Shockwave device with polarity switching

Abstract

An apparatus and method for forming a shock wave are described herein. The apparatus may include an axially extending elongated member. A first electrode pair may include a first electrode and a second electrode. The first electrode pair may be disposed on the elongated member and within a conductive fluid. A controller may be coupled to the first electrode pair. The controller may be configured to transmit a series of individual pulses to the first electrode pair, wherein each pulse forms a shock wave. The controller may cause a current to flow through the electrode pair in a first direction for a portion of the pulses in the series, and in a second direction opposite to the first direction for the remainder of the pulses in the series.

Description

[0001] This application is a divisional application of the patent application with application number 201780025574.6. The application date of the original application is February 1, 2017, and the name of the invention is "Shock wave device with polarity switching". Technical Field

[0002] The present invention relates to devices and methods for generating shock waves. These devices and methods can be used in angioplasty and / or valvuloplasty. Background Art

[0003] Currently, angioplasty balloons are used to open calcified lesions in arterial walls. However, when an angioplasty balloon is inflated to expand the lesion in the vessel wall, the inflation pressure stores a large amount of energy in the balloon until the calcified lesion ruptures or breaks open. The stored energy is then released and can compress and damage the vessel wall.

[0004] Electrohydraulic lithotripsy is commonly used to destroy calcified deposits or "stones" in the urethra or bile duct. Lithotripsy electrodes can similarly be used to destroy calcified plaques in the walls of vascular structures. The shock waves generated by the lithotripsy electrodes can be used to selectively destroy calcified lesions to help prevent sudden stress and damage to the vessel or valve wall when balloon dilation is used. Therefore, it may be useful to find improved ways to form shock waves in a balloon. Summary of the invention

[0005] Devices and methods for forming shock waves in angioplasty or valvuloplasty are described herein. In general, the shock wave device described herein includes an axially extending elongated member. The elongated member may include a first electrode pair, the first electrode pair including a first electrode and a second electrode. The electrode pair may be located in a conductive fluid. A controller may be coupled / connected to the first electrode pair and may be configured to transmit a series of individual pulses to the first electrode pair so that each pulse generates a shock wave in the conductive fluid. The controller may cause a current to flow through the electrode pair in a first direction for a portion of the pulses in the series, and in a second direction opposite to the first direction for the remaining pulses in the series. In some variations, the current may flow in a second direction for between 25 percent and 50 percent of the pulses in the series. The shock wave device and method described herein may help promote uniform and consistent delivery of energy to the electrodes, which may enhance the durability and performance of the electrodes.

[0006] In some variations, the controller may cause the current to flow in the second direction for between one third and one half of the pulses in the series. In other variations, the controller may cause the current to flow in the second direction for at least about half of the pulses in the series.

[0007] In some variations, the controller may include a voltage polarity switch to switch the polarity of the electrode between positive and negative. The electrodes may have opposite polarities. In other variations, the first surface area of ​​the first conductive region of the first electrode may be smaller than the second surface area of ​​the second conductive region of the second electrode.

[0008] In some variations, the controller may include a voltage source. A first wire may connect the first electrode to a first terminal of the voltage source, and a second wire may connect the second electrode to a second terminal of the voltage source. In some cases, in a first current flow direction, the first terminal is positive and the second terminal is negative, and in a second direction, the first terminal is negative and the second terminal is positive.

[0009] In some variations, a second electrode pair may be provided, and the controller may further include a multiplexer configured to selectively transmit a series of pulses to the first electrode pair and the second electrode pair. In other variations, the device may further include a fluid enclosure surrounding the electrode pair. The fluid enclosure may include a sacculus surrounding a portion of the elongated member. The sacculus may be configured to be filled with a conductive fluid, and the first electrode pair may be encapsulated in the sacculus and spaced apart from the sacculus.

[0010] In yet other variations, the shock wave device described herein may include an axially extending elongated member. The elongated member may include a first electrode assembly, the first electrode assembly including a first electrode pair and a second electrode pair. The first electrode assembly may be located within a conductive fluid. A controller may be coupled to the first electrode assembly and configured to transmit a series of individual pulses to the first electrode assembly so that each pulse generates a shock wave in the conductive fluid. The controller may cause the current to flow through the electrode assembly in a first direction for a portion of the pulses in the series, and in a second direction opposite to the first direction for the remaining pulses in the series. In some cases, the current flows in the second direction for between twenty-five percent and fifty percent of the pulses in the series.

[0011] In some variations, the first electrode assembly may include a first electrode, a second electrode, and a common electrode. The first electrode pair may include a first electrode and a common electrode, and the second electrode pair may include a second electrode and a common electrode. In some cases, the controller may include a voltage polarity switch to switch the polarity of the first electrode and the second electrode between positive and negative. The first electrode and the second electrode may have opposite polarities. In other cases, the first surface area of ​​the first conductive region of the first electrode and the second surface area of ​​the second conductive region of the second electrode may be different from the third surface area of ​​the third conductive region of the common electrode. In some cases, the controller may include a voltage source, wherein the first wire may connect the first electrode to the first terminal of the voltage source, and the second wire may connect the second electrode to the second terminal of the voltage source. In some cases, the controller may include a voltage source, wherein the first wire may connect the first electrode to the first terminal of the voltage source, the second wire may connect the second electrode to the second terminal of the voltage source, and the third wire may connect the common electrode to the third terminal of the voltage source.

[0012] In some variations, the second electrode assembly may be coupled in series to the first electrode assembly. In some cases, the controller may include a voltage source, wherein a first wire may connect the first electrode assembly to a first terminal of the voltage source, a second wire may connect the second electrode assembly to the second electrode assembly, and a third wire may connect the second electrode assembly to a second terminal of the voltage source.

[0013] In other variations, the device may include a second electrode assembly. The controller may also include a multiplexer that selectively transmits a series of pulses to the first electrode assembly and the second electrode assembly. In yet other variations, the device may also include a fluid enclosure surrounding the first electrode assembly. The fluid enclosure may include a balloon surrounding a portion of the elongated member. The balloon may be configured to be filled with a conductive fluid, and the first electrode assembly may be encapsulated within the balloon and spaced apart from the balloon.

[0014] In some variations, the methods of forming shock waves described herein may include advancing a shock wave device into a blood vessel. The shock wave device may include an axially extending elongated member. The elongated member may include a first electrode pair, the first electrode pair including a first electrode and a second electrode. The first electrode pair may be located within a conductive fluid. A series of individual pulses may be delivered to the first electrode pair to generate a shock wave in the conductive fluid, such that current flows through the electrode pair in a first direction for a portion of the pulses in the series, and flows through the electrode pair in a second direction opposite to the first direction for the remaining pulses in the series. In some variations, the current may flow in the second direction for between 25 percent and 50 percent of the pulses in the series.

[0015] In some variations, the current may flow in the second direction for between one-third and one-half of the pulses in the series. In other variations, the current may flow in the second direction for at least about half of the pulses in the series. In some variations, the voltage pulse width may be measured to monitor the status of the shock wave device. In some of these variations, the percentage of pulses that cause current to flow in the second direction may be adjusted based on the measured voltage pulse width. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figures 1A-1D is an illustrative diagram of a variation of the electrode assembly. Figure 1A and 1D is a block diagram of a variation of a controller coupled to an electrode assembly. Figure 1B and 1C is an explanatory diagram of a variation of a flat electrode assembly.

[0017] Figure 2A-2B is an illustrative diagram of a variation of a series of electrode assemblies. Figure 2A is a block diagram of a variation of a controller coupled to the series of electrode assemblies. Figure 2B is an explanatory diagram of a variation of a flat electrode assembly.

[0018] Figure 3 is an illustrative block diagram of one variation of a shock wave system including an electrode assembly, a controller, and a voltage source.

[0019] Figure 4 is an illustrative timing diagram of a variation of the shock wave system.

[0020] Figure 5 is a perspective view of another variation of the shock wave device.

[0021] Figures 6A-6C is an explanatory diagram of another variation of the electrode assembly. Fig. 6A is a top view / plan view of a variation of an electrode assembly, Figure 6B This is its bottom view / bottom view. Figure 6C is a perspective view of a variation of the common electrode.

[0022] Figure 7A-7B is an illustrative diagram of a variation of a series of electrode assemblies. Fig. 7A is a top view of a variation of a series of electrode assemblies, Figure 7B This is its bottom view.

[0023] Fig. 8A is an illustrative graph comparing voltage drop as a function of pulse number between switching and non-switching energy pulses. Figure 8B and 8Cis an illustrative graph comparing voltage drops as a function of pulse width variation for non-switching electrode assemblies and switching electrode assemblies, respectively.

[0024] Fig. 9A It is an explanatory graph of the number of pulses that change according to the voltage polarity. Fig. 9B is an illustrative graph of energy delivered at an electrode assembly as a function of the number of pulses between switching and non-switching energy pulses. DETAILED DESCRIPTION

[0025] Devices and systems comprising one or more shock wave electrodes are described herein that may be suitable for use in angioplasty and / or valvuloplasty. In general, the shock wave electrodes are disposed along an axially extending elongated member (e.g., a catheter) and may be attached to a high voltage pulse source in the range of 0.1 kV to 10 kV for various pulse durations. In some variations, the electrodes may be surrounded by an enclosure that transports a conductive fluid (e.g., saline). In some variations, the enclosure may include a balloon that surrounds a portion of the elongated member and is configured to be filled with a conductive fluid, wherein the electrodes may be encapsulated within and spaced apart from the balloon wall.

[0026] A controller may be coupled to the first electrode pair to transmit a series of energy pulses, thereby generating a shock wave. The generated shock wave may destroy calcified obstructions in an artery or valve. A mechanism for the formation of shock waves is described below. When a high voltage is applied across a pair of electrodes located in a conductive fluid, a plasma arc may be formed between them, thereby generating steam bubbles in the fluid. A first shock wave may occur when the steam bubble first forms, and a second shock wave may occur when the steam bubble ruptures. The shock wave may be mechanically conducted via the fluid to apply a mechanical force or pressure, thereby breaking open any calcified plaque on or in the wall of the vascular system.

[0027] The size, expansion rate, and collapse of the bubbles (and thus the magnitude, duration, and distribution of the mechanical forces) can vary based on the amplitude and duration of the voltage pulses. In addition, the timing and size of the bubbles and the acoustic output and propagation direction of the resultant shock waves depend, at least in part, on the location, geometry, size, state, and distance between the electrodes (electrode gap distance) of the electrodes. For example, an increase in the electrode gap distance can reduce the corresponding acoustic output. The size and arrangement of the electrodes can also affect the type of vascular structures that can be approached and treated by the shock wave device. The shock wave electrodes can be made of materials that can withstand the high voltage levels and strong mechanical forces (e.g., about 300-3000 psi or 20-200 ATM in a few microseconds) that may be generated during use. For example, the electrodes can be made of stainless steel, tungsten, nickel, iron, steel, etc.

[0028] Generally speaking, current flowing between a pair of electrodes in a conductive fluid causes metal to move from the positive terminal to the negative terminal, eventually depleting the positive terminal material and what may be referred to as single-sided corrosion when the direction of current flow is fixed. Shockwave electrodes experience high rates of wear and corrosion due to the necessarily high currents (e.g., hundreds of amperes) flowing through the fluid, the heat generated by the plasma arc, and the mechanical shockwave forces.

[0029] The apparatus, system and method described herein can help reduce the electrode wear rate to enhance electrode durability and shock wave consistency. The life of the electrode pair can depend on at least one of the following: the polarity of the voltage pulse, the length of the voltage pulse, the size of the voltage pulse, the material properties, the fluid conductivity, the electrode gap distance between the conductive areas of each electrode in the electrode pair, and / or the surface area of ​​the conductive area of ​​the electrode in the electrode pair. Compared with shorter pulses, longer pulses can increase the wear / corrosion of the electrode pair. In some variations of the electrode pair with electrodes of different sizes, one of the electrodes has a smaller conductive area surface area than the other electrode, and the electrode with a smaller conductive area is more susceptible to corrosion than the electrode with a larger conductive area. That is, the corrosion rate of the electrode with a smaller conductive area can be faster than the corrosion rate of the electrode with a larger conductive area. The apparatus and method described herein can help balance the corrosion rate between the electrodes in the electrode pair so that the electrodes corrode at approximately the same rate. This can enhance the durability of the entire electrode pair and can also facilitate uniform energy transmission to the electrode pair over a larger number of pulses.

[0030] It should be understood that the shock wave device generates the strongest shock waves when the electrodes are of different sizes and wherein the smaller electrode has a positive polarity and the larger electrode has a negative polarity. Thus, while an electrode pair having a smaller positive terminal electrode and a larger negative terminal electrode may form the strongest shock waves, this combination of size and polarity may shorten the life of the electrode pair. The problem of short life may not be a simple matter of increasing the size of the electrodes, since the size of the shock wave device and the electrodes may be limited by the size of the vascular system through which they are advanced. However, as described in further detail below, voltage polarity switching may promote electrode life while maintaining electrode size so that the electrodes may be navigated through the vascular system. Additionally or alternatively, voltage polarity switching may be advantageous in reducing electrode size while having an electrode life similar to that of a non-polarity switched device.

[0031] In addition, the devices, systems, and methods described herein can promote uniformity in the intensity of shock waves formed at different locations along the shock wave device. In some variations, the shock wave device can include multiple spaced-apart electrode pairs connected in series. Even if the electrode pairs are the same size and shape, the intensity of the shock waves generated by the electrode pairs can vary. For example, identical electrode pairs in series positioned 180 degrees apart from each other can form shock waves of different intensities from opposite sides of the device. For any single pulse, this difference can be negligible. However, for a series of pulses, one side of the shock wave device may be more effective in lysing calcium deposits than the other side of the device. Voltage polarity switching, as described in further detail below, can promote uniformity in the intensity of the shock waves formed in different electrode pairs.

[0032] For example, the controller may cause the current to flow through the electrode pair in a first direction for a portion of the pulses, and in a second direction opposite to the first direction for another portion of the pulses. As an example, the current flow direction may change between each pulse or between every two pulses, and is not particularly limited. It should be noted that the pulses are output discretely so that there is a time interval between the pulses when the current is not flowing through the shock wave device. The duration of the time interval may be preselected based on, for example, the desired rate or frequency of shock wave generation. In addition, each pulse has a single current flow direction and does not switch within the pulse. For example, the voltage polarity switching may only switch when the current is not flowing to the shock wave device (i.e., the voltage polarity switching may only occur in the interval between the voltage pulses, and not during the voltage pulses).

[0033] Furthermore, for each pulse, the current flow direction may change randomly, as long as the total number of pulses maintains a predetermined current flow direction ratio. For example, for a set of 50 pulses evenly divided into a first direction and a second direction, the current flow direction does not need to be switched for each pulse. As an illustrative example, 20 pulses in the first direction may be followed by 10 pulses in the second direction, followed by 3 pulses in the first direction, 15 pulses in the second direction, and 2 pulses in the first direction. Thus, while the total number of pulses is evenly divided between the first and second directions, the number of switches in the current flow does not necessarily correspond to the current flow direction ratio.

[0034] In some variations, a single pulse may be provided in the second direction with the remaining pulses in the first direction, or vice versa. This allows the electrode pair to generate a shock wave with a greater number of pulses before failure compared to an electrode pair receiving pulses with a constant polarity. Thus, durability may be improved by distributing electrode wear / loss of positive pulses across both electrodes.

[0035] In one variation, the current may flow in a first direction for approximately half of the pulses in the series and in an opposite second direction for the other half of the pulses in the series. In this way, for approximately half of the pulses, each electrode is configured as a positive terminal, thereby distributing the number of high-corrosion positive pulses experienced by any one electrode approximately equally between the electrodes of the electrode pair. The direction of current flow may be switched one or more times. In some cases, the life of an electrode pair may be approximately twice that of an electrode having a single current flow direction, thereby allowing more shock waves to be formed and / or smaller electrode pairs to be formed than electrodes having a single current flow direction. Therefore, the shock wave device described herein may be particularly suitable for small arteries such as coronary arteries. In addition, a shock wave device including multiple electrode pairs having pulses with current flowing in both directions may promote uniformity in the intensity of shock waves generated by the electrode pairs.

[0036] I. Device

[0037] Generally described herein are shock wave devices for use in angioplasty and / or valvuloplasty. The devices and methods described herein may use one or more devices or elements described in U.S. Patent No. 8,888,788, entitled "LOW PROFILE ELECTRODES FOR AN ANGIOPLASTY SHOCK WAVE CATHETER" and / or one or more devices or elements described in U.S. Patent No. 9,011,463, entitled "SHOCK WAVE BALLOON CATHETER WITH MULTIPLESHOCK WAVE SOURCES," each of which is hereby incorporated by reference in its entirety.

[0038] Figure 1A1 is a block diagram of a controller 120 coupled to an electrode assembly 100. The electrode assembly 100 may include a first electrode 102, a second electrode 104, and a third electrode 106. The first electrode 102 may be connected to a first voltage output terminal V01 of a voltage source of the controller 120 via a first wire 108, the third electrode 106 may be connected to a second voltage output terminal V02 of a voltage source of the controller 120 via a second wire 110, and the second or common electrode 104 may be arranged in series between the first electrode 102 and the third electrode 106. When a sufficient voltage pulse is applied, a first plasma arc may be formed between the first electrode 102 and the second electrode 104 (i.e., a first electrode pair), and a second plasma arc may be formed between the second electrode 104 and the third electrode 106 (i.e., a second electrode pair). The first and second electrode pairs are connected in series, wherein the second electrode 104 is shared between the first and second electrode pairs. Although the electrode assembly 100 is described above as including three electrodes forming two electrode pairs, some variations of the electrode assembly may include two electrodes forming one electrode pair.

[0039] The first current flow direction 112 of the energy pulse can be delivered to the electrode assembly 100 by the voltage source 122 of the controller 120. The controller 120 can cause other pulses delivered to the electrode assembly 100 to have a second current flow direction 116 opposite to the first direction 112. For each pulse delivered to the electrode assembly 100, the controller 120 can select the current flow direction, and therefore the voltage polarity of the electrode. To select the current flow direction, the controller 120 can include a voltage polarity switch 124 to switch the polarity of the electrodes 102, 106 between positive and negative polarity, wherein the electrodes 102, 106 have opposite polarities.

[0040] In some variations, for a series of pulses, the controller may cause the current to flow through the electrode pair in a first direction for a portion of the pulses in the series, and the current to flow through the electrode pair in a second direction opposite to the first direction for the remaining pulses in the series. In one variation, a first current flow direction may be provided for at least one of the pulses. In another variation, a first current flow direction may be provided for at least about 5% of the pulses. In another variation, a first current flow direction may be provided for at least about 10% of the pulses. In another variation, a first current flow direction may be provided for at least about 15% of the pulses. In another variation, a first current flow direction may be provided for at least about 20% of the pulses. In another variation, a first current flow direction may be provided for at least about 25% of the pulses. In another variation, a first current flow direction may be provided for at least about 30% of the pulses. In yet another variation, a first current flow direction may be provided for at least about one-third of the pulses. In another variation, a first current flow direction may be provided for at least about 40% of the pulses. In another variation, a first current flow direction may be provided for at least about 45% of the pulses. In yet another variation, the first current flow direction may be provided for at least about half of the pulses.

[0041] In still other variations, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:6. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:6. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 3:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 7:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 2:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 4:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 7:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 8:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 1:12. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 1:16. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 1:32.

[0042] It should be understood that these examples are non-limiting. For example, the controller may provide current delivery in the first direction for each pulse, except for one pulse provided in the second direction, or vice versa. The number of pulses in each current flow direction (e.g., the ratio of current flow in the first direction to the second direction) may be determined based on the expected life of the shock wave device, shock wave uniformity, shock wave energy, etc. In some variations, providing the first current flow direction for approximately half of the pulses may maximize the life of the shock wave device.

[0043] There is no particular limit to the number of transitions between the directions of current flow. In some cases, the direction of current flow can be switched according to the ratio of the pulses in the first direction to the pulses in the second direction. For example, when there are an equal number of positive pulses and negative pulses, the direction of the current can be switched for each pulse. However, for each pulse, the direction of current flow can also change randomly, as long as the total number of pulses maintains a predetermined current flow direction ratio. Therefore, even if the number of pulses in each direction is equal, the direction of current flow does not need to be switched for each pulse. As another example, the current flow direction of the average alternating pulses can increase the durability of the smaller electrode by about one time, thereby increasing the life of the electrode assembly by about one time. Even when the electrodes in the electrode pair are of equal size, alternating the current flow direction so that each electrode receives approximately the same number of positive pulses will also distribute the wear on the two electrodes, thereby increasing the durability of the electrode pair by about one time compared to the electrode receiving a single current direction. It should be noted that the polarity switching of any number of pulses contributes to durability (e.g., the number of shock waves generated by the electrode before the electrode fails).

[0044] Furthermore, since polarity switching allows each electrode pair to receive a positive pulse, the shockwaves output from different electrode pairs are averaged to promote uniformity of shockwave force between shockwave locations. This allows for more predictable results in which a higher average shockwave intensity is delivered at each shockwave location. For example, Fig. 9B is an illustrative graph of the energy delivered as a function of pulse number for a static (constant polarity) shock wave device and a switching (alternating polarity) shock wave device. Fig. 9B In the present invention, the electrical energy delivered by the polarity switching shock wave device is higher on average per pulse and has less attenuation than the energy delivered to the constant polarity device. The delivered electrical energy can be positively correlated with the shock wave intensity.

[0045] Next, Figure 1B and 1C The second electrode 104 shown in FIG. 1 may have a barrel (cylindrical) or annular shape, similar to that discussed in further detail below. Figure 6C However, for ease of explanation, Figure 1B and1C A flat second electrode 104 is depicted to illustrate the different voltage polarities that may be applied to the electrode assembly 100. Figure 1B In the embodiment of the present invention, the controller 120 can output one or more positive pulses in a first current flow direction 112, wherein the first wire 108 is coupled to the positive terminal of the voltage source 122 of the controller 120 and the first electrode 102, and the second wire 110 is coupled to the negative terminal of the voltage source of the controller 120 and the third electrode 106. In use, applying a voltage pulse generates a plasma in the fluid, which extends through the electrode pair and allows current to be conducted. The current then flows from the first electrode 102 to the second electrode 104 and then to the third electrode 106. Thus, the plasma formation creates two electrode pairs connected in series. As described above, when receiving a positive pulse from the controller 120, the first electrode 102 at the positive terminal may experience a higher wear rate than the third electrode 106 at the negative terminal.

[0046] On the contrary, Figure 1C In the embodiment, when receiving a negative pulse in the second current flow direction 116 from the voltage source 122 of the controller 120, the first electrode 102 of the negative terminal may consume less material than the third electrode 106 of the positive terminal. In order to more evenly distribute the wear between the first electrode 102 and the third electrode 106, the controller 120 may make the first direction 112 flow ( Figure 1B ) and for other pulses the current flows in a second direction 116 opposite to the first direction 112 ( Figure 1C As a result, the electrode assembly 100 can form a greater number of shock waves with improved consistency before one or both of the smaller electrodes (102, 106) are exhausted and the electrode assembly 100 fails.

[0047] In addition, if Figure 1B and 1C As shown, regardless of the direction of current flow, the first electrode 102 and the third electrode 106 will have opposite voltage polarities. Therefore, the strength of the shock wave formed by the first electrode pair and the second electrode pair will be different for each pulse. In the illustrated embodiment, the conductive area of ​​the first electrode 102 and the third electrode 106 can be smaller than the conductive area of ​​the second electrode 104. Therefore, receiving a positive pulse 112 ( Figure 1B ) can generate a stronger shock wave than the second electrode pair. Similarly, the first electrode pair receiving the negative pulse 116 can generate a weaker shock wave than the second electrode pair.

[0048] However, by alternating positive and negative pulses to the electrode assembly 100, the average shock wave intensity output by the first electrode pair and the second electrode pair can be more uniform, thereby reducing variability. This can provide more consistent and predictable treatment by the shock wave device, so that practitioners may not need to align the shock wave device in the vascular system based on differences in shock wave intensity between electrode pairs.

[0049] Figure 1D 1 is a block diagram of another variation of a controller 120 coupled to an electrode assembly 100. The electrode assembly 100 may include a first electrode 102, a second electrode 104, and a third electrode 106. The first electrode 102 and the second or common electrode 104 form a first electrode pair, and the third electrode 106 and the second electrode 104 form a second electrode pair. A first current flow direction 112 of an energy pulse may be delivered to the electrode assembly 100 by a voltage source 122 of the controller 120. The controller 120 may cause other pulses delivered to the electrode assembly 100 to have a second current flow direction 116 that is opposite to the first direction 112 through the electrode assembly 100. For each pulse delivered to the electrode assembly 100, a voltage polarity switch 124 of the controller 120 may select a current flow direction, and therefore a voltage polarity of the electrode.

[0050] exist Figure 1D In the embodiment, the first electrode 102 can be connected to the first voltage output terminal V01 of the voltage source 122 of the controller 120 through the first wire 108, the third electrode 106 can be connected to the second voltage output terminal V02 of the voltage source 122 of the controller 120 through the second wire 110, and the second electrode 104 can be connected to the third voltage output terminal V03 (ground channel) of the voltage source 122 of the controller 120 through the third wire 114. In some variations, for a portion of the pulses, the first voltage output terminal V01 and the second voltage output terminal V02 can be positive channels, and the third voltage output terminal V03 can be a negative channel. For the remaining pulses, the controller 120 can also set the first voltage output terminal V01 and the second voltage output terminal V02 as negative channels, and the third voltage output terminal V03 can be a positive channel.

[0051] During the high voltage pulse on the first and / or second voltage output terminals V01, V02, the current may flow to the corresponding first electrode 102 and the third electrode 106 via the first wire 108 and / or the second wire 110 in the first direction 112 or the second direction 116. The voltage source 122 of the controller 120 may apply a positive or negative pulse on the output terminal V01 so that the potential difference between the first electrode 102 and the second electrode 104 is large enough to form a plasma arc between them, thereby generating bubbles, which generate shock waves. Similarly, the voltage source 122 of the controller 120 may apply a positive or negative pulse on the output terminal V02 simultaneously or sequentially so that the potential difference between the third electrode 106 and the second electrode 104 is large enough to form a plasma arc between them, thereby generating bubbles, which generate different shock waves. In some variations, when energy pulses are simultaneously applied to output terminals V01 and V02 , a first shock wave formed between the first electrode 102 and the second electrode 104 and a second shock wave formed between the third electrode 106 and the second electrode 104 may be simultaneously formed.

[0052] Where the first electrode 102 and the third electrode 106 are positioned circumferentially opposite one another (e.g., 180 degrees apart from one another around the circumference of the elongated member), the shock waves generated by the first and second electrode pairs may propagate in opposite directions extending outwardly from both sides of the shock wave device. Current passing through the bubble from the first electrode 102 and / or the third electrode 106 to the second electrode 104 may be returned to the voltage output terminal V03 (which may be a ground path) via the third conductor 114. The voltage output terminals V01 and V02 may be independently addressable (e.g., voltage and current may be applied to one output terminal but not necessarily to the other output terminal), or may not be independently addressable (e.g., activation of one output terminal necessarily activates the other output terminal).

[0053] In another variation, Figure 2A 2 is a block diagram of a controller 220 coupled to first and second electrode assemblies 200, 250. The first electrode 202 and the first common electrode 206 form a first electrode pair that can generate a first shock wave, and the second electrode 204 and the first common electrode 206 form a second electrode pair that can generate a second shock wave. Similarly, the third electrode 252 and the second common electrode 256 form a third electrode pair that can generate a third shock wave, and the fourth electrode 254 and the second common electrode 256 form a fourth electrode pair that can generate a fourth shock wave.

[0054] The first, second, third and fourth electrode pairs can be connected in a series configuration and receive a series of pulses. The first current flow direction 214 of a portion of the pulses in the series can be transmitted to the first and second electrode assemblies 200, 250 by the voltage source 222 of the controller 220. The controller 220 can make the remaining pulses in the series delivered to the first and second electrode assemblies 200, 250 have a second current flow direction 216 through the electrode assemblies 200, 250. For each pulse transmitted to the electrode assemblies 200, 250, the voltage polarity switch 224 of the controller 220 can select the current flow direction, and therefore select the voltage polarity of the electrode. For example, the voltage polarity switch 224 can switch the polarity of the first electrode 202 and the fourth electrode 254 between positive and negative, wherein the first electrode 202 and the fourth electrode 254 have opposite polarities.

[0055] In some variations, for a series of pulses, the controller may cause the current to flow through the electrode pair in a first direction for a portion of the pulses in the series, and the current to flow through the electrode pair in a second direction opposite to the first direction for the remaining pulses in the series. In one variation, a first current flow direction may be provided for at least one of the pulses. In another variation, a first current flow direction may be provided for at least about 5% of the pulses. In another variation, a first current flow direction may be provided for at least about 10% of the pulses. In another variation, a first current flow direction may be provided for at least about 15% of the pulses. In another variation, a first current flow direction may be provided for at least about 20% of the pulses. In another variation, a first current flow direction may be provided for at least about 25% of the pulses. In another variation, a first current flow direction may be provided for at least about 30% of the pulses. In yet another variation, a first current flow direction may be provided for at least about one-third of the pulses. In another variation, a first current flow direction may be provided for at least about 40% of the pulses. In another variation, a first current flow direction may be provided for at least about 45% of the pulses. In yet another variation, the first current flow direction may be provided for at least about half of the pulses.

[0056] In still other variations, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:6. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:6. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 3:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 7:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 2:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 4:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 7:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 8:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 1:12. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 1:16. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be about 1:32.

[0057] In some variations, the number of pulses in each current flow direction (e.g., the ratio of current flow in the first direction to the second direction) may be determined based on the expected life of the shock wave device, shock wave uniformity, shock wave energy, material properties, electrode gap distance, fluid conductivity, etc. In some cases, the current flow direction may be switched based on the ratio of pulses in the first direction to the second direction. In other cases, the current flow direction may be randomly changed for each pulse, as long as the total number of pulses maintains the predetermined current flow direction ratio.

[0058] In addition, the shock waves output from the first through fourth electrode pairs can have, on average, a more uniform intensity because the polarity switching allows each electrode pair to receive a positive pulse. This allows for more predictable results, wherein a greater amount of electrical energy is delivered to each electrode pair, which can promote the generation of stronger shock waves. Thus, the shock wave device can apply mechanical force / pressure more uniformly regardless of the orientation of the shock wave device within the vascular system.

[0059] In some variations, Figure 2AThe illustrated first and second common electrodes 206, 256 may have a cylindrical or annular shape, similar to that discussed in further detail below. Figure 6C However, for ease of illustration, Figure 2B The flat first and second common electrodes 206, 256 are depicted to illustrate the different voltage polarities that can be applied to the first and second electrode assemblies 200, 250. The voltage source 222 of the controller 220 can output one or more pulses, wherein the first wire 208 is coupled to the positive terminal V01 of the controller 220, and the third wire 212 is coupled to the negative terminal V02 of the controller 220. The second electrode 204 can be connected to the third electrode 252 via the second wire 210 (e.g., an interconnect wire). In this configuration, the first and second electrode assemblies 200, 250 receive positive pulses, wherein the first and third electrode pairs generate stronger shock waves than the second and fourth electrode pairs.

[0060] Conversely, the voltage source 222 of the controller 220 may output one or more pulses, wherein the first wire 208 is coupled to the negative terminal V01 of the controller 220, and the third wire 212 is coupled to the positive terminal V02 of the controller 220. In this configuration, the first and second electrode assemblies 200, 250 receive negative pulses, wherein the second and fourth electrode pairs generate stronger shock waves. Therefore, in order to more evenly distribute the wear between the electrodes of the first and second electrode assemblies 200, 250, the voltage polarity switch 224 of the controller 220 may cause the current to flow in a first direction for a portion of the pulses in a series of pulses and in a second direction opposite to the first direction for the remaining pulses in the series. As a result, the electrode assemblies 200, 250 may form a greater number of shock waves before one or more smaller internal electrodes (202, 204, 252, 254) are exhausted, as well as more uniform shock waves that propagate on average from the electrode assemblies (200, 250).

[0061] Figure 3 FIG. 3 is an illustrative block diagram of a variation of a shock wave system 300, which includes a first electrode assembly 302, a second electrode assembly 303, a third electrode assembly 304, a fourth electrode assembly 306, and a fifth electrode assembly 307. The first electrode assembly 302 may include a first electrode 302a, a second electrode 302b, and a third electrode 302c, each having a configuration similar to that shown in FIG. Figure 1A and 1B The structure of the first electrode 102, the second electrode 104 and the third electrode 106 is shown. Figure 3, the conductive surface area of ​​the first electrode 302a and the third electrode 302c can be smaller than the conductive surface area of ​​the second electrode 302b. In other variations, the larger electrode 302b may include separate electrodes connected by, for example, interconnecting wires. The second to fifth electrode assemblies 303, 304, 306, and 307 may include an electrode configuration similar to the first electrode assembly 302.

[0062] The first and second electrode assemblies 302 and 303 are connected in series. The fourth and fifth electrode assemblies 306 and 307 are connected in series. Figure 3 As shown, the electrode assemblies 302, 303, 304, 306, and 307 are switchably connected in parallel with the controller 310. The controller 310 may include a voltage source 312 to deliver pulses to the electrode assemblies 302, 303, 304, 306, and 307. The multiplexer 316 of the controller 310 may selectively activate the first and second electrode assemblies 302 and 303, the third electrode assembly 304, and the fourth and fifth electrode assemblies 306 and 307. The multiplexer 316 may be configured to selectively connect the voltage source 312 across the parallel electrode assembly lines individually, one at a time, or in any combination. The controller 310 may also include a voltage polarity switch 314, which is configured to provide a first current flow direction corresponding to a first switch position 318 and a second current flow direction opposite to the first direction, the second direction corresponding to a second switch position 320.

[0063] For example, the voltage source 312 outputs a predetermined voltage pulse to the voltage polarity switch 314. In the switch 314, the current flow direction is selected between a first current flow direction and a second direction opposite to the first direction. The multiplexer 316 can receive energy pulses in the first direction or the second direction, and then selectively transmit a series of pulses having the current flow direction selected by the voltage polarity switch 314 to the electrode assemblies 302, 303, 304, 306 and 307, as shown in FIG. Figure 4 As shown in the timing diagram.

[0064] Figure 4is an illustrative timing diagram of a variation of a shock wave system 300 for selectively coupling electrodes to a power source with a selective current delivery direction. For example, the controller 310 may sequentially (e.g., one at a time) activate different groups of electrode assemblies with a first voltage polarity, and then sequentially activate different groups of electrode assemblies with a second voltage polarity. This conserves all of the high voltage for each shock wave, thereby forming a shock wave of maximum intensity to be applied to calcium deposits along the entire vasculature. Reversing the polarity in subsequent pulses for each electrode assembly 302, 303, 304, 306, and 307 may more evenly distribute electrode wear and shock wave intensity within the electrode pairs of the electrode assembly, thereby improving the life and consistency of the shock wave device. In other examples, the voltage polarity of the electrode assembly may be varied for each pulse, every two pulses, every three pulses, and is not particularly limited. In addition, the voltage polarity may be varied randomly. For example, for a set of 50 pulses evenly split between a first voltage polarity (e.g., positive pulses) and a second voltage polarity (e.g., negative pulses), the voltage polarity need not be switched for every pulse. As an illustrative example, 8 pulses at the first voltage polarity may be followed by 5 pulses at the second voltage polarity, followed by 7 pulses at the first voltage polarity, 5 pulses at the second voltage polarity, 10 pulses at the first voltage polarity, and 15 pulses at the second voltage polarity. Thus, while the total number of pulses is evenly split between the first and second voltage polarities, the number of switching of polarities does not necessarily correspond to / depend on the current flow ratio.

[0065] In some variations, a multiplexer may be coupled to one or more of the electrode assemblies 302, 303, 304, 306, and 307, such as Figure 3 As shown. For example, any voltage polarity switching sequence discussed herein may be incorporated with multiplexer 316. In some variations, the selection of voltage polarity may be independent of the electrode assembly selected by the multiplexer. Alternating polarity and timing may provide the dual benefits of distributing positive pulse wear across multiple electrodes and increasing rest time for electrode assemblies.

[0066] The polarity switching and multiplexing described above can be applied to any shock wave device described herein, including as described in detail below. Figure 5-7B In one embodiment, a shock wave device having multiple electrode assemblies is described. In particular, Figure 5 A distal portion of a shock wave device is depicted having two electrode assemblies 506, 508. In particular, Figure 5A variation of a shock wave device 500 is depicted, comprising an elongated member 502, a first electrode assembly 506 at a first position along the length of the elongated member 502, a second electrode assembly 508 at a second position along the length of the elongated member 502, and an optional enclosure 504 configured to be fillable with a conductive fluid to sealably enclose the first and second electrode assemblies 506, 508. In some variations, the enclosure may include a membrane and / or a balloon, which may be made of an electrically insulating material that may be non-compliant (e.g., PET, etc.), semi-compliant (e.g., PBAX, nylon, PEBA, polyethylene, etc.), and / or compliant (e.g., polyurethane, silicone, etc.). The enclosure 504 may enclose any number of electrode assemblies.

[0067] The shock wave device 500 may include a fluid lumen (not shown) that communicates with a fluid source that introduces a conductive fluid into the enclosure 506. A voltage source (not shown) having a first terminal 510 and a second terminal 512 may be coupled to the shock wave device 500. As described above, the polarity of the terminals 510, 512 may be varied per pulse or in a predetermined sequence. Energy pulses may be applied to the electrode pairs 506, 508, thereby generating one or more shock waves that may propagate through the fluid to impact the calcified obstruction. Although Figure 5 The shock wave device 500 in FIG. 5 is depicted as having two electrode pairs 506 , 508 , but it should be understood that other variations may have a different number of electrode pairs (eg, 3, 4, 5, 6, or more electrode pairs).

[0068] In some variations, electrode assemblies 506, 508 may each include two inner electrodes positioned circumferentially opposite each other, an insulating sheath having two openings aligned on the two inner electrodes, and an outer common electrode having two openings coaxially aligned with the two openings of the insulating sheath. Figures 6A-6C A variation of the electrode assembly in this configuration is shown, which includes two inner electrodes and an outer common electrode. Each electrode assembly 506, 508 can be configured to generate a pair of directional shock waves, wherein the shock wave generated by the high voltage pulse that reaches the first inner electrode propagates in a direction opposite to the direction of the shock wave generated by the high voltage pulse that reaches the second inner electrode. In some variations, the electrode assemblies 506, 508 can generate shock waves that propagate outward from different locations around the circumference of the elongated member 502. For example, the electrode assembly 506 can generate shock waves that propagate from the left and right longitudinal sides of the elongated member, while the electrode assembly 508 can generate shock waves that propagate from the upper and lower longitudinal sides of the elongated member 502.

[0069] In other variations, electrode assembly 506 may generate a pair of shock waves that propagate outwardly from 0 and 180 degree positions around the circumference of elongated member 502, while electrode assembly 508 may generate a pair of shock waves that propagate outwardly from 60 and 240 degree positions around the circumference of the elongated member. In still other variations, electrode assemblies 506, 508 may each generate a pair of shock waves that propagate outwardly at the same position around the circumference of the elongated member but from different positions along the length of the elongated member. Optionally, one or more radiopaque marker bands may be provided along the length of the elongated member to allow a practitioner to identify the position and / or orientation of shock wave device 500 as it is inserted through the vasculature of a patient.

[0070] It should be understood that a shock wave device having multiple electrode assemblies distributed along the length of a catheter may be suitable for angioplasty to disrupt calcified plaque that may be located along the length of a vessel. A shock wave device having multiple electrode assemblies along the length of a curved elongated member may be suitable for valvuloplasty to disrupt calcified plaque that may be located around the circumference of a valve (e.g., at or around the leaflets of a valve). It should be noted that when electrode assemblies 506, 508 each include two electrode pairs as shown in FIG. 6, Figure 2A The circuit diagram and Figure 2B The simplified layout corresponds electrically to Figure 5 Embodiment of the invention.

[0071] Figure 6A-6B Depicted are top and bottom views, respectively, of one variation of a shock wave device having an electrode assembly 600 that can be configured to generate shock waves in opposite directions. Fig. 6A is a top view of the electrode assembly 600, showing the first inner electrode 602, Figure 6B 600, showing the second inner electrode 604. The first and second inner electrodes share a common electrode 606 and are circumferentially positioned opposite each other (i.e., 180 degrees apart). The first electrode 602 may be connected to a controller ( Figure 6A-6B The first electrode 602 and the common electrode 606 form a first electrode pair, which can generate a first shock wave that propagates outward in a first shock wave direction, and the second electrode 604 and the common electrode 606 form a second electrode pair, which can generate a second shock wave that propagates outward in a second shock wave direction opposite to the first shock wave direction. For a positive pulse provided in the first current direction 616, the current flows from the first electrode pair to the second electrode pair. Similarly, for a negative pulse provided in the second current direction 618 opposite to the first current direction 616, the current flows from the second electrode pair to the first electrode pair.

[0072] The difference in surface area of ​​the conductive regions within the electrode pair can be provided to generate a larger shock wave. For example, the surface area of ​​the edge of the first electrode 602 and the second electrode 604 can be used as the conductive region and can be the portion of the electrode that is most susceptible to wear due to the high energy pulse. An electrode such as a common electrode 606 can form two conductive regions for each of the first and second electrodes 602, 604 having different surface areas. In some variations, the surface area of ​​the conductive regions of the first electrode 602 and the second electrode 604 can be smaller than the surface area of ​​the common electrode 606. Therefore, the life of the electrode assembly 600 can depend on the consumption rate of the smaller electrodes 602, 604.

[0073] When an energy pulse is applied to the electrode pair to form a shock wave, corrosion of the electrode material from the inner and outer electrodes can increase the distance between the electrodes in the electrode pair until a plasma arc is no longer possible. At this point, the electrode pair has failed and reached the end of its useful life. As discussed in further detail below, the extent of corrosion and wear can be determined by measuring one or more of a voltage drop, a voltage pulse width, a low voltage analog of a voltage pulse width, and / or any signal indicating the duration of (or related to) a high voltage pulse on either side of the electrode pair.

[0074] Figure 6C A perspective view of the outer common electrode 606 is depicted. As shown therein, the first opening 612 can be positioned directly opposite the second opening 614. The outer common electrode 606 can have the second opening 614 coaxially aligned on the second inner electrode, and the first inner electrode 604 can be coaxially aligned with the first opening 612 of the outer common electrode 606. This configuration can generate a first shock wave that propagates outward in a first direction and a second shock wave that propagates outward in a second direction opposite the first direction.

[0075] Back to Fig. 6A and 6B , the wires 608, 610 can be electrically insulated along their length (e.g., by an insulating coating or sheath made of, for example, polyimide, PEBA, PET, FEP, PTFE, etc.), except for one or more areas where the conductive core of the wire is exposed to contact a portion of the inner electrode and / or the outer electrode. The wires 608, 610 can be made of any conductive material, for example, oxygen-free copper or copper or silver.

[0076] Figure 7A-7BDepicted are top and bottom views of one variation of a shock wave device having a first electrode assembly 700 and a second electrode assembly 750 that can be configured to generate shock waves along the length of the shock wave device. The electrode assemblies 700, 750 can be connected in series relative to each other such that activating the first electrode assembly 700 also activates the second electrode assembly 750. In some variations, it may be desirable to have multiple shock wave sources without as many wires as possible and to use fewer terminals on a controller. For example, connecting two electrode assemblies in series can allow the shock wave device to generate up to four different shock waves simultaneously using only two voltage output terminals (e.g., one positive channel and one negative channel). Additionally, reducing the number of wires extending along the length of the elongated member can allow the elongated member to bend and contract more freely as it is advanced through the patient's vasculature (e.g., can allow for a smaller turning radius).

[0077] Fig. 7A is a top view of the electrode assemblies 700 , 750 , wherein the first inner electrode 706 and the fourth inner electrode 754 are depicted. Figure 7B 7 is a bottom view of the electrode assembly 700, 750, showing the second inner electrode 704 and the third inner electrode 752. The first and second inner electrodes 702, 704 share the first common electrode 706 and are positioned circumferentially opposite each other (i.e., 180 degrees apart). The third and fourth inner electrodes 752, 754 share the second common electrode 756 and are also positioned circumferentially opposite each other. Alternatively, the inner electrodes and electrode assemblies may be offset from each other in some other manner as described above.

[0078] The first electrode 702 and the first common electrode 706 form a first electrode pair that can generate a first shock wave that propagates outward in a first shock wave direction, and the second electrode 704 and the first common electrode 706 form a second electrode pair that can generate a second shock wave that propagates outward in a second direction. Similarly, the third electrode 752 and the second common electrode 756 form a third electrode pair that can generate a third shock wave that propagates outward in a third direction, and the fourth electrode 754 and the second common electrode 756 form a fourth electrode pair that can generate a fourth shock wave that propagates outward in a fourth direction.

[0079] Figure 7A-7B The first and second electrode assemblies 700, 750 in the embodiment may be connected in series. The first electrode 702 may be connected to a first voltage output terminal V01 (V02) of a voltage source of a controller via a first wire 708. Figure 7A-7B704 (not shown). The second electrode 704 may be connected to the third electrode 752 via a second wire 710 (e.g., an interconnect wire). The fourth electrode 754 may be connected to the second voltage output terminal V02 of the voltage source of the controller via the third wire 712. Therefore, for a positive pulse provided in the first current direction 714, the current flows from the first electrode pair (in ascending order) to the fourth electrode pair. Similarly, for a negative pulse provided in the second current direction 716 opposite to the first current direction 714, the current flows from the fourth electrode pair (in descending order) to the first electrode pair. The size of each of the first to fourth electrodes 702, 704, 752, 754 may be smaller than the first and second common electrodes 706, 756. In some variations, the size may refer to the total size of the electrode and / or the surface area of ​​the conductive area of ​​the electrode. Therefore, the life of the electrode assemblies 700, 750 may depend on the consumption rate of the smaller electrodes 702, 704, 752, 754.

[0080] Any shock wave device described herein can be provided in a shock wave system suitable for angioplasty or valvuloplasty. A shock wave system (not shown) can include a shock wave device, a catheter, a high voltage pulse generator (e.g., a voltage source), and / or a cover configured to be filled with a conductive fluid. The catheter can have a wire lumen passing therethrough. In some variations, the high voltage pulse generator can be a pulse power source of 0.1 kV to 10 kV, for example, a pulse power source of 2 kV to 6 kV.

[0081] II. Methods

[0082] Methods for forming shock waves are generally described herein. Any shock wave device described herein can be used for angioplasty and / or valvuloplasty. The methods described herein can include advancing a guide wire from an entry site of a patient (e.g., an artery in the groin region of the leg) to a target area of ​​a blood vessel (e.g., an area with calcified plaque that needs to be destroyed). The shock wave device can include an axially extending elongated member having a guide wire lumen, an electrode pair including a first electrode and a second electrode, and / or an electrode assembly disposed along the length of the elongated member. The electrode pair and / or electrode assembly can be any electrode described herein.

[0083] In some variations, the balloon can collapse on the elongated member as the device is advanced through the vasculature. In some variations, the position of the shock wave device can be determined by X-ray imaging and / or fluoroscopy. When the shock wave device reaches the target area, the balloon can be filled with a conductive fluid (e.g., saline and / or saline mixed with a contrast agent). For example, a series of pulses can be delivered to the first electrode pair and / or the electrode assembly to generate shock waves that can destroy calcified plaque.

[0084] In some variations, the current flows through the electrode pairs and / or electrode assemblies in a first direction for a portion of the pulses in the series, and flows through the electrode pairs and / or electrode assemblies in a second direction opposite to the first direction for the remaining pulses in the series. In one variation, a first current flow direction can be provided for at least one of the pulses. In another variation, a first current flow direction can be provided for at least about 5% of the pulses. In another variation, a first current flow direction can be provided for at least about 10% of the pulses. In another variation, a first current flow direction can be provided for at least about 15% of the pulses. In another variation, a first current flow direction can be provided for at least about 20% of the pulses. In another variation, a first current flow direction can be provided for at least about 25% of the pulses. In another variation, a first current flow direction can be provided for at least about 30% of the pulses. In yet another variation, a first current flow direction can be provided for at least about one-third of the pulses. In another variation, a first current flow direction can be provided for at least about 40% of the pulses. In another variation, a first current flow direction can be provided for at least about 45% of the pulses. In yet another variation, the first current flow direction may be provided for at least about half of the pulses.

[0085] In still other variations, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:6. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:6. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 3:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 7:8. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 1:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 2:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 4:9. In another variation, the ratio of the current flow of the pulse in the first direction to the second direction may be about 5:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be approximately 7:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be approximately 8:9. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be approximately 1:12. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be approximately 1:16. In another variation, the ratio of current flow in the first direction of the pulse to the second direction may be approximately 1:32. The number of pulses in each current flow direction (e.g., the ratio of current flow in the first direction to the second direction) may be determined based on the expected life of the shock wave device, shock wave uniformity, shock wave energy, etc.

[0086] There is no particular limit to the number of changes in the direction of current flow. In some cases, the direction of current flow can be switched according to the ratio of pulses in the first direction to the second direction. In other cases, the direction of current flow can change randomly for each pulse, as long as the total number of pulses maintains a predetermined current flow direction ratio. Therefore, even if the number of pulses in each direction is equal, the direction of current flow does not need to be switched for each pulse. Averaging the current flow direction of alternating pulses can increase the durability of smaller electrodes by about one-fold, thereby increasing the life of the electrode assembly by about one-fold. Even when the electrodes in the electrode pair are of equal size, alternating the current flow direction so that each electrode receives approximately the same number of positive pulses will distribute the wear on the two electrodes, thereby increasing the durability of the electrode pair by about one-fold.

[0087] Furthermore, the shock waves output from different electrode pairs can, on average, have a more uniform intensity because the polarity switching allows each electrode pair to receive a positive pulse. This allows for more predictable shock waves with less variation in shock wave intensity.

[0088] The progress of plaque rupture can be monitored by X-ray imaging and / or fluoroscopy. If the calcified region is longer than the length of the elongated member with the electrode assembly, and / or if the calcified region is too far from the electrode assembly to receive the full force of the generated shock waves, the shock wave device can be moved along the length of the vessel. For example, the shock wave device can be stepped / shifted along the length of the calcified vessel region to sequentially rupture the plaque.

[0089] Voltage and current measurements can be made at the load (here the electrode assembly) to determine the condition of the shockwave device when the pulse is delivered. As discussed in further detail below, measurements including voltage drop, voltage pulse width, and current can be used to determine the condition / life of the shockwave device.

[0090] In some variations, the polarity switching of the pulses can be based on the condition of the electrodes in the shock wave device. For example, a measurement related to the voltage drop, such as the voltage pulse width, which can be related to the condition of the electrodes, can be used to determine the direction of current flow for a series of pulses. For example, a first voltage pulse width can be measured across an electrode pair for a first current direction, and a second voltage pulse width can be measured across the electrode pair for a second current flow direction. The difference between the first voltage pulse width and the second voltage pulse width, if any, can indicate a difference in electrode wear. In some cases, a difference in the degree of electrode corrosion between a pair of electrodes can result in a shortened life of the entire shock wave device. By switching the direction of current flow based on the measured voltage pulse width to balance the wear between the first and second electrodes, the life of the shock wave device can be extended.

[0091] In some variations, the current flow direction of a series of pulses (e.g., the polarity of each pulse in a series of voltage pulses) can be selected based on the measured voltage pulse width. For example, the current flow direction can be selected so that the difference between the voltage pulse width across the electrode pair when the current flows in the first direction and the voltage pulse width when the current flows in the second direction is within a predetermined threshold. In other variations, the current flow direction can be selected so that the voltage pulse width across the electrode pair when the current flows in the first direction is substantially equal to the voltage pulse width across the electrode pair when the current flows in the second direction. The ratio of the pulse current flow in the first direction to the second (opposite) direction (i.e., the polarity ratio) can be determined at least in part by the measured voltage pulse width. For example, if the voltage pulse width measured in the first current direction (i.e., the first polarity) meets or exceeds a predetermined threshold, the controller can determine that the first electrode of the electrode pair has a greater degree of corrosion than the second electrode of the electrode pair. Then, the controller can adjust the polarity ratio so that the second current flow direction (i.e., the second polarity) increases compared to the first current flow direction. This can help reduce or stabilize the corrosion rate of the first electrode so that the entire electrode pair can be more durable (eg, have a longer life) compared to a shock wave system that does not switch polarity and / or adjust polarity ratios.

[0092] The electrode assemblies of the shock wave device may be connected in series and may be activated simultaneously and / or sequentially, as described above. For example, a pair of electrode assemblies may be connected in series and activated simultaneously or sequentially.

[0093] Once the calcified area has been adequately treated, the balloon can be further inflated or deflated, and the shock wave device and guidewire can be withdrawn from the patient. Wear of the shock wave device can be assessed by visual inspection under a microscope.

[0094] III. Examples

[0095] In the following example, test results are provided to electrodes to compare power delivery to a set of electrodes receiving with a constant polarity for each pulse (static device) and alternating polarity as described above (switching device). Current, voltage, energy measurements as a function of pulse and visual inspections were taken from an 8-gap copper coil transmitter to determine corrosion, electrode integrity and electrode life.

[0096] After pulsing the device, a bright field microscopy evaluation was performed to visually inspect the electrodes for wear. It was determined that the positive terminal in the electrostatic device consumed more conductor than the negative terminal. The switching device had more uniform wear than the static device. In FIGS. 8 and 9A-9B discussed below, the shock wave device was pulsed at a frequency of 0.5 Hz or slower, with a pulse width of about 6 μs.

[0097] Fig. 8Ais an illustrative graph of voltage drop (kV) as a function of pulse number. Voltage drop is defined as the difference between the highest and lowest voltage before current flows (representing voltage loss associated with electrode wear). Fig. 8A As shown, the voltage drop increases with the number of pulses. However, static energy delivery has a much greater voltage drop rate than switching energy delivery indicating more electrode wear. Fig. 8A The rate of voltage drop (slope a) is shown with a linear best fit (R). According to the linear best fit, the voltage loss represented by the voltage drop (kV) for the static energy increases at a much faster rate 800 than the rate 802 for the switching energy. It should be noted that the static shock wave device fails 804 at approximately 40 pulses before the switching shock wave device fails at approximately 70 pulses.

[0098] Despite Fig. 8A The voltage drop is depicted in , but the voltage pulse width is very closely related to the voltage drop, so that the measurement of the voltage pulse width can be used to monitor the life and / or condition of the shock wave device for each pulse. For example, Figure 8B and 8C is an illustrative graph comparing voltage drops according to pulse width variations for non-switching electrode assemblies and switching electrode assemblies, respectively. Figure 8B , line 808 represents a fit of the height correlation between the voltage drop and the pulse width of a non-switching shock wave device. Similarly, line 810 shows a fit of the height correlation between the voltage drop and the pulse width of a polarity switching shock wave device. The width of each pulse (e.g., voltage, current) is defined herein as the first and last time that the pulse reaches 20% of the maximum voltage peak. Similar to the voltage drop (kV), the voltage pulse width increases with the increase in the number of pulses and is an indicator of electrode degradation. In other words, the measured value of the voltage pulse width can be used as a representative of the voltage drop to monitor the condition (e.g., degradation) of the electrode pair. That is, the longer the measured voltage pulse width, the more the electrode with positive polarity corrodes or degrades. Alternatively, the measured value of an internal signal indicating the start and offset of the high voltage pulse across the electrode pair can be used to monitor the condition of the electrode. For example, the internal signal can be a trigger TTL output signal of a high voltage pulse generator.

[0099] Fig. 9A is an illustrative graph of the number of pulses as a function of voltage polarity. As mentioned above, Fig. 9B is an illustrative graph of the energy delivered as a function of the number of pulses. Since more pulses can be provided to a switching device than to a static device, the life of the switching device can be approximately double that of a static device. Fig. 9B, it is apparent that due to the polarity switching, the number of pulses and the average amount of energy delivered by the switching device is significantly greater than that of the static device. For example, the static device provides approximately 40 pulses before the static device fails 900, while the switching device provides approximately 70 pulses before the switching device fails 902.

[0100] The test results show that switching the current flow direction can increase the life and energy delivery of an 8-gap shockwave device compared to a constant current flow direction 8-gap shockwave device. Visual inspection also shows bias wear of the electrodes when a single current flow direction is applied compared to alternating current flow. Experimental testing shows that the voltage pulse width is proportional to the energy voltage drop before the current flows. Therefore, a static device has more voltage loss than a switched device. The voltage pulse width can be used as a metrological tool to monitor the life and / or condition of the shockwave device for each pulse. Therefore, switching the current flow direction can improve the efficiency and / or consistency of the shockwave output by the shockwave device.

[0101] It should be understood that the foregoing is only intended to illustrate the principles of the present invention, and that various modifications, variations, and combinations may be made by those skilled in the art without departing from the scope and spirit of the present invention. Any of the various shock wave device variations disclosed herein may include features described in any other shock wave device or combination of the disclosed devices. Therefore, the present invention should not be limited except by the appended claims. For all of the above variations, the steps of the method need not be performed sequentially.

Claims

1. A shock wave device for treating a lesion in a body, comprising: an axially extending elongated member; a first electrode pair comprising a first electrode and a second electrode, wherein the first electrode pair is carried on the elongated member and is located within the conductive fluid; and A controller coupled to the first electrode pair, the controller comprising a voltage source and a polarity switch, the controller being configured to transmit a series of individual voltage pulses to the first electrode pair so that each of the voltage pulses generates a shock wave in the conductive fluid, wherein, through operation of the polarity switch, the controller causes current to flow through the first electrode pair in a first direction for a portion of the pulses in the series and in a second direction opposite to the first direction for the remaining pulses in the series, and the controller further measures the voltage or current at the first electrode pair and adjusts a ratio of the number of voltage pulses transmitted in the first direction to the number of voltage pulses transmitted in the second direction based on the measurement results, wherein the number of voltage pulses transmitted in the first direction is different from the number of voltage pulses transmitted in the second direction.

2. The device according to claim 1, wherein: The controller measures one of a voltage drop, a voltage pulse width, and a current, and adjusts a ratio of a number of voltage pulses transmitted in a first direction to a number of voltage pulses transmitted in a second direction based on the measurement result.

3. The device according to claim 2, wherein: The controller measures a first voltage pulse width across the first electrode pair for a first current direction and measures a second voltage pulse width across the first electrode pair for a second current direction, and adjusts the ratio of the number of voltage pulses transmitted along the first direction to the number of voltage pulses transmitted along the second direction based on the difference between the measured first voltage pulse width and the second voltage pulse width.

4. The device according to claim 1, wherein: The polarity switch is operated only between the delivery of individual voltage pulses, so that each voltage pulse delivered to the first electrode pair has a single current flow direction.

5. The device of claim 1, further comprising one or more additional electrode pairs connected in series to the first electrode pair.

6. The apparatus of claim 1, further comprising a fluid enclosure surrounding the first electrode pair.

7. The device according to claim 6, wherein: The fluid enclosure includes a balloon surrounding a portion of the elongated member, wherein the balloon is configured to be filled with a conductive fluid, and wherein the first electrode pair is encapsulated within and spaced apart from the balloon.

8. The device according to claim 1, wherein: One or more radiopaque marker bands are disposed along the length of the elongated member.

Images