Selectively insulated ultrasonic transducer

Abstract

Disclosed herein are ultrasonic transducers that are selectively insulated to thereby enable the transducers to be exposed to electrically conductive fluids without causing a short between electrodes of the transducers. Such transducers include a piezoelectric transducer body having a first surface and a second surface that are spaced apart from and do not intersect each other. The ultrasonic transducers also include a first electrode disposed on the first surface, a second electrode disposed on the second surface, and an electrical insulator covering only one of the first and second electrodes and configured to prevent electrical conduction between the first and second electrodes when the ultrasonic transducer is placed within an electrically conductive fluid. Devices and systems including such transducers are also disclosed. Related methods are also disclosed herein.

Description

[0001] priority

[0002] This application claims priority to U.S. Patent Application No. 17 / 457,997, entitled “Selectively Insulated Ultrasonic Transducers,” filed December 7, 2021, by Thirumalai et al., and U.S. Provisional Patent Application No. 63 / 151,514, entitled “Selectively Insulated Ultrasonic Transducers,” filed February 19, 2021, by Thirumalai et al. Technical Field

[0003] This application generally relates to minimally invasive devices, systems, and methods for delivering energy to a target anatomical site of an individual, and more specifically, to catheter-based intraluminal devices, systems, and methods that include or utilize an ultrasound transducer configured to emit ultrasound energy for the treatment of tissues, such as nerve tissue. Background Technology

[0004] 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, high blood pressure can lead to kidney disease, arrhythmias, and heart failure. In recent years, treatment for hypertension has focused on interventional methods that deactivate the renal nerves surrounding the renal arteries. The autonomic nervous system tends to follow blood vessels to organs where the autonomic nervous system is weakened. Catheters can reach specific structures within the lumen through which the catheter travels. For example, one system uses a radiofrequency (RF) generator connected to a catheter with multiple electrodes positioned against the intima of the renal artery to generate an electric field in the vessel wall and surrounding tissue. This field causes the tissue to be resistively (ohmetically) heated to a temperature sufficient to ablate the tissue and the renal nerves passing through it. To treat all the renal nerves surrounding the renal artery, the RF electrodes are repositioned several times around the interior of the renal artery. However, the relatively limited electric field generated by the RF electrodes may miss some renal nerves, resulting in incomplete treatment. In addition, in order to heat the renal nerve, the RF electrode must come into contact with the vascular endothelium, which carries the risk of endothelial damage or necrosis, which may lead to thrombosis, vascular wall fibrosis, mechanical weakening of the blood vessel, and possible vascular dissection.

[0005] Another method for achieving renal nerve deactivation is the use of high-intensity focused ultrasound (HIFU), which relies on vibrational energy to induce frictional heating and rupture of the tissue, thereby raising the tissue temperature sufficiently to cause ablation or remodeling. However, intravascular HIFU may at most create a thin focal ring in the vessel and surrounding tissue. If applied to renal denervation, it will be difficult to align this thin ring with the renal nerve because the renal nerve is at a different radial distance along the length of the renal artery. Another problem is that the thin focal ring results in a smaller longitudinal treatment area relative to the vessel axis.

[0006] The entire contents of each of these U.S. Patents, Nos. 9,943,666, 9,981,108, and 10,039,901 of Warnking, Nos. 9,700,372, 9,707,034, and 10,368,944 of Schaer, and Nos. 10,350,440 and 10,456,605 of Taylor, address many of the disadvantages of RF and HIFU systems, such as those described above. Example embodiments of these systems include an ultrasound transducer positioned along the distal end of a catheter designed for insertion into a blood vessel (e.g., a renal artery). The ultrasound transducer emits one or more therapeutic doses of non-focused ultrasound energy that heat tissue adjacent to a body cavity in which the transducer is housed. Such non-focused ultrasound can ablate target nerves around the body cavity, for example, without damaging non-target tissues, such as the lining of the body cavity or unintended organs outside the body cavity. The system may include a balloon mounted at the distal end of a catheter, the balloon being designed to cool the blood vessel when cooling fluid is delivered to the balloon. This design can create one or more ablation zones sufficient to achieve long-term neural inactivation at different locations around the circumference of the blood vessel.

[0007] An ultrasonic transducer may include a first electrode and a second electrode disposed on either side of a cylindrical piezoelectric material, such as lead zirconate titanate (PZT). To power the transducer, a voltage is applied across the first and second electrodes at a selected frequency chosen to resonate the piezoelectric material, thereby generating vibrational energy emitted radially outward from the transducer. The transducer is designed to provide a generally uniform and predictable emission profile to prevent damage to surrounding non-target tissues. Additionally, a cooling fluid circulates through the balloon before, during, and after transducer activation to reduce heating of the body cavity lining. In this way, the peak temperature achieved by the tissue within the cooling zone remains lower than the peak temperature for tissue located outside the cooling zone.

[0008] It is necessary to prevent electrical short circuits that could occur between the electrodes of the ultrasound transducer via fluid. One way to prevent such short circuits is to use a non-conductive cooling fluid, such as deionized water with sufficiently low conductivity, within the balloon. However, greater flexibility in the choice of the type of cooling fluid used within the balloon would be required. Additionally, it may be necessary to use the ultrasound transducer without a balloon, in which case the transducer can be directly inserted into a body cavity through which conductive blood flows. In such procedures, it will be necessary to prevent electrical short circuits between the electrodes of the ultrasound transducer caused by conductive blood. Summary of the Invention

[0009] This document discloses various ultrasound transducers in which only one of the electrodes is covered by an electrical insulator to prevent electrical short circuits between the electrodes via a conductive fluid, such as a cooling fluid within a balloon or blood when the transducer is directly inserted into a body cavity through which conductive blood flows. Such ultrasound transducers may be referred to herein as selectively insulated transducers or partially insulated transducers, or more simply as transducers. This document also discloses ultrasound-based tissue therapy devices and systems with selectively insulated transducers. The system is catheter-based and can be delivered within a lumen (e.g., within a blood vessel) to place the selectively insulated transducer within a suitable body cavity, such as a blood vessel, for example, a renal artery. The selectively insulated transducer can be activated to deliver non-focused ultrasound energy radially outward for neuromodulation of tissues within a target anatomical region, and thus for the treatment of conditions such as hypertension. Additionally, the selectively insulated transducer can be placed within a balloon filled with cooling fluid before and during treatment. A cooling fluid can be used to remove heat from the ultrasonic transducer and surrounding tissue during use. In such embodiments, the cooling fluid may be conductive.

[0010] According to certain embodiments of the present invention, an ultrasonic transducer includes a piezoelectric transducer body having a first surface and a second surface spaced apart from each other and not intersecting. The ultrasonic transducer further includes: a first electrode disposed on the first surface; a second electrode disposed on the second surface; and an electrical insulator directly or indirectly covering the first electrode. The second electrode is not covered by the electrical insulator and is thereby configured to contact the conductive fluid when the ultrasonic transducer is placed in a conductive fluid.

[0011] According to certain embodiments of the invention, an electrical insulator covers the first electrode and is configured to prevent the first electrode from contacting the conductive fluid when the ultrasonic transducer is placed in the conductive fluid, thereby preventing electrical conduction between the first electrode and the second electrode when the ultrasonic transducer is placed in the conductive fluid. In such embodiments, the second electrode is not covered by an electrical insulator. Because the second electrode is not covered by an electrical insulator, it will contact the conductive fluid when the ultrasonic transducer is placed in the conductive fluid.

[0012] According to certain embodiments of the invention, the piezoelectric transducer body is configured to generate ultrasonic waves in response to a voltage applied between the first and second electrodes (also referred to as applying a voltage between the first and second electrodes). In such embodiments, an electrical insulator covering the first electrode is configured to prevent, and preferably prevent, a short circuit between the first and second electrodes when the ultrasonic transducer is placed in a conductive fluid and a voltage is applied between the first and second electrodes.

[0013] According to certain embodiments of the present invention, a piezoelectric transducer body includes a hollow tube of piezoelectric material having an inner surface and an outer surface, the inner surface being one of a first surface and a second surface of the piezoelectric transducer body, and the outer surface being the other of the first surface and the second surface of the piezoelectric transducer body. In some such embodiments, a first electrode is disposed on one of the inner surface and the outer surface of the piezoelectric material hollow tube, and a second electrode is disposed on the other of the inner surface and the outer surface of the piezoelectric material hollow tube. According to certain embodiments of the present invention, the piezoelectric material hollow tube is cylindrical, such that it has a circular radial cross-section. In alternative specific embodiments, the piezoelectric material hollow tube may have other shapes besides a cylindrical shape with a circular cross-section. Other cross-sectional shapes of the piezoelectric material hollow tube, and more generally other cross-sectional shapes of the piezoelectric transducer body, include, but are not limited to, oval or elliptical cross-sections, square or rectangular cross-sections, pentagonal cross-sections, hexagonal cross-sections, heptagonal cross-sections, octagonal cross-sections, and / or similar shapes. In other embodiments, the piezoelectric transducer body is not hollow; for example, the piezoelectric transducer body may have a generally solid rectangular shape, or some other solid shape. For instance, the piezoelectric transducer body may be a solid piezoelectric transducer body.

[0014] According to certain embodiments of the present invention, the piezoelectric transducer body is configured to transmit acoustic energy in the frequency range of 8.5 MHz to 9.5 MHz.

[0015] According to certain embodiments of the invention, the piezoelectric transducer body is configured to generate an acoustic output power in the range of 5 watts to 45 watts in response to an input electrical power in the range of 10 watts to 80 watts.

[0016] According to certain embodiments of the invention, when the ultrasonic transducer is positioned in a conductive fluid, an electrical insulator covering the first electrode prevents (and preferably prevents) the first electrode from contacting the conductive fluid. In such embodiments, the electrical insulator does not cover the second electrode, and therefore, when the ultrasonic transducer is positioned in the conductive fluid, the second electrode will contact the conductive fluid. In other words, only one of the first and second electrodes is covered by an electrical insulator.

[0017] In this embodiment, the conductive fluid includes one of blood, saline, non-pure water, or sodium lactate solution. Therefore, in this embodiment, the conductive fluid is selected from the group consisting of blood, saline, non-pure water, sodium lactate solution, and combinations thereof.

[0018] In one embodiment, the first electrode includes a main peripheral surface and a longitudinal end. In this type of embodiment, a portion of the electrical insulator covers the main peripheral surface of the first electrode and is made of a first type of electrical insulating material. In this embodiment, another portion or the remainder of the electrical insulator covers the longitudinal end of the first electrode and is made of a first type of electrical insulating material or a second different type of electrical insulating material.

[0019] According to certain embodiments of the invention, an ultrasonic transducer is configured to be placed within a balloon at least partially filled with a conductive fluid used to cool portions of a body cavity in which the ultrasonic transducer can be positioned. The cooling fluid can also be used to cool the transducer, which is positioned together with the balloon. In some such embodiments, the conductive fluid used to at least partially fill the balloon includes at least one of saline, non-pure water, or a sodium lactate solution. Thus, in such embodiments, the conductive fluid is selected from the group consisting of saline, non-pure water, sodium lactate solution, and combinations thereof. The use of other conductive fluids is also possible and is within the scope of the embodiments described herein.

[0020] According to certain embodiments of the invention, which may be referred to as balloon-free embodiments, the ultrasonic transducer is configured to be directly exposed to blood flowing through a body cavity in which the ultrasonic transducer can be positioned. In such embodiments, the conductive fluid includes or is blood.

[0021] According to certain embodiments of the present invention, the electrical insulator comprises parylene. Alternative or additional materials may be used to provide the electrical insulator, such as, but not limited to, cyanoacetate, epoxy resin, nylon, polytetrafluoroethylene (PTFE), polyimide, polyethylene, polyethylene terephthalate, polyvinyl chloride (PVC), and synthetic diamond coating, or combinations thereof. For example, in one embodiment, the electrical insulator comprises parylene disposed on and covering the outer circumference of the first electrode and epoxy resin disposed on and covering the longitudinal end of the first electrode. In another embodiment, the electrical insulator is composed of parylene.

[0022] In one embodiment, the ultrasonic transducer further includes a cable that contacts and is configured to provide power to the first electrode. In this embodiment, an electrical insulator covers both the peripheral surface of the first electrode and the contact point between the cable and the first electrode.

[0023] In a particular embodiment, the electrical insulator includes a first insulator disposed on a first electrode and a second insulator disposed on a contact, the second insulator being the same as or different from the first insulator.

[0024] The above embodiments of the combinable ultrasonic transducer.

[0025] Some embodiments of the present invention relate to a device comprising: a balloon configured to receive cooling fluid; and an ultrasonic transducer disposed within the balloon. In some such embodiments, the ultrasonic transducer comprises a hollow tube of piezoelectric material having an inner surface and an outer surface. A first electrode is disposed on one of the inner and outer surfaces of the piezoelectric material hollow tube. A second electrode is disposed on the other of the inner and outer surfaces of the piezoelectric material hollow tube. An electrical insulator covers the first electrode and is configured to prevent the first electrode from contacting the cooling fluid received by the balloon. Therefore, in this embodiment, the electrical insulator is configured to prevent electrical conduction between the first and second electrodes.

[0026] In this embodiment, the piezoelectric hollow tube is a cylindrical piezoelectric hollow tube.

[0027] In embodiments, the conductive cooling fluid may include, but is not limited to, at least one of brine, non-pure water, or sodium lactate solution. Therefore, in embodiments, the conductive cooling fluid is selected from the group consisting of brine, non-pure water, sodium lactate solution, and combinations thereof.

[0028] In some embodiments, the first electrode (covered by an electrical insulator) is disposed on the outer surface of a hollow tube of piezoelectric material. In other embodiments, the first electrode (covered by an electrical insulator) is disposed on the inner surface of a hollow tube of piezoelectric material. In some such embodiments, the second electrode is not covered by an electrical insulator and is therefore in contact with the cooling fluid contained in the balloon.

[0029] According to certain embodiments of the invention, the device further includes a controller configured to apply a voltage between the first and second electrodes, thereby causing the ultrasonic transducer to generate ultrasonic waves. In such embodiments, when the cooling fluid housed within the balloon is a conductive cooling fluid and a voltage is applied between the first and second electrodes by the controller, an electrical insulator prevents (and preferably prevents) a short circuit between the first and second electrodes. In some such embodiments, the first electrode is an external electrode. In other embodiments, the first electrode is an internal electrode.

[0030] In embodiments, the electrical insulator includes one or more of the following: parylene, cyanoacetate, epoxy resin, nylon, polytetrafluoroethylene (PTFE), polyimide, polyethylene, polyethylene terephthalate, polyvinyl chloride (PVC), and synthetic diamond coating.

[0031] According to certain embodiments of the present invention, a method includes providing an ultrasonic transducer having a first surface and a second surface spaced apart from each other and not intersecting, wherein a first electrode is disposed on the first surface and a second electrode is disposed on the second surface. The method further includes: covering only one of the first electrode and the second electrode with an electrical insulator; and exposing the ultrasonic transducer to a conductive fluid, the conductive fluid contacting the second electrode and being prevented from contacting the first electrode by the insulator covering the first electrode. Additionally, when the ultrasonic transducer is exposed to the conductive fluid, the method includes applying a voltage between the first and second electrodes to thereby cause the ultrasonic transducer to generate ultrasonic waves. The method further includes: when the ultrasonic transducer is exposed to the conductive fluid and a voltage is applied between the first and second electrodes, preventing a short circuit between the first and second electrodes using an electrical insulator. The aforementioned conductive fluid may include, but is not limited to, at least one of saline, non-pure water, or a sodium lactate solution. Alternatively, the aforementioned conductive fluid may be blood flowing through a body cavity.

[0032] According to some embodiments, the method further includes placing an ultrasonic transducer inside a balloon. In such embodiments, the step of exposing the ultrasonic transducer to a conductive fluid includes filling the balloon at least partially with the conductive fluid. Such methods may also include inserting the balloon, in which the ultrasonic transducer is located, into a body cavity. In such embodiments, while the balloon is within the body cavity, a step occurs where a voltage is applied between a first electrode and a second electrode to thereby cause the ultrasonic transducer to generate ultrasonic waves.

[0033] According to an alternative embodiment, which may be referred to as a balloon-free embodiment, the method further includes inserting an ultrasound transducer into a body cavity through which blood flows, such that the ultrasound transducer comes into contact with the blood. In such embodiments, the conductive fluid includes blood, and the step of exposing the ultrasound transducer to the conductive fluid includes exposing the ultrasound transducer to the blood.

[0034] According to certain principles of the invention, conductive cooling fluids such as saline or sodium lactate solutions can be used with selectively insulating transducers. Saline and sodium lactate solutions are readily available in all hospitals and other treatment centers, thus enhancing the ease of integrating the system of the invention into the surgical environment. Therefore, the selectively insulating transducer may include an electrical insulator covering one of the internal or external electrodes of the insulating transducer, which prevents short circuits between the electrodes of the transducer caused by the conductive fluid within the balloon. Specifically, in the absence of an electrical insulator, if the balloon is filled with conductive fluid, applying a voltage across the internal and external electrodes may cause an electrical short circuit, which would prevent the ultrasonic material of the transducer from generating ultrasound with the desired output power.

[0035] This summary is not intended to be a complete description of the embodiments of the present invention. Other features and advantages of the embodiments of the present invention will become apparent from the following detailed description, in which preferred embodiments have been set forth in detail with reference to the accompanying drawings and claims. Attached Figure Description

[0036] Various features and implementations thereof of this disclosure will be described in more detail with reference to the following detailed description, claims and drawings, wherein reference numerals are repeated where appropriate to indicate correspondences between referenced items, and wherein:

[0037] Figure 1 Selected components of an ultrasound-based tissue therapy system according to certain embodiments of the present invention are shown.

[0038] Figure 2A Show Figure 1 A side view of selected components of the ultrasound-based tissue therapy system described in the article.

[0039] Figure 2B Perspective view showing additional selected components of an ultrasound-based tissue therapy system inserted into a body cavity according to various configurations provided herein.

[0040] Figure 2C A longitudinal cross-sectional view of the distal portion of a catheter in an ultrasound-based tissue therapy system according to an embodiment of the present invention is shown.

[0041] Figure 3A1 The guide shaft according to an embodiment is shown along Figure 2C The cross-sectional view of line AA in the diagram.

[0042] Figure 3A2 The guide shaft according to an alternative embodiment is shown along... Figure 2C The cross-sectional view of line AA in the diagram.

[0043] Figure 3BShow along Figure 2C A cross-sectional view of the section of the ultrasonic transducer that the line BB crosses across the duct.

[0044] Figure 4A This is a side view of the distal portion of a catheter in an ultrasound-based tissue therapy system containing a selectively insulating transducer, according to certain embodiments of the present invention.

[0045] Figure 4B This is a perspective view of a selectively insulated transducer according to certain embodiments of the present invention, wherein the external electrodes of the piezoelectric transducer are covered by an electrical insulator.

[0046] Figure 4C Show Figure 4A and 4B The longitudinal cross-sectional view of the selectively insulating transducer described in the article.

[0047] Figure 4D Show Figure 4A and 4B The radial cross-sectional view of the selectively insulating transducer described in the article.

[0048] Figure 5A A longitudinal cross-sectional view of a selectively insulating transducer according to another embodiment of the present invention is shown, wherein the internal electrodes of the piezoelectric transducer are covered by an electrical insulator.

[0049] Figure 5B Show Figure 5A The radial cross-sectional view of the selectively insulated transducer described in the figure shows that the internal electrodes of the piezoelectric transducer are covered by an electrical insulator.

[0050] Figure 6A A longitudinal cross-sectional view of the transducer is shown, in which the interior of the piezoelectric transducer and the electrodes are both covered by an electrical insulator.

[0051] Figure 6B Show Figure 6A The radial cross-sectional view of the transducer described in the article shows that the interior of the piezoelectric transducer and the electrodes are both covered by an electrical insulator.

[0052] Figure 7 The graph shows the input electrical power versus acoustic output electrical power for a piezoelectric transducer, illustrating how insulating various electrodes or combinations thereof affects the transducer's performance.

[0053] Figure 8A A perspective view of an alternative configuration of a piezoelectric transducer is shown, wherein the transducer body is rectangular and the transducer electrodes are planar.

[0054] Figure 8B Show Figure 8A The cross-sectional diagram of the piezoelectric transducer described in the article.

[0055] Figure 9 A cross-sectional view of a selectively insulating transducer according to another embodiment of the present invention is shown.

[0056] Figure 10 A cross-sectional view of a selectively insulating transducer according to another embodiment of the present invention is shown.

[0057] Figure 11 This is a high-level flowchart used to outline various embodiments of the methods according to the present invention. Detailed Implementation

[0058] This document provides acoustic-based transducers, devices, and systems for tissue therapy. Preferably, the system is catheter-based and can be delivered within a lumen (e.g., within a blood vessel) to place the transducer within a target anatomical region of an individual, such as within a suitable body cavity, for example, a blood vessel. Once properly positioned within the target anatomical region, the transducer can be activated to deliver non-focused ultrasound energy radially outward to appropriately heat and thus treat the tissue within the target anatomical region. The transducer can be adapted to be activated at frequencies, times, and energy levels suitable for treating the target tissue. In a non-limiting example, the non-focused ultrasound energy generated by the transducer can target selected neural tissue of an individual and can be heated in a manner that facilitates neuromodulation of the neural tissue (e.g., complete or partial ablation, necrosis, or stimulation). Neuromodulation of renal nerves, as described in, for example, the patents of Warnkin, Shire, and Taylor mentioned above, can be used to treat a variety of conditions, such as hypertension, chronic kidney disease, atrial fibrillation, arrhythmia, heart failure, chronic kidney disease, end-stage renal disease, myocardial infarction, anxiety, contrast-induced nephropathy, diabetes, metabolic disorders, and insulin resistance. However, it should be understood that the transducer can be suitably used to treat other nerves and conditions, such as the sympathetic nerves of the hepatic plexus within the hepatic artery responsible for blood glucose levels important for the treatment of diabetes, or to treat any suitable tissue, such as cardiac tissue that triggers abnormal heart rhythms, and is not limited to the treatment (e.g., neuromodulation) of renal nerve tissue.

[0059] In endoluminal systems, the ultrasound transducer may be placed within a balloon filled with cooling fluid before and during treatment. Alternatively, in embodiments that may be referred to as balloon-free embodiments, the ultrasound transducer may be directly exposed to blood flow without a surrounding balloon.

[0060] Overview of system components and features

[0061] Figure 1 , 2A Figures 2B and 2B illustrate the features of an ultrasound-based tissue therapy system 100 according to the various configurations provided herein. First, refer to... Figure 1System 100 is shown to include a catheter 102, a controller 120, and a connecting cable 140. In some embodiments, system 100 further includes an ultrasonic transducer 111, a reservoir 110, a tube 130, and a control mechanism, such as a handheld remote control, within a balloon 112. In some embodiments, which may be referred to as "balloon-free" embodiments, system 100 does not include a balloon 112. In some such balloon-free embodiments, system 100 also does not include the reservoir 110 and the tube 130. In some other balloon-free embodiments, system 100 does include the reservoir 110 and / or the tube 130.

[0062] exist Figure 1 In the embodiments shown, the controller 120 is depicted connected to the conduit 102 via a cylinder 130 and a connecting cable 140. In some embodiments, the controller 120 interfaces with the cylinder 130 to provide cooling fluid to the conduit 102 to selectively inflate and deflate the balloon 112. The balloon 112 may be made of, for example, nylon, a polyimide membrane, or a thermoplastic elastomer (e.g., branded PEBAX). TM Marked thermoplastic elastomers), medical-grade thermoplastic polyurethane elastomers (e.g., those under the trademark PELLETHANE) TM The products sold are made from thermoplastic polyurethane elastomers, pellethane, isothane, or other suitable polymers or any combination thereof, but are not limited thereto.

[0063] Now see Figure 2A The catheter 102 includes a distal portion 210 and a proximal portion 220. The catheter 102 includes a catheter shaft 214, which may include one or more lumens extending therethrough. As an example, the catheter shaft 214 includes a guidewire lumen 225 shaped, sized, and otherwise configured to receive a guidewire. In some embodiments suitable for, for example, renal denervation, the catheter 102 may have a diameter of approximately 6 French and a length of approximately 85 cm. The proximal portion 220 of the catheter 102 may include one or more connectors or couplings. For example, the proximal portion 220 may include one or more electrical couplings 232. The catheter 102 can be coupled to a controller 120 by connecting the electrical couplings 232 to a connecting cable 140. The connecting cable 140 can be removably connected to the controller 120 and / or the catheter 102 via a port on the controller 120 and / or the catheter 102 to allow the use of multiple catheters during the procedure. In some embodiments, such as when only one catheter 102 is needed during surgery, the connecting cable 140 may be permanently connected to the controller 120.

[0064] In some embodiments, the proximal portion 220 of catheter 102 may further include one or more fluid ports, such as a fluid inlet port 234a and a fluid outlet port 234b, through which an inflatable member (e.g., balloon 112) may be fluidly coupled to reservoir 110. Figure 1 (As shown in the diagram), the reservoir supplies cooling fluid. The reservoir 110 may optionally be included within the controller 120, such as... Figure 1 The external housing attached to controller 120 shown may be provided separately. In other embodiments, fluid inlet port 234a and fluid outlet port 234b, balloon 112, and reservoir 110 may all be absent from system 100. Other variations are also possible and are within the scope of the embodiments described herein.

[0065] Figure 2B A perspective view of selected components of catheter 102 is shown, such as the distal portion 210 that can be inserted into a body cavity BL of an individual. Figure 2B In this context, the body cavity BL is a blood vessel (e.g., the renal artery), which has multiple nerve endings (N) in its outer layer (e.g., the adventitia). Figure 2B As shown, the distal portion 210 may include an ultrasonic transducer 111, a balloon 112 filled with cooling fluid 213, a catheter shaft 214, and / or a guidewire support tip 215 configured to receive a guidewire 216.

[0066] The transducer 111 may be partially or completely housed within the balloon 112, which may be inflated with cooling fluid 213 to contact the inner surface of the body cavity BL (e.g., the vascular intima). In some embodiments, the transducer 111 may be used to output acoustic signals when the balloon 112 completely obstructs the body cavity BL. The balloon 112 may center the transducer 111 within the body cavity BL. In some embodiments, such as those suitable for renal denervation, the balloon 112 is inflated with cooling fluid 213 during surgery at an operating pressure of approximately 1.4 atm to 2 atm as it is inserted into the patient's body cavity BL. The balloon 112 may be or comprise a compliant, semi-compliant, or non-compliant medical balloon. The balloon 112 is sized for insertion into the body cavity BL, and, for example, in the case of insertion into the renal artery, the balloon 112 may be selected from available sizes including, but not limited to, outer diameters of 3.5 mm, 4.2 mm, 5 mm, 6 mm, 7 mm, or 8 mm. In some embodiments, such as Figure 2BAs shown, when inflated by filling with cooling fluid 213 under the control of controller 120, the outer wall of balloon 112 can be substantially parallel to the outer surface of transducer 111. Optionally, balloon 112 can be fully inflated to align with body cavity BL. For example, when inflated, balloon 112 can at least partially contact and thus align with the inner wall of body cavity BL. In other configurations, balloon 112 is configured not to contact body cavity BL during inflating. Alternatively or additionally, balloon 112 can be maintained at a specified size by pushing cooling fluid into and out of balloon 112 at a specified flow rate. In balloon-free embodiments, transducer 111 is not housed within balloon.

[0067] Figure 2C A longitudinal cross-sectional view of the distal portion 210 of the catheter 102 is shown. Figure 3A1 The guide shaft 214 according to an embodiment is shown along... Figure 2C The cross-sectional view of line AA shown in the figure. Figure 3A2 The guide shaft 214 according to an alternative embodiment is shown along... Figure 2C The cross-sectional view of line AA shown in the figure. Figure 3B The ultrasonic transducer 111 according to an embodiment is shown along... Figure 2C The diagram shows a cross-sectional view of line BB. In some embodiments, the catheter shaft 214 may have a diameter of approximately 1.8 mm. The catheter shaft 214 includes one or more lumens that can be used as fluid conduits, cable channels, guidewire lumens, and / or the like, as referenced below. Figure 3A1 and 3A2 As described in more detail. In some embodiments suitable for, for example, renal denervation, the guidewire 216 has a diameter of about 0.36 mm and a length of about 180 cm to about 300 cm, and is delivered using a 7-French guiding catheter having a minimum inner diameter of 2.06 mm and a length of less than about 80 cm. In some embodiments, a 6-French guiding catheter is used to deliver the guidewire 216. In some embodiments, the guiding catheter has a length of about 55 cm. In some embodiments, the guiding catheter has a length of about 85 cm, and a hemostatic valve is attached to the hub of the guiding catheter to allow continuous irrigation of the guiding catheter, thereby reducing the risk of thromboembolism.

[0068] See again Figure 2CThe ultrasonic transducer 111 may comprise a cylindrical hollow tube 201 made of a piezoelectric material (e.g., lead zirconate titanate (PZT), etc.), wherein an internal electrode 202 and an external electrode 203 are respectively disposed on the inner and outer surfaces of the cylindrical tube 201. Such a cylindrical piezoelectric hollow tube is an example of a piezoelectric transducer body 201 and is therefore referred to as the piezoelectric transducer body 201. As will be described in further detail below, the piezoelectric transducer body may have various other shapes and need not be hollow. In some embodiments suitable for, for example, renal denervation, the piezoelectric material used to make the piezoelectric transducer body 201 is lead zirconate titanate 8 (PZT8), also known as Navy III piezoelectric material. A pristine PZT transducer may be plated with copper, nickel, and / or gold layers to create electrodes on the surfaces (e.g., the inner and outer surfaces) of the piezoelectric transducer body (e.g., 201). Applying voltage and alternating current across the internal electrode 202 and external electrode 203 causes the piezoelectric material to vibrate transversely to the longitudinal direction of the cylindrical tube 201 and emit ultrasonic waves radially. Although Figure 2C The ultrasound transducer 111 is not shown as being surrounded by a balloon, but it should be noted that the ultrasound transducer 111 may be positioned within the balloon (e.g., 112), for example... Figure 2B As shown in the image.

[0069] like Figure 2C As shown, the ultrasonic transducer 111 is typically supported by a backing member or support 218. In some embodiments, the backing member 218 comprises stainless steel coated with nickel and gold, wherein nickel serves as a bonding material between the stainless steel and the gold plating. In some embodiments suitable for, for example, renal denervation, the transducer 111 has an outer diameter of about 1.5 mm, an inner diameter of about 1 mm, and a length of about 6 mm. Transducers having other inner diameters, outer diameters, and lengths, and more generally other sizes and shapes, are also within the scope of the embodiments described herein. Furthermore, it should be noted that the diagrams in the figures are not necessarily drawn to scale and are often not drawn to scale.

[0070] like Figure 2C As shown, the backing member 218 can extend from the distal portion 210 of the catheter shaft 214 to the distal tip 215. For example, the distal end of the backing member 218 can be positioned within an adjacent opening in the tip 215, and the proximal end of the backing member 218 can be movably coupled to the distal portion 210 of the catheter shaft 214 via a cable 282. In other embodiments, a gap exists between the distal end of the catheter shaft 214 and the proximal end of the ultrasonic transducer 111 (e.g., in...). Figure 2C (marked as D in the middle).

[0071] To allow liquid cooling along both the internal electrode 202 and the external electrode 203, the backing member 218 may include one or more support assemblies 230a and 230b. The support assemblies 230a and 230b may define one or more annular openings through which cooling fluid 213 can enter the space between the backing member 218 and the transducer 111 (which may be selectively insulated according to some embodiments described below) between the backing member 218 and the internal electrode 202. Therefore, the backing member 218 may act as a fluid barrier between the cooling fluid 213 circulating within the balloon 112 and the interior cavity of the backing member 218 housing the guidewire 216. For example, as... Figure 2C As schematically shown, the support assemblies 230a, 230b of the backing member 218 can be positioned along or adjacent to each longitudinal end of the ultrasonic transducer 111 (separated from the main support body 289) and couple the cylindrical tube 201 of the ultrasonic transducer 111 to the backing member 218. Reference Figure 3B The support assembly 230 (230a or 230b) may have multiple lugs, ribs, or attachment points 334 for engaging the internal electrodes 202 of the transducer 111. In some embodiments, the attachment points 334 are welded to the internal electrodes 202 of the transducer 111. The number, size, and placement of the ribs 334 may vary as needed or required. For example, such as... Figure 3B As shown, a total of three ribs 334 are generally equidistant from each other at an angle of 120 degrees, thereby defining an opening 336 through which cooling fluid or blood can enter the internal space of the cylindrical tube 201 between the internal electrode 202 disposed along the inner surface of the cylindrical tube 201 and the backing member 218. In some embodiments, the maximum outer diameter of the support assemblies 230a and 230b is about 1 mm, the outer diameter of the main support body 289 is about 0.76 mm, and the inner diameter of the backing member 218 is about 0.56 mm.

[0072] According to some embodiments, the support assemblies 230a and 230b are conductive to electrically couple the internal electrodes 202 of the ultrasonic transducer 111 to the backing member 218. One or more conductors of the cable 282 may be electrically coupled to the backing member 218. Thus, with the activation of the controller 120, current can be transferred from the cable 282 to the internal electrodes 202 of the ultrasonic transducer 111 via the backing member 218 and the support assemblies 230a and 230b, which advantageously eliminates the need for direct coupling of the cable 282 to the internal electrodes 202 of the transducer 111. In other embodiments, the backing member 218 and the support assemblies 230a and 230b are made of one or more electrically insulating materials, or, if made of conductive materials, coated with one or more electrically insulating materials.

[0073] In addition, such as Figure 2CAs shown, the backing member 218 may have an isolation tube 219 disposed along its inner surface to prevent or reduce the guide wire 216 ( Figure 2B The possibility of electrical conduction between the insulating tube 219 (as shown in the diagram) and the backing member 218 is considered for use in embodiments where such electrical conduction is not required. The insulating tube 219 may be formed of a non-conductive material (e.g., a polymer, such as polyimide), which may also be referred to as an electrical insulator. Figure 2C As shown, the isolation tube 219 can extend from the conduit shaft 214 through the lumen of the backing member 218 within the transducer 111 to the tip 215. In this way, the transducer 111 is offset distally from the distal end of the conduit shaft 214.

[0074] like Figure 2C As shown, the catheter 102 may also include an orifice 277 extending proximally within the catheter 102 from its distal end and sized and shaped to receive at least a portion of the backing member 218, thereby electrically insulating the isolation tube 219 and / or the ultrasound transducer 111. Therefore, during delivery of the catheter 102 to the anatomical region being treated, the backing member 218, the isolation tube 219, and / or the ultrasound transducer 111 can be at least partially retracted within the orifice 277 of the catheter 102, for example, by retracting the cable 282, thereby providing sufficient stiffness to allow the catheter 102 to be delivered safely.

[0075] like Figure 3A1 and 3A2 As shown, the conduit shaft 214 includes one or more lumens that can be used as fluid conduits, cable channels, guidewire lumens, and / or the like. For example, such as Figure 3A1 and 3A2 As shown, the catheter shaft 214 may include a guidewire lumen 325 shaped, sized, and otherwise configured to receive the guidewire 216. In some embodiments, such as Figure 3A1 As shown, the guidewire lumen 325 is located at the center of the catheter shaft 214 so that the transducer 111 is centered within the catheter shaft 214. Alternatively, the guidewire lumen 325 may be offset from the center of the catheter shaft 214, for example... Figure 3A2 As shown in the diagram. The catheter shaft 214 may also include a cable lumen 326 for receiving the cable. Furthermore, the catheter shaft 214 may include one or more fluid lumens 327, 328 for delivering cooling fluid 213 (e.g., water, sterile water, saline, 5% dextrose (D5W)), other liquids or gases, etc., from a fluid source (e.g., reservoir 110) at the proximal portion 220 of the catheter 102 (outside the patient) to the balloon 112, and to said fluid source, under the control of the controller 120. Active cooling of approximately one millimeter of tissue is designed to maintain the integrity of the vessel wall, such as the renal artery wall.

[0076] Depending on the need or requirement, catheter 102 may include a single fluid lumen or two or more fluid lumens (e.g., three, four, more than four, etc.). Figure 3A1 As shown, in the embodiments, the fluid cavities 327 and 328 and the cable cavity 326 all have a kidney-shaped or D-shaped cross-section, configured to maximize the efficiency of fluid flow transmission by maximizing the area while minimizing the perimeter of the fluid cavities 327 and 328, and to uniformly distribute fluid across the ultrasonic transducer 111. In some embodiments, each of the fluid cavities 327 and 328 and the cable cavity 326 is substantially symmetrical, identical in size, identical in geometry, and / or interchangeable, for example... Figure 3A1 As shown in the illustration. Variations in the fluid flow rate within the catheter may result in treatment delays or incompleteness. In some embodiments, the catheter shaft 214 is configured to achieve a fluid flow rate of approximately 40 mL / min. In some embodiments, the catheter shaft 214 is configured to achieve a fluid flow rate of approximately 35 mL / min to 45 mL / min. In some embodiments, the catheter shaft 214 is configured to achieve a fluid flow rate of approximately 20 mL / min to 45 mL / min. In some embodiments, such as those suitable for radial delivery during renal denervation surgery, the catheter shaft 214 is configured to achieve a fluid flow rate of approximately 10 mL / min to 20 mL / min. Each of one or more lumens (e.g., 328) may be in fluid communication with the same or separate individual fluid sources outside the patient at the proximal portion 220 of the catheter 102.

[0077] As another example, catheter shaft 214 may include any suitable number of fluid lumens for delivering cooling fluid from reservoir 110 to balloon 112 and from balloon 112 (or delivering cooling fluid to transducer 111 in a balloon-free embodiment) in response to instructions executed by controller 120. In some balloon-free embodiments, fluid lumens 327, 328 of catheter shaft 214 may be omitted and reservoir 110 may be omitted from system 100. In some balloon-free embodiments, catheter shaft 214 includes fluid lumens 327, 328 and system 100 includes reservoir 110.

[0078] In some embodiments, such as Figure 3A2As shown, the guidewire lumen 225 is positioned close to and / or shares a wall with the catheter shaft 214 to allow for rapid catheter replacement during surgery. In such embodiments, the cable lumen 326 may be positioned opposite the guidewire lumen 225 and also shares a wall with the catheter shaft 214. The cable lumen 326 may be, for example, triangular or rectangular in shape and may be configured to maximize the area available for the fluid cavities 327 and 328 while minimizing their perimeter, thereby achieving a higher flow rate for the same pressure. The fluid cavities 327 and 328 may be shaped to optimize flow rate and reduce resistance of the catheter 102. In such embodiments, instead of maximizing the area of ​​the fluid cavities 327 and 328, the walls of the fluid cavities 327 and 328 may be rounded to avoid cavities that could otherwise cause resistance, thereby optimizing the flow rate of the cooling fluid 213 within the fluid cavities 327 and 328.

[0079] The conduit shaft 214 may contain a cable 282 (e.g., a coaxial cable, a parallel-coaxial cable, a shielded parallel-pair cable, one or more wires, or one or more other electrical conductors) at least within the cable cavity 326. The cable 282 couples the internal electrodes 202 and external electrodes 203 of the ultrasonic transducer 111 to the controller 120, allowing the controller 120 to apply a suitable voltage across these electrodes to cause the piezoelectric material of the transducer 111 to emit ultrasonic energy toward an individual. In some embodiments, the cable cavity 326 is shaped, sized, and otherwise configured to accommodate the cable 282 (e.g., a coaxial cable, wire, other electrical conductor, etc.). The cable 282 allows selective activation of the electrodes 202, 203 of the ultrasonic transducer 111 to emit acoustic energy toward an individual. More specifically, cable 282 allows transducer information, such as operating frequency and power, to be transmitted from conduit 102 to controller 120 and / or from controller 120 to conduit 102, and electrical energy to be delivered to ultrasound transducer 111 during surgery.

[0080] The distal portion 210 of catheter 102 can be percutaneously delivered to the target anatomical site (e.g., a designated site within the body cavity BL) via any suitable endoluminal access, such as via a gastrointestinal access or via an endovascular access such as a femoral or radial access. In some embodiments, controller 120 is configured to fill balloon 112 with cooling fluid 213 only after the distal portion 210 of catheter 102 has been properly positioned at the target anatomical site. Catheter 102 can be delivered across the body cavity BL with or without the assistance of a commercially available guidewire. For example, catheter 102 and balloon 112 can be delivered via guidewire 216 (… Figure 2B(As shown in the diagram) and delivered via a renal guiding catheter. For other examples of guidewire-based delivery of ultrasound transducers, see U.S. Patent No. 10,456,605, which is incorporated herein by reference above. However, it should be understood that any suitable maneuverable catheter or sheath or any other suitable guiding device or method can be used to deliver the distal portion 210 of catheter 102 to the target anatomical site of the individual. Once delivered to the appropriate site within the body cavity BL, balloon 112 can be inflated with cooling fluid 213 (e.g., under the control of controller 120), and transducer 111 can be actuated (e.g., by applying voltage across internal electrode 202 and external electrode 203 under the control of controller 120) to deliver non-focused ultrasound energy to the target anatomical site. The transducer 111 is sized for insertion into the body cavity BL, and for example, when inserted into a renal artery, the transducer 111 may have an outer diameter of less than 2 mm, for example, about 1.5 mm, and an inner diameter of less than 1.8 mm, for example, about 1 mm. As described in more detail below, the length L of the transducer 111 may be optionally selected such that the ultrasound waves generated by the transducer 111 have a near-field depth suitable for generating lesions only in the desired area relative to the wall of the target body cavity BL.

[0081] See Figure 1 , 2A According to certain embodiments, 2C, 3A1, and 3A2, the proximal end of the connecting cable 140 is connected to the controller 120, and the distal end of the connecting cable 140 is connected to an electrical coupling connector 232 on the proximal portion of the conduit 102. The cable 282 passes through the cable cavity of the conduit shaft 214 (e.g., Figure 3A1 (Or 326 in 3A2) extends to the electrical coupling connector 232, thereby electrically coupling the transducer 111 to the electrical coupling connector 232. By electrically coupling the connecting cable 140 between the controller 120 and the electrical coupling connector 232 and by electrically coupling the cable 282 between the electrical coupling connector 232 and the transducer 111, the controller 120 is electrically coupled to the transducer 111, thereby providing power to the transducer 111 and otherwise controlling the transducer 111.

[0082] It should be understood that the frequency, power, and duration at which the transducer 111 is appropriately actuated can be selected based on the treatment to be performed. For example, the frequency may be optionally in the range of 1 MHz to 20 MHz, such as 1 MHz to 5 MHz, 5 MHz to 10 MHz, 8.5 MHz to 9.5 MHz, 10 MHz to 15 MHz, 15 MHz to 20 MHz, or 8 MHz to 10 MHz, such as about 9 MHz. Or, for example, the frequency may be optionally in the range below 1 MHz, such as 0.1 MHz to 0.2 MHz, 0.2 MHz to 0.3 MHz, 0.3 MHz to 0.4 MHz, 0.4 MHz to 0.5 MHz, 0.5 MHz to 0.6 MHz, 0.6 MHz to 0.7 MHz, 0.7 MHz to 0.8 MHz, 0.8 MHz to 0.9 MHz, or 0.9 MHz to 1.0 MHz. Alternatively, for example, the frequency may optionally be in the range above 20 MHz, such as 20 MHz to 25 MHz, 25 MHz to 30 MHz, or above 30 MHz. Optionally, the power may be in the range of 5 W to 80 W (e.g., 5 W to 50 W, 5 W to 10 W, 12.1 W to 16.6 W, 10 W to 20 W, 20 W to 30 W, 30 W to 40 W, 40 W to 50 W, 50 W to 60 W, 60 W to 70 W, or 70 W to 80 W, or greater than 80 W). For example, the power may be 20 W to 40 W, wherein for a balloon with a smaller diameter (e.g., 3.5 mm to 5 mm), the power may be 20 W to 30 W, and for a balloon with a larger diameter (e.g., 5 mm to 8 mm), the power may be 30 W to 40 W. The duration for which transducer 111 is actuated may be sufficient to complete the specific treatment being performed and may depend on factors such as, for example, the power at the transducer, the frequency of the emitted ultrasound energy, the size of the tissue area being treated, the age, weight, and sex of the patient being treated, and / or similar factors. Illustratively, in some configurations, the duration for which transducer 111 can be actuated may range from about 3 seconds to 5 minutes, for example, 3 seconds to 10 seconds, 3 seconds to 30 seconds, 30 seconds to 1 minute, 30 seconds to 5 minutes, 1 minute to 3 minutes, about 2 minutes, 10 seconds to 1 minute, 1 minute to 2 minutes, 2 minutes to 3 minutes, 3 minutes to 4 minutes, or 4 minutes to 5 minutes. Alternatively, for example, transducer 111 can be actuated for less than 10 seconds (s), such as 0.1s to 10s, 1s to 2s, 2s to 3s, 3s to 4s, 4s to 5s, 5s to 6s, 6s to 7s, 7s to 8s, 8s to 9s, or 9s to 10s. Alternatively, for example, transducer 111 can be actuated for more than 5 minutes (m), such as 5m to 6m, 6m to 7m, 7m to 8m, 8m to 9m, 9m to 10m, 10m to 15m, 15m to 20m, or more than 20 minutes.

[0083] In various configurations, the delivery of ultrasound energy during treatment can be continuous or substantially continuous, for example, without any interruption or fluctuation in frequency, power, duty cycle, and / or any other parameters. Alternatively, one or more of the frequency, power, duty cycle, or any other parameters can be modified during treatment. For example, in some configurations, the delivery of ultrasound energy is modulated, such as between on and off states or between relatively high and relatively low levels, to prevent or reduce the possibility of overheating of adjacent (e.g., target or non-target) tissue. For examples of such modulation, see U.S. Patent No. 10,499,937 to Warnkin, the entire contents of which are incorporated herein by reference.

[0084] In treating nerve tissue (e.g.) Figure 2B In the illustrated example configuration of the nerve N, transducer 111 (or 411, 511, 811, 911, 1011, or 111, etc.) may be positioned and configured to transmit ultrasound energy through the wall of the body cavity BL adjacent to the nerve tissue, for example, through the wall of the body cavity BL. In a non-limiting example, the renal nerve to be treated with transducer 111 may be positioned approximately 0.5 mm to 8 mm (e.g., approximately 1 mm to 6 mm) from the inner wall of the renal artery. In other examples, the nerve tissue to be treated may be positioned less than approximately 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, less than 0.5 mm, or greater than 8 mm from the inner wall of the body cavity where the transducer is located. Under the control of controller 120, transducer 111 (or 411, 511, 811, 911, 1011, or 111, etc.) generates non-focused ultrasonic energy that heats any suitable nerve tissue to at least partially neuromodulate such nerve tissue, for example, causing complete or partial ablation, necrosis, or stimulation of such nerve tissue. The ultrasonic energy generated by transducer 111 (or 411, 511, 811, 911, 1011, or 111, etc.) can be radiated radially outward to target nerve tissue, regardless of the radial orientation of such nerve tissue relative to the body cavity. In some configurations, the non-focused ultrasonic energy is delivered along the entire continuous circumference of transducer 111 (or 411, 511, 811, 911, 1011, or 111, etc.). In other configurations, ultrasound energy is emitted discontinuously or intermittently around the circumference of transducer 111 (or 411, 511, 811, 911, 1011, or 111, etc.). It should be understood that neural tissue, and more specifically the renal nerve, is only one example of tissue that can be treated with an ultrasound transducer. Other examples of target anatomical regions that can be treated with ultrasound transducer 111 are described elsewhere in this document.

[0085] Regardless of the specific shape or extent of the acoustic energy delivered by the transducer to the target anatomical region, the cooling fluid 213 within the balloon 112 surrounding the transducer protects certain tissues of the individual. For example, the cooling fluid 213 can prevent or reduce the possibility of narrowing or other damage to the walls of the body cavity BL through which energy is delivered during treatment. In some configurations, the cooling fluid 213 flows across one or both of the outer and inner surfaces of the transducer 111 (or 411, 511, 811, 911, 1011, or 111, etc.), for example, in direct contact with one or both of the outer and inner surfaces of the transducer. In some embodiments described in more detail below, the electrical insulator of the transducer prevents electrical short circuits between the electrodes of the transducer caused by the conductive cooling fluid 213 or by blood. As used herein, the terms “short circuit,” “electrical short,” and the like are used interchangeably and refer to any conductive path with an impedance of less than 10,000 ohms. Therefore, in the case of a “short circuit” between a pair of electrodes, this means that there is a conductive path with an impedance of less than 10,000 ohms between the pair of electrodes, wherein such a conductive path may be provided by a conductive fluid, but is not limited thereto.

[0086] Selective Insulation Transducer

[0087] Briefly refer back to Figure 2B According to some embodiments, the ultrasonic transducer 111 is partially or completely housed within the balloon 112. As explained above, in Figure 2B In the initial discussion, the balloon 112 can be inflated using a cooling fluid 213 to contact the inner surface of the body cavity BL (e.g., the endothelium of a blood vessel). More specifically, the cooling fluid 213 circulates around the ultrasound transducer 111 to actively cool the treatment area. Using a non-conductive cooling fluid 213 maintains electrical isolation between the internal electrode 202 and the external electrode 203 of the ultrasound transducer 111. However, medical personnel must keep a reserve of and remember to use the non-conductive cooling fluid 213. For the convenience of medical personnel, ultrasound transducers according to certain embodiments described herein are designed to operate properly when surrounded by or otherwise exposed to a conductive fluid, such as, but not limited to, saline. It should be understood from the following discussion that such embodiments are implemented by insulating at least a portion of the ultrasound transducer 111. Where the ultrasound transducer is partially insulated so that it can operate properly when used with or otherwise exposed to a conductive fluid, such as blood, the transducer may generally be referred to as a selectively insulated transducer or a partially insulated transducer, or more simply as a transducer.

[0088] Advantageously, the selectively insulating transducer disclosed herein allows for cooling of the transducer using a conductive cooling fluid (e.g., 213) and / or the patient's own blood flow. More specifically, the selectively insulating transducer disclosed herein can be configured to include at least one electrical insulator that prevents (and preferably prevents) short circuits between the transducer's electrodes (e.g., 202 and 203) via a conductive fluid within the balloon or blood. Illustratively, the insulating transducer of the present invention may comprise a hollow cylindrical tube (e.g., 201) made of a piezoelectric material, which can be disposed within a balloon and includes an inner surface and an outer surface. In some embodiments, such as some embodiments described above, the transducer is cylindrical. An inner electrode (e.g., 202) may be disposed on the inner surface of the hollow cylindrical tube (e.g., 201), and an outer electrode (e.g., 203) may be disposed on the outer surface of the hollow cylindrical tube (e.g., 201) of the transducer. The external or internal electrode may have an electrical insulator that covers the electrode to prevent an electrical short circuit between the external electrode (e.g., 203) and the internal electrode (e.g., 202) via a conductive fluid.

[0089] The piezoelectric material constituting the hollow cylindrical tube (e.g., 201) can be actuated by applying a voltage across the internal and external electrodes, for example, by a suitably programmed controller (e.g., 120) electrically connected to the internal electrodes (e.g., 202) and the external electrodes (e.g., 203), in a manner known in the art. In the absence of the electrical insulator of the present invention, in the absence of a balloon, or if the balloon is filled with a conductive fluid, applying a voltage across the internal and external electrodes (e.g., 202 and 203) may cause an electrical short circuit, which would prevent the piezoelectric material from generating ultrasonic waves. In the absence of the electrical insulator of the present invention, such short circuits can be prevented by using a non-conductive fluid, such as suitable deionized water or dextrose, within the balloon, which itself provides insulation between the internal and external electrodes. However, using such a non-conductive fluid in a surgical environment may be inconvenient. For example, hospitals and other treatment centers typically do not maintain a deionized water supply in their operating rooms. The selectively insulating transducer described herein allows for the use of conductive fluids readily available in all hospitals and other treatment centers within the balloon, thus enhancing the ease of integrating the system of the present invention into the surgical environment. Examples of conductive fluids readily available in all hospitals and other treatment centers include saline, non-pure water, or sodium lactate solution. Sodium lactate solution, also known as Ringer's lactate solution, lactate Ringer's solution, or Hartmann's solution, is a type of isotonic crystalline fluid, further classified as a equilibrium or buffer solution for fluid displacement. Such sodium lactate solutions contain sodium, chloride, potassium, calcium, and lactate in the form of sodium lactate, mixed to form a solution with a volumetric osmotic concentration of 273 mOsm / L and a pH of approximately 6.5.

[0090] In some embodiments, a balloon-free catheter can be used, in which case conductive blood flowing within the body cavity is used to cool the transducer. The requirement to use a balloon increases the time and complexity of the procedure, as the physician may need to use multiple balloons and catheters during a single procedure. Furthermore, failure to use the correct balloon size can lead to renal artery dissection, perforation, aneurysm, severe vasospasm requiring intervention, ablation of unintended tissue or structures, or failure to achieve target tissue ablation. Additionally, some arteries, such as accessory arteries, may be untreatable due to balloon size constraints. Untreated accessory arteries may indicate a reduced response to renal denervation. The inflatable balloon should be positioned against the renal artery wall to maximize tissue ablation, and multiple balloon inflations to achieve this alignment can increase vascular trauma. Advantageously, the selectively insulated transducer disclosed herein allows for the use of a balloon-free catheter, where the patient's own blood flow serves as the cooling fluid.

[0091] Figure 4AThis is a side view of the distal portion of a catheter (e.g., 102) of an ultrasound-based tissue therapy system (e.g., 100) including a selectively insulating transducer 411, according to certain embodiments of the present invention. The selectively insulating transducer 411 may also be more simply referred to as selectively insulating transducer 411, or even more simply referred to as transducer 411. Figure 4B This is a perspective view of a selectively insulating transducer 411 according to certain embodiments of the present invention, wherein the external electrodes (e.g., 203) of the piezoelectric transducer body (e.g., 202) are covered by an electrical insulator 404. Figure 4C and 4D Show each Figure 4A and 4B The longitudinal and radial cross-sectional views of the selectively insulating transducer 411 described in the document are shown.

[0092] exist Figures 4A to 4D In one embodiment, the piezoelectric transducer body 201 includes a hollow tube of piezoelectric material having an inner surface and an outer surface, wherein an internal electrode 202 is disposed on the inner surface of the hollow tube, and an external electrode 203 is disposed on the outer surface of the hollow tube. In this embodiment, the hollow tube of piezoelectric material is an example of the piezoelectric transducer body 201. Figures 4A to 4D In the piezoelectric material, the hollow tube, or more generally the piezoelectric transducer body 201, is cylindrical with a circular radial cross-section, such as from... Figure 4D It is understood. However, in alternative embodiments, the hollow tube of the piezoelectric material may have shapes other than a cylinder with a circular radial cross-section. Other cross-sectional shapes of the hollow tube of the piezoelectric material, and more generally other cross-sectional shapes of the piezoelectric transducer body 201, include, but are not limited to, oval or elliptical cross-sections, square or rectangular cross-sections, pentagonal cross-sections, hexagonal cross-sections, heptagonal cross-sections, octagonal cross-sections, and / or similar shapes.

[0093] The hollow tube, and more generally the piezoelectric transducer body 201, can be made of various types of piezoelectric materials, such as, but not limited to, lead zirconate titanate (PZT), polyvinylidene fluoride (PVDF), or other currently available or future-developed piezoelectric ceramic materials. Figures 4A to 4CAs depicted herein, transducer 411 may include a stepped portion 417, as described in its entirety in U.S. Patent No. 10,456,605, which is incorporated herein by reference. In some embodiments, the stepped portion 417 on the proximal end of transducer 411 allows attachment of cable 282, for example, via a parallel wire (not shown), which transfers energy to transducer 411. In some embodiments, cable 282 comprises a parallel coaxial cable having a combined impedance of approximately 50 ohms. Such a stepped portion 417 may be incorporated into any of the transducers described herein. It will also be possible for both the proximal and distal ends of the transducer to include stepped portions (same as or similar to 417), and such embodiments may be referred to as double-stepped embodiments.

[0094] See Figure 4C According to certain embodiments suitable for renal denervation surgery, the outer diameter (OD) of the piezoelectric transducer body 201 is in the range of about 1.3 mm to 1.7 mm, and the inner diameter (ID) of the piezoelectric transducer body 201 is in the range of about 0.8 mm to 1.2 mm. In a particular embodiment, the OD is about 1.5 mm and the ID is about 1 mm. According to certain embodiments, the piezoelectric material wall thickness (W-TH) of the piezoelectric transducer body 201 between its inner diameter (ID) and its outer diameter (OD) is in the range of 0.2 mm to 1.0 mm. More specifically, the wall thickness (W-TH) may be in the range of 0.2 mm to 0.5 mm. Even more specifically, the wall thickness (W-TH) may be in the range of 0.24 mm to 0.26 mm (and even more specifically, may be 0.25 mm + / - 0.01 mm), which can provide an ultrasonic transducer that generates acoustic energy at a frequency of about 9 MHz. In some embodiments, the ultrasonic transducers described herein (e.g., 211, 411, 511, 811, 911, 1011, 1211, etc.) are configured to deliver acoustic energy in the frequency range of 8.5 MHz to 9.5 MHz. In some embodiments, such transducers are configured to deliver acoustic energy in the frequency range of 8.7 MHz to 9.3 MHz or 8.695 MHz to 9.304 MHz. Transducers delivering acoustic energy in the frequency range of 8.7 MHz to 9.3 MHz have been shown to produce ablation with an average depth of up to 6 mm. The piezoelectric transducer body 201, as well as the external electrode 203 and internal electrode 202, can be formed using any suitable method, such as the method described in U.S. Patent No. 10,140,041 to Taylor, the entire contents of which are incorporated herein by reference. The thickness (I-TH) of the electrical insulator 404 (and other electrical insulators described herein) can be in the range of about 10 μm to 20 μm, but is not limited thereto. The dimensions and thicknesses mentioned above are for reference only. Figures 4A to 4DThe embodiments shown herein are described, but the same applies to other embodiments described herein, including those described below.

[0095] exist Figures 4A to 4D In this embodiment, the electrical insulator is not disposed on the internal electrode 202. In other words, in Figures 4A to 4D In this embodiment, regarding both the internal electrode 202 and the external electrode 203, only the external electrode 203 is covered by an electrical insulator 404. In this type of embodiment, the electrical insulator 404, disposed on and covering the external electrode 203, prevents (and preferably prevents) the external electrode 203 from contacting the conductive fluid (e.g., 213) when the ultrasonic transducer 411 is positioned in a conductive fluid. In other words, in this type of embodiment, the electrical insulator 404 provides both electrical and physical isolation from the conductive fluid in which the transducer is internally housed. However, since the electrical insulator is not disposed on the internal electrode 202, the internal electrode 202 can contact the conductive fluid when the ultrasonic transducer 411 is positioned in the conductive fluid (e.g., 213). In this type of embodiment, when the ultrasonic transducer 411 is placed in a conductive fluid, the electrical insulator 404 disposed on the external electrode 203 prevents (and preferably prevents) electrical conduction between the internal electrode 202 and the external electrode 203. The piezoelectric transducer body 201 is configured to generate ultrasonic waves in response to a voltage applied between the internal electrode 202 and the external electrode 203. When the ultrasonic transducer 411 is placed in a conductive fluid and a voltage is applied between the internal electrode 202 and the external electrode 203, the electrical insulator 404 prevents (and preferably prevents) a short circuit between the internal electrode 202 and the external electrode 203. More specifically, the controller 120 may be electrically coupled to the internal electrode 202 and the external electrode 203 via a cable 282 and may actuate the selectively insulated transducer 411 (or any other selectively insulated transducer described herein) by applying a voltage between the internal electrode 202 and the external electrode 203 (or any other pair of electrodes described herein) to cause the piezoelectric material of the piezoelectric transducer body 201 to generate radially outwardly radiating, unfocused ultrasonic waves.

[0096] In some embodiments, the ultrasonic transducer 411 is placed within a balloon (e.g., 112) at least partially filled with a cooling fluid (e.g., 213), said cooling fluid being a conductive fluid used to cool a portion of the body cavity BL in which the ultrasonic transducer 411 is located. The conductive fluid used to at least partially fill the balloon may be, for example, saline, non-pure water, or a sodium lactate solution, or combinations thereof, but is not limited thereto. In an alternative embodiment, which may be referred to as a balloon-free embodiment, the ultrasonic transducer 411 is directly exposed to blood flowing through the body cavity BL in which the ultrasonic transducer is located; in this case, the conductive fluid comprises blood. In some embodiments, the electrical insulator 404 is parylene, and more specifically, a parylene conformal coating.

[0097] Materials suitable for forming the electrical insulator 404 include, but are not limited to, parylene, cyanoacetate, epoxy resin, nylon, polytetrafluoroethylene (PTFE), polyimide, polyethylene, polyethylene terephthalate, polyvinyl chloride (PVC), or combinations thereof. In some embodiments, parylene C is used to coat gold-containing electrodes using a chemical vapor deposition method as described, for example, in U.S. Patent No. 5,908,506. As another example, the electrical insulator 404 may be a synthetic diamond coating, which may be deposited, for example, using chemical vapor deposition (CVD). In an embodiment, the surface of the electrode is treated with an adhesion promoter, followed by coating the surface with an electrical insulator 404, such as parylene. The adhesion promoter is, for example, a solution of silane, titanium (Ti), silicon oxide (SiOx), cobalt-like carbon (DLC), tetramethylsilane (TMS), and alumina (AlOx), 1 gram of ethyl 2-methylthiomethacrylate, or 1 gram of 4-chlorothiophenol diluted in 1 L of propanol (purchased from Th. Geyer GmbH & Co. KG, headquartered in Reningen, Germany), or AdPro, available from Specialty Coating Systems (headquartered in Indianapolis, Indiana, USA). or AdPro And many other suppliers. In some embodiments, plasma surface treatment methods may be used to prevent parylene delamination. It should be noted that polytetrafluoroethylene (PTFE) is often marketed under the trademark TEFLON. TM For sale, the trademark mentioned is a registered trademark of Chemours, Inc. (headquartered in Wilmington, Delaware, USA), and polyimide is often marketed under the trademark KAPTON. TM The trademark is a registered trademark of DuPont (also headquartered in Wilmington, Delaware, USA). In a particular embodiment, the peripheral surface of the outer electrode 203 is covered with a parylene coating, and the opposing longitudinal ends of the outer electrode 203 are covered with epoxy resin. Other combinations of the aforementioned electrical insulating materials are also possible and within the scope of the embodiments described herein.

[0098] Various types of parylene coatings can be used, including conformal coatings of ultrathin, pinhole-free polymer coatings with excellent moisture-proof, chemical and dielectric barrier properties, thermal and ultraviolet (UV) stability, and dry film lubricity. Examples of parylene types include, but are not limited to, parylene N, parylene C, and parylene D.

[0099] As mentioned above, the thickness of the electrical insulator (e.g., 404, and other electrical insulators described herein) can range from about 10 μm to 20 μm, but is not limited thereto. According to some embodiments, an adhesion promoter may be included between the electrode (e.g., external electrode 203) and the electrical insulator (e.g., 404) to improve the adhesion of the electrical insulator to the electrode. To reduce the chance of pinholes in the electrical insulator (e.g., 404) that could lead to undesirable leakage, multiple layers or coatings of the electrical insulator material may be applied during multiple coating cycles. For example, in the case of an electrical insulator with a 15 μm thick parylene coating, the coating may be deposited on the electrode in three separate coating cycles, each providing a 5 μm coating thickness to collectively provide a 15 μm thick parylene coating.

[0100] The internal electrode 202 and the external electrode 203 may be made of the same conductive material or of different conductive materials. Examples of suitable conductive materials for use as the internal electrode 202 and the external electrode 203 include copper, silver, and gold, and / or combinations thereof. In some embodiments, nickel may be used as a barrier layer to prevent lead from degrading the gold-plated electrode. Examples of thicknesses for the internal electrode 202 and the external electrode 203 include approximately 120 microinches. In some embodiments, electrodes 202, 203 comprise an approximately 15-microinch base coat of electroless copper plating, a second coating of approximately 102 to 120 microinches of high-phosphorus electroless nickel plating, and a third coating of approximately 5 microinches of electroplated gold plating. The metal layers provide a means for soldering cables 282 (e.g., parallel coaxial cables) to the tube surface without damaging the piezoelectric material and allowing for a uniform electrical load to be applied to the transducer. In some embodiments, the metal layers of the electrode coatings are configured to produce electrodes that do not peel or detach due to mechanical or thermal loads and supply a uniform electrical load during acoustic treatment. The internal electrode 202 and the external electrode 203 may have the same thickness or different thicknesses. The internal electrode 202 and the external electrode 203 may be formed using any suitable method, such as, but not limited to, electroless plating and vapor deposition.

[0101] To apply voltage between the internal electrode 202 and the external electrode 203 (or any other electrode) of the transducer disclosed herein, or more generally, to provide input power to the transducer, a cable (e.g., 282) is connected between the controller 120 (or some other voltage source) and the electrodes of the transducer to provide an electrical connection between the controller 120 (or some other voltage source) and the electrodes. For example, one or more coaxial cables or other types of conductive wiring may be soldered to the electrodes of the transducer. Before or after such cables are attached to the electrodes of the transducer, one of the electrodes may be coated with and thereby covered with an electrical insulator. If the electrical insulator is applied to the electrode before the cable (e.g., 282) is attached (e.g., soldered) to the electrode, then portions of the electrical insulator should be removed (e.g., by etching) or left uninsulated (e.g., by using a mask) so that the cable (e.g., 282) can be soldered or otherwise attached to the electrode. Following welding or other types of attachment, the solder ball or similar material is covered with an electrical insulator, such as, but not limited to, epoxy resin. In other words, the connection between the cable (which comprises one or more cables) and the electrode (which is to be insulated) should also be insulated. Otherwise, exposing the solder ball (or other electrical connection between the cable and the electrode) to a conductive fluid would be equivalent to exposing the entire electrode to the conductive fluid. More generally, in cases where a cable will be connected to an electrode covered with an electrical insulator, care should be taken to ensure that the conductive portions of the cable or attachment mechanism (e.g., the solder ball) are not exposed to the conductive fluid when the transducer is in use. This applies to transducer 411 and other selectively insulated transducers described herein (e.g., 511, 911, 1011, etc.).

[0102] Figure 5A and 5BLongitudinal and radial cross-sectional views of a selectively insulated transducer 511 according to another embodiment of the invention are shown, wherein the internal electrode 202 of the piezoelectric transducer body 201 is covered by an electrical insulator 504. In this embodiment, when the ultrasonic transducer 511 is positioned in a conductive fluid (e.g., 213), the electrical insulator 504, disposed on and covering the internal electrode 202, prevents (and preferably prevents) contact between the internal electrode 202 and the conductive fluid. In other words, in this embodiment, the electrical insulator 504 provides both electrical and physical isolation from the conductive fluid in which the transducer is housed. However, since the electrical insulator is not disposed on the external electrode 203, the external electrode 203 can contact the conductive fluid when the ultrasonic transducer 511 is positioned in the conductive fluid (e.g., 213). In this embodiment, when the ultrasonic transducer 511 is placed in the conductive fluid, the electrical insulator 504 disposed on the internal electrode 202 prevents (and preferably prevents) electrical conduction between the internal electrode 202 and the external electrode 203. When the ultrasonic transducer 511 is placed in a conductive fluid and a voltage is applied between the inner electrode 202 and the outer electrode 203, the electrical insulator 504 prevents (and preferably prevents) a short circuit between the inner electrode 202 and the outer electrode 203.

[0103] In some embodiments, the ultrasonic transducer 511 is placed within a balloon (e.g., 112) at least partially filled with a cooling fluid (e.g., 213), said cooling fluid being a conductive fluid, used to cool a portion of the body cavity BL in which the ultrasonic transducer 511 is located. (See above for further details.) Figures 4A to 4D The embodiments described herein illustrate examples of types of conductive cooling fluids that can be used, and therefore need not be repeated. Electrical insulator 504 may be made of parylene, or of any or a combination of other types of electrical insulating materials described above with reference to electrical insulator 404. In a particular embodiment, the peripheral surface of the inner electrode 202 is covered with a parylene coating, and the opposing longitudinal ends of the inner electrode 202 are covered with epoxy resin. Other combinations of the aforementioned electrical insulating materials are also possible and within the scope of the embodiments described herein.

[0104] Figure 6A and 6B Longitudinal and radial cross-sectional views of transducer 611 are shown, wherein both the internal electrode 202 and the external electrode 203 of the piezoelectric transducer body 211 are covered by an electrical insulator. More specifically, the internal electrode 202 is covered by an electrical insulator 504, and the external electrode 203 is covered by an electrical insulator 404. Reference will be made below. Figure 7As described in more detail, isolating both the internal electrode 202 and the external electrode 203 (or more generally, both electrodes) of the ultrasonic transducer provides poorer performance, especially when the input power is in the range of about 5 watts to 80 watts and the acoustic output power is in the range of about 5 watts to 45 watts.

[0105] The above reference Figures 4A to 4D The selectively insulating transducers described in 5A and 5B (each of which includes a piezoelectric transducer body 201 comprising a hollow tube of piezoelectric material) may also include a backing member (e.g., 218), an isolation tube (e.g., 219), a support assembly (e.g., 230), and / or an attachment point (334), examples of which are shown in Figure 2C and 3B And in the above reference Figure 2C and 3B These details are described. However, for the sake of simplicity, these added details are not shown in the diagram. Figures 4A to 4D 5A and 5B.

[0106] Figure 7 This is a graph showing the input electrical power versus acoustic output electrical power for a piezoelectric ultrasonic transducer, illustrating how varying the insulation of different electrodes or combinations thereof can affect the performance of an ultrasonic transducer immersed in a cooling fluid. The piezoelectric transducer body 201 includes a hollow tube of piezoelectric material with inner and outer surfaces, with an internal electrode 202 and an external electrode 203 respectively disposed on the inner and outer surfaces. The acoustic output power of the ultrasonic transducer can be measured in response to different electrical input powers using radiation force balancing (RFB) or other instruments and techniques. See also... Figure 7 Curve 701 corresponds to an ultrasonic transducer (e.g., Figure 2B In curve 701 (e.g., 411), neither the internal electrode 202 nor the external electrode 203 is covered by an electrical insulator. As can be seen from curve 701, the acoustic output power increases in response to an increase in the input electrical power until the electrical input power reaches approximately 80 watts (W). After this point, the ultrasonic transducer begins to fail and the acoustic output power drops rapidly. Curve 702 corresponds to an ultrasonic transducer (e.g., 411), where the external electrode 203 is covered by an electrical insulator (e.g., 404), but the internal electrode 202 is not. From... Figure 7 As can be seen, curves 701 and 702 are almost identical. Therefore, in curve 702, the acoustic output power increases in response to the increase of the input electrical power until the electrical input power reaches about 80W. After this point, the ultrasonic transducer begins to break down and the acoustic output power drops rapidly.

[0107] Curve 703 corresponds to an ultrasonic transducer (e.g., 511), where the inner electrode 202 is covered by an electrical insulator (e.g., 504), but the outer electrode 203 is not covered by an electrical insulator. From Figure 7 It can be understood that although the efficiency of the ultrasonic transducer (e.g., 511) is slightly lower than that of the case where electrodes 202 and 203 are not covered by an electrical insulator or only the external electrode 203 is covered by an electrical insulator, the acoustic output power still increases in response to the increase of the input electrical power until the electrical input power reaches approximately 80W. After this point, the ultrasonic transducer begins to fail and the acoustic output power drops rapidly. Curve 704 corresponds to the ultrasonic transducer (e.g., 611), where the internal electrode 202 is covered by an electrical insulator (e.g., 504) and the external electrode 203 is covered by an electrical insulator (e.g., 404). From curve 704, it can be seen that the acoustic output power increases in response to the increase of the input electrical power until the electrical input power reaches approximately 58W. After this point, the ultrasonic transducer begins to fail and the acoustic output power drops rapidly. The electrical insulators (e.g., 404 and 504) that produce curves 702, 703, and 704 were tested to be a parylene C coating.

[0108] When execution generates Figure 7 In the experiments shown in the diagram, the cooling fluid (in which the transducer under test was immersed) was deionized water, which is a non-conductive fluid. The reason for using a non-conductive fluid in this type of experiment is that if a conductive cooling fluid were used, a short circuit would occur between the non-insulated electrodes of the ultrasonic transducer (e.g., 111), whose performance is represented by curve 701. Regarding the selectively insulated ultrasonic transducers (e.g., 411 and 511), whose performance is represented by curves 702 and 703, and regarding the transducer (e.g., 611), whose performance is represented by curve 704, where both electrodes are covered by an electrically insulating material, it is believed that… Figure 7 Curves 702, 703, and 704 in the diagram also demonstrate how such transducers behave when immersed in conductive cooling fluids such as saline, sodium lactate solution, or blood.

[0109] from Figure 7 It can be understood that the selectively insulated transducer providing optimal performance is a selectively insulated transducer (e.g., 411) where only the outer electrode 203 is covered by a parylene-coated type electrical insulator and the input power is less than about 90 W (as shown by curve 702), while the next best performance is provided by a selectively insulated transducer (e.g., 511) where only the inner electrode 202 is covered by a parylene-coated type electrical insulator (as shown by curve 703). From Figure 7 It is also understood that transducers (e.g., 611) with both internal electrode 202 and external electrode 203 coated with an electrical insulator of the type of parylene coating break down at significantly lower input power (as shown by curve 704) and thus provide poor performance.

[0110] More specifically, from Figure 7It is understood that covering both the internal electrode 202 and the external electrode 203 with appropriate electrical insulators will degrade the power performance of the transducer at higher input power (e.g., above approximately 30 W) (curve 704), at which point the ultrasonic output power of the transducer is lower than that without any electrical insulators (curve 701), or lower than that with only one electrode covered by an electrical insulator (curves 702 and 703). Without wishing to be bound by any theory, it is believed that such degradation may be caused by thermally induced mechanical stress during operation of the transducer at higher power levels, for example, because the electrical insulators on the two electrodes of the piezoelectric transducer body 201 can trap heat within the piezoelectric material, thus causing mechanical stress. Figure 7 It is also understood that covering only the internal electrode 202 with an electrical insulator can degrade the acoustic output power performance of the transducer at higher input power levels (e.g., above approximately 30 W) (curve 703), where the acoustic output power of the transducer is lower than that without the electrical insulator. In contrast, the power performance of a selectively insulated transducer (curve 702) covered only by an electrical insulator (see, for example, reference) is significantly improved. Figures 4A to 4D The power performance (as described) is similar to that of a non-insulated ultrasonic transducer at all power levels (curve 701). However, it has been clearly considered that in some configurations and implementations, it may be suitable to have an electrical insulator covering only the internal electrodes 202. It should be understood that reference Figure 11 The operation of the described method can be appropriately modified based on the specific arrangement of the electrical insulators of the selectively insulating transducer.

[0111] In some embodiments suitable for, for example, renal denervation, the preferred range of electrical input power is about 30 W to about 50 W, corresponding to an acoustic output power of about 25 W to about 35 W. Figure 7 As observed, compared to a non-insulated transducer (curve 701) or a transducer with only the external electrode 203 coated (curve 702), coating both the internal electrode 202 and the external electrode 203 (curve 704) reduces the transducer's efficiency at these power input ranges. Without bias or limitation, it is theoretically considered that, compared to a transducer with non-insulated electrodes or a transducer with only the external electrode 203 insulated (or only the internal electrode 202 insulated), coating the internal electrode 202 and the external electrode 203 (or more generally, both electrodes) of the transducer 111 can adversely affect the transducer's lifespan due to the generation of more thermal and mechanical stress on the conduit (e.g., 102).

[0112] like Figure 7As observed, compared to a non-insulated transducer (curve 701), or a transducer where only the outer electrode 203 is covered by an electrical insulator (curve 702), covering only the inner electrode 202 with an electrical insulator (curve 703) reduces transducer efficiency over a power input range of approximately 30W to approximately 50W. Furthermore, theoretically, covering only the inner electrode 202 with an electrical insulator (e.g., 504) can also adversely affect the transducer's lifespan due to the generation of more thermal and mechanical stress, compared to a transducer with non-insulated electrodes or a transducer where only the outer electrode 203 is covered by an electrical insulator (e.g., 404). This may be because the cooling fluid (e.g., 213) inserted into the balloon (or blood in the balloon-free embodiment) may only come into contact with the electrical insulator (e.g., 504) covering the inner electrode 202 through an opening (e.g., 336) in the support assembly (e.g., 230), making it difficult for the cooling fluid to effectively absorb heat from the inner electrode 202. In contrast, when a cooling fluid (e.g., 213) is fed into a balloon (or blood in a balloon-free embodiment), the cooling fluid can come into more full contact with the electrical insulator (e.g., 404) covering the external electrode 203, and thus can more easily carry away heat that might otherwise be trapped by the electrical insulator (e.g., a parylene coating) covering the external electrode 203.

[0113] In the above embodiments, the piezoelectric transducer body is shown and described as being made of a hollow tube of piezoelectric material and having an inner surface and an outer surface, with internal electrodes and external electrodes respectively disposed on the inner surface and the outer surface. In alternative embodiments, the piezoelectric transducer body does not need to be hollow. For example, Figure 8A and 8B As shown, the ultrasonic transducer 811 may comprise a generally rectangular piezoelectric transducer body 801, which has first and second planar opposing surfaces (i.e., the top and bottom surfaces in this example) parallel to each other, on which planar and parallel electrodes 802 and 803 are disposed. For this purpose, electrodes 802 and 803 will be referred to as the lower electrode and upper electrode, respectively. See also Figure 9 According to some embodiments, the selectively insulated ultrasonic transducer 911 has a generally rectangular piezoelectric transducer body 801, wherein only the upper electrode 803 is covered by an electrical insulator 904. In such embodiments, the electrical insulator 904 provides both electrical and physical isolation between the upper electrode 803 and the conductive fluid in which the transducer is housed. See also Figure 10 According to some embodiments, the ultrasonic transducer 1011 has a generally rectangular piezoelectric transducer body 801, wherein only the lower electrode 802 is covered by an electrical insulator 1004. In such embodiments, the electrical insulator 1004 provides both electrical and physical isolation between the lower electrode 802 and the conductive fluid in which the transducer is housed.

[0114] In some embodiments, each of the selectively insulated ultrasonic transducers 911, 1011 may be placed within a balloon (e.g., 112) at least partially filled with a cooling fluid (e.g., 213), said cooling fluid being a conductive fluid used to cool portions of the body cavity BL in which the ultrasonic transducer may be located. As mentioned above, the conductive fluid may also cool the ultrasonic transducer itself. Reference has been made above. Figures 4A to 4D The embodiments described illustrate examples of types of conductive cooling fluids that can be used, and therefore need not be repeated. In an alternative embodiment, which may be referred to as the balloon-free embodiment, the selectively insulated ultrasonic transducer 911 or 1011 may be directly exposed to blood flowing through a body cavity in which the ultrasonic transducer can be positioned, in which case the conductive fluid includes blood.

[0115] Electrical insulators 904 and 1004 may be made of parylene, or of any or a combination of other types of materials described above with reference to electrical insulator 404. In a particular embodiment, the peripheral surface of one of the outer electrodes 803 (or 802) is covered with a parylene coating, and the opposing longitudinal ends of one of the electrodes 803 (or 802) are covered with epoxy resin. Other combinations of the aforementioned electrical insulator materials are also possible and are within the scope of the embodiments described herein.

[0116] Embodiments of the present invention are not limited to ultrasonic transducers having the specific shapes shown in the figures and described above. As an example, a cylindrical (or other shaped) hollow piezoelectric transducer body does not need to have a constant outer diameter, but may have longitudinally distal and / or proximal ends that are stepped, or more specifically, longitudinally distal and / or proximal ends with a smaller diameter compared to the rest of the transducer body (i.e., the non-stepped portion). Other variations are also possible and are within the scope of the embodiments described herein. The non-stepped portion of the transducer body may comprise the majority of the transducer length, for example, 50% to 95% or 60% to 90% of the total transducer length (e.g., 50% to 60%, 60% to 70%, 70% to 80%, 80% to 90%, 90% to 95%, 90% to 99%, percentages between the aforementioned ranges, etc.). However, in other embodiments, the non-stepped portion may extend along the total length of the transducer by less than 60% (e.g., 40% to 50%, 50% to 55%, 55% to 60%, less than 40%, etc.) or more than 95% (e.g., 95% to 96%, 96% to 97%, 97% to 98%, 98% to 99%, more than 99%, etc.) as needed or required.

[0117] Furthermore, it should be noted that when the piezoelectric transducer body is not hollow, for example in the reference... Figures 8A to 10In the described embodiments, the shape of the piezoelectric transducer body can be any shape other than a generally rectangular shape having parallel upper and lower surfaces. For example, see reference [link to previous section]. Figures 8A to 10 The upper and lower surfaces of the piezoelectric transducer body 801 shown may be concave or convex, or have some other non-planar shape, thus causing one or more of the lower electrode 802 and upper electrode 803 to have such an alternative shape. If one of such electrodes is coated with an electrical insulator, then the electrical insulator will also have such an alternative shape.

[0118] Additional options for the design and use of ultrasonic transducers and conduit-based ultrasonic delivery systems are provided in their entirety in the following patents and published applications incorporated herein by reference: U.S. Patent No. 6,635,054; U.S. Patent No. 6,763,722; U.S. Patent No. 7,540,846; U.S. Patent No. 7,837,676; U.S. Patent No. 9,707,034; U.S. Patent No. 9,981,108; U.S. Patent No. 10,350,440; U.S. Patent No. 10,456,605; U.S. Patent No. 10,499,937; and PCT Publication No. WO 2012 / 112165.

[0119] The transducers, devices, and systems described herein can be used to treat any suitable tissue, which may be referred to as the target anatomy. For example, the above description uses the system of the present invention to treat renal nerves (e.g., neuromodulation). It should be understood that body cavities in which the system of the present invention can be positioned for treatment are not necessarily limited to naturally occurring body cavities. For example, treatment may involve creating a body cavity within the tissue (e.g., using a drill, cannula, laser ablation, or the like), and then positioning suitable components within such a body cavity. Other suitable applications of the system of the present invention include ablation of pulmonary nerves and tissues causing venous or cardiac arrhythmias, nerves within the intervertebral disc, nerves within or outside the intervertebral disc, vertex nerves within the vertebrae, nerves within brain tissue, tissues causing cardiac arrhythmias within cardiac tissue, nerves along the bronchial tree, one or more esophageal branches of the vagus nerve, and one or more nerves around the bladder.

[0120] Figure 11 This is a high-level flowchart illustrating various embodiments of the method according to the present invention. See also... Figure 11Step 1102 involves providing a piezoelectric transducer having a first surface and a second surface spaced apart from each other and not intersecting, wherein a first electrode is disposed on the first surface and a second electrode is disposed on the second surface. Step 1104 involves covering only one of the first and second electrodes with an electrical insulator. Step 1106 involves inserting the piezoelectric transducer into a body cavity (e.g., a renal artery), and step 1108 involves exposing the piezoelectric transducer to a conductive fluid, the conductive fluid contacting the second electrode and being prevented (by the electrical insulator covering the first electrode) from contacting the first electrode. Step 1110 involves applying a voltage between the first and second electrodes when the piezoelectric transducer is exposed to the conductive fluid (and inserted into the body cavity BL), thereby causing the piezoelectric transducer to generate ultrasound. Step 1112 involves using an electrical insulator to prevent (and preferably prevent) a short circuit between the first and second electrodes when the piezoelectric transducer is exposed to the conductive fluid and a voltage is applied between the first and second electrodes.

[0121] In some embodiments, the method further includes placing a piezoelectric transducer inside a balloon. In such embodiments, exposing the piezoelectric transducer to a conductive fluid at step 1108 involves at least partially filling the balloon with the conductive fluid. As explained above, the conductive fluid may include, but is not limited to, at least one of saline, non-pure water, or a sodium lactate solution. In such embodiments, the method may also include inserting a balloon containing the piezoelectric transducer into a body cavity. In such embodiments, when the balloon is in the body cavity, a voltage is applied between the first and second electrodes to thereby cause the piezoelectric transducer to generate ultrasound.

[0122] In other embodiments referred to herein as balloon-free embodiments, step 1108 is performed by inserting a piezoelectric transducer into a body cavity through which blood flows, such that the piezoelectric transducer comes into contact with the blood. In such embodiments, the conductive fluid includes blood, and exposing the piezoelectric transducer to the conductive fluid at step 208 includes exposing the piezoelectric transducer to the blood.

[0123] Although several embodiments and examples have been disclosed herein, this application extends beyond the specific disclosed embodiments to other alternative embodiments and / or uses of the invention, as well as modifications and equivalents thereof. It has also been considered that various combinations or sub-combinations of specific features and aspects of the embodiments may be made and still fall within the scope of the invention. Therefore, it should be understood that various features and aspects of the disclosed embodiments may be combined or substituted with each other to form different modes of the disclosed invention. Accordingly, it is intended that the scope of the invention disclosed herein should not be limited to the specific disclosed embodiments described above, but should be determined only through a proper reading of the appended claims.

[0124] While the invention is open to various modifications and alternatives, specific examples have been shown in the drawings and described in detail herein. However, it should be understood that the invention is not limited to the specific forms or methods disclosed, but rather encompasses all modifications, equivalents, and alternatives falling within the scope of the various embodiments described and the appended claims. No method disclosed herein needs to be performed in the order stated.

Claims

1. A tissue therapy device (102), comprising: A balloon (112) configured to contain cooling fluid; and An ultrasonic transducer (111) is disposed within the balloon (112); The ultrasonic transducer (111) includes: Hollow tube of piezoelectric material with inner and outer surfaces (201); A first electrode disposed on one of the inner surface and the outer surface of the hollow tube (201) of the piezoelectric material; and A second electrode disposed on the other of the inner surface and the outer surface of the hollow tube (201) of the piezoelectric material, and An electrical insulator (404, 504) is coated on and covers the first electrode and is configured to prevent the first electrode from contacting the cooling fluid contained in the balloon (112), and thereby prevents electrical conduction between the first electrode and the second electrode when the cooling fluid contained in the balloon (112) is a conductive cooling fluid, wherein the second electrode is not covered by the electrical insulator and is therefore in contact with the cooling fluid contained in the balloon (112).

2. The tissue treatment device according to claim 1, wherein: The ultrasonic transducer (111) is configured to generate ultrasonic waves in response to a voltage applied between the first electrode and the second electrode; and When the cooling fluid contained in the balloon (112) is a conductive cooling fluid and the voltage is applied between the first electrode and the second electrode, the electrical insulator (404; 504) covering the first electrode prevents a short circuit between the first electrode and the second electrode.

3. The tissue treatment device according to claim 1, wherein the electrical insulator (404; 504) comprises one or more of the following: parylene; Cyanoacetate; Epoxy resin; nylon; Polytetrafluoroethylene (PTFE); Polyimide; Polyethylene; Polyethylene terephthalate; Polyvinyl chloride (PVC); and Synthetic diamond coating.

4. The tissue therapy device according to claim 3, wherein the electrical insulator (404; 504) comprises parylene.

5. The tissue therapy device of claim 4, wherein the electrical insulator (404; 504) comprises parylene having a thickness of 15 µm.

6. The tissue therapy device of claim 5, wherein the electrical insulator (404; 504) comprises three parylene coatings, each having a coating thickness of 5 µm, to collectively provide the parylene coating having a thickness of said 15 µm.

7. The tissue treatment device of claim 3, wherein the electrical insulator (404; 504) comprises a synthetic diamond coating.

8. The tissue treatment device according to any one of claims 1 to 7, wherein the electrical insulator (404; 504) comprises multiple layers of electrical insulating material.

9. The tissue treatment device according to any one of claims 1 to 7, wherein the first electrode covered by the electrical insulator (404) is disposed on the outer surface of the hollow tube (201) of the piezoelectric material.

10. The tissue treatment device according to any one of claims 1 to 7, wherein the hollow tube (201) of the piezoelectric material is cylindrical.

11. The tissue treatment device according to any one of claims 1 to 7, wherein the electrical insulator (404, 504) has a thickness selected in the range of 10 µm to 20 µm.

12. The tissue therapy device according to any one of claims 1 to 7, wherein the hollow tube (201) of the piezoelectric material is configured to transmit acoustic energy in the frequency range of 8.5 MHz to 9.5 MHz.

13. The tissue treatment device according to any one of claims 1 to 7, wherein: The hollow tube (201) of the piezoelectric material is configured to generate an acoustic output power in the range of 5 watts to 45 watts in response to an input electrical power in the range of 10 watts to 80 watts. The ultrasonic transducer (111) has a length of 6 mm. The outer diameter of the ultrasonic transducer (111) is 1.5 mm, and The inner diameter of the ultrasonic transducer (111) is 1 mm.

14. The tissue treatment device according to any one of claims 1 to 7, wherein: The first electrode includes a main peripheral surface and a longitudinal end; The portion of the electrical insulator (404; 504) covering the main peripheral surface of the first electrode is made of a first type of electrical insulating material; and Another portion of the electrical insulator (404; 504) covering the longitudinal end of the first electrode is made of the same or different material from the electrical insulating material covering the main peripheral surface of the first electrode.

15. The tissue therapy device of claim 14, wherein the electrical insulator (404; 504) comprises parylene disposed on and covering the outer circumference of the first electrode and epoxy resin disposed on and covering the longitudinal end of the first electrode.

16. The tissue therapy device according to any one of claims 1 to 7, further comprising a backing member (218) supporting the transducer (111), wherein the backing member (218) includes one or more support assemblies (230a; 230b) coupling the piezoelectric hollow tube (201) to the backing member (218), the one or more support assemblies (230a; 230b) defining one or more annular openings configured to receive the cooling fluid into the internal space of the piezoelectric hollow tube (201) between the backing member (218) and internal electrodes disposed on the inner surface of the piezoelectric hollow tube (201).

Images