Intravascular lithotripsy devices and systems including forward-facing electrode and flex circuit placement

Abstract

The catheter system generates a primarily forward force from forward-facing electrodes within the balloon catheter. The system includes a high-voltage pulse generator that provides positive and negative voltage connections to electrode wires. The electrode wires can further pass through the catheter lumen toward the distal end of the catheter, where they are connected to electrodes preferably arranged in series to trigger one of more energy waves to propagate toward the thrombus or calcified lesion. An inflation fluid can be easily injected into the balloon. The inflation fluid is preferably saline, which has some electrical conductivity.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 416,231, filed October 14, 2022, entitled CATHETER SYSTEM WITH FORWARD FACING ELECTRODES FOR CREATING ENERGY WAVES, and U.S. Provisional Patent Application No. 63 / 462,208, filed April 26, 2023, entitled INTRAVASCULAR LITHOTRIPSY DEVICES AND SYSTEMS WITH FORWARD FACING ELECTRODES AND Flex Circuit Arrangements, the entire contents of which are incorporated herein by reference in their entireties.

[0002] The present invention is directed to a catheter system for treating vascular thrombi or calcified lesions, etc., using energy waves generated by electrodes in a conductive flowing medium. [Background technology]

[0003] Catheter systems with angioplasty balloons are commonly used to apply physical force to calcified lesions within the vasculature by expanding the balloon to push the calcifications back and into the vessel wall. However, certain calcified lesions and thrombi are not effectively disrupted by the use of angioplasty balloons. For example, thrombi may exist within the vasculature in front of the inserted angioplasty balloon. The angioplasty balloon is ineffective against the obstacle ahead.

[0004] More recently, intravascular lithotripsy (IVL) catheter systems have been developed. These systems include a balloon, similar to an angioplasty balloon, filled with a conductive fluid medium, such as saline, to expand the balloon in place at the lesion or thrombus. The catheter system also includes a pair of electrodes operably positioned in the conductive fluid medium. The electrodes are pulsed with high voltage to generate a spark that travels across the gap between the two electrodes with each pulse. The spark in the conductive medium creates an energy wave that propagates through the fluid medium, causing the balloon to exert a physical force against the lesion or thrombus. The energy propagation also involves the generation of microbubbles, which facilitate the physical force. Such devices are known to deliver a primarily radial energy wave that acts radially against the lesion or thrombus, with the goal of breaking up calcifications or clots.

[0005] Current catheter systems include treatment sequences that include a maximum number of consecutive pulses, a minimum delay thereafter, and a hard maximum total pulses associated with a particular catheter. One such product is specified in the table below.

[0006] [Table 1]

[0007] If treatment is still not complete after counting the maximum total pulses per catheter, the physician must replace the catheter, with the attendant undesirable cost, delay, and confusion. Intravascular lithotripsy (IVL) devices are available for several calcification patterns. Disposable IVL balloon devices come in a variety of designs and sizes for peripheral or coronary indications. All designs utilize a reusable power source, such as an IVL generator. One reusable DC generator includes the specifications in the table below.

[0008] [Table 2]

[0009] One such disposable device consists of a fluid-filled balloon angioplasty catheter fitted with a 0.014 inch guidewire that contains two lithotripsy emitters integrated into the shaft of a 12 mm long balloon segment. To deliver treatment, the fluid-filled balloon (e.g., 50 / 50 saline contrast medium) is inflated to approximately 4 atm, and then an electrical pulse is delivered to the emitters, which cause a high-voltage spark. Acoustic waves are generated, shattering the calcium. Summary of the Invention

[0010] The present invention is directed to a catheter system that generates a primarily forward force from forward-facing electrodes disposed within a balloon catheter. The system includes a high-voltage pulse generator that provides positive and negative voltage connections to electrode wires. The electrode wires can further pass through the catheter lumen toward the distal end of the catheter, where they are connected to electrodes preferably arranged in series to induce one of more energy waves to propagate toward the thrombus or calcified lesion. An inflation fluid can be injected into the balloon to facilitate inflation. The inflation fluid is preferably saline, so as to have some electrical conductivity.

[0011] In one aspect of the present invention, an intravascular lithotripsy (IVL) system is provided for use in inducing an energy wave as a force against a lesion in the vasculature. The IVL system includes a catheter extending from a proximal end to a distal end, the catheter including an electrode and conductive tube arrangement at the distal end, the electrode disposed within the conductive tube and spaced from the conductive tube by an insulating layer, the electrode having a forward-facing electrode distal end, the conductive tube further including a forward-facing conductive tube distal end, the forward-facing conductive tube distal end radially spaced from the electrode distal end to form at least one spark gap with the forward-facing electrode distal end.

[0012] The IVL system can include multiple electrodes within the conductive tube, each spaced from the conductive tube by an insulating layer, the electrodes electrically isolated from one another to form multiple gaps with the conductive tube, and energized in series to produce multiple sparks. Additionally, the electrodes can be arc segments of conductive material coaxial with the conductive tube so as to be similarly spaced from the tube, with the distal ends of the electrodes and the distal ends of the conductive tube extending to similar axial lengths so as to terminate adjacent to one another.

[0013] In other embodiments, the IVL system can have a distal end of the conductive tube that extends axially further distally than the distal end of the electrode such that the entire distal end of the electrode is proximally disposed within and spaced from the distal end of the conductive tube. The insulating layer can preferably extend to terminate adjacent the distal end of the electrode such that a spark can be generated between the distal end of the electrode and the inner sidewall of the conductive tube.

[0014] In another aspect of the invention, a method of using an intravascular lithotripsy (IVL) system for a lesion in the vasculature includes inserting an IVL catheter having a balloon, a conductive tube, and at least one electrode into a patient's vasculature to a location of a lesion in the vasculature beyond a distal end of the balloon, the electrode having a distal end and the conductive tube also having a distal end, wherein a spark gap is formed between the distal end of the electrode and the distal end of the conductive tube; electrically connecting the conductive tube and the electrode to a high-voltage pulse generator; delivering an at least partially conductive fluid to the balloon; and generating a high-voltage pulse in the high-voltage pulse generator, thereby causing a spark in the spark gap along with cavitation bubbles such that a forward-directed energy wave propagates through the fluid in the balloon and from the balloon to the lesion.

[0015] Such an IVL system may have a plurality of electrodes disposed within the conductive tube and spaced from the conductive tube by an insulating layer, the electrodes being electrically insulated from one another to form a plurality of spark gaps with the conductive tube, and the method further includes energizing the electrodes in series to create a plurality of sparks in the plurality of spark gaps. The distal ends of the electrodes and the distal end of the conductive tube may extend similar axial distances and may terminate adjacent to one another with the insulating layer therebetween so that sparks can be generated from the distal ends of the electrodes and the distal end of the conductive tube. In other methods, the distal end of the conducting tube may extend axially further distally than the distal end of the electrode such that the distal end of the electrode is disposed entirely proximally within and spaced apart from the distal end of the conducting tube, the method further including generating a spark between the distal end of the electrode and an inner sidewall of the conducting tube, and thus generating a cavitation bubble at least partially within the distal end of the conducting tube such that an energy wave may be directed from the open distal end of the conducting tube in a desired forward direction. More preferably, the distal end of the conducting tube may extend axially sufficiently beyond the distal end of the electrode such that the cavitation bubble is formed entirely within the distal end of the conducting tube.

[0016] In another aspect, an intravascular lithotripsy (IVL) system used to deliver an energy wave as a force to a lesion in the vasculature includes a catheter extending from a proximal end to a distal end, the catheter including an arrangement of electrodes and conductive tubing at the distal end of the catheter such that a plurality of electrodes are disposed adjacent the distal end of the catheter, and further including a flex circuit extending from the proximal end of the catheter to the electrodes for electrically connecting the electrodes to a high voltage pulse generator at the proximal end of the flex circuit, the flex circuit being helically wound within the catheter along at least a portion of the catheter. [Brief explanation of the drawings]

[0017] [Figure 1]FIG. 1 is a schematic diagram of a high-voltage pulse generator including an arrangement of electrodes and conductive tubes to create a forward (axially) facing spark, such as in an intravascular lithotripsy (IVL) device, along with a balloon catheter. [Figure 2] FIG. 2 is a schematic view similar to FIG. 1, but with the ends of the balloon open to allow for the flow of conductive fluid from the balloon during an IVL procedure. [Figure 3] FIG. 1 is a perspective view of a distal portion of a conductive tube having a pair of arcuate electrodes disposed therein to form an IVL device, with the insulating layer not shown. [Figure 4] A cross-sectional view of the distal portion of an IVL device showing the two electrodes and the end of the conductive tube, generating a spark and causing energy propagation in the forward axial direction. [Figure 5] FIG. 5 is a cross-sectional view similar to FIG. 4, but with the conductive tube extending axially forward further than the end of the electrode to cause propagation of energy slightly radially inward from the generated spark. [Figure 6] FIG. 6 is a cross-sectional view of the distal portion of the IVL device of FIGS. 1-5, showing the conductive electrodes and conductive tubes insulated from one another. [Figure 7] 1 is a cross-sectional view of a flex circuit section including an insulating layer with multiple electrodes rolled and inserted into a conductive tube to provide an electrode structure according to the present invention. [Figure 8] FIG. 8 is a cross-sectional view of the resulting electrode arrangement comprising the flex circuit of FIG. 7. [Figure 9] 10A-10C are diagrams of other flex circuit configurations including conductive layers, insulating layers, and multiple electrodes suitable for forming the electrode structures of the present invention. [Figure 10] 10 is a cross-sectional view of the resulting electrode arrangement with the flex circuit of FIG. 9 wrapped around a tube defining a lumen. [Figure 11] FIG. 10 is a diagram of a flex circuit similar to that shown in FIG. 9 shortened so that it is not coextensive with the circumference of the tube that defines the lumen. [Figure 12]FIG. 1 is a cross-sectional view of a flex circuit partially wrapped around a tube defining a lumen. [Figure 13] FIG. 10 is a diagram of a flex circuit section having multiple electrode pads connected to traces for electrical connection and conduction. [Figure 14] FIG. 14 is a view similar to FIG. 13 showing a spark emanating from the electrode pad to the outer conductive layer. [Figure 15] FIG. 12 is a view of the distal portion of the electrode pad connected to a trace that is angled to form a spiral winding of the trace as it extends from the electrode pad down the length of the catheter. [Figure 16] FIG. 16 is a diagram of such an electrode pad and the length of such angled trace suitable for wrapping as shown in FIG. 15. [Figure 17] FIG. 10 is a diagram of the distal portion of an electrode including multiple traces that extend from the electrode pad and may be wrapped as they extend. [Figure 18] FIG. 17 is a view similar to FIG. 16 showing pairs of conductors along one side of a single trace for connecting to pairs of electrode pads. [Figure 19] FIG. 19 is an enlarged view of the distal ends of the traces, conductors, and electrode pads of FIG. 18. [Figure 20] FIG. 19 is a view similar to FIG. 18 showing pairs of conductors along either side of a single trace for connecting to pairs of electrode pads. [Figure 21] FIG. 21 is an enlarged view of the distal ends of the traces, conductors, and electrode pads of FIG. 20. [Figure 22] FIG. 10 is a diagram of the length of a pair of electrodes including traces having linearly extending pairs of conductors for connection to a high voltage pulse generator. [Figure 23] FIG. 23 is an enlarged view of a distal portion of the electrodes, conductors, and traces of the flex circuit of FIG. 22. [Figure 24]FIG. 6 is an axial cross-sectional view similar to FIG. 5, but with the conducting tube extending further axially forward than the end of the electrode to cause a spark between the end of the electrode and the inner wall of the conducting tube due to energy wave propagation from the end of the conducting tube. [Figure 25] FIG. 25 is a cross-sectional view of the conducting tube and electrode arrangement of FIG. 24 showing a single electrode as a coaxial conducting tube inside an outer conducting tube. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention is directed to a catheter system 10, as shown generally in FIG. 1, which generates a primarily forward force from forward-facing electrodes 12 and 14, as described below. The system 10 includes a high-voltage pulse generator 16 that provides positive and negative voltage connections to electrode wires 18 and 20. The catheter 22 includes a hub 24 at its proximal end and a balloon 26 at its distal working end. A guidewire 28 slides within a lumen 30 that extends from an access inlet 32 ​​in the hub 24 to the distal end of the balloon 26. Additionally, the electrode wires 18 and 20 may pass through the lumen 30 through an electrical inlet 34 in the hub 24 toward the distal end of the catheter 22. Inflation fluid may be easily injected into the balloon through an auxiliary inflation inlet 36, and fluid flow through the catheter 22 is provided by an optional inflation lumen, as may be provided to the balloon 26, as is well known. The inflation fluid is preferably saline, so as to provide some electrical conductivity for purposes described below.

[0019] Electrode wires 18 and 20, as shown within balloon 26, are electrically connected to electrodes 12 and 14, respectively. Electrode 12 is preferably spaced from wire lumen 30 by a first insulating layer 38, which may surround and define lumen 30. A second insulating layer 40 preferably surrounds electrodes 12 and 14 to electrically insulate electrodes 12 and 14 from conductive tube 42. As best shown schematically in FIG. 3 , each electrode 12 and 14 may preferably be disposed within the same radial space from lumen 30. As shown, electrode 12 is arcuate whether viewed from its distal or proximal end, includes an arc segment that is preferably less than 180 degrees, extends axially for a predetermined length, and is connected to electrode wire 20. Similarly, electrode 14 is arcuate whether viewed from its distal or proximal end, and includes another arc segment, preferably also less than 180 degrees, that extends axially for a predetermined length and is connected to electrode wire 18. Electrodes 12 and 14 may be of similar or different lengths. The length of electrodes 12 and 14 may be related to their useful life as they wear over time, as described in more detail below. Conductive tube 42 is positioned to generally, preferably concentrically, surround both electrodes 12 and 14.

[0020] Insulating layers 38 and 40 are not shown in FIG. 3 . Layer 38 is preferably a concentric layer between lumen 30 and electrodes 12 and 14. Layer 40 is preferably a concentric layer between electrodes 12 and 14 and conductive tube 42. Because electrodes 12 and 14 are each arc segments of less than 180 degrees, gaps 44 and 46 are formed between the opposing axial edges of electrodes 12 and 14. The gaps are preferably, but not necessarily, of similar length to the arc segments. Furthermore, to prevent any arcing between electrodes 12 and 14 at gaps 44 and 46, insulating material from either or both insulating layers 38 and 40 is preferably provided to fill gaps 44 and 46.

[0021] 1, the distal ends of electrodes 12 and 14 are where the electrodes are controllably sparked by high voltage pulses generated by generator 16. Controller 48 is shown schematically operatively connected to high voltage pulse generator 16 and may include an operator input module to allow an operator to control the pulses and therefore the sparking between electrodes 12 and 14 and conductive tubing 42. Controller 48 may further include a program to control the high voltage pulses according to a predetermined sequence that may be tailored to particular vasculature conditions or other circumstances.

[0022] Preferably, multiple sparks are generated per high-voltage pulse. In the example of Figures 1-5, a positive charge can be delivered to electrode 14 by electrode wire 20 from high-voltage pulse generator 16 as a single pulse or as a series of controlled pulses. A neutral or ground can be applied from generator 16 to electrode 12 by electrode wire 18. As a result, with each pulse, a spark arcs from the distal end face of electrode 14 to the distal end face of conductive tube 42. The charge delivered to conductive tube 42 generates a second spark as it arcs from conductive tube 42 to neutral electrode 12. In this manner, the spark gaps are electrically connected in series. As described above, balloon 26 is filled with a flowable medium during this process. The flowable medium is at least partially conductive, such as saline. Other known or developed flowable media may also be used. The dashed arrows at electrodes 12 and 14 and the distal end of conductive tube 42 in Figure 1 indicate this arcing. In Figures 3 and 4, the energy propagation is shown by dashed lines.

[0023] According to a preferred embodiment of the present invention, the spark or arc discharge in each case is from the forward-facing surfaces of electrodes 12 and 14 and conductive tube 42, respectively. More preferably, the forward-facing surfaces are at the distal ends of electrodes 12 and 14 and conductive tube 42. To prevent sparking on the proximal side of the electrodes, an insulating material may be applied to cover the proximal or rearward-facing surfaces of both electrodes 12 and 14. As a result of such orientation, each spark generates an energy wave that propagates in a forward direction, defined primarily as the axial direction, from the distal ends of electrodes 12 and 14 and conductive tube 42. In operation, catheter 22 is inserted into the vasculature so that balloon 26 abuts a thrombus or other calcified lesion in a manner likely to deform the thrombus or lesion with the distal portion of balloon 26. Thus, the high-voltage pulse generates one or a series of energy waves that propagate in a forward direction through the flowing medium within balloon 26 to apply a force or series of forces to the thrombus or lesion to fracture it.

[0024] After each firing and sparking between the electrodes 12 and 14 and the conductive tube 42, a small forward-facing surface of each of the electrodes 12 and 14 and the conductive tube 42 collapses at the closest point. Thus, the spark travels from one point to the nearest new point or across the smallest gap between these forward-facing surfaces. The spark therefore travels along the arcuate forward-facing surfaces of the electrodes 12 and 14 and the conductive tube 42 between the axial edges of the electrodes 12 and 14. Over time, the electrodes 12 and 14 and the conductive tube 42 wear not only along the arcuate forward-facing surfaces of the electrodes 12 and 14 and the conductive tube 42 but also along the axial direction. The useful life of the electrodes 12 and 14 and the conductive tube 42 can be based on an axial length of wear that is deemed acceptable.

[0025] FIG. 2 illustrates a catheter embodiment generally similar to FIG. 1 , but in which the distal end of balloon 126 is open, as indicated at 127, allowing a flowing medium to pass therethrough. In operation, fluid is supplied under pressure, causing axial flow (fluid flow indicated by the arrows) from the distal end of balloon 126 while sparks and energy waves are generated from the high-voltage pulse. Such fluid flow can aid in the fragmentation of thrombus or lesions. Fluid flow may be controlled to a minimal amount, such as a trickle, through open end 127. Alternatively, fluid flow may be controlled to compensate for impact on the thrombus or lesion. In this case, microbubbles in the fluid, such as those generated by the energy wave, can pass through open end 127 and interact with the thrombus or lesion. All other components and features are similar as those described with reference to FIGS. 1 , 3 , and 4 and are labeled with similar numbers, with one added to the hundredths.

[0026] FIG. 5 shows another example of a forward-facing electrode arrangement that generates an energy wave that propagates primarily in the axial or forward direction. In this example, the distal end, and therefore the forward-facing surface, of at least a portion of the conductive tube 42 extends axially beyond the forward-facing surface of the electrode 14. The axial distance that the conductive tube extends beyond the front surface of the electrodes 12 and / or 14 can vary depending on the desired directional control of the spark. The insulating layer 40 extends from the distal tip of the conductive tube 42 to the electrode 14 and may, but need not, be angled. The spark can be generated between the end of the conductive tube 42 and the ends of the electrodes 12 and 14, as described above. Alternatively, the spark can originate from the inner surface of the conductive tube slightly proximal to its distal end. While the spark is generated primarily in the forward and axial direction with this arrangement, the energy wave also propagates somewhat radially inward, as indicated by the wave pattern. It is contemplated that the entire circumference of the conductive tube 42 may extend distally forward relative to both electrodes 12 and 14 such that both sparks propagate similar wave patterns that are primarily forward and somewhat radially inward. It is also contemplated that the reverse arrangement may be performed. One or both of electrodes 12 and / or 14 may extend forward of the distal end of the conductive tube 42. In such an arrangement, one or both energy waves may propagate primarily forward or axially while also being somewhat radially outward. One energy wave may be primarily forward and radially inward combined with another energy wave that is primarily forward and radially outward. Additionally, any combination of forward energy waves as described above may be combined with other primarily forward and radially inward or outward energy waves.

[0027] 24 and 25 show yet another example of a forward-facing electrode arrangement, again generating energy waves that propagate primarily axially and forward. In this arrangement, the outer conductive tube 42' extends axially further distally than the single, inner tubular electrode 12'. The insulating layer 40' preferably extends to a similar extent as the electrode 12'. Similarly, the insulating layer 38' also preferably extends to a similar extent as the electrode 12', creating a lumen 30' for the guidewire. The single electrode 12' is shown as a conductive tube, concentric with the outer conductive tube 42' and electrically connected to either the positive or negative conductor from the high-voltage pulse generator 16, which in turn is electrically connected to the other of the positive or negative conductors from the high-voltage pulse generator 16. In this way, a spark S can be generated between the distal portion of the outer conductive tube 42' and the electrode 12'. As shown, the spark S and the generated cavitation bubbles are preferably generated at least partially (and more preferably entirely) within the distal end of the outer conducting tube 42', with the spark S generated between the end face of the electrode 12' and the inner wall of the outer conducting tube 42'. With this arrangement, cavitation bubbles (or microbubbles) are generated by the spark S within at least partially (and more preferably entirely) within the distal end of the conducting tube 42', which directionally guide or steer the associated energy as an energy wave exiting the opening of the outer conducting tube 42' and propagating toward the lesion. Surprisingly, this can be accomplished without destroying any catheter components for most applications. The spark S generates an energy wave, preferably at least partially within the distal end of the outer conducting tube 42', to propagate from the distal end of the outer conducting tube 42'. Furthermore, the cavitation of the microbubbles within the distal portion of the outer conducting tube 42' adds to the energy wave generated and propagating from the distal end of the conducting tube 42'. It is contemplated that multiple electrodes may be used in a similar arrangement, such as a modification of that shown in FIG.

[0028] It is contemplated that more than two such electrodes may be provided, and depending on the number of such electrodes, additional conductive tubes may be required to achieve a conductive sequence with controlled sparking in the defined gap.

[0029] FIG. 6 shows a cross-section of the electrode and conductive tube arrangement of FIGS. 1-4. The conductive tube 42 is shown as a seamless tube, also known as a hypotube, concentric with the guidewire tube 29, which defines the lumen 30 through which the guidewire 28 can pass. In this arrangement, the tube 29 provides insulation from one side of the electrodes 12 and 14, absent the first insulating layer 38 described above. The electrodes 12 and 14 are positioned within a common radial space and as arc segments relative to the outer surface of the tube 29. A second insulating layer 40 is shown between the conductive tube 42 and the outer curved surfaces of the electrodes 12 and 14, filling gaps 44 and 46 between the axially extending edges of the electrodes 12 and 14. Such an arrangement can be made in a number of ways, including providing the tube 29 and gluing, welding, or otherwise supporting the electrodes 12 and 14 to the outer surface of the tube 29. Such a subassembly may then be supported concentrically in place relative to the outer conductive tube 42, after which insulating material may be injected between the conductive tube 42, the outer surfaces of the respective electrodes 12 and 14, and the outer surface of the tube 29 within the gaps 44 and 46.

[0030] Figures 7 and 8 together illustrate a method for fabricating an electrode and conductive tube arrangement similar to those in Figures 1-4. As shown in Figure 7, electrodes 212 and 214 can be formed as a flexible circuit with an insulating layer 240. Flex or flexible circuits 227 can be made by well-known processes, which may include additive or subtractive material steps accompanied by masking steps and controlled deposition and / or etching steps. Flex circuits are well known for combining conductive metals, such as electrical traces, pads, or electrodes, with insulating layers and possibly other supporting materials, used for electrical interconnection of components. In this example, insulating layer 240 and electrodes 212 and 214 are formed as a flat flex circuit 227 subassembly, which can then be wrapped around a tube 229 defining a lumen 230, glued, welded, or otherwise attached to the tube 229, and then inserted into a conductive tube 242. The conductive tube 242 may or may not be glued, welded, or otherwise attached to the flex circuit 227. Electrodes 212 and 214, along with insulating layer 240, must be sufficiently flexible to be rolled as shown. Electrodes 212 and 214 are positioned flat along the surface of insulating layer 230 so that when wrapped around tube 229, they are positioned in diametrically opposed positions, preferably as shown in FIG. 8, as desired. The flat flex circuit extends from a first axially extending edge 231 (when rolled) to a second axially extending edge 233. A gap 235 is preferably created between ends 231 and 233 to ensure proper positioning of electrodes 212 and 214 when wrapped around tube 229 and to prevent them from engaging or interfering with one another.

[0031] 9 and 10 illustrate another method of fabricating such an electrode and conductive tube arrangement. As shown in FIG. 9, another flex circuit 327 is formed, including a conductive layer 342, an insulating layer 340, and electrodes 312 and 314 embedded in the insulating layer 340. In this case, not only must electrodes 312 and 314 and insulating layer 340 be flexible enough to be rolled, but so must the conductive layer 342. To form the electrode and conductive tube arrangement, the flex circuit 327 of FIG. 9 can be wrapped around the exterior of a tube 329 and secured in place, such as by gluing, welding, or otherwise. The flat flex circuit 327 extends from a first axially extending edge 331 (when rolled) to a second axially extending edge 333. A gap 335 is preferably created between ends 331 and 333 to ensure proper positioning of electrodes 312 and 314 when wrapped around tube 329 and to prevent them from engaging or interfering with one another.

[0032] 11 and 12 illustrate another method of fabricating such an alternative electrode and conductive tube arrangement. In this arrangement, a flex circuit 427 is fabricated and wrapped only partially around a tube 429 defining a lumen 430 and secured in place. Specifically, a flex circuit is formed comprising a conductive layer 442, an insulating layer 440, and electrodes 412 and 414. Again, in this arrangement, electrodes 412 and 414 and insulating layer 440 must be flexible enough to be rolled along with conductive layer 442. To form the electrode and conductive tube arrangement, flex circuit 427 of FIG. 11 may be wrapped partially around the exterior surface of tube 429 and secured in place, such as by gluing, welding, or another method. Flat flex circuit 427 extends from a first axially extending edge 431 (when rolled) to a second axially extending edge 433. A gap 435 is preferably created between ends 431 and 433 to ensure proper positioning of electrodes 412 and 414 and to prevent them from engaging or interfering with one another when wrapped partially around tube 429. Such an arrangement can reduce material requirements while effectively placing electrodes 412 and 414, preferably diametrically opposed, in operative position relative to conductive layer 442.

[0033] 13 and 14 illustrate another advantageous fabrication of electrode and conductive tube arrangements from a flex circuit. As shown, flex circuit 527 can be made with an insulating layer 540 on which electrical traces 518 and 520 can be formed, as described above. Electrical traces 518 and 520 extend axially and can terminate at or near the distal end of insulating layer 540 as pads, depicted as rectangular, on which electrodes 512 and 514 can be formed. Flex circuit 527 can be attached to conductive material layer 542 by any known bonding technique. When rolled, electrical traces 518 and 520 extend axially of the tube formed by the rolled conductive material 542. Flex circuit 527 and conductive material 542 can be wrapped around the exterior of an insulating tube (not shown, but similar to tube 29) and also bonded in place. Electrical traces 518 and 520 may advantageously extend beyond the proximal end of insulating layer 540 and / or conductive material 542, possibly all the way to hub 24 and over its outer surface. With such an arrangement, there is no need to make any electrical connections within the balloon or anywhere along the catheter. Not making electrical connections within the balloon allows for a smaller profile of the balloon and electrode / conductive tubing within the patient's body.

[0034] 14 shows sparking between the distal end of each electrode 512 and 514 and the distal end of conductive material 542. The sparking can be controlled to be more radial or axial depending on the relative extension of electrodes 512 and 514, conductive material 542, and insulating material 540, as described above.

[0035] Other flex circuits are contemplated that allow the flex circuit to more easily extend the length of the catheter to the electrodes, preferably with minimal impact on catheter stiffness to allow for desired IVL balloon positioning within the patient's vasculature. As noted above, two conductors are preferably capable of electrically connecting any number of emitters, each with two electrodes, in series. Thus, the flex circuit design can include two electrical traces on a flexible insulating layer that extend from the high-voltage pulse generator to one of more emitters on the IVL balloon.

[0036] The following embodiments of flex circuits according to the present invention are directed to providing a pair of electrodes at the distal end of the flex circuit, such as may be used with a forward-facing IVL emitter, as described above. However, it is contemplated that flex circuits according to the present invention may instead be used with designs other than axial firing, in which the distal ends of the flex circuit conductors may comprise electrodes or may provide bond pads or other electrical connections or connectors that can connect to any other electrode design. Such bond pads may be used in other axial firing emitter designs, radial firing emitter designs, or otherwise. Thus, in the following description, the term "electrode" may be read as actually comprising electrodes, such as electrodes according to an IVL device, or bond pads or other electrical connections or connectors that can connect to electrodes of an IVL device.

[0037] 15 and 16 show a flex circuit 600 intended to be spirally wound along the length of a catheter as part of an IVL device. A distal pad 602 is shown including an extension 604 extending proximally therefrom at an angle to form a spiral winding. This angle may be based on the width of the flex circuit 604 so that the windings are preferably wrapped within and along the distance of the catheter (not shown) without overlapping. FIG. 15 shows the first winding located near the distal end of the flex circuit 604 and the distal pad 602. The distal pad 602 and extension 604 can include multiple (preferably two) electrical traces and electrodes or pads, as may be manufactured by any flex circuit production process, as described above or otherwise developed (discussed in more detail below). Such electrical traces can extend to the distal end of the flex circuit to terminate at a proximal pad 606 for electrical connection to a high-voltage pulse generator, also as described above. It is contemplated that a control system or module may also be provided in this connection with the high voltage pulse generator for controlling the high voltage pulses for the IVL process and the controlled operation of the IVL process.

[0038] Figure 17 shows a similar concept to that of Figures 15 and 16, but with multiple (preferably two) extensions 603 and 605 extending at similar angles from distal pad 601. Additionally, these same components are shown in a rolled state at the beginning of multiple turns of distal pad 601 and extensions 603 and 605, which extend within and along the length of the IVL catheter.

[0039] 18 and 19 show the flex circuit 600 of FIGS. 15 and 16 including electrical traces 608 and 610 extending from proximal electrical bond pads 612 and 614 on the proximal pad 606 to distal electrode or bond pads 616 and 618 on the distal pad 602. Thus, electrical conductors, including bond pads 612 and 614, traces 608 and 610, and electrode or bond pads 616 and 618, respectively, extend from the proximal pad 606 to the distal pad 602. Additionally, an insulating layer, including the proximal pad 606, extension 604, and distal pad 602, is provided along with the electrical conductors. Preferably, the traces 608 and 610 are spaced apart so as not to electrically interfere with each other and to prevent electrical breakdown between them during a high voltage pulse or any time period of expected IVL system usage. Preferably, the proximal and distal pads 606 and 602 may be wider than the extension 604 to accommodate larger bond pads or electrodes, so that the bond pads 612 and 614 and the electrodes or bond pads 616 and 618 may be appropriately spaced from one another when provided on the proximal and distal pads 606 and 602.

[0040] 20 and 21 illustrate another embodiment of a flex circuit 700 in accordance with the present invention. Similar to flex circuit 600, an insulating layer can include a proximal pad 706, an extension 704, and a distal pad 702. In this case, a first electrical trace 710 can extend along one side (the front side) of the insulating layer, and a second electrical trace 708 can extend along the other side (the back side) of the insulating layer. To accomplish this, a bond pad 712 electrically formed with the trace 710, which is further electrically formed with a distal electrode or bond pad 716, can be provided on the first side of the proximal pad 706. In that case, the electrical trace 708 can extend along the second side and be formed with or connected to a proximal bond pad 714 and a distal electrode or bond pad 718. The proximal and distal bond pads or electrodes 714 and 718 can be provided on either the second side of the insulating layer or the first side of the insulating layer. In the latter case, electrical vias can connect one or both of the proximal bond pad 714 and the distal electrode or bond pad 718 to the trace 708. If electrodes are provided at 716 and 718, for example in the case of a forward-firing configuration, it is preferable to have both electrodes on the same side of the distal pad 702. Figures 20 and 21 show the top (blue) trace portion of trace 708 as it runs along only a portion of each proximal and distal pad 706 and 702 and is connected by an electrical via to the remainder of the trace 708 that extends along the second side of the insulator. The advantage of this design is better insulation between trace 708 and trace 710 while allowing for a narrower extension 704 of the flex circuit for easier wrapping.

[0041] 22 and 23 illustrate yet another flex circuit according to the present invention. Flex circuit 800 is similar to flex circuit 600 of FIGS. 18 and 19, but lacks a distal pad to accommodate the placement of electrode or bond pads 816 and 818. In this embodiment, traces 808 and 810 extend side-by-side on one side of the insulating layer along extension 804 between proximal pad 806 and the distal end. Traces 806 and 810 are further spaced apart as they extend along extension 804 of flex circuit 800 to provide better isolation of the traces from each other during high-voltage pulsing. Making extension 804 wider provides sufficient space to space both traces 808 and 810 farther apart. However, this wider extension 804 may make it more difficult to form the spiral windings of flex circuit 800 along which it is positioned within an IVL catheter. In this case, the flex circuit 800 may simply extend along the IVL catheter without being wrapped. As shown in Figure 23, the electrodes may be provided at 816 and 818 spaced apart similarly to the spacing of the traces 808 and 810, but this is not required.

[0042] It will be understood that assemblies or subassemblies such as the flex circuits described above may be fabricated using methods other than flex circuit technology, for example, by fabricating each element separately and then assembling them. Other arrangements including two or more electrodes and any number of conductive layers or tubes are also contemplated. While an arrangement of electrodes and conductive tubes or layers preferably results in energy wave propagation primarily in a forward or axial direction, it is contemplated that an arrangement can result in energy wave propagation that is more radial than axial, but preferably includes at least an axial component.

[0043] It will also be appreciated that the arrangement of the electrodes and conductive tubes need not be limited to a cylindrical shape. The electrodes are preferably shaped similarly to spaced apart sections of conductive material, preferably tubes or partial tubes, which may have a circular cross section or a portion thereof or other shapes, such as square, rectangular, hexagonal, etc. As discussed above, controlling the spacing of the electrodes relative to similarly shaped conductive walls ensures that the spark will jump across a similar gap, and over time, as the electrodes wear with the conductive walls, the spark will move from side to side along the forward-facing edge. Preferably, the tubes, or portions thereof, can electrically connect the spark gaps formed by the spacing in series. [Explanation of symbols]

[0044] 10 Catheter System 12 electrodes 12' electrode 14 electrodes 16 High voltage pulse generator 18 Electrode Wires 20 electrode wires 22 Catheter 24 Hub 26 Balloon 28 Guidewire 29 Guidewire tube 30 lumens 30' lumens 32 Access Entrance 34 Electrical entrance 36 Expansion inlet 38 First insulating layer 38' Insulation layer 40 Second insulating layer 40' insulation layer 42 Conductive tube 42' Conductive Tube 44 Gap 46 Gap 48 Controller 126 Balloon 127 Distal End 212 Electrode 214 Electrode 227 Flexible circuits, flex circuits 229 tube 230 lumens 231 En 233 En 235 Gap 240 Insulating Layer 242 Conductive Tube 312 Electrode 314 Electrode 327 Flex Circuit 329 Tube 331 Edge, edge 333 Edge, edge 335 Gap 340 Insulating Layer 342 Conductive Layer 412 Electrode 414 Electrode 427 Flex Circuit 429 Tube 430 lumens 431 Edge, edge 433 Edge, edge 435 Gap 440 Insulation Layer 442 Conductive Layer 512 Electrode 514 Electrode 518 Electrical Trace 520 Electrical Trace 527 Flex Circuit 540 Insulating Layer 542 conductive material layer 600 flex circuit 601 Distal Pad 602 Distal Pad 603 Extension 604 Extension 605 Extension 606 Proximal Pad 608 Electrical Trace 610 Electrical Trace 612 Proximal Electrical Bond Pad 614 Proximal Electrical Bond Pad 616 Distal electrode, bond pad 618 Distal electrode, bond pad 700 flex circuit 702 Distal Pad 704 Extension 706 Proximal Pad 708 Second Electrical Trace 710 First Electrical Trace 712 Proximal Bond Pad 714 Proximal Bond Pad 716 Distal Electrode, Distal Bond Pad 718 Distal Electrode, Distal Bond Pad 800 flex circuit 804 Extension 806 Proximal Pad 808 Trace 810 Trace 816 Electrode, Bond Pad 818 Electrode, Bond Pad S Spark

Claims

1. 1. An intravascular lithotripsy (IVL) system used to deliver an energy wave as a force to a lesion within the vasculature, comprising: a catheter extending from a proximal end to a distal end, the catheter including an electrode and conductive tube arrangement at the distal end, the electrode disposed within the conductive tube and spaced from the conductive tube by an insulating layer, the electrode having a forward-facing electrode distal end, the conductive tube further including a forward-facing conductive tube distal end, the forward-facing conductive tube distal end being radially spaced from the distal end of the electrode to form at least one spark gap between the catheter and the forward-facing electrode distal end; An intravascular lithotripsy (IVL) system comprising:

2. 2. The IVL system of claim 1, wherein a plurality of electrodes are provided inside the conductive tube and spaced apart from the conductive tube by the insulating layer, the electrodes being electrically isolated from one another to form a plurality of gaps with the conductive tube and capable of being energized in series to produce a plurality of sparks.

3. 3. The IVL system of claim 2, wherein the electrode is an arc segment of conductive material coaxial with the conductive tube so as to be similarly spaced from the conductive tube, and the distal end of the electrode and the distal end of the conductive tube extend to similar axial lengths so as to terminate adjacent one another.

4. 5. The IVL system of claim 4, wherein the insulating layer extends similarly to terminate near the distal end of the electrode and the conductive tube, and a guidewire insulating layer is provided inside the electrode to define a guidewire lumen.

5. 2. The IVL system of claim 1, wherein the distal end of the conductive tube extends axially further distally than the distal end of the electrode such that the distal end of the electrode is entirely positioned proximally within and spaced apart from the distal end of the conductive tube.

6. 6. The IVL system of claim 5, wherein the insulating layer extends to terminate adjacent the distal end of the electrode such that a spark can be generated between the distal end of the electrode and an inner sidewall of the conductive tube.

7. 10. The IVL system of claim 1, wherein the electrodes and the insulating layer comprise a flex circuit that can be rolled into a cylindrical shape and inserted into the conductive tube.

8. The IVL system of claim 7 , wherein the conductive tube is further formed as part of the flex circuit.

9. 1. A method of using an intravascular lithotripsy (IVL) system for a lesion within the vasculature, comprising: inserting an IVL catheter having a balloon, a conductive tube, and at least one electrode into the patient's vasculature to a location of a lesion in the vasculature beyond a distal end of the balloon, the IVL catheter having a distal end, the electrode having a distal end, the conductive tube also having a distal end, and a spark gap formed between the distal end of the electrode and the distal end of the conductive tube; electrically connecting the conductive tube and the electrode to a high voltage pulse generator; delivering an at least partially electrically conductive fluid to the balloon; generating a high voltage pulse with the high voltage pulse generator, thereby causing a spark in the spark gap along with a cavitation bubble such that a forward-directed energy wave propagates through the fluid in the balloon and from the balloon to the lesion; A method comprising:

10. 10. The IVL system of claim 9, wherein a plurality of electrodes are disposed within the conductive tube and spaced apart from the conductive tube by the insulating layer, the electrodes being electrically isolated from one another to form a plurality of spark gaps with the conductive tube, the method further comprising energizing the electrodes in series to induce a plurality of sparks in the plurality of spark gaps.

11. 11. The IVL system of claim 10, wherein the distal end of the electrode and the distal end of the conductive tube extend a similar axial distance and terminate adjacent to one another with the insulating layer therebetween so that the spark can be generated from the distal end of the electrode and the distal end of the conductive tube.

12. 10. The IVL system of claim 9, wherein the distal end of the conductive tube extends axially more distally than the distal end of the electrode such that the distal end of the electrode is positioned entirely proximally within and spaced apart from the distal end of the conductive tube, and the method further comprises generating a spark between the distal end of the electrode and an inner sidewall of the conductive tube, thereby generating a cavitation bubble at least partially within the distal end of the conductive tube such that an energy wave can be directed from the open distal end of the conductive tube in a desired forward direction.

13. 13. The IVL system of claim 12, wherein the distal end of the conductive tube extends axially sufficiently beyond the distal end of the electrode such that the cavitation bubble is formed entirely within the distal end of the conductive tube.

14. 1. An intravascular lithotripsy (IVL) system used to deliver an energy wave as a force to a lesion within the vasculature, comprising: A catheter extending from a proximal end to a distal end, the catheter including an arrangement of electrodes and conductive tubing at the distal end of the catheter with a plurality of electrodes disposed adjacent the distal end of the catheter, and further including a flex circuit extending from the proximal end of the catheter to the electrodes for electrically connecting the electrodes to a high voltage pulse generator at the proximal end of the flex circuit, the flex circuit being spirally wound within the catheter along at least a portion of the catheter. An intravascular lithotripsy (IVL) system comprising:

15. 15. The IVL system of claim 14, wherein the electrodes are formed on a flex pad portion at a distal end of the flex circuit, an extension of the flex circuit extending proximally from the flex pad within the catheter, the extension of the flex circuit further having a plurality of conductive traces extending along the extension.

16. 16. The IVL system of claim 15, wherein the extension extends from the flex pad at an angle to facilitate spiral winding of the extension along the catheter within the catheter, and thus the traces are positioned at the angle relative to the placement of the electrodes.

17. 16. The IVL system of claim 15, wherein a plurality of traces are provided along one side of the extension of the flex circuit.

18. 16. The IVL system of claim 15, wherein at least one trace extends along one side of the extension of the flex circuit and at least one other trace extends along a second side of the extension of the flex circuit.

Images