NUM>) to the display <NUM> the representation <NUM> of the force vector responsively to the computed magnitude and direction, and the representation <NUM> of the inflatable balloon <NUM> (<FIG>) responsively to the computed position of the inflatable balloon <NUM> (which is based on the computed position of the distal tip <NUM> and the force signal(s), as described above with the step of block <NUM> of <FIG>), while modifying a visual feature of one(s) of the electrodes <NUM> (<FIG>) responsively to the respective quality of contact of the electrodes <NUM> with the tissue at the respective locations. The electrodes <NUM> having a quality of contact above a given quality of contact are highlighted as compared to other electrodes <NUM>. The electrode representations in <FIG> are labeled with reference numeral <NUM>. The highlighted electrodes may be displayed in a different color and/or using a greater brightness and/or using a border or any suitable way to distinguish the electrodes <NUM> having the quality of contact above the given quality of contact as compared to other electrodes <NUM>. The electrodes <NUM> may be labeled using electrode numbers <NUM> to allow the operator <NUM> to easily identify which electrodes are in contact with the tissue. In <FIG>, the highlighted electrodes include the electrode numbers <NUM>, while non-highlighted electrodes do not include the electrode numbers <NUM>. In some embodiments, both highlighted and non-highlighted electrodes may be numbered. The representation <NUM> of the balloon catheter <NUM> and the representation <NUM> of the force vector may also be displayed with an image <NUM> of the body-part in which the balloon catheter <NUM> is inserted. The image <NUM> of the body-part may be acquired from a CT or MRI scan, or any suitable scan, which has been preregistered with the system <NUM> (<FIG>). The steps <NUM>-<NUM> may be performed in any suitable order and may be repeated intermittently or periodically so as to update the position of the balloon catheter <NUM> with respect to the body-part and/or the size and magnitude of the force vector.

Claim 1:
A system (<NUM>) comprising a balloon catheter configured to be inserted into a body-part of a living subject, the balloon catheter comprising:
an insertion tube (<NUM>) having a distal tip (<NUM>);
a force sensor (<NUM>) connected to the distal tip; an inflatable balloon (<NUM>) including: a proximal portion (<NUM>) connected to the force sensor so that the force sensor is disposed between the distal tip of the insertion tube and the inflatable balloon; and multiple electrodes (<NUM>) disposed around an outer surface of the balloon, and configured, when the balloon is inflated, to contact tissue at respective locations in the body-part; wherein the force sensor is configured to output at least one force signal indicative of a magnitude and a direction of a force applied by the balloon on the tissue when the balloon is inflated;
a display (<NUM>); and
processing circuitry (<NUM>) configured to:
receive contact signals from the electrodes;
in response to the contact signals, assess a respective quality of contact of each of the electrodes with the tissue;
compute the magnitude and direction of the force responsively to the at least one force signal; and
render to the display a representation of a force vector and a representation of the inflatable balloon, responsively to the at least one force signal, while modifying a visual feature of at least one of the represented electrodes responsively to the respective quality of contact of the electrodes.