Lesion-crossing shockwave catheter

Abstract

The present invention provides a catheter for treating occlusions in blood vessels. The catheter includes at least one electrode pair positioned inside a flexible angioplasty balloon at the distal end of the catheter. In some designs, the electrode pair is arranged in a low-profile or flush configuration, reducing the diameter of the distal end of the device and enabling treatment of tight, difficult-to-cross occlusions. The flexible angioplasty balloon has an extremely low profile and does not need to be folded before insertion of the catheter into the cardiovascular system. During treatment, the balloon can be expanded only a relatively small amount, enough to immerse the electrode pair in a conductive fluid before generating shock waves across the electrodes to treat the occlusion. The balloon can be made of a material with elastomeric properties so that it returns to its original low-profile configuration when deflated following treatment.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Provisional Patent Application No. 62 / 904,847, filed Sep. 24, 2019, and entitled “LESION CROSSING CATHETER WITH LOW PROFILE SHOCK WAVE GENERATOR,” the contents of which are incorporated herein by reference in their entirety. FIELD OF THE DISCLOSURE

[0002] The present disclosure relates generally to a catheter device that can be used to cross calcified lesions. The catheter includes a distal shockwave generator that is constructed with a very low profile to enable advancement through narrow vasculature. [Background technology]

[0003] A wide variety of catheters have been developed to treat arterial disease. For example, treatment systems for percutaneous coronary intervention or peripheral angioplasty use angioplasty balloons to open lesions (e.g., calcified lesions) and restore normal blood flow within the artery. 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, reducing or destroying the calcified plaques and forcing them back into the vessel wall. The balloon can have a smooth wall or be equipped with structures that physically scrape the lesions within the vessel. Other catheters, known as atherectomy devices, have rotating members to pierce and remove the lesions.

[0004] More recently, catheters have been developed that include one or more electrode pairs positioned inside an angioplasty balloon. In these devices, the catheter is advanced over a guidewire within the patient's vasculature until it is proximal to the lesion. The balloon is inflated with a conductive fluid to contact the lesion, and then a shockwave generator is fired to generate shockwaves that direct acoustic waves into the lesion. Shockwave devices are particularly effective for treating calcified lesions because the acoustic waves can break up the lesion without harming the surrounding vessels. Once the lesion is broken up, the balloon can be further expanded within the vessel to create an improved blood flow lumen.

[0005] Shockwave generators are typically electrode pairs that are excited by the application of high voltage pulses. Attempts have been made to reduce the size of the electrode pairs and allow access to tighter, harder to traverse calcified lesions. Examples of such low-profile designs can be found in U.S. Patent Nos. 8,747,416 and 10,555,744 and U.S. Publication No. 2019 / 0150960, all of which are incorporated herein by reference.

[0006] Although the low-profile designs discussed above have been deployed in both coronary and peripheral vascular applications, even those designs have difficulty crossing partial or total occlusions in vessels. One approach to address that problem is to use a guidewire with a shockwave generator at the distal tip. In that case, the proximal and distal shaft portions of the catheter are reinforced to aid in the advancement of the guidewire into the occlusion. One or more shockwaves are generated to partially open the blockage. The guidewire can then be advanced further into the occlusion where additional shockwaves are generated. This sequence can be continued to move the guidewire through the occlusion and provide a large enough channel where a balloon catheter can be inserted. An example of such a shockwave guidewire design can be found in U.S. Pat. No. 9,730,715 (incorporated herein by reference).

[0007] Although placing the shockwave electrode on the tip of the guidewire can lead to an extremely low-profile structure, such an approach has some disadvantages compared to low-profile designs that include inflatable balloons. For example, the guidewire necessarily has a soft tip, which cannot be easily pushed through obstructions. In addition, the guidewire design is monopolar, with one electrode at the tip of the guidewire and a second electrode defined by a pad that is affixed to the patient's body. This means that the patient is part of the electrical circuit. In addition, the guidewire design does not have a balloon at the tip. A balloon is advantageous in that it may protect tissue from direct contact with the plasma generated during shockwave creation. The balloon also ensures that a conductive fluid surrounds the electrode during shockwave generation.

[0008] Therefore, a need exists to provide a catheter design that incorporates an angioplasty balloon and has a lower profile than previous approaches that include bipolar electrical circuitry for generating shock waves inside the balloon. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] U.S. Pat. No. 8,747,416 [Patent Document 2] U.S. Patent No. 9,730,715 Summary of the Invention [Means for solving the problem]

[0010] The above objectives are realized in a catheter for treating an obstruction in a blood vessel having at least one electrode pair inside a flexible angioplasty balloon at the distal end of the catheter. In some designs, the electrodes are flush, reducing the diameter of the device. In addition, a low-profile balloon is used that does not need to be folded prior to insertion into the cardiovascular system. Such a balloon can be expanded only a relatively small amount, sufficient to immerse the electrodes in a conductive fluid, prior to generating shock waves at the electrodes to treat the obstruction. The balloon can be made of a material with elastomeric properties so that when it is deflated following treatment, it returns to its original low-profile configuration.

[0011] The present invention provides a catheter for treating an occlusion in a blood vessel. An exemplary catheter for treating an occlusion in a blood vessel includes a tubular guidewire sheath defining a first lumen for receiving a guidewire and a second lumen for carrying the first wire, a shockwave generator located near a distal end of the catheter, the shockwave generator including at least one electrode pair, the electrodes of each pair being spaced apart and defining at least one gap, and a first wire extending within the second lumen, a proximal end of the first wire connectable to a pulsed voltage source and a distal end of the first wire connected to the at least one electrode pair. a reinforcing sheath wrapped around the guidewire sheath, a proximal end of the reinforcing sheath connectable to a pulsed voltage source and a distal end of the reinforcing wire sheath connected to the at least one electrode pair such that when a high voltage pulse is applied across the reinforcing wire sheath and the first wire, current flows across the at least one gap creating shock waves to treat the occlusion, and a cap sealably attached to the distal end of the catheter and surrounding the at least one electrode pair, the cap being fillable with a conductive fluid. The cap can be flexible and can be expanded to provide a space between an inner wall of the cap and the at least one electrode pair.

[0012] A second exemplary catheter for treating an occlusion in a blood vessel includes a tubular guidewire sheath defining a plurality of lumens, the plurality of lumens including a first lumen for carrying a guidewire, a shockwave generator located near a distal end of the catheter, the shockwave generator including at least one distal electrode pair, the electrodes of each pair being spaced apart and defining at least one gap, and a first wire and a second wire, such that when a high voltage pulse is applied across the first wire and the second wire, a current flows across the at least one gap. a first wire and a second wire, proximal ends of the first wire and the second wire connectable to a pulsed voltage source and distal ends of the first wire and the second wire connected to at least one distal electrode pair so that the conductive fluid flows through the first wire and the second wire and creates shock waves to treat the occlusion; and a flexible cap sealably attached to the distal end of the catheter and surrounding the at least one electrode pair, the flexible cap being inflatable with a conductive fluid such that the cap expands to provide a space between an inner wall of the cap and the at least one electrode pair. The present invention provides, for example, the following: (Item 1) 1. A catheter for treating an occlusion in a blood vessel, the catheter comprising: a tubular guidewire sheath defining a first lumen for receiving a guidewire and a second lumen for carrying the first wire; a shockwave generator located near a distal end of the catheter, the shockwave generator including at least one pair of electrodes, the electrodes of each pair being spaced apart to define at least one gap; a first wire extending within the second lumen, a proximal end of the first wire connectable to a pulsed voltage source and a distal end of the first wire connected to the at least one electrode pair; and a reinforced wire sheath wrapped around the guidewire sheath, a proximal end of the reinforced wire sheath connectable to the pulsed voltage source and a distal end of the reinforced wire sheath connected to the at least one electrode pair, whereby when a high voltage pulse is applied across the reinforced wire sheath and the first wire, current flows across the at least one gap creating shock waves to treat an occlusion; a cap sealably attached to the distal end of the catheter; Equipped with A catheter, wherein the cap surrounds the at least one electrode pair, the cap being fillable with a conductive fluid. (Item 2) 2. The catheter of claim 1, wherein the cap is flexible and can be expanded by inflation with the conductive fluid, and wherein a maximum expanded diameter of the flexible cap is no more than 15% greater than a contracted diameter of the flexible cap. (Item 3) 2. The catheter of claim 1, wherein the flexible cap is made from a material having elastomeric properties such that after being inflated, the flexible cap returns to a low-profile configuration when the cap is deflated. (Item 4) The at least one electrode pair comprises a first electrode pair, the first electrode pair comprising: a stripped portion of the first wire; a cutout in a conductive sheath wrapped around the entire circumference of the guidewire sheath; 2. The catheter of item 1, comprising: (Item 5) 5. The catheter of claim 4, wherein the cutout is defined by a hole in the conductive sheath. (Item 6) 5. The catheter of claim 4, wherein the tubular guidewire sheath includes an opening extending between an outer surface of the guidewire sheath and the second lumen, the opening being positioned over a removed insulation portion of the first wire such that when a high voltage pulse is applied across the reinforced wire sheath and the first wire, current flows through the opening. (Item 7) The at least one electrode pair comprises a second electrode pair, the second electrode pair comprising: an edge of the conductive sheath; a conductive emitter portion coplanar with said conductive sheath; Equipped with 5. The catheter of claim 4, wherein the emitter portion is electrically coupled to the reinforced wire sheath. (Item 8) 8. The catheter of claim 7, wherein an edge of the conductive sheath includes a groove and the emitter portion includes a coplanar tongue extending into the groove, whereby the tongue and groove define a U-shaped gap between the emitter portion and a second side edge. (Item 9) 8. The catheter of claim 7, wherein the first electrode pair and the second electrode pair are positioned approximately 180 degrees apart circumferentially around the conductive sheath. (Item 10) 2. The catheter of claim 1, wherein the tubular guidewire sheath further defines one or more fluid lumens for carrying a conductive fluid between the proximal end of the catheter and the balloon. (Item 11) 2. The catheter of claim 1, wherein the tubular guidewire sheath comprises a fluid inlet for flowing a conductive fluid into the balloon and a fluid outlet for flowing a conductive fluid out of the balloon, and the at least one electrode pair is positioned between the fluid inlet and the fluid outlet such that conductive fluid flowed through the balloon flows across the at least one electrode pair. (Item 12) 2. The catheter of claim 1, wherein the reinforced wire sheath comprises at least one braided or coiled metal wire encapsulated in a polymer. (Item 13) Item 13. The catheter of item 12, wherein the metal wire is flattened to reduce the profile of the reinforcing wire sheath. (Item 14) Item 13. The catheter of item 12, wherein the metal wire comprises at least one of copper and stainless steel. (Item 15) 2. The catheter of claim 1, wherein the guidewire sheath comprises a soft tip that tapers toward the distal end of the catheter. (Item 16) 1. A catheter for treating an occlusion in a blood vessel, the catheter comprising: a tubular guidewire sheath defining a plurality of lumens, the plurality of lumens including a first lumen for carrying a guidewire; a shockwave generator located near a distal end of the catheter, the shockwave generator including at least one distal electrode pair, the electrodes of each pair being spaced apart to define at least one gap; a first wire and a second wire, a proximal end of the first wire and the second wire being connectable to a pulsed voltage source and a distal end of the first wire and the second wire being connected to the at least one distal electrode pair, whereby when a high voltage pulse is applied across the first wire and the second wire, an electric current flows across the at least one gap creating a shock wave to treat an obstruction; a flexible cap sealably attached to the distal end of the catheter; Equipped with A catheter, wherein the flexible cap surrounds the at least one electrode pair, and the flexible cap is inflatable with a conductive fluid, whereby the cap expands and provides a space between an inner wall of the cap and the at least one electrode pair. (Item 17) Item 17. The catheter according to item 16, wherein when the flexible cap is in an expanded state, the diameter of the flexible cap is 10 to 15% larger than the diameter of the flexible cap in a contracted state. (Item 18) Item 17. The catheter of item 16, wherein the flexible cap comprises an angioplasty balloon, the surface area of ​​the balloon being small enough when the balloon is in a deflated state so that the balloon does not collapse when the catheter is advanced into a blood vessel. (Item 19) Item 17. The catheter of item 16, wherein the flexible cap comprises an extruded polymer tube. (Item 20) Item 17. The catheter of item 16, wherein the flexible cap is made from a material having elastomeric properties so that after it is contracted, it returns to a low-profile configuration when contracted. (Item 21) The at least one distal electrode pair comprises a first electrode pair and a second electrode pair, the first electrode pair comprising: a conductive portion of the first wire; and a conductive sheath wrapped around the entire circumference of the guidewire sheath; Equipped with The second electrode pair is the conductive sheath; a conductive portion of the second wire; Item 17. The catheter according to item 16, comprising: (Item 22) Item 17. The catheter of item 16, further comprising a third wire and a fourth wire extending within one or more lumens of the tubular guidewire sheath, proximal ends of the third wire and fourth wire connectable to the pulsed voltage source, and distal ends of the third wire and the fourth wire connected to at least one proximal electrode pair. (Item 23) The at least one proximal electrode pair comprises a third electrode pair and a fourth electrode pair, the third electrode pair comprising: a stripped portion of the third wire; and a further conductive sheath wrapped around the entire circumference of the guidewire sheath; Equipped with The fourth electrode pair is the further conductive sheath; and a stripped portion of the fourth wire; 23. The catheter according to item 22, comprising: (Item 24) 23. The catheter of claim 22, wherein the pulse voltage source is controllable to apply a high voltage pulse across either the first wire and the second wire or the third wire and the fourth wire to create shock waves in either the at least one distal electrode pair or the at least one proximal electrode pair. (Item 25) Item 17. The catheter of item 16, wherein the tubular guidewire sheath defines one or more fluid lumens for carrying a conductive fluid between the proximal end of the catheter and the balloon. (Item 26) Item 17. The catheter of item 16, wherein at least a portion of the tubular guidewire sheath comprises spacing features protruding from an outer surface of the guidewire sheath, the spacing features configured to maintain an inner wall of the balloon a controlled distance away from the outer surface of the guidewire sheath. [Brief description of the drawings]

[0013] [Figure 1A] FIG. 1A is an illustration of a shock wave angioplasty catheter used to treat an obstruction in a blood vessel, according to one embodiment of the subject invention.

[0014] [Figure 1B]FIG. 1B is an illustration of a distal end of a catheter having a low-profile, non-collapsible balloon in a deflated state, according to some embodiments of the subject invention.

[0015] [Figure 1C] FIG. 1C is an illustration of the distal end of the catheter of FIG. 1B showing the low-profile, non-collapsible balloon in an inflated state.

[0016] [Figure 1D] FIG. 1D is an illustration of a catheter of the subject invention used to treat a coronary total occlusion (CTO).

[0017] [Figure 1E] FIG. 1E is an illustration of a catheter of the subject invention being used in a blood vessel that is severely narrowed by a partial occlusion.

[0018] [Figure 2A] FIG. 2A is an exploded perspective view of a distal section of a catheter, according to one embodiment of the subject invention.

[0019] [Figure 2B] FIG. 2B is a side view illustration of the distal end of the catheter of FIG. 2A including a first electrode pair and a non-collapsible balloon covering the electrode pair.

[0020] [Figure 2C] FIG. 2C is an illustration of the embodiment of FIG. 2B rotated 180 degrees to show the second electrode pair.

[0021] [Figure 2D] FIG. 2D is an exploded perspective view of the catheter of FIG. 2A showing the fluid inlet and fluid outlet.

[0022] [Figure 2E] FIG. 2E is a cross-sectional view of the embodiment of FIGS. 2B-2C taken at a more proximal region of the catheter.

[0023] [Figure 2F] FIG. 2F is a cross-sectional perspective view of the catheter of FIG. 2E.

[0024] [Figure 2G] FIG. 2G is a longitudinal cutaway view of the catheter of FIG. 2A showing current flow through the catheter.

[0025] [Figure 3A] FIG. 3A is a perspective view of a distal section of a catheter according to another embodiment of the subject invention.

[0026] [Figure 3B] FIG. 3B is a side view illustration of the distal end of the catheter of FIG. 3A including a first distal electrode pair, a first proximal electrode pair, and a non-collapsible balloon covering the electrode pairs.

[0027] [Figure 3C] FIG. 3C is an illustration of the embodiment of FIG. 3B rotated 180 degrees to show a second distal electrode pair and a second proximal electrode pair.

[0028] [Figure 3D] FIG. 3D is a longitudinal cross-section of the distal end of the catheter of FIG. 3A showing the fluid pathway for the conductive fluid.

[0029] [Figure 3E] FIG. 3E is a cross-sectional view of the embodiment of FIGS. 3B-3C taken at a more proximal region of the catheter.

[0030] [Figure 3F] FIG. 3F is a cross-sectional perspective view of the catheter of FIG. 3E.

[0031] [Figure 3G] FIG. 3G provides a cross-sectional view of the catheter of FIG. 3A used to generate shock waves at the proximal emitter.

[0032] [Figure 3H]FIG. 3H provides a vertical cross-sectional view of the catheter of FIG. 3G used to generate shock waves at the distal emitter.

[0033] [Figure 4A] FIG. 4A illustrates a top view of a ring electrode configuration, according to some embodiments of the subject invention.

[0034] [Figure 4B] FIG. 4B illustrates an enlarged side view of the embodiment of FIG. 4A.

[0035] [Figure 5A] FIG. 5A illustrates a top view of a tongue and groove electrode configuration, according to some embodiments of the subject invention.

[0036] [Figure 5B] FIG. 5B illustrates a side view of the embodiment of FIG. 5A.

[0037] [Figure 5C] FIG. 5C illustrates an exploded view of an alternative tongue and groove electrode configuration arranged to create two electrode pairs, according to some embodiments of the subject invention.

[0038] [Figure 6A] FIG. 6A illustrates a spiral electrode configuration, according to some embodiments of the subject invention.

[0039] [Figure 6B] FIG. 6B illustrates the helical electrode configuration of FIG. 6A showing only the helical coiled wire. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The following description is presented to enable those skilled in the art to make and use the various embodiments disclosed herein. Descriptions of specific devices, 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 defined herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described and shown herein, but are to be accorded the scope consistent with the claims.

[0041] The assignee herein has developed several low-profile shockwave electrodes that may be suitable for use in angioplasty and / or valvuloplasty procedures. For example, in U.S. Publication No. 2019 / 0150960, the assignee discloses a low-profile electrode assembly in which an outer electrode is formed by a conductive sheath and an inner electrode is formed by removing a portion of the insulated wire (e.g., cutting a hole in the insulating layer near the end of the wire) to expose a conductive portion of the insulated wire. The inner electrode is placed a controlled distance away from the side edge of the conductive sheath to allow for reproducible arcing for a given current and voltage.

[0042] More recently, the assignee has developed several coplanar electrode assemblies for use in shockwave catheters. These designs provide novel configurations of electrode pairs with helical structures and tongue and groove designs, with each electrode on the same lateral plane, for example, to limit the overall thickness of the electrode assembly. These assemblies are particularly advantageous for generating shockwaves in tight, difficult-to-pass lesions or completely occluded vessels. For example, in U.S. Pat. No. 9,993,292 and U.S. Publication No. 2018 / 0098779 (incorporated herein by reference), the assignee discloses forming electrode pairs from helically wound wires to generate shockwaves at various gaps positioned around the entire circumference of a tubular structure. In U.S. Pat. No. 10,555,744 (also incorporated herein by reference), the assignee discloses a tongue and groove electrode assembly in which the electrode pairs are formed from a channel cutout in a conductive sheath and a coplanar tongue protrusion extending into the channel cutout.

[0043] Described herein is a catheter that incorporates a low-profile design element that allows for intravascular lithotripsy (IVL) treatment in tighter, hard-to-traverse calcific lesions and total coronary occlusions. The present invention is similar to existing IVL systems in that it may include an array of lithotripsy emitters (e.g., electrode pairs) on a catheter that is advanced into the patient's vessel to deliver shock waves to the occlusion. However, the present invention additionally includes a low-profile angioplasty balloon attached to the distal end of the catheter that can be positioned in the patient's vessel without folding. When deflated, the surface area of ​​the balloon is small enough that the balloon does not need to be folded during advancement of the catheter through the vessel. The low profile of the non-folding balloon advantageously allows the catheter to be advanced into even tighter areas of the vessel, such as those that are partially or completely occluded. Once the balloon is in position, the elastomeric material properties of the low-profile balloon allow it to be inflated with conductive fluid to increase the balloon's profile, i.e., to contact the occlusion and provide space within the balloon for the conductive fluid to soak the electrodes.

[0044] In some embodiments, the catheters described herein include additional low profile elements, such as flush electrodes, that further reduce the diameter of the distal end of the catheter. Additionally or alternatively, the catheter may provide electrical connections to the electrodes using a reinforced wire sheath wrapped around the entire circumference of the catheter shaft. The reinforced wire sheath provides the catheter with improved kink resistance, torqueability, and pushability for easier maneuvering of the device within the patient's vasculature. The inclusion of at least one electrical connection integrated into the reinforced wire sheath also improves the low profile aspect of the device by reducing the number of wires or other conductors that must be carried elsewhere within the catheter.

[0045] FIG. 1A illustrates an exemplary catheter 10 for treating an obstruction in a blood vessel, according to an embodiment of the subject invention. The catheter 10 is advanced over a guidewire 20 carried within a guidewire sheath and into an obstruction in a patient's vasculature, such as a stenotic lesion depicted in FIG. 1A. A distal end 14 of the catheter 10 includes a shockwave generator 16 that generates shockwaves in a plurality of emitters (e.g., an electrode pair) to disrupt calcified lesions. As used herein, a plurality of emitters includes an electrode pair having first and second electrodes separated by a gap, in which shockwaves are formed when an electric current flows across the gap between the electrodes of the pair (i.e., when a voltage is applied across the first and second electrodes). The electrode pair is arranged in a low-profile configuration that reduces the diameter of the distal end 14 of the catheter 10 and enables treatment of tight, hard-to-traverse lesions. In some embodiments, the shockwave generator 16 includes one or more coplanar electrode pairs or includes one or more electrodes that are at least partially retracted within the catheter 10.

[0046] A flexible cap 18 (e.g., a thin flexible angioplasty balloon) is sealably attached to the distal end 14 of the catheter 10 and forms an annular channel around the shaft 12 of the catheter. The flexible cap 18 surrounds the shockwave generator 16 such that shockwaves are generated in a closed system defined by the walls of the cap. The cap 18 is filled with a conductive fluid, such as saline. The conductive fluid allows acoustic shockwaves to propagate from the electrode pair of the shockwave generator 16, through the walls of the cap 18, and then into the target lesion. In some embodiments, the conductive fluid may also include an x-ray contrast agent to allow fluoroscopic visualization of the catheter 10 during use. In some embodiments, the cap is rigid and not flexible.

[0047] 1B-1C provide more detailed views of the distal end 14 of the catheter 10 of FIG. 1A including an exemplary non-foldable angioplasty balloon forming a flexible cap 18 over the shockwave generator 16. The balloon 18 has a sufficiently small diameter and surface area that it does not need to fold as a conventional angioplasty balloon does when advanced through the patient's vasculature. The extremely low profile of the balloon 18 allows the distal end 14 of the catheter to access tightly occluded areas of the vasculature. In some instances, the diameter of the distal end 14 of the catheter in the area of ​​the balloon 18 is one millimeter or less. To maintain its low profile, the balloon 18 is preferably formed from a material with elastomeric properties so that the balloon can be inflated during treatment of the occlusion and then returned to a low profile state when deflated after treatment. In some instances, the flexible cap 18 is an extruded polymer tube with semi-compliant material properties so that the polymer tube can be inflated and deflated similarly to an angioplasty balloon. As used herein, flexible cap and balloon are used interchangeably to describe the flexible annular structure that surrounds the electrode pairs and is inflated with a conductive fluid during treatment.

[0048] 1B shows an exemplary flexible balloon 18 in a deflated state, for example, during entry, advancement, and positioning of the balloon within a blood vessel. When the balloon 18 is in the deflated state, the surface area of ​​the balloon is small enough that the balloon does not fold when the catheter 10 is advanced through the blood vessel. When the balloon 18 is navigated through a patient's blood vessel inside a guide catheter or some other outer sheath (e.g., the tubular outer jacket of the catheter 10), the surface area of ​​the deflated balloon is small enough that the balloon does not fold inside the guide catheter or outer jacket. In such an example, the diameter of the balloon is smaller than the diameter of the guide catheter or outer jacket.

[0049] Once the balloon 18 is positioned within the patient's vasculature, additional conductive fluid can be flowed into the balloon to inflate the balloon and gently secure the outer surface of the balloon to the lesion. FIG. 1C shows the same balloon 18 in an inflated state. The balloon 18 is formed from a material having elastomeric properties such that the balloon can accommodate an inflation pressure of about 1 atmosphere to about 6 atmospheres. The balloon 18 is configured to expand only slightly when inflated with conductive fluid during treatment. For example, the maximum inflated diameter of the balloon 18 may be less than the original diameter of the balloon (i.e., the diameter of the balloon in a deflated state). twist 10%~15% below only Big The maximum diameter of the balloon in a deflated state can be determined by the material durometer of the balloon 18, its wall thickness, and / or the inflation pressure inside the balloon. When the balloon is inflated with a conductive fluid, the balloon 18 expands to provide a space between the inner surface of the balloon and the electrode pair 16. In some examples, the outer diameter of the guidewire sheath is about 0.028 inches and the inner diameter of the inflated balloon 18 is about 0.039 inches, providing a space of about 0.011 inches between the guidewire sheath and the inner surface of the balloon. The space ensures that the electrode pair 16 is immersed in the conductive fluid during shock wave generation and that the inner surface of the balloon 18 is far enough from the electrode pair that the balloon material is not damaged by the shock waves. In some embodiments, the diameter of the inflated balloon 18 is 1 millimeter or less. Optionally, the outer surface of the balloon 18 includes a hydrophilic coating to promote contact between the balloon and the target lesion.

[0050] After the lesion has been treated, the balloon 18 can be deflated to its original low-profile, contracted configuration. When the balloon 18 returns to the contracted state after being inflated, it should return to its original low-profile configuration (i.e., a configuration having a small surface area and diameter) so that the balloon does not collapse when the catheter 10 is removed from the patient's vasculature.

[0051] 1A, the exemplary catheter 10 also includes a proximal end or handle 22 that remains outside the patient's vasculature during treatment. The proximal end 22 includes an entry port for receiving a guidewire 20. The proximal end 22 also includes a fluid port 26 for receiving a conductive fluid for inflating and deflating the flexible cap 18 during treatment. An electrical connection port 24 is also located on the proximal end 22 to provide an electrical connection between the distal shockwave generator 16 and an external pulsed high voltage source 28, such as an intravascular lithotripsy (IVL) generator shown in FIG. 1A.

[0052] The catheter 10 also includes a flexible shaft 12 extending from the proximal handle 22 to the distal end 14 of the catheter. The shaft 12 provides various internal conduits connecting elements of the distal end 14 with the handle 22 of the catheter (see, e.g., FIGS. 2E-2F and 3E-3F for cross-sections of regions of an exemplary shaft). The shaft 12 includes a guidewire sheath including a lumen for receiving a guidewire 20. The guidewire sheath also defines several additional lumens extending longitudinally through the shaft 12. For example, one or more wire lumens can be included for carrying conductive wires that electrically connect the pulsed voltage source 28 with the electrodes of the distal shockwave generator 16. In some embodiments, one or more fluid lumens (e.g., fluid inlet and fluid outlet lumens) are provided within the guidewire sheath for carrying conductive fluid from the fluid port 26 into the cap 18. Optionally, the flexible shaft 12 includes a reinforced wire sheath wrapped around the entire circumference of the guidewire sheath. The reinforced wire sheath provides mechanical support to the flexible shaft 12 to facilitate torquing, pushing, and steering of the catheter 10 through the patient's vasculature. In some embodiments, the reinforced wire sheath is also configured to carry electrical current such that the reinforced wire sheath may be used to connect one or more of the distal electrode pairs of the shockwave generator 16 to the pulsed voltage source 28 (i.e., in place of one or more of the conductive wires). In some embodiments, a tubular outer jacket covers the guidewire sheath and the reinforced wire sheath and provides a barrier between the active elements of the catheter 10 and the in situ environment.

[0053] As shown in FIG. 1A, the catheter 10 can be used to treat an obstruction in a vessel, such as a stenotic lesion, a calcified portion of an artery, or some other obstruction in a blood vessel. In operation, a physician advances a guidewire 20 from an entry site on a patient (e.g., an artery in the groin area of ​​a leg) to a target area of ​​a blood vessel (e.g., an area having an obstruction that needs to be broken up). The catheter 10 is then advanced over the guidewire 20 to the target area of ​​the blood vessel. In some examples, the flexible cap 18 sealed to the distal end 14 is a non-folding balloon that has a low profile when deflated so that the balloon does not need to be folded while the device is advanced through the vessel. During the positioning phase of treatment, a guide catheter or outer jacket can be used to aid in the entry and steering of the catheter 10 within the vessel. The outer jacket provides tubular linear support to the catheter shaft 12 and maintains the deflated state of the flexible cap 18 during pushing, traversing, and placement of the catheter 10. The in situ location of the distal end 14 of the catheter 10 may be determined by x-ray imaging and / or fluoroscopy.

[0054] The distal end 14 of the catheter 10 is advanced as far as possible inside the tight lesion. The flexible cap 18 is then inflated with a conductive fluid (e.g., saline and / or saline mixed with an imaging contrast agent) introduced via the fluid port 26, allowing the conductive fluid to expand the cap so that the outer surface of the cap contacts the target lesion. The cap is inflated to an IVL pressure, which is about 1 atm to about 6 atm. The diameter of the flexible cap in the inflated state may be about 10-15% greater than the diameter of the flexible cap in the contracted state. However, in some instances, the diameter of the cap in the inflated state is less than 10% greater than the diameter of the cap in the contracted state. A voltage pulse is then applied across one or more electrode pairs (i.e., the emitters of the shock wave generator 16) by a pulsed high voltage source 28. Each pulse first ionizes the conductive fluid in the flexible cap 18, creating small gas bubbles around the shockwave generator 16 that insulate the electrodes. Fluid can be continuously flowed through the cap 18 during treatment at a constant rate to clear bubbles and debris from the electrodes. The fluid flow rate can be controlled throughout the treatment, but is generally within the range of about 1 ml / min to about 3 ml / min. At some point, a plasma arc forms across the electrode pair, creating a low impedance path through which current can flow freely. The heat from the plasma arc heats the conductive fluid, creating a rapidly expanding vapor bubble. The expansion of the vapor bubble creates a shock wave that is conducted through the fluid, through the walls of the flexible cap 18, and into the occlusion, where the energy shatters the hardened lesion.

[0055] For the treatment of occlusions in blood vessels, the voltage pulses applied by the voltage pulse generator 28 are typically in the range of about 2,000 volts to about 3,000 volts, preferably 2,300 to 3,000 volts. The pulse width of the applied voltage pulses ranges from 2 microseconds to 6 microseconds. The repetition rate or frequency of the applied voltage pulses may be about 1 Hz to about 10 Hz. However, the preferred voltage and repetition rate may vary depending on, for example, the size of the lesion, the degree of calcification, the size of the blood vessel, the patient's attributes, or the stage of treatment. For example, a physician may start with low energy shock waves and increase the energy as needed during the procedure. The magnitude of the shock waves can be controlled by controlling the voltage, current, duration, and repetition rate of the pulse voltage from the pulse voltage source 28. Further information about the physics of shock wave generation and their control can be found in U.S. Patent Nos. 8,956,371, 8,728,091, 9,522,012, and 10,226,265, each of which is incorporated by reference.

[0056] During an IVL treatment, one or more cycles of shock waves can be applied to create a more compliant vessel. For example, once the stenosis has been sufficiently softened by a first cycle of shock waves, the flexible cap 18 can be contracted and the distal end 14 of the catheter 10 can be advanced further into the occlusion. The flexible cap 18 can then be re-inflated and another cycle of shock waves can be applied. Further advancement of the cap 18 can be attempted after completion of the successive cycles.

[0057] The placement and spacing of the electrode pairs can be controlled to provide more effective shockwave therapy. For example, the electrode pairs of the shockwave generator 16 can be spaced around the entire circumference of the distal end 14 of the catheter 10 in consistent increments, e.g., 180 degrees apart or 90 degrees apart, to generate shockwaves more uniformly around the catheter. In some embodiments, the shockwave generator 16 includes electrode pairs positioned in various groupings spaced longitudinally along the catheter 10 within the flexible cap 18. For example, the shockwave generator 16 can include at least one distal electrode pair and at least one proximal electrode pair. In such an example, the pulsed voltage source 28 can be controlled to selectively generate high voltage pulses in either the proximal or distal electrode pairs, e.g., by applying voltage pulses across different sets of wires or other conductors leading to each pair. During the first phase of treatment (i.e., during initial treatment of a tight or completely occluding lesion), only the distal electrode pair is activated to generate shockwaves. After the tight lesion is corrected and the more proximal portion of the cap 18 is allowed to cross the lesion, the cap is again inflated and the more proximal electrode pair is activated to generate a more proximal shock wave.

[0058] The progress of the procedure may be monitored by x-ray and / or fluoroscopy. The shockwave cycles may be repeated until the obstruction is cleared or a channel is formed within the lesion with a sufficient diameter to receive a second treatment device with a larger profile. For example, the enlarged channel may receive a more conventional angioplasty balloon or a different catheter with a differently oriented shockwave source. Catheters of this type are described in U.S. Pat. No. 8,747,416 and U.S. Publication No. 2019 / 0150960, cited above. Once the lesion is sufficiently treated, the flexible cap 18 may be further inflated and then deflated, and the catheter 10 and guidewire 20 may be withdrawn from the patient.

[0059] FIG. 1D depicts a catheter 10 used to treat a total occlusion in a blood vessel, e.g., a coronary total occlusion (CTO). When treating a total occlusion, a guidewire is advanced at least partially into the stenotic lesion. The catheter is then advanced through the patient's vasculature, over the guidewire, and at least partially into the lesion. The flexible cap is then inflated with a conductive fluid until the cap gently contacts the lesion. A voltage pulse is then applied by a pulsed voltage source to the electrode pair at the tip of the catheter, generating shock waves that disrupt or loosen the lesion. The guidewire and catheter can then be advanced further into the lesion, and shockwave treatment can be repeated until the total occlusion is cleared or the diameter of the vessel allows for the placement of a larger, more conventional angioplasty device.

[0060] FIG. 1E illustrates the use of the inventive catheter 10 in a small blood vessel that is partially blocked by a stenotic lesion. In this situation, a guidewire can be advanced further into the lesion, and in some cases, through the entire lesion. After positioning the guidewire, the catheter is advanced through the lesion in incremental steps. At each step, the flexible cap is inflated and shock waves are generated to shatter the blockage and increase the diameter of the vessel. As above, once the diameter of the vessel becomes large enough, a larger diameter catheter can be advanced through the vessel to complete the treatment.

[0061] 2A-2G and 3A-3H provide more detailed views of the distal end of a catheter that may be included in a shock wave angioplasty device, such as any of the catheters described herein in FIGS. 1A-1E. FIG. 2A illustrates an exploded perspective view of the distal section of an exemplary catheter that includes two low-profile electrode pairs formed from a conductive sheath ("emitter bands", e.g., ring electrodes) wrapped around a guidewire sheath ("multi-lumen inner member"). The electrode pairs are electrically connected to an external pulsed voltage source using conductive wires (e.g., polyimide-insulated copper wires) and a conductive reinforced wire sheath ("flat wire braid") wrapped around the guidewire sheath. A cap (e.g., a low-profile angioplasty balloon or tubular polymer) is sealed to the distal tip of the catheter, covering the electrode pairs and a portion of the guidewire sheath. The catheter also includes an outer jacket having a diameter greater than the diameter of the distal section of the catheter. The outer jacket aids in the entry and positioning of the catheter by providing circumferential protection and mechanical support to the device.

[0062] FIG. 2B depicts a first side view of an exemplary catheter distal end 200 showing a first electrode pair in a dot circle configuration. FIG. 2C provides a second view of the catheter distal end 200 of FIG. 2B rotated 180 degrees to show a second electrode pair opposite the first electrode pair, the second electrode pair having a tongue and groove configuration. As shown in FIGS. 2B-2C, the catheter distal end 200 includes a guidewire sheath 210, a shockwave generator including a first electrode pair and a second electrode pair, and a flexible cap 280 that encloses the electrode pairs. The flexible cap 280 is wrapped around the entire circumference of the guidewire sheath 210 and sealed to the catheter distal end 200 using, for example, an adhesive seal or a heat bond, to form a closed annular channel around a portion of the guidewire sheath 210. In some embodiments, flexible cap 280 is a non-foldable angioplasty balloon (i.e., a low-profile angioplasty balloon) that can be positioned within a patient's vasculature without collapsing. When balloon 280 is in a deflated state (see, e.g., FIG. 1B), the surface area of ​​the balloon is small enough that the balloon does not collapse when the catheter is advanced into the vessel. In some examples, flexible cap 280 is an extruded tubular structure (i.e., an extruded polymer tube) formed from a semi-compliant polymer material. The semi-compliant polymer material allows flexible cap 280 to expand slightly in response to fluid pressure inside the flexible cap and then return to its original size when not under any pressure.

[0063] The flexible cap 280 is expandable with a conductive fluid, e.g., saline, such that the cap expands to provide space between the inner wall of the cap and the electrode pair (see, e.g., FIG. 1C). In some embodiments, the flexible cap 280 expands only a relatively small amount when it is in an expanded state, such that the cap maintains a low profile (e.g., has a diameter of less than one millimeter). For example, the maximum expanded diameter of the flexible cap 280 is less than the original diameter of the cap. twist 10%~15% below only BigThe flexible cap may be inflated such that the diameter of the flexible cap in the inflated state is 10-15% greater than the diameter of the cap in the contracted state. However, when inflated, the flexible cap 280 should provide enough space to allow the conductive fluid to surround and immerse the electrode pairs to avoid damage to the cap during shock wave generation. When inflated, the conductive fluid allows acoustic shock waves from the electrode pairs to propagate through the walls of the cap 280 and into the lesion in contact with the outer surface of the cap. In some embodiments, the conductive fluid also contains an x-ray contrast agent to allow fluoroscopic visualization of the catheter during IVL treatment.

[0064] Conductive fluid is admitted into the cap 280 via a fluid inlet 217 in the guidewire sheath 210 and removed from the cap via a fluid outlet 219 in the guidewire sheath. The fluid inlet 217 and fluid outlet 219 provide a channel extending from the surface of the guidewire sheath 210 to the respective fluid inlet and outlet lumens 216 and 218 in the guidewire sheath (and more proximally allowing the cap to access fluid provided by the fluid ports shown in FIG. 1A). When treating an occlusion, fluid can be intermittently flushed through the flexible cap 280 via the inlet 217 and outlet 219 to clear out air bubbles and debris generated when high voltage pulses across the electrodes create shock waves in the cap 280. The fluid inlet 217 and fluid outlet 219 are positioned to maximize fluid flow across the electrode pairs such that fluid forced through the cap 280 via the inlet and outlet flows across at least one of the electrode pairs. For example, as depicted in Figure 2B, the fluid inlet 217 and fluid outlet 219 can be positioned diagonally across the conductive sheath 220 such that one or more of the electrode pairs are positioned between the fluid inlet and fluid outlet. Figure 2D provides an exploded perspective view of an IVL catheter embodiment having a fluid inlet and fluid outlet positioned to allow fluid flow across the electrode pairs.

[0065] 2B-2C, guidewire sheath 210 provides various internal conduits connecting elements of distal end 200 with the proximal end of the catheter (not depicted), including guidewire lumen 211 for receiving a guidewire, wire lumen 212 for carrying insulated wire 242, and one or more fluid lumens 216, 218 for carrying fluid, e.g., conductive fluid, from the proximal end of the catheter to cap 280. The internal structure of guidewire sheath 210 is shown more clearly in FIGS. 2E-2F. FIG. 2E provides a cross-section of a more proximal section of the shaft of the catheter of FIGS. 2B-2C. FIG. 2F provides a perspective view of the cross-section of FIG. 2E inside the outer jacket of catheter 200.

[0066] As shown in FIG. 2E, the catheter includes a central tubular guidewire sheath 210 that defines multiple lumens. The multiple lumens include a first lumen (i.e., guidewire lumen 211) for receiving a guidewire and a second lumen (i.e., wire lumen 212) for carrying a conductive wire 242. The guidewire lumen 211 may extend through the center of the guidewire sheath 210 or may be slightly offset from the center, as shown in FIG. 2E. The guidewire lumen 211 is shaped to loosely receive a guidewire having a diameter of about 0.014 inches to about 0.035 inches. The wire lumen 212 is shaped to carry at least one wire 242 for flowing electrical current from a pulsed voltage source (such as the pulsed voltage source of FIG. 1A) to the electrode pair at the distal end 200 of the catheter. In some examples, the wire is a polyimide insulated copper wire having a diameter of about 0.003 inches to about 0.007 inches. The wire is flattened to reduce the profile of the catheter, and the flattened wire may have a cross section that is approximately 0.003 inches thick and approximately 0.010 inches wide. The multiple lumens also include a fluid inlet lumen 216 for flowing fluid into the cap 280 and a fluid outlet lumen 218 for flowing fluid out of the cap 280. Although the lumens are depicted in FIG. 2E as having a generally circular cross section, the lumens within the guidewire sheath 210 may have any desired shape. For example, the wire 242 may have a flattened shape and the second lumen 212 may have a flattened or elliptical shape to accommodate the flattened wire. Similarly, the fluid inlet lumen 216 or the fluid outlet lumen 218 may be disposed around the circumference of the guidewire sheath (e.g., within the annular space between the sheath and the reinforced wire sheath 230). The location, size, and shape of any of the lumens can be modified to reduce the profile of the catheter or to provide some other benefit. Additionally, various lumens may be combined (eg, by providing two or more insulated wires in the same lumen) or eliminated without departing from the scope of the present invention.

[0067] Surrounding the guidewire sheath 210 is a tubular reinforced wire sheath 230 formed from at least one conductive reinforced wire material (e.g., wire that is braided, coiled, or both), such as reinforced copper or stainless steel. As described above with reference to FIG. 1A, the reinforced wire sheath 230 can be used to carry electrical current from a pulsed voltage source at the proximal end of the catheter to the distal end 200 of the catheter and provide electrical current to one or more electrode pairs. The proximal end of the reinforced wire sheath 230 is connectable to a pulsed voltage source, while the distal end of the reinforced wire sheath is connected to one or more of the electrode pairs. In some embodiments, the reinforced wire sheath 230 is connected to the electrode pairs via conductive portions of metal (e.g., conductive emitter portion 234 depicted in FIG. 2C) that are shaped to form electrodes. In addition to providing electrical current to the electrode pairs at the distal end 200, the reinforced wire sheath 230 can also provide advantageous mechanical properties to the catheter shaft. For example, the material composition of the reinforced wire sheath 230 may provide increased torqueability, pushability, or enhanced stiffness to the catheter shaft to facilitate steering the catheter through the patient's vasculature. In some embodiments, the reinforced sheath 230 includes one or more braided or coiled metals (e.g., metal wires) that are at least partially encapsulated within a polymer. The polymer encapsulation insulates the conductive metal elements of the sheath 230 and / or provides improved mechanical properties. The reinforced metal of the sheath 230 may be flattened to reduce the profile of the sheath 230 and allow the catheter to more easily fit into tightly occluded blood vessels.

[0068] 2B-2C, the distal end 200 of the catheter also includes a soft tip 290 that tapers toward the distal tip of the catheter. The soft tip 290 can be formed from a polymer or any other suitable biocompatible material. In a preferred embodiment, the tip 290 is formed at least in part from a radiopaque material such as platinum, iridium, or stainless steel to allow fluoroscopic visualization of the catheter during use. The soft tip also includes a guidewire lumen such that during operation, the catheter is advanced through the patient's vasculature along a guidewire with the soft tip leading. Providing a soft tip 290 may prevent physical damage to the vessel wall while facilitating contact with and entry into tight lesions within the vasculature.

[0069] The distal tip 200 also includes a catheter shock wave generator that includes a first electrode pair shown in Figure 2B and a second electrode pair shown in Figure 2C. The electrode pairs have a low profile configuration (e.g., coplanar or at least partially retracted into the guidewire sheath 210) to reduce the diameter of the distal tip 200. The first and second electrode pairs are located approximately 180 degrees apart circumferentially around the guidewire sheath 210. The electrodes of each pair are spaced to define a gap through which current can flow to generate shock waves in the conductive fluid inside the flexible cap 280.

[0070] An electrode pair can be formed by the side edges of a conductive sheath (e.g., a ring electrode) and a conductive portion of the wire, as described in assignee's prior application U.S. Publication No. 2019 / 0150960. The conductive portion of the wire can be formed by removing a portion of the insulating layer of the insulated wire near the distal end of the wire to expose the conductive portion of the wire. The location, size, and shape of the removed portion can be varied to control the location, direction, and / or magnitude of the shock wave. In some embodiments, an electrode can be formed by cutting the end of an insulated wire to expose a conductive cross-section. In some embodiments, a flat wire rather than a round wire is used to further reduce the cross-sectional profile of the electrode assembly.

[0071] 2B, the first electrode pair includes a first electrode formed from an insulation removed portion 243 of a wire, e.g., conductive wire 242, extending through a lumen 212 of the guidewire sheath 210. The first electrode pair also includes a second electrode formed from a cutout 222 in a conductive sheath 220 wrapped around the entire circumference of the guidewire sheath. The cutout 222 in the conductive sheath 220 is defined by a generally circular hole in the conductive sheath. The location, size, and shape of the cutout 222 can be varied to control the location, direction, and / or magnitude of the shock wave. In some examples, the conductive sheath 220 is at least partially retracted into the guidewire sheath 210 to reduce the profile of the electrode assembly and the diameter of the distal end 200 of the catheter.

[0072] The insulation removed portion 243 of the wire 242 and the cutout 222 of the conductive sheath 220 are spaced to define a gap between the first and second electrodes of the first electrode pair. The gap spacing can be controlled to generate a reproducible electric arc in the conductive fluid between the electrodes. The electrode spacing can be modified to generate a shock wave having a desired magnitude for a given voltage and current output from the pulsed voltage source. To allow current flow between the insulation removed portion 243 of the wire 242 within the lumen and the cutout 222 of the outer conductive sheath 220, the guidewire sheath 210 includes an opening extending between the outer surface of the guidewire sheath and the wire lumen 212. The opening is positioned over the insulation removed portion 243 of the wire 242 and under the cutout 222 such that when a high voltage pulse is applied across the reinforced wire sheath 230 and the wire 242, current flows through the opening. The size of the opening may correspond to the size of the insulation removed portion 243 of the wire 242, the size of the cutout 222 in the conductive sheath 220, or some other desired size or shape.

[0073] FIG. 2C provides a cross-section of the distal end 200 of the catheter of FIG. 2B rotated 180 degrees to show a second electrode pair of the shockwave generator. The second electrode pair includes a first electrode formed from the edge 224 of the conductive sheath 220 and a second electrode formed from a conductive emitter portion 234 coplanar with the conductive sheath 220. As shown in FIG. 2C, the first and second electrodes of the second electrode pair are formed in a tongue and groove configuration. The edge 224 of the conductive sheath 220 is defined by a longitudinal cut in the side of the conductive sheath to form a "groove". The "tongue" is formed from the conductive emitter portion 234 extending into the groove such that the tongue and groove defines a U-shaped gap between the emitter portion 234 and the edge 224 of the conductive sheath 220. The geometry of the gap can be controlled to generate a reproducible electrical arc in the conductive fluid between the pair of electrodes, generating shock waves having a desired magnitude. The conductive sheath 220 and emitter portion 234 are coplanar to reduce the profile of the electrode pair and the diameter of the distal end 200 of the catheter. In some embodiments, the conductive emitter portion 234 additionally includes PET heat shrink tubing. Further information on tongue and groove electrode configurations is contained in Applicant's U.S. Pat. No. 10,555,744, which is incorporated herein by reference.

[0074] As shown in FIG. 2C, emitter portion 234 is coupled to a distal end of reinforced wire sheath 230, which electrically connects the second electrode pair to a pulsed voltage source (not depicted). However, in alternative embodiments, emitter portion 234 may be coupled to an additional wire, e.g., extending along the catheter, which electrically connects the second electrode pair to a pulsed voltage source. Turning again to FIG. 2B, the first electrode pair is electrically connected to the pulsed voltage source via wire 242, which extends within lumen 212 of guidewire sheath 210. A proximal end of wire 242 is connectable to the pulsed voltage source, while a distal end of wire 242 is connected to (i.e., forms part of, or is otherwise electrically connected to) the first electrode pair.

[0075] The wire 242 and reinforced wire sheath 230 complete a circuit between the electrode pairs and a pulsed voltage source such that when a high voltage pulse is applied across the reinforced wire sheath 230 and wire 242, current flows across the gap between the electrodes of the first and second electrode pairs, creating shock waves to treat the occlusion. Figure 2G shows an exemplary current flow through a catheter with one tongue and groove electrode pair and one point circle electrode pair connected to a voltage source with a reinforced wire sheath formed from polyimide insulated copper wire and flat copper clad stainless steel wire.

[0076] In operation, the physician may simultaneously connect wire 242 to the positive lead of a voltage pulse generator and reinforced wire sheath 230 (or a wire electrically connected to the proximal end of the sheath) to the negative lead or ground. In such an example, current will flow from the voltage source, up wire 242, across a first gap between insulation removed portion 243 of the wire and cutout 222 in conductive sheath 220, creating a plasma arc that generates a shock wave at a first electrode pair. Current then flows across conductive sheath 220 and across a second gap between edge 224 of conductive sheath 220 and conductive emitter portion 234, creating another plasma arc that generates a shock wave at a second electrode pair. Current then flows from conductive emitter portion 234 to reinforced wire sheath 230 and up the reinforced wire sheath to the negative lead or ground. Alternatively (as seen in FIG. 1G), the physician may connect the reinforced wire sheath 230 (or a wire electrically connected to the reinforced wire sheath) to the positive lead of the pulse generator and connect wire 242 to the negative lead or ground, so that the current travels in opposite paths across the first and second electrode pairs.

[0077] Figures 3A-3H provide detailed views of the distal end of an alternative catheter that may be included in a shockwave angioplasty device, such as any of the catheters described herein in Figures 1A-1E. Unlike Figures 2A-2G, the distal end 300 of the shockwave generator of the catheter of Figures 3A-3H includes at least one distal emitter (e.g., one or more distal electrode pairs) and at least one proximal emitter (e.g., one or more proximal electrode pairs). Figure 3A provides a perspective view of an exemplary catheter including a distal emitter and a proximal emitter. As illustrated in Figure 3A, the distal and proximal emitters are formed from respective proximal conductive sheaths (e.g., proximal electrode ring) and distal conductive sheaths (e.g., distal electrode ring) that are wrapped around the entire circumference of the guidewire sheath. The distal emitter includes one or more distal electrode pairs, while the proximal emitter includes one or more proximal electrode pairs. The electrode pairs have a low-profile configuration and are electrically connected to an external pulsed voltage source using several conductive wires that extend through the lumen of the guidewire sheath.

[0078] FIG. 3B depicts a first side of an exemplary catheter distal end 300 showing a first distal electrode pair and a first proximal electrode pair. FIG. 3C provides a second view of the catheter distal end 300 of FIG. 3B rotated 180 degrees to show a second distal electrode pair and a second proximal electrode pair. As shown in FIGS. 3B-3C, the catheter distal end 300 includes a guidewire sheath 310, a shockwave generator including two distal electrode pairs and two proximal electrode pairs, and a flexible cap 380 that encloses the electrode pairs. The flexible cap 380 is wrapped around the entire circumference of the guidewire sheath 310 and sealed to the catheter distal end 300 using, for example, an adhesive seal or a heat seal, to form a closed annular channel around the guidewire sheath 310. In some embodiments, flexible cap 380 is a non-foldable angioplasty balloon (i.e., a low-profile angioplasty balloon) that can be positioned within a patient's vasculature without collapsing. When balloon 380 is in a deflated state (see, e.g., FIG. 1B), the surface area of ​​the balloon is small enough that the balloon does not collapse when the catheter is advanced into the vessel. In some examples, flexible cap 380 is an extruded tubular structure (i.e., an extruded polymer tube) formed from a semi-compliant polymer material. The semi-compliant polymer material allows flexible cap 380 to expand slightly in response to fluid pressure inside the flexible cap and then return to its original size when not under any pressure.

[0079] The flexible cap 380 is inflatable with a conductive fluid, e.g., saline, such that the cap expands to provide space between the inner wall of the cap and the proximal and distal electrode pairs (see, e.g., FIG. 1C). In some embodiments, the flexible cap 380 expands only a relatively small amount so that the inflated cap maintains a low profile (e.g., has a diameter less than one millimeter). For example, the maximum inflated diameter of the flexible cap 380 is less than the original (i.e., contracted) diameter of the cap. twist 10%~15% below only BigHowever, when inflated, the flexible cap 380 should provide enough space to allow the conductive fluid to surround and immerse the electrode pairs to avoid damage to the cap during shock wave generation. When inflated, the conductive fluid allows acoustic shock waves from the proximal and distal electrode pairs to propagate through the walls of the flexible cap 380 and into the lesion in contact with the outer surface of the cap. In some embodiments, the conductive fluid also contains an x-ray contrast agent to allow fluoroscopic visualization of the catheter during IVL treatment.

[0080] Conductive fluid is admitted into the cap 380 via a fluid inlet 317 in the guidewire sheath 310 and removed from the cap via a fluid outlet 319 in the guidewire sheath. The fluid inlet 317 and fluid outlet 319 provide a channel extending from the surface of the guidewire sheath 310 to the respective fluid inlet and outlet lumens 316 and 318 in the guidewire sheath (and more proximally allowing the flexible cap to access the fluid provided by the fluid ports shown in FIG. 1A). When treating an occlusion, fluid can be intermittently flushed through the cap 380 via the inlet 317 and outlet 319 to clear out air bubbles and debris generated when high voltage pulses across the electrodes create shock waves in the cap. The fluid inlet 317 and fluid outlet 3219 are positioned to maximize fluid flow across the electrode pairs such that fluid forced through the cap 380 via the inlet and outlet flows across at least one of the electrode pairs. For example, as depicted in Figure 3A, the fluid inlet 317 and fluid outlet 319 can be positioned diagonally across one or more of the conductive sheaths 330, 336 such that one or more of the electrode pairs are positioned between the fluid inlet and outlet. Figure 3D provides a cross-sectional view of the distal section of an exemplary catheter depicting fluid flow through the inner lumen of the catheter and the flexible cap via the fluid inlet and outlet in the guidewire sheath.

[0081] As illustrated in Figures 3A-3D, the guidewire sheath 310 provides various internal conduits connecting elements of the distal end with the proximal end of the catheter, including a guidewire lumen, a lumen for carrying a conductive wire, and one or more fluid lumens. The internal structure of the guidewire sheath 310 is shown more clearly in Figure 3E, which provides a cross-section of a more proximal section of the catheter shaft. Figure 3F provides a perspective view of the cross-section of Figure 3E inside a flexible cap 380 of the catheter 300.

[0082] As shown in FIG. 3E, the catheter includes a central tubular guidewire sheath 310 that defines multiple lumens. The multiple lumens include a guidewire lumen 311 for receiving a guidewire. The guidewire lumen 311 may extend through the center of the guidewire sheath 310, or may be slightly offset from the center, as shown in FIGS. 3E-3F. The guidewire lumen 311 is shaped to loosely receive a guidewire having a diameter of about 0.014 inches to about 0.035 inches. The guidewire sheath 310 also includes four wire lumens for carrying respective conductive wires 342, 344, 346, 348 for flowing electrical current from a pulsed voltage source (such as the pulsed voltage source of FIG. 1A) to the proximal and distal electrode pairs. In some examples, the wires 342, 344, 346, 348 are polyimide insulated copper wires having a diameter of about 0.003 inches to about 0.007 inches. The wires 342, 344, 346, 348 are flattened to reduce the profile of the catheter, and the flattened wires may have a cross-section that is approximately 0.003 inches thick and approximately 0.010 inches wide. The multiple lumens also include a fluid inlet lumen 316 for flowing fluid into the cap 380 and a fluid outlet lumen 318 for flowing fluid out of the cap 380. Although the lumens are depicted in FIGS. 3E-3F as having a generally circular cross-section, the lumens within the guidewire sheath 310 may have any desired shape. For example, one or more of the wires 342, 344, 346, 348 may have a flattened shape and the associated lumen may have a flattened or elliptical shape to accommodate the flattened wires. Similarly, the fluid inlet lumen 316 or the fluid outlet lumen 318 may be disposed around the circumference of the guidewire sheath 310 (e.g., within the annular space between the sheath and the reinforced wire sheath 330). The location, size, and shape of any of the lumens can be modified to reduce the profile of the catheter or to provide some other benefit. Additionally, various lumens may be combined (e.g., by providing two or more insulated wires within the same lumen) or eliminated without departing from the scope of the invention.

[0083] 3E-3F, at least a portion of the guidewire sheath 310 includes a spacing feature 312 protruding from an outer surface of the guidewire sheath. The spacing feature 312 is configured to maintain an inner surface of the cap 380 a controlled distance away from the outer surface of the guidewire sheath 310, for example, to prevent damage to the cap caused by shock waves generated at the electrode pair. In some embodiments, the spacing feature 312 surrounds one or more of the conductive sheaths 320, 326 or each extends between the proximal conductive sheath 320 and the distal conductive sheath 326.

[0084] 3B-3C, the distal end 300 of the catheter also includes a soft tip 390 that tapers toward the distal tip of the catheter. The soft tip 390 can be formed from a polymer or any other suitable biocompatible material. In a preferred embodiment, the tip 390 is formed at least in part from a radiopaque material such as platinum, iridium, or stainless steel to allow fluoroscopic visualization of the catheter during use. The soft tip also includes a guidewire lumen such that during operation, the catheter is advanced through the patient's vasculature along a guidewire with the soft tip leading. Providing a soft tip 390 may prevent physical damage to the vessel wall while facilitating contact with and entry into tight lesions within the vasculature.

[0085] The distal end 300 also includes a catheter shockwave generator including a first distal electrode pair and a first proximal electrode pair shown in Figure 3B and a second distal electrode pair and a second proximal electrode pair shown in Figure 3C. The first and second distal electrodes are formed from conductive portions 343, 355 of the first and second wires 342, 344, respectively, and a distal conductive sheath 326 (e.g., distal ring electrodes), while the first and second proximal electrode pairs are point-circle electrode pairs formed from insulation removed portions of the third and fourth wires 346, 348, and a proximal conductive sheath 320. The electrode pairs have a low-profile configuration to reduce the diameter of the distal end 300. For example, the proximal conductive sheath 320 and / or the distal conductive sheath 326 may be at least partially retracted into the guidewire sheath 310 to reduce the diameter of the distal end 300 of the catheter.

[0086] As mentioned above, an electrode pair can be formed by the side edges of the conductive sheath and a portion of the wire. The portion of the wire can be formed by removing a portion of the insulation layer of the wire near the distal end of the wire to expose the conductive portion of the wire. The location, size, and shape of the removed portion can be varied to control the location, direction, and / or magnitude of the shock wave. In some embodiments, an electrode can be formed by cutting the end of an insulated wire to expose a conductive cross-section. In some embodiments, a flat wire rather than a round wire is used to further reduce the cross-sectional profile of the electrode assembly.

[0087] With reference to FIG. 3B, the first distal electrode pair includes a first electrode formed from a conductive portion 343 of a first wire 342 extending through the lumen of the guidewire sheath 310. The first distal electrode pair also includes a second electrode formed from a side edge 328 of a distal conductive sheath 326 that is wrapped around the entire circumference of the guidewire sheath 310. With reference to FIG. 3C, the second distal electrode pair includes a first electrode formed from a side edge 328 of the distal conductive sheath 326. The second distal electrode pair also includes a second electrode formed from a conductive portion 345 of a second wire 344 that extends through the lumen of the guidewire sheath 310. The first distal electrode pair and the second distal electrode pair are located approximately 180 degrees apart circumferentially around the distal conductive sheath 326.

[0088] The conductive portion 343 of the first wire 342 is spaced from the side edge 328 of the distal conductive sheath 326 to define a first gap between the first distal pair of electrodes. Similarly, the conductive portion 345 of the second wire 344 is spaced from the side edge 328 of the distal conductive sheath 326 to define a second gap between the second distal pair of electrodes. The gap spacing can be controlled to generate a reproducible electrical arc in the conductive fluid between each pair of electrodes to generate shock waves having a desired magnitude for a given voltage and current output from the pulsed voltage source. To allow current flow between the conductive portions 343, 345 of the wires 342, 344 and the distal conductive sheath 326, the guidewire sheath 310 includes a distal opening extending between an outer surface of the guidewire sheath 310 and the lumen containing the first wire 342 and the second wire 344. The openings are positioned between the conductive portions 343, 345 of the wires 342, 344 and the side edge 328 of the distal conductive sheath 326 such that when a high voltage pulse is applied across the first wire 342 and the second wire 344, current flows through the respective openings.

[0089] Turning again to FIG. 3B, the first proximal electrode pair includes a first electrode formed from an insulation removed portion 347 of a third wire 346 extending through the lumen of the guidewire sheath 310. The first proximal electrode pair also includes a second electrode formed from a first cutout 322 in the proximal conductive sheath 320. Referring to FIG. 3C, the second proximal electrode pair includes a first electrode formed from an insulation removed portion 349 of a fourth wire 348 extending through the lumen of the guidewire sheath 310. The second proximal electrode pair also includes a second electrode formed from a second cutout 324 in the proximal conductive sheath 320. The first proximal electrode pair and the second proximal electrode pair are located approximately 180 degrees apart circumferentially around the proximal conductive sheath 320.

[0090] An insulation removed portion 347 of the third wire 346 is spaced from the first cutout 322 in the proximal conductive sheath 320 to define a first gap between the first proximal pair of electrodes. Similarly, an insulation removed portion 349 of the fourth wire 348 is spaced from the second cutout 324 in the proximal conductive sheath 320 to define a second gap between the second proximal pair of electrodes. The gap spacing can be controlled to generate a repeatable electrical arc in the conductive fluid between each pair of electrodes to generate shock waves having a desired magnitude for a given voltage and current output from the pulsed voltage source. To allow current flow between the insulation removed portions 347, 349 of the wires 346, 348 within the lumen and the exterior cutouts 322, 324 in the proximal conductive sheath 320, the guidewire sheath 310 includes proximal openings extending between an outer surface of the guidewire sheath 310 and the lumen containing the third wire 346 and the fourth wire 348. The openings are positioned between the insulation removed portions 347, 349 of the wires 346, 348 and the cutouts 322, 324 in the proximal conductive sheath 320 such that when a high voltage pulse is applied across the third wire 346 and the fourth wire 348, current flows through the respective openings.

[0091] As shown in Figures 3B-3C, the distal ends of the first wire 342 and the second wire 344 are connected to (i.e., form part of or are electrically connected to) the distal electrode pair, and the proximal ends of the first wire 342 and the second wire 344 (not shown) are connectable to a pulse voltage source such that when a high voltage pulse is applied across the first wire 342 and the second wire 344, current flows across the first gap and the second gap creating a shock wave to treat the occlusion near the distal electrode. Similarly, the distal ends of the third wire 346 and the fourth wire 348 are connected to the proximal electrode pair and the proximal ends of the third wire 346 and the fourth wire 348 are connectable to a pulse voltage source such that when a high voltage pulse is applied across the third wire 346 and the fourth wire 348, current flows across the first gap and the second gap, creating a shock wave to treat the occlusion near the proximal electrode.

[0092] In operation, a physician may wish to independently control the distal and proximal electrode pairs to selectively generate shock waves at different portions of the cap 380. FIG. 3G illustrates selective firing of the proximal emitter by applying a current to the proximal emitter wire. FIG. 3H illustrates selective firing of the distal emitter by applying a current to the distal emitter wire. Separate wiring of the proximal and distal electrode pairs advantageously allows for the generation of either distal or proximal shock waves by applying a high voltage pulse only across the wires corresponding to the proximal or distal electrodes. In other words, the pulse voltage source may be controllable to apply a high voltage pulse either across the first wire 342 and the second wire 344 to create shock waves at the distal electrode pair, or across the third wire 346 and the fourth wire 348 to create shock waves at the proximal electrode pair.

[0093] It should be noted that the elements and features of the exemplary catheters illustrated in Figures 2A-2G and 3A-3H may be rearranged, recombined, and modified without departing from the present invention. For example, Figures 2A-2G provide a catheter including a reinforced wire sheath, but the reinforced wire sheath may be replaced by one or more conductive wires, as seen in the catheter of Figures 3A-3H. Relatedly, one or more of the wires in Figures 3A-3H may be replaced by a reinforced wire sheath. Similarly, features of the embodiments of Figures 3A-3H, such as spacing features, additional proximal conductive sheaths, additional electrode pairs, and / or independently controlled distal and proximal electrode pairs, may be combined with the catheter of Figures 2A-2G without departing from the subject invention.

[0094] Additionally, although Figures 2A-2G and 3A-3H illustrate two examples of shockwave generators, the subject invention is intended to include catheters having a variety of electrode configurations. For example, the shockwave generator of the exemplary catheter may include two tongue and groove electrode pairs (see Figures 2B and 5A-5C), two point and circle electrode pairs (see the proximal electrode pairs in Figures 2C and 3B-3C), or two electrode pairs formed from a distal conductive portion of a wire and a conductive sheath (see, e.g., the distal electrode pair in Figures 3B-3C), or any other desired configuration. Additionally, the placement and spacing of the electrode pairs may be modified without departing from the subject invention. For example, the electrode pairs may be spaced around the entire circumference of the catheter in consistent increments, e.g., 180 degrees apart, 90 degrees apart, or 60 degrees apart, to generate shockwaves more uniformly around the catheter. 3A-3H, the shockwave generator includes electrode pairs positioned in various groupings spaced longitudinally along the catheter. For example, the shockwave generator may include multiple electrode pairs defined by multiple conductive sheaths spaced longitudinally along the catheter.

[0095] Figures 4A-4B, 5A-5C, and 6A-6B depict several exemplary shockwave electrode assemblies that may be included within a shockwave angioplasty device, such as any of the catheters illustrated in Figures 1A-1C, 2A-2G, and 3A-3H and described herein.

[0096] 4A and 4B illustrate an exemplary variation of an electrode pair. This embodiment includes a pair of spaced apart ring electrodes provided as a first conductive sheath 52b and a second conductive sheath 58c wrapped around the entire shaft of the catheter. One or more of the sheaths 58c, 52b can be retracted into the shaft to reduce the diameter of the shockwave generator and allow the catheter to enter tighter lesions. In this example, the electrode pair is formed from the respective side edges of the first conductive sheath 52b and the second conductive sheath 58c. The spacing between the side edges of the two conductive sheaths defines a spark gap 64 between the electrodes. FIG. 4B illustrates a different view of the electrodes of FIG. 4A, with the gap 64 shown larger for clarity. A first wire "A" 36 is connected to the first conductive sheath 52b and a second wire "B" is connected to the ring electrode 58c. When a high voltage pulse is applied across the first wire "A" 36 and the second wire "B", a plasma arc is created across the spark gap 64 between the ring electrodes. The plasma arc creates a shock wave to treat the occlusion.

[0097] 5A, 5B, and 5C illustrate exemplary tongue and groove electrode pair configurations formed from a conductive sheath (e.g., a ring electrode) and a conductive emitter portion extending into the conductive sheath. In these examples, the first electrode of the pair is formed from the edge of the conductive sheath defined by a groove cut into the side of the conductive sheath. The second electrode of the pair is formed from a conductive tongue-shaped emitter portion extending into the groove. The "tongue" of the conductive emitter portion may be formed from a conductive portion of a wire (e.g., an insulation-removed portion or a conductive end of the wire) or some other conductive metal portion shaped to fit within the groove. The tongue and groove define a U-shaped spark gap between the electrodes of the pair. As illustrated in FIG. 5B, a first wire 36 is connected to the "tongue" 52 of the conductive emitter portion and a second wire 38 is connected to the ring electrode conductive sheath 58. When a high voltage pulse is applied across the first wire 36 and the second wire 38, a plasma arc is created across the spark gap 64 between the tongue 52 and the groove 60. The plasma arc creates a shock wave to treat the stenosis.

[0098] FIG. 5C illustrates a related exemplary tongue and groove electrode embodiment that provides two electrode pairs formed from a single conductive sheath 58a (e.g., a single ring electrode) wrapped around the entire circumference of the guidewire sheath. As shown in FIG. 5C, a first groove 60a and a second groove 60b are cut into the edge of the same conductive sheath 58a. The first and second grooves may be located 180 degrees apart around the entire circumference of the conductive sheath. Corresponding conductive tongue-shaped emitter portions extend into the first and second grooves to create the first and second electrode pairs. The first electrode pair is formed from the edge of the conductive sheath defined by the first groove 60a and the first tongue-shaped emitter portion 68 extending into the first groove. The second electrode pair is formed from the edge of the conductive sheath defined by the second groove 60b and the second tongue-shaped emitter portion 52 extending into the second groove. Each electrode pair defines a U-shaped gap between the tongue and groove of each of the first and second electrode pairs. In such an example, the first wire 38 is connected to the "tongue" 68 of the first emitter portion, and the second wire 36 is connected to the "tongue" 52 of the second emitter portion. When a high voltage pulse is applied across the first wire 38 and the second wire 36, current flows down the first wire 38, jumps the first U-shaped gap, and creates a first plasma arc. The current then travels along the conductive sheath 58a, jumps the second U-shaped gap, creates a second plasma arc, and then travels back along the second wire 36 to the voltage source. The first and second plasma arcs create shock waves at two locations around the guidewire sheath, providing a more complete circumferential treatment of the lesion within the vessel. Further information and examples of tongue and groove electrode configurations can be found in US Pat. No. 10,555,744, which is incorporated herein by reference.

[0099] 6A and 6B illustrate another variation of the electrode pair of the subject invention. In this case, a first wire 36 and a second wire 38 are helically wrapped around the shaft of the catheter. One or more electrode pairs are created by selectively removing insulation from the wires to define electrodes. For example, a first electrode pair comprises a first insulation removed portion of the first wire 36 and a first insulation removed portion of the second wire 38. Additional electrode pairs can be created by removing additional portions of insulation from the wires (i.e., a second electrode pair comprises a second insulation removed portion of the first wire and a second insulation removed portion of the second wire, etc.). The helically wrapped first wire 36 and second wire 38 are spaced sufficiently closely together to allow for spark formation between the insulation removed portions of the two wires. The space between the insulation removed portions defines a spark gap between the respective electrode pairs. Examples and further information on helically wound wire to create electrode pairs can be found in U.S. Pat. No. 9,993,292 and U.S. Publication No. 2018 / 0098779, which are incorporated herein by reference.

[0100] It should be noted that in the designs described above with reference to Figures 4A-4B, 5A-5C, and 6A-6B, the electrodes are positioned in the same plane (i.e., coplanar), thereby minimizing the diameter of the distal end of the catheter. Other suitable coplanar electrode designs are described in US 2017 / 0135709, which is incorporated herein by reference.

[0101] 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 shockwave catheter variations disclosed herein may include features described with any other shockwave catheter or combination of shockwave catheters herein. Furthermore, any of the methods may be used with any of the shockwave devices disclosed. Thus, it is not intended that the present invention be limited, except as by the appended claims.

Claims

1. 1. A catheter for treating an occlusion in a blood vessel, the catheter comprising: a tubular guidewire sheath defining a plurality of lumens, the plurality of lumens including a first lumen for carrying a guidewire; a shockwave generator located near a distal end of the catheter, the shockwave generator including at least one distal electrode pair, the electrodes of each pair being spaced apart to define at least one gap; a first wire and a second wire, a proximal end of the first wire and the second wire being connectable to a pulsed voltage source and a distal end of the first wire and the second wire being connected to the at least one distal electrode pair, whereby when a high voltage pulse is applied across the first wire and the second wire, an electrical current flows across the at least one gap creating shock waves to treat an obstruction; a flexible cap sealably attached to the distal end of the catheter; Equipped with the flexible cap surrounds the at least one distal electrode pair, the flexible cap being expandable with a conductive fluid, whereby the flexible cap expands and provides a space between an inner wall of the flexible cap and the at least one distal electrode pair; when the flexible cap is in a contracted state, the flexible cap has a contracted configuration, in which a surface area of ​​the flexible cap is sufficiently small so that the flexible cap does not collapse as the catheter is advanced into a blood vessel; the flexible cap is configured to increase in surface area from the surface area in the contracted state as the flexible cap is expanded with a conductive fluid; A catheter, wherein after the flexible cap is inflated with a conductive fluid, the catheter is then deflated, whereby the flexible cap returns to the deflated state configuration without the flexible cap collapsing.

2. The catheter of claim 1 , wherein when the flexible cap is in an expanded state, the diameter of the flexible cap is 10 to 15% larger than the diameter of the flexible cap in a contracted state.

3. The catheter of claim 1 , wherein the flexible cap comprises an angioplasty balloon.

4. The catheter of claim 1 , wherein the flexible cap comprises an extruded polymer tube.

5. The catheter of claim 1 , wherein the flexible cap is made from a material having elastomeric properties.

6. The at least one distal electrode pair comprises a first electrode pair and a second electrode pair, the first electrode pair comprising: a conductive portion of the first wire; a conductive sheath wrapped around the entire circumference of the tubular guidewire sheath; Equipped with The second electrode pair is the conductive sheath; a conductive portion of the second wire; The catheter of claim 1 , comprising:

7. 10. The catheter of claim 1, further comprising a third wire and a fourth wire extending within one or more lumens of the tubular guidewire sheath, proximal ends of the third wire and fourth wire being connectable to the pulsed voltage source and distal ends of the third wire and fourth wire being connected to at least one proximal electrode pair.

8. The at least one proximal electrode pair comprises a third electrode pair and a fourth electrode pair, the third electrode pair comprising: a stripped portion of the third wire; and a further conductive sheath wrapped around the entire circumference of said tubular guidewire sheath; Equipped with The fourth electrode pair is the further conductive sheath; and a stripped portion of the fourth wire; The catheter of claim 7 , comprising:

9. 8. The catheter of claim 7, wherein the pulsed voltage source is controllable to apply high voltage pulses across either the first and second wires or the third and fourth wires to create shock waves in either the at least one distal electrode pair or the at least one proximal electrode pair.

10. The catheter of claim 1 , wherein the tubular guidewire sheath defines one or more fluid lumens for carrying a conductive fluid between a proximal end of the catheter and a balloon.

11. 10. The catheter of claim 1, wherein at least a portion of the tubular guidewire sheath comprises spacing features protruding from an outer surface of the tubular guidewire sheath, the spacing features configured to maintain an inner wall of a balloon a controlled distance away from the outer surface of the tubular guidewire sheath.

12. The catheter of any one of claims 1 to 11, wherein when the flexible cap is in an expanded state, the maximum diameter of the flexible cap is no more than 15% greater than the diameter of the flexible cap in the contracted state.

13. 13. The catheter of any one of claims 1 to 12, wherein the catheter comprises a soft tip at a distal end of the catheter, the soft tip tapering such that the soft tip is narrower at the distal end of the soft tip.

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