Intravascular lithotripsy device and system with current fault detection

Abstract

Fault detection of an intravascular lithotripsy (IVL) device and a circuit including one or more transmitters. The balancing current circuit comprises a high voltage power supply, a control device or console, and at least one emitter comprising a pair of electrodes between which a spark is to be generated. Under normal working conditions, voltage is applied through the two conductors, a closed circuit is formed, and current flows between the two conductors when sparks occur. In normal cases, the current IC on the first conductor from the console to the transmitter is the same as the current IR on the second conductor from the transmitter back to the high voltage power supply. In this case, the circuit is in a balanced state. In such a balanced state, there is no sign of current leakage of the circuit. In the imbalance state of the circuit, the current IC is compared with the current IR, showing the current amplitude difference of the pulse over time during the pulse period. Specifically, when the current IR is less than the current IC, there is a circuit imbalance, which indicates a loss or leakage of the current IF.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 455,805, filed March 30, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a catheter system for treating vascular thrombosis or calcification lesions by utilizing energy waves generated by electrodes in a conductive fluid medium. Background Technology

[0004] Catheter systems equipped with angioplasty balloons are typically used to apply physical pressure to calcified lesions within the vascular system by balloon dilation, forcing the calcifications back and adhere to the vessel wall. Some such calcified lesions and thrombi cannot be effectively broken up using angioplasty balloons.

[0005] Recently, catheter systems have been developed, including balloons similar to angioplasty balloons, filled with a conductive liquid medium, such as saline solution, for expanding the balloon to the site of a lesion or thrombus. These catheter systems include one or more pairs of electrodes operably placed within the conductive liquid medium. The electrodes are pulsed with a high-voltage direct current, generating a spark across the gap between the two electrodes with each pulse. The spark in the conductive medium generates an energy wave that propagates through the liquid medium, causing the balloon to physically exert pressure on the lesion or thrombus. This energy propagation includes the generation of microbubbles, which also contribute to the physical force. Such devices are known to provide energy waves to combat lesions or thrombi for the purpose of breaking down calcifications or clots.

[0006] Current catheter systems include a treatment sequence comprising a maximum number of consecutive pulses, followed by a minimum delay time and a hard maximum total pulses associated with the specific catheter. One such product specification is:

[0007]

[0008]

[0009] If treatment is not completed after the maximum total number of pulses for each catheter, the physician must replace the catheter to avoid the resulting adverse consequences, costs, delays, and disruptions.

[0010] Intravascular lithotripsy (IVL) devices can be used for several calcification patterns. Disposable IVL balloon devices are available in different designs and sizes for peripheral nervous system or coronary indications. All designs utilize a reusable power source, such as an IVL generator. One reusable DC generator includes the following specifications:

[0011]

[0012] A disposable device consists of a 0.014-inch compatible guide wire, liquid filled balloon angioplasty catheter that integrates two lithotripsy emitters on the shaft of a 12 mm long balloon segment. The liquid filled balloon (e.g., 50 / 50 saline versus media) is inflated to about 4 atmospheres and then an electrical pulse is provided to the emitters, which produce a high voltage spark to provide therapy. Upon the sound wave, calcium is broken up. SUMMARY

[0013] The present invention relates to fault detection of IVL devices and the electrical circuit comprising one or more emitters, each emitter comprising spaced apart pairs of electrodes. The balanced current circuit comprises a high voltage power supply, a control device or console, and at least one emitter comprising pairs of electrodes between which a spark is generated. As mentioned above, the electrical energy used in intravascular lithotripsy (IVL) devices reaches the order of thousands of volts, tens or even hundreds of amperes. In normal working conditions, the voltage is applied through two conductors, forming a closed circuit, and the current flows between them when the spark appears. In normal conditions, the current IC on the first conductor from the console to the emitter is the same as the current IR on the second conductor from the emitter back to the high voltage power supply. In this case, the circuit is in a balanced state. In this balanced state, there is no indication of current leakage from the circuit. In the unbalanced state of the circuit, the comparison of the current IC with the current IR shows a pulse over time, the difference in the amplitude of the current on the pulse. Specifically, when the current IR is less than the current IC, there is a circuit imbalance, which indicates a loss or leakage of the current IF.

[0014] In one aspect of the invention, a method for determining a fault of an intravascular lithotripsy (IVL) device, the device comprising: a catheter with at least one emitter distal from a control module; a first conductor extending from the control module to the emitter and electrically connected with the emitter; and a second conductor electrically connected from the emitter and extending from the emitter to the control module, the first conductor and the second conductor electrically connected with a high voltage pulse generator through the control module, as a system with the IVL device. Wherein the method comprises: generating a high voltage pulse at the high voltage pulse generator; measuring a supply current through the first conductor, and measuring a return current through the second conductor; and comparing the supply current and the return current to find any imbalance between the supply current and the return current.

[0015] Each emitter includes pairs of electrodes spaced apart from one another for generating a spark between the pairs of electrodes upon high voltage pulse generation. In many cases, multiple pairs of electrodes are arranged in electrical series with one another. Then, a preferred pair performs the measurement step of return current from the last pair of electrodes to the control module through the second conductor. In another preferred arrangement, the measurement step can be performed within the control module.

[0016] In another preferred arrangement, multiple pairs of electrodes can be arranged in electrical parallel with one another, and each of the pairs of electrodes in parallel has a parallel portion of the first conductor, and further wherein the measurement of supply current is done across the multiple parallel portions of the first conductor.

[0017] The measurement step of supply current is done across the first conductor using a supply current sensor, and the measurement step of return current is done across the second conductor using a return current sensor, and the comparison step can use values obtained from each of the supply current and return current sensors.

[0018] The measurement step and comparison step can alternatively be performed by passing the first conductor and the second conductor through a ferromagnetic ring, such that current passing through the first conductor generates a current in the ferromagnetic ring in one direction, and current passing through the second conductor generates a cancelling current in the ferromagnetic ring in the opposite direction, and the imbalance is indicated by the current in the ferromagnetic ring in one direction.

[0019] If it is determined that the supply current and return current are in a non-imbalance state, but the measurements indicate that the supply current and return current have decreased compared to measurements over a period of time, such a determination can indicate damage to the pairs of electrodes.

[0020] The method can also use a differential amplifier circuit that receives the measurements of the supply current sensor and the return current sensor, and amplifies the difference between them, and then compares the amplified difference to a threshold to determine any imbalance.

[0021] Alternatively, the method can also use an inductive amplifier that receives a current value from the ferromagnetic ring and amplifies the current value, and then the amplified current value can be compared to a threshold to determine any imbalance.

[0022] In another aspect of the invention, a system can determine a malfunction of an intravascular lithotripsy (IVL) device, the device including a catheter with at least one emitter remote from a control module, a first conductor extending from the control module to the emitter and electrically connected therewith, and a second conductor electrically connected from the emitter and extending from the emitter to the control module, the first conductor and the second conductor electrically connected through the control module with a high voltage pulse generator, as a system with the IVL device, the system being connectable at the high voltage pulse generator with a high voltage pulse for generating a spark at the emitter by the high voltage pulse, the system further including a sensor for measuring a supply current through the first conductor, and a sensor for measuring a return current through the second conductor, such that the supply current can be compared with the return current to discover any imbalance between the supply current and the return current.

[0023] Each emitter includes a pair of electrodes spaced from one another for generating a spark between the pair of electrodes upon generation of the high voltage pulse. In many cases, multiple pairs of electrodes are arranged in electrical series with one another. Then, the preferred pair performs the measurement step with the return current from the last pair of electrodes to the control module through the second conductor. In another preferred arrangement, the measurement step can be performed within the control module.

[0024] In this system, the multiple pairs of electrodes can be arranged in electrical parallel with one another, and each of the pairs of electrodes in parallel has a parallel portion of the first conductor, and further wherein the sensing of the supply current is done on at least one of the parallel portions of the first conductor.

[0025] In particular, the sensing of the supply current is done on the first conductor, and the sensing of the return current is done on the second conductor, such that the comparison can use values obtained from each of the supply current sensor and the return current sensor.

[0026] In an alternative arrangement, the first conductor and the second conductor pass through a ferromagnetic ring, such that current passing through the first conductor generates a current in the ferromagnetic ring in one direction, while current passing through the second conductor generates a cancelling current in the ferromagnetic ring in the opposite direction, the imbalance being indicated by the current in the ferromagnetic ring in one direction.

[0027] The system further includes a differential amplifier circuit that receives the measurements of the supply current sensor and the return current sensor, and amplifies the difference between them, and then compares the amplified difference to a threshold to determine any imbalance.

[0028] Alternatively, the system can further use an inductive amplifier that receives a current value from the ferromagnetic ring and amplifies it, and then the amplified current value can be compared to a threshold to determine any imbalance.

[0029] In another aspect of the application, a system for determining a fault in an intravascular lithotripsy (IVL) device, the device can include: a catheter with at least one emitter remote from a control module, the emitter including an electrode pair having electrodes spaced apart from one another for generating a spark between the electrode pair upon high voltage pulse generation, the IVL device further including: the catheter with at least one emitter remote from the control module; a first conductor extending from the control module to the emitter and electrically connected therewith; and a second conductor electrically connected with the emitter and extending therefrom to the control module, the first and second conductors being electrically connected with a high voltage pulse generator through the control module, as a system with the IVL device, the system being connectable at the high voltage pulse generator with a high voltage pulse for generating a spark at the emitter by the high voltage pulse, the system further including a sensor for measuring a supply current through the first conductor, and a sensor for measuring a return current through the second conductor, enabling a comparison of the supply current with the return current to discover any imbalance between the supply current and the return current, wherein: (a) the sensing of the supply current is done on the first conductor and the sensing of the return current is done on the second conductor, enabling the comparison to use values obtained from each of the supply current sensor and the return current sensor, or (b) the first and second conductors pass through a ferromagnetic ring, such that current passing through the first conductor generates a current in the ferromagnetic ring in one direction, while current passing through the second conductor generates a cancelling current in the ferromagnetic ring in the opposite direction, the imbalance being indicated by the current in the ferromagnetic ring in one direction. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A system for intravascular lithotripsy is shown in accordance with one aspect of the application.

[0031] Figure 2 A balloon for intravascular inflation is shown in accordance with one aspect of the application for providing intravascular lithotripsy.

[0032] Figure 3 A current circuit for an IVL device is shown schematically in accordance with one aspect of the application, the first and second conductors being balanced in current flow.

[0033] Figure 4 A plot of high voltage pulse versus time is shown, and a balancing circuit is shown as Figure 3

[0034] Figure 5 A current circuit for an IVL device is shown schematically in accordance with one aspect of the application, the first and second conductors being unbalanced in current flow.

[0035] Figure 6 A plot of high voltage pulse versus time is shown, and a balancing circuit is shown as​Figure 5 The imbalance circuit is shown.

[0036] Figure 7 A graph showing a series of high voltage pulses over time is shown, and the balancing circuit is shown on a plurality of peaks, followed by detection of an imbalance.

[0037] Figure 8 A subcircuit of one aspect of the invention is shown schematically for determining a balanced or imbalanced current within the IVL device circuit.

[0038] Figure 9 A graph showing a series of high voltage pulses over time is shown, and the balancing circuit, damage to the balancing circuit, and the difference between detection of an imbalance are shown.

[0039] Figure 10 is a schematic diagram of another current circuit for an IVL device according to another aspect of the invention, with a first conductor and a second conductor passing through a ferromagnetic ring for detection of an imbalance in the circuit.

[0040] Figure 11 is a schematic diagram of a current circuit for an IVL device similar to Figure 10 but with multiple conductors from the control console to the IVL emitter.

[0041] Figure 12 is a schematic diagram of a current circuit for an IVL device similar to Figure 10 and Figure 11 but with multiple circuits to and from the IVL emitter. DETAILED DESCRIPTION

[0042] The present invention relates to a type of IVL device including an electrode or lithotripsy emitter that generates acoustic waves from arc discharge between electrode assemblies, but can also include devices that generate acoustic energy within a balloon by a laser energy source. Examples of such laser systems have been described in U.S. Patents Nos. 11,058,492 and 11,246,569 (the entire contents of which are incorporated by reference). Examples of electrical induction systems have been described in U.S. Patents Nos. 8,728,091, 9,642,673, and 10,850,078, and published U.S. Patent Application Publication No. 2022-0054194 (the entire contents of which are incorporated by reference).

[0043] Referring to the drawings, Figure 1 and Figure 2A system 10 according to the present application is shown, which includes a console or power supply 12 (in the form of an electrical generator, but which can instead be in the form of a laser system), a handle 14 with a treatment delivery controller 15, and a catheter 20 with two lithotripsy emitters 22 (shown in the form of a pair of arc-shaped electrodes, but which can instead comprise optical or laser emitters), and a balloon 24 filled with a liquid. An optional marker band B can be provided. The catheter 20 preferably includes a central tube 26 which defines a guide wire lumen 27 through which a guide wire G is used to deliver the balloon 24 along the guide wire G to a desired location. A sheath 28 surrounds the central tube 26 and defines a delivery lumen 29 through which saline can be controllably delivered for inflation of the balloon 24. The lumen 29 provides a concentric space around the central tube 26 in which electrode wires (not shown) and other components can extend from the controller 15 to the emitters 22 according to the present application and as described below. The proximal end of the sheath 28 is connected to a hub 17 which can include any number of ports allowing the electrode wires and saline for inflation, the guide wire G, and other required components to access the lumen 29.

[0044] The balloon 24 can be placed in a deflated state to more easily pass through the patient's vasculature to the calcification site. In use, the balloon 24 will be inflated to a typical angioplasty pressure (e.g., 4 atmospheres) and the treatment activated by the delivery controller 15.

[0045] Figure 2 The balloon 24 is shown inflated to a treatment delivery state at which time the lithotripsy emitters 22 can be "fired" to break up the vascular calcification C. The optional marker band B can be provided to provide visualization and correct positioning by use of known imaging techniques. The balloon 24 is inflated to a typical angioplasty pressure (e.g., 4 atmospheres) and the treatment is performed. During or just after the treatment is performed, the balloon 24 can be allowed to naturally expand to clear the vessel for blood flow.

[0046] According to the treatment protocol, the controller 15 is used to generate one or a series of voltage pulses. A high voltage pulse is provided to one of the emitters 22, which includes a pair of spaced-apart electrodes, and then, according to the illustrated embodiment, to the second emitter 22, which also includes a pair of spaced-apart electrodes. The high voltage pulse creates a spark between the first pair of electrodes and the second pair of electrodes in the balloon 24 in sequence. The weakly conductive saline solution within the balloon 24 allows the high voltage spark between each pair of electrodes, thereby creating an energy wave that propagates within the balloon and toward the vascular calcification. The "high" voltage used in the IVL device of the present application is preferably above 500 V, more preferably above 1000 V, and most preferably above 2000 V.

[0047] Any spark generated in the balloon 24 located within the patient's vasculature will also generate a visible or detectable light event. Such a light event can be detected at wavelengths outside of the visible light. Further, it is understood that when a high voltage pulse is initiated on a hot electrode pair prior to the actual spark event, a visible or detectable light leader can emanate from the grounded electrode of any electrode pair. This leader is similar to what is observed from a conductive object prior to a lightning strike. It is the purpose of the present invention to monitor these visible or detectable light events as feedback to the controlled generation of high voltage sparks. Understanding the time of generation of this leader and the actual spark in one or more electrode pairs after the high voltage pulse is generated can lead to design changes in the electrode pairs and other components within the balloon for energy wave propagation. It is the purpose of the present invention to better predict the time of spark generation upon high voltage pulse transmission by sensing any optical phenomena that can predict the actual time of spark occurrence.

[0048] It is also contemplated that a catheter not including a balloon can be used in accordance with the present invention. Such a catheter preferably includes a lumen 29 for delivering saline to a controlled volume including one or more emitters 22. This controlled volume can be created by the structure of the patient's vasculature and the distal end of the catheter in the area of the emitters. Saline can be provided to fill this controlled volume or saline can flow within or out of this controlled volume at a controlled flow rate. It is also contemplated that a partial balloon, from which saline fluid flow can emanate from the open distal end of the partial balloon. This partial or open balloon design is useful for forward facing electrode systems such as disclosed in U.S. Provisional Patent Application No. 63 / 416,231 filed October 14, 2022, the entire contents of which are incorporated herein by reference. In the case of catheter 20 having a balloon 24, the controlled volume is disposed within the volume of balloon 24.

[0049] As Figure 2As shown, the optical fiber 30 can extend within the lumen 29 to a desired point within the balloon 24 for sensing light generated by the spark within the balloon 24. The proximal end of the optical fiber 30 is preferably optically coupled to an optical detector, which preferably provides an amplified signal of the sensed light. Optical fibers are well known to include an optical core in which light can propagate and are surrounded by a cladding layer. The cladding layer can be further surrounded by a protective layer. Light generated by the spark or pilot, for example, can propagate along the optical core and be sensed by an optical detector, such as a photodiode. By detecting the occurrence of the spark or pilot directly in the observed visible or detectable light (through the optical fiber), the life of the IVL device can potentially be improved by varying the power used for each spark and optimizing the strength of the spark. It is contemplated that reducing the strength and duration of the spark can contribute to the life of the IVL and can reduce the adverse effects of heat generated by the spark. Control aspects and responsiveness can also be improved by knowing the strength of the spark and the time relative to the high voltage pulse.

[0050] An additional optional use of the optical fiber 30 and optical sensor is to detect microbubbles in the saline solution within the balloon 24, which can interfere with the passage of the shockwave. It is understood that microbubbles can be generated by the high voltage spark and the resulting energy wave. It is also understood that when a certain amount of energy is applied to microbubbles suspended in a solution, the microbubbles can collapse. Sonoluminescence is a phenomenon in which the collapse of microbubbles results in the generation of detectable light and sound waves. In this case, a first pulse can generate an energy wave and microbubbles in the saline solution within the balloon 24. A subsequent pulse can generate another energy wave and microbubbles, but can also cause the microbubbles in the saline solution from the previous pulse to collapse. This event can generate additional detectable light that can be detected by the optical fiber 30. For example, this light generated from the collapse of the microbubbles can be detected at a different wavelength than the light detectable from the spark. Optical filters can be used depending on the optical phenomenon detected to understand the light emitted at a particular wavelength. For example, sodium ion excitation in a saline solution can result in the emission of light at a wavelength of 589 nm (yellow-orange). Detecting light at this wavelength can be indicative of the characteristics of the spark and allow for adjustments to the spark generation.

[0051] In the event that one or more emitters 22 are energized by the controller 15 and the optical fiber 30 does not detect light, this would be an example of a fault condition. This fault is caused by a current leak in which the current from the wire electrode to the one or more emitters 22 within the balloon 24 is different (in this case greater) than the current returning from the emitters 22 within the balloon 24 to the controller 15. Thus, one aspect of the present invention is to measure the current balance from the emitters 22 to the electrode wires to look for any current faults. In the event that there is no current passing through the electrode gap between a pair of electrodes of an emitter and no spark is generated, the current flow from the emitter 22 can be zero. This means that the emitter 22 is broken or damaged or there is a current leak somewhere before the emitter 22. In the event that there is current flowing through one or more emitters 22, whether or not there is a spark, the current difference or imbalance between the current supplied to the emitter and the current flowing from the emitter can also be a fault, indicating a current leak somewhere along the circuit.

[0052] Reference is now made to Figure 3 and Figure 4 showing a balanced current circuit 50, including a high voltage power supply 52, a control device or console 54, and an emitter 56, which includes a pair of electrodes between which a spark is to be generated. As noted above, the electrical energy used in intravascular lithotripsy (IVL) devices reaches the order of thousands of volts, tens or even hundreds of amperes. In normal working conditions, the circuit 50 forms a closed loop, a voltage is applied through two conductors, and a current flows between them when a spark occurs. In normal conditions, the current IC on a first conductor 58 from the console 54 to the emitter 56 is the same as the current IR on a second conductor 60 from the emitter 56 back to the high voltage power supply 52. In this case, the circuit 50 is in a balanced state. In this balanced state, there is no indication of a current leak of the circuit 50. Figure 4 The balanced state of the circuit 50 is shown, the number of amperes of the high voltage pulse as a function of time, and the current IC is equal to the current IR. It will be appreciated that there will be a slight difference between the IC current and the IR current of any circuit, and a threshold is preferably used when comparing the IC current and the IR current based on empirical information or otherwise.

[0053] In Figure 5 and Figure 6In the context of FIG. 5, circuit 50 is shown with current IC from control console 54 to emitter 56 and current IR from emitter 56 back to high voltage power supply 52. In the event of a spark at emitter 56, IR and IC should be the same or substantially the same, as described above. However, a third current is shown as current IF, which is the current leakage of circuit 50, which can occur outside or inside of control console 54 and through any other conductive medium. This current leakage IF can still allow a spark to be generated at emitter 56, but the energy can be lower and the energy wave acting on the lesion is reduced, as described above. Figure 6 An unbalanced condition of circuit 50 is shown in which a comparison of current IC to current IR shows the variation of the pulse over time, the difference in current amplitude on the pulse. Specifically, current IR is less than current IC by current IF, in the aggregate sense, taking into account small variations in the system.

[0054] The current through the conductors (e.g., conductor 58 and conductor 60) is measured by any current sensor, such as are commercially available. Examples include current sense resistors and voltage amplifiers for measuring voltage differences. Other examples include magnetic coils or systems including Hall effect sensors. In one embodiment of a system according to the present application, as shown schematically in FIG. 6, a first current sensor 62 is disposed along first conductor 58 from control console 54 to emitter 56, and a second current sensor 64 is disposed along second conductor 60 from emitter 56 to high voltage power supply 52. In this manner, current IC and current IR can be directly compared to each other. Current sensors 62 and 64 can be disposed within control console 54, or at any location along the length of first conductor 58 and second conductor 60. Figure 3

[0055] It will be appreciated that a system according to the present application, including current balance monitoring, can determine any such imbalance at any time during or after any number of high voltage spark and energy wave firings. For example, in the context of FIG. 5, a series of three such high voltage pulses is shown over a period of time, the first two pulses having current balance, and the third pulse having current imbalance. The first two pulses as shown include identical curves, which are superimposed on each other, while the curve of the third pulse is shown distinctly from each other, with the amplitude of curve IR being small, and the amplitude of curve IC being larger. This illustrates the current imbalance, the amplitude of which is shown in the lower graph below the third, imbalanced pulse of the graph below. In operation, once such an imbalance is determined, this imbalance within a series of pulses can control the cessation of any further pulses. It is also contemplated that a pulse can even be terminated within the pulse if an imbalance is detected during the pulse. Figure 7

[0056] Figure 8 ​​An embodiment of a system sub-circuit 70 is shown schematically that can be used to determine imbalance from a comparison of the current IC and the current IR. In this example, a current amplifier 72 receives current values from current sensors (e.g., 62 and 64) to amplify any difference between IC and IR. The difference is then provided to a comparator 74 that compares the amplified difference value to a threshold value. If the amplified difference value is greater than the threshold value, then imbalance is determined. Such amplifiers and comparators are well known and commercially available. It will be appreciated that the comparator can be used alone without amplification, and that the threshold value can be as low as zero and can be determined empirically or by other methods.

[0057] It is also noted that with current sensors on the first conductor 58 and the second conductor 60, normal wear over time can also be detected. As Figure 9 shown, the top graph shows a plurality of pulses over time, and the amplitude of the two current curves of IC and IR during each pulse. The first pulse, as described above, shows the two curves overlapping together, indicating no imbalance or other change. The second pulse also shows the two curves overlapping together, but with a smaller amplitude than the first pulse. In comparing the first and second pulses, which can be any number of pulses over a period of time and between them, the second pulse shows wear within the system (console or catheter) that increases the resistance within the first conductor 58 and the second conductor 60. It is contemplated that comparing the amplitude of the pulses over time of a plurality of current sensors can provide feedback information of system wear or electrode wear that also facilitates determining excessive wear of the system or electrodes that need to be replaced. The third pulse illustrates imbalance as described above, with the difference in amplitude below the graph of the third pulse.

[0058] In another aspect of the application, the system can utilize non-contact measurements to determine imbalance. In the system described above, the current sensors 62, 64 provide current data, amperage, at a plurality of locations for comparison with each other. In Figure 10 In the above-described system, the current sensors 62, 64 provide current data, amperage, at a plurality of locations for comparison with each other. In Figure 10As shown, the current IC passing in the direction from the console 154 to the transmitter 156 passes through the center opening of the ferromagnetic ring 166 in this direction. The current IR passing in the direction from the transmitter 156 to the high voltage power supply 152 passes through the center opening of the ferromagnetic ring 166 in the opposite direction. A current passing through the center of the ferromagnetic ring 166 in one direction will generate a current in one direction within the ferromagnetic ring 166 by magnetic flux interaction. A current passing through the center of the ferromagnetic ring 166 in the opposite direction will likewise generate a current in the opposite direction within the ferromagnetic ring 166. If the two currents passing through the center opening of the ferromagnetic ring are the same, no current will be generated within the ring. If the current in the first conductor 158 differs from the current in the second conductor 160, a current in one direction or the other will be generated in the ferromagnetic ring based on the difference. Any such difference can be the result of system leakage IF, and is also indicated in Figure 10 As described above, the subcircuit 170 can first amplify any current generated within the ferromagnetic ring 166 at 172, and compare the value to a threshold at 174 to determine imbalance. Variations are contemplated as described above.

[0059] Figure 11 Variations of the system of Figure 10 are shown, in which multiple conductors 158 and 159 extend from the console 155 to a pair of parallel transmitters 156 and 157. Both transmitters 156 and 157 are electrically connected by return conductors 160 to the high voltage power supply 152. Multiple return conductors are also contemplated. In any case, the current generated within the ferromagnetic ring 166 is the same as described above, even if multiple conductors are used for the current IC passing through the ferromagnetic ring 166.

[0060] In contrast to the system of Figure 11 , the system 250 of Figure 12 may include multiple subsystems, each including circuitry similar to the system of Figure 10 . The subsystems can share the high voltage power supply 252 and the console 254. Each subsystem can have its own first conductors 258 and 259 extending through ferromagnetic rings 266 and 267 to transmitters 256 and 257, and second conductors 260 and 261 returning from the transmitters 256 and 257 to the high voltage power supply 252. Each ferromagnetic ring 266, 267 can then have an independent subcircuit (not shown) like the subcircuit 170 for determining imbalance. Figure 12 The advantage of the system over the system of Figure 11 is that it is easier to identify specific conductors and transmitters.

Claims

1. A method for determining a failure of an intravascular lithotripsy (IVL) device, the device comprising: a conduit with at least one emitter remote from a control module; a first conductor extending from the control module to the emitter and electrically connected therewith; and a second conductor electrically connected with the emitter and extending from the emitter to the control module, the first and second conductors being electrically connected with a high voltage pulse generator through the control module, as a system with the IVL device, the method comprising: generating a high voltage pulse at the high voltage pulse generator; measuring a supply current through the first conductor and a return current through the second conductor; and comparing the supply current and the return current to find any imbalance between the supply current and the return current.

2. The method of claim 1, wherein the emitter comprises a pair of electrodes spaced from one another for creating a spark between the pair of electrodes upon high voltage pulse generation.

3. The method of claim 2, wherein multiple pairs of electrodes are disposed in electrical series with one another, and the step of measuring is done on the return current through the second conductor from the last pair of electrodes back to the control module.

4. The method of claim 3, wherein the step of measuring is done within the control module.

5. The method of claim 2, wherein multiple pairs of electrodes are disposed in electrical parallel with one another, and each of the pairs of electrodes in parallel has a parallel portion of the first conductor, and further wherein the measurement of the supply current is done on the multiple parallel portions of the first conductor.

6. The method of claim 1, wherein the step of measuring the supply current is done on the first conductor by using a supply current sensor, and the measurement of the return current is done on the second conductor by using a return current sensor, and the step of comparing uses values obtained from each of the supply current sensor and the return current sensor.

7. The method of claim 1, wherein the steps of measuring and comparing are done by threading the first and second conductors through a ferromagnetic ring such that current through the first conductor generates a current in one direction within the ferromagnetic ring, while current through the second conductor generates a counter current in the opposite direction within the ferromagnetic ring, imbalance being indicated by the current in the one direction in the ferromagnetic ring.

8. The method of claim 2, wherein after the step of measuring, it is determined that the supply current and the return current are in a non-imbalance state, but the results of the measurement indicate that the supply current and the return current are reduced compared to measurements over a period of time, which indicates damage to the pair of electrodes.

9. The method of claim 6, further comprising a differential amplifier circuit that receives the measurements of the supply current sensor and the return current sensor and amplifies a difference between the measurements of the supply current sensor and the return current sensor, and then compares the amplified difference to a threshold to determine any imbalance.

10. The method of claim 7, further comprising an inductive amplifier that receives a current value from the ferromagnetic ring and amplifies the current value, and then compares the amplified current value to a threshold to determine any imbalance.

11. A system for determining a failure of an intravascular lithotripsy (IVL) device, the device comprising: a conduit with at least one emitter remote from a control module; a first conductor extending from the control module to the emitter and electrically connected therewith; and a second conductor electrically connected with the emitter and extending from the emitter to the control module, the first and second conductors being electrically connected with a high voltage pulse generator through the control module, as a system with the IVL device, the system being connectable with high voltage pulses at the high voltage pulse generator for generating sparks at the emitter by the high voltage pulses, the system further comprising a sensor for measuring a supply current through the first conductor, and a sensor for measuring a return current through the second conductor, enabling a comparison of the supply current with the return current to find any imbalance between the supply current and the return current.

12. The system of claim 11, wherein the emitter comprises pairs of electrodes spaced from one another for generating the sparks between the pairs of electrodes upon high voltage pulse generation.

13. The system of claim 12, wherein multiple pairs of electrodes are arranged in electrical series with one another, and the sensor for measuring return current is done on the return current through the second conductor from the last pair of electrodes to the control module.

14. The system of claim 13, wherein the supply current sensor and the return current sensor are arranged within the control module.

15. The system of claim 12, wherein multiple pairs of electrodes are arranged in electrical parallel with one another, and each of the pairs of electrodes in parallel has a parallel portion of the first conductor, and further wherein the sensing of the supply current is done on at least one of the parallel portions of the first conductor.

16. The system of claim 11, wherein the sensing of the supply current is done on the first conductor, and the sensing of the return current is done on the second conductor, enabling the comparison to use values obtained from each of the supply current sensor and the return current sensor.

17. The system of claim 11, wherein the first conductor and the second conductor pass through a ferromagnetic ring such that current passing through the first conductor generates current in the ferromagnetic ring in one direction and current passing through the second conductor generates a canceling current in the ferromagnetic ring in the opposite direction, imbalance being indicated by current in the ferromagnetic ring in the one direction.

18. The system of claim 16, further comprising a differential amplifier circuit that receives measurements of the supply current sensor and the return current sensor and amplifies a difference between the measurements of the supply current sensor and the return current sensor such that the amplified difference can then be compared to a threshold to determine any imbalance.

19. The system of claim 17, further comprising an inductive amplifier that receives a current value from the ferromagnetic ring and amplifies the current value such that the amplified current value can then be compared to a threshold to determine any imbalance.

20. A system for determining a failure of an intravascular lithotripsy (IVL) device, the device comprising: A catheter with at least one emitter remote from a control module, the emitter including an electrode pair with electrodes spaced from each other for generating a spark between the electrode pair upon high voltage pulse generation, the IVL device further including: a first conductor extending from the control module to the emitter and electrically connected with the emitter; and a second conductor electrically connected with the emitter and extending from the emitter to the control module, the first conductor and the second conductor being electrically connected with a high voltage pulse generator through the control module, as a system with the IVL device, the system being connectable with high voltage pulses at the high voltage pulse generator for generating a spark at the emitter by the high voltage pulses, the system further including a sensor for measuring a supply current through the first conductor and a sensor for measuring a return current through the second conductor such that the supply current can be compared with the return current to find any imbalance between the supply current and the return current, wherein: (a) sensing of the supply current is done on the first conductor and sensing of the return current is done on the second conductor such that the comparison can use values obtained from each of the supply current sensor and the return current sensor, or (b) the first conductor and the second conductor pass through a ferromagnetic ring such that current passing through the first conductor generates current in the ferromagnetic ring in one direction and current passing through the second conductor generates a canceling current in the ferromagnetic ring in the opposite direction, imbalance being indicated by current in the ferromagnetic ring in the one direction.

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