Reinforced tissue treatment catheter and methods of manufacturing

Abstract

A tissue treatment catheter includes a catheter shaft (202) and a sleeve (302). The catheter shaft has a proximal shaft end, a distal shaft end opposite the proximal shaft end, and an outer shaft wall extending between the proximal shaft end and the distal shaft end. The catheter shaft (202) defines a first fluid lumen extending between the proximal shaft end and the distal shaft end. The sleeve (302) has a sleeve proximal end and sleeve distal end opposite the sleeve proximal end. The sleeve is bonded to the outer shaft wall of the catheter shaft with the sleeve adjacent to the proximal shaft end.

Description

Attorney Docket No.: POMD04601PRI_US01REINFORCED TISSUE TREATMENT CATHETERS AND METHODS OF MANUFACTURING THE SAMEPRIORITYThis application claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Nos. 63 / 696,790, filed September 19, 2024, and 63 / 696,793, filed September 19, 2024, all of which are incorporated herein by reference in their entireties to provide continuity of disclosure.BACKGROUNDFIEED

[0001] This application relates generally to minimally-invasive apparatuses, systems, and methods that provide energy delivery to a targeted anatomical location of a subject, and more specifically, to catheter-based, intraluminal apparatuses for the treatment of tissue, such as nerve tissue.BACKGROUND INFORMATION

[0002] High blood pressure, also known as hypertension, commonly affects adults. Left untreated, hypertension can result in renal disease, arrhythmias, and heart failure. In recent years, the treatment of hypertension has focused on interventional approaches to inactivate the renal nerves surrounding a renal artery. Autonomic nerves tend to follow blood vessels to the organs that they innervate. Intraluminal devices, such as catheters, may reach specific structures, such as the renal nerves, which are proximate to the lumens in which the catheters travel. Accordingly, catheter-based systems can deliver energy from within the lumens to inactivate the renal nerves in the vessel walls.

[0003] One approach to renal nerve deactivation uses radio frequency (RF) energy. The RF energy is delivered to a catheter having multiple electrodes placed against the intima of the renal artery to create an electrical field in the vessel wall and surrounding tissue. The electrical field results in resistive (ohmic) heating of the tissue to ablate the tissue and the renalAttorney Docket No.: POMD04601PRI_US01 nerve passing through that tissue. To treat all the renal nerves surrounding the renal arteries, the RF electrodes are repositioned several times around the inside of the renal artery.

[0004] Many of the problems associated with RF systems are solved by a system having an ultrasound transducer that emits one or more therapeutic doses of unfocused ultrasound energy. The ultrasound transducer can be mounted at a distal end of catheter, and the unfocused ultrasound energy can heat tissue adjacent to a body lumen within which the catheter (and the transducer) is disposed. Such unfocused ultrasound energy may, for example, ablate target nerves surrounding the body lumen, without damaging non-target tissue such as the inner lining of the body lumen or unintended organs outside of the body lumen. The unfocused ultrasound energy system may also include a balloon mounted at the distal end of the catheter around the ultrasound transducer. A cooling fluid can be circulated through the balloon to cool the body lumen during ultrasound energy delivery. Such a design enables creation of one or more ablation zones sufficient to achieve long-term nerve inactivation at different locations around the circumference of the blood vessel.SUMMARY

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

[0006] In an aspect of the present disclosure, a tissue treatment catheter includes a catheter shaft and a sleeve. The catheter shaft has a proximal shaft end, a distal shaft end opposite the proximal shaft end, and an outer shaft wall extending between the proximal shaft end and the distal shaft end. The catheter shaft defines a first fluid lumen extending between the proximal shaft end and the distal shaft end. The sleeve has a sleeve proximal end and sleeve distal end opposite the sleeve proximal end. The sleeve is bonded to the outer shaft wall of the catheter shaft with the sleeve adjacent to the proximal shaft end.Attorney Docket No.: POMD04601PRI_US01

[0007] In another aspect of the present disclosure, a tissue treatment catheter includes a catheter shaft and a sleeve. The catheter shaft has a proximal shaft end, a distal shaft end opposite the proximal shaft end, and an outer wall extending between the proximal shaft end and the distal shaft end. The catheter shaft defines a fluid lumen extending between the proximal shaft end and the distal shaft end. The sleeve is bonded to the outer shaft wall to reinforce the catheter shaft. The sleeve is configured to maintain a profile of the catheter shaft during use.

[0008] In another aspect of the present disclosure, a method of reinforcing a catheter shaft includes inserting the catheter shaft into a sleeve. The catheter shaft has an outer shaft wall. The catheter shaft defines a fluid lumen. The method also includes bonding the sleeve to the outer shaft wall of the catheter shaft. The sleeve is configured to maintain a profile of the catheter shaft to prevent deformation of the catheter shaft during use.

[0009] In an aspect of the present disclosure, a tissue treatment catheter includes a catheter shaft and a stiffening mandrel. The catheter shaft has an outer shaft wall. The catheter shaft defines a guidewire lumen and a mandrel lumen. The outer shaft wall has a collapsed section defining a guidewire port in the outer shaft wall such that the guidewire lumen is accessible through the guidewire port. The collapsed section forms a ramp including a proximal ramp end positioned at the outer shaft wall and distal ramp end positioned within the guidewire lumen. The ramp tapers outwardly from the distal ramp end longitudinally to the proximal ramp end. The collapsed section separates the guidewire lumen such that the guidewire lumen and the mandrel lumen are coaxially aligned. The stiffening mandrel includes a tapered segment having a proximal taper end and distal taper end. The tapered segment tapers longitudinally from the proximal taper end to the distal taper end such that the distal taper end of the tapered segment has a smaller cross-section than the proximal taper end. The stiffeningAttorney Docket No.: POMD04601PRI_US01 mandrel is disposed within the mandrel lumen. The collapsed section is conformed about at least a portion of the tapered segment.

[0010] In another aspect of the present disclosure, a tissue treatment catheter includes a catheter shaft and stiffening mandrel. The catheter shaft has an outer shaft wall. The catheter shaft defines a guidewire lumen and a mandrel lumen. The outer shaft wall has a collapsed section defining a guidewire port through the outer shaft wall. The collapsed section forms a ramp configured to slidingly receive a guidewire through the guidewire port and into the guidewire lumen from a surrounding environment. The collapsed section separates the guidewire lumen and mandrel lumen such that guidewire lumen and the mandrel lumen are coaxially aligned. The stiffening mandrel includes a tapered segment. The stiffening mandrel is disposed within the mandrel lumen. The tapered segment is configured to prevent bum- through of the catheter shaft when the tissue treatment catheter is exposed to elevated temperatures.

[0011] In another aspect of the present disclosure, a method of manufacturing a tissue treat catheter includes forming a guidewire port through an outer shaft wall of a catheter shaft. The catheter shaft defines a mandrel lumen coaxially aligned with a guidewire lumen. The method also includes collapsing the outer shaft wall to form a collapsed section of the catheter shaft to separate the mandrel lumen and the guidewire lumen. The collapse section forms a ramp that tapers outward from a distal ramp end longitudinally to a proximal ram end that is positioned at the outer shaft wall. The method also includes inserting a stiffening mandrel into the mandrel lumen. The stiffening mandrel has a tapered segment. The collapsed section is conformed about at least a portion of the tapered segment to fix the stiffening mandrel to the catheter shaft.

[0012] The above summary does not include an exhaustive list of all aspects of the present invention. It is contemplated that the invention includes all systems and methods that can be practiced from all suitable combinations of the various aspects summarized above, as well asAttorney Docket No.: PGMD04601PRI_US01 those disclosed in the Detailed Description below and particularly pointed out in the claims filed with the application. Such combinations have particular advantages not specifically recited in the above summary.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The various features of the present disclosure and the manner of attaining them will be described in greater detail with reference to the following description, claims, and drawings, wherein reference numerals are reused, where appropriate, to indicate a correspondence between the referenced items, and wherein:

[0014] FIG. 1 is a perspective view of a tissue treatment system, in accordance with an embodiment.

[0015] FIG. 2 is a plan view of a tissue treatment catheter, in accordance with an embodiment.

[0016] FIG. 3 is a perspective view of a medial catheter subassembly of a tissue treatment catheter, in accordance with an embodiment.

[0017] FIG. 4 is a perspective view of a lumen hub of a tissue treatment catheter, in accordance with an embodiment.

[0018] FIG. 5 is an exploded view of a lumen hub of a tissue treatment catheter, in accordance with an embodiment.

[0019] FIG. 6 a top view of a tissue treatment catheter, in accordance with an embodiment.

[0020] FIG. 7 is a sectional view of a tissue treatment catheter, in accordance with an embodiment.

[0021] FIG. 8 is sectional view of a tissue treatment catheter, in accordance with an embodiment.

[0022] FIG. 9 is a perspective view of a guidewire port of a tissue treatment catheter, in accordance with an embodiment.Attorney Docket No.: PGMD04601PRI_US01

[0023] FIG. 10 is a top view of a distal catheter subassembly of a tissue treatment catheter, in accordance with an embodiment.

[0024] FIG. 11 is a perspective view of a tissue treatment catheter inserted into a body lumen, in accordance with an embodiment.

[0025] FIG. 12 is a perspective view of a proximal catheter subassembly of a tissue treatment catheter, in accordance with an embodiment.

[0026] FIG. 13 is a perspective view of an electrical connector of a tissue treatment catheter, in accordance with an embodiment.

[0027] FIG. 14 is a sectional view of an electrical connector of a tissue treatment catheter, in accordance with an embodiment.

[0028] FIG. 15 is a sectional view of a tissue treatment catheter, in accordance with an embodiment.

[0029] FIG. 16 is a sectional view of a tissue treatment catheter, in accordance with an embodiment.

[0030] FIG. 17 is a flowchart of a method of reinforcing a tissue treatment catheter, in accordance with an embodiment.

[0031] FIG. 18 is a perspective view of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0032] FIG. 19 is a perspective view of a tissue treatment catheter delivered into a body lumen, in accordance with embodiments of the present disclosure.

[0033] FIG. 20 is a top view of a balloon including an ultrasound transducer secured to a distal end of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0034] FIG. 21 is a perspective view of a guidewire port of a tissue treatment catheter, in accordance with embodiments of the present disclosure.Attorney Docket No.: PGMD04601PRI_US01

[0035] FIG. 22 is a top view of a guidewire port of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0036] FIG. 23 is a cross-sectional view of a guidewire port of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0037] FIG. 24 is top view of a stiffening mandrel of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0038] FIG. 25 is a top view of another stiffening mandrel of tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0039] FIG. 26 is a top view of a guidewire port of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0040] FIG. 27 is a cross-sectional view, taken about line A-A of FIG. 26, of a distal wall portion of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0041] FIG. 28 is a cross-sectional view, taken about line B-B of FIG. 26, of a guidewire port of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0042] FIG. 29 is a cross-sectional view, taken about line C-C of FIG. 26, of a ramp of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0043] FIG. 30 is a cross-sectional view, taken about line D-D of FIG. 26, of a proximal wall portion of a tissue treatment catheter, in accordance with embodiments of the present disclosure.

[0044] FIG. 31 is a flowchart of a method of manufacturing a tissue treatment catheter, in accordance with embodiments of the present disclosure.DETAILED DESCRIPTION

[0045] Systems that use unfocused ultrasound energy to treat tissue, and methods of using the same are provided herein. In certain embodiments, acoustic -based tissue treatmentAttorney Docket No.: POMD04601PRI_US01 transducers, apparatuses, systems, and portions thereof, are provided. The systems may be catheter-based. The systems may be delivered intraluminally (e.g., intravascularly) so as to place a transducer within a target anatomical region of the subject, for example, within a suitable body lumen such as a blood vessel. Once properly positioned within the target anatomical region, the transducer can be activated to deliver unfocused ultrasonic energy radially outward so as to suitably heat, and thus treat, tissue within the target anatomical region. The transducer or piezoelectric material can be activated at a frequency, duration, and energy level suitable for treating the targeted tissue. In one non-limiting example, unfocused ultrasonic energy generated by the transducer or piezoelectric material or radio frequency (RF) energy transmitted by the electrodes may target select nerve tissue of the subject, and may heat such tissue in such a manner as to neuromodulate (e.g., fully or partially ablate, necrose, or stimulate) the nerve tissue.

[0046] Neuromodulating renal nerves may be used to treat various conditions, e.g., pulmonary hypertension, chronic kidney disease (CKD), cardiovascular disease, atrial fibrillation, stroke, autonomic nervous system for use in treating a variety of medical conditions, arrhythmia, heart failure, end stage renal disease, myocardial infarction, anxiety, contrast nephropathy, diabetes, non-alcoholic fatty liver disease, digestive disease, pancreatic cancer, other cancers, tumors, pain, polycystic kidney disease, asthma, sepsis, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), post-traumatic stress disorder (PTSD), sleep apnea, anxiety, depression, metabolic disorder, and insulin resistance, etc. It should be appreciated, however, that balloon catheters suitably may be used to treat other nerves in and / or around a body lumen and other conditions, e.g., the nerves in and / or around a renal artery, superior mesenteric artery, inferior mesenteric artery, femoral artery, pelvic artery, portal vein, hepatic artery, common hepatic artery, gastroduodenal artery, splenic artery, gastric artery, celiac trunk, pulmonary artery, pulmonary vein, aorta, vena cava, etc., e.g., sympatheticAttorney Docket No.: POMD04601PRI_US01 nerves of the hepatic plexus within a hepatic artery responsible for blood glucose levels important to treating diabetes, or any suitable tissue, e.g., heart tissue triggering an abnormal heart rhythm, and is not limited to use in treating (e.g., neuromodulating) renal nerve tissue. In another example, a tissue treatment catheter is used to ablate sympathetic nerves of the renal arteries and a hepatic artery to treat diabetes or other metabolic disorders. In certain embodiments, the tissue treatment catheters are used to treat an autoimmune and / or inflammatory condition, such as rheumatoid arthritis, sepsis, Crohn’s disease, ulcerative colitis, and / or gastrointestinal motility disorders by neuromodulating sympathetic nerves within one or more of a splenic artery, celiac trunk, superior or inferior mesenteric artery. In certain embodiments, the tissue treatment catheter is used to ablate nerve fibers in the celiac ganglion and / or renal arteries to treat hypertension. In certain embodiments, the transducers are used to treat pain, such as pain associated with pancreatic cancer, by, e.g., neuromodulating nerves that innervate the pancreas. Ultrasound or RF energy may also be used to ablate nerves of both the pulmonary vein and the renal arteries to treat atrial fibrillation. In still other examples, ultrasound or RF energy may additionally or alternatively be used to ablate nerves innervating a carotid body in order to treat hypertension and / or chronic kidney disease.

[0047] Existing tissue treatment catheters track over a guidewire to access a target anatomical region. Such tissue treatment catheters may include a guidewire lumen having a guidewire port. The guidewire port may be a rapid exchange port, which is typically a slot in a catheter wall midway between a distal end and a proximal end of the catheter. A guidewire can exit the guidewire lumen through the guidewire port. The guidewire port is formed either by removing material from the catheter wall or deforming, e.g., by reflowing, a portion of the catheter wall. Where the guidewire port is formed by a reflowing process the catheter wall is exposed to heat to melt a portion of the catheter wall. In some embodiments, the catheter wall is reflowed around a portion of a stiffening mandrel to fix the stiffening mandrel to the catheter.Attorney Docket No.: POMD04601PRI_US01The stiffening mandrel may improve the pushability of the catheter during use. However, the reflowing process may result in “burn-through” and a defective catheter, when the reflowed material thins or evacuates a space between the stiffening mandrel and a shaping mandrel leading to a hole. The hole can create procedural risks, such as a risk of fluid leakage during an interventional procedure. Burn-through may be exacerbated by the stiffening mandrel and / or the shaping mandrel positioned within catheter. Specifically, the stiffening mandrel and / or the shaping mandrel may be made of a thermally conductive material that can increase the instances of bum-through defects during manufacturing.

[0048] As described below, embodiments can include a tissue treatment catheter and methods of manufacturing the tissue treatment catheter that reduce the instances of bum- through. Specifically, the tissue treatment catheter may include a stiffening mandrel having a tapered segment that is configured to reduce the instances of burn-through defects during a reflow process. The tapered segment can significantly reduce the instances of burn-through when compared to conventional stiffening mandrels, which have a uniform profile.

[0049] The tissue treatment catheter may be an ultrasound-based tissue treatment catheter, used to deliver unfocused ultrasonic energy radially outwardly to treat tissue within a target anatomical region, such as the renal nerves within a renal artery. Alternatively, the tissue treatment system may be used in other applications, such as to treat sympathetic nerves of the hepatic plexus within a hepatic artery. Thus, reference to the system as being a renal denervation system, or being used in treating, e.g., neuromodulating, renal nerve tissue is not limiting. Additionally, the tissue treatment catheter or components thereof may be useable with any appropriate catheter system. For example, the tissue treatment catheter may be a catheter system for stent placement or thrombectomy procedures. More specifically, the tissue treatment catheter may be any catheter system that enters a patient’s vasculature via a hemostasis valve. The stiffening mandrel as described below may be used in any catheterAttorney Docket No.: POMD04601PRI_US01 system to contribute the rigidity of the catheter shaft. As such, reference to the tissue treatment catheter being an ultrasound-based tissue treatment catheter is not limiting.

[0050] Tissue treatment catheters must navigate tortuous paths to reach target anatomies for denervation procedures. To reach target anatomies treatment catheter shafts must be flexible. However, the flexibility that allows for the catheter shaft to navigate to the target anatomy can also make the catheter shaft delicate and prone to deformation that may obstruct lumens in the catheter. Deformation of the catheter can result from the flowing of inflation fluids through the catheter shaft. Specifically, the catheter shaft may experience pressure or vacuum forces during a procedure, e.g., during a renal denervation procedure, near the proximal end of the catheter shaft great enough to cause deformation of the catheter. Accordingly, there is a need for devices and methods for reinforcing tissue treatment catheters.

[0051] As described below, embodiments of the present disclosure reinforce the shaft of tissue treatment catheters to reduce the instances of deformation. Specifically, a sleeve is bonded to a portion of the catheter shaft to reinforce the tissue treatment catheter where the shaft is most likely to be deformed by exposure to pressure or vacuum forces.

[0052] In various embodiments, description is made with reference to the figures. However, certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, numerous specific details are set forth, such as specific configurations, dimensions, and processes, in order to provide a thorough understanding of the embodiments. In other instances, well-known processes and manufacturing techniques have not been described in particular detail in order to not unnecessarily obscure the description. Reference throughout this specification to “one embodiment,” “an embodiment,” or the like, means that a particular feature, structure, configuration, or characteristic described is included in at least one embodiment. Thus, the appearance of the phrase “one embodiment,” “an embodiment,” or theAttorney Docket No.: PGMD04601PRI_US01 like, in various places throughout this specification are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

[0053] The use of relative terms throughout the description may denote a relative position or direction. For example, “distal” may indicate a first direction. Similarly, “proximal” may indicate a second direction, opposite to the first direction. Such terms are provided to establish relative frames of reference, however, and are not intended to limit the use or orientation of a tissue treatment catheter to a specific configuration described in the various embodiments below.

[0054] Referring to FIG. 1, an example tissue treatment system 100 is illustrated in accordance with embodiments of the present disclosure. The tissue treatment system 100 is shown as including a tissue treatment catheter 102, a controller 120, and a connection cable 140. In certain embodiments, the tissue treatment catheter 102 includes an ultrasound transducer 111 within a balloon 112. The tissue treatment system 100 can include a reservoir 110 and a control mechanism (not shown) to circulate an inflation fluid to inflate the balloon 112 within a target anatomy and to control activation of the ultrasound transducer 111 to deliver energy, e.g., acoustic energy, to the target anatomy.

[0055] Referring to FIG. 2, a plan view of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The tissue treatment catheter 102 can have a modular construction. More particularly, the tissue treatment catheter 102 may include an assembly composed of several subassemblies. The subassemblies can divide the overall assembly of the tissue treatment catheter 102 into segments that are manufactured at the subassembly level and then combined to form the overall assembly. The tissue treatment catheter 102 may have a proximal catheter subassembly 204, a medial catheter subassemblyAttorney Docket No.: PGMD04601PRI_US01206, and a distal catheter subassembly 208. Each subassembly 204, 206, 208 will be described in turn hereinbelow.

[0056] Additionally referring to FIG. 3, a perspective view of the medial catheter subassembly 206 of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The medial catheter subassembly 206 can include a catheter shaft 202, a sleeve 302, fluid tubes 304, 306, e.g., a first fluid tube 304 and a second fluid tube 306, and a lumen hub 308. The catheter shaft 202 can extend from a distal shaft end 201 to a proximal shaft end 203 along a central axis 205.

[0057] The lumen hub 308 can have a symmetric configuration about the central axis 205. Inflow and outflow fluid lumens, e.g., the first fluid tube 304 and the second fluid tube 306, can extend laterally outward from the central axis 205 of the catheter shaft 202 in a wye configuration. The symmetric configuration of the fluid tubes 304, 306 can provide ease of use because fluid lumens from the controller 120 can be more easily connected to fluid connectors 305 at the proximal ends of the fluid tubes 304, 306 on opposite sides of the central axis 205. Each fluid tube 304, 306 of the medial catheter subassembly 206 may extend proximally to respective fluid connectors 305. The fluid connectors 305 may be connectors that receive and / or attach to a respective fluid transfer device. For example, the fluid connectors 305 may be luer connectors to receive and connect to fluid fittings of the controller 120. Fluid may therefore be communicated through the fluid tubes 304, 306 from the controller 120 to the balloon 112. More particularly, the fluid tubes 304, 306 can be in fluid communication with the fluid lumens (e.g., fluid lumens 804a, 804b of FIG. 8) of the catheter shaft 202 to transfer fluid between the controller 120 and the balloon 112.

[0058] Referring to FIG. 4, the lumen hub 308 provides a point to fluidly couple the several lumens of the tissue treatment catheter 102. For example, within the lumen hub 308, the first fluid tube 304 and the second fluid tube 306 may be fluidly coupled to the catheter shaft 202.Attorney Docket No.: PGMD04601PRI_US01The lumen hub 308 can include an innermold 402 that is partially surrounded by a hub shell 404. The innermold 402 can include several strain reliefs at locations where the lumen hub 308 connects to adjacent structures. For example, the lumen hub 308 can have a distal strain relief 406 attached to the catheter shaft 202, e.g., at the proximal shaft end 203. The lumen hub 308 may also include strain reliefs in a proximal region. For example, proximal strain reliefs 408 can connect to the fluid tubes 304, 306 that extend from the lumen hub 308 in the wye configuration.

[0059] Additionally referring to FIG. 5, an exploded view of the lumen hub 308 is shown in accordance with embodiments of the present disclosure. The exploded view reveals that the innermold 402 can be a monolithically formed body having various features including the distal strain relief 406 and the proximal strain reliefs 408. Each of the strain reliefs can define respective lumens to receive respective tubular structures. For example, the distal strain relief 406 can receive and contain the proximal shaft end 203 of the catheter shaft 202, and the proximal strain reliefs 408 can contain distal ends of the first fluid tube 304 and the second fluid tube 306. Channels can extend through the innermold 402 to interconnect the strain relief lumens such that the lumens passing through the fluid tubes 304, 306 can be in fluid communication with the fluid lumens passing through the catheter shaft 202.

[0060] In certain embodiments, the innermold 402 can also define a central cable channel 502 extending longitudinally through the distal strain relief 406 and exiting the innermold 402 at a proximal face 550 of the innermold 402. The catheter shaft 202 can be received within the distal strain relief 406, and a cable lumen (e.g., cable lumen 808 of FIG. 8) of the catheter shaft 202 can align with the central cable channel 502. Accordingly, electrical cables can extend longitudinally through the catheter shaft 202 and the innermold 402 to a proximal notch 504.

[0061] The proximal notch 504 can be a cutout in the innermold 402 sized and shaped to receive a strain relief of the proximal catheter subassembly 204, as described below. TheAttorney Docket No.: POMD04601PRI_US01 proximal notch 504 can have a U-shaped profile, as shown. The proximal notch 504 of the innermold 402 can be between the first fluid tube 304 and the second fluid tube 306 when the tubes are inserted into the proximal strain reliefs 408. The proximal notch 504 provides a receiving cavity between two halves of the hub shell 404. More particularly, when the hub shell 404 is clamped onto and surrounds the innermold 402, the space defined between the hub shell 404 and within the proximal notch 504 forms the receiving cavity to receive the proximal catheter subassembly 204 and secure the proximal catheter subassembly 204 and the medial catheter subassembly 206 together.

[0062] The hub shell 404 can include several components that are assembled to each other around the innermold 402. For example, the hub shell 404 can include a first hub shell 508, shown above the innermold 402, and a second hub shell 510, shown below the innermold 402. The components of the hub shell 404 can be attached and / or bonded to each other to form an outer housing surrounding the innermold 402. The hub shell 404 may be formed from a stiffer material, e.g., polycarbonate, than the innermold 402. For example, the innermold 402 may be formed from an injection molded elastomer or similarly soft durometer material. Accordingly, the innermold 402 may be flexible to allow the catheter shaft 202 and the fluid tubes 304, 306 to easily flex, and the hub shell 404 can provide rigidity to support the body of the innermold 402.

[0063] The hub shell 404 may include one or more posts 512 extending orthogonal to an inner wall of the hub shell 404. The posts 512 can extend upward to pass through corresponding post holes 514 defined in the body of the innermold 402 when the hub shell 404 is assembled onto the innermold 402. The posts 512 can engage mating components (not shown) of the hub shell 404 to secure the first hub shell 508 to the second hub shell 510 with the innermold 402 disposed therebetween. For example, the posts 512 extending from the second hub shell 510 can engage and connect to corresponding clips or tubes in the first hubAttorney Docket No.: POMD04601PRI_US01 shell 508. When engaged, the posts 512 can hold the hub shells 508, 510 together around the innermold 402.

[0064] Referring to FIGS. 3, 6-8, the sleeve 302 is bonded to the outer shaft wall 810 of the catheter shaft 202 to reinforce the catheter shaft 202. The sleeve 302 is configured to maintain the profile of the catheter shaft 202 during use, e.g., during a renal denervation procedure. The sleeve 302 may be formed of a more rigid material than the catheter shaft 202. For example, the sleeve 302 may be formed of a polycarbonate, a polyimide, a polyurethane, or an elastomer. For example, the sleeve 302 may be made of Pellethane®, Nylon, PeBax®, polyetheretherketone (PEEK), or Isothane® 5075D. Specifically, the sleeve 302 may be made of a material with a higher durometer than that of the catheter shaft 202. The sleeve 302 may have durometer in the range of Shore 60D to Shore 80D, e.g., Shore 75D. In embodiments, the sleeve 302 has a durometer greater than or equal to Shore 75D.

[0065] The rigidity of the sleeve 302 may resist deformation of the catheter shaft 202, e.g., collapsing of a fluid lumen 804. Specifically, the sleeve 302 may resist deformation as a result of positive pressures or negative pressures, i.e., vacuum pressures, experienced by the catheter shaft 202 during use. The sleeve 302 may also thermally insulate the catheter shaft 202. The catheter shaft 202 may become more prone to deformation when exposed to elevated temperatures. More particularly, the catheter shaft 202 may be made of a material that softens or becomes more pliable when exposed to temperatures in the range of 30 degrees Celsius to 40 degrees Celsius, e.g., 37 degrees Celsius. For example, the catheter shaft 202 may be warmed by the inflation fluid as it is circulated and draws heat away from the ultrasound transducer 111, as described below. Additionally or alternatively the catheter shaft 202 may be warmed by the patient’ s body heat during the course of a procedure.

[0066] The sleeve 302 may be positioned along the catheter shaft 202 at or near the proximal shaft end 203 of the catheter shaft 202 and extend therefrom along the catheter shaftAttorney Docket No.: POMD04601PRI_US01202 towards the distal shaft end 201 of the catheter shaft 202. The proximal shaft end 203 of the catheter shaft 202 may experience the greatest intensity of deformation forces. For example, the pressures applied to the fluid lumens 804 may be greatest at the proximal shaft end 203 and equilibrate along the length of the catheter shaft 202. For example, pressure or vacuum forces may equalize along the length of the catheter shaft 202 as a result of loss of pressure head. In embodiments where the catheter shaft 202 may experience vacuum forces, the fluid lumens 804 may be filled with the inflation fluid to oppose the vacuum forces. The sleeve 302 may extend along this length of the catheter shaft 202 to reinforce the outer shaft wall 810 and resist obstruction of the fluid lumens 804.

[0067] The sleeve 302 may have a sleeve proximal end 602 and a sleeve distal end 604. The sleeve proximal end 602 may be flush with the proximal shaft end 203 of the catheter shaft 202. A portion of the sleeve 302, including the sleeve proximal end 602, may be disposed within the distal strain relief 406. In some embodiments, the sleeve proximal end 602 may abut the distal strain relief 406, as shown in FIG. 7. The sleeve 302 may have a length that extends past a point on the catheter shaft 202 at which the pressure or vacuum forces applied to the fluid lumens 804 has equalized to a level unlikely to deform the catheter shaft 202. In embodiments, the sleeve 302 may have a length in the range of 4 inches to 10 inches, e.g., 6 inches or 8 inches.

[0068] In some embodiments, the sleeve 302 may visually indicate to a clinician that the tissue treatment catheter 102, and more specifically the distal catheter subassembly 208, has entered the patient’s body, e.g., the target lumen. For example, the tissue treatment system 100 may include a guide catheter (not shown) to deliver the tissue treatment catheter 102 to a target anatomy. The tissue treatment catheter 102, specifically the distal catheter subassembly 208, may be deployed into a body lumen from a distal end of the guide catheter by moving the tissue treatment catheter 102 distally through the guide catheter. When the sleeve distal end 604 ofAttorney Docket No.: POMD04601PRI_US01 the sleeve 302 aligns with a proximal end of the guide catheter, the sleeve 302 visually indicates to a clinician that the tissue treatment catheter 102 is within the body lumen and deployed from the guide catheter.

[0069] In some embodiments, the sleeve 302 includes deployment indicators disposed along the length of the sleeve 302 from the sleeve distal end 604 to the sleeve proximal end 602. The proximal end of the guide catheter may align with a respective deployment indicator along the sleeve 302 to visually indicate to a clinician the distance the tissue treatment catheter 102 has been deployed from the distal end of the guide catheter. Each deployment indicator may represent a known distance between the distal shaft end 201 and the distal end of the guide catheter. For example, the distance between each deployment indicator may be 10 millimeters. In such an embodiment, where the third deployment indicator from the sleeve distal end 604 is aligned with the proximal end of the guide catheter, the distal shaft end 201 is 30 millimeters from the distal end of the guide catheter. In some embodiments, the distance between each deployment indicator is equal to the length of the distal catheter subassembly 208. Specifically, the distance between each deployment indicator may be equal the length of the balloon 112. As such, inserting or withdrawing the tissue treatment catheter 102 by one deployment indicator moves the distal catheter subassembly 208 one balloon length.

[0070] Additionally or alternatively, the sleeve 302 may be configured to resist buckling of the catheter shaft 202 as result of compressive forces applied thereto. For example, in embodiments, manipulation by a clinician may cause bending, pinching, or crushing of the catheter shaft 202 during a procedure. The sleeve 302 may resist buckling under these external compressive or bending forces. Additionally or alternatively, the sleeve 302 may resist deformation from compression from hemostasis valves. The sleeve 302 may make the tissue treatment catheter 102 compatible with any commercially available hemostasis valve. ThisAttorney Docket No.: POMD04601PRI_US01 may reduce need for healthcare facilities to maintain an inventory of several different hemostasis valves.

[0071] Particularly referring to FIG. 8, the sleeve 302 surrounds the catheter shaft 202. The sleeve 302 has a cross-sectional profile similar to that of the catheter shaft 202. As shown, both the sleeve 302 and catheter shaft 202 have a circular cross-sectional profile. The sleeve 302 may be slightly larger in diameter than the catheter shaft 202 such that a gap 801 can be defined therebetween. The gap 801 may ease insertion of the catheter shaft 202 into the sleeve 302 during assembly of the tissue treatment catheter 102. The gap 801 may be filled with adhesive to bond the sleeve 302 and the catheter shaft 202 together. The adhesive may fix the sleeve 302 and the catheter shaft 202 such that the sleeve 302 and the catheter shaft 202 do not move radially or longitudinally with respect to each other. Fixing radial motion of the sleeve 302 relative to the catheter shaft 202 may further prevent deformation of the catheter shaft 202. For example, where vacuum is applied to the fluid lumens 804, the sleeve 302 may resist collapsing of the outer shaft wall 810 and hold the fluid lumen 804 open. In embodiments, the adhesive may be, but are not limited to, cyanoacrylates, acrylics, or polyurethanes. In particular embodiments, the sleeve 302 is frictionally engaged with the catheter shaft 202 to affix the sleeve 302 thereto.

[0072] In embodiments, the sleeve 302 is bonded to the catheter shaft 202 by a reflowing process that shrinks the sleeve 302 about the catheter shaft 202. Once bonded, the sleeve 302 engages the outer shaft wall 810 of the catheter shaft 202 and the gap 801 is eliminated. The reflowing process may include compressing the sleeve 302 such that the gap 801 is eliminated and the sleeve is in physical contact with catheter shaft 202 prior to applying heat to the sleeve 302 to reflow the sleeve 302. The sleeve 302 may distribute forces experienced by the catheter shaft 202 and, thus, resist deformation forces. In embodiments where the sleeve 302 is adhered by reflowing, the sleeve 302 may be made of a heat shrink polymer, e.g., a polyolefin. In someAttorney Docket No.: PGMD04601PRI_US01 embodiments, the sleeve 302 is bonded to the catheter shaft 202 by a reflow process and by an adhesive.

[0073] The catheter shaft 202 defines a plurality of lumens. The catheter shaft 202 may define one or more fluid lumens 804, a guidewire lumen 806, and a cable lumen 808. The fluid lumen(s) 804 may be in fluid communication with the fluid tubes 304, 306 such that the inflation fluid may be flowed therethrough. The fluid lumens 804 can have semi-circular (or non-circular) cross-sectional profiles to efficiently utilize the available space of the catheter shaft 202. A first fluid lumen 804a can be located on a first side of the catheter shaft 202, and a second fluid lumen 804b may be located on an opposite side of the catheter shaft 202. The first fluid lumen 804a and the second fluid lumen 804b can be in fluid communication with each other through the balloon 112.

[0074] The cable lumen 808 may be located below the guidewire lumen 806 and between the fluid lumens 804. In an embodiment, one or more electrical cables are received within the cable lumen 808. The electrical cable(s) can extend through the cable lumen 808 from a proximal connection point within the lumen hub 308 to a distal termination point distal at the distal shaft end 201. Accordingly, the electrical cable(s) can deliver energy from the controller 120 to the ultrasound transducer 111.

[0075] The guidewire lumen 806 may allow the tissue treatment catheter 102 to be tracked over a guidewire (e.g., the guidewire 1104 of FIG. 11) to a target vessel 1900. The guidewire lumen 806 can have a circular cross-sectional profile to conform to a cylindrical outer surface of the guidewire. The guidewire lumen 806 may be radially offset from the central axis 205 of the catheter shaft 202.

[0076] Referring to FIG. 9, the guidewire lumen 806 terminates in a guidewire port 900 defined through the outer shaft wall 810 of the catheter shaft 202. More particularly, the guidewire port 900 can extend through the outer shaft wall 810 of the catheter shaft 202 intoAttorney Docket No.: POMD04601PRI_US01 the guidewire lumen 806. For example, the guidewire port 900 can be a hole, cut, slit, skive, etc. formed in the outer shaft wall 810. The guidewire port 900 therefore places the guidewire lumen 806 in fluid communication with a surrounding environment 1822 and allows a guidewire to pass through the outer shaft wall 810 from the guidewire lumen 806 to the surrounding environment 1822. Accordingly, the guidewire port 900 can provide a rapid exchange port (RX port) acting as an exit hole formed in the outer shaft wall 810 of the catheter shaft 202 to allow the guidewire to track through a portion of the catheter shaft 202. More particularly, the tissue treatment catheter 102 can be tracked over the guidewire in an RX fashion. The guidewire port 900 is positioned along the catheter shaft 202 between distal shaft end 201 of the catheter shaft 202 and the sleeve distal end 604.

[0077] Referring to FIG. 10, the distal catheter subassembly 208 is shown in accordance with embodiments of the present disclosure. The distal catheter subassembly 208 may include the balloon 112 and the ultrasound transducer 111 within the balloon 112. The balloon 112 defines an interior 1002. The interior 1002 is in fluid communication with the fluid lumen(s) 804 and can receive an inflation fluid. The interior 1002 of the balloon 112 can be filled with inflation fluid and the ultrasound transducer 111 surrounded by the inflation fluid. The inflation fluid may inflate the balloon 112 and additionally act as a cooling fluid to cool the ultrasound transducer 111 during operation. The inflation fluid and / or cooling fluid may be, but is not limited to, water, dextrose, or saline. The inflation fluid may be circulated into and out of the interior 1002 of the balloon 112. For example, the inflation fluid may flow into the balloon 112 through the first fluid lumen 804a and flow out of the balloon 112 through the second fluid lumen 804b.

[0078] The ultrasound transducer 111 is located or disposed in the interior 1002 of the balloon 112. More particularly, the ultrasound transducer 111 is contained within the interior 1002. The ultrasound transducer 111 may include a cylindrical hollow tube made of aAttorney Docket No.: POMD04601PRI_US01 piezoelectric material (e.g., lead zirconate titanate (PZT), etc.). For example, the piezoelectric material can be lead zirconate titanate 8 (PZT8), which is also known as Navy III Piezo Material. The ultrasound transducer 111 may be electrically coupled to an energy source, e.g., contained within the controller 120. A voltage and alternating current may be applied to ultrasound transducer 111 to cause the piezoelectric material to vibrate and emit ultrasonic waves.

[0079] Referring to FIG. 11, a distal portion of the tissue treatment catheter 102, including the distal catheter subassembly 208, may be inserted into a body lumen 1100 of a subject or patient. The body lumen 1100 may be a blood vessel 1900, e.g., a renal artery, that has several nerves 1101 in an outer layer, e.g., adventitia layer, of the body lumen 1100. The balloon 112 may be inflated with the inflation fluid so as to contact the interior surface, e.g., an intima, of the body lumen 1100. The balloon 112 may be maintained at a specified size by pushing the inflation fluid through and / or pulling the inflation fluid out of the balloon 112 at a specified flow rate. In certain embodiments, the ultrasound transducer 111 may be used to output an acoustic signal when the balloon 112 fully occludes the body lumen 1100 of a target vessel 1900. The balloon 112 may center the ultrasound transducer 111 within the body lumen 1100. In certain embodiments, e.g., suitable for renal denervation, the balloon 112 is inflated while inserted in the body lumen 1100 of the patient during a procedure at a working pressure of about 10 to about 30 psi using the inflation fluid. The balloon 112 may be or include a compliant, semi-compliant, or non-compliant medical balloon 112. The balloon 112 is sized for insertion in the body lumen 1100 and, in the case of insertion into the renal artery, for example, the balloon 112 may be selected from available sizes including outer diameters of 3.5, 4.2, 5, 6, 7, or 8 mm, but not limited thereto. When activated the ultrasound transducer 111 can deliver the acoustic signal to a vessel wall 1112 of the target vessel 1900.Attorney Docket No.: PGMD04601PRI_US01

[0080] Referring to FIG.12, a perspective view of a proximal catheter subassembly 204 of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The proximal catheter subassembly 204 includes an electrical connector 1210 at a distal end and a proximal connector 1214 at a proximal end. An extension cable 1212 extends between the electrical connector 1210 and the proximal connector 1214. The extension cable 1212 can be a lightweight and thin cable. Accordingly, the extension cable 1212 may not add substantial weight to the proximal end of the tissue treatment catheter 102. By contrast, the proximal connector 1214 can attach to a bulky electrical cable, e.g., the connection cable 140, that then extends to attach to the controller 120. The extension cable 1212 can separate the catheter shaft 202 from the bulky cable and may not pull the catheter shaft 202 off of an operating table when the tissue treatment catheter 102 is connected to the bulky cable.

[0081] Referring to FIG. 13, the electrical connector 1210 may include a connector housing 1302 at a distal end. The connector housing 1302 can have a tubular, rectangular body to insert into the proximal notch 504 of the lumen hub 308. One or more ridges 1304 can extend peripherally about the connector housing 1302. The ridges 1304 can extend laterally from the connector housing 1302 to engage mating features of the innermold 402. Each ridge 1304 can provide a key that can engage a corresponding slot 1502 of the lumen hub 308 to secure the electrical connector 1210 to the lumen hub 308 when the proximal catheter subassembly 204 is attached to the medial catheter subassembly 206.

[0082] Referring to FIG. 14, in cross-section, a cavity within the connector housing 1302 can be seen. The cavity can contain a mending board 1404. The mending board 1404 within the connector housing 1302 can be an electrical component that provides an electrical interconnect between an extension cable wire 1406 of the proximal catheter subassembly 204 and the electrical cables 1504 of the medial catheter subassembly 206. The extension cable wire 1406 can be a twisted wire pair or a coaxial cable, for example. The mending board 1404Attorney Docket No.: POMD04601PRI_US01 can have a printed circuit board construction, including a substrate 1408 and two or more contact pads. More particularly, the mending board 1404 can include distal electrical contacts 1410 deposited on the substrate 1408, and proximal electrical contacts 1412 deposited on the substrate 1408. The distal and proximal electrical contacts 1410, 1412 can be interconnected through vias and / or traces passing through the substrate 1408. Accordingly, the proximal electrical contacts 1412 can be electrically connected to the distal electrical contact 1410. The mending board 1404 may include several pairs of contact pads. Each pair can include a respective proximal pad electrically connected to a respective distal pad. For example, the mending board 1404 can include two pairs of contact pads, as shown.

[0083] An electrical connection can be made between the electrical cables 1504 of the medial catheter subassembly 206 and the extension cable wire 1406 of the proximal catheter subassembly 204 through the mending board 1404. As shown, the extension cable wire 1406 can extend from the proximal electrical contacts 1412 to the proximal connector 1214 of the extension cable 1212. Similarly, the electrical cables 1504, which extends through the cable lumen 808, can connect to the distal electrical contact 1410. Accordingly, an electrical path from the proximal connector 1214 through the mending board 1404 to the ultrasound transducer 111 can be provided by the interconnected extension cable wires 1406 and electrical cables 1504. At the subassembly level, the extension cable wire 1406 can be attached to the proximal electrical contacts 1412 of the mending board 1404. The connected extension cable wire 1406 can then be sealed, e.g., by adding a sealant layer over the contact pads, to protect the electrical connection.

[0084] Referring to FIG. 15, a sectional view of the tissue treatment catheter 102 at the connection between the proximal catheter subassembly 204 and the distal catheter subassembly 208 is shown in accordance with embodiments of the present disclosure. The proximal catheter subassembly 204 and the medial catheter subassembly 206 may quickly and easily combined.Attorney Docket No.: PGMD04601PRI_US01Specifically, the electrical connector 1210 can be secured to the lumen hub 308. More particularly, the lumen hub 308 may define a slot 1502 to receive the ridges 1304 radiating from the connector housing 1302. Accordingly, the electrical connector 1210 can fit into the lumen hub 308 and may be secured by a key-and-slot mechanism. The electrical cables 1504 can be contacted and to the distal electrical contacts 1410 to deliver electrical energy to the distal catheter subassembly 208. More particularly, to deliver electrical energy to the ultrasound transducer 111.

[0085] Referring to FIG. 16, a sectional view of a tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The tissue treatment catheter 102 comprises a single-piece strain relief 406, 408. The single-piece strain relief may be overmolded over the lumen hub 308. The single-piece strain relief 406, 408 functions similar to the proximal and distal strain reliefs shown, e.g., in Fig. 5. One advantage of providing a single-piece strain relief 406, 408 instead of three distinct strain reliefs 406, 408 is a simplified construction of the tissue treatment catheter 102.

[0086] Referring to FIG. 17, a method 1600 of reinforcing a tissue treatment catheter in accordance with embodiments of the present disclosure is described with reference to the tissue treatment catheter 102 of FIGS. 1-16.

[0087] At operation 1602 the catheter shaft 202 is inserted into the sleeve 302. The catheter shaft 202 may be inserted into the sleeve 302 manually. In some embodiments, the catheter shaft 202 is inserted into the sleeve 302 by an automated process.

[0088] At operation 1604, optionally, the sleeve 302 is positioned along the length of the catheter shaft 202. The sleeve 302 may be positioned such that the sleeve proximal end 602 is flush with the proximal shaft end 203 of the catheter shaft 202. In embodiments, the sleeve proximal end 602 and the proximal shaft end 203 are made flush by cutting away a segment of both the sleeve 302 and the catheter shaft 202 and, thus, the sleeve 302 need not be positionedAttorney Docket No.: POMD04601PRI_US01 with respect to the catheter shaft 202. In embodiments, the sleeve proximal end 602 may be spaced apart from the proximal shaft end 203.

[0089] At operation 1606 the sleeve 302 is bonded to the catheter shaft 202. The sleeve 302 may be bonded to the catheter shaft 202, specifically the outer shaft wall 810 of the catheter shaft 202, by an adhesive. As described above, the gap 801 between outer shaft wall 810 and the sleeve 302 may be filled with an adhesive. The adhesive may be applied to the inside of the sleeve 302 or the outer shaft wall 810 before the catheter shaft 202 is inserted into the sleeve 302. In embodiments, the proximal shaft end 203 and / or the distal shaft end 201 of the catheter shaft 202 may be covered, e.g., with a piece of tape, to prevent any adhesive from clogging one of the lumens, e.g., the fluid lumens 804. In some embodiments, the sleeve 302 is bonded by a reflowing process. The sleeve 302, with the catheter shaft 202 inserted, can be exposed to a heat source and reflowed about the catheter shaft 202 to fix the sleeve 302 to the catheter shaft 202. The heat source may be a heated air nozzle to blow hot air over the sleeve 302. The reflowing process may shrink the diameter of the sleeve 302 such that the gap 801 between the outer shaft wall and the sleeve 302 is eliminated.

[0090] Additional method operations can be performed to complete the tissue treatment catheter 102. For example, the ultrasound transducer 111 and the balloon 112 can be mounted on the catheter shaft 202 to place an interior 1002 of the balloon 112 in fluid communication with the fluid lumen(s) 804 of the catheter shaft 202.

[0091] Referring now to FIGS. 1 and 18, a perspective view of an example tissue treatment system 100 is shown in accordance with embodiments of the present disclosure. The tissue treatment system 100 includes a tissue treatment catheter 102 connected to a controller 120 by a connection cable 140. In certain embodiments, the tissue treatment catheter 102 includes an ultrasound transducer 111 within a balloon 112. The tissue treatment system 100 can include a fluid reservoir 110 to store an inflation fluid. The inflation fluid may be a cooling fluid. TheAttorney Docket No.: POMD04601PRI_US01 tissue treatment system 100 may have a fluid transfer unit 130 integrated within the controller 120 to transfer or move the inflation fluid into and out of the balloon 112. More particularly, the fluid transfer unit 130 of the tissue treatment system 100 may deliver the inflation fluid at a desired inflation pressure to the balloon 112, as described below. The tissue treatment system 100 may also include a cooling unit, e.g., integrated within the controller 120, to cool the inflation fluid. Accordingly, the inflation fluid can be delivered to the balloon 112 by the fluid transfer unit 130 at a temperature below ambient temperature. In embodiments, the tissue treatment system 100 includes an energy delivery unit configured to control activation, e.g., energize, the ultrasound transducer to deliver energy to the target anatomy.

[0092] The controller 120 is connected to the tissue treatment catheter 102 through an inflation tube 138 for fluid transfer, and the connection cable 140 for electrical communication. In certain embodiments, the controller 120 interfaces with the fluid transfer unit 130 to provide the inflation fluid to the tissue treatment catheter 102 for selectively inflating and deflating the balloon 112. The balloon 112 can be made from a biocompatible material. For example, the balloon 112 may be formed from a biocompatible elastomeric material. Examples of balloon materials that can be used to form the balloon 112 include, but are not limited to, nylon, a polyimide film, a thermoplastic elastomer (such as those marked under the trademark PEBAX™), a medical-grade thermoplastic polyurethane elastomer (such as Pellethane®, Isothane®, or other suitable polymers or any combination thereof), a silicone material, etc. The balloon material may be configured to transmit acoustic energy. More particularly, a wall of the balloon 112 can be transparent to, and pass, acoustic energy, e.g., from an inner balloon surface to an outer balloon surface.

[0093] Particularly referring to FIG. 18, the tissue treatment catheter 102 of the tissue treatment system 100 can include a catheter shaft 202 having an elongated body extending from a proximal catheter end 1804 to a distal catheter end 1806. The balloon 112 may be mountedAttorney Docket No.: PGMD04601PRI_US01 on the catheter shaft 202, e.g., at the distal catheter end 1806. One or more energy transducers, such as an ultrasound transducer 111, may be mounted on the catheter shaft 202. For example, the ultrasound transducer 111 may be positioned on the catheter shaft 202 within an interior defined by the balloon 112.

[0094] The catheter shaft 202 can define one or more lumens (e.g., FIG. 27), such as: fluid lumen(s) to deliver an inflation / cooling fluid to the balloon 112, cable lumen(s) to provide electrical cables passageways to deliver energy to the ultrasound transducer 111, and guidewire lumens for exchanging guidewires, etc. The lumen(s) may be connected to corresponding connectors and / or terminal features, such as at the proximal catheter end 1804. For example, the fluid lumens may connect to one or more fluid ports 1810, which receive inflation / cooling fluid from the fluid transfer unit 130 of the tissue treatment system 100. Similarly, the electrical cables 1504 can connect to an external connector 1812, which receives energy from a generator of the tissue treatment system 100 through the connection cable 140. In embodiments, a terminal feature of the guidewire lumen is a guidewire port 900, located along the catheter shaft 202 between the distal catheter end 1806 and the proximal catheter end 1804. The guidewire port 900 allows a guidewire 1104 to pass between the guidewire lumen and a surrounding environment 1822, as described below.

[0095] Referring to FIG. 19, a detail, perspective view of the tissue treatment catheter 102 delivered into a body lumen is shown in accordance with embodiments. A distal portion of the tissue treatment catheter 102 may be inserted into a body lumen of a subject. The body lumen may be a vessel 1900, e.g., a blood vessel such as a renal artery, which has a plurality of nerves 1101. The vessel 1900 can be a target vessel of an ablation procedure. More particularly, the nerves 1101 can be an ablation target. The nerves 1101 can surround the body lumen. For example, the nerves 1101 may run in and around the blood vessel 1900.Attorney Docket No.: PGMD04601PRI_US01

[0096] The distal portion of the tissue treatment catheter 102 may include the ultrasound transducer 111, the balloon 112 that may be filled with the inflation fluid, the catheter shaft 202, and / or a guidewire support tip 1902 configured to receive a guidewire 1104. More particularly, the guidewire 1104 can enter a guidewire lumen 806 through the guidewire support tip 1902 and extend proximally through the catheter shaft 202 in the guidewire lumen 806 to exit the catheter shaft 202 through the guidewire port 900 into the surrounding environment 1822. The tissue treatment catheter 102 may therefore be tracked over the guidewire 1104 into the body lumen. The ultrasound transducer 111 may be disposed or contained partially or completely within an interior 1002 of the balloon 112.

[0097] Additionally referring to FIG. 20, the balloon 112 is adapted to inflate within a target anatomy, e.g., the vessel 1900. The balloon 112 may be inflated with the inflation fluid. The inflation fluid may be, but is not limited to, water, dextrose, and / or saline. In embodiments, the inflation fluid is a liquid. The liquid inflation fluid may be selected for its heat capacity. A liquid inflation may be selected for having a relatively high heat capacity, as compared to gaseous inflation fluids. The interior 1002 of the balloon 112 may be in fluid communication with a fluid lumen 802 (FIG. 27) extending through the catheter shaft 202. When the inflation fluid is delivered through the fluid lumen 802 and into the interior 1002 of the balloon 112, the balloon 112 can inflate into contact with a vessel wall 1112 of the vessel 1900. The vessel wall 1112, and / or the nerves 1101 extending within and around the vessel wall, can be an ablation target.

[0098] In certain embodiments, the ultrasound transducer 111 can be adapted to deliver ablation energy, e.g., ultrasound energy, to the target anatomy during a medical procedure, e.g., a renal denervation procedure. For example, the ultrasound transducer 111 may be configured to emit acoustic energy in one or more energy lobes toward the target anatomy. More particularly, the ultrasound transducer 111 may be used to output acoustic energy to ablate theAttorney Docket No.: POMD04601PRI_US01 ablation target. During energy emission, the inflation fluid can be circulated within the interior 1002, around the ultrasound transducer 111. As the inflation fluid circulates within the interior 1002 of the balloon 112, the inflation fluid can act as a heat sink to absorb heat generated by the ultrasound transducer 111 and / or delivered to the ablation target from the ultrasound transducer 111. In some embodiments, the cooling fluid within the balloon 112 can be static and absorb heat to passively cool the ablation target and protect the target tissue and the ultrasound transducer 111.

[0099] In certain embodiments, the balloon 112 is inflated, while inserted in the body lumen of the target vessel 1900 of the patient, during a procedure to a working pressure of about 10 to about 30 psi using the inflation fluid. The balloon 112 may be, or may include, a compliant, semi-compliant, or non-compliant medical balloon. The balloon 112 is sized for insertion in the body lumen. For example, in the case of insertion into the renal artery, for example, the balloon 112 may be selected from available sizes including outer diameters of 3.5, 4.2, 5, 6, 7, or 8 mm, but not limited thereto. When activated, the ultrasound transducer 111 can deliver the acoustic energy to the vessel wall 1112 of the target vessel 1900. The delivered energy can ablate the ablation target, e.g., by thermal ablation through raising a temperature of the ablation target.

[0100] Referring to FIGS. 21 and 22, the catheter shaft 202 has a guidewire port 900 that includes a ramp 2201 formed from the native shaft material. The catheter shaft 202 can have the outer shaft wall 810 extending around the internal lumens of the tissue treatment catheter 102. More particularly, an outer surface of the outer shaft wall 810 can face radially outward and can extend, e.g., circumferentially, around the internal lumens such as the guidewire lumen 806, the fluid lumen(s) 804a, b, or the cable lumen 808. The outer shaft wall 810 can be processed, e.g., reflowed, to form the ramp 2201. For example, the outer shaft wall 810 can have a collapsed section 2102 that is indented inward relative to the surrounding outer surfaceAttorney Docket No.: POMD04601PRI_US01 of the outer shaft wall 810. Accordingly, the collapsed section 2102 can provide a ramp 2201 that is tapered from the guidewire lumen 806 to a surrounding environment 1822. The ramp 2201 may assist insertion or withdrawal of the guidewire 1104 into or out of the guidewire lumen 806.

[0101] A port edge 2106 can define the guidewire port 900. The port edge 2106 may be a continuous edge extending around a hole that extends through the outer shaft wall 810 into the guidewire lumen 806. The port edge 2106 may be formed by cutting, punching, skiving, or otherwise removing material from a tubular extrusion having the outer shaft wall 810. As described below, the port edge 2106 may be deformed, e.g., reflowed, to form the collapsed section 2102. The port edge 2106 may initially have an elliptical profile and may be deformed into a non-elliptical profile.

[0102] The collapsed section 2102 of the catheter shaft 202, which contains the ramp 2201 to direct the guidewire 1104 through the guidewire port 900, may be distinguished from adjacent sections of the catheter shaft 202 by a change in the profile of the otherwise smooth outer surface of the outer shaft wall 810. In an embodiment, the collapsed section 2102 is non- cylindrical. More particularly, a cross-sectional profile of the outer surface of the collapsed section 2102 can be non-circular. Such non-circularity can result from an indentation 2902 in the outer surface, as described below. By contrast, the outer shaft wall 810 can have a distal wall portion 2108 and a proximal wall portion 2110 on either side of the collapsed section 2102, one or both of which may be circular. More particularly, a cross-sectional profile of the outer surface of one or both of the distal wall portion 2108 distal to the collapsed section 2102 or the proximal wall portion 2110 proximal to the collapsed section 2102 can be circular. Such circularity of the distal wall portion 2108, which may be distal to the port edge 2106, results from the distal wall portion 2108 being cylindrical. Similarly, the proximal wall portion 2110 can be proximal to the port edge 2106 and may be cylindrical. The cylindrical shaft wallAttorney Docket No.: POMD04601PRI_US01 sections can have continuous circular outer profiles on both sides distal and proximal to the non-circular outer profile of the ramp 2201 used to guide the guidewire 1104 through the guidewire port 900. The cylindricity of the catheter shaft 202 can promote trackability and a low profile smooth insertion of the tissue treatment catheter 102, and the non-cylindricity of the collapsed section 2102 can provide the ramp 2201 through the guidewire port 900.

[0103] Particularly referring to FIG. 22, a top view of a guidewire port of a tissue treatment catheter is shown in accordance with embodiments of the present disclosure. The ramp 2201 formed by the collapsed section 2102 and extends longitudinally along the outer shaft wall 810. More particularly, the tissue treatment catheter 102 can include a longitudinal axis 2202, e.g., extending through a center of the guidewire lumen 806, a center of the catheter shaft 202, or a center of the cable lumen 808. The longitudinal axis 2202 establishes a reference against which the surfaces of the catheter shaft 202 can be described. For example, when the longitudinal axis 2202 is a center of the catheter shaft 202, the cylindrical distal wall portion 2108 and proximal wall portion 2110 extend circumferentially about the longitudinal axis 2202.

[0104] The collapsed section 2102 tapers outward from the port edge 2106 that surrounds the guidewire port 900. For example, a distal ramp end 2203 of the collapsed section 2102 at the port edge 2106 can be nearer to the longitudinal axis 2202 (into the page) than the collapsed section 2102 at a proximal ramp end 2204. More particularly, the proximal ramp end 2204 can be radially farther from the longitudinal axis 2202 than the distal ramp end 2203. The ramp 2201 can therefore taper outward in a proximal direction along the longitudinal axis 2202.

[0105] The ramp 2201 can have reference geometries, e.g., defining boundaries and / or surface features. For example, the ramp 2201 may be bounded by lateral boundaries 2206 separated from each other in a circumferential direction. More particularly, the lateral boundaries 2206 can define a lateral width of the collapsed section 2102. Portions of the catheter shaft 202 wall circumferentially outside of the lateral boundaries 2206 (on an oppositeAttorney Docket No.: POMD04601PRI_US01 side of the boundaries from the ramp 2201) may be convex in a first radial direction relative to the longitudinal axis 2202. For example, the outside portions may be arc-shaped, e.g., cylindrical sections, convex outward away from the longitudinal axis 2202. By contrast, portions of the catheter shaft 202 between the lateral boundaries 2206 (on the ramp 2201) can be convex in a second radial direction relative to the longitudinal axis 2202. For example, the collapsed section 2102 can be convex inward (or concave outward) relative to the longitudinal axis 2202 of the catheter shaft 202. A bottom of the ramp 2201, e.g., a reference line defined by points along the ramp 2201 that are nearer to the longitudinal axis 2202 than other points on the ramp 2201 transversely aligned with the points, can provide a track along which the guidewire 1104 can slide when passing from the guidewire lumen 806 to the surrounding environment 1822 through the guidewire port 900.

[0106] Referring to FIG. 23, a cross-sectional view of a guidewire port of a tissue treatment catheter is shown in accordance with an embodiment. Based on the above description, it is appreciated that the outer shaft wall 810 has a collapsed section 2102 tapering outward from the port edge 2106. More particularly, the collapsed section 2102 provides the ramp 2201 that tapers upward from the distal ramp end 2203 to the proximal ramp end 2204 at the port edge 2106. Accordingly, the collapsed section 2102 is nearer to the cable lumen 808 at the distal ramp end 2203 than at the proximal ramp end 2204.

[0107] The guidewire lumen 806 may be coaxially aligned with a mandrel lumen 2310. For example, the mandrel lumen 2310 and the guidewire lumen 806 can be a same lumen prior to forming the ramp 2201. After the ramp 2201 is formed the collapsed section 2102 (which defines the ramp 2201) can longitudinally separate the guidewire lumen 806 from the mandrel lumen 2310. The collapsed section 2102 can taper outward from the port edge 2106 longitudinally between the mandrel lumen 2310 and the guidewire lumen 806, effectively forming a barrier between the lumens. The ramp 2201 may fluidly seal the mandrel lumenAttorney Docket No.: POMD04601PRI_US012310 and the guidewire lumen 806 from one another. The ramp 2201 acts as a guide for the guidewire 1104 from the guidewire lumen 806 to the surrounding environment 1822 while also acting as a barrier to reduce a likelihood of material or fluid passage between the guidewire lumen 806 and the mandrel lumen 2310. Accordingly, when the guidewire 1104 passes through the guidewire lumen 806, it can pass along the ramp 2201 to exit through the guidewire port 900 into the surrounding environment 1822, rather than continuing longitudinally into the mandrel lumen 2310.

[0108] The ramp 2201 can be formed between the guidewire lumen 806 and the mandrel lumen 2310 by collapsing a portion, e.g., the collapsed section 2102, of the outer shaft wall 810 surrounding the mandrel lumen 2310 onto itself. For example, the port edge 2106 can be forced inward against a septum 2302 separating the mandrel lumen 2310 from the cable lumen 808. The port edge 2106 may be formed when a hole is made, e.g., by cutting or skiving, in the cylindrical wall of the catheter shaft 202. More particularly, the collapsed section 2102 can include an inner wall 2304 having portions that appose each other at the port edge 2106. The inner wall 2304 at the port edge 2106 can be brought adjacent to itself in a u-shaped or arc-shaped double-wall (FIG. 28). Accordingly, the inner wall 2304 portions can appose each other along a seam 2306. In forming the ramp 2201, as shown, the distal ramp end 2203 may be bonded to the septum 2302 such that the ramp 2201 tapers upwardly from the septum 2302 to the proximal ramp end 2204. The distal ramp end 2203 may be bonded to the septum 2302 as part of a reflowing process during formation of the collapsed section 2102 and the ramp 2201. In some embodiments, the distal ramp end 2203 may be adhered to the septum 2302 by a sealant 2308. The sealant 2308 can be disposed along the seam 2306 to form a seal between the inner wall 2304 portions that can hermetically seal off the mandrel lumen 2310 from the guidewire lumen 806. The seal between the septum 2302 and the distal ramp end 2203 may therefore prevent egress of blood or air between the guidewire lumen 806 and the mandrelAttorney Docket No.: POMD04601PRI_US01 lumen 2310. The sealant 2308 may be an adhesive, such as but not limited to a light-cured adhesive, which is dispensed between the apposed inner walls 2304 and cured during a manufacturing process, as described below. The sealant 2308 may also be applied at a proximal end of the mandrel lumen 2310 (not shown) to further seal off the mandrel lumen 2310 and reduce a likelihood of fluid egress through the mandrel lumen 2310 to or from the guidewire lumen 806.

[0109] Referring to FIG. 24, a stiffening mandrel 2400 in accordance with embodiments of the present disclosure is shown. The catheter shaft 202 can be supported by the stiffening mandrel 2400 disposed in the mandrel lumen 2310. The stiffening mandrel 2400 may be an elongated member, such as a wire, inserted into the catheter to contribute rigidity to the catheter shaft 202. Accordingly, the stiffening mandrel 2400 may be fabricated from a material that is stiffer than the outer shaft wall 810. For example, the catheter shaft 202 may be formed from a polymer and the stiffening mandrel 2400 may be formed from a stainless steel. Alternatively, the components can both be polymers, with the stiffening mandrel 2400 being a more rigid polymer.

[0110] The stiffening mandrel 2400 includes a tapered segment 2410. The tapered segment 2410 has a proximal taper end 2412 and a distal taper end 2414. The tapered segment 2410 tapers from the proximal taper end 2412 to the distal taper end 2414 along the longitudinal length of the stiffening mandrel 2400. The tapered segment 2410 may extend along the longitudinal length of the stiffening mandrel 2400 for a length in the range of 0.5 inches to 2 inches, e.g., 1 inch. The total length of the stiffening mandrel 2400 may be any length suitable for a given procedure. For example, for a renal denervation procedure, the stiffening mandrel 2400 may have a length of about 20-70 inches, e.g., about 50 inches. The tapered segment 2410 may be positioned at the distal end of the stiffening mandrel 2400.Attorney Docket No.: POMD04601PRI_US01

[0111] The tapered segment 2410 tapers from a larger cross-section at the proximal taper end 2412 to a smaller cross-section at the distal taper end 2414. For example, the stiffening mandrel 2400 may have a circular cross-section with a diameter in the range of 0.014 inches to 0.018 inches, e.g., 0.015, 0.016, or 0.017 inches, at the proximal taper end 2412. At the distal taper end 2414 the stiffening mandrel 2400 may have a diameter in the range 0.01 inches to 0.014 inches, e.g., 0.011, 0.012, or 0.013 inches. In embodiments, the stiffening mandrel 2400 may have a polygonal cross-section, e.g., square, rectangular, or hexagonal. In some embodiments, the stiffening mandrel 2400 may have an oblong or elliptical cross-section. The distal taper end 2414 may be positioned at a distalmost end 2416 of the stiffening mandrel 2400 and extend proximally toward the proximal taper end 2412. The distalmost end 2416 of the stiffening mandrel 2400 may have a hemispherical or bull nose shape as shown. In some embodiments, the distalmost end 2416 may have a flat profile. The tapered segment 2410 may have a constant taper as shown, e.g., a linear change in cross-section between the proximal taper end 2412 and the distal taper end 2414. In certain embodiments, the tapered segment 2410 has a non-constant or a compound taper. For example, the tapered segment 2410 may have parabolic or an exponential taper. In particular embodiments, the tapered segment 2410 is formed as a plurality of steps of decreasing diameter.

[0112] Referring to FIG. 25, another stiffening mandrel 2500 in accordance with embodiments of the present disclosure is shown. The distal taper end 2414 of the stiffening mandrel 2500 may be spaced apart from the distalmost end 2416 along the longitudinal length of the stiffening mandrel 2400 such that the stiffening mandrel 2400 has a reduced segment 2502 extending between the distal taper end 2414 and the distalmost end 2416. The reduced segment 2502 can have a uniform cross-section along its length. The size and dimension of the reduced segment 2502 can be equal to that of the stiffening mandrel 2500 at the distal taper end 2414. For example, where the stiffening mandrel 2400 has a circular cross-section and aAttorney Docket No.: PGMD04601PRI_US01 diameter of 0.012 inches at the distal taper end 2414, the reduced segment 2502 may have a circular cross-section and a diameter of 0.012 along the entire length thereof.

[0113] Continuing to refer to FIGS. 24 and 25, in particular embodiments, the stiffening mandrel 2400, 2500 may be configured to improve mating between the outer shaft wall 810. For example, the stiffening mandrel 2400 may define at or near the distalmost end 2416 a divot(s) or a passage(s) (not shown). The divot(s) or passage(s) may receive material of the outer shaft wall 810 therein when the outer shaft wall 810 is reflowed to conform to the stiffening mandrel 2400 as described below. The divot(s) or passage(s) may increase the surface area of the stiffening mandrel 2400 thereby improving the mating between the stiffening mandrel 2400 and the outer shaft wall 810. In embodiments where the stiffening mandrel 2400 defines passages, the material of the outer shaft wall 810 may be flowed through the passage and improve mechanical fixation of the stiffening mandrel 2400 to the catheter shaft 202. In some embodiments, the divot(s) or passage(s) may be created by a secondary roughening process, e.g., knurling or laser abrading.

[0114] Referring back to FIG. 23, the stiffening mandrel 2400 can be disposed in the mandrel lumen 2310 such that a distalmost end 2416 of the stiffening mandrel 2400 abuts the ramp 2201. The distalmost end 2416 and a portion of the stiffening mandrel 2400, e.g., part of the tapered segment 2410, may be embedded within the collapsed section 2102. Specifically, the collapsed section 2102 may be reflowed to conform to the tapered segment 2410 as described below. When abutting or embedded within the collapsed section 2102, the stiffening mandrel 2400 can act as a support to the ramp 2201. More particularly, when the guidewire 1104 is tracked through the guidewire lumen 806 and onto the ramp 2201, the ramp 2201 may flex slightly against the stiffening mandrel 2400 but can maintain a shape, rather than deflect backward, to guide the guidewire 1104 outward toward the surrounding environment 1822.Attorney Docket No.: PGMD04601PRI_US01

[0115] In some variants, a transitional element may be disposed between the collapsed section 2102 and at least a portion of the tapered segment 2410. The transitional element may have a width between 2 mm and 8 mm, preferably 5 mm. The transitional element may be made of thermal plastic. Adding the transitional element may reduce the probability of the mandrel piercing the collapsed section during manufacturing of the catheter and thus rendering the catheter unusable.

[0116] Referring to FIG. 26, a top view of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The catheter shaft 202 is shown having the collapsed section 2102 longitudinally between the distal wall portion 2108 and the proximal wall portion 2110. The collapsed section 2102, which includes the ramp 2201 to guide the guidewire 1104 from the guidewire port 900 to the surrounding environment 1822, can be bounded by the lateral boundaries 2206, the distal ramp end 2203, and the proximal ramp end 2204. As described above, the ramp 2201 is recessed (into the page), as compared to the surrounding lateral boundaries 2206. Cross-sectional views along the section lines are now described for further understanding.

[0117] Referring to FIG. 27, a cross-sectional view, taken about line A-A of FIG. 26, of the distal wall portion 2108 of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The distal wall portion 2108 of the catheter shaft 202 can include three or more lumens. The lumens may, for example, include the guidewire lumen 806, the cable lumen 808, and one or more fluid lumens 802, e.g., a supply fluid lumen and a return fluid lumen. The lumens may be disposed about the longitudinal axis 2202, which can extend longitudinally through the septum 2302 of the catheter shaft 202. The septum 2302 can separate the shaft lumens.

[0118] The lumens may be configured to receive materials or objects. For example, the fluid lumens 802 can receive and circulate the inflation fluid and the guidewire lumen 806 canAttorney Docket No.: PGMD04601PRI_US01 be configured to receive the guidewire 1104. An electrical cable 1504 can be disposed in the cable lumen 808 to deliver electrical signals to the ultrasound transducer 111. Notably, the outward facing surface of the outer shaft wall 810 in the distal wall portion 2108 can be circular and, thus, convex outward relative to the longitudinal axis 2202.

[0119] Referring to FIG. 28, a cross-sectional view, taken about line B-B of FIG. 26, of the guidewire port 900 of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. The fluid lumens 802 and the cable lumen 808 can be shaped the same at a transverse cross-section at the guidewire port 900, as compared to the transverse cross-section at the distal wall portion 2108. The guidewire lumen 806, however, may be terminated by collapsing the outer shaft wall 810. For example, the inner wall surfaces 2304 can be squeezed and / or reflowed toward each other to define the seam 2306 at the port edge 2106. The seam 2306 can have a u-shaped profile revealing the concave outward shape of the ramp 2201 relative to the longitudinal axis 2202. The ramp 2201 may provide a smooth surface tapering upward to guide the guidewire 1104 toward the surrounding environment 1822.

[0120] Referring to FIG. 29, a cross-sectional view, taken about line C-C of FIG. 26, of the ramp 2201 of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. Proximal to the guidewire port 900, the luminal profiles of the catheter shaft 202 can be identical to the luminal profiles distal to the guidewire port 900. More particularly, the fluid lumen(s) 802, the cable lumen 808, and the mandrel lumen 2310 near the proximal wall portion 2110 can have a same shape as the fluid lumen(s) 802, the cable lumen 808, and the guidewire lumen 806 at the distal wall portion 2108. For example, the mandrel lumen 2310, like the guidewire lumen 806, can be circular to receive the round stiffening mandrel 2400. The outer shape of the catheter wall may, however, not be circular at the transverse plane location along the ramp 2201. More particularly, at the proximal ramp endAttorney Docket No.: PGMD04601PRI_US012204 of the ramp 2201, the outer shaft wall 810 can have an indentation 2902. The indentation 2902 can be a concavity where the ramp 2201 is transitioning from the port edge 2106 to the proximal wall portion 2110. The concavity may be shallower than the concavity at the seam 2306, however, the outer surface of the catheter shaft 202 may nonetheless be non-circular.

[0121] Referring to FIG. 30, a cross-sectional view, taken about line D-D of FIG. 26, of the proximal wall portion 2110 of the tissue treatment catheter 102 is shown in accordance with embodiments of the present disclosure. Proximal to the ramp 2201, the luminal profiles of the catheter shaft 202 can be identical to the luminal profiles distal to the guidewire port 900. More particularly, the fluid lumen(s) 802, the cable lumen 808, and the mandrel lumen 2310 in the proximal wall portion 2110 can have a same shape as the fluid lumen(s) 802, the cable lumen 808, and the guidewire lumen 806 at the distal wall portion 2108. For example, the mandrel lumen 2310, like the guidewire lumen 806, can be circular. The outer shape of the catheter wall may also be circular. More particularly, the proximal wall portion 2110 can be cylindrical.

[0122] The example embodiments of the tissue treatment catheter 102 described above can allow access to a variety of tortuous anatomies throughout a patient anatomy. In an embodiment, the tissue treatment catheter 102 may be delivered through a radial access approach to vascular target sites. For example, radial access may be through a radial artery, a subclavian artery, and then into a downstream vessel having a sharp takeoff, such as a renal artery.

[0123] Referring to FIG. 31, a method 3100 of manufacturing tissue treatment catheters in accordance with embodiments of the present disclosure is described with reference to the tissue treatment catheter 102 is now described of FIGS. 17-30. It will be appreciated that the method 3100 is provided by way of example, and the operations described may be added to or subtracted from, including being performed in different orders, to manufacture the structures described above.Attorney Docket No.: POMD04601PRI_US01

[0124] At operation 3102, the guidewire port 900 is formed though the outer shaft wall 810 of the catheter shaft 202. More particularly, the outer shaft wall 810 can be extruded as a multilumen catheter having several lumens extending longitudinally from the proximal catheter end 1804 to the distal catheter end 1806. The outer shaft wall 810 can extend around a single lumen, which has portions that will become the mandrel lumen 2310 and the guidewire lumen 806. The mandrel lumen 2310 portion is therefore coaxially aligned with the guidewire lumen 806 portion. When the guidewire port 900 is formed, e.g., by skiving, punching, drilling, or otherwise forming a hole through the cylindrical outer shaft wall 810 of the catheter shaft 202 into the single lumen, the guidewire port 900 can form a reference delineation between the mandrel lumen 2310, proximal to the hole, and the guidewire lumen 806, distal to the hole. The guidewire port 900 includes the port edge 2106 extending around the hole. In the initial state, prior to reforming the catheter shaft 202 to fabricate the ramp 2201, the port edge 2106 can have a circular profile that is projected onto a cylindrical outer surface.

[0125] At operation 3104, the outer shaft wall 810 is collapsed to form the collapsed section 2102. As described above, the collapsed section 2102 can taper outward from the port edge 2106 longitudinally between the mandrel lumen 2310 and the guidewire lumen 806. Collapsing the outer shaft wall 810 can include a plastic reflowing process. The reflowing process may include a heat shrink tubing length being placed over the catheter shaft 202 and aligned with the guidewire port 900. The assembly may be heated, e.g., by a heated air nozzle to melt the outer shaft wall 810. The catheter shaft 202 may be exposed to temperatures in the range of 340 degrees Fahrenheit to 350 degrees Fahrenheit, e.g., 345 degrees Fahrenheit. The catheter shaft 202 may be exposed to heat for a duration in the range of 5 second to 15 seconds, e.g., 10 seconds. In embodiments, the heated air nozzle may blow heated air over the catheter shaft 202 at a rate in the range of 20 to 30 standard cubic feet per hour (SCFH). As the outer shaft wall 810 melts and the heat shrink tubing squeezes around the guidewire port 900, aAttorney Docket No.: POMD04601PRI_US01 shaping mandrel positioned in the guidewire lumen 806 can be squeezed downward, causing the port edge 2106 to reflow and to collapse against the septum 2302. The assembly may then be cooled, and the heat shrink tubing removed. The shaping mandrel in the guidewire lumen 806 can be removed to expose the guidewire lumen 806 and reveal the ramp 2201 tapering into the guidewire port 900.

[0126] At operation 3106, the stiffening mandrel 2400 is inserted into the mandrel lumen 2310. The stiffening mandrel 2400 can be inserted through a proximal end of the mandrel lumen 2310 and advanced distally until the distalmost end 2416 of the stiffening mandrel 2400 is adjacent to the guide wire port 900. The stiffening mandrel 2400 may be inserted into the mandrel lumen 2310 prior to collapsing the outer shaft wall 810 at operation 3104. When the collapsed section 2102 is formed, material of the collapsed section 2102 may be conformed about a portion of the stiffening mandrel 2400. Specifically, the distalmost end 2416 of the stiffening mandrel 2400 and portion the tapered segment 2410 may be embedded in the collapsed section 2102. More particularly, the distalmost end 2416 of the stiffening mandrel 2400 and portion the tapered segment 2410 may be embedded the proximal side of the ramp 2201. In embodiments, the entire tapered segment 2410 may be embedded in the collapsed section 2102. In some embodiments, when the collapsed section 2102 is formed, the distalmost end 2416 of the stiffening mandrel 2400 can abut the collapsed section 2102 without becoming embedded within the collapsed section 2102.

[0127] The tapered segment 2410 of the stiffening mandrel 2400 is configured to reduce the likelihood of bum-through when the outer shaft wall 810 is collapsed during operation 3104. In extreme cases, bum-through could cause damage to other portion of the catheter shaft 202, such as the fluid lumen 802, or other components, such as the electrical cable 1504. Bum- through may be caused by uneven heating during operation 3104. Additionally or alternatively, bum-through may be caused by thermal inertia or “carry over cooking”. For example, onceAttorney Docket No.: POMD04601PRI_US01 the application of heat to the catheter shaft 202 has ceased, the temperature of the stiffening mandrel 2400 may continue to increase slightly before beginning to cool. During operation 3104 heat can be applied to the catheter shaft 202 to reflow and conform the outer shaft wall 810 to the stiffening mandrel 2400. The tapered segment 2410 may reduce the heat capacity of the stiffening mandrel 2400 locally. Specifically, the tapered segment 2410 may have less thermal mass within the area of applied heat as compared to a stiffening member with a uniform cross-section along the entire length thereof. In contrast, a stiffening member having a uniform cross-section of smaller size and dimension, e.g., a diameter equal to the stiffening mandrel 2400 at the distal taper end 2414, may not adequately stiffen the catheter shaft 202 or support pushability of the tissue treatment catheter 102 though may reduce the instances of burn- through. The stiffening mandrel 2400 may reduce the likelihood of bum-through without a reduction stiffness and pushability of the tissue treatment catheter 102. The reduced thermal mass of the stiffening mandrel 2400 at the tapered segment 2410 may result in less “carry over cooking” and, thus, may prevent bum-through. The presence of the shaping mandrel and the stiffening mandrel 2400 in close proximity to one another during application of heat to the catheter shaft 202 may exacerbate bum-through. Specifically, the shaping mandrel and the stiffening mandrel 2400 may be separated only by the collapsed section 2102. Accordingly, the collapsed section 2102 is surrounded by the thermal mass and / or thermal inertia of both the shaping mandrel and the stiffening mandrel 2400. As noted above, the tapered segment 2410 reduces the amount of thermal mass surrounding the collapsed section 2102. This reduction in thermal mass may reduce the likelihood of burn-through. Additionally or alternatively, the tapered segment 2410 may create additional space between the stiffening mandrel 2400 the catheter shaft 202 to encourage the material of the catheter shaft 202 reflow. In contrast, a stiffening mandrel with a uniform thickness may force material out from between the stiffening mandrel and the shaping mandrel thereby creating thin walled portions of the catheter shaft 202Attorney Docket No.: POMD04601PRI_US01 or bum-through. In some embodiments, the material of the stiffening mandrel 2400 may reduce instances of burn through. For example, a metallic stiffening mandrel 2400 may conduct heat away from the portion of wall being reflowed. Additionally or alternatively, the metallic material of the stiffening mandrel 2400 may improve bonding with the catheter shaft 202. For example, the material of the stiffening mandrel 2400 may chemically bond, e.g., by covalent bonding, with the metallic material of the catheter wall 202. The chemical bonding between the metallic stiffening mandrel 2400 and the reflowed portion of catheter wall 202 may occur at lower tempers than with a non-metallic stiffening mandrel 2400 and, as such, a metallic stiffening mandrel 2400 may reduce the likelihood of bum-through.

[0128] Additional method operations can be performed to complete the tissue treatment catheter 102. For example, the ultrasound transducer 111 and the balloon 112 can be mounted on the catheter shaft 202 to place an interior 1002 of the balloon 112 in fluid communication with the fluid lumen 802 of the catheter shaft 202.

[0129] Embodiments are described in the following enumerated examples.

[0130] Example 1. A tissue treatment catheter includes a catheter shaft and a sleeve. The catheter shaft has a proximal shaft end, a distal saft end opposite the proximal shaft end, and an outer shaft wall extending between the proximal shaft end and the distal shaft end. The catheter shaft defines a first fluid lumen extending between the proximal shaft end and the distal shaft end. The sleeve has a sleeve proximal end and sleeve distal end opposite the sleeve proximal end. The sleeve is bonded to the outer shaft wall of the catheter shaft with the sleeve adjacent to the proximal shaft end.

[0131] Example 2. The tissue treatment catheter of example 1. The sleeve has a higher durometer than the catheter shaft.

[0132] Example 3. The tissue treatment catheter of example 1. The sleeve has a durometer greater than or equal to Shore 75D.Attorney Docket No.: POMD04601PRI_US01

[0133] Example 4. The tissue treatment catheter of example 1 or example 2. The sleeve is positioned along the catheter shaft with the sleeve proximal end flush with the proximal shaft end.

[0134] Example 5. The tissue treatment catheter of any one of example 1 through example 4. The catheter shaft defines a guidewire lumen and the outer shaft wall defines a guidewire port. The guidewire lumen extends from the distal end to the guidewire port. The guidewire lumen is accessible through the guidewire port from a surrounding environment.

[0135] Example 6. The tissue treatment catheter of example 5. The guidewire port is positioned between the distal shaft end and the sleeve distal end.

[0136] Example 7. The tissue treatment catheter of any one of example 1 through example 6. The tissue treatment catheter comprises a balloon mounted on the catheter shaft. The balloon defines an interior. The interior is in fluid communication with the first fluid lumen.

[0137] Example 8. The tissue treatment catheter of example 7. The tissue treatment catheter comprising an ultrasound transducer disposed within the interior of the balloon. The catheter shaft defines a cable lumen extending from the proximal shaft end to the distal shaft end. The tissue treatment catheter further comprises an electrical cable extending through the cable lumen and electrically coupled to the ultrasound transducer.

[0138] Example 9. The tissue treatment catheter of example 8. The catheter shaft defines a second fluid lumen in fluid communication with the interior of the balloon. The tissue treatment catheter further comprises a lumen hub coupled to the proximal shaft end. The lumen hub including a first fluid tube in fluid communication with the first fluid lumen and second fluid tube in fluid communication with the second fluid lumen. The first fluid tube and the second fluid tube extend outward from a longitudinal axis of the catheter shaft in a wye configuration.Attorney Docket No.: POMD04601PRI_US01

[0139] Example 10. The tissue treatment catheter of example 9. The lumen hub comprises a strain relief. The strain relief contains the proximal shaft end and the sleeve distal end.

[0140] Example 11. The tissue treatment catheter of example 9. The lumen hub comprises a strain relief. The strain relief containing the proximal shaft end. The sleeve is positioned along the catheter shaft such that the sleeve distal end abuts a distal most face of the strain relief.

[0141] Example 12. A tissue treatment catheter includes a catheter shaft and a sleeve. The catheter shaft has a proximal shaft end, a distal shaft end opposite the proximal shaft end, and an outer wall extending between the proximal shaft end and the distal shaft end. The catheter shaft defines a fluid lumen extending between the proximal shaft end and the distal shaft end. The sleeve is bonded to the outer shaft wall to reinforce the catheter shaft. The sleeve is configured to maintain a profile of the catheter shaft during use.

[0142] Example 13. The tissue treatment catheter of example 12. The sleeve is configured to resist buckling under compressive forces applied to the sleeve from a surrounding environment to maintain the profile of the catheter shaft.

[0143] Example 14. The tissue treatment catheter of example 12 or 13. The sleeve is configured to resist collapsing resulting from vacuum pressure applied to the fluid lumen to maintain the profile of the catheter shaft.

[0144] Example 15. The tissue treatment catheter of any one of example 12 through 14. The sleeve is configured to maintain the profile of the catheter shaft when exposed to elevated temperatures in the range of 35 degrees Celsius to 40 degrees Celsius.

[0145] Example 16. A method of reinforcing a catheter shaft includes inserting the catheter shaft into a sleeve. The catheter shaft has an outer shaft wall. The catheter shaft defines a fluid lumen. The method also includes bonding the sleeve to the outer shaft wall of the catheterAttorney Docket No.: POMD04601PRI_US01 shaft. The sleeve is configured to maintain a profile of the catheter shaft to prevent deformation of the catheter shaft during use.

[0146] Example 17. The method of example 16. The sleeve is configured to resist collapse of the catheter shaft when vacuum is applied through the fluid lumen.

[0147] Example 18. The method of example 16 or 17. Bonding the sleeve to the outer shaft wall includes adhering the sleeve to the outer shaft wall with an adhesive and curing the adhesive.

[0148] Example 19. The method of any one of example 16 through example 18. Bonding the sleeve to the outer shaft wall includes applying heat the sleeve such that the sleeve reflows about the catheter shaft and engaged the outer shaft wall.

[0149] Example 20. The method of any one of example 16 through example 19. The method comprising positioning the sleeve along the length of the catheter shaft. The sleeve is positioned before bonding the sleeve to the outer shaft wall. The sleeve is positioned such that a sleeve proximal end is flush with a proximal shaft end.

[0150] Example I. A tissue treatment catheter includes a catheter shaft and a stiffening mandrel. The catheter shaft has an outer shaft wall. The catheter shaft defines a guidewire lumen and mandrel lumen. The outer shaft wall has a collapsed section defines a guidewire port in the outer shaft wall such that the guidewire lumen is accessible through the guidewire port. The collapsed section forms a ramp including a proximal ramp end positioned at the outer shaft wall and distal ramp end positioned within the guidewire lumen. The ramp tapers outwardly from the distal ramp end longitudinally to the proximal ramp end. The collapsed section separates the guidewire lumen such that the guidewire lumen and the mandrel lumen are coaxially aligned. The stiffening mandrel includes a tapered segment having a proximal taper end and distal taper end. The tapered segment tapers longitudinally from the proximal taper end to the distal taper end such that the distal taper end of the tapered segment has a smallAttorney Docket No.: POMD04601PRI_US01 cross-section than the proximal taper end. The stiffening mandrel is disposed within the mandrel lumen. The collapsed section is conformed about at least a portion of the tapered segment.

[0151] Example II. The tissue treatment catheter of example I, the catheter shaft further defining a fluid lumen and a cable lumen. The guidewire lumen, the mandrel lumen, the fluid lumen, and the cable lumen are separated by the septum.

[0152] Example III. The tissue treatment catheter of example II further including a balloon and an ultrasound transducer. The balloon is mounted to the catheter shaft. The balloon defines an interior in fluid communication with the fluid lumen. The ultrasound transducer is mounted to the catheter shaft and contained within the interior of the balloon. The ultrasound transducer is electrically coupled to an electrical cable within the cable lumen.

[0153] Example IV. The tissue treatment catheter of example II. The distal ramp end is bonded to the septum such that the collapsed section fluidly seals the guidewire lumen from the mandrel lumen.

[0154] Example V. The tissue treatment catheter of any one of example I through exampleIV. The tapered segment of the stiffening mandrel has a constant taper between the proximal taper end and the distal taper end.

[0155] Example VI. The tissue treatment catheter of any one of example I through exampleV. A most distal end of the stiffening mandrel has a hemispherical, bullnose shape.

[0156] Example VII. The tissue treatment catheter according to any one of example I through example VI. The collapsed section is concave outward relative to a longitudinal axis of the catheter shaft.

[0157] Example VIII. The tissue treatment catheter according to any one of example I through example VII. At least a portion of the tapered segment is embedded within the collapsed section.Attorney Docket No.: POMD04601PRI_US01

[0158] Example IX. A tissue treatment catheter includes a catheter shaft and stiffening mandrel. The catheter shaft has an outer shaft wall. The catheter shaft defines a guidewire lumen and a mandrel lumen. The outer shaft wall has collapsed section defining a guidewire port through the outer shaft wall. The collapsed section forms a ramp configured to slidingly receive a guidewire through the guidewire port and into the guidewire lumen from a surrounding environment. The collapsed section separates the guidewire lumen and mandrel lumen such that guidewire lumen and the mandrel lumen are coaxially aligned. The stiffening mandrel includes a tapered segment. The stiffening mandrel is disposed within the mandrel lumen. The tapered segment is configured to prevent bum-through of the catheter shaft when the tissue treatment catheter is exposed to elevated temperatures.

[0159] Example X. The tissue treatment catheter of example IX. The tapered segment is configured to the prevent burn-through of the catheter shaft when the tissue treatment catheter is exposed to elevated temperatures in the range of 340 degrees Fahrenheit to 350 degrees Fahrenheit for a duration in the range of 5 seconds to 15 seconds.

[0160] Example XI. The tissue treatment catheter of example IX or example X. The stiffening mandrel is configured to stiffen the catheter shaft along a length thereof, the length extending proximally from the collapsed section.

[0161] Example XII. The tissue treatment catheter of any one of example IX through example XI. The catheter shaft further defines a fluid lumen and a cable lumen. The treatment catheter further includes a balloon and an ultrasound transducer. The balloon and the ultrasound transducer are mounted on the catheter shaft. The balloon defines an interior in fluid communication with the fluid lumen. The ultrasound transducer is contained within the interior of the balloon. The ultrasound transducer is electrically coupled to an electrical cable within the cable lumen. The ultrasound transducer is configured to emit acoustic energy.Attorney Docket No.: POMD04601PRI_US01

[0162] Example XIII. The tissue treatment catheter according to any one of example IX through example XII. The collapsed section is conformed about a portion of the tapered segment to fix the stiffening mandrel to the catheter shaft. The collapsed section is conformed about the tapered segment by exposing catheter shaft to elevated temperatures. The tapered segment is spaced apart from an inner shaft wall of catheter shaft prior to exposing the catheter shaft to elevated temperatures.

[0163] Example XIV. A method of manufacturing a tissue treat catheter includes forming a guidewire port through an outer shaft wall of a catheter shaft. The catheter shaft defines a mandrel lumen coaxially aligned with a guidewire lumen. The method also includes collapsing the outer shaft wall to form a collapsed section of the catheter shaft to separate the mandrel lumen and the guidewire lumen. The collapse section forms a ramp that tapers outward from a distal ramp end longitudinally to a proximal ram end that is positioned at the outer shaft wall. The method also includes inserting a stiffening mandrel into the mandrel lumen. The stiffening mandrel has a tapered segment. The collapsed section is conformed about at least a portion of the tapered segment to fix the stiffening mandrel to the catheter shaft.

[0164] Example XV. The method of example XIV. Inserting the stiffening the stiffening mandrel into the mandrel lumen occurs before collapsing the outer shaft wall to form the collapsed section.

[0165] Example XVI. The method of example XIV or example XV. The method further includes mounting a balloon and an ultrasound transducer on the catheter shaft. The balloon defines an interior in fluid communication with a fluid lumen defined by the catheter shaft. The ultrasound transducer is contained within the interior of the balloon. The ultrasound transducer is configured to emit acoustic energy.Attorney Docket No.: POMD04601PRI_US01

[0166] Example XVII. The method of any one of example XIV through example XVI. Collapsing the outer shaft wall includes bifurcating a first lumen into the guidewire lumen and the mandrel lumen.

[0167] Example XVIII. The method of any one of example XIV through example XVII. Collapsing the outer shaft wall includes applying heat to the catheter shaft to reflow a portion of the catheter shaft about the stiffening mandrel and embed at least a portion of the tapered segment within the collapsed section. The tapered segment is configured to prevent burn- through of the catheter shaft during collapsing of the outer shaft wall.

[0168] Example XIX. The method of example XVIII. Applying heat to the catheter shaft includes applying heat with a temperature in the range of 340 degrees Fahrenheit to 350 degrees Fahrenheit for a duration in the range of 5 seconds to 15 seconds.

[0169] Example XX. The method of example XIX. Collapsing the outer shaft wall includes cooling the tissue treatment catheter to allow the collapses section to fix the stiffening mandrel in place.

[0170] In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will be evident that various modifications may be made thereto without departing from the broader spirit and scope of the invention as set forth in the following claims. The specification and drawings are, accordingly, to be regarded in an illustrative sense rather than a restrictive sense.

Claims

Attorney Docket No.: POMD04601PRI_US01CLAIMSWhat is claimed is:

1. A tissue treatment catheter comprising: a catheter shaft having a proximal shaft end, a distal shaft end opposite the proximal shaft end, and an outer shaft wall extending between the proximal shaft end and the distal shaft end, the catheter shaft defining a first fluid lumen extending between the proximal shaft end and the distal shaft end; and a sleeve having a sleeve proximal end and a sleeve distal end opposite the sleeve proximal end, the sleeve bonded to the outer shaft wall to reinforce the catheter shaft and enclosing a portion of the catheter shaft therein, the sleeve positioned along the outer shaft wall of the catheter shaft with the sleeve proximal end adjacent to the proximal shaft end.

2. The tissue treatment catheter according to claim 1, wherein the sleeve has a higher durometer than the catheter shaft.

3. The tissue treatment catheter according to claim 2, wherein the sleeve has durometer greater than or equal to Shore 75D.

4. The tissue treatment catheter according to claims 1 or 2, wherein the sleeve is positioned along the catheter shaft with the sleeve proximal end flush with the proximal shaft end.

5. The tissue treatment catheter according to any one of claims 1 through 4, wherein the catheter shaft defines a guidewire lumen and the outer shaft wall defines a guidewire port, the guidewire lumen extending from the distal shaft end to the guidewire port, the guidewire lumen accessible through the guidewire port from a surrounding environment.Attorney Docket No.: POMD04601PRI_US016. The tissue treatment catheter according to claim 5, wherein the guidewire port is positioned between the distal shaft end and the sleeve distal end.

7. The tissue treatment catheter according to any one of claims 1 through 6, comprising a balloon mounted on the catheter shaft, the balloon defining an interior, the interior in fluid communication with the first fluid lumen.

8. The tissue treatment catheter according to claim 7, comprising an ultrasound transducer disposed within the interior of the balloon, and wherein the catheter shaft defines a cable lumen extending from the proximal shaft end to the distal shaft end, and further comprising an electrical cable extending through the cable lumen and electrically coupled to the ultrasound transducer.

9. The tissue treatment catheter according to claim 8, wherein the catheter shaft defines a second fluid lumen in fluid communication with the interior of the balloon, and the tissue treatment catheter further comprises a lumen hub coupled to the proximal shaft end, the lumen hub including a first fluid tube in fluid communication with the first fluid lumen and a second fluid tube in fluid communication with the second fluid lumen, the first fluid tube and the second fluid tube extending outward from a longitudinal axis of the catheter shaft in a wye configuration.

10. The tissue treatment catheter according to claim 9, wherein the lumen hub comprises a first strain relief, the first strain relief containing the proximal shaft end and the sleeve distal end.Attorney Docket No.: POMD04601PRI_US0111. The tissue treatment catheter according to claim 9, wherein the lumen hub comprises a first strain relief, the strain relief containing the proximal shaft end, and wherein the sleeve is positioned along the catheter shaft such that the sleeve distal end abuts a distal most face of the strain relief.

12. The tissue treatment catheter according to claim 10 or 11, when depending on claim 9, wherein the lumen hub further comprises a second strain relief containing a portion of the first fluid tube and a third strain relief containing a portion of the second fluid tube.

13. The tissue treatment catheter according to claim 9, wherein the lumen hub comprises a single-piece strain relief comprising the proximal shaft end, a portion of the first fluid tube and a portion of the second fluid tube; and, optionally, wherein the single-piece strain relief is formed 'via overmolding.

14. A tissue treatment catheter comprising: a catheter shaft having proximal shaft end, a distal shaft end opposite the proximal shaft end, and an outer shaft wall extending between the proximal shaft end and the distal shaft end, the catheter shaft defining a fluid lumen extending between the proximal shaft end and the distal shaft end; and a sleeve bonded to the outer shaft wall to reinforce the catheter shaft, the sleeve configured to maintain a profile of the catheter shaft during use.

15. The tissue treatment catheter according to claim 14, wherein the sleeve is configured to resist buckling under compressive forces applied to the sleeve from a surrounding environment to maintain the profile of the catheter shaft.Attorney Docket No.: POMD04601PRI_US0116. The tissue treatment catheter according to claim 14 or 15, wherein the sleeve is configured to resist collapsing resulting from vacuum pressure applied to the fluid lumen to maintain the profile of the catheter shaft.

17. The tissue treatment catheter according to any one of claims 14 through 16, wherein the sleeve is configured to maintain the profile of the catheter shaft when exposed to elevated temperatures in the range of 35 degrees Celsius to 40 degrees Celsius.

18. A method of reinforcing a catheter shaft, the method comprising: inserting the catheter shaft into a sleeve, the catheter shaft having an outer shaft wall, the catheter shaft defining a fluid lumen; and bonding the sleeve to the outer shaft wall of the catheter shaft, the sleeve configured to maintain a profile of the catheter shaft to prevent deformation of the catheter shaft during use.

19. The method according claim 18, wherein the sleeve is configured to resist collapse of the catheter shaft when vacuum is applied through the fluid lumen.

20. The method according to claim 18 or 19, wherein bonding the sleeve to the outer shaft wall includes adhering the sleeve to the outer shaft wall with an adhesive and curing the adhesive.

21. The method according to any one of claims 18 through 20, wherein bonding the sleeve to the outer shaft wall includes applying heat to the sleeve such that the sleeve reflows about the catheter shaft and engages the outer shaft wall.Attorney Docket No.: POMD04601PRI_US0122. The method according to any one of claims 18 through 21, comprising positioning the sleeve along the length of the catheter shaft, the sleeve being positioned before bonding the sleeve to the outer shaft wall, the sleeve positioned such that a sleeve proximal end is flush with a proximal shaft end.

23. A tissue treatment catheter comprising: a catheter shaft having an outer shaft wall, the catheter shaft defining a guidewire lumen and a mandrel lumen, the outer shaft wall having a collapsed section defining a guidewire port in the outer shaft wall such that the guidewire lumen is accessible through the guidewire port, the collapsed section forming a ramp including a proximal ramp end positioned at the outer shaft wall and a distal ramp end positioned within the guidewire lumen, the ramp tapering outward from the distal ramp end longitudinally to the proximal ramp end, the collapsed section separating the guidewire lumen and the mandrel lumen such that the guidewire lumen and the mandrel lumen are coaxially aligned; and a stiffening mandrel including a tapered segment having a proximal taper end and a distal taper end, the tapered segment tapering longitudinally from the proximal taper end to the distal taper end such that the distal taper end of the tapered segment has a smaller cross-section than the proximal taper end, the stiffening mandrel disposed within the mandrel lumen, the collapsed section conformed about at least a portion of the tapered segment.

24. The tissue treatment catheter according to claim 23, wherein the catheter shaft further defines a fluid lumen and a cable lumen, and wherein the guidewire lumen, the mandrel lumen, the fluid lumen, and the cable lumen are separated by a septum.

25. The tissue treatment catheter according to claim 24, comprising a balloon and ultrasound transducer, the balloon mounted to the catheter shaft, the balloon defining an interiorAttorney Docket No.: POMD04601PRI_US01 in fluid communication with the fluid lumen, the ultrasound transducer mounted to the catheter shaft and contained within the interior of the balloon, the ultrasound transducer electrically coupled to an electrical cable within the cable lumen.

26. The tissue treatment catheter according to claim 24, wherein the distal ramp end is bonded to the septum such that the collapsed section fluidly seals the guidewire lumen from the mandrel lumen.

27. The tissue treatment catheter according to any one of claims 23 through 26, wherein the tapered segment of the stiffening mandrel has a constant taper between the proximal taper end and the distal taper end.

28. The tissue treatment catheter according to any one of claims 23 through 27, wherein a most distal end of the stiffening mandrel has a hemispherical, bullnose shape.

29. The tissue treatment catheter according to any one of claims 23 through 28, wherein the collapsed section is concave outward relative to a longitudinal axis of the catheter shaft.

30. The tissue treatment catheter according to any one of claims 23 through 29, wherein at least a portion of the tapered segment is embedded within the collapsed section.

31. The tissue treatment catheter according to any one of claims 23 through 30, further comprising a transitional element disposed between the collapsed section and at least a portion of the tapered segment.Attorney Docket No.: POMD04601PRI_US0132. The tissue treatment catheter according to claim 31 wherein (i) the transitional element has a width between 2 mm and 8 mm, preferably 5 mm; and / or (ii) is made of thermal plastic.

33. A tissue treatment catheter comprising: a catheter shaft having an outer shaft wall, the catheter shaft defining a guidewire lumen and a mandrel lumen, the outer shaft wall having a collapsed section defining a guidewire port through the outer shaft wall, the collapsed section forming a ramp configured to slidingly receive a guidewire through the guidewire port and into the guidewire lumen from a surrounding environment, the collapsed section separating the guidewire lumen and the mandrel lumen such that the guidewire lumen and the mandrel lumen are coaxially aligned; and a stiffening mandrel including a tapered segment, the stiffening mandrel disposed within the mandrel lumen and fixed to the catheter shaft, the tapered segment configured to prevent bum-through of the catheter shaft when the tissue treatment catheter is exposed to elevated temperatures.

34. The tissue treatment catheter according to claim 33, wherein the tapered segment is configured to prevent bum-through of the catheter shaft when the tissue treatment catheter is exposed to elevated temperatures in the range of 340 degrees Fahrenheit to 350 degrees Fahrenheit for a duration in the range of 5 seconds to 15 seconds.

35. The tissue treatment catheter according to claim 33 or 34, wherein the stiffening mandrel is configured to stiffen the catheter shaft along a length thereof, the length extending proximally from the collapsed section.Attorney Docket No.: POMD04601PRI_US0136. The tissue treatment catheter according to any one of claims 33 through 35, wherein the catheter shaft further defines a fluid lumen and a cable lumen, and wherein the treatment catheter comprises a balloon and an ultrasound transducer, the balloon and the ultrasound transducer mounted on the catheter shaft, the balloon defining an interior in fluid communication with the fluid lumen, the ultrasound transducer contained within the interior of the balloon, the ultrasound transducer electrically coupled to an electrical cable within the cable lumen, the ultrasound transducer configured to emit acoustic energy.

37. The tissue treatment catheter according to any one of claims 33 through 36, wherein the collapsed section is conformed about a portion of the tapered segment to fix the stiffening mandrel to the catheter shaft, the collapse section conformed about the tapered segment by exposing the catheter shaft to elevated temperatures, the tapered segment spaced apart from an inner shaft wall of the catheter shaft prior to exposing the catheter shaft to elevated temperatures.

38. The tissue treatment catheter according to any one of claims 33 through 37, further comprising a transitional element disposed between the collapsed section and at least a portion of the tapered segment.

39. The tissue treatment catheter according to claim 38 wherein (i) the transitional element has a width between 2 mm and 8 mm, preferably 5 mm; and / or (ii) is made of thermal plastic.

40. A method of manufacturing a tissue treatment catheter, the method comprising: forming a guidewire port through an outer shaft wall of a catheter shaft, the catheter shaft defining a mandrel lumen coaxially aligned with a guidewire lumen; collapsing the outer shaft wall to form a collapsed section of the catheter shaftAttorney Docket No.: POMD04601PRI_US01 separating the mandrel lumen and the guidewire lumen, the collapsed section forming a ramp that tapers outward from a distal ramp end longitudinally to a proximal ramp end that is positioned at the outer shaft wall; and inserting a stiffening mandrel into the mandrel lumen, the stiffening mandrel having a tapered segment, the collapsed section conformed about at least a portion of the tapered segment to fix the stiffening mandrel to the catheter shaft.

41. The method according to claim 40, wherein inserting the stiffening mandrel into the mandrel lumen occurs before collapsing the outer shaft wall to form the collapsed section.

42. The method according to claim 40 or 41, further comprising mounting a balloon and an ultrasound transducer on the catheter shaft, the balloon defining an interior in fluid communication with a fluid lumen defined by the catheter shaft, the ultrasound transducer contained within the interior of the balloon, the ultrasound transducer configured to emit acoustic energy.

43. The method according to any one of claims 40 through 42, wherein collapsing the outer shaft wall includes bifurcating a first lumen into the guidewire lumen and the mandrel lumen.

44. The method according to any one of claim 40 through 43, wherein collapsing the outer shaft wall includes applying heat to the catheter shaft to reflow a portion of the catheter shaft about the stiffening mandrel and embed at least a portion of the tapered segment within the collapsed section, the tapered segment configured to prevent burn-through of the catheter shaft during collapsing of the outer shaft wall.Attorney Docket No.: POMD04601PRI_US0145. The method according to claim 44, wherein applying heat to the catheter shaft includes applying heat with a temperature in the range of 340 degrees Fahrenheit to 350 degrees Fahrenheit for a duration in the range of 5 seconds to 15 seconds.

46. The method according to claim 45, wherein collapsing the outer shaft wall includes cooling the tissue treatment catheter to allow the collapses section to fix the stiffening mandrel in place.

47. The method according to any one of claims 40 through 46, further comprising disposing a transitional element between the collapsed section and at least a portion of the tapered segment.

48. The method according to claim 47 wherein (i) the transitional element has a width between 2 mm and 8 mm, preferably 5 mm; and / or (ii) is made of thermal plastic.

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