Transmission of acoustic signal and electromagnetic signal from catheter balloon

Abstract

To provide a catheter configured to apply electromagnetic energy to a treatment part.SOLUTION: A catheter includes at least a first transducer positioned inside at least a first balloon 14 and configured to operate by an operation frequency. The first transducer transmits an acoustic signal applying a plurality of lobes to a first acoustic field along a longitudinal axial line of the first transducer. Each of the lobes includes a space intensity maximum value in a space intensity distribution of the first acoustic field. The space intensity distribution is on a surface of the first balloon 14 and is parallel with a surface of the first transducer. The space intensity distribution of the first acoustic field includes one or more reduced space acoustic intensity positions in which a space intensity of the acoustic field of the first transducer is 50% or less of one value of the space intensity maximum values of the first transducer.SELECTED DRAWING: Figure 2D

Description

[Technical Field]

[0001] The present disclosure relates to catheters. In particular, the present disclosure includes a catheter configured to apply electromagnetic energy to a treatment site. The present disclosure also includes a catheter with a plurality of transducers circumscribing a longitudinal axis of the catheter, each of the transducers configured to transmit an acoustic signal. [Background technology]

[0002] According to the Centers for Disease Control and Prevention (CDC), approximately one in three adults suffers from high blood pressure, also known as hypertension. Left untreated, hypertension can lead to kidney disease, arrhythmias, and heart failure. In recent years, the treatment of hypertension has focused on minimally invasive interventional approaches that apply different forms of energy to the renal nerves surrounding the renal artery in order to inactivate these nerves. Unfortunately, not all patients respond favorably to this therapy. Renal neurectomy is often ineffective, potentially due to an insufficient probe-tissue interface. Therefore, not enough disruption is delivered to the nerve fibers passing along the renal artery. One reason for this is that delivery of disruption to the arterial wall lacks a feedback mechanism to assess the disruption of neural activity. As a result, not enough disruption is delivered, and neural activity is not destroyed. Therefore, clinicians need ways to improve the probe-tissue interface or better target the nerve, as well as techniques to monitor the integrity of the nerve fibers passing through the arterial wall to confirm the disruption of neural activity before terminating treatment. Current techniques for the destruction of neural activity do not provide the practitioner with a feedback mechanism to detect when the desired destruction of neural activity has been achieved. Neurodestruction procedures are applied empirically without knowledge that the desired effect has been achieved. There is a need for a system that can provide real-time feedback regarding whether the denervation procedure was successful.

[0003] There is also a need for catheters that can ablate smaller blood vessels or navigate more tortuous anatomy than currently available devices. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Provisional Patent Application No. 63 / 263,000 [Patent Document 2] U.S. Patent Publication No. 20220095979 [Patent Document 3] U.S. Patent Publication No. 2018 / 0221087 [Patent Document 4] U.S. Patent Publication No. 2017 / 0035310 [Patent Document 5] U.S. Provisional Patent Application No. 63 / 223,519 [Patent Document 6] U.S. Patent Publication No. 15 / 299694 Summary of the Invention [Means for solving the problem]

[0005] The invention is defined by the independent claims. Further embodiments of the invention are defined by the dependent claims.

[0006] The catheter includes at least a first transducer positioned within at least a first balloon, the first transducer configured to operate at an operating frequency, the first transducer transmitting acoustic signals that impart a first acoustic field with multiple lobes along a longitudinal axis of the first transducer, each lobe having a spatial intensity maximum in a spatial intensity distribution of the first acoustic field, the spatial intensity distribution being on a surface of the first balloon and parallel to the surface of the first transducer, the spatial intensity distribution of the first acoustic field having one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the first transducer is less than or equal to 50% of the value of one of the spatial intensity maxima of the first transducer, each reduced spatial acoustic intensity location being between spatial intensity maxima for lobes that are adjacent to each other along the longitudinal axis of the first transducer, and each reduced spatial acoustic intensity location being on the surface of the first balloon between adjacent spatial intensity maxima along the longitudinal axis of the first transducer. The catheter further comprises at least a first electrode configured to transmit an electromagnetic signal, the first electrode being positioned on the first balloon at one of the reduced spatial acoustic intensity positions of the first transducer.

[0007] A method for delivering energy to a treatment site includes advancing a distal end of a catheter to a treatment site within a patient, the catheter having at least a first transducer positioned within a first balloon. The method further includes operating the first transducer at an operating frequency such that the first transducer transmits an acoustic signal having an acoustic field along a longitudinal axis of the first transducer with a plurality of lobes, each of the lobes having a spatial intensity maximum in a spatial intensity distribution of the acoustic field, the spatial intensity distribution being at a surface of the balloon and parallel to a surface of the first transducer, the spatial intensity distribution of the first acoustic field including one or more low lobes where the spatial intensity of the acoustic field of the first transducer is less than or equal to 50% of the value of one of the spatial intensity maxima of the first transducer. The catheter has reduced spatial acoustic intensity locations, each of the reduced spatial acoustic intensity locations being between spatial intensity maxima for lobes that are adjacent to each other along the longitudinal axis of the first transducer, each of the reduced spatial acoustic intensity locations being on a surface of the first balloon between spatial intensity maxima that are adjacent to each other along the longitudinal axis of the first transducer, and the catheter further comprises at least a first electrode configured to transmit an electromagnetic signal, the first electrode being positioned on the first balloon at one of the reduced spatial acoustic intensity locations of the first transducer.

[0008] Another embodiment of the catheter includes a transducer located inside the balloon. The transducer is configured to operate at an operating frequency that transmits acoustic signals that impart a plurality of lobes to the acoustic field along the longitudinal axis of the transducer. Each of the lobes has a spatial intensity maximum in the spatial intensity distribution of the acoustic field. The spatial intensity distribution is at a surface of the balloon and parallel to the surface of the transducer. The spatial intensity distribution of the acoustic field has one or more spatial intensity minima. Each of the spatial intensity minima is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the transducer. One or more electrodes are configured to transmit electromagnetic signals, each of the one or more electrodes positioned on the balloon and on the transducer at a location that is above one of the one or more spatial intensity minima.

[0009] Another embodiment of the catheter includes a transducer located inside the balloon. The transducer is configured to transmit an acoustic signal. One or more electrodes are positioned on the balloon and configured to transmit an electromagnetic signal. Each of the one or more electrodes is positioned on the balloon such that at least a portion of the electrode is positioned beyond the acoustic signal of the transducer.

[0010] Another embodiment of the catheter has multiple transducers located inside the balloon, each of the transducers configured to transmit an acoustic signal. The catheter also includes one or more electrodes configured to transmit an electromagnetic signal, at least some of the one or more electrodes positioned on the balloon and between the transducers within the balloon.

[0011] Another embodiment of the catheter includes a plurality of transducers positioned within a balloon, each of the transducers configured to transmit an acoustic signal, and one or more electrodes configured to transmit an electromagnetic signal, at least a portion of the one or more electrodes positioned on and within the balloon between the transducers.

[0012] Another embodiment of the catheter includes a plurality of transducers positioned within a balloon, each of the transducers configured to transmit an acoustic signal. Each of the plurality of transducers is configured to transmit an acoustic signal that imparts at least one lobe to the acoustic field along a longitudinal axis of each transducer. The at least one lobe has a spatial intensity maximum in the spatial intensity distribution of the acoustic field. The spatial intensity distribution is on a surface of the balloon and parallel to the surface of each of the transducers. One or more electrodes are configured to transmit an electromagnetic signal. Each of the one or more electrodes is positioned on the balloon other than at a location of the spatial intensity maximum of the at least one lobe of each transducer.

[0013] Another embodiment of the catheter includes a plurality of transducers positioned within the balloon such that the transducers surround the longitudinal axis of the catheter. Each of the transducers is configured to transmit an acoustic signal. A pair of transducers are adjacent to one another along the longitudinal axis of the catheter, and each transducer in the pair has ends positioned such that the ends are adjacent to one another along the longitudinal axis of the catheter. One or both of the transducers in the pair have a thickness that tapers toward the adjacent end of the transducer.

[0014] Another embodiment of the catheter includes a backing member. The catheter also includes a plurality of transducers, each of which surrounds the backing member. Each of the transducers is configured to transmit an acoustic signal. The backing member includes reinforced flexible regions located between the transducers. In some examples, the reinforced flexible regions spiral around the backing member. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a side view of the catheter system. [Figure 2A] Figure 2 illustrates a catheter suitable for use with the catheter system of Figure 1. The catheter is a cross-section of the distal end of the catheter taken along the longitudinal axis of the catheter. The catheter includes multiple circumferential electrodes connected to a single electrode option configured to operate as a dispersive electrode. [Figure 2B] 2B is a cross-section of the catheter shown in FIG. 2A taken along the line labeled B in FIG. 2A. [Figure 2C] 2B is a cross-section of the catheter shown in FIG. 2A taken along the line labeled C in FIG. 2A. [Figure 2D] FIG. 2B is a side view of the distal end of the catheter shown in FIG. 2A. [Figure 2E] 2A-2D are illustrated in which the electrodes are modified to connect to multiple electrode options, each of which includes a single circumferential electrode. [Figure 2F]2E is the catheter of FIG. 2E modified so that each of the electrode options includes multiple individual electrodes. [Figure 2G] 2F illustrates the catheter of FIG. 2F modified so that the electrodes function as external electrodes positioned approximately coaxially with the transducer, proximal and distal to the transducer along the longitudinal axis of the transducer, and not overlapping with the transducer or its acoustic signal. [Figure 2H] 2F is an illustration of the catheter of FIG. 2F modified to include electrodes between the lobes of the acoustic field as shown in FIG. 2G. [Figure 2I] 2G illustrates the catheter of FIG. 2G modified so that the electrodes from the different electrode options are not longitudinally aligned on the balloon. [Figure 2J] 2I illustrates the electrodes of FIG. 2I connected to multiple electrode options, each electrode option comprising a single individual electrode. [Figure 2K] 2G illustrates the catheter of FIG. 2G modified so that the electrodes are positioned on the balloon, but the transducer assembly is not within the balloon. [Figure 2L] 2B illustrates the catheter of FIG. 2A modified so that the transducer assembly resides within the balloon, but the electrodes are not positioned on the balloon. [Figure 2M] 2E illustrates the catheter of FIG. 2E modified to include electrodes connected to multiple electrode options, one electrode option including a single circumferential electrode and one electrode option including multiple individual electrodes. [Figure 2N] 1 illustrates a portion of a catheter that includes an intermediate balloon between a proximal balloon and a distal balloon. [Figure 2O] 10 illustrates an alternative embodiment in which a portion of the catheter includes an intermediate balloon between the proximal and distal balloons. [Figure 3A] 1A-1C illustrate examples of catheter constructions that can allow for independent inflation and / or deflation of different balloons on the same catheter; FIG. 1B illustrates a portion of the distal end of a catheter shaft; and FIG. 1C is a perspective view of a portion of a catheter shaft. [Figure 3B]3A illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. 3B illustrates a portion of the distal end of a catheter shaft. 3C is a cross-section of the catheter shaft shown in FIG. 3A taken along the line labeled B in FIG. 3A. [Figure 3C] 3A illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. 3B illustrates a portion of the distal end of a catheter shaft. 3C is a cross-section of the catheter shaft shown in FIG. 3A taken along the line labeled C in FIG. 3A. [Figure 3D] 1 illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. [Figure 3E] 3D illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. FIG. 3D is a cross-section of the catheter shown in FIG. 3D along the longitudinal axis of the catheter and through one of the balloons. [Figure 3F] 3F illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. FIG. 3E is a cross-section of the catheter shown in FIG. 3E taken along the line labeled E in FIG. 3F. [Figure 3G] 3F illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. FIG. 3E is a cross-section of the catheter shown in FIG. 3E taken along the line labeled G in FIG. 3F. [Figure 4A] FIG. 1 is a top view of a flex circuit. [Figure 4B] FIG. 4B is a side view of a portion of a catheter including the flex circuit of FIG. 4A. [Figure 4C] 4C is a cross-section of the portion of the catheter shown in FIG. 4B taken along the line labeled B in FIG. 4C. [Figure 5A] 1 illustrates an example of a double-sided flex circuit suitable for use with a catheter. 2 is a top view of the inside of a double-sided flex circuit including conductive paths in a substrate. [Figure 5B]5A and 5B illustrate examples of double-sided flex circuits suitable for use with catheters. [Figure 5C] 5A and 5B illustrate examples of double-sided flex circuits suitable for use with catheters. [Figure 6A] 1 illustrates an example of a catheter including multiple transducer assemblies in a balloon.FIGS. 1A and 1B are perspective views of a portion of a catheter including a balloon and transducer assemblies connected in parallel.FIGS. [Figure 6B] 6B illustrates an example of a catheter including multiple transducer assemblies in a balloon. FIG. 6C is a cross-section of the catheter shown in FIG. 6A taken along the line labeled B. [Figure 6C] FIG. 1 is a perspective view of a portion of a catheter including serially connected transducer assemblies. [Figure 6D] FIG. 1 is a perspective view of a portion of a catheter including a transducer assembly and a balloon. [Figure 6E] 6E is a cross section of the catheter shown in FIG. 6D taken along the line labeled E. [Figure 6F] Cross sections of the transducer adjacent to each other, each having a thickness that tapers at the end of the transducer. [Figure 6G] Cross sections of the transducer adjacent to each other, each having a thickness that tapers at the end of the transducer. [Figure 6H] 1 is a cross section of a transducer having a thickness that tapers at the ends of the transducer. [Figure 6I] 1 is a cross section of a transducer having a thickness that tapers at the ends of the transducer. [Figure 6J] 1 is a cross section of a transducer having a thickness that tapers towards the end of the transducer. [Figure 6K] 6A to 6E are schematic cross-sections of possible catheter constructions. [Figure 7A]1 illustrates an example of an inner catheter; [Figure 7B] 1 illustrates an example of an inner catheter. 2 is a perspective view of another embodiment of an inner catheter. [Figure 7C] 7A illustrates an example of an inner catheter. FIG. 7B illustrates the inner catheter of FIG. 7A positioned in the guidewire lumen of the catheter disclosed in connection with FIG. 5C. [Figure 8] 1 is a cross-sectional view of a blood vessel, such as a renal artery, that receives the distal end of a catheter. [Figure 9] 1 is a cross section of a catheter having a transducer with a recess. [Figure 10A] 1 is a cross-section of the distal end of the catheter taken along the longitudinal axis of the catheter. [Figure 10B] 10B is a cross-section of the catheter shown in FIG. 10A taken along the line labeled B in FIG. 10A. DETAILED DESCRIPTION OF THE INVENTION

[0016] The catheter includes a transducer positioned inside the balloon. The transducer is configured to transmit an acoustic signal having acoustic energy in multiple lobes. The lobes represent the spatial acoustic energy or spatial intensity distribution of the acoustic field. As a result, the lobes of the acoustic field can deliver acoustic energy to a treatment site, such as the renal nerve, hepatic nerve, pulmonary artery nerve, or cardiac tissue. The catheter also includes one or more electrodes configured to transmit an electromagnetic signal. Each of the one or more electrodes is positioned on the balloon and between the lobes of the acoustic field. As a result, the electromagnetic signal can deliver electromagnetic energy to the treatment site. Because the electrodes are positioned from the acoustic field or between the lobes of the acoustic field, electromagnetic energy can be delivered to the treatment site between the locations where the lobes deliver acoustic energy to the treatment site. Because the electromagnetic energy is delivered to a location where acoustic energy is, for example, minimized, the uniformity of the energy delivered throughout the treatment site can be increased, maximizing the effectiveness of the treatment.

[0017] FIG. 1 is a side view of a catheter system. The catheter system includes a catheter 10 having a proximal end and a distal end. The catheter 10 includes a catheter shaft 12, a balloon 14, and a tip member 15. The balloon 14 can be positioned between the catheter shaft 12 and the tip member 15. The balloon 14 can be or include a compliant, semi-compliant, or non-compliant medical balloon 14. Suitable materials for the balloon 14 include, but are not limited to, nylon, polyimide film, thermoplastic elastomers such as those marked with the trademark PEBAX™, medical-grade thermoplastic polyurethane elastomers such as those sold under the trademark PELETHANE™, perethane, isoether, and other suitable polymers, or any combination thereof.

[0018] The catheter 10 can have a handle 16 at the proximal end of the catheter shaft 12. The handle 16 can include one or more electrical couplers 18 for connecting the catheter system to one or more external conductors 20, each in electrical communication with electronics 22. Suitable external conductors 20 include, but are not limited to, wires, cables, and flexible printed circuits (FPCs).

[0019] The catheter shaft 12 may include one or more electrical lumens (not shown). Each of the electrical lumens extends from one or more of the electrical couplers 18 along the longitudinal length of the catheter shaft 12 toward the distal end of the catheter shaft 12. The electrical lumens may hold one or more conductor carriers (not shown), each carrying one or more conductors. The conductors may be in electrical communication with the electronics 22 through the electrical couplers 18 and one or more of the external conductors 20. Suitable conductors include, but are not limited to, wire, insulated wire, cable, and flexible printed circuit (FPC). When the conductor carrier carries multiple conductors, a suitable conductor carrier may be an electrically insulating jacket. When the conductor carrier carries a single conductor, electrical insulation on the conductor may function as the conductor carrier.

[0020] The handle 16 may include one or more fluid ports 24 for connecting the catheter to conduits 26. Suitable conduits 26 include, but are not limited to, tubing and hoses. The conduits 26 may provide fluid communication between the fluid ports 24 and a fluid source 28. Suitable fluid sources 28 include, but are not limited to, a pump, a tank, a reservoir, and a container. The catheter shaft 12 may include one or more fluid lumens (not shown). Each of the fluid lumens may be in fluid communication with one of the fluid ports 24 and may extend along the longitudinal length of the catheter shaft 12 toward the distal end of the catheter shaft 12.

[0021] The handle 16 may include one or more guidewire ports 30 for receiving a guidewire 31. The catheter shaft 12 may include a guidewire lumen (not shown). The guidewire lumen may extend along the longitudinal length of the catheter shaft 12 toward the distal end of the catheter shaft 12. The guidewire lumen may be in fluid communication with the guidewire port 30 such that a guidewire 31 inserted into the guidewire port 30 is received in the guidewire lumen.

[0022] FIG. 2A is a cross-section of the distal end of the catheter taken along the longitudinal axis of the catheter. FIG. 2B is a cross-section of the catheter shown in FIG. 2A taken along the line labeled B in FIG. 2A. FIG. 2C is a cross-section of the catheter shown in FIG. 2A taken along the line labeled C in FIG. 2A. FIG. 2D is a side view of the distal end of the catheter shown in FIG. 2A. The balloon 14 can be positioned between the catheter shaft 12 and the tip member 15. The balloon 14 can be secured along the exterior of the catheter shaft 12 and / or the exterior of the tip member 15. Suitable mechanisms for securing the balloon 14 to the exterior of the catheter shaft 12 and / or the exterior of the tip member 15 include, but are not limited to, friction fit; adhesive mechanisms such as glue, adhesive, or epoxy; mechanical attachment mechanisms such as retainers, locking rings, clamps such as ring clamps or hose clamps; welding such as laser welding, heat welding, and combinations thereof.

[0023] The transducer assembly 32 is positioned within the balloon 14. The transducer assembly 32 can include a transducer 34. In one embodiment, the transducer is configured for focused ultrasound. The transducer can have a hollow cylindrical configuration having an inner and outer surface. An inner electrode 36 can contact the inner surface and extend along the length of the transducer 34. An outer electrode 38 can contact the outer surface and extend along the length of the transducer 34. Suitable materials for the transducer 34 include, but are not limited to, piezoelectric materials including piezoelectric ceramics, crystals, and polymers, and micro-electromechanical systems (MEMS) transducers such as piezoelectric micromachined ultrasonic transducers (PMUTs) and capacitive micromachined ultrasonic transducers (CMUTs). Examples of suitable piezoelectric materials include, but are not limited to, lead zirconate titanate (PZT), CMUTs, and PMUTs. In an embodiment suitable for use in renal denervation, the material of the transducer 34 includes or consists of lead zirconate titanate 8 (PZT8), also known as Navy III piezo material. The raw PZT transducer may be plated with layers of copper, nickel, and / or gold to create the inner electrode 36 and the outer electrode 38. In one embodiment, the transducer 34 is configured for focused ultrasound.

[0024] FIG. 2A shows a fluid lumen 40 in the catheter shaft 12. The lumen 40 includes a fluid port 41 that allows fluid exchange between the fluid lumen 40 and the interior of the balloon 14. As a result, the fluid lumen 40 is in fluid communication with the interior of the balloon 14. Thus, the fluid lumen 40 provides fluid communication between the interior of the balloon 14 and one of the conduits 26 disclosed in connection with FIG. 1. The catheter system can be configured to push fluid into the interior of the balloon 14 through the fluid lumen 40 and / or to withdraw fluid from the interior of the balloon 14 through the fluid lumen 40. As a result, the balloon 14 can be inflated or deflated using fluid. Alternatively, the catheter shaft 12 can include multiple fluid lumens 40, each opening into the interior of the balloon 14. The catheter system can be configured to push fluid into the interior of the balloon 14 through a first selection of the fluid lumens 40 and withdraw fluid from the interior of the balloon 14 through a second selection of the fluid lumens 40. The relative flow of fluid into and out of the balloon 14 can be varied to inflate the balloon 14, to deflate the balloon 14, or to maintain a steady inflation level of the balloon 14.

[0025] In some examples, the fluid is a liquid. Fluid inside the balloon 14 can contact the transducer assembly 32. For example, the fluid can contact the transducer 34, the internal electrode 36, and / or the external electrode 38. As a result, the fluid can cool both the body cavity and the transducer assembly 32. In some examples, the fluid source 28 disclosed in connection with FIG. 1 is configured to pre-cool the fluid and / or store the pre-cooled fluid. As a result, the fluid is cooled before entering the fluid lumen 40 and / or the interior of the balloon 14. Suitable temperatures for the pre-cooled fluid include, but are not limited to, temperatures from the freezing temperature of the fluid to room temperature, and / or temperatures above 0° C., 15° C., or 25° C., and / or temperatures below 20° C., 25° C., or 37° C. Examples of suitable fluids include, but are not limited to, sterile water, dextrose, saline, or other suitable cooling fluids.

[0026] The backing member 42 can be positioned within the acoustic transducer 34. In some examples, the backing member 42 is also positioned within the inner electrode 36. The inner electrode 36 and / or the transducer 34 can surround the backing member 42. As is apparent from FIG. 2A , the backing member 42 can extend beyond both ends of the transducer 34. The backing member 42 extends from the distal end of the catheter shaft 12 to the tip member 15. One end of the backing member 42 is received in a recess 44 in the distal end of the catheter shaft 12, and the other end of the backing member 42 is received in a recess 44 in the tip member 15.

[0027] A backing member lumen 46 extends longitudinally through the backing member 42. An electrical insulator 48 can be positioned within the backing member lumen 46. A second guidewire lumen 50 can extend longitudinally through the backing member 42 and be defined by the electrical insulator 48. The second guidewire lumen 50 is aligned with a guidewire lumen 51 extending longitudinally through the catheter shaft 12. The guidewire lumen 51 and the second guidewire lumen 50 are sized to receive a guidewire (not shown). The electrical insulator 48 is positioned to electrically insulate the backing member 42 from a guidewire received in the second guidewire lumen 50. Suitable materials for the electrical insulator 48 include, but are not limited to, polyimide, other polymeric or elastomeric materials, and other natural or synthetic materials. The backing member 42 can be constructed to be electrically conductive. Suitable materials for the backing member 42 include, but are not limited to, tungsten, steel, and aluminum.

[0028] The second guidewire lumen 50 is aligned with the lumen of the tip member 15. The lumen of the tip member 15 is sized to receive a guidewire (not shown). As a result, the catheter can move along a guidewire positioned in the guidewire lumen, the second guidewire lumen 50, and the tip member 15 lumen.

[0029] One or more spacing elements 54 can be positioned between the backing member 42 and the transducer assembly 32. The spacing elements 54 can be configured to maintain a space between the backing member 42 and the transducer assembly 32. The spacing elements 54 can include a plurality of spacers 56 extending away from a spacer body 58. An opening can extend through the spacer body 58. The opening can be sized to receive the backing member 42. Thus, the spacer body 58 can surround the backing member 42.

[0030] The spacer 56 can contact the interior of the transducer assembly 32 at one or more contact locations. For example, the spacer 56 can contact the internal electrode 36 at one or more contact locations. The contact locations can be selected to allow fluid within the balloon 14 to flow to contact the interior of the transducer assembly 32 and the exterior of the backing member 42 while maintaining the position of the transducer 34 and backing member 42 relative to one another. In some examples, the contact locations are selected to keep the backing member 42 concentric within the transducer assembly 32 and are configured to allow fluid within the balloon 14 to flow through the backing member 42 to contact the interior of the transducer assembly 32 and / or to contact the interior of the transducer assembly 32 and then flow through the backing member 42.

[0031] FIG. 2B shows a first group of contact locations at the same location along the length of the longitudinal axis (labeled L). The contact locations in FIG. 2B are spaced apart from one another and disposed about the longitudinal axis of the backing member 42. The spacing between the contact locations is a result of openings between the spacers 56 that allow fluid to flow into the interior of the transducer assembly 32. FIG. 2B illustrates three spacers 56 that are approximately equally spaced apart from one another at an angle of 120°, the angle being measured from the longitudinal axis of the backing member 42. However, the quantity, shape, size, orientation, spacing and / or other details of the spacers 56 can vary as desired or required by a particular design or application.

[0032] One or more of the spacing elements 54 may be electrically conductive. Suitable materials for the conductive spacing elements 54 include, but are not limited to, steel, copper, and aluminum.

[0033] The illustrated catheter system includes a second spacing element 54 that is spaced apart from spacing element 54 of FIG. 2B along the longitudinal axis of backing member 42. Spacing elements 54 can be positioned at or near either end of transducer assembly 32.

[0034] The catheter shaft 12 includes an electrical lumen 64. The illustrated electrical lumen 64 includes a first conductor carrier 66 and a second conductor carrier 68. The first conductor carrier 66 extends through the wall of the catheter shaft 12 to the interior of the balloon 14. The first conductor carrier 66 includes a first conductor 70 that can be connected to the backing member 42. The conductive backing member 42 and the conductive spacing element 54 provide electrical communication between the inner electrode 36 and the first conductor 70. Additionally, the first conductor 70 is in electrical communication with the electronics 22 through the electrical coupler 18 and one of the outer conductors 20.

[0035] The first conductor carrier 66 includes a second conductor 72 that can be connected to the outer electrode 38 of the transducer assembly 32. In addition, the second conductor 72 is in electrical communication with the electronics 22 through the electrical coupler 18 and one of the outer conductors 20. As a result, the outer electrode 38 of the transducer assembly 32 is in electrical communication with the electronics 22 through the second conductor 72, the electrical coupler 18, and one of the outer conductors 20.

[0036] The electronics 22 are in electrical communication with the inner electrode 36 and the outer electrode 38, such that application of a voltage and an alternating current between the inner electrode 36 and the outer electrode 38 causes the transducer 34 to vibrate transversely to the longitudinal axis of the transducer 34 and radially emit an acoustic signal. In some examples, the transducer 34 is operated such that the acoustic signal has a desired frequency level.

[0037] The acoustic signal carries acoustic energy in lobes positioned adjacent to one another along the longitudinal axis of the transducer, as shown by the dashed lines in Figure 2D. The dashed lines illustrating the lobes represent positions around the transducer where the spatial intensity of the acoustic signal is at the same level. In some examples, when the lobes are depicted in three dimensions, each of the three lobes is roughly circularly symmetric and disk-shaped.

[0038] FIG. 2D also includes a graph showing the spatial intensity distribution of the acoustic field along the line labeled P. The line labeled P is parallel to the surface and / or longitudinal axis of the transducer assembly 32. The graph represents the spatial acoustic energy or spatial intensity (power / area) distribution of the acoustic field at a given distance from the transducer surface. The spatial intensity distribution shown in FIG. 2D is an example of a spatial intensity distribution for a multi-lobe distribution. The spatial intensity distribution includes spatial intensity peaks (labeled SIp), each associated with a different lobe. Each spatial intensity peak has a spatial intensity maximum. All or some of the spatial intensity maxima associated with the different lobes can have the same or different spatial intensity values. The spatial intensity distribution also includes spatial intensity valleys (labeled SIv), each having a spatial intensity minimum located between adjacent lobes. Thus, each spatial intensity minimum is associated with a different pair of lobes located adjacent to each other along the longitudinal axis of the transducer. Additionally, each spatial intensity minimum is associated with a pair of spatial intensity maxima for the pair of lobes associated with the spatial intensity minimum. All or some of the spatial intensity minima associated with different pairs of lobes may have the same or different spatial intensity values.

[0039] The line labeled P passes through the acoustic field at a distance from the longitudinal axis selected to illustrate the spatial intensity pattern parallel to the longitudinal axis and / or surface of the transducer. For example, the line labeled P can represent an example of the spatial intensity distribution of the acoustic field at the surface of the balloon when the balloon is not inflated or when the balloon is inflated. In addition, the spatial intensity shown can represent the distribution when no electrodes are present on the surface of the balloon. Thus, the graph illustrates the spatial intensity distribution along the longitudinal axis of the transducer 34.

[0040] Without being bound by theory, lobes may be the result of the transducer 34 vibrating in additional modes that create more complex vibrations of the transducer surface. Specifically, if the walls of a cylindrical transducer 34 are vibrating in guided wave (plate) modes that create standing waves along the length of the transducer 34 with different regions oscillating either in phase or out of phase with the thickness modes, the spatial acoustic intensity between these oscillations and the expected thickness modes can create regions of the transducer 34 that emit no sound or very little sound.

[0041] A second conductor carrier 68 in the electrical lumen 64 extends through a conductor port 67 in the wall of the catheter shaft 12. The second conductor carrier 68 includes a conductive component 84. The conductive component 84 is in electrical communication with the electronics through the electrical coupler 18 and one of the external conductors 20. Suitable conductors include, but are not limited to, insulated wire and flexible printed circuits (FPC).

[0042] Multiple electrical pathways are located within or on the balloon 14. For example, FIG. 2D illustrates multiple electrodes 76 positioned on the balloon 14. The electrodes 76 can surround the balloon 14. One or more of the electrodes 76 may comprise an expandable ring cylindrical electrode and / or a segmented cylindrical electrode and / or an expandable wire mesh that expands cylindrically with the balloon 14. One or more of the electrodes 76 may form a conductive periphery around the balloon 14, allowing the entire periphery of the expandable electrode(s) of the balloon 14 to make circumferential electrical contact with the inner wall of the blood vessel 360° around the vessel. The balloon 14 may be expanded into apposition with the vessel wall so that the electrodes 76 achieve and maintain intimate contact with the vessel wall despite movement caused by breathing, etc. The use of segmented electrodes 76, which can selectively stimulate the size and location of the electrodes controlled by adjusting stimulation parameters for each electrode contact, may enable more selective activation of target structures. In some embodiments, at least one electrode 76 comprises an expandable mesh of wires, each wire having a diameter of 8000-10000ths of an inch, and in other examples, the wire diameter is any size less than 5000-10000ths, 5000-15000ths, or 15000, 10000, 8000, or 5000ths of an inch to improve neural signal detection.

[0043] The electrical pathways include electrode interconnects 78 that provide electrical communication between the electrodes 76. In some embodiments, the electrodes 76 comprise an expandable mesh of wires, and all of the wires may be connected to the same electrode interconnect 78, which can improve the signal-to-noise ratio while sensing neural activity. The electrical pathways also include pad interconnects 80 that provide electrical communication between contact pads 82 on the balloon 14 and the electrodes 76 or between the contact pads 82 and the electrode interconnects 78. Conductive components 84 are connected to the contact pads 82 by an attachment mechanism. Suitable conductive components 84 include, but are not limited to, metal wires and flexible printed circuits (FPCs). Suitable attachment mechanisms include, but are not limited to, welding, soldering, and epoxy. The electrodes 76 are in electrical communication with the electronics 22 through one of the electrical pathways, the electrical coupler 18, and the external conductor 20. As a result, the electronics 22 can apply electrical energy to the electrodes 76. The electrical energy can be emitted from the electrode 76 as an electromagnetic signal. As an example, the electronics 22 can apply electrical energy to the electrode 76, and the applied electrical energy can be emitted from the electrode 76 as an electromagnetic signal having a radio frequency, such as an RF signal.

[0044] The electrodes 76 on the catheter of FIG. 2D are positioned between lobes of the acoustic field. Additionally or alternatively, all or some of the electrodes 76 are positioned or aligned with one of the spatial intensity minima associated with a pair of lobes. In some examples, the location on each electrode of the electrodes 76 coincides with one of the spatial intensity minima, as illustrated in the graph of FIG. 2D . An example of an electrode 76 positioned on one of the spatial intensity minima may be an electrode 76 positioned such that a line perpendicular to the longitudinal axis of the transducer 34 and / or the outer surface of the transducer 34 can extend through the electrode 76 and through one of the spatial intensity minima. In some examples, the line can pass through the center of gravity of the electrode 76 and the spatial intensity minimum. The electrode 76, and / or the width of the electrode, can be centered over the spatial intensity minimum or can be off-center relative to the spatial intensity minimum.

[0045] In some examples, all or some of the electrodes 76 are positioned on the surface of the balloon between pairs of reduced spatial acoustic intensity locations. Each pair of reduced spatial acoustic intensity locations is located on the surface of the balloon between a pair of spatial intensity maxima, each associated with the same spatial intensity minimum. Thus, each reduced spatial acoustic intensity location in a pair of reduced spatial acoustic intensity locations is associated with a spatial intensity minimum and a pair of spatial intensity maxima associated with that spatial intensity minimum. As an example, the spatial intensity distribution of FIG. 2D includes two reduced spatial acoustic intensity locations labeled RL. Each reduced spatial acoustic intensity location labeled RL is located on the surface of the balloon between a pair of spatial intensity maxima, labeled y, each associated with the same spatial intensity minimum, labeled x. Thus, the illustrated reduced spatial acoustic intensity locations are associated with a spatial intensity maximum labeled y and a spatial intensity minimum labeled x.

[0046] Each reduced spatial acoustic intensity location may be a location on the balloon's surface where the spatial intensity of the acoustic field is at a particular intensity threshold relative to the spatial intensity maximum associated with the reduced spatial acoustic intensity location. For example, the intensity threshold for a reduced spatial acoustic intensity location may be less than or equal to 50% or 25%, greater than 0%, or greater than 0.5% of the spatial intensity maximum associated with the reduced spatial acoustic intensity location. To illustrate this, FIG. 2D uses an intensity threshold equal to 50% of the spatial intensity maximum associated with the illustrated reduced spatial acoustic intensity location. For example, the lines labeled L1 and L2 in FIG. 2D indicate locations on the balloon's surface where the spatial intensity of the acoustic field is 50% of the value of the spatial intensity maximum relative to the spatial intensity maximum associated with the reduced spatial acoustic intensity location labeled RL. The electrode labeled El is located between the reduced spatial acoustic intensity locations labeled RL.

[0047] In some embodiments, the acoustic signal emitted from the transducer 34 is not reflected by the electrodes 76, resulting in more uniform and / or effective treatment of the tissue. In some embodiments, the acoustic signal emitted from the transducer 34 is not significantly reflected by the electrodes 76, resulting in more uniform and / or effective treatment of the tissue. In some embodiments, the system takes into account the reflection of the acoustic signal by the electrodes 76 when determining the power to be generated by the generator to provide more effective treatment of the tissue.

[0048] The electrodes 76 positioned between the reduced spatial acoustic intensity locations can be centered between the reduced spatial acoustic intensity locations or can be off-center relative to the reduced spatial acoustic intensity locations. The electrodes 76 positioned between the reduced spatial acoustic intensity locations can be positioned above a spatial intensity minimum associated with the spatial acoustic intensity locations, but need not be positioned above a spatial intensity minimum associated with the spatial acoustic intensity locations. In some examples, one or more of the n electrodes 76 positioned between the reduced spatial acoustic intensity locations are not positioned above a spatial intensity minimum associated with the spatial acoustic intensity locations. In some examples, none of the electrodes 76 are positioned outside of pairs of reduced spatial acoustic intensity locations. In some examples, none of the electrodes 76 are positioned completely or partially between adjacent pairs of reduced spatial acoustic intensity locations. Thus, the catheter can exclude electrodes positioned on the balloon where any portion of the electrode is located between pairs of reduced spatial acoustic intensity locations that are adjacent to each other along the longitudinal axis of the catheter.

[0049] The lobe characteristics can vary depending on the construction and / or operation of the transducer 34. For example, the number and / or size of the lobes can vary depending on changes in the drive frequency or operating frequency of the transducer. Additionally or alternatively, the lobe characteristics can vary depending on the physical properties of the transducer. For example, the number and / or size of the lobes can vary depending on the length of the transducer, the radius of the transducer, the distance between the transducer 34 and the backing member 42, and / or the geometry and size of the transducer components. However, catheter transducers are sold at operating frequencies certified by the manufacturer. The lobe characteristics for a particular transducer are determined by the operation of the transducer at the operating frequency.

[0050] 2A-2D illustrate two electrodes 76 positioned between two pairs of adjacent lobes, the transducer 34 can generate more than three lobes, as well as one or two lobes. As a result, the transducer 34 can generate one lobe, two lobes, or more than two lobes. When the transducer 34 generates an acoustic field having multiple lobes, the catheter can have one or more electrodes 76 each located at one or more positions selected from the group consisting of between adjacent lobes, spatial intensity minima, and between locations of reduced spatial acoustic intensity.

[0051] Because the characteristics of the lobes can vary depending on various variables, the electrodes 76 are positioned such that, when the transducer is operated at the operating frequency, each of the electrodes 76 is located at one or more positions selected from the group consisting of between adjacent lobes, spatial intensity minima, and between reduced spatial acoustic intensity positions. In some examples, the operating frequency is in the range of frequencies above 1 MHz and / or below 20 MHz, or any other frequency. Examples of suitable operating frequencies include, but are not limited to, 6 MHz, 7 MHz, 9 MHz, 10 MHz, and 12 MHz.

[0052] The distance between lobes and / or the distance between spatial intensity minima is labeled d in FIG. 2D . The distance between lobes and / or the distance between spatial intensity minima (labeled d) may represent the center-to-center distance between lobes, the center-to-center distance between adjacent electrodes 76, or the distance the electrodes 76 are separated along the longitudinal axis of the transducer 34. In some examples, the center-to-center distance between adjacent lobes, spatial intensity minima, and / or adjacent electrodes is greater than or equal to 1.0 mm, 1.5 mm, or 2.0 mm, and / or is less than or equal to 3.0 mm, 4.0 mm, or 6.0 mm. In one example, the center-to-center distance is greater than 1.0 mm and less than 6.0 mm.

[0053] The separation distance (denoted as s) between adjacent lobes on the outer surface of the balloon can represent the distance between locations where the spatial intensity of adjacent acoustic lobes is less than or equal to 50% of the spatial intensity maximum for the two lobes. In some examples, the separation distance between adjacent lobes is greater than 0 mm and less than 1.2 mm. In some examples, the distance (denoted as s) between adjacent lobes on the outer surface of the balloon is greater than or equal to 0.3 mm and less than 0.9 mm. Electrodes 76 at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minimums, and between reduced spatial acoustic intensity locations provide an acoustic field at a lower level of spatial acoustic intensity. Thus, in some examples, the electrodes 76 at these locations have a width greater than 0 mm and less than 1.2 mm. In some examples, the electrodes 76 at these locations have a width greater than or equal to 0.3 mm and less than 0.9 mm. Increasing the width of the electrodes can lower contact impedance, increasing electrode sensitivity and improving neural signal detection. In some embodiments, the electrodes 76 are sufficiently spaced apart from one another so that stimulation of one electrode 76 does not interfere with sensing and / or stimulation of a different electrode 76 .

[0054] The catheter may include one or more insulating layers positioned on the balloon 14. The one or more insulating layers may be positioned over the exposed electrical pathways, contact pads 82, attachment mechanisms, and conductive components 84 to reduce or eliminate radiation of energy from one or more of these components. For example, FIG. 2D illustrates an insulating layer 88 positioned over the electrode interconnects 78, pad interconnects 80, contact pads 82, attachment mechanisms, and conductive components 84. The insulating layer 88 shown in FIG. 2D is treated as transparent to illustrate the underlying features. Suitable materials for the insulating layer 88 include, but are not limited to, epoxy and rubber.

[0055] The electrodes 76 can be connected to one or more electrode 76 options. The electrode 76 options can include multiple electrodes 76 connected as a dispersive electrode 76, or can include a single electrode 76. The electrodes 76 in a dispersive electrode 76 can be connected to a single node such that electrical energy flowing through the node is distributed across the electrodes 76 in the dispersive electrode 76. For example, the electrodes 76 in FIG. 2D are each in electrical communication with a pad interconnect 80. The pad interconnect 80 can function as a common node, and electrical energy passing through the pad interconnect 80 is distributed across the electrodes 76. As a result, the electrodes 76 in FIG. 2D are arranged as a dispersive electrode 76 in a single electrode 76 option.

[0056] The electrode 76 can be arranged in multiple electrode 76 options. For example, the electrode 76 can be connected to multiple electrode 76 options, with each electrode 76 option including a single electrode 76. As an example, FIG. 2E illustrates an electrode 76 connected to multiple electrode 76 options, with each electrode 76 option including a single electrode 76. Acoustic energy lobes are not shown in FIG. 2E to better illustrate the location of one or more insulating layers 88. The insulating layer 88 shown in FIG. 2E is treated as transparent to illustrate the underlying features.

[0057] The second conductor carrier 68 includes a plurality of electrical conductors 74, each carrying a conductive component 84. A plurality of contact pads 82 are positioned on the balloon 14. The conductive components 84 are each connected to a different one of the contact pads 82 by an attachment mechanism. A plurality of pad interconnects 80 are positioned on the balloon 14. Each of the pad interconnects 80 provides electrical communication between one of the contact pads 82 and a different one of the electrodes 76. As a result, the electrodes 76 are in electrical communication with the electronics 22 through one of the pad interconnects 80, one of the contact pads 82, one of the electrical conductors 74, the electrical coupler 18, and one of the external conductors 20.

[0058] An insulating layer 88 is positioned on the balloon 14 over the pad interconnects 80, contact pads 82, attachment features, and conductive components 84. One of the electrodes 76 crosses over one of the pad interconnects 80. The insulating layer 88 is positioned between the electrode 76 and the underlying pad interconnect 80 to electrically isolate the electrodes 76 from each other. Because the electrodes 76 are electrically isolated from each other, the electronics 22 can operate the electrodes 76 independently. Thus, the electrodes 76 can apply different electrical energies to different electrodes 76.

[0059] The electrodes 76 disclosed in FIGS. 2D and 2K can be divided into individual electrodes 76, allowing for selective stimulation of electrode dimensions and positions controlled by adjusting stimulation parameters for each electrode contact, allowing for more selective activation of target structures. In some embodiments, the individual electrodes 76 are optimized for ablation. The individual electrodes 76 may be square, rectangular, circular, and / or star-shaped. The individual electrodes 76 may be positioned on the balloon 14 so that nerves in the body cavity can be ablated in a circumferential, four-quadrant pattern by simultaneously activating multiple electrodes 76 or selectively activating multiple electrodes 76 on the balloon 14 without moving the balloon 14. At least some of the individual electrodes 76 may comprise at least two bipolar electrode pairs offset longitudinally and circumferentially from each other to treat four quadrants of the body cavity, e.g., the renal arteries, while reducing the risk of cavity stenosis. The electrodes 76 may be used to detect wall apposition by detecting impedance. If one or more electrodes 76 are not in apposition with the wall of the body cavity, the balloon 14 may be further inflated and / or one or more electrodes 76 may be deselected.

[0060] In some embodiments that include a transducer 32 within the balloon 14, the electrodes 76 are also positioned such that the electrodes are each located at one or more positions selected from the group consisting of between adjacent lobes, spatial intensity minima, and between reduced spatial acoustic intensity positions.

[0061] For example, FIG. 2F shows the catheter of FIG. 2E modified to include a planar electrode 76. While FIG. 2F depicts rectangular electrodes, square electrodes, circular electrodes, irregular (serpentine) electrodes, such as an octagonal star with pointed corners, etc., may alternatively or additionally be used. For example, without limitation, an octagonal star may enable deeper neural stimulation with less power. Additionally, while four electrodes are depicted, the catheter may include more or fewer ablation and / or neural stimulation and / or neural sensing and / or impedance measurement electrodes. For example, in some embodiments, an array of 1 to 16 electrodes, e.g., 3, 8, or 16 electrodes. Acoustic field lobes are not shown in FIG. 2F to better illustrate the location of one or more insulating layers 88. The insulating layer 88 shown in FIG. 2F is treated as transparent to illustrate the underlying features.

[0062] In Figure 2F, the electrodes 76 are arranged in two electrode 76 options, each of which includes multiple electrodes 76 connected as a dispersive electrode 76. The electrical pathways include electrode interconnects 78 that provide electrical communication between the segmented electrodes 76 in the same electrode 76 option. Although not shown in Figure 2F, an insulating layer can optionally be positioned over all or a portion of the electrode interconnects 78 to prevent or reduce radiation of electrical energy from the electrode interconnects 78.

[0063] Segmented electrodes 76 in the same electrode option are positioned around the same location along the longitudinal axis (labeled L) of the transducer. Segmented electrodes 76 in different electrode options are spaced apart along the longitudinal axis of the transducer. As a result, each of the electrode 76 options includes multiple segmented electrodes 76, each positioned at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations.

[0064] As an alternative to, or in addition to, being positioned between adjacent lobes, the balloon 14 may include one or more electrodes 76 that are not positioned between adjacent lobes originating from the same transducer 34. For example, one or more of the electrodes 76 may be external electrodes, in that at least a portion of the electrode 76 is not positioned on the transducer 34 and is not in the path of the acoustic signal of the transducer 34. As an example, the external electrode 76 may be positioned in front of and / or behind the transducer 34 along the longitudinal axis of the transducer 34, beyond the acoustic signal of the transducer 34. For example, FIG. 2G illustrates the catheter of FIG. 2F modified to function as an external electrode, with the electrode 76 positioned such that the location of the transducer 34 is between the location of the electrode 76 along the longitudinal axis of the transducer 34. In FIG. 2G, the location of the transducer assembly 32 within the balloon 14 is illustrated with dashed lines. Additionally, to simplify the illustration, the location of one or more insulating layers is not shown.

[0065] The catheter of FIG. 2G includes two electrode 76 options, each including a plurality of segmented electrodes 76. While segmented electrodes are depicted in FIG. 2G, in certain embodiments, ring electrodes and / or mesh electrodes 76 may additionally or alternatively be used. Each of the electrodes 76 is an external electrode positioned in front of or behind the transducer 34, coaxial with the transducer 34. The one or more external electrodes 76 are positioned such that a line perpendicular to the longitudinal axis of the transducer 34 can extend through each of the external electrodes 76 without passing through the transducer 34. In this manner, the electrodes 76 do not interfere with the acoustic output of the transducer 76.

[0066] Electrodes 76 in FIG. 2G are not positioned between adjacent lobes. As a result, the width (labeled W in FIG. 2G) of electrodes 76 is not limited by the proximity of the lobes. Thus, one or more of the outer electrodes may be wider and / or have a larger transmitting surface area than electrodes 76 placed at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations.

[0067] While FIG. 2G illustrates the overall width of each electrode 76 positioned in front of or behind the transducer 34, the transducer 34 can overlap with the acoustic signal of the transducer 34 as long as one or more of the outer electrodes is not at a spatial intensity maximum of an adjacent lobe of the acoustic field, e.g., a spatial intensity minimum of an adjacent lobe of the acoustic field, or a reduced spatial acoustic intensity position.

[0068] The catheter may include one or more external electrodes (e.g., segmented, ring, mesh) and may also include one or more electrodes 76 placed at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and between locations of reduced spatial acoustic intensity. As an example, FIG. 2H illustrates the catheter of FIG. 2F modified to include the external electrodes from FIG. 2G. In FIG. 2G, the location of the transducer assembly 32 within the balloon 14 is illustrated with dashed lines. Additionally, for simplicity of illustration, the location of one or more insulating layers is not shown. The electrodes 76 are connected to four electrode 76 options, each of which includes multiple segmented electrodes 76. The segmented electrodes 76 in the same electrode 76 option are arranged around the same location along the longitudinal axis of the transducer 34, and the electrodes 76 in different electrode 76 options are arranged around different locations along the longitudinal axis of the transducer 34.

[0069] 2H illustrates an external electrode at the distal end of the balloon 14 connected to the same electrode 76 option, the external electrode at the distal end of the balloon 14 can be connected to two electrode 76 options. As a result, the external electrode at the distal end of the balloon 14 can operate as a bipolar electrode 76. Additionally or alternatively, the external electrode at the proximal end of the balloon 14 can be connected to two electrode 76 options. As a result, the external electrode at the proximal end of the balloon 14 can operate as a bipolar electrode 76.

[0070] 2F-2H illustrate electrodes 76 from different electrode 76 options longitudinally aligned on the balloon 14. However, the electrodes 76 from different electrode 76 options need not be longitudinally aligned on the balloon 14. As an example, FIG. 21 illustrates the catheter of FIG. 2G modified such that the electrodes 76 from different electrode 76 options are not longitudinally aligned on the balloon 14.

[0071] Although Figures 2E-2I illustrate electrodes 76 connected to multiple electrode 76 options, the electrodes 76 on the catheters of Figures 2E-2I can be connected to a single electrode 76 option. As an example, Figure 2D illustrates the electrode 76 of Figure 2E connected to a single electrode 76 option. Additionally, although the electrode 76 options illustrated in Figures 2F-2I each include multiple electrodes 76, the electrodes 76 can be connected such that each electrode 76 option includes up to one electrode 76. As an example, Figure 2J illustrates the electrode 76 of Figure 2I connected to multiple electrode 76 options, each electrode 76 option including a single electrode 76. In some examples, a catheter includes multiple electrode 76 options, with some of the electrode 76 options including a single electrode 76 and another portion of the electrode 76 options each including multiple electrodes 76.

[0072] 2A through 2J, the electrical connections combining the electrodes 76 in the electrode 76 options are provided by electrical pathways on the balloon 14. For example, electrode interconnects 78 provide electrical communication between the electrodes 76 in the same electrode 76 option. However, the electronics 22 can connect different electrode 76 options to a common node such that current through the common node is distributed to the electrodes 76 in both of the electrode 76 options. As a result, the electronics 22 can combine several of the above-disclosed electrode 76 options together to form another, larger electrode 76 option. Thus, an electrode 76 option may be the result of electrical pathways on the balloon 14 as well as electrical connections at other locations within the catheter system. When the electronics 22 connects different electrode 76 options to a common node, the connections may be permanent or temporary. For example, the electronics 22 may include a switch that the electronics 22 can operate to connect different electrode 76 options to the common node or to disconnect the electrode 76 options from the common node. As a result, the electronics 22 can adjust and / or regulate the electrodes 76 included in the electrode 76 option.

[0073] In some examples, the transducer assembly 32 is not present within the balloon 14. As an example, Figure 2K illustrates the catheter of Figure 2G modified so that the electrodes 76 are positioned on the balloon 14, but the transducer assembly 32 is not present within the balloon 14. In some examples, the electrodes 76 are not present on the balloon 14. As an example, Figure 2L illustrates a catheter having a transducer assembly 32 constructed as disclosed in connection with Figures 2A-2J modified to exclude the electrodes 76 on the surface of the balloon 14.

[0074] 2M illustrates the catheter of FIG. 2E modified so that, for electrodes connected to multiple electrode options, one electrode option includes a single circumferential electrode 76 and one electrode option includes multiple individual electrodes 76. In some embodiments, the circumferential electrode 76 can be optimized for neural sensing and / or neural stimulation, and the electrode option including multiple individual electrodes 76 can be optimized for tissue ablation and / or neural stimulation. For example, the circumferential electrode 76 can be a mesh electrode configured to sense and / or stimulate nerves 360° around a blood vessel, and the electrode option including multiple individual electrodes 76 can include at least two bipolar electrode pairs that are longitudinally and circumferentially offset from each other to ablate four quadrants of the body cavity while reducing the risk of narrowing the body cavity. In another example, the circumferential electrode 76 can be a ring electrode or a segmented electrode configured to sense and / or stimulate nerves 360° around the blood vessel, and electrode options including multiple individual electrodes 76 can include multiple irregular (serpentine) electrodes, such as an octagonal star with sharp corners, to stimulate and / or ablate tissue.

[0075] The catheter may include two or more of the balloons 14 and / or transducers disclosed in connection with Figures 2A-2M. By way of example, Figure 2N illustrates a portion of a catheter including an intermediate balloon 100 between a proximal balloon 102 and a distal balloon 104. The intermediate balloon 100 excludes the electrodes 76. The proximal balloon 102 and the distal balloon 104 exclude the transducer assembly 32 but may include the electrodes 76.

[0076] 2N further illustrates that the secondary catheter shaft 106 can be positioned between adjacent balloons 102 and 100 and between adjacent balloons 100 and 104. The secondary catheter shaft 106 can have the same cross-section as the catheter shaft 12. As a result, fluid within the fluid lumen of the catheter shaft 12 can pass between the interiors of the different balloons 102, 100, and 104 and through the fluid lumen within the secondary catheter shaft 106. Additionally, one or more of the multiple electrical conductors and / or one or more electrical conductor carriers within the electrical lumen within the catheter shaft 12 can pass through the interiors of the balloons 102, 100, and 104 and enter the electrical lumen within the secondary catheter shaft 106.

[0077] While the secondary catheter shaft 106 can have the same cross-section as the catheter shaft 12, the interiors of the balloons 102, 100, and 104 are in fluid communication with one another. When the balloons are constructed to have the same or approximately the same level of stiffness, they are inflated to approximately the same pressure level. As a result, the balloons are inflated simultaneously or substantially simultaneously. However, the balloons can be constructed to have different levels of stiffness. For example, all or part of the balloons can be made of different materials and / or have different material thicknesses. A balloon with increased stiffness inflates at a higher pressure and deflates at a higher pressure. As a result, a balloon(s) with reduced stiffness inflates faster and deflates slower than a stiffer balloon. Thus, the level of balloon stiffness can be selected to inflate and / or deflate the balloons in a desired order.

[0078] While the electrodes depicted in FIG. 2N are individual, in embodiments, as depicted in FIG. 2O, one or more of the electrodes 76 comprise expandable rings or separate electrodes and / or an expandable mesh of wires that expand with the balloon 14 to provide a continuously conductive electrode ring and / or mesh that forms one or more continuous conductive circumferences around the balloon 14, such that the entire circumference of the expandable electrode(s) on the balloon 14 can make circumferential electrical contact with the inner wall of the blood vessel 360° around the vessel.

[0079] In some examples, catheters constructed according to Figures 2A-2O have a catheter shaft 12 with a diameter of 3 French or more and / or 7 French or less and / or a catheter length of 75 cm or more and / or 175 cm or less. In one example suitable for renal denervation, the catheter has a catheter shaft with a diameter of 3 French or more and / or 6 French or less and / or a catheter length of 85 cm or more and / or 155 cm or less. Additionally or alternatively, in some examples, the transducer assembly 32 and / or transducer 34 has a length (labeled Lt in Figure 2A) of 0.5 mm or more and / or 12 mm or less and / or a diameter of 3 French or more and / or 10 French or less. In one example suitable for renal denervation, the transducer assembly 32 and / or transducer 34 has a length of 0.5 mm or more and / or 8 mm or less and a diameter of 3 French or more and / or 5 French or less.

[0080] In some examples, catheters are constructed to allow the balloons to be independently inflated and / or deflated. Figures 3A through 3G illustrate examples of catheter constructions that allow for independent inflation and / or deflation of the balloons. Each balloon may or may not include electrodes 76 on the surface of the balloons 104, 100, and 102 and / or may exclude the transducer assembly 32 within the balloon. Figures 3A through 3C illustrate a portion of the distal end of a catheter shaft. Figure 3A is a perspective view of a portion of the catheter shaft. Figure 3B is a cross-section of the catheter shaft shown in Figure 3A taken along the line labeled B in Figure 3A. Figure 3C is a cross-section of the catheter shaft shown in Figure 3A taken along the line labeled C in Figure 3A. The catheter shaft includes three fluid lumens 40. Each of the lumens 40 includes a fluid port 41 and a conductor port 67 within the wall of the catheter shaft 12. In Figure 3A, the locations of the fluid ports 41 and conductor ports 67, which are located on the back side of the catheter shaft, are illustrated using dashed lines.

[0081] FIG. 3D is a perspective view of the distal end of the catheter. The distal end of the catheter shaft includes three balloons 104, 100, and 102. In FIG. 3D, each of the balloons surrounds the catheter shaft. Each of the fluid ports 41 is located inside a different balloon. Because the fluid ports 41 are located behind the balloons or catheter shaft 12, the fluid ports 41 are illustrated with dashed lines. The conductor ports 67 are positioned outside the balloons such that each of the balloons is adjacent to at least one of the conductor ports 67. A first conductor carrier may extend through each of the conductor ports 67 but is not shown for ease of illustration.

[0082] Figure 3E is a cross-section of the catheter shown in Figure 3D taken along the longitudinal axis of the catheter and through one of the balloons. For purposes of illustration, the cross-section is taken through the proximal balloon 102. However, the cross-section of Figure 3E can represent a cross-section through the other balloons (the intermediate balloon 100 and the distal balloon 104). Figure 3F is a cross-section of the catheter shown in Figure 3E taken along the line labeled E in Figure 3F. Figure 3G is a cross-section of the catheter shown in Figure 3E taken along the line labeled G in Figure 3F.

[0083] The catheter of Figures 3F-3G shows the catheter shaft received in a backing member lumen 46 defined by the backing member 42 of the transducer assembly 32. An electrical insulator 48 is illustrated as defining the backing member lumen 46 and contacting the catheter shaft 12. However, the electrical insulator 48 may be optional. As a result, the backing member 42 may define the backing member lumen 46 and contact the catheter shaft 12.

[0084] The fluid lumen 40 associated with the illustrated balloon is a fluid lumen having a fluid port 41 located inside the balloon. A first conductor carrier 66 is positioned in the fluid lumen 40 associated with the illustrated balloon. The first conductor carrier 66 can extend through the fluid port 41. In one embodiment, the first conductor carrier 66 can be mounted to a wall of the fluid port 41 so as not to significantly interfere with the fluid force conditions of the fluid port 41. The first conductor carrier 66 can carry a first conductor 70 and a second conductor 72 that are connected to the transducer assembly 32. Thus, the first conductor 70 and the second conductor 72 can provide electrical communication between the electronics 22 and the electrodes (the inner electrode 36 and the outer electrode 38) of the transducer assembly 32.

[0085] A second conductor carrier 68 is also positioned in the fluid lumen 40 associated with the illustrated balloon. The second conductor carrier 68 extends through a conductor port 67 in the wall of the catheter shaft 12 to the exterior of the catheter shaft. The second conductor carrier 68 includes one or more conductive components 84 as disclosed above. Additionally, although the electrodes disclosed in connection with FIGS. 2A through 2N are not shown on the balloon, all or some of the balloons on the catheter may each include zero, one, or more electrodes 76, and / or may include zero, one, or more electrodes 76 arranged as described above. The second conductor carrier 68 associated with the balloon may provide electrical communication between any electrodes 76 on the balloon and electronics.

[0086] In some examples, a balloon may not include a transducer assembly 32, but may only include one or more electrodes 76. In some examples, a balloon may include a transducer assembly 32, but not one or more electrodes 76. For example, the intermediate balloon 100 can exclude the electrode 76 thereon, while the proximal balloon 102 and the distal balloon 104 each exclude a transducer assembly 32. Alternatively, for example, the intermediate balloon 100 can include an electrode 76 thereon, but not include a transducer assembly 32 within the intermediate balloon 100, while either or both the proximal balloon 102 and the distal balloon 104 may include a transducer assembly 32 and / or exclude an electrode 76. A balloon that excludes the electrode 76 on the intermediate balloon 100 can be associated with a fluid lumen that excludes the second conductor carrier 68. A balloon that excludes the transducer assembly 32 can be associated with a fluid lumen that excludes the first conductor carrier 66. As a result, in some instances, the first conductor carrier 68 and / or the second conductor carrier 68 are not present in the fluid lumen 40 associated with the balloon.

[0087] FIG. 3G illustrates a first conductor carrier 68 and a second conductor carrier 68 residing in a fluid lumen 40 labeled B and a fluid lumen 40 labeled C. The fluid lumen 40 labeled A in FIG. 3G is associated with the proximal balloon 102 illustrated in FIG. 3E. As a result, the first conductor carrier 68 and the second conductor carrier 68 are not shown in the fluid lumen 40 labeled A in FIG. 3G because they exit the fluid lumen 40 labeled A as shown in FIG. 3E. Because the balloon in FIG. 3E is the most proximal of the balloons, more balloons (the middle balloon 100 and the distal balloon 104 in the illustrated example) are located distal to the balloon in FIG. 3E. As a result, the first conductor carrier 68 and the second conductor carrier 68 associated with each of these balloons bypass the balloon in FIG. 3E. Therefore, the fluid lumens 40 labeled B and C are associated with balloons distal to the proximal balloon 102 illustrated in FIG. 3E. As a result, the first conductor carrier 68 and the second conductor carrier 68 shown in the fluid lumen 40 labeled B bypass the balloon in FIG. 3E and are associated with the first of the balloons located distal to the balloon in FIG. 3E, and the first conductor carrier 68 and the second conductor carrier 68 shown in the fluid lumen 40 labeled C bypass the balloon in FIG. 3E and are associated with the second of the balloons located distal to the balloon in FIG. 3E.

[0088] 3A-3G illustrate that a fluid lumen 40 associated with one of the balloons can bypass any other balloons positioned proximal to the associated balloon. The ability of the fluid lumen 40 to bypass one or more proximal balloons allows all or some of the balloons to be independently inflated and / or deflated. For example, the central balloon on the catheter of FIG. 3D can be inflated without inflating the other balloons by transporting fluid into the balloon through the fluid lumen associated with the central balloon without transporting fluid into the other balloons. Similarly, the central balloon on the catheter of FIG. 3D can be deflated without deflating the other balloons by transporting fluid out of the balloon through the fluid lumen associated with the central balloon without transporting fluid from the other balloons.

[0089] 3A-3G illustrate fluid lumens 40 extending past their associated balloons. For example, FIG. 3E shows a fluid lumen 40 carrying a first conductor carrier 68 and a second conductor carrier 68 associated with a proximal balloon 102 extending past their associated balloons. However, in instances where the fluid lumen 40 does not serve a function past its associated balloon, the fluid lumen can terminate within or proximal to its associated balloon. Terminating one or more fluid lumens before the catheter's distal end can reduce the catheter's diameter and provide the catheter with increasing levels of flexibility approaching its distal end.

[0090] While Figures 3A through 3G illustrate a single fluid lumen 40 associated with each balloon, the catheter can be constructed so that multiple fluid lumens 40 are associated with one or more of the balloons. For example, the catheter of Figures 3A through 3G can be constructed with six fluid lumens 40, with each balloon associated with two of the fluid lumens 40. For example, fluid ports for the two fluid lumens can be located on each balloon. When multiple fluid lumens 40 are associated with a balloon, fluid can be delivered through a first selection of fluid lumens 40 to inflate the balloon and through a second selection of fluid lumens to deflate the balloon. The first selection of fluid lumens includes one or more of the fluid lumens, and the second selection of fluid lumens includes one or more of the fluid lumens and is different from the first selection of fluid lumens.

[0091] Although the catheter construction disclosed in connection with Figures 3A-3G illustrates a catheter including multiple balloons, the catheter construction according to Figures 3A-3G can have a single balloon. As an example, a catheter can be constructed having a side view construction as disclosed in connection with Figures 2D-2M, but with a cross section of the transducer assembly 32 constructed according to Figures 3E-3G.

[0092] In some examples, catheters constructed as disclosed in connection with Figures 3A-3G have a catheter shaft 12 with a diameter of 3 French or more and / or 9 French or less and / or a catheter length of 75 cm or more and / or 175 cm or less. In one example suitable for renal denervation, the catheter has a catheter shaft with a diameter of 3 French or more and / or 6 French or less and / or a catheter length of 85 cm or more and / or 155 cm or less. In some examples, one or more of the transducer assemblies 32 and / or one or more of the transducers 34, respectively, have a length (labeled Lt in Figure 3D) of 0.5 mm or more and / or 12 mm or less and / or a diameter of 3 French or more and / or 10 French or less. In one example suitable for renal denervation, the intra-balloon transducer assembly 32 and / or the intra-balloon transducer, respectively, have a length of 0.5 mm or more and / or 8 mm or less and a diameter of 3 French or more and / or 5 French or less.

[0093] The electrical pathways, contact pads 82, and electrodes 76 disclosed in connection with FIGS. 2A through 3G may be conductive traces on the surface of the balloon 14, metal foil attached to the surface of the balloon 14, or a patterned metal layer on the surface of the balloon 14. Suitable conductive traces include, but are not limited to, traces of materials such as metal, conductive polymer, flexible printed circuit (FPC), and epoxy. Suitable methods for forming conductive traces on the surface of the balloon 14 include, but are not limited to, printing and photolithography. Suitable methods for attaching metal foil to the surface of the balloon 14 include, but are not limited to, adhesive mechanisms such as glue, adhesive, and epoxy, and welding such as laser welding and heat welding. Suitable methods for forming a patterned metal layer on the surface of the balloon 14 include, but are not limited to, etching and photolithography. Examples of specific materials for the electrical pathways, contact pads 82, and electrodes 76 include, but are not limited to, stainless steel, copper, platinum, gold, nickel, nickel-plated steel, magnesium, and other suitable conductive materials.

[0094] In some examples, all or a portion of the electrical pathways, contact pads 82, and electrodes 76 disclosed in connection with FIGS. 2A through 3G are included on a flex circuit, such as a flexible printed circuit (FPC). As an example, FIG. 4A is a top view of a flex circuit. The flex circuit includes conductive pathways 110 on a substrate 112. In FIG. 4A, the substrate 112 is shown in a planar configuration, but can be bent into other configurations, such as a cylindrical configuration. The conductive pathways 110 can be patterned to function as the electrical pathways, contact pads 82, and electrodes 76 disclosed in connection with FIGS. 2A through 3G. In FIG. 4A, the conductive pathways 110 are suitable for functioning as the electrical pathways, contact pads 82, and electrodes 76 disclosed in connection with FIG. 2F.

[0095] Figure 4B is a side view of a portion of a catheter including the flex circuit of Figure 4A. Figure 4C is a cross-section of the portion of the catheter shown in Figure 4B taken along the line labeled B in Figure 4C. The flex circuit substrate 112 can be positioned on and in contact with the balloon 14. While the substrate 112 can move relative to the balloon, in some examples the flex circuit substrate can be secured to the balloon using adhesive mechanisms such as glues, adhesives, and epoxies, and welding such as heat welding and laser welding.

[0096] Each of the conductive components 84 is connected to one of the contact pads 82 by an attachment mechanism. The substrate 112 is positioned on the balloon 14 such that the electrodes 76 are at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and between locations of reduced spatial acoustic intensity. Suitable mechanisms for attaching the substrate 112 to the balloon 14 include, but are not limited to, adhesive mechanisms such as glue, adhesives, and epoxies, and welding such as heat welding and laser welding.

[0097] 4C illustrates the substrate 112 of the flex circuit wrapped around the periphery of the balloon 14 so that opposing edges of the substrate 112 touch or nearly touch each other. In instances where the substrate 112 can interact with the acoustic signal output from the transducer, such an arrangement may be desirable to increase the uniformity of the power of the acoustic signal about the longitudinal axis of the transducer. In some instances, the flex circuit is positioned on the balloon 14 so that there is a gap between opposing edges of the substrate 112.

[0098] The flex circuit of Figures 4A-4C does not include one or more insulating layers as disclosed in connection with Figures 2A-3G. As described above, one or more insulating layers can be positioned over any conductive components 84 and / or attachment mechanisms connecting the conductive components 84 to the contact pads 82. The connections between any conductive components 84 and the contact pads 82 can be made before or after the substrate 112 is attached to the balloon 14. Any insulating layer(s) positioned over the conductive components 84 and / or attachment mechanisms can be formed after connecting the conductive components 84 and the contact pads 82. Any insulating layer(s) positioned over electrical pathways, such as the pad interconnects 80 and the electrode interconnects 78, can be formed before or after connecting the conductive components 84 and the contact pads 82.

[0099] The flex circuit illustrated in FIG. 4A is a single-sided flex circuit. However, flex circuits can have a variety of other constructions. For example, the flex circuit can be a dual-access or backside flex circuit, a sculpted flex circuit, a double-sided flex circuit, a multilayer flex circuit, a rigid flex circuit, or a polymer thick-film flex circuit. Many of these flex circuit structures, such as double-sided flex circuits, use through-holes to allow the conductive pathways 110 to be located on both sides of the substrate 112. A portion of the conductive pathways 110 can be located on the backside of the substrate 112, thereby positioning a portion of the conductive pathways 110 between the balloon 14 and the substrate 112. As a result, the substrate 112 can act as one or more insulating layers as disclosed above.

[0100] Figures 5A-5C illustrate examples of double-sided flex circuits suitable for use with catheters. Figure 5A is a top view of the inside of a double-sided flex circuit including conductive pathways 110 on a substrate 112. Figure 5B is a top view of the outside of the double-sided flex circuit shown in Figure 5A. The conductive pathways 110 are patterned on the substrate 112 to function as the electrical pathways, contact pads 82, and electrodes 76 disclosed in connection with Figure 2F. Figure 5C is a side view of a portion of a catheter including the flex circuit of Figures 5A and 5B.

[0101] The flex circuit includes or is provided on the outside of the substrate 112. In addition, the flex circuit includes pad interconnects 80, electrode interconnects 78, and contact pads 82 on the inside of the substrate 112. The electrode interconnects 78 are each connected to two through-holes 121 that are in electrical communication with one of the electrodes 76 on the other side of the substrate 112. The pad interconnects 80 are each connected to the contact pads 82 and the electrode interconnects 78. Instead, the pad interconnects 80 are each connected to the contact pads 82 and the through-holes 121 that are in electrical communication with one of the electrodes 76 on the other side of the substrate 112 as shown in FIG. 5A .

[0102] The substrate 112 is attached to the balloon 14, and the conductive components 84 are each connected to one of the contact pads 82 by an attachment mechanism. The substrate 112 is positioned on the balloon 14 such that the electrodes 76 are at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and between reduced spatial acoustic intensity locations. Because the pad interconnects 80, electrode interconnects 78, and contact pads 82 are inside the substrate 112, the pad interconnects 80, electrode interconnects 78, and contact pads 82 are positioned between the balloon 14 and the substrate 112. Thus, the substrate 112 can perform the function of one or more insulating layers disclosed above.

[0103] The substrate 112 may include or consist of an electrically insulating and / or dielectric material. The substrate 112 may be selectively transparent or substantially transparent to the acoustic signal output from the transducer. Additionally or alternatively, the substrate 112 may have an impedance that matches the tissue associated with the body cavity to reduce interference with the acoustic field of the substrate 112. In some examples, the substrate 112 has an impedance greater than 1.5 MRayl and / or less than 30 MRayl. In one example, the substrate 112 has an impedance greater than 1.5 MRayl and less than 30 MRayl.

[0104] Although the substrate 112 is shown as a single layer of material, the substrate 112 can include one or more layers of material. All or a portion of the layer can be a continuous material or a porous material, such as a mat, mesh, fabric, or screen, and combinations thereof. The layer of porous material can include or consist of an assembly of multiple material elements. For example, the layer of porous material can be constructed from and / or consist of one or more material elements selected from the group consisting of an assembly of fibers, threads, strands, or nanotubes, and combinations thereof. All or a portion of the material elements included in the porous material can have a width and / or diameter that is less than the wavelength of the acoustic field. In some examples, all or a portion of the multiple material elements have a width and / or diameter that is a fraction of the acoustic wavelength of the acoustic field, such as less than one-fifth of the acoustic wavelength. Additionally or alternatively, in some examples, all or a portion of the plurality of material elements have a width and / or diameter greater than 0 μm, 5 μm, 30 μm, or 50 μm and / or less than or equal to 30 μm, 80 μm, or 120 μm. In one example, all or a portion of the plurality of material elements have a width and / or diameter greater than 5 μm and less than 80 μm. Suitable materials for the plurality of material elements in the porous material and / or one or more of the layers of the substrate include, but are not limited to, polypropylene, polyethylene, polyurethane, polyether block amide, polyamide, polystyrene, polyimide, open-chain polyurethane ether or foamed ester, any other acoustically transparent polymer or material, and combinations thereof.

[0105] The conductive paths 110 on the substrate can be conductive traces on the surface of the substrate, metal foil attached to the surface of the substrate, and / or a patterned metal layer on the surface of the substrate. Suitable conductive traces include, but are not limited to, traces of materials such as metal, conductive polymer, and conductive epoxy. Suitable methods for forming conductive traces on the surface of the substrate include, but are not limited to, printing and photolithography. Suitable methods for attaching metal foil to the surface of the substrate include, but are not limited to, adhesive mechanisms such as glue, adhesive, and epoxy, and welding such as laser welding and heat welding. Suitable methods for forming a pattern of a metal layer on the surface of the substrate include, but are not limited to, etching and photolithography. Examples of specific materials for the electrical pathways, contact pads 82, through-holes 120, and electrodes 76 include, but are not limited to, stainless steel, copper, platinum, gold, nickel, nickel-plated steel, magnesium, conductive nanotubes such as carbon nanotubes, conductive carbon materials, and any other suitable conductive material.

[0106] All or a portion of the conductive pathway 110 may be a continuous material or a porous material, such as a mesh material, a mat, a fabric, a screen, and combinations thereof. The conductive pathway 110 may include or consist of an assembly of multiple material elements. For example, a layer of porous material may be constructed from and / or consist of one or more material elements selected from the group consisting of an assembly of fibers, threads, strands, nanotubes, and combinations thereof. All or a portion of the material elements included in the porous material that function as conductive pathways may have a width and / or diameter that is less than the wavelength of the acoustic field. In some examples, all or a portion of the material elements that function as conductive pathways have a width and / or diameter that is a fraction of the acoustic wavelength of the acoustic field, such as less than one-fifth of the acoustic wavelength. Additionally or alternatively, in some examples, all or a portion of the material elements that function as conductive pathways have a width and / or diameter that is greater than 0 μm, 10 μm, 50 μm, 80 μm, and / or less than or equal to 160 μm. In one example, all or a portion of the material features have a width and / or diameter greater than 10 μm and less than or equal to 140 μm. Suitable methods for forming porous conductive pathways on a substrate include, but are not limited to, painting or printing inks such as silver conductive ink, curing conductive epoxies, flexible printed circuit application techniques, and attaching flexible flat cables (FFCs) using mechanisms such as gluing, epoxidation, or lamination during a balloon inflation process. In some examples, painting or printing inks includes thermally curing the ink. Examples of specific materials for material features included in electrical pathways such as contact pads, through-holes, and / or electrodes include, but are not limited to, carbon nanotubes.

[0107] The electrode 76 has a transmitting surface area. The transmitting surface area of the electrode 76 is the area of the electrode 76 that transmits electromagnetic signals that are received by the interior of the body cavity and the tissues that define the cavity. For example, the transmitting surface area of the electrode 76 is the area of the electrode 76 that transmits electromagnetic signals that are received by the perivascular space. As an example, the transmitting surface of the electrode 76 shown in FIG. 4C is t sIn some examples, the transmitting surfaces of the electrodes 76 are each surfaces of the electrodes 76 that are not between the electrodes 76 and the transducer.

[0108] The electrodes 76 and / or the electrodes 76 in the electrode 76 options are constructed to have a transmitting surface large enough to efficiently deliver the desired level of electromagnetic energy from the electrode(s) 76 to the perivascular space. However, as described above, the fluid inside the balloon 14 can provide cooling to the transducer assembly 32. The fluid inside the balloon 14 can also provide cooling to one or more electrodes 76 on the balloon 14. The electrodes 76 and / or the electrodes 76 in the electrode 76 options can be constructed to have a transmitting surface that can be cooled to a temperature that does not cause thrombus formation and / or endothelial wall damage. For example, the electrodes 76 and / or the electrodes 76 in the electrode 76 options are constructed to have a transmitting surface size that allows the electrodes 76 and / or the electrodes 76 in the electrode 76 options to be cooled to a desired temperature. As an example, electrode 76 and / or electrodes 76 in the electrode 76 options can be constructed to have transmit surface dimensions that allow electrode 76 and / or electrodes 76 in the electrode 76 options to be maintained at a temperature greater than 0° C. and / or less than 42° C. during transmission of acoustic fields from transducer assembly 32 and / or transmission of electromagnetic signals from electrode 76 and / or electrodes 76 in the electrode 76 options. In one example, electrode 76 and / or electrodes 76 in the electrode 76 options are constructed to have transmit surface dimensions that allow electrode 76 and / or electrodes 76 in the electrode 76 options to be maintained at a temperature greater than 5° C. and less than 40° C. during transmission of acoustic fields from transducer assembly 32 and / or transmission of electromagnetic signals from electrode 76 and / or electrodes 76 in the electrode 76 options.

[0109] In some examples, one or more electrodes 76 may each be 0 mm 2 , 0.1mm 2 , 1mm 2 , 2.5mm 2 Or 4mm 2 or more, and / or 1 mm 2, 2.5mm 2 , or 4mm 2 In an example suitable for use when treating the renal arteries, the one or more electrodes 76 each have a transmitting surface area of 1 mm 2 Over 2.5mm 2 It has the following transmitting surface area:

[0110] 2G , when the catheter includes one or more external electrodes configured such that at least a portion of the external electrode is proximal or distal to the transducer along the longitudinal axis of the transducer and beyond the acoustic signal of the transducer, the external electrode can have a wider and / or larger transmit surface area than electrodes 76 located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations. In some examples, the ratio of the transmit surface area of the external electrode to the transmit surface area of electrodes 76 located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations is greater than or equal to 2:1, 100:1, or 200:1, and / or less than or equal to 10:1, 200:1, or 500:1. Additionally or alternatively, in some examples, the ratio of the width of the outer electrode to the transmitting surface area of the electrode located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations is greater than or equal to 2:1, 100:1, or 200:1, and / or less than or equal to 10:1, 200:1, or 500:1. Thus, the outer electrode can be substantially larger than the electrode located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations. Increasing the size of the outer electrode results in lower electrical impedance, making the outer electrode more suitable for use in applications such as nerve stimulation. In one example, the ratio is greater than or equal to 50:1 and less than or equal to 200:1.

[0111] In some examples, the combined transmitting surface area for the electrodes 76 in one or more electrode 76 options is less than 10 mm 2 , 50mm 2, 100mm 2 , or 200mm 2 or more and / or 200mm 2 , 400mm 2 , or 2000mm 2 In one example, the combined transmitting surface area for the electrodes 76 in one or more electrode 76 options is 50 mm 2 Over 400mm 2 is less than.

[0112] When the catheter includes one or more electrode 76 options that include or consist of external electrodes and that include one or more electrodes 76 located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations, in some examples, the ratio of the transmit surface area of the electrodes 76 in the electrode 76 options that include or consist of external electrodes to the ratio of the transmit surface area of the electrodes 76 in the electrode 76 options that include or consist of one or more electrodes 76 located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial acoustic intensity locations is greater than or equal to 2:1, 50:1, or 100:1, and / or less than or equal to 100:1, 200:1, or 500:1. In one example, the ratio is greater than or equal to 50:1 and less than or equal to 200:1.

[0113] The thickness of the electrode 76 is labeled T in FIG. 2C . The thickness of the electrode 76 and / or electrical pathways is selected to reduce the spatial acoustic intensity between the electrode 76 and the acoustic field. For example, the electrode 76 and / or electrical pathways can have a thickness that is less than the wavelength of the acoustic field output from the transducer. In some examples, all or a portion of the electrode 76 and / or electrical pathways have a thickness that is a fraction of the acoustic wavelength of the acoustic field, such as less than one-fifth of the acoustic wavelength. Additionally or alternatively, in certain examples, all or a portion of the electrode 76 and / or electrical pathways have a thickness that is greater than 0 μm, 5 μm, or 20 μm, and / or is equal to or less than 50 μm, 80 μm, 120 μm, or 160 μm. The thickness of the electrode 76 can exceed one acoustic wavelength, in which case the system can compensate for electrode interruptions introduced into the acoustic field. In one example, all or a portion of the electrode 76 and / or electrical pathways have a thickness that is greater than 5 μm and less than 120 μm.

[0114] In some embodiments, multiple transducer assemblies can be located on one or more balloons on a catheter. As an example, FIGS. 6A and 6B show an illustration of a catheter including multiple transducer assemblies on a balloon. FIG. 6A is a perspective view of a portion of a catheter including multiple transducer assemblies 32a and 32b on a balloon 14. While two transducer assemblies are depicted in FIGS. 6A, 6C, and 6D, the catheter may include more transducer assemblies, such as, but not limited to, three, four, five, or more, e.g., 20 assemblies. The balloon 14 in FIG. 6A is illustrated as transparent so that the underlying components can be seen. FIG. 6B is a cross-section of the catheter shown in FIG. 6A taken along the line labeled B. Additionally, FIG. 6B can represent a cross-section of the catheter shown in FIG. 6A taken along the line labeled B'.

[0115] The bridge portion 113 of the backing member 42 extends between adjacent transducer assemblies 32a and 32b and can serve as the backing member 42 for multiple transducer assemblies 32a and 32b within the same balloon 14. A first conductor 74a connects to the backing member 42. A second conductor 74b connects to the outer electrode 38a of the proximal-most transducer assembly 32a and connects the outer electrode 38a to the generator through a wiring system extending through the catheter shaft. A third conductor 74c extends from the outer electrode 38b of the distal transducer assembly 32b through an opening into the internal lumen of the backing member 42 and into the catheter shaft. The conductor 74c connects the outer electrode 38b of the transducer assembly 32b to the generator through a wiring system extending through the catheter shaft.

[0116] During operation of the transducer assemblies 32a and 32b, the backing member 42 can function as a common return for electrical energy applied to the transducer assemblies 32a and 32b. As a result, the electronics can independently operate the transducer assemblies 32a and 32b by applying a voltage between the outer electrodes 38a and / or 38b of the desired transducer assembly 32a and / or 32b and the backing member 42. Alternate arrangements of the electrical conductors 74 can be used to enable independent operation of all or different selections of the transducer assemblies.

[0117] Although conductors 74a, b, and c are shown as wires in FIGS. 6A and 6C, other conductors can be employed. For example, a conductive adhesive can function as one or more of conductors 74a, b, and c. The conductive adhesive can be used with a substrate. For example, the conductive adhesive can have one or more characteristics selected from the group consisting of: on one side of the substrate, on both sides of the substrate, supported by the substrate, or positioned with the substrate by other mechanisms such as absorption or impregnation. In one example, the conductive adhesive is included in a layer on the tape that replaces third conductor 74c shown in FIG. 6A. Suitable conductive adhesives include, but are not limited to, conductive epoxies, adhesive metal films, and mixtures including acrylates and epoxies impregnated with silver-coated glass beads. Suitable substrates include, but are not limited to, plastics such as polyethylene terephthalate (PET).

[0118] At least a portion of the bridge portion of the backing member that extends between adjacent transducer assemblies can include one or more reinforced flexibility regions 114. The one or more reinforced flexibility regions can be selected to enhance the flexibility of the backing member 42 and, correspondingly, the catheter. For example, a portion of the backing member having a reinforced flexibility region can be more flexible than and / or more flexible than one or more portions of the backing member that do not have a reinforced flexibility region.

[0119] Suitable reinforced flexible regions include, but are not limited to, openings through the wall of the backing member 42 arranged in a pattern, and a backing member 42 cut into a grid pattern.

[0120] 6A is an opening 116 through the wall of the backing member 42. The opening 116 spirals around the longitudinal axis of the backing member 42 for portions of the backing member 42 located between adjacent transducer assemblies. As a result, at least one reinforced flexible portion of the backing member 42 has a spiral or substantially spiral configuration for a portion of the longitudinal length of the backing member 42. In some examples, the reinforced flexible region 114 does not extend to any of the transducer assemblies 32 within the balloon.

[0121] The helix ratio can be measured as the number of degrees the spiral rotates around the longitudinal axis of the backing member per length of the longitudinal axis. The helix ratio can determine the degree of flexibility of the flexible reinforcement portion of the backing member 42. For example, increasing the helix ratio can create a more flexible backing member, while decreasing the helix ratio can create a stiffer backing member. Suitable helix ratios (pitch numbers) include, but are not limited to, ratios of 0° / mm or greater and can extend over 360° or 720° or greater.

[0122] Using multiple transducer assemblies within a single balloon can increase the flexibility of the catheter. Increased flexibility can achieve access to small diameter body cavities, such as the accessory renal arteries and renal artery branches (e.g., vessels less than 3 mm in diameter), aid in steering the catheter through tortuous anatomical structures, and / or reduce transducer assembly eccentricity due to placement of the transducer assembly around curves within a body lumen. When it becomes more desirable to address smaller and / or more tortuous spaces, the transducer assembly 32 disclosed above can be divided into multiple smaller transducer assemblies.

[0123] While Figure 6A illustrates electrical connections that provide the electronics with the ability to operate the transducer assemblies 32 independently, the electrical connections can be configured for simultaneous operation of the transducer assemblies 32. For example, the transducer assemblies 32 can be connected in parallel or in series. As an example, Figure 6C illustrates the catheter of Figures 6A and 6B modified so that the transducer assemblies 32 are connected in series with electrical conductors 74c connected to the outer electrodes 38a and 38b of multiple different transducer assemblies 32a and 32b.

[0124] Although two transducer assemblies 32 are depicted in FIG. 6C, the catheter may include many more transducer assemblies, for example, without limitation, three, four, five, six, or more, all connected in series by conductors 74 that connect the outer electrodes 38 of each pair of transducer assemblies 32 to each other and then ultimately connect the proximal-most outer electrode 38 of the most proximal transducer assembly 32 to the generator via a wiring system that extends through the catheter shaft to the generator.

[0125] The conductors 74 connecting the external electrodes 38 of different transducer assemblies 32 can be replaced with other conductors. For example, FIGS. 6D and 6E illustrate the catheter of FIG. 6C modified so that conductive plating 92 provides electrical communication between the external electrodes 38 of different transducer assemblies 32. FIG. 6D is a perspective view of a portion of the catheter, including the transducer assembly and balloon. The balloon in FIG. 6D is illustrated as transparent, allowing the underlying components to be seen. FIG. 6E is a cross-section of the catheter illustrated in FIG. 6D taken along the line labeled E in FIG. 6D. The conductive plating 92 is in electrical communication with the external electrodes 38 of different transducer assemblies 32. Electrical insulators 94 are optionally positioned between the conductive plating 92 and the backing member 42 to electrically insulate each external electrode 38 from the backing member 42 and the internal electrode 36. Suitable platings 92 include, but are not limited to, metallic conductors. Although the bridge portion 113 illustrated in Figures 6D and 6E excludes one or more reinforced flexible regions, the bridge portion 113 may include one or more reinforced flexible regions.

[0126] All or some of the transducer assemblies 32 may each have one or more ends that are chamfered and / or include a chamfer. For example, all or some of the transducer assemblies 32 may each have one or more ends that have a tapered portion. In some examples, one or both of the ends of adjacent transducers 34 may have a tapered end. As an example, FIG. 6F is a cross-section of a portion of a catheter constructed as disclosed in connection with FIGS. 6A-6E. FIG. 6F shows the ends of two transducer assemblies 32 positioned adjacent to each other along the longitudinal axis of the catheter. Both transducer assemblies 32 have tapered ends. For example, the thickness of the transducer assemblies 32 decreases as they approach the ends of the transducer assemblies 32. The illustrated tapered portion may surround the longitudinal axis of the catheter.

[0127] In the example of FIG. 6F, the tapers on adjacent transducer assemblies 32 taper in the same direction as the thickness of both transducer assemblies 32 tapers toward the inner surface of the transducer assemblies 32.

[0128] The presence of one or more tapered portions can increase the bending range of the catheter. For example, when the backing member 42 is bent while advancing the catheter to and / or retracting the catheter from the treatment site, the one or more tapered portions can allow adjacent transducers 34 and / or transducer assemblies 32 to approach and contact each other, as shown in FIG. 6G. This allows the separation distance (Ls) between adjacent transducer assemblies 32 to be reduced while still allowing bending of the backing member 42. As a result, the benefits of one or more reinforced flexible regions between adjacent transducers 34 can be maintained as the separation between adjacent transducers 34 decreases. This ability to reduce the separation distance between adjacent transducer assemblies 32 can allow a collection of transducer assemblies 32 to approach a single transducer assembly 32, thereby increasing the uniformity of the acoustic field.

[0129] Although Figures 6F and 6G illustrate the entire end of the transducer assembly 32 as having a tapered portion, the transducer 34 may have a tapered portion while the ends of the inner and / or outer electrodes may exclude a tapered portion, as shown in Figure 6H.

[0130] While Figures 6F-6H illustrate linear tapers, the tapers may have other configurations. For example, the tapers may be curved, as shown in Figures 6I and 6J. The curvature may be configured so that the transducers 34 have a convex end, as shown in Figure 6J, or a concave end, as shown in Figure 6I. When one transducer 34 has a convex end, the end of an adjacent transducer may have a convex end.

[0131] When adjacent transducers 34 have adjacent ends, the tapered portion can optionally be configured such that, depending on the bending of the catheter, adjacent ends of transducers 34 from different transducer assemblies 32 can be in continuous or substantially continuous contact from the inner surface to the outer surface of one or both transducers. The continuous contact can occur within a plane. As an example, the page on which Figure 6G is shown represents a plane, with the ends of the transducers 34 in continuous contact from the inner surface to the outer surface of both transducers 34 within the plane, as shown by the interface labeled P.

[0132] FIG. 6F includes two dashed lines labeled AR. The dashed lines illustrate where the acoustic field output loses its desired characteristics and becomes ineffective or substantially ineffective for the desired treatment. For example, each dashed line labeled AR can mark the edge of a lobe of the acoustic field output from the transducer. The edge of the acoustic field lobe is generally located at the beginning of the tapered portion. As a result, the tapered portion can effectively define the location of the interface between the active region of the transducer assembly 32 and the inactive region of the transducer assembly 32. In many cases, it is desirable for the transducers to be sufficiently close to each other so that the conduction of thermal energy through the treatment site causes lesions formed by multiple different transducers to join and / or fuse to form a contiguous lesion at the treatment site. The thermal energy can result from the absorption of acoustic energy by tissue within the treatment site. Thus, different lobes of acoustic energy can form different lesions that join and / or fuse together through the conduction of thermal energy within the treatment site. This joining and / or fusion of the lesions allows the separated transducer assemblies to approach the performance of a single continuous transducer assembly while retaining the enhanced flexibility achieved by the presence of multiple transducer assemblies.

[0133] Figure 6F shows the L ar Additionally or alternatively, the separation distance between the active areas of adjacent transducer assemblies 34 is denoted by L ar The distance labeled L may represent the distance between the beginning of the tapered portion on adjacent transducers. When it is desired that the catheter form welded and / or fused lesions by conduction of thermal energy, a suitable separation distance (L) between the active areas of adjacent transducer assemblies may be determined. ar ) and / or the distance between the beginning of the tapered portion on adjacent transducers, including, but not limited to, a separation distance of 0.0 mm or greater and less than 0.5 mm. In some examples, the distance (L ar) and / or the distance between the beginning of the tapered portions on adjacent transducers is desirably large enough to reduce or eliminate interference between acoustic field lobes from different transducers.

[0134] In some instances, it may be desirable for the transducers to be sufficiently spaced apart so that the acoustic energy applied from the different transducers creates different, spatially separated lesions at the treatment site when the transducers are not moved at the treatment site between the application of acoustic energy to the different transducers. It may be advantageous to create multiple ablation rings at the treatment site to create lesions in multiple distinct areas where nerves may be preferentially located. By simultaneously ablating multiple different regions of the treatment site, such as an artery, overall surgical time can be reduced.

[0135] When it is desired that the catheter form non-bonded and / or non-fused lesions by conduction of thermal energy, a suitable separation distance (L) between the active areas of adjacent transducer assemblies is determined. ar ) and / or the distance between the start of the tapered portions on adjacent transducers (L ar ) includes, but is not limited to, separation distances greater than 0.5 mm.

[0136] The thickness of the transducer 34 is labeled T in FIG. 6J. The thickness can be a function of the operating frequency. The thickness of the tapered portion of the transducer is labeled dT in FIG. 6J. The length of the tapered portion is labeled dL in FIG. 6J. The tapered portion ratio can be expressed as dT / dL. The tapered portion can span all or a portion of the thickness (T) of the transducer. In some examples, the thickness (dT) of the tapered portion ranges from 0%, greater than 30%, to less than 100% of the thickness (T) of the transducer. Additionally or alternatively, the tapered portion may have a taper ratio (dT / dL) greater than 0.0, 0.3, or 1, and / or less than 0.2, 0.5, or 2. In one example, the taper ratio (dT / dL) is greater than 0.0 and less than 2. In some examples, the thickness and taper ratio of adjacent ends of different transducers are the same. In some examples, the thickness and taper ratio of adjacent ends of different transducers are the same, but in opposite directions. In some instances, adjacent ends of different transducers have the same tapered shape in that the thickness and taper rate are the same in opposite directions, both are straight, or both have the same shaped curve and / or curvature.

[0137] Although Figures 6A through 6G illustrate bridge portion 113 having reinforced flexibility regions that do not extend below the transducer assemblies, all of the portions of bridge portion 113 within the catheter can each include more reinforced flexibility regions that extend from below and between one or more transducer assemblies. Figures 6A, 6C, and 6D each illustrate a connection portion 96 of backing member 42 that extends from transducer assembly 32a to catheter shaft 12. Although the illustrated connection portion 96 is shown excluding one or more reinforced flexibility regions, connection portion 96 can optionally include one or more reinforced flexibility regions.

[0138] 6A-6J illustrate a catheter including two transducer assemblies 32 in a single balloon, the balloon can include more than two transducer assemblies 32. When the catheter includes three or more transducer assemblies 32, the backing member can include multiple bridge portions 113. All or some of the bridge portions 113 can each include one or more reinforced flexibility regions 114. In some examples, the number of transducer assemblies in the balloon is two or more and / or less than 20. In examples suitable for use when treating renal arteries, the number of transducer assemblies in the balloon is two or more and / or five or less.

[0139] Although the transducer assembly 32 in the catheter of Figures 6A through 6J is shown constructed according to Figures 2A through 2C, the transducer assembly 32 can be constructed as disclosed in connection with Figures 3E through 3G. When the transducer assembly 32 is constructed as disclosed in connection with Figures 3E through 3G, a catheter shaft can be received in the backing member lumen 46 defined by the backing member 42 of the transducer assembly 32 as disclosed in connection with Figures 3A through 3G. As a result, the portion of the backing member 42 between adjacent transducer assemblies 32 can be positioned over the catheter shaft 12.

[0140] In some examples, catheters constructed as disclosed in connection with Figures 6A through 6J have a catheter shaft 12 with a diameter of 3 French or more and / or 7 French or less and / or a catheter length of 75 cm or more and / or 175 cm or less. In examples suitable for renal denervation, the catheter has a catheter shaft with a diameter of 3 French or more and / or 6 French or less and / or a catheter length of 85 cm or more and / or 155 cm or less. In some examples, one or more of the intra-balloon transducer assemblies 32 and / or one or more of the intra-balloon transducers 34 each have a length (labeled Lt in Figure 6A) of 0.5 mm or more and / or 10 mm or less. In one example suitable for renal denervation, the intra-balloon transducer assemblies 32 and / or the intra-balloon transducers each have a length of 0.8 mm or more and / or 6 mm or less and / or a diameter of 3 French or more and / or 6 French or less.

[0141] Although the electrodes 76 disclosed in connection with FIGS. 2A through 2N are not shown on the balloon 14 in FIGS. 6A through 6J , the balloon 14 may or may not include one or more electrodes 76 arranged as described above. When the balloon 14 includes one or more electrodes 76, the second conductor carrier 68 can provide electrical communication between the one or more electrodes 76 on the balloon 14 and between the one or more electrodes 76 and the electronics. When the balloon 14 includes one or more electrodes 76, all or some of the transducer assemblies 32 can each be associated with a different selection of one or more electrodes 76. For example, one or more electrodes 76 associated with different transducer assemblies can be positioned on or adjacent to the associated transducer assembly 32. Additionally, the electronics can operate the one or more selection of electrodes 76 independently of one another. As a result, the electronics can deliver ultrasonic energy from the selection of transducer assemblies 32 and can deliver electromagnetic energy from one or more electrodes 76 associated with the selection of transducer assemblies 32 and / or from one or more electrodes 76 not associated with the selection of transducer assemblies 32.

[0142] As the length of the transducer 34 decreases, the number of lobes output from the transducer 34 can also decrease. For example, a 2.5 mm to 3 mm long transducer operating at 9 MHz may produce a single lobe. In such an example, one or more electrodes 76 on the balloon 14 can be positioned between lobes from different transducers 34. For example, one or more electrodes 76 on the balloon 14 can be positioned on a catheter component located between adjacent transducers 34. As an example, FIG. 6K is a schematic cross-section of a possible catheter configuration according to FIGS. 6A to 6J. The electrode 76 labeled A is on a catheter component located between adjacent transducers 34 and is accordingly positioned between lobes from different transducers 34. As a result, one or more electrodes 76 on the balloon 14 can each be positioned over a spatial intensity minimum that can be output from a different transducer assembly. Additionally or alternatively, all or some of the electrodes 76 on the balloon 14 may be external electrodes in that the spatial intensity maximum generated by the transducer assembly 32 occurs between the external electrodes. As a result, all or part of each of the external electrodes can be located on a portion of the catheter that is located outside the overall length (Lc) of the combined transducer assembly 32 within a single balloon. For example, the electrode 76 labeled B in FIG. 6K is an external electrode positioned such that the spatial intensity maximum generated by the transducer assembly 32 occurs between the external electrodes. Although not shown in FIG. 6K, when one or more of the electrode assemblies are configured to generate multiple lobes, one or more electrodes can be placed at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and between locations of reduced spatial acoustic intensity.In one example, the balloon 14 includes one or more electrodes 76 arranged such that all or a portion of the electrodes 76 are located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and between reduced spatial acoustic intensity locations, and / or the balloon includes one or more electrodes 76 arranged such that all or a portion of the electrodes are external electrodes, i.e., positioned between the transducers so as not to interfere with the acoustic signals of the transducers.

[0143] The separation distance between adjacent transducer assemblies 32 is labeled Ls in FIG. 6A and may represent the length of the bridge portion 113. The separation distance between adjacent transducer assemblies 32 is also labeled Ls in FIG. 6D and may represent the length of the bridge portion 113. Increasing the separation distance may increase the flexibility of the catheter. In some examples, the separation distance (Ls) is 0 mm or greater than 2 mm and / or less than 6 mm, reducing the spatial acoustic intensity between the operation of adjacent transducer assemblies 32. The total length of the combined transducer assemblies 32 within one balloon is labeled Lc in FIG. 6A.

[0144] The catheter can be used with an internal catheter. The distal end of the internal catheter can include one or more electrodes, each in electrical communication with the electronics. The internal catheter is configured so that the one or more electrodes are received in one of the catheter lumens remaining outside the catheter. For example, the internal catheter can be configured so that the one or more electrodes are received in a guidewire lumen of the catheter that is outside the catheter and exposed to the treatment site in the body cavity. The electronics can operate the one or more electrodes to stimulate nerves and / or sense nerves at the treatment site in the body cavity.

[0145] 7A-7C illustrate examples of inner catheters. FIG. 7A is a perspective view of an embodiment of an inner catheter. The inner catheter includes an inner catheter shaft 118. A transport member 120 and an electrode support 122 are positioned at the distal end of the inner catheter shaft 118. The transport member 120 can connect the electrode support 122 to the inner catheter shaft 118. In some examples, the transport member 120 and the electrode support 122 are integral with and / or constructed of the same material as the inner catheter shaft 118. The transport member 120 is optional. For example, the inner catheter shaft 118 can be directly connected to the electrode support 122.

[0146] The electrode support 122 includes a plurality of electrodes 124 spaced along the length of the electrode support 122. The electrode support 122 has an arc shape, with the electrodes positioned along the arc. While the arc is shown as a smooth arc, the arc shape may include one or more segments connected to approximate an arc configuration. All or some of the segments may be straight. The arc may be two-dimensional or three-dimensional. For example, the arc may approximate a semicircle or may approximate a spiral.

[0147] The longitudinal axis of the electrode support 122 is shown in FIG. 7A by the dashed line labeled LA. The length of each electrode along the longitudinal axis of the electrode support 122 is labeled LE. The spacing between the electrodes 124 along the longitudinal axis of the electrode support 122 is labeled LS. In some examples, the length of each electrode along the longitudinal axis of the electrode support 122 is greater than 0.1 mm and / or the spacing between the electrodes 124 along the longitudinal axis of the electrode support 122 is greater than 0.1 mm and less than 3 mm. In one example of an electrode support suitable for use in treating renal arteries, the electrode support 122 includes at least four or at least eight electrodes, the length of each electrode along the longitudinal axis of the electrode support 122 is greater than 0.1 mm, and the spacing between the electrodes 124 along the longitudinal axis of the electrode support 122 is greater than 0.5 mm and less than 1.5 mm.

[0148] The coverage angle is measured as the angular extent over which the electrode is positioned on the arc, and is labeled Θ in FIG. 7A. When the arc is two-dimensional, the coverage angle can be measured from the center of gravity. In FIG. 7A, the center of gravity of the arc is labeled C. When the arc is three-dimensional, the coverage angle can be measured from the axis of the arc. For example, when the arc is spiral, the coverage angle can be measured from the spiral axis or twist axis. When the arc is three-dimensional, the coverage angle can exceed 360°. In some instances, the coverage angle is greater than 720°.

[0149] When the electrode support 122 has an arcuate geometry, the radius of curvature of the arc can be constant or can vary along the length of the electrode support. In examples where the radius of curvature varies along the length of the electrode support, the radius of curvature has a maximum and a minimum value along the length of the electrode support. In some examples, the constant radius of curvature is greater than 1 mm and less than 4 mm. In some examples, the maximum radius of curvature is greater than 1 mm and less than 5 mm, and the minimum radius of curvature is greater than 1 mm and less than 5 mm. The constant radius of curvature value, or the maximum and minimum radius of curvature values, can be selected to conform to the body lumen. For example, the constant radius of curvature value, or the maximum and minimum radius of curvature values can be selected to achieve a desired number of contact points between the electrode 124 and the wall(s) of the body lumen. In examples suitable for use in renal arteries, the constant radius of curvature is greater than 1 mm and less than 5 mm, or the maximum radius of curvature is greater than 1 mm and less than 5 mm, and the minimum radius of curvature is greater than 1 mm and less than 5 mm.

[0150] The electrode support 122 can have other geometric shapes. For example, the electrode support 122 can be configured as a basket with arms each extending from the inner catheter shaft 118. The arms 125 can each have a distal end, and the distal ends of different arms can be connected. As an example, FIG. 7B illustrates an electrode support 122 having four arms 125 with connected distal ends. The arms can be positioned regularly or periodically around the inner catheter shaft 118.

[0151] In some examples, the length of each electrode along the longitudinal axis of each arm 125 is greater than 0.1 mm.

[0152] Although the electrode support 122 in FIG. 7B has two electrodes 124 on each arm 125, each arm can have one or more electrodes 124. Furthermore, different arms can have the same number of electrodes 124 or different numbers of electrodes 124. In some examples, the number of electrodes 124 along each arm is selected depending on the length of the desired treatment area. For example, an electrode support 122 for use with a longer treatment area can have longer arms and, accordingly, more electrodes on all or some of the arms. In some examples, when an arm includes multiple electrodes 124, the spacing between the electrodes 124 along the longitudinal axis of the arm 125 is greater than 0.1 mm, and the spacing between the electrodes 124 along the longitudinal axis of the arm 125 is greater than 0.5 mm but less than 1.5 mm. One example of an electrode support suitable for use in treating renal arteries has multiple electrodes on each arm 125, with each electrode having a length along the longitudinal axis of the arm greater than 0.1 mm and a spacing between electrodes 124 along the longitudinal axis of each arm greater than 0.5 mm and less than 1.5 mm.

[0153] 7B has four arms 125, the electrode support 122 can have more than two arms. In one example of an electrode support suitable for use in treating renal arteries, the electrode support 122 has between 3 and 20 arms 125, between 2 and 10 electrodes per arm, the length of each electrode along the longitudinal axis of the arm 105 is greater than 0.5 mm, and the spacing between the electrodes 124 along the longitudinal axis of each arm is greater than 0.5 mm and less than 3 mm.

[0154] Although the electrodes are shown as being the same height as the electrode support 122, one or more of the electrodes 124 may be taller than the electrode support 122. Although Figures 7A and 7B illustrate the electrode support 122 as having a rectangular cross section, the electrode support 122 may have other geometric shapes, such as circular or oval.

[0155] As is apparent in FIG. 7A , the electrical cable 126 can extend from the proximal end of the inner catheter shaft 118. The inner catheter shaft 118 can include electrical conductors (not shown) that are each in electrical communication with one or more of the electrodes 124. In some examples, the electrodes are individually connected to the electronics. For example, when the electrode support has N electrodes 124, the inner catheter shaft 118 can carry N electrical conductors, each in electrical communication with a different one of the N electrodes. As a result, the electronics can apply electrical energy to any one of the N electrodes selected by the electronics. In some examples, the electrodes include one or more electrode options, where the electrodes 124 are individually connected to the electronics. For example, when the electrode support has N electrodes 124, the inner catheter shaft 118 can carry N electrical conductors, each in electrical communication with a different one of the N electrodes. As a result, the electronics can apply electrical energy to any one of the N electrodes selected from the N electrodes and / or to any group of electrodes selected from the N electrodes. Additionally or alternatively, the electronic device may receive electrical energy from any one of the electrodes selected from the N electrodes and / or from any group of the electrodes selected from the N electrodes.

[0156] Electrode 124 can be connected to one or more electrode options. The electrode options can include a plurality of electrodes 124 connected as a distributed electrode, or can include a single electrode. The electrodes 124 within the distributed electrode can be connected to a single node such that the electrical energy flowing through the node is distributed across all of the electrodes 124 within the distributed electrode. As a result, when the electrode support has N electrodes 124 disposed in M electrode options, where M < N, the inner catheter shaft 118 can carry M conductors that are each in electrical communication with a different one of the N electrodes. As a result, the electronic device can apply electrical energy to any one of the electrode options selected from the M electrode options, and / or to any group of the electrode options selected from the M electrode options. Additionally or alternatively, the electronic device can receive electrical energy from any one of the electrode options selected from the M electrodes, and / or from any group of the electrode options selected from the M electrode options. Conductors suitable for use in cable 126 include, but are not limited to, wires.

[0157] The inner catheter is configured to be received within one of the lumens of the catheter that function as an inner catheter lumen. For example, FIG. 7C illustrates the inner catheter of FIG. 7A positioned within the lumen of the guide wire of the catheter disclosed in connection with FIG. 5C. Thus, the guide wire lumen can function as an inner catheter lumen. As is apparent from FIG. 7C, the inner catheter shaft 118 can be longer than the catheter shaft 12, so that the inner catheter shaft remains accessible after the electrode support is introduced into the body cavity through the catheter shaft 12. In some examples, the inner catheter has an inner catheter shaft 118 that has a diameter of 1 French or more and / or 6 French or less, and / or the length of the inner catheter is 75 cm or more and / or 200 cm or less. In one example suitable for renal denervation, the inner catheter has an inner catheter shaft 118 that has a diameter of 2 French or more and 5 French or less, and / or the length of the inner catheter is 85 cm or more and 160 cm or less. The catheter shaft and the inner catheter shaft can be constructed of the same material or different materials.

[0158] The distal end of the catheter is configured to be inserted into a body cavity of a subject. Examples of suitable body cavities include, but are not limited to, veins and / or arteries, such as the renal arteries. As an example, FIG. 8 is a cross-sectional view of a body cavity 128 having multiple nerves on its outer surface. For example, the body cavity 128 in FIG. 8 may represent a blood vessel, such as a renal artery, with nerves 132 running throughout the vessel. As illustrated in FIG. 6, the balloon 14, the distal portion of the catheter shaft 12, and the tip member 15 are received in the body cavity 128. A guidewire 31 may be used to assist in placing the catheter in the body cavity 128, as shown in FIG. 8.

[0159] The balloon 14 can be a compliant balloon 14 or a non-compliant balloon 14 .

[0160] The electronics 22 can operate the transducer assembly 32 such that the transducer outputs an acoustic signal before, during, and / or after inflation of the balloon 14 to the second inflated diameter and / or second inflation pressure. In some examples, the electronics 22 can operate the transducer assembly 32 at an operating frequency of 1 to 20 MHz. For example, the transducer can be configured with an operating frequency of approximately 9 MHz, 10 MHz, or 12 MHz. In other examples, the transducer outputs an acoustic signal at a frequency less than 1 MHz. For example, the transducer can have an operating frequency of at least 0.1 MHz and not more than 20 MHz. The operating frequency of the acoustic signal can be a function of the particular application, function, or use of the catheter.

[0161] In some embodiments including multiple transducer assemblies in a single balloon or multiple balloons each having one or more transducer assemblies, each transducer may have the same or different operating frequencies. In some embodiments, a catheter may include transducer assemblies optimized for the same or different applications and / or target structures. For example, in some embodiments, a catheter may include one or more transducer assemblies including transducers having an operating frequency optimized for imaging, e.g., between about 2 MHz and 60 MHz, e.g., between 20 and 60 MHz, and one or more transducer assemblies including transducers having an operating frequency optimized for ablation, e.g., between 1 MHz and 20 MHz, e.g., between 6 MHz and 15 MHz, or between 6 MHz and 10 MHz, or 9 MHz. For example, in an embodiment optimized for denervation, one or more of the operating frequencies of the transducer assemblies may be 9 MHz, 10 MHz, and / or 12 MHz.

[0162] The power supplied to the transducer to generate the acoustic signal can vary as desired or needed. In some examples, the power supplied to the transducer to generate the acoustic signal is between 5 and 80 watts. The duration for which the acoustic signal is applied to the body cavity can vary depending on a variety of factors, including the treatment procedure, the power level at the transducer, the frequency of the emitted acoustic signal, the size of the body cavity or the type of tissue being treated, the age of the patient, the weight of the patient, and the gender of the patient. However, in some examples, the acoustic signal is applied to the body cavity for a duration of at least 0.1 seconds and not more than 20 minutes.

[0163] The electronics 22 can use one or more electrodes 76 on the balloon 14 for one or more different purposes. For example, one or more of the electrode 76 options may be operated to generate an electromagnetic signal that performs ablation. For example, the electromagnetic signal can have a radio frequency, such as an RF signal. Thus, the electromagnetic signal can be an RF signal that ablates tissue associated with a body cavity, such as tissue defining the inner surface of the body cavity and / or tissue adjacent to or around the body cavity. In some examples, the electronics 22 operates one or more of the electrode 76 options to generate an RF signal that ablates nerves associated with a body cavity, such as nerves within the body cavity, nerves in tissue defining the body cavity, and / or nerves adjacent to and / or around the body cavity. In one example, one or more electrodes 76 are used to generate RF energy that ablates nerves associated with the renal arteries to reduce high blood pressure. In one example, one or more electrodes 76 are used to generate RF energy that ablates sympathetic nerves in the hepatic plexus in the hepatic artery, which is involved in blood glucose levels, which is important for treating diabetes. In another example, one or more electrodes 76 can be used to generate RF energy to ablate cardiac tissue that induces abnormal heart rhythms to treat atrial fibrillation.

[0164] Using electrodes 76 on the balloon 14 to deliver RF energy for ablation advantageously allows ablation energy to be delivered to areas that would otherwise be inaccessible by an ultrasound balloon 14 catheter or an RF catheter using electrodes 76 on a more rigid structure.

[0165] In some instances, one or more of the electrodes 76 of the balloon 14 and the transducer 34 all generate ablation energy simultaneously to aid in more efficient and rapid denervation and / or ablation procedures.

[0166] As described above, the electronics 22 can operate one or more pairs of electrode 76 options as bipolar electrodes 76 and / or operate one or more of the electrode 76 options as monopolar electrodes 76. In some examples, applying ablation energy with bipolar electrodes 76 can enable more controlled ablation and / or shallower ablation than monopolar electrode 76 implementations. In some examples, the electronics 22 identifies one or more pairs of electrode 76 options to operate as bipolar electrodes 76 and / or one or more electrode 76 options to operate as monopolar electrodes 76. In some examples, the electronics 22 includes a user interface that an operator uses to program the identity of one or more pairs of electrode 76 options to operate as bipolar electrodes 76 and / or one or more electrode 76 options to operate as monopolar electrodes 76 into the electronics 22. In some examples, the one or more pairs of electrode 76 options to operate as bipolar electrodes 76 and / or one or more electrode 76 options to operate as monopolar electrodes 76 are stored in the electronics 22. For example, when the catheter has electrodes 76 arranged as shown in FIG. 2H, the external electrodes positioned distally on the balloon 14 can each be connected to a different electrode 76 option and operate as a bipolar electrode 76. Additionally or alternatively, the external electrodes positioned proximally on the balloon 14 can each be connected to a different electrode 76 option and operate as a bipolar electrode 76. An electrode 76 option that includes or consists of one or more electrodes 76 located between adjacent lobes can operate as a unipolar electrode 76 when the dispersive electrode 76 is positioned on the patient's body away from the catheter.

[0167] In examples where the electrode 76 options operate as monopolar electrodes 76 that output electromagnetic signals to perform ablation and / or denervation, the electromagnetic signals output from one or more electrodes 76 included in the electrode 76 options can have a frequency greater than or equal to 0 Hz, 2 Hz, 9 Hz, or 100 Hz and / or less than 500 Hz. The pulse duration can be 0.5 ms to 10 ms. Additionally or alternatively, the power level of the electromagnetic signal can be greater than or equal to 0.5 mAmp and / or less than or equal to 10 mAmp. In some examples, the electromagnetic signal has a square or rectangular waveform.

[0168] In examples where a pair of electrode 76 options operates as a bipolar electrode 76 that outputs electromagnetic signals to perform ablation and / or denervation, the electromagnetic signals output from one or more electrodes 76 included in the electrode 76 options functioning as the active electrode 76 can have a frequency greater than or equal to 0 Hz, 2 Hz, 9 Hz, or 100 Hz and / or less than 500 Hz. The pulse duration is 0.5 ms to 10 ms. Additionally or alternatively, the power level of the electromagnetic signal can be greater than or equal to 0.5 mAmp and / or less than or equal to 10 mAmp. In some examples, the electromagnetic signal has a square or rectangular waveform.

[0169] The electrode option(s) 76 can be used to perform one or more applications in addition to ablation and / or denervation, or as an alternative to or in addition to ablation. Applications for the electrode option(s) 76, electrode option(s) 124, and electrode option(s) 124 are mapping and / or sensing of nerves within a body cavity, within tissue defining a body cavity, within tissue surrounding a body cavity, and / or associated with a body cavity. Examples of suitable methods for mapping nerves within a body cavity, within tissues defining a body cavity, within tissues surrounding a body cavity, and / or associated with a body cavity using electrode 76 options, one or more electrodes 124, and / or one or more electrode 124 options can be found in U.S. Provisional Patent Application No. 63 / 263,000, filed October 25, 2021, entitled "CATHETERS FOR NEURAL MEASUREMENTS AND TREATMENT AND RELATED SYSTEMS AND METHODS," and U.S. Patent Publication No. 20220095979, filed April 11, 2021, entitled "INTRALUMINAL MICRONEUROGRAPHY PROBES AND RELATED SYSTEMS AND METHODS," both of which are incorporated herein by reference in their entireties. Examples of suitable methods for using electrode 76 options, one or more electrodes 124, and one or more electrode 124 options to sense within a body cavity, within tissue defining a body cavity, within tissue surrounding a body cavity, and / or nerves associated with a body cavity can be found in U.S. Patent Publication No. 2022 / 0095979, entitled "INTRALUMINAL MICRONEUROGRAPHY PROBES AND RELATED SYSTEMS AND METHODS," which is incorporated herein in its entirety.

[0170] Another use for option one or more of electrodes 76, option one or more of electrodes 124, and option one or more of electrodes 124 is to stimulate nerves at a treatment site in a body cavity. For example, another application for option one or more of electrodes 76, option one or more of electrodes 124, and / or option one or more of electrodes 124 is to stimulate nerves in the renal arteries. One example of a suitable method of stimulating nerves using one or more electrodes 76 can be found in U.S. Patent Publication No. 2018 / 0221087, which is incorporated herein in its entirety, and in U.S. Patent Publication No. 2017 / 0035310, which is incorporated herein in its entirety.

[0171] Another use for one or more optional electrodes 76, one or more electrodes 124, and / or one or more optional electrodes 124 is to measure one or more dimensions and / or characteristics of a body cavity, such as the width and / or cross-sectional area of the body cavity. For example, impedance between optional electrodes 76, between electrodes 124, and / or between optional electrodes 124 may be measured to assist in measuring the width of the body cavity. One or more optional electrodes 76 may additionally or alternatively determine the apposition between the vessel wall and the electrodes 76 and / or balloon 14, which may be used in determining the size of the body cavity, whether inflation of the balloon 14 is sufficient, and / or whether an appropriately sized balloon 14 was implemented in the procedure. Examples of suitable methods for measuring one or more dimensions, characteristics of a body cavity and / or validating balloon options using one or more electrode 76 options, one or more electrodes 124, and / or one or more electrode 124 options can be found in U.S. Provisional Patent Application No. 63 / 223,519, filed July 19, 2021, entitled "METHODS AND SYSTEMS FOR DETERMINING BODY LUMEN SIZE," which is incorporated herein in its entirety.

[0172] The electronics 22 can use one or more electrode 76 options to perform one or more of the applications at one or more moments selected from the group consisting of before, during, and after transmission of the acoustic signal from the transducer. As a result, the electronics 22 can use one or more electrode 76 options on the balloon 14 at one or more moments selected from the group consisting of before, during, and after inflation of the balloon 14. As an example, the electronics 22 can operate all or a portion of the one or more electrode 76 options to map, stimulate, and / or sense nerves associated with a body cavity, such as a renal artery. After mapping, stimulating, and / or sensing nerves associated with a body cavity, the electronics 22 can operate all or a portion of the one or more electrode 76 options and / or the transducer to ablate and / or denervate the mapped and / or sensed nerves. After applying ablation energy to the mapped and / or sensed nerves, electronics 22 can operate all or a portion of one or more electrode options 76 to image the area of the body cavity where ablation energy was applied. From the imaging, electronics 22 and / or the operator can assess the success of the treatment and, from that assessment, decide whether to apply additional ablation energy.

[0173] As is apparent from the above, an embodiment of the catheter includes a balloon enclosing one or more transducer assemblies and having one or more electrode 76 options on the surface of the balloon. In one example of operating the catheter, the catheter is advanced through a body lumen such that one or more electrode 76 options are positioned to measure neural activity at a target location within the body lumen. Electronics can then operate one or more electrodes on the distal balloon 104 to measure neural activity at the target location. The neural activity can be measured to determine whether treatment is desired at the target location. Suitable methods for operating one or more electrodes to measure neural activity can be found in U.S. Provisional Patent Application No. 63 / 263,000, filed April 11, 2021, and entitled "INTRALUMINAL MICRONEUROGRAPHY PROBES AND RELATED SYSTEMS AND METHODS," and U.S. Patent Publication No. 20220095979. Once it is determined that treatment is desired at the target location, the electronics can operate the transducer assembly and / or one or more electrodes 76 to ablate and / or denervate the nerve(s) at the target location. The electronics can operate the one or more electrodes 76 to determine the effectiveness of the prior ablation and / or denervation. The effectiveness of the prior ablation and / or denervation can be determined by measuring the level of neural activity at the target location using one or more electrodes. Once the electronics determine that the prior ablation and / or denervation was ineffective or insufficient, the electronics can operate the transducer assembly and / or one or more electrodes 76 to perform further ablation and / or denervation of the nerve, and the process can be repeated until the electronics determine that the prior ablation was effective or sufficient. Once the electronics determine that the prior ablation was effective or sufficient, the catheter can be advanced so that the balloon is positioned at a second location within the body cavity. The method can then be repeated, with the second location as the target location.

[0174] As disclosed in connection with FIGS. 2A to 6E, one embodiment of a catheter constructed includes an intermediate balloon 100 between a proximal balloon 102 and a distal balloon 104. In some examples, the catheter is operated such that all three balloons are inflated to occlude the body cavity. In other examples, the intermediate balloon 100 does not occlude the body cavity, and the proximal balloon 102 and the distal balloon 104 are used to align the transducer assembly at the center within the body cavity. In one embodiment, one or more electrodes and the transducer all generate ablation energy, for example, simultaneously, to assist in a more efficient and rapid denervation procedure.

[0175] An example of a catheter constructed as disclosed in connection with FIGS. 2A to 2M includes an intermediate balloon 100 between a proximal balloon 102 and a distal balloon 104. FIG. 2N depicts an embodiment in which the intermediate balloon 100 includes the transducer assembly and excludes the electrode 76. The proximal balloon 102 and the distal balloon 104 may also include the transducer assembly 32 and one or more electrodes 76. FIG. 2N depicts the proximal balloon 102 and the distal balloon 104 each including an individual electrode 76, but circumferential rings, segmented electrodes, and / or mesh electrodes may be provided additionally or alternatively to enhance 360° nerve sensing and / or nerve stimulation around a body cavity, such as the renal artery. And while the intermediate balloon 100 is depicted as including only the transducer 34, the intermediate balloon 100 may include the electrode 76 or exclude the transducer 34 and include only the electrode 76.

[0176] In one example of operating a catheter, the catheter is advanced through a body cavity such that one or more electrodes are positioned to measure neural activity at the target location. Electronics can then operate one or more electrodes on the distal balloon 104 to measure neural activity at the target location. The neural activity can be measured to determine whether treatment is desired at the target location, which may be the proximal intermediate balloon 100, the proximal balloon 102, and / or the distal balloon 104. Suitable methods for operating one or more electrodes to measure neural activity can be found in U.S. Provisional Patent Application No. 63 / 263,000, filed April 11, 2021, and entitled "INTRALUMINAL MICRONEUROGRAPHY PROBES AND RELATED SYSTEMS AND METHODS," and U.S. Patent Publication No. 20220095979. Upon determining that treatment is desired at the target location, a first movement can be made, for example, to move the catheter so that the intermediate balloon 100 is suitably positioned to treat nerves at the target location. The electronics can operate the transducer assembly and / or one or more electrodes on the intermediate balloon 100 to ablate the nerve. A second movement can be performed to move the catheter so that the proximal balloon 102 is suitably positioned to measure neural activity at the target location. The electronics can operate one or more electrodes on the proximal balloon 102 to determine the effectiveness of the prior ablation and / or denervation. The effectiveness of the prior ablation can be determined by measuring the level of neural activity at the target location using one or more electrodes on the proximal balloon 102 and / or one or more electrodes on the distal balloon 104. If the electronics determine that the prior ablation was ineffective or insufficient, a third movement can be performed to move the catheter so that the intermediate balloon 100 is suitably positioned to treat the nerve at the target location. The electronics can operate the transducer assembly and / or one or more electrodes on the intermediate balloon 100 to perform additional ablation and / or denervation of the nerve.The second movement can then be repeated, and the process can be repeated until the electronics determine that the prior ablation was effective or sufficient. Once the electronics determine that the prior ablation was effective or sufficient, the catheter can be configured to place the distal balloon 104 at a second position. The method can then be repeated, with the second position as the target position.

[0177] When a catheter is used with an internal catheter, the catheter and / or the internal catheter can be delivered to a body cavity using a guide mechanism, such as a guidewire, or a guide catheter. In some examples, a guidewire is advanced through the body into the body cavity, the catheter is advanced over the guidewire to the body cavity, the guidewire is withdrawn through the catheter from the body cavity, and the catheter is advanced over the internal catheter to the body cavity. In some examples, the catheter is advanced into the body cavity after the internal catheter has been advanced into the body cavity. As a result, the catheter can be introduced into the body cavity before the internal catheter. When a catheter is advanced into the body cavity after the internal catheter has been introduced into the body cavity, the internal catheter can function as a guidewire. Thus, the catheter can be advanced into the body cavity along with the internal catheter. Next, electronics can operate one or more electrodes on the balloon to measure neural activity at the target location. The neural activity can be measured to determine whether treatment is desired at the target location. Suitable methods for manipulating one or more electrodes to measure neural activity can be found in U.S. Provisional Patent Application No. 63 / 263,000, filed April 11, 2021, and entitled "INTRALUMINAL MICRONEUROGRAPHY PROBES AND RELATED SYSTEMS AND METHODS," and U.S. Patent Publication No. 20220095979. Upon determining that treatment is desired at the target location, a first movement can be made to move the catheter to a location within the body cavity where a balloon on the catheter is suitably positioned to treat the nerve at the target location. Electronics can operate the transducer assembly and / or one or more electrodes on the balloon to ablate and / or denervate the nerve at the target location. If the catheter is not positioned within the body cavity prior to determining that treatment is desired at the target location, the inner catheter can be advanced into the body cavity, and then the catheter can be advanced along the inner catheter to place the balloon at the desired location. Alternatively, the catheter may be positioned on the inner catheter prior to determining that treatment is desired at the target location.For example, before neural activity is measured at a target location, the electrode support of the inner catheter can be introduced into the body cavity by threading the inner catheter through the lumen of the catheter, or the catheter can be advanced over the inner catheter. When the catheter is positioned over the inner catheter before it is determined that treatment is desired at the target location, the combination of the catheter and inner catheter can be advanced simultaneously through the body cavity until the balloon on the catheter is suitably positioned to treat the nerve at the target location.

[0178] After treatment of the nerve at the target location, if the balloon used to perform the ablation and / or denervation includes one or more of the electrodes 76, the electronics can operate one or more electrodes on the balloon to determine the effectiveness of the prior ablation and / or denervation. The effectiveness of the prior ablation and / or denervation can be determined by measuring the level of neural activity at the target location using one or more electrodes 76 on the balloon. If the electronics determine that the prior ablation was ineffective or insufficient, the electronics can operate the transducer assembly and / or one or more electrodes on the balloon to perform additional ablation and / or denervation of the nerve. The electronics can again determine the effectiveness of the prior ablation and / or denervation using one or more electrodes 76, and the process can then be repeated until the electronics determine that the prior ablation was effective or sufficient. If the electronics determine that the prior ablation was effective or insufficient, the catheter can be configured to place one or more electrodes 124 on the electrode support in a second position. The method can then be repeated with the second location as the target location.

[0179] After treating the nerve at the target location, if the balloon used to perform the ablation and / or denervation does not include one or more of the electrodes 76, or if it is preferable to sense neural activity with one or more of the electrodes 124 on the internal catheter, a second movement can be made to move the catheter and the internal catheter so that one or more of the electrodes 124 are suitably positioned to measure neural activity at the target location. The electronics can operate the one or more electrodes 124 to determine the effectiveness of the prior ablation and / or denervation. The effectiveness of the prior ablation can be determined by measuring the level of neural activity at the target location using the one or more electrodes 124. If the electronics determine that the prior ablation and / or denervation was ineffective or insufficient, a third movement can be made to move the catheter and the internal catheter to a location within the body cavity where the balloon on the catheter is suitably positioned to treat the nerve at the target location. The electronics can operate the transducer assembly and / or one or more electrodes on the balloon to perform additional ablation and / or denervation of the nerve. The second movement is then repeated, and the process can be repeated until the electronics determine that the prior ablation and / or denervation was effective or sufficient. Once the electronics determine that the prior ablation and / or denervation was effective or sufficient, a fourth movement can be made to move the internal catheter so that one or more of the electrodes 124 are suitably positioned to measure neural activity at a second location within the body cavity. The method can then be repeated, with the second location as the target location.

[0180] In cases where the method does not fall into any of the above examples when measuring neural activity, or in all or some of the above examples, a cathode can be used to stimulate the nerve being measured. For example, all or some of the electrodes 76 and / or 102 used to measure neural activity can be used to stimulate the nerve before measuring neural activity. The catheter need not be moved into the body cavity between stimulating the nerve and subsequently measuring activity. Suitable methods for stimulating a nerve using one or more electrodes 76 and / or 102 are described in U.S. Patent Publication Nos. 2018 / 0221087 and 15 / 299694, entitled "Nerve Probe," filed April 2, 2018, each of which is incorporated herein by reference in its entirety. As a result, neural activity can be measured relative to a previously stimulated nerve, facilitating nerve localization. The one or more electrodes used to stimulate the nerve at a location within the body cavity can be the same or different from the one or more electrodes used to measure neural activity.

[0181] In some examples where nerves are stimulated, some of the electrodes 76 are used to sense neural activity, other portions of the electrodes 76 are used to stimulate neural activity, and some of the electrodes 124 are used to sense neural activity and other portions of the electrodes 124 are used to stimulate neural activity. As a result, some of the electrodes are used to sense neural activity and other portions of the electrodes are simultaneously used to stimulate neural activity. In these examples, the electrodes used to sense neural activity can be separated by more than 2 mm from the electrodes used to stimulate neural activity to reduce spatial acoustic intensity. The separation can be a product of electrode selection by the electronics or physical separation of the electronics on the electrode support or balloon.

[0182] In some examples, determining whether treatment is desired at the target location includes, consists of, or consists essentially of comparing the measured level of neural activity to a first activity threshold. When the measured level of neural activity is below the first activity threshold, treatment may not be required or desired. When the measured level of neural activity is equal to or greater than the first activity threshold, treatment may be required or desired. In some examples, determining that prior ablation at the target location was ineffective or insufficient includes, consists of, or consists essentially of comparing the measured level of neural activity to a second activity threshold. When the measured level of neural activity is below the second activity threshold, the prior ablation can be determined to be effective or sufficient. When the measured level of neural activity is equal to or greater than the second activity threshold, the prior ablation can be determined to be ineffective or insufficient.

[0183] The above description of the catheter and / or internal catheter operation describes one or more movements of the catheter within the body cavity. These movements include moving from one location to another within the body cavity and / or adjusting the position of the catheter within the body cavity. Movement of the catheter within the body cavity may include deflation of any balloons at a first location within the body cavity, followed by physical rotation and / or translation of the catheter, followed by re-inflation of one or more balloons on the catheter at a second location.

[0184] The above description of methods for operating a catheter and / or internal catheter includes one or more operations in which a treatment site within a body cavity is ablated and / or denervated. When the denervation and / or ablation includes the use of one or more electrodes 76, the electronics 22 can operate one or more paired electrode 76 options as bipolar electrodes 76. Alternatively, the electronics 22 can operate one or more of the electrode 76 options as unipolar options. Additionally, the electromagnetic signal and acoustic signal can alternate in sequence without overlapping the delivery of the electromagnetic signal and acoustic signal. Alternatively, the electromagnetic signal and acoustic signal can be applied simultaneously. A higher frequency of the acoustic signal relative to the electromagnetic signal can reduce or eliminate the spatial acoustic intensity between the electromagnetic signal and the acoustic signal during simultaneous application of the electromagnetic signal and acoustic signal. Thus, one or more electrodes 76 associated with the balloon and the transducer assembly within the balloon can operate simultaneously.

[0185] In some examples of denervation and / or ablation, the electromagnetic signal is delivered to the treatment site at a frequency greater than 0 Hz and / or less than 500 Hz, and / or the acoustic signal is delivered to the treatment site at a frequency greater than 1 MHz and less than 20 MHz. In examples suitable for use in treating renal arteries, the electromagnetic signal is delivered to the treatment site at a frequency greater than 100 Hz and / or less than 500 Hz, and / or the acoustic signal is delivered to the treatment site at a frequency greater than 1 MHz and less than 9 MHz.

[0186] The transducer assemblies disclosed above may have alternative constructions. For example, one or more of the transducer assemblies included in one of the catheters described above may have a step-down construction. As an example, FIG. 9 is a cross-section of the catheter shown in FIG. 2A modified to include a recess 150 extending into the transducer 34. The recess 150 may extend through the external electrode 38, as shown in FIG. 9. Accordingly, one or more side(s) of the recess 150 may be defined by the transducer 34 and / or the external electrode 38. Additionally or alternatively, one or more side(s) of the recess 150 may be open at the end of the transducer 34. Electrical conductors, such as the second electrical conductor 72, may be attached to the floor and / or one or more side(s) of the recess 150. The recess 150 may be sufficiently deep so that the conductors do not separate from the transducer 34 and / or the external electrode 38. Accordingly, the conductors may be positioned at or below the level of the outer surface of the transducer 34 and / or the external electrode 38. Although recess 150 is not shown extending around the axis of the transducer, recess 150 may surround the axis of the transducer.

[0187] The above-described transducer assemblies may also optionally include insulation. For example, when a transducer assembly such as the above-described transducer assembly 32 of FIGS. 2A and 2B is exposed to a conductive liquid, such as a conductive cooling fluid, saline, or a conductive body fluid such as blood, the conductive liquid may provide a short circuit between the inner electrode 36 and the outer electrode 38. FIGS. 10A and 10B illustrate the electrode assembly 32 of FIGS. 2A and 2B modified to include an electrical insulator 152. FIG. 10A is a cross-section of the distal end of the catheter taken along the longitudinal axis of the catheter. FIG. 10B is a cross-section of the catheter shown in FIG. 10A taken along the line labeled B in FIG. 10A. The electrical insulator 152 is positioned on the outer surface of the outer electrode 38 and the inner surface of the inner electrode 36. In addition, the electrical insulator 152 is positioned on the edges of the outer electrode 38 and the inner electrode 36. As a result, the electrical insulator 152 can prevent fluid from forming an electrical path between the outer electrode 38 and the inner electrode 36. The electrical insulator 152 can be in direct physical contact with the outer electrode 38 and / or the inner electrode 36. In addition, the electrical insulator 152 can be positioned over the exposed edges of the outer electrode 38 and the inner electrode 36. Although the electrical insulator 152 is shown positioned over the outer electrode 38 and the inner electrode 36, the electrical insulator 152 can also prevent fluid from forming an electrical path between the outer electrode 38 and the inner electrode 36 by being positioned over the outer electrode 38, as shown in FIGS. 10A and 10B, or by being positioned over the inner electrode 36, as shown in FIGS. 10A and 10B.

[0188] The catheter may also be provided without the disclosed balloon, providing a balloon-less catheter. As a result, the transducer assembly 32 disclosed above need not be surrounded by a balloon. For example, the balloon 14 may be omitted from the catheter depicted in FIGS. 6A-6E, and the catheter may rely on cooling from the blood and / or injecting fluid directly around the transducer electrodes. In some embodiments, a fixation mechanism other than a balloon, such as a basket, may be used to center the catheter / transducer assembly 32. The transducer may be a high-frequency unfocused transducer having an operating frequency between 1 MHz and 20 MHz, e.g., between about 6 MHz and 10 MHz. The generator may deliver sufficiently low power through the wiring to avoid coagulating blood passing through the body cavity while ablating tissue, e.g., nerves, such as renal nerves, hepatic nerves, and pulmonary artery nerves, within or adjacent to a body cavity, e.g., the renal artery, hepatic artery, and pulmonary artery.

[0189] A suitable electronics 22 may include one or more components selected from the group consisting of analog electrical circuits, digital electrical circuits, processors, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), computers, microcomputers, or any combination suitable for performing the above-described operational, monitoring, and control functions. In some examples, the electronics 22 includes an RF electrosurgical generator, such as an electrosurgical unit (ESU), to generate energy for electromagnetic signals output from all or a portion of one or more electrode 76 options. In some examples, the electronics 22 includes a user interface that allows an operator to provide input to and / or retrieve information and / or data from the electronics 22. In some examples, the electronics 22 includes a memory that carries instructions executed by the electronics 22 during the performance of the operational, control, and monitoring functions. While the electronics 22 is illustrated as a single component in a single location, the electronics 22 may include multiple distinct components that are separate from one another and / or located in different locations.

[0190] Other embodiments, combinations, and modifications of the present disclosure will readily occur to those skilled in the art in light of these teachings. Accordingly, the present disclosure is to be limited only by the scope of the following claims, which include all such embodiments and modifications, when viewed in conjunction with the above specification and accompanying drawings.

Claims

1. at least a first transducer (34); A catheter (10) comprising at least a first balloon (14), the first transducer (34) is located inside the first balloon (14), the first transducer (34) is configured to operate at an operating frequency; the first transducer (34) transmits acoustic signals that impart a first acoustic field with multiple lobes along a longitudinal axis of the first transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the first acoustic field; the spatial intensity distribution is on a surface of the first balloon (14) and parallel to a surface of the first transducer (34); the spatial intensity distribution of the first acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the first transducer is less than or equal to 50% of the value of one of the spatial intensity maxima of the first transducer; each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the first transducer; each of the reduced spatial acoustic intensity locations is located on the surface of the first balloon between adjacent spatial intensity maxima along the longitudinal axis of the first transducer; The catheter (10) further comprises: A catheter (10) comprising at least a first electrode (76) configured to transmit an electromagnetic signal, the first electrode (76) being positioned on the first balloon (14) at one of the reduced spatial acoustic intensity positions of the first transducer (34).

2. a backing member (42); 10. The catheter of claim 1, further comprising: at least a second transducer located within the first balloon, the second transducer configured to transmit a second acoustic signal; and the first and second transducers surrounding a backing member having an enhanced flexibility region located between the first and second transducers.

3. 3. The catheter of claim 2, wherein the region of enhanced flexibility is spirally formed around the backing member.

4. 3. The catheter of claim 2, wherein the enhanced flexibility region is an opening extending through the wall of the backing member.

5. 5. The catheter (10) of claim 2, wherein the first and second transducers (34) are separated by a distance sufficient to form lesions at the treatment site that are spaced apart from one another by transmission of the acoustic signals from the first and second transducers (34) to the treatment site.

6. a backing member (42); at least a second transducer (34); and at least a second balloon (14), the second transducer (34) is located inside the second balloon (14); The first and second transducers (34) surround the backing member (42); 2. The catheter of claim 1, wherein the backing member has a first reinforced flexible region located between the first transducer and the second transducer.

7. the second transducer (34) is configured to operate at an operating frequency such that the second transducer (34) transmits acoustic signals that impart a second acoustic field with multiple lobes along the longitudinal axis of the second transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the second acoustic field; the spatial intensity distribution is on the surface of the second balloon (14) and parallel to the surface of the second transducer (34); the spatial intensity distribution of the second acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the second transducer (34) is less than or equal to 50% of the value of one of the spatial intensity maxima of the second transducer (34); each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the second transducer (34); 7. The catheter of claim 6, further comprising at least a second electrode configured to transmit an electromagnetic signal, the second electrode positioned on the second balloon at one of the reduced spatial acoustic intensity locations of the second transducer, and at least one of the first or second electrodes comprising a cylindrical expandable mesh of wires configured to make 360° circumferential electrical contact.

8. Further comprising at least a third balloon (14); 8. The catheter (10) of claim 7, wherein the backing member (42) has a second reinforced flexibility region (114) located between the second balloon and the third balloon (14).

9. further comprising at least a third electrode (76) on said third balloon (14) configured to transmit an electromagnetic signal; the first balloon (14) is located at the proximal end of the catheter (10), the third balloon (14) is located at the distal end of the catheter (10), and the second balloon (14) is located between the first balloon and the third balloon; the first electrode (76) comprises a cylindrical expandable mesh of wires configured to provide 360° circumferential electrical contact; The catheter of claim 8, wherein the third electrode comprises an octagonal star.

10. a third transducer (34) located within the third balloon; the third transducer (34) is configured to operate at an operating frequency such that the third transducer (34) transmits acoustic signals that impart a third acoustic field with multiple lobes along the longitudinal axis of the third transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the third acoustic field; the spatial intensity distribution is on a surface of the third balloon and parallel to a surface of the third transducer (34); the spatial intensity distribution of the third acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the third transducer (34) is less than or equal to 50% of the value of one of the spatial intensity maxima of the third transducer (34); each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the third transducer (34); 10. The catheter (10) of claim 8 or 9, wherein the third electrode (76) is positioned on the third balloon at a reduced spatial acoustic intensity location of the third transducer (34).

11. The catheter (10) of any one of claims 2 to 10, wherein the first and second transducers (34) are configured to operate at different operating frequencies.

12. 12. The catheter of claim 11, wherein the first transducer is configured to operate at an operating frequency of at least 6 MHz and at most 20 MHz, and the second transducer is configured to operate at an operating frequency of at least 20 MHz and at most 60 MHz.

13. 13. The catheter (10) of any one of claims 1, 2, 3, 4, 5, 6, 11 and 12, further comprising at least second and third electrodes (76) on the first balloon (14), the second and third electrodes (76) including an external electrode (76) positioned such that the first transducer (34) is between the second electrode and the third electrode (76) along the longitudinal axis of the first transducer (34).

14. 13. The catheter (10) of any one of claims 1, 2, 3, 4, 5, 6, 11 and 12, further comprising at least a second electrode (76) on the first balloon (14), the second electrode (76) comprising an external electrode (76) positioned such that a line perpendicular to the longitudinal axis of the first transducer (34) can extend through the second electrode (76) without extending through the first transducer (34).

15. 15. The catheter (10) of any one of claims 1 to 14, further comprising a flex circuit on the balloon (14), wherein at least the first electrode (76) is positioned on the flex circuit.

16. 16. The catheter (10) of any one of claims 1 to 15, wherein at least the first electrode (76) is a separate, ring-like, or mesh-like electrode that surrounds the circumference of at least the first balloon (14).

17. 16. A catheter (10) as described in any one of claims 1 to 15, wherein at least the first electrode (76) is positioned above one of the spatial intensity minima of the acoustic field of the first transducer (34).

18. at least a second transducer (34) located within the interior of the first balloon (14) and configured to transmit a second acoustic signal; 18. The catheter (10) of any one of claims 1 and 11 to 17, further comprising at least a second electrode (76), the second electrode (76) being positioned on the first balloon (14) between the first transducer and the second transducer (34) at a position outside the acoustic fields of the first and second transducers (34).

19. the first and second transducers (34) are each configured to operate at an operating frequency such that each of the first and second transducers (34) transmits an acoustic signal that provides a single lobe of acoustic energy; 19. The catheter (10) of any one of claims 2 to 11 and 12 to 18, wherein the operating frequency of the first and second transducers (34) is greater than or equal to 1 MHz and less than or equal to 60 MHz.

20. the first and second transducers (34) are each configured to operate at an operating frequency such that each of the first and second transducers (34) transmits an acoustic signal that provides a single lobe of acoustic energy; 19. The catheter (10) of any one of claims 2 to 11 and 12 to 18, wherein the operating frequency of the first and second transducers (34) is greater than or equal to 1 MHz and less than or equal to 60 MHz.

22. 22. The catheter (10) of any one of claims 2 to 21, wherein the first and second transducers (34) are configured to operate at different operating frequencies.

23. 23. The catheter of claim 22, wherein the first transducer is configured to operate at an operating frequency of at least 6 MHz and at most 20 MHz, and the second transducer is configured to operate at an operating frequency of at least 20 MHz and at most 60 MHz.

24. 1. A method of delivering energy to a treatment site, comprising: advancing the distal end of the catheter (10) to the treatment site within the patient; The catheter (10) has at least a first transducer (34) located within a first balloon (14); operating the first transducer (34) at an operating frequency at which the first transducer (34) transmits an acoustic signal having an acoustic field with multiple lobes along a longitudinal axis of the first transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the acoustic field; the spatial intensity distribution is on the surface of the balloon (14) and parallel to the surface of the first transducer (34); the spatial intensity distribution of the first acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the first transducer is less than or equal to 50% of the value of one of the spatial intensity maxima of the first transducer; each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the first transducer; each of the reduced spatial acoustic intensity locations is on the surface of the first balloon between spatial intensity maxima that are adjacent to each other along the longitudinal axis of the first transducer; and the catheter further comprises at least a first electrode configured to transmit an electromagnetic signal, the first electrode being positioned on the first balloon at one of the reduced spatial acoustic intensity locations of the first transducer.

25. The catheter (10) further comprises at least a second balloon (14) proximal to the first balloon and a second electrode (76) on the second balloon configured to sense neural activity, and the method further comprises: using the first electrode (76) to transmit electromagnetic signals that stimulate nerves in the blood vessel; 25. The method of claim 24, further comprising sensing neural activity in the blood vessel using the second electrode (76).

26. 26. The method of any one of claims 24 or 25, wherein the treatment site is a renal artery.

27. A catheter (10) comprising a transducer (34) located inside a balloon (14), the transducer (34) is configured to operate at an operating frequency that transmits acoustic signals that impart multiple lobes to an acoustic field along a longitudinal axis of the transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the acoustic field; the spatial intensity distribution is at the surface of the balloon (14) and parallel to the surface of the transducer (34); the spatial intensity distribution of the acoustic field has one or more spatial intensity minima; each of the spatial intensity minima is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the transducer; The catheter (10) further comprises: A catheter (10) comprising one or more electrodes (76) configured to transmit electromagnetic signals, each of the one or more electrodes (76) positioned on the balloon (14) and on the transducer (34) at a location above one of the one or more spatial intensity minima.

28. 27. The catheter of claim 26, further comprising outer electrodes positioned such that the transducer is between the outer electrodes along the longitudinal axis of the transducer.

29. 27. The catheter (10) of claim 26, further comprising one or more external electrodes (76) positioned such that a line perpendicular to the longitudinal axis of the transducer (34) can extend through each of the external electrodes (76) without extending through the transducer (34).

30. 30. The catheter (10) of any one of claims 26 to 29, wherein the one or more electrodes (76) comprise a mesh electrode surrounding the circumference of the balloon (14).

31. A catheter (10) as described in any one of claims 26 to 30, wherein the one or more electrodes (76) are positioned so that a line perpendicular to the longitudinal axis of the transducer (34) can pass through the center of gravity of the electrode (76) and one of the one or more spatial intensity minima.

32. a transducer (34) located inside the balloon and configured to transmit an acoustic signal; one or more electrodes (76) positioned on the balloon and configured to transmit electromagnetic signals; A catheter (10), wherein each of the one or more electrodes (76) is positioned on the balloon such that at least a portion of the electrode (76) is positioned beyond the acoustic signal of the transducer (34).

33. 33. The catheter (10) of claim 32, wherein each of the one or more electrodes (76) is positioned on the balloon such that the entire electrode (76) is positioned beyond the acoustic signal of the transducer (34).

34. 34. The catheter (10) of any one of claims 27 to 33, wherein the one or more electrodes (76) are positioned on a flex circuit.

35. 34. The catheter (10) of any one of claims 27 to 33, wherein the one or more electrodes (76) surround the circumference of the balloon.

36. a plurality of transducers (34) located inside the balloon, each transducer (34) configured to transmit an acoustic signal; and one or more electrodes (76) configured to transmit electromagnetic signals, at least a portion of the one or more electrodes (76) positioned on and within the balloon between the transducers (34).

37. Each of the transducers (34) is configured to operate at an operating frequency such that the transducer (34) transmits an acoustic signal that provides a single lobe of acoustic energy; 37. The catheter (10) of claim 36, wherein the operating frequency is between 1 MHz and 20 MHz, inclusive.

38. a catheter (10) comprising a plurality of transducers (34) positioned within a balloon, each of the plurality of transducers (34) configured to transmit an acoustic signal, each of the plurality of transducers (34) configured to transmit an acoustic signal that imparts at least one lobe to an acoustic field along a longitudinal axis of each transducer (34), the at least one lobe having a spatial intensity maximum in a spatial intensity distribution of the acoustic field, the spatial intensity distribution being at a surface of the balloon (14) and parallel to the surface of each of the transducers (34); The catheter (10) further comprises: A catheter (10) comprising one or more electrodes (76) configured to transmit electromagnetic signals, each of the one or more electrodes (76) positioned on the balloon other than at the location of the spatial intensity maximum of at least one lobe of each transducer (34).

39. A catheter (10), comprising: a plurality of transducers (34) positioned within the balloon (14) surrounding the longitudinal axis of the catheter (10), each transducer (34) configured to transmit an acoustic signal; a pair of the transducers (34) are adjacent to each other along the longitudinal axis of the catheter (10), and the pair of transducers (34), each having an end, are arranged so that the ends are adjacent to each other along the longitudinal axis of the catheter (10); A catheter (10) wherein one or both of the transducers (34) in the pair of transducers (34) have a thickness that tapers toward the adjacent ends of the transducers (34).

40. 40. The catheter of claim 39, wherein each of the transducers in the pair of transducers has a thickness that tapers toward the adjacent end of the transducer.

41. 41. A catheter (10) according to claim 39 or 40, wherein the separation distance between the locations where the taper begins at each of the pair of transducers (34) is less than 5 mm.

42. 41. A catheter (10) according to claim 39 or 40, wherein the separation distance between the locations where the taper begins at each of the pair of transducers (34) is less than 3 mm.

43. 43. A catheter (10) as claimed in any one of claims 39 to 42, wherein the taper is configured such that, upon bending of the catheter (10), the adjacent ends are continuously contactable from the inner surface of each transducer (34) to the outer surface of each transducer (34).

44. 44. A catheter (10) as described in any one of claims 39 to 43, wherein the thickness of at least one of the transducers (34) in the pair of transducers (34) tapers at a thickness-to-length ratio greater than 0 and less than 2.

45. 45. A catheter (10) according to any one of claims 39 to 44, wherein the tapered thickness towards the adjacent end of the transducer (34) tapers towards an inner surface of the transducer (34).

46. 46. The catheter (10) of any one of claims 39 to 45, wherein the transducers (34) in the pair of transducers (34) are positioned sufficiently close together so that transmission of an acoustic signal from each of the transducers (34) to a treatment site creates a lesion at the treatment site that fuses in response to conduction of thermal energy within the treatment site.

47. 47. A catheter (10) as described in any one of claims 39 to 46, wherein each of the transducers (34) in the pair of transducers (34) has an active area configured to output a lobe of acoustic energy, and wherein a separation distance between the active areas on the transducers (34) in the pair of transducers (34) is less than 5 mm.

48. a backing member (42); a plurality of transducers (34) surrounding the backing member (42); Each of the transducers (34) is configured to transmit an acoustic signal; The catheter (10) wherein the backing (42) has reinforced flexible regions (114) located between the transducers (34).

49. 49. The catheter (10) of claim 48, wherein the enhanced flexibility region (114) is spirally formed around the backing member (42).

50. 49. The catheter (10) of claim 48, wherein the enhanced flexibility region (114) is an opening extending through the wall of the backing member (42).

51. 41. The catheter (10) of any one of claims 40 to 40, wherein the transducers (34) are separated by a distance sufficient to cause the transmission of acoustic signals from the transducers (34) to the treatment site to form lesions at the treatment site that are spaced apart from one another.

52. a backing member (42); at least first and second balloons (14); at least a first transducer and a second transducer (34) surrounding the backing member (42); the first transducer (34) is located inside the first balloon (14); the second transducer (34) is located inside the second balloon (14); Each of the transducers (34) is configured to transmit an acoustic signal; The catheter (10) wherein the backing (42) has reinforced flexible regions (114) located between the transducers (34).

53. 53. The catheter (10) of claim 52, wherein the catheter (10) is configured to independently inflate and / or deflate the first and second balloons (14).

54. 54. The catheter (10) of claim 52 or 53, wherein the catheter (10) is configured to inflate and / or deflate the first and second balloons (14) substantially simultaneously.

55. 55. The catheter (10) of any one of claims 52 to 54, wherein the first and second balloons (14) have the same or approximately the same level of stiffness.

56. 55. The catheter (10) of any one of claims 52 to 54, wherein the first and second balloons (14) have substantially different levels of stiffness.

57. a catheter (10) shaft, the backing member (42) extending from a distal end of the catheter (10) shaft; 57. The catheter (10) of any one of claims 52 to 56, further comprising a fluid lumen on the shaft that opens into the interior of the first and second balloons (14).

58. A catheter (10) comprising a transducer (34) located inside a balloon, the transducer (34) configured to transmit acoustic signals that impart multiple lobes to an acoustic field along a longitudinal axis of the transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the acoustic field; the spatial intensity distribution is at the surface of the balloon (14) and parallel to the surface of the transducer (34); The catheter (10) further comprises: A catheter (10) comprising one or more electrodes (76) configured to transmit electromagnetic signals, each of the one or more electrodes (76) positioned on the balloon (14) other than at the location of the spatial intensity maximum.

59. the spatial intensity distribution of the acoustic field has one or more spatial intensity minima; each of the spatial intensity minima is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the transducer; 59. The catheter (10) of claim 58, wherein each of the one or more electrodes (76) is positioned on the balloon at a location of the spatial intensity minimum.

60. a transducer (34) located inside the balloon (14) and configured to transmit acoustic signals that impart multiple lobes to the acoustic field; one or more electrodes (76) configured to transmit electromagnetic signals; A catheter (10) wherein each of the one or more electrodes (76) is positioned on the balloon (14) in a location that does not significantly interfere with the acoustic field.

61. The plurality of lobes extend along a longitudinal axis of the first transducer (34); each of the lobes having a spatial intensity maximum in the spatial intensity distribution of the first acoustic field; the spatial intensity distribution is on a surface of the first balloon (14) and parallel to a surface of the first transducer (34); the spatial intensity distribution of the first acoustic field has one or more reduced spatial acoustic intensity locations where the spatial intensity of the acoustic field of the first transducer is less than or equal to 50% of the value of one of the spatial intensity maxima of the first transducer; each of the reduced spatial acoustic intensity locations is between the spatial intensity maxima for adjacent lobes along the longitudinal axis of the first transducer; each of the reduced spatial acoustic intensity locations is located on the surface of the first balloon between adjacent spatial intensity maxima along the longitudinal axis of the first transducer; 61. The catheter (10) of claim 60, wherein at least a first electrode (76) is configured to transmit an electromagnetic signal, and the first electrode (76) is positioned on the first balloon (14) at one of the reduced spatial acoustic intensity positions of the first transducer (34).

62. 62. The catheter (10) of claim 61, wherein the spatial intensity distribution of the first acoustic field has one or more reduced spatial acoustic intensity positions where the spatial intensity of the acoustic field of the first transducer (34) is 25% or less of the value of one of the spatial intensity maxima of the first transducer (34).

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