System for treating occlusions in body lumens

Abstract

The present invention provides a system for treating an occlusion in a body lumen. The system may include an insulating outer sheath; an elongated conductive tube, wherein the insulating outer sheath is circumferentially mounted around the elongated conductive tube; and an insulating guidewire having a helical coil portion at its distal end. The coil portion includes an exposed distal end, and the distal portion of the elongated conductive tube is circumferentially mounted around the distal coil portion of the insulating guidewire. When a voltage is applied between the insulating guidewire and the elongated conductive tube, the current is configured to flow from the exposed distal end of the insulating guidewire to the elongated conductive tube to generate a plurality of cavitation bubbles. In an alternative embodiment, an elongated central electrode is used instead of the conductive tube.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Patent Application No. 62 / 688,110, filed on June 21, 2018, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to a system for treating occlusions in body lumens. The system is useful for chronic total coronary occlusion ("CTO"), partial coronary occlusion, or kidney stones in the ureter to restore normal flow in a lumen (e.g., an artery or ureter). Background Art

[0004] In an angioplasty or peripheral angioplasty procedure, an angioplasty balloon is used to dilate lesions (e.g., calcified lesions) and restore normal blood flow in an artery. In some examples, an angioplasty balloon is advanced into the vasculature (e.g., over a guidewire) until the balloon is aligned with the calcified plaque. The balloon is then pressurized with a fluid, thereby dilating the blood vessel to allow blood flow.

[0005] Recently, a system has been developed in which electrodes are placed in an angioplasty balloon. When the balloon is initially positioned near the obstruction, a series of high voltage pulses are applied to the electrodes to generate a series of shock waves. The shock waves rupture the calcified lesions. When the lesions rupture, the balloon can be inflated in a more gentle manner, thereby dilating the blood vessels and improving circulation.

[0006] More information about the latter type of device can be found in U.S. Patents 8,856,371, 8,747,416, and 9,642,673. Shockwave technology has also been developed to treat heart valves (US2018 / 0098779) and guidewire designs (US9,730,715). U.S. Patent Publication 2018 / 03640482 describes a forward shockwave device. Each of these patent documents is incorporated herein by reference.

[0007] Arteries are sometimes completely or partially occluded by, for example, thrombi, plaques, fibrous plaques, and / or calcium deposits. When this occurs, the physician must first traverse the occlusion and then deliver an angioplasty balloon and / or other tools downstream along the artery to the desired blockage location to perform the desired procedure. However, in some cases (e.g., CTOs), the occlusion is so tight and solid that it is difficult to get the treatment device into the true lumen of the distal vessel.

[0008] CTOs remain a challenge in percutaneous coronary interventions, as well as a challenge to the periphery, leading to severe limb ischemia and amputations. First, many currently available devices are unable to physically penetrate the tough proximal or distal caps of a CTO (retrograde approach). In some cases, attempts to pierce the CTO cap using a soft guidewire can result in bending (e.g., deflecting the guidewire to a subintimal channel or side branch). On the other hand, a stiffer guidewire may damage the arterial wall when forced against the CTO. In addition, some currently available devices destroy the CTO by generating strong mechanical vibrations, but the intensity of the vibrations may damage the arterial wall and make the system less durable and more difficult to control.

[0009] Similar problems exist with occlusions that form in other parts of the body, such as kidney stones in the ureters. Summary of the invention

[0010] The present invention provides a system for treating an occlusion such as a CTO or kidney stone in a lumen such as a blood vessel or ureter. In some embodiments, the system includes an insulating outer sheath, an elongated conductive tube, and an insulating guide wire, wherein the insulating outer sheath is circumferentially mounted around the elongated conductive tube, and the insulating guide wire has a spiral coil portion at its distal end. The coil portion includes an exposed distal end. The distal portion of the elongated conductive tube is circumferentially mounted around the distal coil portion of the insulating guide wire. When a voltage is applied between the insulating guide wire and the elongated conductive tube, the current is configured to flow from the exposed distal end of the insulating guide wire to the elongated conductive tube to ionize the fluid around it and generate multiple cavitation bubbles and dynamic characteristics associated with the bubbles (collapse, ejection, etc.).

[0011] In some embodiments, a method for treating an occlusion in a lumen such as a blood vessel or ureter includes advancing a treatment device in the lumen to contact the occlusion. The treatment device includes: an insulating outer sheath; an elongated conductive tube, wherein the insulating outer sheath is circumferentially mounted around the elongated conductive tube; and an insulating guidewire having a helical coil portion at its distal end, wherein the coil portion includes an exposed distal end, and the distal portion of the elongated conductive tube is circumferentially mounted around the distal coil portion of the insulating guidewire. The method also includes injecting a conductive fluid (i.e., saline, a mixture of saline and vascular contrast agent, etc.) into the distal end of the treatment device; and applying a voltage between the insulating guidewire and the elongated conductive tube to cause a current to flow from the exposed distal end of the insulating guidewire to the elongated conductive tube, thereby generating a plurality of cavitation bubbles and dynamic characteristics associated with the bubbles (collapse, ejection, etc.).

[0012] In some embodiments, a system for treating an occlusion in a body lumen is disclosed. The system includes an insulated guidewire having a spiral coil portion near its distal end, and a portion of the insulation of the distal end of the insulated guidewire is removed to define an electrode. The system also includes an elongated central electrode, the distal end of which is housed in the spiral coil portion of the insulated guidewire. In a preferred embodiment, the system also includes an insulating tube located around the distal end of the central electrode and in the spiral coil portion of the insulated guidewire. Finally, a tubular housing is provided for covering the coil portion of the insulated guidewire. The proximal ends of the insulated guidewire and the central electrode can be connected to terminals of an electrical pulse generator, so that in use, when a voltage pulse is applied to the central electrode and the insulated guidewire, a series of cavitation bubbles are generated between the insulated guidewire and the central electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a perspective view of an exemplary system for treating occlusions, according to some embodiments.

[0014] Figure 2A is an enlarged view of an exemplary bubble generating tip of a therapeutic system according to some embodiments.

[0015] Figure 2B is a cross-sectional view of an exemplary bubble generating tip of a therapeutic system according to some embodiments.

[0016] Figure 2C is a cross-sectional view of an exemplary bubble generating tip of a therapeutic system according to some embodiments.

[0017] Figure 3 is a perspective view of another exemplary bubble generating tip of a therapeutic system according to some embodiments.

[0018] Figure 4 is a side view of an exemplary system for treating an occlusion, according to some embodiments.

[0019] Figure 5 is a schematic diagram of an exemplary system for treating occlusions, according to some embodiments.

[0020] Figure 6 is a schematic diagram of another exemplary system for treating occlusion, according to some embodiments.

[0021] Figure 7 is an enlarged view of another exemplary system for treating occlusion, according to some embodiments.

[0022] Figure 8 yes Figure 7 perspective of the system.

[0023] Fig. 9A yes Figure 7 End view of the system.

[0024] Fig. 9B yes Figure 7 A cross-sectional view of the system.

[0025] Fig.10 is a perspective view of another exemplary bubble generating tip system according to some embodiments. DETAILED DESCRIPTION

[0026] The following description sets forth exemplary methods, parameters, etc. However, it should be appreciated that such description is not intended to limit the scope of the present disclosure, but is intended to describe exemplary embodiments.

[0027] Described herein are exemplary systems and methods for treating occlusions such as CTOs or kidney stones in the ureters. According to some embodiments, the treatment system includes a forward bubble generating tip that advances within the lumen to contact the occlusion. The forward bubble generating tip includes an electrode that forms a plasma arc, which in turn causes cavitation bubbles, when provided with a generator with a lower voltage and a higher PRF (pulse repetition frequency). The cavitation bubbles generate mechanical vibrations, turbulence, jets, and / or forceful collapses to destroy the occlusion. The output of the generator is configured to be sufficient to generate electrohydraulic discharges and cavitation bubbles to effectively drill holes, but not sufficient to generate powerful shock waves to compromise the durability of the system. In this way, mechanical vibrations are less than those of currently available devices. Therefore, the treatment system is less likely to cause damage to the lumen wall (e.g., the vessel wall), and is easier to control and more durable.

[0028] Figure 1 1 is a perspective view of an exemplary treatment system 100 according to some embodiments. The treatment system includes a forward bubble generating tip 102 (shown in an enlarged view), an insulating outer sheath 104, a proximal balloon 106 mounted on a length of the insulating outer sheath, a waste conduit 108, and insulating guidewires 110 and 112. The forward bubble generating tip 102 includes an electrode, and reference Figure 2A -C is described in detail. In operation, a conductive fluid such as saline (or saline contrast mixture) is injected from the proximal opening of the insulating outer sheath 104 and flows to the distal end. When the proximal ends of the insulating guide wires 110 and 112 are connected to a voltage source, cavitation bubbles and / or shock waves are generated via the conductive fluid at the forward bubble generation end. The cavitation bubbles and / or shock waves cause continuous mechanical vibrations along the front, thereby breaking up occlusions such as CTOs or kidney stones. When more conductive fluid is injected, debris such as broken occlusion blocks, metals, and bubbles are rushed toward the proximal balloon and taken out of the lumen via the waste conduit 108.

[0029] Figure 2A Shows Figure 11 is an enlarged view of the forward bubble generation end 102. As shown, the forward bubble generation end 102 includes an elongated conductive tube 208, a spiral coil portion 202 at the distal end of the insulating guide wire 112, and an optional insulating layer 206 arranged between the elongated conductive tube 208 and the spiral coil portion 202. In the example shown, the insulating layer 206 includes a plurality of holes 204 arranged along the longitudinal axis. In some examples, the elongated conductive tube 208 can be a stainless steel hypotube. The insulating guide wires 110 and 112 can be polyimide insulated copper guide wires. The insulating layer 206 can be a polyimide tubular insulator. The insulating layer provides an additional insulating layer between the conductive core of the guide wire 112 and the elongated conductive tube 208, and is useful in the case where the insulation around the coil portion 202 is defective and / or damaged (e.g., scratched during assembly). In some examples, the forward bubble generation end 102 does not include the insulating layer 206. In some examples, epoxy or cyanoacrylate glue may be used between the coil portion 202 and the elongated conductive tube 208 to fix the relative position of the two.

[0030] Figure 2B A cross-sectional view of the forward bubble generation end 102 is shown. As shown, the insulating outer sheath 104 is circumferentially mounted on the elongated conductive tube 208. In the example shown, the distal edge of the elongated conductive tube 208 extends beyond the distal edge of the insulating outer sheath 104 by a distance A. The distance A can be adjusted based on the characteristics of the occlusion. For example, the distance A can be set to be longer than the thickness of the calcified cap of the CTO to be drilled through. If this is not the case, it will be necessary to undesirably increase the penetration profile (i.e., a larger hole needs to be drilled to accommodate the insulating outer sheath). In some examples, the distance A is in the range of 0.004″ to 0.01″. As further shown, the insulating layer 206 is arranged between the elongated conductive tube 208 and the helical coil portion 202 with a longitudinal length L. The distal end of the insulating guidewire 110 is welded to the elongated conductive tube 208.

[0031] As shown, the distal edge of the insulating layer 206 is aligned with the distal edge of the elongated conductive tube 208. In addition, the distal edge of the elongated conductive tube 208 extends beyond the helical coil portion 202 by a distance B. In some examples, the distance B is in the range of 0 mm (i.e., the distal end of the coil portion is aligned with the distal edge of the elongated tube) to 0.5 mm. In some examples, when the distance B is set to achieve the best configuration, one or more other factors affecting the operating efficiency are considered, such as the flow rate of the conductive fluid, the applied voltage, the shape and composition of the occlusion. This relative positioning of the distal edge of the helical coil portion 202 and the elongated conductive tube 208 and the insulating layer 206 ensures safety to the surrounding tissues, protects the catheter from the vibration emitted from the end, and makes mechanical vibrations along the front, thereby increasing the strength and effectiveness of the treatment system in destroying the occlusion. In addition, the mechanical vibrations along the front and the continuous flow rate along the front lead to drilling (e.g., size, shape) consistent holes, thereby making the treatment system easier to operate. In some examples, the treatment system is configured to drill a hole having a diameter of approximately 1 mm in the calcified material.

[0032] In some examples, the flow rate of saline or saline / angiographic contrast mixture is adjusted to avoid overheating issues and control the efficiency and rate of drilling. In some examples, the flow rate is configured to be in the range of 1 to 30 mL / min to increase the fragility of calcified structures.

[0033] In an exemplary operation, when the proximal ends of the insulating wires 110 and 112 are connected to the negative and positive ports of the generator, respectively, an electric current flows from the distal end 210 of the insulating wire 112 to the elongated conductive tube 208. The electric current can cause a plurality of plasma arcs to form between the distal end 210 of the insulating wire 112 and the inner diameter of the elongated conductive tube 208 (e.g., on the distal edge 203 of the insulating layer 206 or in the hole 204 in 206). The plasma arc generates cavitation bubbles in a controlled manner (at a specific rate, one at a time), which in turn causes mechanical vibrations in the conductive fluid and other effects related to bubble dynamics, such as collapse, turbulence, jetting, etc. (e.g., via the expansion and collapse of bubbles). The mechanical vibrations are used to destroy or eliminate occlusions. Compared with the generators used in the shock wave generation systems of the above-mentioned prior art, the generator used in this system is configured to generate pulses with lower voltages at a higher pulse repetition frequency, thereby minimizing the intensity of the shock wave and optimizing and maximizing the growth and collapse of the foam. For example, in the prior art system, each pulse may be about 3000 volts with a repetition rate of 1 Hz. In this system, the voltage may be less than 1000 volts with a repetition rate ranging from 14 to 200 Hz. In a preferred embodiment, the repetition rate may be as high as 800 Hz.

[0034] Since the plasma arc erodes the electrode during operation, the insulation on the spiral coil portion 202 and / or the coil portion decomposes and shortens over time. Similarly, the distal edge of the insulating layer 206 and the elongated conductive tube 208 may decompose due to use. The decomposition rate of the coil portion, the insulating layer and the elongated conductive tube may be different based on the polarity of the voltage applied by the physical properties of each component (e.g., the diameter of the guide wire, the characteristics of the guide wire, the thickness of the insulating layer), and the magnitude of the applied voltage. For example, a thinner guide wire connected to a higher voltage source and / or connected to a positive voltage port corrodes faster. In some cases, before the spiral coil portion 202 is widely used, a plasma arc is generated on the distal edge 203 of the insulating layer 206. However, when the spiral coil portion 202 is shortened due to use, the distance between the distal end 210 of the insulating guide wire 112 and the distal edge of the insulating layer 206 increases. Due to the increase in distance, a plasma arc is no longer generated on the distal edge 203 of the insulating layer 206. Conversely, when current flows from the distal end 210 of the helical coil portion 202 to the inner diameter of the elongated conductive tube 208, a plasma arc is generated in one of the holes 204 in the insulating layer 206 (e.g., the hole located closest to the distal end 210 of the shortened helical coil portion). Figure 2A As shown, a plurality of holes are provided along the longitudinal axis of the insulating layer 206, thereby allowing a plasma arc to be formed even if the spiral coil portion 202 is shortened, thereby improving the durability of the treatment system. In other words, when the device (i.e., the electrode) corrodes, the holes in the conductive layer are intended to become new spark areas. In some examples, the plurality of holes are arranged in a spiral orientation to align with the coil to control the maximum arc length. In some examples, the applied voltage is maintained for a relatively long period of time (e.g., several minutes) to achieve continuous generation and eventual penetration of cavitation bubbles. It should be noted that the generation location of the cavitation bubbles will change as the coil portion corrodes. In the embodiment shown, the generation location of the cavitation bubbles will rotate circumferentially around the periphery of the conductive tube 208.

[0035] In some examples, various parameters can be adjusted during operation to slow or even eliminate corrosion of the electrode. For example, the frequency (number of pulses per minute) of bubble generation / emission can be adjusted to control tip corrosion, durability, and drilling time. The frequency of bubble generation can be controlled by reducing capacitance (such capacitance changes can change the speed as needed) or by reducing current. As another example, the applied voltage can be adjusted based on the drilling time to control emitter corrosion and device durability while keeping the frequency constant based on the drilling time. In addition, the polarity of the electrode can be reversed for a period of time equivalent to a portion of the processing time (e.g., 10% to 100% of the time) while keeping the voltage and frequency constant based on the drilling time to control electrode wear and improve the durability of the device. In addition, the thickness of the guide wire insulation can be selected to control the durability of the guide wire.

[0036] U.S. Patent No. 10,226,265, incorporated herein by reference, teaches various methods for reversing the polarity of an electrode pair located in a conductive fluid. Those types of methods can be used with the subject device. In particular, to maintain peak sound output, the spark gap should be constant. As the electrodes erode, the gap may change. To compensate for this change in gap size, the polarity on the electrodes can be reversed. A polarity reversal frequency can be used to help control changes in spark gap length. The polarity reversal frequency can be adjusted based on the power output, the wire diameter, and the thickness of the insulator. The generator can also be made to detect a drop in power and automatically reverse the polarity on the electrodes.

[0037] Figure 2C is a cross-sectional view of an exemplary bubble generating end of a treatment system according to some embodiments. The typical diameter of the core (e.g., a copper core) of the insulated guidewire 112 is 0.005″ with a 0.0005″ polyimide coating. The number of turns of the coil portion determines the life of the electrode. Under an AC 500V-700V arc at 100Hz, one turn can last for approximately 30-40 seconds. Therefore, for a 10 minute procedure, the coil portion may include approximately 17 turns with a coil length of approximately 0.1″. The length of the elongated conductive tube 208 should be longer than the coil length to support the internal structure. The thickness of the insulating layer 206 (e.g., a polyimide insulator sheath) may be 0.001″. The outer diameter of the insulating layer 206 fits within the inner diameter of the elongated conductive tube 208. The outer diameter of the elongated conductive tube 208 (e.g., a stainless steel hypotube) can be in the range of 0.035″ to 0.065″ with a thickness of 0.002″. The arc gap between the guidewire core (e.g., a copper core) and the inner diameter of the elongated conductive tube is approximately 0.004″-0.007″. The arc gap can be longer if the insulating layer 206 and the hole 204 are away from, for example, the other side of the tube. In some examples, the arc gap is an ideal range to maximize cavitation. In some examples, various sizes of the system are selected to be compatible with off-the-shelf components.

[0038] Figure 3A perspective view of an alternative forward bubble generating tip 300 of a treatment system according to some embodiments is shown. The forward bubble generating tip 300 includes a plurality of atraumatic arms or forks 302 extending from the distal end of the elongated conductive tube 208. The forks 302 are made of a flexible material and are designed to deflect the tip without penetrating the lumen wall. In some examples, the fork can be coated with an elastomer (i.e., silicone rubber) or a low durometer polymer (i.e., polyurethane) and can be approximately 0.035″ in length. The flexible forks rotate the tip as the forward bubble generating tip drills through the occlusion and reaches soft tissue. In addition, the forward bubble generating tip 300 includes a plurality of spikes 304 extending from the distal end of the elongated conductive tube 208. The spikes 304 are designed to direct a plasma arc between the distal end 310 of the coil portion and the distal edge of the elongated conductive tube 208, for example, on the distal edge of the insulating layer 306.

[0039] Figure 4 4 is a side view of an exemplary system 400 for treating an occlusion according to some embodiments. As shown, the proximal end of the insulating outer sheath forms an inlet 402 for injecting a conductive fluid (e.g., saline). Inlet 402 can also be used as a conduit to introduce a guidewire (e.g., a 0.014" guidewire) after or during a saline flush. The injected conductive fluid has a number of uses. First, when the proximal ends of guidewires 410 and 412 are connected to a voltage source, as described above with reference to Figure 1-3 As described, a plasma arc can be formed via a conductive fluid at the forward bubble generation end. In addition, the conductive fluid injected continuously helps to dissipate heat and cool the electrode. The flow also generates forward inertia to help the bubble to drill forward and collapse (and eject). In some examples, the flow rate is adjusted to control the drilling efficiency and rate. In addition, the conductive fluid washes through the coil portion at the forward bubble generation end, and the debris such as the occluded block, metal and bubble that are broken are brought to the proximal balloon 406 from the forward bubble generation end 401. The proximal balloon captures the debris when inflated and prevents the debris from entering the aorta. As shown, the catheter 404 extends through the proximal balloon 406, and the distal end 409 of the catheter 404 is used as a waste inlet to receive the debris after flushing, and the debris is transported to the waste outlet 408 at the proximal end of the catheter. In some examples, suction is performed at the proximal end of the catheter 404 to facilitate the removal of debris. Rapidly removing debris helps to restore the cavity.

[0040] Figure 55 is a schematic diagram of an exemplary system 500 for treating occlusion, which illustrates other aspects of the present invention. System 500 also includes a console 502 having an infusion pump 504 and a generator 506. The infusion pump causes a conductive fluid (e.g., saline) to flow to the forward bubble generation end via the flushing lumen. In some examples, an auxiliary pump can be used to aspirate and remove debris. The generator is used as a voltage source for the electrode at the forward bubble generation end. The voltage of the pulse is in the range of 500 to 3000 volts, more preferably in the range of 600 to 1000 volts. In order to avoid generating excessive heat, the ideal electrical energy suitable for CTO penetration is very low (between 5 and 50 mJ per pulse), more preferably 30 mJ. The current range is 1-15 amperes. The repetition frequency of the generated pulses is in the range of 14 to 800 Hz. In some examples, the system also includes a visualization system and / or a steering system to properly navigate (e.g., side branches) and place the forward bubble generation end. Alternatively or additionally, the forward bubble generating tip can be made of a radiopaque material that is easily visible under fluoroscopic guidance. Thus, a barium sulfate filled material, tungsten or other radiopaque material or material filled with a radiopaque material can be used instead of steel so that the device can be tracked.

[0041] In use, a guidewire can be advanced through a central opening area in the device and toward a hole drilled or being drilled in the occlusion. For example, a guidewire can be advanced through a drilled hole to guide advancement of a treatment system that continues drilling until the occlusion is penetrated. In some examples, a guidewire can be advanced through an elongated conductive tube (e.g., from a saline inlet 402), and more specifically, through the center of the coiled portion of the bubble generating tip. After penetrating the closure, the forward bubble generating tip can be withdrawn, and the guidewire can be retained to allow for procedures such as an angioplasty balloon or Lithoplasty TM Other tools of the balloon are entered through the guidewire access. Lithoplasty is the assignee's trademark for its intravascular lithotripsy (shock wave) catheter. As described below, after drilling, the angioplasty balloon catheter can be advanced through the drilled hole to the distal end of the occlusion and aligned with the occlusion.

[0042] Figure 6 600 is a schematic diagram of another exemplary system for treating an occlusion according to some embodiments. The treatment system can be used alone or in combination with an angioplasty balloon 602. In some examples, the forward bubble generation tip is first advanced in a lumen (e.g., a blood vessel or ureter) to contact the occlusion, thereby drilling a hole in the occlusion according to the above-described procedure. The balloon is then advanced to the lesion. The balloon 602 is then pressurized with a fluid to expand the lumen, thereby increasing flow (e.g., blood flow). As described above, the advancement and positioning of the balloon can be aided by a guide wire passed through the center of the device.

[0043] Alternatively, the angioplasty balloon is a lithotripsy balloon, and the shock wave generator can be disposed in balloon 602. The shock wave generator can take the form of, for example, a pair of electrodes. When balloon 602 is aligned with the distal end of the occlusion and a high voltage pulse is applied to the electrodes, a shock wave is formed that propagates through the fluid and impinges on the walls of the balloon and the occlusion. The repeated shock waves destroy the occlusion without damaging the surrounding soft tissue. In some examples, the shock waves can be generated along an axis perpendicular to the axis of the catheter (rather than pointing forward) so that it treats different parts of the occlusion. The angioplasty balloon 602 can then be expanded to further open the lumen. As shown in FIG. Figure 6 As shown, the console 603 includes a selector switch 604 for switching between "CTO" and "Lithoplasty" TM " to switch the voltage source between providing a lower voltage pulse to the forward bubble generation end and a higher voltage pulse to the shock wave generator in balloon 602. In this example, the proximal balloon can be placed on either side of the lithotripsy balloon.

[0044] Figures 7 to 9A -9B shows an alternative embodiment of the treatment system of the present invention. Similar to the above embodiment, Figures 7 to 9A The embodiment of -9B includes a helical coil portion 702 at the distal end of an insulated guidewire 712. In addition, the distal end of the coil is not insulated, but constitutes an electrode. Unlike the above-mentioned embodiment, which includes a second conductor in the form of an outer cylindrical tube, in this embodiment, the second conductor is in the form of a cylindrical center electrode 720.

[0045] The distal end of the center electrode 720 is housed in the coil portion 702 of the insulating guidewire. In a preferred embodiment, an insulating tube 706 surrounds the distal end of the center electrode. The insulating tube includes a plurality of holes 704 that provide additional paths for the conducted current when the coil portion of the insulating guidewire corrodes during use. In a preferred embodiment, an annular channel 730 is formed between the outer surface of the insulating tube 706 and the inner surface of the coil portion 702. This channel can be used to supply a conductive fluid to the distal end of the device. Since the guidewire 712 is insulated, the device can be constructed without the insulating tube 706.

[0046] A cylindrical housing 724 surrounds the distal end of the device. The housing can be made of a metal such as stainless steel. Alternatively, the housing can be made of a non-metal such as polyetheretherketone (PEEK) or a composite such as Vespel. TM The proximal portion 728 of the housing is made of a polyimide-based plastic. The material should be heat resistant and provide a certain rigidity to pass through the occlusion. The proximal portion 728 of the housing is made of a more flexible material to facilitate advancement of the device through the circulatory system.

[0047] Can be used in a similar manner to the above embodiments Figures 7 to 9A -9B embodiment. Briefly, the central electrode and the proximal end of the insulated guidewire are connected to a power source that generates pulses with a repetition rate of several hundred pulses per second. The pulses generate cavitation bubbles in the conductive fluid at the distal end of the device. The cavitation bubbles generate mechanical vibrations that dislodge debris from the occlusion.

[0048] As in the above embodiment, during operation, the end of the coil portion of the insulating wire will generally corrode. As the wire corrodes, the point where the cavitation bubbles are generated moves circumferentially around the circumference of the center electrode. As described above, the holes 704 in the insulating tube 706 provide a sequential path for the current as the coil corrodes.

[0049] In a preferred embodiment, the central electrode 720 is removably mounted in the device. In use, after the occlusion is opened, the central electrode can be removed to provide a channel for inserting a guide wire or other device to perform other treatments.

[0050] Fig.10 Shows Figures 7 to 9A -9B embodiment variation. In this embodiment, the outer surface of the insulating tube 706 includes radially protruding spacers 740. The spacers 740 are used to separate the central electrode 720 from the inner surface of the coil portion 702 of the insulating guide wire 712.

[0051] It should be understood that the above content is only an example of the principles of the present invention, and various modifications, changes and combinations may be made by those skilled in the art without departing from the scope and spirit of the present invention. For example, the above principles can be used to treat occlusions formed in any part of the body. Any variation of the various therapeutic systems disclosed herein may include the features described in any other therapeutic system or combination of therapeutic systems herein. In addition, any method can be used with any therapeutic system disclosed. Therefore, the present invention is not limited except by the appended claims. For all of the above variations, the steps of the method do not need to be performed sequentially.

Claims

1. A system for treating an occlusion in a body lumen, comprising: an insulating outer sheath including an inlet for receiving a conductive fluid; an elongated conductive tube mounted in the distal end of the insulating outer sheath; an insulated guidewire having a helical coil portion at a distal end of the insulated guidewire, wherein the coil portion includes an exposed distal tip; wherein the coil portion is located in a distal portion of the elongated conductive tube; and Wherein, when a voltage is applied between the insulating guide wire and the elongated conductive tube, an electric current is configured to flow from the exposed distal end of the insulating guide wire to the elongated conductive tube to generate a plurality of cavitation bubbles.

2. The system of claim 1, further comprising an insulating layer disposed between the distal coil portion of the insulated guidewire and the elongated conductive tube.

3. The system according to claim 1, wherein: The elongated conductive tube is connected to the grounding wire.

4. The system of claim 3, further comprising a voltage source connected to the proximal end of the grounded guidewire and the proximal end of the insulated guidewire.

5. The system according to claim 2, wherein: The insulating layer includes a plurality of holes arranged along a longitudinal axis of the insulating layer.

6. The system according to claim 2, wherein: A plurality of plasma arcs are generated on a distal edge of the insulating layer.

7. The system according to claim 5, wherein: A plurality of plasma arcs are generated in one of the plurality of holes disposed on the insulating layer.

8. The system of claim 1, further comprising: a proximal balloon mounted over the length of the insulating outer sheath; and A waste conduit is provided for receiving debris carried by the injected conductive fluid.

9. The system of claim 1 further comprising a plurality of prongs at the distal end of the elongated conductive tube, wherein: The plurality of prongs are configured to prevent the distal end of the elongated conductive tube from penetrating the lumen.

10. The system of claim 2, further comprising a plurality of spikes at the distal end of the elongated conductive tube, wherein: The plurality of spikes are configured to generate a plurality of plasma arcs on a distal edge of the insulating layer.

11. The system according to claim 1, wherein: The distal end of the elongated conductive tube is configured to extend beyond the distal coil portion of the insulated guidewire to thereby generate the plurality of cavitation bubbles in a forward direction toward the occlusion.

12. The system of claim 1, wherein: The plurality of cavitation bubbles is configured to generate mechanical vibrations having a vibration frequency in a range of 14 Hz to 800 Hz.

13. The system of claim 1, wherein: The lumen is a blood vessel.

14. The system of claim 1, wherein the lumen is a ureter.

15. A system for treating an occlusion in a body lumen, comprising: an insulating tubular outer sheath including an inlet for receiving an electrically conductive fluid; an insulated guidewire positioned in the outer sheath near the distal end of the outer sheath, the insulated guidewire being a helical coil with a portion of insulation removed from a distal tip of the insulated guidewire to define an electrode; and A conductive tube is located around the insulating guide wire, and the proximal ends of the conductive tube and the insulating guide wire can be connected to the terminals of an electric pulse generator, so that in use, when a voltage pulse is applied to the conductive tube and the insulating guide wire, a series of cavitation bubbles are generated between the electrode of the insulating guide wire and the conductive tube, wherein when the distal end of the insulating guide wire wears during use, the electrode moves toward the proximal end of the insulating guide wire.

16. The system of claim 15, further comprising an insulating tube located between the insulating guidewire and the conductive tube, the insulating tube having a plurality of holes arranged along its longitudinal axis to provide a sequential current path between the electrode of the insulating guidewire and the conductive tube.

17. The system of claim 15, further comprising a guide wire passing through the center of the helical insulated guide wire.

18. The system of claim 15, further comprising a pump for injecting a conductive fluid into the proximal end of the tubular outer sheath, the fluid exiting from the distal end thereof.

19. The system of claim 15, further comprising a voltage pulse generator connected to the proximal ends of the insulated guidewire and the conductive tube, the voltage pulse generator generating pulses with a frequency between 14 and 800 Hz.

20. The system of claim 15, further comprising a balloon located between the distal and proximal ends of the insulating tubular outer sheath to capture debris.

21. The system of claim 15, wherein: The coil of the insulating guide wire is configured such that when the insulating guide wire is worn, the location where cavitation bubbles are generated will rotate circumferentially around the periphery of the conductive tube.

22. A system for treating an occlusion in a body lumen, comprising: an insulated guidewire having a helical coil portion near a distal end thereof and a portion of the insulation of the distal tip of the insulated guidewire removed to define an electrode; an elongated central electrode having a distal end received in the helical coil portion of the insulated guidewire; an insulating tube positioned around the distal end of the central electrode and within the helical coil portion of the insulating guidewire, defining an annular space between an outer surface of the insulating tube and an inner surface of the helical coil portion to define a fluid lumen; and A tubular shell covers the coil portion of the insulating guidewire, the central electrode and the proximal end of the insulating guidewire are capable of being connected to terminals of an electrical pulse generator, so that in use, when a voltage pulse is applied to the central electrode and the insulating guidewire, a series of cavitation bubbles are generated between the electrode of the insulating guidewire and the central electrode, wherein when the distal end of the insulating guidewire wears during use, the electrode moves toward the proximal end of the insulating guidewire.

23. The system of claim 22, further comprising a pump for injecting a conductive fluid into the proximal end of the fluid lumen, the fluid exiting from the distal end thereof.

24. The system of claim 22, wherein: The central electrode is removable and, when removed, defines a lumen for receiving a guide wire.

25. The system of claim 22, wherein: The distal region of the housing is made of a stiffer material than the proximal region of the housing.

26. The system of claim 22, wherein: The insulating tube includes a plurality of holes arranged along a longitudinal axis thereof to provide a sequential current path between the electrodes of the insulated guidewire and the center electrode.

27. The system of claim 22, wherein: The outer surface of the insulating tube includes a plurality of radially protruding spacers to maintain a separation between the center electrode and the helical coil portion of the insulating guidewire.

28. The system of claim 22, further comprising a voltage pulse generator connected to the central electrode and the proximal end of the insulated guidewire, the voltage pulse generator generating pulses with a frequency between 14 and 800 Hz.

29. The system of claim 22, wherein: The coil of the insulating guide wire is configured such that when the insulating guide wire is worn, the location where cavitation bubbles are generated will rotate circumferentially around the periphery of the center electrode.

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