Transmission of acoustic and electromagnetic signals from a catheter balloon

Abstract

The catheter 10 has at least a first transducer 34 located within at least the first balloon 14 and configured to operate at an operating frequency. The first transducer 34 transmits acoustic signals that impart a first acoustic field with a plurality of 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 being on a surface of the first balloon 14 and parallel to the surface of the first transducer 34, 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 34 is less than or equal to 50% of the value of one of the spatial intensity maxima of the first transducer 34, each of the reduced spatial acoustic intensity locations being between spatial intensity maxima for lobes that are adjacent to one another along the longitudinal axis of the first transducer 34, each of the reduced spatial acoustic intensity locations being on the surface of the first balloon 14 between spatial intensity maxima that are adjacent to one another along the longitudinal axis of the first transducer 34. The catheter 10 further comprises 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.

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 including 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. If 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 well to this treatment. Renal nerve ablation procedures are often ineffective, potentially due to a poor probe-tissue interface. Thus, not a sufficient amount of disruptive means is delivered to the nerve fibers passing along the renal artery. One reason is that the delivery of disruptive means to the arterial wall lacks a feedback mechanism to assess the destruction of neural activity. As a result, not a sufficient amount of disruptive means is delivered and the neural activity is not destroyed. Thus, clinicians need a means to improve the probe / tissue interface or to better target the nerve, as well as a technique to monitor the integrity of the nerve fibers passing through the arterial wall to confirm the destruction of the neural activity before terminating the 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 as to 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 has at least a first transducer located inside 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 a plurality of lobes along a longitudinal axis of the first transducer, each of the lobes 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 a value of one of the spatial intensity maxima of the first transducer, each of the reduced spatial acoustic intensity locations being between spatial intensity maxima for lobes that are adjacent to one another along the longitudinal axis of the first transducer, each of the reduced spatial acoustic intensity locations being on the surface of the first balloon between spatial intensity maxima that are adjacent to one another 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 locations of the first transducer.

[0007] A method of 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 located within a first balloon, the method further comprising operating the first transducer at an operating frequency where the first transducer transmits an acoustic signal having an acoustic field with a plurality of lobes along a longitudinal axis of the first transducer, 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 intensity lobes where the spatial intensity of the acoustic field of the first transducer is less than or equal to 50% of a 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 where the transducer transmits an acoustic signal that provides an acoustic field with multiple lobes along a 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 on a surface of the balloon and parallel to a 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 lobes that are adjacent to one another along the longitudinal axis of the transducer. One or more electrodes are configured to transmit electromagnetic signals, each of the one or more electrodes being 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 is configured to transmit an acoustic signal. The catheter also includes one or more electrodes configured to transmit an electromagnetic signal. At least a portion of the one or more electrodes are positioned on the balloon and between the transducers within the balloon.

[0011] Another embodiment of the catheter has a plurality of transducers located within the 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 the balloon and between the transducers within the balloon.

[0012] Another embodiment of the catheter has a plurality of transducers located inside the 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 an acoustic field with at least one lobe 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 at 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 the location of the spatial intensity maximum of the at least one lobe of each transducer.

[0013] Another embodiment of the catheter has a plurality of transducers located within the balloon such that the transducers surround a longitudinal axis of the catheter. Each of the transducers is configured to transmit an acoustic signal. A pair of transducers are adjacent one another along the longitudinal axis of the catheter, each transducer in the pair having ends disposed such that the ends are adjacent 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 ends of the transducers.

[0014] Another embodiment of the catheter includes a backing member and a plurality of transducers each surrounding the backing member, each of the transducers configured to transmit an acoustic signal, the backing member having an enhanced flexibility region located between the transducers, in some examples the enhanced flexibility region spirals around the backing member. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a side view of the catheter system. [Figure 2A] FIG. 2 illustrates a catheter suitable for use with the catheter system of FIG. 1. 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 modified so that the electrodes are each connected to multiple electrode options, including 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 modified so that the electrodes function as external electrodes positioned approximately coaxially with the transducer, proximal and distal to the transducer along the transducer's longitudinal axis, and so as not to overlap with the transducer or its acoustic signal. [Figure 2H] 2F is 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 such 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 is within the balloon, but the electrodes are not positioned on the balloon. [Figure 2M] 2E is illustrated 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] 1 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 are perspective views of a portion of a catheter shaft, and FIGURE 1B illustrates an example of a catheter construction that can allow for independent inflation and / or deflation of different balloons on the same catheter. [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; FIG. 3B illustrates a portion of the distal end of a catheter shaft; and FIG. 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; FIG. 3B illustrates a portion of the distal end of a catheter shaft; and FIG. 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. 3C 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 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. 2 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. FIGURE 1 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. 2 is a perspective view of a portion of a balloon and a catheter including transducer assemblies connected in parallel. [Figure 6B] 6B illustrates an example of a catheter including multiple transducer assemblies in a balloon. FIG. 6A 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 ends of the transducer. [Figure 6K] 6A to 6E are schematic cross-sections of possible catheter constructions according to FIGS. 6A to 6E. [Figure 7A]1 illustrates an example of an inner catheter; [Figure 7B] 1 illustrates an example 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 a 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 PREFERRED EMBODIMENTS

[0016] The catheter has a transducer located 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 a renal nerve, a hepatic nerve, a pulmonary 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, minimally reduced, the uniformity of the energy delivered across 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 electrical 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 electrical conductors include, but are not limited to, wires, insulated wires, cables, and flexible printed circuits (FPCs). 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, tubes 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, pumps, tanks, reservoirs, and containers. 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, epoxy, etc., mechanical attachment mechanisms such as retainers, locking rings, clamps such as ring clamps or hose clamps, welding such as laser welding, heat welding, etc., 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 configuration of a hollow cylinder having an inner surface and an 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-electro mechanical systems (MEMS) transducers such as piezoelectric micromachined ultrasonic transducers (PMUTs) and capacitive micromachined ultrasonic transducers (CMUTs). Examples of suitable piezoelectrics 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 through which the fluid lumen 40 and the interior of the balloon 14 can exchange fluid. As a result, the fluid lumen 40 and the interior of the balloon 14 are in fluid communication. 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 through the fluid lumen 40 into the interior of the balloon 14 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 option of the fluid lumen 40 and to withdraw fluid from the interior of the balloon 14 through a second option of the fluid lumen 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. The fluid inside the balloon 14 can contact the transducer assembly 32. For example, the fluid can contact the transducer 34, the inner electrode 36, and / or the outer electrode 38. As a result, the fluid can provide cooling for 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 of the pre-cooling fluid include, but are not limited to, temperatures from the freezing temperature of the fluid to room temperature, and / or temperatures equal to or greater than 0° C., 15° C., or 25° C., and / or temperatures less than 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 evident 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. An 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 extends longitudinally through the backing member 42 and can be defined by the electrical insulator 48. The second guidewire lumen 50 is aligned with a guidewire lumen 51 that extends 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, polyimides, 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 the guidewire lumen, the second guidewire lumen 50, and a guidewire positioned in 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 number 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 the 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 amount, 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 the spacing element 54 of FIG. 2B along the longitudinal axis of the backing member 42. The spacing elements 54 can be positioned at or near either end of the 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 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 FIG. 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 a 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 distribution of multiple lobes. The spatial intensity distribution includes spatial intensity peaks (labeled SIp) each associated with one of the different lobes. Each of the spatial intensity peaks 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 includes spatial intensity valleys (labeled SIv) each having a spatial intensity minimum located between adjacent lobes. Thus, each of the spatial intensity minima is associated with a different pair of lobes located adjacent to each other along the longitudinal axis of the transducer. Additionally, each of the spatial intensity minima 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 a pattern of spatial intensity that is parallel to the longitudinal axis and / or surface of the transducer. For example, the line labeled P can represent an example of a spatial intensity distribution of the acoustic field at the surface of the balloon when the balloon is not inflated or when the balloon is in an inflated state. In addition, the spatial intensity shown can represent the distribution when no electrodes are present at the surface of the balloon. Thus, the graph illustrates the distribution of spatial intensity along the longitudinal axis of the transducer 34.

[0040] Without being bound by theory, the 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] A plurality of electrical pathways are located in or on the balloon 14. For example, FIG. 2D illustrates a plurality of electrodes 76 positioned on the balloon 14. The electrodes 76 can surround the balloon 14. One or more of the electrodes 76 can 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 can form a conductive periphery around the balloon 14 such that the entire periphery of the expandable electrode(s) of the balloon 14 can be in circumferential electrical contact with the inner wall of the vessel 360° around the vessel. The balloon 14 can be expanded into apposition with the vessel wall such that the electrodes 76 achieve and maintain intimate contact with the vessel wall despite movements caused by breathing, etc. The use of segmented electrodes 76 that can selectively stimulate dimensions and locations relative to the electrodes controlled by adjusting stimulation parameters for each electrode contact can allow for more selective activation of target structures. In one embodiment, at least one electrode 76 comprises an expandable mesh of wires with 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 pathway includes an electrode interconnect 78 that provides electrical communication between the electrodes 76. In one embodiment, the electrodes 76 include an expandable mesh of wires, all of which may connect to the same electrode interconnect 78, which can improve the signal-to-noise ratio while sensing neural activity. The electrical pathway also includes a pad interconnect 80 that provides electrical communication between a contact pad 82 on the balloon 14 and the electrodes 76 or between the contact pad 82 and the electrode interconnect 78. A conductive component 84 is connected to the contact pad 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 the lobes of the acoustic field. Additionally or alternatively, all or a portion 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 can 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 with respect to the spatial intensity minimum.

[0045] In some examples, all or a portion of the electrodes 76 are each positioned on the surface of the balloon between a pair of reduced spatial acoustic intensity locations. Each pair of reduced spatial acoustic intensity locations is 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 of the reduced spatial acoustic intensity locations labeled RL is 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 of the reduced spatial acoustic intensity locations may be at a location on the surface of the balloon where the spatial intensity of the acoustic field is at a particular intensity threshold relative to a spatial intensity maximum associated with the reduced spatial acoustic intensity location. For example, the intensity threshold for the 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 surface of the balloon where the spatial intensity of the acoustic field is 50% of the value of the spatial intensity maximum for the two spatial intensity maximums labeled y. In other words, the lines labeled L1 and L2 in FIG. 2D indicate locations on the surface of the balloon where the spatial intensity of the acoustic field is 50% of the value of the spatial intensity maximum for the spatial intensity maximum associated with the reduced spatial acoustic intensity location labeled RL. The electrodes labeled El are located between the reduced spatial acoustic intensity locations labeled RL.

[0047] In an embodiment, the acoustic signal emitted from the transducer 34 is not reflected by the electrodes 76, resulting in a more uniform and / or effective treatment of the tissue. In an embodiment, the acoustic signal emitted from the transducer 34 is not significantly reflected by the electrodes 76, resulting in a more uniform and / or effective treatment of the tissue. In an embodiment, 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 a 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 with respect 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 a plurality 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 electrodes is positioned between a pair of reduced spatial acoustic intensity locations that are adjacent to one another 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 located 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 positions of reduced spatial acoustic intensity.

[0051] Since the characteristics of the lobes can vary depending on various variables, the electrodes 76 are positioned such that when the transducer operates 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 the lobes and / or the distance between the spatial intensity minima is labeled d in FIG. The distance between the lobes and / or the distance between the spatial intensity minima (labeled d) may represent the center-to-center distance of the lobes, the center-to-center distance of adjacent electrodes 76, or may represent the distance that 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 between adjacent lobes on the exterior surface of the balloon (denoted as s) can represent the distance between the 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 separation distance between adjacent lobes on the exterior surface of the balloon (denoted as s) is greater than or equal to 0.3 mm and less than 0.9 mm. The electrodes 76 at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minimum, and 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 result in lower contact impedance, increased sensitivity of the electrodes, and improved detection of neural signals. 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, epoxies and rubbers.

[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 dispersive electrodes 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, each electrode 76 option including a single electrode 76. As an example, FIG. 2E illustrates an electrode 76 connected to multiple electrode 76 options, each electrode 76 option including a single electrode 76. The acoustic energy lobes are not shown in FIG. 2E to better illustrate the location of the insulating layer(s) 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 is in 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, respectively.

[0058] An insulating layer 88 is positioned on the balloon 14 over the pad interconnects 80, the contact pads 82, the attachment mechanism, and the conductive components 84. One of the electrodes 76 crosses over one of the pad interconnects 80. The insulating layer 88 is positioned between the electrodes 76 and the underlying pad interconnects 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 FIG. 2D and FIG. 2K can be divided into individual electrodes 76 that allow selective stimulation of the size and position relative to the electrode controlled by adjusting the stimulation parameters for each electrode contact, allowing more selective activation of the target structure. In an embodiment, the individual electrodes 76 are optimized for ablation. The individual electrodes 76 can be square, rectangular, circular, and / or star shaped. The individual electrodes 76 can be located on the balloon 14 such that the nerves of the body cavity can be ablated in a 4-quadrant pattern in a circumferential direction by activating multiple electrodes 76 simultaneously or selectively activating multiple electrodes 76 on the balloon 14 without moving the balloon 14. At least some of the individual electrodes 76 can comprise at least two bipolar electrode pairs offset longitudinally and circumferentially from each other to treat the 4 quadrants of the body cavity, e.g., the renal arteries, while reducing the risk of stenosis of the body cavity. The electrodes 76 can be used to detect apposition with a wall by detecting impedance. If the electrode or electrodes 76 are not in apposition with the wall of the body cavity, the balloon 14 may be further inflated and / or the electrode or electrodes 76 may be deselected.

[0060] In certain embodiments including a transducer 32 within the balloon 14, the electrodes 76 are also positioned such that the electrodes are each located 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.

[0061] For example, FIG. 2F is the catheter of FIG. 2E modified to include a planar electrode 76. Although FIG. 2F depicts a rectangular electrode, square electrodes, circular electrodes, irregular (serpentine) electrodes such as an octagonal star with sharp corners, etc. may be used alternatively or in addition. For example, without limitation, an octagonal star may allow deeper neural stimulation with less power. Additionally, while four electrodes are depicted, the catheter may include more or less ablation and / or neural stimulation and / or neural sensing and / or impedance measurement electrodes. For example, in some embodiments, an array of one to sixteen electrodes, e.g., three, eight, or sixteen. 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 pathway includes 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 about the same location along the longitudinal axis of the transducer (labeled L). 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 between reduced spatial acoustic intensity locations.

[0064] As an alternative 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 above the transducer 34 and is not in the path of the acoustic signal of the transducer 34. As an example, the external electrode 76 is positioned in front of and / or behind the transducer 34 along the longitudinal axis of the transducer 34 and is 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 in which the electrode 76 is 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. Although segmented electrodes are depicted in FIG. 2G, in some 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] The electrodes 76 in Figure 2G are not positioned between adjacent lobes. As a result, the width of the electrodes 76 (labeled W in Figure 2G) 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 transmit 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] FIG. 2G illustrates the overall width of each electrode 76 positioned in front of or behind the transducer 34, but one or more of the outer electrodes may be at a spatial intensity maximum of an adjacent lobe of the acoustic field, for example, at a spatial intensity minimum of an adjacent lobe of the acoustic field, or at a reduced spatial acoustic intensity location, so long as the transducer 34 overlaps with the acoustic signal of the transducer 34.

[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 reduced spatial acoustic intensity locations. 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, to simplify the 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 a plurality of 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] Although FIG. 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] Figures 2F through 2H illustrate electrodes 76 from different electrode 76 options aligned longitudinally on the balloon 14. However, the electrodes 76 from the different electrode 76 options need not be aligned longitudinally on the balloon 14. As an example, Figure 2I illustrates the catheter of Figure 2G modified such that the electrodes 76 from the different electrode 76 options are not aligned longitudinally on the balloon 14.

[0071] Although Figures 2E-2I illustrate an electrode 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 each of the electrode 76 options illustrated in Figures 2F-2I includes multiple electrodes 76, the electrodes 76 can be connected such that each of the electrode 76 options 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] In Figures 2A to 2J, the electrical connections combining the electrodes 76 in the electrode 76 options are provided by electrical pathways on the balloon 14. For example, the 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 the 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 electrode 76 options disclosed above together to form another larger electrode 76 option. Thus, the electrode 76 option can 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 the different electrode 76 options to a common node, the connections can be permanent or temporary. For example, the electronics 22 can include a switch that the electronics 22 can operate to connect the 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 such that an electrode 76 is positioned on the balloon 14, but the transducer assembly 32 is not present within the balloon 14. In some examples, the electrode 76 is 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 electrode 76 on the surface of the balloon 14.

[0074] 2M illustrates the catheter of FIG. 2E modified to include electrodes connected to multiple electrode options, one electrode option including a single circumferential electrode 76 and one electrode option including 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 reduce the risk of narrowing of the body cavity while ablating four quadrants of 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. As an 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 in 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 in the secondary catheter shaft 106. Additionally, one or more of the multiple electrical conductors and / or one or more electrical conductor carriers in the electrical lumen in the catheter shaft 12 can pass through the interiors of the balloons 102, 100, and 104 and into the electrical lumen in 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 each other. When the balloons are constructed to have the same or approximately the same level of stiffness, they will inflate at approximately the same pressure level. As a result, the balloons will inflate simultaneously or substantially simultaneously. However, the balloons can be constructed to have different levels of stiffness. For example, all or a portion of the balloons can be made of different materials and / or have different material thicknesses. A balloon with increased stiffness will inflate at a higher pressure and deflate at a higher pressure. As a result, a balloon(s) with reduced stiffness will inflate faster and deflate 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 may 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) of the balloon 14 can make circumferential electrical contact with the inner wall of the blood vessel 360° around the vessel.

[0079] In some examples, the catheter constructed according to Figures 2A-2O has 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, the catheter is constructed to allow the balloons to be independently inflated and / or deflated. Figures 3A-3G illustrate examples of catheter constructions that can 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, 102 and / or may exclude the transducer assembly 32 within the balloon. Figures 3A-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 in the wall of the catheter shaft 12. In Figure 3A, the location of the fluid port 41 and the conductor port 67 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. The fluid ports 41 are illustrated with dashed lines because they are located behind the balloons or catheter shaft 12. 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 may represent a cross-section through the other balloons (middle balloon 100 and 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 in contact with 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 may be in contact with 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. The first conductor 70 and the second conductor 72 can thus 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 Figures 2A-2N are not shown on the balloon, all or some of the balloons on the catheter may each include zero or one or more electrodes 76 and / or may include zero or 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 and may only include one or more electrodes 76. In some examples, a balloon may include a transducer assembly 32 and not include one or more electrodes 76. For example, the intermediate balloon 100 can exclude an electrode 76 thereon, but 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 and not include a transducer assembly 32 within the intermediate balloon 100, but either or both of 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 an 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 have exited from the fluid lumen 40 labeled A as shown in FIG. 3E. Since the balloon in FIG. 3E is the most proximal of the balloons, more balloons (middle balloon 100 and 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. Thus, the fluid lumens 40 labeled B and C are associated with balloons distal to the proximal balloon 102 illustrated in FIG. 3E balloon, respectively. 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 a first balloon among 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 a second balloon among the balloons located distal to the balloon in FIG. 3E.

[0088] 3A-3G illustrate that the 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 middle 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 middle balloon without transporting fluid into the other balloons. Similarly, the middle 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 middle balloon without transporting fluid from the other balloons.

[0089] 3A-3G illustrate fluid lumens 40 that extend past the associated balloon. 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 that extends past the associated balloon. However, in instances where the fluid lumen 40 does not serve a function past the associated balloon, the fluid lumen can terminate within or proximal to the associated balloon. Terminating one or more fluid lumens before the distal end of the catheter can reduce the diameter of the catheter and provide the catheter with an increasing level of flexibility approaching the distal end of the catheter.

[0090] Although Figures 3A-3G illustrate a single fluid lumen 40 associated with each of the balloons, the catheter can be constructed such that multiple fluid lumens 40 are associated with one or more of the balloons. For example, the catheter of Figures 3A-3G can be constructed with six fluid lumens 40, and each of the balloons can be associated with two of the fluid lumens 40. For example, fluid ports for the two fluid lumens can be located in each balloon. When multiple fluid lumens 40 are associated with a balloon, fluid can be transported through a first option of fluid lumens 40 to inflate the balloon and through a second option of fluid lumens to deflate the balloon. The first option of fluid lumens includes one or more of the fluid lumens, and the second option of fluid lumens includes one or more of the fluid lumens and is different from the first option 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 each 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 transducer assembly 32 in the balloon and / or the transducer in the balloon each have a length of 0.5 mm or more and / or 8 mm or less and a diameter of 3 French or more and 5 French or less.

[0093] The electrical pathways, contact pads 82, and electrodes 76 disclosed in connection with Figures 2A-3G may be conductive traces on the surface of the balloon 14, metal foil attached to the surface of the balloon 14, or a metal layer patterned 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 patterns of metal layers 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-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-3G. In FIG. 4A, the conductive pathways 110 are suitable to function 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. Although the substrate 112 can be moved relative to the balloon, in some examples the flex circuit substrate can be secured onto 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 glues, 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 circumference of the balloon 14 such that opposing edges of the substrate 112 touch or nearly touch one another. 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 such 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 discussed 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 connection 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, the flex circuit can have various 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 multi-layer flex circuit, a rigid flex circuit, or a polymer thick film flex circuit. Many of the flex circuit structures, such as these double-sided flex circuits, can 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 back side of the substrate 112, such that a portion of the conductive pathways 110 is located 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 an example of a double-sided flex circuit suitable for use with a catheter. 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. Additionally, 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 includes or is made of a material that is electrically insulating and / or dielectric. The substrate 112 can be selectively transparent or substantially transparent to the acoustic signal output from the transducer. Additionally or alternatively, the substrate 112 can have an impedance that matches 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 includes or consists of a collection of multiple material members. For example, the layer of porous material can be constructed from and / or consists of one or more material members selected from the group consisting of a collection of fibers, threads, strands, or nanotubes, and combinations thereof. All or a portion of the material members 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 members have a width and / or diameter that is a fraction of the acoustic wavelength of the acoustic field, such as less than 1 / 5 of the acoustic wavelength. Additionally or alternatively, in some examples, all or a portion of the plurality of material members 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 members have a width and / or diameter greater than 5 μm and less than 80 μm. Suitable materials for one or more of the plurality of material members in the porous material and / or layers of the substrate include, but are not limited to, polypropylene, polyethylene, polyurethane, polyether block amide, polyamide, polystyrene, polyimide, open 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 the conductive traces on the surface of the substrate include, but are not limited to, printing and photolithography. Suitable methods for attaching the metal foil to the surface of the substrate include, but are not limited to, adhesive mechanisms such as glue, adhesive, epoxy, and welding such as laser welding and heat welding. Suitable methods for forming the pattern of the 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, the 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 functioning as a conductive pathway 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 functioning as a conductive pathway have a width and / or diameter that is a fraction of the acoustic wavelength of the acoustic field, such as less than 1 / 5 of the acoustic wavelength. Additionally or alternatively, in some examples, all or a portion of the material elements functioning as a conductive pathway have a width and / or diameter that is greater than 0 μm, 10 μm, 50 μm, 80 μm, and / or is less than or equal to 160 μm. In one example, all or a portion of the material features have a width and / or diameter that is 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, attachment of flexible flat cables (FFCs) using painting or printing inks such as silver conductive ink, curing conductive epoxies, flexible printed circuit application techniques, mechanisms such as gluing, epoxidization, 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 body 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 transmit surfaces of the electrodes 76 are each surfaces of the electrodes 76 that are not between the electrode 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 a desired level of electromagnetic energy from the electrode(s) 76 to the perivascular space. However, as discussed above, the fluid within the balloon 14 can provide cooling to the transducer assembly 32. The fluid within 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, the electrodes 76 and / or the electrodes 76 in the electrode 76 options can be constructed to have transmit surface dimensions that enable the electrodes 76 and / or the 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 the transducer assembly 32 and / or transmission of electromagnetic signals from the electrodes 76 and / or the electrodes 76 in the electrode 76 options. In one example, the electrodes 76 and / or the electrodes 76 in the electrode 76 options are constructed to have transmit surface dimensions that enable the electrodes 76 and / or the 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 the transducer assembly 32 and / or transmission of electromagnetic signals from the electrodes 76 and / or the 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 More than and / or 1mm 2, 2.5mm 2 , or 4mm 2 In an example suitable for use when treating the renal arteries, the electrode or electrodes 76 each have a transmitting surface area of ​​1 mm 2 More than 2.5mm 2 It has a transmitting surface area of:

[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 larger and / or wider 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 electrodes located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial sound 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 electrodes can be substantially larger than the electrodes located at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and reduced spatial sound intensity locations. Increasing the size of the outer electrodes results in lower electrical impedance, making the outer electrodes more suitable for use in applications such as neural 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 Over 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 Above 400mm 2 is less than.

[0112] When the catheter includes one or more electrode 76 options including or consisting of external electrodes and including 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 including or consisting of external electrodes to the ratio of the transmit surface area of ​​the electrodes 76 in the electrode 76 options including or consisting 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 pathway is selected to reduce the spatial acoustic intensity between the electrode 76 and the acoustic field. For example, the electrode 76 and / or electrical pathway 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 pathway has a thickness that is a fraction of the acoustic wavelength of the acoustic field, such as less than 1 / 5 of the acoustic wavelength. Additionally or alternatively, in some examples, all or a portion of the electrode 76 and / or electrical pathway has a thickness that is greater than 0 μm, 5 μm, or 20 μm, and / or is less than or equal to 50 μm, 80 μm, 120 μm, or 160 μm. The thickness of the electrode 76 can be greater than one acoustic wavelength, in which case the system can compensate for interruptions of the electrode introduced into the acoustic field. In one example, the electrode 76 and / or all or a portion of the electrical pathway has a thickness that is greater than 5 μm and less than 120 μm.

[0114] In some embodiments, multiple transducer assemblies can be placed on one or more balloons on the catheter. As an example, FIGS. 6A and 6B show an illustration of a catheter including multiple transducer assemblies in a balloon. FIG. 6A is a perspective view of a portion of a catheter including multiple transducer assemblies 32a and 32b in a balloon 14. Although 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 being 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 function 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 most proximal transducer assembly 32a and connects the outer electrode 38a to the generator through a wiring system that extends through the shaft of the catheter. A third conductor 74c extends from the outer electrode 38b of the distal transducer assembly 32b through an opening into the inner lumen of the backing member 42 and into the shaft of the catheter. The conductor 74c connects the outer electrode 38b of the transducer assembly 32b to the generator through a wiring system that extends through the shaft of the catheter.

[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 operate the transducer assemblies 32a and 32b independently 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 allow independent operation of all or different selections of the transducer assemblies.

[0117] Although the conductors 74a, b, c are shown as wires in Figures 6A and 6C, other conductors can be employed. For example, a conductive adhesive can function as one or more of the conductors 74a, b, c. The conductive adhesive can be used with a substrate. For example, the conductive adhesive can have one or more features 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 the third conductor 74c shown in Figure 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 may include one or more enhanced flexibility regions 114. The enhanced flexibility region or regions may be selected to enhance the flexibility of the backing member 42 and, correspondingly, the catheter. For example, a portion of the backing member having an enhanced flexibility region may be more and / or more flexible than one or more portions of the backing member that do not have an enhanced flexibility region.

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

[0120] The reinforced flexibility region 114 illustrated in FIG. 6A is an opening 116 through the wall of the backing member 42. The opening 116 spirals about 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 flexibility 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 instances, the reinforced flexibility region 114 does not extend to any of the transducer assemblies 32 within the balloon.

[0121] The helical 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 helical ratio can determine the degree of flexibility of the flexible reinforcement portion of the backing member 42. For example, increasing the helical ratio can create a more flexible backing member, while decreasing the helical ratio can create a stiffer backing member. Suitable helical ratios (pitch numbers) include, but are not limited to, ratios of 0° / mm or greater and can extend over 360° or greater or 720° or greater.

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

[0123] Although 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 such 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 the different transducer assemblies 32 can be replaced with other conductors. For example, Figures 6D and 6E illustrate the catheter of Figure 6C modified so that the conductive plating 92 provides electrical communication between the external electrodes 38 of the different transducer assemblies 32. Figure 6D is a perspective view of a portion of the catheter including the transducer assembly and balloon. The balloon in Figure 6D is illustrated as transparent so that the underlying components are visible. Figure 6E is a cross-section of the catheter illustrated in Figure 6D taken along the line labeled E in Figure 6D. The conductive plating 92 is in electrical communication with the external electrodes 38 of the different transducer assemblies 32. An electrical insulator 94 is 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 flexibility regions, the bridge portion 113 may include one or more reinforced flexibility 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 the transducers 34 that are adjacent to each other 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 that are positioned adjacent to each other along the longitudinal axis of the catheter. Both of the 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 that 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 benefit of one or more reinforced flexible regions between adjacent transducers 34 can be maintained as the separation between adjacent transducers 34 is reduced. 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, enhancing 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 can have a tapered portion while the ends of the inner and / or outer electrodes exclude the tapered portion as shown in Figure 6H.

[0130] Although 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 such 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 taper 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 be in 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 in 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 the desired characteristics and becomes ineffective or substantially ineffective with respect to the desired treatment. For example, each of the dashed lines labeled AR can mark an 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 area of ​​the transducer assembly 32 and the inactive area of ​​the transducer assembly 32. In many cases, it is desirable for the transducers to be sufficiently close to each other such that the lesions formed by the multiple different transducers can join and / or fuse to form a continuous lesion at the treatment site due to the conduction of thermal energy by 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 by 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 may be designated as L ar The distance labeled L may represent the distance between the beginning of the tapered portion on adjacent transducers. When it is desired for the catheter to form bonded 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 more 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 acoustic energy applied from 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 may be reduced.

[0135] When it is desired that the catheter form lesions that do not bond and / or fuse by conduction of thermal energy, a suitable separation distance (L) between the active areas of adjacent transducer assemblies is selected. ar ) and / or the distance between the start of the taper 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 may 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 ratio of the tapered portion may be expressed as dT / dL. The tapered portion may span all or a portion of the thickness (T) of the transducer. In some examples, the thickness (dT) of the tapered portion spans more than 0%, 30%, and up to 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 examples, adjacent ends of different transducers have the same tapered shape in that the thickness and taper rate are the same in opposite directions and both are straight or both have the same shaped curve and / or curvature.

[0137] 6A-6G illustrate bridge portion 113 with reinforced flexibility regions that do not extend below the transducer assemblies, although all of the portions of bridge portion 113 within the catheter may each include more reinforced flexibility regions that extend below and between one or more transducer assemblies. FIGs. 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 may 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 twenty. 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-6J is shown constructed according to Figures 2A-2C, the transducer assembly 32 can be constructed as disclosed in connection with Figures 3E-3G. When the transducer assembly 32 is constructed as disclosed in connection with Figures 3E-3G, a catheter shaft can be received in a backing member lumen 46 defined by the backing member 42 of the transducer assembly 32 as disclosed in connection with Figures 3A-3G. As a result, the portions 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-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 an 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 within the balloon and / or one or more of the transducers 34 within the balloon 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 transducer assemblies 32 within the balloon and / or the transducers within the balloon 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 6 French or less.

[0141] Although the electrodes 76 disclosed in connection with Figures 2A-2N are not shown on the balloon 14 in Figures 6A-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. In addition, the electronics can operate the one or more electrode 76 selections independently of each other. 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 generate 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 construction 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 be positioned above the spatial intensity minimum that can be output from different transducer assemblies, respectively. 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 a portion of each of the external electrodes may be located on a portion of the catheter that is located outside the overall length (Lc) of the combined transducer assembly 32 within one balloon. For example, the electrode 76 labeled B in FIG. 6K is an external electrode that is 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 may be placed at one or more locations selected from the group consisting of between adjacent lobes, spatial intensity minima, and between reduced spatial acoustic intensity locations.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 signal of the transducers.

[0143] The separation distance between adjacent transducer assemblies 32 is labeled as 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 as 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 to reduce the spatial acoustic intensity between the motion of adjacent transducer assemblies 32. The total length of the combined transducer assemblies 32 in one balloon is labeled as 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 such that the one or more electrodes are received in one of the lumens of the catheter that remain outside the catheter. For example, the internal catheter can be configured such that the one or more electrodes are received in a guidewire lumen of said 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 example 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 a 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 apart along the length of the electrode support 122. The electrode support 122 has an arc shape, with the electrodes positioned along the arc. Although 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 lines. 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 one example, 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 102 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 electrodes are 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 a spiral, the coverage angle can be measured from the spiral axis or twist axis. When the arc is three-dimensional, the coverage angle can be greater than 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 value of the radius of curvature is greater than 1 mm and less than 5 mm, and the minimum value of the radius of curvature is greater than 1 mm and less than 5 mm. The value of the constant radius of curvature, or the values ​​of the maximum and minimum radii of curvature, can be selected to match the body cavity. For example, the value of the constant radius of curvature, or the values ​​of the maximum and minimum radii of curvature can be selected to achieve a desired number of contact points between the electrode 124 and the wall(s) of the body cavity. In examples suitable for use with renal arteries, the constant radius of curvature is greater than 1 mm and less than 5 mm, or the maximum value of the radius of curvature is greater than 1 mm and less than 5 mm, and the minimum value of the 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 the 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 correspondingly 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 and 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 the length of each electrode along the longitudinal axis of the arm being greater than 0.1 mm and the spacing between electrodes 124 along the longitudinal axis of each arm being 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, a length of each electrode along the longitudinal axis of the arm 105 greater than 0.5 mm, and a spacing between the electrodes 124 along the longitudinal axis of each arm 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 elliptical.

[0155] As is evident in FIG. 7A , the electrical cable 126 can extend from a proximal end of the internal catheter shaft 118. The internal catheter shaft 118 can include electrical conductors (not shown) 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 internal 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 internal 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 electrodes selected from the N electrodes and / or to any group of electrodes selected from the N electrodes. Additionally or alternatively, the electronics 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 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, such that the inner catheter shaft remains accessible after the electrode support has been introduced into the body cavity through the catheter shaft 12. In some examples, the inner catheter has an inner catheter shaft 118 that is 1 French or more and / or 6 French or less in diameter 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 is 2 French or more and 5 French or less in diameter 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 artery. As an example, FIG. 8 is a cross-sectional view of a body cavity 128 having multiple nerves on its outer layer. For example, the body cavity 128 of FIG. 8 can represent a blood vessel, such as a renal artery, having nerves 132 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 can be used to assist in placing the catheter in the body cavity 128, as shown in FIG. 8.

[0159] The balloon 14 may 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 about 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 0.1 MHz or more and 20 MHz or less. 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 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., about 2 MHz to 60 MHz, e.g., 20 to 60 MHz, and one or more transducer assemblies including transducers having an operating frequency optimized for ablation, e.g., 1 MHz to 20 MHz, e.g., 6 MHz to 15 MHz, or 6 MHz to 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 up to 20 minutes.

[0163] The electronics 22 can use one or more electrodes 76 on the balloon 14 for one or more different applications. For example, one or more of the electrode 76 options may be operative to generate electromagnetic signals to perform 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 to ablate tissue associated with a body cavity, such as tissue defining the inner surface of the body cavity and / or tissue adjacent or around the body cavity. In some examples, the electronics 22 operates one or more of the electrode 76 options to generate RF signals to ablate nerves associated with a body cavity, such as nerves within the body cavity, nerves within tissue defining the body cavity, and / or nerves adjacent and / or around the body cavity. In one example, one or more electrodes 76 are used to generate RF energy to ablate 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 to ablate sympathetic nerves of the hepatic plexus in the hepatic artery, which is responsible for 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 for the delivery of ablation energy to areas that would otherwise be inaccessible with 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 may 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 allow for more controlled ablation and / or shallower ablation than monopolar electrode 76 embodiments. In some examples, the electronics 22 identifies one or more pairs of electrode 76 options that operate as bipolar electrodes 76 and / or one or more electrode 76 options that 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 that operate as bipolar electrodes 76 and / or one or more electrode 76 options that operate as monopolar electrodes 76 into the electronics 22. In some examples, the one or more pairs of electrode 76 options that operate as bipolar electrodes 76 and / or one or more electrode 76 options that 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 monopolar 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 effect ablation and / or denervation, the electromagnetic signals output from one or more electrodes 76 included in the electrode 76 options can have a frequency of 0 Hz, 2 Hz, 9 Hz, or 100 Hz or more 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 0.5 mAmp or more and / or 10 mAmp or less. 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 an electromagnetic signal to effect ablation and / or denervation, the electromagnetic signal output from one or more electrodes 76 included in the electrode 76 option functioning as the active electrode 76 can have a frequency of 0 Hz, 2 Hz, 9 Hz, or 100 Hz or more 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 0.5 mAmp or more and / or 10 mAmp or less. 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 within a body cavity, within tissue defining a body cavity, within tissue surrounding a body cavity, and / or nerves 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 on October 25, 2021, and entitled "CATHETERS FOR NEURAL MEASUREMENTS AND TREATMENT AND RELATED SYSTEMS AND METHODS," and U.S. Patent Publication No. 20220095979, filed on April 11, 2021, and entitled "INTRALUMINAL MICRONEUROGRAPHY PROBES AND RELATED SYSTEMS AND METHODS," both of which are incorporated by reference in their entireties herein. 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 electrode 76, option one or more of electrode 124, and option one or more of electrode 124 is to stimulate a nerve at a treatment site in a body cavity. For example, another application for option one or more of electrode 76, option one or more of electrode 124, and / or option one or more of electrode 124 is to stimulate a nerve in a renal artery. One example of a suitable method of stimulating a nerve 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 also in U.S. Patent Publication No. 2017 / 0035310, which is incorporated herein in its entirety.

[0171] Another use for the electrode option(s) 76, electrode option(s) 124, and / or electrode option(s) 124 is to measure one or more dimensions and / or characteristics of a body cavity, such as a width and / or cross-sectional area of ​​the body cavity. For example, impedance between the electrodes option 76, between the electrodes 124, and / or between the electrodes option 124 may be measured to aid in measuring the width of the body cavity. The electrode option(s) 76 may additionally or alternatively determine 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 has been implemented in the procedure. Examples of suitable methods for measuring one or more dimensions, characteristics of a body cavity and / or verifying 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 the 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 the 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, the electronics 22 can operate all or a portion of one or more electrode options 76 to image the area of ​​the body cavity where the ablation energy was applied. From the imaging, the electronics 22 and / or the operator can assess the success of the treatment and from that assessment can decide whether to apply additional ablation energy.

[0173] As is apparent from the above, an embodiment of the catheter includes a balloon that encases one or more transducer assemblies and has 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. The 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 of 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 such that the balloon is placed at a second location within the body cavity. The method can then be repeated with the second location as the target location.

[0174] One embodiment of a catheter constructed as disclosed in connection with Figures 2A-6E includes an intermediate balloon 100 between the proximal balloon 102 and the distal balloon 104. In some examples, the catheter is manipulated 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 center the transducer assembly within the body cavity. In some embodiments, one or more electrodes and transducers all generate ablation energy, for example, simultaneously, to aid in a more efficient and rapid denervation procedure.

[0175] An example of a catheter constructed as disclosed in connection with Figures 2A-2M includes an intermediate balloon 100 between a proximal balloon 102 and a distal balloon 104. Figure 2N illustrates an embodiment in which the intermediate balloon 100 includes a transducer assembly and excludes an electrode 76. The proximal balloon 102 and the distal balloon 104 may also include a transducer assembly 32 and one or more electrodes 76. Although Figure 2N illustrates the proximal balloon 102 and the distal balloon 104 each including an individual electrode 76, circumferential rings, segmented electrodes, and / or mesh electrodes may additionally or alternatively be provided to enhance 360° neurosensing and / or neurostimulation around a body lumen, e.g., a renal artery. And, although the intermediate balloon 100 is illustrated as including only a transducer 34, the intermediate balloon 100 may include an electrode 76 or exclude the transducer 34 and include only an electrode 76.

[0176] In one example of manipulating the catheter, the catheter is advanced through the body lumen such that one or more electrodes are positioned to measure neural activity at the target location. The 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 of 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, for example, to move the catheter such 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 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 the 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 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 such that the distal balloon 104 is located at a second location. The method can then be repeated with the second location as the target location.

[0177] When the catheter is used with an internal catheter, the catheter and / or the internal catheter can be delivered to the body cavity using a guide mechanism, such as a guidewire, or a guide catheter. In some examples, the guidewire is advanced through the body to the body cavity, the catheter is advanced over the guidewire to the body cavity, and the guidewire is withdrawn from the body cavity through the catheter and advanced over the internal catheter to the body cavity. In some examples, the catheter is advanced to the body cavity after the internal catheter is advanced to the body cavity. As a result, the catheter can be introduced into the body cavity before the internal catheter. When the catheter is advanced into the body cavity after the internal catheter is 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. The electronics can then operate one or more electrodes on the balloon to measure neural activity at the target location. The neural activity can be measured to determine if treatment is desired at the target location. Suitable methods of 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 a nerve at the target location. The 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. When the catheter is not located in 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 over the inner catheter prior to determination 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, when 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. When 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. Once the electronics determine that the prior ablation was effective or sufficient, the catheter can be configured such that one or more electrodes 124 on the electrode support are placed in a second position. The method can then be repeated with the second location as the location of interest.

[0179] After treatment of the nerve at the target location, when the balloon used to perform the ablation and / or denervation does not include one or more of the electrodes 76, or when it is preferred 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 inner catheter such 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, the cathode can be used to stimulate the nerve being measured. For example, all or some of the electrodes 76 and / or electrodes 102 used to measure neural activity can be used to stimulate the nerve prior to measuring neural activity. The catheter does not need to 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 electrodes 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 identification of the nerve's location. The one or more electrodes used to stimulate the nerve at a location in the body cavity may be the same or different than 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 parts of the electrodes 76 are used to stimulate neural activity, and some of the electrodes 124 are used to sense neural activity, and other parts 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 parts of the electrodes are used to stimulate neural activity at the same time. In these examples, the electrodes used to sense neural activity can be separated by more than 2 mm by the electrodes used to stimulate neural activity to reduce spatial acoustic intensity. The separation can be a product of the selection of electrodes by the electronics or the physical separation of the electronics on the electrode support or on the 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 the method of operating the catheter and / or internal catheter includes one or more operations in which a treatment site in 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 of the paired electrode 76 options as bipolar electrodes 76. Alternatively, the electronics 22 can operate one or more of the electrode 76 options as monopolar options. In addition, the electromagnetic signal and the acoustic signal can alternate in sequence without overlapping the delivery of the electromagnetic signal and the acoustic signal. Alternatively, the electromagnetic signal and the acoustic signal can be applied simultaneously. A high 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 the simultaneous application of the electromagnetic signal and the 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 that extends into the transducer 34. The recess 150 may extend through the external electrode 38 as shown in FIG. 9. Thus, 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 deep enough so that the electrical conductors do not leave the transducer 34 and / or the external electrode 38. Thus, the electrical conductors may be located at or below the level of the outer surface of the transducer 34 and / or the external electrode 38. Although the recess 150 is not shown extending around the axis of the transducer, the recess 150 can surround the axis of the transducer.

[0187] The transducer assembly described above may also include optional insulation. For example, when a transducer assembly such as the transducer assembly 32 described above in 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 pathway 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 is 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 prevent fluid from forming an electrical pathway between the outer electrode 38 and the inner electrode 36 by being positioned over the outer electrode 38, as shown in Figures 10A and 10B, or by being positioned over the inner electrode 36, as shown in Figures 10A and 10B.

[0188] The catheter may also exclude the disclosed balloon to provide 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 Figures 6A-6E and the catheter may rely on cooling from the blood and / or injecting fluid directly around the electrodes of the transducer. 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, such as between about 6 MHz and 10 MHz. The generator may deliver low enough power through the wiring to avoid coagulating blood passing through the body cavity while ablating tissue, such as nerves, such as renal nerves, hepatic nerves, pulmonary nerves, etc., in or adjacent to a body cavity, such as the renal artery, hepatic artery, pulmonary artery, etc.

[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 operation, monitoring, and control functions described above. In some examples, the electronics 22 includes an RF electrosurgical generator, such as an electrosurgical unit (ESU), to generate energy in the electromagnetic signals output from all or a portion of the one or more electrode 76 options. In some examples, the electronics 22 includes a user interface that allows an operator to provide input to the electronics 22 and / or extract 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 operation, control, and monitoring functions. Although the electronics 22 is illustrated as a single component in a single location, the electronics 22 may include multiple different components that are separate from one another and / or located in different locations.

[0190] Other embodiments, combinations, and modifications of the present disclosure will occur readily to those of ordinary skill 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 within the first balloon (14), the first transducer (34) being configured to operate at an operating frequency; the first transducer (34) transmits an acoustic signal that imparts 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 (34) is less than or equal to 50% of the value of one of the spatial intensity maxima of the first 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 first transducer; each of the reduced spatial acoustic intensity locations is 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 locations of the first transducer (34).

2. A backing member (42); 2. 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, the first and second transducers surrounding a backing member having an enhanced flexibility region located between the first and second transducers.

3. The catheter (10) of claim 2, wherein the region of enhanced flexibility (114) is spirally formed around the backing member (42).

4. The catheter (10) of claim 2, wherein the enhanced flexibility region (114) is an opening extending through a wall of the backing member (42).

5. 5. The catheter of claim 2, wherein the first and second transducers are separated by a distance sufficient to create lesions at the treatment site that are spaced apart from one another upon transmission of the acoustic signals from the first and second transducers 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 region of enhanced flexibility 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 a surface of the second balloon (14) and parallel to a 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; 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 (42) has a second enhanced flexibility region (114) located between the second balloon and the third balloon (14).

9. and 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 a proximal end of the catheter (10), the third balloon (14) is located at a 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; 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 greater than or equal to 6 MHz and less than or equal to 20 MHz, and the second transducer is configured to operate at an operating frequency of greater than or equal to 20 MHz and less than or equal to 60 MHz.

13. The catheter (10) of any one of claims 1 to 4 and 6, 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. The catheter (10) of any one of claims 1 to 4 and 6, 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 a longitudinal axis of the first transducer (34) can extend through the second electrode (76) without extending through the first transducer (34).

15. The catheter (10) of any one of claims 1 and 6-9, further comprising a flex circuit on the balloon (14), and at least the first electrode (76) being positioned on the flex circuit.

16. The catheter (10) of any one of claims 1 to 4 and 6 to 9, wherein at least the first electrode (76) is a separate, ring-like, or mesh-like electrode that surrounds at least the circumference of the first balloon (14).

17. A catheter (10) as described in any one of claims 1 to 4 and 6 to 9, wherein at least the first electrode (76) is positioned at a position 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; 2. The catheter (10) of claim 1, further comprising at least a second electrode (76), the second electrode (76) positioned on the first balloon (14) between the first transducer (34) and the second transducer (34) at a location 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; The catheter (10) of any one of claims 2 to 4, 6 to 9 and 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; The catheter (10) of any one of claims 2-4, 6-9, 12 and 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.

21. The catheter (10) of any one of claims 2, 4, 6-9 and 18, wherein the first and second transducers (34) are configured to operate at different operating frequencies.

22. 22. The catheter of claim 21, wherein the first transducer is configured to operate at an operating frequency of greater than or equal to 6 MHz and less than or equal to 20 MHz, and the second transducer is configured to operate at an operating frequency of greater than or equal to 20 MHz and less than or equal to 60 MHz.

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