Intravascular lithotripsy catheter with interfering shock waves

Abstract

To provide a catheter for treating an occlusion in a body lumen.SOLUTION: A catheter includes an elongated tube, and a first electrode pair and a second electrode pair each configured to generate shock waves. The catheter also includes a flexible polymer enclosure that is fillable with conductive fluid and wrapped circumferentially around at least a portion of the elongated tube such that it surrounds the first and second electrode pairs. The first and second electrode pairs can be arranged relative to one another to promote interference between shock waves generated at the electrode pairs when voltage is delivered across the electrodes of each pair. The electrode pairs can be longitudinally adjacent (a relatively small longitudinal distance apart), longitudinally aligned (at the same longitudinal location), circumferentially offset (offset about the circumference of the catheter), circumferentially aligned (at the same circumferential location), or any combination of any of the above.SELECTED DRAWING: Figure 2A

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Application No. 63 / 257,397, filed October 19, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates generally to the field of medical devices and methods, and more particularly to a shockwave catheter device for treating calcified lesions and obstructions in blood vessels and calcified lesions in body cavities, such as kidney stones in the urinary system. [Background technology]

[0003] A wide variety of catheters have been developed to treat calcified lesions, such as those in vessels associated with arterial disease. For example, treatment systems for percutaneous coronary angioplasty or peripheral angioplasty use angioplasty balloons to dilate the calcified lesion and restore normal blood flow in the vessel. In these types of procedures, a catheter carrying a balloon is advanced into the vessel along a guidewire until the balloon is aligned with the calcified plaque. The balloon is then pressurized (usually above 10 atm), causing the balloon to expand within the vessel, pushing the calcified plaque back into the vessel wall and dilating the occluded area of ​​the vessel.

[0004] More recently, catheters have been developed that include pairs of electrodes for generating shock waves inside an angioplasty balloon. Shock wave devices can be particularly effective for treating calcified lesions because the acoustic pressure from the shock waves can disrupt and disrupt lesions in the vicinity of the angioplasty balloon without harming surrounding tissue. In these devices, the catheter is advanced over a guidewire through the patient's vasculature until it is positioned proximal to and / or aligned with a calcified lesion in a body cavity. The balloon is then inflated with a conductive fluid (using a relatively low pressure of 2-4 atm) so that the balloon expands and contacts the lesion. A voltage can then be applied to the electrodes of the electrode pair to create acoustic shock waves that propagate through the walls of the angioplasty balloon and into the lesion. Once the lesion has been disrupted by the acoustic shock waves, the balloon can be further expanded to increase the cross-sectional area of ​​the lumen and improve blood flow through the vessel.

[0005] Efforts have been made to improve the delivery of shock waves in these devices, for example by directing the shock waves in a forward direction to break up the tougher, more difficult to cross blockages in the vessel. Examples of forward firing designs can be found in U.S. Pat. No. 10,966,737 and U.S. Publication No. 2019 / 0388110, both of which are incorporated herein by reference. Other catheter devices have been designed to include arrays of low-profile electrode assemblies that reduce the catheter's transverse profile, allowing the catheter to more easily navigate calcified vessels and deliver shock waves into more severely blocked areas of the vessel. For example, U.S. Pat. Nos. 8,888,788 and 10,709,462, both of which are incorporated herein by reference, provide examples of low-profile electrode assemblies.

[0006] Despite these advances, many currently available shockwave catheters have challenges generating shockwaves with sufficient acoustic pressure to treat dense and difficult to disrupt calcium or eccentric calcium in large arterial vessels. First, the total lesion disruption energy delivered by a shockwave catheter is limited by the voltage source used to induce shockwave formation. Many conventional shockwave catheter devices use high-voltage pulse generators, but these generators only deliver a limited range of voltages, and extremely high voltages can risk bursting the catheter balloon and damaging the patient's vasculature during shockwave treatment. Second, many shockwave catheter designs distribute energy to an electrode assembly in which more than one pair of electrodes are connected in series and spaced along the catheter at a distance of six millimeters (6 mm) or more apart. When electrode pairs are spaced more than 6 mm apart from each other, the acoustic shockwaves generated by each of the electrode pairs can propagate individually with little overlap with adjacent waves, resulting in the delivery of a lower pressure single wavefront shockwave. In addition, when multiple electrode pairs are connected in series on the same voltage channel, the voltage is distributed evenly between the electrodes, which reduces the peak pressure of the shock waves generated at each electrode pair, thereby resulting in an array of shock waves with relatively lower peak pressures. Third, some current shock wave catheter designs include emitters that each include a pair of electrode pairs arranged circumferentially 180 degrees apart from each other. When separated circumferentially by 180 degrees on the emitter, the acoustic shock waves emitted from those electrode pairs propagate individually in opposite directions with little overlap with the shock waves of the corresponding electrode pairs at the same longitudinal location (i.e., on the same emitter). Thus, there is an unmet need for a catheter design that can generate acoustic shock waves of increased pressure using a conventional voltage generator. Similar devices are needed to treat blockages formed in other parts of the body, such as kidney stones in the urinary system. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Pat. No. 10,966,737 [Patent Document 2] US Publication No. 2019 / 0388110 [Patent Document 3] U.S. Pat. No. 8,888,788 [Patent Document 4] U.S. Pat. No. 10,709,462 Summary of the Invention [Means for solving the problem]

[0008] The above objects are realized in a catheter including an electrode assembly with electrode pairs located in close proximity to one another such that shock waves emitted from each electrode pair interfere constructively with one another. When shock waves generated from electrode pairs in close proximity to one another interfere constructively, the combined shock waves have a higher pressure than the shock waves of each individual emitter, which allows the combined shock waves to treat denser and more rigid calcified lesions within a body cavity.

[0009] In one or more embodiments, the electrode pairs located inside the flexible enclosure of the catheter are spaced a relatively short distance (e.g., 1 mm to 4 mm) from each other along the length of the catheter. Spaced electrode pairs a relatively short distance from each other promotes constructive interference between acoustic shock waves generated at adjacent electrode pairs, thereby increasing the pressure of the combined shock waves. In one or more embodiments, the catheter includes one or more emitters each including a pair of electrode pairs located at the same longitudinal location (i.e., on the same emitter) along the length of the catheter, and the electrode pairs can be arranged circumferentially on the emitter less than 180 degrees apart from each other. Arranging electrode pairs of the same emitter less than 180 degrees apart promotes constructive interference between acoustic shock waves generated at adjacent electrode pairs, thereby increasing the pressure of the combined shock waves. When a catheter includes multiple emitters (each including a pair of electrode pairs separated by less than 180 degrees from each other on the emitter), the emitters can be spaced a relatively short distance (e.g., 1 mm to 4 mm) from each other along the length of the catheter. Spaced emitters a relatively short distance from each other promotes constructive interference between acoustic shock waves generated at adjacent emitters, thereby increasing the pressure of the combined shock waves.

[0010] An exemplary implementation provides a catheter for treating an occlusion in a body cavity. The catheter includes an elongated tube and a flexible polymer enclosure that is fillable with a conductive fluid and that is circumferentially disposed around at least a portion of the elongated tube. The catheter also includes a first electrode pair and a second electrode pair located inside the flexible enclosure, the first electrode and the second electrode, respectively, configured to generate a shock wave when a voltage is delivered to the electrodes. The electrodes of each electrode pair are generally separated by a distance, referred to as a spark gap, where electricity will traverse (jump) through the conductive fluid and generate a vapor bubble.

[0011] In one or more embodiments, the gaps between the electrodes of each electrode pair can be circumferentially aligned with one another relative to the elongated tube (e.g., the gap between the first and second electrodes of a first electrode pair can be located at the same location along the circumference of the catheter as the gap between the first and second electrodes of a second electrode pair) and separated by a distance of 1 mm to 4 mm along the length of the catheter (e.g., a longitudinal gap) such that shock waves generated at the electrode pairs constructively interfere to produce a combined shock wave.

[0012] In another implementation, the gaps between the electrodes of each electrode pair may be circumferentially offset from one another relative to the extension tube by less than 180 degrees so that shock waves generated at the electrode pairs constructively interfere, resulting in a combined shock wave, but may be located at essentially the same longitudinal location on the extension tube. When located at the same longitudinal location, the electrode pairs may be referred to as being located on the same "emitter." Thus, a catheter that includes an emitter includes one or more electrode pairs at the same longitudinal location.

[0013] Optionally, the catheter can include multiple adjacent emitters configured to generate shock waves that constructively interfere with each other. When a voltage is delivered to the emitters, individual shock waves generated at electrode pairs of adjacent emitters can constructively interfere with each other to form a combined shock wave, provided that the circumferential and / or longitudinal gap between the electrode pairs allows the electrode pairs on the adjacent emitters to remain sufficiently close to each other.

[0014] In one or more embodiments, the catheter may include a first emitter having first and second electrode pairs circumferentially offset from one another at an angle of 180 degrees, and a second emitter having third and fourth electrode pairs circumferentially offset from one another at an angle of 180 degrees, the first emitter and second emitter separated by a longitudinal gap of 1 mm to 4 mm and arranged such that at least one electrode pair of the first emitter is circumferentially aligned with an electrode pair of the second emitter (e.g., located at the same circumferential location of the catheter but longitudinally spaced apart).

[0015] Similarly, in another embodiment, the first emitter and the second emitter each include first and second electrode pairs that are circumferentially offset from one another by an angle of less than 180 degrees, the first and second emitters can be separated by a longitudinal gap of 1 mm to 4 mm, and arranged such that at least one electrode pair of the first emitter is circumferentially aligned with an electrode pair of the second emitter. Optionally, none of the electrode pairs of the first emitter and the second emitter are circumferentially aligned with one another. The present invention provides, for example, the following items. (Item 1) 1. A catheter for treating an obstruction in a body cavity, the catheter comprising: An extension tube; a flexible enclosure circumferentially disposed about at least a portion of the elongated tube, the flexible enclosure being fillable with a conductive fluid; a first electrode pair located inside the flexible enclosure and configured to generate shock waves, the first electrode pair having a first electrode and a second electrode separated by a gap; a second electrode pair located inside the flexible enclosure and configured to generate shock waves, the second electrode pair having a first electrode and a second electrode separated by a gap; Equipped with a gap of the second electrode pair is circumferentially aligned with a gap of the first electrode pair relative to the elongated tube, and a distance between the gap of the first electrode pair and the gap of the second electrode pair is between 1 mm and 4 mm such that when a voltage is applied across the first electrode pair and the second electrode pair, shock waves generated at the first electrode pair and the second electrode pair constructively interfere to produce a combined shock wave. (Item 2) The first electrode pair is a first insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; a first conductive sheath circumferentially mounted about the elongated tube; Equipped with The second electrode pair is a second insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; a second conductive sheath mounted circumferentially around the elongated tube; and Equipped with when a voltage is applied across the first insulated wire and the second insulated wire, a current is configured to flow across the gap between the insulation removed portion of the first insulated wire and the first conductive sheath to generate a first shock wave, and the current is further configured to flow across the gap between the second conductive sheath and the insulation removed portion of the second wire to generate a second shock wave. Item 1. The catheter according to item 1. (Item 3) 3. The catheter of claim 2, wherein the first conductive sheath comprises an arcuate cutout formed on a side edge of the first conductive sheath, and the current is configured to flow between the arcuate cutout and an insulation removed portion of the first insulated wire. (Item 4) 3. The catheter of claim 2, wherein the first conductive sheath comprises a circular cutout located between opposing side edges of the first conductive sheath, and the current is configured to flow between the circular cutout and an insulation removed portion of the first insulated wire. (Item 5) a third electrode pair located inside the flexible enclosure and configured to generate shock waves, the third electrode pair having a first electrode and a second electrode separated by a gap; a fourth electrode pair located inside the flexible enclosure and configured to generate shock waves, the fourth electrode pair having a first electrode and a second electrode separated by a gap; Further equipped with 3. The catheter of claim 2, wherein a gap of the fourth electrode pair is circumferentially aligned with a gap of the third electrode pair relative to the elongated tube, and a distance between the gap of the third electrode pair and the gap of the fourth electrode pair is between 1 mm and 4 mm such that when a voltage is delivered across the third electrode pair and the fourth electrode pair, shock waves generated at the third electrode pair and the fourth electrode pair interfere and produce a combined shock wave. (Item 6) The third electrode pair is the first conductive sheath; a third insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; Equipped with The fourth electrode pair is the second conductive sheath; and a further insulation removed portion of the third insulated wire; Equipped with when a voltage is applied across the first insulated wire and the second insulated wire, a current is configured to flow across the gap between the first conductive sheath and an insulation removed portion of the third insulated wire to generate a third shock wave, and the current is further configured to flow across the gap between the second conductive sheath and a further insulation removed portion of the third insulated wire to generate a fourth shock wave. Item 6. The catheter according to item 5. (Item 7) 6. The catheter of claim 5, wherein the third electrode pair is circumferentially offset from the first electrode pair by approximately 180 degrees relative to the elongated tube. (Item 8) 3. The catheter of claim 2, wherein an outer surface of the elongate tube includes a groove, and the first insulated wire and the second insulated wire extend along the groove of the elongate tube. (Item 9) Item 1 , the catheter of item 1 , wherein the elongate tube includes a guidewire lumen for receiving a guidewire, the catheter being configured to be advanced into the body lumen over the guidewire. (Item 10) 1. A catheter for treating an obstruction in a body cavity, the catheter comprising: An extension tube; a flexible enclosure circumferentially disposed about at least a portion of the elongated tube, the flexible enclosure being fillable with a conductive fluid; a first electrode pair located inside the flexible enclosure and configured to generate shock waves, the first electrode pair having a first electrode and a second electrode separated by a gap; a second electrode pair located inside the flexible enclosure and configured to generate shock waves, the second electrode pair having a first electrode and a second electrode separated by a gap; Equipped with a gap of the second electrode pair located at essentially the same longitudinal location on the elongated tube as the gap of the first electrode pair and circumferentially offset from the gap of the first electrode pair by an angle less than 180 degrees such that when a voltage is applied across the first electrode pair and the second electrode pair, shock waves generated at the first electrode pair and the second electrode pair constructively interfere to produce a combined shock wave. (Item 11) Item 11. The catheter according to item 10, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other by an angle of 40 to 140 degrees. (Item 12) Item 11. The catheter of item 10, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other by an angle of 65 to 125 degrees. (Item 13) Item 11. The catheter of item 10, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other by an angle of 80 to 100 degrees. (Item 14) Item 11. The catheter of item 10, wherein the circumferential offset between the gap of the first electrode pair and the gap of the second electrode pair is selected such that the peak pressure of the combined shock wave exceeds the peak pressure of a shock wave generated by a catheter having first and second electrode pairs having gaps that are circumferentially offset at an angle of 180 degrees relative to one another. (Item 15) The first electrode pair is a first conductive sheath circumferentially mounted about the elongated tube; a first insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; Equipped with The second electrode pair is the first conductive sheath; a second insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; Equipped with when a voltage is applied across the first insulated wire and the second insulated wire, a current is configured to flow across a gap between an insulation removed portion of the first insulated wire and the first conductive sheath to generate a first shock wave, and the current is further configured to flow across the gap between the first conductive sheath and an insulation removed portion of the second wire to generate a second shock wave. 11. The catheter according to item 10. (Item 16) Item 16. The catheter of item 15, wherein the first conductive sheath comprises an arcuate cutout formed on a side edge of the first conductive sheath, and the current is configured to flow between the arcuate cutout and an insulation removed portion of the first insulated wire. (Item 17) Item 16. The catheter of item 15, wherein the first conductive sheath comprises a circular cutout located between opposing side edges of the first conductive sheath, and the current is configured to flow between the circular cutout and an insulation removed portion of the first insulated wire. (Item 18) Item 16. The catheter of item 15, wherein an outer surface of the elongate tube includes a groove, and the first insulated wire and the second insulated wire extend along the groove of the elongate tube. (Item 19) a third electrode pair located inside the flexible enclosure and configured to generate shock waves, the third electrode pair having a first electrode and a second electrode separated by a gap; a fourth electrode pair located inside the flexible enclosure and configured to generate shock waves, the fourth electrode pair having a first electrode and a second electrode separated by a gap; Further equipped with a gap of the fourth electrode pair is located at essentially the same longitudinal location on the extension tube as a gap of the third electrode pair and is circumferentially offset from the gap of the third electrode pair by an angle of less than 180 degrees such that when a voltage is applied across the third electrode pair and the fourth electrode pair, shock waves generated at the third electrode pair and the fourth electrode pair constructively interfere to produce a combined shock wave; the third electrode pair and the fourth electrode pair are separated from the first electrode pair and the second electrode pair by a longitudinal distance of 1 mm to 4 mm along the extension tube such that when a voltage is delivered across each of the first electrode pair, the second electrode pair, the third electrode pair, and the fourth electrode pair, shock waves generated by each of the first electrode pair, the second electrode pair, the third electrode pair, and the fourth electrode pair interfere to produce a combined shock wave. 11. The catheter according to item 10. (Item 20) The third electrode pair is a second conductive sheath; and a third insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; Equipped with The fourth electrode pair is the second conductive sheath; and a further insulation removed portion of the third insulated wire; Equipped with when a voltage is applied across the first insulated wire and the second insulated wire, a current is configured to flow across the gap between the second conductive sheath and an insulation removed portion of the third insulated wire to generate a third shock wave, and the current is further configured to flow across the gap between the second conductive sheath and a further insulation removed portion of the third insulated wire to generate a fourth shock wave. 20. The catheter according to item 19. (Item 21) 20. The catheter of claim 19, wherein the first electrode pair gap and the second electrode pair gap are circumferentially offset from one another at the same angle as the offset between the third electrode pair gap and the fourth electrode pair gap. (Item 22) 20. The catheter of claim 19, wherein the circumferential offset between the first electrode pair gap and the second electrode pair gap is circumferentially aligned with the offset between the third electrode pair gap and the fourth electrode pair gap relative to the elongated tube. (Item 23) 20. The catheter of claim 19, wherein the circumferential offset between the first electrode pair gap and the second electrode pair gap is circumferentially offset from the circumferential offset between the third electrode pair gap and the fourth electrode pair gap by approximately 180 degrees relative to the elongated tube. (Item 24) Item 11. The catheter of item 10, wherein the elongate tube includes a guidewire lumen for receiving a guidewire, the catheter being configured to be advanced into the body lumen over the guidewire. [Brief description of the drawings]

[0016] Exemplary aspects of the present disclosure are described in detail below with reference to the following drawing figures: It is intended that the embodiments and figures disclosed herein be considered illustrative, not restrictive.

[0017] [Figure 1] FIG. 1 illustrates an exemplary catheter having an array of emitters inside an angioplasty balloon in accordance with an aspect of the present disclosure.

[0018] [Figure 2A] FIG. 2A illustrates the spacing of adjacent emitters with an exemplary electrode assembly formed from an insulated wire and a conductive sheath with a circular cutout, in accordance with an aspect of the present disclosure.

[0019] [Figure 2B] FIG. 2B illustrates the spacing of adjacent emitters with an exemplary electrode assembly formed from an insulated wire and a conductive sheath having an arcuate cutout, in accordance with aspects of the present disclosure.

[0020] [Figure 3A] FIG. 3A illustrates an exemplary electrode assembly of a catheter according to an aspect of the present disclosure.

[0021] [Figure 3B]FIG. 3B illustrates current flow through the exemplary electrode assembly of FIG. 3A, according to aspects of the present disclosure.

[0022] [Figure 4A] FIG. 4A illustrates a front side view of an exemplary electrode assembly having a proximal pair of emitters, a central pair of emitters, and a distal pair of emitters in accordance with aspects of the present disclosure.

[0023] [Figure 4B] FIG. 4B illustrates wiring of the exemplary electrode assembly of FIG. 4A, according to an aspect of the present disclosure.

[0024] [Figure 4C] FIG. 4C illustrates a top side view of the exemplary electrode assembly of FIG. 4A in accordance with an aspect of the present disclosure.

[0025] [Figure 4D] FIG. 4D illustrates a top side view of the example electrode assembly wiring of FIG. 4B in accordance with an aspect of the present disclosure.

[0026] [Diagram 5] FIG. 5 provides an image of an exemplary shockwave catheter according to an aspect of the present disclosure.

[0027] [Figure 6] FIG. 6 provides a series of heat map graphics illustrating the pressure of an acoustic wavefront generated by an exemplary catheter such as shown in FIG. 5 in accordance with an aspect of the present disclosure.

[0028] [Figure 7] FIG. 7 provides two graphs illustrating the pressure of an acoustic wavefront measured along the balloon edge of an exemplary catheter in accordance with aspects of the present disclosure.

[0029] [Figure 8] FIG. 8 provides a series of images of bubble formation and collapse resulting from activation of an emitter of an exemplary catheter in accordance with aspects of the present disclosure.

[0030] [Figure 9] FIG. 9 illustrates an exemplary electrode assembly having a pair of electrodes at the same longitudinal location but circumferentially offset from one another by 60 degrees, in accordance with an aspect of the present disclosure.

[0031] [Figure 10] FIG. 10 provides an image of an exemplary shockwave catheter with an electrode assembly having a pair of electrode pairs at the same longitudinal location but circumferentially spaced apart from each other by 60 degrees, in accordance with an aspect of the present disclosure.

[0032] [Figure 11] FIG. 11 provides a series of images of bubble formation and collapse resulting from activation of an exemplary catheter in accordance with aspects of the present disclosure.

[0033] [Figure 12] FIG. 12 provides a graph illustrating the pressure of an acoustic wavefront from a single emitter measured along the balloon edge of an exemplary catheter in accordance with an aspect of the present disclosure.

[0034] [Figure 13A] FIG. 13A illustrates a right front view of an exemplary electrode assembly for a catheter having multiple pairs of emitters spaced along the length of the catheter.

[0035] [Figure 13B] FIG. 13B illustrates a left front view of the exemplary electrode assembly of FIG. 13A.

[0036] [Figure 14] FIG. 14 provides an image of an exemplary shockwave catheter with a first emitter having a pair of electrode pairs with the same longitudinal location but that are circumferentially offset relative to each other, and a second emitter having a pair of electrode pairs with the same longitudinal location but that are circumferentially offset relative to each other, in accordance with aspects of the present disclosure.

[0037] [Figure 15] FIG. 15 provides a series of images of bubble formation and collapse resulting from activation of an exemplary catheter in accordance with aspects of the present disclosure.

[0038] [Figure 16] FIG. 16 provides a graph illustrating the pressure of an acoustic wavefront from a pair of emitters measured along the balloon edge of an exemplary catheter in accordance with an aspect of the present disclosure.

[0039] [Figure 17] FIG. 17 illustrates an exemplary catheter electrode assembly having an emitter with a single electrode pair in accordance with an aspect of the present disclosure.

[0040] [Figure 18] FIG. 18 illustrates a right front view of an exemplary electrode assembly having a pair of emitters, each with a single electrode pair, spaced along the length of the catheter in accordance with an aspect of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Detailed Description The following description is presented to enable those skilled in the art to make and use the various embodiments and aspects thereof disclosed herein. Descriptions of specific devices, assemblies, techniques, and applications are provided only as examples. Various modifications of the examples described herein will be readily apparent to those skilled in the art, and the general principles described herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments and aspects thereof. Thus, the various embodiments and aspects thereof are not intended to be limited to the examples described and shown herein, but are to be accorded the scope consistent with the claims.

[0042] As used herein, the term "electrode" refers to a conductive element (typically made of metal) that receives and subsequently emits current to another conductive element. In the context of this disclosure, electrodes are often positioned relative to each other as an inner electrode and an outer electrode. Thus, as used herein, an "electrode pair" refers to two electrodes positioned adjacent to each other such that current will be transmitted across the gap between the two electrodes (e.g., between an inner electrode and an outer electrode (or vice versa), optionally with an insulator separating the two electrodes and electricity passing through a conductive fluid or gas between them). In some contexts, one or more electrode pairs (positioned across one or more emitters) may also be referred to as an electrode assembly. Furthermore, as used herein, an "emitter" refers to a structure having one or more electrode pairs. Emitters can be single, paired, or otherwise arranged together to be electrically connected as an emitter assembly. A shock wave can be generated at each electrode pair of the emitter.

[0043] Described herein are catheters that incorporate design elements that improve the efficiency and increase the peak pressure of acoustic shock waves delivered from a shockwave catheter device. In one or more embodiments, the catheter includes an emitter pair electrode assembly with reduced spacing between adjacent emitters to promote interference between shock waves generated at the electrode pairs of adjacent emitters. When the electrode pairs of adjacent emitters are activated together, the acoustic pressure wavefronts of the shockwaves can constructively interfere, resulting in overlapping or combined acoustic pressure wavefronts (i.e., combined shockwaves). In one or more embodiments, the catheters described herein include emitter assemblies with electrode pairs located on separate adjacent emitters that are longitudinally adjacent to each other on the catheter, such as spaced apart by a longitudinal gap of one to four millimeters (1 mm to 4 mm).

[0044] In one or more embodiments, the catheters described herein include an emitter assembly having pairs of electrodes located at the same longitudinal location on the catheter (and on the emitter). The electrode pairs of the emitters can be circumferentially offset (e.g., spaced apart) from one another by 180 degrees or less than 180 degrees. Optionally, a first electrode pair on a first emitter at a first longitudinal location can be located proximate to a second electrode pair on a second emitter and spaced apart longitudinally on the catheter. The electrode pairs on each of the first and second emitters can be arranged such that they are circumferentially aligned with one another (e.g., the first electrode pair of the first emitter is positioned at the same circumferential location as the first electrode pair of the second emitter) or such that they are offset from one another (e.g., the first electrode pair of the first emitter is circumferentially offset from the first electrode pair of the second emitter). In one or more embodiments, the catheters described herein include an electrode assembly having an emitter with a single electrode pair and / or a single emitter with a pair of electrode pairs.

[0045] As used herein, a "combined shock wave" includes two or more shock waves produced by closely spaced adjacent emitter pairs that are activated together (e.g., activated by the same high voltage pulse that generates the shock waves simultaneously or nanoseconds apart). Constructive interference between adjacent shock waves can result in high amplitude combined shock waves with higher peak pressures compared to shock waves delivered from conventional shock wave catheters with relatively increased emitter spacing (e.g., see peaks in graph of FIG. 7). Closely spaced electrode pairs and / or closely spaced emitters can also produce combined shock waves with overlapping, higher pressure, multiple (e.g., dual) wavefronts propagating at slightly different angles, producing a "double hit" effect that delivers increased mechanical forces and shear stresses to the lesion (e.g., see pressure wavefronts in the bottom row shown in FIG. 6).

[0046] The catheter designs described herein may be similar to current shockwave catheters in that they include an array of miniaturized emitters, each with one or more electrode pairs along the catheter (e.g., within the working length of an angioplasty balloon), that deliver acoustic shockwaves to a treatment site surrounding the catheter. However, in one embodiment, the present design arranges adjacent emitters about 3.5 mm or less apart along the length of the catheter. In some embodiments, adjacent emitters are arranged in pairs, with each pair of adjacent emitters spaced 3.5 mm or less apart. In some implementations, the longitudinal distance between two adjacent emitters is more precisely the distance between the midpoints of two sets of electrode pairs, one on each emitter, and the electrode pairs can be on the edge of the emitter and / or more centrally located within the body of the emitter. When longitudinally displaced but closely spaced emitters are fired together, bubbles generated from adjacent emitters grow and collapse toward each other, producing a combined shock wave. In one or more embodiments, the pairs of electrodes on each emitter are located at the same longitudinal location on the catheter, but are circumferentially spaced from each other by increments and gradients less than 180 degrees, such as, for example, 120 degrees, 90 degrees, or 60 degrees, and ranges therein. Exemplary ranges for circumferential offsets can include, but are not limited to, angles within the ranges of 40 degrees to 140 degrees, 65 degrees to 125 degrees, 80 degrees to 100 degrees, and the like. Thus, the electrode and emitter arrays as disclosed herein provide implementations of shock wave generation that impart directionality or directional bias to the progression of the shock waves. When longitudinally aligned but circumferentially shifted emitters are fired together, bubbles generated from adjacent emitters grow and collapse toward each other, creating a combined shock wave. The increased peak pressure and dual wavefronts of the combined shock wave maximize the calcification effectiveness of the catheter, which may be particularly beneficial for treating dense and difficult to fracture calcium, eccentric calcium, and calcium within large arterial vessels.Also, shock waves with increased intensity can maintain therapeutic levels of force in larger diameter balloons where there is a longer distance for the shock waves to travel from the emitter to the target tissue region.

[0047] 1 illustrates an exemplary catheter 100 having an array of emitters inside an angioplasty balloon in accordance with aspects of the present disclosure. The catheter 100 includes a shaft, more specifically, an elongated tube 104, that extends between a proximal handle 126 of the catheter and a distal tip of the catheter. A flexible polymer encapsulation 102 (e.g., a flexible angioplasty balloon or some other compliant or semi-compliant polymer encapsulation) is circumferentially disposed around at least a portion of the elongated tube 104 and sealed to the elongated tube 104 via a seal 122 located near the distal tip of the catheter 100. The flexible polymer encapsulation 102 forms an annular cavity 124 around the elongated tube 104 that may be filled with a conductive fluid, such as saline or saline mixed with a contrast agent, to fill and / or inflate the flexible polymer encapsulation 102. Conductive fluid may be placed into cavity 124 via a fill port located in proximal handle 126. Flexible polymer encapsulation 102 also encloses several emitters 111, 112, 113, 114, 115, 116 located inside flexible polymer encapsulation 102 that are configured to generate shock waves in the conductive fluid inside cavity 124. As shown, the emitters may be arranged in pairs, with emitters 111 and 112 as a proximal pair, emitters 113 and 114 as a central pair, and emitters 115 and 116 as a proximal pair. Collectively, emitters 111, 112, 113, 114, 115, 116 may be referred to as an emitter assembly.

[0048] The elongated tube 104 may include several lumens (e.g., longitudinal channels through the tube 104) that extend between the proximal handle 126 and the distal end of the catheter 100. For example, the elongated tube 104 may include a fluid lumen for carrying a conductive fluid between the fluid port and the cavity 124 of the flexible polymer enclosure 102 to fill (i.e., expand) and / or evacuate the enclosure 102 during shock wave therapy. The elongated tube 104 may also include a guidewire lumen that is sized to receive a guidewire 120 to facilitate insertion and positioning of the catheter 100. In such an embodiment, the catheter 100 may be configured to be advanced into a body cavity over the guidewire 120 (generally referred to as an "over-the-wire" or "OTW" arrangement). (In an alternative implementation, the catheter may be arranged as part of a "rapid exchange" or "Rx" configuration, where instruments are swapped in and out of lumens within the patient during a procedure.) The extension tube 104 may also include several wire lumens for retaining wires (e.g., polyimide insulated copper wires) that carry electrical current between the high voltage pulse generator 150 and the emitters 111, 112, 113, 114, 115, 116. Additionally or alternatively, the outer surface of the extension tube 104 may include several longitudinal grooves or channels configured for retaining wires, and the insulated wires may extend along the grooves in the outer surface of the extension tube 104.

[0049] Shock waves can be generated inside the flexible polymer encapsulation 102 in several emitters 111, 112, 113, 114, 115, 116 spaced along the length of the elongated tube 104. In some embodiments, the emitters 111, 112, 113, 114, 115, 116 are formed from a conductive metal sheath and insulated wire positioned around or mounted on the outer surface of the elongated tube 104. High voltage pulses are supplied to the emitters 111, 112, 113, 114, 115, 116 from a high voltage pulse generator 150 external to the catheter 100. In some embodiments, the high voltage pulse generator 150 includes a multiplexing device to selectively apply voltage across a particular emitter (e.g., emitter 111) or pair of emitters (e.g., emitters 111 and 112) to generate shock waves at desired locations within the flexible polymer encapsulation 102. Thus, emitters or emitter pairs as shown are connected on the same or separate electrical channels and the current flow to a given channel can be controlled via the multiplexing device. In other embodiments, a high energy laser is used to generate shock waves by pulsing laser light inside the flexible polymer encapsulation 102. In such embodiments, the catheter 100 may include two or more optical fibers whose output ends are closely spaced together to generate shock waves that interfere constructively.

[0050] In operation, a physician inserts a guidewire 120 into the body cavity through the guidewire lumen, then advances the catheter 100 into the body cavity over the guidewire 120 and uses the guidewire 120 to steer the elongate tube 104 into position at or adjacent to the target lesion. Once positioned at the lesion, the cavity 124 can be at least partially filled with a conductive fluid (e.g., to a pressure of about 4 atm) to expand the flexible polymer encapsulation 102. Once expanded, the flexible polymer encapsulation 102 gently contacts and / or conforms to the wall of the lumen directly adjacent to the calcified lesion, providing space between the emitters 111, 112, 113, 114, 115, 116 and the wall of the flexible polymer encapsulation 102. The variable high-voltage pulse generator 150 can then be activated to deliver a series of high-voltage pulses across one or more of the emitters 111, 112, 113, 114, 115, 116 to generate shock waves within the flexible polymer encapsulation 102.

[0051] Each voltage pulse applied by the generator 150 creates a potential difference across each electrode pair on the emitter. The duration and magnitude of the voltage pulse is sufficient to generate gas bubbles in the conductive fluid on the surfaces of the electrodes. Eventually, a plasma arc of current is formed, which traverses the bubbles and creates a rapidly expanding and collapsing bubble that creates an acoustic shock wave within the flexible polymer encapsulation 102. The magnitude and other characteristics of the shock wave can be controlled by adjusting the shock gap distance between the electrodes of the electrode pair, the surface area of ​​the electrodes, the shape of the electrodes, and / or the distance (relative to the length and / or circumference of the catheter) between adjacent electrode pairs. For example, when adjacent electrode pairs on separate emitters are spaced closely together (lengthwise and / or circumferentially) and activated simultaneously, the bubbles formed at these adjacent electrode pairs can expand and collapse together, creating a combined acoustic shock wave.

[0052] The combined acoustic shock waves are conducted through the conductive fluid in cavity 124, through the walls of flexible polymer encapsulation 102, and into the vessel wall, where the acoustic shock wave energy can disrupt calcified lesions and hardened plaque. The size of the bubbles and the rate of bubble expansion and collapse (and thus the duration and magnitude of the resulting combined acoustic shock waves) can be controlled by adjusting the magnitude, duration, and repetition rate of the voltage pulses applied by high voltage pulse generator 150. In some examples, a physician may begin the procedure with low energy shock waves and increase the energy as needed to disrupt calcified plaque.

[0053] 1, the emitters 111, 112, 113, 114, 115, 116 may be arranged in various groupings or pairs spaced along the length of the elongated tube 104 such that combined shock waves may be generated to treat lesions proximate various portions of the flexible polymer encapsulation 102. The location of the shock waves can be controlled by selectively applying a voltage across desired emitters and / or desired groupings or pairs of emitters. 1 includes a proximal pair including a first emitter 111 and a second emitter 112 located inside a proximal portion of the flexible polymer encapsulation 102, a central pair including a third emitter 113 and a fourth emitter 114 located inside a central portion of the flexible polymer encapsulation 102, and a distal pair including a fifth emitter 115 and a sixth emitter 116 located inside a distal portion of the flexible polymer encapsulation 102. The spacing between adjacent emitters of each pair (e.g., the distance between the first emitter 111 and the second emitter 112 of the proximal pair) is selected to promote constructive interference between shock waves generated by each pair of emitters. In some embodiments, the emitters of separate groups or pairs may be spaced apart a sufficient distance to avoid constructive interference between certain emitters (e.g., to avoid interference between a shock wave generated by the second emitter 112 of the proximal pair and a shock wave generated by the third emitter 113 of the central pair), and the separation distance between all emitters can be selected to avoid destructive interference between the shock waves generated.

[0054] To ensure that adjacent emitters fire at approximately the same time (e.g., at the same time or within a few nanoseconds), an exemplary catheter design can include an electrode assembly having two or more emitters connected in series on a single independent wiring channel. For example, the proximal, central, and distal pairs of emitters may each be wired as independent electrode assemblies that can be activated separately (e.g., the electrodes of the emitters in a given electrode assembly can be electrically connected in series such that a single high voltage pulse activates all emitters of the electrode assembly). For example, the proximal pair, including the first emitter 111 and the second emitter 112, may be wired together in the first electrode assembly. The central and distal emitter pairs may be wired in separate additional electrode assemblies such that the emitters of the central and distal pairs can be activated independently from the proximal pair and from each other. A single high voltage pulse can be applied across the desired electrode assemblies, for example, to activate emitters 111 and 112 together, or alternatively emitters 113 and 114 together, or alternatively emitters 115 and 116 together at approximately the same time. In further embodiments, a high voltage pulse can be directed across an electrode assembly including emitters 111, 112, and 113 together, and then additionally or alternatively to an electrode assembly including emitters 114, 115, and 116 together at approximately the same time. In other examples, emitters 111, 112, 113, 114, 115, 116 of catheter 100 are all wired in series such that application of a single high voltage pulse activates all of the emitters at approximately the same time (or in other words, in a rapid sequential progression that is effectively parallel for a therapeutic function). Constructive interference between closely spaced adjacent emitters can reduce or mitigate any pressure drop that results from distribution of a high voltage pulse across multiple emitters wired in series.

[0055] Figures 2A-B illustrate two exemplary electrode assemblies 200 that may be included in a catheter, such as electrode assemblies corresponding to the proximal, central, or distal pairs of emitters shown in Figure 1. Each emitter of an electrode assembly (e.g., any of the assemblies shown in Figures 1, 2A-B, 3A-B, 4A-D, 9, 13A-B, and 17-18 and described throughout this disclosure) includes an inner electrode and an outer electrode that form an electrode pair separated by a spark gap across which current flows to generate shock waves and / or cavitation bubbles. For example, as described in U.S. Patent No. 10,709,462, each emitter of a catheter (e.g., each pair of electrodes) may be formed from an edge of a conductive metal sheath and a conductive portion of an insulated wire extending along the catheter. In certain embodiments, the outer electrode of each electrode pair is formed from a conductive sheath, and the inner electrode is formed by removing a portion of the insulated wire (e.g., drilling a hole in the insulation layer near the end of the wire) to expose the conductive portion of the insulated wire (i.e., the insulation removed portion). In one or more embodiments, the inner electrode may be formed from a conductive sheath, and the outer electrode may be formed from the conductive portion of the insulated wire. The conductive portion of the wire is separated from the conductive sheath by a controlled distance (i.e., spark gap) to allow reproducible arcing of energy across the electrode for a given current and voltage. In some embodiments, two or more electrode pairs may be formed on the same emitter using a single conductive sheath by positioning two or more conductive portions of the insulated wire in close proximity to the sheath to create two spark gaps across which current may flow and generate shock waves.

[0056] 2A , the exemplary electrode assembly 200 includes at least a first electrode pair 262 and a second electrode pair 264 formed from first and second conductive sheaths 212, 214, respectively, mounted circumferentially around the elongated tube 204 and a series of insulated wires extending along the outer surface of the elongated tube 204. As shown, the first electrode pair 262 resides on the first emitter 282 and the second electrode pair 264 resides on the second emitter 284. 2B, the exemplary electrode assembly 200 includes at least a first electrode pair 263 and a second electrode pair 265 formed from separate first and second conductive sheaths 212, 214, respectively, mounted circumferentially around the elongated tube 204 and a series of insulated wires extending along the outer surface of the elongated tube 204. As shown, the first electrode pair 263 resides on the first emitter 282 and the second electrode pair 265 resides on the second emitter 284. In some embodiments, as will be further described below, each electrode assembly further includes a third electrode pair and a fourth electrode pair (not shown) formed from respective first and second conductive sheaths 212 and 214 (in other words, electrode pairs that share the same or nearly the same longitudinal location as electrode pairs 262 and 264 (or electrode pairs 263 and 265), but are circumferentially offset from one another on each emitter 282 and 284).

[0057] In the exemplary electrode assembly 200 shown in FIG. 2A, each conductive sheath 212, 214 includes a circular cutout configured to allow current to flow between the circular cutout and the conductive portion of the insulated wire (i.e., the insulation removed portion of the wire) to generate shock waves. In FIG. 2B, the side edge of each conductive sheath 212, 214 of the assembly includes an arcuate cutout configured to allow current to flow between the arcuate cutout and the conductive portion of the insulated wire to generate shock waves. In some embodiments, an insulating sheath 252, 254 is positioned between the conductive portion of the wire and each conductive sheath to prevent unintended current flow between the conductive portion of the wire and the conductive sheath 212, 214. The insulating sheath 252, 254 may include one or more holes or cutouts positioned in the gap between each of the conductive portions of the wire and the conductive sheath 212, 214 to provide a path through which current may flow between the electrodes of each emitter.

[0058] Optionally, an electrode pair can be formed from an electrode assembly without a sheath. For example, a pair of wires can be located in close proximity to one another, each containing a conductive portion (such as an insulation removed portion), and configured such that a current flows between the conductive portions of the wires. In such an embodiment, the current can jump from the conductive portion of the first wire to the conductive portion of the second wire, thereby generating a shock wave.

[0059] Each electrode pair of the assembly 200 has a longitudinal location along the length of the extension tube 204 and a circumferential location around the circumference of the extension tube 204. The longitudinal distance and / or circumferential offset between adjacent emitters and / or adjacent electrode pairs can be controlled to promote constructive interference between shock waves generated at the first emitter 282 and the second emitter 284. As shown in FIG. 2A, the first emitter 282 and the second emitter 284 and their respective electrode pairs 262, 264 are circumferentially aligned (i.e., located at the same circumferential location) and longitudinally separated by a distance "d". Similarly, in FIG. 2B, the first emitter 282 and the second emitter 284 and their respective electrode pairs 263, 265 are circumferentially aligned and longitudinally separated by a distance "d", which differs between the two configurations of the emitter assembly.

[0060] When the emitters of an electrode assembly are arranged in sufficiently close groupings or pairs based on their close longitudinal proximity to one another (e.g., arranged together in proximal, central, or distal pairs along the length of the catheter, as shown in FIGS. 1 and 4A-D), the term longitudinally adjacent indicates that the elements are arranged together in the same grouping or pair along the length of the catheter. For example, the first emitter 282 and the second emitter 284 of FIGS. 2A and 2B may be properly considered longitudinally adjacent emitters, while the second emitter 112 and the third emitter 113 of FIG. 1 may not be considered longitudinally adjacent because they correspond to separate emitter pairs. Thus, a catheter described as having 3.5 mm spacing between longitudinally adjacent emitters may include a series of emitters arranged in pairs, with the individual electrode pairs of the emitters spaced 3.5 mm apart from one another. In such embodiments, the distance between pairs of vertically adjacent emitters may be 3.5 mm, while the emitters of separate pairs may be spaced apart from one another by more than 3.5 mm (see, for example, FIG. 1, which shows a proximal emitter pair located in close proximity to one another but separated from a central emitter pair by a distance that exceeds the separation between emitters 111 and 112). In one or more examples, the distance between a first electrode pair of a first emitter and a first electrode pair of a second emitter may exceed the distance between a second electrode pair of the first emitter and a second electrode pair of the second emitter. In other embodiments, depending on the configuration of the emitter assembly and the power supplied thereto, the distance between emitters that qualify as vertically adjacent and their separate electrode pairs may range from 1 mm to 4 mm, or length increments and gradients within that range.

[0061] As used herein, the longitudinal distance ("d") between two adjacent emitters defines the distance between electrode pairs formed from two adjacent conductive sheaths (e.g., in FIG. 2A, the distance between first electrode pair 262 and second electrode pair 264 formed from separate first and second conductive sheaths 212 and 214), rather than the distance between two electrode pairs formed from a single conductive sheath (e.g., the circumferential distance or offset between a first electrode pair 262 and a third emitter (not shown) formed from the same conductive sheath 212). As used herein, the circumferential offset (angle "α") between two emitters formed from a single conductive sheath (i.e., on the same emitter) defines the angle by which those electrode pairs are offset from each other (e.g., an offset of 180 degrees indicates that the electrode pairs are located on opposite sides of the sheath). When longitudinally adjacent electrode pairs are located at the same circumferential location on the catheter (eg, zero degree offset), the electrode pairs can be considered to be circumferentially aligned.

[0062] The longitudinal distance and / or circumferential offset between adjacent electrode pairs can be measured with respect to the gap between the individual electrode pairs. For example, in FIG. 2A, assuming an exemplary distance of 3.5 mm between the first emitter 282 and the second emitter 284 indicates that the spark gap between the electrodes of the first electrode pair 262 is approximately 3.5 mm from the spark gap between the electrodes of the second electrode pair 264. In one or more embodiments, the longitudinal distance between adjacent electrode pairs may alternatively be approximated by the distance between adjacent conductive sheaths. For example, in FIG. 2B, assuming an exemplary distance of less than 3.5 mm indicates the longitudinal distance between the side edge of the first conductive sheath 212 that forms the arcuate electrode pair 263 of the first emitter 282 and the side edge of the second conductive sheath 214 that forms the electrode of the arcuate electrode pair 265 of the second emitter 284. Additionally or alternatively, the distance and / or circumferential offset between adjacent emitters may be approximated by the spacing or circumferential offset of insulation removed portions of insulated wires that form the electrode pairs of the emitters.

[0063] As explained above, longitudinally adjacent emitters of a pair may be spaced apart by a relatively short longitudinal distance (e.g., 4 mm or less) to promote constructive interference between shock waves generated at the electrode pairs of the individual emitters. In some embodiments, the distance between the gap of the electrode pair 262 of the first emitter 282 and the gap of the electrode pair 264 of the second emitter 284 is between 1 mm and 4 mm such that when a voltage is delivered across the first electrode pair 262 and the second electrode pair 264, the shock waves generated at the first emitter 282 and the second emitter 284 interfere and produce a combined shock wave.

[0064] Circumferential offsets between electrode pairs on adjacent emitters can also affect constructive interference between the emitters. For example, the longitudinal distance and circumferential offset between the first electrode pair 262, 263 and the second electrode pair 264, 265 can be selected such that a combined shock wave is formed when the first emitter 282 and the second emitter 284 are both activated (i.e., activated by the same high voltage pulse). In one or more embodiments, the circumferential location of the electrode pairs on each emitter can be selected such that the shock waves propagate in a particular direction relative to the elongated tube (e.g., to promote interference between shock waves propagating in the same direction). 2A and 2B, the gap of the first electrode pair 262, 263 is circumferentially aligned (e.g., offset by zero degrees) with the gap of the second electrode pair 264, 265 with respect to the extension tube 204 such that both emitters generate shock waves in approximately the same radial direction with respect to the extension tube 204. In some embodiments, in addition to the gaps of the first electrode pair 262, 263 and the second electrode pair 264, 265 being spaced apart by a distance of 1 mm to 4 mm, the gap of the first electrode pair 262, 263 is circumferentially aligned with the gap of the second electrode pair 264, 265.

[0065] In some examples, the longitudinal distance and / or circumferential offset between adjacent emitters and their respective electrode pairs can be selected to produce a combined shock wave that has a particular desired pressure increase relative to a non-interfering shock wave (e.g., a pressure increase relative to a shock wave produced from a single electrode pair or from emitters that are spaced such that there is limited or no interference between the shock waves). For example, the longitudinal distance between the spark gap of the first electrode pair 262 and the spark gap of the second electrode pair 264 can be selected such that the peak pressure of the combined shock wave is at least 1.25 times, at least 1.5 times, at least double (i.e., 2 times), or in relative increase increments and gradients within these values, compared to the peak pressure of a shock wave produced by a conventional shock wave catheter (e.g., a catheter having electrode pairs separated by a distance of 10 mm). The longitudinal distance and / or circumferential offset between adjacent emitters and their respective electrode pairs can also be selected to produce combined shock waves with dual pressure waveforms, increased shear stress, increased mechanical stress, or some other beneficial attribute for treating calcified lesions.

[0066] 3A-B provide more detailed views of an exemplary electrode assembly 300 that may be included in a shockwave catheter in accordance with aspects of the present disclosure. FIG. 3A provides a perspective view of the electrode assembly 300 disposed on a catheter extension tube 304. FIG. 3B provides an additional perspective view of the electrode assembly 300 without the extension tube 304, illustrating the connectivity and current flow through the electrode assembly 300.

[0067] 3A, the exemplary electrode assembly 300 can be implemented in a catheter that includes an elongated tube 304 having an outer surface that includes four longitudinal grooves 360, 362, 364, and 368. A number of insulated wires 330, 332, 334 are disposed on the outer surface of the elongated tube 304 extending along the grooves 360, 362, 364, 368. The electrode assembly 300 further includes a first conductive sheath 312 and a second conductive sheath 314, each sheath mounted circumferentially around the elongated tube 304.

[0068] As shown in FIG. 3A, each conductive sheath 312, 314 of the electrode assembly 300 overlaps and surrounds at least a portion of an insulated wire 330, 332, 334. Each of the insulated wires 330, 332, 334 includes a conductive portion 331, 333, 335a, 335b (e.g., a portion of the wire with insulation removed) positioned near an edge of the conductive sheath to form a spark gap across which current may flow and generate a shock wave. For example, the first insulated wire 330 may have a conductive portion 331 that extends along the elongated tube 304 and is proximate a first side edge of the first conductive sheath 312. The second insulated wire 332 may have a conductive portion 333 that extends along the elongated tube 304 and is proximate a first side edge of the second conductive sheath 314. The third insulated wire 334 extends along the elongate tube 304 between the first conductive sheath 312 and the second conductive sheath 314 and may include a first conductive portion 335a proximate the second side edge of the first conductive sheath 312 and a second conductive portion 335b proximate the second side edge of the second conductive sheath 314. In some examples, as shown in Figures 2A and 2B, the side edges of the conductive sheaths 312, 314 may include an arcuate or circular cutout in the conductive sheaths.

[0069] In the particular embodiment shown in Figures 3A and 3B, the electrode assembly 300 includes at least two emitters each having at least two electrode pairs formed from two conductive sheaths 312, 314 and three insulated wires 330, 332, 334. More specifically, the first electrode pair includes a conductive portion 331 of a first insulated wire 330 that extends along the outer surface of the elongated tube and a first conductive sheath 312 that is mounted circumferentially around the elongated tube. The second electrode pair includes the first conductive sheath 312 and a conductive portion 335a of a third insulated wire 334 that extends along the outer surface of the elongated tube. The third electrode pair includes the second conductive sheath 314 and a further conductive portion of a third insulated wire 335b. The fourth electrode pair includes a conductive portion 333 of a second insulated wire 332 that extends along the outer surface of the elongated tube and a second conductive sheath 314 that is mounted circumferentially around the elongated tube. The assembly of elements of the first and second electrode pairs (both formed from the sheath 312) may be referred to as a first emitter, while the assembly of elements of the third and fourth electrode pairs (both formed from the sheath 314) may be referred to as a second emitter.

[0070] FIG. 3B illustrates the flow of current through an exemplary electrode assembly. To initiate shock waves in the four electrode pairs of the electrode assembly, a high voltage pulse can be applied (e.g., using the high voltage pulse generator 150 of FIG. 1) across the first insulated wire 330 and the second insulated wire 332. When a high voltage pulse is applied across the first insulated wire 330 and the second insulated wire 332, current can flow as shown by the arrows, with the second insulated wire 332 as a common ground wire (i.e., connecting to the group or negative channel of the high voltage pulse generator). As shown, current flows from the proximal end of the first insulated wire 330 toward the distal end of the insulated wire 330. The current then flows across the gap between the conductive portion 331 of the first insulated wire 330 and the first conductive sheath 312, generating a shock wave (e.g., a first shock wave corresponding to the first electrode pair). The current then flows around the first conductive sheath 312 across the gap between the first conductive sheath 312 and the conductive portion 335a of the third insulated wire 334, generating an additional shock wave (e.g., a second shock wave corresponding to the second electrode pair). As shown, the current then flows from the proximal end of the third insulated wire 334 to the distal end of the third insulated wire 334. The current then flows across the gap between the additional conductive portion 335b of the third insulated wire 334 and the second conductive sheath 314, generating a shock wave (e.g., a third shock wave corresponding to the third electrode pair). The current then flows around the second conductive sheath 314 across the gap between the second conductive sheath 314 and the conductive portion 333 of the second insulated wire 332, generating additional shock waves (e.g., a fourth shock wave corresponding to the fourth electrode pair). The current then travels proximally back along the second insulated wire 332 (ground).

[0071] In one or more embodiments, longitudinally adjacent electrode pairs of a pair of emitters in an electrode assembly are separated by a distance (see, e.g., distance "d" in FIGS. 2A and 2B). As shown in FIG. 1" measures the distance between the first electrode pair and the fourth electrode pair (first pairing for constructive interference), while "d 2 " measures the distance between the second electrode pair and the third electrode pair (second pairing for constructive interference). As explained above, the distance between longitudinally adjacent emitters can represent the distance between two electrode pairs of adjacent sheaths. In one or more embodiments, the first emitter and the second emitter are circumferentially aligned (e.g., the gap between the electrode pair of the first emitter is at the same circumferential location on the catheter as the gap between the electrode pair of the second emitter) and separated by a distance of 1 mm to 4 mm or 3 mm to 3.5 mm, or in distance increments and gradients within these values.

[0072] Two electrode pairs formed from the same conductive sheath (e.g., a first electrode pair and a second electrode pair both formed from the first conductive sheath 312) may be longitudinally separated by a similar or shorter longitudinal distance. However, in one or more embodiments, two electrode pairs sharing a sheath may generate shock waves that do not interfere with (or minimally interfere with) each other, such as because the electrode pairs are circumferentially offset from each other by an angle of 180 degrees (e.g., on opposite sides of the catheter). Alternatively, the circumferential offset between two electrode pairs sharing a sheath may be selected to promote constructive interference, such as when the two electrode pairs are circumferentially offset from each other by an angle less than 180 degrees, as will be discussed below.

[0073] Furthermore, as explained above, the distance between the two electrode pairs (e.g., “d 1 " or "d 2" ) may specify the distance between the gap between the electrodes of a first electrode pair on a first emitter (e.g., the gap between the insulation removed portion 331 of the first insulated wire 330 and the first conductive sheath 312 of the first emitter) and the gap between the electrodes of a second electrode pair on a second emitter (e.g., the gap between the second conductive sheath 314 and the insulation removed portion 333 of the second insulated wire 332 of the second emitter). Alternatively, the distance between two electrode pairs may be approximated by the distance between the particular electrodes of each emitter. For example, the distance may be approximated by the distance between the insulation removed portions of the wires or conductive sheaths corresponding to the electrodes of each emitter.

[0074] Although Figures 3A-B illustrate one exemplary electrode assembly formed from first and second conductive sheaths 312, 314 and three insulated wires 330, 332, 334, a catheter of the present subject disclosure may include any number of emitters for generating shock waves inside a flexible polymer enclosure. For example, Figures 4A-D illustrate an exemplary electrode assembly 400 that may be included within a shockwave catheter, such as the exemplary catheter 100 shown in Figure 1, according to aspects of the present disclosure. The assembly includes three pairs of longitudinally adjacent emitters configured as separate proximal pair 410, central pair 420, and distal pair 430. Figure 4A illustrates a front side view of the electrode assembly 400. FIG. 4B illustrates a front side view of the wiring of the electrode assembly 400 of FIG. 4A (i.e., a view of the assembly with conductive sheaths 441, 442, 443, 444, 445, 446 removed to better depict insulated wires 451, 452, 453, 453, 455, 456, and 457). FIG. 4C illustrates a top side view of the electrode assembly 400 shown in FIG. 4A (i.e., a view of the assembly rotated 90 degrees to show additional features of the assembly 400). FIG. 4D illustrates a top side view of the wiring of the electrode assembly 400 (i.e., the assembly of FIG. 4C with conductive sheaths 441, 442, 443, 444, 445, 446 removed and / or a view of the wiring of FIG. 4B rotated 90 degrees).

[0075] 4A and 4C, the exemplary electrode assembly 400 includes a plurality of conductive metal sheaths, more specifically, a first conductive sheath 441, a second conductive sheath 442, a third conductive sheath 443, a fourth conductive sheath 444, a fifth conductive sheath 445, and a sixth conductive sheath 446. The exemplary electrode assembly 400 also includes a plurality of wires, more specifically, a first insulated wire 451, a second insulated wire 452, a third insulated wire 453, a fourth insulated wire 454, a fifth insulated wire 455, a sixth insulated wire 456, and a common ground wire 457, extending beneath and through the conductive sheaths. The conductive sheaths 441 , 442 , 443 , 444 , 445 , 446 and conductive portions of the insulated wires 451 , 452 , 453 , 454 , 455 , 456 form a plurality of emitters that can be activated to generate shock waves at various locations along the electrode assembly 400 .

[0076] As shown in Figures 4A and 4C, the conductive sheaths 441, 442, 443, 444, 445, 446 are arranged in closely spaced (e.g., longitudinally adjacent) pairs such that shock waves generated by emitter pairs formed from longitudinally adjacent sheaths can produce shock waves that constructively interfere (i.e., combined shock waves). More specifically, assembly 400 includes a proximal pair 410 including a first electrode pair 411 and a second electrode pair 412 formed from respective first and second conductive sheaths 441 and 442, a central pair 420 including a third electrode pair 413 and a fourth electrode pair 414 formed from respective third and fourth conductive sheaths 443 and 444, and a distal pair 430 including a fifth electrode pair 415 and a sixth electrode pair 416 formed from respective fifth and sixth conductive sheaths 445 and 446.

[0077] Although the front view of electrode assembly 400 in FIG. 4A shows each sheath (e.g., sheath 441 and sheath 442) with one electrode pair (e.g., electrode pair 411 and electrode pair 412), electrode assembly 400 can include additional electrode pairs on the sheaths that are circumferentially offset from one another. For example, FIG. 4C illustrates a top side view of example electrode assembly 400 in FIG. 4A revealing two additional electrode pairs on distal emitter pair 430, specifically, electrode pair 417 and electrode pair 418. In other words, electrode pairs 417 and 418 are circumferentially offset from electrode pairs 415 and 416 on sheaths 445 and 446, respectively. The proximal pair 410 and the central pair 420 may similarly include additional emitters (not shown) that are circumferentially offset around the first conductive sheath 441, the second conductive sheath 442, the third conductive sheath 443, and / or the fourth conductive sheath 444. For example, the proximal pair 410 may include an additional electrode pair (not shown) that is circumferentially offset about 180 degrees from the first electrode pair 411 and the second electrode pair 412 around the respective first conductive sheath 441 and second conductive sheath 442. The central pair may also include an additional electrode pair (not shown) that is circumferentially offset about 180 degrees from the third electrode pair 413 and the fourth electrode pair 414 around the respective third conductive sheath 443 and fourth conductive sheath 444. In one or more embodiments, the circumferential offset between electrode pairs on the same sheath may be less than 180 degrees, as will be discussed further below.

[0078] As discussed with respect to the electrode assembly 200 of Figures 2A and 2B, the electrode pairs included in each of the proximal pair 410, the central pair 420, and the distal pair 430 may be substantially circumferentially aligned to promote constructive interference between shock waves generated by longitudinally adjacent emitters of each pair. In one or more embodiments, as shown in Figures 4A and 4C, the emitters and individual electrode pairs of the proximal pair 410, the central pair 420, and the distal pair 430 may be positioned in different circumferential orientations to more evenly distribute the shock wave therapy around the circumference of the catheter. For example, as shown in Figure 4A, the proximal pair 410 is oriented such that the first electrode pair 411 and the second electrode pair 412 face in a generally upward direction. The emitters of the central pair 420 are offset circumferentially from the proximal pair 410 such that the third electrode pair 413 and the fourth electrode pair 414 generate a radially combined shock wave that is different from the combined shock wave generated in the proximal pair 410. The electrode pairs of the distal pair 430 are offset circumferentially from both the proximal pair 410 and the central pair 420 to generate a further radially different combined shock wave. The radial direction of the shock waves emitted from each pair of emitters can be selected such that the combination of shock waves generated from the emitter pairs generates shock waves evenly around the circumference of the catheter. In some embodiments, as shown in Figures 4A-D, a pair of constructively interfering emitters may be offset circumferentially from another pair of emitters around the circumference of the catheter by about 30 degrees, about 60 degrees, about 120 degrees, or about 180 degrees, or degree increments and gradients within these values. In other embodiments, pairs of constructively interfering emitters may be substantially circumferentially aligned (e.g., offset zero degrees circumferentially) to produce specific radially combined shock waves relative to the catheter.

[0079] 4B and 4D illustrate the wiring of the electrode assembly 400. High voltage pulses can be applied across the insulated wires 451, 452, 453, 454, 455, 456 of the assembly to allow a user to selectively generate shock waves across certain emitters of the assembly 400. For example, in the embodiment shown in FIGS. 4A-D, the proximal pair 410, the central pair 420, and the distal pair 430 are each separately wired to a voltage source (e.g., the high voltage pulse generator 150 of FIG. 1) to allow a user of the assembly 400 to selectively generate shock waves in either the proximal pair 410, the central pair 420, or the distal pair 430. A common ground wire 457 is provided to drain current from the electrode assembly 400.

[0080] 4A-D, the proximal pair 410 includes a first insulated wire 451 extending between a voltage source and the first conductive sheath 441, and further includes a second insulated wire 452 extending between the first conductive sheath 441 and the second conductive sheath 442. Current flows from the proximal pair 410 through a common ground wire 457 having a conductive portion near the second conductive sheath 442. A high voltage pulse voltage can be applied to the first insulated wire 451 to generate shock waves in the proximal pair 410 (i.e., in the first and second electrode pairs 411 and 412 and any additional electrode pairs formed from the first and second conductive sheaths 441, 442).

[0081] The central pair 420 includes a third insulated wire 453 extending between a voltage source and the third conductive sheath 443, and further includes a fourth insulated wire 454 extending between the third conductive sheath 443 and the fourth conductive sheath 444. Current flows from the central pair 420 through a common ground wire 457 having a conductive portion near the fourth conductive sheath 444. A high voltage pulse voltage can be applied to the third insulated wire 453 to generate shock waves in the central pair 420 (i.e., in the third and fourth electrode pairs 413 and 414 and any additional electrode pairs formed from the third and fourth conductive sheaths 443, 444).

[0082] The distal pair 430 includes a fifth insulated wire 455 extending between a voltage source and the fifth conductive sheath 445, and further includes a sixth insulated wire 456 extending between the fifth conductive sheath 445 and the sixth conductive sheath 446. Current flows from the distal pair 430 through a common ground wire 457 having a conductive portion near the sixth conductive sheath 446. A high voltage pulse voltage can be applied to the fifth insulated wire 455 to generate shock waves in the distal pair 430 (i.e., in the fifth and sixth electrode pairs 415 and 416 and any additional electrode pairs formed from the fifth and sixth conductive sheaths 445, 446).

[0083] Although the exemplary catheter 100 shown in FIG. 1 and the electrode assembly of FIGS. 4A-C include three pairs of emitters that can be activated to generate combined shock waves at three locations along the length of the catheter, any number of electrode assemblies and / or emitters can be included in the catheter without departing from the scope of the present disclosure, as described below. For example, some exemplary catheters include a single pair of longitudinally adjacent emitters configured to generate combined shock waves at a single location along the catheter. Further exemplary catheters include two pairs, three pairs, four pairs, or even more pairs, each pair may include one or more constructively interfering emitters that are spaced apart to generate combined shock waves along the length of the catheter. Alternatively or in addition, exemplary catheters may include groups of three or four emitters that are constructively interfering emitters that are spaced apart to generate combined shock waves along the length of the catheter. As an alternative to, or in addition to, longitudinally adjacent emitters configured to generate shock waves that constructively interfere to form a combined shock wave, catheters with circumferentially adjacent electrode pairs (e.g., electrode pairs that are circumferentially offset from one another by an angle less than 180 degrees) configured to generate shock waves that constructively interfere to form a combined shock wave are also contemplated by the present disclosure, as will be discussed below.

[0084] FIG. 5 provides two images of an exemplary shockwave catheter incorporating aspects of the present disclosure. The top image shows an exemplary "M5" catheter having five emitters spaced approximately ten millimeters (10 mm) apart. The bottom image shows an exemplary "Lx" catheter having six adjacent emitters arranged in pairs, with each emitter in a pair spaced approximately 3.5 mm apart from the other emitter of the pair. As shown in FIG. 5, the emitters of the M5 catheter are evenly spaced at a distance of 10 mm along the length of the catheter. The emitters of the Lx catheter are arranged in longitudinally adjacent pairs, more specifically, in proximal, central, and distal pairs. The longitudinally adjacent emitters of each respective proximal, central, and distal pair are spaced approximately 3.5 mm apart to promote constructive interference between shockwaves generated at longitudinally adjacent emitters of the pair. As shown in FIG. 5, the distance between the proximal pair and the central pair and the distance between the central pair and the distal pair are greater than 3.5 mm.

[0085] Figure 6 provides a series of heat map graphics depicting the acoustic pressure wavefronts of shock waves generated by various exemplary catheters, such as those generated by an exemplary catheter as shown in Figure 5. The x-axis of each graph (at the top of each image) corresponds to the lateral location along the catheter of the pressure reading, with "0" representing the central location along the catheter's electrode array (e.g., the location of the catheter's central emitter). Shock waves generated by the catheter at each distinct lateral location are depicted by areas of increased pressure, represented by lighter shaded areas according to the pressure scale below each graphic.

[0086] The spacing of the emitters along the catheter is shown with a schematic diagram superimposed over each heat map. The top row of graphics provides pressure readings from a commercially available M5 catheter from Shockwave Medical, Inc. The M5 catheter includes an array of emitters, with adjacent emitters spaced approximately 10 mm apart along the length of the catheter that are not uniformly circumferentially aligned with respect to one another. More specifically, looking from left to right, the first two emitters are aligned with one another, then there is a rotational offset, then the next two emitters are aligned with one another, then there is a further rotational offset, and the final emitter is not aligned with any of the other emitters. The bottom row of graphs provides pressure readings from an exemplary Lx catheter (a "3.5 mm spacing" catheter) implementing aspects of the present disclosure. The Lx catheter includes a proximal pair of two longitudinally adjacent emitters, a central pair of two longitudinally adjacent emitters, and a distal pair of two longitudinally adjacent emitters. Within each of the proximal, central, and distal pairs, adjacent emitters are spaced apart at a distance of about 3.5 mm, where adjacent emitter pairs are circumferentially aligned with respect to each other. For the paired emitters, looking from left to right relative to each other, the first two (proximal) emitters are aligned with each other, then there is a rotational offset, then the next two (central) emitters are aligned with each other, then there is a further rotational offset, then the last two emitters (distal) are aligned with each other.

[0087] As shown in FIG. 6, when the emitters of the 3.5 mm spaced Lx catheter are activated, the acoustic pressure wavefronts (i.e., shock waves) generated at the longitudinally adjacent emitters converge, producing a double or multiple wavefront and a region of highly focused high amplitude pressure waves (i.e., combined shock waves), as depicted by the double bulge of thinner shaded areas overlapping each other at the lateral locations corresponding to each longitudinally adjacent pair of emitters. In contrast, the acoustic pressure wavefronts generated by the M5 catheter do not converge, or only minimally converge, as depicted by the thinner shaded areas mostly adjacent each other with minimal overlap at the lateral locations corresponding to each emitter, resulting in a relatively more diffuse lower pressure wavefront. As a result, the 3.5 mm spaced Lx catheter can generate an acoustic wavefront with increased pressure compared to the pressure of the acoustic wavefront generated by the M5 catheter.

[0088] FIG. 7 provides two graphs displaying pressure readings of shock waves produced by exemplary catheters according to aspects of the present disclosure. The x-axis corresponds to the lateral distance of the pressure readings along the edge of the angioplasty balloon (i.e., along the surface of the catheter's flexible polymer encapsulation), with "0" representing the center position on the balloon. The graph on the left shows peak-to-peak pressure readings along the length of an M5 catheter (e.g., the M5 catheter described above in connection with FIGS. 5 and 6) having emitters spaced about 10 mm apart. The graph on the right shows peak-to-peak pressure readings along the length of a catheter (e.g., the Lx catheter described above in connection with FIGS. 5 and 6) having a pair of longitudinally adjacent emitters spaced at about 3.5 mm apart. FIG. 7 provides the average pressure of the three data sets, while FIG. 6 shows exemplary pressure readings from a single representative data sample. As shown in FIG. 7, the 3.5 mm-spaced Lx catheter produces acoustic shock waves with increased peak pressures compared to shock waves produced by the M5 catheter.

[0089] FIG. 8 provides a series of images of bubble progression in pairs of emitters of four exemplary catheters in response to a high voltage pulse applied across the emitters in accordance with aspects of the present disclosure. The top row of images shows bubble formation, expansion, and collapse with an M5 catheter having pairs of emitters spaced at a distance of 10 mm. The second, third, and fourth rows of images show bubble formation, expansion, and collapse with an exemplary Lx catheter implementing aspects of the present subject disclosure having longitudinally adjacent emitters spaced at distances of 2.5 mm, 3.5 mm, and 4.5 mm, respectively. As shown in FIG. 8, the M5 catheter produces bubbles that expand and collapse independently, producing two smaller acoustic shock waves in the conductive fluid. As the spacing between the emitters decreases in the exemplary Lx catheter, the bubbles begin to converge and overlap, producing a single combined acoustic shock wave. For example, bubbles generated by a 10 mm spacing M5 catheter do not interfere, bubbles generated by a 4.5 mm spacing Lx catheter do not interfere or only minimally interfere, and bubbles generated by 3.5 mm and 2.5 mm spacing Lx catheters interfere (i.e., expand and collapse together) creating combined shock waves.

[0090] As an alternative or in addition to having longitudinally spaced electrode pairs (e.g., located on separate sheaths of emitter pairs) as discussed above, a catheter can include multiple electrode pairs on the same sheath that are circumferentially offset from one another. Figure 9 illustrates an example catheter electrode assembly 900 having a pair of electrodes 922, 924 at the same longitudinal location on the catheter but circumferentially offset from one another by 60 degrees.

[0091] As shown, the electrode pairs 922, 924 of the electrode assembly 900 can be formed from a conductive sheath 912 and several wires 930, 932. In one or more embodiments, the electrode pairs 922, 924 can be formed from circular cutouts (as shown in FIG. 9 and as in the electrode assembly 200 of FIG. 2A) and / or arcuate cutouts (as shown in FIG. 2B) in the sheath 912. When a voltage is applied to the electrode assembly 900, current flows between the cutouts in the conductive sheath (first electrode) and the conductive portion of the insulated wire (second electrode) (e.g., the insulation removed portion of the wire), generating a shock wave. In one or more embodiments, an insulating sheath 911 can be positioned between the conductive portion of the wire and the cutout to prevent unintended current flow between the conductive portion of the wire and the conductive sheath and provide a path through which current may flow between the electrodes of each electrode pair.

[0092] As shown in FIG. 9, a first electrode pair 922 is circumferentially offset from a second electrode pair 924 at an angle "α". The electrode pairs 922 and 924 are arranged in closely spaced (e.g., circumferentially adjacent) pairs such that shock waves generated by each electrode pair may constructively interfere with one another to produce a combined shock wave. The specific degree of the circumferential offset α between the emitters can be varied. For example, rather than being offset by 60 degrees, the electrode pairs 922 and 924 can be circumferentially offset from one another by 30 degrees, 90 degrees, 120 degrees, 140 degrees, 160 degrees, or degree increments and gradients within these values.

[0093] FIG. 10 provides an image of an exemplary shockwave catheter with a catheter electrode assembly having electrode pairs 1002 and 1004 at the same longitudinal location on the catheter but circumferentially offset from each other by approximately 60 degrees.

[0094] 11 provides a series of images of bubble formation and collapse resulting from activation of an exemplary shockwave catheter with an electrode assembly having pairs of electrodes (referred to as "emitter holes" in the figure) at the same longitudinal location but circumferentially offset from one another by 180 degrees, 120 degrees, 90 degrees, 60 degrees, and 0 degrees. More specifically, image 1180 corresponds to a 180 degree offset, image 1120 corresponds to a 120 degree offset, image 1190 corresponds to a 90 degree offset, image 1160 corresponds to a 60 degree offset, and image 1101 corresponds to a 0 degree offset (i.e., 0 degree is an emitter with only one electrode pair and is provided as a control example).

[0095] As shown in image 1180, the bubbles 1102 generated by each electrode pair when offset 180 degrees from each other do not interfere with each other. Thus, there is little or no constructive interference between shock waves generated by electrode pairs offset 180 degrees from each other. In comparison, as shown in images 1120, 1190, and 1160, the bubbles generated by each electrode pair when offset 120 degrees, 90 degrees, and 60 degrees from each other begin to coalesce together into one combined bubble. Thus, there is constructive interference between bubbles generated by emitters when offset at any of these degrees (e.g., 120 degrees, 90 degrees, 60 degrees) that tends to produce combined bubbles.

[0096] 12 provides a graph illustrating the pressure of an acoustic wavefront from a single emitter measured along the balloon edge of an exemplary catheter with an electrode assembly having two electrode pairs 1201, 1202 at the same longitudinal location but circumferentially spaced 180 degrees, 120 degrees, 90 degrees, 60 degrees, and 0 degrees from each other in accordance with an aspect of the present disclosure. The pressure values ​​shown in the graph of FIG. 12 are tabulated in Table 1 below. [Table 1]

[0097] As shown in the image of FIG. 11, when arranging pairs of electrode pairs at the same longitudinal location but offset circumferentially from each other by less than 180 degrees, the shock waves generated by the emitters tend to constructively interfere with each other and generate combined bubbles. Also, as shown in the graph of FIG. 12 and Table 1, arranging pairs of electrode pairs at the same longitudinal location but offset circumferentially from each other by less than 180 degrees also tends to result in larger pressure values ​​when measured between the electrode pairs (such as where combined bubbles may form). Thus, an electrode assembly with electrode pairs located at the same longitudinal location and offset by less than 180 degrees, such as the electrode assembly of FIG. 9, can achieve pressure values ​​that exceed those of electrode assemblies with electrode pairs offset from each other by 180 degrees.

[0098] In addition to placing two electrode pairs at the same longitudinal location, such as on the same sheath, a catheter can include multiple pairs of electrode pairs located adjacent to one another, e.g., multiple sheaths spaced apart along the length of the catheter. Figures 13A-B illustrate an exemplary electrode assembly 1300 having multiple pairs of longitudinally aligned emitters spaced apart along the length of the catheter, in accordance with aspects of the present disclosure. Figure 13A illustrates a right front view and Figure 13B illustrates a left front view of the exemplary electrode assembly. With respect to the exemplary electrode assembly 400 of Figures 4A-C, the electrode assembly 1300 differs in that here the longitudinally aligned electrode pairs (e.g., located on the same sheath) are circumferentially offset by less than 180 degrees relative to one another.

[0099] The sheath and electrode pairs of the electrode assembly 1300 are connected by several wires, which can be arranged similarly to the wiring described with reference to Figures 3A-B and 4A-C. The emitters of the electrode assembly 1300 can be formed from a conductive sheath with a circular cutout (like the electrode assembly 200 shown in Figure 2A) and / or an arcuate cutout (like the electrode assembly 200 shown in Figure 2B). When a voltage is applied to the electrode assembly, current flows between the cutout of the conductive sheath (first electrode) and the conductive portion of the insulated wire (second electrode) (e.g., the insulation removed portion of the wire), generating a shock wave. An insulating sheath can be positioned between the conductive portion of the wire and the cutout to prevent unintended current flow between the conductive portion of the wire and the conductive sheath, and to provide a path through which current can flow between the electrodes of each emitter.

[0100] As shown in FIG. 13A, electrode assembly 1300 includes a first pair 1310 (emitter) of longitudinally adjacent sheaths 1341 and 1342, each containing a pair of longitudinally aligned but circumferentially offset electrode pairs 1311, 1312, and a second pair 1320 (emitter) of longitudinally adjacent sheaths 1343 and 1344, each containing a pair of longitudinally aligned but circumferentially offset electrode pairs 1313 and 1314, respectively.

[0101] Conductive sheaths 1341, 1342, 1343, and 1344 are arranged in closely spaced (e.g., longitudinally adjacent) emitter pairs 1310 and 1320 such that shock waves generated by electrode pairs in each sheath can constructively interfere with shock waves generated by longitudinally adjacent sheaths. For example, shock waves generated by electrode pair 1311 in sheath 1341 can constructively interfere with shock waves generated by electrode pair 1312 in sheath 1342. As discussed above with respect to FIG. 9, longitudinally aligned and circumferentially offset electrode pairs, such as those in the same sheath, can also constructively interfere with each other. Thus, in one or more embodiments, shock waves generated by separate electrode pair 1311 of sheath 1341 will constructively interfere with each other to generate a first combined shock wave bubble, and shock waves generated by separate electrode pair 1312 of sheath 1342 will constructively interfere with each other to generate a second combined shock wave bubble, and then those first and second combined shock wave bubbles will constructively interfere with each other based on their adjacent longitudinal spacing to form one combined shock wave from emitter pair 1310.

[0102] For the first emitter pair 1310, the sheath 1341 is spaced apart by a distance d 1 13, the electrode pair 1311 of the sheath 1341 is circumferentially aligned with the electrode pair 1312 of the sheath 1342. Similarly, for the second emitter pair 1320, the sheath 1343 is longitudinally separated from the sheath 1342 by a distance d 2 13A, the electrode assembly 1300 is longitudinally separated from the sheath 1344, and the electrode pairs 1313 of the sheath 1343 are circumferentially aligned with the electrode pairs 1314 of the sheath 1344. As used to describe the electrode assembly 1300 of FIG. 1 and d 2specifies the distance between the longitudinally adjacent sheaths of the pair. These distances can also describe the distance between the emitters of those sheaths, e.g., the distance between electrode pair 1311 and electrode pair 1312 and / or the distance between the spark gap of electrode pair 1311 and the spark gap of electrode pair 1312 (e.g., the gap across which current jumps when a voltage is applied to the electrodes of each emitter, generating a shock wave). The distance d separating sheaths 1341 and 1342 1 is the distance d separating the sheaths 1343 and 1344 2 In one or more embodiments, the distance between the pair of sheaths can be between 1 mm and 4 mm, or distance increments and gradients within these values. In one or more embodiments, the distance between the pair of sheaths is 3.5 mm.

[0103] As shown in FIG. 13A, the emitters of a first pair 1310 are not circumferentially aligned with the emitters of a second pair 1320 (e.g., electrode pair 1311 and 1312 are located at a different circumferential location on the catheter from electrode pair 1313 and 1314). The radial direction of the shock waves emitted from each emitter pair (e.g., 1310 and 1320) can be selected such that the combination of shock waves generated from the emitters of the pair generates shock waves evenly around the circumference of the catheter. In some embodiments, as shown in FIG. 13A-B, emitter pair 1310, which includes constructively interfering electrode pair 1311 and 1312, is circumferentially offset from emitter pair 1320. In one or more embodiments, the offset between emitter pairs 1310 and 1320 can be about 30 degrees, about 60 degrees, about 120 degrees, or about 180 degrees around the circumference of the catheter, or degree increments and gradients within these values. In one or more embodiments, each pair of emitters with their respective electrodes (e.g., electrode pairs 1311, 1312, 1313, and 1314) can be circumferentially aligned with one another. That is, emitter pairs 1310 and 1320 may be substantially circumferentially aligned (e.g., offset circumferentially by zero degrees) to produce a particular radially combined shock wave relative to the catheter.

[0104] 14 provides an image of an exemplary shockwave catheter having two emitters 1402 and 1406 with longitudinally aligned electrode pairs 1404 and 1408, respectively, spaced along the length of the catheter. The longitudinally aligned electrode pairs 1404 and 1408 are circumferentially offset from one another but located at the same longitudinal location. In the example shown in FIG. 14, the electrode pair 1404 of the first emitter 1402 is circumferentially aligned with the electrode pair 1408 of the second emitter 1406.

[0105] FIG. 15 provides a series of images of bubble formation and collapse resulting from activation of an exemplary shockwave catheter with an electrode assembly having multiple pairs of emitters with electrode pairs (referred to as "emitter holes" in the images) that are longitudinally aligned but circumferentially offset from one another at 180 degrees, 120 degrees, 90 degrees, 60 degrees, and 0 degrees (i.e., 0 degrees is an emitter with only one electrode pair), where the electrode pairs of the emitter pairs are circumferentially aligned with one another (e.g., an electrode pair of a first sheath with a first pair of longitudinally aligned but circumferentially offset electrode pairs is circumferentially aligned with an electrode pair of a second sheath with a second pair of longitudinally aligned but circumferentially offset electrode pairs) and are located in close proximity to one another (e.g., separated by a distance of 1 mm to 4 mm). More specifically, image 1580 corresponds to a 180 degree offset, image 1520 corresponds to a 120 degree offset, image 1590 corresponds to a 90 degree offset, image 1560 corresponds to a 60 degree offset, and image 1501 corresponds to a 0 degree offset.

[0106] As shown in image 1580, the bubbles 1502 generated by each electrode pair when offset 180 degrees from each other do not interfere with each other. Thus, there is little or no constructive interference between shock waves generated by emitters offset 180 degrees from each other. In comparison, as shown in images 1520, 1590, and 1560, the bubbles generated by each emitter when offset 120 degrees, 90 degrees, and 60 degrees from each other, respectively, begin to coalesce together into one combined bubble. Thus, there is constructive interference between bubbles generated by emitters when offset at any of these degrees (e.g., 120 degrees, 90 degrees, 60 degrees) that tends to produce a combined bubble.

[0107] 16 provides a graph illustrating the pressure of an acoustic wavefront from pairs of emitters measured along the balloon edge of an exemplary catheter with an electrode assembly having multiple electrode pairs that are longitudinally aligned but circumferentially offset from one another by 180 degrees, 120 degrees, 90 degrees, 60 degrees, and 0 degrees, where the electrode pairs of each emitter pair are circumferentially aligned with one another. The pressure values ​​shown in the graph of FIG. 16 are tabulated in Table 2 below. [Table 2-1] [Table 2-2]

[0108] As shown in the image of FIG. 15, when arranging pairs of emitters at the same longitudinal location but offset circumferentially from each other by less than 180 degrees, the shock waves generated by the emitters tend to constructively interfere with each other and generate combined bubbles. Furthermore, as shown in the graph of FIG. 16 and Table 2, arranging pairs of longitudinally aligned and circumferentially offset electrodes so that they are closely longitudinally adjacent to another pair of longitudinally aligned and circumferentially offset electrode pairs (the circumferential offset is less than 180 degrees) tends to result in larger pressure values. For example, considering the central location between all electrode pairs (e.g., electrode pairs 1601, 1602, 1603, and 1604), when the electrode pairs are offset by 180 degrees, the peak pressure is about 7 MPa, which is less than the peak pressure when the electrode pairs are offset by 120 degrees (about 7.7 MPa), 90 degrees (about 7.9 MPa), and 60 degrees (about 7.9 MPa). Also, at all measurement locations, the pressure values ​​measured when the electrode pairs are offset by 120 degrees, 90 degrees, and 60 degrees exceed the pressure values ​​measured when the electrode pairs are offset by 180 degrees. Thus, electrode assemblies with pairs of emitters located at the same longitudinal location, such as the electrode assemblies of Figures 13A-B, each having an electrode pair offset by less than 180 degrees, can achieve pressure values ​​that exceed electrode assemblies with electrode pairs offset from each other by 180 degrees.

[0109] 17 illustrates an exemplary catheter electrode assembly 1700 having a single emitter with a single electrode pair 1722. The electrode assembly 1700 is similar to the electrode assembly 900 of FIG. 9, except that here a second electrode pair would be to be plugged in via a plug 1724, meaning that the electrode assembly 1700 includes a single bore electrode pair 1722 (e.g., a single cutout in a sheath 1712). The electrode pair 1722 is formed from a conductive sheath 1712 and several wires 1730, 1732. As shown, the sheath 1712 includes a circular cutout, however, the electrode assembly 1700 could alternatively include an arcuate cutout. When a voltage is applied to the electrode assembly 1700, current flows between the cutout (first electrode) in the conductive sheath 1712 and the conductive portion of the insulated wire (second electrode) (e.g., the insulation removed portion of the wire 1730), generating a shock wave. In one or more embodiments, the first insulated wire 1730 is located proximate to the cutout in the sheath 1712, forming an electrode pair 1722, and the second insulated wire 1732 is connected directly to the sheath 1712 (or alternatively, connected via a plug 1724 when formed of a conductive material). When a high voltage pulse is applied across the first insulated wire 1730 and the second insulated wire 1732, current may flow as shown by the arrows, using the second insulated wire 1732 as a common ground wire (i.e., connecting to the group or negative channel of the high voltage pulse generator). In one or more embodiments, an insulating sheath 1711 can be positioned between the conductive portion of the wire and the cutout in the sheath 1712 to prevent unintended current flow between the conductive portion of the wire and the conductive sheath and to provide a path through which current can flow between the electrodes of the electrode pair 1722. In one or more embodiments, the electrode assembly 1700 can be considered to include a pair of electrode pairs that are circumferentially offset by 0 degrees.

[0110] 18 illustrates a right front view of an exemplary electrode assembly 1800 having a pair of emitter electrode assemblies, each with a single electrode pair, spaced apart along the length of the catheter. The electrode assembly 1800 includes a pair 1810 of closely spaced (e.g., longitudinally adjacent) sheaths 1841, 1842, each including a single electrode pair 1811 and 1812. The sheaths 1841 and 1842 of the electrode assembly 1800 are connected by several wires. As shown, each conductive sheath 1841, 1842 of the electrode assembly 1800 is located in close proximity to at least a portion of an insulated wire 1830, 1832, 1834. Each of the insulated wires 1830, 1832, 1834 includes a conductive portion (not shown in the figure) that is positioned near the cutout electrode pair 1811, 1812 on the conductive sheath. For example, a first insulated wire 1830 may extend along the catheter tube (not shown) and have a conductive portion proximate a circular cutout (e.g., hole) in a sheath 1841 to form a first electrode pair 1811. A second insulated wire 1832 may extend to a sheath 1842 and have a conductive portion proximate a circular cutout in the sheath 1842 to form a second electrode pair 1812. When a high voltage pulse is applied across the first insulated wire 1830 and the second insulated wire 1832, current may flow as shown by the arrows, with the second insulated wire 1832 as a common ground wire (i.e., connecting to the group or negative channel of the high voltage pulse generator).

[0111] As shown in FIG. 18, electrode pair 1811 of sheath 1841 is circumferentially aligned with electrode pair 1812 of sheath 1842 and separated from electrode pair 1812 by a distance d. Thus, electrode pairs 1811 and 1812 are longitudinally adjacent and circumferentially aligned. As used to describe electrode assembly 1800 of FIG. 18, d designates the distance between longitudinally adjacent sheaths of emitter pairs. Distance d can also describe the distance between electrode pairs of those sheaths, for example, the distance between electrode pair 1811 and electrode pair 1812 and / or the distance between the spark gap of electrode pair 1811 and the spark gap of electrode pair 1812 (e.g., the gap across which current jumps and generates a shock wave when a voltage is applied to the electrodes of each electrode pair). In one or more embodiments, the distance between the sheaths of emitter pairs can be from 1 mm to 4 mm, or distance increments and gradients within these values. In one or more embodiments, the distance d between sheaths 1841 and 1842 is 3.5 mm.

[0112] Shock waves emitted from the closely spaced (e.g., longitudinally adjacent), circumferentially aligned electrode pairs 1811 and 1812 of Figure 18 can generate shock waves in a manner similar to the closely spaced, circumferentially aligned electrode pairs of electrode assembly 400 of Figures 4A-C. Thus, in one or more embodiments, a sufficiently close distance d between electrode pairs 1811 and 1812 can cause the shock waves generated at each electrode pair to constructively interfere with each other to form a single combined shock wave.

[0113] It should be noted that the elements and features of the exemplary catheters illustrated in Figures 1, 2A-B, 3A-B, 4A-D, 5-12, 13A-B, and 14-18 may be rearranged, recombined, and modified without departing from the present invention. For example, while Figures 2A-B, 3A-B, 4A-D, 9, 13A-B, 17, and 18 illustrate several exemplary electrode assemblies, the present disclosure is intended to include catheters having a variety of electrode configurations, and the number, placement, and spacing of emitters and electrode pairs may be modified without departing from the subject invention.

[0114] Additionally, while the emitters disclosed in the examples herein typically have a structure having two electrode pairs on each emitter, it is envisioned to also include emitters having three electrode pairs (e.g., separated circumferentially by 120 degrees from each other), four electrode pairs (e.g., separated circumferentially by 90 degrees from each other), five electrode pairs (e.g., separated circumferentially by 72 degrees from each other), six electrode pairs (e.g., separated circumferentially by 60 degrees from each other), etc. Although there may be physical limitations to the construction of such emitter assemblies related to wiring size and arrangement, ability to deliver sufficient power, electrode erosion profile, etc., it is within the scope of this disclosure that such emitters may be successfully developed with improved manufacturing capabilities.

[0115] Additionally, numerical designators such as "first," "second," "third," "fourth," etc. are merely descriptive and do not indicate a relative order, location, or identity of the elements or features described by the designators. For example, a "first" shock wave may immediately precede a "third" shock wave, which in turn is prior to a "second" shock wave. As another example, a "third" emitter may be used to generate a "first" shock wave, and vice versa. Thus, the numerical designators of the various elements and features are not intended to limit the present disclosure and may be modified and substituted without departing from the subject invention.

[0116] It should be understood that the foregoing is merely illustrative of the principles of the present invention, and that various modifications, alterations, and combinations may be made by those skilled in the art without departing from the scope and spirit of the present invention. Any of the various catheter variations disclosed herein may include features described with any other catheter or combination of catheters herein. Furthermore, any of the present methods may be used in conjunction with any of the catheters disclosed. Thus, the present invention is not intended to be limited, except as by the appended claims.

Claims

1. A catheter for treating an obstruction in a body cavity, the catheter comprising: An extension tube; a flexible enclosure circumferentially disposed about at least a portion of the elongated tube, the flexible enclosure being capable of being filled with an electrically conductive fluid; a first electrode pair disposed inside the flexible enclosure, the first electrode pair configured to generate shock waves, the first electrode pair having a first electrode and a second electrode separated by a gap; a second electrode pair disposed inside the flexible enclosure, the second electrode pair configured to generate shock waves, the second electrode pair having a first electrode and a second electrode separated by a gap; Equipped with A catheter, wherein the gap of the second electrode pair is located at essentially the same longitudinal location on the elongated tube as the gap of the first electrode pair and is circumferentially offset from the gap of the first electrode pair by an angle of less than 180 degrees, which promotes constructive interference between shock waves generated at the first electrode pair and the second electrode pair when a voltage is applied across the first electrode pair and the second electrode pair.

2. A catheter as described in claim 1, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other at an angle of 40 degrees to 140 degrees.

3. A catheter as described in claim 1, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other at an angle of 65 degrees to 125 degrees.

4. A catheter as described in claim 1, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other at an angle of 80 degrees to 100 degrees.

5. A catheter as described in claim 1, wherein a circumferential offset between the gap of the first electrode pair and the gap of the second electrode pair is selected such that the peak pressure of the combined shock wave is greater than the peak pressure of a shock wave generated by a catheter having a first electrode pair and a second electrode pair having gaps that are circumferentially offset at an angle of 180 degrees relative to each other.

6. The first electrode pair, a first electrically conductive sheath circumferentially mounted about the elongated tube; a first insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; Equipped with The second electrode pair is the first electrically conductive sheath; a second insulated wire having an insulation removed portion extending along the outer surface of the elongated tube; Equipped with 2. The catheter of claim 1, wherein when a voltage is applied across the first and second insulated wires, a current flows across a gap between an insulation removed portion of the first insulated wire and the first electrically conductive sheath to generate a first shock wave and a current flows across a gap between the first electrically conductive sheath and an insulation removed portion of the second insulated wire to generate a second shock wave.

7. A catheter as described in claim 6, wherein the first electrically conductive sheath has an arcuate cutout formed on a side edge of the first electrically conductive sheath, and current flows between the arcuate cutout and an insulation removed portion of the first insulated wire.

8. A catheter as described in claim 6, wherein the first electrically conductive sheath has a circular cutout disposed between opposing side edges of the first electrically conductive sheath, and current flows between the circular cutout and an insulation removed portion of the first insulated wire.

9. A catheter as described in claim 6, wherein the outer surface of the elongated tube has a groove, and the first insulated wire and the second insulated wire extend along the groove of the elongated tube.

10. The catheter, a third electrode pair disposed inside the flexible enclosure, the third electrode pair configured to generate shock waves, the third electrode pair having a first electrode and a second electrode separated by a gap; a fourth electrode pair disposed inside the flexible enclosure, the fourth electrode pair configured to generate shock waves, the fourth electrode pair having a first electrode and a second electrode separated by a gap; Further equipped with a gap of the fourth electrode pair is disposed at essentially the same longitudinal location on the extension tube as a gap of the third electrode pair and is circumferentially offset from the gap of the third electrode pair by an angle of less than 180 degrees, which promotes constructive interference between shock waves generated at the third electrode pair and the fourth electrode pair when a voltage is applied across the third electrode pair and the fourth electrode pair; 2. The catheter of claim 1, wherein the third and fourth electrode pairs are separated from the first and second electrode pairs by a longitudinal distance along the elongated tube of between 1 mm and 4 mm, which allows combined shock waves to be created from shock waves generated at each of the first and second and third and fourth electrode pairs when a voltage is delivered across each of the first and second and third and fourth electrode pairs.

11. The third electrode pair: a second electrically conductive sheath; and a third insulated wire having an insulation removed portion extending along an outer surface of the elongated tube; Equipped with The fourth electrode pair is the second electrically conductive sheath; and a further insulation removed portion of the third insulated wire; and Equipped with 11. The catheter of claim 10, wherein when a voltage is applied across the first and second insulated wires, a current flows across a gap between the second electrically conductive sheath and a removed insulation portion of the third insulated wire to generate a third shock wave, and a current flows across the gap between the second electrically conductive sheath and a further removed insulation portion of the third insulated wire to generate a fourth shock wave.

12. A catheter as described in claim 10, wherein the gap of the first electrode pair and the gap of the second electrode pair are circumferentially offset from each other at the same angle as the offset between the gap of the third electrode pair and the gap of the fourth electrode pair.

13. A catheter as described in claim 10, wherein a circumferential offset between the gap of the first electrode pair and the gap of the second electrode pair is circumferentially aligned with the offset between the gap of the third electrode pair and the gap of the fourth electrode pair relative to the extension tube.

14. A catheter as described in claim 10, wherein a circumferential offset between the gaps of the first and second electrode pairs is circumferentially offset by approximately 180 degrees relative to the elongated tube from a circumferential offset between the gaps of the third and fourth electrode pairs.

15. The catheter of claim 1, wherein the extension tube has a guidewire lumen for receiving a guidewire, and the catheter is configured to be advanced over the guidewire into the body cavity.

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