Balloon catheter with force sensor

Abstract

To provide a system including a balloon catheter.SOLUTION: In one embodiment, a system includes a balloon catheter configured to be inserted into a body part of a living subject, the balloon catheter comprising 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, where 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.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to medical devices, and in particular to balloon catheters. [Background technology]

[0002] Cardiac arrhythmias, such as atrial fibrillation, occur when areas of cardiac tissue disrupt the normal cardiac cycle by abnormally conducting electrical signals to adjacent tissue, causing an asynchronous rhythm.

[0003] Treatments for arrhythmias include surgically destroying the source of the signals causing the arrhythmia and disrupting the conduction pathways of those signals. By selectively ablating cardiac tissue with the application of energy via a catheter, it is sometimes possible to prevent or redirect the propagation of unwanted electrical signals from one part of the heart to another. Ablation techniques disrupt unwanted electrical pathways by creating non-conducting lesions.

[0004] Demonstrating physical electrode contact with the target tissue is important for controlling the delivery of ablation energy. Attempts to demonstrate tissue-electrode contact have been extensively made in the art, and various techniques have been proposed. For example, U.S. Patent No. 6,695,808 describes an apparatus for treating a selected tissue or organ region of a patient. A probe has a contact surface that can be pressed against the region, thereby generating contact pressure. A pressure transducer measures the contact pressure. This configuration is said to satisfy the treatment requirement that the medical device must be firmly positioned without excessive contact with the anatomical surface by providing the device user with information indicative of the presence and magnitude of contact force.

[0005] As another example, U.S. Patent No. 6,241,724 describes a method for creating lesions in body tissue using a segmented electrode assembly. In one embodiment, the electrode assembly on the catheter has a pressure transducer that senses contact with tissue and transmits a signal to a pressure contact module. The module identifies the electrode elements associated with the pressure transducer signal and instructs the energy generator to transmit radio frequency energy to those elements and not to other elements that are in contact only with blood.

[0006] A further example is provided in U.S. Patent No. 6,915,149, which describes a method for mapping the heart using a catheter with a tip electrode for measuring local electrical activity. To avoid artifacts that may arise from poor contact between the tip and tissue, the contact pressure between the tip and tissue is measured using a pressure sensor to ensure stable contact.

[0007] U.S. Patent Application Publication No. 2007 / 0100332 describes a system and method for assessing electrode-tissue contact for tissue ablation. An electromechanical sensor within the shaft of a catheter generates an electrical signal corresponding to the amount of movement of an electrode within the distal portion of the catheter shaft. An output device receives the electrical signal to assess the level of contact between the electrode and tissue.

[0008] U.S. Patent Application Publication No. 2009 / 0093806 to Govari et al., incorporated herein by reference, describes another application of contact pressure measurement, in which deformation in response to pressure on an elastic member located at the distal end of a catheter is measured using a sensor.

[0009] Several references, including U.S. Patent Nos. 5,935,079, 5,891,095, 5,836,990, 5,836,874, 5,673,704, 5,662,108, 5,469,857, 5,447,529, 5,341,807, 5,078,714, and Canadian Patent Application No. 2,285,342, report methods for determining electrode-tissue contact. Some of these references, such as U.S. Patent Nos. 5,935,079, 5,836,990, and 5,447,529, determine electrode-tissue contact by measuring impedance between the tip and return electrodes. As disclosed in the '529 patent, it is known that the impedance through blood is generally lower than the impedance through tissue, and therefore tissue contact is detected by comparing the impedance value across a set of electrodes with previously measured impedance values ​​when one electrode is known to be in contact with tissue and when one electrode is known to be in contact with only blood.

[0010] U.S. Patent No. 9,168,004 to Gliner et al., incorporated herein by reference, describes using machine learning to determine catheter electrode contact. The '004 patent describes a cardiac catheterization procedure performed by storing an indication of contact between a probe electrode and the heart wall as either in contact or out of contact, making a series of determinations of the impedance phase angle of current flowing through this electrode and another electrode, identifying a maximum and minimum phase angle in the series of determinations, and defining a binary classifier as the midpoint between the extremes. A test value is compared to the classifier as adjusted by a hysteresis coefficient, and a change in steady state is reported if the test value is greater than or less than the adjusted classifier.

[0011] U.S. Patent Publication No. 2015 / 0141987 to Caplan et al. describes a device for ablating target tissue in a patient using electrical energy. 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 the target tissue is attached to the radially expandable element. The device can be constructed and arranged to ablate the patient's duodenal mucosa while avoiding damage to adventitial duodenal tissue. Systems and methods for treating target tissue are also provided.

[0012] MEDTRONIC Ardian LLC's PCT Patent Publication No. WO 2011 / 139589 states that herein disclosed are catheterization devices, systems, and methods for achieving renal neuromodulation via intravascular access. One aspect relates to devices, systems, and methods incorporating a catheterization device with an elongate shaft sized and configured to deliver an energy delivery element to a renal artery via an intravascular pathway. Thermal or electrical renal neuromodulation can be achieved through the direct and / or indirect application of thermal and / or electrical energy to heat, cool, or otherwise electrically modulate nerve fibers contributing to renal function or the vasculature supplying or perfusing the nerve fibers.

[0013] U.S. Patent Publication No. 2005 / 0203597 to Yamazaki et al. describes a catheter for treating arrhythmias that includes a catheter shaft with a double-cylindrical structure, where an inner shaft is slidably inserted into an outer shaft, and a balloon is disposed between the distal end portion of the inner shaft and the distal end portion of the outer shaft, a pair of high-frequency current-carrying electrodes, at least one of which is provided inside the balloon, and a temperature sensor for monitoring the temperature at the balloon. A leading edge portion of the balloon, at least in a deflated state, protrudes from the distal end portion of the inner shaft. Alternatively, a tube that is more flexible than the inner shaft is provided on the distal end portion of the inner shaft.

[0014] US Patent No. 4,744,366 to Jang describes a catheter for performing balloon angioplasty that includes concentric, independently inflatable / deflatable balloons, each balloon having a different diameter.

[0015] U.S. Patent Publication No. 2018 / 0280080 to Govari et al. describes a medical device including a probe having a distal end configured for insertion into a body cavity and including a lumen opening through the distal end, and an inflatable balloon positionable through the lumen into the body cavity such that when the balloon is positioned through the lumen and inflated, a distal pole on the distal side of the balloon is located on the opposite side of the lumen. The medical device also includes an electrode attached to the distal side of the inflatable balloon and extending across at least 50% of the area distal to the balloon within 30 degrees of arc from the distal pole. Summary of the Invention [Means for solving the problem]

[0016] According to one embodiment of the present disclosure, there is provided a system including a balloon catheter configured to be inserted into a body part of a living subject, the balloon catheter comprising: an insertion tube having a distal tip; a force sensor connected to the distal tip; a proximal portion connected to the force sensor such that the force sensor is disposed between the distal tip of the insertion tube and an inflatable balloon; and an inflation balloon including a plurality of electrodes disposed around an outer surface of the balloon and configured to contact tissue at respective locations in the body part when the balloon is inflated, 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 to the tissue when the balloon is inflated.

[0017] Further, in accordance with one embodiment of the present disclosure, the system includes a display and a processing circuit configured to calculate a force magnitude and direction in response to the at least one force signal, and to render a representation of the force vector and a representation of the inflatable balloon on the display in response to the at least one force signal.

[0018] Still further, in accordance with one 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, and the processing circuitry is configured to calculate a position of the distal tip in response to the at least one position signal and render on the display a representation of a force vector in response to the calculated magnitude and direction and a representation of the inflatable balloon in response to the calculated position and the at least one force signal.

[0019] Additionally, according to one embodiment of the present disclosure, the processing circuitry is configured to receive contact signals from the electrodes, evaluate a respective quality of contact of each of the electrodes with the tissue in response to the contact signals, and render a representation of the inflatable balloon on the display while modifying visual characteristics of the electrodes in response to the respective quality of contact of the electrodes with the tissue at the respective locations.

[0020] Furthermore, according to one embodiment of the present disclosure, each of the electrodes is a flexible electrode formed from a polyamide substrate having a gold coating thereon.

[0021] According to another embodiment of the present disclosure, there is provided an electrophysiology catheter device including: a tubular member extending from a proximal portion to a distal portion along a longitudinal axis; a first coupler member connected to the distal portion of the tubular member; a beam combining member coupled to the first coupler member by at least one first protrusion on one of the beam combining member and the first coupler member, the one first protrusion being engaged with at least one first notch on the other of the beam combining member and the first coupler member; and a second coupler member coupled to the beam combining member by at least one second protrusion on one of the beam combining member and the second coupler member, the at least one second protrusion being engaged with at least one second notch on the other of the beam combining member and the second coupler member.

[0022] Furthermore, according to one embodiment of the present disclosure, the device includes a balloon connected to the second coupler member.

[0023] Furthermore, in accordance with one embodiment of the present disclosure, the beam connecting member defines a generally cylindrical surface extending from a first end to a second end, each of the first and second ends having at least one arm extending along a longitudinal axis, the at least one arm defining a protrusion extending circumferentially about the longitudinal axis.

[0024] Additionally, according to one embodiment of the present disclosure, the at least one arm at the first end includes three arms extending toward the first coupler member, and the at least one arm at the second end includes three arms extending toward the second coupler member, each arm having a protrusion extending circumferentially about the longitudinal axis.

[0025] Furthermore, according to one embodiment of the present disclosure, the protrusion proximate the first end is configured to be divided into two inclined portions that extend in a spiral direction along the longitudinal axis toward another protrusion proximate the second end.

[0026] Further, according to one embodiment of the present disclosure, the first coupler member includes a notch configured to mate with a protrusion of the at least one arm at the first end, and the second coupler member includes a notch configured to mate with a protrusion of the at least one arm at the second end.

[0027] Still further, in accordance with one embodiment of the present disclosure, the apparatus includes a flex circuit having at least one position sensing coil attached to one of the first and second coupler members.

[0028] Additionally, according to one embodiment of the present disclosure, the at least one position sensing coil includes two position sensing coils.

[0029] Furthermore, according to one 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.

[0030] Furthermore, according to one embodiment of the present disclosure, the device includes at least one ablation electrode mounted on the balloon and at least one temperature sensor mounted on the balloon.

[0031] 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. [Brief explanation of the drawings]

[0032] The present invention will be understood from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is a pictorial illustration of a system for assessing electrical activity in the heart of a living subject and providing treatment thereto using a catheter constructed and operative in accordance with an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram of the flexible circuit of the catheter of FIG. 1. [Figure 3] FIG. 3 is a schematic diagram of the flexible circuit of FIG. 2 in a folded configuration. [Figure 4] FIG. 2 is a schematic diagram of another flexible circuit of the catheter of FIG. 1. [Figure 5] 2 is a schematic diagram of a beam combining member 190 of the catheter of FIG. 1. [Figure 6] FIG. 2 is a first cross-sectional view of the distal portion of the catheter of FIG. 1. [Figure 7] FIG. 2 is a second cross-sectional view of the distal portion of the catheter of FIG. 1. [Figure 8] FIG. 7 is a cross-sectional view taken through line AA of FIG. 6. [Figure 9] 1 is a schematic illustration of a balloon catheter constructed and operative in accordance with one embodiment of the present invention; [Figure 10A] FIG. 10 is a semi-transparent view of the balloon catheter of FIG. [Figure 10B] FIG. 10 is a semi-transparent view of the balloon catheter of FIG. [Figure 10C] FIG. 10 is a semi-transparent view of the balloon catheter of FIG. [Figure 10D] FIG. 10 is a semi-transparent view of the balloon catheter of FIG. [Figure 10E] FIG. 10 is a cross-sectional perspective view showing components inside the catheter of FIG. 9. [Figure 10F] FIG. 10F is an exploded view of certain components of FIG. 10E, as aligned with longitudinal axis LL when assembled. [Figure 10G] FIG. 10F is a perspective view of the beam connecting member shown in FIG. [Figure 11] FIG. 10 is a semi-transparent view of the sensor of the balloon catheter of FIG. 9. [Figure 12] FIG. 10 is a semi-transparent view of the sensor of the balloon catheter of FIG. 9. [Figure 13] 10 is a flow diagram including steps in a method of operation of the system of FIG. 1 using the balloon catheter of FIG. 9. [Figure 14] FIG. 10 is a schematic diagram rendering a representation and force vectors of the balloon catheter of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0033] Overview Balloon catheters are inflated to a diameter of approximately 25 mm or greater and can generally be used to simultaneously perform ablations over a relatively large area, such as the ostia of a pulmonary vein. Regional catheters, on the other hand, generally have a diameter of approximately 2.5 mm and are more suitable for performing relatively "precise" ablations within cardiac chambers. To expand the ablation area, regional catheters can be used for multiple, sequential ablations. Performing point-by-point ablations using regional catheters can be time-consuming, which can be a significant factor when performing cardiac procedures.

[0034] Embodiments of the present invention overcome the above problems by providing a system including a balloon catheter that, when fully inflated, has a diameter of about 15 mm or less. Due to the small size of the balloon, after deflation, the balloon collapses to a diameter of about 3 mm without the need for a central extension tube used in many balloon structures to straighten the deflated balloon for reinsertion into the sheath.

[0035] Inflatable balloons are easily maneuvered around the heart cavities to rapidly perform ablation of large areas of cardiac tissue, thus reducing ablation times compared to regional catheters.

[0036] The inflatable balloon includes a flexible electrode disposed thereon for sensing electrical signals and / or applying radio frequency energy to perform ablation. Wires extending from the rear of the electrode can also function as temperature sensors for use in sensing electrode and / or tissue temperature during ablation.

[0037] The maneuverability of an inflated balloon within a cardiac cavity highlights a new problem: a large balloon performing ablation within a pulmonary vein occludes the vein due to its large size, and all electrodes around the surface of the balloon make sufficient contact with the venous tissue to provide a good lesion. However, with a small balloon, sufficient electrode contact with the tissue is not guaranteed.

[0038] Embodiments of the present invention overcome the above problems by providing a balloon catheter with a force sensor 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 can be rendered on a display with a representation of the balloon catheter. The force vector can be used by an operator of the system to estimate the magnitude and direction of the force applied by the balloon to the cardiac tissue, thereby configuring the electrodes to be used to perform the ablation, the power to use, and the duration. In some embodiments, the force vector can indicate the force applied by the cardiac tissue to the balloon.

[0039] In some embodiments of the present invention, the sufficiency of tissue contact between individual electrodes and tissue is used to determine whether to highlight the electrode on a representation of an inflatable balloon rendered on a display. Contact quality can be assessed based on different methods, including, for example, simply using changes in impedance value and / or impedance phase, as described in more detail below, or based on the amplitude of an intracardiac electrogram (IEGM) signal. Contact quality based on impedance or other electrical methods can provide an indication of whether an electrode is in contact (or at least in close proximity) with tissue, but impedance generally does not provide an accurate picture of the degree of contact. Using contact quality in combination with the force vector provides the system operator with a more accurate picture of the degree of contact. The system operator can then configure which electrodes to use, at what power, and for what duration to perform ablation, taking into account both the force vector and the highlighted electrodes. For example, the highlighted electrodes may be identified by the operator as being in sufficient contact with the tissue based on the direction of the force vector. As another example, if the force vector indicates that the applied force is low, the force direction corresponds to the highlighted electrodes, and the highlighted electrodes indicate that many of the electrodes are in contact with tissue, the operator can assume that the catheter is in a region of soft tissue and is partially or completely surrounded by tissue, possibly because the catheter is submerged in the tissue. The operator can then use this information to set the ablation power and duration according to the assumption that the tissue is soft tissue by using lower power for a shorter period of time. As yet another example, if the force vector indicates that the applied force is high, the force direction corresponds to the highlighted electrodes, and the highlighted electrodes indicate that one or two electrodes are in contact with tissue, the operator can assume that the catheter is in a region of hard tissue (e.g., scar tissue). The operator can then use this information to set the ablation power and duration according to the assumption that the tissue is hard tissue by using higher power for a longer period of time.

[0040] In response to signals provided by the catheter electrodes (and optionally, the body surface electrodes), the processing circuitry can evaluate the respective quality of contact of each of the catheter electrodes with tissue within the heart. Any one of the catheter electrodes may be in full or partial contact with cardiac tissue. In some cases, any one of the catheter electrodes may be in contact with tissue through another fluid, such as blood of various concentrations. The quality of contact (full or partial contact, or contact through another fluid) of any one of the catheter electrodes with tissue can be evaluated based on signals provided by the catheter.

[0041] The term "contact quality," as used in this specification and claims, is defined herein as a quantitative measure of the degree of electrical contact between one of the catheter electrodes and tissue. "Contact quality" may be expressed directly, e.g., in terms of measured electrical impedance, or indirectly, e.g., in terms of IEGM amplitude.

[0042] In some embodiments, the catheter may provide a signal indicative of the impedance between the catheter electrode and the body surface electrode. The indication of impedance provides an indication of contact quality. Because myocardium has a lower conductivity than blood, a high value of impedance between one catheter electrode and the body surface electrode indicates high quality of contact between that catheter electrode and the tissue. The impedance value may be selected to define a minimum contact quality that is considered to represent sufficient contact between any one of the catheter electrodes and the tissue.

[0043] In some embodiments, the impedance between one of the catheter electrodes on the catheter and another of these catheter electrodes may be used as a measure of contact quality. As disclosed in the '529 patent referenced in the Background section above, impedance through blood is generally lower than impedance through tissue. Therefore, tissue contact can be assessed by comparing the impedance value of the entire set of electrodes to previously measured impedance values ​​when one electrode is known to be in good contact with tissue and when one electrode is known to be in contact only with blood.

[0044] System Description Documents incorporated herein by reference are to be considered integral parts of this application, and unless any term is defined in those incorporated documents to the contrary, either expressly or impliedly, with a definition given herein, only the definition given herein should be considered.

[0045] Reference is now made to FIG. 1 , which is a pictorial illustration of a system 10 for assessing electrical activity in a living subject's heart 12 and providing treatment thereto using a catheter 14 constructed and operative in accordance with one embodiment of the present invention. The catheter 14 is percutaneously inserted by an operator 16 through the patient's vascular system into a chamber or vasculature of the heart 12. The operator 16, typically a physician, brings the catheter's distal tip 18 into contact with the heart wall, e.g., at an ablation target site. Electrical activity maps may be generated according to methods disclosed in U.S. Pat. Nos. 6,226,542 and 6,301,496, and commonly assigned U.S. Pat. No. 6,892,091, the disclosures of which are incorporated herein by reference in their entireties. One commercially available product embodying elements of system 10 is available as the CARTO® 3 system, available from Biosense Webster, Inc., 31 Technology Drive, Irvine, CA 92618.

[0046] For example, regions determined to be abnormal by evaluation of the electrical activity map can be ablated by application of thermal energy, e.g., by passing radiofrequency current through wires within the catheter to one or more electrodes at the distal tip 18, which apply radiofrequency energy to the target tissue. The energy is absorbed by the tissue as it heats to a point (typically above 50°C) where it permanently loses its electrical excitability. This procedure creates non-conducting lesions in the cardiac tissue that interrupt the abnormal electrical pathways that cause the arrhythmia. Such principles can be applied to different heart chambers to diagnose and treat many different types of cardiac arrhythmias.

[0047] The catheter 14 typically includes a handle 20 with suitable controls thereon to enable the operator 16 to steer, position, and orient the distal end of the catheter as desired to perform ablation. To assist the operator 16, a distal portion 18 of the catheter 14, or portions thereof adjacent thereto, includes position sensors, such as traces or coils (described below), that provide signals to a processor 22 located in a console 24.

[0048] Ablation energy and electrical signals may be transmitted to and from heart 12 through one or more ablation electrodes 32 located at or near distal tip 18 via cables 38 to console 24. Pacing and other control signals may be transmitted from console 24 through cables 38 and electrodes 32 to heart 12.

[0049] Wire connections 35 connect console 24 to body surface electrodes 30 and other components of a positioning subsystem for measuring coordinates of the position and orientation of catheter 14. Processor 22 or another processor may be an element of the positioning subsystem. Electrodes 32 and body surface electrodes 30 may be used to measure tissue impedance at the ablation site, as taught in U.S. Patent No. 7,536,218 to Govari et al., which is incorporated herein by reference in its entirety. A temperature sensor, typically a thermocouple or thermistor, may be attached on or near each of electrodes 32. Examples of temperature sensors for use with ablation electrodes are shown and described in U.S. Patent Application No. SN15 / 939,154, filed March 28, 2018, which is incorporated by reference in its entirety.

[0050] Console 24 typically includes one or more ablation power generators 25. Catheter 14 may be adapted to deliver ablation energy to the heart using any known ablation technique, such as radiofrequency energy, ultrasound energy, cryo-thermal energy, and laser-generated optical energy. Such methods are disclosed in commonly assigned U.S. Patent Nos. 6,814,733, 6,997,924, and 7,156,816, which are incorporated herein by reference in their entireties.

[0051] The positioning subsystem may also include a magnetic position tracking arrangement that generates magnetic fields within a defined working volume using a magnetic field generator 28 and senses these fields at the catheter using coils or traces disposed within the catheter, typically near the tip, to determine the position and orientation of the catheter 14. Positioning subsystems are described in U.S. Patent No. 7,756,576, which is incorporated herein by reference in its entirety, and U.S. Patent No. 7,536,218, cited above.

[0052] Operator 16 can observe and adjust the functions of catheter 14 via console 24. Console 24 includes a processor 22 that executes processing circuitry, including appropriate signal processing circuitry. Processor 22 is coupled to drive a display 29. The signal processing circuitry receives, amplifies, filters, and digitizes signals from catheter 14, including signals generated by sensors, such as electrical sensors, temperature sensors, and contact force sensors, located distally in catheter 14, as well as a plurality of position-sensing coils or traces. The digitized signals are received by console 24 and a positioning subsystem and used to calculate the position and orientation of catheter 14 and to analyze the electrical signals from the electrodes and contact force sensors.

[0053] To generate an electroanatomic map, processor 22 typically includes 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 display 29.

[0054] System 10 typically includes other elements, not shown for simplicity. For example, system 10 may include an electrocardiogram (ECG) monitor coupled to receive signals from one or more body surface electrodes to provide ECG-synchronized signals to console 24. System 10 also typically includes a reference position sensor, either on an externally affixed fiducial patch attached to the exterior of the subject's body or on an internally placed catheter inserted into heart 12 and maintained in a fixed position relative to heart 12. Conventional pumps and lines may be provided for circulating fluid through catheter 14 to cool the ablation site. System 10 includes an image processor, which may receive image data from an external imaging modality, such as an MRI unit, CT, or the like, and which may be incorporated into or invoked by processor 22 for generating and displaying images.

[0055] 2-8 describe a force and position sensor for use at the distal tip of a catheter 14. The sensor must overcome various design constraints to fit within the catheter's small internal diameter (e.g., often about 2.5 mm or less) and still provide reliable feedback. For example, a metal coil can be used to detect position within a magnetic field. Generally, larger, thicker coils provide better detection than smaller, thinner coils, but due to the smaller space within the catheter, the coil must be small and thin enough to fit within it. Furthermore, if such a coil is fabricated as a trace on a circuit board or flexible circuit via a lithographic process, this process limits the trace pitch. While the thickness of the trace can be increased using additional layers in lithography, this option can be expensive and may compromise the coil because yield decreases nonlinearly with the number of layers. These design challenges are complicated by the inclusion of additional structures in close proximity to the position trace, such as a force sensor to provide sub-gram force measurements and reduce crosstalk interference that can result from packing structures into a tight space, as well as ease of assembly and secure wiring.

[0056] Reference is now made to Figure 2, which is a schematic diagram of a flexible circuit 110 of catheter 14 of Figure 1. Flexible circuit 110 may be employed within a catheter, such as catheter 14, to provide signals indicative of position and force to processor 22 in console 24. Flexible circuit 110 includes a substantially planar substrate 112 having a first portion 114 having a first shape (e.g., circular or trilobal as shown) formed from three segments 160, 162, and 164. Flexible circuit 110 also includes a connector segment 126 and, optionally, a second portion 116 having a second shape (e.g., substantially rectangular as shown) formed from two substantially rectangular segments connected by connector segment 150. First portion 114 and second portion 116 typically have different shapes because, as described below, portion 116 is elongated and assembled with its long axis parallel to the longitudinal axis of catheter 12, while portion 114 is assembled transverse to the longitudinal axis of catheter 12 so as to fit the inner diameter of catheter 14 (i.e., have a maximum width or diameter that is less than the inner diameter of catheter 14). The substrate may be formed from any suitable material that is non-conductive and can withstand high temperatures, such as, for example, but not limited to, polyimide, polyamide, or liquid crystal polymer (LCP).

[0057] Substrate 112 may also include additional portions, such as third portion 130 and fourth portion 142. Each of these portions may further include various segments. Third portion 130 may have a similar structure to second portion 116 and may include substantially rectangular segments 132, 134 connected via at least one connector segment, such as 136 and / or 152. Fourth portion 142 may include at least three connector segments 144, 146, and 148 that connect fourth portion 142 to first portion 114, second portion 116, and third portion 130, respectively.

[0058] Electrical components may be incorporated into substrate 112 and its various portions and segments. For example, a substantially planar coil or trace used to measure force-related signals (i.e., a force-sensing coil or trace) may be disposed on first portion 114. Specifically, coil 118 may be disposed on segment 160, coil 170 may be disposed on segment 162, and coil 172 may be disposed on segment 164. Coils 118, 170, and 172 may be separate from one another as shown, or each may be connected to one or both of the remaining coils. Portions or extensions of each coil may extend from the coil to solder joints 168 (only some are labeled for simplicity) located on and soldered to fourth portion 142. If the three coils are separate from one another, each should include at least one respective line (e.g., 166, 174, and 176) that connects to solder joint 168. When the coils are separated from one another, the signal generated in each of the coils can be used to provide further detail of the force, such as an indication of the off-center force or the off-axis direction of the force. As shown, each coil on the first portion 114 includes approximately five turns. However, because signal strength is correlated with the number of turns, the number of turns may be maximized based on the size of each segment and the pitch that the lithography process can achieve.

[0059] Planar coils or traces used to measure signals related to position (i.e., position coils or traces) may also be incorporated into second portion 116 and third portion 130. Coil 120 may be disposed on segment 122, coil 128 may be disposed on segment 124, coil 138 may be disposed on segment 132, and coil 140 may be disposed on segment 134. Each of coils 120, 128, 138, and 140 may extend to a solder joint 168 on fourth portion 142. For example, coil 120 may include an extension 154 that connects to solder joint 168 via connector segment 146, and coil 128 may include an extension 156 that connects to solder joint 168 via connector segment 126, segment 122, and connector segment 146. As shown, each coil on portions 116 and 130 includes approximately five turns. However, since signal strength is correlated with the number of turns, the number of turns may be maximized based on the size of the segments 122, 124, 132, and 134 and the pitch that the lithographic process can achieve.

[0060] Second portion 116 is disposed laterally on one side of first portion 114 and fourth portion 142, such that third portion 130 is disposed laterally on the other side of first portion 114 and fourth portion 142. Thus, fourth portion 142 is disposed between first portion 114, second portion 116, and third portion 130. Furthermore, segments 122 and 124 have traces wound in opposite orientations.

[0061] The substrate 112 may be a single layer. Alternatively, it may include more layers, for example, but not limited to, 2 to 10 layers, e.g., 4 layers. In this manner, the coil may be thickened by adding layers. However, as noted above, thickening with layers results in nonlinearly reduced yields in the manufacture of the component. The flexibility of the flexible circuit 110 provides a solution to this tradeoff, as described below.

[0062] Reference is now made to FIG. 3 , which is a schematic diagram of the flexible circuit 110 of FIG. 2 in a folded configuration. By deforming or bending connectors 126 and 150, segment 124 may be folded onto segment 122 so that coil 128 aligns with coil 120. Similarly, by deforming or bending connectors 136 and 152, segment 134 may be folded onto segment 132 so that coil 140 aligns with coil 138. While connectors 150 and 152 are optional, they may assist in aligning the coils by reducing relative rotation between the segments. If substrate 112 is formed from multiple layers, e.g., four layers, after segment 124 is folded onto segment 122, coils 120 and 128 form a composite coil having three or more layers, e.g., eight layers. Folding different segments onto each other to produce a composite coil allows for the creation of coils with more layers without adversely affecting manufacturing yields.

[0063] The advantage of a thinner substrate (e.g., 4 layers) over a thicker substrate (e.g., 8 layers) is that it is easier to deform or bend, which helps to assemble the flexible circuit 110 to other catheter components, as described, and ultimately helps to fit within the inner diameter of the catheter.

[0064] Reference is now made to Figure 4, which is another schematic diagram of the flexible circuit 180 of the catheter 14 of Figure 1. The flexible circuit 180 includes a substrate 182 and a coil or coils 184. The structure of the flexible circuit 180 is similar to the structure of the first portion 114 of the flexible circuit 110. However, in various embodiments, the number or pitch of the coils may vary, and the various coils on the three segments may be separate from one another or may be integral with one another.

[0065] Reference is now made to FIG. 5, which is a schematic diagram of the beam coupling member 190 of the catheter 14 of FIG. 1. The helical beam coupling member 190 includes a top surface 192, a bottom surface 194, and various arms 196 that can be used to connect the beam coupling member 190 to other components of the catheter 14. The beam coupling member 190 has a known or predetermined spring constant that provides a relationship between distance and force according to Hooke's Law. The flexible circuit 180, the first portion 114 of the flexible circuit 110, and the helical beam coupling member 190 together form a force sensor subassembly that receives electrical signals from and provides electrical signals to the console 24, which can process the received signals to determine the force, e.g., subgram force, applied to the tip 18 of the catheter 14.

[0066] A first portion 114 of the flexible circuit 110 (including coils 118, 170, 172) is disposed on the bottom surface 194, and the coil 184 on the flexible circuit 180 is disposed on the top surface 192. In some embodiments, the first portion 114 of the flexible circuit 110 (including coils 118, 170, 172) is disposed on the top surface 192, and the coil 184 on the flexible circuit 180 is disposed on the bottom surface 194.

[0067] Wires (in cable bundle 198 in FIGS. 6 and 7 ) extending between console 24 and solder joint 168 of fourth portion 142 of flexible circuit 110 connect console 24 to coils 118, 170, and 172 on segments 160, 162, and 164 of first portion 114 via coil extensions 166, 174, and 176, respectively. Wires (also in cable bundle 198) extending from console 24 connect to coil or coils 184 on flexible circuit 180. For example, an electrical signal from console 24 having a radio frequency frequency can be used to power either coils 118, 170, and 172 on first portion 114 of flexible circuit 110 or coil 184 on flexible circuit 180. Either set of coils that receives power from console 24 may be considered a transmitter (i.e., one of flex circuits 110 or 180) because it emits an electromagnetic field that varies with the frequency of the signal received from console 24. The set of coils that is not powered by console 24 may be considered a receiver insofar as it acts like an antenna in response to the electromagnetic field from the transmitter. Thus, the receiver (i.e., the other of flex circuits 110 or 180) generates an electrical signal that can be transmitted to console 24 for analysis. The electrical signal generated by the receiver depends on the distance between the receiver and the transmitter, and therefore can be correlated to the distance between the receiver and the transmitter, which in turn correlates to the compressive displacement of the beam coupling member (e.g., on the order of 100 nanometers) and therefore to the force on tip 18 of catheter 14 that compresses spring 190.

[0068] The beam-coupling member 190 may be deflected more to one side than to another. This off-center deflection represents a lateral component of the force being applied by the tip 18. The lateral force may be detected, for example, by a different distance between the coils 118, 170, 172 and the coil(s) 184, which may be calculated from the signals provided by the coils 118, 170, 172.

[0069] During use, the console 24 may process these signals and use them to adjust the amount of ablation energy delivered to the electrodes. For example, when the signal indicates that the beam coupling member 190 is in a relaxed state (i.e., no compression), this may be perceived as an indication that the tip 18 of the catheter 14 is not in contact with tissue and therefore no ablation energy should be delivered to the electrodes. Informational indicators (e.g., units of force, such as grams-force) may further be provided to the operator 16 on the display 29 to enable the operator 16 to manually adjust the ablation settings.

[0070] The top distal surface 192 and bottom proximal surface 194 of the beam combining member 190 may be parallel to one another and oriented transversely relative to the longitudinal axis of the beam combining member 190 (e.g., at an angle greater than about 60 degrees and less than or equal to about 90 degrees, e.g., about 80 degrees). Accordingly, in some embodiments, the receiver and transmitter affixed thereto are similarly oriented. The inventors have determined that a transverse, but not perpendicular, orientation of the receiver and transceiver increases receiver sensitivity because the distance between the transmitter and receiver is minimized compared to when the receiver and transceiver are disposed perpendicular to the longitudinal axis of the beam combining member 190 and the longitudinal axis of the catheter.

[0071] Reference is now made to Figures 6-8. Figure 6 is a first cross-sectional view of the distal portion of the catheter 14 of Figure 1. Figure 7 is a second cross-sectional view of the distal portion of the catheter 14 of Figure 1. Figure 8 is a cross-sectional view taken through line AA of Figure 6. Figure 6 shows the flexible circuit 110 assembled to the beam coupling member 190 and coupler or coupling sleeve 200. Although not shown, the first portion 114 of the flexible circuit 110 is adhered to the proximal face 194 (Figure 5) of the beam coupling member 190, and the flexible circuit 180 is adhered to the distal face 192 (Figure 5) of the beam coupling member 190. In Figure 7, the tip 18, including the ablation electrode(s) 32 and various irrigation apertures 214, is attached to the beam coupling member 190. Also shown in Figures 6 and 7 is a cable bundle 198. Cable bundle 198 includes a set of wires, not shown, that are connected to solder joints 168 on fourth portion 142 of flexible circuit 110 and, therefore, to various coils or traces on flexible circuit 110 and to coils or traces 184 on flexible circuit 180. As can be seen in FIGS. 6-8 , flexible circuit 110 is no longer flat. Rather, flexible circuit 110 has been deformed to have a shape with a cross-section that is generally circular. Segment 124 of second portion 116 is the most easily visible segment of flexible circuit 110 in FIGS. 6 and 7 . Various sides of segments 122, 132, and 134, as well as connectors 126, 136, 146, 150, and 152, are also visible in these views. As can be seen, these connectors have been deformed into a bent or curved configuration for attachment to coupler 200. Specifically, segment 122 is adhered to substantially planar surface 202 of coupler 200, and segment 132 is adhered to substantially planar surface 204 of coupler 200 (FIG. 8). So assembled, these portions of flexible circuit 110 can be viewed as having a triangular cross-section. Furthermore, connector 146 is adhered to circular (or arcuate) surface 206 of coupler 200, and connector 148 is adhered to circular (or arcuate) surface 208 of coupler 200.When so assembled, these portions of flexible circuit 110 may be seen as having a circular (or arcuate) cross-section. Fourth portion 142 may be further adhered to substantially planar surface 210 of coupler 200.

[0072] The diameter or width of the circular portion of the cross section of the flexible circuit 110 assembled to the coupler 200 is equal to or approximately equal to the diameter or maximum width of the first portion 114, and is also equal to or approximately equal to the maximum width (or base) of the triangular portion of the cross section of the flexible circuit 110 assembled to the sleeve 100. Thus, when assembled, the flexible circuit 110 can be easily inserted into an outer tube or sleeve 216 (FIG. 1), which provides the outer surface of the catheter 14 and defines an inner diameter into which the components of the catheter 14 (e.g., the flexible circuit 110, the beam coupling member 190, the coupler 200) fit. To help prevent soft spots under the sleeve 216 resulting from gaps between the substantially flat outer surfaces of the segments 124 and 134 and the portion 142, on the one hand, and the curvature of the sleeve 216, on the other hand, these gaps may be filled by including additional materials, such as adhesive 218 and polyimide layer 220, on the segments 124 and 134 (of the second portion 116 ( FIG. 2 ) and the third portion 130 ( FIG. 2 ), respectively) and portion 142. The polyimide layer 220 may be fabricated separately from and adhered to the flexible circuit 110, or may be an integral part of the flexible circuit 110, formed during the same lithography process as the rest of the flexible circuit 110. The polyimide layer 220 may interpolate the curve of the sleeve 216 with a series of substantially planar steps or layers.

[0073] The flexible circuit 110 may be incorporated into the catheter 14 as follows. First, the flexible circuit 110 may be provided. The segment 124 of the second portion 116 may be folded onto, overlapping, and contacting the segment 122 of the second portion 116 by deforming the connector 126 and, if included, the connector 150. The segment 134 of the third portion 130 may be folded onto, overlapping, and contacting the segment 132 of the third portion 130 by deforming the connector 136 and, if included, the connector 152. The first portion 114 of the flexible circuit 110 may be oriented to be parallel to the bottom surface 194 of the beam connecting member 190 and oriented transversely (e.g., less than 30 degrees from a perpendicular plane) relative to the longitudinal axis of the beam connecting member 190. The first portion 114 may then be adhered to the bottom surface 194 of the beam connecting member 190. A coupler 200 having a substantially planar surface portion may be provided and oriented so that its longitudinal axis is aligned with the longitudinal axis of the beam connecting member 190. The second portion 116 and the third portion 130 may be oriented so that they are parallel to the respective substantially planar surface portions of the coupler 200. The second portion 116 and the third portion 130 may then be bonded to the respective substantially planar surface portions of the coupler 200. The coupler 200, bonded to the flexible circuit 110, may then be bonded to or inserted into the outer sleeve 216. Finally, the tip 18 may be affixed to the beam connecting member 190. The flexible circuit 180 may be bonded to the top surface 192 of the beam connecting member 190 at almost all steps of the process, as long as the tip 18 is not attached to the beam connecting member 190.

[0074] Reference is now made to Fig. 9, which is a schematic illustration of a balloon catheter 300 constructed and operative in accordance with one embodiment of the present invention. Reference is also made to Figs. 10A-10D, which are semi-transparent illustrations of the balloon catheter 300 of Fig. 9. It should be understood that in all subsequent figures herein, the beam member 190 of Fig. 5 may be utilized with certain modifications shown and described in Figs. 10F and 10G.

[0075] The balloon catheter 300 is configured to be inserted into a body portion of a living subject (such as a heart chamber or any other suitable body portion). The balloon catheter 300 includes an insertion tube 302 having a distal tip 304. The insertion tube 302 can have any suitable outer diameter according to the body portion into which the balloon catheter 300 is to be inserted. In some embodiments, the outer diameter of the insertion tube 302 is approximately 3 mm.

[0076] The balloon catheter 300 includes an inflatable balloon 306 including a proximal portion 308 connected to the distal tip 304 of the insertion tube 302 via a force sensor 312 and a plurality of electrodes 310 disposed thereon. The inflatable balloon 306 also includes various irrigation openings 311 (only one is labeled for simplicity). The inflatable balloon 306 can have any suitable diameter when fully inflated. In some embodiments, the inflatable balloon 306 has an outer diameter of less than 15 mm. The electrodes 310 are configured to contact tissue at respective locations in the body part. Each electrode 310 is a flexible electrode formed, for example, from a polyamide substrate with a gold coating thereon, or any other suitable combination of materials. Each electrode 310 is connected to the proximal end of the insertion tube 302 via a wire (not shown), which can also function as a temperature sensor to provide a signal indicative of the temperature of the electrode 310 for use during ablation.

[0077] The balloon catheter 300 includes a force sensor 312 disposed proximate the distal tip 304 of the insertion tube 302 and configured to output at least one force signal indicative of the magnitude and direction of the force applied by the inflatable balloon 306 as it inflates on tissue. The force sensor 312 is disposed between the distal tip 304 of the insertion tube 302 and the proximal portion 308 of the inflatable balloon 306.

[0078] The force sensor 312 is connected to the insertion tube 302 and the inflatable balloon 306 using a lower coupler 314 and an upper coupler 316, respectively. The lower coupler 314 and the upper coupler 316 may use any suitable coupling mechanism, such as, but not limited to, a threaded fit, a bayonet fit, or a pressure fit coupling.

[0079] The balloon catheter 300 includes at least one position sensor 318 configured to output at least one position signal indicative of the position of the inflatable balloon 306 and / or the distal tip 304. The position sensor 318 is described in more detail with reference to FIG. 12 and may comprise one or more magnetic coils. In some embodiments, the electrode 310 may be used as a position sensor in conjunction with the body surface electrode 30 (FIG. 1) using the current-based or impedance-based position tracking methods described above in more detail with reference to FIG. 1, or a combined magnetic and current / impedance-based position tracking method.

[0080] Due to the small size of the balloon, after deflation, the balloon collapses to a diameter of approximately 3 mm without the need for a central extension tube used in many balloon designs to straighten the deflated balloon for reinsertion into the sheath. Inflatable balloons are easily maneuvered around the heart cavities to rapidly perform ablation of large areas of cardiac tissue, thus reducing ablation times compared to regional catheters.

[0081] During ablation, RF power can be applied equally to all electrodes 310, or a multi-channel RF generator can be used to selectively apply power to each of the electrodes 310. The power level can be controlled according to temperature feedback or by manually controlling the power. The electrodes 310 can also be used to sense electrical activity in a body part, for example, an IEGM.

[0082] 10B and 10D show a coupler / flow diverter 330 connected to the distal portion of the force sensor 312. The coupler / flow diverter 330 is an elongated element that extends distally and is coaxial with the insertion tube 302 (FIGS. 10A and 10B). An irrigation line 334 is disposed on the insertion tube 302, extends through a central portion of the coupler / flow diverter 330, and is coupled to a proximal section of the coupler / flow diverter 330. The coupler / flow diverter 330 includes an irrigation port 332 therein, through which irrigation fluid enters the inflatable balloon 306 from an opening at the end of the irrigation line 334. A wire 336 (which also functions as a temperature sensor) connecting to the electrode 310 is fed through the insertion tube 302 and exits from a proximal elongated opening 338 in the coupler / flow diverter 330. These openings are then sealed to prevent irrigation fluid from entering the insertion tube 302 .

[0083] Inflatable balloon 306 is coupled to the proximal and distal sections of coupler / flow diverter 330. In the distal section of inflatable balloon 306, a polymer ring 340 secures inflatable balloon 306 and / or the distal portion of electrode 310 to coupler / flow diverter 330 to prevent electrode 310 from delaminating. Partial balloon 342 covers inflatable balloon 306 and the proximal section of inflatable balloon 306 and protects wire 336 and the non-ablative surface of electrode 310. Partial balloon 342 may be configured to exhibit a portion of a hemisphere to ensure that certain components, such as wiring and circuit traces, are protected between main balloon 306 and partial balloon 342.

[0084] 10C and 10D show a protector sleeve 344 covering the force sensor 312, the x-axis coil 322, the y-axis coil 324, and the solder pad area 320. The protector sleeve 344 is typically formed from any suitable plastic. A deflectable element 346 (in the form of a pull cable) may be disposed in the distal portion of the insertion tube 302 to facilitate deflection of the balloon catheter 300, as shown in FIG. 10D.

[0085] 10E shows a cross-sectional view of an exemplary end effector of catheter 24. Starting at distal tip 304 of tubular member 302, a first (or lower) coupler 314 is provided that extends along longitudinal axis LL of tubular member 302 through a central opening defined by position sensor coils 322, 324 and beam coupling member 190, as well as contact force coil circuits 110 and 180. First coupler 314 terminates only at 314a and 314b (leaving a small gap between coupler 314 and coil 114) before physical contact with coil 114. Coupler 314 is coupled to beam coupling member 190, shown in FIG. 10F herein, with other components hidden for clarity. Irrigation fluid (arrows) is delivered along irrigation tubing 334 that extends through coupler 314, beam junction 190, and coupler 316 such that the irrigation fluid strikes flat surface 332a, directing the fluid flow from port 332 at approximately 90 degrees or greater.

[0086] Referring to FIG. 10F, which is an exploded view of the components discussed in FIG. 10E, coupler 314 is provided with a plurality of notches 314a, 314b, 314c on the periphery of cylindrical member 314 for corresponding engagement with protrusions 194a, 194b, 194c of beam coupling member 190.

[0087] The second coupler 316 is provided with notches 316a, 316b, 316c that mate with the protrusions 192a, 192b, 192c of the beam combining member 190. Flat surfaces 316d (three shown for coupler 316) are formed such that each flat surface 316d is angled with respect to the axis LL such that each flat surface is complementary to the angulation 190 defined by the helical path (i.e., helix angle) of the angled portions 193a, 193b, 193c. Three flat surfaces (not shown due to perspective view) 314d are also provided on coupler 314 in a configuration similar to flat surfaces 316d of coupler 316, in that the three flat surfaces 314d are also angled with respect to axis LL so that each flat surface 314d of coupler 314 is generally parallel to the angled path 190 defined by helical ramps 193a, 193b, 193c, like flat surface 316d.

[0088] Position sensor coils 322 and 324 are mounted to first coupler 314 in a generally isometric configuration about axis LL. Note that while two coils (for the X and Y axes) are used in the exemplary embodiment to determine the position of these coils (mounted on couplers, whereby the balloon's position is known as the distance between the balloon and the position sensor), in certain circumstances, only one position sensing coil may be utilized if the other two axes are known through other visualization techniques. Similarly, three position sensing coils may also be used depending on the packaging constraints of the catheter.

[0089] 10G shows the beam connecting member 190 (other components are hidden to better show structural details). The beam connecting member 190 defines a generally cylindrical form factor about an axis LL so that the beam connecting member 190 can be mounted inside the catheter outer tube 344. Three arms 192, each having a protrusion 192a, 192b, 192c, extend along the axis LL in FIG. 10F to a first (or distal) end, whereby each protrusion (192a, 192b, or 192c) extends further circumferentially relative to the longitudinal axis LL. At the other end, the three arms 194, each having a protrusion 194a, 194b, 194c, extend to a second (or proximal) end along axis LL in FIG. 10F, such that each protrusion (194a, 194b, or 194c) extends further circumferentially relative to longitudinal axis LL. Note that when beam connecting member 190 is viewed by an observer positioned proximally on axis LL, protrusions 192a, 192b, and 192c extend away from each arm 192 in a counterclockwise circumferential direction. Contrast this with protrusions 194a, 194b, and 194c (at the other end), which extend away from each arm 194 in a clockwise circumferential direction. This opposite orientation feature of the protrusions ensures that when the proximal protrusions (194a, 194b, 194c) of the beam connecting member 190 engage with the notches (314a, 314b, 314c) of the first coupler 314 and the distal protrusions (192a, 192b, 192c) engage with the notches (316a, 316b, 316c) of the second coupler 316, the couplers 314 and 316 remain connected in the catheter (via their respective notches 314a and 316a).

[0090] Each protrusion 192a, 192b, 192c is configured to be split into two members so that elements of a biasing or spring member can be formed. For example, protrusion 192a is split into spiral ramps 191a and 193a that extend circumferentially relative to and along axis LL. Spirals 191a and 193a define a spiral-like path around and along axis LL and reunite at protrusion 194b. Similarly, protrusion 192b at one end (e.g., the distal end) is split into two spiral ramps 191b and 193b separated by a through gap between them, whereby the two ramps 191b and 193b reunite at protrusion 194c at the other end (e.g., the proximal end). Finally, protrusion 192c spirals around axis LL and divides into ramps 191c and 193c (with a through gap between them) that reunite at protrusion 194a.

[0091] By creating these helical ramps (with gaps between each ramp), Applicant is able to convert what is essentially a beam-like structure into a hybrid beam-spring coupling with three helical spring windings. Beyond achieving the function of a coil spring, this design allows for (a) retention of flex circuit 180 between protrusions 192a, 192b, and 192c via notches 195, (b) retention of flex circuit 110 between protrusions 194a, 194b, and 194c via circumferential notches 195, (c) retention of couplers 314 and 316 from separation, and (d) transfer of force from coupler 316 to protrusions 192a, 192b, and 192c and from coupler 314 to protrusions 194a, 194b, and 194c for measurement of displacement between each of the pie-shaped pairs of flex circuits 180 and 110. These features have not previously been available in the art other than in Applicant's designs described herein.

[0092] This configuration of couplers 314 and 316 relative to beam connecting member 190 transfers force applied from balloon 18 to coupler 316 to beam connecting member 190 such that the displacement of individual portions of beam connecting member 190 can be determined (assuming the spring constant k of beam connecting member 190 is known prior to installation) by measuring the displacement at distance "d" between each pair of trilobe force sensor segments on respective flex circuits 180 and 110. Alternatively, after final assembly, balloon catheter 300 can be tested to determine the constant k, taking into account the effects of protector sleeve 344, irrigation line 334, wires 336, and any other components functionally parallel to beam connecting member 190. The results of the test can be used to calibrate the force sensor to eliminate inaccuracies caused by variations in component assembly or manufacturing.

[0093] 10F, each of the trefoil force sensor segments 160, 162, 164 for flex circuit 110 is attached to beam connecting member 190 such that each segment 160, 162, 164 has a corresponding segment with flex circuit 180. For example, segment 162 of flex circuit 110 is attached parallel to segment 182 of flex circuit 180 at a particular distance "d" (distance "d" can vary as force is applied to couplers 316 or 314). The remainder of the force sensor coil segments 162 and 164 for flex circuit 110 are attached in a similar manner to the respective trefoil sensor segments of flex circuit 180. The displacement for each pair of trefoil force sensor segments will allow console 24 to determine the angle and direction of force being applied to one of the pie-shaped force sensor coil segment pairs. For example, when the distance "d" between force sensor coil segments 162 and 182 (opposite-facing arrows in FIG. 10F) is changed without changing the distance over the other two pairs of force sensor coil segments, the system's processor can determine that a force is being applied along one of the directions specified by the dual-facing arrow (FIG. 10F).

[0094] Reference is now made to Figures 11 and 12, which are semi-transparent views of the sensor of the balloon catheter 300 of Figure 9. The force sensor 312 is comprised of a beam connecting member 190 with a first portion 114 of a flexible circuit 110 (Figure 3) disposed on the bottom surface of the beam connecting member 190 and a flexible circuit 180 disposed on the top surface of the beam connecting member 190. In some embodiments, the first portion 114 is disposed on the top surface and the flexible circuit 180 is disposed on the bottom surface. The various components of the beam connecting member 190 and the flexible circuits 110, 180 are described in detail with reference to Figures 2-8.

[0095] Figure 11 shows solder pad area 320 including a plurality of solder pads (e.g., about 11), which may include solder joints 168 of portion 142 (Figure 2) for connecting the coil of flexible circuit 110 (Figure 3) and, optionally, the coil(s) of flexible circuit 180 to console 24 (Figure 1). Figure 12 shows x-axis coil 322 and y-axis coil 324 forming part of position sensor 318. X-axis coil 322 and y-axis coil 324 may be formed from segments 122, 124, 132, and 134 described above in more detail with reference to Figures 2 and 3.

[0096] Reference is now made to Figure 13, which is a flow diagram 400 including steps in a method of operation of the system 10 of Figure 1 using the balloon catheter 300 of Figure 9. The steps described below do not have 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 with one another.

[0097] The processor 22 (FIG. 1) is configured to receive (block 402) the force signal(s) from the force sensor 312 (FIGS. 9-12). The processor 22 (FIG. 1) is configured to calculate (block 404) the magnitude and direction of the force measured by the force sensor 312 in response to the force signal(s).

[0098] The force sensor 312 may be calibrated using any suitable method. According to some embodiments, the distal tip 304 is held in a clamp or other device while the inflatable balloon 306 is deflected using a robot. The robot measures the lateral and angular displacement of the inflatable balloon 306 relative to the distal tip 304 and the corresponding force applied to the inflatable balloon 306 by the robot using strain gauges, as well as the corresponding force signal(s) provided by the force sensor 312. The robot may also perform the above measurements while applying forces from different directions about the axis of the inflatable balloon 306. The calibration measurements may then be stored, such as in a table, for future lookup. Thus, in use of the system 10, the magnitude and direction of the force applied by the inflatable balloon 306 may be calculated from the force signal(s) output by the force sensor 312 by looking up the corresponding value in the table and performing an appropriate interpolation or extrapolation of the values ​​found in the table. The force signal(s) also indicate the lateral and angular displacement of the inflatable balloon 306 relative to the distal tip 304 and can therefore be used to determine the lateral and angular displacement of the inflatable balloon 306 relative to the distal tip 304, and therefore the position (location and orientation) of the inflatable balloon 306 (described in more detail below).

[0099] The processor 22 (FIG. 1) is configured to receive (block 406) position signal(s) from the position sensor 318 (FIGS. 9, 10, 12) and / or the electrodes 310 (FIGS. 9 and 10). The processor 22 (FIG. 1) is configured to calculate (block 407) the position of the distal tip 304 in response to the position signal(s). The processor 22 is configured to calculate (block 408) the position (location and orientation) of the inflatable balloon in response to the calculated position and force signal(s) of the distal tip 304 (which result in the lateral and angular displacement of the inflatable balloon 306 relative to the distal tip 304).

[0100] The processor 22 (FIG. 1) is configured to receive (block 410) contact signals from the electrodes 310 (FIGS. 9 and 10). In response to the contact signals, the processor 22 (FIG. 1) is configured to evaluate (block 412) the respective quality of contact of each of the electrodes 310 with tissue.

[0101] Reference is now made to Figure 14, which is a schematic diagram rendering a representation 502 of the balloon catheter 300 of Figure 9 and a representation 504 of the force vectors. Reference is also made to Figure 13.

[0102] The processor 22 (FIG. 1) is configured to render (block 414) on the display 29 a representation 504 of the force vector in response to the calculated magnitude and direction, and a representation 502 of the inflatable balloon 306 (FIG. 9) in response to the calculated position of the inflatable balloon 306 (based on the calculated position of the distal tip 304 and the force signal(s) as described above in conjunction with the step of block 408 of FIG. 13), while modifying the visual characteristics of one or more of the electrodes 310 (FIG. 9) in response to the respective qualities of contact of the electrodes 310 with the tissue at the respective locations. Electrodes 310 having a contact quality above a given quality of contact are highlighted relative to the other electrodes 310. The electrode representation in FIG. 14 is labeled with reference numeral 510. The highlighted electrodes may be displayed in a different color and / or using a higher brightness and / or using a border or any suitable method for identifying electrodes 310 having a contact quality above a given quality of contact relative to the other electrodes 310. The electrodes 310 may be labeled using electrode numbers 508 to allow the operator 16 to easily identify which electrodes are in contact with tissue. In FIG. 14 , highlighted electrodes include electrode numbers 508, while unhighlighted electrodes do not. In some embodiments, both highlighted and unhighlighted electrodes may be numbered. The representation 502 of the balloon catheter 300 and the representation 504 of the force vectors may be displayed along with an image 506 of the body part into which the balloon catheter 300 is inserted. The image 506 of the body part may be obtained from a CT or MRI scan, or any suitable scan that has been pre-registered with the system 10 ( FIG. 1 ). Steps 402-414 may be performed in any suitable order and may be repeated intermittently or periodically to update the position of the balloon catheter 300 relative to the body part and / or the size and magnitude of the force vectors.

[0103] Various features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable subcombination.

[0104] The above-described embodiments are cited by way of example, and the present invention is not limited to what is particularly shown and described in the foregoing specification. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described in the foregoing specification, as well as variations and modifications thereof not disclosed in the prior art that would occur to one skilled in the art upon reading the foregoing description.

[0105] [Embodiment] (1) A system comprising a balloon catheter configured to be inserted into a body part of a living subject, the balloon catheter comprising: an insertion tube having a distal tip; a force sensor connected to the distal tip; an inflatable balloon including a proximal portion connected to the force sensor such that the force sensor is disposed between the distal tip of the insertion tube and the inflatable balloon; and a plurality of electrodes disposed around an outer surface of the balloon and configured to contact tissue at respective locations in the body portion when the balloon is inflated, 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 to the tissue when the balloon is inflated. (2) a display; and a processing circuit, wherein the processing circuit: calculating the magnitude and the direction of the force in response to the at least one force signal; 2. The system of claim 1, configured to render a representation of a force vector and a representation of the inflatable balloon on the display in response to the at least one force signal. (3) the balloon catheter further comprises at least one position sensor configured to output at least one position signal indicative of a position of the distal tip; the processing circuitry calculating the position of the distal tip in response to the at least one position signal; The system of embodiment 2, configured to render on the display the representation of the force vector in response to the calculated magnitude and direction, and the representation of the inflatable balloon in response to the calculated position and the at least one force signal. (4) The processing circuit receiving a contact signal from the electrode; assessing a respective quality of contact of each of the electrodes with the tissue in response to the contact signal; The system of embodiment 2, configured to render the representation of the inflatable balloon on the display while modifying the visual characteristics of the electrodes in response to the respective qualities of contact of the electrodes with the tissue at the respective locations. (5) The system of embodiment 1, wherein each of the electrodes is a flexible electrode formed from a polyamide substrate having a gold coating thereon.

[0106] (6) An electrophysiology catheter device, 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 combining member coupled to a first coupler member by at least one first protrusion on one of the beam combining member and the first coupler member, the one first protrusion being fitted into at least one first notch on the other one of the beam combining member and the first coupler member; a second coupler member coupled to the beam combining member by at least one second protrusion on one of the beam combining member and the second coupler member, the at least one second protrusion being fitted into at least one second notch on the other of the beam combining member and the second coupler member. (7) The device described in embodiment 6, further comprising a balloon connected to the second coupler member. (8) The apparatus of embodiment 6, wherein the beam connecting member defines a generally cylindrical surface extending 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 extending circumferentially about the longitudinal axis. (9) The device described in embodiment 8, wherein the at least one arm at the first end includes three arms extending toward the first coupler member, and the at least one arm at the second end includes three arms extending toward the second coupler member, each arm having a protrusion extending circumferentially around the longitudinal axis. (10) The device of embodiment 8, wherein the protrusion proximate the first end is configured to split into two sloped sections that extend helically along the longitudinal axis toward another protrusion proximate the second end.

[0107] (11) The device of embodiment 8, wherein the first coupler includes a notch configured to mate with the protrusion of the at least one arm at the first end, and the second coupler member includes a notch configured to mate with the protrusion of the at least one arm at the second end. (12) The device described in embodiment 6, further comprising a flex circuit having at least one position sensing coil attached to one of the first and second coupler members. (13) The device described in embodiment 12, wherein the at least one position sensing coil comprises two position sensing coils. (14) The device described in embodiment 13, further comprising at least one ablation electrode coupled to the second coupler member and at least one temperature sensor coupled to the second coupler member. (15) The device described in embodiment 7, further comprising at least one ablation electrode mounted on the balloon and at least one temperature sensor mounted on the balloon.

[0108] (16) The device of embodiment 15, wherein the at least one ablation electrode comprises eight ablation electrodes and the at least one temperature sensor comprises eight temperature sensors.

Claims

1. 1. An electrophysiology catheter device comprising: 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 combining member coupled to the first coupler member by at least one first protrusion on one of the beam combining member and the first coupler member, the one first protrusion being fitted into at least one first notch on the other one of the beam combining member and the first coupler member; a second coupler member coupled to the beam combining member by at least one second protrusion on one of the beam combining member and the second coupler member, the at least one second protrusion being fitted into at least one second notch on the other one of the beam combining member and the second coupler member; the beam coupling member defines a generally cylindrical surface extending from a first end to a second end, the first and second ends each having at least one arm extending along the longitudinal axis, the at least one arm defining a protrusion extending circumferentially about the longitudinal axis; a protrusion proximate the first end configured to divide into two sloped sections that extend helically along the longitudinal axis toward another protrusion proximate the second end, with a gap between the sloped sections.

2. The device of claim 1 further comprising a balloon connected to the second coupler member.

3. 2. The device of claim 1, wherein the at least one arm at the first end comprises three arms extending toward the first coupler member and the at least one arm at the second end comprises three arms extending toward the second coupler member, each arm having a protrusion extending circumferentially about the longitudinal axis.

4. 2. The device of claim 1, wherein the first coupler member includes a notch configured to mate with the protrusion of the at least one arm at the first end, and the second coupler member includes a notch configured to mate with the protrusion of the at least one arm at the second end.

5. The apparatus of claim 1 , further comprising a flex circuit having at least one position sensing coil attached to one of the first and second coupler members.

6. The apparatus of claim 5 , wherein the at least one position sensing coil comprises two position sensing coils.

7. The device of claim 6, further comprising at least one ablation electrode coupled to the second coupler member and at least one temperature sensor coupled to the second coupler member.

8. 3. The device of claim 2, further comprising at least one ablation electrode mounted on the balloon and at least one temperature sensor mounted on the balloon.

9. 9. The device of claim 8, wherein the at least one ablation electrode comprises eight ablation electrodes and the at least one temperature sensor comprises eight temperature sensors.

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