Lesion Penetrating Shock Wave Catheter

Abstract

The present invention provides a catheter for treating vascular occlusions. The catheter includes at least one electrode pair (222, 243) positioned within a flexible angioplasty balloon (280) at the distal end (200) of the catheter. In some designs, the electrode pair is arranged in a low-profile or coplanar configuration, thereby reducing the diameter of the distal end of the device and allowing treatment of tight and difficult-to-cross occlusions. The flexible angioplasty balloon (280) has a very low profile and does require folding before insertion of the catheter into the cardiovascular system. During treatment, the balloon can be inflated a relatively small amount, an amount sufficient to immerse the electrode pair in a conductive fluid before generating a shock wave across the electrodes to treat the occlusion. The balloon can be made of a material having elastomeric properties such that when it deflates after treatment, it returns to its original low-profile configuration.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority of U.S. Provisional Patent Application No. 62 / 904,847, filed on September 24, 2019, entitled "LESION CROSSING CATHETER WITH LOW - PROFILE SHOCK WAVE GENERATOR", the content of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to catheter devices that can be used to cross calcified lesions. The catheter includes a distal shock wave generator configured to have a very low profile to allow advancement through a stenotic vasculature. Background Art

[0004] A variety of catheters have been developed to treat arterial diseases. For example, treatment systems for percutaneous coronary angioplasty or peripheral angioplasty use an angioplasty balloon to dilate a lesion (e.g., a calcified lesion) and restore normal blood flow in the artery. In these types of procedures, the catheter carrying the balloon is advanced along a guide wire into the vasculature until the balloon is aligned with the calcified plaque. Then the balloon is pressurized to reduce or disrupt the calcified plaque and push them back into the vessel wall. The balloon can have a smooth wall or be provided with a structure that physically scratches the damage in the vasculature. Other catheters, called atherectomy devices, have a rotating member for drilling out the lesion.

[0005] Recently, catheters have been developed that include one or more electrode pairs located within an angioplasty balloon. In these devices, the catheter is advanced on a guide wire in the patient's vasculature until it approaches the lesion. The balloon is inflated with a conductive fluid to contact the lesion, and then the shock wave generator is activated to generate shock waves that direct acoustic waves into the lesion. The shock wave device is particularly effective for treating calcified lesions because the acoustic waves can rupture the lesion without damaging the surrounding vasculature. Once the lesion is ruptured, the balloon can be further expanded in the vessel to create an improved blood flow lumen.

[0006] The shock wave generator is typically an electrode pair excited by applying a high - voltage pulse. Efforts have been made to reduce the size of the electrode pair to allow access to more compact and difficult - to - cross 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.

[0007] Although the low-profile designs discussed above have been deployed in both coronary and peripheral vascular applications, even these designs can have difficulty passing through partial or total occlusions in the vascular system. One way to address this problem is to use a wire having a shock wave generator at the distal end. In this case, the proximal and distal shaft portions of the catheter are reinforced to support advancement of the wire into the occlusion. One or more shock waves are generated to partially open the blockage. The wire can then be further advanced into the occlusion, where additional shock waves are generated. This sequence can be continued in order to move the wire through the occlusion and provide a passageway large enough such that a balloon catheter can now be inserted. An example of such a shock wave wire design can be found in U.S. Patent No. 9,730,715, which is incorporated herein by reference.

[0008] Although placing a shock wave electrode at the end of the wire results in a very low-profile structure, this approach has some disadvantages compared to low-profile designs that include an inflatable balloon. For example, the wire must have a soft tip that cannot easily be pushed through the blockage. Additionally, the wire design is monopolar, with one electrode located at the end of the wire and the second electrode defined by a pad attached to the patient's body. This means that the patient is part of the electrical circuit. Additionally, the wire design does not have a balloon at the tip. The advantage of a balloon is that it can protect tissue from direct contact with the plasma generated during shock wave production. The balloon also ensures that the conductive fluid surrounds the electrodes during shock wave production.

[0009] Accordingly, there is a need to provide a catheter design that has a lower profile than previous methods, that incorporates an angioplasty balloon, and that includes a bipolar circuit to generate shock waves within the balloon. SUMMARY OF THE INVENTION

[0010] The above object is achieved in a catheter for treating a vascular occlusion that has at least one electrode pair within a flexible angioplasty balloon at the distal end of the catheter. In some designs, the electrodes are coplanar, thereby reducing the diameter of the device. Additionally, a low-profile / thin balloon is used that does not require folding prior to insertion into the cardiovascular system. This balloon can be inflated a relatively small amount that is sufficient to immerse the electrodes in a conductive fluid prior to generating shock waves at the electrodes to treat the occlusion. The balloon can be made of a material having elastomeric properties such that it will return to its original low-profile configuration when it is deflated after treatment.

[0011] The present invention provides a catheter for treating vascular occlusion. An exemplary catheter for treating vascular occlusion includes: a tubular wire sheath that defines a first lumen for receiving a wire and a second lumen for carrying a first wire; a shock wave generator near the distal end of the catheter, the shock wave 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, the proximal end of the first wire being connectable to a pulsed voltage source and the distal end of the first wire being connected to the at least one pair of electrodes; a reinforcing sheath circumferentially wound around the wire sheath, wherein the proximal end of the reinforcing sheath is connectable to a pulsed voltage source and the distal end of the reinforcing wire sheath is connected to the at least one pair of electrodes such that when a high voltage pulse is applied across the reinforcing wire sheath and the first wire, current flows through the at least one gap, thereby generating a shock wave for treating the occlusion; and a cap sealably attached to the distal end of the catheter and surrounding the at least one pair of electrodes, the cap being fillable with a conductive fluid. The cap can be flexible and can expand to provide a space between the inner wall of the cap and the at least one pair of electrodes.

[0012] A second exemplary catheter for treating vascular occlusion includes: a tubular wire sheath defining a plurality of lumens, the plurality of lumens including a first lumen for carrying a wire; a shock wave generator near the distal end of the catheter, the shock wave generator including at least one distal pair of electrodes, the electrodes of each pair being spaced apart to define at least one gap; a first wire and a second wire, wherein the proximal ends of the first wire and the second wire are connectable to a pulsed voltage source and wherein the distal ends of the first wire and the second wire are connected to the at least one distal pair of electrodes such that when a high voltage pulse is applied across the first wire and the second wire, current flows through the at least one gap, thereby generating a shock wave for treating the occlusion; and a flexible cap sealably attached to the distal end of the catheter and surrounding the at least one pair of electrodes, the flexible cap being inflatable with a conductive fluid such that the cap expands to provide a space between the inner wall of the cap and the at least one pair of electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A is a diagram of a shock wave angioplasty catheter for treating vascular occlusion according to an embodiment of the present invention.

[0014] Figure 1B is a diagram of the distal end of a catheter having a low-profile non-foldable balloon in a deflated state according to some embodiments of the present invention.

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

[0016] Figure 1D is a diagram of a catheter of the present invention for treating a coronary total occlusion (CTO).

[0017] Figure 1E It is a diagram of the catheter of the present invention used in a blood vessel that is highly narrowed due to partial occlusion.

[0018] Figure 2A It is an exploded perspective view of the distal section of a catheter according to an embodiment of the present invention.

[0019] Figure 2B It is Figure 2A a side view of the distal end of a catheter that includes a first pair of electrodes and an uncollapsed balloon on the pair of electrodes.

[0020] Figure 2C It is a diagram of the Figure 2B embodiment rotated 180 degrees to show the second pair of electrodes.

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

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

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

[0024] Figure 2G It is Figure 2A a longitudinal cross-sectional view of a catheter showing the current flowing through the catheter.

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

[0026] Figure 3B It is Figure 3A a side view of the distal end of a catheter that includes a first distal pair of electrodes and a first proximal pair of electrodes and an uncollapsed balloon on the pair of electrodes.

[0027] Figure 3C It is a diagram of the Figure 3B embodiment rotated 180 degrees to show the second distal pair of electrodes and the second proximal pair of electrodes.

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

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

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

[0031] Figure 3G provides a cross-sectional view of a catheter that is being used to generate a shock wave at a proximal emitter. Figure 3A a cross-sectional view of a catheter.

[0032] Figure 3H provides a cross-sectional view of a catheter that is being used to generate a shock wave at a distal emitter. Figure 3G a vertical cross-sectional view of a catheter.

[0033] Figure 4A illustrates a top view of an annular electrode configuration in accordance with some embodiments of the present invention.

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

[0035] Figure 5A illustrates a top view of a tongue-and-groove electrode configuration in accordance with some embodiments of the present invention.

[0036] Figure 5B shows Figure 5A a side view of an embodiment.

[0037] Figure 5C shows an exploded view of an alternative tongue-and-groove electrode configuration arranged to produce two electrode pairs in accordance with some embodiments of the present invention.

[0038] Figure 6A illustrates a helical electrode configuration in accordance with some embodiments of the present invention.

[0039] Figure 6B illustrates Figure 6A a helical electrode configuration, showing only the helically coiled wire. DETAILED DESCRIPTION

[0040] The following description is presented to enable a person of ordinary skill in the art to make and use the various embodiments disclosed herein. The description of specific devices, techniques, and applications is provided only as an example. Various modifications to the examples described herein will be apparent to a person of ordinary skill in the art, and the general principles described herein may be applied to other examples and applications without departing from the spirit and scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described and shown herein, but are to be accorded a scope consistent with the claims.

[0041] The assignee of the present disclosure has developed a number of low-profile shockwave electrodes that are applicable to angioplasty and / or valvuloplasty procedures. For example, in U.S. Publication No. 2019 / 0150960, the assignee disclosed a low-profile electrode assembly in which the outer electrode is formed by a conductive sheath and the inner electrode is formed by removing a portion of an insulated wire (e.g., by creating a hole in the insulation near the end of the wire) to expose the conductive portion of the insulated wire. The inner electrode is positioned at a controlled distance from the side edge of the conductive sheath to allow for a reproducible arc to be generated at a given current and voltage.

[0042] Recently, the assignee has developed a number of coplanar electrode assemblies for shockwave catheters. These designs provide novel configurations of electrode pairs having, for example, helical structures and tongue-and-groove designs, where the corresponding electrodes are in the same transverse plane to limit the overall thickness of the electrode assembly. These assemblies are particularly advantageous for generating shockwaves in tight, difficult-to-access lesions or in a completely occluded vasculature. For example, in U.S. Patent No. 9,993,292 and U.S. Publication No. 2018 / 0098779, which are incorporated herein by reference, the assignee disclosed forming electrode pairs from helically wound wires to generate shockwaves at various gaps circumferentially positioned around a tubular structure. In U.S. Patent No. 10,555,744, which is also incorporated herein by reference, the assignee disclosed a tongue-and-groove electrode assembly in which the electrode pair is formed by a grooved cutout in a conductive sheath and a coplanar tongue-shaped protrusion extending into the grooved cutout.

[0043] Described herein are catheters incorporating low-profile design elements that allow for intravascular lithotripsy (IVL) treatment in more tight, difficult-to-cross calcified lesions and total coronary occlusions. The present invention is similar to existing IVL systems in that it can include an array of lithotripter emitters (e.g., electrode pairs) on the catheter that enters the patient's vasculature to deliver shockwaves 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 vasculature without being folded. When deflated, the surface area of the balloon is small enough such that the balloon does not need to be folded when advancing the catheter through the vessel. The low profile of the non-folded balloon advantageously allows the catheter to be advanced into tighter regions of the vasculature, such as partially or completely occluded regions. Once the balloon has been positioned, the elastic material properties of the low-profile balloon allow the balloon to be inflated with a conductive fluid to increase the profile of the balloon, i.e., to contact the occlusion and provide space within the balloon for the conductive fluid to submerge the electrodes.

[0044] In some embodiments, the catheters described herein include additional low-profile elements, such as coplanar electrodes, which further reduce the diameter of the distal end of the catheter. Additionally or alternatively, the catheter may provide electrical connection to the electrodes through a braided wire sheath wound circumferentially around the catheter shaft. The braided wire sheath provides improved kink resistance, twistability, and pushability to the catheter to more easily manipulate the device within a patient's vasculature. By reducing the number of wires or other conductors that must be carried elsewhere in the catheter, including at least one electrical connection incorporated into the braided wire sheath also improves the low-profile aspect of the device.

[0045] Figure 1A An exemplary catheter 10 for treating vascular occlusions according to one embodiment of the present invention is shown. The catheter 10 is advanced over a guide wire 20 carried within a guide wire sheath into an occlusion in a patient's vasculature, such as the stenotic lesion shown in FIG. 1. The distal end 14 of the catheter 10 includes a shock wave generator 16 that generates shock waves at a plurality of emitters, such as electrode pairs, to disrupt a calcified lesion. As used herein, a plurality of emitters includes an electrode pair having a first and a second electrode separated by a gap, and a shock wave forms at the gap when current flows through the gap between the electrodes of the pair (i.e., when a voltage is applied across the ends of the first and second electrodes). The electrode pairs are arranged in a low-profile configuration that reduces the diameter of the distal end 14 of the catheter 10 and allows treatment of tight, difficult-to-reach lesions. In some examples, the shock wave generator 16 includes one or more coplanar electrode pairs, or includes one or more electrodes that are at least partially recessed into the catheter 10.

[0046] A flexible cap 18 (e.g., a low-profile flexible angioplasty balloon) is sealably attached to the distal end 14 of the catheter 10, thereby forming an annular channel around the shaft 12 of the catheter. The flexible cap 18 surrounds the shock wave generator 16 such that the shock waves are generated within a closed system defined by the cap wall. The cap 18 is filled with a conductive fluid, such as saline. The conductive fluid allows the acoustic shock waves to propagate from the electrode pairs of the shock wave generator 16 through the wall of the cap 18 and then into the target lesion. In some embodiments, the conductive fluid may also contain an X-ray contrast agent to allow fluoroscopic visualization of the catheter 10 during use. In some embodiments, the cap is rigid rather than flexible.

[0047] Figure 1B-1C There is provided Figure 1AA more detailed view of the distal end 14 of catheter 10, which includes an exemplary non-folded angioplasty balloon forming a flexible cap 18 on a shock wave generator 16. The balloon 18 has a small enough diameter and surface area such that when advanced through a patient's vasculature, it does not need to fold like a conventional angioplasty balloon. The very low profile of the balloon 18 allows the distal end 14 of the catheter to access tight occlusion areas of the vasculature. In some examples, the diameter of the distal end 14 of the catheter in the region of the balloon 18 is one millimeter or less. To maintain its low profile shape, the balloon 18 is preferably formed of a material having elastomeric properties such that the balloon can be inflated during treatment of the occlusion and then return to the low profile state when deflated after treatment. In some examples, the flexible cap 18 is an extruded / extrusion-molded polymeric tube having the properties of a semi-compliant material such that the polymeric tube can be inflated and deflated similar to an angioplasty balloon. As used herein, the terms flexible cap and balloon are used interchangeably to describe the flexible annular structure surrounding the electrode pair and inflated with a conductive fluid during treatment.

[0048] Figure 1B An exemplary flexible balloon 18 is shown in a deflated state, for example, during balloon entry, advancement, and positioning in a blood vessel. When the balloon 18 is in the deflated state, the surface area of the balloon is small enough such that the balloon does not fold when the catheter 10 is advanced through the blood vessel. If the balloon 18 is manipulated through a patient's blood vessel within a guiding catheter or some other outer sheath (such as the tubular outer sheath of catheter 10), the surface area of the deflated balloon is small enough such that the balloon does not fold inside the guiding catheter or outer sheath. In such examples, the diameter of the balloon is less than the diameter of the guiding catheter or outer sheath.

[0049] Once the balloon 18 has been positioned in the patient's vasculature, additional conductive fluid can flow into the balloon to inflate the balloon and gently secure the outer surface of the balloon to the lesion site. Figure 1CShows the same balloon 18 in the inflated state. The balloon 18 is formed of a material having elastomeric properties such that the balloon can withstand an inflation pressure between approximately 1 atmosphere and approximately 6 atmospheres. The balloon 18 is configured to expand only slightly when inflated with a conductive fluid during treatment. For example, the maximum inflated diameter of the balloon 18 can be no more than 10%-15% larger than the original diameter of the balloon (i.e., the diameter of the balloon in the deflated state). The maximum diameter of the balloon in the inflated state can be determined by the material hardness 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 approximately 0.028 inches, and the inner diameter of the inflated balloon 18 is approximately 0.039 inches, thereby providing a space of approximately 0.011 inches between the guidewire sheath and the inner surface of the balloon. This space ensures that the electrode pair 16 is immersed in the conductive fluid during shock wave generation, and the inner surface of the balloon 18 is far enough from the electrode pair that the balloon material is not damaged by the shock wave. In some embodiments, the diameter of the inflated balloon 18 is one millimeter or less. Optionally, the outer surface of the balloon 18 includes a hydrophilic coating to facilitate contact between the balloon and the target lesion.

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

[0051] Return Figure 1A , 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 access port for receiving the 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 shock wave generator 16 and an external pulsed high voltage source 28 - such as Figure 1A the intravascular lithotripsy (IVL) generator shown.

[0052] Catheter 10 also includes a flexible shaft 12 that extends from the proximal handle 22 to the distal end 14 of the catheter. The shaft 12 provides various internal conduits that connect the components at the distal end 14 to the handle 22 of the catheter (see, for example, Figure 2E-2F and Figure 3E-3F(cross-section of an exemplary region of the shaft). The shaft 12 includes a guidewire sheath that includes a lumen for receiving the guidewire 20. The guidewire sheath also defines a plurality of additional lumens that longitudinally extend through the shaft 12. For example, one or more wire lumens may be included for carrying electrical wires that electrically connect the pulsed voltage source 28 to the electrodes of the distal shockwave generator 16. In some embodiments, one or more fluid lumens (e.g., a fluid inlet lumen and a fluid outlet lumen) are provided in the guidewire sheath for carrying the conductive fluid from the fluid port 26 to the cap 18. Optionally, the flexible shaft 12 includes a reinforcement wire sheath that is circumferentially wound around the guidewire sheath. The reinforcement wire sheath provides mechanical support for the flexible shaft 12 to facilitate twisting, pushing, and maneuvering of the catheter 10 through the patient's blood vessel. In some embodiments, the reinforcement wire sheath is also configured to conduct current such that the reinforcement wire sheath can 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 wires). In some embodiments, a tubular outer sheath covers the guidewire sheath and the reinforcement wire sheath to provide a barrier between the active components of the catheter 10 and the in-situ environment.

[0053] As Figure 1A shown, the catheter 10 can be used to treat occlusions in the vasculature, such as stenotic lesions, calcified portions of arteries, or some other occlusion in a blood vessel. In operation, a doctor advances the guidewire 20 from an entry site on the patient (e.g., an artery in the groin region of the leg) to a target region of the vasculature (e.g., a region having an occlusion that needs to be ruptured). The catheter 10 is then advanced over the guidewire 20 to the target region of the vasculature. In some examples, the flexible cap 18 sealed to the distal end 14 is a non-folded balloon with a low profile upon deflation such that the balloon does not need to be folded when the device is advanced through the vasculature. During the positioning phase of the treatment, a guiding catheter or outer sheath may be used to assist the catheter 10 in entering the vasculature and in maneuvering the catheter 10 within the vasculature. The outer sheath provides a tubular linear support for the catheter shaft 12 and maintains the deflated state of the flexible cap 18 during the pushing, threading, and placement of the catheter 10. The in-situ position of the distal end 14 of the catheter 10 can be determined by X-ray imaging and / or fluoroscopy.

[0054] The distal end 14 of the catheter 10 is advanced as far as possible within the tight lesion. Then, the flexible cap 18 is inflated by 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 such that the outer surface of the cap contacts the target lesion. The cap is inflated to an IVL pressure that is between approximately 1 atmosphere and approximately 6 atmospheres. The diameter of the flexible cap in the inflated state can be approximately 10 - 15% larger than the diameter of the flexible cap in the deflated state. However, in some examples, the diameter of the cap in the inflated state is even less than 10% larger than the diameter of the cap in the deflated state. Then, a voltage pulse is applied across the ends of one or more electrode pairs (i.e., the emitters of the shock wave generator 16) by the pulsed high voltage source 28. Each pulse initially ionizes the conductive fluid in the flexible cap 18 to generate small gas bubbles that insulate the electrodes around the shock wave generator 16. During treatment, fluid can flow continuously through the cap 18 at a constant rate to remove gas bubbles and debris from the electrodes. The fluid flow rate can be controlled throughout the treatment, but generally ranges from about 1 ml / min to about 3 ml / min. At some point, a plasma arc forms across the ends of the electrode pair, creating a low impedance path for the free flow of current. Heat from the plasma arc heats the conductive fluid, generating rapidly expanding vapor bubbles. The expansion of the vapor bubbles generates shock waves that are conducted through the fluid, through the wall of the flexible cap 18, and into the occlusion, where the energy destroys the hardened lesion.

[0055] To treat an occlusion in a blood vessel, the voltage pulse applied by the voltage pulse generator 28 is generally in the range of about 2000 volts to about 3000 volts, preferably between 2300 and 3000 volts. The pulse width of the applied voltage pulse is in the range between 2 microseconds and 6 microseconds. The repetition rate or frequency of the applied voltage pulse can be between about 1 Hz and about 10 Hz. However, the preferred voltage and repetition rate can vary depending on, for example, lesion size, degree of calcification, blood vessel size, patient attributes, or treatment stage. For example, a doctor can start with low energy shock waves and increase the energy as needed during the procedure. The amplitude of the shock wave can be controlled by controlling the voltage, current, duration, and repetition rate of the pulsed voltage from the pulsed voltage source 28. More information regarding the physical characteristics of shock wave generation and its 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 IVL treatment, one or more cycles of shock waves can be applied to create a more compliant blood vessel. For example, once the stenosis has been sufficiently softened by the shock waves of the first cycle, the flexible cap 18 can be deflated and the distal end 14 of the catheter 10 can be further advanced into the occlusion. The flexible cap 18 can then be reinflated and another cycle of shock waves can be applied. After completing successive cycles, an attempt can be made to further advance the cap 18.

[0057] The position and spacing of the electrode pairs can be controlled to provide a more effective shock wave treatment. For example, the electrode pairs of the shock wave generator 16 can be circumferentially spaced apart around the distal end 14 of the catheter 10 in consistent increments, such as 180 degrees apart or 90 degrees apart, to generate shock waves more uniformly around the catheter. In some embodiments, the shock wave generator 16 includes electrode pairs in multiple groups longitudinally spaced apart along the catheter 10 within the flexible cap 18. For example, the shock wave 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 a high voltage pulse at the proximal or distal electrode pair, for example, by applying a voltage pulse across different sets of wires or other conductors leading to the respective electrode pairs. During a first treatment phase (i.e., during the initial treatment of a tight or complete occlusion), only the distal electrode pair is activated to generate shock waves. After the tight lesion has been modified and the more proximal portion of the cap 18 is able to pass through the lesion, the cap is reinflated and more proximal electrode pairs are activated to generate more proximal shock waves.

[0058] The progress of the procedure can be monitored by X-ray and / or fluoroscopy. The shock wave cycles can be repeated until the occlusion has been cleared or until a channel has been formed in the lesion having a diameter sufficient to accommodate a second treatment device with a larger profile. For example, the enlarged channel can accommodate a different catheter having a more conventional angioplasty balloon or a shock wave source oriented differently. This type of catheter is described in the above-referenced U.S. Patent No. 8,747,416 and U.S. Publication No. 2019 / 0150960. Once the lesion has been sufficiently treated, the flexible cap 18 can be further inflated, then deflated, and the catheter 10 and guidewire 20 can be removed from the patient.

[0059] Figure 1DDepicts catheter 10 for treating total occlusions in blood vessels such as chronic total occlusions (CTOs) in coronary arteries. When treating a total occlusion, a guide wire is advanced at least partially into the stenotic lesion. The catheter is then advanced over the guide wire through the patient's vasculature 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 supplied to the electrode pair at the distal end of the catheter by a pulsed voltage source to generate a shock wave that disrupts or loosens the lesion. The guide wire and catheter can then be further advanced into the lesion, and the shock wave treatment can be repeated until the total occlusion is cleared or until the diameter of the blood vessel permits placement of a larger and more conventional angioplasty device.

[0060] Figure 1E Illustrates the use of catheter 10 of the present invention in a small blood vessel partially occluded by a stenotic lesion. In this situation, the guide wire can be advanced further into the lesion and, in some cases, all the way through the lesion. After positioning the guide wire, the catheter is advanced through the lesion in incremental stages. At each stage, the flexible cap is inflated and a shock wave is generated to disrupt the occlusion and increase the diameter of the blood vessel. As described above, once the diameter of the blood vessel is large enough, a catheter of larger diameter can be advanced through the blood vessel to complete the treatment.

[0061] Figure 2A-2G and Figure 3A-3H Provides a more detailed view of the distal end of a catheter that can be included in a shock wave angioplasty device - such as Figure 1A-1E and any of the catheters described herein.

[0062] Figure 2A Illustrates an exploded perspective view of the distal section of an exemplary catheter that includes two low-profile electrode pairs formed by a conductive sheath ("emission band", e.g., a toroidal electrode) circumferentially wound around a guide wire sheath ("multi-lumen inner member"). The electrode pairs are electrically connected to an external pulsed voltage source by wires (e.g., polyimide-insulated copper wire) and a conductive reinforcing wire sheath ("flat wire braid") circumferentially wound around the guide wire sheath. A cap (e.g., a low-profile angioplasty balloon or tubular polymer) is sealed to the distal end of the catheter covering the electrode pairs and a portion of the guide wire 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 helps the catheter enter and be positioned by providing circumferential protection and mechanical support for the device.

[0063] Figure 2B Depicts a first side view of the distal end 200 of an exemplary catheter, showing a first electrode pair in a point-circle configuration. Figure 2C Provides Figure 2BA second view of the distal end 200 of the catheter, which has been 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 Figure 2B-2C shown, the distal end 200 of the catheter includes a guidewire sheath 210, a shock wave generator including a first electrode pair and a second electrode pair, and a flexible cap 280 surrounding the electrode pairs. The flexible cap 280 circumferentially wraps around the guidewire sheath 210 and is sealed to the distal end 200 of the catheter, such as by adhesive sealing or heat bonding, to form a closed annular channel around a portion of the guidewire sheath 210. In some embodiments, the flexible cap 280 is a non-foldable angioplasty balloon (i.e., a low-profile angioplasty balloon) that can be positioned in a patient's vasculature without folding. When the balloon 280 is in a deflated state (see, e.g., Figure 1B ), the surface area of the balloon is small enough that the balloon does not fold when the catheter is advanced into a blood vessel. In some examples, the flexible cap 280 is an extruded tubular structure formed from a semi-compliant polymeric material (i.e., an extruded polymeric tube). The semi-compliant polymeric material allows the flexible cap 280 to slightly inflate in response to fluid pressure within the flexible cap and then return to its original size when not under pressure.

[0064] The flexible cap 280 can be inflated with a conductive fluid, such as saline, such that the cap expands to provide space between the inner wall of the cap and the electrode pair (see, e.g., Figure 1C ). In some embodiments, the flexible cap 280 inflates a relatively small amount such that the cap remains low-profile when in its inflated state (e.g., having a diameter of less than 1 millimeter). For example, the maximum inflated diameter of the flexible cap 280 can be no more than 10%-15% larger than the original diameter of the cap, such that the diameter of the flexible cap in the inflated state is 10-15% larger than the diameter of the cap in the deflated state. However, when inflated, the flexible cap 280 should provide sufficient space to allow the conductive fluid to surround and immerse the electrode pair, thereby avoiding damage to the cap during shock wave generation. When inflated, the conductive fluid allows acoustic shock waves from the electrode pair to propagate through the wall of the cap 280 and into a 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.

[0065] The conductive fluid enters the cap 280 via a fluid inlet 217 in the guidewire sheath 210 and is removed from the cap via a fluid outlet 219 in the guidewire sheath. The fluid inlet 217 and fluid outlet 219 provide channels from the surface of the guidewire sheath 210 to corresponding fluid inlet lumens 216 and fluid outlet lumens 218 in the guidewire sheath (and, more proximally, allow the cap to contact by Figure 1AThe fluid supplied by the fluid port shown). During treatment of an occlusion, the fluid can be continuously flushed through the flexible cap 280 via the inlet 217 and the outlet 219 to remove bubbles and debris generated when high-voltage pulses across the electrodes generate shock waves in the cap 280. The fluid inlet 217 and the fluid outlet 219 are positioned to maximize the fluid flow rate through the pair of electrodes such that the fluid flowing through the cap 280 via the inlet and outlet flows through at least one of the pair of electrodes. For example, as Figure 2B shown, the fluid inlet 217 and the fluid outlet 219 can be diagonally positioned on opposite sides of the conductive sheath 220 such that one or more of the pair of electrodes are positioned between the fluid inlet and the fluid outlet. Figure 2D Provided is an exploded perspective view of an IVL catheter embodiment having a fluid inlet and a fluid outlet positioned to allow fluid to flow through a pair of electrodes.

[0066] Returning to Figure 2B-2C , the guidewire sheath 210 provides various internal conduits that connect the components of the distal end 200 to the proximal end (not shown) of the catheter, including a guidewire lumen 211 for receiving a guidewire; a wire lumen 212 for carrying the insulated wire 242, and one or more fluid lumens 216, 218 for delivering fluid (e.g., conductive fluid) from the proximal end of the catheter to the cap 280. The internal structure of the guidewire sheath 210 is shown more clearly in Figure 2E-2F . Figure 2E Provided is Figure 2B-2C a cross-section of a more proximal section of the shaft of the catheter of Figure 2F Provided is a perspective view of a cross-section of the interior of the outer sheath of the catheter 200 Figure 2E .

[0067] As Figure 2E shown, the catheter includes a central tubular guidewire sheath 210 that defines a plurality of lumens. The plurality of lumens include a first lumen (i.e., the guidewire lumen 211) for receiving a guidewire and a second lumen (i.e., the wire lumen 212) for carrying the wire 242. The guidewire lumen 211 can extend through the center of the guidewire sheath 210 or can be slightly off-center, as Figure 2E shown. The guidewire lumen 211 is shaped to loosely receive a guidewire having a diameter between approximately 0.014 inches and approximately 0.035 inches. The wire lumen 212 is shaped to carry at least one wire 242 for supplying current from a pulsed voltage source (e.g., Figure 1Aflows to the electrode pair at the distal end 200 of the catheter from a pulsed voltage source). In some examples, the wire is a polyimide-insulated copper wire having a diameter between approximately 0.003 inches and approximately 0.007 inches. The wire can be flattened to reduce the profile of the catheter, and the flattened wire has a cross-section that is approximately 0.003 inches thick and approximately 0.010 inches wide. The plurality of lumens also includes a fluid inlet lumen 216 for fluid to flow into the cap 280 and a fluid outlet lumen 218 for fluid to flow out of the cap 280. Although the lumens are Figure 2E illustrated in as having an approximately circular cross-section, the lumens in the guidewire sheath 210 can have any desired shape. For example, the wire 242 can have a flattened shape and the second lumen 212 can have a flattened shape or an oval shape to accommodate the flattened wire. Similarly, the fluid inlet lumen 216 or the fluid outlet lumen 218 can be disposed around the circumference of the guidewire sheath (e.g., in the annular space between the sheath and the braided wire sheath 230). The position, size, and shape of any lumen can be modified to reduce the profile of the catheter or to provide some other benefit. Additionally, various lumens can be combined (e.g., by providing two or more insulated wires in the same lumen) or eliminated without departing from the scope of the present invention.

[0068] Surrounding the guidewire sheath 210 is a tubular braided wire sheath 230, which is formed of at least one electrically conductive braided wire material (e.g., braided, coiled, or both wires), such as braided copper or stainless steel. As previously referenced Figure 1A as described, the braided wire sheath 230 can be used to conduct current from a pulsed voltage source at the proximal end of the catheter to the distal end 200 of the catheter to provide current to one or more electrode pairs. The proximal end of the braided wire sheath 230 is capable of being connected to the pulsed voltage source, while the distal end of the braided wire sheath is connected to one or more of the electrode pairs. In some embodiments, the braided wire sheath 230 is connected to the electrode pair via a conductive metal sheet shaped to form an electrode (e.g., Figure 2C the conductive emitter portion 234 depicted in). In addition to providing current to the electrode pair at the distal end 200, the braided wire sheath 230 can also provide beneficial mechanical properties to the shaft of the catheter. For example, the material composition of the braided wire sheath 230 can provide increased torsional flexibility, pushability, or enhanced rigidity to the catheter shaft to facilitate maneuvering the catheter through a patient's vasculature. In some embodiments, the braided sheath 230 includes one or more braided or coiled metals (e.g., metal wires) at least partially encapsulated in a polymer. The polymer encapsulation insulates the conductive metal elements of the sheath 230 and / or provides improved mechanical properties. The braided metal of the sheath 230 can be flattened to reduce the profile of the sheath 230 and allow the catheter to be more easily assembled into a tightly occluded vasculature.

[0069] Returning to Figure 2B-2C, the distal end 200 of the catheter further includes a soft tip 290 that tapers towards the distal end of the catheter. The soft tip 290 can be formed of a polymer or any other suitable biocompatible material. In a preferred embodiment, the tip 290 is at least partially formed of 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 along the guidewire with the soft tip leading through the patient's vasculature. The provision of the soft tip 290 can prevent physical damage to the vessel wall while facilitating contact with and entry into tight lesions in the vasculature.

[0070] The distal end 200 also includes a shock wave generator of the catheter, the shock wave generator including Figure 2B the first electrode pair shown and Figure 2C the second electrode pair shown. The electrode pairs have a low-profile configuration (e.g., coplanar or at least partially recessed into the guidewire sheath 210) to reduce the diameter of the distal end 200. The first electrode pair and the second electrode pair are positioned circumferentially about 180 degrees apart around the guidewire sheath 210. The electrodes of each pair are spaced apart to define a gap in which current can flow to generate a shock wave in the electrically conductive fluid within the flexible cap 280.

[0071] The electrode pairs can be formed by the side edges of a conductive sheath (e.g., a toroidal electrode) and the conductive portion of a wire, as described in the 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 insulation of the insulated wire near the distal end of the wire to expose the conductive portion of the wire. The position, size, and shape of the removed portion can vary to control the position, direction, and / or amplitude of the shock wave. In some embodiments, the electrodes can be formed by cutting the end of the insulated wire to expose a conductive cross-section. In some embodiments, a flat wire is used instead of a round wire to further reduce the crossing profile of the electrode assembly.

[0072] Referring to Figure 2B , the first electrode pair includes a first electrode formed by a removed portion 243 of the insulation of a wire (e.g., wire 242) extending through the lumen 212 of the guidewire sheath 210. The first electrode pair also includes a second electrode formed by a cutout 222 in a conductive sheath 220 circumferentially wound around the guidewire sheath. The cutout 222 in the conductive sheath 220 is defined by an approximately circular hole in the conductive sheath. The position, size, and shape of the cutout 222 can vary to control the position, direction, and / or amplitude of the shock wave. In some examples, the conductive sheath 220 is at least partially recessed into the guidewire sheath 210 to reduce the profile of the electrode assembly and the diameter of the distal end 200 of the catheter.

[0073] The insulation material removal portion 243 of the wire 242 and the incision 222 of the conductive sheath 220 are spaced apart to define the gap between the first electrode and the second electrode of the first electrode pair. The spacing of the gap can be controlled to produce a reproducible arc in the conductive fluid between the electrodes. For a given voltage and current output from a pulse voltage source, the spacing of the electrodes can be modified to produce a shock wave with a desired amplitude. In order to allow the current flow between the insulation material removal portion 243 of the wire 242 in the inner cavity and the incision 222 of the outer conductive sheath 220, the guide wire sheath 210 includes a hole extending between the outer surface of the guide wire sheath and the wire inner cavity 212. The hole is located above the insulation material removal portion 243 of the wire 242 and below the incision 222, so that when a high voltage pulse is applied across the reinforcing wire sheath 230 and the wire 242, the current flows through the hole. The size of the hole can correspond to the size of the insulation material removal portion 243 of the wire 242, the size of the incision 222 in the conductive sheath 220, or some other desired size or shape.

[0074] Figure 2C Provided Figure 2B FIG. 2 is a cross-section of the distal end 200 of the catheter of FIG. 2 , which is rotated 180 degrees to show the second electrode pair of the shock wave generator. The second electrode pair includes a first electrode formed by an edge 224 of the conductive sheath 220 and a second electrode formed by a conductive emitter portion 234 coplanar with the conductive sheath 220. Figure 2C As shown, the first electrode and the second electrode of the second electrode pair are formed into a tongue-and-groove configuration. The edge 224 of the conductive sheath 220 is defined by a longitudinal cut on the side of the conductive sheath and forms a "groove". The "tongue" is formed by a conductive transmitter portion 234, which extends into the groove so that the tongue and the groove define a U-shaped gap between the transmitter portion 234 and the edge 224 of the conductive sheath 220. The shape of the gap can be controlled to produce a reproducible arc in the conductive fluid between the pair of electrodes and to produce a shock wave with a desired amplitude. The conductive sheath 220 and the transmitter 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 transmitter portion 234 additionally includes a PET heat shrink tubing. More information about the tongue-and-groove electrode configuration is included in the applicant's U.S. Patent No. 10,555,744, which is incorporated herein by reference.

[0075] like Figure 2C As shown, the transmitter portion 234 is coupled to the distal end of the reinforcing wire sheath 230, which electrically connects the second electrode pair to a pulse voltage source (not shown). However, in alternative embodiments, the transmitter portion 234 can be coupled to another wire, such as one extending along the catheter, which electrically connects the second electrode pair to the pulse voltage source. Figure 2B, the first electrode pair is electrically connected to a pulsed voltage source via a wire 242 extending within the lumen 212 of the guidewire sheath 210. The proximal end of the wire 242 can be connected to the pulsed voltage source, while the distal end of the wire 242 is connected to the first electrode pair (i.e., forms part of the first electrode pair or is otherwise electrically connected to the first electrode pair).

[0076] The wire 242 and the reinforcement wire sheath 230 complete the circuit between the electrode pair and the pulsed voltage source such that when a high voltage pulse is applied across the reinforcement wire sheath 230 and the wire 242, current flows through the gap between the electrodes of the first and second electrode pairs, thereby generating a shock wave for treating the occlusion. Figure 2G An exemplary current flowing through a catheter is shown, the catheter having a tongue-and-groove electrode pair and a point-circle electrode pair connected to a voltage source through a polyimide-insulated copper wire and a reinforcement wire sheath formed of a flat copper-clad stainless steel wire.

[0077] In operation, the doctor can simultaneously connect the wire 242 to the positive lead of the voltage pulse generator and connect the reinforcement 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 along the wire 242 through the first gap between the insulation removal portion 243 of the wire and the notch 222 in the conductive sheath 220, thereby forming a plasma arc that generates a shock wave at the first electrode pair. Then the current flows through the conductive sheath 220 and through the second gap between the edge 224 of the conductive sheath 220 and the conductive emitter portion 234, thereby forming another plasma arc that generates a shock wave at the second electrode pair. Then the current flows from the conductive emitter portion 234 to the reinforcement wire sheath 230 and along the reinforcement wire sheath to the negative lead or ground. Or (as Figure 2G shown), the doctor can connect the reinforcement wire sheath 230 (or a wire electrically connected to the reinforcement wire sheath) to the positive lead of the pulse generator and connect the wire 242 to the negative lead or ground, such that the current flows through the first and second electrode pairs in the opposite path.

[0078] Figure 3A-3H Alternative catheters that can be included in a shock wave angioplasty device are provided, for example Figure 1A-1E and a detailed view of the distal end of any of the catheters described in the text. Different from Figure 2A-2G , Figure 3A-3H the distal end 300 of the shock wave generator of the catheter of Figure 3A 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 3AAs shown, the distal emitter and the proximal emitter are formed by corresponding proximal conductive sheaths (e.g., proximal electrode rings) and distal conductive sheaths (e.g., distal electrode rings) that are circumferentially wound around the guide wire sheath. The distal emitter includes one or more distal electrode pairs, and 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 by a plurality of wires extending through the lumen of the guide wire sheath.

[0079] Figure 3B A first side of the distal end 300 of an exemplary catheter is depicted, showing a first distal electrode pair and a first proximal electrode pair. Figure 3C A Figure 3B second view of the distal end 300 of the catheter is provided, with the catheter rotated 180 degrees to show a second distal electrode pair and a second proximal electrode pair. As Figure 3B-3C shown, the distal end 300 of the catheter includes a guide wire sheath 310, a shock wave generator including two distal electrode pairs and two proximal electrode pairs, and a flexible cap 380 surrounding the electrode pairs. The flexible cap 380 is circumferentially wound around the guide wire sheath 310 and is sealed to the distal end 300 of the catheter using, for example, adhesive sealing or heat sealing to form a closed annular channel around the guide wire sheath 310. In some embodiments, the flexible cap 380 is a non-folded angioplasty balloon (i.e., a low-profile angioplasty balloon) that can be positioned in a patient's vasculature without folding. When the balloon 380 is in a deflated state (see, for example, Figure 1B ), the surface area of the balloon is small enough that the balloon does not fold when the catheter is advanced into a blood vessel. In some examples, the flexible cap 380 is an extruded tubular structure formed from a semi-compliant polymeric material (i.e., an extruded polymeric tube). The semi-compliant polymeric material allows the flexible cap 380 to expand slightly in response to fluid pressure within the flexible cap and then return to its original dimensions when not pressurized.

[0080] The flexible cap 380 can be inflated with a conductive fluid such as saline so that the cap expands to provide a space between the inner wall of the cap and the proximal and distal electrode pairs (see, for example, Figure 1C)。In some embodiments, the flexible cap 380 expands a relatively small amount such that the inflated cap remains low profile (e.g., having a diameter less than 1 millimeter). For example, the maximum inflated diameter of the flexible cap 380 can be no more than 10%-15% greater than the original (i.e., deflated) diameter of the cap. However, when inflated, the flexible cap 380 should provide sufficient space to allow the electrically conductive fluid to surround and immerse the electrode pair to avoid damaging the cap during shock wave generation. When inflated, the electrically conductive fluid allows acoustic shock waves from the proximal and distal electrode pairs to propagate through the wall of the flexible cap 380 and into the lesion in contact with the outer surface of the cap. In some embodiments, the electrically conductive fluid also contains an X-ray contrast agent to allow fluoroscopic visualization of the catheter during IVL treatment.

[0081] The electrically conductive fluid enters the cap 380 via the fluid inlet 317 in the guidewire sheath 310 and is removed from the cap via the fluid outlet 319 in the guidewire sheath. The fluid inlet 317 and fluid outlet 319 provide passageways extending from the surface of the guidewire sheath 310 to corresponding fluid inlet lumens 316 and fluid outlet lumens 318 within the guidewire sheath (and, more proximally, allow the flexible cap to contact the fluid supplied by the Figure 1A fluid port shown). When treating an occlusion, the fluid can be continuously flushed through the cap 380 via the inlet 317 and outlet 319 to remove bubbles and debris generated when high voltage pulses across the electrodes generate shock waves within the cap. The fluid inlet 317 and fluid outlet 319 are positioned to maximize the fluid flow rate across the electrode pair such that the fluid flowing through the cap 380 via the inlet and outlet flows past at least one of the electrode pairs. For example, as Figure 3A shown, the fluid inlet 317 and fluid outlet 319 can be diagonally positioned on either side of 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 the fluid outlet. Figure 3D A cross-sectional view of a distal section of an exemplary catheter is provided, depicting the flow of fluid through the lumen of the catheter and the flexible cap via the fluid inlet and fluid outlet in the guidewire sheath.

[0082] As Figure 3A-3D shown, the guidewire sheath 310 provides various internal conduits connecting the elements at the distal end of the catheter to the proximal end, including a guidewire lumen, a lumen for carrying electrical wires, and one or more fluid lumens. The internal structure of the guidewire sheath 310 is shown more clearly in Figure 3E , Figure 3E which provides a cross-section of a more proximal section of the shaft of the catheter. Figure 3F A perspective view of a cross-section of the interior of the flexible cap 380 of the catheter 300 is provided. Figure 3E

[0083] As Figure 3EAs shown, the catheter includes a central tubular guidewire sheath 310 that defines a plurality of lumens. The plurality of lumens includes a guidewire lumen 311 for receiving a guidewire. The guidewire lumen 311 may extend through the center of the guidewire sheath 310, as Figure 3E-3F shown, or may be slightly off-center. The guidewire lumen 311 is shaped to loosely receive a guidewire having a diameter between approximately 0.014 inches and approximately 0.035 inches. The guidewire sheath 310 also includes four wire lumens for carrying respective wires 342, 344, 346, 348 to conduct electrical current from a pulsed voltage source (e.g., Figure 1A the pulsed voltage source) to proximal and distal electrode pairs. In some examples, the wires 342, 344, 346, 348 are polyimide-insulated copper wires having a diameter between approximately 0.003 inches and approximately 0.007 inches. The wires 342, 344, 346, 348 may be flattened to reduce the profile of the catheter, and the flattened wires have a cross-section that is approximately 0.003 inches thick and approximately 0.010 inches wide. The plurality of lumens also includes a fluid inlet lumen 316 for fluid to flow into the cap 380 and a fluid outlet lumen 318 for fluid to flow out of the cap 380. Although the lumens are Figure 3E-3F illustrated as having an approximately circular cross-section, the lumens in 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 shape or an oval shape to accommodate the flattened wire. 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., in an annular space between the sheath and the reinforcing wire sheath 330). The position, size, and shape of any lumen may be modified to reduce the profile of the catheter or provide some other benefit. Additionally, various lumens may be combined (e.g., by providing two or more insulated wires in the same lumen) or eliminated without departing from the scope of the present invention.

[0084] As Figure 3E-3F shown, at least a portion of the guidewire sheath 310 includes spacer features 312 that project from the outer surface of the guidewire sheath. The spacer features 312 are configured to maintain a controlled distance between the inner surface of the cap 380 and the outer surface of the guidewire sheath 310, e.g., for the purpose of preventing damage to the cap from shock waves generated at the electrode pairs. In some embodiments, the spacer features 312 surround one or more of the conductive sheaths 320, 326, or extend between the respective proximal conductive sheath 320 and distal conductive sheath 326.

[0085] Returning to Figure 3B-3C, the distal end 300 of the catheter further includes a soft tip 390 that tapers towards the distal end of the catheter. The soft tip 390 can be formed of a polymer or any other suitable biocompatible material. In a preferred embodiment, the tip 390 is at least partially formed of 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 along the guidewire with the soft tip leading through the patient's vasculature. The provision of the soft tip 390 can prevent physical damage to the blood vessel wall while facilitating contact with and entry into tight lesions in the vasculature.

[0086] The distal end 300 also includes a shock wave generator of the catheter, which includes 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 shown in Figure 3C . The first and second distal electrodes are formed by respective conductive portions 343, 355 of the first wire 342 and the second wire 344 and the distal conductive sheath 326 (e.g., a distal annular electrode), while the first and second proximal electrode pairs are point - circle electrode pairs formed by the insulation - removed portions of the third wire 346 and the fourth wire 348 and the proximal conductive sheath 320. The electrode pairs have a low - profile configuration that reduces the diameter of the distal end 300. For example, the proximal conductive sheath 320 and / or the distal conductive sheath 326 can be at least partially recessed into the guidewire sheath 310 to reduce the diameter of the distal end 300 of the catheter.

[0087] As described above, the electrode pairs can be formed by the side edges of the conductive sheaths and a portion of the wires. This portion of the wire can be formed by removing the insulation layer near the distal end of the wire to expose the conductive portion of the wire. The position, size, and shape of the removed portion can be varied to control the position, direction, and / or amplitude of the shock wave. In some embodiments, the electrode can be formed by cutting the end of the insulated wire to expose the conductive cross - section. In some embodiments, flat wires are used instead of round wires to further reduce the crossing profile of the electrode assembly.

[0088] Referring to Figure 3B , the first distal electrode pair includes a first electrode formed by the conductive portion 343 of the first wire 342 that extends through the lumen of the guidewire sheath 310. The first distal electrode pair also includes a second electrode formed by the side edge 328 of the distal conductive sheath 326 that circumferentially wraps around the guidewire sheath 310. Referring to Figure 3C, the second distal electrode pair includes a first electrode formed by a side edge 328 of the distal conductive sheath 326. The second distal electrode pair further includes a second electrode formed by a conductive portion 345 of a second wire 344 that extends through the lumen of the wire sheath 310. The first distal electrode pair and the second distal electrode pair are circumferentially spaced apart by approximately 180 degrees around the distal conductive sheath 326.

[0089] 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 electrodes of the first distal pair. 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 electrodes of the second distal pair. The spacing of the gaps can be controlled to create a reproducible electric arc in the conductive fluid between the electrodes of the respective pairs and to generate a shock wave with a desired amplitude 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 wire sheath 310 includes distal holes that extend between the outer surface of the wire sheath 310 and the lumen containing the first wire 342 and the second wire 344. These holes 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 current flows through the respective holes when a high voltage pulse is applied across the first wire 342 and the second wire 344.

[0090] Return Figure 3B , the first proximal electrode pair includes a first electrode formed by a portion 347 of the insulating material removed from a third wire 346 that extends through the lumen of the wire sheath 310. The first proximal electrode pair further includes a second electrode formed by a first cut 322 in the proximal conductive sheath 320. Refer to Figure 3C , the second proximal electrode pair includes a first electrode formed by a portion 349 of the insulating material removed from a fourth wire 348 that extends through the lumen of the wire sheath 310. The second proximal electrode pair further includes a second electrode formed by a second cut 324 in the proximal conductive sheath 320. The first proximal electrode pair and the second proximal electrode pair are positioned circumferentially spaced apart by approximately 180 degrees around the proximal conductive sheath 320.

[0091] The insulation removal portion 347 of the third wire 346 is spaced from the first incision 322 of the proximal conductive sheath 320 to define a first gap between the first pair of proximal electrodes. Similarly, the insulation removal portion 349 of the fourth wire 348 is spaced from the second incision 324 of the proximal conductive sheath 320 to define a second gap between the second pair of proximal electrodes. The spacing of the gaps can be controlled to produce a reproducible arc in the conductive fluid between the respective pairs of electrodes and to generate a shock wave with a desired amplitude for a given voltage and current output from the pulsed voltage source. To allow current to flow between the insulation removal portions 347, 349 of the wires 346, 348 in the inner lumen and the outer incisions 322, 324 in the proximal conductive sheath 320, the guidewire sheath 310 includes proximal holes extending between the outer surface of the guidewire sheath 310 and the inner lumen containing the third wire 346 and the fourth wire 348. These holes are positioned between the insulation removal portions 347, 349 of the wires 346, 348 and the incisions 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 holes.

[0092] As Figure 3B-3C shown, the distal ends of the first wire 342 and the second wire 344 are connected to the distal electrode pair (i.e., form part of or are electrically connected thereto), while the proximal ends of the first wire 342 and the second wire 344 (not shown) may be connected to a pulsed voltage source such that when a high voltage pulse is applied across the first wire 342 and the second wire 344, current flows through the first gap and the second gap, thereby generating a shock wave for treating an occlusion near the distal electrodes. 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 may be connected to a pulsed voltage source such that when a high voltage pulse is applied across the third wire 346 and the fourth wire 348, current flows through the first gap and the second gap, thereby generating a shock wave for treating an occlusion near the proximal electrodes.

[0093] In operation, a doctor may want to independently control the distal electrode pair and the proximal electrode pair to selectively generate shock waves at different portions of the cap 380. Figure 3G Illustrated is the selective excitation of the proximal emitter by applying current to the proximal emitter wire. Figure 3H Illustrated is the selective excitation of the distal emitter by applying current to the distal emitter wire. The separate wiring of the proximal and distal electrode pairs advantageously allows the generation of 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 pulsed voltage source can be controlled to apply a high voltage pulse across the first wire 342 and the second wire 344 to generate a shock wave at the distal electrode pair, or across the third wire 346 and the fourth wire 348 to generate a shock wave at the proximal electrode pair.

[0094] It should be noted that Figure 2A-2G and Figure 3A-3H the elements and features of the exemplary catheter shown in can be rearranged, recombined, and modified without departing from the present invention. For example, although Figure 2A-2G a catheter including a braided wire sheath is provided, the braided wire sheath can be replaced by one or more wires, as shown in the catheter of Figure 3A-3H . Correlatively, Figure 3A-3H one or more wires in can be replaced by a braided wire sheath. Similarly, Figure 3A-3H the features of the embodiments of, such as spacer features, another proximal conductive sheath, additional electrode pairs, and / or independently controlled distal and proximal electrode pairs, can be combined with the catheter of Figure 2A-2G without departing from the present invention.

[0095] In addition, although Figure 2A-2G and 3A-3H illustrate two examples of shock wave generators, the present invention is intended to include catheters having a variety of electrode configurations. For example, the shock wave generator of the exemplary catheter can include two tongue-groove electrode pairs (see Figure 2B and 5A -5C), two point-circle electrode pairs (see the proximal electrode pair of Figure 2C and Figure 3B-3C ), or two electrode pairs formed by the distal conductive portion of a wire and a conductive sheath (see, for example, the distal electrode pair of Figure 3B-3C ), or any other desired configuration. In addition, the placement and spacing of the electrode pairs can be modified without departing from the present invention. For example, the electrode pairs can be circumferentially spaced apart around the catheter in consistent increments, such as 180 degrees apart, 90 degrees apart, or 60 degrees apart, to generate shock waves more uniformly around the catheter. In some examples, such as in the embodiment shown in Figure 3A-3H , the shock wave generator includes electrode pairs positioned in respective groups longitudinally spaced apart along the catheter. For example, the shock wave generator can include a plurality of electrode pairs defined by a plurality of conductive sheaths longitudinally spaced apart along the catheter.

[0096] Figure 4A-4B , 5A-5C and 6A-6B depict several exemplary shock wave electrode assemblies that can be included in a shock wave angioplasty device, such as in any catheter shown and described herein in Figure 1A-1C , 2A-2G and 3A-3H.

[0097] Figure 4A and 4BShows an exemplary variant of the electrode pair. This embodiment includes a pair of spaced-apart annular electrodes that are provided as a first conductive sheath 52b and a second conductive sheath 58c that are circumferentially wound around the shaft of the catheter. One or more of the sheaths 58c, 52b may be recessed into the shaft to reduce the diameter of the shock wave generator and allow the catheter to enter tighter lesions. In this example, the electrode pair is formed by 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 the spark gap 64 between the electrodes. Figure 4B Illustrates Figure 4A different views of the electrodes, where the gap 64 is shown larger for clarity. The first line "A" 36 is connected to the first conductive sheath 52b, and the second line "B" is connected to the annular electrode 58c. When a high voltage pulse is applied across the first line "A" 36 and the second line "B", a plasma arc is generated across the spark gap 64 between the annular electrodes. The plasma arc generates shock waves for treating occlusions.

[0098] Figure 5A , 5B and 5C illustrate an exemplary tongue-and-groove electrode pair configuration formed by a conductive sheath (e.g., an annular electrode) and a conductive emitter portion extending into the conductive sheath. In these examples, the first electrode of the pair is formed by the edge of the conductive sheath that is defined by a groove cut into the side of the conductive sheath. The second electrode of the pair is formed by a conductive tongue-shaped emitter portion that extends into the groove. The conductive emitter portion "tongue" may be formed by a conductive portion of a wire (e.g., a portion of the wire where the insulation has been removed or the conductive end) or some other conductive metal portion shaped to fit within the groove. The tongue and the groove define a U-shaped spark gap between the electrodes of the pair. As Figure 5B shown, the first line 36 is connected to the conductive emitter portion "tongue" 52, and the second line 38 is connected to the annular electrode conductive sheath 58. When a high voltage pulse is applied across the first line 36 and the second line 38, a plasma arc is generated across the spark gap 64 between the tongue 52 and the groove 60. The plasma arc generates shock waves for treating stenoses.

[0099] Figure 5C Illustrates a related exemplary tongue-and-groove electrode embodiment that provides two electrode pairs formed by a single conductive sheath 58a (e.g., a single annular electrode) that is circumferentially wound around a guide wire sheath. As Figure 5CAs shown, the first groove 60a and the second groove 60b are cut into the edge of the same conductive sheath 58a. The first and second grooves may be positioned circumferentially spaced 180 degrees around the conductive sheath. Corresponding conductive tongue-shaped emitter portions extend into the first and second grooves to form the first and second electrode pairs. The first electrode pair is formed by 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 by 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 respective tongues and grooves of the first and second electrode pairs. In such an example, the first wire 38 is connected to the first emitter portion "tongue" 68, while the second wire 36 is connected to the second emitter portion "tongue" 52. When a high voltage pulse is applied across the first wire 38 and the second wire 36, current flows through the first wire 38 and jumps across the first U-shaped gap, thereby generating a first plasma arc. The current then flows along the conductive sheath 58a and jumps across the second U-shaped gap, thereby generating a second plasma arc, and then flows back to the voltage source along the second wire 36. The first and second plasma arcs generate shock waves at two locations around the guide wire sheath, thereby providing a more complete circumferential treatment for lesions in the vasculature. More information and examples of the tongue-groove electrode configuration can be found in U.S. Patent No. 10,555,744, which is incorporated herein by reference.

[0100] Figure 6A and 6B FIG. illustrates another variant of the electrode pair of the present invention. In this case, the first wire 36 and the second wire 38 are helically wound around the shaft of the catheter. One or more electrode pairs are created by selectively removing the insulation from the wires to define the electrodes. For example, the first electrode pair includes a first insulation removal portion of the first wire 36 and a first insulation removal portion of the second wire 38. Additional electrode pairs may be created by removing additional insulation portions from the wires (i.e., such that the second electrode pair includes a second insulation removal portion of the first wire and a second insulation removal portion of the second wire, etc.). The helically wound first wire 36 and second wire 38 are spaced close enough to allow a spark to form between the insulation removal portions of the two wires. The space between the insulation removal portions defines the spark gap between the respective electrode pairs. Examples and more information on helically wound wires for creating electrode pairs can be found in U.S. Patent No. 9,993,292 and U.S. Publication No. 2018 / 0098779, which are incorporated herein by reference.

[0101] It should be noted that in the above reference Figure 4A-4B, in the designs described in 5A-5C and 6A-6B, the electrodes are arranged 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 U.S. 2017 / 0135709, which is incorporated herein by reference.

[0102] It should be understood that the above is only an illustration of the principles of the present invention, and those skilled in the art can make various modifications, changes, and combinations without departing from the scope and spirit of the present invention. Any variations of the various shock wave catheters disclosed herein may include features described by any other shock wave catheter or combination of shock wave catheters herein. In addition, any method can be used with any of the disclosed shock wave devices. Therefore, the present invention is not intended to be limited except as limited by the appended claims.

Claims

1. A catheter for treating vascular occlusion, comprising: a tubular guidewire sheath defining a plurality of lumens, the plurality of lumens including a first lumen for carrying a guidewire; a shock wave generator near the distal end of the catheter, the shock wave generator including at least one distal electrode pair, wherein the electrodes of each pair are spaced apart to define at least one gap; a first wire and a second wire, wherein the proximal ends of the first wire and the second wire can be connected to a pulsed voltage source, and wherein the distal ends of the first wire and the second wire are connected to the at least one distal electrode pair such that when a high voltage pulse is applied across the first wire and the second wire, current flows through the at least one gap, thereby generating a shock wave for treating occlusion; and a flexible cap formed of a material having elastomeric properties and 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 flexible cap expands to provide a space between the inner wall of the flexible cap and the at least one electrode pair, wherein when the flexible cap is in a deflated state, the surface area of the flexible cap is small enough such that the flexible cap does not fold when the catheter is advanced into a blood vessel, when the flexible cap is in an inflated state, the maximum diameter of the flexible cap is not more than 15% larger than the diameter of the flexible cap in the deflated state, and after being deflated, the flexible cap returns to a low-profile configuration such that the flexible cap does not fold when the catheter is removed from the blood vessel.

2. The catheter according to claim 1, wherein, the flexible cap includes an angioplasty balloon.

3. The catheter according to claim 1, wherein, the flexible cap includes an extruded polymer tube.

4. The catheter according to claim 1, wherein, the at least one distal electrode pair includes a first electrode pair and a second electrode pair, wherein the first electrode pair includes: a conductive portion of the first wire; and a conductive sheath circumferentially wound around the guidewire sheath; and wherein the second electrode pair includes: the conductive sheath; and a conductive portion of the second wire.

5. The catheter according to claim 1, further comprising a third wire and a fourth wire extending within one or more lumens of the tubular guidewire sheath, wherein the proximal ends of the third wire and the fourth wire can be connected to the pulsed voltage source, and wherein the distal ends of the third wire and the fourth wire are connected to at least one proximal electrode pair.

6. The catheter according to claim 5, wherein, the at least one proximal electrode pair includes a third electrode pair and a fourth electrode pair, wherein the third electrode pair includes: a portion of the third wire with insulation removed; and another conductive sheath circumferentially wound around the guidewire sheath; and wherein the fourth electrode pair includes: the another conductive sheath; and a portion of the fourth wire with insulation removed.

7. The catheter according to claim 5, wherein, The pulsed voltage source is controllable to apply a high voltage pulse across the first and second lines or the third and fourth lines to generate a shock wave at the at least one distal electrode pair or the at least one proximal electrode pair.

8. The catheter according to claim 1, wherein, the tubular wire sheath defines one or more fluid lumens for conveying an electrically conductive fluid between the proximal end of the catheter and the flexible cap.

9. The catheter according to claim 1, wherein, at least a portion of the tubular wire sheath includes spaced features protruding from the outer surface of the wire sheath, the spaced features being configured to maintain a controlled distance between the inner wall of the flexible cap and the outer surface of the wire sheath.

10. The catheter according to claim 1, wherein, when the flexible cap is in the inflated state, the maximum diameter of the flexible cap is no more than 10% larger than the diameter of the flexible cap in the deflated state.

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