WO2025230975A1

WO2025230975A1 - Systems, devices and methods for detection of ivl gas buildup

Info

Publication number: WO2025230975A1
Application number: PCT/US2025/026799
Authority: WO
Inventors: Austin PETRONACK
Original assignee: Cardiovascular Systems Inc
Current assignee: Cardiovascular Systems Inc
Priority date: 2024-05-03
Filing date: 2025-04-29
Publication date: 2025-11-06
Anticipated expiration: 2026-11-03

Abstract

A system, device and/or method to test an intravascular lithotripsy ("IVL") system for gas buildup resulting from electrical arc generation within an otherwise liquid fluid-filled enclosure. Generally, a voltage pulse of a magnitude that will not result in an electrical arc is issued from a voltage pulse generator to an electrode of at least one emitter located within the balloon. A voltage or current monitor is used to sense the voltage or current dissipation over time and compared with acceptable dissipation parameter(s). If the voltage or current dissipation over time fails to meet the acceptable dissipation parameter(s), then the IVL system may lock out further execution of voltage pulses designed to produce electrical arcs. Further, the IVL system may alert the operator to initiate a manual degassing procedure, or may automatically initiate a degassing procedure.

Description

SYSTEMS, DEVICES AND METHODS FOR DETECTION OF IVL GAS BUILDUP

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to United States Provisional Patent Application Serial No. 63/642,019 filed on May 3, 2024 and entitled "Systems, Devices and Methods for Detection of IVL Gas Buildup," and which application is expressly incorporated herein by reference in its entirety.

BACKGROUND

Background and Relevant Art

[0002] A variety of techniques and instruments have been developed for use in the removal or repair of tissue in arteries and similar body passageways, including removal and/or cracking of calcified lesions within the passageway and/or formed within the wall defining the passageway. A frequent objective of such techniques and instruments is the removal of atherosclerotic plaque in a patient's arteries. Atherosclerosis is characterized by the buildup of fatty deposits (atheromas) in the intimal layer (i.e., under the endothelium) of a patient's blood vessels. Very often over time what initially is deposited as relatively soft, cholesterol-rich atheromatous material hardens into a calcified atherosclerotic plaque, often within the vessel wall. Such atheromas restrict the flow of blood, cause the vessel to be less compliant than normal, and therefore often are referred to as stenotic lesions or stenoses, the blocking material being referred to as stenotic material. If left untreated, such stenoses can cause angina, hypertension, myocardial infarction, strokes and the like.

[0003] Angioplasty, or balloon angioplasty, is an endovascular procedure to treat by widening narrowed or obstructed arteries or veins, typically to treat arterial atherosclerosis. A collapsed balloon is typically passed through a pre-positioned catheter and over a guide wire into the narrowed occlusion and then inflated to a fixed pressure. [0004] The balloon forces expansion of the occlusion within the vessel and the surrounding muscular wall until the occlusion yields from the radial force applied by the expanding balloon, opening up the blood vessel with an inner diameter that is similar to the native vessel in the occlusion area and, thereby, improving blood flow. Generally, known IVL devices include a voltage pulse generator in operative communication with one or more pairs of electrodes mounted on a catheter and within an inflatable balloon. [0005] Intravascular lithotripsy systems, devices and methods have been described by Applicant. See PCT/2022/074607, filed August 5, 2022 and entitled "INTRAVASCULAR LITHOTRIPSY BALLOON SYSTEMS, DEVICES AND METHODS", and PCT/US2023/085868, filed December 23, 2023 and entitled "INTRAVASCULAR LITHOTRIPSY SYSTEM WITH IMPROVED DURABILITY, EFFICIENCY AND PRESSURE OUTPUT VARIABILITY", the entire contents of each of which are hereby incorporated by reference.

[0006] IVL systems and devices such as those illustrated above generate gas. Gas is generated as the fluid within the enclosure is vaporized during each electrical arc event and may accumulate over time as a series of consecutive electrical arc events are performed. The gas buildup within the enclosure is undesirable as it may, among other things, attenuate the pressure pulse or wave generated by the emitters as it travels to target treatment site, e.g., an occlusion and/or calcification within a blood vessel's wall, thus reducing an amount of energy delivered to the treatment site. Further, the gas buildup may degrade the efficiency of formation of the electrical arc or spark across the spark gap of the emitters. The net result of the gas buildup is reduction of therapeutic efficiency.

[0007] Currently known IVL systems have instructions for use (IFU) that direct a user to perform periodic deflation of the balloon between pulse delivery cycles, which serves to dissipate heat and remove residual gas bubbles through fluid evacuation from the balloon while allowing tissue reperfusion to mitigate ischemia. These periodic balloon deflations are suggested to be executed at predetermined intervals or times and, when performed, are executed manually without regard to the actual gas concentration or buildup within the balloon. Because the current process relies entirely on the operator to stop IVL treatment to degas the balloon at the suggested time intervals, error may be introduced which leads to reduction in therapeutic efficiencies. For example, the operator may choose to forgo balloon deflations in the interest of time or alternatively, the operator may perform more deflations than are prudent.

[0008] The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one exemplary technology area where some embodiments described herein may be practiced. BRIEF SUMMARY

[0009] A system, device and/or method to test an intravascular lithotripsy ("I VL") system for gas buildup resulting from electrical arc generation within an otherwise liquid fluid- filled enclosure are illustrated. Generally, a voltage pulse of a magnitude that will not result in an electrical arc is issued from a voltage pulse generator to an electrode of at least one emitter located within the balloon. A voltage or current monitor is used to sense the voltage or current dissipation over time and compared with acceptable dissipation parameter(s). If the voltage or current dissipation over time fails to meet the acceptable dissipation parameter(s), then the IVL system may lock out further execution of voltage pulses designed to produce electrical arcs. Further, the IVL system may alert the operator to initiate a manual degassing procedure, or may automatically initiate a degassing procedure.

[0010] This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. [0011] Additional features and advantages will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the teachings herein. Features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. Features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to describe the manner in which the above-recited and other advantages and features can be obtained, a more particular description of the subject matter briefly described above will be rendered by reference to specific embodiments which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments and are not therefore to be considered to be limiting in scope, embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

[0013] FIGURE 1 illustrates a schematic view of an IVL system. [0014] FIGURE 2 illustrates a schematic view of part of an IVL system.

[0015] FIGURE 3 illustrates a graphic illustration of a typical timing of applied voltage and current during application of voltage and generation of an electrical arc between emitter. [0016] FIGURE 4 illustrates a pressure vs number of voltage pulses graph comparing pressure output for an IVL system with no air in the enclosure with an IVL system with air in the enclosure.

[0017] FIGURE 5 is a side view of an IVL system enclosure or balloon during normal IVL therapy, illustrating gas bubbles located within the enclosure or balloon.

[0018] FIGURE 6A illustrates a pressure vs number of voltage pulses graph il lustrating the pressure magnitude with normal degassing procedures.

[0019] FIGURE 6B illustrates a pressure vs number of voltage pulses graph il lustrating the pressure magnitude without normal degassing procedures.

[0020] FIGURE 7A illustrates a graphic illustration of timing of applied voltage and current in an IVL system with an enclosure or balloon that is fully filled with a conductive liquid solution.

[0021] FIGURE 7B illustrates a graphic illustration of timing of current and voltage dissipation in an IVL system with an enclosure or balloon that is primarily filled with air.

[0022] FIGURE 8 illustrates a schematic image of one embodiment of the current disclosure.

[0023] FIGURE 9 illustrates a schematic image of one embodiment of the current disclosure.

[0024] FIGURE 10 illustrates a detecting a gas buildup condition of one embodiment of the current disclosure.

DETAILED DESCRIPTION

[0025] As illustrated in Fig. 1, a diagrammatic or schematic layout of portions of an IVL system 12 is provided. The illustrative IVL system 12 comprises a catheter assembly 14 including an elongate member, embodied as a catheter having guidewire 15, and a fluid- filled enclosure 16 configured to contain conductive fluid therein, exemplified by an inflatable balloon, disposed near one end of the body and arranged to receive fluid for inflation to facilitate IVL therapy. A set of dischargeable emitter(s) 18 are shown arranged within the exemplary fluid-filled enclosure 16, at least some of which are spaced apart by a gap 17 from each other to create a spark or electrical arc between the emitter(s) 18. [0026] The IVL system embodiments described herein may be used in connection with electrodes that are within a fluid-filled enclosure 16 configured to contain a fluid, e.g., a conductive fluid, therein. The fluid-filled enclosure 16 embodiments may include an inflatable balloon as shown in Fig. 1, which may be compliant or non-compliant and serves to contain the fluid such that the emitter(s) 18 are preferably fully submerged within the contained fluid. In addition, the fluid-filled enclosure 16 may comprise a fillable member that is at least partially rigid and/or not flexible. In other embodiments, the fluid- filled enclosure 16 may contain the fluid therein and wherein the emitter(s) 18 are most preferably fully submerged within the contained fluid.

[0027] Alternatively, the IVL system control embodiments of the present disclosure may be used in connection with electrodes that are not located or surrounded by a fluid-filled orfillable enclosure 16. In these embodiments, the IVL system may comprise one or more sets of spaced- apart electrodes or emitter(s) 18 that may be continuously or periodically exposed to saline or other fluid and, during the exposure, the IVL system may generate an electrical arc between the emitter(s) 18.

[0028] The emitter(s) 18 in Fig. 1 is arranged in communication (as suggested by dashed line conductors) with an electric pulse generation system, or voltage pulse generator, 20 to receive high voltage electrical energy for spark generation to create pressure waves for IVL therapy. In the illustrative embodiment, one electrode may be grounded and the other provided with high voltage from the electric pulse generation system 20, although in some embodiments, any voltage differential may be applied. The electric pulse generation system 20 includes an IVL control system 22 comprising a processor 24 configured for executing instructions stored on memory 26 and communications signals via circuitry 28 for IVL operations according to the processor governance. The processor 24, memory 26, and circuitry 28 are arranged in communication with each other (as suggested via dashed lines) to facilitate disclosed operations.

[0029] An IVL system is shown in Figure 2, illustrating one method for applying voltage pulses to the system, resulting in current flow through the exemplary system to each emitter(s) 18, wherein the emitter(s) 18 are connected in series. Fig. 2 illustrates two emitter(s) 18 defined within a support body 16. Application of a voltage pulse of sufficient magnitude and/or duration from the electric pulse generation system 20 to the sets of serially connected emitter(s) 18 will result in a successive production of electrical arcs as follows: a first arc across a first spark gap; a second arc across a second spark gap, a third arc across a third spark gap and a fourth arc across a fourth spark gap.

[0030] Sufficient energy is achieved at the discharge site to create an electrical arc across the one or more spark gaps of an IVL system. Embodiments of the IVL systems, devices and methods described within the present disclosure may include operation for adjusting the total electrical energy provided to the system at each emitter. Such control systems for intravascular lithotripsy systems, devices and methods have been described by Applicant. See PCT/2023/79209, filed November 9, 2023 and entitled "CONTROL OF IVL SYSTEMS, DEVICES AND METHODS THEREOF", the entire contents of which are hereby incorporated by reference.

[0031] Figure 3 graphically illustrates the drop in impedance of a current leader across a spark gap defined between two emitter in an IVL system such as shown in Figs. 1 and/or 2 following application of voltage to one of two emitter as the current leader develops into an electrical arc between the emitter. This, in turn, causes the power dissipated in the electrical arc to peak sharply while the voltage and current between the electrodes are both relatively high. The current reaches a peak and the voltage drops, both very rapidly, indicating that an electrical arc between the emitter is present, or has occurred. The peak of the power dissipated in the electrical arc indicates the relatively short time interval during which all the useful work of heating the growing leader into an arc is performed. The graphic illustration of Fig. 3 is exemplary of one aspect of an IVL procedure that produces pressure waves.

[0032] IVL systems and devices such as those illustrated above generate gas. Gas is generated as the fluid within the enclosure is vaporized during each electrical arc event and may accumulate over time as a series of consecutive electrical arc events are performed.

[0033] As shown in Figure 4, and with continued reference to Figs. 1-3, excess air in the enclosure or balloon decreases the efficiency of pressure generation. This may occur as a result of decreasing the efficiency of the spark formation such that not all of the energy in a system, e.g., that energy stored in capacitor banks or similar device, can be consumed by an electrical arc event as described above. Alternatively, this may be as a result of a dampening effect on generated waves caused by the air in the enclosure. The gas generated by the IVL process within the enclosure or balloon may be primarily oxygen and/or water vapor. This, in turn, leads to weaker therapeutic output and therapeutic output that is less predictable than optimal. As illustrated in Fig. 4, the dashed line graphs pressure magnitudes produced across a number of shocks generated by an IVL system comprising a fully fluid-filled balloon evidencing efficient electrical arcing and/or less dampening. In this case, the spaced apart electrode pairs or emitter(s) 18 are fully submerged in fluid. In contrast, the solid line graphs pressure magnitude across a number of shocks generated by an IVL system having a balloon that is filled with so much air buildup that the emitter(s) 18 may not be fully surrounded by a conductive liquid orfluid, and thus evidencing intermittent inefficient electrical arcing and/or dampening of any waves produced.

[0034] Initially, Figure 4 makes it clear that many of the pressure magnitudes produced by the inefficient electrical arcing IVL system or wave dampening with air in the balloon are generally drastically reduced as compared to the efficient electrical arcing pressure outputs generated by a fully fluid-filled balloon.

[0035] Comparison of the graphed pressure output lines of Fig. 4 reveals another problem with an IVL system that is not regularly degassed, i.e., wherein the emitter(s) 18 are not fully submerged in fluid. That is, the variability and the change magnitude from minimum to maximum, of the pressure output magnitudes produced by the IVL system with a balloon filled primarily with air are both very high compared with the IVL system with a balloon filled with liquid fluid. Thus, in inadequately degassed IVL systems, variability, and therefore, unpredictability, of the pressure output magnitudes results during otherwise normal operation. Further, in the primarily air-filled balloon IVL system of Fig. 4, many of the generated pressure magnitudes are much lower than the relatively stable pressure magnitudes of the adequately degassed system pressure magnitudes. Thus, not only is unpredictability of the pressure magnitude output introduced by inadequate degassing, the pressure magnitude output for many of the pressure pulses or pressure waves is much lower than expected, thereby transferring much less force to a lesion than expected, leading to inefficient therapeutic results and likely requiring additional treatment to achieve a desired result.

[0036] Figure 5 illustrates one example of gas buildup within an IVL enclosure 16 after normal use, wherein the fluid within the enclosure 16 still covers the emitters or emitter. Accordingly, Figure 5 illustrates a less extreme case of gas buildup than that of Fig. 4. In Fig. 5, gas bubbles are shown as the black, opaque regions in the fluid within the upper portion of the enclosure 16.

[0037] Thus, even in the normal use case, of FIG. 5, the pressure output from an electrical arc generated by the emitter(s) 18 will be reduced along the upper portion of the enclosure 16 resulting from the presence of the generated gas bubbles. This is a function of acoustic impedance; the skilled artisan recognizes that water-to-solid energy transfer is about 75-95% of energy, but water-to-gas energy transfer is less than 0.1%. Thus, in the exemplary case of Fig. 5, energy transfer through the enclosure 16 material adjacent to the gas bubbles illustrated at the portion of the enclosure 16 will be significantly less than energy transfer through the remaining portion of the enclosure 16 that remains in contact with the liquid fluid. In turn, the energy impacting a calcified lesion located adjacent or above the gas bubbles within the enclosure 16 will be less than expected and less than optimal.

[0038] Further, as discussed above, the pressure magnitude output for many of the pressure pulses or pressure waves in an IVL enclosure 16 with gas buildup is much lower than optimal, leading to inefficient therapeutic results and likely requiring additional treatment to achieve a desired result. This phenomenon effectively compounds the acoustic impedance problem resulting from the presence of gas bubbles at the upper portion of the enclosure 16, leading to lower than expected pressure / energy impacting a lesion.

[0039] With continued reference to Figs. 1 and 2, the importance of degassing within IVL enclosures or balloons 16 is further illustrated in Figures 6A and 6B, plotting pressure magnitude output over a series of executed electrical arcs across spark gap(s) 17 of one or more emitter(s) 18 within an IVL enclosure 16. In the illustrated example, the pressure magnitudes for each point on each pressure graph are measured just outside of the enclosure 16 with ONDA HNR-0500 model needle hydrophones without amplification. These hydrophones have an active diameter of 2.5mm. The hydrophones were calibrated and traceable to Onda Corporation. The frequency response of the hydrophones is flat from 0.5 MHz to 10 MHz within +/- 6 dB with measurement uncertainty of 1.5 dB for frequencies in the range of 0.5 - 1 MHz and 1 DB for frequencies in the range of 1 - 10 MHz. Each tested system comprised immersion of the enclosures or balloons in a water bath. Figure 6A illustrates the effects of regular, periodic degassing of fluid within an IVL enclosure 16. Figure 6B illustrates the impact of not regularly degassing the fluid within an IVL enclosure 16. Comparison of the data in Figs. 6A and 6B makes clear that, without regular degassing, as in Fig. 6B, pressure output decreases significantly compared with regular degassing (Fig. 6A), as air bubbles form in the balloon attenuating the pressure wave.

[0040] In addition to the pressure output magnitude decrease discussed above, inefficient electrical arcing may also result due to excess gas surrounding the spark gap(s)

17 between each electrode of a spaced-apart electrode pair 18. This condition may result in electrical arcs taking longer to form than a predetermined voltage application time and/or may require unnecessarily high voltage magnitudes to generate the desired electrical arc. In these occurrences, the spark or electrical arc event may only utilize a small fraction of the available energy stored on a capacitor bank(s) of a voltage pulse generator. Such occurrences are readily observable by measuring the residual voltage stored in the capacitor bank(s) after discharge and can be audibly distinguished as pulses having decreased volume.

[0041] Embodiments of the IVL system described herein may comprise the voltage pulse generator 20 including a high voltage board that monitors voltage and/or current during therapy delivery. Alternatively or additionally, a voltage monitor and/or current monitor may be operatively associated with the voltage pulse generator.

[0042] Turning to Figures 7A and 7B, a single diagnostic voltage pulse was applied to the IVL system such that a current flows to the spaced-apart set of electrode(s) or emitter(s)

18 as described above, but the voltage magnitude and/or duration is/are not sufficiently high to produce an electrical arc across the subject spark gap 17. The diagnostic voltage pulse is defined as a voltage pulse of magnitude and/or duration that is configured to not produce an electrical arc or spark event across a spark gap 17 separating the electrodes of emitter(s) 18. The magnitude of a diagnostic voltage pulse is system dependent, e.g., the distance of a spark gap 17, the configuration of emitter(s) 18, etc. For example, and without limitation, a diagnostic pulse magnitude may comprise 1200V or less, or 1000V or less, but these magnitudes are exemplary only. Alternatively, a shorter duration of voltage pulse generation may be employed, as compared with voltage pulses designed to generate electrical arcs. For example, the diagnostic voltage pulse may comprise a duration of tens to hundreds of microseconds. In these embodiments, the diagnostic voltage pulse is configured to not produce an electrical arc or spark event.

[0043] The IVL system used to generate the plot of Fig. 7A comprised an enclosure 16 such as described above in connection with Figures 1 and 2, that was filled with saline, a conductive fluid, without gas or air buildup such that the spaced-apart electrode sets of the emitter(s) 18 were fully submerged. The IVL system used to generate the plot of Fig. 7B comprised an enclosure 16 that was filled primarily with air, wherein the spaced-apart electrode sets of the emitter(s) 18 were not fully submerged.

[0044] As can be seen by comparing the voltage dissipation following initial voltage drop in Figs. 7A and 7B, when the emitters of the IVL system are exposed to mostly air, the voltage dissipation takes much longer than when the spaced-apart electrode sets of emitter(s) 18 are submerged in fluid. The spaced-apart electrode sets of emitter(s) 18 that were exposed to mostly air (or gas) produced a voltage magnitude degradation of approximately 50% in magnitude over a time of hundreds of microseconds. The spaced- apart electrode sets of emitter(s) 18 that were submersed in saline produced a voltage magnitude degradation of approximately 50% in magnitude over a time of tens of microseconds.

[0045] It is this differential in voltage magnitude, or rate of, dissipation over time, and the monitoring of same on the voltage pulse generator side of the IVL system, that allows detection and/or diagnosis of the buildup of gas within the IVL enclosure or balloon and provides an alert point triggering in some embodiments a degassing procedure.

[0046] With reference to Figures 8 and 9, some embodiments may comprise a predetermined minimum time parameter and a minimum voltage or current parameter, that when applied result in a threshold parameter minimum voltage or current dissipation threshold which may comprise a voltage or current magnitude or a voltage or current dissipation rate. These predetermined parameters and threshold may be programmed into a storage device 202, such an EPROM (erasable programmable readonly memory). In some embodiments, the storage device may be disposed within a handle H of the catheter C. This arrangement in some embodiments allows the predetermined minimum time and voltage or current parameters, and the resultant minimum voltage or current dissipation threshold to be programmed specifically to a certain model and/or device and/or system. [0047] As shown in, e.g., Fig. 8 and with continued reference to Fig. 1, an IVL system 200 is provided comprising a storage device 202. The storage device 202 is in operative communication and association with the processor 24, which is, in the illustrated embodiment part of the voltage pulse generator 20. In other embodiments, the controller 22, and associated processor 24, memory 26 and related circuitry 28 may be in operative and electrical communication with the voltage pulse generator 20, but located in a different physical location than the voltage pulse generator 20. The storage device 202 is illustrated as located within or in operative association with the handle H of a catheter C, which is in operative association with the enclosure 16.

[0048] The processor 24 is in operative and/or electrical association with a voltage or current monitor 204 that is illustrated as located within the voltage pulse generator 20. In some embodiments, the voltage or current monitor 204 may be located in a separate location apart from the voltage pulse generator 20. The voltage or current monitor 204 may be implemented using various circuits such as solid state electronic circuits, amplifiers, resistive components, capacitive components, and/or other components. The voltage pulse generator 20 may be in operative and electrical association with one or more emitter(s) 18. As illustrated, the two emitters 18, each comprising at least one pair of spaced apart electrodes as discussed above in relation to Figure 1, are connected in a serial connection, with the voltage pulse generator 20 operatively and/or electrically connected with a more proximally located emitter(s) 18. Alternative connection associations between the emitters 18 and the voltage pulse generator 20 may be provided in alternative embodiments. For example, the two emitters 18 may be connected in a parallel arrangement. Further, the voltage pulse generator 20 may be operatively and/or electrically associated with a more distal emitter(s) 18. Finally, a display may be operatively and/or electrically associated with the controller 22.

[0049] In practice, the following procedure may be executed to test an IVL system for excess gas buildup in an IVL enclosure 16 using the configuration of Fig. 8:

[0050] 1. Store minimum time parameter, minimum voltage parameter, and the resultant minimum voltage or current dissipation threshold on the storage device 202. In some embodiments, these data are all predetermined and pre-programmed during manufacturing. [0051] 2. The storage device 202 communicates with the processor 24. The processor is configured to extract from the storage device 202 the stored minimum time parameter, minimum voltage or current parameter, and the resultant minimum voltage or current dissipation threshold. In the embodiment wherein the storage device 202 is located within the handle H, the extraction of stored data by the processor 24 from the storage device 202 may be initiated by connection of the handle H with the voltage pulse generator 20.

[0052] 3. When the voltage pulse generator 20 is activated (after power on, before delivering therapy), the voltage pulse generator 20 is instructed by the processor 24 to apply a low voltage pulse to one or more emitter(s) 18, wherein the applied low voltage pulse comprises a magnitude that approximately matches the voltage or current parameter extracted from the storage device 202. As noted above, the low voltage pulse is defined as comprising a magnitude and/or duration that does not generate an electrical arc between the emitter(s) 18. The voltage or current monitor 204 senses and/or tracks the voltage or current decay of the applied low voltage pulse across a capacitor bank. The processor 24 receives the sensed and/or tracked voltage or current decay from the voltage or current monitor 204 for the time duration specified by the time parameter extracted from the storage device 202. The processor 24 is configured to monitor and determine whether the voltage or current dissipation drops below the minimum voltage or current dissipation threshold parameter within the specified time duration parameter.

[0053] 4. If the voltage or current dissipation drops below the minimum voltage or current dissipation threshold parameter within the specified time duration parameter, then the processor 24 determines the catheter is sufficiently degassed and configures the voltage pulse generator 20 such that an operator user can apply voltage pulses of sufficient magnitude and/or duration to produce electrical arcs between one or more emitter(s) 18.

[0054] If the voltage or current dissipation does not drop below the minimum voltage or current dissipation threshold parameter within the specified time duration parameter, then the processor 24 may alert an operator that more catheter degassing procedures are recommended and/or required. [0055] In some embodiments a detection notice or alert may be issued by the processor 24 and provided to the operator and may comprise an auditory or vibratory notification to degas the system. In other embodiments, a detection notice or alert may be issued by the processor 24 and displayed on the IVL system's display alerting the operator to degas the system.

[0056] In some embodiments, the processor and/or storage device 202 may further comprise a predetermined maximum number of voltage pulses that are configured to generate electrical arcs before requiring a degassing procedure as outlined above.

[0057] In other embodiments, upon receipt of a predetermined minimum voltage or current dissipation over time condition sensed and communicated by the voltage or current sensor, the processor 24 may be configured to automatically instruct deflation (degassing) of the enclosure 16, then reinflate the enclosure 16.

[0058] In other embodiments, upon receipt of a predetermined minimum voltage or current dissipation over time condition sensed and communicated by the voltage or current sensor, the processor 24 may be configured to alert the operator to manually deflate (degas) the enclosure or balloon, then manually reinflate the enclosure or balloon.

[0059] In certain embodiments, upon receipt of a predetermined minimum voltage or current dissipation over time condition, the processor 24 may be configured to lock out, or prevent, any further generation of voltage pulses of sufficient magnitude to generate electrical arcs until the degassing process is completed - whether the degassing is executed manually or automatically.

[0060] Turning to Figure 9, an IVL system 300 comprising the system configuration of Fig.

8 is illustrated, with the addition of a fluid reservoir R in operative and fluid association with a pump P that is in fluid association with the balloon and, in the illustrated embodiment, is in electrical and/or operative association with the controller 22. In this embodiment, the processor 24 ofthe controller 22 may, upon receipt of a predetermined minimum voltage or current dissipation over time condition, be configured to automatically execute a degassing procedure to bring the voltage or current dissipation over time into an acceptable range. In this embodiment, the processor 24 may lock out any further execution of voltage pulses designed to generate electrical arcs until a degassing procedure is executed and/or a test for degassing yields acceptable results. The processor 24 may, in this embodiment, instruct the pump P to automatically begin deflating the enclosure 16 and, when completed, instruct the pump P to automatically reinflate the enclosure 16 to a predetermined volume. At this stage, the processor 24 may allow additional electrical arc -generating voltage pulses to commence, or may require another degassing test as described above with allowance of additional electrical arc-generating voltage pulses only if the degassing test passes the predetermined criterion.

[0061] Generally, during normal operation, a test forgas buildup as described above may be completed after a predetermined number of voltage pulses that are designed to produce electrical arcs within an IVL enclosure 16.

[0062] Accordingly, and generally, a diagnostic low voltage pulse as described and defined above that will not generate an electrical arc may be executed. A voltage or current monitor 204 may sense the voltage or current magnitude during the voltage pulse discharge. The energy available to sustain the voltage pulse is limited by the capacity of a bank of capacitors in the voltage pulse generator. When the emitter or emitters 18 in the IVL enclosure 16 are surrounded by conductive fluid, the voltage pulse decays more rapidly as a conduction path is formed between the conductive fluid and the two emitters forming an anode and a cathode. If, on the other hand, the emitters or emitter(s) 18 within the IVL enclosure or balloon are not surrounded by the conductive fluid, and may be at least partially surrounded by air buildup, the voltage pulse decays much more slowly. Thus, by monitoring the rate of voltage or current pulse decay over time, the surrounding conditions of the emitters or emitter may be sensed and a gas buildup condition may be diagnosed and corrected.

[0063] The following discussion now refers to a number of methods and method acts that may be performed. Although the method acts may be discussed in a certain order or illustrated in a flow chart as occurring in a particular order, no particular ordering is required unless specifically stated, or required because an act is dependent on another act being completed prior to the act being performed.

[0064] Fig. 10 is a flowchart of an example method for detecting a gas buildup condition. At act 1010, the method includes generating a voltage pulse to one or more spaced-apart pairs of electrodes located within a fluid-fillable enclosure or balloon of an intravascular lithotripsy ("IVL") system, wherein the voltage pulse is configured to not generate an electrical arc. At act 1020, the method includes monitoring voltage or current at the one or more spaced-apart electrodes.

[0065] At act 1030, the method includes determining if the received voltage or current dissipation input is at or above a predetermined voltage or current dissipation threshold. [0066] Further, the methods may be practiced by a computer system including one or more processors and computer-readable media such as computer memory. In particular, the computer memory may store computer-executable instructions that when executed by one or more processors cause various functions to be performed, such as the acts recited in the embodiments.

[0067] Embodiments of the present invention may comprise or utilize a special purpose or general-purpose computer including computer hardware, as discussed in greater detail below. Embodiments within the scope of the present invention also include physical and other computer-readable media for carrying or storing computerexecutable instructions and/or data structures. Such computer-readable media can be any available media that can be accessed by a general purpose or special purpose computer system. Computer-readable media that store computer-executable instructions are physical storage media. Computer-readable media that carry computerexecutable instructions are transmission media. Thus, by way of example, and not limitation, embodiments of the invention can comprise at least two distinctly different kinds of computer-readable media: physical computer-readable storage media and transmission computer-readable media.

[0068] Physical computer-readable storage media includes RAM, ROM, EEPROM, CD- ROM or other optical disk storage (such as CDs, DVDs, etc.), magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer.

[0069] A "network" is defined as one or more data links that enable the transport of electronic data between computer systems and/or modules and/or other electronic devices. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a computer, the computer properly views the connection as a transmission medium. Transmissions media can include a network and/or data links which can be used to carry desired program code means in the form of computer-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer. Combinations of the above are also included within the scope of computer- readable media.

[0070] Further, upon reaching various computer system components, program code means in the form of computer-executable instructions or data structures can be transferred automatically from transmission computer-readable media to physical computer-readable storage media (or vice versa). For example, computer-executable instructions or data structures received over a network or data link can be buffered in RAM within a network interface module (e.g., a "NIC"), and then eventually transferred to computer system RAM and/or to less volatile computer-readable physical storage media at a computer system. Thus, computer-readable physical storage media can be included in computer system components that also (or even primarily) utilize transmission media.

[0071] Computer-executable instructions comprise, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. The computerexecutable instructions may be, for example, binaries, intermediate format instructions such as assembly language, or even source code. Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the described features or acts described above. Rather, the described features and acts are disclosed as example forms of implementing the claims.

[0072] Those skilled in the art will appreciate that the invention may be practiced in network computing environments with many types of computer system configurations, including, personal computers, desktop computers, laptop computers, message processors, hand-held devices, multi-processor systems, microprocessor-based or programmable consumer electronics, network PCs, minicomputers, mainframe computers, mobile telephones, PDAs, pagers, routers, switches, and the like. The invention may also be practiced in distributed system environments where local and remote computer systems, which are linked (either by hardwired data links, wireless data links, or by a combination of hardwired and wireless data links) through a network, both perform tasks. In a distributed system environment, program modules may be located in both local and remote memory storage devices.

[0073] Alternatively, or in addition, the functionality described herein can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field- programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0074] The present invention may be embodied in other specific forms without departing from its characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims

CLAIMS What is claimed is:

1. An intravascular lithotripsy ("IVL") catheter with improved pressure output variability comprising: an elongate member; a fluid-fillable enclosure formed of a material having an outer surface and surrounding a distal region of the elongate member; at least one emitter operatively associated with the elongate member and within the fluid-fillable enclosure, wherein each emitter forms a spark gap; a fluid reservoir configured to hold a fluid in operative fluid communication and association with an interior of the fluid-fillable enclosure, a voltage pulse generator configured to be coupled to and in operative electrical communication and association with the at least one emitter; and a controller in operative association with the voltage pulse generator and configured to control the voltage pulse generator, wherein the IVL catheter is configured to produce a plurality of electrical arcs at the emitter, each of the arcs in the plurality of electrical arcs being produced in response to a voltage pulse provided by the voltage pulse generator, and wherein the controller is configured to detect a gas buildup condition within the fluid-fillable enclosure.

2. The IVL catheter of claim 1, wherein the controller is configured to issue an alert of the detected gas buildup condition.

3. The IVL catheter of claim 2, wherein the alert comprises a visual, auditory or haptic alert.

4. The IVL catheter of claim 1, wherein the controller is further configured to initiate an automated degassing of the fluid-fillable enclosure after a gas buildup condition is detected.

5. The IVL catheter of claim 4, wherein the automated degassing comprises deflation of fluid from the fluid-fillable enclosure and reinflation of the enclosure with fluid from the fluid reservoir.

6. The IVL catheter of claim 1, wherein the controller is configured to instruct the voltage pulse generator to generate a diagnostic voltage pulse at a predetermined magnitude and/or duration that is configured to not generate an electrical arc across the spark gap.

7. The IVL catheter of claim 6, further comprising a voltage or current monitor in operative association with the controller and configured to monitor a resulting voltage or current magnitude and/or voltage or current dissipation rate following the generation of the diagnostic voltage pulse.

8. The IVL catheter of claim 6, wherein the controller identifies a minimum voltage or current magnitude and/or minimum voltage or current dissipation rate and wherein when a monitored voltage or current magnitude and/or voltage or current dissipation rate is at or above the minimum voltage or current dissipation rate, the controller indicates a gas buildup condition.

9. The IVL catheter of claim 6, wherein the controller is configured to generate the diagnostic voltage pulse after a predetermined number of voltage pulses have been generated.

10. The IVL catheter of claim 9, wherein the controller is configured to prevent generation of any further voltage pulses configured to generate electrical arcs until degassing is completed.

11. The IVL catheter of claim 1, further comprising a storage device in operative association and communication with the controller, wherein the storage device comprises one or more of the following: a minimum diagnostic time parameter, a minimum diagnostic voltage or current parameter, or a minimum voltage or current dissipation rate or threshold magnitude.

12. The IVL catheter of claim 11, further comprising a handle that is in operative association with the voltage pulse generator and the controller, and wherein the storage device is located on or within the handle.

13. A method for detecting gas buildup in an intravascular lithotripsy ("IVL") catheter, comprising: providing the IVL catheter of claim 1; instructing by the controller a generation of a diagnostic voltage pulse configured to not generate an electrical arc; monitoring a resulting voltage magnitude and/or voltage or current dissipation rate; comparing the monitored voltage or current magnitude and/or voltage or current dissipation rate against a minimum voltage or current magnitude and/or voltage or current dissipation rate; and detecting a gas buildup condition if the monitored voltage or current magnitude and/or voltage or current dissipation rate is/are above the minimum voltage or current magnitude and/or minimum voltage or current dissipation rate.

14. A method for preventing a decrease in pressure output magnitude over a series of electrical arcs generated in an intravascular lithotripsy ("IVL") catheter, comprising: providing the IVL catheter of claim 1; instructing by the controller a generation of a diagnostic voltage pulse configured to not generate an electrical arc; monitoring a resulting voltage or current magnitude and/or voltage or current dissipation rate; comparing the monitored voltage or current magnitude and/or voltage or current dissipation rate against a minimum voltage or current magnitude and/or voltage or current dissipation rate; after generating a predetermined number of electrical arcs, detecting a gas buildup condition if the monitored voltage or current magnitude and/or voltage or current dissipation rate is/are above the minimum voltage or current magnitude and/or minimum voltage or current dissipation rate; and executing a degassing procedure.

15. A system for detecting a gas buildup condition the system comprising: a controller configured to receive voltage or current dissipation input; a voltage pulse generator configured to generate a voltage pulse to one or more spaced-apart pairs of electrodes located within a fluid-fillable enclosure or balloon of an intravascular lithotripsy ("IVL") system, wherein the voltage pulse is configured to not generate an electrical arc; a voltage or current monitor in operative association with a controller, the voltage or current monitor configured to monitor voltage or current at the one or more spaced- apart electrodes; wherein the controller is further configured to determine if the received voltage or current dissipation input is at or above a predetermined voltage or current dissipation threshold.

16. The system of claim 15, wherein the predetermined voltage or current dissipation threshold comprises one or more of a voltage or current magnitude or a voltage or current dissipation rate.

17. The system of claim 16, wherein if the received voltage or current dissipation input is at the predetermined voltage or current dissipation threshold, the controller is further configured to detect the gas buildup condition.

18. The system of claim 16, wherein if the received voltage or current dissipation input is above the predetermined voltage or current dissipation threshold, the controller is further configured to detect the gas buildup condition.

19. A method of detecting a gas buildup condition the method comprising: generating a voltage pulse to one or more spaced-apart pairs of electrodes located within a fluid-fillable enclosure or balloon of an intravascular lithotripsy ("IVL") system, wherein the voltage pulse is configured to not generate an electrical arc; monitoring voltage or current at the one or more spaced-apart electrodes; and determining if the monitored voltage or current is at or above a predetermined voltage or current dissipation threshold.

20. The method of claim 19, wherein the predetermined voltage or current dissipation threshold comprises one or more of a voltage or current magnitude or a voltage or current dissipation rate.